JP2006227606A - Liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve a viewing angle of an IPS (in-plane switching) mode liquid crystal display device. <P>SOLUTION: The liquid crystal display device comprises a polarizing plate having a polarizing film and a protective film disposed at least on one face of the polarizing film, wherein a slow axis of the protective film intersects at least one out of an absorption axis of the polarizing film or an average alignment control direction of a liquid crystal layer, and further the protective film is a cellulose acylate film satisfying inequalities (I): 0≤Re<SB>(630)</SB>≤10, and ¾Rth<SB>(630)</SB>¾≤25, and an inequality (II): ¾Re<SB>(400)</SB>-Re<SB>(700)</SB>¾≤10. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a liquid crystal display device, and in particular, an in-plane switching mode liquid crystal that performs display by applying a horizontal electric field to a horizontally aligned nematic liquid crystal using a specific cellulose acylate film as a polarizing plate protective film. The present invention relates to a display device.

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

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

As one means for improving the color tone and the viewing angle of black display, the arrangement of an optical compensation material having birefringence characteristics between the liquid crystal layer and the polarizing plate is also studied in the IPS mode. For example, by arranging a birefringent medium having an optical axis orthogonal to each other to compensate for the increase / decrease in retardation of the liquid crystal layer during tilting, a white display or a halftone display is diagonally arranged between the substrate and the polarizing plate. It is disclosed that coloring can be improved when viewing directly from (see Patent Document 1).
In addition, a method using an optical compensation film made of a styrenic polymer having a negative intrinsic birefringence or a discotic liquid crystal compound (see Patent Documents 2, 3, and 4), or an optical axis as an optical compensation film with positive birefringence. Is a method of combining a film in the plane of the film with a film having a positive birefringence and an optical axis in the normal direction of the film (see Patent Document 5), biaxial optical compensation with a retardation of 1/2 wavelength A method using a sheet (see Patent Document 6), a method using a film having a negative retardation as a protective film of a polarizing plate, and providing an optical compensation layer having a positive retardation on this surface (see Patent Document 7) Proposed.

Japanese Patent Laid-Open No. 9-80424 Japanese Patent Laid-Open No. 10-54982 JP-A-11-202323 Japanese Patent Laid-Open No. 9-292522 JP 11-133408 A JP-A-11-305217 JP-A-10-307291

However, many of the proposed methods are methods that improve the viewing angle by canceling the birefringence anisotropy of the liquid crystal in the liquid crystal cell, so the polarization axis crossing angle when the orthogonal polarizing plate is viewed from an oblique direction. There is a problem that the light leakage based on the deviation from orthogonality cannot be solved sufficiently. Even in a system that can compensate for this light leakage, it is very difficult to completely optically compensate the liquid crystal cell without any problem. Furthermore, in the optical compensation sheet for IPS mode liquid crystal cell that performs optical compensation with the stretched birefringent polymer film, it is necessary to use a plurality of films. As a result, the thickness of the optical compensation sheet increases, and the display device becomes thinner It is disadvantageous. Moreover, since an adhesive layer is used for lamination | stacking of a stretched film, the adhesive layer contracted by the temperature / humidity change, and defects, such as peeling and a curvature between films, may generate | occur | produce.
In the IPS mode, a substantially parallel orientation is applied to the substrate surface when no voltage is applied, resulting in black display. In this state, there is a problem that display unevenness occurs due to non-uniform alignment of the liquid crystal layer, and the uniformity of black display is lowered.

  The present invention has been made in view of the above-described problems, and has an object to provide an IPS liquid crystal display device with a simple configuration and not only display quality but also significantly improved viewing angle characteristics and display uniformity. To do.

  As a result of intensive studies by the inventor under the above problems, it has been found that the above problems can be solved by the following means. Specifically, it was achieved by the following means.

(1) It has a pair of substrates disposed opposite each other, at least one of which has an electrode, a liquid crystal layer provided between the substrates and controlled in alignment, and a pair of polarizing plates disposed with the liquid crystal layer interposed therebetween. An electric field having a component parallel to the substrate having the electrode is formed by the electrode, and the polarizing plate has a polarizing film and a protective film provided on at least one surface of the polarizing film, Cellulose acylate in which the slow axis of the protective film intersects at least one of the absorption axis of the polarizing film or the average orientation control direction of the liquid crystal layer, and the protective film satisfies the following formulas (I) and (II) A liquid crystal display device which is a film.
(I) 0 ≦ Re ₍₆₃₀₎ ≦ 10 and | Rth ₍₆₃₀₎ | ≦ 25
(II) | Re ₍₄₀₀₎ −Re ₍₇₀₀₎ | ≦ 10 and | Rth ₍₄₀₀₎ −Rth ₍₇₀₀₎ | ≦ 35
(In the above formulas (I) and (II), Re ₍ λ ₎ represents the front retardation value (nm) at the wavelength λnm, and Rth ₍ λ ₎ represents the retardation value in the film thickness direction at the wavelength λnm (nm). Represents.)

(2) having a pair of opposed substrates each having at least one electrode, a liquid crystal layer provided between the substrates and controlled in alignment, and a pair of polarizing plates arranged with the liquid crystal layer sandwiched therebetween An electric field having a component parallel to the substrate having the electrode is formed by the electrode, and the polarizing plate has a polarizing film and a protective film provided on at least one surface of the polarizing film, The slow axis of the protective film intersects at least one of the absorption axis of the polarizing film or the average orientation control direction of the liquid crystal layer, and the protective film has an Rth in the film thickness direction of the following formula ( A liquid crystal display device, which is a cellulose acylate film containing a compound that reduces Rth so as to satisfy III) and (IV).
(III) (Rth _(A) −Rth ₍₀₎ ) / A ≦ −1.0
(IV) 0.01 ≦ A ≦ 30
(In the formulas (III) and (IV), Rth _(A) represents Rth (nm) of a protective film containing a compound that reduces Rth, and Rth ₍₀₎ is the protective film, and Rth is Rth (nm) of a film not containing a compound for reducing is represented, and A represents the weight (%) of a compound for reducing Rht relative to the weight of the film raw material polymer.

(3) The liquid crystal display device according to (1) or (2), wherein at least one optically anisotropic layer is disposed between the polarizing plate and the liquid crystal layer.
(4) The liquid crystal display device according to (3), wherein the optically anisotropic layer is made of a rod-like liquid crystal compound.
(5) The liquid crystal display according to any one of (1) to (4), wherein an intersection angle between the slow axis of the protective film and the absorption axis of the polarizing film is −10 ° to + 10 ° or 80 ° to + 100 °. apparatus.
(6) The liquid crystal display device according to (4), wherein a light source is provided on a side opposite to the liquid crystal layer of the pair of polarizing plates, and the protective film is provided on a side close to the light source.
(7) The liquid crystal display device according to any one of (1) to (6), wherein one layer of the protective film is disposed between any one of the polarizing films and a liquid crystal layer closest to the polarizing film. .
(8) One protective film is provided between one polarizing film and the liquid crystal layer closest to the polarizing film, and between the other polarizing film and the liquid crystal layer closest to the polarizing film. The liquid crystal display device according to any one of (1) to (6), which is disposed.
(9) The liquid crystal display device according to any one of (1) to (8), wherein the parallel electric field is generated by a pixel electrode and a counter electrode arranged in different layers.
(10) The parallel electric field is generated by a pair of transparent electrodes at least one of which is arranged in different layers and an electrode to which no voltage is applied, according to any one of (1) to (9). Liquid crystal display device.
(11) The liquid crystal display device according to any one of (1) to (10), wherein the protective film has a thickness of 10 to 60 μm.

  The liquid crystal display device of the present invention can optically self-compensate for unevenness and improve the uniformity of the image quality of the display device.

  Hereinafter, the contents of the present invention will be described in detail. In the present specification, “to” is used to mean that the numerical values described before and after it are included as a lower limit value and an upper limit value.

In this specification, Re ₍ λ ₎ and Rth ₍ λ ₎ represent in-plane retardation and retardation in the thickness direction at the wavelength λ, respectively. Re ₍ λ ₎ is measured by making light having a wavelength of λ nm incident in the normal direction of the film in KOBRA 21ADH (manufactured by Oji Scientific Instruments). Rth _(lambda) is the Re _(lambda), the slow axis wavelength from the tilt axis direction tilted + 40 ° (rotation axis) as relative to the normal direction of the film (KOBRA 21ADH is judged by) [lambda] nm in the plane light And retardation measured by injecting light of wavelength λ nm from a direction inclined by -40 ° with respect to the film normal direction with the in-plane slow axis as the tilt axis (rotation axis) KOBRA 21ADH calculates based on the retardation measured in three directions, the assumed average refractive index, and the input film thickness value. Here, as the assumed value of the average refractive index, the values in the polymer handbook (JOHN WILEY & SONS, INC) and catalogs of various optical films can be used. Those whose average refractive index is not known can be measured with an Abbe refractometer. The average refractive index values of the main optical films are exemplified below: cellulose acylate (1.48), cycloolefin polymer (1.52), polycarbonate (1.59), polymethyl methacrylate (1.49), Polystyrene (1.59). The KOBRA 21ADH calculates nx, ny, and nz by inputting these assumed values of average refractive index and film thickness. Nz = (nx−nz) / (nx−ny) is further calculated from the calculated nx, ny and nz.

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

[IPS mode liquid crystal display]
FIG. 2 is a schematic side sectional view showing an IPS mode liquid crystal cell. Usually, a plurality of pixels are provided by matrix electrodes, but a part of one pixel is shown. A linear electrode 14 is formed inside a pair of transparent substrates 5 and 8, and an alignment control film (not shown) is formed thereon. The rod-like liquid crystal molecules 7 sandwiched between the substrates 5 and 8 are oriented so as to have a slight angle with respect to the longitudinal direction of the linear electrode 16 when no electric field is applied. In this case, the dielectric anisotropy of the liquid crystal is assumed to be positive. When the electric field 17 is applied, the liquid crystal molecules 7 change their direction in the electric field direction. The light transmittance can be changed by arranging the polarizing plates 1 and 14 at a predetermined angle. The angle formed by the electric field direction 17 with respect to the surface of the substrate 8 is preferably 20 degrees or less, more preferably 10 degrees or less, that is, substantially parallel. Hereinafter, in the present invention, those below 20 degrees are generically expressed as a parallel electric field. Moreover, the effect does not change even if the electrode 14 is formed separately on the upper and lower substrates or only on one substrate.
As described above, the IPS mode is aligned parallel to the substrate surface when no voltage is applied or when a low voltage is applied. In general, the rubbing process is performed after the alignment film is applied to control the alignment. However, the alignment process tends to cause uneven alignment. Since the IPS is aligned parallel to the substrate surface as described above, this alignment unevenness becomes a large retardation unevenness, which leads to the uneven luminance unevenness of light leakage particularly during black display. On the other hand, in each of the VA, TN, and OCB modes, the liquid crystal molecules are aligned perpendicular to the substrate surface during black display. Therefore, even if the alignment unevenness is large, the retardation unevenness is small and the luminance unevenness is small.
FIG. 3 is a schematic cross-sectional view of a liquid crystal cell when the IPS mode has a higher response speed and a higher transmittance. Unlike FIG. 2, the electrode has a two-layer structure with an insulating layer 15 interposed therebetween. The lowermost electrode may be an unpatterned electrode or a linear electrode. The upper layer electrode is preferably linear, but any shape such as mesh, spiral, or dot may be used as long as the electric field from the lower layer electrode 16 can pass through, and a floating electrode having a neutral potential may be further added. . The insulating layer 15 may be either an inorganic material such as SiO or a nitride film, or an organic material such as acrylic or epoxy.
In this method, since the contrast ratio is improved due to the high transmittance, luminance unevenness due to in-plane alignment unevenness during black display is easily observed. In addition, since the electric field strength is high, uneven brightness is likely to occur when a low voltage is applied.

  As the liquid crystal material LC, nematic liquid crystal having a positive dielectric anisotropy Δε is used. The thickness (gap) of the liquid crystal layer was more than 2.8 μm and less than 4.5 μm. As described above, when the retardation (Δn · d) is more than 0.25 μm and less than 0.32 μm, a transmittance characteristic having almost no wavelength dependence within the visible light range can be obtained more easily. By the combination of the alignment film and the polarizing plate described later, the maximum transmittance can be obtained when the liquid crystalline molecules are rotated 45 degrees from the rubbing direction to the electric field direction. The thickness (gap) of the liquid crystal layer is controlled by polymer beads. Of course, the same gap can be obtained with glass bead fiber or resin columnar spacers. The liquid crystal material LC is not particularly limited as long as it is a nematic liquid crystal. The larger the value of the dielectric anisotropy Δε, the lower the driving voltage, and the smaller the refractive index anisotropy Δn, the thicker the liquid crystal layer (gap), the shorter the liquid crystal sealing time, In addition, gap variation can be reduced.

The display mode of the liquid crystal display device used in the present invention is not particularly limited, but ECB mode and IPS mode are preferably used.
In the present invention, the product Δn · d of the thickness d (μm) of the liquid crystal layer and the refractive index anisotropy Δn is 0.2 to 1.2 μm. The optimum value of Δn · d is 0.2 to 0.5 μm. In these ranges, since the white display luminance is high and the black display luminance is small, a bright and high-contrast display device can be obtained. Note that these optimum values are values in the transmission mode, and in the reflection mode, the optical path in the liquid crystal cell is doubled. Therefore, the optimum Δnd value is about a half of the above value. The liquid crystal display device used in the present invention is effective not only in the display mode but also in an aspect applied to the VA mode, OCB mode, TN mode, HAN mode, and STN mode.
IPS

  The liquid crystal display device of the present invention is not limited to the configuration shown in FIG. 1, and may include other members. For example, a color filter may be disposed between the liquid crystal cell and the polarizing film. Further, as will be described later, another optical compensation film can be further disposed between the liquid crystal cell and the polarizing plate. In the case of use as a transmission type, a cold cathode or a hot cathode fluorescent tube, or a backlight using a light emitting diode, a field emission element, or an electroluminescent element as a light source can be disposed on the back surface. In addition, the liquid crystal display device of the present invention may be of a reflective type. In such a case, only one polarizing plate of the present invention may be disposed on the observation side, and the liquid crystal cell back surface or the lower substrate of the liquid crystal cell may be disposed. Install a reflective film on the inner surface. Of course, it is also possible to provide a front light using the light source on the liquid crystal cell observation side.

  The liquid crystal display device of the present invention includes an image direct view type, an image projection type, and a light modulation type. The present invention is particularly effective when applied to an active matrix liquid crystal display device using three-terminal or two-terminal semiconductor elements such as TFT and MIM. Of course, an embodiment applied to a passive matrix liquid crystal display device represented by STN type called time-division driving is also effective.

  The present invention aims to improve the viewing angle of the liquid crystal display device by having a predetermined relationship between the slow axis of the protective film of the polarizing plate and the absorption axis of the polarizing film, and further, between the polarizing plate and the liquid crystal cell. By arranging an optical compensation film between them, the viewing angle is further improved. The optical compensation film is not particularly limited and may have any configuration as long as it has optical compensation capability. Examples thereof include a birefringent polymer film and a laminate of an optical compensation film made of a transparent support and liquid crystal molecules formed on the transparent support. In the latter embodiment, the protective film on the side close to the liquid crystal layer of the polarizing plate may also serve as the support for the optical compensation film.

  Hereinafter, materials used for various members usable in the liquid crystal display device of the present invention, manufacturing methods thereof, and the like will be described in detail.

[Polarizer]
In the present invention, a polarizing plate having a polarizing film and a pair of protective films sandwiching the polarizing film or a protective film provided on at least one surface of the polarizing plate is used. For example, a polarizing film obtained by dyeing a polarizing film made of a polyvinyl alcohol film or the like with iodine, stretching, and laminating both surfaces with a protective film can be used. The polarizing plate is disposed outside the liquid crystal cell. It is preferable that a pair of polarizing plates each including a polarizing film and a pair of protective films sandwiching the polarizing film are disposed with the liquid crystal cell interposed therebetween.

[Polarized film]
Examples of the polarizing film include an iodine polarizing film, a dye polarizing film using a dichroic dye, and a polyene polarizing film. The iodine-based polarizing film and the dye-based polarizing film are generally produced using a polyvinyl alcohol film.

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

  The polarizing film used in the present invention preferably has an absorption axis having a predetermined angle with respect to the longitudinal direction. When the absorption axis of the polarizing film has a predetermined angle with respect to the longitudinal direction, it can be easily pasted with a roll-to-roll when pasting with a protective film whose slow axis coincides with the longitudinal direction. it can. For example, as described in JP-A-2003-207628, a pair of protective films prepared in a long shape is bonded to both sides of a polarizing film prepared in a long shape, and a long laminate is obtained. Through a process of cutting (punching) into a desired size, a single plate polarizing plate can be obtained with high yield.

[Protective film]
The protective film for the liquid crystal display device of the present invention is not particularly defined as long as the protective film provided on at least one surface of the polarizing film satisfies the following conditions (1) and (2). Absent.
(1) Cellulose acylate film satisfying the following formulas (I) and (II) (I) 0 ≦ Re ₍₆₃₀₎ ≦ 10 and | Rth ₍₆₃₀₎ | ≦ 25
(II) | Re ₍₄₀₀₎ −Re ₍₇₀₀₎ | ≦ 10 and | Rth ₍₄₀₀₎ −Rth ₍₇₀₀₎ | ≦ 35
(In the above formulas (I) and (II), Re ₍ λ ₎ represents the front retardation value (nm) at the wavelength λnm, and Rth ₍ λ ₎ represents the retardation value in the film thickness direction at the wavelength λnm (nm). Represents.)
(2) Protective film (III) (Rth _(A) -Rth ₍₀₎ ) containing a compound that reduces Rth such that Rth in the film thickness direction of the protective film satisfies the following formulas (III) and (IV) /A≦−1.0
(IV) 0.01 ≦ A ≦ 30
(In the formulas (III) and (IV), Rth _(A) represents Rth (nm) of a protective film containing a compound that reduces Rth, and Rth ₍₀₎ is the protective film, and Rth is Rth (nm) of the film not containing the compound to be reduced is represented, and the weight (%) of the compound to reduce Rht relative to the weight of the film raw material polymer is represented.)
Here, the polymer of the film raw material refers to the raw material polymer of the main component constituting the film, and examples thereof include cellulose acylate.

  Hereinafter, the cellulose acylate film preferably used in the present invention will be described in detail.

 Examples of cellulose as a cellulose acylate raw material include cotton linter and wood pulp (hardwood pulp, softwood pulp), and any cellulose acylate obtained from any raw material cellulose may be used. . Detailed descriptions of these raw material celluloses can be found in, for example, Plastic Materials Course (17) Fibrous Resin (Maruzawa, Uda, Nikkan Kogyo Shimbun, published in 1970) and Invention Association Open Technical Report 2001-1745 (page 7). To page 8) can be used, and the cellulose acylate film of the present invention is not particularly limited.

Cellulose acylate substitution degree The cellulose acylate that can be used in the present invention is, for example, a cellulose hydroxyl group acylated, and the substituent is any acyl group having 2 to 22 carbon atoms. be able to. The degree of substitution of the cellulose acylate that can be used in the present invention with a hydroxyl group of cellulose is not particularly limited, but the degree of binding of acetic acid and / or a fatty acid having 3 to 22 carbon atoms to replace cellulose with a hydroxyl group is measured, The degree of substitution is obtained by calculation. As a measuring method, it can carry out according to ASTM D-817-91.

  As described above, in the cellulose acylate of the present invention, the degree of substitution of the cellulose with a hydroxyl group is not particularly limited, but the degree of acyl substitution with the hydroxyl group of cellulose is preferably 2.50 to 3.00. Furthermore, the substitution degree is more preferably 2.75 to 3.00, and further preferably 2.85 to 3.00.

  Among the acetic acid substituted for the hydroxyl group of cellulose and / or the fatty acid having 3 to 22 carbon atoms, the acyl group having 2 to 22 carbon atoms may be an aliphatic group or an allyl group, and may be a single or a mixture of two or more. Good. Examples thereof include cellulose alkylcarbonyl esters, alkenylcarbonyl esters, aromatic carbonyl esters, and aromatic alkylcarbonyl esters. Each of these may further have a substituted group. As these preferable acyl groups, acetyl group, propionyl group, butanoyl group, heptanoyl group, hexanoyl group, octanoyl group, decanoyl group, dodecanoyl group, tridecanoyl group, tetradecanoyl group, hexadecanoyl group, octadecanoyl group , Iso-butanoyl group, tert-butanoyl group, cyclohexanecarbonyl group, oleoyl group, benzoyl group, naphthylcarbonyl group, cinnamoyl group and the like. Among these, acetyl group, propionyl group, butanoyl group, dodecanoyl group, octadecanoyl group, tert-butanoyl group, oleoyl group, benzoyl group, naphthylcarbonyl group, cinnamoyl group and the like are preferable, and acetyl group, propionyl group, butanoyl group are preferable. Groups are more preferred.

  As a result of intensive studies by the inventor of the present invention, among the acyl substituents substituted on the above-mentioned cellulose hydroxyl group, in the case of substantially consisting of at least two types of acetyl group, propionyl group and butanoyl group, the total substitution thereof It was found that the optical anisotropy of the cellulose acylate film can be lowered when the degree is 2.50 to 3.00. The degree of acyl substitution is more preferably 2.60 to 3.00, still more preferably 2.65 to 3.00.

Degree of polymerization of cellulose acylate The degree of polymerization of cellulose acylate preferably used in the present invention is 180 to 700 in terms of viscosity average degree of polymerization. In cellulose acetate, 180 to 550 is more preferred, and 180 to 400 is more preferred. 180 to 350 are particularly preferred. By setting the degree of polymerization to a certain value or less, the viscosity of the cellulose acylate dope solution is increased, and it is possible to more effectively prevent film production from becoming difficult due to casting. By setting the degree of polymerization to a certain level or more, it is possible to more effectively prevent the strength of the produced film from being lowered. The average degree of polymerization can be measured, for example, by the intrinsic viscosity method of Uda et al. (Kazuo Uda, Hideo Saito, Journal of Textile Society, Vol. 18, No. 1, pages 105-120, 1962). This method is described in detail in JP-A-9-95538.
Further, the molecular weight distribution of cellulose acylate preferably used in the present invention is evaluated by gel permeation chromatography, and its polydispersity index Mw / Mn (Mw is mass average molecular weight, Mn is number average molecular weight) is small, and molecular weight distribution. Is preferably narrow. The specific value of Mw / Mn is preferably 1.0 to 3.0, more preferably 1.0 to 2.0, and most preferably 1.0 to 1.6. preferable.

  When the low molecular component is removed, the average molecular weight (degree of polymerization) increases, but the viscosity becomes lower than that of normal cellulose acylate, which is useful. Cellulose acylate having a small amount of low molecular components can be obtained by removing low molecular components from cellulose acylate synthesized by a usual method. The removal of the low molecular component can be carried out by washing the cellulose acylate with an appropriate organic solvent. In addition, when manufacturing a cellulose acylate with few low molecular components, it is preferable to adjust the sulfuric acid catalyst amount in an acetylation reaction to 0.5-25 mass parts with respect to 100 mass parts of cellulose. When the amount of the sulfuric acid catalyst is within the above range, cellulose acylate that is preferable in terms of molecular weight distribution (uniform molecular weight distribution) can be synthesized. When used in the production of cellulose acylate that can be used in the present invention, the water content is preferably 2% by mass or less, more preferably 1% by mass or less, and particularly 0.7% by mass. It is a cellulose acylate having a moisture content of not more than%. In general, cellulose acylate contains water and is known to be 2.5 to 5% by mass. In order to obtain the moisture content of the cellulose acylate in the present invention, it is necessary to dry, and the method is not particularly limited as long as the desired moisture content is obtained. These cellulose acylates of the present invention are described in detail on page 7 to page 12 of the raw material cotton and the synthesis method in the Japan Society for Invention and Technology (public technical number 2001-1745, published on March 15, 2001, Japan Society for Invention). It is described in.

  The cellulose acylate of the present invention can be used as a single group or a mixture of two or more different types of cellulose acylates as long as the substituent, substitution degree, polymerization degree, molecular weight distribution and the like are within the above-mentioned ranges.

Additives to cellulose acylate The cellulose acylate solution that can be used in the present invention includes various additives (for example, compounds that reduce optical anisotropy, wavelength dispersion adjusting agents, UV inhibitors, plasticizers, deterioration inhibitors, fine particles, optical property modifiers, etc.) can be added, and these will be described below. Further, the addition may be performed at any time in the dope preparation process, but may be performed by adding an additive to the final preparation process of the dope preparation process.
The cellulose acylate film that can be used in the present invention preferably contains a compound that lowers Rth such that Rth in the film thickness direction satisfies the following formulas (III) and (IV).
(III) (Rth _(A) −Rth ₍₀₎ ) / A ≦ −1.0
(IV) 0.01 ≦ A ≦ 30
(In the formulas (III) and (IV), Rth _(A) represents Rth (nm) of a protective film containing A% of a compound that reduces Rth, and Rth ₍₀₎ is the protective film, Rth (nm) of a film not containing a compound that lowers Rth is represented, and A represents the weight (%) of the compound that lowers Rht when the weight of the film raw material polymer is 100.
The above formulas (III) and (IV) are (III-I) (Rth _(A) -Rth ₍₀₎ ) / A≤-2.0
(IV-I) 0.1 ≦ A ≦ 20
More preferably.

Structural characteristics of compound that reduces optical anisotropy of cellulose acylate film (compound that reduces Rth) The compound that reduces the optical anisotropy of the cellulose acylate film will be described. As a result of intensive studies, the inventors of the present invention have sufficiently reduced optical anisotropy by using a compound that suppresses in-plane and film-thickness orientation of cellulose acylate in the film, and Re is zero. And Rth was set to be close to zero. Here, being close to zero means, for example, ± 2 nm or less at an arbitrary wavelength. For this purpose, it is advantageous that the compound for reducing the optical anisotropy is sufficiently compatible with cellulose acylate, and the compound itself does not have a rod-like structure or a planar structure. Specifically, when a plurality of planar functional groups such as aromatic groups are provided, a structure having these functional groups in a non-planar rather than the same plane is advantageous.

logP value When producing a cellulose acylate film that can be used in the present invention, the optical anisotropy is reduced by suppressing the cellulose acylate in the film from being oriented in the plane and in the film thickness direction as described above. Of the compounds to be produced, compounds having an octanol-water partition coefficient (log P value) of 0 to 7 are preferred. By adopting a compound having a log P value of 7 or less, compatibility with cellulose acylate is improved, and white turbidity and powder blowing of the film can be more effectively prevented. Moreover, since the hydrophilicity is high by adopting a compound having a log P value of 0 or more, it is possible to more effectively prevent the water resistance of the cellulose acetate film from deteriorating. A more preferable range for the logP value is 1 to 6, and a particularly preferable range is 1.5 to 5.
The octanol-water partition coefficient (log P value) can be measured by a flask immersion method described in JIS Japanese Industrial Standard Z7260-107 (2000). Further, the octanol-water partition coefficient (log P value) can be estimated by a computational chemical method or an empirical method instead of the actual measurement. As a calculation method, Crippen's fragmentation method (J. Chem. Inf. Comput. Sci., 27, 21 (1987).), Viswanadhan's fragmentation method (J. Chem. Inf. Comput. Sci., 29, 163 (1989).) The Broto's fragmentation method (Eur. J. Med. Chem.-Chim. Theor., 19, 71 (1984)) is preferably used, but the Crippen's fragmentation method (J. Chem. Inf. Comput. Sci., 27 21 (1987)) is more preferable. When the log P value of a certain compound varies depending on the measurement method or calculation method, it is preferable to determine whether or not the compound is within the scope of the present invention by the Crippen's fragmentation method.

Physical properties of compounds that reduce optical anisotropy The compounds that reduce optical anisotropy may or may not contain an aromatic group. The compound that reduces optical anisotropy preferably has a molecular weight of 150 to 3000, more preferably 170 to 2000, and even more preferably 200 to 1000. A specific monomer structure may be used as long as these molecular weights are within the range, and an oligomer structure or a polymer structure in which a plurality of the monomer units are bonded may be used.
The compound that reduces optical anisotropy is preferably a liquid at 25 ° C. or a solid having a melting point of 25 to 250 ° C., more preferably a liquid at 25 ° C. or a melting point of 25 to 200 ° C. It is a solid. Moreover, it is preferable that the compound which reduces optical anisotropy does not volatilize in the process of dope casting for cellulose acylate film production and drying.
The addition amount of the compound that decreases the optical anisotropy is preferably 0.01 to 30% by mass of the cellulose acylate, more preferably 1 to 25% by mass, and 5 to 20% by mass. Is particularly preferred.
The compound that decreases the optical anisotropy may be used alone, or two or more compounds may be mixed and used in an arbitrary ratio.
The timing for adding the compound for reducing the optical anisotropy may be any time during the dope preparation process, or may be performed at the end of the dope preparation process.

  The compound that reduces the optical anisotropy is such that the average content of the compound in the portion from the surface on at least one side to 10% of the total film thickness is the average content of the compound in the central portion of the cellulose acylate film. It is preferable that it exists so that it may become 80 to 99% of. The abundance of the compound that reduces the optical anisotropy can be determined by measuring the amount of the compound on the surface and in the center by, for example, a method using an infrared absorption spectrum described in JP-A-8-57879.

  Although the specific example of the compound which reduces the optical anisotropy of the cellulose acylate film preferably used by this invention below is shown, this invention is not limited to these compounds.

 The 1st example of the compound which reduces optical anisotropy is a compound represented by following General formula (13).

上記一般式（１３）中、Ｒ¹¹はアルキル基またはアリール基を表し、Ｒ¹²およびＲ¹³は、それぞれ独立に、水素原子、アルキル基またはアリール基を表す。また、Ｒ¹¹、Ｒ¹²およびＲ¹³の炭素原子数の総和が１０以上であることが特に好ましい。Ｒ¹¹、Ｒ¹²およびＲ¹³は置換基を有していてもよく、置換基としてはフッ素原子、アルキル基、アリール基、アルコキシ基、スルホン基およびスルホンアミド基が好ましく、アルキル基、アリール基、アルコキシ基、スルホン基およびスルホンアミド基が特に好ましい。また、アルキル基は直鎖であっても、分岐であっても、環状であってもよく、炭素原子数１〜２５のものが好ましく、６〜２５のものがより好ましく、６〜２０のもの（例えば、メチル基、エチル基、プロピル基、イソプロピル基、ブチル基、イソブチル基、t−ブチル基、アミル基、イソアミル基、t−アミル基、ヘキシル基、シクロヘキシル基、ヘプチル基、オクチル基、ビシクロオクチル基、ノニル基、アダマンチル基、デシル基、t−オクチル基、ウンデシル基、ドデシル基、トリデシル基、テトラデシル基、ペンタデシル基、ヘキサデシル基、ヘプタデシル基、オクタデシル基、ノナデシル基、ジデシル基）が特に好ましい。アリール基としては炭素原子数が６〜３０のものが好ましく、６〜２４のもの（例えば、フェニル基、ビフェニル基、テルフェニル基、ナフチル基、ビナフチル基、トリフェニルフェニル基）が特に好ましい。
以下に、一般式（１３）で表される化合物の好ましい例を下記に示すが、本発明はこれらの具体例に限定されるものではない。尚、化合物中、Ｐｒⁱはイソプロピル基を意味する（以下、同じ）。

In the general formula (13), R ¹¹ represents an alkyl group or an aryl group, and R ¹² and R ¹³ each independently represent a hydrogen atom, an alkyl group, or an aryl group. Further, it is particularly preferable that the total number of carbon atoms of R ¹¹ , R ¹² and R ¹³ is 10 or more. R ¹¹ , R ¹² and R ¹³ may have a substituent, and the substituent is preferably a fluorine atom, an alkyl group, an aryl group, an alkoxy group, a sulfone group, or a sulfonamide group, an alkyl group, an aryl group, Alkoxy groups, sulfone groups and sulfonamido groups are particularly preferred. Further, the alkyl group may be linear, branched or cyclic, and preferably has 1 to 25 carbon atoms, more preferably 6 to 25, and more preferably 6 to 20 (For example, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, t-butyl, amyl, isoamyl, t-amyl, hexyl, cyclohexyl, heptyl, octyl, bicyclo Octyl, nonyl, adamantyl, decyl, t-octyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, nonadecyl, didecyl) are particularly preferred . As the aryl group, those having 6 to 30 carbon atoms are preferable, and those having 6 to 24 carbon atoms (for example, phenyl group, biphenyl group, terphenyl group, naphthyl group, binaphthyl group, triphenylphenyl group) are particularly preferable.
Although the preferable example of a compound represented by General formula (13) below is shown below, this invention is not limited to these specific examples. In the compounds, Pr ⁱ means an isopropyl group (hereinafter the same).

一般式（１８）中、Ｒ¹⁴はアルキル基またはアリール基を表し、Ｒ¹⁵およびＲ¹⁶はそれぞれ独立に水素原子、アルキル基またはアリール基を表す。
Ｒ¹⁴は、フェニル基または、環状アルキル基が好ましい。Ｒ¹⁵およびＲ¹⁶は、それぞれ、フェニル基またはアルキル基が好ましい。アルキル基としては、環状アルキル基および直鎖のアルキル基のいずれも好ましい。
これらの基は、置換基を有していてもよく、置換基としてはフッ素原子、アルキル基、アリール基、アルコキシ基、スルホン基およびスルホンアミド基が好ましく、アルキル基、アリール基、アルコキシ基、スルホン基およびスルホンアミド基が特に好ましい。
一般式（１８）で表される化合物は、より好ましくは一般式（１９）で表される化合物である。

In the general formula (18), R ¹⁴ represents an alkyl group or an aryl group, and R ¹⁵ and R ¹⁶ each independently represent a hydrogen atom, an alkyl group, or an aryl group.
R ¹⁴ is preferably a phenyl group or a cyclic alkyl group. R ¹⁵ and R ¹⁶ are each preferably a phenyl group or an alkyl group. As the alkyl group, both a cyclic alkyl group and a linear alkyl group are preferable.
These groups may have a substituent, and the substituent is preferably a fluorine atom, an alkyl group, an aryl group, an alkoxy group, a sulfone group, or a sulfonamide group, and an alkyl group, an aryl group, an alkoxy group, a sulfone group. And the sulfonamido group are particularly preferred.
The compound represented by the general formula (18) is more preferably a compound represented by the general formula (19).

一般式（１９）中、Ｒ¹¹⁴、Ｒ¹¹⁵およびＲ¹¹⁶はそれぞれ独立にアルキル基またはアリール基を表す。アルキル基は、環状アルキル基および直鎖のアルキル基のいずれも好ましいく、アリール基はフェニル基が好ましい。
以下に、一般式（１８）（および一般式（１９））で表される化合物の好ましい例を下記に示すが、本発明はこれらの具体例に限定されるものではない。尚、化合物中、Ｂｕⁱはイソブチル基を意味する。

In the general formula (19), R ¹¹⁴ , R ¹¹⁵ and R ¹¹⁶ each independently represents an alkyl group or an aryl group. The alkyl group is preferably a cyclic alkyl group or a linear alkyl group, and the aryl group is preferably a phenyl group.
Although the preferable example of a compound represented by General formula (18) (and General formula (19)) below is shown below, this invention is not limited to these specific examples. In the compounds, Bu ⁱ means an isobutyl group.

Wavelength Dispersion Adjusting Agent A compound that reduces the wavelength dispersion of the cellulose acylate film (hereinafter also referred to as a wavelength dispersion adjusting agent) will be described. In order to improve the Rth wavelength dispersion of the cellulose acylate film of the present invention, a compound that reduces the Rth wavelength dispersion ΔRth = | Rth ₍₄₀₀₎ −Rth ₍₇₀₀₎ | represented by the following formula (VII): Is preferably contained within a range satisfying the following formulas (V) and (VI).
(VII) ΔRth = | Rth ₍₄₀₀₎ −Rth ₍₇₀₀₎ |
(V) (ΔRth (B) −ΔRth (0)) / B ≦ −2.0
(VI) 0.01 ≦ B ≦ 30
The above formulas (V) and (VI) are: (VI) (ΔRth (B) −ΔRth (0)) / B ≦ −3.0
(VI-I) 0.05 ≦ B ≦ 25
More preferably,
(V-II) (ΔRth (B) −ΔRth (0)) / B ≦ −4.0
(VI-II) 0.1 ≦ B ≦ 20
More preferably.
The above-mentioned wavelength dispersion adjusting agent has at least a compound having absorption in the ultraviolet region of 200 to ₄₀₀ nm and reducing | Re ₍₄₀₀₎ -Re ₍₇₀₀₎ | and | Rth ₍₄₀₀₎ -Rth ₍₇₀₀₎ | The wavelength dispersion of Re and Rth of the cellulose acylate film was adjusted by including 0.01 to 30% by weight of one type, cellulose acylate solid content. By adding 0.1 to 30% by weight as the addition amount, wavelength dispersion of Re and Rth of the cellulose acylate film was adjusted.

  In general, the Re and Rth values of the cellulose acylate film have a wavelength dispersion characteristic that the longer wavelength side is larger than the shorter wavelength side. Therefore, it is required to smooth the chromatic dispersion by increasing Re and Rth on the relatively short wavelength side. On the other hand, a compound having absorption in the ultraviolet region of 200 to 400 nm has a wavelength dispersion characteristic in which the absorbance on the long wavelength side is larger than that on the short wavelength side. If the compound itself is isotropically present inside the cellulose acylate film, it is assumed that the birefringence of the compound itself, and thus the wavelength dispersion of Re and Rth, is large on the short wavelength side as well as the wavelength dispersion of absorbance. .

  Therefore, as described above, by using the compound having absorption in the ultraviolet region of 200 to 400 nm and assuming that the wavelength dispersion of Re and Rth of the compound itself is large on the short wavelength side, the Re and Rth of the cellulose acylate film are used. Chromatic dispersion can be prepared. For this purpose, the compound for adjusting the wavelength dispersion is required to be sufficiently homogeneously compatible with the cellulose acylate. The absorption band range in the ultraviolet region of such a compound is preferably 200 to 400 nm, more preferably 220 to 395 nm, and even more preferably 240 to 390 nm.

In recent years, liquid crystal display devices such as televisions, notebook personal computers, and mobile portable terminals have been required to have excellent transmittance of optical members used in liquid crystal display devices in order to increase luminance with less power. In this respect, a cellulose acylate film is a compound having absorption in the ultraviolet region of 200 to ₄₀₀ nm and reducing | Re ₍₄₀₀₎ -Re ₍₇₀₀₎ | and | Rth ₍₄₀₀₎ -Rth ₍₇₀₀₎ | When it is added, it is required that the spectral transmittance is excellent. In the cellulose acylate film of the present invention, the spectral transmittance at a wavelength of 380 nm is preferably 45% to 95%, and the spectral transmittance at a wavelength of 350 nm is preferably 10% or less.

  As described above, the wavelength dispersion adjusting agent preferably used in the present invention preferably has a molecular weight of 250 to 1000 from the viewpoint of volatility, more preferably 260 to 800, still more preferably 270 to 800, Especially preferably, it is 300-800. As long as these molecular weights are within the range, a specific monomer structure may be used, or an oligomer structure or a polymer structure in which a plurality of the monomer units are bonded may be used.

  It is preferable that the wavelength dispersion adjusting agent does not volatilize during the dope casting and drying process for producing the cellulose acylate film.

The addition amount of the wavelength dispersion adjusting agent preferably used in the present invention described above is preferably 0.01 to 30% by weight, more preferably 0.1 to 20% by weight of cellulose acylate, and 2 to 10% by weight is particularly preferred.
These wavelength dispersion adjusting agents may be used alone or in combination of two or more compounds at an arbitrary ratio.
In addition, the timing of adding these wavelength dispersion adjusting agents may be any time during the dope preparation process, or may be performed at the end of the dope preparation process.

  Specific examples of the wavelength dispersion adjusting agent preferably used in the present invention include, for example, benzotriazole compounds, benzophenone compounds, cyano group-containing compounds, oxybenzophenone compounds, salicylic acid ester compounds, nickel complex compounds, and the like. However, the present invention is not limited to these compounds.

  As the benzotriazole-based compound, those represented by the following general formula (101) are preferably used as the wavelength dispersion adjusting agent of the present invention.

Formula (101)
Q ¹¹ -Q ¹² -OH
(In the general formula (101), Q ¹¹ represents a nitrogen-containing aromatic heterocycle and Q ¹² represents an aromatic ring.)

Q ¹¹ represents a nitrogen-containing aromatic heterocycle, preferably a 5- to 7-membered nitrogen-containing aromatic heterocycle, more preferably a 5- or 6-membered nitrogen-containing aromatic heterocycle, , Imidazole ring, pyrazole ring, triazole ring, tetrazole ring, thiazole ring, oxazole ring, selenazole ring, benzotriazole ring, benzothiazole ring, benzoxazole ring, benzoselenazole ring, thiadiazole ring, oxadiazole ring, naphthothiazole ring Naphthoxazole ring, azabenzimidazole ring, purine ring, pyridine ring, pyrazine ring, pyrimidine ring, pyridazine ring, triazine ring, triazaindene ring, tetrazaindene ring, etc., more preferably a 5-membered ring. Nitrogen-containing aromatic heterocycle, specifically imidazole ring, pyra Lumpur ring, triazole ring, tetrazole ring, thiazole ring, oxazole ring, benzotriazole ring, benzothiazole ring, benzoxazole ring, thiadiazole ring, oxadiazole ring are preferred, particularly preferably a benzotriazole ring.

The aromatic ring represented by Q ¹² may be an aromatic hydrocarbon ring or an aromatic heterocycle. These may be monocyclic or may form a condensed ring with another ring.
The aromatic hydrocarbon ring is preferably a monocyclic or bicyclic aromatic hydrocarbon ring having 6 to 30 carbon atoms, more preferably a monocyclic or bicyclic aromatic hydrocarbon ring having 6 to 20 carbon atoms. More preferably a monocyclic or bicyclic aromatic hydrocarbon ring having 6 to 12 carbon atoms, and most preferably a benzene ring.
The aromatic heterocycle is preferably an aromatic heterocycle containing a nitrogen atom or a sulfur atom. Specific examples of the hetero ring include, for example, thiophene ring, imidazole ring, pyrazole ring, pyridine ring, pyrazine ring, pyridazine ring, triazole ring, triazine ring, indole ring, indazole ring, purine ring, thiazoline ring, thiazole ring, thiadiazole. Ring, oxazoline ring, oxazole ring, oxadiazole ring, quinoline ring, isoquinoline ring, phthalazine ring, naphthyridine ring, quinoxaline ring, quinazoline ring, cinnoline ring, pteridine ring, acridine ring, phenanthroline ring, phenazine ring, tetrazole ring, benz Examples include an imidazole ring, a benzoxazole ring, a benzthiazole ring, a benzotriazole ring, and a tetrazaindene ring. The aromatic hetero ring is preferably a pyridine ring, a triazine ring or a quinoline ring.
The aromatic ring represented by Q ¹² is preferably an aromatic hydrocarbon ring, more preferably a naphthalene ring or a benzene ring, and particularly preferably a benzene ring. Q ¹² may have a substituent, and the substituent T described below is preferable as the substituent.
Examples of the substituent T include an alkyl group (preferably having 1 to 20 carbon atoms, more preferably 1 to 12 carbon atoms, and particularly preferably 1 to 8 carbon atoms. For example, a methyl group, an ethyl group, an isopropyl group, tert- Butyl group, n-octyl group, n-decyl group, n-hexadecyl group, cyclopropyl group, cyclopentyl group, cyclohexyl group, etc.), alkenyl group (preferably having 2-20 carbon atoms, more preferably carbon number). 2 to 12, particularly preferably 2 to 8 carbon atoms, such as vinyl group, allyl group, 2-butenyl group, 3-pentenyl group, etc.), alkynyl group (preferably 2 to 20 carbon atoms, more Preferably they are C2-C12, Most preferably, it is C2-C8, for example, a propargyl group, 3-pentynyl group, etc. are mentioned. A group (preferably having 6 to 30 carbon atoms, more preferably 6 to 20 carbon atoms, particularly preferably 6 to 12 carbon atoms, and examples thereof include a phenyl group, a p-methylphenyl group, and a naphthyl group), substitution Or an unsubstituted amino group (preferably having 0 to 20 carbon atoms, more preferably 0 to 10 carbon atoms, particularly preferably 0 to 6 carbon atoms, such as an amino group, a methylamino group, a dimethylamino group, a diethylamino group, A dibenzylamino group, etc.), an alkoxy group (preferably having 1 to 20 carbon atoms, more preferably 1 to 12 carbon atoms, particularly preferably 1 to 8 carbon atoms, such as methoxy group, ethoxy group, butoxy Group), an aryloxy group (preferably having 6 to 20 carbon atoms, more preferably 6 to 16 carbon atoms, and particularly preferably 6 to 12 carbon atoms). For example, a phenyloxy group, 2-naphthyloxy group, etc.), an acyl group (preferably having 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, particularly preferably 1 to 12 carbon atoms, For example, an acetyl group, a benzoyl group, a formyl group, a pivaloyl group, etc.), an alkoxycarbonyl group (preferably having 2 to 20 carbon atoms, more preferably 2 to 16 carbon atoms, and particularly preferably 2 to 12 carbon atoms). A methoxycarbonyl group, an ethoxycarbonyl group, etc.), an aryloxycarbonyl group (preferably having a carbon number of 7-20, more preferably having a carbon number of 7-16, particularly preferably having a carbon number of 7-10, Phenyloxycarbonyl group, etc.), acyloxy group (preferably having 2 to 20 carbon atoms, more preferably It has 2 to 16 carbon atoms, particularly preferably 2 to 10 carbon atoms, and examples thereof include an acetoxy group and a benzoyloxy group. ), An acylamino group (preferably having 2 to 20 carbon atoms, more preferably 2 to 16 carbon atoms, particularly preferably 2 to 10 carbon atoms, and examples thereof include an acetylamino group and a benzoylamino group), alkoxycarbonyl. An amino group (preferably having 2 to 20 carbon atoms, more preferably 2 to 16 carbon atoms, particularly preferably 2 to 12 carbon atoms, such as a methoxycarbonylamino group), an aryloxycarbonylamino group (preferably Has 7 to 20 carbon atoms, more preferably 7 to 16 carbon atoms, particularly preferably 7 to 12 carbon atoms, such as a phenyloxycarbonylamino group, and a sulfonylamino group (preferably 1 to 1 carbon atom). 20, more preferably 1 to 16 carbon atoms, particularly preferably 1 to 12 carbon atoms. Nylamino group, benzenesulfonylamino group, etc.), sulfamoyl group (preferably having 0 to 20 carbon atoms, more preferably 0 to 16 carbon atoms, particularly preferably 0 to 12 carbon atoms, such as sulfamoyl group, methyl A sulfamoyl group, a dimethylsulfamoyl group, a phenylsulfamoyl group, etc.), a carbamoyl group (preferably having 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, and particularly preferably 1 to carbon atoms). For example, carbamoyl group, methylcarbamoyl group, diethylcarbamoyl group, phenylcarbamoyl group, etc.), alkylthio group (preferably having 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, particularly preferably carbon). Examples thereof include methylthio group and ethylthio group. ), An arylthio group (preferably having 6 to 20 carbon atoms, more preferably 6 to 16 carbon atoms, particularly preferably 6 to 12 carbon atoms, such as a phenylthio group), a sulfonyl group (preferably C1-C20, More preferably, it is C1-C16, Most preferably, it is C1-C12, For example, a mesyl group, a tosyl group, etc. are mentioned), a sulfinyl group (preferably C1-C20, More preferably, it is C1-C16, Most preferably, it is C1-C12, for example, a methanesulfinyl group, a benzenesulfinyl group, etc.), a ureido group (preferably C1-C20, more preferably carbon) The number is 1 to 16, particularly preferably 1 to 12, and examples thereof include a ureido group, a methylureido group, and a phenylureido group. ), Phosphoric acid amide groups (preferably having 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, particularly preferably 1 to 12 carbon atoms, such as diethyl phosphoric acid amide and phenylphosphoric acid amide. ), Hydroxy group, mercapto group, halogen atom (eg fluorine atom, chlorine atom, bromine atom, iodine atom), cyano group, sulfo group, carboxyl group, nitro group, hydroxamic acid group, sulfino group, hydrazino group, imino group, Heterocyclic group (preferably having 1 to 30 carbon atoms, more preferably 1 to 12 carbon atoms, and examples of the hetero atom include a nitrogen atom, an oxygen atom and a sulfur atom, specifically, for example, an imidazolyl group, a pyridyl group, a quinolyl group, Furyl, piperidyl, morpholino, benzoxazolyl, benzimidazolyl, benzthiazolyl, etc. ), A silyl group (preferably having 3 to 40 carbon atoms, more preferably 3 to 30 carbon atoms, particularly preferably 3 to 24 carbon atoms, and examples thereof include a trimethylsilyl group and a triphenylsilyl group. ) And the like. These substituents may be further substituted. Moreover, when there are two or more substituents, they may be the same or different. If possible, they may be linked together to form a ring.

The general formula (101) is preferably a compound represented by the following general formula (101-A).
General formula (101-A)

(In the general formula (101-A), R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , and R ⁸ each independently represents a hydrogen atom or a substituent.)

R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁸ , and R ⁹ each independently represent a hydrogen atom or a substituent, and the above-mentioned substituent T is applied as the substituent. it can. These substituents may be further substituted with another substituent, and the substituents may be condensed to form a ring structure.
R ¹ and R ³ are each preferably a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group, an amino group, an alkoxy group, an aryloxy group, a hydroxy group, or a halogen atom, more preferably a hydrogen atom. , An alkyl group, an aryl group, an alkyloxy group, an aryloxy group and a halogen atom, more preferably a hydrogen atom and an alkyl group having 1 to 12 carbon atoms, particularly preferably an alkyl group having 1 to 12 carbon atoms (preferably carbon 4 to 12).

R ² and R ⁴ are each preferably a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group, an amino group, an alkoxy group, an aryloxy group, a hydroxy group, or a halogen atom, more preferably a hydrogen atom. , An alkyl group, an aryl group, an alkyloxy group, an aryloxy group and a halogen atom, more preferably a hydrogen atom and an alkyl group having 1 to 12 carbon atoms, particularly preferably a hydrogen atom and a methyl group, most preferably hydrogen. Is an atom.

R ⁵ and R ⁸ are each preferably a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group, an amino group, an alkoxy group, an aryloxy group, a hydroxy group, or a halogen atom, more preferably a hydrogen atom. , An alkyl group, an aryl group, an alkyloxy group, an aryloxy group and a halogen atom, more preferably a hydrogen atom and an alkyl group having 1 to 12 carbon atoms, particularly preferably a hydrogen atom and a methyl group, most preferably hydrogen. Is an atom.

R ⁶ and R ⁷ are each preferably a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group, an amino group, an alkoxy group, an aryloxy group, a hydroxy group, or a halogen atom, more preferably a hydrogen atom. , An alkyl group, an aryl group, an alkyloxy group, an aryloxy group and a halogen atom, more preferably a hydrogen atom and a halogen atom, and particularly preferably a hydrogen atom and a chlorine atom.

The general formula (101) is more preferably a compound represented by the following general formula (101-B).
General formula (101-B)

一般式（１０１−Ｂ）中、Ｒ¹、Ｒ³、Ｒ⁶およびＲ⁷は一般式（１０１−Ａ）におけるそれらと同義であり、また好ましい範囲も同様である。

In general formula (101-B), R ¹ , R ³ , R ⁶ and R ⁷ have the same meanings as those in general formula (101-A), and preferred ranges thereof are also the same.

  Specific examples of the compound represented by formula (101) are listed below, but the present invention is not limited to the following specific examples.

  Among the benzotriazole compounds mentioned in the above examples, when the cellulose acylate film of the present invention was produced without including those having a molecular weight of 320 or less, it was confirmed that it was advantageous in terms of retention.

In addition, as the benzophenone compound which is one of the wavelength dispersion adjusting agents used in the present invention, those represented by the general formula (102) are preferably used.
Formula (102)

（一般式（１０２）中、Ｑ¹およびＱ²は、それぞれ、芳香族環を表す。ＸはＮＲ（Ｒは水素原子または置換基を表す。）、酸素原子または硫黄原子を表す。）

(In General Formula (102), Q ¹ and Q ² each represent an aromatic ring. X represents NR (R represents a hydrogen atom or a substituent), an oxygen atom or a sulfur atom.)

The aromatic ring represented by Q ¹ or Q ² may be an aromatic hydrocarbon ring or an aromatic heterocycle. These may be monocyclic or may form a condensed ring with another ring.
The aromatic hydrocarbon ring represented by Q ¹ and Q ² is preferably (preferably a monocyclic or bicyclic aromatic hydrocarbon ring having 6 to 30 carbon atoms (for example, a benzene ring, a naphthalene ring, etc.). More preferably, it is an aromatic hydrocarbon ring having 6 to 20 carbon atoms, more preferably an aromatic hydrocarbon ring having 6 to 12 carbon atoms.) More preferably, it is a benzene ring.
The aromatic heterocycle represented by Q ¹ and Q ² is preferably an aromatic heterocycle containing at least one of an oxygen atom, a nitrogen atom or a sulfur atom. Specific examples of the heterocyclic ring include, for example, furan ring, pyrrole ring, thiophene ring, imidazole ring, pyrazole ring, pyridine ring, pyrazine ring, pyridazine ring, triazole ring, triazine ring, indole ring, indazole ring, purine ring, thiazoline. Ring, thiazole ring, thiadiazole ring, oxazoline ring, oxazole ring, oxadiazole ring, quinoline ring, isoquinoline ring, phthalazine ring, naphthyridine ring, quinoxaline ring, quinazoline ring, cinnoline ring, pteridine ring, acridine ring, phenanthroline ring, phenazine Ring, tetrazole ring, benzimidazole ring, benzoxazole ring, benzthiazole ring, benzotriazole ring, tetrazaindene ring and the like. The aromatic hetero ring is preferably a pyridine ring, a triazine ring or a quinoline ring.
The aromatic ring represented by Q ¹ or Q ² is preferably an aromatic hydrocarbon ring, more preferably an aromatic hydrocarbon ring having 6 to 10 carbon atoms, and further preferably a substituted or unsubstituted benzene. It is a ring.
Q ¹ or Q ² may further have a substituent, and the substituent T described later is preferable, but the substituent does not contain a carboxylic acid, a sulfonic acid, or a quaternary ammonium salt. Further, if possible, substituents may be linked to form a ring structure.

  X represents NR (R represents a hydrogen atom or a substituent. As the substituent, the above-mentioned substituent T can be applied), an oxygen atom or a sulfur atom, X is preferably NR (R is preferably an acyl group) A sulfonyl group, and these substituents may be further substituted.) Or an oxygen atom, and particularly preferably an oxygen atom.

The general formula (102) is preferably a compound represented by the following general formula (102-A).
Formula (102-A)

(In the general formula (102-A), R ²¹ , R ²² , R ²³ , R ²⁴ , R ²⁵ , R ²⁶ , R ²⁷ , R ²⁸ , and R ²⁹ each independently represent a hydrogen atom or a substituent.)

R ²¹ , R ²³ , R ²⁴ , R ²⁵ , R ²⁶ , R ²⁸ , and R ²⁹ each independently represent a hydrogen atom or a substituent, and the above-described substituent T can be applied as the substituent. These substituents may be further substituted with another substituent, and the substituents may be condensed to form a ring structure.

R ²¹ , R ²³ , R ²⁴ , R ²⁵ , R ²⁶ , R ²⁸ , and R ²⁹ are preferably a hydrogen atom, alkyl group, alkenyl group, alkynyl group, aryl group, amino group, alkoxy group, aryloxy group , A hydroxy group and a halogen atom, more preferably a hydrogen atom, an alkyl group, an aryl group, an alkyloxy group, an aryloxy group, and a halogen atom, still more preferably a hydrogen atom and a carbon 1-12 alkyl group, particularly Preferred are a hydrogen atom and a methyl group, and most preferred is a hydrogen atom.

R ²² is preferably a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group, an amino group, an alkoxy group, an aryloxy group, a hydroxy group, or a halogen atom, more preferably a hydrogen atom or a C 1-20 carbon atom. An alkyl group, an amino group having 0 to 20 carbon atoms, an alkoxy group having 1 to 12 carbon atoms, an aryloxy group having 6 to 12 carbon atoms, and a hydroxy group, more preferably an alkoxy group having 1 to 20 carbon atoms, Preferably it is a C1-C12 alkoxy group.

Preferably a hydrogen atom R ^27, an alkyl group, an alkenyl group, an alkynyl group, an aryl group, an amino group, an alkoxy group, an aryloxy group, a hydroxyl group, a halogen atom, more preferably a hydrogen atom, an alkyl group having 1 to 20 carbon atoms , An amino group having 0 to 20 carbon atoms, an alkoxy group having 1 to 12 carbon atoms, an aryloxy group having 6 to 12 carbon atoms, and a hydroxy group, more preferably a hydrogen atom and an alkyl group having 1 to 20 carbon atoms (preferably C1-C12, More preferably, it is C1-C8, More preferably, it is a methyl group, Especially preferably, they are a methyl group and a hydrogen atom.

More preferable as the general formula (102) is a compound represented by the following general formula (102-B).
General formula (102-B)

(In the general formula (102-B), R ¹⁰ represents a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, or an aryl group.)

R ¹⁰ represents a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, or an aryl group, and these may have a substituent. As the substituent, the above-described substituent T can be applied.
R ¹⁰ is preferably an alkyl group, more preferably an alkyl group having 5 to 20 carbon atoms, and still more preferably an alkyl group having 5 to 12 carbon atoms (n-hexyl group, 2-ethylhexyl group, n-octyl group). Group, n-decyl group, n-dodecyl group, benzyl group, etc.), particularly preferably a substituted or unsubstituted alkyl group having 6 to 12 carbon atoms (2-ethylhexyl group, n-octyl group). N-decyl group, n-dodecyl group, benzyl group).

The compound represented by the general formula (102) can be synthesized by a known method described in JP-A-11-12219.
Specific examples of the compound represented by the general formula (102) are given below, but the present invention is not limited to the following specific examples.

As the compound containing a cyano group, which is one of the wavelength dispersion adjusting agents used in the present invention, those represented by the general formula (103) are preferably used.
General formula (103)

（一般式（１０３）中、Ｑ³¹およびＱ³²はそれぞれ独立に芳香族環を表す。Ｘ³¹およびＸ³²はそれぞれ、水素原子または置換基を表し、少なくともどちらか１つはシアノ基、カルボニル基、スルホニル基、芳香族ヘテロ環を表す。）
Ｑ³¹およびＱ³²で表される芳香族環は芳香族炭化水素環でも芳香族ヘテロ環でもよい。また、これらは単環であってもよいし、さらに他の環と縮合環を形成してもよい。

(In the general formula (103), Q ³¹ and Q ³² each independently represent an aromatic ring. X ³¹ and X ³² each represent a hydrogen atom or a substituent, and at least one of them represents a cyano group or a carbonyl group. Represents a sulfonyl group or an aromatic heterocycle.)
The aromatic ring represented by Q ³¹ and Q ³² may be an aromatic hydrocarbon ring or an aromatic heterocycle. These may be monocyclic or may form a condensed ring with another ring.

  The aromatic hydrocarbon ring is preferably a monocyclic or bicyclic aromatic hydrocarbon ring having 6 to 30 carbon atoms (for example, benzene ring, naphthalene ring, etc.), more preferably 6 to 20 carbon atoms. It is an aromatic hydrocarbon ring, more preferably an aromatic hydrocarbon ring having 6 to 12 carbon atoms, and most preferably a benzene ring.

  The aromatic heterocycle is preferably an aromatic heterocycle containing a nitrogen atom or a sulfur atom. Specific examples of the hetero ring include, for example, thiophene ring, imidazole ring, pyrazole ring, pyridine ring, pyrazine ring, pyridazine ring, triazole ring, triazine ring, indole ring, indazole ring, purine ring, thiazoline ring, thiazole ring, thiadiazole. Ring, oxazoline ring, oxazole ring, oxadiazole ring, quinoline ring, isoquinoline ring, phthalazine ring, naphthyridine ring, quinoxaline ring, quinazoline ring, cinnoline ring, pteridine ring, acridine ring, phenanthroline ring, phenazine ring, tetrazole ring, benz Examples include an imidazole ring, a benzoxazole ring, a benzthiazole ring, a benzotriazole ring, and a tetrazaindene ring. The aromatic hetero ring is preferably a pyridine ring, a triazine ring or a quinoline ring.

The aromatic ring represented by Q ³¹ and Q ³² is preferably an aromatic hydrocarbon ring, more preferably a benzene ring.
Q ³¹ and Q ³² may further have a substituent, and the above-described substituent T is preferable.

X ³¹ and X ³² each represent a hydrogen atom or a substituent, and at least one of them represents a cyano group, a carbonyl group, a sulfonyl group, or an aromatic heterocycle. The substituent T described above can be applied to the substituents represented by X ³¹ and X ³² . In addition, the substituent represented by X ³¹ and X ³² may be further substituted with another substituent, and X ³¹ and X ³² may be condensed to form a ring structure.

X ³¹ and X ³² are preferably a hydrogen atom, an alkyl group, an aryl group, a cyano group, a nitro group, a carbonyl group, a sulfonyl group, or an aromatic heterocycle, and more preferably a cyano group, a carbonyl group, a sulfonyl group, An aromatic heterocycle, more preferably a cyano group or a carbonyl group, and particularly preferably a cyano group or an alkoxycarbonyl group (—C (═O) OR (R is an alkyl group having 1 to 20 carbon atoms, 6 carbon atoms). ˜12 aryl groups and combinations thereof.

As the general formula (103), a compound represented by the following general formula (103-A) is preferable.
General formula (103-A)

（一般式（１０３−Ａ）中、Ｒ³¹、Ｒ³²、Ｒ³³、Ｒ³⁴、Ｒ³⁵、Ｒ³⁶、Ｒ³⁷、Ｒ³⁸、Ｒ³⁹およびＲ³⁰はそれぞれ独立に水素原子または置換基を表す。Ｘ³¹およびＸ³²は一般式（１０３）におけるそれらと同義であり、また好ましい範囲も同様である。）

(In the general formula (103-A), R ³¹ , R ³² , R ³³ , R ³⁴ , R ³⁵ , R ³⁶ , R ³⁷ , R ³⁸ , R ³⁹ and R ³⁰ each independently represents a hydrogen atom or a substituent. X ³¹ and X ³² have the same meanings as those in formula (103), and preferred ranges are also the same.)

R ³¹ , R ³² , R ³⁴ , R ³⁵ , R ³⁶ , R ³⁷ , R ³⁹ and R ³⁰ each independently represent a hydrogen atom or a substituent, and the substituent T described above can be applied as the substituent. These substituents may be further substituted with another substituent, and the substituents may be condensed to form a ring structure.

R ³¹ , R ³² , R ³⁴ , R ³⁵ , R ³⁶ , R ³⁷ , R ³⁹ and R ³⁰ are preferably a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group, an amino group, an alkoxy group, an aryloxy group Group, a hydroxy group, and a halogen atom, more preferably a hydrogen atom, an alkyl group, an aryl group, an alkyloxy group, an aryloxy group, and a halogen atom, still more preferably a hydrogen atom and a carbon 1-12 alkyl group, Particularly preferred are a hydrogen atom and a methyl group, and most preferred is a hydrogen atom.

R ³³ and R ³⁸ are preferably a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group, an amino group, an alkoxy group, an aryloxy group, a hydroxy group, or a halogen atom, more preferably a hydrogen atom or a carbon number. An alkyl group having 1 to 20 carbon atoms, an amino group having 0 to 20 carbon atoms, an alkoxy group having 1 to 12 carbon atoms, an aryloxy group having 6 to 12 carbon atoms, and a hydroxy group, more preferably a hydrogen atom and 1 to 12 carbon atoms. An alkyl group having 1 to 12 carbon atoms, particularly preferably a hydrogen atom.

The general formula (103) is more preferably a compound represented by the following general formula (103-B).
General formula (103-B)

(In the general formula (103-B), R ³³ and R ³⁸ have the same meanings as those in the general formula (103-A), and preferred ranges are also the same. X ³³ represents a hydrogen atom or a substituent. .)

X ³³ represents a hydrogen atom or a substituent. As the substituent, the above-described substituent T can be applied, and if possible, the substituent may be further substituted with a substituent. X ³³ is preferably a hydrogen atom, an alkyl group, an aryl group, a cyano group, a nitro group, a carbonyl group, a sulfonyl group or an aromatic heterocycle, more preferably a cyano group, a carbonyl group, a sulfonyl group or an aromatic heterocycle. A ring, more preferably a cyano group or a carbonyl group, and particularly preferably a cyano group or an alkoxycarbonyl group (—C (═O) OR ³⁰¹ (R ³⁰¹ is an alkyl group having 1 to 20 carbon atoms, 6 to 6 carbon atoms). 12 aryl groups and combinations thereof)).

More preferred as the general formula (103) is a compound represented by the general formula (103-C).
General formula (103-C)

(In the general formula (103-C), R ³³ and R ³⁸ have the same meanings as those in the general formula (103-A), and preferred ranges thereof are also the same. R ³⁰² is an alkyl having 1 to 20 carbon atoms. Represents a group.)

R ³⁰² is preferably an alkyl group having 2 to 12 carbon atoms, more preferably an alkyl group having 4 to 12 carbon atoms, and more preferably when both R ³³ and R ³⁸ are hydrogen atoms, An alkyl group having 6 to 12 carbon atoms, particularly preferably an n-octyl group, a tert-octyl group, a 2-ethylhexyl group, an n-decyl group or an n-dodecyl group, most preferably 2-ethyl Hexyl group.

R ³⁰² is preferably an alkyl group having a molecular weight of 300 or more and a carbon number of 20 or less and a compound represented by the general formula (103-C) when R ³³ and R ³⁸ are other than hydrogen. Is preferred.

  The compound represented by the general formula (103) of the present invention can be synthesized by the method described in Journal of American Chemical Society 63, 3452 (1941).

  Specific examples of the compound represented by the general formula (103) are given below, but the present invention is not limited to the following specific examples.

Matting Agent Fine Particles It is preferable to add fine particles as a matting agent to the cellulose acylate film used in the present invention. The fine particles used in the present invention include silicon dioxide (silica), titanium dioxide, aluminum oxide, zirconium oxide, calcium carbonate, calcium carbonate, talc, clay, calcined kaolin, calcined calcium silicate, hydrated calcium silicate, silicic acid. Mention may be made of aluminum, magnesium silicate and calcium phosphate. Fine particles containing silicon are preferable from the viewpoint of low turbidity, and silicon dioxide is particularly preferable. The fine particles of silicon dioxide preferably have a primary average particle size of 20 nm or less and an apparent specific gravity of 70 g / liter or more. Those having an average primary particle size as small as 5 to 16 nm are more preferred because they can reduce the haze of the film. The apparent specific gravity is preferably 90 to 200 g / liter or more, and more preferably 100 to 200 g / liter or more. A larger apparent specific gravity is preferable because a high-concentration dispersion can be produced, and haze and aggregates are improved.

  These fine particles usually form secondary particles having an average particle size of 0.1 to 3.0 μm, and these fine particles exist in the film as aggregates of primary particles, and 0.1 to 0.1 μm on the film surface. An unevenness of 3.0 μm is formed. The secondary average particle size is preferably 0.2 μm to 1.5 μm, more preferably 0.4 μm to 1.2 μm, and most preferably 0.6 μm to 1.1 μm. For the primary and secondary particle sizes, the particles in the film were observed with a scanning electron microscope, and the diameter of a circle circumscribing the particles was defined as the particle size. In addition, 200 particles were observed at different locations, and the average value was taken as the average particle size.

  As fine particles of silicon dioxide, for example, commercially available products such as Aerosil R972, R972V, R974, R812, 200, 200V, 300, R202, OX50, TT600 (above Nippon Aerosil Co., Ltd.) can be used. 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.

  Among these, Aerosil 200V and Aerosil R972V are fine particles of silicon dioxide having a primary average particle size of 20 nm or less and an apparent specific gravity of 70 g / liter or more, and the coefficient of friction is maintained while keeping the turbidity of the optical film low. It is particularly preferable because it has a great effect of reducing the effect.

In order to obtain a cellulose acylate film having particles having a small secondary average particle size in the present invention, several methods are conceivable when preparing a fine particle dispersion. For example, a method of preparing a fine particle dispersion in which a solvent and fine particles are mixed with stirring in advance, adding this fine particle dispersion to a small amount of cellulose acylate solution separately prepared, stirring and dissolving, and further mixing with the main cellulose acylate dope solution There is. This method is a preferable preparation method in that the dispersibility of the silicon dioxide fine particles is good and the silicon dioxide fine particles are more difficult to reaggregate. In addition, after adding a small amount of cellulose ester to the solvent and dissolving with stirring, add the fine particles to this and disperse with a disperser to make this fine particle additive solution, and mix this fine particle additive solution with the dope solution using an inline mixer There is also a way to do it. Although this invention is not limited to these methods, 5-30 mass% is preferable, as for the density | concentration of silicon dioxide when silicon dioxide microparticles | fine-particles are mixed and disperse | distributed with a solvent etc., 10-25 mass% is more preferable, 15-20 Mass% is most preferred. A higher dispersion concentration is preferable because the liquid turbidity with respect to the added amount is lowered, and haze and aggregates are improved. The addition amount of the matting agent in the final cellulose acylate dope solution is preferably 0.01 to 1.0 g, more preferably 0.03 to 0.3 g, and 0.08 to 0.16 g per 1 m ^2. Most preferred.

  The solvent used is preferably lower alcohols such as methyl alcohol, ethyl alcohol, propyl alcohol, isopropyl alcohol, butyl alcohol and the like. Although it does not specifically limit as solvents other than a lower alcohol, It is preferable to use the solvent used at the time of film forming of a cellulose ester. Examples thereof include a solvent selected from halogenated hydrocarbons having 1 to 7 carbon atoms. One type of solvent may be used, or two or more types may be used in combination.

Plasticizer, deterioration preventing agent, release agent In addition to the above-mentioned compound for reducing optical anisotropy and wavelength dispersion adjusting agent, the cellulose acylate film of the present invention has various additives depending on the application in each preparation step. (For example, a plasticizer, an ultraviolet ray inhibitor, a deterioration inhibitor, a release agent, an infrared absorber, etc.) can be added, and they may be solid or oily. That is, the melting point and boiling point are not particularly limited. For example, mixing of ultraviolet absorbing material at 20 ° C. or lower and 20 ° C. or higher, and similarly, mixing of a plasticizer is described in, for example, JP-A-2001-151901. Furthermore, infrared absorbing dyes are described, for example, in JP-A No. 2001-194522. Moreover, the addition time may be added at any time in the dope preparation step, but may be added by adding an additive to the final preparation step of the dope preparation step. Furthermore, the amount of each material added is not particularly limited as long as the function is manifested. Moreover, when a cellulose acylate film is formed from a multilayer, the kind and addition amount of the additive of each layer may differ. For example, it is described in Japanese Patent Application Laid-Open No. 2001-151902, but these are conventionally known techniques. For these details, materials described in detail on pages 16 to 22 in the Japan Institute of Invention Disclosure Technical Report (Public Technical Number 2001-1745, published on March 15, 2001, Japan Institute of Invention) are preferably used.

Ratio of Compound Addition In the cellulose acylate film that can be used in the present invention, the total amount of compounds having a molecular weight of 3000 or less is preferably 5 to 45% based on the weight of cellulose acylate. More preferably, it is 10-40%, More preferably, it is 15-30%. As described above, these compounds include compounds that reduce optical anisotropy, wavelength dispersion regulators, ultraviolet inhibitors, plasticizers, deterioration inhibitors, fine particles, release agents, infrared absorbers, etc. Is preferably 3000 or less, more preferably 2000 or less, and even more preferably 1000 or less. When the total amount of these compounds is 5% or less, the properties of cellulose acylate alone are likely to be obtained, and there are problems such as that the optical performance and physical strength are likely to vary with changes in temperature and humidity. Moreover, when the total amount of these compounds is 45% or more, problems such as exceeding the limit of compatibility of the compounds in the cellulose acylate film and depositing on the film surface and causing the film to become cloudy (crying out of the film) occur. It becomes easy.

Organic Solvent of Cellulose Acylate Solution In the present invention, it is preferable to produce a cellulose acylate film by a solvent cast method, and the film is produced using a solution (dope) in which cellulose acylate is dissolved in an organic solvent. The organic solvent preferably used as the main solvent of the present invention is preferably a solvent selected from esters, ketones, ethers having 3 to 12 carbon atoms, and halogenated hydrocarbons having 1 to 7 carbon atoms. Esters, ketones and ethers may have a cyclic structure. A compound having two or more functional groups of esters, ketones and ethers (that is, —O—, —CO— and —COO—) can also be used as a main solvent. It may have a functional group of In the case of the main solvent having two or more kinds of functional groups, the number of carbon atoms may be within the specified range of the compound having any functional group.

  As described above, for the cellulose acylate film that can be used in the present invention, a chlorinated halogenated hydrocarbon may be used as a main solvent, and it is described in JIII Journal of Technical Disclosure 2001-1745 (pages 12 to 16). As described above, a non-chlorine solvent may be used as the main solvent, and the cellulose acylate film that can be used in the present invention is not particularly limited.

  In addition, the solvent for the cellulose acylate solution and film of the present invention is disclosed in the following patents, including its dissolution method, and is a preferred embodiment. For example, JP-A-2000-95876, JP-A-12-95877, JP-A-10-324774, JP-A-8-152514, JP-A-10-330538, JP-A-9-95538, and JP-A-9 JP-A-95557, JP-A-10-235664, JP-A-12-63534, JP-A-11-21379, JP-A-10-182853, JP-A-10-278056, JP-A-10-279702, JP-A-10- 323853, JP-A-10-237186, JP-A-11-60807, JP-A-11-152342, JP-A-11-292988, JP-A-11-60752, JP-A-11-60752, and the like. ing. According to these patents, not only the preferred solvent for the cellulose acylate of the present invention but also the physical properties of the solution and the coexisting substances to be coexisted are described, which is also a preferred embodiment in the present invention.

Manufacturing process of cellulose acylate film Dissolution process The preparation of the cellulose acylate solution (dope) of the present invention is not particularly limited, and it may be performed at room temperature, or a cooling dissolution method or a high temperature dissolution method, or a combination thereof. Will be implemented. Regarding the preparation of the cellulose acylate solution in the present invention, and further the steps of solution concentration and filtration associated with the dissolution step, the Technical Report of the Japan Society of Invention (Publication No. 2001-1745, published on March 15, 2001, Japan Society of Invention) The manufacturing process described in detail on pages 22 to 25 is preferably used.

Transparency of dope solution The dope transparency of the cellulose acylate solution used in the present invention is preferably 85% or more, more preferably 88% or more, and further preferably 90% or more. In the present invention, it was confirmed that various additives were sufficiently dissolved in the cellulose acylate dope solution. As a specific method for calculating the dope transparency, the dope solution was poured into a 1 cm square glass cell, and the absorbance at 550 nm was measured with a spectrophotometer (UV-3150, Shimadzu Corporation). Only the solvent was measured in advance as a blank, and the transparency of the cellulose acylate solution was calculated from the ratio with the absorbance of the blank.

Casting, drying, winding process Next, a method for producing a cellulose acylate film using the cellulose acylate solution of the present invention will be described. As a method and equipment for producing a cellulose acylate film that can be used in the present invention, a solution casting film forming method and a solution casting film forming apparatus conventionally used for producing a cellulose triacetate film can be used. For example, a dope (cellulose acylate solution) prepared from a dissolving machine (kettle) is temporarily stored in a storage kettle, and the foam contained in the dope is defoamed for final preparation. The dope is fed from the dope discharge port to the pressure die through a pressure metering gear pump capable of delivering a constant amount of liquid with high accuracy, for example, by the number of rotations. The dry-dried dope film (also referred to as a web) is peeled off from the metal support at the peeling point which is uniformly cast on the metal support and the metal support has almost gone around. The both ends of the obtained web are sandwiched between clips, transported by a tenter while holding the width and dried, and then the obtained film is mechanically transported by a roll group of a drying device, dried, and then rolled by a winder Wind up to a predetermined length. The combination of the tenter and the roll group dryer varies depending on the purpose. Furthermore, the cellulose acylate film used in the present invention is often provided with a coating device for surface processing to a polarizing film. These are described in detail on pages 25-30 in the Japan Society for Invention and Innovation Technical Report (Public Technical Number 2001-1745, issued on March 15, 2001, Japan Society for Invention). Including), metal support, drying, peeling and the like, and can be preferably used in the present invention.
Moreover, 10-120 micrometers is preferable, as for the thickness of a cellulose acylate film, 20-100 micrometers is more preferable, and 30-90 micrometers is more preferable.

Change in optical performance of cellulose acylate film after high-humidity treatment Evaluation of physical properties of cellulose acylate film Regarding the change in optical performance due to environmental change of cellulose acylate film that can be used in the present invention, 240 hours at 60 ° C. and 90% RH The amount of change in Re and Rth of the treated cellulose acylate film is preferably 15 nm or less. More preferably, it is 12 nm or less, and further preferably 10 nm or less.
Change in optical performance of film after high temperature treatment Further, it is preferable that the amount of change in Re and Rth of the cellulose acylate film treated at 80 ° C. for 240 hours is 15 nm or less. More preferably, it is 12 nm or less, and further preferably 10 nm or less.
Compound volatilization amount after film heat treatment In the cellulose acylate film used in the present invention, the compound that lowers Rth and the compound that lowers ΔRth have a volatilization amount of 30 from the cellulose acylate film treated at 80 ° C. for 240 hours. % Or less is preferable. More preferably, it is 25% or less, and more preferably 20% or less.
The volatilization amount from the cellulose acylate film was determined by dissolving the film treated at 80 ° C. for 240 hours and the untreated cellulose acylate film in a solvent, detecting the compound by liquid high-speed chromatography, and detecting the peak area of the compound Was calculated by the following formula as the amount of the compound remaining in the film.
Volatilization amount (%) = {(remaining compound amount in untreated product) − (remaining compound amount in treated product)} / (remaining compound amount in untreated product) × 100

Glass transition temperature (Tg) of cellulose acylate film
The glass transition temperature Tg of the cellulose acylate film that can be used in the present invention is 80 to 165 ° C. From the viewpoint of heat resistance, Tg is more preferably 100 to 160 ° C, and particularly preferably 110 to 150 ° C. The measurement of the glass transition temperature (Tg) was carried out using a differential scanning calorimeter (DSC 2910, TA in) with a cellulose acylate film sample of 10 mg that can be used in the present invention at a temperature increase / decrease rate of 5 ° C./min. The calorimetric measurement can be carried out with the instrument, and the glass transition temperature (Tg) can be calculated.

Haze of cellulose acylate film The haze of the cellulose acylate film that can be used in the present invention is preferably 0.01 to 2.0%. More preferably, it is 0.05 to 1.5%, and further preferably 0.1 to 1.0%. The haze is measured by, for example, a cellulose acylate film sample 40 mm × 80 mm that can be used in the present invention at 25 ° C. and 60% RH using a haze meter (HGM-2DP, Suga Test Instruments) and JIS K-6714. Can be measured according to.

Humidity dependency of Re and Rth of cellulose acylate film Both the in-plane retardation (Re) and the thickness direction retardation (Rth) of the cellulose acylate film that can be used in the present invention are small in change due to humidity. Is preferred. Specifically, the difference ΔRth (= Rth10% RH−Rth80% RH) between the Rth value at 25 ° C. and 10% RH and the Rth value at 25 ° C. and 80% RH is preferably 0 to 50 nm. More preferably, it is 0-40 nm, More preferably, it is 0-35 nm.

Equilibrium moisture content of cellulose acylate film The cellulose acylate film used in the present invention does not impair the adhesiveness with a water-soluble polymer such as polyvinyl alcohol. The equilibrium moisture content is preferably 0 to 4%, more preferably 0.1 to 3.5%, and particularly preferably 1 to 3%. By setting the equilibrium moisture content to 4% or less, the dependency of retardation due to humidity change can be further reduced, which is preferable.
The water content of the present invention was measured by a Karl Fischer method using a cellulose acylate film sample 7 mm × 35 mm with a moisture measuring device and a sample drying apparatus (CA-03, VA-05, both Mitsubishi Chemical Corporation). It can be calculated by dividing (g) by the sample weight (g).

Moisture permeability of cellulose acylate film The moisture permeability of the cellulose acylate film that can be used in the present invention is measured under conditions of a temperature of 60 ° C. and a humidity of 95% RH based on JIS standard JISZ0208, and converted to a film thickness of 80 μm. And it is preferable that it is 400-2000 g / m < ² > * 24h. More preferably 500~1800g / m ² · 24h, and particularly preferably 600~1600g / m ² · 24h. By setting it to 2000 g / m ² · 24 h or less, the absolute value of the humidity dependency of Re and Rth of the cellulose acylate film can be easily maintained at 0.5 nm /% RH or less, and the liquid crystal display device It is possible to more effectively suppress changes in color and viewing angle. In addition, by setting the moisture permeability of the cellulose acylate film to 400 g / m ² · 24 h or more, the adhesive of the cellulose acylate film can be easily dried and the adhesiveness is improved.
If the film thickness of the cellulose acylate film is thick, the moisture permeability becomes small, and if the film thickness is thin, the moisture permeability becomes large. Therefore, it is preferable to convert the sample with any film thickness to a standard of 80 μm. In the present invention, the film thickness was obtained as 80 μm-converted moisture permeability = measured moisture permeability × measured film thickness μm / 80 μm.
The measurement method of moisture permeability is “Polymer Properties II” (Polymer Experiment Course 4, Kyoritsu Shuppan), pages 285-294: Measurement of vapor permeation (mass method, thermometer method, vapor pressure method, adsorption amount method) The cellulose acylate film sample 70 mmφ that can be used in the present invention is conditioned at 25 ° C., 90% RH, 60 ° C., and 95% RH for 24 hours, respectively. (KK-709007, Toyo Seiki Co., Ltd.) calculates the amount of moisture per unit area (g / m ² ) according to JIS Z-0208, and obtains moisture permeability = weight after humidity adjustment−weight before humidity adjustment. It was.

Dimensional change of film The dimensional stability of the cellulose acylate film that can be used in the present invention is the dimensional change rate when the film is allowed to stand for 24 hours at 60 ° C. and 90% RH (high humidity) and 90%. It is preferable that the dimensional change rate when standing at 24 ° C. for 24 hours under the conditions of 5 ° C. and 5% RH is 0.5% or less.
More preferably, it is 0.3% or less, More preferably, it is 0.15% or less.
The dimensional change rate of the present invention is determined by the method described below. That is, two cellulose acylate film samples 30 mm × 120 mm were prepared, humidity-controlled at 25 ° C. and 60% RH for 24 hours, and an automatic pin gauge (Shinto Kagaku Co., Ltd.) with 6 mmφ holes at both ends. Opened at intervals, the original size (L ₀ ) of the punch interval. After measuring the punch interval dimension (L ₁ ) after one sample was treated at 60 ° C. and 90% RH for 24 hours, the other sample was treated at 90 ° C. and 5% RH for 24 hours. The dimension (L ₂ ) of the punch interval was measured. Measurement was made to a minimum scale of 1/1000 mm at all intervals. Dimensional change rate of 60 ° C. and 90% RH (high humidity) = {| L ₀ −L ₁ | / L ₀ } × 100, Dimensional change rate of 90 ° C. and 5% RH (high temperature) = {| L ₀ The dimensional change rate was determined as −L ₂ | / L ₀ } × 100.

Elastic modulus of film (elastic modulus)
Elastic modulus of the cellulose acylate film that can be used in the present invention is preferably 200 to 500 kgf / mm ^2, more preferably 240~470kgf / mm ^2, more preferably at 270~440kgf / mm ² is there. The elastic modulus of the present invention is a value obtained by measuring a stress at 0.5% elongation at 23%, 70% atmosphere and a tensile rate of 10% / min using Toyo Baldwin Universal Tensile Tester STM T50BP. .

Photoelastic coefficient of film (photoelastic coefficient)
The photoelastic coefficient of the cellulose acylate film that can be used in the present invention is preferably 50 × 10 ⁻¹³ cm ² / dyne or less, more preferably 30 × 10 ⁻¹³ cm ² / dyne or less, More preferably, it is 20 × 10 ⁻¹³ cm ² / dyne or less. The photoelastic coefficient is determined by applying a tensile stress to the major axis direction of a 12 mm x 120 mm cellulose acylate film sample, and measuring the retardation with an ellipsometer (M150, JASCO Corporation). It can be calculated from the amount of change.

Front retardation change before and after stretching, detection of slow axis Sample 100 x 100 mm is prepared, and using a fixed uniaxial stretching machine at a temperature of 140 ° C in the machine transport direction (MD direction) or the vertical direction (TD direction) Stretching was performed. The front retardation of each sample before and after stretching was measured using an automatic birefringence meter KOBRA21ADH. The detection of the slow axis was determined from the orientation angle obtained during the retardation measurement. It is preferable that the change in Re by stretching is small. Specifically, in-plane front retardation (nm) of a film obtained by stretching Re _(n) by n (%), in-plane of a film not stretched by Re ₍₀₎ It is preferable to have | Re _(n) −Re ₍₀₎ | /n≦1.0 when the front retardation (nm) is satisfied, and | Re _(n) −Re ₍₀₎ | / n ≦ 0. 3 or less is more preferable.

The direction having a slow axis The cellulose acylate film that can be used in the present invention has a absorption axis in the machine transport direction (MD direction) of the polarizing film, and therefore the cellulose acylate film has a slow axis in the vicinity of the MD direction or TD. It is preferable to be in the vicinity. Light leakage and color change can be reduced by making the slow axis parallel or orthogonal to the polarizing film. The vicinity means that, for example, the slow axis and the MD or TD direction are in the range of 0 to 10 °, preferably 0 to 5 °.

Cellulose acylate film having positive intrinsic birefringence The cellulose acylate film that can be used in the present invention has a slow axis when it is stretched in a direction having a slow axis in the plane of the film. When the film is stretched in a direction perpendicular to the direction, the front retardation is reduced. This indicates that the intrinsic birefringence is positive, and it is effective to stretch in the direction perpendicular to the slow axis in order to cancel the retardation developed in the cellulose acylate film. As this method, for example, when the film has a slow axis in the machine conveyance direction (MD direction), the front retardation can be reduced by using tenter stretching in a direction perpendicular to MD (TD direction). Conceivable. As an opposite example, when the TD direction has a slow axis, it is conceivable to reduce the front retardation by increasing the tension of the machine transport roll in the MD direction and stretching.

Cellulose acylate film having negative intrinsic birefringence The cellulose acylate film that can be used in the present invention has a smaller front retardation when stretched in a direction having a slow axis, and a direction perpendicular to the direction having a slow axis. When the film is stretched, the front retardation may increase. This indicates that the intrinsic birefringence is negative, and it is effective to stretch in the same direction as the slow axis in order to cancel the retardation developed in the film. As this method, for example, when the cellulose acylate film has a slow axis in the machine conveyance direction (MD direction), the front retardation is reduced by increasing the tension of the machine conveyance roll in the MD direction and stretching. It is possible. As an opposite example, when the TD direction has a slow axis, it is conceivable to reduce the front retardation by using tenter stretching in a direction perpendicular to the MD (TD direction).

Evaluation Method of Cellulose Acylate Film In the evaluation of the cellulose acylate film that can be used in the present invention, in the Examples of the present invention described later, measurement was performed by the following method.
(In-plane retardation Re, thickness direction retardation Rth)
Samples 30mm × 40mm, 25 ℃, dampening 2 hours conditioned at 60% RH, Re _(λ) is the incident light of a wavelength λnm the film normal direction in an automatic birefringence meter KOBRA21ADH (manufactured by Oji Scientific Instruments Co.) And measured. Rth ₍ λ ₎ is the Re ₍ λ ₎ and incident light of wavelength λnm with the slow axis in the plane as the tilt axis and the film normal direction as 0 ° and the sample tilted to 50 ° every 10 ° Based on the measured retardation value, the assumed average refractive index of 1.48 and the film thickness were input and calculated.

(Measurement of chromatic dispersion of Re and Rth)
A sample 30mm x 40mm was conditioned at 25 ° C and 60% RH for 2 hours, and Re ₍ λ ₎ was measured by making light of wavelength λnm incident in the normal direction of the film in KOBRA 21ADH (manufactured by Oji Scientific Instruments). Is done. Rth _(lambda) is the Re _(lambda), the slow axis wavelength from the tilt axis direction tilted + 40 ° (rotation axis) as relative to the normal direction of the film (KOBRA 21ADH is judged by) [lambda] nm in the plane light And retardation measured by injecting light of wavelength λ nm from a direction inclined by -40 ° with respect to the film normal direction with the in-plane slow axis as the tilt axis (rotation axis) KOBRA 21ADH calculates based on the retardation measured in three directions, the assumed average refractive index, and the input film thickness value. Here, as the assumed value of the average refractive index, the values in the polymer handbook (JOHN WILEY & SONS, INC) and catalogs of various optical films can be used. Those whose average refractive index is not known can be measured with an Abbe refractometer. The average refractive index values of the main optical films are exemplified below: cellulose acylate (1.48), cycloolefin polymer (1.52), polycarbonate (1.59), polymethyl methacrylate (1.49), Polystyrene (1.59). The KOBRA 21ADH calculates nx, ny, and nz by inputting these assumed values of average refractive index and film thickness. Nz = (nx−nz) / (nx−ny) is further calculated from the calculated nx, ny and nz.

(Molecular orientation axis)
A sample 70 mm x 100 mm was conditioned at 25 ° C and 65% RH for 2 hours, and the molecule was calculated from the phase difference when the incident angle at normal incidence was changed with an automatic birefringence meter (KOBRA21DH, Oji Scientific Co., Ltd.) The orientation axis was calculated.
(Axis misalignment)
Moreover, the axis | shaft misalignment angle was measured with the automatic birefringence meter (KOBRA-21ADH, Oji Scientific Instruments). Twenty points were measured at equal intervals over the entire width in the width direction, and the average absolute value was determined. The range of the slow axis angle (axis deviation) is the measurement of 20 points at equal intervals over the entire width direction, and the difference between the average of the four points from the larger absolute value of the axis deviation and the average of the four points from the smaller one. It is what took.

(Transmittance)
The transmittance of visible light (615 nm) was measured on a 20 mm × 70 mm sample at 25 ° C. and 60% RH with a transparency measuring instrument (AKA phototube colorimeter, KOTAKI Corporation).
(Spectral characteristics)
A sample 13 mm × 40 mm was measured for transmittance at a wavelength of 300 to 450 nm with a spectrophotometer (U-3210, Hitachi, Ltd.) at 25 ° C. and 60% RH. The inclination width was obtained at a wavelength of 72% -5%. The limit wavelength was expressed by a wavelength of (gradient width / 2) + 5%. The absorption edge is represented by a wavelength with a transmittance of 0.4%. From this, the transmittances at 380 nm and 350 nm were evaluated.

Properties of Cellulose Acylate Film Surface The surface of the cellulose acylate film that can be used in the present invention has an arithmetic average roughness (Ra) of surface irregularities of the film based on JIS B0601-1994 of 0.1 μm or less, and a maximum height. (Ry) is preferably 0.5 μm or less. Preferably, the arithmetic average roughness (Ra) is 0.05 μm or less, and the maximum height (Ry) is 0.2 μm or less. The concave and convex shapes on the film surface can be evaluated by an atomic force microscope (AFM).

In-plane variation of retardation of cellulose acylate film The cellulose acylate film that can be used in the present invention preferably satisfies the following formula.
| Re _(MAX) −Re _(MIN) | ≦ 3 and | Rth _(MAX) −Rth _(MIN) | ≦ 5
In the formula, Re _(MAX) and Rth _(MAX) − are the maximum retardation values of 1 m square film cut out arbitrarily, and Re _(MIN) and Rth _(MIN) are the minimum values.

Retaining property of cellulose acylate film In the cellulose acylate film that can be used in the present invention, the retentivity of various compounds added to the film is required. Specifically, the mass change of the film when the cellulose acylate film that can be used in the present invention is allowed to stand for 48 hours at 80 ° C. and 90% RH is preferably 0 to 5%. More preferably, it is 0 to 3%, and still more preferably 0 to 2%.
(Method for evaluating holdability)
The sample was cut to a size of 10 cm × 10 cm, and the mass after being allowed to stand for 24 hours in an atmosphere of 23 ° C. and 55% RH was measured, and left for 48 hours under the conditions of 80 ± 5 ° C. and 90 ± 10% RH. . The surface of the sample after the treatment was lightly wiped, the mass after standing for 1 day at 23 ° C. and 55% RH was measured, and the retention was calculated by the following method.
Retention property (mass%) = {(mass before standing−mass after standing) / mass before standing} × 100

(Mechanical properties of film)
Curl The curl value in the width direction of the cellulose acylate film that can be used in the present invention is preferably −10 / m to + 10 / m. The cellulose acylate film that can be used in the present invention has a curl value in the width direction of the cellulose acylate film that can be used in the present invention within the above-mentioned range when performing a long pasting or the like. Therefore, it is possible to more effectively prevent the handling of the film from being hindered and the film from being cut. In addition, the film is strongly in contact with the transport roll at the edge and center of the film, so it is easy to generate dust, and foreign matter adheres to the film. Exceeding the value can be more effectively prevented. Furthermore, it is preferable also from a viewpoint which can prevent a bubble entering at the time of bonding with a polarizing film.
The curl value can be measured according to a measurement method (ANSI / ASCPH1.29-1985) defined by the American National Standards Institute.

(Tear strength)
The tear strength (Elmendorf tear method) based on the tear test method of JISK7128-2: 1998 is preferably 2 g or more when the film thickness of the cellulose acylate film that can be used in the present invention is in the range of 20 to 80 μm. More preferably, it is 5-25g, More preferably, it is 6-25g. Moreover, 8 g or more is preferable at 60 micrometer conversion, More preferably, it is 8-15g. Specifically, it can be measured using a light load tear strength tester after conditioning a sample piece of 50 mm × 64 mm under the conditions of 25 ° C. and 65% RH for 2 hours.

Residual solvent amount of cellulose acylate film It is preferable that the residual solvent amount with respect to the cellulose acylate film that can be used in the present invention is dried under the condition of 0.01 to 1.5% by mass, more preferably 0. 0.01 to 1.0% by mass. Curling can be suppressed by setting the residual solvent amount of the polarizing film used in the present invention to 1.5% or less. More preferably, it is 1.0% or less. This is probably because free deposition is reduced by reducing the amount of residual solvent during film formation by the above-described solvent casting method.

Hygroscopic expansion coefficient of cellulose acylate film The hygroscopic expansion coefficient of the cellulose acylate film that can be used in the present invention is preferably 30 × 10 ⁻⁵ /% RH or less. The hygroscopic expansion coefficient is preferably 15 × 10 ⁻⁵ /% RH or less, and more preferably 10 × 10 ⁻⁵ /% RH or less. The hygroscopic expansion coefficient is preferably small, but usually it is 1.0 × 10 ⁻⁵ /% RH or more. The hygroscopic expansion coefficient indicates the amount of change in the length of the sample when the relative humidity is changed at a constant temperature.

Surface Treatment The cellulose acylate film can achieve improved adhesion to the cellulose acylate film by optionally performing a surface treatment. For example, glow discharge treatment, ultraviolet irradiation treatment, corona treatment, flame treatment, acid or alkali treatment can be used. The glow discharge treatment here may be low-temperature plasma that occurs in a low-pressure gas of 10 ^{−3 to} 20 Torr, and plasma treatment under atmospheric pressure is also preferable. A plasma-excitable gas is a gas that is plasma-excited under the above conditions, and examples thereof include chlorofluorocarbons such as argon, helium, neon, krypton, xenon, nitrogen, carbon dioxide, tetrafluoromethane, and mixtures thereof. It is done. Details of these are described in detail in pages 30 to 32 in the Japan Institute of Invention Disclosure Technical Bulletin (Public Technical No. 2001-1745, published on March 15, 2001, Japan Institute of Invention), and are preferably used in the present invention. be able to.

Contact angle of cellulose acylate film surface by alkali saponification treatment One effective means for surface treatment of the cellulose acylate film that can be used in the present invention is alkali saponification treatment. In this case, the contact angle on the surface of the cellulose acylate film after the alkali saponification treatment is preferably 55 ° or less. More preferably, it is 50 ° or less, and further preferably 45 ° or less. The contact angle evaluation method can be used as an evaluation of hydrophilicity / hydrophobicity by an ordinary method in which a water droplet having a diameter of 3 mm is dropped on the surface of the film after the alkali saponification treatment and the angle formed by the surface of the cellulose acylate film and the water droplet is obtained.

Light Resistance As an index of light durability of the cellulose acylate film that can be used in the present invention, the color difference ΔE * ab of the cellulose acylate film irradiated with super xenon light for 240 hours is preferably 20 or less. More preferably, it is 18 or less, and it is still more preferable that it is 15 or less. The color difference can be measured using, for example, UV3100 (manufactured by Shimadzu Corporation). The measurement is carried out by adjusting the cellulose acylate film to 25 ° C. and 60% RH for 2 hours and then measuring the color of the cellulose acylate film before irradiation with xenon light, and initial values (L0 ^* , a0 ^* , b0 ^* ). Ask for. Then, the cellulose acylate film alone is irradiated with xenon light for 240 hours under the conditions of 150 W / m ² , 60 ° C. and 50% RH with Super Xenon Weather Meter SX-75 (manufactured by Suga Test Instruments Co., Ltd.). After the elapse of a predetermined time, the cellulose acylate film is taken out from the thermostatic bath, conditioned at 25 ° C. and 60% RH for 2 hours, then subjected to color measurement again, and values after irradiation (L1 ^* , a1 ^* , b1 ^* ). Asked. From these, the color difference ΔE ^* ab = ((L0 ^* −L1 ^* ) ^ 2+ (a0 ^* −a1 ^* ) ^ 2+ (b0 ^* −b1 ^* ) ^ 2) ^ 0.5 can be measured.

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

[Integrated manufacturing process of polarizing film and protective film]
The polarizing plate used in the present invention usually has a drying step in which the polarizing film is stretched and then contracted to reduce the volatile content rate, but after drying or after a protective film is bonded to at least one side during drying, It is preferable to have a heating step. In an aspect in which the protective film also serves as a support for an optical compensation film that functions as an optical compensation layer, heating is performed after laminating a transparent support having a protective film on one side and an optical compensation film on the opposite side. preferable. As a specific attaching method, during the film drying process, a protective film is attached to the polarizing film with an adhesive while holding both ends, and then both ends are cut off, or after drying, polarized from the both end holding portions. There is a method of releasing a film for a film, cutting off both ends of the film, and then attaching a protective film. As a method for cutting off the ears, general techniques such as a method of cutting with a cutter such as a blade or a method of using a laser can be used. After bonding, it is preferable to heat in order to dry the adhesive and to improve the polarization performance. The heating condition varies depending on the adhesive, but in the case of an aqueous system, it is preferably 30 ° C. or higher, more preferably 40 to 100 ° C., and further preferably 50 to 90 ° C. It is more preferable in terms of performance and production efficiency that these processes are manufactured in a consistent line.

[Performance of polarizing plate]
The optical properties and durability (short-term and long-term storage stability) of the polarizing plate comprising the protective film, polarizer and transparent support in the present invention are commercially available super high contrast products (for example, HLC2- manufactured by Sanlitz Co., Ltd.). 5618 or the like) is preferable. Specifically, the visible light transmittance is 42.5% or more, and the degree of polarization {(Tp−Tc) / (Tp + Tc)} ^1/2 ≧ 0.9995 (where Tp is parallel transmittance and Tc is orthogonal transmission) The rate of change in light transmittance before and after standing in an atmosphere of 60 ° C. and humidity 90% RH for 500 hours and 80 ° C. in a dry atmosphere for 500 hours is 3% or less based on the absolute value, Further, it is preferably 1% or less, and the rate of change in polarization degree is preferably 1% or less, more preferably 0.1% or less based on the absolute value.

[Optical compensation film]
The optical compensation film is used in a liquid crystal display device to eliminate image coloring or to expand a viewing angle. In the present invention, as described above, the optical compensation film is not an essential member. For example, in an aspect in which birefringence is added to one or both of the pair of protective films of the polarizing plate to function as the optical compensation film. It is not necessary to provide a separate optical compensation film.

Examples of the liquid crystalline compound forming the optical compensation film include rod-like liquid crystalline molecules and discotic liquid crystalline molecules. The rod-like liquid crystal molecule and the discotic liquid crystal molecule (discotic liquid crystal compound) may be a high-molecular liquid crystal or a low-molecular liquid crystal.
When a rod-like liquid crystalline compound is used for producing the optically anisotropic layer, the orientation direction of the rod-like liquid crystalline molecules may be perpendicular, parallel or hybrid orientation to the protective film surface. In the case of vertical and parallel, it is preferable that the average direction of the axis projected on the support surface is parallel to the orientation axis. Further, when a discotic liquid crystalline compound is used for the production of the optically anisotropic layer, the average direction of the axis of the discotic liquid crystalline molecule projected on the support surface is parallel to the alignment axis. Is preferred. Further, the hybrid orientation described later in which the angle (inclination angle) formed by the disk surface and the layer plane changes in the depth direction may be used.

《Bar-shaped liquid crystalline molecules》
As rod-like liquid crystalline molecules, azomethines, azoxys, cyanobiphenyls, cyanophenyl esters, benzoic acid esters, cyclohexanecarboxylic acid phenyl esters, cyanophenylcyclohexanes, cyano-substituted phenylpyrimidines, alkoxy-substituted phenylpyrimidines , Phenyldioxanes, tolanes and alkenylcyclohexylbenzonitriles are preferably used.
The rod-like liquid crystalline molecule includes a metal complex. In addition, a liquid crystal polymer containing a rod-like liquid crystalline molecule in a repeating unit can also be used as the rod-like liquid crystalline molecule. In other words, the rod-like liquid crystal molecule may be bonded to a (liquid crystal) polymer.
For rod-like liquid crystalline molecules, see Chapter 4, Chapter 7 and Chapter 11 of the Chemical Chemistry of the Quarterly Chemical Review Vol. 22, Liquid Crystal Chemistry (1994), and the 142nd Committee of the Japan Society for the Promotion of Science. Described in Chapter 3. The birefringence of the rod-like liquid crystal molecule is preferably in the range of 0.001 to 0.7.

  The rod-like liquid crystalline molecule preferably has a polymerizable group in order to fix its alignment state. The polymerizable group is preferably a radically polymerizable unsaturated group or a cationically polymerizable group. Specifically, for example, the polymerizable groups described in paragraphs [0064] to [0086] of JP-A-2002-62427 are described. Group and a polymerizable liquid crystal compound.

《Discotic liquid crystalline compound》
The discotic liquid crystalline compound is aligned substantially perpendicular to the polymer film surface. Discotic liquid crystalline compounds are disclosed in various documents (C. Destrade et al., Mol. Crysr. Liq. Cryst., Vol. 71, page 111 (1981); edited by the Chemical Society of Japan, Quarterly Chemical Review, No. 22, Chemistry of liquid crystals, Chapter 5, Chapter 10 Section 2 (1994); B. Kohne et al., Angew. Chem. Soc. Chem. Comm., Page 1794 (1985); J. Zhang et al., J .Am.Chem.Soc., Vol.116, page 2655 (1994)) can be widely used.

The discotic liquid crystalline compound preferably has a polymerizable group, for example, as described in JP-A-8-27284 so that it can be fixed by polymerization. For example, a structure in which a polymerizable group is bonded as a substituent to the discotic core of a discotic liquid crystalline compound can be considered, but if a polymerizable group is directly connected to the discotic core, the alignment state can be maintained in the polymerization reaction. It becomes difficult. Therefore, a structure having a linking group between the discotic core and the polymerizable group is preferable. That is, the discotic liquid crystalline compound having a polymerizable group is preferably a compound represented by the following formula (III).
Formula (III) D (-LP) n
In formula (III), D is a discotic core, L is a divalent linking group, P is a polymerizable group, and n is an integer of 4 to 12.

  Preferred specific examples of the discotic core (D), the divalent linking group (L), and the polymerizable group (P) in the formula (III) are (D1) described in JP-A No. 2001-4837, respectively. To (D15), (L1) to (L25), and (P1) to (P18), and the contents described in the publication can be preferably used.

  These liquid crystalline compounds are substantially vertically aligned with the substrate surface in the optical compensation film. Here, “substantially on the substrate surface” means, for example, being parallel to the substrate surface or shifted by ± 5 degrees. Further, it is preferably substantially uniformly oriented, more preferably fixed in a substantially uniformly oriented state, and most preferably the liquid crystalline compound is fixed by a polymerization reaction. . In the case of a discotic liquid crystalline compound having a polymerizable group, it is preferable to substantially align vertically. Substantially perpendicular means that the average angle (average tilt angle) between the disc surface of the discotic liquid crystal compound and the surface of the optical compensation film is in the range of 70 to 90 degrees.

  The optical compensation film is preferably formed by applying a coating liquid containing a liquid crystalline compound and the following polymerization initiator and other additives on the alignment film. As a solvent used for preparing the coating solution, an organic solvent is preferably used. Examples of organic solvents include amides (eg, N, N-dimethylformamide), sulfoxides (eg, dimethyl sulfoxide), heterocyclic compounds (eg, pyridine), hydrocarbons (eg, benzene, hexane), alkyl halides (eg, , Chloroform, dichloromethane), esters (eg, methyl acetate, butyl acetate), ketones (eg, acetone, methyl ethyl ketone), ethers (eg, tetrahydrofuran, 1,2-dimethoxyethane). Alkyl halides and ketones are preferred. Two or more organic solvents may be used in combination. The coating liquid can be applied by a known method (eg, extrusion coating method, direct gravure coating method, reverse gravure coating method, die coating method).

[Fixation of alignment state of liquid crystalline compounds]
The aligned liquid crystalline compound is preferably fixed while maintaining the alignment state. The immobilization is preferably carried out by a polymerization reaction of a polymerizable group introduced into the liquid crystal compound. The polymerization reaction includes a thermal polymerization reaction using a thermal polymerization initiator and a photopolymerization reaction using a photopolymerization initiator, and a photopolymerization reaction is more preferable. Examples of photopolymerization initiators include α-carbonyl compounds (described in US Pat. Nos. 2,367,661 and 2,367,670), acyloin ether (described in US Pat. No. 2,448,828), α-hydrocarbon substitution. Aromatic acyloin compounds (described in US Pat. No. 2,722,512), polynuclear quinone compounds (described in US Pat. Nos. 3,046,127 and 2,951,758), combinations of triarylimidazole dimers and p-aminophenyl ketone (US Acridine and phenazine compounds (described in JP-A-60-105667, US Pat. No. 4,239,850) and oxadiazole compounds (described in US Pat. No. 4,221,970). Is included.

The amount of the photopolymerization initiator used is preferably 0.01 to 20% by mass, more preferably 0.5 to 5% by mass, based on the solid content of the coating solution. Light irradiation for the polymerization of the liquid crystalline compound is preferably performed using ultraviolet rays. The irradiation energy is preferably ^{20mJ / cm 2 ~50J / cm 2} , further preferably 100 to 800 mJ / cm ^2. In order to accelerate the photopolymerization reaction, light irradiation may be performed under heating conditions. The thickness of the optical compensation film is preferably 0.1 to 10 μm, and more preferably 0.5 to 5 μm.

[Vertical alignment film]
In order to align the liquid crystalline compound vertically on the alignment film side, it is important to reduce the surface energy of the alignment film. Specifically, the surface energy of the alignment film is lowered by the functional group of the polymer, thereby bringing the liquid crystalline compound into a standing state. As the functional group for reducing the surface energy of the alignment film, a hydrocarbon group having 10 or more fluorine atoms and carbon atoms is effective. In order for a fluorine atom or a hydrocarbon group to be present on the surface of the alignment film, it is preferable to introduce a fluorine atom or a hydrocarbon group into the side chain rather than the main chain of the polymer. The fluoropolymer preferably contains fluorine atoms in a proportion of 0.05 to 80% by weight, more preferably in a proportion of 0.1 to 70% by weight, and in a proportion of 0.5 to 65% by weight. More preferably, it is most preferably contained in a proportion of 1 to 60% by weight. The hydrocarbon group is an aliphatic group, an aromatic group, or a combination thereof. The aliphatic group may be cyclic, branched or linear. The aliphatic group is preferably an alkyl group (which may be a cycloalkyl group) or an alkenyl group (which may be a cycloalkenyl group). The hydrocarbon group may have a substituent that does not exhibit strong hydrophilicity, such as a halogen atom. The hydrocarbon group has preferably 10 to 100 carbon atoms, more preferably 10 to 60, and most preferably 10 to 40 carbon atoms. The main chain of the polymer preferably has a polyimide structure or a polyvinyl alcohol structure.

  Polyimide is generally synthesized by a condensation reaction of tetracarboxylic acid and diamine. A polyimide corresponding to a copolymer may be synthesized using two or more kinds of tetracarboxylic acids or two or more kinds of diamines. The fluorine atom or hydrocarbon group may be present in the repeating unit derived from tetracarboxylic acid, may be present in the repeating unit derived from diamine, or may be present in both repeating units. When introducing a hydrocarbon group into polyimide, it is particularly preferable to form a steroid structure in the main chain or side chain of the polyimide. The steroid structure present in the side chain corresponds to a hydrocarbon group having 10 or more carbon atoms, and has a function of vertically aligning the liquid crystalline compound. In this specification, the steroid structure is a cyclopentanohydrophenanthrene ring structure or a ring structure in which a part of the bond of the ring is an aliphatic ring (a range in which an aromatic ring is not formed) is a double bond. means.

  Furthermore, as a means for vertically aligning the liquid crystalline compound, a method of mixing an organic acid with a polymer of polyvinyl alcohol or polyimide can be suitably used. As the acid to be mixed, carboxylic acid, sulfonic acid and amino acid are preferably used. You may use what shows the acidity among the below-mentioned air interface aligning agent. The mixing amount is preferably 0.1% by weight to 20% by weight and more preferably 0.5% by weight to 10% by weight with respect to the polymer.

  For uniform alignment of the discotic liquid crystalline compound, the vertical alignment film is rubbed to control the alignment direction. The rubbing treatment is performed by rubbing the surface of the polymer layer several times in a certain direction with paper or cloth. On the other hand, it is preferable not to perform rubbing treatment for the alignment of the rod-like liquid crystalline compound. In any alignment film, the alignment film preferably has a polymerizable group for the purpose of improving the adhesion between the liquid crystal compound and the transparent support. The polymerizable group can be introduced by introducing a repeating unit having a polymerizable group in the side chain or as a substituent of a cyclic group. It is more preferable to use an alignment film that forms a chemical bond with the liquid crystal compound at the interface. Such an alignment film is described in JP-A-9-152509. The thickness of the alignment film is preferably 0.01 to 5 μm, and more preferably 0.05 to 1 μm. In addition, after aligning a liquid crystalline compound using an alignment film, the liquid crystalline compound is fixed in the alignment state to form a retardation layer, and only the retardation layer is formed on the polymer film (or transparent support). You may transcribe.

[Air interface alignment agent]
Since ordinary liquid crystalline compounds have the property of being tilted and aligned on the air interface side, it is necessary to control the alignment of the liquid crystal compound vertically also on the air interface side in order to obtain a uniformly vertically aligned state. . For this purpose, a compound that is unevenly distributed on the air interface side and has an action of vertically aligning the liquid crystalline compound by the excluded volume effect or the electrostatic effect is added to the liquid crystal coating liquid. The action of vertically aligning the liquid crystal compound corresponds to the action of reducing the tilt angle of the director, that is, the angle formed between the director and the coated liquid crystal air side surface in the discotic liquid crystal compound. Compounds that reduce the angle of inclination of the director of the discotic liquid crystalline molecule include those in which a plurality of F atoms are bonded in order to be unevenly distributed on the air interface side, and those in which a sulfonyl group or a carboxyl group is bonded. In addition, a compound in which a rigid structural unit that gives an excluded volume effect such that the liquid crystal molecules are aligned perpendicularly is bonded preferably.

  In addition to the exemplified compounds, compounds described in JP-A Nos. 2002-20363 and 2002-129162 can be used as the air interface alignment agent. Also, paragraph numbers 0072 to 0075 of Japanese Patent Application No. 2002-212100, paragraph numbers 0038 to 0040 and 0048 to 0049 of Japanese Patent Application No. 2002-243600, and paragraph numbers 0037 to 0039 of Japanese Patent Application No. 2002-262239. The matters described in Paragraph Nos. 0071 to 0078 of Japanese Patent Application No. 2003-91752 can also be appropriately applied to the present invention.

  The amount of the air interface alignment agent used in the liquid crystal coating solution is preferably 0.05% by weight to 5% by weight. Moreover, when using a fluorine saturation type | system | group air interface aligning agent, it is preferable that it is 1 weight% or less.

The in-plane retardation (Re) of the entire optical compensation film is preferably 20 to 200 nm. The thickness direction retardation (Rth) of the entire optical compensation film is preferably 50 to 500 nm. The in-plane retardation (Re) and the thickness direction retardation (Rth) of the optical compensation film are defined by the following equations, respectively. Where d _2a is the thickness (μm) of the optical compensation film.
Re = (nx−ny) × d _2a
Rth = ((nx + ny) / 2−nz) × d _2a
(Where d _2a (nm) is the thickness of the entire optical compensation film, nx and ny (where ny <nx) is the in-plane main average refractive index, and nx is the main average refractive index in the thickness direction) And nx, ny and nz are orthogonal to each other.)

  Examples of the optical compensation film other than the discotic compound include an optical compensation film made of a stretched birefringent polymer film, and an optical compensation film having an optical compensation film formed from a low-molecular or high-molecular liquid crystalline compound on a transparent support. However, any of them can be used in the present invention. In addition, an optical compensation film having a laminated structure can be used, including the case of a laminate of two optical compensation films. Regarding the optical compensation film having a laminated structure, in consideration of the thickness, an optical compensation film made of a coating-type laminate is preferable to an optical compensation film made of a laminate of stretched polymer films.

  The polymer film used as the optical compensation film may be a stretched polymer film or a combination of a coating type polymer layer and a polymer film. As a material for the polymer film, a synthetic polymer (eg, polycarbonate, polysulfone, polyethersulfone, polyacrylate, polymethacrylate, norbornene resin, triacetylcellulose) is generally used. These polymer films are preferably manufactured in the same direction (roll-to-roll) in the longitudinal direction of the film at the time of manufacture in order to improve productivity and shape stability when temperature and humidity change.

  Since the liquid crystalline compound has various alignment forms, the optical compensation film made of the liquid crystalline compound exhibits a desired optical property by a single layer or a laminate of a plurality of layers. That is, the optical compensation film may be an embodiment comprising a support and one or more optical compensation films formed on the support. The retardation of the optical compensation film as a whole can be adjusted by the optical anisotropy of the optical compensation film. Liquid crystal compounds can be classified into rod-like liquid crystal compounds and discotic liquid crystal compounds based on their shapes. Furthermore, there are low molecular weight and high molecular weight types, respectively, and both can be used. The optical compensation film comprising the liquid crystalline compound used in the present invention preferably uses a rod-like liquid crystal compound or a discotic liquid crystalline compound as the liquid crystalline compound, and more preferably uses a discotic liquid crystalline compound having a polymerizable group. .

The liquid crystal display device of the present invention is an aspect in which the liquid crystal material is aligned substantially parallel during black display, and displays black by aligning liquid crystal molecules in parallel with the substrate surface in the absence of applied voltage. In these embodiments, by using the above-described cellulose acylate film as a protective film, it contributes to improvement in color tone, expansion of viewing angle, and improvement in contrast. In this aspect, among the protective films for the polarizing plates above and below the liquid crystal cell, the cellulose acylate that can be used in the present invention for the protective film (the protective film on the cell side) disposed between the liquid crystal cell and the polarizing plate. A polarizing plate using a rate film is preferably used on at least one side.
In the IPS liquid crystal display device shown in the schematic cross-sectional views of FIGS. 4 and 6, when one protective film of the present invention is used, the protective film is preferably disposed between the light source side polarizing film and the liquid crystal layer. . Moreover, when using two sheets, it is good to arrange | position one layer each on the upper and lower sides between a liquid-crystal layer and a polarizing film. At this time, the alignment control direction of the liquid crystal layer, for example, the rubbing direction is the vertical direction of the display device, the 12 o'clock to 6 o'clock direction, and the slow axis of the protective film disposed between the lower polarizing film and the liquid crystal layer is It is preferably parallel to the alignment direction of the liquid crystal layer. These are effective in reducing leakage light during black display and eliminating coloring in the viewing angle direction.
Similarly, in the FFS mode liquid crystal display device shown in FIG. 5 and FIG. 7, the alignment control direction of the liquid crystal layer is different from the IPS mode in the left-right direction and 3 o'clock to 9 o'clock direction of the display device. When using one sheet, it is preferable to dispose between the upper polarizing film and the liquid crystal layer.
More preferably, an optically anisotropic layer is disposed between the protective film of the polarizing plate and the liquid crystal cell, and the retardation value of the disposed optically anisotropic layer is twice the value of Δn · d of the liquid crystal layer. It is preferable to set as follows. In the IPS system, as shown in FIG. 8, the optically anisotropic layer 20 is disposed between the protective film 18 of the upper polarizing film 1 and the liquid crystal layer 5, and one protective film 19 of the present invention, the polarizing film on the light source side, is provided. 12 is preferably disposed between the liquid crystal layer 8 and the liquid crystal layer 8. Regarding the retardation of the protective film of the upper polarizing film, it is effective to reduce leakage light at the time of black display or to eliminate coloring in the viewing angle direction, particularly when Rth is 20 nm or more larger than the retardation of the protective film of the present invention. On the other hand, in the FFS system, as shown in FIG. 9, the optically anisotropic layer 20 is disposed between the protective film 19 of the lower polarizing film 12 and the liquid crystal layer 8, and one protective film 19 of the present invention is formed on the upper polarizing film. Arranging between the film 1 and the liquid crystal layer 5 is preferable because it can reduce leakage light during black display and eliminate coloring in the viewing angle direction.

In the IPS liquid crystal display device, a wide viewing angle is obtained by applying an electric field that changes the alignment state of the liquid crystal in parallel to the substrate surface. An electrode for this purpose is called a comb electrode, and a linear electrode is arranged. In order to obtain a wider viewing angle, the comb electrodes are often zigzag shaped. However, at this time, the orientation of the liquid crystal layer is disturbed at the bent portion of the electrode, and the contrast of the display device may be lowered.
Therefore, the slow axis of the cellulose acylate film intersects with the average alignment control direction of the liquid crystal layer within 10 ° to compensate for the phase difference unevenness of the liquid crystal layer due to this alignment disorder and improve the display uniformity. Furthermore, luminance unevenness during black display due to disorder in the orientation of liquid crystal molecules due to rubbing treatment can also be compensated for by self-compensating for retardation unevenness by crossing the slow axis.
The average direction of the alignment disorder of these liquid crystal molecules deviates from the original alignment control direction by about 5 to 15 °. Display unevenness can be reduced by crossing the slow axis of the protective film with its average orientation axis to compensate for retardation. In addition, when the conventional protective films are crossed, the Re value of the protective film is too large, so that unevenness can be reduced, but the absolute value of black luminance increases and contrast decreases.
Further, unevenness can be similarly reduced by intersecting the slow axis, the alignment control direction, and the average alignment direction of the optically anisotropic layer with the average alignment control direction of the liquid crystal layer within 10 °.
Also, in order to make the IPS type more responsive, a linear electrode has been proposed in which the electrode is changed to a conventional comb electrode and has a two-layer structure through an insulating layer, for example, a planar electrode and an insulating film. ing. In this case, the viewing angle is narrower than that of the conventional IPS type, and since a high electric field is applied at the end of the electrode, the liquid crystal alignment is greatly disturbed. And the effect of reducing unevenness by intersecting with each other within 10 ° becomes larger.

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

<Production of IPS mode liquid crystal cell>
On one glass substrate, electrodes were arranged so that the distance between adjacent electrodes was 20 μm, and a polyimide film was provided as an alignment film thereon, and a rubbing treatment was performed. A polyimide film was provided on one surface of a separately prepared glass substrate, and a rubbing treatment was performed to obtain an alignment film. The two glass substrates are stacked and bonded so that the alignment films face each other, the distance between the substrates (gap; d) is 3.9 μm, and the rubbing directions of the two glass substrates are parallel. A nematic liquid crystal composition having a refractive index anisotropy (Δn) of 0.0769 and a dielectric anisotropy (Δε) of 4.5 was enclosed. The value of d · Δn of the liquid crystal layer was 300 nm.

<Preparation of low retardation protective film R1>
(Preparation of cellulose acetate solution)
The following composition was put into a mixing tank and stirred to dissolve each component to prepare a cellulose acetate solution D.

Cellulose acetate solution D composition Cellulose acetate having an acetylation degree of 2.86 100.0 parts by mass Methylene chloride (first solvent) 402.0 parts by mass Methanol (second solvent) 60.0 parts by mass

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

Matting agent solution composition Silica particle dispersion with an average particle size of 16 nm 10.0 parts by weight Methylene chloride (first solvent) 76.3 parts by weight Methanol (second solvent) 3.4 parts by weight Cellulose acetate solution D 10.3 parts by weight

(Preparation of additive solution)
The following composition was put into a mixing tank and stirred while heating to dissolve each component to prepare a cellulose acetate solution. As the compound (optical anisotropy reducing agent) for reducing optical anisotropy and the wavelength dispersion adjusting agent, those shown in Table 1 below were used.

Additive solution composition Compound that lowers optical anisotropy 49.3 parts by weight Wavelength dispersion adjusting agent 7.6 parts by weight Methylene chloride (first solvent) 58.4 parts by weight Methanol (second solvent) 8.7 parts by weight Cellulose Acetate solution D 12.8 parts by mass

(Production of cellulose acetate film sample 115)
94.6 parts by mass of the cellulose acetate solution D, 1.3 parts by mass of the matting agent solution, and 4.1 parts by mass of the additive solution were mixed after filtration, and cast using a band casting machine. The mass ratio of the compound for reducing optical anisotropy and the wavelength dispersion adjusting agent to cellulose acetate in the above composition was 12% and 1.8%, respectively. The film was peeled from the band with a residual solvent amount of 30% and dried at 140 ° C. for 40 minutes to produce a cellulose acetate film. The obtained cellulose acetate film had a residual solvent amount of 0.2% and a film thickness of 40 μm.

(Production of cellulose acetate film samples 008 to 011 and 116 to 128)
Cellulose acetate film samples 008 to 011 and 116 to 128 were produced in the same manner except that the types and amounts of the compound that reduces the optical anisotropy in the additive solution and the wavelength dispersion adjusting agent were changed to those shown in Table 1. In Table 1, the solution composition for preparing Sample 115 was also entered. When the difference ΔRth (= Rth _{(10% RH)} −Rth _{(80% RH)} ) of retardation in the film thickness direction between 10% relative humidity and 80% relative humidity of these samples was measured, the optical anisotropy was reduced. In Comparative Samples 008 and 009 to which the compound to be added is not added and Comparative Samples 010 and 011 to which the plasticizer biphenyldiphenyl phosphate (BDP) is added instead of the compound that reduces the optical anisotropy, ΔRth does not become 30 nm or less and The humidity dependence of anisotropy was large. On the other hand, in samples 115 to 128 containing the compound for reducing the optical anisotropy of the present invention, ΔRth is in the range of 0 to 30 nm, and it was confirmed that the humidity dependency was reduced. Further, when the equilibrium moisture content at 25 ° C. and 80% RH of these samples was measured, all of them were 4% or less except for the comparative sample 008, and the addition of the compound or the wavelength dispersion adjusting agent for reducing the optical anisotropy of the present invention. This confirmed that the cellulose acylate film was hydrophobized. Further 60 ° C. of the samples, 95% RH, was measured moisture permeability (80 [mu] m equivalent) of 24 hr or, both the non-comparative sample 008 is ^{400g / m 2 · 24hr~2000g / m} 2 · 24hr, also compare It was confirmed that the moisture permeability of samples 115 to 128 to which a compound for reducing optical anisotropy or a wavelength dispersion adjusting agent was added as compared with samples 009 and 010 was improved. In addition, the samples other than the comparative sample 011 had no film turbidity, and a sufficiently transparent film could be prepared. In this case, the film was clouded and the compound was precipitated (crying out), and could not be evaluated as a transparent cellulose acylate film.
Further, in Samples 126 and 127, when the mass change was measured after being left for 48 hours at 80 ° C. and 90% RH, Sample 126 was −0.12% and Sample 127 was −0.02%. It was. As a wavelength dispersion adjusting agent, UV-21, UV-22, and UV-23, which are benzotriazole compounds, were used, but the sample 127 containing no UV-23 (molecular weight 315.5) having a molecular weight of 320 or less was used. It was confirmed that the sample 126 is more advantageous than the sample 126 in terms of retention. In addition, Table 2 shows optical property values of the obtained film.

<Preparation of optically anisotropic film R1>
By stretching the polycarbonate film, an optically anisotropic film having a thickness of 60 μm, an in-plane retardation Re of 210 nm, and Nz = 0.48 was obtained.

<Protective film H2>
A commercially available cellulose acetate film (Fujitac TD80UF, manufactured by Fuji Photo Film Co., Ltd.) was used as the protective film H2. The film had Re ₍₆₃₀₎ of 1, Rth ₍₆₃₀₎ of 38, | Re ₍₄₀₀₎ -Re ₍₇₀₀₎ | was 0.8, and | Rth ₍₄₀₀₎ -Rth ₍₇₀₀₎ | was 20.
<Polarizing film>
A polarizing film in which iodine was adsorbed on a stretched polyvinyl alcohol film was produced and adopted.

[Example 1]
(Polarizer)
The upper polarizing plate was bonded to both sides of the polarizing film using an acrylic adhesive so that the slow axis of the protective film H2 and the absorption axis of the polarizing film were in parallel.
Further, the lower polarizing plate was formed by laminating a protective film H2 on the light source side of the polarizing film using an acrylic adhesive and a protective film H1-116 (Re = 0.5 nm, Rth = 0.2 nm) on the liquid crystal cell side. The protective film H2 and the polarizing film absorption axis were laminated within an intersection angle of ± 2 °, and the protective film H1 and the polarizing film absorption axis were laminated at an intersection angle of 90 ± 5 °.

(Liquid crystal display device)
Optical anisotropic film R1 was laminated | stacked with the adhesive so that it might become the visual recognition side surface of an IPS mode liquid crystal cell. On the other hand, a polarizing plate was laminated with an adhesive on the opposite surface of the liquid crystal cell to produce a liquid crystal display device. The polarizing plate on the viewing side was laminated so that the extraordinary refractive index direction of the liquid crystal composition in the liquid crystal cell and the absorption axis of the polarizing plate were orthogonal when no voltage was applied. The absorption axis of the polarizing plate and the absorption axis of the optically anisotropic film R1 were arranged so as to be orthogonal.

(Evaluation)
In this liquid crystal display device, the contrast ratio in the direction at an inclination of 70 ° from the normal direction was measured at 45 ° in the azimuth direction with respect to the optical axis of the orthogonal polarizing plate, and the contrast ratio was 35. Further, when the black display in-plane unevenness of this liquid crystal display device was visually confirmed, almost no unevenness due to variations in the retardation of the protective film such as a linear shape was observed. In addition, almost no deterioration in polarization performance was observed.
In the optical characteristics of Table 2, the values of the leaked light in the oblique 45 ° direction of black display of the IPS panel and the leaked light in the oblique 45 ° direction of black display when the slow axis is crossed by 5 ° are shown. The leakage light, which was 0.61% in the comparative example of the conventional specification, was improved to 0.01% when the protective film of H1-116 was used. This is because the Re and Rth values of the protective film are small. Furthermore, it was improved to 0.0095% by crossing the slow axis by 5 °. This is because light leakage due to uneven alignment of the liquid crystal panel was compensated.

[Example 2]
(Polarizer)
The upper polarizing plate was bonded to both sides of the polarizing film using an acrylic adhesive so that the slow axis of the protective film H2 and the absorption axis of the polarizing film were in a parallel state.
Further, the lower polarizing plate was formed by laminating protective films H1-116 (Re = 0.5 nm, Rth = 0.2 nm) on both sides of the polarizing film using an acrylic adhesive. The protective film H1-116 and the polarizing film absorption axis were laminated at an intersection angle of 90 ± 5 °.

(Liquid crystal display device)
The anisotropic film R1 was laminated with a pressure-sensitive adhesive so as to be on the viewing side of the IPS mode liquid crystal cell. On the other hand, a polarizing plate was laminated with an adhesive on the opposite surface of the liquid crystal cell to produce a liquid crystal display device. The polarizing plate on the viewing side was laminated so that the extraordinary refractive index direction of the liquid crystal composition in the liquid crystal cell and the absorption axis of the polarizing plate were orthogonal when no voltage was applied. Further, the absorption axis of the polarizing plate and the absorption axis of the optical film were arranged to be orthogonal to each other.

(Evaluation)
The same viewing angle in the oblique direction as in Example 1 was obtained. Furthermore, when this liquid crystal display device was put in under conditions of 60 ° C. and 95% RH for 200 hours, when in-plane unevenness of black display was visually confirmed, most of the unevenness estimated to be caused by the protective film and liquid crystal panel was observed. Was not. In addition, almost no deterioration in polarization performance was observed.

[Example 3]
(Polarizer)
The protective film on the liquid crystal cell side of the upper polarizing plate of Example 1 was designated as protective film H1-116, and the rest of the configuration was the same.

(Evaluation)
The same viewing angle in the oblique direction as in Example 1 was obtained. Furthermore, after this liquid crystal display device was charged for 200 hours under the conditions of 60 ° C. and 95% RH, the warpage of the liquid crystal display device, particularly the liquid crystal panel (polarizing plate and glass substrate) was reduced by 10% compared to the prior art.

[Example 4]
(Polarizer)
The protective film on the light source side of the upper polarizing plate in Example 2 was designated as protective film H1-116, and the rest of the configuration was the same.

(Evaluation)
The same viewing angle in the oblique direction as in Example 1 was obtained. Furthermore, after this liquid crystal display device was charged for 200 hours under the conditions of 60 ° C. and 95% RH, the warpage of the liquid crystal display device, particularly the liquid crystal panel (polarizing plate and glass substrate) was reduced by 12% compared to the prior art.

[Comparative example]
In Example 1, the lower polarizing plate was the same as the upper polarizing plate, and the other configurations were the same.

In this liquid crystal display device, when the contrast ratio in the direction of 70 ° from the normal direction was measured at an azimuth direction of 45 degrees with respect to the optical axis of the orthogonal polarizing plate, the contrast ratio = 9. In addition, after the liquid crystal display device was placed in a condition of 60 ° C. and 95% RH for 200 hours, when in-plane unevenness of the black display was visually confirmed, light leakage was observed from the four corners of the display device, and display uniformity. Decreased.
Further, linear and mottled light leakage presumed to be caused by the liquid crystal panel was observed, and the display uniformity was lower than in Examples 1 and 2.

  By using a cellulose acylate film having a small Re and Rth in the visible region of a wavelength of 400 to 800 nm and a small change in Re and Rth depending on the wavelength as a protective film, the wavelength dependency is small, that is, the display color and durability are low. An improved display device is obtained.

It is the schematic which shows an example of the liquid crystal display device of this invention. It is a schematic sectional drawing which shows an example of the liquid crystal display device of this invention. It is a schematic sectional drawing which shows an example of the liquid crystal display device of this invention. It is a schematic sectional drawing which shows an example of the liquid crystal display device of this invention. It is a schematic sectional drawing which shows an example of the liquid crystal display device of this invention. It is a schematic sectional drawing which shows an example of the liquid crystal display device of this invention. It is a schematic sectional drawing which shows an example of the liquid crystal display device of this invention. It is a schematic sectional drawing which shows an example of the liquid crystal display device of this invention. It is a schematic sectional drawing which shows an example of the liquid crystal display device of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Upper polarizing plate polarizing film 2 Upper polarizing plate polarizing film absorption axis 3 Upper polarizing plate liquid crystal cell side protective film 4 Upper polarizing plate liquid crystal cell side protective film Slow axis 5 Liquid crystal cell upper substrate 6 Upper substrate Liquid crystal alignment rubbing direction 7 Liquid crystal Molecule (liquid crystal layer)
8 Lower substrate Liquid crystal alignment rubbing direction 9 Liquid crystal cell lower substrate 10 Lower polarizing plate Liquid crystal cell side protective film 11 Lower polarizing plate Liquid crystal cell side protective film Slow axis 12 Lower polarizing plate Polarizing film 13 Lower polarizing plate Absorption axis of polarizing film 14 Linear electrode 15 Insulating layer 16 Electrode 17 Electric field direction 18 Protective film I
19 Protective film II
20 Optically anisotropic layer

Claims (11)

A pair of substrates disposed opposite each other having at least one electrode, a liquid crystal layer provided between the substrates and controlled in orientation, and a pair of polarizing plates disposed with the liquid crystal layer interposed therebetween,
An electric field having a component parallel to the substrate having the electrode is formed by the electrode,
The polarizing plate has a polarizing film and a protective film provided on at least one surface of the polarizing film,
A cellulose acylate in which the slow axis of the protective film intersects at least one of the absorption axis of the polarizing film or the average orientation control direction of the liquid crystal layer, and the protective film satisfies the following formulas (I) and (II): A liquid crystal display device which is a rate film.
(I) 0 ≦ Re ₍₆₃₀₎ ≦ 10 and | Rth ₍₆₃₀₎ | ≦ 25
(II) | Re ₍₄₀₀₎ −Re ₍₇₀₀₎ | ≦ 10 and | Rth ₍₄₀₀₎ −Rth ₍₇₀₀₎ | ≦ 35
(In the above formulas (I) and (II), Re ₍ λ ₎ represents the front retardation value (nm) at the wavelength λnm, and Rth ₍ λ ₎ represents the retardation value in the film thickness direction at the wavelength λnm (nm). Represents.) A pair of substrates disposed opposite each other having at least one electrode, a liquid crystal layer provided between the substrates and controlled in orientation, and a pair of polarizing plates disposed with the liquid crystal layer interposed therebetween,
An electric field having a component parallel to the substrate having the electrode is formed by the electrode,
The polarizing plate has a polarizing film and a protective film provided on at least one surface of the polarizing film,
The slow axis of the protective film intersects at least one of the absorption axis of the polarizing film or the average orientation control direction of the liquid crystal layer, and the protective film has an Rth in the thickness direction of the protective film represented by the following formula: A liquid crystal display device, which is a cellulose acylate film containing a compound that reduces Rth so as to satisfy (III) and (IV).
(III) (Rth _(A) −Rth ₍₀₎ ) / A ≦ −1.0
(IV) 0.01 ≦ A ≦ 30
(In the formulas (III) and (IV), Rth _(A) represents Rth (nm) of a protective film containing a compound that reduces Rth, and Rth ₍₀₎ is the protective film, and Rth is Rth (nm) of a film not containing a compound for reducing is represented, and A represents the weight (%) of a compound for reducing Rht relative to the weight of the film raw material polymer.   The liquid crystal display device according to claim 1, wherein at least one optically anisotropic layer is disposed between the polarizing plate and the liquid crystal layer.   The liquid crystal display device according to claim 3, wherein the optically anisotropic layer is made of a rod-like liquid crystalline compound. The liquid crystal display device according to claim 1, wherein an angle of intersection between the slow axis of the protective film and the absorption axis of the polarizing film is −10 ° to + 10 ° or 80 ° to + 100 °.   The liquid crystal display device according to claim 5, wherein a light source is provided on a side opposite to the liquid crystal layer of the pair of polarizing plates, and the protective film is provided on a side close to the light source.   The liquid crystal display device according to claim 1, wherein one protective film is disposed between any one of the polarizing films and a liquid crystal layer closest to the polarizing film.   One protective film is disposed between one polarizing film and the liquid crystal layer closest to the polarizing film, and between the other polarizing film and the liquid crystal layer closest to the polarizing film. The liquid crystal display device according to claim 1.   The liquid crystal display device according to claim 1, wherein the parallel electric field is generated by a pixel electrode and a counter electrode arranged in different layers.   10. The liquid crystal display device according to claim 1, wherein the parallel electric field is generated by a pair of electrodes that are arranged in different layers and at least one of which is transparent, and an electrode to which no voltage is applied.   The liquid crystal display device according to claim 1, wherein the protective film has a thickness of 10 to 60 μm.

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