JP5010883B2 - Liquid crystal display - Google Patents

Description

  The present invention relates to a polarizing plate that reduces a color shift of black display when a viewing angle is changed in a liquid crystal display device, and a liquid crystal display device using the polarizing plate.

Liquid crystal display devices are widely used in monitors for personal computers and portable devices, and for television applications because of their various advantages, such as low voltage and low power consumption, enabling miniaturization and thinning. Various modes have been proposed for such a liquid crystal display device depending on the alignment state of the liquid crystal molecules in the liquid crystal cell. Conventionally, the liquid crystal display device is in an alignment state twisted by about 90 ° from the lower substrate to the upper substrate of the liquid crystal cell. The TN mode was mainstream.
In general, a liquid crystal display device includes a liquid crystal cell, an optical compensation sheet, and a polarizer. The optical compensation sheet is used for eliminating image coloring or expanding the viewing angle, and a stretched birefringent film or a film obtained by applying a liquid crystal to a transparent film is used. For example, Patent Document 1 discloses a technique for applying an optical compensation sheet in which a discotic liquid crystal is applied on a triacetyl cellulose film, aligned, and fixed to a TN mode liquid crystal cell to widen the viewing angle. However, a television-use liquid crystal display device that is expected to be viewed from various angles on a large screen has a strict requirement for viewing angle dependency, and even with the above-described method, the requirement cannot be satisfied. Therefore, liquid crystal display devices different from the TN mode, such as an IPS (In-Plane Switching) mode, an OCB (Optically Compensatory Bend) mode, and a VA (Vertically Aligned) mode, have been studied. In particular, the VA mode is attracting attention as a liquid crystal display device for TV because of its high contrast and relatively high manufacturing yield.

By the way, the cellulose acylate film is characterized by high optical isotropy (low retardation value) as compared with other polymer films. Therefore, it is common to use a cellulose acylate film for an application requiring optical isotropy, for example, a polarizing plate.
On the other hand, the optical compensation sheet (retardation film) of the liquid crystal display device is required to have optical anisotropy (high retardation value). In particular, an optical compensation sheet for VA requires a front retardation (Re) of 30 to 200 nm and a thickness direction retardation (Rth) of 70 to 400 nm. Therefore, it is common to use a synthetic polymer film having a high retardation value such as a polycarbonate film or a polysulfone film as the optical compensation sheet. As described above, in the technical field of optical materials, when a polymer film requires optical anisotropy (high retardation value), a synthetic polymer film is used and optical isotropy (low retardation value) is used. It was a general rule to use cellulose acylate films when required.

Patent Document 2 proposes a cellulose acetate film having a high retardation value that can be used for applications requiring optical anisotropy, overcoming the conventional general principle. In this proposal, in order to achieve a high retardation value with cellulose triacetate, an aromatic compound having at least two aromatic rings, particularly a compound having a 1,3,5-triazine ring, is added and subjected to stretching treatment. Cellulose triacetate is generally a polymer material that is difficult to stretch, and it is known that it is difficult to increase the birefringence, but it is necessary to increase the birefringence by simultaneously orienting the additives in the stretching process. To achieve a high retardation value. Since this film can also serve as a protective film for the polarizing plate, there is an advantage that an inexpensive and thin liquid crystal display device can be provided.
Japanese Patent No. 2587398 JP 2001-249223 A

It is disclosed that a wide viewing angle can be obtained by using an optical compensation sheet composed only of a cellulose acetate film having a Re value range (20 nm to 70 nm) and an Rth value range (70 nm to 400 nm) described in Patent Document 2. However, it does not show a means for reducing the difference in color (color shift) between the normal direction of the liquid crystal cell during black display and the other inclined direction.
In recent years, in liquid crystal display devices, not only the viewing angle defined by the contrast ratio, but also the display color has been demanded for improvement.
An object of the present invention is to provide a polarizing plate that has a wide viewing angle and a small color shift during black display, and a liquid crystal display device that uses the polarizing plate and has a wide viewing angle and a small color shift during black display. .

Conventionally, the adjustment of the Re value and the Rth value of the polarizing plate protective film on the liquid crystal cell side has been studied to achieve both viewing angle and color shift at the time of black display. Improvement could not be achieved.
As a result of intensive studies, the present inventors surprisingly set not only the Re value and Rth value of the polarizing plate protective film on the liquid crystal cell side in the optimum range, but also the hue when the polarizers are arranged orthogonally, It has been found that a liquid crystal display device having a wide viewing angle and a small color shift of black display can be provided by setting the color temperature of the backlight of the liquid crystal display device to an optimum range. That is, the present invention is a polarizing plate and a liquid crystal display device having the following constitutions, thereby achieving the object of the present invention.

The polarizing plate of the present invention is excellent in a viewing angle expansion effect and a color shift reduction effect during black display.
Further, the liquid crystal display device of the present invention can achieve both a wide viewing angle and a reduction in color shift during black display.

  Hereinafter, the present invention will be described in more detail. In the present specification, when a numerical value represents a physical property value, a characteristic value, etc., the description “(numerical value 1) to (numerical value 2)” means “(numerical value 1) or more and (numerical value 2) or less”. . In the present specification, the description “(meth) acryloyl” means “at least one of acryloyl and methacryloyl”. The same applies to “(meth) acrylate”, “(meth) acrylic acid” and the like.

The inventors of the present invention can solve the above problems by setting the Re value and Rth value of the protective film arranged on the liquid crystal cell side, and the hue when the polarizing plates are arranged orthogonally within the following ranges. I found.
That is, according to the present invention, Re (λ) and Rth (λ) of the protective film disposed on the liquid crystal cell side satisfy the following formulas (I) and (II), and the hue of the polarizing plate a * And b * satisfy the following mathematical formulas (III) and (IV).
Formula (I): 45 nm ≦ Re (590) ≦ 65 nm
Formula (II): 150 nm ≦ Rth (590) ≦ 240 nm
Formula (III): −1.0 ≦ a * ≦ 2.0
Formula (IV): −1.0 ≦ b * ≦ 2.0
[In the formula, Re (λ) is a front retardation value (unit: nm) at a wavelength λnm, and Rth (λ) is a retardation value (unit: nm) in a film thickness direction at a wavelength λnm. ]
As a result of intensive studies, the inventors of the present invention have found the following facts and have arrived at the above invention.
(1) In Formula (I) and Formula (II), when Re (590) and Rth (590) are out of the above ranges, the viewing angle is remarkably reduced.
(2) When Re (590) <45 nm and Rth (590) <150 nm, the color when viewed obliquely from the normal direction of the liquid crystal cell in black display appears strong and reddish. When Re (590)> 65 nm and Rth (590)> 240 nm, the tint of the black display when viewed from the normal line direction of the liquid crystal cell appears strong and bluish. (3) In Formula (III), when a * <− 1.0, the hue of the polarizer increases in green, and when a *> 2.0, the redness increases. In the formula (IV), when b * <− 1.0, bluishness increases in the hue of the polarizer, and when b *> 2.0, yellowishness increases.

  The single transmittance and parallel transmittance of the polarizing plate are characteristics that affect the luminance during white display. The inventors of the present invention have further studied to realize high luminance, and preferably the single transmittance is 41% or more and the parallel transmittance is 35% or more, and the single transmittance is 42% or more and parallel. It has been found that the transmittance is more preferably 36% or more.

The orthogonal transmittance of the polarizing plate is a characteristic that affects the luminance during black display, and is preferably 0.02% or less, and 0.01% or less in order to achieve good black display and high contrast. More preferably.
The wavelength dispersion of Re (λ) and Rth (λ) of the protective film disposed on the liquid crystal cell side is a characteristic that affects the color tone when observed from a normal direction of the liquid crystal cell in black display, It has been found that it is preferable to satisfy the following formulas (V) to (VIII).
Formula (V): 1.0 ≦ Re (480) / Re (550) ≦ 1.1
Formula (VI): 0.9 ≦ Re (630) / Re (550) ≦ 1.0
Formula (VII): 1.0 ≦ Rth (480) / Rth (550) ≦ 1.1
Formula (VIII): 0.9 ≦ Rth (630) / Rth (550) ≦ 1.0
The Re value and Rth value of the protective film are the degree of substitution of the cellulose acylate used in the protective film, the type and amount of the retardation enhancer added to the cellulose acylate film, the drying temperature / time of the cellulose acylate film, and the cellulose acylate. It can adjust with the draw ratio of a film, extending | stretching temperature, and the amount of residual solvents at the time of extending | stretching. A preferred range and control method for each control factor will be described below.

First, the cellulose acylate for increasing the optical anisotropy used in the present invention will be described in detail. In the present invention, two or more different cellulose acylates may be mixed and used. When the cellulose acylate film is a protective film disposed on the liquid crystal cell side of the polarizing plate, the substitution degree of the hydroxyl group at the 2-position of the glucose unit constituting the cellulose by the acyl group is replaced with the acyl group of the hydroxyl group at the 2-position or DS-2. It is preferable that the following formulas (IX) and (X) are satisfied when the degree is DS3 and the substitution degree of the hydroxyl group at the 6-position is DS6.
Formula (IX): 2.0 ≦ DS2 + DS3 + DS6 ≦ 3.0
Formula (X): DS6 / (DS2 + DS3 + DS6) ≧ 0.315
By satisfy | filling said Formula (IX) and (X), the solubility to a solvent improves and the humidity dependence of optical anisotropy can be made small.
The smaller the sum of DS2 + DS3 + DS6, the greater the optical anisotropy, but the greater the change in humidity of the optical anisotropy, the more practically problematic. Conversely, when the sum of DS2 + DS3 + DS6 is large, the change in humidity of optical anisotropy is small, but the expression of optical anisotropy is small. Therefore, in order to make the expression of optical anisotropy and the change in humidity compatible, the sum of DS2 + DS3 + DS6 is preferably 2.2 to 2.9, and more preferably 2.4 to 2.85.
In order to suppress the humidity change without impairing the optical anisotropy, DS6 / (DS2 + DS3 + DS6) is preferably 0.315 or more, and more preferably 0.318 or more.

The specific cellulose acylate is a mixed fatty acid ester of cellulose obtained by substituting a hydroxyl group of cellulose with an acetyl group and an acyl group having 3 or more carbon atoms, and the degree of substitution of the cellulose with a hydroxyl group is as follows: It may be a cellulose acylate satisfying the formulas (XIII) and (XIV).
Formula (XII): 2.0 ≦ A + B ≦ 3.0
Formula (XIIV): 0 <B
Here, A and B in the formula represent the substitution degree of the acyl group substituted with the hydroxyl group of cellulose, A is the substitution degree of the acetyl group, and B is the substitution degree of the acyl group having 3 or more carbon atoms.
Glucose units having β-1,4 bonds constituting cellulose have free hydroxyl groups at the 2nd, 3rd and 6th positions. Cellulose acylate is a polymer obtained by esterifying some or all of these hydroxyl groups with acyl groups. The degree of acyl substitution means the proportion of cellulose esterified at each of the 2-position, 3-position and 6-position (100% esterification has a degree of substitution of 1).
In the present invention, the total substitution degree (A + B) of hydroxyl groups A and B is 2.0 to 3.0, preferably 2.2 to 2.9, as shown in the above formula (XII). And particularly preferably 2.40 to 2.85. Further, the substitution degree of B is preferably larger than 0, more preferably 0.6 or more, as shown in the above formula (XIIV).
When A + B is less than 2.0, the hydrophilicity becomes strong and it is easy to be affected by environmental humidity. Further, 28% or more of B is preferably a 6-position hydroxyl group substituent, more preferably 30% or more is a 6-position hydroxyl group substituent, more preferably 31% or more, and particularly preferably 32% or more. A substituent at the 6-position hydroxyl group is preferred.
Furthermore, the total substitution degree of A and B at the 6-position of cellulose acylate is preferably 0.75 or more, more preferably 0.80 or more, and particularly preferably 0.85 or more. With these cellulose acylate films, a solution for preparing a film having preferable solubility and filterability can be produced, and a good solution can be produced even in a non-chlorine organic solvent. Furthermore, it becomes possible to produce a solution having a low viscosity and good filterability.
The acyl group (B) having 3 or more carbon atoms may be an aliphatic group or an aromatic hydrocarbon group and is not particularly limited. The cellulose acylate having an acyl group (B) is, for example, an alkyl carbonyl ester, an alkenyl carbonyl ester, an aromatic carbonyl ester, an aromatic alkyl carbonyl ester or the like of cellulose, and each further has a substituted group. May be. These preferred acyl groups B include propionyl, butanoyl, keptanoyl, hexanoyl, octanoyl, decanoyl, dodecanoyl, tridecanoyl, tetradecanoyl, hexadecanoyl, octadecanoyl, iso- Examples include butanoyl group, t-butanoyl group, cyclohexanecarbonyl group, oleoyl group, benzoyl group, naphthylcarbonyl group, and cinnamoyl group. Among these, groups such as propionyl, butanoyl, dodecanoyl, octadecanoyl, t-butanoyl, oleoyl, benzoyl, naphthylcarbonyl, cinnamoyl and the like are preferable. Particularly preferred are a propionyl group and a butanoyl group. In the case of a propionyl group, the substitution degree B is preferably 1.3 or more.

  Specific examples of the mixed fatty acid cellulose acylate include cellulose acetate propionate and cellulose acetate butyrate.

(Method for synthesizing cellulose acylate)
The basic principle of the cellulose acylate synthesis method is described in Mita et al., Wood Chemistry pages 180-190 (Kyoritsu Shuppan, 1968). A typical synthesis method is a liquid phase acetylation method using a carboxylic acid anhydride-acetic acid-sulfuric acid catalyst.
In order to obtain the cellulose acylate, specifically, a cellulose raw material such as cotton linter or wood pulp is pretreated with an appropriate amount of acetic acid, and then esterified by introducing it into a pre-cooled carboxylated mixed solution. Synthesize the rate (total of acyl substitution at the 2nd, 3rd and 6th positions is approximately 3.00). The carboxylated mixed solution generally contains acetic acid as a solvent, carboxylic anhydride as an esterifying agent, and sulfuric acid as a catalyst. The carboxylic anhydride is usually used in a stoichiometric excess over the sum of the cellulose that reacts with it and the water present in the system. After completion of the esterification reaction, a neutralizing agent (for example, calcium, magnesium, iron, aluminum or zinc) is used for hydrolysis of excess carboxylic anhydride remaining in the system and neutralization of a part of the esterification catalyst. Of carbonate, acetate or oxide). Next, the obtained complete cellulose acylate is saponified and aged by maintaining it at 50 to 90 ° C. in the presence of a small amount of an acetylation reaction catalyst (generally, remaining sulfuric acid) to obtain the desired degree of acyl substitution and polymerization. The cellulose acylate having a degree is changed. When the desired cellulose acylate is obtained, the catalyst remaining in the system is completely neutralized with a neutralizing agent as described above, or in water or dilute sulfuric acid without neutralization. The cellulose acylate solution is added (or water or dilute sulfuric acid is added to the cellulose acylate solution), the cellulose acylate is separated, washed and stabilized, etc. Can be obtained.

In the cellulose acylate film, it is preferable that the polymer component constituting the film is substantially composed of the specific cellulose acylate. “Substantially” means that the polymer component is 55% by mass or more (preferably 70% by mass or more, more preferably 80% by mass or more) of the total amount of cellulose acylate.
The cellulose acylate is preferably used in the form of particles. 90% by mass or more of the particles to be used preferably have a particle diameter of 0.5 to 5 mm. Moreover, it is preferable that 50 mass% or more of the particle | grains to be used have a particle diameter of 1-4 mm. The cellulose acylate particles preferably have a shape as close to a sphere as possible.
The degree of polymerization of the cellulose acylate preferably used in the present invention is a viscosity average degree of polymerization, preferably 200 to 700, more preferably 250 to 550, still more preferably 250 to 400, and particularly preferably 250 to 350. . The average degree of polymerization can be measured by Uda et al.'S intrinsic viscosity method (Kazuo Uda, Hideo Saito, Journal of Textile Society, Vol. 18, No. 1, pages 105-120, 1962). Further details are described in JP-A-9-95538.

When the low molecular component is removed, the average molecular weight (polymerization degree) is increased, but the viscosity is lower than that of ordinary cellulose acylate. Therefore, the cellulose acylate from which the low molecular component is removed 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 acylates. When the amount of the sulfuric acid catalyst is in 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, the water content is preferably 2% by mass or less, more preferably 1% by mass or less, and particularly 0.7% by mass or less. In general, cellulose acylate contains water and is known to have a water content of 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.
The raw material cotton and the synthesis method of the cellulose acylate are the raw material cotton and the synthetic cotton described in detail on pages 7-12 of the Japan Society for Invention and Technology Publication No. 2001-1745 (issued on March 15, 2001, Japan Society for Invention). A synthesis method can be adopted.

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

(Additive)
Examples of the additive that can be used in the cellulose acylate solution in the present invention include a plasticizer, an ultraviolet absorber, a deterioration preventing agent, a retardation (optical anisotropy) developing agent, and a retardation (optical anisotropy). Examples thereof include a reducing agent, fine particles, a peeling accelerator, and an infrared absorber. In the present invention, it is preferable to use a retardation developer. Moreover, it is preferable to use at least one of a plasticizer, an ultraviolet absorber and a peeling accelerator.
They may be solid or oily. That is, the melting point and boiling point are not particularly limited. For example, ultraviolet absorbers of 20 ° C. or lower and 20 ° C. or higher can be mixed and used, and plasticizers can also be mixed and used, for example, as described in JP-A No. 2001-151901.
As the ultraviolet absorber, any type can be selected according to the purpose, and a salicylic acid ester-based, benzophenone-based, benzotriazole-based, benzoate-based, cyanoacrylate-based, nickel complex-based absorber or the like is used. Preferred are benzophenone series, benzotriazole series, and salicylic acid ester series. Examples of benzophenone ultraviolet absorbers include 2,4-dihydroxybenzophenone, 2-hydroxy-4-acetoxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2,2′-di-hydroxy-4-methoxybenzophenone, 2, 2′-di-hydroxy-4,4′-methoxybenzophenone, 2-hydroxy-4-n-octoxybenzophenone, 2-hydroxy-4-dodecyloxybenzophenone, 2-hydroxy-4- (2-hydroxy-3- And methacryloxy) propoxybenzophenone. As a benzotriazole ultraviolet absorber, 2 (2′-hydroxy-3′-tert-butyl-5′-methylphenyl) -5-chlorobenzotriazole, 2 (2′-hydroxy-5′-tert-butylphenyl) ) Benzotriazole, 2 (2′-hydroxy-3 ′, 5′-di-tert-amylphenyl) benzotriazole, 2 (2′-hydroxy-3 ′, 5′-di-tert-butylphenyl) -5 Examples include chlorobenzotriazole, 2 (2′-hydroxy-5′-tert-octylphenyl) benzotriazole, and the like. Examples of salicylic acid esters include phenyl salicylate, p-octylphenyl salicylate, and p-tert-butylphenyl salicylate. Among these exemplified ultraviolet absorbers, in particular, 2-hydroxy-4-methoxybenzophenone, 2,2′-di-hydroxy-4,4′-methoxybenzophenone, 2 (2′-hydroxy-3′-tert-butyl- 5'-methylphenyl) -5-chlorobenzotriazole, 2 (2'-hydroxy-5'-
tert-butylphenyl) benzotriazole, 2 (2′-hydroxy-3 ′, 5′-di-tert-amylphenyl) benzotriazole, 2 (2′-hydroxy-3 ′, 5′-di-tert-butylphenyl) ) -5-chlorobenzotriazole is particularly preferred.

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

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

  0.001-5 mass% is preferable with respect to a cellulose acylate, and, as for the addition amount of a ultraviolet absorber, 0.01-1 mass% is more preferable. If the addition amount is less than 0.001% by mass, the effect of addition cannot be sufficiently exhibited. If the addition amount exceeds 5% by mass, the ultraviolet absorber may bleed out to the film surface.

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

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

The plasticizer is preferably a phosphate ester or a carboxylic acid ester. The plasticizer may be triphenyl phosphate (TPP), tricresyl phosphate (TCP), cresyl diphenyl phosphate, octyl diphenyl phosphate, biphenyl diphenyl phosphate (BDP), trioctyl phosphate, tributyl phosphate, dimethyl phthalate (DMP) ), Diethyl phthalate (DEP), dibutyl phthalate (DBP), dioctyl phthalate (DOP), diphenyl phthalate (DPP), diethyl hexyl phthalate (DEHP), triethyl O-acetylcitrate (OACTE), tributyl O-acetylcitrate ( OACTB), acetyl triethyl citrate, acetyl tributyl citrate, butyl oleate, methyl acetyl ricinoleate, dibutyl sebacate, tria Chin, tributyrin, butyl phthalyl butyl glycolate, ethyl phthalyl ethyl glycolate, methyl phthalyl ethyl glycolate, and more preferably one selected from butyl phthalyl butyl glycolate. Furthermore, the plasticizer is preferably (di) pentaerythritol esters, glycerol esters, diglycerol esters.
Examples of the peeling accelerator include ethyl esters of citric acid. Further, infrared absorbers are described in, for example, JP-A-2001-194522.

These additives may be added at any stage of the dope preparation process, or may be performed by adding an additive to the final preparation process of the dope preparation process. 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 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 and the like, but these are conventionally known techniques. The glass transition point Tg measured with a dynamic viscoelasticity measuring instrument for cellulose acylate film (Vibron: DVA-225 (ITG Measurement & Control Co., Ltd.)) is determined at 70 to 150 ° C. Furthermore, it is preferable that the elastic modulus measured with a tensile tester (Strograph-R2 (Toyo Seiki)) is 1500 to 4000 MPa. More preferably, the glass transition point Tg is 80 to 135 ° C. and the elastic modulus is 1500 to 3000 MPa. That is, the cellulose acylate film of the present invention preferably has a glass transition point Tg and an elastic modulus within the above ranges in terms of process suitability for polarizing plate processing and liquid crystal display device assembly.
Further, as the additive, those described in detail on page 16 and subsequent pages of the Invention Association Public Technical Bulletin No. 2001-1745 (issued March 15, 2001, Invention Association) can be appropriately used.

(Retardation expression agent)
In the present invention, it is preferable to use a retardation enhancer in order to greatly develop optical anisotropy and realize a preferable retardation value.
Examples of the retardation enhancer that can be used in the present invention include those composed of rod-shaped or discotic compounds.
As the rod-like or discotic compound, a compound having at least two aromatic rings can be used.
The addition amount of the retardation developer composed of a rod-shaped compound is preferably 0.1 to 30 parts by mass, and 0.5 to 20 parts by mass with respect to 100 parts by mass of the polymer component containing cellulose acylate. Is more preferable, and 3 to 10 parts by mass is particularly preferable.
The disk-shaped retardation developing agent is preferably 0.1 to 30 parts by mass, more preferably 0.5 to 20 parts by mass with respect to 100 parts by mass of the polymer component containing cellulose acylate. 3 to 10 parts by mass is particularly preferable.
Since the discotic compound is superior to the rod-shaped compound in Rth retardation expression, it is preferably used when a particularly large Rth retardation is required.
Two or more retardation developing agents may be used in combination.
The retardation developer composed of a rod-like or discotic compound preferably has maximum absorption in the wavelength region of 250 to 400 nm, and preferably has substantially no absorption in the visible region.

The discotic compound will be described. As the discotic compound, a compound having at least two aromatic rings can be used.
In the present specification, the “aromatic ring” includes an aromatic hetero ring in addition to an aromatic hydrocarbon ring.
The aromatic hydrocarbon ring is particularly preferably a 6-membered ring (that is, a benzene ring).
The aromatic heterocycle is generally an unsaturated heterocycle. The aromatic heterocycle is preferably a 5-membered ring, 6-membered ring or 7-membered ring, more preferably a 5-membered ring or 6-membered ring. Aromatic heterocycles generally have the most double bonds. As the hetero atom, a nitrogen atom, an oxygen atom and a sulfur atom are preferable, and a nitrogen atom is particularly preferable. Examples of aromatic heterocycles include furan ring, thiophene ring, pyrrole ring, oxazole ring, isoxazole ring, thiazole ring, isothiazole ring, imidazole ring, pyrazole ring, furazane ring, triazole ring, pyran ring, pyridine ring , Pyridazine ring, pyrimidine ring, pyrazine ring and 1,3,5-triazine ring.
As the aromatic ring, benzene ring, furan ring, thiophene ring, pyrrole ring, oxazole ring, thiazole ring, imidazole ring, triazole ring, pyridine ring, pyrimidine ring, pyrazine ring and 1,3,5-triazine ring are preferable, In particular, a 1,3,5-triazine ring is preferably used. Specifically, for example, a compound disclosed in JP 2001-166144 A is preferably used as the discotic compound.

The number of aromatic rings contained in the discotic compound is preferably 2 to 20, more preferably 2 to 12, still more preferably 2 to 8, and most preferably 2 to 6. preferable.
The bonding relationship between two aromatic rings can be classified into (a) when a condensed ring is formed, (b) when directly linked by a single bond, and (c) when linked via a linking group (for aromatic rings). , Spiro bonds cannot be formed). The connection relationship may be any of (a) to (c).

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

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

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

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

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

The aliphatic acyl group preferably has 1 to 10 carbon atoms. Examples of the aliphatic acyl group include an acetyl group, a propanoyl group, and a butanoyl group.
The aliphatic acyloxy group preferably has 1 to 10 carbon atoms. Examples of the aliphatic acyloxy group include an acetoxy group.
The number of carbon atoms of the alkoxy group is preferably 1 to 8. The alkoxy group may further have a substituent (eg, alkoxy group). Examples of the alkoxy group (including a substituted alkoxy group) include a methoxy group, an ethoxy group, a butoxy group, and a methoxyethoxy group.
The alkoxycarbonyl group preferably has 2 to 10 carbon atoms. Examples of the alkoxycarbonyl group include a methoxycarbonyl group and an ethoxycarbonyl group.
The number of carbon atoms of the alkoxycarbonylamino group is preferably 2 to 10. Examples of the alkoxycarbonylamino group include a methoxycarbonylamino group and an ethoxycarbonylamino group.

The alkylthio group preferably has 1 to 12 carbon atoms. Examples of the alkylthio group include a methylthio group, an ethylthio group, and an octylthio group.
The alkylsulfonyl group preferably has 1 to 8 carbon atoms. Examples of the alkylsulfonyl group include a methanesulfonyl group and an ethanesulfonyl group.
The aliphatic amide group preferably has 1 to 10 carbon atoms. Examples of the aliphatic amide group include an acetamide group.
The aliphatic sulfonamide group preferably has 1 to 8 carbon atoms. Examples of the aliphatic sulfonamido group include a methanesulfonamido group, a butanesulfonamido group and an n-octanesulfonamido group.
The number of carbon atoms of the aliphatic substituted amino group is preferably 1 to 10. Examples of the aliphatic substituted amino group include a dimethylamino group, a diethylamino group, and a 2-carboxyethylamino group.
The aliphatic substituted carbamoyl group preferably has 2 to 10 carbon atoms. Examples of the aliphatic substituted carbamoyl group include a methylcarbamoyl group and a diethylcarbamoyl group.
The aliphatic substituted sulfamoyl group preferably has 1 to 8 carbon atoms. Examples of the aliphatic substituted sulfamoyl group include a methylsulfamoyl group and a diethylsulfamoyl group.
The number of carbon atoms in the aliphatic substituted ureido group is preferably 2 to 10. Examples of the aliphatic substituted ureido group include a methylureido group.
Examples of the non-aromatic heterocyclic group include a piperidino group and a morpholino group.
The molecular weight of the retardation developer composed of a discotic compound is preferably 300 to 800.

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

As the rod-shaped compound, those having at least two aromatic rings are preferable, and as the rod-shaped compound having at least two aromatic rings, a compound represented by the following general formula (1) is preferable.
General formula (1): Ar1-L1-Ar2
In the general formula (1), Ar1 and Ar2 are each independently an aromatic group.
In the present specification, the aromatic group includes an aryl group (aromatic hydrocarbon group), a substituted aryl group, an aromatic heterocyclic group, and a substituted aromatic heterocyclic group.
An aryl group and a substituted aryl group are more preferable than an aromatic heterocyclic group and a substituted aromatic heterocyclic group. The heterocycle of the aromatic heterocyclic group is generally unsaturated. The aromatic heterocycle is preferably a 5-membered ring, 6-membered ring or 7-membered ring, more preferably a 5-membered ring or 6-membered ring. Aromatic heterocycles generally have the most double bonds. As a hetero atom, a nitrogen atom, an oxygen atom or a sulfur atom is preferable, and a nitrogen atom or a sulfur atom is more preferable.
As the aromatic ring of the aromatic group, a benzene ring, a furan ring, a thiophene ring, a pyrrole ring, an oxazole ring, a thiazole ring, an imidazole ring, a triazole ring, a pyridine ring, a pyrimidine ring and a pyrazine ring are preferable, and a benzene ring is particularly preferable. .

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

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

In the general formula (1), L1 represents an alkylene group, an alkenylene group, an alkynylene group,-
A divalent linking group selected from the group consisting of O-, -CO-, and combinations thereof.
The alkylene group may have a cyclic structure. As the cyclic alkylene group, cyclohexylene is preferable, and 1,4-cyclohexylene is particularly preferable. As the chain alkylene group, a linear alkylene group is more preferable than a branched alkylene group.
The alkylene group preferably has 1 to 20 carbon atoms, more preferably 1 to 15, more preferably 1 to 10, still more preferably 1 to 8, and most preferably 1 to 6. It is.

The alkenylene group and the alkynylene group preferably have a chain structure rather than a cyclic structure, and more preferably have a linear structure rather than a branched chain structure.
The number of carbon atoms of the alkenylene group and the alkynylene group is preferably 2 to 10, more preferably 2 to 8, further preferably 2 to 6, further preferably 2 to 4, and most preferably 2. (Vinylene or ethynylene).
The arylene group preferably has 6 to 20 carbon atoms, more preferably 6 to 16, and still more preferably 6 to 12.

In the molecular structure of the general formula (1), the angle formed by Ar1 and Ar2 across L1 is
It is preferable that it is 140 degree | times or more.
As the rod-like compound, a compound represented by the following formula (2) is more preferable.
Formula (2): Ar1-L2-X-L3-Ar2
In the general formula (2), Ar1 and Ar2 are each independently an aromatic group. The definition and examples of the aromatic group are the same as those of Ar1 and Ar2 in the general formula (1).

In the general formula (2), L 2 and L 3 are each independently a divalent linking group selected from an alkylene group, —O—, —CO— and a group consisting of a combination thereof.
The alkylene group preferably has a chain structure rather than a cyclic structure, and more preferably has a linear structure rather than a branched chain structure.
The alkylene group preferably has 1 to 10 carbon atoms, more preferably 1 to 8, more preferably 1 to 6, still more preferably 1 to 4, and 1 or 2 (methylene or Most preferred is ethylene).
L2 and L3 are particularly preferably —O—CO— or —CO—O—.

In the general formula (2), X is 1,4-cyclohexylene, vinylene or ethynylene.
Specific examples of the compound represented by the general formula (1) or (2) include compounds described in [Chemical Formula 1] to [Chemical Formula 11] of JP-A No. 2004-109657.

  Other preferred compounds are shown below.

Two or more rod-shaped compounds whose maximum absorption wavelength (λmax) is shorter than 250 nm in the ultraviolet absorption spectrum of the solution may be used in combination.
The rod-like compound can be synthesized by a method described in the literature. As literatures, Mol. Cryst. Liq. Cryst., 53, 229 (1979), 89, 93 (1982), 145, 111 (1987), 170, 43 (1989), J. Am. Chem. Soc., 113, 1349 (1991), 118, 5346 (1996), 92, 1582 (1970), J. Org Chem., 40, 420 (1975), Tetrahedron, 48, 16, 3437 (1992).

[Matting agent fine particles]
It is preferable to add fine particles as a matting agent to the cellulose acylate film of the present invention. The fine particles used in the present invention include silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide, calcium carbonate, calcium carbonate, talc, clay, calcined kaolin, calcined calcium silicate, hydrated calcium silicate, aluminum silicate, silica Mention may be made of magnesium and calcium phosphates. Fine particles containing silicon are preferable in terms of low turbidity, and silicon dioxide is particularly preferable. The silicon dioxide fine particles 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.
The amount of silicon dioxide fine particles used is preferably 0.01 to 0.3 parts by mass with respect to 100 parts by mass of the polymer component containing cellulose acylate.

These fine particles usually form secondary particles having an average particle diameter of 0.1 to 3.0 μm, and these fine particles are present as aggregates of primary particles in the film, 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 from 0.2 μm to 1.5 μm, more preferably from 0.4 μm to 1.2 μm, and most preferably from 0.6 μm to 1.1 μm. When it is larger than 1.5 μm, the haze becomes strong, and when it is smaller than 0.2 μm, the effect of preventing stain is reduced.
The primary and secondary particle diameters are determined by observing the particles in the film with a scanning electron microscope and using the diameter of a circle circumscribing the particles as the particle diameter. Also, 200 particles are observed at different locations, and the average value is taken as the average particle diameter.

  As the fine particles of silicon dioxide, for example, commercially available products such as Aerosil R972, R972V, R974, R812, 200, 200V, 300, R202, OX50, TT600 (above 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 diameter 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 stirred and mixed in advance, adding the fine particle dispersion to a small amount of cellulose acylate solution separately prepared, stirring and dissolving, and further mixing with a main cellulose acylate dope solution There is. This method is a preferred preparation method in that the dispersibility of the silicon dioxide fine particles is good and the silicon dioxide fine particles are more difficult to reaggregate. In addition, after adding a small amount of cellulose ester to the solvent and dissolving with stirring, add the fine particles to this and disperse it with a disperser to make this fine particle additive solution. There is also a way to do it. The present invention is not limited to these methods, but the concentration of silicon dioxide when the silicon dioxide fine particles are mixed and dispersed with a solvent or the like is preferably 5 to 30% by mass, more preferably 10 to 25% by mass, and 15 to 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.

Next, the organic solvent in which the cellulose acylate of the present invention is dissolved will be described.
In the present invention, any of a chlorinated solvent containing a chlorinated organic solvent as a main solvent and a non-chlorinated solvent not containing a chlorinated organic solvent can be used as the organic solvent.
(Chlorine solvent)
In preparing the cellulose acylate solution of the present invention, a chlorinated organic solvent is preferably used as the main solvent. In the present invention, the type of the chlorinated organic solvent is not particularly limited as long as the object can be achieved within a range where the cellulose acylate can be dissolved, cast and formed. These chlorinated organic solvents are preferably dichloromethane and chloroform. Particularly preferred is dichloromethane. In addition, there is no particular problem in mixing an organic solvent other than the chlorinated organic solvent. In that case, it is necessary to use at least 50 mass% of dichloromethane in the total amount of the organic solvent. Other organic solvents used in combination with the chlorinated organic solvent in the present invention will be described below. That is, as another preferable organic solvent, a solvent selected from esters, ketones, ethers, alcohols, hydrocarbons and the like having 3 to 12 carbon atoms is preferable. Esters, ketones, ethers and alcohols may have a cyclic structure. A compound having two or more functional groups of esters, ketones and ethers (that is, —O—, —CO— and —COO—) can also be used as a solvent. You may have group simultaneously. In the case of a solvent having two or more types of functional groups, the number of carbon atoms may be within the specified range of the compound having any functional group. Examples of esters having 3 to 12 carbon atoms include ethyl formate, propyl formate, pentyl formate, methyl acetate, ethyl acetate and pentyl acetate. Examples of ketones having 3 to 12 carbon atoms include acetone, methyl ethyl ketone, diethyl ketone, diisobutyl ketone, cyclopentanone, cyclohexanone and methylcyclohexanone. Examples of ethers having 3 to 12 carbon atoms include diisopropyl ether, dimethoxymethane, dimethoxyethane, 1,4-dioxane, 1,3-dioxolane, tetrahydrofuran, anisole and phenetole. Examples of the organic solvent having two or more kinds of functional groups include 2-ethoxyethyl acetate, 2-methoxyethanol and 2-butoxyethanol.

The alcohol used in combination with the chlorinated organic solvent may be linear, branched or cyclic, and is preferably a saturated aliphatic hydrocarbon alcohol. . The hydroxyl group of the alcohol may be any of primary to tertiary. Examples of the alcohol include methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, t-butanol, 1-pentanol, 2-methyl-2-butanol and cyclohexanol. As the alcohol, fluorine-based alcohol is also used. Examples thereof include 2-fluoroethanol, 2,2,2-trifluoroethanol, 2,2,3,3-tetrafluoro-1-propanol and the like. Furthermore, the hydrocarbon having a hydroxyl group may be linear, branched or cyclic. In addition, both aromatic hydrocarbons and aliphatic hydrocarbons can be used. The aliphatic hydrocarbon may be saturated or unsaturated. Examples of hydrocarbons include cyclohexane, hexane, benzene, toluene and xylene.
Examples of combinations of chlorinated organic solvents and other organic solvents include the following compositions, but are not limited thereto.

Dichloromethane / methanol / ethanol / butanol (80/10/5/5, parts by mass),
Dichloromethane / acetone / methanol / propanol (80/10/5/5, parts by mass),
Dichloromethane / methanol / butanol / cyclohexane (80/10/5/5, parts by mass),
Dichloromethane / methyl ethyl ketone / methanol / butanol (80/10/5/5, parts by mass),
Dichloromethane / acetone / methyl ethyl ketone / ethanol / isopropanol (75/8/5/5/7, parts by mass),
・ Dichloromethane / cyclopentanone / methanol / isopropanol (80/7/5 /
8, mass parts),
Dichloromethane / methyl acetate / butanol (80/10/10, parts by mass),
Dichloromethane / cyclohexanone / methanol / hexane (70/20/5/5, parts by mass)
Dichloromethane / methyl ethyl ketone / acetone / methanol / ethanol (50/20/20/5/5, parts by mass),
Dichloromethane / 1, 3 dioxolane / methanol / ethanol (70/20/5/5, parts by mass),
Dichloromethane / dioxane / acetone / methanol / ethanol (60/20/10/5/5, parts by mass),
Dichloromethane / acetone / cyclopentanone / ethanol / isobutanol / cyclohexane (65/10/10/5/5/5, parts by mass),
Dichloromethane / methyl ethyl ketone / acetone / methanol / ethanol (70/10/10/5/5, parts by mass),
Dichloromethane / acetone / ethyl acetate / ethanol / butanol / hexane (65/10/10/5/5/5, parts by mass),
Dichloromethane / methyl acetoacetate / methanol / ethanol 65/20/10/5, parts by mass)
Dichloromethane / cyclopentanone / ethanol / butanol (65/20/10/5, parts by mass),
And so on.

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

  The non-chlorine organic solvent used in the above cellulose acylate is selected from the various viewpoints described above, and is preferably as follows. That is, the non-chlorine solvent is preferably a mixed solvent containing the non-chlorine organic solvent as a main solvent, and is a mixed solvent of three or more different solvents, wherein the first solvent is methyl acetate, ethyl acetate, At least one selected from methyl formate, ethyl formate, acetone, dioxolane, and dioxane, or a mixture thereof; the second solvent is selected from ketones having 4 to 7 carbon atoms or acetoacetate; The solvent is a mixed solvent selected from alcohols or hydrocarbons having 1 to 10 carbon atoms, more preferably alcohols having 1 to 8 carbon atoms. Note that when the first solvent is a mixed liquid of two or more kinds of solvents, the second solvent may be omitted. The first solvent is more preferably methyl acetate, acetone, methyl formate, ethyl formate, or a mixture thereof, and the second solvent is preferably methyl ethyl ketone, cyclopentanone, cyclohexanone, methyl acetyl acetate, or a mixed solvent thereof. It may be.

  The alcohol as the third solvent may be linear, branched or cyclic, and is preferably a saturated aliphatic hydrocarbon. The hydroxyl group of the alcohol may be any of primary to tertiary. Examples of the alcohol include methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, t-butanol, 1-pentanol, 2-methyl-2-butanol and cyclohexanol. As the alcohol, fluorine-based alcohol is also used. Examples thereof include 2-fluoroethanol, 2,2,2-trifluoroethanol, 2,2,3,3-tetrafluoro-1-propanol and the like. Furthermore, the hydrocarbon may be linear, branched or cyclic. Either aromatic hydrocarbons or aliphatic hydrocarbons can be used. The aliphatic hydrocarbon may be saturated or unsaturated. Examples of hydrocarbons include cyclohexane, hexane, benzene, toluene and xylene. These alcohols and hydrocarbons as the third solvent may be used alone or in combination of two or more, and are not particularly limited. As the third solvent, preferred specific compounds include alcohol, methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, and cyclohexanol, cyclohexane, hexane, Are methanol, ethanol, 1-propanol, 2-propanol, 1-butanol.

  The mixing ratio of the above three types of mixed solvents is 20 to 95% by mass for the first solvent, 2 to 60% by mass for the second solvent, and 2 to 30% by mass for the third solvent in the total amount of the mixed solvent. The first solvent is preferably 30 to 90% by mass, the second solvent is 3 to 50% by mass, and the third alcohol is preferably 3 to 25% by mass. . In particular, it is preferable that the first solvent is 30 to 90% by mass, the second solvent is 3 to 30% by mass, and the third solvent is alcohol and 3 to 15% by mass. The non-chlorine-based organic solvent used in the present invention is described in detail on pages 12-16 of the Japan Society for Invention and Innovation Technical Bulletin No. 2001-1745 (issued on March 15, 2001, Japan Society for Invention). Has been. Preferred combinations of non-chlorine organic solvents of the present invention can include the following, but are not limited thereto.

-Methyl acetate / acetone / methanol / ethanol / butanol (75/10/5/5/5, parts by mass),
-Methyl acetate / acetone / methanol / ethanol / propanol (75/10/5/5/5, parts by mass),
Methyl acetate / acetone / methanol / butanol / cyclohexane (75/10/5/5/5, parts by mass),
Methyl acetate / acetone / ethanol / butanol (81/8/7/4, parts by mass)
-Methyl acetate / acetone / ethanol / butanol (82/10/4/4, parts by mass),
-Methyl acetate / acetone / ethanol / butanol (80/10/4/6, parts by mass),
Methyl acetate / methyl ethyl ketone / methanol / butanol (80/10/5/5, parts by mass),
-Methyl acetate / acetone / methyl ethyl ketone / ethanol / isopropanol (75/8/10/5/7, parts by mass)
-Methyl acetate / cyclopentanone / methanol / isopropanol (80/7/5/8, parts by mass),
-Methyl acetate / acetone / butanol (85/10/5, parts by mass),
Methyl acetate / cyclopentanone / acetone / methanol / butanol (60/15/14/5/6, parts by mass),
-Methyl acetate / cyclohexanone / methanol / hexane (70/20/5/5, parts by mass)
Methyl acetate / methyl ethyl ketone / acetone / methanol / ethanol (50/20/20/5/5, parts by mass),
・ Methyl acetate / 1,3-dioxolane / methanol / ethanol (70/20/5/5, parts by mass),
Methyl acetate / dioxane / acetone / methanol / ethanol (60/20/10/5/5, parts by mass),
Methyl acetate / acetone / cyclopentanone / ethanol / isobutanol / cyclohexane (65/10/10/5/5/5, parts by mass),

Methyl formate / methyl ethyl ketone / acetone / methanol / ethanol (50/20/20/5/5, parts by mass),
-Methyl formate / acetone / ethyl acetate / ethanol / butanol / hexane (65/10/10/5/5/5, parts by mass)
Acetone / methyl acetoacetate / methanol / ethanol (65/20/10/5, parts by mass)
Acetone / cyclopentanone / ethanol / butanol (65/20/10/5, parts by mass)
Acetone / 1,3-dioxolane / ethanol / butanol (65/20/10/5, parts by mass)
1,3-dioxolane / cyclohexanone / methyl ethyl ketone / methanol / butanol (55/20/10/5/5/5, parts by mass)
Etc.
Further, a cellulose acylate solution prepared by the following method can also be used.
A method of preparing a cellulose acylate solution with methyl acetate / acetone / ethanol / butanol (81/8/7/4, parts by mass), adding 2 parts by weight of butanol after filtration and concentration, and methyl acetate / acetone / ethanol / Butanol (84/10/4/2, parts by mass) A method for adding a cellulose acylate solution after filtration and concentration, and adding 4 parts by mass of butanol after addition. Methyl acetate / acetone / ethanol (84/10/6, A method of adding a cellulose acylate solution at 5 parts by mass and adding 5 parts by weight of butanol after filtration and concentration. In addition to the non-chlorine organic solvent of the present invention, dichloromethane is used for the dope used in the present invention. You may make it contain 10 mass% or less of the total amount of organic solvents.

(Characteristics of cellulose acylate solution)
The cellulose acylate solution is preferably a solution in which cellulose acylate is dissolved in the organic solvent at a concentration of 10 to 30% by mass from the viewpoint of film forming casting suitability, and more preferably 13 to 27% by mass. It is particularly preferably 15 to 25% by mass. The method for carrying out the cellulose acylate at these concentrations may be carried out so as to obtain a predetermined concentration at the stage of dissolution, or it is prepared as a low-concentration solution (for example, 9 to 14% by mass) and then concentrated as described later. You may adjust to a predetermined high concentration solution by a process. Furthermore, after preparing a high concentration cellulose acylate solution in advance, a predetermined low concentration cellulose acylate solution may be obtained by adding various additives, and the cellulose acylate solution concentration of the present invention is obtained by either method. If implemented, there is no particular problem.

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

Here, the definition of the associated molecular weight, the inertial square radius and the second virial coefficient in the present invention will be described. These are measured using the static light scattering method according to the following method. Although the measurement is performed in a dilute region for the convenience of the apparatus, these measured values reflect the behavior of the dope in the high concentration region of the present invention.
First, cellulose acylate is dissolved in a solvent used for the dope to prepare 0.1 mass%, 0.2 mass%, 0.3 mass%, and 0.4 mass% solutions. In order to prevent moisture absorption, the cellulose acylate is dried at 120 ° C. for 2 hours, and is measured at 25 ° C. and 10% RH. The dissolution method is carried out according to the method employed at the time of dope dissolution (room temperature dissolution method, cooling dissolution method, high temperature dissolution method). Subsequently, these solutions and the solvent are filtered through a 0.2 μm Teflon (trade name) filter. The filtered solution is measured for static light scattering at intervals of 10 degrees from 30 degrees to 140 degrees at 25 ° C. using a light scattering measuring device (DLS-700 manufactured by Otsuka Electronics Co., Ltd.). The obtained data is analyzed by the BERRY plot method. In addition, the refractive index required for this analysis uses the value of the solvent calculated | required with the Abbe refractive system, and the refractive index gradient (dn / dc) uses the differential refractometer (Otsuka Electronics Co., Ltd. DRM-1021). It can be measured using the solvent and solution used for light scattering measurement.

(Dope preparation)
Next, preparation of a cellulose acylate solution (dope) will be described. The method for dissolving the cellulose acylate is not particularly limited, and may be room temperature, or a cooling dissolution method or a high-temperature dissolution method, or a combination thereof. Regarding these, for example, JP-A-5-163301, JP-A-61-106628, JP-A-58-127737, JP-A-9-95544, JP-A-10-95854, JP-A-10-45950, JP 2000-53784, JP 11-322946 A, JP 11-322947 A, JP 2-276830, JP 2000-273239, JP 11-71463, JP 04-259511. No. 2000-273184, JP-A No. 11-323017, JP-A No. 11-302388, etc. describe methods for preparing cellulose acylate solutions. The above-described method for dissolving cellulose acylate in an organic solvent is applicable to the present invention as long as it is within the scope of the present invention. The details of these are described in detail in detail on the non-chlorine solvent system, pages 22-25 of the Japan Institute of Invention and Technology Publication No. 2001-1745 (issued on March 15, 2001, Japan Institute of Invention). To be implemented. Further, the cellulose acylate dope solution of the present invention is usually subjected to solution concentration and filtration. Similarly, on the 25th page of the Japan Society of Invention and Innovation Technical Bulletin No. 2001-1745 (issued on March 15, 2001, Japan Society of Invention). It is described in detail. In addition, when it melt | dissolves at high temperature, it is the case where it is more than the boiling point of the organic solvent to be used, and in that case, it uses in a pressurized state.

It is preferable that the cellulose acylate solution has a viscosity and a dynamic storage elastic modulus within the ranges described below because it is easy to cast. 1 mL of the sample solution is measured with a rheometer (CLS 500) using a Steel Cone (both manufactured by TA Instruments) having a diameter of 4 cm / 2 °. Measurement conditions were measured at Oscillation Step / Temperature Ramp, varying from 40 ° C to -10 ° C at 2 ° C / min, and static non-Newtonian viscosity n * (Pa · s) at 40 ° C and storage at -5 ° C The elastic modulus G ′ (Pa) is obtained. The sample solution is preliminarily kept at the measurement start temperature until the liquid temperature becomes constant, and then the measurement is started. In the present invention, the viscosity at 40 ° C. is 1 to 400 Pa · s, the dynamic storage elastic modulus at 15 ° C. is preferably 500 Pa or more, and more preferably the viscosity at 40 ° C. is 10 to 200 Pa · s. And the dynamic storage elastic modulus in 15 degreeC is 100-1 million. Furthermore, it is preferable that the dynamic storage elastic modulus at a low temperature is large. For example, when the casting support is −5 ° C., the dynamic storage elastic modulus is preferably 10,000 to 1,000,000 Pa at −5 ° C. When the body is at −50 ° C., the dynamic storage elastic modulus at −50 ° C. is preferably 10,000 to 5 million Pa.

  In the present invention, since the above-mentioned specific cellulose acylate is used, it is characterized in that a high concentration dope is obtained, and a cellulose acylate having a high concentration and excellent stability without relying on a means of concentration. A solution is obtained. Furthermore, in order to make it easy to melt | dissolve, after making it melt | dissolve at a low density | concentration, you may concentrate using a concentration means. The concentration method is not particularly limited. For example, the low concentration solution is guided between the cylinder and the rotation locus of the outer periphery of the rotating blade rotating in the circumferential direction, and the temperature between the solution and the solution. A method of obtaining a high-concentration solution while evaporating the solvent by giving a difference (for example, JP-A-4-259511), a heated low-concentration solution is blown into the container from the nozzle, and the solution is applied from the nozzle to the inner wall of the container In which the solvent is flash evaporated and the solvent vapor is withdrawn from the container and the concentrated solution is withdrawn from the bottom of the container (eg, US Pat. No. 2,541,012, US Pat. No. 2,858,229, US Pat. No. 4,414,341, US Pat. No. 4,504,355, etc.).

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

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

  First, the prepared cellulose acylate solution (dope) is casted on a drum or band when a cellulose acylate film is produced by a solvent cast method, and the solvent is evaporated to form a film. It is preferable to adjust the concentration of the dope before casting so that the solid content is 5 to 40% by mass. The surface of the drum or band is preferably finished in a mirror state. The dope is preferably cast on a drum or band having a surface temperature of 30 ° C. or lower, and particularly preferably a metal support temperature of −10 to 20 ° C. Further, JP 2000-301555, JP 2000-301558, JP 07-032391, JP 03-193316, JP 05-086212, JP 62-037113, JP 02-276607. The methods described in JP-A Nos. 55-014201, 02-111511, and 02-208650 can be used in the present invention.

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

In the conventional single-layer liquid, it is necessary to extrude a high-concentration and high-viscosity cellulose acylate solution in order to obtain the required film thickness. In many cases, this causes a problem such as a fault or flatness. As a solution to this, by casting a plurality of cellulose acylate solutions from a casting port, a highly viscous solution can be extruded onto a metal support at the same time. Not only can it be produced, but also the use of a concentrated cellulose acylate solution can reduce the drying load and increase the film production speed.
In the case of co-casting, the inner and outer thicknesses are not particularly limited, but preferably the outer side is preferably 1 to 50% of the total film thickness, and more preferably 2 to 30%. Here, in the case of co-casting with three or more layers, the total thickness of the layer in contact with the metal support and the layer in contact with the air side is defined as the outer thickness. In the case of co-casting, a cellulose acylate film having a laminated structure can be produced by co-casting cellulose acylate solutions having different additive concentrations such as the above-mentioned plasticizer, ultraviolet absorber and matting agent. For example, a cellulose acylate film having a structure of skin layer / core layer / skin layer can be produced. For example, the matting agent can be contained in the skin layer in a large amount or only in the skin layer. The plasticizer and the ultraviolet absorber can be contained in the core layer more than the skin layer, and may be contained only in the core layer. It is also possible to change the type of plasticizer and ultraviolet absorber between the core layer and the skin layer. For example, the skin layer contains at least one of a low-volatile plasticizer and an ultraviolet absorber, and the core layer is made plastic. It is also possible to add an excellent plasticizer or an ultraviolet absorber excellent in ultraviolet absorption. Moreover, it is also a preferable aspect to contain a peeling accelerator only in the skin layer on the metal support side. It is also preferable to add more alcohol, which is a poor solvent, to the skin layer than the core layer in order to cool the metal support by the cooling drum method to gel the solution. The Tg of the skin layer and the core layer may be different, and the Tg of the core layer is preferably lower than the Tg of the skin layer. Further, the viscosity of the solution containing cellulose acylate during casting may be different between the skin layer and the core layer, and the viscosity of the skin layer is preferably smaller than the viscosity of the core layer. It may be smaller than the viscosity.

(Casting)
As a solution casting method, a method in which the prepared dope is uniformly extruded from a pressure die onto a metal support, and a method using a doctor blade in which the dope once cast on the metal support is adjusted with a blade is used. Alternatively, there is a method using a reverse roll coater that adjusts with a reverse rotating roll, but a method using a pressure die is preferable. The pressure die includes a coat hanger type and a T die type, and any of them can be preferably used. In addition to the methods listed here, it can be carried out by various methods of casting a cellulose triacetate solution known in the art, and by setting each condition in consideration of differences in the boiling point of the solvent used, etc. The same effects as described in the above publication can be obtained. The endlessly running metal support used for producing the cellulose acylate film of the present invention includes a drum whose surface is mirror-finished by chrome plating and a stainless steel belt whose surface is mirror-finished by surface polishing (referred to as a band). May be used). One or two or more pressure dies used for producing the cellulose acylate film of the present invention may be installed above the metal support. Preferably 1 or 2 groups. When two or more units are installed, the amount of dope to be cast may be divided into various ratios for each die, or the dope may be fed to the dies from each of a plurality of precision quantitative gear pumps. The temperature of the cellulose acylate solution used for casting is preferably −10 to 55 ° C., more preferably 25 to 50 ° C. In that case, all of the processes may be the same, or may be different at various points in the process. If they are different, the temperature may be a desired temperature just before casting.

(Dry)
The drying of the dope on the metal support involved in the production of the cellulose acylate film is generally performed by applying hot air from the surface side of the metal support (drum or belt), that is, the surface of the web on the metal support, A method of applying hot air from the back of the drum or belt, contacting the temperature-controlled liquid from the back of the belt or drum opposite the dope casting surface, and heating the drum or belt by heat transfer to control the surface temperature Although there is a heat transfer method, the back surface liquid heat transfer method is preferable. The surface temperature of the metal support before casting may be any number as long as it is not higher than the boiling point of the solvent used for the dope. However, in order to promote drying and to lose fluidity on the metal support, the temperature should be set to 1 to 10 ° C. lower than the boiling point of the lowest boiling solvent. Is preferred. This is not the case when the casting dope is cooled and peeled off without drying.
The Re value and Rth value of the cellulose acylate film can also be adjusted by adjusting the temperature on the metal support on which the dope film is cast, the temperature and amount of drying air applied to the dope film cast on the metal support. Can be adjusted. In particular, the Rth value is greatly affected by the drying conditions on the metal support. Increasing the temperature of the metal support, or increasing the temperature of the drying air applied to the dope film, or increasing the air volume of the drying air, that is, increasing the amount of heat applied to the dope film, lowers the Rth value. Rth is increased by reducing. In particular, the drying of the first half part immediately after casting and before peeling off greatly affects the Rth value.

(Extension process)
In the cellulose acylate film of the present invention, the retardation can be adjusted by a stretching treatment. Furthermore, there is also a method of positively stretching in the width direction. -48271, and the like. This stretches the produced film in order to increase the in-plane retardation value of the cellulose acylate film.
The film is stretched at room temperature or under heating conditions. The heating temperature is preferably an apparent glass transition temperature Tg to Tg + 20 ° C. of the film during stretching. The stretching of the film may be uniaxial stretching only in the longitudinal or lateral direction, or may be simultaneous or sequential biaxial stretching. The longitudinal stretching is performed by 0.1 to 50%. Preferably 1 to 10% stretching, particularly preferably 2 to 5% stretching. The transverse stretching is performed by 3 to 100%. The stretching is preferably 10 to 50%, particularly preferably 20 to 40%. The birefringence of the optical film is preferably such that the refractive index in the width direction is larger than the refractive index in the length direction. Accordingly, it is preferable to make the transverse stretching ratio larger than the longitudinal stretching ratio. In addition, the stretching process may be performed in the middle of the film forming process, or the raw film that has been formed and wound may be stretched. In the former case, the stretching may be performed in a state including the residual solvent amount, and the stretching can be preferably performed at a residual solvent amount of 2 to 40%.
In order to reduce variation in the in-plane slow axis in the width direction, it is preferable to provide a relaxation step after transverse stretching. In the relaxation step, it is preferable to adjust the width of the film after relaxation to a range of 100 to 70% (relaxation rate of 0 to 30%) with respect to the width of the film before relaxation. The temperature in the relaxation step is preferably the apparent glass transition temperature Tg-10 to Tg + 20 ° C. of the film. Further, the residual solvent amount in the relaxation step is preferably in the range of 2 to 20%.
Here, the apparent Tg of the film in the stretching process is that the film containing the residual solvent is enclosed in an aluminum pan, and the temperature is increased from 25 ° C. to 150 ° C. at 20 ° C./min with a differential scanning calorimeter (DSC). Tg was determined by obtaining an endothermic curve.

  The film thickness of the cellulose acylate film of the present invention obtained after drying varies depending on the purpose of use and is usually preferably in the range of 5 to 500 μm, more preferably in the range of 20 to 300 μm, particularly preferably in the range of 30 to 150 μm. . Moreover, it is preferable that it is 40-110 micrometers for VA liquid crystal display devices especially for optical use. The thickness of the film may be adjusted by adjusting the solid content concentration contained in the dope, the slit gap of the die base, the extrusion pressure from the die, the metal support speed, and the like. The width of the cellulose acylate film obtained as described above is preferably 0.5 to 3 m, more preferably 0.6 to 2.5 m, and still more preferably 0.8 to 2.2 m. The length is preferably 100 to 10000 m per roll, more preferably 500 to 7000 m, and still more preferably 1000 to 6000 m. When winding, knurling is preferably applied to at least one end, the width is preferably 3 mm to 50 mm, more preferably 5 mm to 30 mm, and the height is preferably 0.5 to 500 μm, more preferably 1 to 200 μm. This may be a single push or a double push.

(Cyclic olefin polymer)
Further, as the protective film, a cyclic olefin polymer can be used instead of cellulose acylate.
(Cyclic polyolefin resin)
In the present invention, the cyclic polyolefin resin represents a polymer resin having a cyclic polyolefin structure. In the present invention, the cyclic polyolefin resin is also referred to as a cyclic polyolefin.
Examples of the polymer resin having a cyclic olefin structure used in the present invention include (1) a norbornene polymer, (2) a monocyclic olefin polymer, (3) a cyclic conjugated diene polymer, (4) There are vinyl alicyclic hydrocarbon polymers and hydrides of (1) to (4). The polymer resin preferably used in the present invention is an addition (co) polymer cyclic polyolefin containing at least one repeating unit represented by the following general formula (II) and, if necessary, represented by the general formula (I). An addition (co) polymer cyclic polyolefin further comprising at least one or more repeating units. Further, a ring-opening (co) polymer containing at least one cyclic repeating unit represented by the general formula (III) can also be suitably used.

In formula, m represents the integer of 0-4. R ^{1 to} R ⁶ are a hydrogen atom or a hydrocarbon group having 1 to 10 carbon atoms, X ^{1 to} X ³ and Y ^{1 to} Y ³ are a hydrogen atom, a hydrocarbon group having 1 to 10 carbon atoms, a halogen atom, and a halogen atom. substituted hydrocarbon group having 1 to 10 carbon _{atoms, - (CH 2) n COOR} 11, - (CH 2) n OCOR 12, - (CH 2) n NCO, - (CH 2) n NO 2, - ( _{CH 2) n CN, - (} CH 2) n CONR 13 R 14, - (CH 2) n NR 13 R 14, - (CH 2) n OZ, - (CH 2) n W or X ¹ and Y ^1, Alternatively, (—CO) ₂ O and (—CO) ₂ NR ¹⁵ composed of X ² and Y ² or X ³ and Y ³ are shown. R ¹¹ , R ¹² , R ¹³ , R ¹⁴ , and R ¹⁵ are hydrogen atoms, hydrocarbon groups having 1 to 20 carbon atoms, Z is a hydrocarbon group or a hydrocarbon group substituted with halogen, and W is SiR ¹⁶ _p. D _3-p (R ¹⁶ is a hydrocarbon group having 1 to 10 carbon atoms, D is a halogen atom, —OCOR ¹⁶ or —OR ¹⁶ , p is an integer of 0 to 3), n is an integer of 0 to 10 Show.

By introducing a polarizable large functional group in a substituent ^{X 1 ~X 3, Y 1 ~Y} 3, by increasing the thickness-direction retardation of the optical film (Rth), in-plane retardation (Re) The expression can be increased. A film having a high Re developability can increase the Re value by stretching in the film forming process.

  As the norbornene-based addition (co) polymer, those disclosed in JP-A No. 10-7732, JP-T-2002-504184, US2004229157A1 or International Publication No. 2004 / 070463A1 may be used. it can. It can be obtained by addition polymerization of norbornene-based polycyclic unsaturated compounds. If necessary, norbornene-based polycyclic unsaturated compounds and conjugated dienes such as ethylene, propylene, butene, butadiene and isoprene; non-conjugated dienes such as ethylidene norbornene; acrylonitrile, acrylic acid, methacrylic acid, maleic anhydride It is also possible to carry out addition polymerization with linear diene compounds such as acid, acrylic acid ester, methacrylic acid ester, maleimide, vinyl acetate and vinyl chloride. As this norbornene type addition (co) polymer, a commercial item can also be used. Specifically, grades such as APL8008T (Tg70 ° C), APL6013T (Tg125 ° C), or APL6015T (Tg145 ° C), which are sold under the trade name of Apel from Mitsui Chemicals, Inc. and have different glass transition temperatures (Tg), are used. There is. Pellets such as TOPAS 8007, 6013, and 6015 are sold by Polyplastics Co., Ltd. Furthermore, Appear 3000 is marketed by Promerus.

Norbornene-based polymer hydrides are disclosed in JP-A-1-240517, JP-A-7-196736, JP-A-60-26024, JP-A-62-19807, JP-A-2003-1159767, or As disclosed in Japanese Patent Application Laid-Open No. 2004-309979 and the like, it is possible to use those produced by hydrogenation after addition polymerization or metathesis ring-opening polymerization of a polycyclic unsaturated compound. In the norbornene-based polymer used in the present invention, R ^{5 to} R ⁶ are preferably a hydrogen atom or —CH ₃ , X ³ and Y ³ are preferably a hydrogen atom, Cl, —COOCH ₃ , and other groups are appropriately selected. The This norbornene-based resin may be a commercially available product. Specifically, it is sold under the trade name Arton G or Arton F by JSR Co., Ltd., and Zeonor from Nippon Zeon Co., Ltd. ) ZF14, ZF16, Zeonex 250 or ZEONEX 280 are commercially available and can be used.

The cyclic polyolefin resin used in the present invention preferably has a mass average molecular weight (Mw) measured by gel permeation chromatography (GPC) of 5,000 to 1,000,000 in terms of polystyrene molecular weight. 10,000-500,
000 is more preferable, and 50,000 to 300,000 is even more preferable. The molecular weight distribution (Mw / Mn; Mn is the number average molecular weight measured by GPC) is preferably 10 or less, more preferably 5.0 or less, and even more preferably 3.0 or less. The glass transition temperature (Tg; measured by DSC) is preferably 50 to 350 ° C, more preferably 80 to 330 ° C, and still more preferably 100 to 300 ° C.

As an optical compensation sheet, one having two or more layers in which an optically anisotropic layer comprising a liquid crystalline or non-liquid crystal performance polymer layer is formed on a polymer film is also known. Specifically, an optical compensation sheet (Japanese Patent Laid-Open No. 2004-4474) in which a polyimide layer is formed on a cellulose acetate film and further stretched, or an optical compensation sheet (Patent No. 1) in which a cholesteric liquid crystal layer is formed on a cellulose acetate film No. 2660601 and JP-A 2003-287622). These optical compensation sheets having two or more layers are formed by coating an optically anisotropic layer on a substrate or by transferring a separately formed optically anisotropic layer through an adhesive layer. is doing.
When an optically anisotropic layer is formed on a substrate by coating, an organic solvent that appropriately dissolves the surface of the substrate is used to increase the adhesion between the optically anisotropic layer and the substrate. Used as a solvent for the solution. In such a case, since the interface between the base material and the optically anisotropic layer is not smooth and is disturbed, scattering may increase.
In addition, when the optically anisotropic layer is transferred onto the substrate via an adhesive material, scattering due to the adhesive layer or scattering due to minute cracks generated in the optically anisotropic layer to be transferred may occur.
Such scattering of the optically anisotropic layer scatters light traveling in a direction inclined from the normal direction of the liquid crystal display panel in the black display state of the liquid crystal display apparatus in the normal direction of the panel (front of the panel). Therefore, the black luminance at the front of the panel is increased. That is, the contrast ratio at the front of the panel is lowered.
When the optical compensation sheet consisting of only one layer of the present invention is used as a polarizing plate protective film, the above-mentioned scattering does not occur, so that the black luminance at the front of the panel is low and the contrast ratio at the front of the panel can be increased. Therefore, it is preferable to use an optical compensation sheet consisting of only one layer as the polarizing plate protective film.

In this specification, Re (λ) and Rth (λ) represent in-plane retardation and retardation in the thickness direction at a wavelength λ, respectively. Re (λ) is an automatic birefringence meter such as KOBRA
It is measured by using 21ADH (manufactured by Oji Scientific Instruments) with light having a wavelength of λ nm incident in the normal direction of the film. Rth (λ) is in the film normal direction with the film normal direction as the incident angle of 0 degree and the in-plane slow axis (determined by the measured value of the automatic birefringence meter, for example, KOBRA21ADH) as the tilt axis (rotation axis). On the other hand, an automatic birefringence meter, for example, based on the retardation value measured by making light of wavelength λ nm incident every 10 ° from an incident angle of −50 ° to + 50 °, the assumed value of the average refractive index, and the input film thickness value, for example, Calculated by KOBRA21ADH. 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 main optical films are exemplified below in parentheses: cellulose acylate (1.48), cycloolefin polymer (1.52), polycarbonate (1.59), polymethyl methacrylate (1. 49), polystyrene (1.59).
By inputting the assumed value of average refractive index and the film thickness, KOBRA21ADH can calculate nx, ny, nz
Is calculated. Nz = (nx-nz) / (nx-ny) is further calculated from the calculated nx, ny, and nz.
The variation in the Re (590) value of the full width is preferably ± 5 nm, and more preferably ± 3 nm. Further, the variation of the Rth (590) value is preferably ± 10 nm, and more preferably ± 5 nm. Further, it is preferable that the variation in the Re value and the Rth value in the length direction is also within the range of the variation in the width direction.

  The variation of the slow axis angle in the film plane of the protective film disposed on the liquid crystal cell side used in the present invention is preferably in the range of −2 degrees to +2 degrees with respect to the reference direction of the roll film. More preferably, it is in the range of +1 degree to +1 degree, and most preferably in the range of -0.5 degree to +0.5 degree. Here, the reference direction is the longitudinal direction of the roll film when the protective film disposed on the liquid crystal cell side is longitudinally stretched, and the width direction of the roll film when laterally stretched.

Further, the protective film disposed on the liquid crystal cell side used in the present invention has a difference ΔRe (= Re10% RH−Re80% RH) between the Re value at 25 ° C. and 10% RH and the Re value at 25 ° C. and 80% RH is 0. 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 0 to 30 nm. It is preferable in reducing the color change due to.
In addition, the protective film disposed on the liquid crystal cell side used in the present invention has an equilibrium water content of not more than 3.2% at 25 ° C. and 80% RH in order to reduce the color change with time of the liquid crystal display device. Is preferable.
The moisture content was measured by applying a protective film sample 7 mm × 35 mm disposed on the liquid crystal cell side used in the present invention to a moisture measuring device and a sample drying apparatus (CA-03, VA-05, both manufactured by Mitsubishi Chemical Corporation). And then measured by the Karl Fischer method. It is calculated by dividing the amount of water (g) by the sample mass (g).

Further, the protective film disposed on the liquid crystal cell side used in the present invention has a liquid permeability of 60 ° C., 95% RH, and a moisture permeability of 24 hours (converted to a film thickness of 80 μm) of 1800 g / m ² · 24 hours or less. This is preferable for reducing the change in color of the apparatus over time.
If the thickness of the protective film disposed on the liquid crystal cell side is thick, the moisture permeability becomes small, and if the film thickness is thin, the moisture permeability becomes large. Therefore, it is necessary to convert the sample of any film thickness to a standard of 80 μm. Conversion of the film thickness is obtained as (water vapor permeability in terms of 80 μm = measured moisture permeability × measured film thickness μm / 80 μm).
The measurement method of moisture permeability is “Polymer Physical Properties II” (Polymer Experiment Course 4, Kyoritsu Shuppan), pages 285-294: Measurement of vapor permeation amount (mass method, thermometer method, vapor pressure method, adsorption amount method) The method described in can be applied.
The glass transition temperature is measured by adjusting the thickness of a protective film sample (unstretched) 5 mm × 30 mm placed on the liquid crystal cell side used in the present invention at 25 ° C. and 60% RH for 2 hours or more, and then measuring the dynamic viscoelasticity ( Vibron: DVA-225 (manufactured by IT Measurement Control Co., Ltd.) with a grip distance of 20 mm, a heating rate of 2 ° C./min, a measuring temperature range of 30 ° C. to 200 ° C., and a frequency of 1 Hz. When the storage elastic modulus is taken along the horizontal axis and the temperature (° C.) is taken along the linear axis, the sudden decrease in the storage elastic modulus seen when the storage elastic modulus transitions from the solid region to the glass transition region is linear 1 in the solid region. When the straight line 2 is drawn in the glass transition region, the intersection of the straight line 1 and the straight line 2 is a temperature at which the storage elastic modulus suddenly decreases and the film starts to soften when the temperature rises, and begins to move to the glass transition region. Glass transition temperature T It was (dynamic viscoelasticity).

The elastic modulus was measured by conditioning a protective film sample 10 mm × 150 mm arranged on the liquid crystal cell side used in the present invention for 2 hours or more at 25 ° C. and 60% RH, and then using a tensile tester (Strograph-R2 (Toyo Seiki Manufactured)), at a distance between chucks of 100 mm, a temperature of 25 ° C., and a stretching speed of 10 mm / min.
The hygroscopic expansion coefficient is measured with a pin gauge from the value L80 obtained by measuring the dimension of a film left at 25 ° C. and 80% RH for 2 hours or longer with a pin gauge. It calculated | required by following Formula from obtained value L10.
(L10-L80) / (80% RH-10% RH) x 1000000
The protective film disposed on the liquid crystal cell side used in the present invention preferably has a haze of 0.01 to 2%. Here, the haze can be measured as follows.
The haze is measured according to JIS K-6714 using a haze meter (HGM-2DP, Suga Test Instruments) at 25 ° C. and 60% RH on a protective film sample 40 mm × 80 mm arranged on the liquid crystal cell side used in the present invention. .
Moreover, it is preferable that the protective film arrange | positioned at the side of the liquid crystal cell used for this invention is 0 to 5% of mass changes when it is left still for 48 hours on 80 degreeC and 90% RH conditions.
Further, the protective film disposed on the liquid crystal cell side used in the present invention has a dimensional change when left for 24 hours under conditions of 60 ° C. and 95% RH, and 24 hours under conditions of 90 ° C. and 5% RH. It is preferable that the dimensional change when standing is 0 to 5%.
It is preferable that the photoelastic coefficient is 50 × 10 −13 cm ² / dyn (5 × 10 −11 m ² / N) or less in order to reduce the color change with time of the liquid crystal display device.
As a specific measuring method, a tensile stress is applied to the major axis direction of a protective film sample 10 mm × 100 mm arranged on the liquid crystal cell side, and the retardation at that time is measured by an ellipsometer (M150, JASCO Corporation). The photoelastic coefficient was calculated from the amount of change in retardation with respect to stress.

(Polarizer)
Next, the polarizing plate of the present invention will be described.
The polarizing plate of the present invention uses at least one optical cellulose acylate film used in the present invention as a protective film for a polarizer. The protective film may be a cyclic polyolefin resin film, but here, the protective film will be described as an example using a cellulose acetate film.
The polarizing plate is usually composed of a polarizer and two transparent protective films disposed on both sides thereof. In the present invention, the cellulose acylate film or cyclic polyolefin film used in the present invention is used as at least one protective film. The other protective film may be a cellulose acylate film used in the present invention or a normal cellulose acetate film. The relationship between the thickness of the protective film on the liquid crystal cell side and the protective film on the side opposite to the liquid crystal cell, the elastic modulus, and the hygroscopic expansion coefficient can be adjusted to adjust the curl of the polarizing plate.

Examples of the polarizer of the polarizing film include an iodine polarizer, a dye polarizer using a dichroic dye, and a polyene polarizer. The iodine polarizer and the dye polarizer are generally produced using a polyvinyl alcohol film. When using the cellulose acylate film used for this invention as a polarizing plate protective film, the preparation methods of a polarizing plate are not specifically limited, It can manufacture by a general method. For example, there is a method in which the obtained cellulose acylate film is treated with an alkali and bonded to both sides of a polarizer produced by immersing and stretching a polyvinyl alcohol film in an iodine solution using a completely saponified polyvinyl alcohol aqueous solution. Instead of alkali treatment, easy adhesion processing as described in JP-A-6-94915 and JP-A-6-118232 may be performed. Examples of the adhesive used to bond the protective film-treated surface and the polarizer include polyvinyl alcohol adhesives such as polyvinyl alcohol and polyvinyl butyral, vinyl latexes such as butyl acrylate, and the like. The polarizing plate is composed of a polarizer and a protective film that protects both surfaces of the polarizer, and a protective film may be bonded to one surface of the polarizing plate and a separate film may be bonded to the opposite surface.
The protective film and the separate film are used for the purpose of protecting the polarizing plate at the time of shipping the polarizing plate and at the time of product inspection. In this case, the protect film is bonded for the purpose of protecting the surface of the polarizing plate, and is used on the side opposite to the surface where the polarizing plate is bonded to the liquid crystal cell. Moreover, a separate film is used in order to cover the adhesive layer bonded to a liquid crystal cell, and is used for the surface side which bonds a polarizing plate to a liquid crystal cell.
The cellulose acylate film of the present invention is bonded to the polarizer as shown in the schematic diagram of cellulose acylate film bonding in FIG. 1 and the transmission axis of the polarizer and the cellulose acylate film of the present invention (in the drawing) The TAC) is preferably bonded so that the slow axes thereof coincide with each other. As described above, the cellulose acetate protective film may be a protective film of a cyclic polyolefin resin. In this case, it is preferable to perform a surface treatment to be described later and to bond it with a polarizer.
In addition, the polarizing plate produced under polarizing plate crossed Nicol, when the orthogonal accuracy between the slow axis of the cellulose acylate film of the present invention and the absorption axis of the polarizer (axis orthogonal to the transmission axis) is greater than 1 °, Polarization degree performance under polarizing plate crossed Nicole is reduced, light leakage occurs, and when combined with a liquid crystal cell, sufficient black level and contrast cannot be obtained, so the slow axis of the cellulose acylate film of the present invention The deviation between the direction and the direction of the transmission axis of the polarizing plate is within 1 °, preferably within 0.5 °.
The hues a and b in the crossed Nicols of the polarizing plate of the present invention are −1.0 ≦ a ** ≦ 2.0 and −, respectively, in order to set the color tone in the black display state of the liquid crystal display device to an appropriate range. 1.0 ≦ b * ≦ 2.0, and more preferably −0.5 ≦ a * ≦ 1.5 and −0.5 ≦ b * ≦ 1.5.
In order to make the hue of a polarizing plate into the said range, it can achieve mainly by optimizing the preparation conditions of a polarizer.
The hues a * and b * of the polarizing plate are determined by measuring the spectral transmittance in the visible range of the polarizing plate with a spectrophotometer, and multiplying the measured spectral transmittance by a color matching function to integrate the tristimulus values X, Y, Z is obtained from the definition of the CIE 1976 L * a * b * color space. Details are described in “Basics of Color Reproduction Optics” (Corona Co., Ltd.).
Specifically, in a spectrophotometer UV-3100 (manufactured by Shimadzu Corporation), in the color measurement mode, the transmittance was measured under the following measurement conditions to calculate the polarizing plate hue.
Measurement wavelength range: 780 to 380 nm,
Scanning speed: medium speed, slit width: 2.0 nm,
Sampling pitch: 1.0 nm,
Light source: C light source, field of view: 2 °.
Here, the two polarizing plates are combined so that the cell-side protective films face each other and their transmission axes are orthogonal to each other, and the polarizing plate transmission axes are in the direction normal to the sample chamber of the spectrophotometer (the grating grooves). (Direction) was arranged to be 45 °.
The single plate transmittance, parallel transmittance, and orthogonal transmittance of the polarizing plate can be measured with a spectrophotometer in the same manner as the hue of the polarizing plate. Specifically, the transmittance is measured with a spectrophotometer UV-3100 (manufactured by Shimadzu Corporation) under the following measurement conditions.
Measurement wavelength range: 780 to 380 nm,
Scanning speed: medium speed, slit width: 2.0 nm,
Sampling pitch: 1.0 nm.
Here, it arrange | positioned so that a polarizing plate transmission axis might be 45 degrees with respect to the normal line direction (direction of a groove of a grating) of the sample chamber of a spectrophotometer.

(surface treatment)
The cellulose acylate film or the cyclic polyolefin film of the present invention is optionally subjected to surface treatment to allow adhesion between the cellulose acylate film or the cyclic polyolefin film and each functional layer (for example, an undercoat layer and a back layer). An improvement can be achieved. As the surface treatment, for example, glow discharge treatment, ultraviolet irradiation treatment, corona treatment, flame treatment, acid or alkali treatment can be used. The glow discharge treatment here may be low-temperature plasma that occurs 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 includes 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 on pages 30-32 of the Japan Society for Invention and Innovation Technical Bulletin No. 2001-1745 (issued on March 15, 2001, Japan Institute of Invention). In the plasma treatment at atmospheric pressure, which has been attracting attention in recent years, for example, irradiation energy of 20 to 500 kGy is used under 10 to 1000 keV, and more preferably irradiation energy of 20 to 300 kGy is used under 30 to 500 keV. Among these, an alkali saponification treatment is particularly preferable, and it is extremely effective as a surface treatment of a cellulose acylate film.

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

  In the polarizing plate of the present invention, it is preferable that at least one layer of a hard coat layer, an antiglare layer and an antireflection layer is provided on the surface of the protective film on the other side of the polarizing plate. That is, as shown in FIG. 2 schematically showing the cross-sectional structure of the polarizing plate of the present invention, the protective film (TAC2) disposed on the side opposite to the liquid crystal cell when the polarizing plate is used in a liquid crystal display device has an antireflection layer. It is preferable to provide a functional film such as at least one of a hard coat layer, an antiglare layer and an antireflection layer. Each layer does not need to be provided as a separate layer. For example, the antiglare layer functions as an antireflection layer and an antiglare layer by providing the antireflection layer and the hard coat layer with the function. May be provided.

(Antireflection layer)
In the present invention, the intermediate refractive index layer, the high refractive index layer, and the low refractive index layer are arranged in this order on the antireflection layer or protective film in which at least the light scattering layer and the low refractive index layer are laminated in this order on the protective film. The antireflection layer laminated with is preferably used. Preferred examples thereof are described below. In the former configuration, the specular reflectance is generally 1% or more, which is called a low reflection (LR) film. In the latter configuration, it is possible to realize a mirror reflectivity of 0.5% or less, which is called an Anti Reflection (AR) film.

A preferred example of an antireflection layer (LR film) in which a light scattering layer and a low refractive index layer are provided on a protective film will be described.
In the light scattering layer, mat particles are preferably dispersed, and the refractive index of the material other than the mat particles in the light scattering layer is preferably in the range of 1.50 to 2.00, and the low refractive index The refractive index of the layer is preferably in the range of 1.20 to 1.49. In the present invention, the light scattering layer has both antiglare properties and hard coat properties, and may be a single layer or a plurality of layers, for example, 2 to 4 layers.

  The antireflection layer has an uneven surface shape with a center line average roughness Ra of 0.08 to 0.40 μm, a 10-point average roughness Rz of 10 times or less of Ra, an average mountain valley distance Sm of 1 to 100 μm, and an uneven depth. Designed so that the standard deviation of the height of the convex part from the part is 0.5 μm or less, the standard deviation of the average mountain valley distance Sm with respect to the center line is 20 μm or less, and the surface with an inclination angle of 0 to 5 degrees is 10% or more. By doing so, sufficient anti-glare properties and a visually uniform matte feeling are achieved, which is preferable. Further, the ratio of the minimum value and the maximum value of the reflectance within the range of the a * value −2 to 2, the b * value −3 to 3, and the 380 nm to 780 nm in the color of the reflected light under the C light source is 0.5. By being -0.99, the color of reflected light becomes neutral, which is preferable. Moreover, it is preferable that the b * value of the transmitted light under the C light source is 0 to 3 because the yellow color of white display when applied to a display device is reduced. In addition, when a 120 μm × 40 μm grid is inserted between the surface light source and the antireflection film of the present invention and the luminance distribution is measured on the film, the standard deviation of the luminance distribution is 20 or less. Glare when applying the film of the present invention is reduced, which is preferable.

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

(Low refractive index layer)
The refractive index of the low refractive index layer that can be used in the present invention is preferably 1.20 to 1.49, more preferably 1.30 to 1.44. Furthermore, the low refractive index layer preferably satisfies the following formula (XVII) from the viewpoint of reducing the reflectance.
Formula (XVII): (m / 4) × 0.7 <n1d1 <(m / 4) × 1.3
In the formula, m is a positive odd number, n1 is the refractive index of the low refractive index layer, and d1 is the film thickness (nm) of the low refractive index layer. Further, λ is a wavelength, which is a value in the range of 500 to 550 nm.

The material for forming the low refractive index layer is described below.
The low refractive index layer preferably contains a fluorine-containing polymer as a low refractive index binder. The fluorine polymer is preferably a fluorine-containing polymer that is crosslinked by heat or ionizing radiation with a coefficient of dynamic friction of 0.03 to 0.20, a contact angle with water of 90 to 120 °, and a sliding angle of pure water of 70 ° or less. When the polarizing plate of the present invention is mounted on an image display device, the lower the peel strength from a commercially available adhesive tape, the easier it is to peel off after sticking a seal or memo, and 500 gf or less is preferred when measured with a tensile tester. 300 gf (2.94 N) or less is more preferable, and 100 gf (0.98 N) or less is most preferable. Further, the higher the surface hardness measured with a micro hardness tester, the harder it is to scratch, preferably 0.3 GPa or more, more preferably 0.5 GPa or more.

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

  Specific examples of the fluorine-containing monomer include fluoroolefins (for example, fluoroethylene, vinylidene fluoride, tetrafluoroethylene, perfluorooctylethylene, hexafluoropropylene, perfluoro-2,2-dimethyl-1,3-dioxole, etc. ), A part of (meth) acrylic acid or a fully fluorinated alkyl ester derivative (for example, Biscoat 6FM (manufactured by Osaka Organic Chemicals) or M-2020 (manufactured by Daikin)), a complete or partially fluorinated vinyl ether, and the like. Perfluoroolefins are preferred, and hexafluoropropylene is particularly preferred from the viewpoints of refractive index, solubility, transparency, availability, and the like.

  As structural units for imparting crosslinking reactivity, structural units obtained by polymerization of monomers having a self-crosslinkable functional group in the molecule in advance such as glycidyl (meth) acrylate and glycidyl vinyl ether, carboxyl groups, hydroxy groups, amino acids Polymerization of monomers having a group, a sulfo group, etc. (eg (meth) acrylic acid, methylol (meth) acrylate, hydroxyalkyl (meth) acrylate, allyl acrylate, hydroxyethyl vinyl ether, hydroxybutyl vinyl ether, maleic acid, crotonic acid, etc.) The resulting structural unit, a structural unit in which a crosslinking reactive group such as a (meth) acryloyl group is introduced into these structural units by a polymer reaction (for example, an acrylic acid chloride is allowed to act on a hydroxy group). And the like.

  In addition to the above-mentioned fluorine-containing monomer units and structural units for imparting crosslinking reactivity, monomers not containing fluorine atoms can be copolymerized as appropriate from the viewpoints of solubility in solvents and film transparency. There are no particular limitations on the monomer units that can be used in combination. For example, olefins (ethylene, propylene, isoprene, vinyl chloride, vinylidene chloride, etc.), acrylic esters (methyl acrylate, methyl acrylate, ethyl acrylate, acrylic acid 2) -Ethylhexyl), methacrylates (methyl methacrylate, ethyl methacrylate, butyl methacrylate, ethylene glycol dimethacrylate, etc.), styrene derivatives (styrene, divinylbenzene, vinyl toluene, α-methylstyrene, etc.), vinyl ethers (methyl) Vinyl ether, ethyl vinyl ether, cyclohexyl vinyl ether, etc.), vinyl esters (vinyl acetate, vinyl propionate, vinyl cinnamate etc.), acrylamides (N-tert-butylacrylamide, N- Black hexyl acrylamide), methacrylamides, and acrylonitrile derivatives.

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

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

  The thickness of the light scattering layer is preferably 1 to 10 μm and more preferably 1.2 to 6 μm for the purpose of imparting hard coat properties. If it is too thin, the hard property will be insufficient, and if it is too thick, curling and brittleness will deteriorate and the workability will be insufficient.

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

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

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

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

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

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

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

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

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

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

The light scattering layer is made of an oxide of at least one metal selected from titanium, zirconium, aluminum, indium, zinc, tin, and antimony, in addition to the matte particles, in order to increase the refractive index of the layer. Thus, it is preferable that an inorganic filler having an average particle diameter of 0.2 μm or less, preferably 0.1 μm or less, more preferably 0.06 μm or less is contained. Conversely, in order to increase the difference in refractive index from the mat particles, it is also preferable to use a silicon oxide in order to keep the refractive index of the light scattering layer using the high refractive index mat particles low. The preferred particle size is the same as that of the aforementioned inorganic filler.
Specific examples of the inorganic filler used for the light scattering layer include TiO ₂ , ZrO ₂ , Al ₂ O ₃ , In ₂ O ₃ , ZnO, SnO ₂ , Sb ₂ O ₃ , ITO and SiO ₂ . TiO2 and ZrO ₂ are preferred from the standpoint of elevating the refractive index. The surface of the inorganic filler is preferably subjected to a silane coupling treatment or a titanium coupling treatment, and a surface treatment agent having a functional group capable of reacting with a binder species on the filler surface is preferably used.
The amount of these inorganic fillers added is preferably 10 to 90% of the total mass of the light scattering layer, more preferably 20 to 80%, and particularly preferably 30 to 75%.
Such a filler does not scatter because the particle size is sufficiently smaller than the wavelength of light, and a dispersion in which the filler is dispersed in a binder polymer behaves as an optically uniform substance.

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

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

Next, an antireflection layer (AR film) in which a middle refractive index layer, a high refractive index layer, and a low refractive index layer are laminated in this order on the protective film will be described.
The antireflection layer comprising at least a middle refractive index layer, a high refractive index layer, and a low refractive index layer (outermost layer) in order on the protective film is designed to have a refractive index satisfying the following relationship: .
Refractive index of high refractive index layer> refractive index of medium refractive index layer> refractive index of protective film> refractive index of low refractive index layer Further, a hard coat layer may be provided between the protective film and the middle refractive index layer. . Furthermore, it may consist of a medium refractive index hard coat layer, a high refractive index layer and a low refractive index layer.
Examples thereof include antireflection layers described in JP-A-8-122504, JP-A-8-110401, JP-A-10-300902, JP-A-2002-243906, JP-A-2000-11706, and the like.
Other functions may be imparted to each layer, for example, an antifouling low refractive index layer or an antistatic high refractive index layer (eg, JP-A-10-206603, JP-A-2002). -243906 publication etc.) etc. are mentioned.
The haze of the antireflection layer is preferably 5% or less, more preferably 3% or less. Further, the strength of the film is preferably H or more, more preferably 2H or more, and most preferably 3H or more in a pencil hardness test according to JIS K5400.

(High refractive index layer and medium refractive index layer)
The layer having a high refractive index of the antireflection film is composed of a cured film containing at least an inorganic compound fine particle having a high refractive index having an average particle diameter of 100 nm or less and a matrix binder.
Examples of the high refractive index inorganic compound fine particles include inorganic compounds having a refractive index of 1.65 or more, preferably those having a refractive index of 1.9 or more. Examples thereof include oxides such as Ti, Zn, Sb, Sn, Zr, Ce, Ta, La, and In, and composite oxides containing these metal atoms.
In order to obtain such fine particles, the surface of the particles is treated with a surface treatment agent (for example, silane coupling agents, etc .: JP-A Nos. 1-295503, 11-153703, 2000-9908). See also publications, etc., anionic compounds or organometallic coupling agents: see JP 2001-310432 A, etc., and a core-shell structure with high refractive index particles as a core (for example, JP 2001-166104 A). And the like (see, for example, JP-A-11-153703, US Pat. No. 6,210,858B1, and JP-A-2002-27776069).
Examples of the material forming the matrix include conventionally known thermoplastic resins and curable resin films.
More preferable materials include a polyfunctional compound-containing composition having at least two polymerizable groups of at least one of radically polymerizable and cationically polymerizable, a composition containing an organometallic compound containing a hydrolyzable group, And at least one composition selected from compositions containing a partial condensate thereof.
For example, JP 2000-47004 A, 2001-315242 A, 20
Examples thereof include compounds described in JP-A Nos. 01-31871 and 2001-296401.

A curable film obtained from a colloidal metal oxide obtained from a hydrolyzed condensate of metal alkoxide and a metal alkoxide composition is also preferred. For example, it describes in Unexamined-Japanese-Patent No. 2001-293818.
The refractive index of the high refractive index layer is preferably 1.70 to 2.20. The thickness of the high refractive index layer is preferably 5 nm to 10 μm, and more preferably 10 nm to 1 μm.
The refractive index of the middle refractive index layer is adjusted to be a value between the refractive index of the low refractive index layer and the refractive index of the high refractive index layer. The refractive index of the middle refractive index layer is preferably 1.50 to 1.70. The thickness is preferably 5 nm to 10 μm, and more preferably 10 nm to 1 μm.

(Low refractive index layer)
The low refractive index layer is formed by sequentially laminating on the high refractive index layer. The refractive index of the low refractive index layer is preferably 1.20 to 1.55. More preferably, it is 1.30-1.50.
The low refractive index layer is preferably constructed as an outermost layer having scratch resistance and antifouling properties. As means for greatly improving the scratch resistance, imparting slipperiness to the surface is effective, and conventionally known thin film layer means such as introduction of silicone or introduction of fluorine can be applied.
The fluorine-containing compound is preferably a compound containing a crosslinkable or polymerizable functional group containing fluorine atoms in the range of 35 to 80% by mass.
For example, paragraph numbers [0018] to [0026] of Japanese Patent Application Laid-Open No. 9-222503, paragraph numbers [0019] to [0030] of Japanese Patent Application Laid-Open No. 11-38220,
Examples include the compounds described in paragraph Nos. [0027] to [0028] of Japanese Patent No. 40284, JP-A 2000-284102, and the like.
The refractive index of the fluorine-containing compound is preferably 1.35 to 1.50. More preferably, it is 1.36-1.47.
The silicone compound is a compound having a polysiloxane structure, preferably containing a curable functional group or a polymerizable functional group in the polymer chain and having a crosslinked structure in the film. For example, reactive silicone (eg, Silaplane (manufactured by Chisso Corporation), silanol group-containing polysiloxane (Japanese Patent Laid-Open No. 11-258403, etc.) and the like can be mentioned.
The crosslinking or polymerization reaction of at least one of the fluorine-containing polymer having a crosslinking or polymerizable group and the siloxane polymer is performed simultaneously with the application of the coating composition for forming the outermost layer containing a polymerization initiator, a sensitizer, or the like. It is preferable to form the low refractive index layer by light irradiation or heating after coating.
Also preferred is a sol-gel cured film in which an organometallic compound such as a silane coupling agent and a specific fluorine-containing hydrocarbon group-containing silane coupling agent are cured by a condensation reaction in the presence of a catalyst.
For example, a polyfluoroalkyl group-containing silane compound or a partially hydrolyzed condensate thereof (Japanese Patent Laid-Open Nos. 58-142958, 58-147483, 58-147484, Japanese Patent Laid-Open Nos. 9-157582, 11) -106704), silyl compounds containing a poly "perfluoroalkyl ether" group which is a fluorine-containing long chain group (Japanese Patent Application Laid-Open Nos. 2000-117902, 2001-48590, 2002) 53804), and the like.
The low refractive index layer has an average primary particle diameter of 1 to 150 nm such as a filler (for example, silicon dioxide (silica), fluorine-containing particles (magnesium fluoride, calcium fluoride, barium fluoride)) as an additive other than the above. Low refractive index inorganic compounds, organic fine particles described in paragraphs [0020] to [0038] of JP-A-11-3820, etc.), silane coupling agents, slip agents, surfactants, and the like can be contained.
When the low refractive index layer is positioned below the outermost layer, the low refractive index layer may be formed by a vapor phase method (vacuum deposition method, sputtering method, ion plating method, plasma CVD method, etc.). The coating method is preferable because it can be manufactured at a low cost.
The film thickness of the low refractive index layer is preferably 30 to 200 nm, more preferably 50 to 150 nm, and most preferably 60 to 120 nm.

(Hard coat layer)
The hard coat layer is provided on the surface of the protective film in order to impart physical strength to the protective film provided with the antireflection layer. In particular, it is preferably provided between the transparent support and the high refractive index layer. The hard coat layer is preferably formed by a crosslinking reaction or a polymerization reaction of a light and / or heat curable compound. The curable functional group in the curable compound is preferably a photopolymerizable functional group. Also, hydrolyzable functional group-containing organometallic compounds and organoalkoxysilyl compounds are preferred.
Specific examples of these compounds are the same as those exemplified for the high refractive index layer. Specific examples of the constituent composition of the hard coat layer include those described in JP-A Nos. 2002-144913, 2000-9908, and WO00 / 46617.
The high refractive index layer can also serve as a hard coat layer. In such a case, it is preferable to form fine particles dispersed in the hard coat layer using the method described for the high refractive index layer.
The hard coat layer can also serve as an antiglare layer containing particles having an average particle size of 0.2 to 10 μm and imparted with an antiglare function (antiglare function).
The film thickness of the hard coat layer can be appropriately designed depending on the application. The film thickness of the hard coat layer is preferably 0.2 to 10 μm, more preferably 0.5 to 7 μm.
The strength of the hard coat layer is preferably H or higher, more preferably 2H or higher, and most preferably 3H or higher in a pencil hardness test according to JIS K5400. Further, in the Taber test according to JISK5400, the smaller the amount of wear of the test piece before and after the test, the better.

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

(Antistatic layer)
When an antistatic layer is provided, it is preferable to impart conductivity with a volume resistivity of 10 ⁻⁸ (Ωcm ⁻⁸³ ) or less. The use of hygroscopic substances, water-soluble inorganic salts, certain surfactants, cationic polymers, anionic polymers, colloidal silica, etc. can give a volume resistivity of 10 ⁻⁸ (Ωcm ⁻³ ). There is a problem that dependency is large, and sufficient conductivity cannot be secured at low humidity. Therefore, a metal oxide is preferable as the conductive layer material. Some metal oxides are colored, but using these metal oxides as the conductive layer material is not preferable because the entire film is colored. Zn as a metal that forms a metal oxide without coloration,
Ti, Al, In, Si, Mg, Ba, Mo, W, or V can be used, and it is preferable to use a metal oxide containing this as a main component. Specific examples include ZnO, TiO ₂ , SnO ₂ , Al ₂ O ₃ , In ₂ O ₃ , SiO ₂ , MgO, BaO, MoO ₃ , V ₂ O ₅ , or a composite oxide thereof. In particular, ZnO, TiO ₂ and SnO ₂ are preferable. Examples of containing different atoms include, for example, additives such as Al and In for ZnO, addition of Sb, Nb and halogen elements for SnO ₂ , and addition of Nb and TA for TiO 2. Is effective. Furthermore, as described in Japanese Examined Patent Publication No. 59-6235, a material in which the above metal oxide is attached to other crystalline metal particles or fibrous materials (for example, titanium oxide) may be used. The volume resistance value and the surface resistance value are different physical properties and cannot be simply compared. However, in order to secure a conductivity of 10 ⁻⁸ (Ωcm ⁻³ ) or less in volume resistance, It is sufficient that the layer has a surface resistance value of about 10 ⁻¹⁰ (Ω / □) or less, and more preferably 10 ⁻⁸ (Ω / □). The surface resistance value of the conductive layer needs to be measured as a value when the antistatic layer is the outermost layer, and can be measured in the middle of forming the laminated film.

(Liquid crystal display device)
The liquid crystal display device of the present invention includes a liquid crystal display device (first form) using at least one polarizing plate of the present invention, a VA mode and an OCB mode using one of the polarizing plates of the present invention one above and below the cell. And a TN mode liquid crystal display device (second embodiment) and a VA mode liquid crystal display device (third embodiment) using only one of the polarizing plates of the present invention on the backlight side.
FIG. 2 is a diagram showing a second embodiment. The third embodiment corresponds to the case where the polarizing plate of the present invention is used only on the light source side in FIG.
That is, the cellulose acylate film of the present invention is advantageously used as an optical compensation sheet. Moreover, the polarizing plate using the cellulose acylate film of the present invention is advantageously used in a liquid crystal display device. The cellulose acylate film of the present invention can be used for liquid crystal cells in various display modes. TN (Twisted Nematic), IPS (In-Plane Switching), FLC (Ferroelectric Liquid Crystal), AFLC (Anti-ferroelectric Liquid Crystal), OCB (Optically Compensatory Bend), STN (Supper Twisted Nematic), VA (Vertically Aligned) and Various display modes such as HAN (Hybrid Aligned Nematic) have been proposed. Among these, it can use preferably for VA mode or OCB mode.

In a VA mode liquid crystal cell, rod-like liquid crystalline molecules are aligned substantially vertically when no voltage is applied.
The VA mode liquid crystal cell includes (1) a narrowly defined VA mode liquid crystal cell in which rod-like liquid crystalline molecules are aligned substantially vertically when no voltage is applied, and substantially horizontally when a voltage is applied (Japanese Patent Laid-Open No. Hei 2-). 176625) (2) Liquid crystal cell (SID97, Digest of tech. Papers (Preliminary Proceed) 28 (1997) 845 in which the VA mode is converted into a multi-domain (MVA mode) for widening the viewing angle ), (3) Liquid crystal cells (n-ASM mode, CPA mode) in which rod-like liquid crystalline molecules are aligned substantially vertically when no voltage is applied and twisted multi-domain alignment is applied when a voltage is applied 58-59 (1998)) and (4) SURVAIVAL mode liquid crystal cells (announced at LCD International 98).
As shown in FIG. 3, the VA mode liquid crystal display device comprises a liquid crystal cell (VA mode cell) and two polarizing plates (polarizing plates comprising TAC1, polarizer and TAC2) disposed on both sides thereof. Is mentioned. The liquid crystal cell carries liquid crystal between two electrode substrates, although not particularly shown.
In one aspect of the transmissive liquid crystal display device of the present invention, the cellulose acylate film of the present invention is used as an optical compensation sheet, and one sheet is disposed between the liquid crystal cell and one polarizing plate, or the liquid crystal cell Two sheets are arranged between both polarizing plates. When one optical compensation sheet is disposed, any one of TAC1 in FIG. 3 can be replaced with a commercially available cellulose acylate film.
In another aspect of the transmissive liquid crystal display device of the present invention, the cellulose acylate film of the present invention is used as a protective film for a polarizing plate disposed between a liquid crystal cell and a polarizer. The cellulose acylate film may be used only for the protective film (between the liquid crystal cell and the polarizer) of one polarizing plate, or between the polarizing plates (between the liquid crystal cell and the polarizer). The cellulose acylate film may be used for the two protective films. For bonding to the liquid crystal cell, the cellulose acylate film (TAC1) of the present invention is preferably on the VA cell side. When the above cellulose acylate film is used only for the protective film (between the liquid crystal cell and the polarizer) of one polarizing plate, these are the upper polarizing plate (observation side) and the lower polarizing plate (backlight side). Either side can be used and there is no functional problem. However, when used as an upper polarizing plate, it is necessary to provide a functional film on the observation side (upper side), and the production yield may be lowered. It is considered an embodiment.
And what formed both the light source side of FIG. 3 and the observer side with the polarizing plate of this invention is the liquid crystal display device of a 2nd form, and what formed only the light source side with the polarizing plate of this invention is 3rd. It is a liquid crystal display device of a form.
The protective film (TAC2) in FIG. 3 may be a commercially available cellulose acylate film, and is preferably thinner than the cellulose acylate film of the present invention. For example, 40-80 μm is preferable, and examples include, but are not limited to, commercially available KC4UX2M (40 μm manufactured by Konica Capto), KC5UX (60 μm manufactured by Konica Capto), TD80 (80 μm manufactured by Fuji Photo Film) and the like.

  EXAMPLES Hereinafter, although this invention is demonstrated concretely based on an Example, this invention is not limited to an Example.

[Example 1: Production of cellulose acylate film by film casting machine (films 1 to 7)]
(1) Cellulose acylate Cellulose acylates having different types of acyl groups and different degrees of substitution described in Table 1 were prepared. In this, sulfuric acid (7.8 parts by mass with respect to 100 parts by mass of cellulose) was added as a catalyst, a carboxylic acid serving as a raw material for the acyl substituent was added, and an acylation reaction was performed at 40 ° C. At this time, the kind and substitution degree of the acyl group were adjusted by adjusting the kind and amount of the carboxylic acid. The acylation was followed by aging at 40 ° C. Further, the low molecular weight component of the cellulose acylate was removed by washing with acetone. In the table, CAB is an abbreviation for cellulose acetate butyrate (cellulose ester derivative in which an acyl group is an acetate and a butyryl group), and CAP is cellulose acetate propionate (an acyl group is an acetate group and a propionyl group). CTA means cellulose triacetate (cellulose ester derivative in which an acyl group is composed only of an acetate group).
(2) Dissolution Cellulose acylate described in Table 1, plasticizer (TPP: triphenyl phosphate, BDP: biphenyl diphenyl phosphate), ultraviolet absorber (UV1: 2- (2'-)
Hydroxy-3 ′, 5′-di-tert-butylphenyl) benzotriazole), UV2: 2- (2′-hydroxy-3 ′, 5′-di-amylphenyl) -5-chlorobenzotriazole), the following letter Add the retardation developing agent (RP1) and the following retardation developing agent (RP2) to the following mixed solvent, dichloromethane / methanol (87/13 parts by mass) with stirring so that the mass concentration of cotton is 15% by mass. The mixture was dissolved by heating and stirring. At this time, a matting agent (AEROSIL) which is fine particles with respect to 100 parts by mass of cellulose acylate at the same time.
R972, manufactured by Nippon Aerosil Co., Ltd.) 0.05 part by mass and 0.0009 part by mass of the dye (Dye1) were added and stirred while heating. The additive amount in Table 1 is the mass of the additive with respect to 100 mass of cotton.
Retardation developer (RP1)

  Retardation expression agent (RP2)

  Dye (Dye1)

(Casting)
The above dope was cast using a band casting machine. A film peeled off from the band with a residual solvent amount of 25 to 35% by mass was stretched at a stretch ratio of 0.5 to 5% in the section from stripping to tenter under the conditions where the stretching temperature was in the range of Tg to Tg + 10 ° C. 1) and then stretched in the width direction at a stretch ratio of 0% to 30% (see Table 1) using a tenter, and contracted in the width direction at a ratio of 0 to 10% immediately after transverse stretching. Then, the film was detached from the tenter and a cellulose acylate film was formed. Table 1 shows the draw ratio. About the produced cellulose acylate film (optical compensation sheet), the Re retardation value and the Rth retardation value at wavelengths of 480 nm, 550 nm, 590 nm, and 630 nm were measured with KOBRA21ADH (manufactured by Oji Scientific Instruments) at 25 ° C. and 60% RH. did. Here, the results are shown in Table 1. In the film of the present invention, Rth (λ) was calculated with an average refractive index of 1.48.

The hazes of the films obtained in this example are all 0.1 to 0.9, the secondary average particle size of the matting agent is 1.0 μm or less, and left for 48 hours under conditions of 80 ° C. and 90% RH. The mass change was 0-3%. Moreover, the dimensional change when it left still for 24 hours on the conditions of 60 degreeC95% RH and 90 degreeC5% RH was 0 to 4.5%. Furthermore, the photoelastic coefficient of any sample was 50 × 10 ⁻¹³ cm ² / dyn (5 × 10 ⁻¹¹ m ² / N) or less.

[Example 2]
[Preparation of two-layer protective film (film 8)]
2,2′-bis (3,4-discarboxyphenyl) hexafluoropropane;
A polyimide synthesized from 2′-bis (trifluoromethyl) -4,4′-diaminobiphenyl was dissolved in cyclohexanone to prepare a 15 mass% solution. This polyimide solution was coated with a base film of “Fujitac TD80UL” {manufactured by Fuji Photo Film Co., Ltd.] for 3.5 μm in thickness after drying, and dried at 150 ° C. for 5 minutes. After stretching 13% in the width direction with a tenter stretching machine in an atmosphere of ° C., relaxed by 2% in the width direction, cut off both ends in front of the winding part to a width of 1474 mm, and wound up as a roll film with a length of 3800 m, Film 8 was obtained. The film 8 had a thickness of 75 μm. With respect to the produced film 8, Re retardation values and Rth retardation values at wavelengths of 480 nm, 550 nm, 590 nm, and 630 nm at 25 ° C. and 60% RH were measured with KOBRA21ADH (manufactured by Oji Scientific Instruments). Here, the results are shown in Table 1. In the film of the present invention, Rth (λ) was calculated with an average refractive index of 1.58. The haze of the film obtained in this example was 1.5.

[Example 3: Production of protective film made of cyclic polyolefin (film 9)]
<Synthesis of Cyclic Polyolefin Polymer P-1>
100 parts by mass of purified toluene and 100 parts by mass of norbornene carboxylic acid methyl ester were charged into a reaction kettle. Next, ethylhexanoate-Ni 25 mmol% (based on monomer mass) dissolved in toluene, tri (pentafluorophenyl) boron 0.225 mol% (based on monomer mass), and triethylaluminum 0.25 mol% (based on monomer mass) dissolved in toluene ) Was charged into the reaction kettle. The reaction was allowed to proceed for 18 hours at room temperature with stirring. After completion of the reaction, the reaction mixture was put into excess ethanol to produce a polymer precipitate. The polymer (P-1) obtained by purifying the precipitate was vacuum dried at 65 ° C. for 24 hours.

  The following composition was put into a mixing tank, stirred to dissolve each component, and then filtered through a filter paper having an average pore size of 34 μm and a sintered metal filter having an average pore size of 10 μm.

―――――――――――――――――――――――――――――――――
Cyclic polyolefin solution D-1
―――――――――――――――――――――――――――――――――
Cyclic polyolefin P-1 150 parts by mass Dichloromethane 380 parts by mass Methanol 70 parts by mass ―――――――――――――――――――――――――――――――――

  Next, the following composition containing the cyclic polyolefin solution D-1 prepared by the above method was charged into a disperser to prepare a fine particle dispersion.

―――――――――――――――――――――――――――――――――
Fine particle dispersion M-1
―――――――――――――――――――――――――――――――――
Silica particles having an average particle diameter of 16 nm (aerosil R972 Nippon Aerosil Co., Ltd.) 2 parts by mass Dichloromethane 73 parts by mass Methanol 10 parts by mass Cyclic polyolefin solution D-1 10 parts by mass ――――――――――――― ―――――――――――――――――――

100 parts by mass of the cyclic polyolefin solution D-1 and 1.35 masses of the fine particle dispersion M-1 were mixed to prepare a dope for film formation.
The dope was cast using a band casting machine. Hot air was applied from the surface of the web on the metal support. The temperature of the hot air is 140 ° C., and the air volume is 200 m ³ / min. A film peeled off from the band with a residual solvent amount of 43% by mass was stretched in the width direction at a stretching temperature of 140% using a tenter at a stretching ratio of 10%, and then relaxed by 2% in the width direction to produce a cyclic polyolefin film. Filmed. Both ends were cut off in front of the winding part to make a width of 2000 mm and wound up as a roll film 9 having a length of 4000 m.
With respect to the produced film 9, Re retardation values and Rth retardation values at wavelengths of 480 nm, 550 nm, 590 nm, and 630 nm were measured at 25 ° C. and 60% RH with KOBRA21ADH (manufactured by Oji Scientific Instruments). The results are shown in Table 1. In the film of the present invention, Rth (λ) was calculated with an average refractive index of 1.51. The haze of the film obtained in this example was 0.5.

[Example 4: Production of protective film made of cyclic polyolefin (film 10)]
The following composition was put into a mixing tank, stirred to dissolve each component, and then filtered through a filter paper having an average pore size of 34 μm and a sintered metal filter having an average pore size of 10 μm.

――――――――――――――――――――――――――――――――――
Cyclic polyolefin solution D-2
――――――――――――――――――――――――――――――――――
Cyclic polyolefin: Appear 3000 100 parts by mass
(Promelas)
Dichloromethane 380 parts by mass Methanol 70 parts by mass ――――――――――――――――――――――――――――――――――――

  Next, the following composition containing the cyclic polyolefin solution prepared by the above method was charged into a disperser to prepare a fine particle dispersion M-2.

―――――――――――――――――――――――――――――――――
Fine particle dispersion M-2
―――――――――――――――――――――――――――――――――
Silica particles having an average particle diameter of 16 nm (aerosil R972, manufactured by Nippon Aerosil Co., Ltd.) 2 parts by mass Dichloromethane 73 parts by mass Methanol 10 parts by mass Cyclic polyolefin solution D-2 10 parts by mass ――――――――――――― ――――――――――――――――――――

100 parts by mass of the cyclic polyolefin solution D-2 and 1.35 masses of the fine particle dispersion M-2 were mixed to prepare a dope for film formation.
The dope was cast using a band casting machine. Hot air was applied from the surface of the web on the metal support. The temperature of the hot air is 140 ° C., and the air volume is 200 m ³ / min. A film stripped from the band with a residual solvent amount of 38% by mass was stretched in the width direction at a stretching temperature of 140% using a tenter at a stretching ratio of 15%, and then relaxed by 2% in the width direction to form a cyclic polyolefin film. A film was formed. Both ends were cut off in front of the winding part to make a width of 2000 mm, and the roll film 10 having a length of 4000 m was taken up.
About the produced film 10, Re retardation value and Rth retardation value in wavelength 480nm, 550nm, 590nm, and 630nm were measured with KOBRA21ADH (Oji Scientific Instruments Co., Ltd.) at 25 degreeC60% RH. The results are shown in Table 1. In the film of the present invention, Rth (λ) was calculated with an average refractive index of 1.51. The haze of the film obtained in this example was 0.6.

[Example 5: Production of protective film with antireflection function (protective film 1)]
(Preparation of coating solution for light scattering layer)
50 g of a mixture of pentaerythritol triacrylate and pentaerythritol tetraacrylate (PETA, Nippon Kayaku Co., Ltd.) was diluted with 38.5 g of toluene. Furthermore, 2 g of a polymerization initiator (Irgacure 184, manufactured by Ciba Specialty Chemicals Co., Ltd.) was added and mixed and stirred.
The refractive index of the coating film obtained by applying this solution and curing with ultraviolet rays was 1.51.
Further, a 30% toluene dispersion of crosslinked polystyrene particles having an average particle size of 3.5 μm (refractive index: 1.60, SX-350, manufactured by Soken Chemical Co., Ltd.) dispersed in this solution for 20 minutes at 10,000 rpm with a Polytron disperser. Add 13.3 g of a 30% toluene dispersion of 1.7 g and crosslinked acrylic-styrene particles having an average particle size of 3.5 μm (refractive index 1.55, manufactured by Soken Chemical Co., Ltd.), and finally, fluorine-based surface modification 0.75 g of an agent (FP-1) and 10 g of a silane coupling agent (KBM-5103, manufactured by Shin-Etsu Chemical Co., Ltd.) were added to obtain a finished solution.
The liquid mixture was filtered through a polypropylene filter having a pore size of 30 μm to prepare a light scattering layer coating solution.
<Fluorine-based surface modifier (FP-1)>

(Preparation of coating solution for low refractive index layer)
First, sol solution a was prepared as follows. A stirrer, a reactor equipped with a reflux condenser, 120 parts of methyl ethyl ketone, 100 parts of acryloyloxypropyltrimethoxysilane (KBM5103, manufactured by Shin-Etsu Chemical Co., Ltd.), 3 parts of diisopropoxyaluminum ethyl acetoacetate were added and mixed. After adding 30 parts of ion-exchanged water and reacting at 60 ° C. for 4 hours, the mixture was cooled to room temperature to obtain a sol solution a. The mass average molecular weight was 1600, and among the components higher than the oligomer component, the component having a molecular weight of 1000 to 20000 was 100%. Further, from the gas chromatography analysis, the raw material acryloyloxypropyltrimethoxysilane did not remain at all.
Thermally crosslinkable fluorine-containing polymer having a refractive index of 1.42 (JN-7228, solid content concentration 6%, manufactured by JSR Corporation) 13 g, silica sol (silica, MEK-ST particle size difference, average particle size 45 nm, solid content Concentration 30%, manufactured by Nissan Chemical Co., Ltd.) 1.3 g, 0.6 g of sol solution a prepared as described above, 5 g of methyl ethyl ketone, and 0.6 g of cyclohexanone were added. Filtration was performed to prepare a coating solution for a low refractive index layer.

(Preparation of transparent protective film with antireflection layer)
An 80 μm-thick triacetylcellulose film (Fujitac TDY80UL, manufactured by Fuji Photo Film Co., Ltd.) is unwound in a roll form, and the coating liquid for the functional layer (light scattering layer) is 180 lines / inch, depth Using a micro gravure roll with a diameter of 50 mm having a 40 μm gravure pattern and a doctor blade, the coating was applied under the conditions of a gravure roll rotation speed of 30 rpm and a conveyance speed of 30 m / min, drying at 60 ° C. for 150 seconds, and further under a nitrogen purge. 1
Using a 60 W / cm air-cooled metal halide lamp (manufactured by Eye Graphics Co., Ltd.), the coating layer is cured by irradiating ultraviolet rays with an irradiance of 400 mW / cm ² and an irradiation amount of 250 mJ / cm ^2. A layer was formed and wound up.
The triacetylcellulose film coated with the functional layer (light scattering layer) is unwound again, and the prepared coating liquid for low refractive index layer is 180 lines / inch and the depth is 40 μm on the light scattering layer side.
Using a micro gravure roll having a diameter of 50 mm and a doctor blade having a gravure pattern, the coating was performed under the conditions of a gravure roll rotation speed of 30 rpm and a conveyance speed of 15 m / min.
After drying at 0 ° C. for 150 seconds, further drying at 140 ° C. for 8 minutes, and using a 240 W / cm air-cooled metal halide lamp (manufactured by Eye Graphics Co., Ltd.) under a nitrogen purge, the irradiance is 400 mW / cm ² 2. The film was irradiated with ultraviolet rays having an irradiation amount of 900 mJ / cm ² to form a low refractive index layer having a thickness of 100 nm, and wound up to produce a protective film with an antireflection function (protective film 1).

[Example 6]
(Preparation of polarizing plate)
A polyvinyl alcohol (PVA) film having a thickness of 80 μm is dyed by immersing it in a potassium iodide aqueous solution having a potassium iodide concentration of 2% by mass at 30 ° C. for 60 seconds, and then in a boric acid aqueous solution having a boric acid concentration of 4% by mass. The film was longitudinally stretched 5 times the original length while being immersed in the film for 60 seconds, and then dried at 50 ° C. for 4 minutes to obtain a polarizing film A having a thickness of 20 μm.
Further, a polyvinyl alcohol (PVA) film having a thickness of 80 μm is dyed by dipping in a potassium iodide aqueous solution having a potassium iodide concentration of 12% by mass at 30 ° C. for 60 seconds, and then boric acid having a boric acid concentration of 4% by mass. While being immersed in an aqueous solution for 60 seconds, the film was longitudinally stretched to 5 times the original length and then dried at 50 ° C. for 4 minutes to obtain a polarizing film B having a thickness of 20 μm.
Protective film prepared in Examples 1 and 2 shown in Table 1 and commercially available cellulose acylate film Fujitac TDY80UL (manufactured by Fuji Photo Film Co., Ltd.) at 55 mol / liter
After immersing in a sodium hydroxide aqueous solution at 0 ° C., the sodium hydroxide was sufficiently washed away with water. Then, after being immersed in a diluted sulfuric acid aqueous solution at 0.005 mol / liter at 35 ° C. for 1 minute, it was immersed in water to sufficiently wash away the diluted sulfuric acid aqueous solution.
Finally, the sample was thoroughly dried at 120 ° C.
Using the polyvinyl alcohol adhesive so as to sandwich the polarizing film in the combination shown in Table 2 with the protective film prepared in Examples 1 to 3 subjected to saponification treatment as described above and the commercially available cellulose acylate Fujitac TDY80UL. The laminated polarizing plates 1-11 were obtained.
Commercially available cellulose acylate film Fujitac TDY80UL (Fuji Photo Film Co., Ltd.), which was saponified in the same manner as described above, on one side of a polarizer produced in the same manner as in Example 1, using a polyvinyl alcohol-based adhesive. The films 9 and 10 prepared in Examples 3 and 4 were bonded to the other surface using an acrylic adhesive “DD624” {manufactured by Nogawa Chemical Co., Ltd.} to prepare bonded polarizing plates 12 and 13.
At this time, since the polarizing film and the protective films on both sides of the polarizing film are produced in a roll form, the longitudinal directions of the roll films are parallel to each other and are continuously bonded. Moreover, as shown in FIG. 1, in the protective film arrange | positioned at the cell side, the transmission axis of a polarizer and the slow axis of the optical compensation sheet produced in Examples 1-4 are parallel.
An acrylic adhesive was applied to the cell side surface of the polarizing plate prepared above, and a separate film was attached on the adhesive. A protective film was attached to the surface opposite to the cell.

[Example 7]
Using a spectrophotometer (manufactured by JASCO Corporation), the spectral reflectance at an incident angle of 5 ° is measured from the functional film side in the wavelength region of 380 to 780 nm, and the integrating sphere average reflectance of 450 to 650 nm is obtained. When it asked for, it was 2.3% in polarizing plates 9-10 which used protective film 1 which is a transparent protective film with an antireflection layer. Here, the protective film on the transparent protective film with the antireflection layer was peeled off, and the reflectance was measured.

[Example 8]
(Mounting on the panel)
Mounting on VA panel (single-sheet type)
The polarizing plates 1 and 13 of the VA mode liquid crystal TV (LC-32AD5, manufactured by Sharp Corporation) were peeled off and the polarizing plates 1 to 13 produced in Example 3 were pasted in the combinations shown in Table 3. It was. In this case, the absorption axis of the polarizing plate on the viewing side is in the horizontal direction of the panel, the absorption axis of the polarizing plate on the backlight side is in the vertical direction of the panel, and the pressure-sensitive adhesive surface is on the liquid crystal cell side. In the liquid crystal display device LCD7, the cold cathode ray tube used for the backlight was replaced with one having a color temperature of 12000K.
After removing the protective film, the brightness and chromaticity of black display and white display are measured in a dark room using a measuring instrument (EZ-Contrast 160D, manufactured by ELDIM), and the color shift and contrast ratio in black display are calculated. did. The results are shown in Table 3. The color shift and viewing angle in black display will be described below. The chromaticity is the value of the coordinate axis in the CIE x, y chromaticity space.

[Black color shift in polar direction]
In black display, changes in chromaticity Δxθ and Δyθ when the viewing angle is tilted from the normal direction of the liquid crystal cell to the center line direction of the transmission axis of the pair of polarizing plates (azimuth angle 45 degrees) are polar angles 0 to 80 degrees. It is preferable that the following formulas (XXIII) and (XXIV) are always satisfied.
Formula (XXIII): 0 ≦ Δxθ ≦ 0.1
Formula (XXIV): 0 ≦ Δyθ ≦ 0.1
[Where Δxθ = xθ−xθ0, Δyθ = yθ−yθ0, (xθ0, yθ0) is the chromaticity measured in the normal direction of the liquid crystal cell in black display, and (xθ, yθ) is the liquid crystal cell method in black display. Chromaticity measured in the direction of the viewing angle tilted from the linear direction to the polar axis θ degrees in the direction of the center line of the transmission axis of the pair of polarizing plates]

[Black color shift in azimuth direction]
Further, the color when the viewing angle is tilted from the normal direction of the liquid crystal cell to 60 degrees in the absorption axis direction of the polarizing plate on the viewing side, and the chromaticity is measured by rotating 360 degrees around the normal with the direction as the base point. The degree change Δxφ is preferably such that Δyφ always satisfies the following formulas (XXV) and (XXVI) between azimuth angles of 0 to 360 degrees.
Formula (XXV): −0.02 ≦ Δxφ ≦ 0.1
Formula (XXVI): −0.02 ≦ Δyφ ≦ 0.1
[In the formula, Δxφ = xφ−xφ0, Δyφ = yφ−yφ0, and (xφ0, yφ0) tilts the viewing angle from the normal direction of the liquid crystal cell in black display to the absorption axis direction of the viewing side polarizing plate by 60 degrees. The measured chromaticity, (xφ, yφ), tilts the viewing angle from the normal direction of the liquid crystal cell in the black display to 60 degrees in the absorption axis direction of the viewing side polarizing plate, and from the direction of the azimuth angle φ around the normal direction. Measured chromaticity]

[Viewing angle]
A larger contrast ratio at an azimuth angle of 45 degrees and a polar angle of 60 degrees means a wider viewing angle.

[Observation of black display under illumination]
In an environment where the irradiance on the surface of the liquid crystal display device is 150 (lx) under daylight color fluorescent lamp illumination, the liquid crystal display device is displayed in black, and the brightness and display color of the screen is set from 45 degrees azimuth and 60 degrees polar. It was observed visually. The results are shown in Table 3.

  As shown in Table 3, the liquid crystal display devices LCD1 to LCD5 and LCD10 to 12 using polarizing plates satisfying the retardation characteristics and hues a * and b * defined in the present invention are both azimuth and polar angles. The color shift in any direction was small, and the black display portion was sufficiently black and dark in the bright room, and the viewing angle contrast was sufficient. On the other hand, in the liquid crystal display device of the comparative example, none of the liquid crystal display devices satisfy all of these characteristics.

It is a schematic diagram which shows the bonding method of the cellulose acylate film at the time of manufacture of the polarizing plate of this invention. It is sectional drawing which shows typically the cross-section of the polarizing plate of this invention. It is sectional drawing which shows typically the cross-section of the polarizing plate of this invention.

Claims (15)

A liquid crystal display device in which a liquid crystal cell and a pair of polarizing plates are arranged orthogonally on both sides of the liquid crystal cell,
Wherein on one side of the liquid crystal cell alone, Ri polarizer der comprising at least one protective film and the polarizing film, the protective film disposed on the liquid crystal cell side Re (lambda) and Rth (lambda) is the following satisfying the formula (I) and (II), the liquid crystal display when the orthogonal arrangement polarizers hue a * and b * are characterized by having a polarizing plate that meets the following formula (III) and (IV) Equipment .
Formula (I): 45 nm ≦ Re (590) ≦ 65 nm
Formula (II): 190 nm ≦ Rth (590) ≦ 220 nm
Formula (III): −1.0 ≦ a * ≦ 2.0
Formula (IV): −1.0 ≦ b * ≦ 2.0
[In the formula, Re (λ) is a front retardation value (unit: nm) at a wavelength λnm, and Rth (λ) is a retardation value (unit: nm) in a film thickness direction at a wavelength λnm. ] The protective film arranged on the liquid crystal cell side is a rod-like compound or discotic compound retardation developer, and contains at least one retardation developer having a maximum absorption in a wavelength region of 250 to 400 nm . The liquid crystal display device according to claim 1 . The polarizing plate, single transmittance of 41% or more, parallel transmittance of 35% or more, crossed transmittance of 0.02% or less, according to claim 1 polarization is equal to or not less than 99.93%, or 2. A liquid crystal display device according to 2 . Re of the protective film disposed on the liquid crystal cell side (lambda) and Rth (lambda) is the liquid crystal display device according to any one of claims 1 to 3 and satisfies the following formula (V) to (VIII) .
Formula (V): 1.0 ≦ Re (480) / Re (550) ≦ 1.1
Formula (VI): 0.9 ≦ Re (630) / Re (550) ≦ 1.0
Formula (VII): 1.0 ≦ Rth (480) / Rth (550) ≦ 1.1
Formula (VIII): 0.9 ≦ Rth (630) / Rth (550) ≦ 1.0 The protective film disposed on the liquid crystal cell side is a film made of cellulose acylate obtained by substituting the hydroxyl group of glucose units constituting cellulose with an acyl group having 2 or more carbon atoms, and constitutes cellulose. When the substitution degree of the hydroxyl group at the 2-position of the glucose unit with the acyl group is DS2, the substitution degree of the hydroxyl group at the 3-position with the acyl group is DS3, and the substitution degree with the acyl group of the hydroxyl group at the 6-position is DS6, the following formula (IX ) and (a liquid crystal display device according to any one of claims 1 to 4, characterized in that a cellulose acylate film satisfying X).
Formula (IX): 2.0 ≦ DS2 + DS3 + DS6 ≦ 3.0
Formula (X): DS6 / (DS2 + DS3 + DS6) ≧ 0.315 The liquid crystal display device according to claim 5 , wherein the acyl group is an acetyl group. Cellulose acylate comprising, as a main polymer component, a cellulose acylate in which a protective film disposed on the liquid crystal cell side is a mixed fatty acid ester of cellulose in which a hydroxyl group of cellulose is substituted with an acetyl group and an acyl group having 3 or more carbon atoms The cellulose acylate is characterized in that the substitution degree A of acetyl groups and the substitution degree B of acyl groups having 3 or more carbon atoms satisfy the following formulas (XI) and (XII): the liquid crystal display device according to any one of claims 1 to 4.
Formula (XI): 2.0 ≦ A + B ≦ 3.0
Formula (XII): 0 <B The liquid crystal display device according to claim 7 , wherein the acyl group having 3 or more carbon atoms is a butanoyl group. The liquid crystal display device according to claim 7 , wherein the acyl group having 3 or more carbon atoms is a propionyl group. The liquid crystal display device according to any one of claims 7 to 9 6-position substitution degree of the hydroxyl groups of cellulose, characterized in that at least 0.75. The liquid crystal display device according to any one of claims 1 to 4 , wherein the protective film disposed on the liquid crystal cell side is a film made of a cyclic polyolefin. Protective film disposed on the liquid crystal cell side, a plasticizer, an ultraviolet absorber, release promoter, dyes, and any of claims 1 to 1 1, characterized by containing one or more of the matting agent the liquid crystal display device according to an item or. Protective film disposed on the liquid crystal cell side, the liquid crystal display device according to any one of claims 1 to 12, characterized in that a protective film made of only one layer. The liquid crystal display device according to any one of claims 1 to 13, wherein the backlight has a color temperature of 8000 to 10,000K. The liquid crystal display device according to any one of claims 1 to 1 4, wherein the liquid crystal cell is a vertical alignment mode.

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