JP2007112870A - Method for preparation of cellulose acylate solution, cellulose acylate film for optical use, polarizing plate and liquid crystal display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for preparation of cellulose acylate solution having a high productivity, and suitable for production of a highly productive cellulose acylate film for optical use, which has an excellent surface quality (optical uniformity and low scattering property), in particular having a high optical anisotropy such as a compensation film for VA (vertical alignment) type liquid crystal display. <P>SOLUTION: The method for preparation of cellulose acylate solution comprises dissolution of cellulose acylate particles having 22-43° of angle of repose, 0.30-0.75 g/cm<SP>3</SP>of bulk density and having ≤3 mass% of particles with ≥1.7 mm of particle diameter. The cellulose acylate preferably, satisfies following inequalities, 2.0≤DS2+DS3+DS6≤3.0 and/or DS6/(DS2+DS3+DS6)≥0.315, wherein the DS2 is a degree of substitution of the hydroxyl group on the 2nd position of a glucose unit, DS3 is a degree of substitution of the hydroxyl group on the 3rd position of the glucose unit, and DS6 is a degree of substitution of the hydroxyl group on the 6th position of the glucose unit. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for preparing a cellulose acylate solution, a method for producing a cellulose acylate film, and a cellulose acylate film obtained therefrom. Furthermore, the present invention relates to an optical cellulose acylate film, a polarizing plate using the same as an optical compensation sheet, and a liquid crystal display device including 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.

  In the liquid crystal display device, the use of an optical compensation sheet for widening the viewing angle, improving image coloring, and improving contrast is a well-known technique as described above. Among them, a film in which a low molecular compound having high planarity is added to cellulose ester is particularly useful because it can adjust the retardation in a wide range, and is disclosed in Patent Document 1.

Optical films (polarizing plate protective films and optical compensation films) used in such liquid crystal display devices are required to have higher surface quality as the liquid crystal display devices have higher definition and larger screens.
In Patent Document 2, in order to reduce the number of so-called bright spot foreign matters having a size of 5 μm or more when the film is observed under a crossed Nicol using a polarizing microscope, the powder characteristics (repose angle) of cellulose ester are reduced. , A bulk density, a tap density, a degree of compression) and a particle diameter are improved to 1 to 20 mm, and a method for improving optical defects (bright spot foreign matter) is disclosed.
However, in the above method, as described in paragraph 38 of Patent Document 2, the particle diameter of the starting material is 0.01 mm to 0.5 mm, and sieving is first performed to obtain the starting material. Since granulation has been performed to obtain particles having a particle diameter of 1 to 20 mm, it is complicated in two steps of sieving and granulation, and cannot be practically employed in terms of productivity.

Further, in the cellulose ester film prepared from the above method of Patent Document 2, although the number of optical defects (bright spot foreign matter) of 5 μm or more can be suppressed, particularly when an optical compensation film having high optical properties is prepared, the thickness direction It became clear that there was a large variation in retardation (Rth). This is because the particles are not uniformly dissolved at a finer level, and there are insolubles at a finer level, so the drying at the fine level is uneven and the solution casting drying process It is inferred that the Rth generated in the process is uneven.
In recent years, optical films are a very important issue in the industry because of the ever-increasing demand for both improved productivity and improved surface quality.
JP 2000-1111914 A JP 2002-128903 A

  An object of the present invention is an optical cellulose acylate film, particularly vertical, which has high productivity, good surface quality (optical homogeneity and low scattering property), and can be used as an optical compensation sheet. Method for preparing cellulose acylate solution suitable for production of optical cellulose acylate film having high optical anisotropy and high productivity as required for compensation film of alignment type (VA) liquid crystal display device Is to provide.

  Another object of the present invention is to provide an optical cellulose acylate film, a polarizing plate having an optical compensation function, and a liquid crystal display device excellent in display performance by the method for preparing a cellulose acylate solution.

As a result of intensive studies, the present inventors have determined that the repose angle of the cellulose acylate particles is from 22 degrees to 43 degrees, the bulk density is from 0.30 g / cm ^{3 to} 0.75 g / cm ³ , and among the cellulose acylate particles. When the particle diameter is larger than 1.7 mm, by making the mass ratio 3% or less, the bright spot foreign matter is reduced, the variation in Rth is suppressed from 10%, and sufficient film surface quality can be obtained. I found out.
As a result of further intensive studies, the ratio of the substitution degree at the 6-position of the cellulose acylate particles is set to 0.315 or more with respect to the total substitution degree, and particles having a particle size of 0.85 mm or less are 70% of the whole particles by mass ratio. By occupying the above, it has been found that Rth variation and bright spot foreign matter are reduced.

The object is achieved by the following configuration.
(1) or less angle of repose 22 degrees 43 degrees, or less bulk density 0.30 g / cm ³ or more 0.75 g / cm ^3, the mass ratio of the particle size 1.7mm larger particles is 3% or less A method for preparing a cellulose acylate solution, comprising dissolving cellulose acylate particles in an organic solvent.
(2) The substitution degree of the hydroxyl group at the 2-position of the glucose unit of the cellulose acylate with an acyl group is DS2, the substitution degree of the 3-position hydroxyl group with an acyl group is DS3, and the substitution degree of the 6-position hydroxyl group with an acyl group is DS6. In some cases, the cellulose acylate satisfies at least one of the following formulas (I) and (II).
Formula (I): 2.0 ≦ DS2 + DS3 + DS6 ≦ 3.0
Formula (II): DS6 / (DS2 + DS3 + DS6) ≧ 0.315
(3) Cellulose acylate particles containing particles having a particle size of 0.85 mm or less on a mass basis in an amount of 70% or more of all constituent particles are dissolved in an organic solvent, as described in (1) or (2) above A method for preparing a cellulose acylate solution.
(4) A cellulose acylate solution is prepared by the method described in any one of (1) to (3) above, cast on the support, and the solvent is dried to form a film. A method for producing a cellulose acylate film.

(5) A cellulose acylate film obtained by the production method described in (4) above.
(6) The substitution degree A of the hydroxyl group of the cellulose acylate with an acetyl group and the substitution degree B with an acyl group having 3 or more carbon atoms satisfy the following formula (III), and the casting direction or the casting width direction The cellulose acylate film for optical use according to (5), wherein the film is substantially stretched by 10% or more.
Formula (III): 2.0 ≦ A + B ≦ 3.0
(7) The optical cellulose acylate film as described in (6) above, wherein the acyl group is a butanoyl group.
(8) The optical cellulose acylate film as described in (5) above, wherein the acyl group is a propionyl group and the substitution degree B is 0.6 or more.
(9) The front retardation Re (590) and retardation Rth (590) in the film thickness direction at a wavelength of 590 nm of the film satisfy the following formulas (IX) and (X): The cellulose acylate film for optics according to any one of (8).
Formula (IX): 30 nm ≦ Re (590) ≦ 200 nm
Formula (X): 70 nm ≦ Rth (590) ≦ 400 nm
(10) The cellulose acylate film for optical use according to (9), wherein Re (590) and Rth (590) satisfy the following mathematical formulas (XI) and (XII).
Formula (XI): 40 ≦ Re (590) ≦ 100
Formula (XII): 120 nm ≦ Rth (590) ≦ 300 nm
(11) The optical cellulose acylate film as described in any one of (5) to (10) above, which contains at least one retardation enhancer comprising a rod-like or discotic compound.
(12) The cellulose acylate film for optics according to any one of (5) to (11) above, which contains at least one of a plasticizer, an ultraviolet absorber and a peeling accelerator. .
(13) The optical cellulose acylate according to any one of (5) to (12) above, which is stretched by a uniaxial stretching method, a simultaneous biaxial stretching method or a sequential biaxial stretching method. the film.
(14) Front retardation Re (590) at a wavelength of 590 nm of the film at 25 ° C. and a relative humidity of 60%, retardation Rth (590) in the film thickness direction at a wavelength of 590 nm of the film at a temperature of 25 ° C. and a relative humidity of 60%, The optical cellulose acylate film according to any one of (5) to (13), wherein an adjustment coefficient a of the optical properties of the film satisfies the following mathematical formulas (A) to (C): .
Formula (A): 40 nm ≦ Re (590) ≦ 145 nm
Formula (B): Rth (590) = a−5.9Re (590)
Formula (C): 520 nm ≦ a ≦ 670 nm

(15) A polarizing plate having protective films on both sides of a polarizer, wherein at least one of the protective films is the optical cellulose acylate film according to any one of (5) to (14). A polarizing plate characterized by.
(16) The polarizing plate as described in (15) above, wherein at least one of a hard coat layer, an antiglare layer and an antireflection layer is provided on the surface of one protective film of the polarizer.
(17) The optical cellulose acylate film according to any one of (5) to (14) above and the polarizing plate according to (15) or (16) are provided. Liquid crystal display device.
(18) An OCB or VA mode liquid crystal display device using the polarizing plate according to (15) or (16) above in at least one of upper and lower sides of a cell.
(19) A VA mode liquid crystal display device using any one of the polarizing plates described in (15 or (16) above on the backlight side.

  By using the solution preparation method of the present invention, it is possible to quickly prepare a stable and optically homogeneous solution that is less likely to generate foreign matters. The cellulose acylate film produced by this method has high productivity and retardation in the film thickness direction. The film has good surface quality such that there is little variation in the thickness of the film, there are few foreign matters in the film, and no whitening occurs, and it can be used as an optical compensation sheet. The polarizing plate of the present invention also has an optical compensation function, and the liquid crystal display device of the present invention is excellent in display performance.

  Hereinafter, the present invention will be described in more detail. The description of the constituent elements described below may be made based on typical embodiments of the present invention, but the present invention is not limited to such embodiments. 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. When a hydrogen atom is substituted with an atom other than a hydrogen atom, the atom other than the hydrogen atom is treated as a substituent for convenience.

First, the optical cellulose acylate film of the present invention is described.
[Cellulose acylate]
The optical cellulose acylate used in the present invention (hereinafter simply referred to as “the cellulose acylate of the present invention”) will be described in detail. In the present invention, two or more different cellulose acylates may be mixed and used.
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 substitution degree of 1).
When all acyl substitution degrees are acetyl substitution degree, it can measure using ASTM: D-817-91. Moreover, the substitution degree of each substitution position can be measured by NMR method.
In the present invention, the substitution degree of the hydroxyl group at the 2-position of the glucose unit of the cellulose acylate film with DS2 is DS2, the substitution degree with the acyl group of the hydroxyl group at position 3 is DS3, and the substitution degree of the hydroxyl group at the 6-position is DS6. The following mathematical formulas (I) and (I) are satisfied.
Formula (I): 2.0 ≦ DS2 + DS3 + DS6 ≦ 3.0
Formula (I): DS6 / (DS2 + DS3 + DS6) ≧ 0.315

  Among the above, DS2 + DS3 + DS6 is 2.00 to 3.00, preferably 2.40 to 2.98, and particularly preferably 2.60 to 2.96. DS6 / (DS2 + DS3 + DS6) is preferably 0.200 to 0.360, more preferably 0.240 to 0.350, and most preferably 0.280 to 0.340.

  The cellulose acylate film of the present invention is produced using a cellulose acylate having a molecular weight distribution Mw / Mn of 2.0 to 3.4 obtained by dividing the mass average molecular weight Mw by the number average molecular weight Mn.

Here, the mass average molecular weight Mw and the number average molecular weight Mn can be calculated using gel permeation chromatography shown below. The measurement conditions are as follows.
Gel permeation chromatography Solvent (eluent): Dichloromethane Column name: Showa Denko GPCk806- GPCk805- GPCk803 (3)
Sample concentration: 0.1 (mass%)
Flow rate: 1.0 (ml / min)
Sample injection volume: 100 (μl)
Standard sample: Polystyrene (Mw: 5,000-6,700,000)
Temperature: 25 ° C
Detection: RI (differential refractometer)

  When the molecular weight distribution Mw / Mn is less than 2.0, the mechanical properties of the film are lowered, stretching unevenness is likely to occur, and the flatness of the film is lowered. On the other hand, when the molecular weight distribution exceeds 3.4, the dope viscosity is increased, casting stripes and the like are easily generated, and the surface state is deteriorated and the peelability is deteriorated. The molecular weight distribution Mw / Mn is preferably 2.2 to 3.4, more preferably 2.4 to 3.4.

The range of the mass average molecular weight Mw is preferably 70,000 to 300,000, more preferably 80,000 to 280,000, and further preferably 100,000 to 260,000.
The mass average molecular weight Mw, the number average molecular weight Mn, and the molecular weight distribution Mw / Mn can be controlled by changing, for example, the amount of catalyst sulfuric acid, or changing the heating time, heating temperature, and stirring speed in the acetylation process of the raw material cellulose.

The cellulose acylate of the present invention is a fatty acid ester of cellulose obtained by substituting a hydroxyl group of cellulose with an acetyl group and / or an acyl group having 3 or more carbon atoms, preferably a substitution of cellulose with a hydroxyl group. The degree preferably satisfies the following mathematical formula (III).
Formula (III): 2.0 ≦ A + B ≦ 3.0
Here, in the formula, A and B 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.

When A + B is 2.0 or more, hydrophilicity is weak and it is difficult to be influenced by environmental humidity.
When B is 0 and becomes cellulose acetate, it becomes susceptible to environmental humidity.

Further, 28% or more of B is preferably the substitution degree of the 6-position hydroxyl group, more preferably 30% or more is the substitution degree of the 6-position hydroxyl group, more preferably 31% or more, and particularly preferably 32% or more. The substitution degree of the 6-position hydroxyl group is preferred.
Furthermore, the total substitution degree of A and B at the 6-position hydroxyl group 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 having 3 or more carbon atoms may be an aliphatic group or an aromatic hydrocarbon group, and is not particularly limited. These are, for example, cellulose alkylcarbonyl esters, alkenylcarbonyl esters, aromatic carbonyl esters, aromatic alkylcarbonyl esters, and the like, each of which may further have a substituted group. Preferably, propionyl group, butanoyl group, keptanoyl group, hexanoyl group, octanoyl group, decanoyl group, dodecanoyl group, tridecanoyl group, tetradecanoyl group, hexadecanoyl group, octadecanoyl group, isobutanoyl group, tert-butanoyl group, A cyclohexanecarbonyl group, an oleoyl group, a benzoyl group, a naphthylcarbonyl group, a cinnamoyl group, etc. can be mentioned. Among these, a propionyl group, butanoyl group, dodecanoyl group, octadecanoyl group, tert-butanoyl group, oleoyl group, benzoyl group, naphthylcarbonyl group, cinnamoyl group 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 0.6 or more.

  Specific examples of cellulose acylate include cellulose acetate, cellulose acetate propionate, and cellulose acetate butyrate.

[Method of synthesizing cellulose acylate]
The basic principle of the cellulose acylate synthesis method is described in Mita et al., Wood chemistry, 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.
Specifically, cellulose raw materials such as cotton linter and wood pulp are pretreated with an appropriate amount of acetic acid, and then put into a pre-cooled carboxylated mixed solution to be esterified to complete cellulose acylate (2nd, 3rd and 6th). The total degree of acyl substitution at the position 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 a desired acyl substitution degree 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) to separate the cellulose acylate, and the specific cellulose acylate is obtained by washing and stabilizing treatment. Obtainable.

  In the cellulose acylate film, the polymer component constituting the film is preferably substantially composed of the specific cellulose acylate. “Substantially” means 55% by mass or more (preferably 70% by mass or more, more preferably 80% by mass or more) of the polymer component.

  In the method of Patent Document 2, which is a conventional method, first, sieving is performed to obtain a starting material, and the particles are classified into those having a particle diameter of 0.01 mm to 0.5 mm. Since a 20 mm product was obtained, it was complicated in two steps of sieving and granulation. This method has a problem that the yield at the time of sieving and the yield at the time of granulation is low, and improvement has been demanded from the viewpoint of productivity.

Furthermore, in the cellulose ester film prepared from the above method of Patent Document 2, the number of optical defects (bright spot foreign matter) of 5 μm or more can be suppressed, but when creating an optical compensation film that requires particularly high optical performance, In particular, there is a problem that the variation in retardation (Rth) in the thickness direction becomes large.
This is because the particles are not uniformly dissolved at a finer level, and there is an insoluble matter at the finer level. Therefore, the Rth generated in the drying process of the solution casting is uneven and the solution is cast. It was inferred that variation occurred.
In the present invention, the surface quality of the film (foreign matter in the film, variation in Rth) can be improved without going through the complicated two steps (sieving and granulating) as in the conventional method.

The cellulose acylate used in the method for preparing a cellulose acylate solution and the method for producing a cellulose acylate film of the present invention is preferably used in the form of particles, and the powder characteristics (repose angle, bulk density (loose bulk density) of the particles) ), The mass ratio of particles having an angle of repose of 22 ° to 43 °, a bulk density of 0.30 g / cm ^{3 to} 0.75 g / cm ³ and a particle size of 1.7 mm or less is 3% or less. The repose angle is 25 degrees or more and 42 degrees or less, and the mass ratio of particles having a bulk density of 0.30 g / cm ³ or more and 0.65 g / cm ³ and a particle diameter of 1.7 mm or more is 2.0% or less. More preferably, the repose angle is 28 ° or more and 40 ° or less, the bulk density is 0.30 g / cm ³ or more and 0.50 g / cm ³ and the mass ratio of particles having a particle size of 1.7 mm or less is 1.0% or less. In It is most preferable.
Among the above, the angle of repose and the bulk density are characteristics required for imparting production suitability for transportability in a particle production machine, and the mass ratio of particles having a particle size larger than 1.7 mm is a finished film. This is a characteristic required for improving the surface quality (foreign matter in the film, variation in Rth).

Furthermore, in order to improve the surface quality of the film in particular, the cell source acylate particles to be used have an acyl group substitution degree DS2 of the hydroxyl group at the 2-position of the glucose unit, an acyl group substitution degree DS3 of the hydroxyl group at the 3-position, and a hydroxyl group substitution at the 6-position. It is preferable that at least one of the following formulas (I) and (II) is satisfied during the acyl group substitution degree DS6, and it is more preferable that both the following formulas (I) and (II) are satisfied.
Formula (I): 2.0 ≦ DS2 + DS3 + DS6 ≦ 3.0
Formula (II): DS6 / (DS2 + DS3 + DS6) ≧ 0.315

90% by mass or more of the particles to be used preferably have a particle diameter of 0.10 to 1.20 mm. Further, 70% by mass or more of the particles to be used preferably have a particle size of 0.85 mm or less, more preferably 0.10 to 0.85 mm or less, and most preferably 0.21 to 0.85 mm. It is preferable to have.
In order to obtain particles having a particle size in the range of 0.10 mm to 1.20 mm, for example, a product obtained by synthesis can be easily obtained using a sieve having an opening of 0.10 mm and 1.2 mm.

  The particle size can be measured by sieving. For example, a particle size of 0.10 mm to 1.20 mm means a particle having an opening of 1.20 mm and cannot pass through a sieve of 0.10 mm. The sieving was performed using a sonic sieving measuring device RPS-85P manufactured by Seishin Company, with a vibration level of 3, a vibration time of 3 minutes, and a pulse interval of 1 second.

The other powder characteristics of the cellulose acylate particles used in the present invention are as follows: the compacted bulk density is 0.42 g / cm ³ or more and 0.85 g / cm ³ or less, the degree of compression is 5% or more and 25% or less, and the collapse angle is 21 degrees or more and 42. It is preferable to set the physical properties at a degree of 3 ° or less, a difference angle of −3 ° to 5 °, and a dispersity of 5% to 25%.
These characteristics are measured using a multi-tester MT-1001 manufactured by Seishin Corporation. The measurement was performed at least 10 times, and the average value was used. Details of the measurement are described in the website of Seishin company http://www.betterseishin.co.jp or the catalog of the multi tester MT-1001.

  In order to obtain the powder characteristics of the cellulose acylate particles of the present invention, the solid content concentration of the cellulose acylate in the solution system and the amount of the neutralizing solution to be added during the aging step and neutralization step after the acetylation step It is obtained by changing the balance. For example, if the solid content concentration during aging is low and a large amount of neutralized solution is added, a product with a low bulk density can be obtained. Conversely, if the solid content concentration during aging is high and a small amount of neutralized solution is added, the bulk density is low. A big one is obtained.

  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 within the above range, cellulose acylate that is preferable in terms of molecular weight distribution (uniform molecular weight distribution) can be synthesized. When used in the production of cellulose acylate, 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, the cellulose acylate contains water and generally has a water content of 2.5 to 5% by mass. In order to make this moisture content, it is preferable to dry, and the method will not be specifically limited if it becomes the target moisture content.
The raw material cotton of cellulose acylate and the synthesis method thereof are the raw material cotton described in detail on pages 7 to 12 of the Japan Institute of Invention Technology (Publication No. 2001-1745, published on March 15, 2001, Japan Society of 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]
In the present invention, examples of the additive that can be used in the cellulose acylate solution include a plasticizer, an ultraviolet absorber, a deterioration inhibitor, a retardation (optical anisotropy) developer, fine particles, a peeling accelerator, and red. An external absorbent etc. can be mentioned. In the present invention, it is preferable to use at least one 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 having melting points 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-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 the 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 And 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 light having a wavelength of 370 nm or less, and has little absorption of visible light having a wavelength of 400 nm or more from the viewpoint of liquid crystal display properties. Particularly preferred ultraviolet absorbers are the benzotriazole compounds, benzophenone compounds, and salicylic acid ester compounds mentioned above. Among these, a benzotriazole-based compound is preferable because unnecessary coloring with respect to the cellulose ester is small.

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

  The addition amount of the ultraviolet absorber is preferably 0.001 to 5% by mass with respect to the solid content of cellulose acylate from the viewpoint of the addition effect and suppressing the bleeding out of the ultraviolet absorber to the film surface. The mass% is more preferable.

  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 preventing agent prevents 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. Specific examples of the plasticizer include triphenyl phosphate (TPP), tricresyl phosphate (TCP), cresyl diphenyl phosphate, octyl diphenyl phosphate, diphenyl biphenyl phosphate, 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, triacetin, Ribuchirin, butyl phthalyl butyl glycolate, ethyl phthalyl ethyl glycolate, methyl phthalyl ethyl glycolate, butyl phthalyl butyl glycolate may be preferably mentioned. Further, preferred plasticizers include (di) pentaerythritol esters, glycerol esters, and diglycerol esters.

  Examples of the peeling accelerator include citric acid ethyl esters. Furthermore, as an infrared absorber, it describes in Unexamined-Japanese-Patent No. 2001-194522, for example.

  The timing of adding these additives may be added at any stage in the dope preparation process, but may be performed by adding a process of adding additives as 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, although it describes in Unexamined-Japanese-Patent No. 2001-151902 etc., these are techniques conventionally known.

  The glass transition point Tg of the cellulose acylate film of the present invention is preferably 70 to 180 ° C, more preferably 100 to 170 ° C, and more preferably 120 ° C to 160 ° C. The glass transition point Tg can be measured with a dynamic viscoelasticity measuring device (Vibron: DVA-225 (ITG Measurement Control Co., Ltd.)). The glass transition point can also be adjusted to the above range by appropriately selecting the type and amount of plasticizer. The cellulose acylate film of the present invention preferably has a glass transition point Tg within the above range from the viewpoint of process suitability for polarizing plate processing and liquid crystal display device assembly.

  Furthermore, about an additive, what is described in detail after 16 pages of invention association public technical bulletins (public technical number 2001-1745, March 15, 2001 issue, invention association) can be used suitably.

When the molecular weight distribution (Mw / Mn) is less than 2.0, the mechanical properties of the film are lowered, stretching unevenness is likely to occur, and the flatness of the film is lowered. When the molecular weight distribution exceeds 3.4, the dope viscosity becomes high, casting stripes and the like are easily generated, and the surface state is deteriorated or the peelability is deteriorated. The molecular weight distribution Mw / Mn is preferably 2.0 to 3.4, more preferably 2.2 to 3.4, and even more preferably 2.4 to 3.4.
Moreover, even if it is comparatively smaller than the molecular weight of a normal cellulose acylate film by raising the ratio of the substitution degree of the acyl group at the 6-position in the total substitution degree, the mass average molecular weight is due to the molecular weight being lowered. No decrease in mechanical strength (elastic modulus, elongation at break, strength at break, etc.) is observed. The range of Mw is preferably 70,000 to 300,000, more preferably 80,000 to 280,000, and even more preferably 100,000 to 260,000.

[Retardation expression agent]
In the present invention, in order to express a preferable retardation value, it is preferable to use at least one retardation developer.
Examples of the retardation enhancer that can be used in the present invention include those composed of rod-like 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 preferably 0.5 to 20 parts by mass with respect to 100 parts by mass of the polymer component containing cellulose acylate. Further preferred.
The discotic retardation enhancer is preferably used in a range of 0.05 to 20 parts by mass, and in a range of 0.1 to 10 parts by mass with respect to 100 parts by mass of the polymer component containing the cellulose acylate. It is more preferable to use it, it is more preferable to use it in the range of 0.2 to 5 parts by mass, and it is most preferable to use it in the range of 0.5 to 2 parts by mass.
Since the discotic compound is superior to the rod-like compound in Rth retardation expression, it is preferably used when a particularly large Rth retardation is required.
In the present invention, two or more types of 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-A-2001-166144 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, further preferably 2 to 8, and most preferably 2 to 6. preferable.
The bond relationship between two aromatic rings can be classified into (a) a condensed ring, (b) a direct bond with a single bond, and (c) a bond through a linking group (for aromatic rings). , Spiro bonds cannot be formed). The connection relationship may be any of (a) to (c).

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

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

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

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

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

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

The alkylthio group preferably has 1 to 12 carbon atoms. Examples of the alkylthio group include a methylthio group, an ethylthio group, and an octylthio group.
The alkylsulfonyl group preferably has 1 to 8 carbon atoms. Examples of the alkylsulfonyl group include a methanesulfonyl group and an ethanesulfonyl group.
The number of carbon atoms in the aliphatic amide group is preferably 1-10. Examples of the aliphatic amide group include an acetamide group.
The number of carbon atoms of the aliphatic sulfonamide group is preferably 1-8. Examples of the aliphatic sulfonamido group include a methanesulfonamido group, a butanesulfonamido group, and an n-octanesulfonamido group.
The number of carbon atoms of the aliphatic substituted amino group is preferably 1-10. Examples of the aliphatic substituted amino group include a dimethylamino group, a diethylamino group, and a 2-carboxyethylamino group.
The number of carbon atoms in the aliphatic substituted carbamoyl group is preferably 2-10. Examples of the aliphatic substituted carbamoyl group include a methylcarbamoyl group and a diethylcarbamoyl group.
The number of carbon atoms in the aliphatic substituted sulfamoyl group is preferably 1-8. Examples of the aliphatic substituted sulfamoyl group include a methylsulfamoyl group and a diethylsulfamoyl group.
The number of carbon atoms in the aliphatic substituted ureido group is preferably 2-10. Examples of the aliphatic substituted ureido group include a methylureido group.
Examples of the non-aromatic heterocyclic group include a piperidino group and a morpholino group.
The molecular weight of the 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 can be performed using molecular orbital calculation software (for example, WinMOPAC2000, manufactured by Fujitsu Limited) to obtain a molecular structure that minimizes the heat of formation of a compound. The molecular structure being linear means that in the thermodynamically most stable structure obtained by calculation as described above, the angle of the main chain constituting the molecular structure is 140 degrees or more.

As the rod-shaped compound, those having at least two aromatic rings are preferable, and as the rod-shaped compound having at least two aromatic rings, a compound represented by the following general formula (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 (for example, methyl Amino group, ethylamino group, butylamino group, dimethylamino group), nitro group, sulfo group, carbamoyl group, alkylcarbamoyl group (for example, N-methylcarbamoyl group, N-ethylcarbamoyl group, N, N-dimethylcarbamoyl group) ), Sulfamoyl group, alkylsulfamoyl group (for example, N-methylsulfamoyl group, N-ethylsulfamoyl group, N, N-dimethylsulfamoyl group), ureido group, alkylureido group (for example, N -Methylureido group, N, N-dimethylureido group, N, N, N'-trimethylureido group), An alkyl group (for example, methyl group, ethyl group, propyl group, butyl group, pentyl group, heptyl group, octyl group, isopropyl group, s-butyl group, tert-amyl group, cyclohexyl group, cyclopentyl group), alkenyl group (for example, , Vinyl group, allyl group, hexenyl group), alkynyl group (for example, ethynyl group, butynyl group), acyl group (for example, formyl group, acetyl group, butyryl group, hexanoyl group, lauryl group), acyloxy group (for example, acetoxy group) Group, butyryloxy group, hexanoyloxy group, lauryloxy group), alkoxy group (for example, methoxy group, ethoxy group, propoxy group, butoxy group, pentyloxy group, heptyloxy group, octyloxy group), aryloxy group (for example, , Phenoxy group), alkoxycarbonyl group For example, methoxycarbonyl group, ethoxycarbonyl group, propoxycarbonyl group, butoxycarbonyl group, pentyloxycarbonyl group, heptyloxycarbonyl group), aryloxycarbonyl group (for example, phenoxycarbonyl group), alkoxycarbonylamino group (for example, butoxycarbonyl group) Amino group, hexyloxycarbonylamino group), alkylthio group (for example, methylthio group, ethylthio group, propylthio group, butylthio group, pentylthio group, heptylthio group, octylthio group), arylthio group (for example, phenylthio group), alkylsulfonyl group ( For example, methylsulfonyl group, ethylsulfonyl group, propylsulfonyl group, butylsulfonyl group, pentylsulfonyl group, heptylsulfonyl group, octylsulfo group Le group), an amido group (e.g., acetamido group, butylamide group, hexylamide group, laurylamide group) and a non-aromatic Hajime Tamaki (e.g., morpholyl group, include pyrazinyl group).

Substituents for substituted aryl groups and substituted aromatic heterocyclic groups include halogen atoms, cyano groups, carboxyl groups, hydroxyl groups, amino groups, alkylamino groups, acyl groups, acyloxy groups, amide groups, alkoxycarbonyl groups, alkoxy groups. 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 alkyl moieties and substituents of alkyl groups 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 is a divalent linking group selected from an alkylene group, an alkenylene group, an alkynylene group, an arylene group, —O—, —CO—, and a combination thereof.
The alkylene group may have a cyclic structure. As the cyclic alkylene group, cyclohexylene is preferable, and 1,4-cyclohexylene is particularly preferable. As the chain alkylene group, a linear alkylene group is more preferable than a branched alkylene group.
The 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 alkynylene group preferably have a chain structure rather than a cyclic structure, and more preferably have a linear structure rather than a branched chain structure.
The alkenylene group and the alkynylene group preferably have 2 to 10 carbon atoms, more preferably 2 to 8, more preferably 2 to 6, still more preferably 2 to 4, and most preferably 2. (Vinylene or ethynylene).
The arylene group preferably has 6 to 20 carbon atoms, more preferably 6 to 16, and still more preferably 6 to 12.

In the molecular structure of the general formula (1), the angle formed by Ar1 and Ar2 across L1 is preferably 140 degrees or more.
As the rod-like compound, a compound represented by the following formula (2) is more preferable.
General 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), L2 and L3 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) are shown below.

  Specific examples (1) to (34), (41), and (42) have two asymmetric carbon atoms at the 1-position and the 4-position of the cyclohexane ring. However, since the specific examples (1), (4) to (34), (41), and (42) have a symmetrical meso type molecular structure, there are no optical isomers (optical activity), and geometric isomers (trans Type and cis type). The trans type (1-trans) and cis type (1-cis) of specific example (1) are shown below.

As described above, the rod-like compound preferably has a linear molecular structure. Therefore, the trans type is preferable to the cis type.
Specific examples (2) and (3) have optical isomers (a total of four isomers) in addition to geometric isomers. As for geometric isomers, the trans type is similarly preferable to the cis type. The optical isomer is not particularly superior or inferior, and may be D, L, or a racemate.
In specific examples (43) to (45), the central vinylene bond includes a trans type and a cis type. For the same reason as described above, the trans type is preferable to the cis type.

As the rod-like compound, a compound represented by the following general formula (3) is also preferable.
General formula (3)

(Wherein R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁹ and R ¹⁰ each independently represents a hydrogen atom or a substituent, and R ¹ , R ² , R ³ , R ⁴ and R ⁵ each represents an electron donating group, R ⁸ represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, or an alkynyl group having 2 to 6 carbon atoms. Group, aryl group having 6 to 12 carbon atoms, alkoxy group having 1 to 12 carbon atoms, aryloxy group having 6 to 12 carbon atoms, alkoxycarbonyl group having 2 to 12 carbon atoms, acylamino group having 2 to 12 carbon atoms, cyano Represents a group or a halogen atom.)
Specific examples of the compound represented by the general formula (3) are given below.

Two or more rod-shaped compounds having a maximum absorption wavelength (λmax) shorter than 250 nm in the ultraviolet absorption spectrum of the solution may be used in combination.
The rod-like compound can be synthesized by a method described in the literature. References include Mol. Cryst. Liq. Cryst., 53, 229 (1979), 89, 93 (1982), 145, 111 (1987), 170, 43 Page (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 from the viewpoint of low turbidity, and silicon dioxide is particularly preferable. The fine particles of silicon dioxide preferably have a primary average particle diameter of 20 nm or less and an apparent specific gravity of 70 g / 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.
When the silicon dioxide fine particles are used, the amount used is preferably 0.01 to 0.3 parts by mass with respect to 100 parts by mass of the polymer component containing cellulose acylate.

These fine particles usually form secondary particles having an average particle diameter of 0.1 to 3.0 μm, 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 diameter is preferably 0.2 μm to 1.5 μm, more preferably 0.4 μm to 1.2 μm, and most preferably 0.6 μm to 1.1 μm. If the secondary average particle diameter is in the above range, the effect of preventing squeaking is sufficiently exhibited and the haze is small.
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 diameter in the present invention, several methods are conceivable when preparing a fine particle dispersion. For example, a method of preparing a fine particle dispersion in which a solvent and fine particles are mixed with stirring in advance, adding this fine particle dispersion to a small amount of cellulose acylate solution separately prepared, stirring and dissolving, and further mixing with the main cellulose acylate dope solution There is. This method is a preferable preparation method in that the dispersibility of the silicon dioxide fine particles is good and the silicon dioxide fine particles are more difficult to reaggregate. In addition, after adding a small amount of cellulose ester to the solvent and dissolving with stirring, add the fine particles to this and disperse with a disperser to make this fine particle additive solution, and mix this fine particle additive solution with the dope solution using an in-line mixer. There is also a way to do it. Although this invention is not limited to these methods, 5-30 mass% is preferable, as for the density | concentration of silicon dioxide when silicon dioxide microparticles | fine-particles are mixed and disperse | distributed with a solvent etc., 10-25 mass% is more preferable, 15-20 Mass% is most preferred. A higher dispersion concentration is preferable because the liquid turbidity with respect to the added amount is lowered, and haze and aggregates are improved. The addition amount of the matting agent in the final cellulose acylate dope solution is preferably 0.01 to 1.0 g, more preferably 0.03 to 0.3 g, and most preferably 0.08 to 0.16 g per 1 m2. preferable.

  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. The main solvent refers to a solvent having the highest constituent ratio when there is at least one solvent constituting the cellulose acylate solution. In the present invention, the type of the chlorinated organic solvent is not particularly limited as long as the object can be achieved within the range in which cellulose acylate can be dissolved and 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% by mass of dichloromethane in the total amount of the organic solvent. Other organic solvents used in combination with the chlorinated organic solvent in the present invention 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 the 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 among them, saturated aliphatic hydrocarbon is preferable. The hydroxyl group of the alcohol may be any of primary to tertiary. Examples of the alcohol include methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, tert-butanol, 1-pentanol, 2-methyl-2-butanol and cyclohexanol. As the alcohol, fluorine-based alcohol is also used. Examples thereof include 2-fluoroethanol, 2,2,2-trifluoroethanol, 2,2,3,3-tetrafluoro-1-propanol and the like. Furthermore, the hydrocarbon may be linear, branched or cyclic. Either aromatic hydrocarbons or aliphatic hydrocarbons can be used. The aliphatic hydrocarbon may be saturated or unsaturated. Examples of hydrocarbons include cyclohexane, hexane, benzene, toluene and xylene.
Examples of combinations of chlorinated organic solvents and other organic solvents include the following compositions, but are not limited thereto.

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

[Non-chlorine solvents]
Next, a non-chlorine organic solvent that is preferably used in preparing 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 as long as the cellulose acylate can be dissolved and cast and formed into a film. The non-chlorine organic solvent used in the present invention is preferably a solvent selected from esters, ketones and ethers having 3 to 12 carbon atoms. Esters, ketones and ethers may have a cyclic structure. A compound having two or more functional groups of esters, ketones and ethers (that is, —O—, —CO— and —COO—) can also be used as a main solvent, such as an alcoholic hydroxyl group. 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 not be provided. The first solvent is more preferably methyl acetate, acetone, methyl formate, ethyl formate, or a mixture thereof, and the second solvent is preferably methyl ethyl ketone, cyclopentanone, cyclohexanone, 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, tert-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 more detail on pages 12 to 16 of the Japan Society for Invention and Innovation (Publication No. 2001-1745, published on March 15, 2001, Japan Institute of Invention). ing. 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, part by mass) ・ Methyl acetate / acetone / ethanol / butanol (82/10/4/4, part by mass) ・ Methyl acetate / acetone / ethanol / Butanol (80/10/4/6, part by mass), methyl acetate / methyl ethyl ketone / methanol / butanol (80/10/5/5, part by mass),
-Methyl acetate / acetone / methyl ethyl ketone / ethanol / isopropanol (75/10/10/5/7, parts by mass)
Methyl acetate / cyclopentanone / methanol / isopropanol (80/10/5/8, parts by mass),
・ Methyl acetate / acetone / butanol (85/5/5, part by mass),
Methyl acetate / cyclopentanone / acetone / methanol / butanol (60/15/15/5/6, parts by mass),
-Methyl acetate / cyclohexanone / methanol / hexane (70/20/5/5, parts by mass)
Methyl acetate / methyl ethyl ketone / acetone / methanol / ethanol (50/20/20/5/5, parts by mass),
Methyl acetate / 1,3-dioxolane / methanol / ethanol (70/20/5/5, parts by mass),
Methyl acetate / dioxane / acetone / methanol / ethanol (60/20/10/5/5, parts by mass),
Methyl acetate / acetone / cyclopentanone / ethanol / isobutanol / cyclohexane (65/10/10/5/5/5, parts by mass),
Methyl formate / methyl ethyl ketone / acetone / methanol / ethanol (50/20/20/5/5, parts by mass),
-Methyl formate / acetone / ethyl acetate / ethanol / butanol / hexane (65/10/10/5/5/5, parts by mass)
Acetone / methyl acetoacetate / methanol / ethanol (65/20/10/5, parts by mass)
Acetone / cyclopentanone / ethanol / butanol (65/20/10/5, parts by mass)
Acetone / 1,3-dioxolane / ethanol / butanol (65/20/10/5, parts by mass)
1,3-dioxolane / cyclohexanone / methyl ethyl ketone / methanol / butanol (55/20/10/5/5/5, parts by mass)
And so on.

Furthermore, the 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) and adding 2 parts by weight of butanol after filtration and concentration. Methyl acetate / acetone / ethanol / Butanol (84/10/4/2, parts by mass) A cellulose acylate solution is prepared, and after filtration and concentration, 4 parts by mass of butanol is additionally added.
A method in which a cellulose acylate solution is prepared with methyl acetate / acetone / ethanol (84/10/6, parts by mass), and 5 parts by weight of butanol is additionally added after filtration and concentration.
In addition to the non-chlorine organic solvent of the present invention, the dope used in the present invention may contain dichloromethane in an amount of 10% by mass or less of the total organic solvent amount of the present invention.

[Cellulose acylate solution properties]
The cellulose acylate solution is preferably a solution in which cellulose acylate solids are dissolved in the organic solvent at a concentration of 10 to 30% by mass in terms of suitability for film casting, and more preferably 13 to 27% by mass. %, Particularly preferably 15 to 25% by mass. The method for carrying out the cellulose acylate at these concentrations may be carried out so that the cellulose acylate has 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, various additives may be added to obtain a predetermined low-concentration cellulose acylate solution, and any method will result in the cellulose acylate solution concentration of the present invention. If implemented, there is no particular problem.

Next, in this invention, it is preferable that the aggregate molecular weight of the cellulose acylate in the diluted solution which made the cellulose acylate solution 0.1-5 mass% with the organic solvent of the same composition is 150,000-15 million. 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 that case, it is preferable to dissolve so that the inertial square radius required at the same time 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 to + 4 × 10 ^−4, and more preferably, the second virial coefficient is −2 × 10 ⁻⁴ to + 2 × 10 ^−4. It is.

Here, the definition of the associated molecular weight, the 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 dried at 120 ° C. for 2 hours is used at 25 ° C. and 10% relative humidity. 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, the solution and the solvent are filtered through a 0.2 μm Teflon filter. Then, static light scattering of the filtered solution is measured at 10 ° intervals from 30 ° to 140 ° at 25 ° C. using a light scattering measuring device (DLS-700 manufactured by Otsuka Electronics Co., Ltd.). The obtained data is analyzed by the BERRY plot method. 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 concentration gradient (dn / dc) uses the differential refractometer (Otsuka Electronics Co., Ltd. DRM-1021). Measure 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. With respect to these, for example, JP-A-5-163301, JP-A-61-106628, JP-A-58-127737, JP-A-9-95544, JP-A-10-95854, JP-A-10-45950, JP 2000-53784, JP 11-322946, JP 11-322947, JP 2-276830, JP 2000-273239, JP 11-71463, JP 04-259511, Special JP-A 2000-273184, JP-A-11-323017, JP-A-11-302388, etc. describe methods for preparing a cellulose acylate solution.
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 methods, particularly for non-chlorinated solvent systems, are described in detail on pages 22 to 25 of the Japan Institute of Invention and Technology (Publication No. 2001-1745, published on March 15, 2001, Japan Institute of Invention). Will be implemented. Further, the cellulose acylate dope solution of the present invention is usually subjected to solution concentration and filtration. Similarly, the technical report of the Japan Society of Invention (Publication No. 2001-1745, published on March 15, 2001, Japan Society of Invention), page 25. Are 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 having a diameter of 4 cm / 2 ° (both manufactured by TA Instruments). Measurement conditions are Oscillation Step / Temperature Ramp, measured by changing the range from 40 ° C to -10 ° C at 2 ° C / min. Static non-Newtonian viscosity (Pa · s) at 40 ° C and storage modulus at -5 ° C Find (Pa). 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 Pa. 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 cylindrical body and the rotation trajectory of the outer periphery of the rotating blade rotating in the circumferential direction, and the temperature between the solution and the solution. A method of 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 from 0.1 to 10 mm, more preferably from 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 once stored in a storage kettle, and the foam contained in the dope is defoamed for final preparation. The dope is fed from the dope discharge port to the pressure die through a pressure metering gear pump capable of delivering a constant amount of liquid with high accuracy, for example, by the number of rotations, and the dope is run endlessly from the die (slit) of the pressure die. At the peeling point where the metal support is cast almost uniformly on the metal support, and the raw dry dope film (also referred to as web) has a volatile content ratio with respect to the solid content in the web of 70% by mass to 30% by mass. %, Preferably 68% to 35% by weight, and more preferably 65% to 40% by weight, from the metal support. The 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. The atmospheric temperature difference in each step such as drying and stretching performed in the step in which the film (web) is conveyed in a state where the volatile component ratio in the film is 70% by mass to 30% by mass is within 50 ° C., preferably 0 to 40 ° C., more preferably 0 to 35 ° C. By making the atmospheric temperature difference in each step performed in the step of transporting the volatile component in the film in a state of 70% by mass to 30% by mass within 50 ° C., drying unevenness including the drying history of the web is caused. This reduces the stretching unevenness and the optical property unevenness.
The volatile component referred to herein is defined as the mass of solvent present in the film / the mass of solid content present in the film.
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, when the cellulose acylate solution (dope) prepared is produced by a solvent casting method, a dope is cast on a drum or a band, and a 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- and low-viscosity cellulose acylate solutions are simultaneously extruded. A casting method may be used. Furthermore, it is also a preferred embodiment 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. Further, the cellulose acylate solution may be cast simultaneously with other functional layers (for example, an adhesive layer, a dye layer, an antistatic layer, an antihalation layer, a UV absorbing layer, a polarizing film).

  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 a concentrated cellulose acylate solution can be used to 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 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 film thickness of the dope once cast on the metal support is adjusted with a blade. 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 for 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 are installed, the dope amount 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 a method of 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 used. Is preferred. This is not the case when the casting dope is cooled and peeled off without drying.

[Stretching treatment]
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. For example, JP-A-62-115035, JP-A-4-152125, JP-A-4-284221, JP-A-4-298310, and JP-A-11 -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 ± 20 ° C. sandwiching the glass transition temperature of the film. If the film is stretched at a temperature extremely lower than the glass transition temperature, it tends to break and cannot exhibit desired optical properties. In addition, when stretching at a temperature extremely higher than the glass transition temperature, it is not possible to fix the orientation by relaxing with the heat during stretching before the molecularly oriented material by stretching is heat-set. Becomes worse.
The stretching of the film may be uniaxial stretching (fixed width, free width) only in the longitudinal or lateral direction, or simultaneous or sequential biaxial stretching. Stretching is performed by 10 to 200%. The stretching is preferably 12 to 100%, particularly preferably 15 to 80%. 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. Therefore, it is preferable to stretch more in the width direction. 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, stretching may be performed in a state including the residual solvent amount, and the residual solvent amount (residual solvent amount / (residual solvent amount + solid content amount)) may be preferably 2 to 50%.

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, still more preferably in the range of 30 to 180 μm. Particularly preferably, it is in the range of 40 to 180 μm, particularly preferably 40 to 150 μm. Moreover, when using especially for VA liquid crystal display devices, it is preferable that it is 40-110 micrometers.
Although the film thickness of the film is 110 to 180 μm, the drying load during casting film formation increases, but the size of the optical characteristics is proportional to the film thickness, so the desired optical characteristics can be increased by increasing the film thickness. Can be achieved. In addition, since the moisture permeability also decreases in inverse proportion to the film thickness, increasing the film thickness reduces the moisture permeability and makes it more difficult for water to pass through. This is advantageous in a polarizing plate durability test for 500 hours at 60 ° C. and 90% relative humidity.
The film thickness may be adjusted by adjusting the solid content concentration contained in the dope, the slit gap of the die base, the extrusion pressure from the die, the metal support speed, and the like so as to obtain a desired thickness. The width of the cellulose acylate film obtained as described above is preferably 0.5 to 3 m, more preferably 0.6 to 2.5 m, still more preferably 0.8 to 2.2 m. The length is preferably 100 to 10,000 m per roll, more preferably 500 to 7000 m, and still more preferably 1000 to 6000 m. When winding, 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.

[Optical properties of cellulose acylate film]
The optical properties of the cellulose acylate film of the present invention are such that the Re retardation value and the Rth retardation value satisfy the following formulas (IX) and (X), respectively, for liquid crystal display devices, particularly VA mode liquid crystal display devices. It is preferable for widening the corner.
Formula (IX): 30 nm ≦ Re (590) ≦ 200 nm
Formula (X): 70 nm ≦ Rth (590) ≦ 400 nm
[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. ]
More preferably, the Re letter value satisfies the following formula (XI).
Formula (XI): 40 nm ≦ Re (590) ≦ 100 nm
The cellulose acylate film of the present invention is an optical biaxial film and preferably satisfies the following formula (XIV) because the viewing angle of the VA mode liquid crystal display device can be particularly widened.
Formula (XIV): 120 nm ≦ Rth (590) ≦ 300 nm
In the cellulose acylate film of the present invention, Re (590) and Rth (590) at 25 ° C. and a relative humidity of 60% preferably satisfy the following formulas (A) to (C).
Formula (A) 40 ≦ Re (590) ≦ 145
Formula (B) Rth (590) = a−5.9Re (590)
Formula (C) 520 ≦ a ≦ 670
[In the formula, Re (590) is the front retardation value (unit: nm) at a wavelength of 590 nm, and Rth (590) is the retardation value (unit: nm) in the film thickness direction at a wavelength of 590 nm. Further, a is an adjustment factor (unit: nm) of optical characteristics. ]
a is an adjustment coefficient of Re and Rth, more preferably 590 ≦ a ≦ 660, and further preferably 600 ≦ a ≦ 650. The presence of a in the above range is preferable in terms of widening the viewing angle characteristics of the vertical alignment type liquid crystal display device.

  In addition, the cellulose acylate film of the present invention has a difference ΔRe (= Re (10% RH) −Re () between Re at 25 ° C./relative humidity 10% and Re at 25 ° C./relative humidity 80% measured at a wavelength of 590 nm. 80% RH)) is 0-10 nm, preferably 0-9 nm, more preferably 0-8 nm. The difference ΔRth (= Rth (10% RH) −Rth (80% RH)) between Rth at 25 ° C. and relative humidity of 10% measured at a wavelength of 590 nm and Rth at 25 ° C. and relative humidity of 80% is 0 to 30 nm. It is preferably 0 to 29 nm, more preferably 0 to 27 nm, which is preferable for reducing the change in color of the liquid crystal display device over time.

The film thickness distribution in the width direction of Re was sequentially sampled from the position of 2 cm (width direction) × 3 cm (width direction perpendicular) of the film in the width direction, from the position of the film edge 5 cm, Ten points were collected at equal intervals. The film thickness of each test piece (2 cm × 3 cm) was measured at a total of 9 points in the longitudinal and lateral directions in the plane of the film, and used as the film thickness of the sample.
When the film thickness distribution R is defined as R (%) = (Rmax−Rmin) / Rave × 100 when the maximum value, minimum value, and average value of the film thickness in the width direction are Rmax, Rmin, and Rave, respectively. These are preferably adjusted to 0 to 8%, more preferably adjusted to 0 to 7.8%, and further preferably adjusted to 0 to 7.6%. Since Re and Rth are values proportional to the film thickness, the smaller the film thickness distribution in the width direction of the film thickness, the smaller the variation in Re (590) and Rth (590).
The distribution of Re (590) and Rth (590) is caused by the above-described film thickness variation, or due to stretching unevenness, drying unevenness, etc., but this Re distribution (variation) is 5% or less. The Rth distribution is preferably adjusted to 10% or less. More preferably, the Re distribution is 4.8% or less, the Rth distribution is 9.8% or less, more preferably the Re distribution is 4.6% or less, and the Rth distribution is 9.6% or less. It is preferable.
The above film thickness distribution R, Re distribution, and Rth distribution are coefficients of variation (CV) measured at intervals of 1 cm in the width direction of the film, and are displayed using the film on a liquid crystal display device (particularly a VA liquid crystal display device). This is preferable because display unevenness is reduced.

In the present invention, the optical characteristics were measured by the following method.
In this specification, Re (λ) and Rth (λ) respectively represent front retardation and retardation in the film thickness direction at wavelength λ. Re (λ) is measured by making light having a wavelength of λ nm incident in the normal direction of the film in KOBRA 21ADH (manufactured by Oji Scientific Instruments). Rth (λ) is incident with light having a wavelength of λ nm from the direction inclined by + 40 ° with respect to the normal direction of the film with Re (λ) and the in-plane slow axis (determined by KOBRA · 21ADH) as the tilt axis The retardation value measured in this way, and the retardation value measured by making light of wavelength λ nm incident from a direction inclined −40 ° with respect to the film normal direction with the in-plane slow axis as the tilt axis KOBRA · 21ADH is calculated based on the retardation value measured in (1).
Here, as the assumed value of the average refractive index, the values in the polymer handbook (JOHN WILEY & SONS, INC) and catalogs of various optical films can be used. Those whose average refractive index is not known can be measured with an Abbe refractometer. The average refractive index values of the main optical films are exemplified below: cellulose acylate (1.48), cycloolefin polymer (1.52), polycarbonate (1.59), polymethyl methacrylate (1.49), Polystyrene (1.59). KOBRA 21ADH calculates nx, ny, and nz by inputting these assumed values of average refractive index and film thickness. Nz = (nx-nz) / (nx-ny) is further calculated from the calculated nx, ny, and nz.

  In the cellulose acylate film of the present invention, the color difference ΔE * ab before and after aging at 90 ° C. for 500 hours is preferably 0.8 or less, preferably 0.7 or less, The following is more preferable. The color difference between before and after aging at 140 ° C. for 24 hours is preferably 1.5 or less, more preferably 1.0 or less, and further preferably 0.5 or less. If the film is colored under an environmentally forced condition such as 90 ° C. for 500 hours or 140 ° C. for 24 hours, the optical compensation ability as a retardation film is lowered, which is not preferable in terms of appearance. The color difference was measured using UV3100 (manufactured by Shimadzu Corporation). The measurement is performed by adjusting the film to 25 ° C. and 60% relative humidity for 2 hours or more and then measuring the chromaticity in the CIEL * a * b * chromaticity coordinate space of the film before the thermo lapse of time. L0 *, a0 *, b0 *). Thereafter, the film alone was left in an air thermostat for a predetermined time. After the elapse of a predetermined time, the film is taken out from the thermostatic chamber, and after adjusting the humidity to 25 ° C. and a relative humidity of 60% for 2 hours, the chromaticity measurement of the chromaticity space is performed, and the chromaticity value (L1 *, a1 *, b1 *). From these, the color difference ΔE * ab = ((L0 * −L1 *) 2+ (a0 * −a1 *) 2+ (b0 * −b1 *) 2) ½ was obtained.

In the cellulose acylate film of the present invention, the equilibrium water content at 25 ° C. and 80% relative humidity is preferably 5.0% or less, more preferably 4.0% or less, and 3.2%. The following is more preferable, and it is preferable in order to reduce the color change with time of the liquid crystal display device.
The moisture content is measured by measuring the cellulose acylate film sample 7 mm × 35 mm of the present invention by the Karl Fischer method using a moisture measuring device and a sample drying apparatus (CA-03, VA-05, both Mitsubishi Chemical Corporation). . It is calculated by dividing the amount of water (g) by the sample mass (g).
In addition, the cellulose acylate film of the present invention has a liquid crystal display having a water vapor transmission rate of 400 g / m ² · 24 hr to 1800 g / m ² · 24 hr at 60 ° C., 95% relative humidity, and 24 hr (in terms of film thickness 80 μm). It is preferable in order to reduce the color change with time of the apparatus.
If the film thickness of the cellulose acylate film is thick, the moisture permeability becomes small, and if the film thickness is thin, the moisture permeability becomes large. The measured moisture permeability is converted with a reference film thickness of 80 μm. The converted value of moisture permeability is calculated by “80 μm converted moisture permeability = actually measured moisture permeability × actually 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 was measured by adjusting a viscoelasticity measuring apparatus (Vibron: DVA-) after conditioning the cellulose acylate film sample (unstretched) 5 mm × 30 mm of the present invention at 25 ° C. and 60% relative humidity for 2 hours or more. 225 (manufactured by IT Measurement Control Co., Ltd.) with a distance between grips of 20 mm, a temperature increase rate of 2 ° C./min, a measurement temperature range of 30 ° C. to 200 ° C., and a frequency of 1 Hz. When a temperature (° C.) is taken on the linear axis on the horizontal axis, a straight line 1 is drawn in the solid region to draw a sharp decrease in the storage elastic modulus seen when the storage elastic modulus transitions from the solid region to the glass transition region. The intersection of the straight line 1 and the straight line 2 when the straight line 2 is drawn in the transition region is a temperature at which the storage elastic modulus suddenly decreases and the film starts to soften when the temperature rises, and the temperature starts to move to the glass transition region. ,Glass-transition temperature And g (dynamic viscoelasticity).

  The elastic modulus was measured by conditioning a 10 mm × 150 mm dry film cellulose acylate film sample of the present invention at 25 ° C. and a relative humidity of 60% for 2 hours or more, and then using a tensile tester (Strograph-R2 (manufactured by Toyo Seiki Co., Ltd.). )), The distance between chucks was 100 mm, the temperature was 25 ° C., and the stretching speed was 10 mm / min.

Further, the cellulose acylate film of the present invention preferably has a haze of 0.01 to 2%. Here, the haze is measured as follows.
The cellulose acylate film sample 40 mm × 80 mm of the present invention is measured according to JIS K-6714 with a haze meter (HGM-2DP, Suga Test Instruments) at 25 ° C. and a relative humidity of 60%.
The dry cellulose acylate film of the present invention (a film having a volatile content of 1% by mass or less based on the solid content) is mixed with a good solvent (GS) and a poor solvent (PS) in a mixing ratio of 0.5 ≦ GS. When exposed to a mixed solvent (MS) vapor atmosphere mixed at /PS≦4.0 at room temperature for 45 minutes, the difference in film haze before and after exposure is 0.5% or less, preferably 0% Is 0.4%, more preferably 0% to 0.3%.
If the haze difference of the film before and after exposure is 0.5% or less, the film can be prevented from crying, and the crying property of low molecular additives in the film can be evaluated in advance at the laboratory level. Thus, the film can be stably produced without contaminating the manufacturing process. Moreover, the film excellent in the optical uniformity in the surface of a film can be obtained.

Examples of the good solvent (GS) for the cellulose acylate film include dichloromethane, methyl acetate, acetone and the like, preferably dichloromethane.
On the other hand, examples of the poor solvent (PS) for the cellulose acylate film include lower alcohols such as methanol, ethanol, n-butanol, etc., preferably methanol.

  Furthermore, in the cellulose acylate film of the present invention, it is preferable that the film is not whitened when the film is exposed for 4 hours at room temperature in a vapor atmosphere of a mixed solvent (MS) having a GS / PS ratio of 2. The degree of whitening can be measured with the aforementioned haze meter. The difference in film haze before and after exposure is 0.8% or less, preferably 0% to 0.6%, more preferably 0% to 0.5%. That is, the film has good compatibility with the cellulose acylate and the diffusion rate of the low molecular additive is slow (that is, the crying property is low (manufacturability is good)). Intermediate compatibility, intermediate diffusion rate of low molecular additives, intermediate degree of whitening, poor compatibility with polymers, low diffusion rate of low molecular additives (ie, crying ability) The worst (the poor production suitability) is the most whitened.

The cellulose acylate film of the present invention preferably has a mass change of 0 to 5% when allowed to stand for 48 hours under conditions of 80 ° C. and 90% relative humidity.
In addition, the cellulose acylate film of the present invention has a dimensional change when left for 24 hours under conditions of 60 ° C. and 95% relative humidity, and when left for 24 hours under conditions of 90 ° C. and 5% relative humidity. It is preferable that the dimensional change is -5% to 5%.

The photoelastic coefficient of the cellulose acylate film of the present invention is 50 × 10 ⁻¹³ cm ² / dyn (5 × 10 ⁻¹⁰ Pa ⁻¹ ) or less in order to reduce color change with time of the liquid crystal display device. Is preferable.
As a specific measuring method, a tensile stress is applied to the major axis direction of a 10 mm × 100 mm cellulose acylate film sample, and the retardation at that time is measured with an ellipsometer (M150, JASCO Corporation). The photoelastic coefficient is calculated from the amount of change in retardation with respect to.

[Polarizer]
Next, the polarizing plate of the present invention will be described.
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 of the present invention is used as at least one protective film. The other protective film may be the cellulose acylate film of the present invention or a normal cellulose acetate film. Examples of the polarizer 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 the cellulose acylate film of the present invention is used as a polarizing plate protective film, the method for producing the polarizing plate is not particularly limited, and can be produced 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 prepared 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 may further be configured by laminating a protective film on one surface of the polarizing plate and a separate film on 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 plate. Moreover, a separate film is used in order to cover the contact bonding layer bonded to a liquid crystal plate, and is used for the surface side which bonds a polarizing plate to a liquid crystal plate.

As shown in FIG. 1, the method of laminating the cellulose acylate film of the present invention to the polarizer is such that the transmission axis of the polarizer matches the slow axis of the cellulose acylate film of the present invention (TAC1 in the figure). It is preferable to bond together.
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 the polarizing plate crossed Nicole decreases, light leakage occurs, and when combined with a liquid crystal cell, a sufficient black level and contrast cannot be obtained, so the main refractive index of the cellulose acylate film of the present invention The deviation between the direction of nx and the direction of the transmission axis of the polarizing plate is preferably within 1 °, preferably within 0.5 °.
In the present invention, the single plate transmittance (TT), parallel transmittance (PT), and orthogonal transmittance (CT) of the polarizing plate were measured using UV3100PC (manufactured by Shimadzu Corporation). In the measurement, the measurement was performed in the range of 380 nm to 780 nm under the conditions of 25 ° C. and relative humidity 60%, and the average value of 10 measurements was used for each of the single plate, parallel and orthogonal transmittance. The polarizing plate durability test was performed as follows in two types of forms in which (1) only the polarizing plate and (2) the polarizing plate were bonded to glass via an adhesive. For the measurement of only the polarizing plate, two orthogonal and identical ones were prepared and measured so that the optical compensation film was sandwiched between the two polarizers. Two samples (approx. 5 cm × 5 cm) are prepared by attaching a polarizing plate on a glass so that the optical compensation film is on the glass side. In the single plate transmittance measurement, the film side of this sample was set with the light source facing the light source. Two samples were measured, and the average value was defined as the transmittance of the single plate. The preferable range of the polarization performance is 40.0 ≦ TT ≦ 45.0, 30.0 ≦ PT ≦ 40 in the order of single plate transmittance (TT), parallel transmittance (PT), and orthogonal transmittance (CT), respectively. 0.0, CT ≦ 2.0, and more preferable ranges are 40.2 ≦ TT ≦ 44.8, 32.2 ≦ PT ≦ 39.5, and CT ≦ 1.6, and a more preferable range is 41. 0.0 ≦ TT ≦ 44.6, 34 ≦ PT ≦ 39.1, and CT ≦ 1.3.
The degree of polarization P is calculated from these transmittances, and the greater the degree of polarization P is, the less light leaks when arranged in a cross, indicating that the performance of the polarizing plate is higher. The degree of polarization P is preferably 95.0% or more, more preferably 96.0% or more, and further preferably 97.0% or more.

In the polarizing plate of the present invention, T (380), T (410), and T (700) are at least one of the following formulas (e) to (g), where T (λ) is an orthogonal transmittance at a wavelength λ. It is preferable to satisfy one or more.
Formula (e) T (380) ≦ 2.0
Formula (f) T (410) ≦ 1.0
Formula (g) T (700) ≦ 0.5
More preferably, T (380) ≦ 1.95, T (410) ≦ 0.9, T (700) ≦ 0.49, and even more preferably T (380) ≦ 1.90, T (410) ≦ 0. .8, T (700) ≦ 0.48.

In the polarizing plate of the present invention, the amount of change ΔCT and the amount of polarization change ΔP of the orthogonal single plate when left standing at 60 ° C. and 95% relative humidity for 500 hours have the following mathematical formulas (j) and (k): It is preferable to satisfy at least one of the following.
Formula (j) −6.0 ≦ ΔCT ≦ 6.0
Formula (k) -10.0 ≦ ΔP ≦ 0.0
(However, the amount of change indicates the value obtained by subtracting the measured value before the test from the measured value after the test.)
More preferably, −5.8 ≦ ΔCT ≦ 5.8, −9.5 ≦ ΔP ≦ 0.0, and still more preferably −5.6 ≦ ΔCT ≦ 5.6, −9.0 ≦ ΔP ≦ 0.0. It is.
The polarizing plate of the present invention has an orthogonal single plate transmittance change ΔCT and a polarization degree change ΔP when left at 60 ° C. and a relative humidity of 90% for 500 hours with the following formulas (h) and (i): It is preferable to satisfy at least one of the following.
Formula (h) −3.0 ≦ ΔCT ≦ 3.0
Formula (i) −5.0 ≦ ΔP ≦ 0.0
The polarizing plate of the present invention has an orthogonal single plate transmittance change ΔCT and a polarization degree change ΔP of at least one of the following formulas (l) and (m) when left standing at 80 ° C. for 500 hours. It is preferable to satisfy.
Formula (l) −3.0 ≦ ΔCT ≦ 3.0
Formula (m) −2.0 ≦ ΔP ≦ 0.0
In the polarizing plate durability test, the amount of change is preferably smaller.

[surface treatment]
The cellulose acylate film of the present invention can achieve improved adhesion between the cellulose acylate film and each functional layer (for example, the undercoat layer and the back layer) by optionally performing a surface treatment. As the surface treatment, for example, glow discharge treatment, ultraviolet irradiation treatment, corona treatment, flame treatment, acid or alkali treatment can be used. The glow discharge treatment referred to here may be low-temperature plasma that occurs under a low pressure gas of 10-3 to 20 Torr, and plasma treatment under atmospheric pressure is also preferred. A plasma-excitable gas is a gas that is plasma-excited under the above conditions, and includes chlorofluorocarbons such as argon, helium, neon, krypton, xenon, nitrogen, carbon dioxide, tetrafluoromethane, and mixtures thereof. It is done. Details of these are described in detail on pages 30-32 of the Invention Association (Public Technical Bulletin No. 2001-1745, issued on March 15, 2001, Invention Association). 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, the alkali saponification treatment is particularly preferable, and it is extremely effective as the surface treatment of the cellulose acylate film.

  The alkali saponification treatment is preferably carried out by a method in which a cellulose acylate film is directly immersed in a saponification solution tank or a method in which a saponification solution is applied to a 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 without forming irregularities on the surface of the cellulose acylate film with the saponification solution solvent, It is preferable to select a solvent that keeps the surface state 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, and 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 to which the saponification solution is applied with water or acid, and then with water.

  In addition, the polarizing plate of the present invention is preferably one in which 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 liquid crystal cell of the polarizing plate. That is, as shown in FIG. 2, it is preferable to provide a functional film such as an antireflection layer on 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. It is preferable to provide at least one layer of a hard coat layer, an antiglare layer and an antireflection layer as the functional film. Each layer does not need to be provided as a separate layer. For example, the antireflection layer may function as an antireflection layer and an antiglare layer by providing the antireflection layer with a function as an antiglare layer.

[Antireflection layer]
In the present invention, at least the light scattering layer and the low refractive index layer are laminated in this order on the protective film, or the medium refractive index layer, the high refractive index layer, and the low refractive index layer are formed on the protective film. An antireflection layer formed by laminating in order is preferably used. Preferred examples thereof are described below.

A preferred example of an antireflection layer in which a light scattering layer and a low refractive index layer are provided on a protective film will be described.
It is preferable that mat particles are dispersed in the light scattering layer, 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. The refractive index of the low refractive index 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 in the range of the a * value −2 to 2, the b * value −3 to 3, and the 380 nm to 780 nm is 0. By being 5-0.99, the color of reflected light becomes neutral, which is preferable. Moreover, by setting the b * value of the transmitted light under the C light source to 0 to 3, the yellow color of white display when applied to a display device is reduced, which is preferable. 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 antireflection layer that can be used in the present invention preferably has, as its optical characteristics, a specular reflectance of 2.5% or less, a transmittance of 90% or more, and a 60 ° gloss of 70% or less. By doing in this way, reflection of external light can be suppressed and visibility improves. In particular, the specular reflectance is more preferably 1% or less, and most preferably 0.5% or less. Haze 20% to 50%, internal haze / total haze value 0.3 to 1, haze value after formation of low refractive index layer from haze value to light scattering layer within 15%, comb width at 0.5 mm Transmission image clarity 20% to 50%, vertical transmission light / transmittance ratio of 2 degrees from vertical to 1.5 to 5.0 prevents glare on high-definition LCD panels, characters, etc. Reduction of blur is achieved, which is preferable.

[Low refractive index layer]
The low refractive index layer in the antireflection layer in which at least a light scattering layer and a low refractive index layer are laminated in this order on the protective film will be described below.
The refractive index of the low refractive index layer 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 (XV) from the viewpoint of reducing the reflectance.
Formula (XV): (mλ / 4) × 0.7 <n1d1 <(mλ / 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 and is a value in the range of 500 to 550 nm.

The material for forming the low refractive index layer will be described below.
The low refractive index layer preferably contains a fluorine-containing polymer as a low refractive index binder. 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 sticker or memo, which is preferably measured by pulling in the -180 degree direction with a tensile tester. In this case, 500 gf (4.9 N) or less is preferable, 300 gf (2.94 N) or less is more preferable, and 100 gf (0.98 N) or less is most preferable. The sample shape in the tensile tester was a rectangular sample of 1 cm × 15 cm, the distance between chucks was 10 cm, and the chucking margin was 2.5 cm. Moreover, it is preferable that the surface hardness measured with a microhardness meter is high, so that scratches are less likely to occur, and the scratch hardness is preferably 0.3 GPa or more, more preferably 0.5 GPa or more. With a microhardness meter, the load and the depth of indentation (displacement) when the probe is pushed down to a certain depth (about 1 / 100,000 to 1 / 10th of the thickness of the object to be measured) The surface hardness (elastic modulus) is measured from the relationship.

  Examples of the fluorine-containing polymer used in the low refractive index layer include hydrolysis and dehydration condensate of perfluoroalkyl group-containing silane compounds (for example, (heptadecafluoro-1,1,2,2-tetrahydrodecyl) triethoxysilane). And a fluorine-containing copolymer having a fluorine-containing monomer unit and a structural unit for imparting crosslinking reactivity as structural components.

  Specific examples of the monomer that forms the fluorine-containing monomer unit that is a constituent of the fluorine-containing copolymer include, for example, fluoroolefins (for example, fluoroethylene, vinylidene fluoride, tetrafluoroethylene, perfluorooctylethylene, hexafluoropropylene, Perfluoro-2,2-dimethyl-1,3-dioxole, etc.), (meth) acrylic acid partial or fully fluorinated alkyl ester derivatives (for example, Biscoat 6FM (Osaka Organic Chemical) or M-2020 (Daikin)) Etc.), fully or partially fluorinated vinyl ethers, and the like, preferably perfluoroolefins, and particularly preferably hexafluoropropylene 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. The monomer that can be used in combination is not particularly limited. For example, olefins (ethylene, propylene, isoprene, vinyl chloride, vinylidene chloride, etc.), acrylic esters (methyl acrylate, methyl acrylate, ethyl acrylate, 2-acrylic acid 2- Ethyl hexyl), 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-cycl) 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 contributing to the film light diffusibility due to at least one of surface scattering and internal scattering and hard coat properties 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 or at least one atom selected from halogen atoms other than fluorine, sulfur atoms, phosphorus atoms, and nitrogen atoms. You can also choose.

  Examples of the monomer having two or more ethylenically unsaturated groups include esters of polyhydric alcohol and (meth) acrylic acid (for example, ethylene glycol di (meth) acrylate, butanediol di (meth) acrylate, hexanediol di ( (Meth) acrylate, 1,4-cyclohexanediacrylate, pentaerythritol tetra (meth) acrylate), pentaerythritol tri (meth) acrylate, trimethylolpropane tri (meth) acrylate, trimethylolethane tri (meth) acrylate, dipentaerythritol Tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, pentaerythritol hexa (meth) acrylate, 1,2,3 Cyclohexane tetramethacrylate, polyurethane polyacrylate, polyester polyacrylate), modified ethylene oxide, vinylbenzene and derivatives thereof (for example, 1,4-divinylbenzene, 4-vinylbenzoic acid-2-acryloylethyl ester, 1,4 -Divinylcyclohexanone), vinyl sulfone (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 these monomers having an ethylenically unsaturated group can be carried out by irradiation with ionizing radiation or heating in the presence of a photo radical initiator or a thermal radical initiator.
Accordingly, a coating liquid containing a monomer having an ethylenically unsaturated group, a photo radical initiator or a thermal radical initiator, mat particles and an inorganic filler is prepared, and the coating liquid is applied onto a protective film and then ionizing radiation or heat. 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 liquid containing a polyfunctional epoxy compound, a photoacid generator or a thermal acid generator, matte particles and an inorganic filler is prepared, and the coating liquid is applied onto 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 size 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 particles having a particle size of 20% or more than the average particle size are defined as coarse particles, the proportion of coarse particles is preferably 1% or less of the total number of particles, more preferably 0.1%. Or less, more preferably 0.01% or less. Matt particles having such a particle size distribution are obtained by classification after a normal synthesis reaction, and a matting agent having a more preferable distribution can be obtained by increasing the number of classifications or increasing the degree of classification.

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

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

  The bulk refractive index of the mixture of binder and inorganic filler in the light scattering layer is preferably 1.50 to 2.00, more preferably 1.51 to 1.80. In order to make the refractive index within the above range, the type 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 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 (for example, 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. The strength of the film 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.

[High refractive index layer and medium refractive index layer]
The layer having a high refractive index of the antireflection layer is composed of a cured film containing at least an inorganic compound fine particle having a high refractive index having an average particle diameter of 100 nm or less and a matrix binder.
Examples of the high refractive index inorganic compound fine particles include inorganic compound fine particles having a refractive index of 1.65 or more, preferably those having a refractive index of 1.9 or more. Examples thereof include fine particles such as oxides such as Ti, Zn, Sb, Sn, Zr, Ce, Ta, La, and In, and composite oxides containing these metal atoms.
In order to obtain fine particles having an average particle size of 100 nm or less, 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). No.-9908, anionic compound or organometallic coupling agent: JP-A No. 2001-310432, etc., and a core-shell structure with high refractive index particles as a core (for example, JP-A No. 2001-166104) ) And specific dispersants (for example, JP-A No. 11-153703, US Pat. No. 6,210,858B1, JP-A No. 2002-276069) and the like.
Examples of the material forming the matrix include conventionally known thermoplastic resins and curable resin films.
Further, a polyfunctional compound-containing composition containing two or more polymerizable groups of at least one of radically polymerizable and cationically polymerizable, an organometallic compound containing a hydrolyzable group, and a partial condensate-containing composition thereof At least one composition selected is preferred. For example, the composition as described in Unexamined-Japanese-Patent No. 2000-47004, 2001-315242, 2001-31871, 2001-296401 etc. is mentioned.
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]
Next, the low refractive index layer in the antireflection layer in which the middle refractive index layer, the high refractive index layer, and the low refractive index layer are laminated in this order on the protective film will be described.
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.
It is preferable to construct as the outermost layer having scratch resistance and antifouling property. As means for greatly improving the scratch resistance, it is effective to impart slipperiness to the surface, 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. 11-38202, and paragraph numbers of Japanese Patent Application Laid-Open No. 2001-40284. [0027] to [0028], compounds described in JP-A No. 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 (for example, 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 a fluorine-containing polymer having a crosslinking or polymerizable group and a siloxane polymer is performed by applying a coating composition for forming an outermost layer containing a polymerization initiator, a sensitizer and the like. It is preferable to form the low refractive index layer by light irradiation or heating simultaneously or 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. A low refractive index inorganic compound, organic fine particles described in paragraphs [0020] to [0038] of JP-A-11-3820), silane coupling agents, slip agents, surfactants, and the like.
When the low refractive index layer is located below the outermost layer, the low refractive index layer may be formed by a vapor phase method (vacuum deposition method, sputtering method, ion plating method, plasma CVD method, etc.). The coating method is preferable because it can be manufactured at a low cost.
The film thickness of the low refractive index layer is preferably 30 to 200 nm, more preferably 50 to 150 nm, and most preferably 60 to 120 nm.

[Hard coat layer]
The hard coat layer is provided on the surface of the protective film in order to impart physical strength to the protective film provided with the antireflection layer. In particular, it is preferably provided between the transparent support and the high refractive index layer. The hard coat layer is preferably formed by a crosslinking reaction or a polymerization reaction of the curable compound by at least one of light and heat. The curable functional group in the curable compound is preferably a photopolymerizable functional group. Also preferred are hydrolyzable functional group-containing organometallic compounds and organoalkoxysilyl compounds.
Specific examples of these compounds are the same as those exemplified for the high refractive index layer. Specific examples of the composition of the hard coat layer include those described in JP-A Nos. 2002-144913, 2000-9908, and WO 00/46617.
The high refractive index layer can also serve as a hard coat layer. In such a case, it is preferable to form fine particles dispersed in the hard coat layer using the method described for the high refractive index layer.

The hard coat layer can also serve as an antiglare layer containing particles having an average particle size of 0.2 to 10 μm and imparted with an antiglare function (antiglare function).
The film thickness of the hard coat layer can be appropriately designed depending on the application. The film thickness of the hard coat layer is preferably 0.2 to 10 μm, more preferably 0.5 to 7 μm.
The strength of the hard coat layer is preferably H or more, more preferably 2H or more, and most preferably 3H or more in a pencil hardness test according to JIS K5400. Moreover, in the Taber test according to JIS K5400, 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 ⁻³ ) or less. Although the use of a hygroscopic substance, a water-soluble inorganic salt, a certain surfactant, a cationic polymer, an anionic polymer, colloidal silica or the like can provide 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 such metal oxides as the conductive layer material is not preferable because the entire film is colored. Zn, Ti, Al, In, Si, Mg, Ba, Mo, W, or V can be cited as a metal that forms a metal oxide without coloration, and a metal oxide based on this can be used. preferable. 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 , and complex oxides thereof. ZnO, TiO ₂ and SnO ₂ are preferred. Examples of containing different atoms include, for example, additives such as Al and In for ZnO, addition of Sb, Nb and halogen elements for SnO ₂ , and Nb and TA for TiO ₂ . Addition is effective. Furthermore, as described in Japanese Examined Patent Publication No. 59-6235, a material obtained by adhering the above metal oxide to other crystalline metal particles or fibrous materials (for example, titanium oxide) may be used. The volume resistance value and the surface resistance value are different physical properties and cannot be simply compared. However, in order to ensure conductivity of 10 ⁻⁸ (Ωcm ⁻³ ) or less in volume resistance, The prevention layer should just have a surface resistance value of about 10 ⁻¹⁰ (Ω / □) or less, more preferably 10 ⁻⁸ (Ω / □) or less. The surface resistance value of the antistatic layer is a value obtained when the antistatic layer is the outermost layer, and can be measured in the middle of forming the antistatic layer.

[Liquid Crystal Display]
The liquid crystal display device of the present invention is a liquid crystal display device (first embodiment) using either the cellulose acylate film of the present invention described above or the polarizing plate of the present invention, and the polarizing plate of the present invention above and below the cell. An OCB or VA mode liquid crystal display device using two sheets (second embodiment) and a VA mode liquid crystal display device (third embodiment) using one polarizing plate of the present invention on the backlight side.
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 made into a multi-domain (MVA mode) for widening the viewing angle ), (3) Liquid crystal cell in a mode (n-ASM mode) in which rod-like liquid crystalline molecules are substantially vertically aligned when no voltage is applied and twisted multi-domain alignment is applied when a voltage is applied (Preliminary collections 58-59 of the Japanese Liquid Crystal Society) (1998)) and (4) SURVAVAL 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 plate 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.
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 the lamination 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 and observer side of FIG. 3 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) of FIG. 3 may be a normal cell rate 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.

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

[Example 1: Production of cellulose acylate film]
(1) Cellulose acylate Cellulose acylates with different types of acyl groups and acyl substitution degrees as shown in Tables 1 to 3 were prepared. Sulfuric acid (7.8 parts by mass with respect to 100 parts by mass of cellulose) was added as a catalyst, carboxylic acid was added, and an acylation reaction was performed at 40 ° C. Thereafter, the total substitution degree and the 6-position substitution degree were adjusted by adjusting the amount of sulfuric acid catalyst, the amount of water, and the aging time. The aging temperature was 40 ° C. Further, the low molecular weight component of the cellulose acylate was removed by washing with acetone. In the table, CAP is an abbreviation for cellulose acetate propionate (cellulose ester derivative in which an acyl group is an acetate group and propionyl group), and CAB is cellulose acetate butyrate (an acyl group is an acetate group and butyryl). CTA means cellulose triacetate (a cellulose ester derivative having an acyl group only with an acetate group and a substitution degree of about 3).

  These repose angles and bulk densities are controlled by changing the amount of catalyst sulfuric acid, heating time, heating temperature, stirring speed, polymer concentration in the neutralization step, amount of neutralizing agent, etc. in the acylation reaction. As for the particle size, when a desired particle was not obtained under the above conditions, the particle size was classified through a sieve having a sieve opening of 1.7 mm.

(Repose angle)
It was determined by measuring the angle between the horizontal side of a conical hypotenuse formed by pouring through a funnel on a disk with a diameter of 8 cm and the horizontal.

(The bulk density)
The bulk density (A) before tapping using a cylinder capacity of 100 cm ³ was measured using a multi-tester MT-1001 manufactured by Seishin Corporation.

(Particle size measurement)
Using a sonic sieving measuring device RPS-85P manufactured by Seishin Corporation, a mass ratio (unit%) of particles that did not pass through the sieve using a sieve having an opening of 1.7 mm, that is, particles larger than 1.7 mm. Was measured. Moreover, the mass ratio (unit%) which occupied the particle | grains which passed the sieve, ie, the particle | grains of 0.85 mm or less, was measured using the sieve of the opening of 0.85 mm.

(Process suitability)
In order to dissolve the cellulose acylate powder, it is blown from the silo to the mixing tank while being dried with dry air as described below. At that time, the case where the particles cause bridging, block the silo, and cannot be blown is indicated by ×, and the case where the particles can be blown without problem is indicated by ◯ in Tables 1 to 3 described later.

(Foreign matter in the film)
Using a polarizing microscope, a film size range of 10 mm × 10 mm was observed under a crossed Nicol at a magnification of 100 times, and the number of foreign matters of 5 μm or more was counted. It is desirable that it is 10 or less.

(Rth variation)
13 points were sampled in the width direction of the finished film, and using an automatic birefringence meter (KOBRA 21ADH: Oji Scientific Instruments), Re retardation value and Rth retardation value at 590 nm wavelength at 25 ° C and 60% relative humidity were measured. did. The variation of Rth was calculated by the following equation.
(Rth (maximum value) −Rth (minimum value)) / Rth (average value) * 100

(2) Dope Preparation <1-1> Cellulose Acylate Solution Cellulose acylate is charged into a polymer storage silo indicated by 6 in FIG. 1 of JP-A-2003-236863 and dried in a measuring tank indicated by 4 in FIG. It is blown while being sequentially dried with wind. Here, the amount of polymer is measured, and a predetermined amount of polymer is charged into a dissolution tank (mixing tank) indicated by 5 in FIG. The following composition was placed in a mixing tank, stirred to dissolve each component, further heated to 90 ° C. for about 10 minutes, 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.

Cellulose acylate solution
Cellulose acylate listed in Table 1 100.0 parts by mass Triphenyl phosphate 8.0 parts by mass Biphenyl diphenyl phosphate 4.0 parts by mass Methylene chloride 403.0 parts by mass
60.2 parts by mass of methanol

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

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

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

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

  100 parts by mass of the cellulose acylate solution, 1.35 parts by mass of the matting agent dispersion, and the retardation developer solution A were mixed at a ratio shown in Table 1 to prepare a dope for film formation. The addition ratio of the retardation enhancer was 5.0 parts by mass with respect to 100 parts by mass of the amount of cellulose acylate.

Retardation expression agent A

(Casting)
The above dope was cast using a band casting machine. After drying at an air supply temperature of 80 ° C. to 150 ° C. (exhaust temperature is 75 ° C. to 145 ° C.) on the band, the film peeled off from the band with a residual solvent amount of 50 to 75% by mass is supplied to the tenter zone A cellulose acylate film (thickness: 92 μm) was produced by stretching in the width direction at a temperature of 140 ° C. (exhaust temperature in the range of 90 ° C. to 125 ° C.) at a stretch ratio of 10% to 50%. The cast film thickness was adjusted so that the film thickness after stretching was 85 μm. Films having the respective compositions shown in Tables 1 to 3 according to the type of acyl group were prepared, and at least 24 rolls having a roll width of 1340 mm and a roll length of 2600 mm were prepared under the above conditions for the purpose of judging the production suitability. . The surface quality described in Tables 1 to 3 was measured 10 times with a sample of 1 m in the longitudinal direction (width 1340 mm) at intervals of 100 m per roll when the roll was continuously produced in 24 rolls while changing the visual field in the width direction. Average values are shown.

  When the inventive samples 101 to 120 and the comparative samples 011 to 015 in Table 1 are seen, the particles from the silo are mixed into the mixing tank when the angle of repose exceeds 45 degrees or the bulk density becomes 0.30 or less in the comparative samples 011 and 012. In the case of air-feeding, bridging or the like was not possible, and there was a problem in transportability. In Comparative Samples 013, 014, and 015, the bulk density is 0.75 or more and the mass ratio of particles having a particle diameter of 1.7 mm or more exceeds 3%. There are problems with the surface quality of the film, such as more than 10 foreign matters and Rth variation exceeding 10%.

  On the other hand, in the samples 101 to 120 of the present invention, it can be seen that even if the total substitution degree of CTA is widely changed to 2.00 to 2.86, good process suitability and film surface quality are maintained.

  Looking at the inventive samples 201-220 and comparative samples 021-025 in Table 2, when the angle of repose exceeds 45 degrees or the bulk density becomes 0.30 or less in comparative samples 021 and 022, particles are transferred from the silo to the mixing tank. In the case of air sending, bridging was caused, so that air sending could not be carried out and there was a problem in transportability. In Comparative Samples 023, 024, and 025, the bulk density was 0.75 or more and the mass ratio of particles having a particle diameter of 1.7 mm or more exceeded 3%, and although there was no problem in transportability, There are problems with the surface quality of the film, such as more than 10 foreign matters and Rth variation exceeding 10%.

  On the other hand, in the samples 201 to 220 of the present invention, it can be seen that even when the total substitution degree of CAP is changed widely to 2.20 to 2.90, good process suitability and film surface quality are maintained.

  Looking at the inventive samples 301 to 320 and the comparative samples 031 to 035 in Table 3, when the repose angle exceeds 45 degrees or the bulk density becomes 0.30 or less in the comparative samples 031 and 032, the particles are transferred from the silo to the mixing tank. In the case of air-feeding, bridging or the like was not possible, and there was a problem in transportability. In Comparative Samples 033, 034, and 035, the bulk density is 0.75 or more and the mass ratio of the particles having a particle diameter of greater than 1.7 mm exceeds 3%. There are problems with the surface quality of the film, such as more than 10 foreign matters and Rth variation exceeding 10%.

  On the other hand, in the samples 301 to 320 of the present invention, it can be seen that even if the total substitution degree of CAB is widely changed to 2.20 to 2.90, good process suitability and film surface quality are maintained.

About the produced cellulose acylate film (optical compensation sheet), using an automatic birefringence meter (KOBRA 21ADH: Oji Scientific Instruments), the Re retardation value and the Rth retardation value at a wavelength of 590 nm at 25 ° C. and a relative humidity of 60% are obtained. When measured, Re and Rth of the sample of the present invention had Re of 40 nm or more and 130 nm or less, and Rth of 123 nm or more and 260 nm or less.
The film was conditioned at 25 ° C./relative humidity 10% and 25 ° C./relative humidity 80% for 2 hours or more, and then measured in that environment. Changes in retardation of the cellulose acylate film from relative humidity 80% to relative humidity 10% at this time ΔRe, ΔRth (ΔRe = Re (10% RH) −Re (80% RH), ΔRth = Rth (10%) RH) −Rth (80% RH)), CTA had ΔRe of 5 to 13 nm and ΔRth of 25 to 30. Further, CAP had ΔRe of 10 nm or less and ΔRth of 20 nm or less. CAB had ΔRe of 8 nm or less and ΔRth of 13 nm or less.
The following examples were carried out on the inventive samples 112, 212, 312 and comparative samples 015, 025, 035, in which Re was 60 nm and Rth was 220 nm.

[Example 2: Polarizing plate]
<2-1-1>
(Preparation of polarizing plate-1)
A polarizer was produced by adsorbing iodine to a stretched polyvinyl alcohol film.
The cellulose acylate films (invention samples 112, 212, 312 and comparative samples 015, 025, 035) prepared in Example 1 were attached to one side of a polarizer using a polyvinyl alcohol-based adhesive. The saponification treatment was performed under the following conditions.
A 1.5 mol / L aqueous sodium hydroxide solution was prepared and kept at 55 ° C. A 0.005 mol / L dilute sulfuric acid aqueous solution was prepared and kept at 35 ° C. The produced cellulose acylate film was immersed in the aqueous sodium hydroxide solution for 2 minutes, and then immersed in water to sufficiently wash away the aqueous sodium hydroxide solution. Subsequently, after being immersed in the above-mentioned dilute sulfuric acid aqueous solution for 1 minute, it was immersed in water to sufficiently wash away the dilute sulfuric acid aqueous solution. Finally, the sample was thoroughly dried at 120 ° C.
Commercially available cellulose triacylate film (Fujitac TD80UF, manufactured by Fuji Photo Film Co., Ltd .: functional film TAC2 in FIG. 2, equivalent to TAC2-1 or 2-2 in FIG. 3) is subjected to saponification treatment to obtain a polyvinyl alcohol type Using an adhesive, it was attached to the opposite side of the polarizer and dried at 70 ° C. for 10 minutes or more.
The transmission axis of the polarizer and the slow axis of the cellulose acylate film produced in Example 1 were arranged so as to be parallel (FIG. 1). The transmission axis of the polarizer and the slow axis of the commercially available cellulose triacylate film were arranged so as to be orthogonal.
A part of the polarizing plates A112, A212, A312 of the present invention and the comparative polarizing plates A015, A025, A035 (the polarizing plate integrated with the optical compensation film in FIG. The other part was stored in a moisture-proof bag, and the other part was conditioned at 25 ° C. and 60% relative humidity for 2 hours and stored in a moisture-proof bag. The moisture-proof bag was a packaging material having a laminated structure of polyethylene terephthalate / aluminum / polyethylene, and the moisture permeability was 0.01 mg / m ² (24 hours) or less.

<2-2-1>
(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) 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.

<2-2-2>
(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 by mass of methyl ethyl ketone, 100 parts by mass of acryloyloxypropyltrimethoxysilane (KBM5103, manufactured by Shin-Etsu Chemical Co., Ltd.), 3 parts by mass of diisopropoxyaluminum ethyl acetoacetate were added and mixed. Then, 30 parts by mass of ion-exchanged water was added and reacted at 60 ° C. for 4 hours, and then cooled to room temperature to obtain 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 30% concentration, manufactured by Nissan Chemical Co., Ltd.) 1.3 g, 0.6 g of the above sol solution a, 5 g of methyl ethyl ketone, and 0.6 g of cyclohexano were added. After stirring, the mixture was filtered through a polypropylene filter having a pore size of 1 μm. A coating solution for the refractive index layer was prepared.

<2-2-3>
(Preparation of transparent protective film 01 with light scattering layer)
An 80 μm-thick triacetyl cellulose film (TAC-TD80U, 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, Using a gravure pattern with a depth of 40 μm and a microgravure roll with a diameter of 50 mm and a doctor blade, it was applied under the conditions of a gravure roll rotation speed of 30 rpm and a conveyance speed of 30 m / min, dried at 60 ° C. for 150 seconds, and further purged with nitrogen Using an air-cooled metal halide lamp (manufactured by Eye Graphics Co., Ltd.) at 160 W / cm, the coating layer was cured by irradiating ultraviolet rays with an irradiance of 400 mW / cm ² and an irradiation amount of 250 mJ / cm ² , and a thickness of 6 μm A functional layer was formed and wound up.
The triacetyl cellulose film coated with the functional layer (light scattering layer) is unwound again, and the prepared coating liquid for the low refractive index layer is gravure with a line number of 180 lines / inch and a depth of 40 μm on the light scattering layer side. Using a micro gravure roll with a diameter of 50 mm and a doctor blade having a pattern, it was applied under the conditions of a gravure roll rotation speed of 30 rpm and a conveyance speed of 15 m / min, dried at 120 ° C. for 150 seconds and further dried at 140 ° C. for 8 minutes Then, using a 240 W / cm air-cooled metal halide lamp (manufactured by Eye Graphics Co., Ltd.) under nitrogen purge, irradiance was irradiated with ultraviolet rays of 400 mW / cm ² and an irradiation amount of 900 mJ / cm ^2. A refractive index layer was formed and wound up (corresponding to the functional film TAC2 in FIG. 2 or TAC2-1 in FIG. 3).

<2-3-1>
(Preparation of polarizing plate-2)
A polarizer was produced by adsorbing iodine to a stretched polyvinyl alcohol film.
The prepared transparent protective film 01 with a light scattering layer is subjected to the same saponification treatment as described in <2-1-1>, and a side without a functional film and one side of a polarizer are attached using a polyvinyl alcohol-based adhesive. I attached.
The cellulose acylate film prepared in Example 1 (present invention samples 112, 212, 312 and comparative samples 015, 025, 035: equivalent to TAC1 in FIG. 1) was subjected to the same saponification treatment, and a polyvinyl alcohol adhesive was applied. And attached to the opposite side of the polarizer and dried at 70 ° C. for 10 minutes or more (the configuration in FIG. 2 was completed).
The transmission axis of the polarizer and the slow axis of the cellulose acylate film produced in Example 1 were arranged so as to be parallel (FIG. 1). The transmission axis of the polarizer and the slow axis of the transparent protective film 01 with the light scattering layer were arranged so as to be orthogonal to each other. In this way, polarizing plates (B112, B212, B312 and B015, B025, B035: functional film and optical compensation film integrated polarizing plate (FIG. 2)) were produced. In the same manner as the production of the polarizing plate <2-1-1>, a product that was put in a moisture-proof bag after conditioning for 2 hours at 25 ° C. and a relative humidity of 60% and a product that was put in a moisture-proof bag without conditioning were prepared. .
A polarizer was produced by adsorbing iodine to a stretched polyvinyl alcohol film. The transparent protective film 01 with the light scattering layer prepared in <2-2-3> and the triacetyl cellulose film (TAC-TD80U, manufactured by Fuji Photo Film Co., Ltd.) having a thickness of 80 μm without the functional layer applied. The saponification process was performed in the same manner as described above, and was bonded to the polarizer in the same manner as described above using a polyvinyl alcohol-based adhesive. In this way, a polarizing plate (B0: functional film, optical compensation film integrated polarizing plate (FIG. 2)) was prepared. In the same manner as the production <2-1-1> of the polarizing plate, a product put in a moisture-proof bag after humidity control and a product put in a moisture-proof bag without conditioning were prepared.
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 determined, it was 2.3%.
Using a spectrophotometer (UV3100PC), the single plate transmittance TT, the parallel transmittance PT, and the orthogonal transmittance CT of the 380 nm to 780 nm humidity-controlled polarizing plate are combined so that the optical compensation film is placed inside the polarizer. When measured and an average value of 400 to 700 nm was determined for the sample of the present invention, TT was 42.7, PT was 38, and CT was 0.8. Further, in the polarizing plate durability test for 500 hours at 60 ° C. and 95% relative humidity, both are in the range of −0.1 ≦ ΔCT ≦ 0.2 and −2.0 ≦ ΔP ≦ 0, and 60 ° C. and relative humidity 90 %, −0.05 ≦ ΔCT ≦ 0.15 and −1.5 ≦ ΔP ≦ 0. Further, the orthogonal transmittance T (410) at a wavelength of 410 nm was 0.07 to 0.18.

<2-4-1>
(Preparation of coating solution for hard coat layer)
750.0 parts by mass of trimethylolpropane triacrylate (TMPTA, Nippon Kayaku Co., Ltd.), 270.0 parts by mass of poly (glycidyl methacrylate) with a weight average molecular weight of 3000, 730.0 g of methyl ethyl ketone, 500.0 g of cyclohexanone and light A polymerization initiator (Irgacure 184, manufactured by Nippon Ciba-Geigy Co., Ltd.) 50.0 g was added and stirred. The solution was filtered through a polypropylene filter having a pore size of 0.4 μm to prepare a coating solution for a hard coat layer.

<2-4-2>
(Preparation of titanium dioxide fine particle dispersion)
As the titanium dioxide fine particles, titanium dioxide fine particles (MPT-129, manufactured by Ishihara Sangyo Co., Ltd.) containing cobalt and surface-treated with aluminum hydroxide and zirconium hydroxide were used.
The following dispersant (38.6 g) and cyclohexanone (704.3 g) were added to 257.1 g of the particles and dispersed by dynomill to prepare a titanium dioxide dispersion having a mass average diameter of 70 nm.

Dispersant

<2-4-3>
(Preparation of coating solution for medium refractive index layer)
To 88.9 g of the above titanium dioxide dispersion, 58.4 g of a mixture of dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate (DPHA), 3.1 g of a photopolymerization initiator (Irgacure 907), a photosensitizer (Kayacure DETX) 1.1 g of Nippon Kayaku Co., Ltd.), 482.4 g of methyl ethyl ketone and 1869.8 g of cyclohexanone were added and stirred. After sufficiently stirring, the solution was filtered through a polypropylene filter having a pore size of 0.4 μm to prepare a coating solution for a medium refractive index layer.

<2-4-4>
(Preparation of coating solution for high refractive index layer)
To 56.8 g of the above titanium dioxide dispersion, 47.9 g of a mixture of dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate (DPHA, manufactured by Nippon Kayaku Co., Ltd.), a photopolymerization initiator (Irgacure 907, Nippon Ciba Geigy ( 4.0 g), photosensitizer (Kayacure-DETX, Nippon Kayaku Co., Ltd.) 1.3 g, methyl ethyl ketone 455.8 g, and cyclohexanone 1427.8 g were added and stirred. The solution was filtered through a polypropylene filter having a pore size of 0.4 μm to prepare a coating solution for a high refractive index layer.

<2-4-5>
(Preparation of coating solution for low refractive index layer)
The following copolymer was dissolved in methyl isobutyl ketone so as to have a concentration of 7% by mass, and a terminal methacrylate group-containing silicone resin X-22-164C (manufactured by Shin-Etsu Chemical Co., Ltd.) was 3% based on the solid content, light Radical generator Irgacure 907 (trade name) was added in an amount of 5% by mass based on the solid content to prepare a coating solution for a low refractive index layer.

Copolymer

<2-4-6>
(Preparation of transparent protective film 02 with antireflection layer)
A hard coat layer coating solution was applied onto a triacetyl cellulose film (TD-80UF, manufactured by Fuji Photo Film Co., Ltd.) having a thickness of 80 μm using a gravure coater. After drying at 100 ° C., using a 160 W / cm air-cooled metal halide lamp (manufactured by Eye Graphics Co., Ltd.) while purging with nitrogen so that the atmosphere has an oxygen concentration of 1.0 vol% or less, an irradiance of 400 mW / The coating layer was cured by irradiating ultraviolet rays having a cm ² and an irradiation amount of 300 mJ / cm ² to form a hard coat layer having a thickness of 8 μm.
On the hard coat layer, a medium refractive index layer coating solution, a high refractive index layer coating solution, and a low refractive index layer coating solution were successively applied using a gravure coater having three coating stations.

  The intermediate refractive index layer was dried at 100 ° C. for 2 minutes, and the ultraviolet curing condition was 180 W / cm air-cooled metal halide lamp (eye graphics) while purging with nitrogen so that the atmosphere had an oxygen concentration of 1.0% by volume or less. The amount of irradiation was 400 mW / cm 2 and the amount of irradiation was 400 mJ / cm 2. The medium refractive index layer after curing had a refractive index of 1.630 and a film thickness of 67 nm.

The drying conditions of the high refractive index layer and the low refractive index layer are both 90 ° C., 1 minute, 100 ° C., 1 minute, and the ultraviolet curing condition is nitrogen so that the oxygen concentration is 1.0 volume% or less. While purging, a 240 W / cm air-cooled metal halide lamp (manufactured by Eye Graphics Co., Ltd.) was used to obtain an irradiance of 600 mW / cm ² and an irradiation amount of 600 mJ / cm ² .
The cured high refractive index layer had a refractive index of 1.905 and a film thickness of 107 nm, and the low refractive index layer had a refractive index of 1.440 and a film thickness of 85 nm. Thus, the transparent protective film 02 with an antireflection layer was produced (corresponding to the functional film TAC2 in FIG. 2 or TAC2-1 in FIG. 3).

<2-5-1>
(Preparation of polarizing plate-3)
A polarizing plate (C112, C212, C312 and C015, C025, C035: similar to <2-3-1> except that the transparent protective film 02 with an antireflection layer was used instead of the transparent protective film with a light scattering layer 01: A functional film and an optical compensation film integrated polarizing plate (FIG. 2)) were produced. Further, in the same manner, the transparent protective film 02 with an antireflection layer, a triacetyl cellulose film (TAC-TD80U, manufactured by Fuji Photo Film Co., Ltd.) having a thickness of 80 μm without applying a polarizer and a functional layer is used. A polarizing plate (C0) was produced.
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 determined, it was 0.4%.

[Example 3]
(Mounting on the panel)
[Example 3-1]
(Mounting on VA panel) (Single sheet type)
The liquid crystal display device of FIG. 3 was produced. That is, from the observation direction (top), the upper polarizing plate (TAC2-1 (with / without functional film), polarizer, TAC1-1), VA mode liquid crystal cell, lower polarizing plate (TAC1-2, polarizer, TAC2) -2) were laminated, and a backlight light source was further arranged. In the following example, a commercially available polarizing plate (HLC2-5618) is used for the upper polarizing plate, and a polarizing plate integrated with an optical compensation film is used for the lower polarizing plate. But there is no problem functionally. However, as an integrated polarizing plate, it is often used as a lower polarizing plate (if it is 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 reduced. Therefore, it is considered to be a more preferable embodiment.

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

A commercially available super high contrast product (for example, HLC2-5618 manufactured by Sanlitz Co., Ltd.) is used for the upper polarizing plate (observer side) of the liquid crystal display device (FIG. 3) using the vertical alignment type liquid crystal cell. It was. Polarizing plates (A112, A212, A312) prepared in <2-1-1> of Example 2 using the optical compensation sheet prepared in Example 1 (sample 106) for the lower polarizing plate (backlight side) The cellulose acylate film prepared in Example 1 (corresponding to TAC1-2 in FIG. 3) was placed on the liquid crystal cell side. The upper polarizing plate and the lower polarizing plate were attached to the liquid crystal cell via an adhesive. The crossed Nicols were arranged so that the transmission axis of the upper polarizing plate was in the vertical direction and the transmission axis of the lower polarizing plate was in the left-right direction. The polarizing plate to be used is both the one that has been stored in a moisture-proof and moisture-proof bag for 2 hours under the temperature and humidity conditions of 25 ° C. and 60% relative humidity, and the one that has been stored in a bag without humidity control. A liquid crystal display device was created.
Here, a commercial product is used for the upper polarizing plate and the integrated polarizing plate of the present invention is used for the lower polarizing plate. As a result of observing the produced liquid crystal display device, the front direction and the viewing angle direction are also neutral. Black display was realized. In addition, using a measuring instrument (EZ-Contrast 160D, manufactured by ELDIM), the viewing angle (contrast ratio is 10 or more and there is no black-side gradation inversion) in eight stages from black display (L1) to white display (L8). Range).
As a result of observing the manufactured liquid crystal display device, a neutral black display was realized in the front direction and the viewing angle direction. In addition, using a measuring instrument (EZ-Contrast 160D, manufactured by ELDIM), the viewing angle (contrast ratio is 10 or more and there is no gradation inversion on the black side) in 8 steps from black display (L1) to white display (L8). ) Was measured.
Next, measuring instrument (EZ-Contrast160D, manufactured by ELDIM) for the display of black with an azimuth angle of 45 ° with respect to the horizontal direction of the liquid crystal display screen and a polar angle of 60 ° with respect to the normal direction of the screen surface. Was used as an initial value. Next, this panel was left in a room at room temperature and normal humidity (25 ° C., relative humidity of about 60% and no humidity control) for one week, and the color during black display was measured again.
Table 2 below shows the measurement of viewing angle and color change. All of the examples had a wide viewing angle and little color change. In the case where the humidity of the polarizing plate was adjusted before assembling the liquid crystal display device, the color change was particularly small.

[Example 3-2]
<2-1-1 of Example 2 using the optical compensation sheet prepared in Example 1 (sample 106) as the lower polarizing plate of the liquid crystal display device (FIG. 3) using the vertical alignment type liquid crystal cell described above. The polarizing plate (B106) prepared in <2-3-1> of Example 2 was attached to the upper polarizing plate (A106) via an adhesive. The crossed Nicols were arranged so that the transmission axis of the polarizing plate on the viewer side was in the vertical direction and the transmission axis of the polarizing plate on the backlight side was in the horizontal direction. At this time, it was air-conditioned so that the temperature of the workplace was 20 to 25 ° C. and the relative humidity was 50 to 70%. The polarizing plate to be used is both the one that has been stored in a moisture-proof and moisture-proof bag for 2 hours under the temperature and humidity conditions of 25 ° C. and 60% relative humidity, and the one that has been stored in a bag without humidity control. A liquid crystal display device was created.
As a result of observing the manufactured liquid crystal display device, a neutral black display was realized in the front direction and the viewing angle direction. Moreover, the viewing angle and the color change were measured in the same manner as in Example 3-1, and the results are shown in Table 2.

[Example 3-3]
<2-1-1 of Example 2 using the optical compensation sheet prepared in Example 1 (sample 106) as the lower polarizing plate of the liquid crystal display device (FIG. 3) using the vertical alignment type liquid crystal cell described above. > The polarizing plate (C0) prepared in <2-5-1> of Example 2 was attached to the upper polarizing plate (A112, A212, A312) via an adhesive. The crossed Nicols were arranged so that the transmission axis of the polarizing plate on the viewer side was in the vertical direction and the transmission axis of the polarizing plate on the backlight side was in the horizontal direction. At this time, it was air-conditioned so that the temperature of the workplace was 20 to 25 ° C. and the relative humidity was 50 to 70%. The polarizing plate to be used is both the one that has been stored in a moisture-proof and moisture-proof bag for 2 hours under the temperature and humidity conditions of 25 ° C. and 60% relative humidity, and the one that has been stored in a bag without humidity control. A liquid crystal display device was created.
As a result of observing the manufactured liquid crystal display device, a neutral black display was realized in the front direction and the viewing angle direction. Moreover, the viewing angle and the color change were measured in the same manner as in Example 3-1, and the results are shown in Table 2.

[Comparative Example 3-1]
The same procedure as in Example 3-1 was performed except that the lower polarizing plate of Example 3-1 was A005, A006, and A007. The polarizing plate used here was not conditioned.
As a result of observing the manufactured liquid crystal display device, bright spot defects were conspicuous, and not the neutral black display in the front direction and the viewing angle direction, but unevenness occurred on the entire panel. Further, as in Example 3-1, the viewing angle and the color change were measured, and the results are shown in Table 4.

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 at the time of arrange | positioning the polarizing plate of this invention to a VA mode liquid crystal cell.

Claims (13)

Cellulose acylate having an angle of repose of 22 degrees or more and 43 degrees or less, a bulk density of 0.30 g / cm ³ or more and 0.75 g / cm ³ or less, and a mass ratio of particles having a particle size larger than 1.7 mm is 3% or less. A method for preparing a cellulose acylate solution, comprising dissolving particles in an organic solvent. When the substitution degree of the acyl group of the hydroxyl group at the 2-position of the glucose unit of the cellulose acylate is DS2, the substitution degree of the hydroxyl group of the 3-position is DS3, and the substitution degree of the hydroxyl group of the 6-position is DS6, The method for preparing a cellulose acylate solution according to claim 1, wherein the cellulose acylate satisfies at least one of the following formulas (I) and (II).
Formula (I): 2.0 ≦ DS2 + DS3 + DS6 ≦ 3.0
Formula (II): DS6 / (DS2 + DS3 + DS6) ≧ 0.315   The cellulose acylate solution according to claim 1 or 2, wherein cellulose acylate particles containing particles having a particle size of 0.85 mm or less on a mass basis in an amount of 70% or more of all constituent particles are dissolved in an organic solvent. Method.   A cellulose acylate film prepared by preparing a cellulose acylate solution according to any one of claims 1 to 3, casting the solution on a support, and drying the solvent to form a film. Manufacturing method.   A cellulose acylate film obtained by the production method according to claim 4. The optical retardation according to claim 5, wherein the front retardation Re (590) and the retardation Rth (590) in the film thickness direction of the film at a wavelength of 590 nm satisfy the following formulas (IX) and (X). Cellulose acylate film.
Formula (IX): 30 nm ≦ Re (590) ≦ 200 nm
Formula (X): 70 nm ≦ Rth (590) ≦ 400 nm   The optical cellulose acylate film according to claim 5, comprising at least one retardation developer composed of a rod-like or discotic compound.   The optical cellulose acylate film according to claim 5, comprising at least one of a plasticizer, an ultraviolet absorber, and a peeling accelerator.   It is a polarizing plate which has a protective film on both surfaces of a polarizer, Comprising: At least one of the said protective films is a cellulose acylate film for optics as described in any one of Claims 5-8, The polarizing plate characterized by the above-mentioned. .   The polarizing plate according to claim 9, wherein at least one of a hard coat layer, an antiglare layer, and an antireflection layer is provided on the surface of one protective film of the polarizer.   A liquid crystal display device comprising the optical cellulose acylate film according to any one of claims 5 to 8 and the polarizing plate according to claim 9 or 10.   An OCB or VA mode liquid crystal display device using the polarizing plate according to claim 9 for at least one of upper and lower sides of a cell. A VA mode liquid crystal display device using any one of the polarizing plates according to claim 9 or 10 on a backlight side.

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