JPWO2010116803A1 - Liquid crystal display - Google Patents

Abstract

An object of the present invention is to provide a liquid crystal display device that expands the viewing angle, improves the front contrast, and prevents color shift when viewed from an oblique direction. In the liquid crystal display device 1 of the present invention, the first polarizer 2, the first optical compensation layer 3, the liquid crystal cell 4, the second optical compensation layer 5, and the second polarizer 6 are arranged in this order. The first and second optical compensation layers 3 and 5 satisfy the following formulas (1) to (3), and the liquid crystal molecules in the liquid crystal cell 4 are aligned in the thickness direction of the liquid crystal cell 4 during black display. To do. nx1> nz1> ny1 (1) nx2 ≧ ny2> nz2 (2) DSP (Ro1) <1 <DSP (Rth2) (3)

Description

  The present invention relates to a liquid crystal display device.

  Conventionally, a liquid crystal display device is composed of a liquid crystal cell in which a transparent electrode, a liquid crystal layer, a color filter, etc. are sandwiched between glass plates, and two polarizing plates provided on both sides thereof. A polarizer (also referred to as a polarizing film or a polarizing film) is sandwiched between two optical films (a polarizing plate protective film or an optical compensation film). In such a liquid crystal display device, various methods such as a VA (Virtual Alignment) mode, an IPS (In-Place-Switching) mode, and a TN (Twisted Nematic) mode have been developed as a liquid crystal driving method. Among them, the VA mode is frequently used for a large-screen liquid crystal TV because it has a high display speed and excellent front contrast.

  Here, in the VA mode liquid crystal display device, when the voltage is not applied, the major axis of the liquid crystal material is aligned perpendicular to the substrate surface, so that almost complete black display is obtained when viewed from the direction perpendicular to the substrate. It is possible to achieve high contrast.

  On the other hand, when the liquid crystal material is vertically aligned, there is a problem that, when viewed from an oblique direction, a black display is colored due to light leakage or the contrast is lowered. There are mainly two causes for this problem. One reason is that the liquid crystal layer itself used in the liquid crystal cell has a phase difference (also referred to as retardation) in the thickness direction. Also, for one thing, the two polarizers sandwiching the liquid crystal cell are arranged in crossed Nicols (so that the transmission axes are orthogonal), and the transmission axes of these polarizers are orthogonal when viewed from the front, This is due to the fact that when viewed from an angle, it appears to deviate from 90 degrees.

  For such problems, the refractive indexes nx, ny, and nz (where nx is the refractive index in the slow axis direction in the film surface, ny is the refractive index in the fast axis direction in the film surface, and nz is the thickness direction). A technique has been proposed in which two biaxial films having a refractive index of nx> ny> nz are disposed on both sides of a liquid crystal cell to increase the viewing angle. However, with this configuration, the use of two films of the same type has a cost merit, but a sufficient viewing angle expansion effect could not be obtained.

Therefore, in recent years, a technology has been developed to further increase the viewing angle by arranging a film called negative C plate with nx = ny> nz and a film called Z plate with nx>nz> ny on the polarizing plate. (For example, see Patent Documents 1 and 2.)
However, although the techniques described in Patent Documents 1 and 2 can widen the viewing angle, other optical performances that have been especially emphasized in recent years, specifically, front contrast and color shift when viewed from an oblique direction. Is not considered at all, and further improvement is desired.

JP 2000-39610 A JP 2007-148016 A

  An object of the present invention is to provide a liquid crystal display device capable of expanding a viewing angle, improving front contrast, and preventing color shift when viewed from an oblique direction.

  As a result of diligent research by the present inventors on the above-mentioned problems, since the conventional Z plate is produced by heat shrinkage of polycarbonate, cycloolefin, etc., only those having positive wavelength dispersion (DSP> 1) can be produced. However, it was found that a reverse chromatic dispersion Z-plate can be prepared by using reverse chromatic dispersion (DSP <1) cellulose. And in the said patent document 2, although it is described that it is preferable that the C plate is reverse wavelength dispersion and the Z plate is positive wavelength dispersion regarding the wavelength dispersion value DSP, It has been found that when a liquid crystal cell is sandwiched between a dispersion Z plate and a positive wavelength dispersion C plate, the color shift when viewed from an oblique direction can be reduced, and the viewing angle and front contrast can be improved. Furthermore, even when using a Z plate with reverse wavelength dispersion, when this Z plate is composed of a single layer, the retardation value Ro is very large, ie, Ro≈275, in order to produce a viewing angle expansion effect. Since it is necessary to apply a phase difference to the Z plate, the Z plate amplifies the effect of slight optical axis variations in the surface, causing a decrease in front contrast. When a laminated structure of a film and a liquid crystal layer functioning as a positive C plate is used, a viewing angle widening effect can be achieved by giving a retardation value Ro = 50 to 100 of a half or less phase difference to the entire Z plate. It has been found that it is possible to achieve a high degree of contrast, and that it is possible to reduce unevenness in phase difference and maintain a high front contrast.

In view of the above points, according to the first aspect of the present invention, in the liquid crystal display device,
Having at least a first polarizer, a first optical compensation layer, a liquid crystal cell, a second optical compensation layer, and a second polarizer in this order;
The first and second optical compensation layers satisfy the following formulas (1) to (3),
The liquid crystal molecules in the liquid crystal cell are aligned in the thickness direction of the liquid crystal cell during black display.

nx1>nz1> ny1 (1)
nx2 ≧ ny2> nz2 (2)
DSP (Ro1) <1 <DSP (Rth2) (3)
(Where nx1 is the refractive index in the slow axis direction in the plane of the first optical compensation layer, ny1 is the refractive index in the fast axis direction in the plane of the first optical compensation layer, and nz1 is the first refractive index in the first optical compensation layer) Nx2 represents the refractive index in the slow axis direction in the plane of the second optical compensation layer, and ny2 represents the phase advance in the plane of the second optical compensation layer. The refractive index in the axial direction, nz2 represents the refractive index in the thickness direction of the second optical compensation layer, and Ro1 represents the in-plane letter of the first optical compensation layer represented by the following formula (8-1). Rth2 represents the retardation value in the thickness direction of the second optical compensation layer represented by the following formula (9-2): DSP (Ro1) represents the first optical compensation layer. The chromatic dispersion value of the in-plane retardation value Ro1, and the first light measured at a wavelength of 480 nm. A value obtained by dividing the in-plane retardation value Ro1 of the compensation layer by the in-plane retardation value Ro1 measured at a wavelength of 630 nm DSP (Rth2) is the retardation value Rth2 in the thickness direction of the second optical compensation layer. The chromatic dispersion value is a value obtained by dividing the retardation value Rth2 of the second optical compensation layer measured at a wavelength of 480 nm by the retardation value Rth2 measured at a wavelength of 630 nm.

Ro1 = (nx1-ny1) × d1 (8-1)
Rth2 = {(nx2 + ny2) / 2-nz2} × d2) (9-2)
Here, d1 represents the thickness (nm) of the first optical compensation layer, d2 represents the thickness (nm) of the second optical compensation layer, and Ro1 and Rth2 are values measured at a wavelength of 590 nm, respectively. )
In the liquid crystal display device of the present invention,
The first optical compensation layer preferably includes a cellulose resin layer.

In the liquid crystal display device of the present invention,
The first optical compensation layer satisfies the following formulas (4) and (5),
The second optical compensation layer preferably satisfies the following formulas (6) and (7).

Ro1 = 50-100 [nm] (4)
| Rth1 | = 0 to 20 [nm] (5)
Ro2 = 0 to 20 [nm] (6)
Rth2 = 200 to 350 [nm] (7)
(However, Rth1 represents the retardation value in the thickness direction of the first optical compensation layer represented by the following formula (9-1), and Ro2 represents the first formula represented by the following formula (8-2). 2 represents the in-plane retardation value of the optical compensation layer, and Ro2 and Rth1 are values measured at a wavelength of 590 nm, respectively.

Ro2 = (nx2-ny2) × d2 (8-2)
Rth1 = {(nx1 + ny1) / 2−nz1} × d1) (9-1)
In the liquid crystal display device of the present invention,
The first optical compensation layer includes at least a cellulose resin layer and a liquid crystal layer,
The cellulose resin layer is
Disposed on the first polarizer side of the liquid crystal layer;
It is preferable that the in-plane phase difference is present and the slow axis is orthogonal to the absorption axis of the first polarizer.

In the liquid crystal display device of the present invention,
The first optical compensation layer includes at least a cellulose resin layer and a liquid crystal layer,
The cellulose resin layer is
It is disposed on the liquid crystal cell side than the liquid crystal layer,
The phase difference may be in-plane and the slow axis may be parallel to the absorption axis of the first polarizer.

In the liquid crystal display device of the present invention,
The second optical compensation layer includes:
It preferably comprises a cellulose resin layer containing a DSP value increasing agent.

  According to the present invention, the liquid crystal molecules in the liquid crystal cell are aligned in the thickness direction of the liquid crystal cell during black display, and the first and second optical compensation layers are nx1> nz1> ny1, nx2 ≧ ny2> nz2, DSP. Since (Ro1) <1 <DSP (Rth2) is satisfied, the viewing angle can be enlarged, the front contrast can be improved, and color shift when viewed from an oblique direction can be prevented (see the embodiment).

It is a conceptual diagram which shows schematic structure of the liquid crystal display device which concerns on this invention. It is a conceptual diagram which shows schematic structure of the modification of the liquid crystal display device which concerns on this invention.

Embodiments of the present invention will be described below with reference to the drawings.
[First Embodiment]
FIG. 1A is a conceptual diagram showing an example of a liquid crystal display device 1 according to the first embodiment.

As shown in this figure, the liquid crystal display device 1 is a VA mode liquid crystal display device, and includes a first polarizer 2, a first optical compensation layer 3, and a liquid crystal cell from the viewing side toward the backlight side. 4, the second optical compensation layer 5, and the second polarizer 6 are stacked in this order. More specifically, the first and second polarizers 2 and 6 and the first optical compensation layer 3 include an absorption axis 2J of the first polarizer 2 and a slow axis 3J of the first optical compensation layer 3. Are orthogonal, the absorption axis 2J of the first polarizer 2 and the absorption axis 6J of the second polarizer 6 are orthogonal, and the slow axis 3J of the first optical compensation layer 3 and the second polarizer 6 are arranged so as to be parallel to the absorption axis 6J. In FIG. 1, the backlight is illustrated as the lower side in the drawing, but may be the upper side. Further, 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 °. Further, in this specification, the slow axis means a direction in which the refractive index is maximized.
(1) Liquid Crystal Cell Among these, the liquid crystal cell 4 is formed by sandwiching the liquid crystal layer 40 between two glass substrates 41.

  The liquid crystal layer 40 is composed of rod-like liquid crystal molecules, and each liquid crystal molecule is aligned in the thickness direction of the liquid crystal cell 4 during black display. Here, the alignment of the liquid crystal molecules in the thickness direction of the liquid crystal cell 4 during black display is synonymous with the alignment in the vertical direction of the glass substrate 41, which means that the liquid crystal cell 4 is in the VA mode. The retardation value Rth of the rod-like liquid crystal in such a VA mode liquid crystal cell 4 is negative, and its wavelength dispersion is positive.

  As the liquid crystal material of the liquid crystal layer 40, a nematic liquid crystal material having a negative dielectric anisotropy, a refractive index anisotropy Δn = 0.0815, and a dielectric anisotropy Δε = −4.5 can be used. . The thickness d of the liquid crystal layer 40 is not particularly limited, but can be set to about 3.5 μm when the above-described nematic liquid crystal material is used. However, since the brightness at the time of white display changes depending on the magnitude of the product Δn · d of the thickness d and the refractive index anisotropy Δn, Δn · d is 0.2 to 0.2 in order to obtain the maximum brightness. It is preferable to set it in the range of 0.5 μm.

  In a VA mode liquid crystal display device, the addition of a chiral material generally used in a TN mode liquid crystal display device is rarely used to degrade dynamic response characteristics, but to reduce alignment defects. You may add to.

  In addition, the multi-domain structure is advantageous for adjusting the alignment of the liquid crystal molecules in the boundary region between the domains.

Here, the multi-domain structure refers to a structure in which one pixel of a liquid crystal display device is divided into a plurality of regions. For example, in the VA mode, since the liquid crystal molecules are tilted when displaying white, the magnitude of birefringence of the liquid crystal molecules when viewed from an oblique direction is different between the tilt direction and the opposite direction, resulting in differences in luminance and color tone. However, a multi-domain structure is preferable because the viewing angle characteristics of luminance and color tone are improved. Specifically, each pixel is composed of two or more (preferably 4 or 8) regions in which the initial alignment state of the liquid crystal molecules is different from each other, and averaging is performed. Can be reduced. Further, the same effect can be obtained even if each pixel is constituted by two or more different regions where the alignment direction of liquid crystal molecules continuously changes in a voltage application state. To form multiple regions with different alignment directions of liquid crystal molecules within one pixel, for example, use methods such as providing slits on electrodes, providing protrusions, changing the electric field direction, or biasing the electric field density. can do. In order to obtain a uniform viewing angle in all directions, the number of divisions may be increased. However, a substantially uniform viewing angle can be obtained by using four or more divisions. In particular, it is preferable that the polarizing plate absorption axis can be set at an arbitrary angle when dividing into eight. At the region boundary of each domain, the liquid crystal molecules tend to be difficult to respond. In the normally black mode such as the VA mode, since black display is maintained, a decrease in luminance becomes a problem. Therefore, it is possible to reduce the boundary region between domains by adding a chiral agent to the liquid crystal material. On the other hand, since the white display state is maintained in the normally white mode, the front contrast is lowered. Therefore, a light shielding layer such as a black matrix covering the region may be provided.
(2) First and second polarizers The first and second polarizers 2 and 6 are optical elements that allow only light having a polarization plane in a certain direction to pass through, and are manufactured by a conventionally known general method. ing. Here, as a typical polarizer currently known, there is a polyvinyl alcohol polarizing film, and more specifically, a polyvinyl alcohol film dyed with iodine and a dichroic dye dyed. There is. As such a polarizer, a polyvinyl alcohol aqueous solution is formed into a film and dyed by uniaxial stretching or dyed or uniaxially stretched and then preferably subjected to a durability treatment with a boron compound. ing.

  Usually, a polarizer is sandwiched on both sides by a TAC film or the like as a protective layer. It is preferable that the back surface side of the TAC film is subjected to alkali saponification treatment and bonded to at least one surface of a polarizer produced by immersion and stretching in the iodine solution using a completely saponified polyvinyl alcohol aqueous solution. The TAC film may be used for the other surface, or a film having another polarizing plate protecting function may be used. Commercially available cellulose ester films (for example, Konica Minoltak KC8UX, KC4UX, KC5UX, KC8UCR3, KC8UCR4, KC8UCR5, KC4UE, KC8UY, KC4UY, KC12UR, KC4FR, and the like, also manufactured by Konica Minolta Opto, Inc., preferably used).

In the configuration of the present invention, the first and second polarizers 2 and 6 are each sandwiched between two TAC films and bonded to the first and second optical compensation layers 3 and 5 through an adhesive layer. However, from the viewpoints of thinning, reduction of members, and optical compensation, it is preferable that the optical compensation layers 3 and 5 are bonded directly without using a TAC film.
(3) First and second optical compensation layers The first and second optical compensation layers 3 and 5 satisfy the following formulas (1) to (3), and are preferably film-like from the viewpoint of handling ( Hereinafter, also referred to as optical compensation films 3 and 5). More preferably, the following expressions (4) to (7) are satisfied.

nx1>nz1> ny1 (1)
nx2 ≧ ny2> nz2 (2)
DSP (Ro1) <1 <DSP (Rth2) (3)
Ro1 = 50-100 [nm] (4)
| Rth1 | = 0 to 20 [nm] (5)
Ro2 = 0 to 20 [nm] (6)
Rth2 = 200 to 350 [nm] (7)
Here, “nx” is the refractive index in the slow axis direction in the plane of the optical compensation layer, “ny” is the refractive index in the fast axis direction in the plane of the optical compensation layer, and “nz” is the thickness of the optical compensation layer. Respective refractive indexes are represented, and “Ro” and “Rth” are retardation values obtained by the following formulas (8) and (9). In each formula, the subscripts “1” and “2” indicate values for the first optical compensation layer 3 and the second optical compensation layer 5. These values are values measured at a wavelength of 590 nm. Moreover, the value of each refractive index can be calculated | required in 23 degreeC and 55% RH environment, for example using KOBRA-21ADH (Oji Scientific Instruments) and Axoscan (made by AXOMETRICS).

Ro = (nx−ny) × d (8)
Rth = {(nx + ny) / 2−nz} × d) (9)
According to these formulas (8) and (9), when the refractive index is nx>nz> ny, Ro> 0 and −Ro / 2 <Rth <Ro / 2 are satisfied, and conversely Ro It can be seen that nx>nz> ny is satisfied when> 0 and −Ro / 2 <Rth <Ro / 2. When nx ≧ ny> nz, Ro ≧ 0 and Rth> Ro / 2 are satisfied. Conversely, when Ro ≧ 0 and Rth> Ro / 2, nx ≧ ny> nz is satisfied. I understand.

In addition, “DSP (Ro1)” in the above formula (3) is the chromatic dispersion value of the in-plane retardation of the first optical compensation layer 3, and specifically, the first optical value measured at a wavelength of 480 nm. This is a value obtained by dividing the retardation value Ro of the compensation layer 3 by the retardation value Ro measured at a wavelength of 630 nm. “DSP (Rth2)” is the chromatic dispersion value of the thickness direction retardation of the second optical compensation layer 5, and specifically, the retardation value Rth of the second optical compensation layer 5 measured at a wavelength of 480 nm. Is divided by the retardation value Rth measured at a wavelength of 630 nm. These chromatic dispersion values DSP are DSP> 1 in the case of positive chromatic dispersion, and DSP <1 in the case of negative (reverse) chromatic dispersion.
(3.1) First Optical Compensation Layer The first optical compensation layer 3 satisfies nx1>nz1> ny1 and DSP (Ro1) <1 as described above, and is a so-called reverse wavelength dispersion Z plate. ing. The first optical compensation layer 3 preferably has an in-plane retardation value Ro1 of 50 to 100 nm, and an absolute value of the retardation value Rth1 in the thickness direction of 0 nm to 20 nm.

  Here, in order to impart the performance of nx1> nz1> ny1 and DSP (Ro1) <1 to the first optical compensation layer 3, as will be described later, a shrinkable film is added to the cellulose resin film having reverse wavelength dispersion. It is preferable to paste together and shrink while stretching. It is also preferable to use a biaxial film obtained by stretching this resin as a base material, apply a liquid crystal layer thereon, and dry and fix it. These will be described in detail together with the description of FIG.

Although the form of the first optical compensation layer 3 is not limited, it is preferably a film. The thickness d of the film is preferably 40 to 100 μm, more preferably 40 to 70 μm.
(3.1.1) Cellulose Resin Used for First Optical Compensation Layer The cellulose ester used for the first optical compensation layer 3 is not particularly limited, but preferably has 2 to 22 carbon atoms as the cellulose ester. A carboxylic acid ester having a carbon number of 6 or less, particularly preferably a lower fatty acid ester having 6 or less carbon atoms. Moreover, you may use the cellulose-ester resin which graft-polymerized (epsilon) -caprolactone to the cellulose-ester resin as disclosed by Unexamined-Japanese-Patent No. 2008-197561.

  The acyl group bonded to the hydroxyl group may be linear or branched or may form a ring. Furthermore, another substituent may be substituted. When the degree of substitution is the same, birefringence decreases when the number of carbon atoms is large, and therefore, the number of carbon atoms is preferably selected from acyl groups having 2 to 6 carbon atoms. The cellulose ester preferably has 2 to 4 carbon atoms, more preferably 2 to 3 carbon atoms.

  Specifically, the cellulose ester includes cellulose acetate propionate, cellulose acetate butyrate, or a mixed fatty acid ester of cellulose to which a propionate group or a butyrate group is bonded in addition to an acetyl group such as cellulose acetate propionate butyrate. Can be used.

  The butyryl group forming butyrate may be linear or branched. As the cellulose ester preferably used in the present invention, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, and cellulose acetate phthalate are particularly preferably used.

  Preferred cellulose esters other than cellulose acetate phthalate for the present invention preferably satisfy the following formulas (101) and (102).

Formula (101) 2.0 ≦ X + Y ≦ 3.0
Formula (102) 0 ≦ Y ≦ 1.5
In the formula, X is the degree of substitution of the acetyl group, and Y is the degree of substitution of the propionyl group or butyryl group, or a mixture thereof.

  Further, in order to obtain optical characteristics that meet the purpose, resins having different degrees of substitution may be mixed and used. The mixing ratio is preferably 10:90 to 90:10 (mass ratio).

  Of these, cellulose acetate propionate is particularly preferably used. In cellulose acetate propionate, 1.0 ≦ X ≦ 2.5, preferably 0.1 ≦ Y ≦ 1.5, and 2.0 ≦ X + Y ≦ 3.0. The measuring method of the substitution degree of an acyl group can be measured according to ASTM-D817-96.

  The number average molecular weight of the cellulose ester used in the present invention is preferably in the range of 60,000 to 300,000 because the mechanical strength of the resulting film is strong. Furthermore, the thing of 70000-200000 is used preferably.

  The weight average molecular weight Mw and the number average molecular weight Mn of the cellulose ester can be measured using gel permeation chromatography (GPC).

  The measurement conditions are as follows.

Solvent: Methylene chloride Column: Shodex K806, K805, K803G (Used by connecting three products manufactured by Showa Denko KK)
Column temperature: 25 ° C
Sample concentration: 0.1% by mass
Detector: RI Model 504 (manufactured by GL Sciences)
Pump: L6000 (manufactured by Hitachi, Ltd.)
Flow rate: 1.0ml / min
Calibration curve: Standard polystyrene STK standard polystyrene (manufactured by Tosoh Corporation) Mw = 100000 to 500 calibration curves with 13 samples are used. Thirteen samples are used at approximately equal intervals.

  The cellulose used as a raw material for the cellulose ester used in the present invention is not particularly limited, and examples thereof include cotton linter, wood pulp, and kenaf. Moreover, the cellulose ester obtained from them can be mixed and used in arbitrary ratios, respectively.

The cellulose ester such as cellulose acetate phthalate of the present invention can be produced by a known method. Specifically, it can be synthesized with reference to the method described in JP-A-10-45804.
(3.2) Second Optical Compensation Layer The second optical compensation layer 5 satisfies nx2 ≧ ny2> nz2, 1 <DSP (Rth2) as described above, and is a so-called positive wavelength dispersion negative C plate and It has become. The second optical compensation layer 5 preferably has Ro2 = 0 to 20 and Rth2 = 200 to 350.

  Here, in order to set the retardation value of the second optical compensation layer 5 in the above numerical range, it is preferable to perform biaxial stretching. When the second optical compensation layer 5 contains a cellulose ester, the glass transition point of the cellulose ester is within a range of about ± 10 ° C. in order to reduce residual strain as much as possible in the heat treatment and stretching treatment. The film produced by stretching in the conveying direction (length direction) and its orthogonal direction (width direction) at about 1.1 to 1.5 times or by solution casting has a residual solvent amount of 2 to 2. It is preferable to stretch about 1.1 to 1.7 times in the conveying direction and the orthogonal direction with about 100% by mass remaining.

  In the second optical compensation layer 5, it is preferable to control in-plane unevenness. For this purpose, it is preferable to precisely control the balance between the stretching temperature and the stretching ratio, and to independently control the stretched portion (such as a tenter clip) on both sides of the optical compensation layer 5. Such control can be achieved by adjusting the clip position and adjusting the stretching temperature and the stretching ratio with respect to the stress of the clip.

Although the form of the second optical compensation layer 5 is not limited, it is preferably a film. The thickness of the film is 40 to 200 μm, preferably 40 to 120 μm.
(3.2.1) Cellulose-based resin used for the second optical compensation layer The cellulose ester used for the second optical compensation layer 5 is not particularly limited and can be used for the first optical compensation layer 3. Among these cellulose esters, resins other than cellulose ester resins obtained by graft polymerization of ε-caprolactone onto cellulose ester resins can be used.
(3.2.2) DSP Value Raising Agent For the second optical compensation layer 5, it is preferable to use a DSP value raising agent in order to obtain the effects of the present invention by setting the retardation value within the above numerical range.

  The DSP raising agent refers to a compound whose DSP (Rth) is increased by 0.001 or more, preferably 0.002 or more by addition of 1%.

As the DSP increasing agent, for example, a triazine compound represented by the following general formula (II) disclosed in JP-A-2007-249180 can be used.
Formula (II)

(In the general formula (II), each R ¹² independently represents an aromatic ring or a heterocyclic ring having a substituent in at least one of the ortho position, the meta position, and the para position. X ¹¹ each independently represents Represents a single bond or —NR ¹³ —, wherein each R ¹³ independently represents a hydrogen atom, a substituted or unsubstituted alkyl group, an alkenyl group, an aryl group or a heterocyclic group.
Further, a discotic compound may be used as the DSP raising agent.

  As the discotic compound, a compound having at least two aromatic rings can be used.

  In the present specification, the “aromatic ring” includes an aromatic hetero ring in addition to an aromatic hydrocarbon ring.

  The aromatic hydrocarbon ring is particularly preferably a 6-membered ring (that is, a benzene ring).

  The aromatic heterocycle is generally an unsaturated heterocycle. The aromatic heterocycle is preferably a 5-membered ring, 6-membered ring or 7-membered ring, more preferably a 5-membered ring or 6-membered ring. Aromatic heterocycles generally have the most double bonds. As the hetero atom, a nitrogen atom, an oxygen atom and a sulfur atom are preferable, and a nitrogen atom is particularly preferable. Examples of aromatic heterocycles include furan ring, thiophene ring, pyrrole ring, oxazole ring, isoxazole ring, thiazole ring, isothiazole ring, imidazole ring, pyrazole ring, furazane ring, triazole ring, pyran ring, pyridine ring , Pyridazine ring, pyrimidine ring, pyrazine ring and 1,3,5-triazine ring.

  As the aromatic ring, benzene ring, furan ring, thiophene ring, pyrrole ring, oxazole ring, thiazole ring, imidazole ring, triazole ring, pyridine ring, pyrimidine ring, pyrazine ring and 1,3,5-triazine ring are preferable, In particular, a 1,3,5-triazine ring is preferably used. Specifically, for example, a compound disclosed in JP 2001-166144 A is preferably used as the discotic compound.

  The number of aromatic rings contained in the discotic compound is preferably 2 to 20, more preferably 2 to 12, still more preferably 2 to 8, and most preferably 2 to 6. preferable.

  The bonding relationship between two aromatic rings can be classified into (a) when a condensed ring is formed, (b) when directly linked by a single bond, and (c) when linked via a linking group (for aromatic rings). , Spiro bonds cannot be formed). The connection relationship may be any of (a) to (c).

  Examples of the condensed ring (a condensed ring of two or more aromatic rings) include an indene ring, a naphthalene ring, an azulene ring, a fluorene ring, a phenanthrene ring, an anthracene ring, an acenaphthylene ring, a biphenylene ring, a naphthacene ring, Pyrene ring, indole ring, isoindole ring, benzofuran ring, benzothiophene ring, indolizine ring, benzoxazole ring, benzothiazole ring, benzimidazole ring, benzotriazole ring, purine ring, indazole ring, chromene ring, quinoline ring, isoquinoline Ring, quinolidine ring, quinazoline ring, cinnoline ring, quinoxaline ring, phthalazine ring, pteridine ring, carbazole ring, acridine ring, phenanthridine ring, xanthene ring, phenazine ring, phenothiazine ring, phenoxathiin ring, phenoxazine ring and thiant It includes emissions ring. Naphthalene ring, azulene ring, indole ring, benzoxazole ring, benzothiazole ring, benzimidazole ring, benzotriazole ring and quinoline ring are preferred.

  The single bond (b) is preferably a bond between carbon atoms of two aromatic rings. Two aromatic rings may be bonded with two or more single bonds to form an aliphatic ring or a non-aromatic heterocyclic ring between the two aromatic rings.

The linking group in (c) is also preferably bonded to carbon atoms of two aromatic rings. The linking group is preferably an alkylene group, an alkenylene group, an alkynylene group, —CO—, —O—, —NH—, —S—, or a combination thereof. Examples of linking groups composed of combinations are shown below. In addition, the relationship between the left and right in the following examples of the linking group may be reversed. c1: -CO-O-c2: -CO-NH-c3: -alkylene-O-c4: -NH-CO-NH-c5: -NH-CO-O-c6: -O-CO-O-c7: -O-alkylene-O-c8: -CO-alkenylene-c9: -CO-alkenylene-NH-c10: -CO-alkenylene-O-c11: -alkylene-CO-O-alkylene-O-CO-alkylene-c12 : -O-alkylene-CO-O-alkylene-O-CO-alkylene-O-c13: -O-CO-alkylene-CO-O-c14: -NH-CO-alkenylene-c15: -O-CO-alkenylene −
The aromatic ring and the linking group may have a substituent.

  Examples of substituents include halogen atoms (F, Cl, Br, I), hydroxyl groups, carboxyl groups, cyano groups, amino groups, nitro groups, sulfo groups, carbamoyl groups, sulfamoyl groups, ureido groups, alkyl groups, alkenyls. Group, alkynyl group, aliphatic acyl group, aliphatic acyloxy group, alkoxy group, alkoxycarbonyl group, alkoxycarbonylamino group, alkylthio group, alkylsulfonyl group, aliphatic amide group, aliphatic sulfonamido group, aliphatic substituted amino group An aliphatic substituted carbamoyl group, an aliphatic substituted sulfamoyl group, an aliphatic substituted ureido group, and a non-aromatic heterocyclic group.

  It is preferable that the alkyl group has 1 to 8 carbon atoms. A chain alkyl group is preferable to a cyclic alkyl group, and a linear alkyl group is particularly preferable. The alkyl group may further have a substituent (eg, hydroxy group, carboxy group, alkoxy group, alkyl-substituted amino group). Examples of alkyl groups (including substituted alkyl groups) include methyl, ethyl, n-butyl, n-hexyl, 2-hydroxyethyl, 4-carboxybutyl, 2-methoxyethyl, and 2- A diethylaminoethyl group is included.

  The alkenyl group preferably has 2 to 8 carbon atoms. A chain alkenyl group is preferable to a cyclic alkenyl group, and a linear alkenyl group is particularly preferable. The alkenyl group may further have a substituent. Examples of the alkenyl group include a vinyl group, an allyl group, and a 1-hexenyl group.

  The alkynyl group preferably has 2 to 8 carbon atoms. A chain alkynyl group is preferable to a cyclic alkynyl group, and a linear alkynyl group is particularly preferable. The alkynyl group may further have a substituent. Examples of the alkynyl group include ethynyl group, 1-butynyl group and 1-hexynyl group.

  The number of carbon atoms in the aliphatic acyl group is preferably 1-10. Examples of the aliphatic acyl group include an acetyl group, a propanoyl group, and a butanoyl group.

  The number of carbon atoms in the aliphatic acyloxy group is preferably 1-10. Examples of the aliphatic acyloxy group include an acetoxy group.

  The number of carbon atoms of the alkoxy group is preferably 1-8. The alkoxy group may further have a substituent (eg, alkoxy group). Examples of the alkoxy group (including a substituted alkoxy group) include a methoxy group, an ethoxy group, a butoxy group, and a methoxyethoxy group.

  The number of carbon atoms of the alkoxycarbonyl group is preferably 2-10. Examples of the alkoxycarbonyl group include a methoxycarbonyl group and an ethoxycarbonyl group.

  The number of carbon atoms of the alkoxycarbonylamino group is preferably 2-10. Examples of the alkoxycarbonylamino group include a methoxycarbonylamino group and an ethoxycarbonylamino group.

  The alkylthio group preferably has 1 to 12 carbon atoms. Examples of the alkylthio group include a methylthio group, an ethylthio group, and an octylthio group.

  The alkylsulfonyl group preferably has 1 to 8 carbon atoms. Examples of the alkylsulfonyl group include a methanesulfonyl group and an ethanesulfonyl group.

  The number of carbon atoms in the aliphatic amide group is preferably 1-10. Examples of the aliphatic amide group include an acetamide group.

  The number of carbon atoms of the aliphatic sulfonamide group is preferably 1-8. Examples of the aliphatic sulfonamido group include a methanesulfonamido group, a butanesulfonamido group, and an n-octanesulfonamido group.

  The number of carbon atoms of the aliphatic substituted amino group is preferably 1-10. Examples of the aliphatic substituted amino group include a dimethylamino group, a diethylamino group, and a 2-carboxyethylamino group.

  The number of carbon atoms in the aliphatic substituted carbamoyl group is preferably 2-10. Examples of the aliphatic substituted carbamoyl group include a methylcarbamoyl group and a diethylcarbamoyl group.

  The number of carbon atoms in the aliphatic substituted sulfamoyl group is preferably 1-8. Examples of the aliphatic substituted sulfamoyl group include a methylsulfamoyl group and a diethylsulfamoyl group.

  The number of carbon atoms in the aliphatic substituted ureido group is preferably 2-10. Examples of the aliphatic substituted ureido group include a methylureido group.

  Examples of the non-aromatic heterocyclic group include a piperidino group and a morpholino group.

  The molecular weight of the DSP elevating agent made of a discotic compound is preferably 300 to 800.

  In the present invention, in addition to the aforementioned discotic compound, a rod-shaped compound having a linear molecular structure can also be preferably used. The linear molecular structure means that the molecular structure of the rod-like compound is linear in the most thermodynamically stable structure. The most thermodynamically stable structure can be obtained by crystal structure analysis or molecular orbital calculation. For example, molecular orbital calculation can be performed using molecular orbital calculation software (eg, WinMOPAC2000, manufactured by Fujitsu Limited) to obtain a molecular structure that minimizes the heat of formation of a compound. The molecular structure being linear means that in the thermodynamically most stable structure obtained by calculation as described above, the angle of the main chain constituting the molecular structure is 140 degrees or more.

  As the rod-shaped compound, those having at least two aromatic rings are preferable, and as the rod-shaped compound having at least two aromatic rings, a compound represented by the following general formula (103) is preferable.

Formula ^{(103): Ar 1 -L 1} -Ar 2
In the general formula (103), Ar ¹ and Ar ² are each independently an aromatic group.

  In the present specification, the aromatic group includes an aryl group (aromatic hydrocarbon group), a substituted aryl group, an aromatic heterocyclic group, and a substituted aromatic heterocyclic group.

  An aryl group and a substituted aryl group are more preferable than an aromatic heterocyclic group and a substituted aromatic heterocyclic group. The heterocycle of the aromatic heterocyclic group is generally unsaturated. The aromatic heterocycle is preferably a 5-membered ring, 6-membered ring or 7-membered ring, more preferably a 5-membered ring or 6-membered ring. Aromatic heterocycles generally have the most double bonds. As a hetero atom, a nitrogen atom, an oxygen atom or a sulfur atom is preferable, and a nitrogen atom or a sulfur atom is more preferable.

  As the aromatic ring of the aromatic group, a benzene ring, a furan ring, a thiophene ring, a pyrrole ring, an oxazole ring, a thiazole ring, an imidazole ring, a triazole ring, a pyridine ring, a pyrimidine ring and a pyrazine ring are preferable, and a benzene ring is particularly preferable. .

  Examples of the substituent of the substituted aryl group and the substituted aromatic heterocyclic group include a halogen atom (F, Cl, Br, I), a hydroxyl group, a carboxyl group, a cyano group, an amino group, an alkylamino group (eg, methyl). Amino group, ethylamino group, butylamino group, dimethylamino group), nitro group, sulfo group, carbamoyl group, alkylcarbamoyl group (eg, N-methylcarbamoyl group, N-ethylcarbamoyl group, N, N-dimethylcarbamoyl group) ), Sulfamoyl group, alkylsulfamoyl group (eg, N-methylsulfamoyl group, N-ethylsulfamoyl group, N, N-dimethylsulfamoyl group), ureido group, alkylureido group (eg, N -Methylureido group, N, N-dimethylureido group, N, N, N'-trimethylureido group), alkyl group (example Methyl, ethyl, propyl, butyl, pentyl, heptyl, octyl, isopropyl, s-butyl, t-amyl, cyclohexyl, cyclopentyl), alkenyl (eg, vinyl, allyl) Group, hexenyl group), alkynyl group (eg, ethynyl group, butynyl group), acyl group (eg, formyl group, acetyl group, butyryl group, hexanoyl group, lauryl group), acyloxy group (eg, acetoxy group, butyryloxy group, Hexanoyloxy group, lauryloxy group), alkoxy group (eg, methoxy group, ethoxy group, propoxy group, butoxy group, pentyloxy group, heptyloxy group, octyloxy group), aryloxy group (eg, phenoxy group), Alkoxycarbonyl group (eg, methoxycarbonyl group, ethoxycarbonyl group) Propoxycarbonyl group, butoxycarbonyl group, pentyloxycarbonyl group, heptyloxycarbonyl group), aryloxycarbonyl group (eg, phenoxycarbonyl group), alkoxycarbonylamino group (eg, butoxycarbonylamino group, hexyloxycarbonylamino group), Alkylthio group (eg, methylthio group, ethylthio group, propylthio group, butylthio group, pentylthio group, heptylthio group, octylthio group), arylthio group (eg, phenylthio group), alkylsulfonyl group (eg, methylsulfonyl group, ethylsulfonyl group, Propylsulfonyl group, butylsulfonyl group, pentylsulfonyl group, heptylsulfonyl group, octylsulfonyl group), amide group (eg, acetamido group, butyramide group, hexylamide group, Laurylamide group) and non-aromatic heterocyclic groups (eg, morpholyl group, pyrazinyl group).

  Examples of the substituent of the substituted aryl group and the substituted aromatic heterocyclic group include a halogen atom, a cyano group, a carboxyl group, a hydroxyl group, an amino group, an alkyl-substituted amino group, an acyl group, an acyloxy group, an amide group, an alkoxycarbonyl group, Alkoxy groups, alkylthio groups and alkyl groups are preferred.

  The alkyl part and alkyl group of the alkylamino group, alkoxycarbonyl group, alkoxy group and alkylthio group may further have a substituent. Examples of the alkyl moiety and the substituent of the alkyl group include halogen atom, hydroxyl, carboxyl, cyano, amino, alkylamino group, nitro, sulfo, carbamoyl, alkylcarbamoyl group, sulfamoyl, alkylsulfamoyl group, ureido, alkylureido Group, alkenyl group, alkynyl group, acyl group, acyloxy group, acylamino group, alkoxy group, aryloxy group, alkoxycarbonyl group, aryloxycarbonyl group, alkoxycarbonylamino group, alkylthio group, arylthio group, alkylsulfonyl group, amide group And non-aromatic heterocyclic groups. As the substituent for the alkyl moiety and the alkyl group, a halogen atom, hydroxyl, amino, alkylamino group, acyl group, acyloxy group, acylamino group, alkoxycarbonyl group and alkoxy group are preferable.

In General Formula (103), L ¹ is a divalent linking group selected from an alkylene group, an alkenylene group, an alkynylene group, —O—, —CO—, and a combination thereof.

  The alkylene group may have a cyclic structure. As the cyclic alkylene group, cyclohexylene is preferable, and 1,4-cyclohexylene is particularly preferable. As the chain alkylene group, a linear alkylene group is more preferable than a branched alkylene group.

  The number of carbon atoms of the alkylene group is preferably 1-20, more preferably 1-15, still more preferably 1-10, still more preferably 1-8, and most preferably 1-6. It is.

  The alkenylene group and the alkynylene group preferably have a chain structure rather than a cyclic structure, and more preferably have a linear structure rather than a branched chain structure.

  The alkenylene group and the alkynylene group preferably have 2 to 10 carbon atoms, more preferably 2 to 8, more preferably 2 to 6, still more preferably 2 to 4, and most preferably 2. (Vinylene or ethynylene).

  The arylene group preferably has 6 to 20 carbon atoms, more preferably 6 to 16, and still more preferably 6 to 12.

In the molecular structure of the general formula (103), the angle formed by Ar ¹ and Ar ² across L ¹ is preferably 140 degrees or more.

  As the rod-like compound, a compound represented by the following formula (104) is more preferable.

Formula ^{(104): Ar 1 -L 2} -X-L 3 -Ar 2
In the general formula (104), Ar ¹ and Ar ² are each independently an aromatic group. The definition and examples of the aromatic group are the same as those of Ar ¹ and Ar ^{2 in} the general formula (103).

In General Formula (104), L ² and L ³ are each independently a divalent linking group selected from an alkylene group, —O—, —CO—, and a group consisting of a combination thereof.

  The alkylene group preferably has a chain structure rather than a cyclic structure, and more preferably has a linear structure rather than a branched chain structure.

  The alkylene group preferably has 1 to 10 carbon atoms, more preferably 1 to 8, more preferably 1 to 6, still more preferably 1 to 4, and 1 or 2 (methylene or Most preferred is ethylene).

L ² and L ³ are particularly preferably —O—CO— or —CO—O—.

  In the general formula (104), X is 1,4-cyclohexylene, vinylene or ethynylene.

  Specific examples of the compound represented by the general formula (103) or (104) include compounds described in [Chemical Formula 1] to [Chemical Formula 11] of JP-A No. 2004-109657.

  Other preferred compounds are shown below.

  Two or more rod-shaped compounds having a maximum absorption wavelength (λmax) shorter than 250 nm in the ultraviolet absorption spectrum of the solution may be used in combination.

The rod-like compound can be synthesized by a method described in the literature. As literature, Mol. Cryst. Liq. Cryst. 53, 229 (1979), 89, 93 (1982), 145, 111 (1987), 170, 43 (1989), J. Am. Am. Chem. Soc. 113, p. 1349 (1991), p. 118, p. 5346 (1996), p. 92, p. 1582 (1970). Org. Chem. 40, 420 pages (1975), Tetrahedron, Vol. 48, No. 16, page 3437 (1992).
(3.3) Additive The above first and second optical compensation layers 3 and 5 may contain an additive as necessary in order to obtain the effects of the present invention. Additives are not particularly limited, but preferably aromatic-terminated polyester compounds, sugar ester compounds, (meth) acrylic compounds, polycarboxylic acid ester compounds, glycolate compounds, phthalate ester compounds, fatty acid esters Selected from the group compounds, polyhydric alcohol ester compounds, polyester plasticizers, and the like.
(3.3.1) Aromatic Terminal Polyester Compound In the present invention, an aromatic terminal polyester compound represented by the following general formula (I) can be used.

General formula (I) B- (GA) n-GB
(In the formula, B is an arylcarboxylic acid residue, G is an alkylene glycol residue having 2 to 12 carbon atoms, an aryl glycol residue having 6 to 12 carbon atoms, or an oxyalkylene glycol residue having 4 to 12 carbon atoms, A Represents an alkylene dicarboxylic acid residue having 4 to 12 carbon atoms or an aryl dicarboxylic acid residue having 6 to 12 carbon atoms, and n represents an integer of 1 or more.)
In general formula (I), an arylcarboxylic acid residue represented by B and an alkylene glycol residue or oxyalkylene glycol residue or arylglycol residue represented by G, an alkylenedicarboxylic acid residue or aryldicarboxylic acid represented by A And is obtained by the same reaction as a normal polyester compound.

  Examples of the arylcarboxylic acid component of the aromatic-terminated polyester compound used in the present invention include, for example, benzoic acid, para-tert-butylbenzoic acid, orthotoluic acid, metatoluic acid, p-toluic acid, dimethylbenzoic acid, ethylbenzoic acid, normal There are propylbenzoic acid, aminobenzoic acid, acetoxybenzoic acid and the like, and these can be used as one kind or a mixture of two or more kinds, respectively.

  Examples of the alkylene glycol component having 2 to 12 carbon atoms of the aromatic terminal polyester compound that can be used in the present invention include ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,2-butanediol, 1,3-butanediol, 1,2-propanediol, 2-methyl 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 2,2-dimethyl-1,3-propanediol (Neopentyl glycol), 2,2-diethyl-1,3-propanediol (3,3-dimethylolpentane), 2-n-butyl-2-ethyl-1,3-propanediol (3,3-dimethylol) Heptane), 3-methyl-1,5-pentanediol 1,6-hexanediol, 2,2,4-trimethyl 1, -Pentanediol, 2-ethyl 1,3-hexanediol, 2-methyl 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,12-octadecanediol, etc. Glycol is used as one or a mixture of two or more.

  In particular, an alkylene glycol having 2 to 12 carbon atoms is particularly preferable because of excellent compatibility with a cellulose ester.

  In addition, examples of the oxyalkylene glycol component having 4 to 12 carbon atoms of the aromatic terminal polyester compound include diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, and tripropylene glycol. One kind or a mixture of two or more kinds can be used.

  Examples of the alkylene dicarboxylic acid component having 4 to 12 carbon atoms of the aromatic terminal polyester compound include succinic acid, maleic acid, fumaric acid, glutaric acid, adipic acid, azelaic acid, sebacic acid, and dodecanedicarboxylic acid. These are used as one kind or a mixture of two or more kinds, respectively.

  Examples of the arylene dicarboxylic acid component having 6 to 12 carbon atoms include phthalic acid, terephthalic acid, isophthalic acid, 1,5 naphthalene dicarboxylic acid, and 1,4 naphthalene dicarboxylic acid.

  As for the aromatic terminal polyester type compound used by this invention, it is preferable that n is 1 or more and 100 or less, The number average molecular weight becomes like this. Preferably it is 300-1500, More preferably, the range of 400-1000 is suitable.

  The acid value is 0.5 mgKOH / g or less, the hydroxyl value is 25 mgKOH / g or less, more preferably the acid value is 0.3 mgKOH / g or less, and the hydroxyl value is 15 mgKOH / g or less.

  The aromatic terminal polyester compound represented by the general formula (I) of the present invention is preferably contained in an amount of 0.5 to 30% by mass with respect to the cellulose ester.

  Although the specific compound of the aromatic terminal polyester type compound which can be used for this invention below is shown, this invention is not limited to this.

The additives described below are appropriately used in the first and second optical compensation layers according to the present invention.
(3.3.2) Sugar ester compound The first and second optical compensation layers 3 and 5 of the present invention have at least one pyranose structure or at least one furanose structure and 12 or less OH having the structure. It is good also as including the ester compound (sugar ester compound) which esterified all or one part of group.

  The proportion of esterification is preferably 70% or more of the OH groups present in the pyranose structure or furanose structure.

  In the present invention, ester compounds are collectively referred to as sugar ester compounds.

  Examples of the ester compound of the present invention include the following, but the present invention is not limited thereto.

  Glucose, galactose, mannose, fructose, xylose or arabinose, lactose, sucrose, nystose, 1F-fructosyl nystose, stachyose, maltitol, lactitol, lactulose, cellobiose, maltose, cellotriose, maltotriose, raffinose or kestose .

  In addition, gentiobiose, gentiotriose, gentiotetraose, xylotriose, galactosyl sucrose, and the like are also included.

  Among these compounds, compounds having both a pyranose structure and a furanose structure are particularly preferable.

  Examples include sucrose, kestose, nystose, 1F-fructosyl nystose, stachyose, and more preferably sucrose.

  The monocarboxylic acid used for esterifying all or part of the OH group in the pyranose structure or furanose structure of the present invention is not particularly limited, and is a known aliphatic monocarboxylic acid or alicyclic monocarboxylic acid. An aromatic monocarboxylic acid or the like can be used. The carboxylic acid used may be one type or a mixture of two or more types.

  Preferred aliphatic monocarboxylic acids include acetic acid, propionic acid, butyric acid, isobutyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, 2-ethyl-hexanecarboxylic acid, undecylic acid, lauric acid , Saturated fatty acids such as tridecylic acid, myristic acid, pentadecylic acid, palmitic acid, heptadecylic acid, stearic acid, nonadecanoic acid, arachidic acid, behenic acid, lignoceric acid, serotic acid, heptacosanoic acid, montanic acid, melicic acid, and laccelic acid, Examples include unsaturated fatty acids such as undecylenic acid, oleic acid, sorbic acid, linoleic acid, linolenic acid, arachidonic acid and octenoic acid.

  Examples of preferable alicyclic monocarboxylic acids include acetic acid, cyclopentanecarboxylic acid, cyclohexanecarboxylic acid, cyclooctanecarboxylic acid, and derivatives thereof.

  Examples of preferred aromatic monocarboxylic acids include aromatic monocarboxylic acids having an alkyl group or alkoxy group introduced into the benzene ring of benzoic acid such as benzoic acid and toluic acid, cinnamic acid, benzylic acid, biphenylcarboxylic acid, and naphthalene. Examples thereof include aromatic monocarboxylic acids having two or more benzene rings such as carboxylic acid and tetralin carboxylic acid, or derivatives thereof. More specifically, xylyl acid, hemelic acid, mesitylene acid, prenylic acid, γ-isoduric acid, jurylic acid, mesitic acid, α-isoduric acid, cumic acid, α-toluic acid, hydroatropic acid, atropic acid, hydrocinnamic acid, salicylic acid, o-anisic acid, m-anisic acid, p-anisic acid , Creosote acid, o-homosalicylic acid, m-homosalicylic acid, p-homosalicylic acid, o-pyroca Succinic acid, β-resorcylic acid, vanillic acid, isovanillic acid, veratromic acid, o-veratrumic acid, gallic acid, asaronic acid, mandelic acid, homoanisic acid, homovanillic acid, homoveratrumic acid, o-homoveratrumic acid, phthalonic acid, p- Although coumaric acid can be mentioned, benzoic acid is particularly preferable.

  The oligosaccharide ester compound can be applied as a compound having 1 to 12 at least one pyranose structure or furanose structure in the present invention.

  Oligosaccharides are produced by allowing an enzyme such as amylase to act on starch, sucrose, etc. Examples of oligosaccharides that can be applied to the present invention include maltooligosaccharides, isomaltoligosaccharides, fructooligosaccharides, galactooligosaccharides, xylooligos. Sugar.

Moreover, the said ester compound is a compound which condensed 1 or more and 12 or less of at least 1 sort (s) of the pyranose structure or furanose structure represented with the following general formula (A). However, R < ₁₁ > -R < ₁₅ >, R < ₂₁ > -R < ₂₅ > represents a C2-C22 acyl group or a hydrogen atom, m and n represent the integer of 0-12 respectively, and m + n represents the integer of 1-12.

R _{11 to} R ₁₅ and R _{21 to} R ₂₅ are preferably a benzoyl group or a hydrogen atom. Benzoyl group may further have a substituent R _{26 (p} is 0-5), for example, an alkyl group, an alkenyl group, an alkoxyl group and a phenyl group, further the alkyl group, an alkenyl group, a phenyl group May have a substituent. Oligosaccharides can also be produced by the same method as the ester compound of the present invention.

  Although the specific example of the ester compound in this invention is given to the following, this invention is not limited to this.

The cellulose ester film (first and second optical compensation layers 3 and 5) of the present invention is obtained by using the sugar ester compound of the present invention in order to stabilize the display quality by suppressing the fluctuation of the retardation value. It is preferable to contain 0.5-30 mass% of an ester film, and it is preferable to contain 5-30 mass% especially.
(3.3.3) (Meth) acrylic compound The (meth) acrylic compound used in the present invention exhibits negative birefringence as a function of the stretching direction when it is contained in an optical compensation film. Although the structure is not particularly limited, a polymer having a weight average molecular weight of 500 to 30,000 obtained by polymerizing an ethylenically unsaturated monomer is preferable.

(Test method for birefringence of (meth) acrylic compounds)
A (meth) acrylic polymer (compound) was dissolved in a solvent, cast into a film, then dried by heating, and birefringence was evaluated for a film having a transmittance of 80% or more.

  Refractive index measurement was performed using an Abbe refractometer-4T (manufactured by Atago Co., Ltd.) using a multi-wavelength light source. The refractive index ny in the stretching direction and the refractive index in the in-plane direction perpendicular to each other were defined as nx. For a film where (ny−nx) <0 for each refractive index at 550 nm, the (meth) acrylic polymer is judged to be negatively birefringent with respect to the stretching direction.

  The (meth) acrylic polymer having a weight average molecular weight of 500 to 30,000 used in the present invention is a (meth) acrylic polymer having an aromatic ring in the side chain or a (meth) acrylic having a cyclohexyl group in the side chain. A polymer may be used.

  When the polymer has a weight average molecular weight of 500 or more and 30000 or less, and the composition of the polymer is controlled, for example, when the optical compensation film is a cellulose ester film particularly preferable in the present invention, the cellulose ester and the polymer The compatibility with can be improved.

  For a (meth) acrylic polymer having an aromatic ring in the side chain or a (meth) acrylic polymer having a cyclohexyl group in the side chain, preferably if the weight average molecular weight is from 500 to 10,000, The cellulose ester film after film formation is excellent in transparency, has extremely low moisture permeability, and exhibits excellent performance as a protective film for a polarizing plate.

  Since the polymer has a weight average molecular weight of 500 or more and 30000 or less, it is considered to be between the oligomer and the low molecular weight polymer. In order to synthesize such a polymer, it is difficult to control the molecular weight in normal polymerization, and it is desirable to use a method that can align the molecular weight as much as possible by a method that does not increase the molecular weight too much.

  In particular, the (meth) acrylic polymer used in the optical compensation film of the present invention includes an ethylenically unsaturated monomer Xa having no aromatic ring and hydroxyl group in the molecule, and no hydroxyl ring in the molecule. A polymer X having a weight average molecular weight of 2,000 to 30,000 obtained by copolymerizing an ethylenically unsaturated monomer Xb having a copolymerizable ethylenically unsaturated monomer excluding Xa and Xb, or an aromatic ring; A polymer Y having a weight average molecular weight of 500 or more and 3000 or less obtained by polymerizing an ethylenically unsaturated monomer Ya that does not exist and an ethylenically unsaturated monomer copolymerizable with Ya is preferable.

[Polymer X, Polymer Y]
The method for adjusting Ro and Rth of the optical compensation film in the present invention includes an ethylenically unsaturated monomer Xa having no aromatic ring and hydroxyl group in the molecule, and an ethylenic group having no hydroxyl ring and having a hydroxyl group in the molecule. High molecular weight polymer X having a weight average molecular weight of 2,000 to 30,000 obtained by copolymerizing unsaturated monomer Xb and a copolymerizable ethylenically unsaturated monomer excluding Xa and Xb, and more preferably, Contains a low molecular weight polymer Y having a weight average molecular weight of 500 to 3,000 obtained by polymerizing an ethylenically unsaturated monomer Ya having no aromatic ring and an ethylenically unsaturated monomer copolymerizable with Ya It is preferable.

  The polymer X used in the present invention includes an ethylenically unsaturated monomer Xa having no aromatic ring and a hydroxyl group in the molecule and an ethylenically unsaturated monomer Xb having no hydroxyl ring in the molecule and having a hydroxyl group, Xa and Xb. Is a polymer having a weight average molecular weight of 2000 or more and 30000 or less obtained by copolymerization with a copolymerizable ethylenically unsaturated monomer other than.

  Preferably, Xa is an acrylic or methacrylic monomer having no aromatic ring and hydroxyl group in the molecule, and Xb is an acrylic or methacrylic monomer having no aromatic ring and having a hydroxyl group in the molecule.

  The polymer X used in the present invention is represented by the following general formula (X).

Formula (X)
-[Xa] m- [Xb] n- [Xc] p-
In the general formula (X), Xa represents an ethylenically unsaturated monomer having no aromatic ring and hydroxyl group in the molecule, and Xb represents an ethylenically unsaturated monomer having no aromatic ring and having a hydroxyl group in the molecule. Xc represents a copolymerizable ethylenically unsaturated monomer excluding Xa and Xb. m, n, and p each represent a molar composition ratio. However, m ≠ 0, n ≠ 0, and m + n + p = 100.

  Furthermore, the polymer X is preferably a polymer represented by the following general formula (X-1).

Formula (X-1)
_{- [CH 2 -C (-R1)} (- CO 2 R2)] m- [CH 2 -C (-R3) (- CO 2 R4-OH) -] n- [Xc] p-
In the general formula (X-1), R1 and R3 each represent a hydrogen atom or a methyl group. R2 represents an alkyl group having 1 to 12 carbon atoms or a cycloalkyl group. R4 is _{-CH 2 -, - C 2 H} 4 - or _-C 3 _{H 6} - represents a. Xc _{is, [CH 2 -C (-R1)} (- CO 2 R2)] representing the a polymerizable monomer unit or _{[CH 2 -C (-R3) (} - - CO 2 R4-OH)]. m, n, and p represent a molar composition ratio. However, m ≠ 0, n ≠ 0, and m + n + p = 100.

  Although the monomer as a monomer unit which comprises the polymer X used for this invention is mentioned below, it is not limited to this.

  In X, the hydroxyl group means not only a hydroxyl group but also a group having an ethylene oxide chain.

  Examples of the ethylenically unsaturated monomer Xa having no aromatic ring and hydroxyl group in the molecule include methyl acrylate, ethyl acrylate, propyl acrylate (i-, n-), and butyl acrylate (n-, i-, s). -, T-), pentyl acrylate (n-, i-, s-), hexyl acrylate (n-, i-), heptyl acrylate (n-, i-), octyl acrylate (n-, i -), Nonyl acrylate (n-, i-), myristyl acrylate (n-, i-), acrylic acid (2-ethylhexyl), acrylic acid (ε-caprolactone), etc. The thing changed into acid ester can be mentioned. Among these, methyl acrylate, ethyl acrylate, methyl methacrylate, ethyl methacrylate, and propyl methacrylate (i-, n-) are preferable.

  The ethylenically unsaturated monomer Xb having no hydroxyl ring in the molecule and having a hydroxyl group is preferably acrylic acid or methacrylic acid ester as a monomer unit having a hydroxyl group, such as acrylic acid (2-hydroxyethyl), acrylic acid. (2-hydroxypropyl), acrylic acid (3-hydroxypropyl), acrylic acid (4-hydroxybutyl), acrylic acid (2-hydroxybutyl), or those obtained by replacing these acrylic acids with methacrylic acid. Preferred are acrylic acid (2-hydroxyethyl) and methacrylic acid (2-hydroxyethyl), acrylic acid (2-hydroxypropyl), and acrylic acid (3-hydroxypropyl).

  Xc is not particularly limited as long as it is a monomer other than Xa and Xb and is a copolymerizable ethylenically unsaturated monomer, but preferably has no aromatic ring.

  The molar composition ratio m: n of Xa and Xb is preferably in the range of 99: 1 to 65:35, more preferably in the range of 95: 5 to 75:25. P of Xc is 0-10. Xc may be a plurality of monomer units.

  When the molar composition ratio of Xa is large, compatibility with the cellulose ester is improved, but the retardation value Rth in the film thickness direction is increased. When the molar composition ratio of Xb is large, the compatibility is deteriorated, but the effect of reducing Rth is high.

  Further, if the molar composition ratio of Xb exceeds the above range, haze tends to occur during film formation, and it is preferable to optimize these and determine the molar composition ratio of Xa and Xb.

  The molecular weight of the high molecular weight polymer X is more preferably 5,000 or more and 30,000 or less, and still more preferably 8,000 or more and 25,000 or less.

  By setting the weight average molecular weight to 5,000 or more, it is preferable because advantages such as little dimensional change of the optical compensation film under high temperature and high humidity and less curling as a polarizing plate protective film can be obtained.

  When the weight average molecular weight is 30000 or less, compatibility with the cellulose ester is further improved, and bleeding out under high temperature and high humidity and further haze generation immediately after film formation are suppressed.

  The weight average molecular weight of the polymer X used in the present invention can be adjusted by a known molecular weight adjusting method. Examples of such a molecular weight adjusting method include a method of adding a chain transfer agent such as carbon tetrachloride, lauryl mercaptan, octyl thioglycolate, and the like.

  The polymerization temperature is usually from room temperature to 130 ° C., preferably from 50 ° C. to 100 ° C., and this temperature or the polymerization reaction time can be adjusted.

  As the method for measuring the average molecular weight, the method described above in (3.1.1) can be used.

  The low molecular weight polymer Y used in the present invention is a polymer having a weight average molecular weight of 500 or more and 3000 or less obtained by polymerizing an ethylenically unsaturated monomer Ya having no aromatic ring. A weight average molecular weight of 500 or more is preferred because the residual monomer in the polymer is reduced.

  Moreover, it is preferable to set it as 3000 or less in order to maintain retardation value Rth fall performance. Ya is preferably an acrylic or methacrylic monomer having no aromatic ring.

  The polymer Y used in the present invention is represented by the following general formula (Y).

General formula (Y)
-[Ya] k- [Yb] q-
In the general formula (Y), Ya represents an ethylenically unsaturated monomer having no aromatic ring, and Yb represents an ethylenically unsaturated monomer copolymerizable with Ya. k and q each represent a molar composition ratio. However, k ≠ 0, q ≠ 0, and k + q = 100.

  The polymer Y used in the present invention is more preferably a polymer represented by the following general formula (Y-1).

General formula (Y-1)
_{- [CH 2 -C (-R5)} (- CO 2 R6)] k- [Yb] q-
In the general formula (Y-1), R5 represents a hydrogen atom or a methyl group, respectively. R6 represents an alkyl group having 1 to 12 carbon atoms or a cycloalkyl group. Yb represents a monomer unit copolymerizable with [CH ₂ —C (—R 5) (— CO ₂ R 6)]. k and q each represent a molar composition ratio. However, k ≠ 0, q ≠ 0, and k + q = 100.

Yb is a _{Ya [CH 2 -C (-R5)} (- CO 2 R6)] and is not particularly limited as long as it is copolymerizable ethylenically unsaturated monomers. Yb may be plural. k + q = 100, q is preferably 1-30.

  The ethylenically unsaturated monomer Ya constituting the polymer Y obtained by polymerizing the ethylenically unsaturated monomer having no aromatic ring is, for example, methyl acrylate, ethyl acrylate, propyl acrylate ( i-, n-), butyl acrylate (n-, i-, s-, t-), pentyl acrylate (n-, i-, s-), hexyl acrylate (n-, i-), acrylic Acid heptyl (n-, i-), octyl acrylate (n-, i-), nonyl acrylate (n-, i-), myristyl acrylate (n-, i-), cyclohexyl acrylate, acrylic acid ( 2-ethylhexyl), acrylic acid (ε-caprolactone), acrylic acid (2-hydroxyethyl), acrylic acid (2-hydroxypropyl), acrylic acid (3-hydroxypropiyl) ), Acrylic acid (4-hydroxybutyl), acrylic acid (2-hydroxybutyl), methacrylic acid ester, the above acrylic acid ester changed to methacrylic acid ester; unsaturated acid, for example, acrylic acid, methacrylic acid And maleic anhydride, crotonic acid, itaconic acid and the like.

  Yb is not particularly limited as long as it is an ethylenically unsaturated monomer copolymerizable with Ya. Examples of vinyl esters include vinyl acetate, vinyl propionate, vinyl butyrate, vinyl valerate, vinyl pivalate, and vinyl caproate. Vinyl caprate, vinyl laurate, vinyl myristate, vinyl palmitate, vinyl stearate, vinyl cyclohexanecarboxylate, vinyl octylate, vinyl methacrylate, vinyl crotonate, vinyl sorbate, vinyl cinnamate and the like are preferred. Yb may be plural.

  In order to synthesize the polymers X and Y, it is difficult to control the molecular weight in normal polymerization, and it is desirable to use a method that can make the molecular weights as uniform as possible without increasing the molecular weight.

  Such polymerization methods include a method using a peroxide polymerization initiator such as cumene peroxide and t-butyl hydroperoxide, a method using a polymerization initiator in a larger amount than normal polymerization, and a mercapto compound in addition to the polymerization initiator. And a method of using a chain transfer agent such as carbon tetrachloride, a method of using a polymerization terminator such as benzoquinone and dinitrobenzene in addition to the polymerization initiator, and further, Japanese Patent Application Laid-Open No. 2000-128911 or 2000-344823. Examples thereof include a compound having one thiol group and a secondary hydroxyl group, or a bulk polymerization method using a polymerization catalyst in which the compound and an organometallic compound are used in combination. Used.

  In particular, the polymer Y is preferably a polymerization method using a compound having a thiol group and a secondary hydroxyl group in the molecule as a chain transfer agent. In this case, the terminal of the polymer Y has a hydroxyl group and a thioether resulting from the polymerization catalyst and the chain transfer agent. The compatibility of Y and cellulose ester can be adjusted by this terminal residue.

  The hydroxyl values of the polymers X and Y are preferably 30 to 150 [mg KOH / g].

(Measurement method of hydroxyl value)
The measurement of the hydroxyl value is based on JIS K 0070 (1992). This hydroxyl value is defined as the number of mg of potassium hydroxide required to neutralize acetic acid bonded to a hydroxyl group when 1 g of a sample is acetylated.

  Specifically, sample Xg (about 1 g) is precisely weighed in a flask, and 20 ml of an acetylating reagent (a solution obtained by adding pyridine to 20 ml of acetic anhydride to 400 ml) is accurately added thereto. An air cooling tube is attached to the mouth of the flask and heated in a glycerin bath at 95-100 ° C. After 1 hour and 30 minutes, the mixture is cooled, 1 ml of purified water is added from an air condenser, and acetic anhydride is decomposed into acetic acid.

  Next, titration is performed with a 0.5 mol / L potassium hydroxide ethanol solution using a potentiometric titrator, and the inflection point of the obtained titration curve is set as the end point.

  Further, as a blank test, titration is performed without a sample, and an inflection point of the titration curve is obtained. The hydroxyl value is calculated by the following formula.

Hydroxyl value = {(BC) × f × 28.05 / X} + D
In the formula, B is the amount (ml) of 0.5 mol / L potassium hydroxide ethanol solution used for the blank test, C is the amount (ml) of 0.5 mol / L potassium hydroxide ethanol solution used for titration, f is a factor of a 0.5 mol / L potassium hydroxide ethanol solution, D is an acid value, and 28.05 is 1/2 of 1 mol amount 56.11 of potassium hydroxide.

  The above-mentioned polymer X and polymer Y are both excellent in compatibility with cellulose ester, excellent in productivity without evaporation and volatilization, good retention as a protective film for polarizing plates, low moisture permeability, and dimension stability. Excellent in properties.

  The content of the polymer X and the polymer Y in the optical compensation film is such that the content of the polymer X is Xg (mass% = (mass of polymer X / mass of cellulose ester) × 100). When the content is Yg (mass%), it is preferably in a range satisfying the following formulas (i) and (ii).

Formula (i) 5 ≦ Xg + Yg ≦ 35 (mass%)
Formula (ii) 0.05 ≦ Yg / (Xg + Yg) ≦ 0.4
A preferable range of (Xg + Yg) in the formula (i) is 10 to 35% by mass. If the polymer X and the polymer Y are 5 mass% or more as a total amount with respect to the total mass of the cellulose ester, they sufficiently act to adjust the retardation value Rth. Moreover, if it is 35 mass% or less as a total amount, adhesiveness with polarizer PVA is favorable.

The polymer X and the polymer Y can be directly added and dissolved as a material constituting the dope solution described later, or can be added to the dope solution after being previously dissolved in an organic solvent for dissolving the cellulose ester.
(3.4) Ultraviolet Absorber The first and second optical compensation layers 3 and 5 can also contain an ultraviolet absorber. The ultraviolet absorber is intended to improve durability by absorbing ultraviolet rays of 400 nm or less, and in particular, the transmittance at a wavelength of 370 nm is preferably 10% or less, more preferably 5% or less, and further Preferably it is 2% or less.

  Although the ultraviolet absorber used in the present invention is not particularly limited, for example, oxybenzophenone compounds, benzotriazole compounds, salicylic acid ester compounds, benzophenone compounds, cyanoacrylate compounds, triazine compounds, nickel complex compounds, inorganic powders Examples include the body.

  For example, 5-chloro-2- (3,5-di-sec-butyl-2-hydroxylphenyl) -2H-benzotriazole, (2-2H-benzotriazol-2-yl) -6- (linear and side Chain dodecyl) -4-methylphenol, 2-hydroxy-4-benzyloxybenzophenone, 2,4-benzyloxybenzophenone, etc., and tinuvin 109, tinuvin 171, tinuvin 234, tinuvin 326, tinuvin 327, tinuvin 328, etc. These are commercially available products made by Ciba Japan Co., Ltd. and can be preferably used.

  The UV absorbers preferably used in the present invention are benzotriazole UV absorbers, benzophenone UV absorbers, and triazine UV absorbers, particularly preferably benzotriazole UV absorbers and benzophenone UV absorbers. .

  For example, as the benzotriazole ultraviolet absorber, a compound represented by the following general formula (d) can be used.

In the formula, R ₁ , R ₂ , R ₃ , R ₄ and R ₅ may be the same or different, and are a hydrogen atom, a halogen atom, a nitro group, a hydroxyl group, an alkyl group, an alkenyl group, an aryl group, an alkoxyl group, an acyloxy group. Represents a group, aryloxy group, alkylthio group, arylthio group, mono- or dialkylamino group, acylamino group or 5- to 6-membered heterocyclic group, and R ₄ and R ₅ are closed to form a 5- to 6-membered carbocycle May be.

  Moreover, these groups described above may have an arbitrary substituent.

  Although the specific example of the benzotriazole type ultraviolet absorber used for this invention below is given, this invention is not limited to these.

UV-1: 2- (2'-hydroxy-5'-methylphenyl) benzotriazole UV-2: 2- (2'-hydroxy-3 ', 5'-di-tert-butylphenyl) benzotriazole UV-3 : 2- (2'-hydroxy-3'-tert-butyl-5'-methylphenyl) benzotriazole UV-4: 2- (2'-hydroxy-3 ', 5'-di-tert-butylphenyl)- 5-Chlorobenzotriazole UV-5: 2- (2'-hydroxy-3 '-(3 ", 4", 5 ", 6" -tetrahydrophthalimidomethyl) -5'-methylphenyl) benzotriazole UV-6: 2,2-methylenebis (4- (1,1,3,3-tetramethylbutyl) -6- (2H-benzotriazol-2-yl) phenol)
UV-7: 2- (2'-hydroxy-3'-tert-butyl-5'-methylphenyl) -5-chlorobenzotriazole UV-8: 2- (2H-benzotriazol-2-yl) -6 (Linear and side chain dodecyl) -4-methylphenol (TINUVIN171)
UV-9: Octyl-3- [3-tert-butyl-4-hydroxy-5- (chloro-2H-benzotriazol-2-yl) phenyl] propionate and 2-ethylhexyl-3- [3-tert-butyl- 4-Hydroxy-5- (5-chloro-2H-benzotriazol-2-yl) phenyl] propionate mixture (TINUVIN 109)
Further, as the benzophenone ultraviolet absorber, a compound represented by the following general formula (e) is preferably used.

  In the formula, Y represents a hydrogen atom, a halogen atom or an alkyl group, an alkenyl group, an alkoxyl group, and a phenyl group, and these alkyl group, alkenyl group, and phenyl group may have a substituent. A represents a hydrogen atom, an alkyl group, an alkenyl group, a phenyl group, a cycloalkyl group, an alkylcarbonyl group, an alkylsulfonyl group or a —CO (NH) n-1-D group, and D represents an alkyl group, an alkenyl group or a substituent. Represents a phenyl group which may have m and n represent 1 or 2.

  In the above, the alkyl group represents, for example, a linear or branched aliphatic group having up to 24 carbon atoms, the alkoxyl group represents, for example, an alkoxyl group having up to 18 carbon atoms, and the alkenyl group has, for example, carbon number An alkenyl group up to 16 represents an allyl group, a 2-butenyl group, or the like. In addition, as substituents to alkyl groups, alkenyl groups, and phenyl groups, halogen atoms such as chlorine atoms, bromine atoms, fluorine atoms, etc., hydroxyl groups, phenyl groups (this phenyl group is substituted with alkyl groups or halogen atoms, etc.) May be used).

  Specific examples of the benzophenone-based ultraviolet absorber represented by the general formula (e) are shown below, but the present invention is not limited thereto.

UV-10: 2,4-dihydroxybenzophenone UV-11: 2,2'-dihydroxy-4-methoxybenzophenone UV-12: 2-hydroxy-4-methoxy-5-sulfobenzophenone UV-13: Bis (2-methoxy -4-hydroxy-5-benzoylphenylmethane)
In addition, a discotic compound such as a compound having a 1,3,5 triazine ring is also preferably used as the ultraviolet absorber.

  The first and second optical compensation layers 3 and 5 in the present invention preferably contain two or more kinds of ultraviolet absorbers.

  As the UV absorber, a polymer UV absorber can also be preferably used, and in particular, a polymer type UV absorber described in JP-A-6-148430 is preferably used.

  The method for adding the UV absorber is to add the UV absorber to the dope after dissolving the UV absorber in an alcohol such as methanol, ethanol or butanol, an organic solvent such as methylene chloride, methyl acetate, acetone or dioxolane, or a mixed solvent thereof. Or you may add directly in dope composition. For an inorganic powder that does not dissolve in an organic solvent, a dissolver or a sand mill is used in the organic solvent and cellulose ester to disperse and then added to the dope.

The amount of UV absorber used is not uniform depending on the type of UV absorber, operating conditions, etc. If the dry film thickness of the optical compensation film (optical compensation layers 3 and 5) is 30 to 200 μm, the optical compensation film 0.5-10 mass% is preferable with respect to 0.6-4 mass%.
(3.5) Antioxidants Antioxidants are also called deterioration inhibitors. When a liquid crystal image display device or the like is placed in a high humidity and high temperature state, the first and second optical compensation layers 3 and 5 as the optical compensation film may be deteriorated. The antioxidant has a role of delaying or preventing the optical compensation film from being decomposed by, for example, halogen in the amount of residual solvent in the optical compensation film or phosphoric acid as a phosphoric acid-based additive. It is preferable to make it contain in a film.

  As such an antioxidant, a hindered phenol compound is preferably used. For example, 2,6-di-t-butyl-p-cresol, pentaerythrityl-tetrakis [3- (3,5-di- -T-butyl-4-hydroxyphenyl) propionate], triethylene glycol-bis [3- (3-t-butyl-5-methyl-4-hydroxyphenyl) propionate], 1,6-hexanediol-bis [3 -(3,5-di-t-butyl-4-hydroxyphenyl) propionate], 2,4-bis- (n-octylthio) -6- (4-hydroxy-3,5-di-t-butylanilino)- 1,3,5-triazine, 2,2-thio-diethylenebis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], octa Sil-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate, N, N'-hexamethylenebis (3,5-di-t-butyl-4-hydroxy-hydrocinnamamide) 1,3,5-trimethyl-2,4,6-tris (3,5-di-t-butyl-4-hydroxybenzyl) benzene, tris- (3,5-di-t-butyl-4-hydroxy Benzyl) -isocyanurate and the like. In particular, 2,6-di-t-butyl-p-cresol, pentaerythrityl-tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], triethylene glycol-bis [3 -(3-t-butyl-5-methyl-4-hydroxyphenyl) propionate] is preferred. Further, for example, hydrazine-based metal deactivators such as N, N′-bis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyl] hydrazine and tris (2,4-di- A phosphorus processing stabilizer such as t-butylphenyl) phosphite may be used in combination.

The addition amount of these compounds is preferably 1 ppm to 1.0%, more preferably 10 to 1000 ppm in terms of mass ratio with respect to the cellulose derivative.
(3.6) Fine Particles The first and second optical compensation layers 3 and 5 in the present invention preferably contain fine particles.

  As fine particles used in the present invention, examples of inorganic compounds include silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide, calcium carbonate, calcium carbonate, talc, clay, calcined kaolin, calcined calcium silicate, and hydrated silicic acid. Mention may be made of calcium, aluminum silicate, magnesium silicate and calcium phosphate. Fine particles containing silicon are preferable in terms of low turbidity, and silicon dioxide is particularly preferable.

  The average primary particle diameter of the fine particles is preferably 5 to 400 nm, and more preferably 10 to 300 nm. These may be mainly contained as secondary aggregates having a particle size of 0.05 to 0.3 μm, and may be contained as primary particles without being aggregated if the particles have an average particle size of 100 to 400 nm. preferable. The content of these fine particles in the optical compensation films 3 and 5 is preferably 0.01 to 1% by mass, particularly preferably 0.05 to 0.5% by mass. In the case of the optical compensation films 3 and 5 having a multilayer structure formed by the co-casting method, it is preferable that the surface contains this amount of fine particles.

  Silicon dioxide fine particles are commercially available, for example, under the trade names Aerosil R972, R972V, R974, R812, 200, 200V, 300, R202, OX50, TT600 (above Nippon Aerosil Co., Ltd.). it can.

  Zirconium oxide fine particles are commercially available, for example, under the trade names Aerosil R976 and R811 (manufactured by Nippon Aerosil Co., Ltd.) and can be used.

  Examples of the polymer include silicone resin, fluororesin, and acrylic resin. Silicone resins are preferable, and those having a three-dimensional network structure are particularly preferable. For example, Tospearl 103, 105, 108, 120, 145, 3120, and 240 (manufactured by Toshiba Silicone Co., Ltd.) It is marketed by name and can be used.

  Among these, Aerosil 200V and Aerosil R972V are particularly preferably used because they have a large effect of reducing the friction coefficient while keeping the turbidity of the optical compensation film low. In the optical compensation films 3 and 5 used in the present invention, it is preferable that the dynamic friction coefficient of at least one surface is 0.2 to 1.0.

  Various additives may be batch-added to a dope that is a cellulose ester-containing solution before film formation, or an additive solution may be separately prepared and added in-line. In particular, it is preferable to add a part or all of the fine particles in-line in order to reduce the load on the filter medium.

  When the additive solution is added in-line, it is preferable to dissolve a small amount of cellulose ester in order to improve mixing with the dope. The amount of the cellulose ester is preferably 1 to 10 parts by mass, more preferably 3 to 5 parts by mass with respect to 100 parts by mass of the solvent.

In order to perform in-line addition and mixing in the present invention, for example, an in-line mixer such as a static mixer (manufactured by Toray Engineering) or SWJ (Toray static type in-tube mixer Hi-Mixer) is preferably used.
(3.7) Method for Producing Optical Compensation Film Next, a method for producing an optical compensation film as the first and second optical compensation layers 3 and 5 in the present invention will be described.

  The optical compensation film can be preferably used regardless of whether it is a film produced by a solution casting method or a film produced by a melt casting method.

  The optical compensation film of the present invention is produced by dissolving a cellulose ester and an additive in a solvent to prepare a dope, casting a dope on an endless metal support that moves infinitely, and casting the dope. It is carried out by a step of drying as a web, a step of peeling from a metal support, a step of stretching or maintaining the width, a step of further drying, and a step of winding up the finished film.

  The process for preparing the dope will be described. The concentration of cellulose ester in the dope is preferably higher because the drying load after casting on the metal support can be reduced. However, if the concentration of cellulose ester is too high, the load during filtration increases and the filtration accuracy is poor. Become. As a density | concentration which makes these compatible, 10-35 mass% is preferable, More preferably, it is 15-25 mass%.

  The solvent used in the dope may be used alone or in combination of two or more, but it is preferable to use a mixture of a good solvent and a poor solvent of cellulose ester in terms of production efficiency, and there are many good solvents. This is preferable from the viewpoint of the solubility of the cellulose ester. The preferable range of the mixing ratio of the good solvent and the poor solvent is 70 to 98% by mass for the good solvent and 2 to 30% by mass for the poor solvent. With a good solvent and a poor solvent, what dissolve | melts the cellulose ester to be used independently is defined as a good solvent, and what poorly swells or does not melt | dissolve is defined as a poor solvent. Therefore, depending on the average acetylation degree (acetyl group substitution degree) of the cellulose ester, the good solvent and the poor solvent change. For example, when acetone is used as the solvent, the cellulose ester acetate ester (acetyl group substitution degree 2.4), cellulose Acetate propionate is a good solvent, and cellulose acetate (acetyl group substitution degree 2.8) is a poor solvent.

  Although the good solvent used for this invention is not specifically limited, Organic halogen compounds, such as a methylene chloride, dioxolanes, acetone, methyl acetate, methyl acetoacetate, etc. are mentioned. Particularly preferred is methylene chloride or methyl acetate.

  Moreover, although the poor solvent used for this invention is not specifically limited, For example, methanol, ethanol, n-butanol, cyclohexane, cyclohexanone, etc. are used preferably. Moreover, it is preferable that 0.01-2 mass% of water contains in dope. Moreover, the solvent used for melt | dissolution of a cellulose ester collect | recovers the solvent removed from the film by drying at the film-forming process, and uses this again. The recovery solvent may contain trace amounts of additives added to the cellulose ester, such as plasticizers, UV absorbers, polymers, monomer components, etc., but even if these are included, they are preferably reused. Can be purified and reused if necessary.

  A general method can be used as a dissolution method of the cellulose ester when preparing the dope described above. When heating and pressurization are combined, it is possible to heat above the boiling point at normal pressure. It is preferable to stir and dissolve while heating at a temperature that is equal to or higher than the boiling point of the solvent at normal pressure and that the solvent does not boil under pressure, in order to prevent the generation of massive undissolved materials called gels and mamaco. Moreover, after mixing a cellulose ester with a poor solvent and making it wet or swell, the method of adding a good solvent and melt | dissolving is also used preferably.

  The pressurization may be performed by a method of injecting an inert gas such as nitrogen gas or a method of increasing the vapor pressure of the solvent by heating. Heating is preferably performed from the outside. For example, a jacket type is preferable because temperature control is easy.

  The heating temperature with the addition of a solvent is preferably higher from the viewpoint of the solubility of the cellulose ester, but if the heating temperature is too high, the required pressure increases and the productivity deteriorates. A preferable heating temperature is 45 to 120 ° C, more preferably 60 to 110 ° C, and still more preferably 70 ° C to 105 ° C. The pressure is adjusted so that the solvent does not boil at the set temperature.

  Alternatively, a cooling dissolution method is also preferably used, whereby the cellulose ester can be dissolved in a solvent such as methyl acetate.

  Next, this cellulose ester solution is filtered using a suitable filter medium such as filter paper. As the filter medium, it is preferable that the absolute filtration accuracy is small in order to remove insoluble matters and the like, but there is a problem that the filter medium is easily clogged if the absolute filtration accuracy is too small. For this reason, a filter medium with an absolute filtration accuracy of 0.008 mm or less is preferable, a filter medium with 0.001 to 0.008 mm is more preferable, and a filter medium with 0.003 to 0.006 mm is still more preferable.

  There are no particular restrictions on the material of the filter medium, and ordinary filter media can be used. However, plastic filter media such as polypropylene and Teflon (registered trademark), and metal filter media such as stainless steel do not drop off fibers. preferable. It is preferable to remove and reduce impurities, particularly bright spot foreign matter, contained in the raw material cellulose ester by filtration.

Bright spot foreign matter means that when two polarizing plates are placed in a crossed Nicol state, an optical film or the like is placed between them, light is applied from one polarizing plate side, and observation is performed from the other polarizing plate side. It is a point (foreign matter) where light from the opposite side appears to leak, and the number of bright spots having a diameter of 0.01 mm or more is preferably 200 / cm ² or less. More preferably, it is 100 pieces / cm < ² > or less, More preferably, it is 50 pieces / m < ² > or less, More preferably, it is 0-10 pieces / cm < ² > or less. Further, it is preferable that the number of bright spots of 0.01 mm or less is small.

  The dope can be filtered by a normal method, but the method of filtering while heating at a temperature not lower than the boiling point of the solvent at normal pressure and in a range where the solvent does not boil under pressure is the filtration pressure before and after filtration. The increase in the difference (referred to as differential pressure) is small and preferable. A preferred temperature is 45 to 120 ° C, more preferably 45 to 70 ° C, and still more preferably 45 to 55 ° C.

  A smaller filtration pressure is preferred. The filtration pressure is preferably 1.6 MPa or less, more preferably 1.2 MPa or less, and further preferably 1.0 MPa or less.

  Here, the dope casting will be described.

  The metal support in the casting (casting) step preferably has a mirror-finished surface. As the metal support, a stainless steel belt or a drum whose surface is plated with a casting is preferably used. The cast width can be 1 to 4 m. The surface temperature of the metal support in the casting step is −50 ° C. to a temperature lower than the boiling point of the solvent, and a higher temperature is preferable because the web can be dried faster. May deteriorate. A preferable support body temperature is 0-40 degreeC, and 5-30 degreeC is still more preferable. Alternatively, it is also a preferable method that the web is gelled by cooling and peeled from the drum in a state containing a large amount of residual solvent. The method for controlling the temperature of the metal support is not particularly limited, and there are a method of blowing hot air or cold air, and a method of contacting hot water with the back side of the metal support. It is preferable to use warm water because heat transfer is performed efficiently, so that the time until the temperature of the metal support becomes constant is short. When warm air is used, wind at a temperature higher than the target temperature may be used.

  In order for the optical compensation film to exhibit good flatness, the residual solvent amount when peeling the web from the metal support is preferably 10 to 150% by mass, more preferably 20 to 40% by mass or 60 to 130% by mass. Especially preferably, it is 20-30 mass% or 70-120 mass%.

  In the present invention, the amount of residual solvent is defined by the following formula.

Residual solvent amount (% by mass) = {(MN) / N} × 100
M is the mass of a sample collected during or after the production of the web or film, and N is the mass after heating M at 115 ° C. for 1 hour.

  In the step of drying the optical compensation film, the web is peeled off from the metal support and further dried, and the residual solvent amount is preferably 1% by mass or less, more preferably 0.1% by mass or less, Especially preferably, it is 0-0.01 mass% or less.

  In the film drying step, generally, a roll drying method (a method in which webs are alternately passed through a plurality of rolls arranged above and below) and a method in which the web is dried while being conveyed by a tenter method are employed.

  At this time, when an optical compensation film as the first optical compensation layer 3 is produced, it is preferable that a shrinkable film is bonded to the dried cellulose resin film and contracted while being stretched.

  Moreover, when manufacturing the optical compensation film as the 2nd optical compensation layer 5, it is preferable to perform a biaxial stretching process.

  In order to produce the optical compensation film of the present invention, it is particularly preferable to stretch in the width direction (lateral direction) by a tenter method in which both ends of the web are gripped by clips or the like. Peeling is preferably performed at a peeling tension of 300 N / m or less.

  The means for drying the web is not particularly limited, and can be generally performed with hot air, infrared rays, a heating roll, microwave, or the like, but it is preferably performed with hot air in terms of simplicity.

  The drying temperature in the web drying step is preferably increased stepwise from 40 to 200 ° C.

  Although the film thickness of an optical compensation film is not specifically limited, 10-200 micrometers is used. In particular, the film thickness is particularly preferably 10 to 100 μm. More preferably, it is 20-60 micrometers.

  The optical compensation film of the present invention has a width of 1 to 4 m. In particular, those having a width of 1.4 to 4 m are preferably used, and particularly preferably 1.6 to 3 m. If it exceeds 4 m, conveyance becomes difficult.

  According to the liquid crystal display device 1 described above, the liquid crystal molecules in the liquid crystal cell 4 are aligned in the thickness direction of the liquid crystal cell 4 during black display, and the first and second optical compensation layers 3 and 5 are nx1> nz1>. Since ny1, nx2 ≧ ny2> nz2, and DSP (Ro1) <1 <DSP (Rth2) are satisfied, the viewing angle can be enlarged, the front contrast can be improved, and color shift when viewed from an oblique direction can be prevented. (See Examples).

Although the liquid crystal display device according to the present invention has been described as the liquid crystal display device 1 shown in FIG. 1A in the first embodiment, the liquid crystal display device 1A shown in FIG. 1B may be used. . Here, in the liquid crystal display device 1 </ b> A of FIG. 1B, the first polarizer 2, the first optical compensation layer 3, the liquid crystal cell 4, The optical compensation layer 5 and the second polarizer 6 are laminated in this order, and the absorption axis 2J of the first polarizer 2 and the slow axis 3J of the first optical compensation layer 3 are parallel to each other. The absorption axis 2J of the first polarizer 2 and the absorption axis 6J of the second polarizer 6 are orthogonal, and the slow axis 3J of the first optical compensation layer 3 and the absorption axis 6J of the second polarizer 6 are. Are arranged so as to be orthogonal to each other. However, in FIG. 1B, the backlight is illustrated as the lower side in the figure, but may be the upper side.
[Second Embodiment]
Next, a second embodiment of the present invention will be described. In addition, the same code | symbol is attached | subjected to the component similar to the said 1st Embodiment, and the description is abbreviate | omitted.

  FIG. 2A is a conceptual diagram showing a schematic configuration of another liquid crystal display device 1D according to the present invention.

  As shown in this figure, the liquid crystal display device 1D includes a first polarizer 2, a first optical compensation layer 3D, a liquid crystal cell 4, and a second optical compensation layer from the viewing side toward the backlight side. 5 and the second polarizer 6 are stacked in this order. Further, the first optical compensation layer 3D includes a biaxial film (base film) 30 and a liquid crystal layer 31 in this order from the viewing side toward the backlight side.

  More specifically, the first polarizer 2, the second polarizer 6, and the biaxial film 30 have an absorption axis 2 </ b> J of the first polarizer 2 and a slow axis 30 </ b> J of the biaxial film 30. The absorption axis 2J of the first polarizer 2 and the absorption axis 6J of the second polarizer 6 are orthogonal to each other, and the slow axis 30J of the biaxial film 30 and the absorption of the second polarizer 6 are orthogonal to each other. It arrange | positions so that the axis | shaft 6J may become parallel. In FIG. 2, the backlight is illustrated as the lower side in the figure, but may be the upper side.

(First optical compensation layer)
The first optical compensation layer 3D in the present embodiment has a biaxial film 30 and a liquid crystal layer 30 and is laminated, and satisfies nx1>nz1> ny1 and DSP (Ro1) <1 as a whole. It is a Z plate with reverse wavelength dispersion. The first optical compensation layer 3D preferably has an in-plane retardation value Ro1 of 50 to 100 nm, and an absolute value of the retardation value Rth1 in the thickness direction of 0 nm to 20 nm.

  The first optical compensation layer 3D is preferably a film although its form is not limited. The thickness d of the film is preferably 40 to 100 μm, more preferably 40 to 70 μm.

<Biaxial film>
The biaxial film 30 is a film whose refractive index satisfies nx>ny> nz. As such a biaxial film 30, what stretched with respect to the cellulose resin film similar to the 1st optical compensation layer 3 in the said 1st Embodiment can be used.

<Intermediate layer>
In the optical compensation layer 3D of the present invention, an intermediate layer (alignment film, not shown) that assists the vertical alignment of the liquid crystal can be provided between the biaxial film 30 and the liquid crystal layer 31.

  The intermediate layer of the present invention is made of a transparent resin. The transparent resin is preferably a binder polymer having a saturated hydrocarbon chain or a polyether chain as a main chain, and more preferably a binder polymer having a saturated hydrocarbon chain as a main chain.

  Particularly preferred is a resin that is cured through a crosslinking reaction or the like by irradiation with active rays such as ultraviolet rays or electron beams, or a mixed composition of a crosslinking agent and a resin having a reactive site.

  Examples of the curable resin include UV curable urethane acrylate resins, UV curable polyester acrylate resins, UV curable epoxy acrylate resins, UV curable polyol acrylate resins, and UV curable epoxy resins. A type acrylate resin is preferably used.

  The UV curable urethane acrylate resin generally includes a product obtained by reacting a polyester polyol with an isocyanate monomer or a prepolymer, and further includes 2-hydroxyethyl acrylate and 2-hydroxyethyl methacrylate (hereinafter, acrylate includes methacrylate). It can be easily obtained by reacting an acrylate monomer having a hydroxyl group such as 2-hydroxypropyl acrylate.

  For example, those described in JP-A-59-151110 can be used. For example, a mixture of 100 parts of purple light UV-7510B (manufactured by Nippon Synthetic Chemical Co., Ltd.), Unidic 17-806 (manufactured by Dainippon Ink Co., Ltd.) and 1 part of coronate L (manufactured by Nippon Polyurethane Co., Ltd.) Preferably used.

  Examples of UV curable polyester acrylate resins include those which are easily formed when 2-hydroxyethyl acrylate and 2-hydroxy acrylate monomers are generally reacted with polyester polyols. JP-A-59-151112 Those described in the publication can be used.

  Specific examples of the ultraviolet curable epoxy acrylate resin include an epoxy acrylate as an oligomer, a reactive diluent and a photopolymerization initiator added thereto, and reacted to form an oligomer. Those described in Japanese Patent No. 105738 can be used.

  Specific examples of UV curable polyol acrylate resins include trimethylolpropane triacrylate, ditrimethylolpropane tetraacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol hexaacrylate, alkyl-modified dipentaerythritol pentaacrylate, etc. Can be mentioned.

  Specific examples of photopolymerization initiators for these curable resins include benzoin and its derivatives, acetophenone, benzophenone, hydroxybenzophenone, Michler's ketone, α-amyloxime ester, thioxanthone, and derivatives thereof. You may use with a photosensitizer.

  In addition, when using an epoxy acrylate photopolymerization initiator, a sensitizer such as n-butylamine, triethylamine, tri-n-butylphosphine can be used.

  The photopolymerization initiator or photosensitizer used in the curable resin composition is 0.1 to 25 parts by mass, preferably 1 to 15 parts by mass with respect to 100 parts by mass of the composition.

  As acrylate resins, methyl acrylate, ethyl acrylate, butyl acrylate, benzyl acrylate, cyclohexyl acrylate, ethylene glycol diacrylate, propylene glycol diacrylate, divinylbenzene, 1,4-cyclohexane diacrylate, 1,4-cyclohexyl dimethyl adiacrylate , Trimethylolpropane triacrylate, pentaerythritol tetraacrylic ester and the like.

  As these commercial products, Adekaoptomer KR / BY series: KR-400, KR-410, KR-550, KR-566, KR-567, BY-320B (manufactured by Asahi Denka Co., Ltd.); -101-KK, A-101-WS, C-302, C-401-N, C-501, M-101, M-102, T-102, D-102, NS-101, FT-102Q8, MAG -1-P20, AG-106, M-101-C (manufactured by Guangei Chemical Co., Ltd.); Seika Beam PHC2210 (S), PHCX-9 (K-3), PHC2213, DP-10, DP-20, DP- 30, P1000, P1100, P1200, P1300, P1400, P1500, P1600, SCR900 (manufactured by Dainichi Seika Kogyo Co., Ltd.); KRM7033, KRM7039 KRM 7130, KRM 7131, UVECRYL 29201, UVECRYL 29202 (manufactured by Daicel UCB); RC-5015, RC-5016, RC-5020, RC-5031, RC-5100, RC-5102, RC-5120, RC-5122, RC-5152, RC-5171, RC-5180, RC-5181 (manufactured by Dainippon Ink & Chemicals, Inc.); 340 clear (manufactured by China Paint Co., Ltd.); Sunrad H-601, RC-750, RC-700, RC-600, RC-500, RC-611, RC-612 (manufactured by Sanyo Chemical Industries); SP -1509, SP-1507 (manufactured by Showa Polymer Co., Ltd.); RCC-15C (manufactured by Grace Japan Co., Ltd.), Aronix M-6100, M-8030, M-8060 (manufactured by Toagosei Co., Ltd.), NK hard B-420, NK ester A-DOG, NK ester A-IBD-2E (manufactured by Shin-Nakamura Chemical Co., Ltd.) and the like can be appropriately selected and used.

  Other examples include trimethylolpropane triacrylate, ditrimethylolpropane tetraacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol hexaacrylate, dioxane glycol acrylate, ethoxylated acrylate, alkyl-modified dipentaerythritol pentaacrylate, etc. Can be mentioned.

  Examples of the mixed composition of the crosslinking agent and the resin having a reactive site according to the present invention include polyvinyl alcohol and glyoxal, gelatin and glyoxal.

  Further, the intermediate layer may contain a fluorine-acrylic copolymer resin. The fluorine-acrylic copolymer resin is a copolymer resin composed of a fluorine monomer and an acrylic monomer, and a block copolymer composed of a fluorine monomer segment and an acrylic monomer segment is particularly preferable.

(Method for producing intermediate layer)
The intermediate layer is coated with a coating composition for forming the intermediate layer on the biaxial film 30 using a known method such as a gravure coater, dip coater, reverse coater, wire bar coater, die coater, or ink jet method, and then dried by heating. And UV curing treatment is preferred.

  The coating amount is suitably 0.1 to 40 μm, preferably 0.5 to 30 μm, as the wet film thickness.

  Moreover, as a dry film thickness, it is an average film thickness of 0.01-1 micrometer, Preferably it is 0.02-0.7 micrometer.

  As the light source for the UV curing treatment, any light source that generates ultraviolet rays can be used without limitation. For example, a low pressure mercury lamp, a medium pressure mercury lamp, a high pressure mercury lamp, an ultrahigh pressure mercury lamp, a carbon arc lamp, a metal halide lamp, a xenon lamp, or the like can be used.

Irradiation conditions vary depending on each lamp, but the irradiation amount of active rays is usually 5 to 500 mJ / cm ² , preferably 5 to 150 mJ / cm ² .

  Moreover, when irradiating actinic radiation, it is preferable to carry out while applying tension | tensile_strength in the conveyance direction of the biaxial film 30, More preferably, it is performing applying tension | tensile_strength also in the width direction. The tension to be applied is preferably 30 to 300 N / m.

  The method for applying tension is not particularly limited, and tension may be applied in the transport direction on the back roll, or tension may be applied in the width direction or biaxial direction by a tenter. This makes it possible to obtain a film having further excellent flatness.

  The coating composition for forming the intermediate layer may contain a solvent. Examples of the organic solvent contained in the coating composition include hydrocarbons (toluene, xylene), alcohols (methanol, ethanol, isopropanol, butanol, cyclohexanol), and ketones (acetone, methyl ethyl ketone, methyl isobutyl ketone). , Esters (methyl acetate, ethyl acetate, methyl lactate), glycol ethers, and other organic solvents may be appropriately selected or mixed for use.

  As the organic solvent, propylene glycol monoalkyl ether (1 to 4 carbon atoms of the alkyl group) or propylene glycol monoalkyl ether acetate (1 to 4 carbon atoms of the alkyl group) is preferable. Moreover, as content of an organic solvent, 5-80 mass% is preferable in a coating composition.

<Liquid crystal layer>
The liquid crystal layer 31 has a refractive index satisfying nz> nx = ny and is a so-called positive C plate. The liquid crystal layer 31 preferably has the following characteristics.

0 ≦ Ro ≦ 10
−500 ≦ Rth ≦ −100
The liquid crystal layer 31 is formed by applying a liquid crystal material or a liquid crystal solution directly on the biaxial film 30 or on the intermediate layer, drying and heat-treating (also referred to as alignment treatment), and curing the liquid crystal by ultraviolet curing or thermal polymerization. And has a phase difference due to a rod-like liquid crystal aligned in the vertical direction.

  Here, “orienting in the vertical direction” means that the rod-like liquid crystal is within a range of 70 to 90 ° (the vertical direction is 90 °) with respect to the film surface of the biaxial film 30 as a support.

  The rod-shaped liquid crystal may be aligned obliquely with respect to the biaxial film 30 or may be aligned by gradually changing the alignment angle. Preferably it is the range of 80-90 degrees.

  The liquid crystal layer 31 is a retardation layer made of rod-like liquid crystal aligned in the vertical direction in which Ro is in the range of 0 to 10 nm and Rth is in the range of −500 to −100 nm. Further, Ro is more preferably in the range of 0 to 5 nm.

  When the liquid crystal layer 31 is formed by aligning rod-shaped liquid crystals, the above-described intermediate layer (alignment film) coated with a vertical alignment agent that aligns the so-called liquid crystal material in the vertical direction is used to vertically align the liquid crystal material. Later, it can be fixed.

  When the liquid crystal material itself is aligned in the vertical direction at the air interface, the alignment regulating force extends to the interface opposite to the air interface, and the alignment film is not particularly necessary, and this is preferable from the viewpoint of simplifying the configuration. .

  As a specific method for vertically aligning the liquid crystal material, as described in JP-A-2005-148473, an alignment film composed of a cross-linked product of a block polymer composition containing a (meth) acrylic block polymer, etc. As described in JP 2005-265889 A, a known method such as a method using a vertical alignment film or a method using an air interface vertical alignment agent can be used.

  In order to make the liquid crystal layer 31 in the range of the characteristics of Ro and Rth, the orientation of the rod-like liquid crystal layer, the film thickness control, the temperature during UV curing, the tilt angle control, and the support (biaxial film 30) and air It is preferable to control the pretilt angle at the interface.

  The liquid crystal layer 31 is formed by curing a liquid crystal material that can be in a liquid crystal phase at a predetermined temperature and having a predetermined liquid crystal regularity. The upper limit of the temperature showing the liquid crystal phase is not particularly limited as long as the cellulose ester film of the base material is not damaged.

  Specifically, a temperature of 120 ° C. or lower is preferable from the viewpoint of easy control of process temperature and maintenance of dimensional accuracy, and a liquid crystal material that becomes a liquid crystal phase at a temperature of 100 ° C. or lower is preferably used. On the other hand, the lower limit of the temperature showing the liquid crystal phase can be said to be a temperature at which the liquid crystal material can maintain the alignment state when used as a polarizing plate.

  As the liquid crystal material used for the liquid crystal layer 31, a polymerizable liquid crystal material is preferably used. The polymerizable liquid crystal material can be used by being polymerized by irradiating with predetermined actinic radiation. In the polymerized state, the vertical alignment state is fixed.

  As the polymerizable liquid crystal material, any of a polymerizable liquid crystal monomer, a polymerizable liquid crystal oligomer, and a polymerizable liquid crystal polymer can be used, and they can also be mixed with each other.

  Of the above, a polymerizable liquid crystal monomer is preferably used as the polymerizable liquid crystal material because of its high sensitivity during alignment and easy vertical alignment.

  Specific examples of the polymerizable liquid crystal monomer include a rod-like liquid crystal compound (I) represented by the following general formula (1) and a rod-like liquid crystal compound (II) represented by the following general formula (2). be able to. As the compound (I), two or more compounds included in the general formula (1) can be mixed and used. Similarly, the compound (II) is included in the general formula (2). Two or more kinds of compounds may be mixed and used. Moreover, 1 or more types of compound (I) and 1 or more types of compound (II) can also be mixed and used.

In the general formula (1) representing the compound (I), R ¹ and R ² each represent hydrogen or a methyl group, but R ¹ and R ² must be both hydrogen because of the wide temperature range showing the liquid crystal phase. preferable.

  X may be hydrogen, chlorine, bromine, iodine, an alkyl group having 1 to 4 carbon atoms, a methoxy group, a cyano group, or a nitro group, but is preferably chlorine or a methyl group.

  Moreover, a and b which show the chain length of the alkylene group which is a spacer with the (meth) acryloyloxy group of both ends of the molecular chain of a compound (I), and an aromatic ring are respectively arbitrary integers in the range of 2-12. Although it can take, it is preferable that it is the range of 4-10, and it is more preferable that it is the range of 6-9.

  In addition to the above, in the present invention, conventionally known materials can be appropriately selected and used as the polymerizable liquid crystal oligomer and the polymerizable liquid crystal polymer.

  For example, as a 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 Yes.

  In the present invention, a photopolymerization initiator is used as required in addition to the polymerizable liquid crystal material. When polymerizing a polymerizable liquid crystal material by electron beam irradiation, a photopolymerization initiator may not be necessary. However, in the case of curing by, for example, ultraviolet (UV) irradiation, which is generally used, photopolymerization is usually performed. An initiator is used to promote polymerization.

  Photopolymerization initiators include benzyl (also called bibenzoyl), benzoin isobutyl ether, benzoin isopropyl ether, benzophenone, benzoyl benzoic acid, methyl benzoyl benzoate, 4-benzoyl-4'-methyldiphenyl sulfide, benzyl methyl ketal, dimethylamino Methylbenzoate, 2-n-butoxyethyl-4-dimethylaminobenzoate, isoamyl p-dimethylaminobenzoate, 3,3′-dimethyl-4-methoxybenzophenone, methylobenzoylformate, 2-methyl-1- (4 -(Methylthio) phenyl) -2-morpholinopropan-1-one, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butan-1-one, 1- (4-dodecylphenyl) -2- Droxy-2-methylpropan-1-one, 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1- (4-isopropylphenyl) -2-hydroxy-2- Examples include methylpropan-1-one, 2-chlorothioxanthone, 2,4-diethylthioxanthone, 2,4-diisopropylthioxanthone, 2,4-dimethylthioxanthone, isopropylthioxanthone, or 1-chloro-4-propoxythioxanthone. it can.

  In general, the addition amount of the photopolymerization initiator is preferably 0.01% to 20%, more preferably 0.1% to 10%, and still more preferably 0.5% to 5%. Can be added to the polymerizable liquid crystal material of the present invention.

  In addition to the photopolymerization initiator, a sensitizer can be added as long as the object of the present invention is not impaired.

  The film thickness of the liquid crystal layer 31 in the present invention is preferably in the range of 0.1 μm to 10 μm, and more preferably in the range of 0.2 to 5 μm.

  A polymerizable liquid crystal material is used by preparing a composition for forming a liquid crystal layer by blending a photopolymerization initiator, a sensitizer, and the like, if necessary, and coating the substrate (biaxial film 30). A liquid crystal layer forming layer is formed.

  As a method of forming a layer in which the alignment of liquid crystal is fixed, for example, a dry film or the like is formed in advance and a layer in which the alignment of liquid crystal is fixed is laminated on a substrate, or a liquid crystal composition is dissolved. Alternatively, it is possible to use a method of melting and coating on a substrate, but in the present invention, a liquid crystal composition is added with a solvent and a coating composition in which other components are dissolved is used. It is preferable to form a layer in which the orientation of the liquid crystal is fixed by coating on the substrate and removing the solvent. This is simple in terms of process as compared with other methods.

  The solvent is not particularly limited as long as it is a solvent capable of dissolving the above-described polymerizable liquid crystal material and the like and does not deteriorate the properties of the transparent resin film. Specifically, benzene, Hydrocarbons such as toluene, xylene, n-butylbenzene, diethylbenzene, tetralin; ethers such as methoxybenzene, 1,2-dimethoxybenzene, diethylene glycol dimethyl ether; acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, or 2,4- Ketones such as pentanedione; ethyl acetate, ethylene glycol monomethyl ether acetate, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, or γ-butyrolactone Amides solvents such as 2-pyrrolidone, N-methyl-2-pyrrolidone, dimethylformamide or dimethylacetamide; chloroform, dichloromethane, carbon tetrachloride, dichloroethane, tetrachloroethane, tritrichloroethylene, tetrachloroethylene, chlorobenzene, or orthodichlorobenzene Halogen solvents such as t-butyl alcohol, diacetone alcohol, glycerin, monoacetin, ethylene glycol, triethylene glycol, hexylene glycol, ethylene glycol monomethyl ether, ethyl cellosolve, or butyl cellosolve; phenols, One or more of phenols such as parachlorophenol can be used.

  If only a single kind of solvent is used, the solubility of the polymerizable liquid crystal material or the like may be insufficient, or the substrate (biaxial film 30) may be eroded as described above. However, this inconvenience can be avoided by using a mixture of two or more solvents.

  Of the above-mentioned solvents, preferred as a single solvent are a hydrocarbon solvent and a glycol monoether acetate solvent, and a preferred mixed solvent is a mixed system of ethers or ketones and glycols. It is.

  The concentration of the solution depends on the solubility of the polymerizable liquid crystal material or the like and the film thickness of the liquid crystal layer to be produced, but cannot be defined unconditionally, but is usually preferably 1% to 60%, more preferably 3% to It is adjusted within the range of 40%.

  Compounds other than those described above can be added to the composition for forming a liquid crystal layer used in the present invention within a range not impairing the object of the present invention.

  Examples of compounds that can be added include polyester (meth) acrylate obtained by reacting (meth) acrylic acid with a polyester prepolymer obtained by condensing polyhydric alcohol and monobasic acid or polybasic acid; A polyurethane (meth) acrylate obtained by reacting a compound having two isocyanate groups with each other and then reacting the reaction product with (meth) acrylic acid; bisphenol A type epoxy resin, bisphenol F type epoxy resin, novolak Type epoxy resin, polycarboxylic acid polyglycidyl ester, polyol polyglycidyl ether, aliphatic or cycloaliphatic epoxy resin, amine epoxy resin, triphenolmethane type epoxy resin, dihydroxybenzene type epoxy resin and the like (meth) Ak A photopolymerizable compound such as epoxy (meth) acrylate obtained by reacting phosphoric acid, a photopolymerizable liquid crystal compound having an acrylic group or a methacryl group, an onium salt described in JP-A-2007-45993, and a fluorine compound. Acrylate polymers and the like.

  The amount of these compounds added to the composition for forming a liquid crystal layer of the present invention is selected within a range that does not impair the purpose of the present invention, and is generally 40% or less of the composition for forming a liquid crystal layer of the present invention. Preferably, it is 20% or less.

  Addition of these compounds improves the curability of the liquid crystal material in the present invention, increases the mechanical strength of the resulting liquid crystal layer, and improves its stability.

  In addition, a surfactant or the like can be added to the composition for forming a liquid crystal layer containing a solvent in order to facilitate coating.

  Examples of surfactants that can be added include cationic surfactants such as imidazoline, quaternary ammonium salts, alkylamine oxides and polyamine derivatives; polyoxyethylene-polyoxypropylene condensates, primary or secondary Alcohol ethoxylates, alkylphenol ethoxylates, polyethylene glycol and esters thereof, sodium lauryl sulfate, ammonium lauryl sulfate, lauryl sulfate amines, alkyl-substituted aromatic sulfonates, alkyl phosphates, aliphatic or aromatic sulfonic acid formalin condensates, etc. Anionic surfactants; amphoteric surfactants such as laurylamidopropylbetaine and laurylaminoacetic acid betaine; nonionics such as polyethylene glycol fatty acid esters and polyoxyethylene alkylamine Surfactant: Perfluoroalkyl sulfonate, perfluoroalkyl carboxylate, perfluoroalkyl ethylene oxide adduct, perfluoroalkyl trimethyl ammonium salt, perfluoroalkyl group / hydrophilic group-containing oligomer, perfluoroalkyl / lipophilic group Fluorosurfactants such as containing oligomer perfluoroalkyl group-containing urethanes.

  The amount of surfactant added depends on the type of surfactant, the type of liquid crystal material, the type of solvent, and the type of alignment film on which the solution is applied. 10 ppm to 10% is preferable, more preferably 100 ppm to 5%, and still more preferably 0.1 to 1%.

  As a method for coating the composition for forming a liquid crystal layer, a spin coating method, a roll coating method, a printing method, a dip pulling method, a die coating method, a casting method, a bar coating method, a blade coating method, a spray coating method, a gravure coating method , Reverse coating method or extrusion coating method.

  The method for removing the solvent after coating the composition for forming a liquid crystal layer is performed, for example, by air drying, heat removal, or removal under reduced pressure, or a combination thereof. By removing the solvent, a layer in which the alignment of the liquid crystal is fixed is formed.

  In the step of curing the polymerizable liquid crystal material, energy for curing the polymerizable liquid crystal material is given, and thermal energy may be used, but it is usually performed by irradiation with ionizing radiation capable of causing polymerization.

  If necessary, a polymerization initiator may be contained in the polymerizable liquid crystal material. The ionizing radiation is not particularly limited as long as it is a radiation capable of polymerizing the polymerizable liquid crystal material, but usually ultraviolet light or visible light is used from the viewpoint of the ease of the apparatus, and the wavelength. Is preferably from 150 to 500 nm, more preferably from 250 to 450 nm, and even more preferably from 300 to 400 nm.

  In the present invention, a method of performing radical polymerization by irradiating ultraviolet rays (UV) as actinic radiation and generating radicals from the polymerization initiator with ultraviolet rays is preferable. Since the method using UV as the actinic radiation is an already established technique, it can be easily applied to the present invention including the polymerization initiator to be used.

  As a light source for irradiating ultraviolet rays, a low-pressure mercury lamp (sterilization lamp, fluorescent chemical lamp, black light), a high-pressure discharge lamp (high-pressure mercury lamp, metal halide lamp), or a short arc discharge lamp (ultra-high-pressure mercury lamp, xenon) Lamp, mercury xenon lamp) and the like.

  In particular, the use of metal halide lamps, xenon lamps, high-pressure mercury lamps, etc. is recommended. The irradiation intensity may be appropriately adjusted depending on the composition of the polymerizable liquid crystal material used for forming the layer in which the alignment of the liquid crystal is fixed and the amount of the photopolymerization initiator.

  The alignment fixing step by irradiation with actinic radiation may be performed at the processing temperature in the step of forming the liquid crystal layer forming layer described above, that is, the temperature condition in which the polymerizable liquid crystal material becomes a liquid crystal phase, It may be performed at a lower temperature.

  According to the above liquid crystal display device 1D, the same effect as that of the first embodiment can be obtained, and the first optical compensation layer 3D is formed of a biaxial film 30 and a positive C plate. Since the liquid crystal layer 31 has a laminated structure, the phase difference to be imparted to the optical compensation layer in order to produce a viewing angle widening effect as compared with the case where the first optical compensation layer is composed of a single layer. Can be significantly reduced in size. Specifically, when the first optical compensation layer is composed of a single layer, a very large phase difference of retardation value Ro≈275 is applied to the optical compensation layer in order to produce a viewing angle expansion effect. In the first optical compensation layer 3D, if the phase difference less than a half of the retardation value Ro = 50 to 100 is given to the entire optical compensation layer 3D, the viewing angle widening effect is required. Can be issued. Therefore, unlike the case where the first optical compensation layer is formed of a single layer, it is possible to prevent the optical compensation layer from amplifying the influence of slight variations in the optical axis. And the front contrast can be kept high (see the examples).

  Although the liquid crystal display device according to the present invention has been described as the liquid crystal display device 1D shown in FIG. 2A in the second embodiment, the liquid crystal display device 1E shown in FIG. . Here, in the liquid crystal display device 1E of FIG. 2B, the first polarizer 2, the liquid crystal layer 31 of the first optical compensation layer 3D, and the biaxial film 30 from the viewing side toward the backlight side. The liquid crystal cell 4, the second optical compensation layer 5, and the second polarizer 6 are laminated in this order. The absorption axis 2J of the first polarizer 2 and the retardation of the biaxial film 30 are laminated. The phase axis 30J is parallel, the absorption axis 2J of the first polarizer 2 and the absorption axis 6J of the second polarizer 6 are orthogonal, the slow axis 30J of the biaxial film 30 and the second axis It arrange | positions so that the absorption axis 6J of the polarizer 6 may orthogonally cross. However, in FIG. 2B, the backlight is illustrated as the lower side in the figure, but may be the upper side.

  Further, the present invention should not be construed as being limited to the first and second embodiments described above, and can be changed or improved as appropriate.

  For example, the liquid crystal display device of the present invention is not limited to the configuration shown in FIGS. 1 and 2 and may include other members. For example, a color filter is disposed between the liquid crystal cell 4 and the polarizers 2 and 6. May be. Further, the surface of the protective film of the polarizers 2 and 6 may be subjected to an antireflection treatment or a hard coat. Moreover, you may use what gave electroconductivity to the structural member. In the case of use as a transmission type, a cold cathode or a hot cathode fluorescent tube, or a backlight having a light emitting diode, a field emission element, or an electroluminescent element as a light source can be disposed on the back surface. In this case, the arrangement of the backlight may be on the upper side or the lower side of FIGS. In addition, a reflective polarizing plate, a diffusion plate, a prism sheet, or a light guide plate can be disposed between the liquid crystal cell 4 and the backlight. Further, as described above, the liquid crystal display device of the present invention may be of a reflective type. In such a case, only one polarizing plate may be disposed on the viewing side. A reflective film is disposed on the inner surface of the lower glass substrate 41. Of course, a front light using the light source may be provided on the liquid crystal cell viewing side.

EXAMPLES The present invention will be specifically described below with reference to examples and comparative examples, but the present invention is not limited to these.
<< Production of optical compensation films Z1-Z9 >>
As samples of the first optical compensation film 3 in the above embodiment, optical compensation films Z1 to Z9 as shown in Table 1 below were produced.

(Preparation of cellulose ester mixture)
Cellulose ester A (cellulose acetate propionate)
100 parts by weight Additive 1 10 parts by weight Methylene chloride 300 parts by weight Ethanol 52 parts by weight The above was put into a sealed container and completely dissolved with heating and stirring, and then Azumi filter paper No. 1 manufactured by Azumi Filter Paper Co., Ltd. 24 was used to prepare a cellulose ester mixture. This mixture was filtered through Finemet NF manufactured by Nippon Seisen Co., Ltd.

  However, the above-mentioned cellulose ester A is a cellulose ester having an acetyl group substitution degree of 1.6 and a propionyl group substitution degree of 0.9 as shown in Table 2 below. Further, the above-mentioned additive 1 is a sugar ester compound represented by the following compound 3 as shown in Table 3 below.

(Preparation of silicon dioxide dispersion dilution)
Aerosil 972V (manufactured by Nippon Aerosil Co., Ltd.) 10 parts by mass (average primary particle diameter 16 nm, apparent specific gravity 90 g / liter)
Ethanol 80 parts by mass The above was stirred and mixed with a dissolver for 30 minutes, and then dispersed with Manton Gorin to prepare a silicon dioxide dispersion. The liquid turbidity after dispersion was 200 ppm. 80 parts by mass of methylene chloride was added to this silicon dioxide dispersion with stirring, and the mixture was stirred and mixed for 30 minutes with a dissolver to prepare a silicon dioxide dispersion dilution.

(Preparation of dope solution 1)
10 parts by mass of the silicon dioxide dispersion dilution was added to 100 parts by mass of the cellulose ester mixture obtained as described above, and the mixture was stirred well to obtain a dope solution 1.

(Preparation of base film A1 of optical compensation film Z1)
Using a belt casting apparatus, the dope solution 1 was uniformly cast on a stainless steel band support at a temperature of 35 ° C. and a width of 1800 mm. With the stainless steel band support, the solvent was evaporated until the amount of residual solvent reached 100%, and then peeled off from the stainless steel band support. The solvent of the web of the peeled cellulose ester film was evaporated at 55 ° C., and stretched 1.40 times in the width direction using a tenter while applying heat at 140 ° C. to 160 ° C. The residual solvent at the start of stretching was 15%. Then, drying was completed while transporting the drying zone at 130 ° C. with many rolls, knurling with a width of 15 mm and an average height of 10 μm was applied to both ends of the film, and the initial winding tension was 220 N / m and the final tension was 110 N / m. The film was wound around a core to obtain a base film (biaxial film) A1 of the optical compensation film Z1 having a dry film thickness of 60 μm.

(Preparation of base films A2 to 5, 8, and 9 of optical compensation films Z2 to 5,8,9)
Further, as shown in Table 1 above, a dope solution is prepared almost in the same manner as the base film A1 except that the cellulose ester species, additive species, additive amount, film thickness, and stretching ratio in the width direction are changed. Then, base film A2-5,8,9 of optical compensation film Z2-5,8,9 was produced.

  However, in Table 1, “B” and “C” in the “resin” column indicate cellulose esters B and C in Table 2 above, and C is specifically ε-caprolactone grafted per mole of glucose unit. The average number of moles (MS) is 0.72, the average degree of substitution (DS) of the graft chain (grafted caprolactone) is 0.3, the average degree of polymerization (DPn) of ε-caprolactone of the graft chain is 5.4, hydroxyl A group having an average degree of substitution DS (OH) of 0.3 was used. Further, “additive 2” in the “additive type” column indicates additive 2 (acrylic compound) in Table 3 above, specifically, an acrylic compound synthesized as follows.

(Synthesis of acrylic compounds)
In a glass flask equipped with a stirrer, two dropping funnels, a gas introduction tube and a thermometer, 40 g of a monomer Xa and Xb mixed solution of the types and ratios (molar composition ratios) shown in Table 4 below, a mercaptopropionic acid chain transfer agent 2 g and 30 g of toluene were charged, and the temperature was raised to 90 ° C. Thereafter, 60 g of a mixture of monomers Xa and Xb having the types and ratios (molar composition ratios) shown in Table 4 was dropped from one dropping funnel over 3 hours, and at the same time, azobisiso dissolved in 14 g of toluene from the other funnel. 0.4 g of butyronitrile was added dropwise over 3 hours. Thereafter, 0.6 g of azobisisobutyronitrile dissolved in 56 g of toluene was added dropwise over 2 hours, and the reaction was further continued for 2 hours to obtain polymer X. The obtained polymer X was solid at room temperature. The weight average molecular weight of the polymer X is shown in Table 4 by the following measurement method.

  In addition, MMA and HEA described in Table 4 are abbreviations of the following compounds, respectively.

MMA: methyl methacrylate HEA: 2-hydroxyethyl acrylate (weight average molecular weight measurement)
The weight average molecular weight was measured using gel permeation chromatography.

  The measurement conditions are as follows.

Solvent: Methylene chloride Column: Shodex K806, K805, K803G (Used by connecting three Showa Denko Co., Ltd.)
Column temperature: 25 ° C
Sample concentration: 0.1% by mass
Detector: RI Model 504 (manufactured by GL Sciences)
Pump: L6000 (manufactured by Hitachi, Ltd.)
Flow rate: 1.0ml / min
Calibration curve: Standard polystyrene STK standard polystyrene (manufactured by Tosoh Corp.) Mw = 100000-500 calibration curves with 13 samples were used. Thirteen samples are used at approximately equal intervals.
<Preparation of optical compensation film Z1>
By forming an intermediate layer and a liquid crystal layer on the base film A1 obtained as described above, an optical compensation film Z1 was prepared as shown in Table 1 above.

(Formation of intermediate layer)
25 parts by mass of urethane acrylate oligomer (UV-7510B Nippon Synthetic Chemical Co., Ltd.)
Propylene glycol monomethyl ether 290 parts by mass Isopropyl alcohol 685 parts by mass Photopolymerization initiator 0.05 part by mass (Lucirin TPO (manufactured by BASF Corporation))
This coating solution was applied onto the base film A1 with a wire bar # 3, dried at 80 ° C. for 30 seconds, and then cured by irradiating with ultraviolet rays of 120 mJ / mm for 10 seconds to form an intermediate layer. The film thickness of the intermediate layer after drying was 0.5 μm.

(Formation of liquid crystal layer (anisotropic layer))
UV-polymerizable liquid crystal material 20 parts by mass (UCL018 manufactured by Dainippon Ink & Chemicals, Inc.)
Propylene glycol monomethyl ether acetate 80 parts by mass Photopolymerization initiator 0.04 parts by mass (Lucirin TPO (manufactured by BASF Corporation))
Hindered amine 0.02 parts by mass LS-765 (manufactured by Sankyo Lifetech Co., Ltd.)
Vertical alignment agent 0.03 mass part (Shin-Etsu Silicone Co., Ltd. X-22-161A)
This polymerizable liquid crystal layer coating solution was applied onto the intermediate layer by a die coater. The liquid crystal layer was heated and dried in an 80 ° C. atmosphere for 1 minute until the temperature of the liquid crystal layer reached 65 ° C., and then rapidly cooled to 28 ° C. to align the liquid crystal material.

  It has been confirmed in advance that the ultraviolet-polymerizable liquid crystal compound has a solid-liquid crystal phase transition temperature of 23 ° C. and a liquid crystal phase-isotropic liquid phase transition temperature of 70 ° C.

After aligning the liquid crystal material, the liquid crystal layer was irradiated with UV light of 250 mJ / mm for 10 seconds at an oxygen concentration of 0.2% and a temperature of 28 ° C. to cure the polymerizable liquid crystal composition, thereby forming a liquid crystal layer. The thickness of the liquid crystal layer was 1.2 μm.
<Preparation of optical compensation films Z2-4, 8, 9>
As shown in Table 1 above, the optical compensation films Z2-4, 8, 9 are used in substantially the same manner as the optical compensation film Z1 except that the substrate films A2-4, 8, 9 are used and the liquid crystal film thickness is changed. Was made.
<Preparation of optical compensation film Z5>
As shown in Table 1 above, the base film A5 was used as the optical compensation film Z5 as it was.
<Preparation of optical compensation film Z6>
Shrinkable via an acrylic pressure-sensitive adhesive layer (thickness 15 μm) on both sides of a film A6 produced in the same manner as the base film A2, except that the draw ratio in the width direction was 1.01 and the film thickness was 150 μm. A film (trade name “Trephan BO2873” manufactured by Toray Industries, Inc.) was bonded together. After that, the film longitudinal direction was held with a roll stretching machine, and 1.5 times in the longitudinal direction in an air circulation oven at 180 ° C. Then, the shrinkable film was peeled off together with the acrylic pressure-sensitive adhesive layer to prepare an optical compensation film Z6.
<Preparation of optical compensation film Z7>
An acrylic adhesive layer (thickness 15 μm) on both sides of ZEONOR ZF-14-100 (average refractive index = 1.52, Tg = 136 ° C., Ro = 3.0 nm, Rth = 5.0 nm, manufactured by Optes Co., Ltd.) A shrinkable film (manufactured by Toray Industries, Inc., trade name “Trephan BO2873”) was attached. Thereafter, the film longitudinal direction is held with a roll stretching machine, and stretched 1.38 times in the longitudinal direction in an air circulation oven at 146 ° C. After stretching, the shrinkable film is peeled off together with the acrylic pressure-sensitive adhesive layer. Thus, an optical compensation film Z7 was produced.
<< Production of optical compensation films C1-C8 >>
As samples of the second optical compensation film 5 in the above embodiment, optical compensation films C1 to C8 as shown in Table 5 below were produced.

Specifically, the cellulose ester species, additive species, additive amount, and film thickness are changed, and the substrate film A1 is formed except for stretching in the longitudinal direction by applying conveyance tension after stretching in the width direction with a tenter. Optical compensation films C1 to C8 were prepared in the same manner as the preparation. The additive material types in Table 5 are as shown in Table 3, DSP value increasing agent 1 indicates an aromatic terminal polyester compound 18, and DSP value increasing agent indicates a triazine compound.
≪Evaluation of optical compensation film≫
<Measurement of retardation values Ro and Rth>
The retardation values of the optical compensation films Z1 to Z9 and C1 to C8 were measured using an automatic birefringence meter (manufactured by Oji Scientific Instruments, KOBRA-21ADH).

  Specifically, after measuring the three-dimensional refractive index of the optical compensation film at 10 locations at a wavelength of 590 nm in an environment of 23 ° C. and 55% RH, and obtaining the average values of the refractive indexes nx, ny and nz The retardation value Ro in the in-plane direction and the retardation value Rth in the thickness direction were calculated according to the following formula. The results are shown in Table 6 below.

Ro = (nx−ny) × d
Rth = {(nx + ny) / 2−nz} × d
In the formula, Ro is the retardation value in the film plane, Rth is the retardation value in the film thickness direction, nx is the refractive index in the slow axis direction in the film plane, ny is the refractive index in the fast axis direction in the film plane. , Nz represents the refractive index in the thickness direction of the film, and d represents the thickness (nm) of the film.

  From the values of the retardation values Ro1 and Rth1 of the first optical compensation layer in Table 6, the optical compensation films Z1 to Z4, Z6, Z8, and Z9 according to the present invention are Ro> 0 and −Ro / 2 <Rth. Since it is <Ro / 2, it turns out that nx1> nz1> ny1 (: Formula (1)) is satisfy | filled.

  Further, from the values of the retardation values Ro2 and Rth2 of the second optical compensation layer, the optical compensation films C1 to C6 according to the present invention satisfy Ro ≧ 0 and Rth> Ro / 2, and thus nx2 ≧ ny2>. It can be seen that nz2 (: Formula (2)) is satisfied.

Furthermore, it can be seen that the optical compensation layers used in the liquid crystal display devices 1 to 8 of the present invention satisfy DSP (Ro1) <1 <DSP (Rth2) (: Formula (3)) as wavelength dispersion.
≪Preparation of polarizing plate≫
A polyvinyl alcohol film having a thickness of 120 μm was uniaxially stretched (temperature: 110 ° C., stretch ratio: 5 times). This was immersed in an aqueous solution composed of 0.075 g of iodine, 5 g of potassium iodide and 100 g of water for 60 seconds, and then immersed in an aqueous solution of 68 ° C. composed of 6 g of potassium iodide, 7.5 g of boric acid and 100 g of water. This was washed with water and dried to obtain a polarizer.

  Subsequently, according to the following steps 1 to 5, the optical compensation films Z1 to 9 or the optical compensation films C1 to 8 are provided on the front surface side of the polarizer, and the Konica Minolta tack KC4UY (cellulose ester manufactured by Konica Minolta Opto Co., Ltd.) is provided on the back surface side. Film) as a polarizing plate protective film, and polarizing plates Z11 to 19 and C11 to 18 were produced. However, the optical compensation films Z1 to 4, 8, and 9 were bonded to the polarizer such that the base film side was the polarizer side (the liquid crystal layer side was the opposite side of the polarizer).

  Step 1: A film (optical compensation film, cellulose ester film) immersed in a 2 mol / L sodium hydroxide solution at 60 ° C. for 90 seconds, then washed with water and dried to saponify the side to be bonded to the polarizer. Got.

  Process 2: The said polarizer was immersed in the polyvinyl alcohol adhesive tank of 2 mass% of solid content for 1-2 seconds.

  Step 3: Excess adhesive adhered to the polarizer in Step 2 was lightly wiped off, and this was sandwiched and laminated between the optical compensation film treated in Step 1 and the cellulose ester film.

Step 4: pressure 20-30 N / cm ² to laminate obtained by laminating at Step 3, was stuck at about 2m / min conveyor speed.

Process 5: The sample bonded in the process 4 in an 80 degreeC dryer was dried for 2 minutes, and the polarizing plates Z11-19 and C11-18 were produced.
≪Production of liquid crystal display device≫
Strip the polarizing plates on both sides of a commercially available 32-inch MVA liquid crystal television (“Aquos 32AD5” manufactured by Sharp. However, “Aquos” is a registered trademark), and the polarizing plates Z11 to 19 and C11 to 18 produced above are shown in Table 6. The liquid crystal display devices (1) to (11) were prepared by pasting on both sides so as to be combined. At that time, the direction of bonding of the polarizing plate was such that the optical compensation film side (the side opposite to Konica Minoltack KC4UY) was the liquid crystal cell side and was previously bonded at the time of purchase. The absorption axis was oriented in the same direction.

The following evaluation was performed using the liquid crystal display devices (1) to (11) produced as described above.
<< Evaluation of Liquid Crystal Display >>
<Evaluation of viewing angle>
The backlight of each liquid crystal display device was lit continuously for one week in an environment of 23 ° C. and 55% RH, and then the viewing angle was measured. For measurement, EZ-Contrast 160D manufactured by ELDIM was used to measure the luminance ratio A between black display and white display in directions of azimuth angles of 45 °, 135 °, 225 °, 315 °, and tilt angle of 70 °. The average value was adopted. When the measurement results were evaluated according to the following criteria, they were as shown in Table 6 above. In this evaluation standard, “Δ” means that it is practically within the allowable range, and “X” means that it is practically outside the allowable range.

A: 100 <A
Δ: 50 <A ≦ 100
×: A ≦ 50
<Front contrast>
The backlight of each liquid crystal display device is turned on in an environment of 23 ° C. and 55% RH, the luminance from the normal direction of the display screen of white display and black display is measured, and the ratio is defined as the front contrast and evaluated according to the following criteria. The result was as shown in Table 6 above. For the measurement, CS-2000 manufactured by Konica Minolta Sensing Co., Ltd. was used. When the front contrast exceeds 1000, the liquid crystal display device is excellent. In this evaluation standard, “Δ” means that it is practically within the allowable range, and “X” means that it is practically outside the allowable range.

Front contrast = (brightness of white display measured from the normal direction of the display device)
/ (Luminance of black display measured from normal direction of display device)
A: 1000 <Front contrast ○: 750 <Front contrast ≦ 1000
Δ: 500 <front contrast ≦ 750
×: Front contrast ≦ 500
<Evaluation of diagonal color shift>
About each liquid crystal display device, the black display state in a dark room was confirmed visually by a plurality of persons from an oblique direction, and evaluated according to the following criteria. The results were as shown in Table 6 above. In this evaluation standard, “Δ” means that it is practically within the allowable range, and “X” means that it is practically outside the allowable range.

A: 0 out of 10 people recognized coloring ○: 1-2 people out of 10 recognized coloring Δ: 3-5 people out of 10 recognized coloring

X: 5-10 out of 10 people recognized coloring.
<Comprehensive evaluation>
From the above results, in the liquid crystal display devices (1) to (8) as examples of the present invention, unlike the liquid crystal display devices (9) to (11) as comparative examples, the viewing angle is increased and the front contrast is improved. It was found that color shift prevention when viewed from an oblique direction was achieved at the same time and was excellent.

  Considering this point, first, the Rth of the rod-like liquid crystal in the VA mode liquid crystal cell is negative and its wavelength dispersion is positive. Light leakage of such a liquid crystal cell (the liquid crystal cell is positioned in the thickness direction). In order to cancel the light leakage due to having a phase difference), it is considered that a C-plate optical compensation layer having a positive Rth and a positive wavelength dispersion like the liquid crystal cell is necessary. On the other hand, in order to compensate for light leakage of the polarizer (light leakage caused by the transmission axes of the two polarizers not being orthogonal when viewed from an oblique direction), it is preferable to obtain the same compensation effect at each wavelength. It is considered that a Z-plate optical compensation layer having a reverse wavelength dispersion, in which the phase difference increases with the increase of the phase difference, is suitable. Therefore, according to the configuration of the present invention in which the optical compensation layer of the C plate having positive wavelength dispersion and the optical compensation layer of the Z plate having reverse wavelength dispersion are combined, compensation for light leakage caused by the liquid crystal cell and the polarizing plate is achieved. Are both optimized, and it is estimated that the diagonal color shift, viewing angle, and front contrast are compatible.

1, 1A, 1D, 1E Liquid crystal display device 2 First polarizer 3, 3D First optical compensation layer 4 Liquid crystal cell 5 Second optical compensation layer 6 Second polarizer 30 Biaxial film (cellulosic resin) layer)
31 Liquid crystal layer

Claims (6)

Having at least a first polarizer, a first optical compensation layer, a liquid crystal cell, a second optical compensation layer, and a second polarizer in this order;
The first and second optical compensation layers satisfy the following formulas (1) to (3),
Liquid crystal molecules in the liquid crystal cell are aligned in the thickness direction of the liquid crystal cell during black display.
nx1>nz1> ny1 (1)
nx2 ≧ ny2> nz2 (2)
DSP (Ro1) <1 <DSP (Rth2) (3)
(Where nx1 is the refractive index in the slow axis direction in the plane of the first optical compensation layer, ny1 is the refractive index in the fast axis direction in the plane of the first optical compensation layer, and nz1 is the first refractive index in the first optical compensation layer) Nx2 represents the refractive index in the slow axis direction in the plane of the second optical compensation layer, and ny2 represents the phase advance in the plane of the second optical compensation layer. The refractive index in the axial direction, nz2 represents the refractive index in the thickness direction of the second optical compensation layer, and Ro1 represents the in-plane letter of the first optical compensation layer represented by the following formula (8-1). Rth2 represents the retardation value in the thickness direction of the second optical compensation layer represented by the following formula (9-2): DSP (Ro1) represents the first optical compensation layer. The chromatic dispersion value of the in-plane retardation value Ro1, and the first light measured at a wavelength of 480 nm. A value obtained by dividing the in-plane retardation value Ro1 of the compensation layer by the in-plane retardation value Ro1 measured at a wavelength of 630 nm DSP (Rth2) is the retardation value Rth2 in the thickness direction of the second optical compensation layer. The chromatic dispersion value is a value obtained by dividing the retardation value Rth2 of the second optical compensation layer measured at a wavelength of 480 nm by the retardation value Rth2 measured at a wavelength of 630 nm.
Ro1 = (nx1-ny1) × d1 (8-1)
Rth2 = {(nx2 + ny2) / 2-nz2} × d2) (9-2)
Here, d1 represents the thickness (nm) of the first optical compensation layer, d2 represents the thickness (nm) of the second optical compensation layer, and Ro1 and Rth2 are values measured at a wavelength of 590 nm, respectively. )   The liquid crystal display device according to claim 1, wherein the first optical compensation layer includes a cellulose resin layer. The first optical compensation layer satisfies the following formulas (4) and (5),
The liquid crystal display device according to claim 1, wherein the second optical compensation layer satisfies the following formulas (6) and (7).
Ro1 = 50-100 [nm] (4)
| Rth1 | = 0 to 20 [nm] (5)
Ro2 = 0 to 20 [nm] (6)
Rth2 = 200 to 350 [nm] (7)
(However, Rth1 represents the retardation value in the thickness direction of the first optical compensation layer represented by the following formula (9-1), and Ro2 represents the first formula represented by the following formula (8-2). 2 represents the in-plane retardation value of the optical compensation layer, and Ro2 and Rth1 are values measured at a wavelength of 590 nm, respectively.
Ro2 = (nx2-ny2) × d2 (8-2)
Rth1 = {(nx1 + ny1) / 2-nz1} × d1) (9-1)) The first optical compensation layer includes at least a cellulose resin layer and a liquid crystal layer,
The cellulose resin layer is
Disposed on the first polarizer side of the liquid crystal layer;
4. The liquid crystal display device according to claim 1, wherein the liquid crystal display device has an in-plane retardation and a slow axis orthogonal to an absorption axis of the first polarizer. The first optical compensation layer includes at least a cellulose resin layer and a liquid crystal layer,
The cellulose resin layer is
It is disposed on the liquid crystal cell side than the liquid crystal layer,
4. The liquid crystal display device according to claim 1, wherein the liquid crystal display device has an in-plane retardation and a slow axis parallel to the absorption axis of the first polarizer. 5. The second optical compensation layer includes:
The liquid crystal display device according to claim 1, comprising a cellulose-based resin layer containing a DSP value increasing agent.