JP2007326244A - Method for producing cellulose acylate film, cellulose acylate film, phase difference film, polarizing plate, and liquid crystal display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystal display which is reduced in light leakage after receiving changes in temperature and humidity, a cellulose acylate film, a phase difference film, and a polarizing plate for materializing the liquid crystal display, and methods for producing these. <P>SOLUTION: The method for producing the cellulose acylate film includes a film making process in which a cellulose acylate solution is cast on a metal support to make the film, the first stretching process in which the film is stretched at a temperature of Tg+(0-60)°C in a region of 30-65 mass% volatilization, and the second stretching process in which the film is stretched perpendicularly to the direction of the stretching in the first stretching process at a temperature of Tg+(0-60)°C in a region of 0-35 mass% volatilization. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for producing a cellulose acylate film, a cellulose acylate film, a retardation film, a polarizing plate, and a liquid crystal display device.

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. In such a liquid crystal display device, various modes have been proposed depending on the alignment state of the liquid crystal in the liquid crystal cell. Conventionally, the TN is in an alignment state twisted by about 90 ° from the lower substrate to the upper substrate of the liquid crystal cell. The mode was mainstream.
In general, a liquid crystal display device includes a liquid crystal cell, an optical compensation sheet (also referred to as a retardation film), 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 liquid crystal display device for television 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.

The cellulose acylate film is characterized by high optical isotropy (low retardation value) compared to other polymer films. Therefore, it is common to use a cellulose acetate film for an application requiring optical isotropy, for example, a polarizing plate. Patent Document 2 discloses a method for producing a cellulose acetate film with little insoluble matter and high transparency by defining the relationship between the viscosity average degree of polymerization of cellulose acetate and the viscosity of a dope obtained by dissolving this in a solvent. Further, Patent Document 3 discloses a preferable relationship among the thickness d of the cellulose acetate film, the solid content concentration y (%) of the cellulose acetate film-forming solution, and the solution viscosity ρ in order to eliminate the planar failure called die stripe. ing.
On the other hand, an optical anisotropy (high retardation value) is required for an optical compensation sheet of a liquid crystal display device. In particular, an optical compensation sheet for VA requires in-plane retardation (Re) of 30 to 200 nm and thickness direction retardation (Rth) of 70 to 400 nm. Therefore, it is common to use a synthetic polymer film having a high retardation value such as a polycarbonate film or a polysulfone film as the optical compensation sheet.
As described above, in the technical field of optical materials, when a polymer film requires optical anisotropy (high retardation value (Re, Rth)), a synthetic polymer film is used and optical isotropy ( When low retardation values are required, it was a general rule to use a cellulose acetate film.

  Patent Document 4 discloses a cellulose acetate film having a high retardation value that can be used for applications requiring optical anisotropy, overcoming the conventional general principle. In this document, in order to realize a high retardation value with cellulose triacetate, an aromatic compound having at least two aromatic rings is added and subjected to stretching treatment.

Japanese Patent No. 2587398 JP 2000-131524 A JP 2001-129838 A European Patent Application No. 91656

Cellulose triacetate is generally a polymer material that is difficult to stretch, and it is known that it is difficult to increase the birefringence, but it is necessary to increase the birefringence by simultaneously orienting the additives in the stretching process. And a high retardation value (Re, Rth) is realized. Since this film can also serve as a protective film for the polarizing plate, there is an advantage that an inexpensive and thin liquid crystal display device can be provided, and the method described in the above-mentioned patent document provides an inexpensive and thin liquid crystal display device. Effective in terms.
On the other hand, light leakage at the periphery of the screen during black display due to the contraction stress of the polarizing plate has become a problem in a liquid crystal display device having a large screen. The polarizing plate causes a dimensional change accompanying a change in the temperature and humidity of the environment mainly by using the contraction of the polarizer as a driving force. Stress is locally generated in the glass substrate of the layer and the liquid crystal cell, and light leakage occurs with a change in birefringence due to photoelasticity of each member.
About a polarizing plate protective film, since the extending | stretching process is performed, the elasticity modulus of an extending | stretching direction is high compared with the direction orthogonal to an extending | stretching direction, and elastic modulus anisotropy is large. Therefore, the dimensional change of the polarizing plate in the direction of low elastic modulus is large, and light leakage occurs.
In order to reduce light leakage, it is necessary to adjust the stretching conditions and increase the elastic modulus in both the stretching direction of the protective film and the direction orthogonal to the stretching direction in a balanced manner. However, in simultaneous biaxial stretching and fixed-width uniaxial stretching, the optical performance will not reach a desired value when trying to balance the elastic modulus.
There has been a demand for a solution to this light leakage problem.

  An object of the present invention is to provide a liquid crystal display device with little light leakage even after being subjected to changes in temperature and humidity, and a cellulose acylate film, a retardation film, a polarizing plate, and a production for producing them, for realizing the liquid crystal display device Is to provide a method.

The present invention is specifically shown below.
(1)
A film forming step of casting a cellulose acylate solution on a metal support to form a film, and then Tg + 0 to 60 ° C. in a volatile content region of 30 to 65% by mass with respect to the film obtained by the film forming step. The first stretching step for stretching and the second stretching step for stretching in the direction substantially orthogonal to the first stretching step at Tg + 0 to 60 ° C. in the volatile fraction region of 0 to 35% by mass after the first stretching step. The manufacturing method of the cellulose acylate film containing this.
(2)
Stretching in the first stretching step is performed in the transport direction, and stretching in the second stretching step is performed in a direction substantially orthogonal to the transport direction. The method for producing a cellulose acylate film according to (1),
(3)
(1) or (2), wherein the stretching in the first stretching step is performed at a stretching ratio of 1.03 to 2 times, and the stretching in the second stretching step is performed at a stretching ratio of 1.10 to 2 times. The manufacturing method of the cellulose acylate film of description.
(4)
A cellulose acylate film produced by the method for producing a cellulose acylate film according to any one of (1) to (3).
(5)
The ratio of the elastic modulus in the film conveyance direction and the elastic modulus in the direction substantially perpendicular to the conveyance direction (elastic modulus in the film conveyance direction / elastic modulus in the direction substantially orthogonal to the conveyance direction) is 0.8 to 1.2. The cellulose acylate film as described in (4), wherein
(6)
Both the elastic modulus in the film transport direction and the elastic modulus in the direction substantially perpendicular to the transport direction are 3000 MPa to 10000 MPa, and the cellulose acylate film according to (4) or (5).
(7)
The cellulose according to any one of (4) to (6), wherein the front retardation value Re is 30 ≦ Re ≦ 200 nm, and the retardation value Rth in the film thickness direction is 70 ≦ Rth ≦ 350 nm. Acylate film.
(8)
The film thickness of a film is 20-110 micrometers, The cellulose acylate film of any one of (4)-(7) characterized by the above-mentioned.
(9)
The cellulose acylate film according to any one of (4) to (8), wherein the cellulose acylate film contains at least one retardation enhancer.
(10)
The content of the retardation developer added to the cellulose acylate film is 0% by mass or more and 10% by mass or less when the cellulose acylate is 100% by mass (4 The cellulose acylate film of any one of (9)-(9).
(11)
Cellulose acylate film, cellulose ester obtained by substituting cellulose hydroxyl group with acetyl group, and / or cellulose mixed fatty acid obtained by substituting acetyl group and acyl group having 3 or more carbon atoms A cellulose acylate film produced using an ester, wherein the substitution degree A of the acetyl group and the substitution degree B of the acyl group having 3 or more carbon atoms satisfy the following formulas (I) and (II) (4) The cellulose acylate film according to any one of to (10).
Formula (I): 2.0 ≦ A + B ≦ 3.0
Formula (II): 0 ≦ B
(12)
The cellulose acylate film as described in (11), wherein the acyl group is a butanoyl group.
(13)
The cellulose acylate film according to (11), wherein the acyl group is a propionyl group, and the substitution degree B is 0.6 or more.
(14)
The cellulose acylate film is a film produced using cellulose acylate obtained by substituting the hydroxyl group of the glucose unit constituting the cellulose acylate film with an acyl group having 2 or more carbon atoms, When the substitution degree of the hydroxyl group at the 2-position of the unit with an acyl group is DS2, the substitution degree of the hydroxyl group at the 3-position with an acyl group is DS3, and the substitution degree of the hydroxyl group at the 6-position with DS6 is DS6, the following formula (III) And (IV), the cellulose acylate film as described in (11).
(III): 2.0 ≦ DS2 + DS3 + DS6 ≦ 2.85
(IV): DS6 / (DS2 + DS3 + DS6) ≧ 0.315
(15)
A retardation film having the cellulose acylate film according to any one of (4) to (14).
(16)
Polarized light characterized in that at least one of the cellulose acylate film according to any one of (4) to (14) and the retardation film according to (15) is used as a protective film for a polarizer. Board.
(17)
At least one of the cellulose acylate film according to any one of (4) to (14), the retardation film according to (15), and the polarizing plate according to (16) is used. A liquid crystal display device characterized by the above.

  According to the present invention, there are provided a liquid crystal display device with little light leakage even after being subjected to temperature and humidity changes, a cellulose acylate film, a retardation film, a polarizing plate, and a production method for producing them, for realizing the liquid crystal display device. I was able to provide it.

  In this specification, the description “A to B” means “A to B”.

  Hereinafter, the present invention will be described in detail.

  The main point of realizing a liquid crystal display device with little light leakage even after being subjected to temperature and humidity changes according to the present invention, and a cellulose acylate film, a retardation film, and a polarizing plate for realizing the liquid crystal display device has a high retardation value. On the other hand, it is possible to find a method for producing a cellulose acylate film having relatively small elastic modulus anisotropy in the film plane.

Hereinafter, the method for producing the cellulose acylate film of the present invention will be described in detail.
The production method of the present invention comprises a film forming step of casting a cellulose acylate solution on a metal support to form a film, and then a volatile fraction of 30 to 65% by mass with respect to the film obtained by the film forming step. First stretching step in which stretching is performed at Tg + 0 to 60 ° C. in the region, and after the first stretching step, in a volatile content region of 0 to 35% by mass in a direction substantially orthogonal to the first stretching step at Tg + 0 to 60 ° C. The present invention relates to a method for producing a cellulose acylate film including a second stretching step of stretching.

The casting and film formation will be described later.
In this invention, this extending | stretching of a cellulose acylate film is performed at Tg + 0-60 degreeC in a 30-65 mass% volatile content area | region in a 1st extending process, and 0-35 mass% volatile content in a 2nd extending process. In the rate region, Tg + 0 to 60 ° C. is performed in a direction substantially orthogonal to the stretching direction in the first stretching step. Here, Tg represents the glass transition temperature of the cellulose acylate film containing a solvent. Moreover, you may perform a 1st extending process and a 2nd extending process by sequential extending | stretching. Sequential stretching refers to a series of stretching operations in which a film is first stretched in a certain direction and second stretching is performed in a direction different from the first stretching after the stretching is completed.

More preferably, the first stretching is performed at Tg + 0 to 50 ° C. in a volatile fraction region of 35 to 60% by mass, and the second stretching is performed at Tg + 0 to 50 ° C. in a volatile fraction region of 10 to 30% by mass. More preferably, the first stretching is performed at Tg + 0 to 40 ° C. in a volatile fraction region of 40 to 55% by mass, and the second stretching is performed at Tg + 0 to 40 ° C. in a volatile fraction region of 10 to 25% by mass. Examples of the method for adjusting the volatile fraction include adjusting the concentration of the cellulose acylate solution during casting, adjusting the drying conditions after casting, and changing the mechanical stretching position.
Moreover, in this invention, it is preferable that the extending | stretching direction in a 1st extending | stretching process is a conveyance direction, and 2nd extending | stretching is performed in the direction substantially orthogonal to this conveyance direction.

In the present invention, the glass transition temperature (Tg) was measured with a differential scanning calorimeter DSC2910 manufactured by TA Instruments. The measurement mode was a modulated DSC mode. The temperature increase rate was 2 ° C./min, the amplitude was ± 1 ° C., the amplitude period was 80 sec, and the measurement temperature range was −50 to 200 ° C., and the measurement was performed in 2 cycles (temperature increase to temperature decrease to temperature increase to temperature decrease). A cellulose acylate film containing volatile components was sealed in a stainless steel sealed container made of SII and measured.
When the vertical axis represents the reversible heat capacity (J / g / ° C.) and the horizontal axis represents the temperature (° C.), the reversible heat capacity seen when moving from the solid region to the glass transition region in the second temperature rise curve is abrupt. At the increasing portion, the straight line 1 is drawn in the solid region and the straight line 2 when the straight line 2 is drawn in the glass transition region is defined as the glass transition temperature Tg.
The term “substantially orthogonal” means that the angle formed by the transport direction and the second stretching direction is approximately orthogonal. The angle is preferably 70 to 110 °, more preferably 80 to 100 °, and most preferably 85 to 95 °.

The reason why a cellulose acylate film having a relatively small elastic modulus anisotropy in the film plane can be obtained while realizing a high retardation value by the production method of the present invention is presumed as follows.
In the present invention, the cellulose acylate chain is stretched in a substantially orthogonal direction by the first stretching step and the second stretching step. That is, the cellulose acylate chain is not only oriented in one direction in the film plane, but also oriented in a direction substantially orthogonal to it to some extent. This makes it possible to obtain a film having a relatively small elastic modulus anisotropy in the film plane.
On the other hand, since the retardation developer is a low molecular weight compound, the first stretching step with a large amount of volatile components in the film is affected by the relaxation of the orientation due to the solvent, and is not efficiently oriented in the stretching direction in the first stretching step. .
However, since the drying progresses and the influence of relaxation by the solvent is reduced in the second stretching step in a state where the amount of volatile components in the film is small, the retardation developer is efficiently oriented in the stretching direction in the second stretching step. It will be. That is, unlike the cellulose acylate, the retardation enhancer is mainly oriented in the stretching direction in the second stretching step, so that a high retardation value can be obtained.

Regarding the first stretching, in the volatile content region higher than 65% by mass, the cellulose acylate film is too soft and has no self-supporting property, and stretching cannot be performed. In addition, the first stretching in the volatile fraction region lower than 30% by mass and the second stretching in the volatile fraction region higher than 35% by mass cannot induce orientation anisotropy of the retardation developer. Further, at a temperature lower than Tg, the elongation at break is small, so that sufficient stretching cannot be performed. At a temperature higher than Tg + 60 ° C., relaxation of the cellulose acylate chain occurs, so that the elastic modulus is lowered.
The measurement of the volatile content rate during stretching is performed by a method of estimating the volatile content rate from a film drying simulation, or by a method in which the conveyance is stopped in the middle of stretching and the sample is directly cut to measure the volatile content. When the mass of the sample containing the volatile matter is M and the mass of the sample after drying at 140 ° C. for 1 hour is N, the volatile content rate (%) = (MN) × 100 / M.
Drying simulation is a method of observing the decrease in volatile fraction during the process of casting a dope and drying it in a small amount of experiment, and simulating the drying behavior in a film forming machine based on the drying constant obtained from the measured value. It is.

The first stretching of the present invention is preferably performed at a stretching ratio of 1.03 times to 2 times, more preferably at a stretching ratio of 1.1 times to 1.5 times, and particularly preferably 1.15 times to 1 times. Performed at a draw ratio of 3 times. Drawing at a draw ratio of 2 times or less is preferable in that the risk of film breakage is low. Moreover, 1.03 times or more is preferable at the point which the elasticity modulus of a 1st extending | stretching direction is enough.
The second stretching of the film is preferably performed at a stretching ratio of 1.10 times to 2 times, more preferably at a stretching ratio of 1.2 times to 1.5 times, and particularly preferably from 1.25 times to It is carried out at a draw ratio of 1.3 times. Drawing at a draw ratio of 2 times or less is preferable in that the risk of film breakage is low. Moreover, 1.10 times or more is preferable at a point with sufficient retardation value.

  The retardation of the cellulose acylate film can be adjusted by the stretching treatment according to the present invention. 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.

(Elastic modulus)
In the cellulose acylate film of the present invention, the ratio (A / B) of the elastic modulus (A) in the film conveyance direction and the elastic modulus (B) in the direction substantially orthogonal to the conveyance direction is 0.8 to 1.2. Preferably there is. More preferably, it is 0.85-1.15, Most preferably, it is 0.9-1.1. A / B is preferably 0.8 or more and 1.2 or less in that the anisotropy of the elastic modulus is small and the light leakage is small.
In the cellulose acylate film of the present invention, both the film transport direction and the elastic modulus in the direction substantially perpendicular to the transport direction are preferably 3000 MPa or more and 10,000 MPa or less, more preferably 4500 MPa or more and 9000 MPa or less, and particularly preferably. Is 5300 MPa or more and 8000 MPa or less. The elastic modulus of the film is preferably 3000 MPa or more in that the dimensional change of the polarizing plate is small and light leakage is less likely to occur. Moreover, 10000 MPa or less is preferable at the point which is not too brittle and a crack and a chip | tip are hard to generate | occur | produce at the edge part of a film.
In the present invention, the elastic modulus is a tensile elastic modulus and can be measured by the following method.
Measurement method: 10 mm × 200 mm of sample is conditioned at 25 ° C., 60% RH for 2 hours, using a tensile tester (Strograph-R2 (manufactured by Toyo Seiki)) with an initial sample length of 100 mm and a tensile rate of 10 mm / min. Is calculated from the stress and elongation at the initial stage of tension.

(Optical properties of cellulose acylate film)
The front retardation value Re and the retardation value Rth in the film thickness direction of the cellulose acylate film of the present invention are preferably 30 ≦ Re ≦ 200 nm and 70 ≦ Rth ≦ 350 nm. More preferably, 40 ≦ Re ≦ 150 nm and 100 ≦ Rth ≦ 280 nm, and particularly preferably 50 ≦ Re ≦ 100 nm and 160 ≦ Rth ≦ 220 nm.
The front retardation value Re and the retardation value Rth in the film thickness direction were 25 ° C. and 60% R.D. H. Is a value measured by making 590 nm light incident.

In this specification, Re (λ) and Rth (λ) represent in-plane retardation and retardation in the thickness direction at a wavelength λ, respectively. Re (λ) is measured by making light with a wavelength of λ nm incident in the normal direction of the film in KOBRA 21ADH or WR (manufactured by Oji Scientific Instruments).
When the film to be measured is represented by a uniaxial or biaxial refractive index ellipsoid, Rth (λ) is calculated by the following method.
Rth (λ) is Re (λ), with the in-plane slow axis (determined by KOBRA 21ADH or WR) as the tilt axis (rotating axis) (if there is no slow axis, any in-plane The light is incident at a wavelength of λ nm from the inclined direction in steps of 10 degrees from the normal direction to 50 degrees on one side with respect to the film normal direction of KOBRA 21ADH or WR is calculated based on the measured retardation value, the assumed average refractive index, and the input film thickness value.
In the above case, in the case of a film having a direction in which the retardation value is zero at a certain tilt angle with the in-plane slow axis from the normal direction as the rotation axis, retardation at a tilt angle larger than the tilt angle. The value is calculated by KOBRA 21ADH or WR after changing the sign to negative.
In addition, the retardation value is measured from the two inclined directions, with the slow axis as the tilt axis (rotation axis) (in the absence of the slow axis, the arbitrary direction in the film plane is the rotation axis), Rth can also be calculated from the following formula (1) and formula (2) based on the value, the assumed value of the average refractive index, and the input film thickness value.
Formula (1)

The above Re (θ) represents a retardation value in a direction inclined by an angle θ from the normal direction.
In formula (1), nx represents the refractive index in the slow axis direction in the plane, ny represents the refractive index in the direction perpendicular to nx in the plane, and nz represents the refractive index in the direction perpendicular to nx and ny. .
Rth = ((nx + ny) / 2-nz) xd --- Formula (2)
In the case where the film to be measured cannot be expressed by a uniaxial or biaxial refractive index ellipsoid, that is, a film without a so-called optic axis, Rth (λ) is calculated by the following method.
Rth (λ) is from −50 degrees to +50 degrees with respect to the normal direction of the film, with Re (λ) as the slow axis (indicated by KOBRA 21ADH or WR) in the plane and the tilt axis (rotation axis). Measured at 11 points with light of wavelength λ nm from each inclined direction in 10 degree steps, and KOBRA 21ADH or based on the measured retardation value, average refractive index assumption and input film thickness value Calculated by WR.
In the above measurement, as the assumed value of the average refractive index, the values in the polymer handbook (JOHN WILEY & SONS, INC) and catalogs of various optical films can be used. Those whose average refractive index is not known can be measured with an Abbe refractometer. The average refractive index values of main optical films are exemplified below: cellulose acylate (1.48), cycloolefin polymer (1.52), polycarbonate (1.59), polymethyl methacrylate (1.49), Polystyrene (1.59). By inputting these assumed values of average refractive index and film thickness, KOBRA 21ADH or WR calculates nx, ny, and nz. Nz = (nx-nz) / (nx-ny) is further calculated from the calculated nx, ny, and nz.

When the cellulose acylate film has such Re and Rth, a high-performance liquid crystal display device can be produced.
The variation in the Re value over the entire width is preferably ± 5 nm, and more preferably ± 3 nm. Further, the variation of the Rth value is preferably ± 10 nm, and more preferably ± 5 nm. Further, it is preferable that the variation in the Re value and the Rth value in the length direction is also within the range of the variation in the width direction.

  In the present invention, the thickness of the finished cellulose acylate film (after drying) varies depending on the purpose of use, but is preferably in the range of 20 to 110 μm, more preferably 40 to 95 μm, and even more preferably 40 to 75 μm. Thinning of a film is demanded by a panel maker, and the demand from the panel maker can be met by using the film thickness of the present invention. In addition, the reduction in the thickness leads to the reduction of raw materials, so that the cost can be reduced. A film thickness of 20 μm or more is preferable in that the film is not too thin and the handleability is good. Moreover, there is a request from a panel manufacturer to make the film member as thin as possible, and 110 μm or less is preferable because it is not too thick. 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.

(Cellulose acylate)
First, the specific cellulose acylate preferably used in the present invention will be described in detail. In the present invention, two or more different cellulose acylates may be mixed and used.

  The cellulose acylate used in the present invention is a cellulose ester obtained by substituting a hydroxyl group of cellulose with an acetyl group, and / or a cellulose ester obtained by substituting an acetyl group and an acyl group having 3 or more carbon atoms. It is a mixed fatty acid ester, and is preferably a cellulose acylate satisfying the following mathematical formulas (I) and (II) in terms of the degree of substitution of cellulose with a hydroxyl group.

Formula (I): 2.0 ≦ A + B ≦ 3.0
Formula (II): 0 ≦ B

  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.

  Glucose units having β-1,4 bonds constituting cellulose have free hydroxyl groups at the 2nd, 3rd and 6th positions. Cellulose acylate is a polymer obtained by esterifying some or all of these hydroxyl groups with acyl groups. The degree of acyl substitution means the proportion of cellulose esterified at each of the 2-position, 3-position and 6-position (100% esterification has a degree of substitution of 1).

In the present invention, the total sum (A + B) of the degree of substitution of hydroxyl groups A and B is preferably 2.0 to 3.0, more preferably 2.2 to 2.9, as shown in the above formula (I). And particularly preferably 2.40 to 2.85. Further, the substitution degree of B is preferably a value of 0 or more as shown in the above formula (II).
A + B is preferably 2.0 or more from the viewpoint that the hydrophilicity does not become too strong and is hardly affected by the environmental humidity.

  When B> 0, the total substitution degree of A and B of the 6-position hydroxyl group of cellulose acylate is preferably 0.6 or more, more preferably 0.75 or more, and particularly preferably 0.85 or more. 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, particularly 32% or more. Is preferably the substitution degree of the 6-position hydroxyl group.

The acyl group having 3 or more carbon atoms may be an aliphatic acyl group or an arylacyl group, and is not particularly limited. The cellulose acylate used in the present invention is, for example, cellulose alkylcarbonyl ester, alkenylcarbonyl ester, aromatic carbonyl ester, aromatic alkylcarbonyl ester or the like, and each may further have a substituted group. Preferred examples of the acyl group include propionyl, butanoyl, keptanoyl, hexanoyl, octanoyl, decanoyl, dodecanoyl, tridecanoyl, tetradecanoyl, hexadecanoyl, octadecanoyl, iso-butanoyl, t-butanoyl, cyclohexanecarbonyl, oleoyl, Examples thereof include benzoyl, naphthylcarbonyl, cinnamoyl and the like. Among these, a propionyl group, a butanoyl group, a dodecanoyl group, an octadecanoyl group, a t-butanoyl group, an oleoyl group, a benzoyl group, a naphthylcarbonyl group, a cinnamoyl group, and the like are more preferable, and a propionyl group and a butanoyl group are particularly preferable. is there.
In the case of a propionyl group, the substitution degree B is preferably 0.6 or more, more preferably 0.7 or more, and particularly preferably 0.75 or more. These cellulose acylates have high retardation development properties, and a film that exhibits a high retardation value can be produced.

  Further, DS6 / (DS2 + DS3 + DS6) is preferably 0.315 or more, particularly preferably 0.320 or more. The above range is particularly preferred when B = 0. Here, DS2 is the degree of substitution of the hydroxyl group at the 2-position of the glucose unit with an acyl group (hereinafter also referred to as “degree of acyl substitution at the 2-position”), and DS3 is the degree of substitution of the hydroxyl group at the 3-position with an acyl group (hereinafter, referred to as “acyl group”). DS6 is the substitution degree of the hydroxyl group at the 6-position with an acyl group (hereinafter also referred to as “acyl substitution degree at the 6-position”). Further, DS2 + DS3 + DS6 is preferably 2.00 to 2.85, more preferably 2.22 to 2.82, and particularly preferably 2.40 to 2.80. This cellulose acylate has a high retardation development property, and a film exhibiting a high retardation value can be produced.

(Method for synthesizing cellulose acylate)
The basic principle of the cellulose acylate synthesis method is described in Mita et al., “Wood Chemistry”, Kyoritsu Shuppan, 1968, pages 180-190. 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 the acylation reaction is completed, a neutralizing agent (for example, calcium, magnesium, iron, aluminum or zinc is used to neutralize a part of the hydrolysis and esterification catalyst of excess carboxylic anhydride remaining in the system. 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 the 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 into the cellulose acylate solution) to coagulate and separate the cellulose acylate, and the cellulose acylate is obtained by washing and stabilizing treatment.

  In the cellulose acylate film of the present invention, 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. Cellulose acylate particles are preferably used as a raw material for film production. 90% by mass or more of the particles to be used preferably have a particle diameter of 0.5 to 5 mm. Moreover, it is preferable that 50 mass% or more of the particle | grains to be used have a particle diameter of 1-4 mm. The cellulose acylate particles preferably have a shape as close to a sphere as possible. The bulk specific gravity (apparent density) of the particles thus produced is preferably 0.3 to 0.8 kg / L. The bulk density is preferably in the above range from the viewpoint that it is difficult to cause bridging when it is introduced into the dissolution tank from the silo and is excellent in solubility. Therefore, a more preferable bulk specific gravity is 0.4 to 0.6. The particle diameter and bulk specific gravity are adjusted by adjusting the stirring speed and aggregation speed when agglomerating and precipitating.

  The degree of polymerization of the cellulose acylate preferably used in the present invention is preferably a viscosity average degree of polymerization of 200 to 700, more preferably 250 to 550, still more preferably 250 to 400, and particularly preferably a viscosity average degree of polymerization of 265 to 380. It is. 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. The viscosity average degree of polymerization is determined from the intrinsic viscosity [η] of cellulose acylate measured with an Ostwald viscometer by the following formula.

Viscosity average degree of polymerization DP = [η] / Km
{Where [η] is the intrinsic viscosity of cellulose acylate, and Km is a constant of 6 × 10 ⁻⁴ . }

  The cellulose acylate used in the present invention preferably has a narrow molecular weight distribution represented by Mw / Mn (Mw is a mass average molecular weight, Mn is a number average molecular weight) by gel permeation chromatography. Specifically, the value of Mw / Mn is preferably 0.8 to 2, and more preferably 1 to 1.8. When the low molecular component is removed, the average molecular weight (degree of polymerization) increases, but the viscosity becomes lower than that of normal cellulose acylate, which is useful. Cellulose acylate having a small amount of low molecular components can be obtained by removing low molecular components from cellulose acylate synthesized by a usual method. The removal of the low molecular component can be carried out by washing the cellulose acylate with an appropriate organic solvent. In addition, when manufacturing a cellulose acylate with few low molecular components, it is preferable to adjust the sulfuric acid catalyst amount in an acetylation reaction to 0.5-25 mass parts with respect to 100 mass parts of cellulose. When the amount of the sulfuric acid catalyst is in the above range, cellulose acylate that is preferable in terms of molecular weight distribution (uniform molecular weight distribution) can be synthesized.

  These cellulose acylates of the present invention are described in detail on pages 7 to 12 in the raw material cotton and the synthesis method in the Japan Society for Invention and Innovation Technical Bulletin No. 2001-1745 (issued on March 15, 2001, Japan Society for Invention). It is described in.

(Additive)
In the cellulose acylate solution according to the present invention, various additives (for example, plasticizers, ultraviolet inhibitors, deterioration inhibitors, retardation (optical anisotropy) modifiers, fine particles, Peeling accelerators, infrared absorbers, etc.) can be added and they can be solid or oily. That is, the melting point and boiling point are not particularly limited. For example, mixing of ultraviolet absorbing materials at 20 ° C. or lower and 20 ° C. or higher, and similarly mixing of a plasticizer is described in, for example, Japanese Patent Application Laid-Open No. 2001-151901. Examples of the peeling accelerator include citric acid ethyl esters. Furthermore, infrared absorbing dyes are described, for example, in JP-A No. 2001-194522. Moreover, the addition time may be added at any stage in the dope preparation process, but may be performed by adding an additive to the final preparation process of the dope preparation process. Furthermore, the amount of each material added is not particularly limited as long as the function is manifested. Moreover, when a cellulose acylate film is formed in a multilayer, the kind and addition amount of the additive of each layer may differ. Examples thereof are described in Japanese Patent Application Laid-Open No. 2001-151902 and the like, but these are conventionally known techniques.
Further, for these details, materials described in detail on page 16 and after in the Invention Association Public Technical Bulletin No. 2001-1745 (issued on March 15, 2001, Invention Association) are preferably used.

(Plasticizer)
The film of the present invention may contain a plasticizer. Although it does not specifically limit as a plasticizer which can be used, Triphosphate, tricresyl phosphate, cresyl diphenyl phosphate, octyl diphenyl phosphate, diphenyl biphenyl phosphate, trioctyl phosphate, tributyl phosphate, etc. In acid ester systems, diethyl phthalate, dimethoxyethyl phthalate, dimethyl phthalate, dioctyl phthalate, dibutyl phthalate, di-2-ethylhexyl phthalate, etc., in glycolic acid ester systems, triacetin, tributyrin, butyl phthalyl butyl glycolate, ethyl phthalyl ethyl Less cellulose acylate such as glycolate, methyl phthalyl ethyl glycolate, butyl phthalyl butyl glycolate Specific preferred to singly or in combination one. Two or more plasticizers may be used in combination as required. By using a plasticizer, the cellulose acylate film can be stretched at a high magnification. In addition, by using a compound that is more hydrophobic than cellulose acylate, fluctuations in Re and Rth accompanying changes in humidity can be suppressed.

(Retardation expression agent)
In the present invention, since a high retardation value is expressed, a retardation developer can be preferably used. As the retardation developer, a compound having at least two aromatic rings can be used. The retardation developer is preferably used in the range of 0 to 10% by mass, more preferably in the range of 0 to 7% by mass, based on 100% by mass of the cellulose acylate, and more preferably 0 to 5% by mass. More preferably, it is used in the range of 0.1 to 4% by mass. If this invention is used, since the usage-amount of a retardation developing agent can be reduced, it leads to a cost reduction. It is preferable to add 10% by mass or less of the retardation enhancer to the cellulose acylate in that the retardation enhancer is difficult to precipitate during film formation. One kind may be used, or two or more kinds of retardation developing agents may be used in combination.
The retardation developer preferably has a maximum absorption in the wavelength region of 250 to 400 nm, and preferably has substantially no absorption in the visible region.

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, a benzene ring, a condensed benzene ring, and biphenyls are preferable. In particular, a 1,3,5-triazine ring is preferably used. Specifically, for example, compounds disclosed in JP-A No. 2001-166144 are preferably used.

The number of carbon atoms of the aromatic ring in the retardation enhancer is preferably 2 to 20, more preferably 2 to 12, still more preferably 2 to 8, and more preferably 2 to 6. Most preferred.
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.

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

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

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

  In the present invention, a rod-shaped compound having a linear molecular structure can be preferably used in addition to a compound using a 1,3,5-triazine ring. The linear molecular structure means that the molecular structure of the rod-like compound is linear in the most thermodynamically stable structure. The most thermodynamically stable structure can be obtained by crystal structure analysis or molecular orbital calculation. For example, molecular orbital calculation can be performed using molecular orbital calculation software (eg, WinMOPAC2000, manufactured by Fujitsu Limited) to obtain a molecular structure that minimizes the heat of formation of a compound. The molecular structure being linear means that in the thermodynamically most stable structure obtained by calculation as described above, the angle of the main chain constituting the molecular structure is 140 degrees or more.

As the rod-shaped compound having at least two aromatic rings, a compound represented by the following general formula (10) is preferable.
Formula (10): Ar ¹ -L ¹ -Ar ²

In the general formula (10), Ar ¹ and Ar ² are each independently an aromatic group.
In the present specification, the aromatic group includes an aryl group (aromatic hydrocarbon group), a substituted aryl group, an aromatic heterocyclic group, and a substituted aromatic heterocyclic group.
An aryl group and a substituted aryl group are more preferable than an aromatic heterocyclic group and a substituted aromatic heterocyclic group. The heterocycle of the aromatic heterocyclic group is generally unsaturated. The aromatic heterocycle is preferably a 5-membered ring, 6-membered ring or 7-membered ring, more preferably a 5-membered ring or 6-membered ring. Aromatic heterocycles generally have the most double bonds. As a hetero atom, a nitrogen atom, an oxygen atom or a sulfur atom is preferable, and a nitrogen atom or a sulfur atom is more preferable.
As the aromatic ring of the aromatic group, a benzene ring, a furan ring, a thiophene ring, a pyrrole ring, an oxazole ring, a thiazole ring, an imidazole ring, a triazole ring, a pyridine ring, a pyrimidine ring and a pyrazine ring are preferable, and a benzene ring is particularly preferable. .

  Examples of the substituent of the substituted aryl group and the substituted aromatic heterocyclic group include halogen atom (F, Cl, Br, I), hydroxyl, carboxyl, cyano, amino, alkylamino group (eg, methylamino, ethylamino) , Butylamino, dimethylamino groups), nitro, sulfo, carbamoyl, alkylcarbamoyl groups (eg, N-methylcarbamoyl, N-ethylcarbamoyl, N, N-dimethylcarbamoyl groups), sulfamoyl groups, alkylsulfurates Moyl group (eg, N-methylsulfamoyl, N-ethylsulfamoyl, N, N-dimethylsulfamoyl groups), ureido group, alkylureido group (eg, N-methylureido, N, N- Dimethylureido, N, N, N′-trimethylureido groups), alkyl groups (eg, methyl, ethyl, Propyl, butyl, pentyl, heptyl, octyl, isopropyl, sec-butyl, t-amyl, cyclohexyl, cyclopentyl groups), alkenyl groups (eg, vinyl, aryl, hexenyl groups), alkynyl groups (eg, ethynyl groups) , Butynyl group), acyl group (eg, formyl, acetyl, butyryl, hexanoyl, lauryl groups), acyloxy group (eg, acetoxy, butyryloxy, hexanoyloxy, lauryloxy groups), alkoxy group (eg, methoxy) , Ethoxy, propoxy, butoxy, pentyloxy, heptyloxy, octyloxy groups), aryloxy groups (eg, phenoxy groups), alkoxycarbonyl groups (eg, methoxycarbonyl, ethoxycarbonyl, propoxycarbonyl, butoxycarbonyl, pentyl) Xyloxycarbonyl, heptyloxycarbonyl groups), aryloxycarbonyl groups (eg, phenoxycarbonyl groups), alkoxycarbonylamino groups (eg, butoxycarbonylamino groups, hexyloxycarbonylamino groups), alkylthio groups (eg, methylthio, ethylthio) , Propylthio, butylthio, pentylthio, heptylthio, octylthio group), arylthio group (eg, phenylthio group), alkylsulfonyl group (eg, methylsulfonyl, ethylsulfonyl, propylsulfonyl, butylsulfonyl, pentylsulfonyl, heptylsulfonyl, octylsulfonyl) Groups), amide groups (eg, acetamide, butyramide group, hexylamide, laurylamide groups) and non-aromatic heterocyclic groups (eg, morpholyl groups, pyrazi groups) Le group) include.

Among these, preferred substituents include halogen atoms, cyano groups, carboxyl groups, hydroxyl groups, amino groups, alkylamino groups, acyl groups, acyloxy groups, amide groups, alkoxycarbonyl groups, alkoxy groups, alkylthio groups, and alkyl groups. Can be mentioned.
The alkyl part and alkyl group of the alkylamino group, alkoxycarbonyl group, alkoxy group and alkylthio group may further have a substituent. Examples of the alkyl moiety and the substituent of the alkyl group include halogen atom, hydroxyl group, carboxyl group, cyano group, amino group, alkylamino group, nitro group, sulfo group, carbamoyl group, alkylcarbamoyl group, sulfamoyl group, alkylsulfur group. Famoyl group, ureido group, alkylureido group, alkenyl group, alkynyl group, acyl group, acyloxy group, alkoxy group, aryloxy group, alkoxycarbonyl group, aryloxycarbonyl group, alkoxycarbonylamino group, alkylthio group, arylthio group, An alkylsulfonyl group, an amide group and a non-aromatic heterocyclic group are included. As the substituent for the alkyl moiety and the alkyl group, a halogen atom, a hydroxyl group, an amino group, an alkylamino group, an acyl group, an acyloxy group, an acylamino group, an alkoxycarbonyl group, and an alkoxy group are preferable.

In the general formula (10), L ¹ is a divalent linking group selected from an alkylene group, an alkenylene group, an alkynylene group, —O—, —CO— and a combination thereof.
The alkylene group may have a cyclic structure. As the cyclic alkylene group, cyclohexylene is preferable, and 1,4-cyclohexylene is particularly preferable. As the chain alkylene group, a linear alkylene group is more preferable than a branched alkylene group.
The 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 number of carbon atoms of the alkenylene group and the alkynylene group is preferably 2 to 10, more preferably 2 to 8, further preferably 2 to 6, further preferably 2 to 4, and most preferably 2. (Vinylene group or ethynylene group).
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 (10), the angle formed by Ar ¹ and Ar ² across L ¹ is preferably 140 degrees or more.
As the rod-like compound, a compound represented by the following general formula (20) is more preferable.

Formula ^{(20): Ar 1 -L 2} -X-L 3 -Ar 2
In the general formula (20), Ar ¹ and Ar ² are each independently an aromatic group. The definition and examples of the aromatic group are the same as those for Ar ¹ and Ar ^{2 in} the general formula (10).

In the general formula (20), L ² and L ³ are each independently a divalent linking group selected from an alkylene group, —O—, —CO—, and a group consisting of a combination thereof.
The alkylene group preferably has a chain structure rather than a cyclic structure, and more preferably has a linear structure rather than a branched chain structure.
The alkylene group preferably has 1 to 10 carbon atoms, more preferably 1 to 8, still more preferably 1 to 6, still more preferably 1 to 4, and 1 or 2 (methylene group). Or ethylene group).
L ² and L ³ are particularly preferably —O—CO— or —CO—O—.

In the general formula (20), X represents a 1,4-cyclohexylene group, a vinylene group or an ethynylene group.
The specific example of a compound represented by General formula (10) below is shown.

  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.
A compound represented by the following general formula (3) is also preferable.

(In the formula, R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁹ and R ¹⁰ each independently represent 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.)

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 with reference to methods described in 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).

Next, the organic solvent in which the cellulose acylate of the present invention is dissolved will be described.
(Chlorine solvent)
In preparing the cellulose acylate solution of the present invention, a chlorinated organic solvent is preferably used as the main solvent. In the present invention, the type of the chlorinated organic solvent is not particularly limited as long as the object can be achieved within 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 preferable to use at least 50% by mass of dichloromethane. The non-chlorine organic solvent used in combination with the chlorinated organic solvent in the present invention is described below. That is, as a preferable non-chlorine 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, t-butanol, 1-pentanol, 2-methyl-2-butanol and cyclohexanol. As the alcohol, fluorine-based alcohol is also used. Examples thereof include 2-fluoroethanol, 2,2,2-trifluoroethanol, 2,2,3,3-tetrafluoro-1-propanol and the like. Furthermore, the hydrocarbon may be linear, branched or cyclic. Either aromatic hydrocarbons or aliphatic hydrocarbons can be used. The aliphatic hydrocarbon may be saturated or unsaturated. Examples of hydrocarbons include cyclohexane, hexane, benzene, toluene and xylene.
Although the following can be mentioned as a combination of the chlorinated organic solvent which is a preferable main solvent of this invention, It is not limited to these.

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

(Non-chlorine solvent)
Next, a non-chlorine organic solvent that is preferably used in preparing the cellulose acylate solution of the present invention will be described. In the present invention, the non-chlorine organic solvent is not particularly limited as long as the object can be achieved 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, a preferred solvent for the cellulose acylate of the present invention is a mixed solvent of three or more different from each other, and the first solvent is selected from methyl acetate, ethyl acetate, methyl formate, ethyl formate, acetone, dioxolane, and dioxane. And at least one kind or a mixture thereof, the second solvent is selected from ketones having 4 to 7 carbon atoms or acetoacetate, and the third solvent is alcohol or hydrocarbon having 1 to 10 carbon atoms More preferably, it is a C1-C8 alcohol. Note that when the first solvent is a mixed liquid of two or more kinds of solvents, the second solvent may be omitted. The first solvent is more preferably methyl acetate, acetone, methyl formate, ethyl formate, or a mixture thereof, and the second solvent is preferably methyl ethyl ketone, cyclopentanone, cyclohexanone, or methyl acetyl acetate. It may be.

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

  The above three types of mixed solvents preferably contain a first solvent in a proportion of 20 to 95% by mass, a second solvent in a proportion of 2 to 60% by mass, and a third solvent in a proportion of 2 to 30% by mass, Furthermore, it is preferable that a 1st solvent is 30-90 mass%, a 2nd solvent is 3-50 mass%, and also 3-25 mass% of 3rd alcohol is contained. 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. In addition, when the first solvent is a mixed solution and the second solvent is not used, the first solvent is preferably contained in a ratio of 20 to 90% by mass and the third solvent in a ratio of 5 to 30% by mass, Furthermore, it is preferable that a 1st solvent is 30-86 mass%, and also a 3rd solvent is contained 7-25 mass%. The non-chlorine-based organic solvent used in the present invention is more specifically described in pages 12 to 16 of the Japan Society for Invention and Innovation Technical Bulletin No. 2001-1745 (issued on March 15, 2001, Japan Society for Invention). It is described in detail. Preferred combinations of non-chlorine organic solvents of the present invention can be listed below, but are not limited thereto.

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

Methyl formate / methyl ethyl ketone / acetone / methanol / ethanol (50/20/20/5/5, parts by mass),
-Methyl formate / acetone / ethyl acetate / ethanol / butanol / hexane (65/10/10/5/5/5, parts by mass)
Acetone / methyl acetoacetate / methanol / ethanol (65/20/10/5, parts by mass)
Acetone / cyclopentanone / ethanol / butanol (65/20/10/5, parts by mass)
Acetone / 1,3 dioxolane / ethanol / butanol (65/20/10/5, part by mass),
1,3 dioxolane / cyclohexanone / methyl ethyl ketone / methanol / butanol (60/20/10/5/5, parts by mass)
And so on.

Furthermore, a cellulose acylate solution can also be used by the following method.
-Prepare cellulose acylate solution with methyl acetate / acetone / ethanol / butanol (81/8/7/4, parts by mass) and add 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 was prepared, and after filtration and concentration, 4 parts by weight of butanol was added additionally. In methyl acetate / acetone / ethanol (84/10/6, parts by mass) Make a cellulose acylate solution, add 5 parts by weight of butanol after filtration and concentration

(Characteristics of cellulose acylate solution)
In the present invention, the cellulose acylate solution preferably contains 10-30% by mass of solid components such as cellulose acylate and additives in an organic solvent, more preferably 13-27% by mass, and still more preferably. It is preferably 15 to 25% by mass, particularly preferably 20 to 25% by mass. The method for preparing cellulose acylate at these concentrations may be a predetermined concentration at the stage of dissolution, or after preparing in advance as a low concentration solution (for example, 9 to 14% by mass), by a concentration step described later. You may adjust to a predetermined high concentration solution. 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 can be used for the cellulose acylate of the present invention. If it is prepared so that it may become the said solution concentration range, there will be no problem in particular. In the present invention, in order to reduce the volatile content of the cellulose acylate film immediately before stretching, it is an effective means to set the concentration of the cellulose acylate solution before casting higher than usual.

Next, in this invention, it is preferable that the aggregate molecular weight of the cellulose acylate of 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 aggregate molecular weight is 180,000 to 9 million. This aggregate 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, definitions of the molecular weight of the aggregate, the inertial square radius, and the second virial coefficient will be described. These were measured using the static light scattering method according to the following method. Although the measurement was 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 was 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 was dried at 120 ° C. for 2 hours and measured at 25 ° C. and 10% RH. The dissolution method was carried out according to the method employed at the time of dope dissolution (room temperature dissolution method, cooling dissolution method, high temperature dissolution method). Subsequently, these solutions and the solvent were filtered through a 0.2 μm Teflon (registered trademark) filter. The filtered solution was measured for static light scattering at intervals of 10 degrees from 30 degrees to 140 degrees at 25 ° C. using a light scattering measuring device (DLS-700 manufactured by Otsuka Electronics Co., Ltd.). The obtained data was analyzed by the BERRY plot method. In addition, the refractive index required for this analysis uses the value of the solvent calculated | required with the Abbe refractive system, and the refractive index gradient (dn / dc) uses the differential refractometer (Otsuka Electronics Co., Ltd. product DRM-1021). The measurement was performed using the solvent and the solution used for the light scattering measurement.

(Dope preparation)
Next, preparation of the cellulose acylate solution (dope) in the present invention will be described.
The dissolution method 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-10-95854 -45950, JP-A-2000-53784, JP-A-11-322946, JP-A-11-322947, JP-A-2-276830, JP-A-2000-273239, JP-A-11-. No. 71463, JP-A No. 04-259511, JP-A No. 2000-273184, JP-A No. 11-323017, JP-A No. 11-302388, etc. describe methods for preparing cellulose acylate solutions. The above-described method for dissolving cellulose acylate in an organic solvent can appropriately apply these techniques to the present invention within the scope of the present invention. These details are described in detail on pages 22 to 25 in the non-chlorine-based solvent system, especially in the Japan Society for Invention and Innovation Technical Bulletin No. 2001-1745 (issued on March 15, 2001, Japan Society for Invention). Can be done in any way. Further, the cellulose acylate dope solution of the present invention is usually subjected to solution concentration and filtration. Similarly, the dope solution of the Japan Society of Invention and Innovation is published as No. 2001-1745 (issued on March 15, 2001, Invention Association). It is described in detail on the page. 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.

  As described above, the concentration of the cellulose acylate solution is characterized in that a high-concentration dope can be obtained, and a cellulose acylate solution having a high concentration and excellent stability can be obtained without depending on the means of concentration. 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), blowing a low-concentration solution from the nozzle into 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.) and the like can be used.

  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 filtration of the cellulose acylate solution, a filter having an absolute filtration accuracy of 0.1 to 100 μm is preferably used, and a filter having an absolute filtration accuracy of 0.5 to 25 μm is preferably used. The thickness of the filter is preferably 0.1 to 10 mm, and more preferably 0.2 to 2 mm. In that case, the filtration pressure is preferably 1.6 MPa or less, more preferably 1.2 MPa or less, further 1.0 MPa or less, 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.

In the present invention, the cellulose acylate solution is preferably adjusted to have a certain range of viscosity. The viscosity is measured using, for example, a stress rheometer (CVO 120) manufactured by Bohlin Instruments, about 1 mL of the sample solution. Viscosity (unit: Pas) is measured under the condition of applying a displacement of 1% at a dope temperature of 33 ° C. and a frequency of 1 Hz.
The preferred viscosity is 10 to 70 Pas (measurement temperature 33 ° C.). If the viscosity is higher than this range, the fluidity is poor and filtration or casting becomes difficult. If the viscosity is lower than this range, the internal pressure of the casting die is reduced. It becomes low and cannot be uniformly cast in the width direction, and the thickness variation in the width direction tends to increase. The viscosity of the dope is more preferably 15 to 45 Pas, and most preferably 20 to 35 Pas.
If the solution viscosity is in the above-mentioned range, the burden of filtration is reduced. Therefore, it is possible to use a filter medium having a smaller pore diameter and higher accuracy than the conventional one. As a result, the cellulose acylate film of the present invention has less foreign matter, and in particular, when incorporated in a liquid crystal display device and displaying black, it is possible to reduce so-called bright spot foreign matter that shines due to light leakage. .

(Film formation)
Subsequently, the manufacturing method of the film using the said cellulose acylate solution is described.
In the production method of the present invention, a cellulose acylate solution is cast on a metal support to form a film, and then stretched at Tg + 0 to 60 ° C. in a volatile fraction region of 30 to 65% by mass. After the first stretching step, after the first stretching step, a second stretching step is performed in which stretching is performed in a direction substantially orthogonal to the first stretching step at Tg + 0 to 60 ° C. in a volatile fraction region of 0 to 35% by mass.
As a method and equipment for producing the cellulose acylate film of the present invention, a solution casting film forming method and a solution casting film forming apparatus conventionally used for producing a cellulose triacetate film are preferably used.
Although the example of the manufacturing method preferable to this invention is given to the following, if it is in the range of the manufacturing method of this invention, it will not be limited to this.

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

First, when the prepared cellulose acylate solution (dope) is used to produce a cellulose acylate film by the solvent cast method, the dope is cast on a drum or a band, and the solvent is evaporated to form a film. It is preferable to adjust the concentration of the dope before casting so that the solid content is 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-A Nos. 2000-301555, 2000-301558, 7-032391, JP-A-3-193316, JP-A-5-086212, JP-A-62-237113, JP-A-2-276607. The techniques described in JP-A-55-014201, JP-A-2-111511, and JP-A-2-208650 can be applied 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.

  Alternatively, a film may be formed by casting a cellulose acylate solution from two casting ports. For example, JP-B-60-27562, JP-A-61-94724, JP-A-61-947245, JP-A-6-247245 It can be carried out by the methods described in JP-A-61-104813, JP-A-61-158413, and JP-A-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, the membrane cast on the metal support is peeled off by the first casting port, and the second casting is performed on the side that is in contact with the metal support surface. For example, it is a method described in Japanese Patent Publication No. 44-20235. The cellulose acylate solutions to be cast may be the same solution or different cellulose acylate solutions, and are not particularly limited. In order to give a function to a plurality of cellulose acylate layers, a cellulose acylate solution corresponding to the function may be extruded from each casting port. Furthermore, the cellulose acylate solution can be cast by simultaneously casting other functional layers (for example, an adhesive layer, a dye layer, an antistatic layer, an antihalation layer, a UV absorbing layer, a polarizing layer).

  In the conventional single-layer liquid, it is necessary to extrude a cellulose acylate solution having a high concentration and a high viscosity in order to obtain a required film thickness. In many cases, the problem occurs, such as a failure 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. In addition to being able to be produced, the use of a concentrated cellulose acylate solution could achieve a reduction in drying load and increase the production speed of the membrane.

  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. In addition, the type of plasticizer and ultraviolet absorber can be changed between the core layer and the skin layer. For example, the skin layer contains a low-volatile plasticizer and / or an ultraviolet absorber, and the core layer has excellent plasticity. It is also possible to add a 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 steps may be at the same temperature or may be different at different points in the step. If they are different, it may be a desired temperature just before casting.

  The drying of the dope on the metal support involved in the production of the cellulose acylate film (drying here means drying after casting and immediately before stretching) is generally a metal support (drum or belt). The surface side of the web, that is, the method of applying hot air from the surface of the web on the metal support, the method of applying hot air from the back side of the drum or belt, the back side of the temperature-controlled liquid opposite to the belt or drum dope casting surface There is a liquid heat transfer method in which the drum or belt is heated by heat transfer to control the surface temperature, and the back surface liquid heat transfer method is preferred. 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 degrees 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.

  The production method of the present invention includes a first stretching step and a second stretching step after the casting and film formation, and the stretching is as described above.

  The width of the cellulose acylate film is preferably 0.5 to 3 m, more preferably 0.6 to 2.5 m, and still more preferably 0.8 to 2.2 m. The length is preferably 100 to 10000 m per roll, more preferably 500 to 7000 m, and still more preferably 1000 to 6000 m. When winding, it is preferable to give a knurling 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 1 to 50 μm, more preferably 2 to 20 μm, even more preferably. Is 3 to 10 μm. This may be a single push or a double push.

(Change in water content and optical properties)
The change in the display performance of the liquid crystal display device accompanying a change in humidity is due to a change in Re and Rth accompanying a change in the moisture content of the film on the cell side of the polarizer. By reducing the moisture content, the accompanying humidity change in Re and Rth can be reduced.

The water content of the film is preferably 0 to 2.8% by mass, more preferably 0 to 2.4% by mass, and particularly preferably 0 to 1.5% by mass.
In the cellulose acylate film, the values of Re and Rth change with changes in humidity, but the moisture content change at this time is preferably as small as possible.
Cellulose acylate films have a Re ₍₅₉₀₎ at 25 ° C. of 10, 60 and 80% RH of Re _{( 590)} 10% RH, Re ₍₅₉₀₎ 60% RH and Re ₍₅₉₀₎ 80% RH, 25 ° C. of 10, 60 and 80% _Rth of _(590), respectively _Rth (590) in RH _{10% RH,} when the _{Rth (590)} 60% RH and _{Rth (590)} 80% RH, satisfying the following formulas (a) and (B) It is preferable.

(A): 0 <(Re ₍₅₉₀₎ 10% RH-Re ₍₅₉₀₎ 80% RH) × 100 / Re ₍₅₉₀₎ 60% RH <20
(B): 0 <(Rth ₍₅₉₀₎ 10% RH-Rth ₍₅₉₀₎ 80% RH) × 100 / Rth ₍₅₉₀₎ 60% RH <20

More preferably, it is satisfy | filling following formula (C) and (D).
(C): 0 <(Re ₍₅₉₀₎ 10% RH-Re ₍₅₉₀₎ 80% RH) × 100 / Re ₍₅₉₀₎ 60% RH <15
(D): 0 <(Rth ₍₅₉₀₎ 10% RH-Rth ₍₅₉₀₎ 80% RH) × 100 / Rth ₍₅₉₀₎ 60% RH <15

Most preferably, the following formulas (E) and (F) are satisfied.
(E): 0 <(Re ₍₅₉₀₎ 10% RH-Re ₍₅₉₀₎ 80% RH) × 100 / Re ₍₅₉₀₎ 60% RH <10
(F): 0 <(Rth ₍₅₉₀₎ 10% RH-Rth ₍₅₉₀₎ 80% RH) × 100 / Rth ₍₅₉₀₎ 60% RH <10
In order to reduce changes in optical properties due to humidity, in addition to increasing the number of knots in the cellulose acylate film, cellulose acylate with a high degree of acyl substitution at the 6-position and various hydrophobic additives (plasticizer, retardation expression) Agents, ultraviolet absorbers, etc.) can also be used.

(Moisture permeability)
As described above, the cellulose acylate film changes its Re value and Rth value with changes in environmental humidity. This change corresponds to a change in the amount of moisture in the film. By reducing the moisture permeability of the film, it is possible to make it difficult for a change in the amount of water accompanying an abrupt change in environmental humidity to occur, and to suppress changes in the Re value and Rth value.
The preferable moisture permeability of the cellulose acylate film of the present invention is 0 to 2500 g / (m ² · day) per square meter at 60 ° C. and 95% RH for 24 hours. More preferably, it is 200-2000 g / (m < ² > * day), and 400-1500 g / (m < ² > * day) is especially preferable. The above range is preferable in that moisture hardly enters and exits the film and the film optical performance is not easily affected by environmental humidity.
The moisture permeability measurement in the present invention is performed by the cup method. The moisture permeability per square meter was calculated at 60 ° C. and 95% RH for 24 hours.

(Roughness etc.)
The cellulose acylate film of the present invention preferably has a maximum height difference (PV value) of 0 to 1 μm, and an RMS value of the film thickness represented by the following formula is 0 to 0.07 μm. It is preferable that the difference between the maximum value and the minimum value of the orientation angle distribution is 0 to 0.40 degrees.

d _i : difference between the film thickness at the measurement point within the range of 60 mm in diameter and the average film thickness within the same range, N: the number of points at which the film thickness is measured within the range of 60 mm in diameter

Here, the maximum height difference (PV value) of the film thickness and the RMS value of the film thickness were measured by a FUJINON fringe analyzer (FX-03). At this time, the measurement area was in the range of φ = 60 mm.
The RMS value can also be obtained using other devices such as a laser displacement meter and a contact-type film thickness meter. In this case, the film thickness is measured using a laser displacement meter, a contact-type film thickness meter, or the like for at least 200 points within a diameter of 60 mm around an arbitrary point in the film, and an average value of the film thickness is obtained. Then, the difference between the average value of the film thickness and the film thickness at each measurement point is calculated to obtain Δd _i , and the RMS value can be obtained by applying this to the above equation.

  The preferred range of the film thickness (P-V value) measured in this way is 0 to 1 μm, more preferably 0 to 0.8 μm, still more preferably 0 to 0.6 μm, Most preferably, it is 0-0.4 micrometer.

  A preferable range of the RMS value of the film thickness is 0 to 0.07 μm, more preferably 0 to 0.06 μm, still more preferably 0 to 0.05 μm, and most preferably 0 to 0.04 μm. is there. Thus, the cellulose acylate film excellent in flatness is less likely to cause unevenness when the polarizing plates are bonded together, and can provide a panel without unevenness. A cellulose acylate film having a (PV value) of 1 μm or less and / or RMS of 0.07 μm or less is preferred in terms of non-uniformity.

  The orientation angle distribution of the cellulose acylate film was measured by OPTIPRO (XY scanning stage, halogen lamp light + 550 nm interference filter). At this time, the measurement area was 60 mm × 60 mm, and measurement was performed at intervals of 4 mm using a beam with a diameter of 3 mm.

  A preferable range of the difference between the maximum value and the minimum value of the orientation angle distribution in the range of 60 mm × 60 mm measured in this way is 0 to 0.40 degrees, more preferably 0 to 0.30 degrees. Yes, more preferably 0 to 0.20 degrees, and most preferably 0 to 0.10 degrees. Thus, the cellulose acylate film having an improved orientation angle distribution in a minute region can remarkably improve unevenness during crossed Nicol observation, and can provide a panel without unevenness. A cellulose acylate film having a difference between the maximum value and the minimum value of the orientation angle distribution of 0.40 degrees or less is preferable in that unevenness is not noticeable.

(Haze)
In order to increase the front contrast of the liquid crystal display device, it is effective to reduce the haze of the cellulose acylate film. The increase in haze value is caused by the occurrence of microscopic crazing (cracking) of the cellulose acylate film due to stretching. Crazing occurs when the entanglement between cellulose acylate chains disappears by stretching. Since there are many nodal points in the low volatile content region, the entanglement between the cellulose acylate chains is strong, and the entanglement does not disappear even if stretched, so that crazing can be reduced.
As a specific value, the haze value is preferably 0 to 1.0%. More preferably, it is 0-0.8%, Most preferably, it is 0-0.6%. In addition, in order to reduce haze by means other than suppressing crazing, the matting agent to be added is sufficiently dispersed to reduce the number of agglomerated particles, or to reduce the amount of addition, a matting agent is added only to the skin layer. Or use it. It is also effective to remove insoluble matters contained in cellulose acylate and additives.

(Retardation film)
A retardation film can be obtained by using the cellulose acylate film of the present invention.
The retardation film is also referred to as an optical compensation sheet, and is usually used for eliminating image coloring of a liquid crystal display device or expanding a viewing angle.
The cellulose acylate film of the present invention itself may be a retardation film. Moreover, you may use the cellulose acylate film of this invention as a transparent film at the time of apply | coating a liquid crystal etc. to a transparent film and setting it as a phase difference film.

  In the case where the cellulose acylate film itself of the present invention is used as a retardation film, the properties described above as preferred in the present invention are preferable as the physical properties such as retardation.

(Polarizer)
The polarizing plate includes a polarizer and two transparent protective films disposed on both sides thereof. The cellulose acylate film of the present invention can be used as at least one protective film. A normal cellulose acylate film may be used for the other protective 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. 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 further comprises a protective film bonded to one surface of the polarizing plate and a separate film bonded to the other 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.

  The cellulose acylate film of the present invention is preferably bonded to the polarizer so that the transmission axis of the polarizer matches the slow axis of the cellulose acylate film of the present invention. In addition, when the polarizing plate produced under polarizing plate crossed Nicols was evaluated, the orthogonality 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) was 1. It was found that when it was larger than 0 °, the polarization degree performance under the polarizing plate crossed Nicols was lowered and light leakage occurred. In this case, when combined with a liquid crystal cell, sufficient black level and contrast cannot be obtained. Therefore, the deviation between the stretching direction of the cellulose acylate film of the present invention and the direction of the transmission axis of the polarizing plate is preferably within 1 °, preferably within 0.5 °.

UV3100PC (manufactured by Shimadzu Corporation) was used for the single plate transmittance TT, the parallel transmittance PT, and the orthogonal transmittance CT of the polarizing plate. In the measurement, measurement was performed in the range of 380 nm to 780 nm, 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 single-plate transmittance measurement, the sample is set with the film side facing the light source. Each of the two samples is measured, and the average value is taken as the transmittance of the single plate. The preferable range of polarization performance is 40.0 ≦ TT ≦ 45.0, 30.0 ≦ PT ≦ 40.0, CT ≦ 2 in the order of single plate transmittance TT, parallel transmittance PT, and orthogonal transmittance CT, respectively. 0.0, and more preferable ranges are 41.0 ≦ TT ≦ 44.5, 34 ≦ PT ≦ 39.0, and CT ≦ 1.3 (the unit is%). In the polarizing plate durability test, the amount of change is preferably smaller.
In addition, 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 95% RH for 500 hours with the following formulas (a) and (b): ) Is satisfied.

(A) −6.0 ≦ ΔCT ≦ 6.0
(B) -10.0 ≦ ΔP ≦ 0.0
Here, the amount of change is a value obtained by subtracting the measured value before the test from the measured value after the test.
Satisfying this requirement ensures stability during use or storage of the polarizing plate.

(Dampproof bag)
In the present invention, the “moisture-proof bag” is defined by the moisture permeability measured based on the cup method (JIS-Z208). In general, since the retardation value of a cellulose acylate film changes as the humidity changes, it is necessary to eliminate the influence of the humidity change on the film as much as possible. In order to prevent the influence of the environmental humidity outside the bag containing the produced polarizing plate, the moisture permeability is 40 ° C. and 90% R.D. H. It is preferable to use a material having a moisture permeability of 30 g / (m ² · Day) or less. When it is 30 g / (m ² · Day) or more, it becomes impossible to prevent the influence of environmental humidity outside the bag. More preferably, it is 10 g / (m ² · Day) or less, and most preferably 5 g / (m ² · Day) or less.

The material of the moisture-proof bag is not particularly limited as long as it satisfies the above-described moisture permeability, and any known material can be used [("Packaging Handbook", Japan Packaging Technology Association (1995)). ; "Basic knowledge of packaging materials", Japan Packaging Technology Association (November 2001); "Introduction to functional packaging", 21st century packaging research boundary (February 28, 2002, first edition, first print), etc.) . In the present invention, a material that has low moisture permeability and is light and easy to handle is desirable, and a composite material such as a film obtained by vapor-depositing silica, alumina, ceramics material, etc. on a plastic film or a laminated film of a plastic film and an aluminum foil is particularly preferably used. Can do. The thickness of the aluminum foil is not particularly limited as long as the humidity in the bag does not change in the environmental humidity, but it is preferably several μm to several 100 μm, and preferably 10 μm to 500 μm. Further preferred. Since the cellulose acylate film of the present invention has a high retardation value, the amount of fluctuation of the retardation value accompanying a change in humidity is large. If the difference between the humidity control state of the polarizing plate and the temperature and humidity at the time of pasting is large, the retardation value greatly fluctuates after the pasting, so that the difference is preferably small. It is preferable that the humidity in the bag subjected to the moisture-proofing treatment used in the present invention satisfies any of the following.
43% RH to 70% RH at 25 ° C. with the polarizing plate packaged, more preferably 45% to 65%, and still more preferably 45% to 63%.
The humidity in the bag with the polarizing plate packaged is within 15% RH with respect to the humidity when the polarizing plate is bonded to the liquid crystal panel.

(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. For example, glow discharge treatment, ultraviolet irradiation treatment, corona treatment, flame treatment, acid or alkali treatment can be used. The glow discharge treatment here may be low-temperature plasma that occurs 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-mentioned conditions, and examples thereof include chlorofluorocarbons such as argon, helium, neon, krypton, xenon, nitrogen, carbon dioxide, tetrafluoromethane, and mixtures thereof. It is done. Details of these are described in detail on pages 30 to 32 in JIII Journal of Technical Disclosure No. 2001-1745 (issued on March 15, 2001, Invention Association). Note that, in the plasma treatment at atmospheric pressure which has been attracting attention in recent years, for example, irradiation energy of 20 to 500 kgy is used under 10 to 1000 kev, and more preferably irradiation energy of 20 to 300 kgy is used under 30 to 500 kev. Among these, an alkali saponification treatment is particularly preferable, and it is extremely effective as a surface treatment of a cellulose acylate film.

The alkali saponification treatment is preferably carried out by a method in which the cellulose acylate film is directly immersed in a saponification solution tank or a method in which the saponification solution is applied to the cellulose acylate film.
Examples of the coating method include a dip coating method, a curtain coating method, an extrusion coating method, a bar coating method, and an E-type coating method. The solvent of the alkali saponification coating solution has good wettability because it is applied to the transparent support of the saponification solution, and the surface state remains good without forming irregularities on the surface of the transparent support by the saponification solution solvent. It is preferred to select a solvent to keep. 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 on which the saponification solution is applied with water or with an acid and then with water.

(Antireflection layer)
It is preferable to provide a functional film such as an antireflection layer on the transparent protective film disposed on the opposite side of the polarizing plate from the liquid crystal cell. In particular, in the present invention, at least a light scattering layer and a low refractive index layer are laminated in this order on the transparent protective film, or a medium refractive index layer, a high refractive index layer, and a low refractive index layer are formed on the transparent protective film. An antireflection layer laminated in order is preferably used. These preferred examples 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 transparent protective film will be described.
The matting particles are dispersed in the light scattering layer according to the present invention, and the refractive index of the material other than the matting particles in the light scattering layer is preferably in the range of 1.50 to 2.00. The refractive index of the layer is preferably in the range of 1.35 to 1.49. In the present invention, the light scattering layer has both antiglare properties and hard coat properties, and may be a single layer or a plurality of layers, for example, 2 to 4 layers.

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

  When the antireflection layer according to the present invention has optical characteristics such as a specular reflectance of 2.5% or less, a transmittance of 90% or more, and a 60 ° gloss of 70% or less, reflection of external light can be suppressed, and visibility is improved. It is preferable because it 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 (ratio) is 0.3 to 1, and haze value decreases after forming a low refractive index layer from the haze value when the light scattering layer is provided. Within 15%, with a comb width of 0.5 mm, the transmitted image clarity is 20% to 50%. Setting it to 0 is preferable because it prevents glare on a high-definition LCD panel and reduces blurring of characters and the like.

(Low refractive index layer)
The refractive index of the low refractive index layer of the antireflection film according to the present invention is preferably 1.20 to 1.49, more preferably 1.30 to 1.44. Furthermore, the low refractive index layer preferably satisfies the following formula (XI) from the viewpoint of reducing the reflectance.

Formula (XI): (m / 4) × 0.7 <n1d1 <(m / 4) × 1.3
In formula (XI), 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 according to the present invention will be described below.
The low refractive index layer according to the present invention 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 antireflection film according to the present invention is mounted on an image display device, the lower the peel strength from a commercially available adhesive tape, the easier it is to peel off after sticking a seal or memo, preferably 5N or less, more preferably 3N or less. 1N or less is most preferable. Further, the higher the surface hardness measured with a microhardness meter, the harder it is to scratch, preferably 0.3 GPa or more, more preferably 0.5 GPa or more.

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

  As structural units for imparting crosslinking reactivity, structural units obtained by polymerization of monomers having a self-crosslinkable functional group in advance in the molecule such as glycidyl (meth) acrylate and glycidyl vinyl ether, carboxyl groups, hydroxy groups, amino groups , Obtained by polymerization of a monomer having a sulfo group or the like (for example, (meth) acrylic acid, methylol (meth) acrylate, hydroxyalkyl (meth) acrylate, allyl acrylate, hydroxyethyl vinyl ether, hydroxybutyl vinyl ether, maleic acid, crotonic acid, etc.) And a structural unit obtained by introducing a crosslinking reactive group such as a (meth) acryloyl group into these structural units by a polymer reaction (for example, it can be introduced by a technique such as allowing acrylic acid chloride to act on a hydroxy group) And the like.

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

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

(Light scattering layer)
The light scattering layer is formed for the purpose of contributing to the film light diffusibility due to surface scattering and / or 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

  The thickness of the light scattering layer is preferably from 1 to 10 μm, more preferably from 1.2 to 6 μm, from the viewpoint of imparting hard coat properties and from the viewpoint of curling and suppression of deterioration of brittleness.

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

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

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

Polymerization of 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 on a transparent support and then ionizing radiation or heat is applied. The antireflection film can be formed by curing by the polymerization reaction. 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.
Accordingly, 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 transparent support and then subjected to a polymerization reaction by ionizing radiation or heat. Curing can form an antireflection film.

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 is usually made of 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, than filler particles. Contained.
As specific examples of the mat particles, inorganic particles such as silica particles and TiO ₂ particles; resin particles such as acrylic particles, crosslinked acrylic particles, polystyrene particles, crosslinked styrene particles, melamine resin particles, and benzoguanamine resin particles are preferable. Can be mentioned. Of these, crosslinked styrene particles, crosslinked acrylic particles, crosslinked acrylic styrene particles, and silica particles are preferable. The shape of the mat particles can be either spherical or irregular.

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

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

The mat particles are contained in the light scattering layer so that the amount of mat particles in the formed light scattering layer is preferably 10 to 1000 mg / m ² , more preferably 100 to 700 mg / m ² .
The particle size distribution of the 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 to be used in the light scattering _{layer, TiO 2, ZrO 2, Al} 2 O 3, In 2 O 3, ZnO, SnO 2, Sb 2 O 3, ITO and SiO ₂ and the like. TiO ₂ and ZrO ₂ are particularly preferable from the viewpoint 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 1.48 to 2.00, more preferably 1.50 to 1.80. In order to make the refractive index within the above range, the kind and amount ratio of the binder and the inorganic filler may be appropriately selected. How to select can be easily known experimentally in advance.

  In order to ensure surface uniformity such as coating unevenness, drying unevenness, 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 an antiglare 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 transparent protective film will be described.
An antireflection film comprising a layer structure of at least a middle refractive index layer, a high refractive index layer, and a low refractive index layer (outermost layer) on the substrate 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 transparent support> refractive index of low refractive index layer

A hard coat layer may be provided between the transparent support and the medium refractive index layer. Further, it may be composed of a medium refractive index hard coat layer, a high refractive index layer and a low refractive index layer (for example, JP-A-8-122504, JP-A-8-110401, JP-A-10-300902, (See JP 2002-243906, JP 2000-11706, etc.). Other functions may be imparted to each layer. Examples of such a layer include an antifouling low refractive index layer and an antistatic high refractive index layer (for example, JP-A-10-206603). JP, 2002-243906, A) etc. are mentioned.
The haze of the antireflection film 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 film is usually composed of a curable film containing at least an inorganic compound ultrafine particle having a high refractive index having an average particle diameter of 100 nm or less and a matrix binder.
Examples of the high refractive index inorganic compound fine particles include inorganic compounds having a refractive index of 1.65 or more, preferably those having a refractive index of 1.9 or more. Examples thereof include oxides such as Ti, Zn, Sb, Sn, Zr, Ce, Ta, La, and In, and composite oxides containing these metal atoms.
In order to obtain such ultrafine particles, the surface of the particles is treated with a surface treating agent (for example, silane coupling agents, etc .: JP-A Nos. 1-295503, 11-153703, 2000-9908). No. 1, anionic compound or organometallic coupling agent: Japanese Patent Application Laid-Open No. 2001-310432, etc. -310432, etc.), specific dispersant combination (eg, JP-A-11-153703, US Pat. No. 6,210,858, JP-A-2002-27776069, etc.) and the like.

Examples of the material forming the matrix include conventionally known thermoplastic resins and curable resin films.
Furthermore, a polyfunctional compound-containing composition having at least two radically polymerizable and / or cationically polymerizable groups, and a composition containing an organometallic compound having a hydrolyzable group and a partial condensate 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 generally 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 mμ, more preferably 10 nm to 1 μm.

(Low refractive index layer)
The low refractive index layer is formed by sequentially laminating on the high refractive index layer. The refractive index of the low refractive index layer is 1.20 to 1.55. Preferably it is 1.30-1.50.
It is preferable to construct as an outermost layer having scratch resistance and antifouling properties. 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 refractive index of the fluorine-containing compound is preferably 1.35 to 1.50. More preferably, it is 1.36-1.47. 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], JP-A 2000-284102, and the like.
The silicone compound is a compound having a polysiloxane structure, preferably containing a curable functional group or a polymerizable functional group in the polymer chain and having a crosslinked structure in the film. For example, reactive silicone (eg, Silaplane (manufactured by Chisso Corporation), silanol group-containing polysiloxane (Japanese Patent Laid-Open No. 11-258403, etc.) and the like can be mentioned.

The crosslinking or polymerization reaction of the fluorine-containing and / or siloxane polymer having a crosslinking or polymerizable group is carried out at the same time as or after the application of the coating composition for forming the outermost layer containing a polymerization initiator, a sensitizer and the like. It is preferable to carry out by light irradiation or heating.
Also preferred is a cured film by sol-gel conversion in which an organometallic compound such as a silane coupling agent and a specific fluorine-containing hydrocarbon group-containing silane coupling agent are cured by a condensation reaction in the presence of a catalyst.
For example, a polyfluoroalkyl group-containing silane compound or a partially hydrolyzed condensate thereof (Japanese Patent Laid-Open Nos. 58-142958, 58-147483, 58-147484, Japanese Patent Laid-Open Nos. 9-157582, 11) -106704), silyl compounds containing a poly "perfluoroalkyl ether" group which is a fluorine-containing long chain group (Japanese Patent Application Laid-Open Nos. 2000-117902, 2001-48590, 2002) 53804), and the like.

The low refractive index layer has an average primary particle diameter of 1 to 150 nm such as a filler (for example, silicon dioxide (silica), fluorine-containing particles (magnesium fluoride, calcium fluoride, barium fluoride)) as an additive other than the above. Low refractive index inorganic compounds, organic fine particles described in paragraphs [0020] to [0038] of JP-A-11-3820, etc.), silane coupling agents, slip agents, surfactants, and the like can be contained.
When the low refractive index layer is 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.
Further, a hard coat layer, a forward scattering layer, a primer layer, an antistatic layer, an undercoat layer, a protective layer, and the like may be provided.

(Hard coat layer)
The hard coat layer is provided on the surface of the transparent support in order to impart physical strength to the transparent protective film provided with the antireflection layer. In particular, it is preferably provided between the transparent support and the high refractive index layer. The hard coat layer is preferably formed by a crosslinking reaction or a polymerization reaction of a light and / or heat curable compound. The curable functional group is preferably a photopolymerizable functional group, and the hydrolyzable functional group-containing organometallic compound is preferably an organic alkoxysilyl compound.
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 (described later) provided with 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.

(Antistatic layer)
In the case of providing an antistatic layer, it is preferable to impart conductivity with a volume resistivity of 10 ⁻⁸ (Ωcm ⁻³ ) or less. The use of hygroscopic substances, water-soluble inorganic salts, certain surfactants, cationic polymers, anionic polymers, colloidal silica, etc. can give a volume resistivity of 10 ⁻⁸ (Ωcm ⁻³ ). There is a problem that dependency is large, and sufficient conductivity cannot be secured at low humidity. Therefore, a metal oxide is preferable as the conductive layer material. Some metal oxides are colored, but using these metal oxides as the conductive layer material is not preferable because the entire film is colored. Zn, Ti, Al, In, Si, Mg, Ba, Mo, W, or V can be given as the metal that forms the metal oxide without coloring, and a metal oxide containing this as a main component should 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 , or a composite oxide thereof. In particular, ZnO, TiO ₂ and SnO ₂ are preferable. Examples of containing different atoms include, for example, additives such as Al and In for ZnO, addition of Sb, Nb and halogen elements for SnO ₂ , and 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 secure a conductivity of 10 ⁻⁸ (Ωcm ⁻³ ) or less in volume resistance, It is sufficient that the layer has a surface resistance value of approximately 10 ⁻¹⁰ (Ω / □) or less, and more preferably 10 ⁻⁸ (Ω / □). The surface resistance value of the conductive layer needs to be measured as a value when the antistatic layer is the outermost layer, and can be measured in the middle of forming the laminated film described in this patent.

(Liquid crystal display device)
The cellulose acylate film of the present invention, an optical compensation sheet (also referred to as a retardation film) comprising the film, and a polarizing plate using the film can be used for liquid crystal cells and liquid crystal display devices in various display modes. TN (Twisted Nematic), IPS (In-Plane Switching), FLC (Ferroelectric Liquid Crystal, AFLC) Various display modes such as HAN (Hybrid Aligned Nematic) have been proposed. Of these, the OCB mode or the VA mode is preferable, and the VA mode can be most preferably used.

  The OCB mode liquid crystal cell is a liquid crystal display device using a bend alignment mode liquid crystal cell in which rod-like liquid crystalline molecules are aligned in a substantially opposite direction (symmetrically) between an upper portion and a lower portion of the liquid crystal cell. OCB mode liquid crystal cells are disclosed in US Pat. Nos. 4,583,825 and 5,410,422. Since the rod-like liquid crystal molecules are aligned symmetrically between the upper part and the lower part of the liquid crystal cell, the bend alignment mode liquid crystal cell has a self-optical compensation function. For this reason, this liquid crystal mode is also called an OCB (Optically Compensatory Bend) liquid crystal mode. The bend alignment mode liquid crystal display device has an advantage of high response speed.

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).
A VA mode liquid crystal display device includes a liquid crystal cell and two polarizing plates disposed on both sides thereof. The liquid crystal cell carries a liquid crystal between two electrode substrates. In one aspect of the transmissive liquid crystal display device of the present invention, the optical compensation sheet of the present invention is disposed between the liquid crystal cell and one polarizing plate, or between the liquid crystal cell and both polarizing plates. Place two in between.

  In another aspect of the transmissive liquid crystal display device of the present invention, an optical compensation sheet made of the cellulose acylate film of the present invention is used as the transparent protective film of the polarizing plate disposed between the liquid crystal cell and the polarizer. The above optical compensation sheet may be used only for the transparent 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 above optical compensation sheet may be used for the two transparent protective films. When the optical compensation sheet is used only for one polarizing plate, it is particularly preferable to use it as a protective film for the liquid crystal cell side of the backlight side polarizing plate of the liquid crystal cell. This is because when an optical compensation sheet and a functional film (such as an anti-glare sheet) are bonded together, if an error occurs during the processing of a polarizing plate, the expensive optical compensation sheet and functional film will be discarded at once. The cellulose acylate film of the present invention is preferably attached to the VA cell side for bonding to the liquid crystal cell. The protective film may be a normal cellulose acylate film, and is preferably thinner than the cellulose acylate film of the present invention. For example, 40-80 μm is preferable, and examples include, but are not limited to, commercially available KC4UX2M (40 μm manufactured by Konica Capto), KC5UX (60 μm manufactured by Konica Capto), TD80 (80 μm manufactured by Fuji Photo Film) and the like.

EXAMPLES Hereinafter, although this invention is demonstrated concretely based on an Example, this invention is not limited to an Example.
In this example, Re was 30 ≦ Re ≦ 200, and Rth was 70 ≦ Rth ≦ 350 nm as desired values for the cellulose acylate film.

[Measurement method]
Hereinafter, various properties of the cellulose acylate film were measured and measured by the following methods.
(Volatile content of cellulose acylate film)
It was calculated by the method described in this specification.
(Retardation values Re, Rth)
It was calculated by the method described in this specification.

(Glass transition temperature Tg)
In the present invention, the glass transition temperature was measured with a differential scanning calorimeter DSC2910 manufactured by TA Instruments. The measurement mode was a modulated DSC mode. The temperature increase rate was 2 ° C./min, the amplitude was ± 1 ° C., the amplitude period was 80 sec, and the measurement temperature range was −50 to 200 ° C., and the measurement was performed in 2 cycles (temperature increase to temperature decrease to temperature increase to temperature decrease). A cellulose acylate film containing volatile components was sealed in a stainless steel sealed container made of SII and measured.
When the vertical axis represents the reversible heat capacity (J / g / ° C.) and the horizontal axis represents the temperature (° C.), the reversible heat capacity seen when moving from the solid region to the glass transition region in the second temperature rise curve is abrupt. At the increasing portion, the straight line 1 is drawn in the solid region and the straight line 2 when the straight line 2 is drawn in the glass transition region is defined as the glass transition temperature Tg.
(Elastic modulus)
Sample 10mm × 200mm was conditioned at 25 ° C, 60% RH for 2 hours, and the tensile modulus was initially measured with a tensile tester (Strograph-R2 (manufactured by Toyo Seiki)) at an initial sample length of 100 mm and a tensile speed of 10 mm / min. It was calculated from the stress and elongation.
(Moisture permeability)
The film sample was conditioned at 25 ° C. and 10% RH for 3 hours or more, and 10 g of calcium chloride was placed in a 6 cm cup and measured by the cup method. The moisture permeability per square meter at 60 ° C. and 95% RH for 24 hours was calculated.
(Stretching temperature)
In the stretching process, the film surface temperature of the film was measured using a radiation thermometer (for thin film).

(Mass change)
A sample was cut into a size of 100 mm × 100 mm, and a change in mass was measured when the sample was allowed to stand for 48 hours under a thermo condition of 80 ° C. and 90% RH. Before and after thermostat, the humidity was measured at 25 ° C. and 60% RH for 2 hours.

(Photoelastic coefficient)
A tensile stress was applied to the long axis direction of a 10 mm × 100 mm film sample, and the Re retardation at that time was measured with an ellipsometer (M150, JASCO Corporation), and the photoelastic coefficient was calculated from the amount of change in retardation with respect to the stress. Was calculated.

(PV value, RMS value)
Here, the maximum height difference (PV value) of the film thickness and the RMS value of the film thickness were measured by a FUJINON fringe analyzer (FX-03). At this time, the measurement area was in the range of φ = 60 mm.

(Micro-region orientation angle distribution)
The orientation angle distribution of the cellulose acylate film was measured by OPTIPRO (XY scanning stage, halogen lamp light + 550 nm interference filter). At this time, the measurement area was 60 mm × 60 mm, and measurement was performed at intervals of 4 mm using a beam with a diameter of 3 mm.

[Example 1]
-Film formation of cellulose acylate film (1) Cellulose acylate Cellulose acylates with different degrees of acyl substitution described in Table 1 were prepared. In this, sulfuric acid (7.8 parts by mass with respect to 100 parts by mass of cellulose) was added as a catalyst, 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.

(2) Dope preparation <1-1> Cellulose acylate solution The following composition was put into a mixing tank, stirred to dissolve each component, further heated to 90 ° C. for about 10 minutes, and then filtered with an average pore diameter of 34 μm and It filtered with the sintered metal filter with an average hole diameter of 10 micrometers.

(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 Methanol 60.2 parts by mass

<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 size 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 A
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 A. (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 so as to have the ratio shown in Table 2 to prepare a dope for film formation. This dope was used for film production from F1 to F3 and from F5 to F13.
Retardation expression agent A

<1-4> Retardation developer solution B
Furthermore, 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 B.

(Retardation developer solution B)
Retardation developing agent A 8.0 parts by mass Retardation developing agent B 12.0 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 B were mixed at a ratio shown in Table 2 to prepare a dope for film formation. This dope was subjected to F4 film preparation.
The addition ratio of the retardation developer is shown in Table 2 in terms of parts by mass when the amount of cellulose acylate is 100 parts by mass.
Retardation expression agent B

(Casting)
The above dope was cast using a band casting machine. After casting, under the conditions shown in Table 2, the film is stretched in the direction substantially perpendicular to the conveying direction (second stretching) after the drying step if necessary following the stretching in the conveying direction (first stretching), and further dried and wound. A film was obtained. In the processes after casting, the volatile matter during stretching can be arbitrarily changed by adjusting process conditions such as drying air temperature, humidity, air volume, and the place where stretching is performed. As shown in Table 2, in F1 to F10, the first stretching is performed at Tg + 0 to 60 ° C. in the region where the volatile fraction is 30% by mass to 65% by mass in the transport direction, and the second stretching is a direction orthogonal to the transport direction. In the volatile content region of 0 to 35% by mass at Tg + 0 to 60 ° C. On the other hand, in F11, the volatile content region of the first stretching was less than 30% by mass. In F12, the first stretching was performed in a temperature range outside the range of Tg + 0 to 60 ° C. In F13, the second stretching was performed outside the region where the volatile fraction was 0% by mass to 35% by mass in the transport direction. Table 2 shows the stretch ratio calculated from the film width at the entrance of the stretch section and the film width at the exit of the stretch section. The casting conditions for each film were the same.

As shown in Table 2, Samples F1 to F10 according to the present invention achieve desired Re and Rth and have small elastic modulus anisotropy, but Comparative Sample F11 has small elastic modulus anisotropy but achieves desired Re Not done. Further, since the comparative sample F12 could not be sufficiently stretched because the first stretching temperature was low and desired Re and Rth could be realized, the elastic anisotropy was not within the preferred range. Furthermore, since Comparative Example F13 had a high volatile fraction in the second stretching, the retardation developer could not be sufficiently oriented and the desired Re value could not be achieved.
The secondary average particle size of the matting agent of these films was 1.0 μm or less, and the mass change when left standing at 80 ° C. and 90% RH for 48 hours was 0 to 3%. Moreover, the dimensional change when it left still for 24 hours on the conditions of 60 degreeC90% RH and 90 degreeC3% RH was -1.2 to 0.2%. Further, all the samples had a photoelastic coefficient of 50 × 10 ⁻¹³ cm ² / dyn (5 × 10 ⁻¹¹ m ² / N) or less. The water vapor permeability was 2500 g / (m ² · day) or less per square meter at 60 ° C. and 95% RH for 24 hours, the PV value was 1 μm or less, and the RMS value of the film thickness was 0.07 μm or less.

<Preparation of Comparative Film F14>
F14 was prepared under the same conditions as in F1 except that the volatile region at the first stretching was 70% by mass, but the volatile content rate at the film stripping part was high, and stripping could not be performed.

[Example 2]
<2-1-1>
(Preparation of polarizing plate-1)
A polarizer was produced by adsorbing iodine to a stretched polyvinyl alcohol film.
The cellulose acylate film prepared in Example 1 (F1 to F13: equivalent to TAC1 in FIGS. 1 and 2 and TAC1-1 and TAC1-2 in FIG. 3) is applied to one side of the polarizer using a polyvinyl alcohol-based adhesive. Pasted. The saponification treatment was performed under the following conditions.
A 1.5N aqueous sodium hydroxide solution was prepared and kept at 55 ° C. A 0.01 N 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.

It arrange | positioned so that the transmission axis of a polarizer might become parallel with the width direction of the cellulose acylate film produced in Example 1 (FIG. 1). It arrange | positioned so that the transmission axis of a polarizer might become parallel to the width direction of a commercially available cellulose triacylate film.
In this way, polarizing plates A1 to A13 were produced.
By using a spectrophotometer (UV3100PC), the cellulose acylate film prepared in Example 1 is combined inside the polarizer so that the single plate transmittance TT, parallel transmittance PT of the polarizing plate of 380 nm to 780 nm, When orthogonal transmittance CT was measured and the average value of 400-700 nm was calculated | required, TT was 40.8-44.7, PT was 34-38.8, and CT was 1.0 or less. Further, in the polarizing plate durability test at 60 ° C. and 95% RH for 500 hours, both are in the range of −0.1 ≦ ΔCT ≦ 0.2 and −2.0 ≦ ΔP ≦ 0, and at −60 ° C. and 90% RH, −0.05 ≦ ΔCT ≦ 0.15 and −1.5 ≦ ΔP ≦ 0.

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

<2-2-2>
(Preparation of coating solution for low refractive index layer)
First, the sol solution a was prepared as follows. A stirrer, a reactor equipped with a reflux condenser, 120 parts of methyl ethyl ketone, 100 parts of acryloyloxypropyltrimethoxysilane (KBM5103, manufactured by Shin-Etsu Chemical Co., Ltd.), 3 parts of diisopropoxyaluminum ethyl acetoacetate were added and mixed. 30 parts 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 triacetylcellulose film (Fujitac TD80UF, manufactured by Fuji Photo Film Co., Ltd.) is unwound in a roll form, and the above functional layer (light scattering layer) coating solution is 180 lines / inch in line depth. Using a microgravure roll with a diameter of 50 mm and a doctor blade having a gravure pattern of 40 μm, coating was performed under the conditions of a gravure roll rotation speed of 30 rpm and a conveyance speed of 30 m / min, drying at 60 ° C. for 150 seconds, and further under nitrogen purge Using a 160 W / cm air-cooled metal halide lamp (manufactured by Eye Graphics Co., Ltd.), the coating layer is cured by irradiating ultraviolet rays with an illuminance of 400 mW / cm ² and an irradiation amount of 250 mJ / cm ² , and a functional layer having a thickness of 6 μm 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 is 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 a nitrogen purge, ultraviolet rays with an illuminance of 400 mW / cm ² and an irradiation amount of 900 mJ / cm ² were irradiated, and a low refraction with a thickness of 100 nm The rate 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 transparent protective film 01 with the light scattering layer prepared in <2-2-3> and the triacetylcellulose film (Fujitac TD80UF, manufactured by Fuji Photo Film Co., Ltd.) having a thickness of 80 μm without applying the functional layer are described above. The same saponification treatment was performed, and the film was pasted on the opposite side of the polarizer and dried at 70 ° C. for 10 minutes or more.
The polarizer was arranged so that the transmission axis of the polarizer and the width direction of the triacetylcellulose film (Fujitac TD80UF, manufactured by Fuji Photo Film Co., Ltd.) were parallel to each other (FIG. 1). The polarizer was disposed so that the transmission axis of the polarizer was parallel to the width direction of the transparent protective film 01 with the light scattering layer. In this way, a polarizing plate (B0) 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 2.3%.

(Evaluation of light leakage with commercially available VA panel)
The polarizing plate (B0) produced by <2-3-1> on the front side is peeled off on the front side of the VA mode liquid crystal TV (LC-32AD5, manufactured by Sharp Corporation). Polarizing plates A1 to A9 prepared in Example 2 were attached. In the case where A10 and A12 were pasted on the back side, polarizing plates using F10 and F12, respectively, were pasted on the front side instead of TD80UF of the polarizing plate of <2-3-1>. The absorption axis of the polarizing plate on the viewing side is in the horizontal direction of the panel, the absorption axis of the polarizing plate on the backlight side is in the vertical direction of the panel, and the pressure-sensitive adhesive surface is on the liquid crystal cell side.
Evaluation of light leakage after temperature and humidity change was held at 60 ° C. and 90% RH for 200 hours, taken out in an environment of 25 ° C. and 60% RH, 24 hours later, and displayed black from the front.
1: Strong light leakage, impractical, 3: Light leaked, but practically acceptable 5: No light leak

From Table 3, it can be seen that the present invention is superior to the comparative example in terms of light leakage.
When A11 and A13 were evaluated in the same manner, F11 and 13 had insufficient Re compensation values, so that optical compensation was insufficient, light leakage in an oblique direction was large, and actual use could not be endured.
Further, the light leakage in the oblique direction of the liquid crystal display device using the polarizing plate using the film of the present invention was at a level that can withstand actual use.

It is a schematic diagram which shows an example of 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 an example of the polarizing plate of this invention. It is sectional drawing which shows typically the cross-section of an example of the liquid crystal display device of this invention.

Claims (17)

  A film forming step of casting a cellulose acylate solution on a metal support to form a film, and then Tg + 0 to 60 ° C. in a volatile content region of 30 to 65% by mass with respect to the film obtained by the film forming step. The first stretching step for stretching and the second stretching step for stretching in the direction substantially orthogonal to the first stretching step at Tg + 0 to 60 ° C. in the volatile fraction region of 0 to 35% by mass after the first stretching step. The manufacturing method of the cellulose acylate film containing this.   The method for producing a cellulose acylate film according to claim 1, wherein stretching in the first stretching step is performed in the transport direction, and stretching in the second stretching step is performed in a direction substantially orthogonal to the transport direction.   The stretching in the first stretching process is performed at a stretching ratio of 1.03 to 2 times, and the stretching in the second stretching process is performed at a stretching ratio of 1.10 to 2 times. A method for producing a cellulose acylate film.   A cellulose acylate film produced by the method for producing a cellulose acylate film according to claim 1.   The ratio of the elastic modulus in the film conveyance direction and the elastic modulus in the direction substantially perpendicular to the conveyance direction (elastic modulus in the film conveyance direction / elastic modulus in the direction substantially orthogonal to the conveyance direction) is 0.8 to 1.2. The cellulose acylate film according to claim 4, wherein the cellulose acylate film is provided.   The cellulose acylate film according to claim 4 or 5, wherein both the elastic modulus in the film transport direction and the elastic modulus in the direction substantially perpendicular to the transport direction are 3000 MPa to 10,000 MPa.   The cellulose acylate according to any one of claims 4 to 6, wherein the front retardation value Re is 30≤Re≤200nm, and the retardation value Rth in the film thickness direction is 70≤Rth≤350nm. the film.   The film thickness of a film is 20-110 micrometers, The cellulose acylate film of any one of Claims 4-7 characterized by the above-mentioned.   The cellulose acylate film according to claim 4, wherein the cellulose acylate film contains at least one retardation developer.   The retardation developer added to the cellulose acylate film is 0% by mass or more and 10% by mass or less when the cellulose acylate is 100% by mass. The cellulose acylate film according to any one of 4 to 9. Cellulose acylate film, cellulose ester obtained by substituting cellulose hydroxyl group with acetyl group, and / or cellulose mixed fatty acid obtained by substituting acetyl group and acyl group having 3 or more carbon atoms A cellulose acylate film produced using an ester, wherein the substitution degree A of the acetyl group and the substitution degree B of the acyl group having 3 or more carbon atoms satisfy the following formulas (I) and (II): The cellulose acylate film according to any one of 10 to 10.
Formula (I): 2.0 ≦ A + B ≦ 3.0
Formula (II): 0 ≦ B   The cellulose acylate film according to claim 11, wherein the acyl group is a butanoyl group.   The cellulose acylate film according to claim 11, wherein the acyl group is a propionyl group, and the substitution degree B is 0.6 or more. The cellulose acylate film is a film produced using cellulose acylate obtained by substituting the hydroxyl group of the glucose unit constituting the cellulose acylate film with an acyl group having 2 or more carbon atoms, When the substitution degree of the hydroxyl group at the 2-position of the unit with an acyl group is DS2, the substitution degree of the hydroxyl group at the 3-position with an acyl group is DS3, and the substitution degree of the hydroxyl group at the 6-position with DS6 is DS6, the following formula (III) The cellulose acylate film according to claim 11, satisfying (IV) and (IV).
(III): 2.0 ≦ DS2 + DS3 + DS6 ≦ 2.85
(IV): DS6 / (DS2 + DS3 + DS6) ≧ 0.315   The retardation film which has a cellulose acylate film of any one of Claims 4-14.   A polarizing plate using at least one of the cellulose acylate film according to any one of claims 4 to 14 and the retardation film according to claim 15 as a protective film for a polarizer.   Use of at least one of the cellulose acylate film according to any one of claims 4 to 14, the retardation film according to claim 15, and the polarizing plate according to claim 16. A characteristic liquid crystal display device.

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