JP2003170492A - Cellulose ester film, method for producing the same, phase difference film, optical compensation sheet, elliptic polarizing plate, and display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cellulose ester film having good optical properties, a method for producing the film, a phase difference film, an elliptic polarizing plate, an optical compensation sheet, and a display. <P>SOLUTION: The method for producing the cellulose ester film has a process D0 in which the film, after being cast on a supports, is conveyed, a process A for grasping the ends of the width of the film, and a process B for stretching the film in the widthwise direction. The amount of a residual solvent at the start of stretching is 90-5 mass%, and R<SB>t</SB>/R<SB>0</SB>is adjusted to be 0.8-3.5. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a cellulose ester film, a method for producing a cellulose ester film, a retardation film, an optical compensation sheet, an elliptically polarizing plate and a display device.

[0002]

2. Description of the Related Art Nowadays, personal computers are becoming multimedia and color display has become common even in laptop personal computers. STN liquid crystal displays and TFT liquid crystal displays are mainly used in the laptop computers and desktop monitors. Further, in recent years, a liquid crystal display has become mainstream, and a TFT liquid crystal excellent in display quality has become mainstream at the same time, and a high degree of improvement in viewing angle characteristics has been demanded.

For that purpose, as the display mode of the TFT type liquid crystal, not only the conventional TN type but also the lateral electric field type (IP
S), vertical alignment method (VA), etc. have been proposed and put to practical use. On the other hand, the TN type TFT liquid crystal has a feature that the light utilization efficiency is high because the manufacturing cost is low and the optical rotation mode is used.
With the advent of optical compensation sheets in recent years, viewing angle characteristics have been improved and they are widely used.

For example, the viewing angle compensating elliptically polarizing plate has a laminated structure, and a typical example is a first transparent support (usually a cellulose triacetate film) -polarizer-second transparent support. Body (usually a cellulose ester film) -an optically anisotropic layer formed by fixing the orientation of a liquid crystalline compound in a specific direction-a transparent support C having optical biaxiality (for example, a stretched cellulose ester film) Directly on the second transparent support, or
After forming the optically anisotropic layer indirectly, the transparent support C having optical biaxiality is arranged on the optically anisotropic layer.

Further, an optically anisotropic layer containing an optically anisotropic compound can be provided on the transparent support C by fixing the orientation of the liquid crystalline compound in a specific direction.

For the first transparent support and the second transparent support,
A cellulose triacetate film having a film thickness of 40 μm to 80 μm, each produced by a casting method is used, a polarizer is a stretched polyvinyl alcohol doped with iodine, and a polarizer is used as the first transparent support and A polarizing plate is formed by laminating the second transparent support.

As the optically anisotropic layer, a liquid crystal compound having a polymerizable group is placed on a support having orientation ability by rubbing or the like by coating, and cured by, for example, ultraviolet rays to prepare a fixed layer. As the support, a transparent support having optical biaxiality, preferably 40 μm to 150
A stretched cellulose ester film having a thickness of μm can be used.

From the viewpoint of the productivity of the support, in the case of continuous production, the cellulose ester film stretched in the width direction is preferably used as the optically biaxially transparent support according to the present invention. In this case, by aligning the liquid crystalline compound in the transport (longitudinal) direction of the long second transparent support, the viewing angle compensating elliptically polarizing plate of the present invention is directly laminated by roll-to-roll production. can do.

As a method of stretching in the width direction, a method of using a tenter type width stretching machine is generally used. In this method, the clips of the tenter do not change in size at equal intervals, and only the width direction is stretched, so that there is no molecular orientation in the longitudinal direction and there is no change in size, and Only the molecules are oriented. As a result, the thickness is reduced by the stretched amount, and the retardation in the thickness direction becomes too large. Since the dimension in the longitudinal direction is regulated, the molecular orientation in the longitudinal direction is also regulated. Therefore, by stretching in the width direction, the molecular orientation advances in the width direction, and at the same time, the contraction force acts in the thickness direction to increase the plane orientation of the molecules, and thus the retardation (R _t ) in the thickness direction becomes too large. was there.

Other than the widthwise stretching by the tenter, unintended stretching in the longitudinal direction causes a problem that the retardation in the film thickness direction becomes excessive with respect to the retardation in the film plane.

As a film for an LCD display member, not only physical uniformity but also optical uniformity is a very important issue. When the film is incorporated as an LCD member, the uniformity of the retardation in the in-plane and thickness methods of the film and the uniformity of the optical slow axis distribution (hereinafter, orientation angle distribution) of the film are disturbed,
It causes light leakage when displaying black and causes a serious defect in practical use.

[0012]

The object of the present invention is to provide a cellulose ester film having excellent optical properties, a method for producing the film, a retardation film having the film, an elliptically polarizing plate, an optical compensation sheet and a display device. Is to provide.

Further, there is provided a method for producing a physically and optically uniform cellulose ester film, a cellulose ester film suitable as a member of a display device, a retardation plate using the same, an elliptically polarizing plate, an optical compensation sheet, and these. Is to provide a display device using.

[0014]

The above objects of the present invention have been achieved by the following constitutions 1 to 50.

1. Nx>Ny> Nz, where Nx, Ny, and Nz are the refractive indices in the width, length, and film thickness directions, respectively, and the in-plane retardation is R ₀ (nm),
In the method for producing a cellulose ester film in which R _t / R ₀ is 0.8 to 3.5 when the retardation in the thickness direction is R _t (nm), the cellulose peeled off after casting on a support. Process D for transporting the ester film
0, a step A of gripping the width end, and a step B of stretching in the width direction, and the residual solvent amount of the film represented by the general formula (1) at the start of stretching is 90% by mass to 5% by mass. And a method for producing a cellulose ester film.

2. The transport tension of the film in process D0 is 3
The method for producing a cellulose ester film as described in 1 above, which is in the range of 0 N / m to 300 N / m.

3. At the end point of step D0, the poor solvent content (%) in the residual solvent in the film represented by the general formula (2) is from 15% by mass to 95% by mass, and the cellulose ester according to 2 above. Film manufacturing method.

4. After casting on the support, there is a step B of stretching the peeled cellulose ester film in the width direction, and the retardation in the film plane is R ₀ (n
m), the residual solvent of the film at the start of step B in the method for producing a cellulose ester film in which R _t / R ₀ is 0.8 to 3.5, where R _t (nm) is the retardation in the thickness direction. The amount B0% is 90% by mass to 10% by mass, the temperature of the film is 30 ° C to 140 ° C, and the film temperature at the end of the step B is 70 ° C to 140 ° C.
C, and when the residual solvent amount of the film at the end of step B is B1%, B0% and B1% are 0.4 × B
A method for producing a cellulose ester film, which satisfies the relationship of 0 ≦ B1 ≦ 0.8 × B0.

5. The poor solvent content (%) in the residual solvent in the film at the end of the step B is 15% by mass to 95%.
5. The method for producing a cellulose ester film as described in 4 above, which is in the range of mass%.

6. After casting on the support, there is a step B of stretching the peeled cellulose ester film in the width direction, and the retardation in the film plane is R ₀ (n
m), the residual solvent of the film at the start of step B in the method for producing a cellulose ester film in which R _t / R ₀ is 0.8 to 3.5, where R _t (nm) is the retardation in the thickness direction. The amount is 90% by mass to 10% by mass,
The temperature of the film is 30 ° C to 130 ° C, the film temperature at the end of step B is 60 ° C to 130 ° C, and the residual solvent amount of the film at the end of step B is B1%, at the start of step B. When the residual solvent amount of the film of B is 0%, B0% and B1% are 0.8 × B0 ≦ B1 ≦ 0.9.
A method for producing a cellulose ester film, which satisfies the relationship of 9 × B0.

7. The poor solvent content (%) in the residual solvent in the film at the end of the step B is 15% by mass to 95%.
The method for producing a cellulose ester film as described in 6 above, characterized in that the content is% by mass.

8. After casting on the support, there is a step B of stretching the peeled cellulose ester film in the width direction, and the retardation in the film plane is R ₀ (n
m), a retardation in the thickness direction when the R _t (nm), in the method for producing a cellulose ester film R _t / R ₀ is 0.8 to 3.5, the film atmosphere temperature of step B is 110 ° C. ~ 140 ° C, and step B
When the residual solvent amount of the film at the end is B3% and the residual solvent amount of the film at the start of step B is B2%, B is
3% and B2% are 0.4 × B2 ≦ B3 ≦ 0.8 × B2
The method for producing a cellulose ester film, characterized in that

9. The poor solvent content (%) in the residual solvent in the film at the end of the step B is 15% by mass to 95%.
The method for producing a cellulose ester film as described in 8 above, wherein the content is% by mass.

10. Step B of stretching the peeled cellulose ester film in the width direction after casting on the support
And the retardation in the film plane is R ₀ (n
m), a retardation in the thickness direction when the R _t (nm), in the method for producing a cellulose ester film R _t / R ₀ is 0.8 to 3.5, the film atmosphere temperature of step B is 30 ° C. To 130 ° C., and the residual solvent amount of the film at the end of step B is B1%, step B
Assuming that the residual solvent amount of the film at the start is B0%, B1% and B0% are 0.8 × B0 ≦ B1 ≦ 0.9.
A method for producing a cellulose ester film, which satisfies the relationship of 9 × B0.

11. 11. The method for producing a cellulose ester film as described in 10 above, wherein the poor solvent content (%) in the residual solvent in the film in step B is 15% by mass to 95% by mass.

12. The stretching speed represented by the general formula (3) in the width direction of the film in step B is 50%.
/ Min-500% / min, The manufacturing method of the cellulose-ester film as described in any one of said 1-11 characterized by the above-mentioned.

13. After casting on the support, there is a step A of gripping the peeled cellulose ester film, a step B of stretching the film in the width direction, and a grip relaxation step C. The retardation in the film plane is R ₀ (nm), the thickness. When the retardation in the direction is R _t (nm), in the method for producing a cellulose ester film having R _t / R ₀ of 0.8 to 3.5, the good solvent concentration of the atmosphere in steps A and B is 2000 ppm or more. A method for producing a cellulose ester film, which is less than a saturated vapor amount.

14. Step B of stretching the peeled cellulose ester film in the width direction after casting on the support
And the retardation in the film plane is R ₀ (n
m), when the retardation in the thickness direction is R _t (nm), in the method for producing a cellulose ester film having R _t / R ₀ of 0.8 to 3.5, in the step B, film stretching in the width direction A method for producing a cellulose ester film, characterized in that the magnification is in the range of 1.1 to 2.5.

15. After casting on the support, there is a step B of stretching the peeled cellulose ester film in the width direction, a grip relaxation step C, and a step D1 of further drying, and the retardation in the film plane is R ₀ ( nm),
In the method for producing a cellulose ester film in which R _t / R ₀ is 0.8 to 3.5 when the retardation in the thickness direction is R _t (nm), the length at the end of step B and the start of step D1 A method for producing a cellulose ester film, which comprises drying under the condition of DB <DD1 when the film elastic moduli in the directions are DB and DD1, respectively.

16. Step B of stretching the peeled cellulose ester film in the width direction after casting on the support
And the retardation in the film plane is R ₀ (n
m), where R _t (nm) is the retardation in the thickness direction, R _t / R ₀ is 0.8 to 3.5. A method for producing a cellulose ester film, which comprises cutting off a portion.

17. After casting on the support, step A of gripping the peeled cellulose ester film in the width direction,
When the stretching step B and the grip relaxation step C are included, and the retardation in the film plane is R ₀ (nm) and the retardation in the thickness direction is R _t (nm), R _t / R ₀
Is 0.8 to 3.5, wherein a neutral zone is provided between steps A, B and C.

18. After casting on the support, step A of gripping the peeled cellulose ester film in the width direction,
In the method for producing a cellulose ester film having a stretching step B and a grip relaxation step C, a step A,
17. The method for producing a cellulose ester film according to any one of 1 to 16 above, which has a neutral zone between B and C.

19. After casting on a support, the peeled cellulose ester film is stretched in the width direction, and when the in-film retardation is R ₀ (nm) and the thickness-direction retardation is R _t (nm), R _t / R ₀
In the method for producing a cellulose ester film having a value of 0.8 to 3.5, when the tear strength in the width direction and the tear strength in the longitudinal direction are Htd and Hmd, respectively, H
td / Hmd is adjusted to 0.62-1.0, The manufacturing method of the cellulose-ester film characterized by the above-mentioned.

20. After casting on a support, the peeled cellulose ester film is stretched in the width direction, and when the in-film retardation is R ₀ (nm) and the thickness-direction retardation is R _t (nm), R _t / R ₀
In the method for producing a cellulose ester film having a ratio of 0.8 to 3.5, the dimensional change rate in the width direction and the dimensional change rate in the longitudinal direction before and after the treatment at 60 ° C. and 90% RH for 24 hours are Std% and Smd, respectively. %, Std is −0.
4 to 0.4%, and Smd is -0.4 to
A method for producing a cellulose ester film, which comprises adjusting to 0.4%.

21. After casting on a support, the peeled cellulose ester film is stretched in the width direction, and when the in-film retardation is R ₀ (nm) and the thickness-direction retardation is R _t (nm), R _t / R ₀
In the method for producing a cellulose ester film having a ratio of 0.8 to 3.5, the plasticizer content at the time of casting is G1, D1.
A method for producing a cellulose ester film, wherein G2 / G1 is adjusted to 0.9 to 1.0 when the plasticizer content after completion is G2.

22. After casting on a support, the peeled cellulose ester film is stretched in the width direction, and when the in-film retardation is R ₀ (nm) and the thickness-direction retardation is R _t (nm), R _t / R ₀
Is 0.8 to 3.5, the maximum value, the minimum value, and the average value of the film thickness in the width direction are Rmax, Rmin, and Rave, respectively. ) The film thickness distribution represented by 0-8
%, And a method for producing a cellulose ester film.

23. After casting on a support, the peeled cellulose ester film is stretched in the width direction, and when the in-film retardation is R ₀ (nm) and the thickness-direction retardation is R _t (nm), R _t / R ₀
In the method for producing a cellulose ester film having a distribution of 0.8 to 3.5, the orientation angle distribution is set in the casting direction (longitudinal direction).
The method for producing a cellulose ester film is characterized in that it is adjusted to 90 ± 1 degree.

24. After casting on a support, the peeled cellulose ester film is stretched in the width direction, and when the in-film retardation is R ₀ (nm) and the thickness-direction retardation is R _t (nm), R _t / R ₀
In the method for producing a cellulose ester film having a ratio of 0.8 to 3.5, the retardation (R ₀ ) distribution in the in-plane direction of the film is adjusted to 5% or less.

25. After casting on a support, the peeled cellulose ester film is stretched in the width direction, and when the in-film retardation is R ₀ (nm) and the thickness-direction retardation is R _t (nm), R _t / R ₀
In the method for producing a cellulose ester film having a ratio of 0.8 to 3.5, the retardation (R _t ) distribution in the thickness direction of the film is adjusted to 10% or less.

26. In the method for producing a cellulose ester film in which the peeled cellulose ester film is stretched in the width direction after casting on a support, the haze value is 0.
26% is adjusted to 2%, The manufacturing method of the cellulose-ester film of any one of said 1-25 characterized by the above-mentioned.

27. The total degree of acyl substitution of the cellulose ester film is 2.3 to 2.85, and the degree of acetyl substitution is 1.4 to 2.85. A method for producing the described cellulose ester film.

28. 28. A cellulose ester film produced by using the method for producing a cellulose ester film described in any one of 1 to 27 above.

29. A retardation film comprising the cellulose ester film described in 28 above.

30. 29. An optical compensation sheet having an optically anisotropic layer on the cellulose ester film described in 28 above.

31. 28. A cellulose ester film produced by the method for producing a cellulose ester film according to any one of 1 to 27, which has an optically anisotropic layer on the surface side which is in contact with the support during casting. And an optical compensation sheet.

32. An elliptically polarizing plate having the cellulose ester film described in 28 above.

33. 33. A display device having the elliptically polarizing plate described in 32 above. 34. In the peeled cellulose ester film after casting on the support, when the tear strengths in the width and longitudinal directions with respect to the casting direction are Htd and Hmd, respectively,
Htd / Hmd is the range of 0.62-1.0, The cellulose ester film characterized by the above-mentioned.

35. In the peeled cellulose ester film after casting on a support, the refractive index in the width direction, the longitudinal direction, and the film thickness direction with respect to the casting direction are Nx, Ny, and N, respectively.
The cellulose ester film as described in 34 above, wherein, when z, Nx>Ny> Nz.

36. The retardation in the plane of the film is R ₀ (nm), and the retardation value in the thickness direction is R _t (n
m), R _t / R ₀ is in the range of 0.8 to 3.5. The cellulose ester film as described in 34 or 35 above.

37. Any of the above 34 to 36, wherein the total acyl group substitution degree of the cellulose ester is in the range of 2.3 to 2.85 and the acetyl group substitution degree is in the range of 1.4 to 2.85. The cellulose ester film according to item 1.

38. Orientation angle distribution is 9 in the longitudinal direction
34 to 3 characterized in that it is within a range of 0 ± 1 degree
7. The cellulose ester film according to any one of 7.

39. When the maximum value, the minimum value, and the average value of the film thickness in the width direction are Rmax, Rmin, and Rave, respectively, (Rmax-Rmin) / Rave is 0 to 8%.
39. The cellulose ester film according to any one of 34 to 38 above, wherein

40. 40. The cellulose ester film as described in any one of 34 to 39 above, wherein the retardation (R ₀ ) distribution in the film plane is 5% or less.

41. The retardation (R _t ) distribution in the film thickness direction is 10% or less, wherein the cellulose ester film according to any one of the above items 34 to 40.

42. After being cast on a support, the peeled cellulose ester film was 60 ° C. and 90% RH.
After 24 hours of treatment, the dimensional change rate in the width direction and the dimensional change rate in the longitudinal direction with respect to the casting direction are respectively Std.
% And Smd%, Std is -0.4% to 0.4%
And Smd is -0.4% to 0.4%.

43. When Nx, Ny, and Nz are the refractive indices in the width, length, and film thickness directions with respect to the casting direction, N
The cellulose ester film as described in 42 above, wherein x>Ny> Nz.

44. The retardation in the plane of the film is R ₀ (nm), and the retardation value in the thickness direction is R _t (n
m), the R _t / R ₀ is in the range of _0.8 to 3.5. The cellulose ester film as described in 42 or 43 above, wherein

45. 4. The total degree of substitution of cellulose ester is in the range of 2.3 to 2.85, and the degree of substitution of acetyl groups is in the range of 1.4 to 2.85.
The cellulose ester film according to any one of 2 to 44.

46. The orientation angle distribution is 90 in the longitudinal direction.
42 to 45, characterized in that it is within a range of ± 1 degree
The cellulose ester film according to any one of 1.

47. A retardation film comprising the cellulose ester film according to any one of 34 to 46.

48. 47. An optical compensatory sheet having an optically anisotropic layer on the cellulose ester film according to any one of 34 to 46.

49. An elliptically polarizing plate comprising the cellulose ester film according to any one of 34 to 46.

50. A display device having the elliptical polarizing plate as described in 49 above. Hereinafter, the present invention will be described in detail.

The method for producing the cellulose ester film of the present invention will be described. As a method for producing a cellulose ester film of the present invention, a dope solution in which cellulose ester is dissolved and adjusted is cast onto a support (stainless belt or the like) to form a film, and the obtained film is peeled off from the support (both peeling and peeling). Then, a solution casting film forming method is used in which the film is stretched by applying tension in the width direction and then dried while being conveyed in a drying zone. The solution casting film forming method according to the manufacturing method of the present invention will be described below. The longitudinal direction (sometimes abbreviated as MD) represents the machine transport direction and the dope casting direction, and the width direction (TD) represents the direction orthogonal to the longitudinal direction in the film plane.

<Solution casting film forming method> (a) Dissolution step: Cellulose ester (flakes or powder or granules (preferably average particle size 1
This is a step of dissolving the cellulose ester and additives with stirring in an organic solvent mainly composed of a good solvent for particles having a particle size of 00 μm or more)) to form a dope. For the dissolution, there are various dissolution methods such as a method under normal pressure, a method under a boiling point of a good solvent, a method under pressurization over a boiling point of a good solvent, a cooling dissolution method, and a method under high pressure. After dissolution, the dope is filtered with a filter material, defoamed, and sent to the next step with a pump.

The above dope is a solution prepared by dissolving a cellulose ester and the additives described below in an organic solvent.

(Cellulose Ester) Cellulose as a raw material of the cellulose ester used in the present invention is not particularly limited, but examples thereof include cotton linter, wood pulp, kenaf and the like. The cellulose esters obtained from them can be mixed and used in arbitrary proportions.

When the acylating agent of the cellulose raw material is an acid anhydride (acetic anhydride, propionic anhydride, butyric anhydride), the cellulose ester according to the present invention is an organic acid such as acetic acid or an organic acid such as methylene chloride. The reaction is carried out using a solvent and a protic catalyst such as sulfuric acid. The acylating agent is an acid chloride (CH ₃ COCl, C ₂ H ₅ CO
Cl, C ₃ H ₇ COCl), the reaction is carried out using a basic compound such as an amine as a catalyst. Specifically, it can be synthesized by referring to the method described in JP-A-10-45804. In the cellulose ester, the acyl group reacts with the hydroxyl group of the cellulose molecule. The cellulose molecule is composed of a large number of glucose units linked together, and each glucose unit has three hydroxyl groups. The number of acyl groups derived from these three hydroxyl groups is called the degree of substitution. For example, cellulose triacetate has an acetyl group bonded to all three hydroxyl groups of a glucose unit.

The cellulose ester usable in the cellulose ester film of the present invention is not particularly limited, but those satisfying the following formulas (I) and (II) at the same time are preferable.

(I) 2.3 ≦ X + Y ≦ 2.85 (II) 1.4 ≦ X ≦ 2.85 In the formula, X is the substitution degree of acetyl group, and Y is the substitution degree of propionyl group and / or butyryl group. Is. Those satisfying the above two formulas are suitable for producing a cellulose ester film exhibiting excellent optical properties that meet the object of the present invention, are excellent in heat resistance, and have a positive wavelength dispersion as a retardation film, which is good. A retardation is obtained.
From the viewpoint of obtaining a film having uniform optical properties during stretching in the lateral direction, and particularly having little unevenness in retardation distribution, 2.5 ≦ X + Y ≦ 2.8 is more preferable, and 2.6 ≦ X is more preferable.
+ Y ≦ 2.75 is more preferable.

The cellulose ester used in the present invention is a cellulose ester such as cellulose acetate propionate, cellulose acetate butyrate, or cellulose acetate propionate butyrate having a propionate group or a butyrate group bonded thereto in addition to an acetyl group. Is preferably used. Butyrate includes iso-in addition to n-. Cellulose acetate propionate having a large degree of substitution of propionate groups is characterized by excellent water resistance.

The method for measuring the substitution degree of the acyl group is ASTM-
It can be measured according to D817-96.

The number average molecular weight of the cellulose ester used in the present invention is preferably in the range of 60,000 to 300,000 because the resulting film has high mechanical strength. Further, those of 70,000 to 200,000 are preferably used.

The number average molecular weight of cellulose ester can be measured as follows. It is measured by high performance liquid chromatography under the following conditions.

Solvent: Acetone Column: MPW × 1 (manufactured by Tosoh Corporation) Sample concentration: 0.2 (mass / volume)% Flow rate: 1.0 ml / min Sample injection amount: 300 μl Standard sample: polymethylmethacrylate ( Weight average molecular weight M
w = 188,200) Temperature: 23 degreeC.

(Organic Solvent) Chlorine-based organic solvents and non-chlorine-based organic solvents are available as the organic solvents useful for forming the dope that dissolves the cellulose ester. As a chlorine-based organic solvent, methylene chloride (methylene chloride) can be mentioned, which is suitable for dissolving cellulose ester, particularly cellulose triacetate. Due to the recent environmental problems, the use of non-chlorine organic solvents is being considered. As the non-chlorine organic solvent, methyl acetate, ethyl acetate, amyl acetate, acetone, tetrahydrofuran, 1,3-dioxolane, 1,
4-dioxane, cyclohexanone, ethyl formate, 2,
2,2-trifluoroethanol, 2,2,3,3-tetrafluoro-1-propanol, 1,3-difluoro-2-propanol, 1,1,1,3,3,3-hexafluoro-2- Methyl-2-propanol, 1,1,
1,3,3,3-hexafluoro-2-propanol,
2,2,3,3,3-pentafluoro-1-propanol, nitroethane and the like can be mentioned. When these organic solvents are used for cellulose triacetate, a dissolution method at room temperature can also be used, but insoluble matter can be obtained by using a dissolution method such as a high temperature dissolution method, a cooling dissolution method, or a high pressure dissolution method. Is preferable because it can be reduced. Methylene chloride can be used for cellulose esters other than cellulose triacetate, but methyl acetate, ethyl acetate, and acetone are preferably used. Methyl acetate is particularly preferable. In the present invention, an organic solvent having a good solubility for the cellulose ester is referred to as a good solvent, and also exhibits a main effect on dissolution, in which a large amount of the organic solvent used is referred to as a main organic solvent or a main organic solvent. . The good solvent in the present invention is a solvent that dissolves 5 g or more of cellulose ester in 100 g of the solvent at 25 ° C.

In addition to the above organic solvent, the dope used in the present invention has 1 to 40% by mass of 1 to 4 carbon atoms.
It is preferable to include the alcohol. These are used as a gelling solvent that makes the web gel when the dope is cast on a metal support and the solvent begins to evaporate and the ratio of alcohol increases, and makes the web tough and easy to peel from the metal support. When these proportions are small, it also has a role of promoting the dissolution of the cellulose ester of the non-chlorine organic solvent. As the alcohol having 1 to 4 carbon atoms, methanol, ethanol, n-propanol, iso-propanol, n-butanol, sec-butanol, t
ert-butanol and the like can be mentioned. Of these, ethanol is preferable because it is excellent in stability of the dope, has a relatively low boiling point, has good drying property, and has no toxicity. These organic solvents alone have poor solubility in cellulose ester and thus fall into the category of poor solvents. The poor solvent in the present invention is a solvent that dissolves less than 5 g of cellulose ester in 100 g of the solvent at 25 ° C.

From the viewpoint of improving the film surface quality, the concentration of the cellulose ester in the dope is adjusted to 15% by mass to 40% by mass, and the dope viscosity is 10 Pa · s to 50 Pa · s.
It is preferable to adjust to the range.

The following various materials may be used for the dope used in the present invention. <Additives> In the dope, plasticizers, UV inhibitors, antioxidants, dyes, matting agents, etc. may be added. These compounds may be added together with the cellulose ester or the solvent when preparing the cellulose ester solution, or may be added during or after the solution preparation. For liquid crystal display devices, it is preferable to add a plasticizer that imparts heat and humidity resistance, an antioxidant, an anti-UV agent, and the like.

<< Plasticizer >> The dope used in the present invention contains a compound known as a so-called plasticizer for improving mechanical properties, imparting flexibility, imparting water absorption resistance, reducing water vapor transmission rate, adjusting retardation and the like. It is preferably added for the purpose, and for example, phosphoric acid ester and carboxylic acid ester are preferably used. In addition, Japanese Patent Application No. 2001-19845
0, a polymer obtained by polymerizing an ethylenically unsaturated monomer having a weight average molecular weight of 500 or more and 10,000, an acrylic polymer, an acrylic polymer having an aromatic ring in a side chain, or a cyclohexyl group in a side chain. Acrylic polymers are also preferably used. Examples of the phosphoric acid ester include triphenyl phosphate,
Examples thereof include tricresyl phosphate and phenyldiphenyl phosphate. Examples of the carboxylic acid ester include phthalic acid ester and citric acid ester, and examples of the phthalic acid ester include dimethyl phthalate,
Examples thereof include diethyl phthalate, dicyclohexyl phthalate, dioctyl phthalate and diethyl hexyl phthalate, and examples of the citric acid ester include acetyl triethyl citrate and acetyl tributyl citrate. Other examples include butyl oleate, methylacetyl ricinoleate, dibutyl sebacate, triacetin, trimethylolpropane tribenzoate, and the like. Alkylphthalylalkyl glycolates are also preferably used for this purpose. The alkyl of the alkyl phthalyl alkyl glycolate is an alkyl group having 1 to 8 carbon atoms. As the alkyl phthalyl alkyl glycolate, methyl phthalyl methyl glycolate, ethyl phthalyl ethyl glycolate, propyl phthalyl propyl glycolate, butyl phthalyl butyl glycolate, octyl phthalyl octyl glycolate, methyl phthalyl ethyl glycolate, Ethylphthalyl methyl glycolate,
Ethyl phthalyl propyl glycolate, propyl phthalyl ethyl glycolate, methyl phthalyl propyl glycolate, methyl phthalyl butyl glycolate, ethyl phthalyl butyl glycolate, butyl phthalyl methyl glycolate, butyl phthalyl ethyl glycolate, propyl Phthalyl butyl glycolate, butyl phthalyl propyl glycolate, methyl phthalyl octyl glycolate, ethyl phthalyl octyl glycolate, octyl phthalyl methyl glycolate, octyl phthalyl ethyl glycolate and the like, methyl phthalyl Methyl glycolate, ethylphthalyl ethyl glycolate,
Propylphthalylpropyl glycolate, butylphthalylbutyl glycolate and octylphthalyloctylglycolate are preferable, and ethylphthalylethylglycolate is particularly preferable. Moreover, you may use these alkylphthalyl alkyl glycolate etc. in mixture of 2 or more types.

The amount of these compounds added is from 1% by mass to 20% by mass with respect to the cellulose ester from the viewpoint of manifesting desired effects and suppressing bleeding out from the film.
Is preferred. The heating temperature during stretching and drying is 200.
Since the temperature rises to around ℃, the plasticizer has a vapor pressure of 13 at 200 ℃ to suppress bleed-out.
It is preferably 33 Pa or less.

<Ultraviolet Absorber> Examples of the ultraviolet absorber used in the present invention include oxybenzophenone compounds, benzotriazole compounds, salicylate compounds, benzophenone compounds, cyanoacrylate compounds, nickel complex salt compounds and the like. Examples thereof include benzotriazole compounds that are less colored. Further, the ultraviolet absorbers described in JP-A-10-182621 and JP-A-8-337574, JP-A6-1
The polymer ultraviolet absorber described in No. 48430 is also preferably used. The ultraviolet absorber has an excellent ability to absorb ultraviolet rays having a wavelength of 370 nm or less from the viewpoint of preventing deterioration of the polarizer and the liquid crystal, and has a wavelength of 400 from the viewpoint of liquid crystal display.
Those that absorb less visible light of nm or more are preferable.

Specific examples of the benzotriazole type ultraviolet absorber useful in the present invention include 2- (2'-hydroxy-).
5'-methylphenyl) benzotriazole, 2-
(2'-hydroxy-3 ', 5'-di-tert-butylphenyl) benzotriazole, 2- (2'-hydroxy-3'-tert-butyl-5'-methylphenyl) benzotriazole, 2- (2 ′ -Hydroxy-
3 ', 5'-di-tert-butylphenyl) -5-chlorobenzotriazole, 2- (2'-hydroxy-
3 '-(3 ", 4", 5 ", 6" -tetrahydrophthalimidomethyl) -5'-methylphenyl) benzotriazole, 2,2-methylenebis (4- (1,1,3,3)
-Tetramethylbutyl) -6- (2H-benzotriazol-2-yl) phenol), 2- (2'-hydroxy-3'-tert-butyl-5'-methylphenyl)
-5-chlorobenzotriazole, 2- (2H-benzotriazol-2-yl) -6- (linear and side chain dodecyl) -4-methylphenol, octyl-3- [3-t
ert-Butyl-4-hydroxy-5- (chloro-2H
-Benzotriazol-2-yl) phenyl] propionate and 2-ethylhexyl-3- [3-tert-butyl-4-hydroxy-5- (5-chloro-2H-benzotriazol-2-yl) phenyl] propionate mixture However, the present invention is not limited to these. In addition, as a commercial product, tinuvin (TINUVI
N) 109, TINUVIN 171, and TINUVIN 326 (all manufactured by Ciba Specialty Chemicals) can be preferably used.

Specific examples of the benzophenone compound include:
2,4-dihydroxybenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone, 2-hydroxy-4-methoxy-5-sulfobenzophenone, bis (2-methoxy-4-hydroxy-5-benzoylphenylmethane), etc. Examples include, but are not limited to:

The above-mentioned UV absorber preferably used in the present invention is preferably a benzotriazole-based UV absorber or a benzophenone-based UV absorber which has high transparency and is excellent in the effect of preventing deterioration of a polarizing plate or a liquid crystal element, A benzotriazole-based ultraviolet absorber that causes less unnecessary coloring is particularly preferably used. The method of adding the ultraviolet absorber to the dope can be used without limitation as long as the ultraviolet absorber is dissolved in the dope, but in the present invention, the ultraviolet absorber is a cellulose such as methylene chloride, methyl acetate, or dioxolane. A good solvent for the ester, or a good solvent and a mixed solvent of a poor solvent such as a lower aliphatic alcohol (methanol, ethanol, propanol, butanol, etc.) dissolved in an organic solvent and mixed with a cellulose ester solution as an ultraviolet absorber solution to obtain a dope. Is preferred. In this case, it is preferable to make the dope solvent composition and the solvent composition of the ultraviolet absorbent solution the same or close to each other. The content of the ultraviolet absorber is 0.01% by mass to 5% by mass, and particularly 0.5% by mass to 3% by mass.

<Antioxidant> As the antioxidant, a hindered phenol compound is preferably used.
6-di-t-butyl-p-cresol, pentaerythrityl-tetrakis [3- (3,5-di-t-butyl-4)
-Hydroxyphenyl) propionate], triethylene glycol-bis [3- (3-t-butyl-5-methyl-4-hydroxyphenyl) propionate], 1,
6-hexanediol-bis [3- (3,5-di-t-
Butyl-4-hydroxyphenyl) propionate],
2,4-bis- (n-octylthio) -6- (4-hydroxy-3,5-di-t-butylanilino) -1,3
5-triazine, 2,2-thio-diethylenebis [3-
(3,5-di-t-butyl-4-hydroxyphenyl)
Propionate], octadecyl-3- (3,5-di-
t-butyl-4-hydroxyphenyl) propionate, N, N'-hexamethylenebis (3,5-di-t-
Butyl-4-hydroxy-hydrocinnamamide), 1,
3,5-Trimethyl-2,4,6-tris (3,5-di-t-butyl-4-hydroxybenzyl) benzene, Tris- (3,5-di-t-butyl-4-hydroxybenzyl)- Isocyanurate and the like can be mentioned. Especially 2,6
-Di-t-butyl-p-cresol, pentaerythrityl-tetrakis [3- (3,5-di-t-butyl-4-
Hydroxyphenyl) propionate], triethylene glycol-bis [3- (3-t-butyl-5-methyl-4-hydroxyphenyl) propionate] are preferred. Also, for example, N, N'-bis [3- (3,5-di-
t-butyl-4-hydroxyphenyl) propionyl]
A hydrazine-based metal deactivator such as hydrazine and a phosphorus-based processing stabilizer such as tris (2,4-di-t-butylphenyl) phosphite may be used in combination. The addition amount of these compounds is 1 in a mass ratio with respect to the cellulose ester.
ppm-1.0% is preferable, 10 ppm-1000p
pm is more preferred.

<< Mat Agent >> In the present invention, by incorporating a mat agent into the cellulose ester film, it is possible to facilitate transportation and winding. The matting agent is preferably as fine particles as possible. Examples of the fine particles include silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide, calcium carbonate, kaolin,
Examples thereof include talc, calcined calcium silicate, hydrated calcium silicate, aluminum silicate, magnesium silicate, calcium phosphate, and other inorganic fine particles and crosslinked polymer fine particles. Of these, silicon dioxide is preferable because it can reduce the haze of the film.

Fine particles such as silicon dioxide are often surface-treated with an organic substance, but such particles are preferable because they can reduce the haze of the film.

Preferred organic substances for the surface treatment include halosilanes, alkoxysilanes, silazanes, siloxanes and the like. The larger the average particle size of the fine particles, the greater the sliding effect, and conversely, the smaller the average particle size, the better the transparency. The average particle size of the secondary particles of the fine particles is 0.05.
It is in the range of μm to 1.0 μm. The average particle size of secondary particles of preferable fine particles is preferably 5 nm to 50 nm, and more preferably 7 nm to 14 nm. In the cellulose ester film, these fine particles are preferably used for generating irregularities of 0.01 μm to 1.0 μm on the surface of the cellulose ester film. The content of the fine particles in the cellulose ester was 0.
005 mass% -0.3 mass% are preferable.

As fine particles of silicon dioxide, Aerosil 200 manufactured by Nippon Aerosil Co., Ltd.,
200V, 300, R972, R972V, R974,
R202, R812, OX50, TT600 and the like can be mentioned, preferably Aerosil 200V, R97
2, R972V, R974, R202, and R812. Two or more kinds of these fine particles may be used in combination. When two or more kinds are used in combination, they can be mixed and used at an arbitrary ratio. In this case, fine particles having different average particle diameters or different materials, for example, Aerosil 200V and R972V in a mass ratio of 0.
It can be used in the range of 1: 99.9 to 99.9: 0.1.

When an alignment layer or a liquid crystal layer is applied, if the unevenness of the matting agent hinders the alignment, the matting agent can be contained only in the surface layer on one surface. Alternatively,
It is also possible to apply a coating solution containing these matting agent and cellulose ester (diacetyl cellulose, cellulose acetate propionate, etc.) to reduce the coefficient of friction and improve the slipperiness.

<< Other Additives >> In addition, thermal stability of inorganic fine particles such as kaolin, talc, diatomaceous earth, quartz, calcium carbonate, barium sulfate, titanium oxide and alumina, and salts of alkaline earth metals such as calcium and magnesium. Agents may be added. Further, an antistatic agent, a flame retardant, a lubricant, an oil agent, etc. may be added.

(B) Casting step: An endless metal belt, for example, a stainless belt or a metal support such as a rotating metal drum, which transfers the dope to a pressure die through a pressure type fixed gear pump and transfers it infinitely. It is a step of casting the dope from the pressure die at the casting position. The surface of the metal support is a mirror surface. Other casting methods include a doctor blade method for adjusting the film thickness of the cast dope film with a blade, or a method with a reverse roll coater for adjusting with a reverse rotating roll, but the slit shape of the die is prepared. A pressure die is preferable because it can be formed and the film thickness can be easily made uniform. The pressure die includes a coat hanger die and a T die, and any of them is preferably used. In order to increase the film formation speed, two or more pressure dies may be provided on the metal support, and the dope amount may be divided to form multiple layers.

(C) Solvent evaporation step: The web (the dope film after the dope is cast on the metal support is referred to as the web) is heated on the metal support to separate the web from the metal support. It is a step of evaporating the solvent until it becomes. To evaporate the solvent, there are a method of blowing air from the web side and / or a method of transferring heat from the back surface of the metal support by a liquid, a method of transferring heat from the front and back sides by radiant heat, and the like.
The back surface liquid heat transfer method is preferable in terms of drying efficiency. A method of combining them is also preferable.

In order to increase the film forming speed, it is effective to raise the web temperature on the metal support. However, since excessive solvent supply causes foaming from the inside of the web due to the solvent contained in the web, the preferable drying rate is defined by the composition of the web. Further, a method of casting on a belt-shaped metal support is also preferably used in order to increase the film formation speed. When casting is performed using a belt-shaped support, the casting speed can be increased by increasing the belt length. However, the expansion of the belt length promotes the deflection due to the weight of the belt. This flexure causes vibration during film formation and makes the film thickness non-uniform during casting. Therefore, the belt length is preferably 40 m to 120 m.

(D) Peeling step: This is a step of peeling the web having the solvent evaporated on the metal support at the peeling position. The peeled web is sent to the next step. If the residual solvent amount of the web at the time of peeling is too large, peeling is difficult, or conversely, if the web is peeled off after being sufficiently dried on the metal support, a part of the web may peel off.

As a method of increasing the film forming speed (the film forming speed can be increased by peeling while the residual solvent amount is as large as possible), there is a gel casting method (gel casting).

There are a method in which a poor solvent for cellulose ester is added to the dope, the dope is cast and then gelled, and a method in which the temperature of the metal support is lowered to cause gelation. By gelling on the metal support to increase the strength of the film at the time of peeling, the peeling can be accelerated and the film forming speed can be increased.

In the present invention, the temperature at the peeling position on the metal support is preferably adjusted to 10 to 40 ° C., more preferably 15 to 30 ° C. Further, the residual solvent amount of the web at the peeling position is preferably 5% by mass to 120% by mass. In the present invention, the amount of residual solvent can be represented by the general formula (1).

When a film is formed on a belt-shaped support, the increase in speed promotes the above belt vibration. Considering the amount of residual solvent at the time of peeling and the belt length, the film forming rate is preferably 10 m / min to 120 m / min, more preferably 15 m / min to 60 m / min.

In the present invention, the amount of residual solvent with respect to the entire width of the web may be referred to as the average amount of residual solvent or the amount of residual solvent in the central portion, and the amount of residual solvent at both ends of the web may be referred to as the amount of local residual solvent. There is also a case.

(E) Drying step: After peeling, generally, a drying device for transporting the web through rolls arranged in a staggered manner and / or a tenter device for transporting by clipping both ends of the web are used. To dry the web.
As a drying means, hot air is generally blown on both sides of the web, but a microwave may be applied instead of the air to heat the web. Drying too rapidly tends to impair the flatness of the finished film. In general, the drying temperature is usually in the range of 30 to 250 ° C. The drying temperature, the amount of drying air and the drying time vary depending on the solvent used, and the drying conditions may be appropriately selected depending on the type and combination of the solvents used.

In the present invention, the step D0 represents a step of peeling the cast film and then carrying it to the tenter portion. In step D0, it is preferable to control the temperature for the purpose of controlling the residual solvent amount of the film during stretching. Depending on the amount of residual solvent in the film in step D0, stretching in the transport direction (hereinafter, the longitudinal direction) is less likely to occur and the amount of residual solvent is adjusted to 20 ° C to 7 ° C for the purpose of adjusting the amount of residual solvent.
0 degreeC is preferable, More preferably, it is 20 degreeC-68 degreeC, Most preferably, it is 20 degreeC-40 degreeC.

In step D0, the fact that the film atmosphere temperature distribution is small in the direction perpendicular to the film transport (hereinafter, the width direction) in the film plane has a preferable range from the viewpoint of enhancing the uniformity of the film. . The temperature distribution in step D0 is preferably within ± 5 ° C, more preferably within ± 2 ° C, and most preferably within ± 1 ° C.

The film transport tension in step D0 is as follows.
From the viewpoint of peeling conditions from the support and prevention of elongation in the carrying direction in the step D0, there are preferable conditions as shown below.

(Film Conveyance Tension at Step D0) Step D
The film transport tension at 0 is affected by the physical properties of the dope, the amount of residual solvent at the time of peeling and in step D0, the temperature in step D0, etc., but is preferably 30 N / m to 300 N / m, more preferably 57 N / m. / M to 284 N / m, particularly preferably 57 N / m to 170 N / m.

A tension cut roll is preferably provided for the purpose of preventing elongation of the film in the transport direction in step D0.

The ratio of the good solvent and the poor solvent in the step D0 is defined in a preferable range in order to prevent elongation during the film transportation. As poor solvent mass / (good solvent mass + poor solvent mass) × 100 (%) at the end point of step D0, a range of 95% by mass to 15% by mass is preferable, and more preferably,
95 mass% to 25 mass%, particularly preferably 95
It is from 30% by mass to 30% by mass.

(F) Stretching step (also referred to as a tenter step) FIG. 2 shows the stretching step (also referred to as a tenter step) according to the present invention.
Will be explained.

In FIG. 2, step A is a step of gripping the film conveyed from the film conveying step D0 (not shown), and in the next step B, the film is drawn at a stretching angle as shown in FIG. 1 described later. Is stretched in the width direction (direction orthogonal to the film advancing direction), and in step C, the stretching is completed and the film is conveyed while being gripped.

It is preferable to provide a slitter for cutting off the edge in the film width direction after the film is peeled and before the step B is started and / or immediately after the step C. In particular, it is preferable to provide a slitter for cutting off the film edge just before the start of the step A. When the same stretching is performed in the width direction, especially when the film end is cut off before the start of the process B and the condition where the film end is not cut are compared, the former has the effect of further improving the orientation angle distribution. To be

It is considered that this is the effect of suppressing unintended stretching in the longitudinal direction from the peeling with a relatively large amount of residual solvent to the width stretching step B.

In the tenter process, it is also preferable to intentionally create compartments having different temperatures in order to improve the orientation angle distribution. It is also preferable to provide a neutral zone between different temperature zones so that the respective zones do not interfere with each other.

(Amount of residual solvent at the start of stretching in step B)
In the manufacturing method according to claim 1, the film surface in-plane
Tardation (R ₀(Nm)) and retardation in the thickness direction
Value (R_t(Nm)), R_t/ R₀Is 0.8
Start process B in order to achieve a range of ~ 3.5
The amount of residual solvent at the time is adjusted to 90% by mass to 5% by mass.
Is preferable, and more preferably 40% by mass to
10% by mass, and most preferably 35% by mass to 10%
Mass% is most preferred.

Further, in the manufacturing method according to claims 4 and 6, in the step B, the retardation in the film plane is R ₀ (nm) and the retardation value in the thickness direction is R _t (nm). It is essential to adjust the ratio, R _t / R _{0 so} that it falls within the range of _0.8 to 3.5, but in order to obtain the numerical value within the above range, the amount of residual solvent at the start of step B is Needs to be adjusted to 90% by mass to 10% by mass, preferably 40% by mass to 10% by mass, and more preferably 35% by mass to 10% by mass.

In order to obtain the above-mentioned R _t / R ₀ ratio within the target range in the tenter process, there is a preferable relative relationship of the good atmosphere solvent concentration in the processes A, B and C. The good solvent concentrations in steps A, B, and C are set to Ma, Mb, and Mc, respectively.
Then, it is preferable that the relationship of Ma> Mc is satisfied. Further, it is preferable to satisfy the relationship of Mb> Mc.

It is well known that in the process of stretching a film in the direction perpendicular to the transport direction, the distribution of the optical slow axis (hereinafter referred to as the orientation angle distribution) becomes poor in the width direction of the film. In order to achieve a good balance between R _t and R ₀ and to carry out stretching so that the orientation angle distribution is in a good state, there is a preferable range of good atmosphere solvent concentration in steps A, B, and C. . When the good solvent concentrations in the steps A, B, and C are Ma, Mb, and Mc, respectively, Ma> 2000 ppm is preferable, Ma> 3000 ppm is more preferable, and Ma> 3000 ppm is more preferable.
> 60% of the saturated solvent vapor concentration is most preferable. Also,
Mb> 2000 ppm is preferable, Mb> 3000 pp
m is more preferable, and Mb> 60 of saturated solvent vapor concentration is good.
% Is most preferred. Further, Mc <60% of the saturated solvent vapor concentration is preferable, Mc <3000 ppm is more preferable, and Mc <2500 ppm is the most preferable.

In order to obtain a good balance between R _t and R ₀ and to perform width stretching in a state in which the orientation angle distribution is good, the range of the relative relationship of the film elastic moduli in steps A, B and C is Exists. If the film elastic moduli in the steps A, B, and C are Da, Db, and Dc, respectively, 100 <| Da-D
b | <2000 N / mm ² is preferable, 100 <| Da
-Db | <1000 N / mm ² is more preferable, and 10
0 <| Da−Db | <700 N / mm ² is the most preferable.

In order to obtain the above R _t / R ₀ ratio in the target range in the tenter step, there is a preferable range of the film elastic modulus in steps A, B and C. If the film elastic moduli in steps A, B, and C are Da, Db, and Dc, respectively, then 5
00 <Db <2000 N / mm ² is preferable, 500 <
Db <1500 N / mm ² is more preferable, and 500 <
Most preferably Db <1000 N / mm ² .

(Poor Solvent Content (%) in Residual Solvent in Film) In the tenter step, in order to obtain the above R _t / R ₀ ratio within a desired range, the end points of steps A, B and C There is a good solvent to poor solvent ratio for the residual solvent in the film at. Each of the residual poor solvent mass / (residual good solvent mass + remaining poor solvent mass) × 100 (%) at the end of steps A, B, and C is preferably in the range of 95% by mass to 15% by mass. Furthermore, 95 mass% to 25 mass% is preferable, and the range of 95 mass% to 30 mass% is the most preferable. In addition, each residual poor solvent mass / (residual good solvent mass + remaining poor solvent mass) × 100 at the end of steps A, B, and C × 100
(%) May be the same or different.

(Temperature Setting of Film in Steps A, B and C and Amount of Residual Solvent) In the step of stretching the film in the width direction,
It is well known that the distribution of the optical slow axis (hereinafter, orientation angle distribution) becomes poor in the width direction of the film. R _t and R ₀
In order to obtain a good balance of the above and to perform the widthwise stretching in a state in which the orientation angle distribution is good, there is a preferable relative relationship of the film temperatures in the steps A, B and C. Process A, B, C
When the film temperatures at the end point are Ta, Tb, and Tc ° C., respectively, it is preferable that Ta ≦ Tb-10. Further, it is preferable that Tc ≦ Tb. Ta ≦ Tb-1
It is more preferable that 0 and Tc ≦ Tb.

In the tenter step, when the film is stretched in the direction perpendicular to the transport direction, the base is relatively soft in step B in order to reduce the distribution of orientation angle and keep R _t / R ₀ in a favorable range. Stretching is performed in the state, and in steps A and C, the base is preferably harder than in step B. The above conditions can be achieved by specifically controlling the film temperature and the amount of residual solvent in the film. The ambient temperature in each step is affected by the amount of residual solvent in the film, but is 30 to 40 ° C. in step A, steps B and C.
Then, the temperature is preferably 30 to 140 ° C. Specifically, when the film residual solvent amount at the end of step B is in the range of 0.4 to 0.8 of the film residual solvent amount at the start of step B, the ambient temperature of step B is 110 to 140 ° C. It is preferable. When the film residual solvent amount at the end of step B is in the range of 0.4 to 0.8 of the film residual solvent amount at the start of step B, the film temperature at the start of step B is 30 to 140.
And the film temperature at the end of step B is 70 to 140 ° C.
It is preferably in the range of. When the residual film solvent amount at the end of step B is in the range of 0.8 to 0.99 based on the residual film solvent amount at the start of step B, the ambient temperature of step B is 30 to 130 ° C. Is preferred. When the film residual solvent amount at the end of step B is in the range of 0.8 to 0.99 based on the film residual solvent amount at the start of step B, the film temperature at the start of step B is 30 to 130 ° C. The film temperature at the end of B is preferably in the range of 60 to 130 ° C.

The film heating rate in step B is preferably in the range of 0.5 to 10 ° C./s so that the orientation angle distribution is good and R _t / R ₀ is in the preferred range.

The stretching time in step B is preferably short in order to keep R _t / R ₀ within the preferable range. However, from the viewpoint of film uniformity, the minimum necessary stretching time range is defined. Specifically, it is preferably in the range of 1 to 10 seconds, more preferably 4 to 10 seconds.

In the tenter process, the heat transfer coefficient may be constant or may be changed. The heat transfer coefficient preferably has a heat transfer coefficient in the range of 41.9 to 419 × 10 ³ J / m ² · hr. More preferably, 4
1.9 to 209.5 in the range of ^{× 10 3 J / m 2 ·} hr, and most preferably a range of ^{41.9~126 × 10 3 J / m 2} · hr.

In order to obtain the values of R _t and R ₀ within the target range, the stretching speed in the width direction in the step B may be constant or may be changed. As the stretching speed,
50% / min to 500% / min is preferable, more preferably 100% / min to 400% / min,
The most preferable range is 200% / min to 300% / min.

In the tenter step, the fact that the temperature distribution of the film atmosphere is small has a preferable range from the viewpoint of enhancing the uniformity of the film. The temperature distribution in the tenter process is preferably within ± 5 ° C, more preferably within ± 2 ° C, and most preferably within ± 1 ° C. By reducing the temperature distribution as described above, it can be expected that the temperature distribution on the width of the film is also reduced.

(Stretching Angle during Production of Cellulose Ester Film) In step B of the method for producing a cellulose ester film of the present invention, the cast cellulose ester film is stretched in the width direction on a support. Figure 1
An aspect of the stretching step will be described with reference to.

In step B, the stretching angle shown in FIG. 1 is preferably 2 ° to 10 °, more preferably 3 ° to 7 °, and most preferably 3 ° to 5 °.

In order to obtain the preferred retardation in the present invention, the stretching ratio when stretching the cellulose ester film in the width direction is preferably 1.1 to 2.5 times,
1.3-1.8 are more preferable, and 1.3-1.6 are the most preferable.

When the cellulose ester film is stretched in step B, a uniaxial stretching machine or a biaxial stretching machine may be used.

In step C, it is preferable to relax in the direction perpendicular to the film transport direction in order to suppress dimensional change. Specifically, 95 to the film width of the previous step
It is preferable to adjust the film width so as to fall within the range of 99.5%.

After the treatment in the tenter process, it is preferable to further provide a drying process (hereinafter referred to as process D1). For the purpose of refining the optical properties imparted to the cellulose ester film in the tenter step and drying, the heat treatment is preferably performed in a temperature range of 50 ° C to 140 ° C. More preferably, it is in the range of 80 ° C to 140 ° C, and most preferably 8 ° C.
It is in the range of 0 ° C to 130 ° C.

Cellulose ester fill in the tenter process
An eye for refining the optical properties imparted to the glass and for drying.
And heat transfer coefficient 20.9 J / m²hr ~ 126 x 10³J
/ M ²It is preferable to perform the heat treatment at an hr. More preferably
Is 41.9 J / m²hr ~ 129 × 10³J / m²hr
Range, most preferably 41.9 J / m²hr ~
83.7 x 10³J / m²It is the range of hr.

(Film Temperature Distribution in Process D1) Process D
1, the film atmosphere temperature distribution is small in the widthwise film plane and in the direction perpendicular to the film conveyance, which is a preferable range from the viewpoint of enhancing the uniformity of the film. The temperature distribution in the tenter process is preferably within ± 5 ° C, more preferably within ± 2 ° C, and most preferably within ± 1 ° C.

(Film Conveyance Tension in Step D1) Step D
As the film transport tension of No. 1, there are preferable conditions for preventing the film elongation in the transport direction. The film transport tension in the step D1 is affected by the physical properties of the dope, the amount of residual solvent at the time of peeling and in the step D0, the temperature in the step D1, and the like, but is preferably 120 N / m to 200 N / m, and 140 N / m to 200 N / m is more preferable. 1
Most preferably, it is 40 N / m to 160 N / m.

A tension cut roll is preferably provided for the purpose of preventing elongation of the film in the transport direction in step D1. After drying, it is preferable to provide a slitter and cut off the end portion before winding, in order to obtain a good winding shape.

(Tear strength in width direction and length direction of cellulose ester film) When the cellulose ester film is stretched in the width direction, the machine conveying direction (hereinafter
It is preferable to stretch under the condition that the ratio of the film tear strength in the direction perpendicular to the machine direction (MD direction) and the direction perpendicular to the machine transport direction (hereinafter, TD direction) is controlled within a certain range. When the tear strengths in the TD and MD directions are Htd and Hmd, respectively, 0.6 <
Htd / Hmd <1 is preferable, 0.783 <Htd /
Hmd <1 is more preferable, and 0.83 <Htd / Hm
Most preferably d <1.

(Dimensional Change Ratios in Width and Longitudinal Direction of Cellulose Ester Film) When the cellulose ester film is stretched in the width direction, it is preferable to stretch it under the condition of controlling the dimensional change ratio within a certain range. When the dimensional change rates in the TD and MD directions are Std and Smd, respectively, −
0.4% <Std, Smd <0.4% are preferable,
More preferably, 0.25% <Std, Smd <0.25%, most preferably -0.2% <Std, Smd <0.2%.

When the cellulose ester film is stretched in the width direction, the change rate of the amount of the plasticizer at the time of making the dope, the amount of the ultraviolet absorber and the amount of the plasticizer contained in the film after the stretching and the amount of the ultraviolet absorber are changed. Stretching is preferably carried out under the condition of controlling in a certain range. The change rate of the amount of plasticizer and the amount of ultraviolet absorber is preferably within 10%, more preferably within 7%, most preferably within 5%.

When the cellulose ester film is stretched in the width direction, it is preferably stretched under the condition that the crystallinity of the film after the stretching is controlled within a certain range.

When the cellulose ester film is stretched in the width direction, it is preferable to stretch it under the condition of controlling the plasticizer distribution within a certain range.

The cellulose ester film produced by the above production method will be described. (Retardation (R ₀ , R _t ) Characteristics of Cellulose Ester Film) From the viewpoint of obtaining a liquid crystal display device having a high viewing angle display effect, which is incorporated in the retardation film, the optical compensation sheet, the elliptically polarizing plate or the like of the present invention, cellulose is used. The ester film was stretched in the width direction, resulting in R _{t of the} cellulose ester film.
/ R ₀ ratio of needs to be adjusted such that _{0.8 ≦ R t / R 0 ≦} 3.5 in, but _{preferably, 0.8 ≦ R t / R 0} ≦
3.0, and more preferably 0.8 ≦ R _t / R ₀ ≦
It is 2.5.

The retardation (R ₀ ) in the in-plane direction of the cellulose ester film of the present invention is preferably in the range of 30 nm to 1000 nm, more preferably 30 nm to 500 nm, and particularly preferably 30 nm to 150 nm is, and most preferably, it is in the range of 30 nm to 75 nm.

For the same reason as above, the film thickness direction retardation (R _t ) of the cellulose ester film of the present invention is preferably in the range of 30 nm to 1000 nm, more preferably in the range of 30 nm to 500 nm. , Particularly preferably in the range of 30 nm to 250 nm.

Further, when the cellulose ester film is stretched in the width direction, it is particularly preferable to control the orientation angle distribution in the width direction within a certain range. At any measurement point in which the orientation angle is in the width direction, it is preferably within ± 2 ° from the angle of the average orientation angle of all the measurement points, more preferably ± 1 °, most preferably ± 0.5 °.

(Orientation Angle) In the present invention, the orientation angle represents the direction of the slow axis in the plane of the cellulose ester film (the angle with respect to the width direction during casting film formation), and
The orientation angle is measured by the automatic birefringence meter KOBURA-21AD.
H was used.

The disturbance in the orientation angle of the widthwise stretched cellulose ester film is considered to be one of the causes of unintended stretching in the longitudinal direction of the film. When unintended stretching is performed in the longitudinal direction, it has an in-plane retardation having a slow axis in the longitudinal direction, and also increases the retardation in the thickness direction of the film, thereby deteriorating the orientation angle distribution. In order to give this film an in-plane retardation having a slow axis in the width direction, it is necessary to cancel the in-plane retardation having a slow axis in the longitudinal direction described above. Causes an increase in retardation. Therefore, by controlling the orientation angle uniformly, the retardation in the plane and in the thickness direction can be made uniform, and R _t / R ₀ can be kept low.

(Retardation Distribution of Cellulose Ester Film) In the present invention, the retardation (R ₀ ) distribution in the in-plane direction of the cellulose ester film is preferably adjusted to 5% or less, more preferably 2% or less. Yes, and particularly preferably 1.5% or less. Further, the retardation (R _t ) distribution in the thickness direction of the film is adjusted to preferably 10% or less, and more preferably,
It is 2% or less, and particularly preferably 1.5% or less.

The numerical value of the retardation distribution is the retardation variation coefficient (CV) obtained by measuring the retardation at 1 cm intervals in the width direction of the obtained film. The method of measuring the retardation and the numerical value of its distribution will be described later.

(Change in Retardation Characteristic Due to Difference in Measurement Wavelength) When the cellulose ester film is stretched in the width direction, it is preferable that the change in retardation due to the difference in wavelength is small in order to prevent color unevenness when incorporated in an LCD panel. .

Preferably, 0.7 <R ₄₅₀ / R ₀ <1.
_{0 and} 1.0 <R ₆₅₀ / R ₀ <1.5. More preferably 0.7 <R ₄₅₀ / R ₀ <0.95, 1.01 <R ₆₅₀
/ R ₀ <1.2, particularly preferably 0.8 <R ₄₅₀ /
_{R 0 <0.93,1.02 <R 65 0} / R 0 < 1.1.

(Transmittance of cellulose ester film)
As a member of an LCD display device, high transmittance and ultraviolet absorption performance are required, and the above-mentioned additives are added in combination,
The manufactured cellulose ester film has a 500 nm transmittance of preferably 85% to 100%, and 90% to 1%.
00% is more preferable, and 92% to 100% is the most preferable. Also, the 400 nm transmittance is 40% to 100%.
Is preferred, 50% to 100% is more preferred, and 6
Most preferred is 0% to 100%. Also, 380n
The m transmittance is preferably 0% to 10%, more preferably 0% to 5%, most preferably 0% to 3%.

(Film Thickness Distribution in Width Direction of Cellulose Ester Film) When the cellulose ester film is stretched in the width direction, the film thickness distribution R (%) in the width direction is 0 ≦ R.
(%) ≦ 8% is preferable, 0 ≦ R (%) ≦ 5% is more preferable, and 0 ≦ R is particularly preferable.
R (%) ≦ 4%.

(Haze Value of Cellulose Ester Film) The increase in the haze value of the cellulose ester film stretched in the width direction is considered to be one of the causes of unintended stretching in the longitudinal direction of the film. To be By stretching under the condition that the haze value is controlled to be low, the retardation in the plane and in the thickness direction can be made uniform, and R _t / R ₀ can be kept low.

When the cellulose ester film is stretched in the width direction, it is preferably stretched under the condition that the film haze value after the stretching is controlled within a certain range. The film haze value is preferably within 2%, more preferably within 1.5%, most preferably within 1%.

(Elastic modulus of cellulose ester film)
When the cellulose ester film is stretched in the width direction, it is preferably stretched under the condition that the tensile strength of the film after stretching is controlled within a certain range.

When the cellulose ester film is stretched in the width direction, it is preferable to stretch it under the condition of controlling the elastic modulus of the stretched film within a certain range. The elastic moduli in the width direction (TD) and the longitudinal direction (MD) may be the same or different. When the cellulose ester film stretched in the width direction undergoes unintended stretching in the longitudinal direction, the elastic modulus is changed. By stretching under the condition that the elastic modulus is controlled within a certain range, the retardation in the plane and in the thickness direction can be made uniform, and R _t / R ₀ can be kept low.

Specifically, the elastic modulus is 1.5 GPa to 5 G
The range of Pa is preferable, and 1.8 GPa is more preferable.
To 4 GPa, particularly preferably 1.9 GPa to 3
It is in the GPa range.

When the cellulose ester film stretched in the width direction undergoes unintended stretching in the longitudinal direction, the stress at break of the film after stretching is changed. By stretching under the condition that the stress at break is controlled within a certain range, retardation in the plane and in the thickness direction can be made uniform, and R _t / R ₀ can be kept low. The breaking point stresses in the width direction (TD) and the longitudinal direction (MD) may be the same or different.

Specifically, the stress at break is 50 to 200.
It is preferable to control in the range of MPa, 70 to 15
It is more preferable to control in the range of 0 MPa, and most preferable to control in the range of 80 to 100 MPa.

When the cellulose ester film stretched in the width direction undergoes unintended stretching in the longitudinal direction, the elongation at break of the film after completion of stretching is changed. By stretching under the condition that the elongation at break is controlled within a certain range, the retardation in the plane and in the thickness direction can be made uniform, and R _t / R ₀ can be kept low. The elongation at break in the width direction (TD) and the elongation at break in the longitudinal direction (MD) may be the same or different.

Specifically, the elongation at break at 23 ° C. and 55% RH is preferably controlled within the range of 20 to 80%, more preferably within the range of 30 to 60%, and even more preferably 40. It is most preferable to control in the range of 50%.

When the cellulose ester film stretched in the width direction undergoes unintended stretching in the longitudinal direction, the hygroscopic expansion rate of the film after the stretching is changed. When the cellulose ester film is stretched in the width direction, it is preferable to stretch it under the condition that the hygroscopic expansion coefficient of the film after the stretching is controlled within a certain range. Width direction (T
D) and the coefficient of hygroscopic expansion in the longitudinal direction (MD) may be the same or different.

Specifically, the hygroscopic expansion coefficient is preferably in the range of -1 to 1%, more preferably in the range of -0.5 to 0.5%, most preferably 0 to 0.2% or less.

When the cellulose ester film stretched in the width direction is unintentionally stretched in the longitudinal direction, generation of bright spot foreign matter is promoted. In-plane by stretching under conditions that suppress the generation of bright spot foreign matter in the film after stretching,
Also, the retardation in the thickness direction can be made uniform, and R _t / R ₀ can be kept low.

Specifically, 0 to 80 bright spot foreign matter / c
It is preferable to control in the range of m ² , and 0 to 60 pieces /
It is more preferable to control in the range of cm ² , and 0 to 3
Most preferably, it is controlled within the range of 0 / cm ² .

Generally, when a cellulose ester film is used as a polarizing plate protective film, an alkali saponification treatment may be carried out in order to improve the adhesiveness to the polarizer. Since the film after the alkali saponification treatment and the polarizer are bonded together using an aqueous polyvinyl alcohol solution as an adhesive, the polyvinyl ester cannot be adhered when the contact angle of the cellulose ester film with water after the alkali saponification treatment is high, thereby protecting the polarizing plate. This is a problem for films.

Therefore, the contact angle of the cellulose ester film after the alkali saponification treatment is preferably 0 to 60 °, more preferably 5 to 55 °, most preferably 10 to 30 °.

(Center Line Average Roughness (Ra) of Cellulose Ester Film)
When used as an application member, high flatness is required to reduce light leakage of the film. Centerline average roughness (Ra)
Is a numerical value defined in JIS B 0601, and examples of the measuring method include a stylus method and an optical method.

The center line average roughness (Ra) of the cellulose ester film of the present invention is preferably 20 nm or less, more preferably 10 nm or less, and particularly preferably 3 nm or less.

The outline of the method for measuring the measured values of the cellulose ester film of the present invention and the measuring method used in the examples described later will be described below.

(Amount of poor solvent in the amount of residual solvent) From the sample containing the residual solvent, the residual solvent was collected under reduced pressure, and each solvent was quantified by gas chromatography measurement.

(Film Elastic Modulus, Elongation at Break, Stress at Break) A film containing any residual solvent was sampled at a width of 10 m.
m, length 130 mm, and a tensile test was carried out at an arbitrary temperature and a methyl chloride saturated atmosphere with a chuck distance of 100 mm and a tensile speed of 100 mm / min.

For films containing no residual solvent, JI
23 ° C 55% according to the method described in SK 7127
The measurement was performed under the environment of RH. Cut the sample width to 10 mm and length to 130 mm, and set the chuck distance to 10 at an arbitrary temperature.
It was determined to be 0 mm and a tensile test was conducted at a tensile speed of 100 mm / min.

(Measurement of refractive index in the slow axis direction (width direction), fast axis direction (longitudinal direction), thickness direction (thickness direction) and slow axis direction) Abbe's The average refractive index of the sample was determined by a refractometer. Furthermore, automatic birefringence meter KO
Using BRA-21ADH (manufactured by Oji Scientific Instruments Co., Ltd.), the wavelength is 590 nm under the environment of 23 ° C. and 55% RH.
In three, the three-dimensional refractive index is measured, and the refractive index Nx, Ny,
Nz was determined.

(Retardation (R ₀ , R _t ) Values and Their Distributions) Automatic Birefringence Meter KOBURA · 21ADH
(Oji Keisoku Co., Ltd.), 23 ℃, 55% RH
Under the environment, the three-dimensional birefringence was measured at 1 cm intervals in the width direction of the sample at a wavelength of 590 nm. The in-plane retardation and the retardation in the thickness direction thus obtained were each determined by the standard deviation by the (n-1) method. For the retardation distribution, the coefficient of variation (CV) shown below was determined and used as an index. In the actual measurement, n is 13
It was set to 0 to 140.

Coefficient of variation (CV) = standard deviation / retardation average value (wavelength dispersion characteristic) Automatic birefringence meter KOBURA-21AD
Using H (manufactured by Oji Scientific Instruments), 23 ° C, 55% R
Under the environment of H, at wavelengths of 450 and 650 nm, 3
The dimensional birefringence was measured. The obtained value is R
_{It was set to 450} and _R650 .

The wavelength dispersion characteristics are R ₄₅₀ / R ₀ and R _650.
/ R ₀ was evaluated respectively. (Dry film tear strength)
After conditioned for 4 hours in a room conditioned at 55 ° C and relative humidity of 55%, cut into sample size sample width 50 mm x 64 mm, and
It was determined by measurement according to SO 6383 / 2-1983.

(Dimensional change rate) The film was placed at a temperature of 23 ° C.
After conditioned for 4 hours in a room conditioned at a relative humidity of 55%,
The width (L1) was measured by making marks on the width and the length at intervals of about 10 cm with a cutter. Next, 60 ℃ 9
The film is stored for 24 hours in a thermostatic chamber whose humidity is adjusted to 0%. The film was conditioned again in a room conditioned at a temperature of 23 ° C. and a relative humidity of 55% for 4 hours, and then the distance (L2) of the mark was measured. The dimensional change rate was evaluated by the following formula.

Dimensional change rate (%) = {(L2-L1) / L1} × 100 (Hygroscopic expansion coefficient) The film was placed at a temperature of 23 ° C. and a relative humidity of 55.
After conditioning the humidity for 4 hours in a room where the humidity is controlled to%, mark the width and the length with a cutter at intervals of about 20 cm,
The distance (L3) was measured. Next, the film is stored for 24 hours in a thermostatic chamber whose humidity is controlled at 60 ° C and 90%. After the film was taken out from the constant temperature bath, the distance (L4) of the mark was measured within 2 minutes. The hygroscopic expansion coefficient was evaluated by the following formula.

Hygroscopic expansion rate (%) = {(L4-L3) / L3} × 100 (film thickness distribution) The sample film was heated at 23 ° C. and a relative humidity of 55.
% In the room after humidity control for 4 hours in the room
The film thickness was measured at 0 mm intervals. From the obtained film thickness distribution data, the film thickness distribution R (%) was calculated according to the following formula.

R (%) = {R (max) -R (mi
n)} × 100 / R (ave) where R (max): maximum film thickness, R (min): minimum film thickness, R (ave): average film thickness (haze value) according to JIS K-6714. It was measured using a meter (1001DP type, manufactured by Nippon Denshoku Industries Co., Ltd.) and used as an index of transparency.

(Measurement of Transmittance) Transmittance T was measured by using a spectrophotometer U-3400 (Hitachi Ltd.) and measuring 3 for each sample.
The transmittances of 380, 400 and 500 nm were calculated from the spectral transmittance τ (λ) obtained every 10 nm in the wavelength range of 50 to 700 nm.

(Curl) The film sample was heated at 25 ° C. 55.
After standing in the% RH environment for 3 days, the film is stretched in the width direction 5
It was cut to 0 mm and 2 mm in the longitudinal direction. Further, the film pieces are conditioned under an environment of 23 ° C. ± 2 ° C. and 55% RH for 24 hours, and the curl value of the film is measured using a curvature scale. The curl degree is measured according to JIS-K7619-198.
This was carried out according to Method A of 8.

The curl value is represented by 1 / R, where R is the radius of curvature and the unit is m. (Bright spot foreign material) Two polarizers are sandwiched between two polarizers in an orthogonal state (crossed Nicols state), and light is applied from the outside of one polarizing plate.
From the outside of the other polarizing plate, use a microscope (30
The number of foreign matters that appear to be white and shiny per 25 mm ² was measured. Measurements were a bright spot foreign matter from the number of total 250 mm ² per C over 10 locations to evaluate seek pieces / cm ^2. In the present invention, the size of the bright spot foreign matter is 5 to 5
It was 0 μm ² and nothing more than that was observed.

(Contact angle after saponification treatment) Sample was 2.5 N
NaOH was treated at 50 ° C. for 2.5 minutes, and then washed with pure water for 2.5 minutes. The sample after the treatment was conditioned under a condition of a temperature of 23 ° C. and a relative humidity of 55% for 24 H, and measured using a contact angle meter CA-D type manufactured by Kyowa Interface Science Co.

(Centerline average roughness Ra) The centerline average roughness (Ra) was measured using a non-contact surface fine shape measuring device WYKO NT-2000.

(Image sharpness) Defined in JIS K-7105. When measured with a 1 mm slit, 90% or more is preferable, 95% or more is preferable, and 99% or more is preferable.

(Measurement Method of Water Absorption) The sample is 10 cm ×
Cut it to a size of 10 cm, soak it in water at 23 ° C for 24 hours, and immediately after taking it out wipe off the surrounding water drops with a filter paper,
The mass was measured and designated as W1. Next, this film
After conditioning the humidity for 24 hours in an atmosphere of 23 ° C-55% RH,
The mass was measured and designated as W0. The water absorption rate when immersed in water at 23 ° C. for 24 hours is obtained by calculating from the respective measured values by the following formula.

Water absorption rate (%) = {(W1−W0) / W0} × 100 (Measurement method of water content) A sample was cut into a size of 10 cm × 10 cm, and was cut under an atmosphere of 23 ° C.-80% RH. After the humidity was adjusted over time, the mass was measured and designated as W3. Next, this film was dried at 120 ° C. for 45 minutes, and the mass thereof was measured and designated as W2. The moisture content at 23 ° C.-80% RH is calculated by the following formula from each measured value.

Moisture Content (%) = {(W3-W2) / W2} × 100 (Measurement Method of Moisture Permeability) It is defined as a value that can be measured by the method described in JIS Z 0208. The moisture vapor permeability of the cellulose ester film of the present invention is 25 ° C. and 90% RH.
It is preferably 10~250g / m ² · 24 hours in an environment, further preferably 20~200g / m ² · 24 hours, and most preferably 50~180g / m ² · 24 hours.

The retardation film (also referred to as a retardation plate) of the present invention will be described. The cellulose ester film of the present invention can be used by itself as a retardation film (also referred to as a retardation plate) for enlarging the viewing angle of a liquid crystal display device.

The optical compensation sheet of the present invention will be described. An optical anisotropy containing an optically anisotropic compound is provided on the cellulose ester film of the present invention directly or through another layer to obtain an optical compensation sheet.

When an optically anisotropic layer containing an optically anisotropic compound is provided on a cellulose ester film stretched in the width direction, the optically anisotropic layer is provided on the side facing the support at the time of casting the cellulose ester film. Is preferable from the viewpoint of the smoothness of the film.

When a liquid crystalline compound is applied on a cellulose ester film stretched in the width direction to provide an optically anisotropic layer, it is preferable to provide the optically anisotropic layer on the side not facing the support when the cellulose ester film is cast. It is preferable from the viewpoint of liquid crystal alignment.

The polarizing plate of the present invention and the liquid crystal display device of the present invention using the same will be described. As the polarizer used in the polarizing plate of the present invention, conventionally known ones can be used. For example, a film made of a hydrophilic polymer such as polyvinyl alcohol treated with a dichroic dye such as iodine and stretched, or a film obtained by treating and orienting a plastic film such as vinyl chloride is used. The polarizer thus obtained is laminated with a cellulose ester film.

The polarizing plate is constituted by laminating the optical compensation film of the present invention on at least one side of the polarizer, and in the case of only one side, the cellulose ester film of the present invention in which the liquid crystal layer is not coated on the other side. A support or other transparent support or a TAC (triacetate) film may be used.

The cellulose ester film of the present invention can be preferably used also as a polarizing plate protective film. For example, an optical anisotropic layer in which liquid crystal is applied and aligned and fixed (for example, a layer fixed by hybrid alignment) is provided directly or through an alignment layer, and this is used as a polarizing plate protective film to have a viewing angle expansion effect. A polarizing plate can be manufactured.

For example, a polarizing plate having a structure of antireflection layer / antiglare layer / polarizing plate protective film (TAC) / polarizer / cellulose ester film of the present invention / alignment layer / optically anisotropic layer can be prepared.

When the cellulose ester film is stretched in the width direction, it is preferable to stretch it under the condition that the surface energy of the film after the stretching is controlled within a certain range.

When the cellulose ester film is stretched in the width direction, it is preferable to stretch it under the condition that the conductivity of the film after stretching is controlled within a certain range.

When the cellulose ester film is stretched in the width direction, it is preferable to stretch it under the condition that the curl of the film after stretching is controlled within a certain range.

Specifically, the temperature is 23 ° C. and the relative humidity is 55%.
The curl value at 20 is preferably in the range of -20 (l / m) to 20 (1 / m), and more preferably in the range of -15 (1 / m) to 1.
It is in the range of 5 (1 / m), and particularly preferably -10.
The range is (1 / m) to 10 (1 / m).

When the cellulose ester film is used as a polarizing plate protective film, if the durability of the polarizing plate and the water absorption rate during the production of the polarizing plate exceed 4.5%, the durability of the polarizing plate may be problematic. Yes, 1.0%
If it is less than the above range, the drying property is deteriorated when the polarizer and the protective film are attached and dried during the production of the polarizing plate.

The water content of the cellulose ester film is preferably 0.5% to 4.5%, more preferably 1.5%.
To 3.5% is more preferable, and 1.5% to 3.0
Most preferably, it is in the range of%.

The polarizing plate thus obtained may be provided on one side of the liquid crystal cell on the cell side or on both sides thereof.
In any case, the optical compensation film of the present invention can be attached to the polarizer closer to the liquid crystal cell to obtain the liquid crystal display device of the present invention.

When the optical compensation film of the present invention is installed in a liquid crystal display device, an upper polarizer and a lower polarizer arranged above and below a pair of substrates located on both sides of a driving liquid crystal cell are usually constructed. At this time, at least one optical compensation film of the present invention is provided between the substrate and either the upper or lower polarizer, or between the substrate and each of the upper and lower polarizers, but at a low cost. In order to effectively realize the object of the invention and the object of the invention, one sheet of the optical compensation film of the invention is provided between the viewer-side polarizer and the driving cell-side substrate in the case of a display device. Preferably.

When the liquid crystal display device is a twisted nematic type (TN type) liquid crystal display device, the optical compensation film is provided on the substrate closest to the TN type liquid crystal cell in the direction in which the cellulose ester film support surface of the optical compensation film is in contact. Laminating, and laminating in a direction in which the maximum refractive index direction in the surface of the cellulose ester film support of the optical compensation film is substantially orthogonal to the alignment direction of the nematic liquid crystal of the substrate closest to the liquid crystal cell of the present invention. The purpose can be effectively expressed. Substantially orthogonal means 90 ° ± 5 °
However, 90 ° is preferable.

[0210]

EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited thereto.

Example 1 << Preparation of Cellulose Ester Film 1 >> A dope solution and an ultraviolet absorbent solution were prepared as described below, and Cellulose ester film 1 was prepared using them.

(Preparation of Dope) Degree of Substitution of Acetyl Group 2.
00, cellulose acetate propionate 100 having a degree of substitution of propionyl groups of 0.80 and a viscosity average degree of polymerization of 350
Parts by mass, 2 parts by mass of ethylphthalylethyl glycolate,
8.5 parts by mass of triphenyl phosphate, 290 parts by mass of methylene chloride, and 60 parts by mass of ethanol were placed in a closed container, and the temperature of the mixture was gradually raised while slowly stirring.
The temperature was raised to 45 ° C over a period of time and dissolved. The pressure in the container was 1.2 atm. Azumi filter paper N manufactured by Azumi Filter Paper Co., Ltd.
o. After filtering using 244, it was left standing for 24 hours to remove bubbles in the dope.

(Preparation of Ultraviolet Absorber Solution) Separately from this, 5 parts by mass of the above cellulose acetate propionate, 6 parts by mass of TINUVIN 326 (manufactured by Ciba Specialty Chemicals Co., Ltd.), TINUVIN 109 (Ciba. Specialty Chemicals Co., Ltd.) 4 parts by mass, Tinuvin 171 (Ciba Specialty Chemicals Co., Ltd.)
5 parts by mass of 94 parts by mass of methylene chloride and 8 parts by mass of ethanol were mixed and dissolved by stirring to prepare an ultraviolet absorbent solution.

The above UV absorber solution was added at a ratio of 2 parts by mass to 100 parts by mass of the dope and thoroughly mixed by a static mixer. Then, the dope temperature was 30 ° C. and the width was 1.6 m on the stainless belt from the die. It was cast. After contacting hot water at a temperature of 25 ° C. from the back surface of the stainless belt and drying for 1 minute on the temperature-controlled stainless belt,
Further, cold water at 15 ° C. was brought into contact with the back surface of the stainless belt to hold for 15 seconds, and then the stainless belt was peeled off.

The amount of residual solvent in the web at the time of peeling was 80% by mass. Then, the film was conveyed at a film conveying tension of 100 N / m in the D0 zone. The ethanol / (methylene chloride + ethanol) mass at the end point of D0 was 70%.

Then, using a uniaxial stretching tenter, both ends of the web separated in step A were held by clips, and in step B, the clip interval was changed in the width direction at a stretching speed of 250% / min. At this time, the film atmosphere temperature was 120 ° C. and the stretching ratio was 1.5 times.

The film temperature at the start of stretching is 80 ° C., the residual solvent amount is 25% by mass, and the film temperature is 12 at the end of stretching.
At 0 ° C., the amount of residual solvent was 60% at the start of stretching, and the mass of ethanol / (ethanol + methylene chloride) was 93%.

Then, in step C, the film was conveyed while being held. In step C, relaxation was performed so that the width in step B was 98%. The methylene chloride atmosphere concentration in steps A and B was 4000 ppm. The methylene chloride atmosphere concentration in step C was 60% or less of the saturated concentration. Subsequently, step D1 in which the ambient temperature is set to 100 ° C.
The film was dried with to obtain a cellulose ester film 1.

At the end of step B, the film elastic modulus is 600.
N / mm ² , and the film elastic modulus at the start of step D1 was 2000 N / mm ² .

The resulting cellulose ester film was
Width of a glass fiber reinforced resin core with a core diameter of 200 mm 1
The film was wound into a film roll having a length of m and a length of 1000 m by the taper tension method. At this time, the temperature 2
An embossing ring at 50 ° C. was pressed against the surface to perform thickness-raising processing to prevent the films from sticking to each other.

The center of the film taken out from the obtained film roll was used for sampling, and the width, length,
When Nx, Ny, and Nz of the refractive index in the film thickness direction were measured, they were 1.47783, 1.47703, 1.
It was 47613. The film thickness was 80 μm.

Then, the following optical characteristics were measured. Nx-Ny = 0.0008 (Nx + Ny) /2-Nz=0.0013 R 0 = 64nm R t = 104nm R t / R 0 = 1.63 R 0 distribution = 1.4% R _t distribution = 1.6 % Further, when the central part of the film was sampled from the obtained film roll and the haze value was measured, it was 0.1%.

From the above, it is understood that the cellulose ester film 1 of the present invention has excellent optical characteristics suitable for applications such as retardation films and optical compensation sheets.

Example 2 << Preparation of Cellulose Ester Film 2 >> In the same manner as the preparation of the cellulose ester film 1, a dope was prepared and cast and peeled on the belt. The amount of residual solvent in the web at the time of peeling was 90% by mass. Then, the film was conveyed at a film conveying tension of 100 N / m in the D0 zone.
The ethanol / (methylene chloride + ethanol) mass at the end point of D0 was 62%.

Then, both ends of the web separated in step A were gripped with clips using a uniaxial stretching tenter, and in step B, the clip interval was widened in the width direction at a stretching rate of 250% / min. At this time, the film atmosphere temperature was 170 ° C. and the stretching ratio was 1.5 times.

The film temperature at the start of stretching is 80 ° C., the residual solvent amount is 30% by mass, and the film temperature at the end of stretching is 10%.
At 0 ° C., the amount of residual solvent was 90% at the start of stretching, and the mass of ethanol / (ethanol + methylene chloride) was 66%.

In the next step C, the width in step B is 98
It was eased so that it became%. The methylene chloride atmosphere concentration in steps A and B was 4000 ppm. Also, process C
The methylene chloride atmosphere concentration in was less than 60% of the saturated concentration.

Subsequently, the film was dried in step D1 in which the atmospheric temperature was set to 100 ° C. to obtain a cellulose ester film 2.

The elastic modulus of the film at the end of the step B is 500 N.
/ Mm ² , and the film elastic modulus at the start of step D1 was 1800 N / mm ² .

The obtained film has a glass fiber reinforced resin core having a core diameter of 200 mm and a width of 1 m and a length of 1000 m.
The film was wound into a film roll by taper tension method. At this time, an embossing ring at a temperature of 250 ° C. was pressed against the edges of the film, and a thickness of about 10 μm was applied to prevent the films from adhering to each other.

The obtained film roll was sampled from the central part of the film, and the width, length and refractive index in the film thickness direction were measured for Nx, Ny and Nz by the above. These are 1.47790, 1.47710, 1.476, respectively.
00 and the film thickness was 80 μm.

Then, the following optical characteristics were measured. Nx-Ny = 0.0008 (Nx + Ny) /2-Nz=0.0015 R 0 = 64nm R t = 120nm R t / R 0 = 1.88 R 0 distribution = 1.3% R _t distribution = 1.4 % The slow axis direction of each sample was within ± 0.4 degrees with respect to the width direction of the film. The central part of the film was sampled from the obtained film roll and the haze value was measured and found to be 0.1%.

From the above, it is understood that the cellulose ester film 2 of the present invention has excellent optical characteristics suitable for applications such as a retardation film and an optical compensation sheet.

Example 3 << Preparation of Cellulose Ester Film 3 (Comparative Example) >> A dope was prepared in the same manner as the preparation of the cellulose ester film 1, and the dope was cast and peeled on the belt. The amount of residual solvent in the web at the time of peeling was 90% by mass. Then, D
The film was conveyed at a tension of 100 N / m in the 0 zone. The ethanol / (methylene chloride + ethanol) mass at the end of D0 was 95%.

Then, both ends of the web separated in step A were gripped with clips using a uniaxial stretching tenter. In step B, the clip interval was changed in the width direction by a stretching speed of 250% / min. At this time, the film atmosphere temperature was 170 ° C. and the stretching ratio was 1.5 times.

The film temperature at the start of stretching is 150 ° C., the amount of residual solvent is 4% by mass, and the film temperature at the end of stretching is 17
At 0 ° C., the amount of residual solvent was 30% at the start of stretching, and the mass of ethanol / (ethanol + methylene chloride) was 98%.

Next, in step C, the film was conveyed while being held. The methylene chloride medium atmosphere concentration in steps A and B was 4000 ppm.

Subsequently, the film was heated to an ambient temperature of 100.
The cellulose ester film 3 was conveyed by the process D1 set to 0 degreeC, and was dried. The film elastic modulus in step B was 1500 N / mm ² , and the film elastic modulus in step D1 was 2000 N / mm ² .

The cellulose ester film obtained was
Width of a glass fiber reinforced resin core with a core diameter of 200 mm 1
The film was wound into a film roll having a length of m and a length of 1000 m by the taper tension method. At this time, the temperature 2
An embossing ring at 50 ° C. was pressed against the surface to perform thickness-raising processing to prevent the films from sticking to each other.

The obtained film roll was sampled from the central portion of the film, and the refractive indexes in the width, the length and the film thickness direction were measured for Nx, Ny and Nz by the following. 1.47792, 1.47742, 1.47 respectively
567 and the film thickness was 80 μm. From these,
Nx−Ny, (Nx + Ny) / 2−Nz, R ₀ , and R _t were calculated, and they were 0.0005 and 0.00, respectively.
It was 2, 40.0 nm and 160.0 nm.

R _t is very high as compared with R _0, and a problem remains as a retardation film for improving the viewing angle. Further, the direction of the slow axis exceeded ± 2 degrees with respect to the film width direction.

Other evaluation results of the obtained film are shown below. In-plane retardation distribution (R ₀ ) 5.1% Thickness direction retardation (R _t ) distribution 11.2% Thickness R (ave) 80 μm Maximum thickness R (max) 83.4 μm Minimum thickness R (Min) 76.1 μm Film thickness distribution R (%) 9.1% Transmittance (500 nm) 80% Transmittance (400 nm) 78% Transmittance (380 nm) 12% Haze 2.1% Center line average roughness (Ra) ) 21.1 nm Dimensional change rate (Smd) -0.41% Dimensional change rate (Std) -0.51% Hygroscopic expansion coefficient (MD) 1.2% Hygroscopic expansion coefficient (TD) 2.3% Tear strength (MD) ) 2.2 N / μm tear strength (TD) 1.2 N / μm Htd / Hmd 0.6 stress at break (MD) 45 MPa stress at break (TD) 32 MPa elongation at break (MD) 15% elongation at break (MD) TD) 12% Sex ratio (MD) 1.4 GPa elastic modulus (TD) 1.3 GPa curl (23 ℃, 55% RH) 45m -1 85 amino bright defect / cm ² plasticizer content ratio (G2 / G1) 0.88 saponification Contact angle after treatment 65 ° Water vapor transmission rate 260 g / m ² · 24 h Example 4 << Preparation of Cellulose Ester Films 4-9 >> In preparation of Cellulose Ester Film 1, the same dope except that the acetyl substitution degree is 1.9. Width,
Cellulose ester films 4 to 9 were produced in the same manner, except that the tear strength ratio (Htd / Hmd) in the longitudinal direction was adjusted as shown in Table 1.

For each of the obtained films, the retardation (R ₀ ) in the in-plane direction of the film and the retardation (R _t ) in the thickness direction of the film were obtained, and the retardation ratio (R _t / R ₀ ) was calculated as Was calculated. The results obtained are shown in Table 1.

[0244]

[Table 1]

From Table 1, the tear strength ratio (Htd / Hm
It can be seen that the cellulose ester films 5 to 8 produced so that d) is 0.62 to 1.0 exhibit optical characteristics suitable for use in retardation films, optical compensation sheets and the like.

Example 5 << Preparation of Cellulose Ester Films 10-18 >> The degree of propionyl substitution of the cellulose acetate propionate used for preparation of the cellulose ester film 1 was 0.7.
The same dope is used except that the width change and the dimensional change in the longitudinal direction are Std (%) and Smd (%), respectively. Std (%) and Smd (%) are shown in Table 2 below. The film was stretched in the width direction so as to satisfy the conditions of, and cellulose ester films 10 to 18 were produced.

Also, the retardation ratio (R _t / R ₀ ) obtained for each film is shown.

[0248]

[Table 2]

From Table 2, the cellulose ester film 1 stretched under the conditions that Std is in the range of -0.4 to 0.4% and Smd is set in the range of -0.4 to 0.4%.
It can be seen that 0 to 16 show optical characteristics suitable for use in a retardation film, an optical compensation sheet and the like.

Example 6 << Preparation of Cellulose Ester Films 19 to 23 >> Cellulose acetate propionate used to prepare Cellulose Ester Film 1 had an acetyl substitution degree of 1.9 and a propionyl substitution degree of 0.7. Is stretched in the width direction so that the above-mentioned film thickness distribution R (%) in the width direction satisfies the conditions shown in Table 3 below, to produce cellulose ester films 19 to 23, respectively. . Also, the retardation ratio (R _t / R ₀ ) obtained for each film is shown.

[0251]

[Table 3]

From Table 3, it can be seen that the cellulose ester films 19 to 22 stretched under the condition that the film thickness distribution is 0 to 8% show optical characteristics suitable for use in retardation films, optical compensation sheets and the like. .

Example 7 << Preparation of Polarizing Plate >> (Preparation of viewing angle compensation elliptical polarizing plate A) A triacetyl cellulose support (manufactured by Konica Corp., film thickness = 80 μm) was used.
It was immersed in an aqueous sodium hydroxide solution having a concentration of 2 mol / l at 0 ° C. for 2 minutes, washed with water, and then dried at 100 ° C. for 10 minutes to obtain an alkali saponification-treated triacetyl cellulose support.

Further, a polyvinyl alcohol film having a thickness of 120 μm was immersed in 100 parts by mass of an aqueous solution containing 1 part by mass of iodine and 4 parts by mass of boric acid, and stretched 4 times at 50 ° C. to form a polarizing film (polarizer 1). Had made.

Polarizing plate 1 was prepared by laminating the alkali-saponified triacetyl cellulose support on both surfaces of the above-mentioned polarizer 1 using a completely saponified polyvinyl alcohol 5% aqueous solution as an adhesive.

Subsequently, a gelatin thin film (0.1 μm) was coated on one surface of the above-mentioned polarizing plate 1, and an alkyl-modified polyvinyl alcohol having the structure shown below was added to methanol / water =
A 1: 3 1.5% solution was applied with wire bar # 3. This was dried with warm air at 65 ° C., and then, on the surface of the support, the alkyl-modified polyvinyl alcohol-coated surface was rubbed in a direction parallel to the absorption axis of the polarizing plate to form an alignment layer. Let these be polarizing plates 1a.

[0257]

[Chemical 1]

On the alignment layer of the polarizing plate 1a prepared above,
The following solution LC-1 was applied using a wire bar # 6.
Furthermore, this is dried for 30 seconds in a windless condition at 55 ° C, and then 1
After heat treatment at 00 degrees for 30 seconds, the temperature is gradually lowered to 98
After purging with nitrogen for 60 seconds at kPa, oxygen concentration 0.1%
A film cured by 450 mJ / cm ² ultraviolet light under the conditions was prepared. In this way, a polarizing plate 1b having one optically anisotropic layer in which the orientation of the liquid crystal compound was fixed was obtained.

Further, the optically anisotropic layer surface of the polarizing plate 1b obtained above and the cellulose ester film 1 described in Example 1 were used.
And SK Dyne 20 were used as an adhesive so that the transmission axis of the polarizer was aligned with the direction in which the maximum refractive index of the cellulose ester film 1 was given to obtain a viewing angle compensation elliptically polarizing plate A. .

[0260]   (Composition of solution LC-1)   MEK 86 parts   Compound 2 3 parts   Compound 3 2 parts   Compound 4 3 parts   Compound 5 3 parts   Irgacure 369 (manufactured by Ciba Specialty Chemicals)

[0261]

[Chemical 2]

<< Evaluation of Viewing Angle Compensating Elliptical Polarizing Plate >> The viewing angle compensating elliptical polarizing plate of the present invention obtained above was manufactured by NEC 15
Type liquid crystal display Multi Sync LCD15
The previously laminated optical compensation film of 25 J and the polarizing plate were peeled off, and they were laminated so that the absorption axis of the viewing angle compensation elliptical polarizing plate of the present invention was in the same direction as the absorption axis of the previously laminated polarizing plate. .

The viewing angle was evaluated by subjecting the liquid crystal panel on which the viewing angle compensating elliptically polarizing plate of the present invention obtained above was laminated to ELDI.
The viewing angle was measured using EZ-contrast manufactured by M company.

As the evaluation of the viewing angle, the contrast ratio between the white display and the black display of the liquid crystal panel was 10 or more, and the range of the tilt angle from the normal direction to the panel surface showing the region where the inversion occurred was evaluated. As a result, the sample of the present invention had an extremely high viewing angle improving property.

Example 8 << Preparation of Cellulose Ester Film 24 >> A dope was prepared in the same manner as in the preparation of the cellulose ester film 1, and was cast and peeled on the belt. The amount of residual solvent in the web at the time of peeling was 90% by mass. Then, the film was conveyed in the D0 zone at a tension of 150 N / m.
The content of ethanol / (methylene chloride + ethanol) at the end point of D0 was 30% by mass.

[0266] Then, the both ends of the film were cut off by 10 cm with a slitter, and then both ends of the web peeled in step A were gripped with clips using a uniaxial stretching tenter.

In step B, the clip interval was changed in the width direction by a stretching speed of 130% / min. At this time, the film atmosphere temperature was 110 ° C. and the stretching ratio was 1.4 times. The film temperature at the start of stretching is 60 ° C., the residual solvent amount is 20% by mass, the film temperature at the end of stretching is 100 ° C., the residual solvent amount is 90% at the start of stretching, and ethanol / (ethanol + methylene chloride) mass Was 93%.

Next, in step C, the film was gripped and conveyed. In step C, relaxation was performed so that the width in step B was 97%. The methylene chloride atmosphere concentration in steps A and B was 2000 ppm. The methylene chloride atmosphere concentration in step C was 60% or less of the saturated concentration.

Further, a neutral zone for preventing temperature interference is provided between the zones of the A, B and C steps.

Subsequently, the film was dried in step D1 in which the ambient temperature was set to 100 ° C. to obtain a cellulose ester film 24.

The film elastic modulus at the end of the process B is 550 N.
/ Mm ² , and the film elastic modulus at the start of step D1 was 1800 N / mm ² .

The cellulose ester film 24 comprises a glass fiber reinforced resin core having a core diameter of 200 mm and a width of 1 m.
It was wound into a film roll having a length of 1000 m by the taper tension method. At this time, a temperature of 250
An embossing ring at a temperature of 0 ° C. was pressed against the surface, and a film having a height of about 10 μm was processed to prevent the films from sticking to each other.

The physical properties of the obtained film are summarized below. Nx 1.4778 Ny 1.4772 Nz 1.4760 R ₀ 50 nm R _t 120 nm R _t / R ₀ 2.4 R ₄₅₀ / R ₀ 0.88 R ₆₅₀ / R ₀ 1.03 Orientation angle distribution ± 0.5 ° Retardation distribution (R ₀ ) 1% Retardation distribution (R _t ) 1.4% Film thickness R (ave) 80.0 μm Maximum film thickness R (max) 80.5 μm Minimum film thickness R (min) 79.5 μm Thickness distribution R (%) 1.3% Transmittance (500 nm) 92.2% Transmittance (400 nm) 58.2% Transmittance (380 nm) 2.3% Haze 0.1% Center line average roughness (Ra) ) 1.65 nm Dimensional change rate (Smd) -0.05% Dimensional change rate (Std) -0.03% Hygroscopic expansion coefficient (MD) 0.1% Hygroscopic expansion coefficient (TD) 0.07% Tear strength (MD) ) 2.3 N / μm Tear strength (T D) 2.0 N / μm Stress at break (MD) 93 MPa Stress at break (TD) 87 MPa Elongation at break (MD) 40% Elongation at break (TD) 45% Elastic modulus (MD) 2.8 GPa Elastic modulus ( TD) 3.0 GPa curl (23 ° C., 55% RH) 8 m ⁻¹ bright spot foreign matter 21 / cm ² plasticizer content ratio (G2 / G1) 0.99 contact angle after saponification treatment 17 °, moisture vapor transmission rate 245 g / m ² · 24h It can be seen that the cellulose ester film 24 of the present invention exhibits optical characteristics suitable for use as a retardation film, an optical compensation sheet and the like.

Also, the viewing angle compensation elliptical polarizing plate A of Example 7 was used.
In the production of, a viewing angle compensation elliptically polarizing plate was produced in the same manner except that the cellulose ester film 24 was used instead of the cellulose ester film 1, and the viewing angle characteristics were changed in the same manner as described in Example 7. evaluated. As a result, it was found that, as compared with the case where the optical compensation film and the polarizing plate which were previously attached to the Multi Sync LCD1525J were used, a very high viewing angle improving property was exhibited.

Example 9 A polarizer 1 was produced in the same manner as in Example 7.
Further, the cellulose ester film 24 obtained in Example 8 was immersed in a sodium hydroxide aqueous solution having a concentration of 2 mol / l for 2 minutes at 60 ° C., washed with water, and then dried at 100 ° C. for 10 minutes to give an alkali saponification-treated transparent support. Body B is obtained.

A gelatin thin film (0.1 μm) was applied to the surface of the transparent support B which was in contact with the belt support at the time of casting, and the above-mentioned alkyl-modified polyvinyl alcohol was mixed with methanol / water = 1: 3. Wire bar with 1.5% solution #
3 was applied. This was dried with warm air at 65 ° C., and then, on the surface of the support, the alkyl-modified polyvinyl alcohol-coated surface was rubbed parallel to the longitudinal direction during film formation to form an alignment layer.

Further, the above solution LC-1 was treated with a wire bar #
6 was used for coating. This was dried for 30 seconds in a windless state at 55 ° C., then heat-treated at 100 ° C. for 30 seconds, gradually cooled, and nitrogen purged at 98 kPa for 60 seconds, and then 450 mJ / cm 2 under an oxygen concentration of 0.1%. An optical compensatory sheet C having an optically anisotropic layer containing an optically anisotropic compound in which the orientation of the liquid crystal compound was fixed was obtained by producing a film cured by the ultraviolet ray of ² .

The polarizer 1 and the surface of the optical compensatory sheet C having the optically anisotropic layer obtained above were bonded to each other with SK Dyne 20 as an adhesive, and the transmission axis of the polarizing plate 1 and the slow axis of the transparent support B were used. Were adhered to each other to obtain a viewing angle compensation elliptically polarizing plate D.

The obtained viewing angle-compensating elliptically polarizing plate D was evaluated for viewing angle in the same manner as in Example 7, and as a result, it was found to have extremely high viewing angle characteristics.

Example 10 The same procedure as in Example 9 except that a gelatin thin film (0.1 μm) was applied to the surface of the transparent support B which was in contact with the belt support during casting. Then, an alignment layer and an optical compensation sheet were produced to obtain a viewing angle compensation elliptically polarizing plate E. The obtained viewing angle compensation elliptically polarizing plate E was used in Example 7.
As a result of evaluation of the viewing angle in the same manner as described in (1), it was found that an extremely high viewing angle characteristic was exhibited.

Example 11 << Preparation of Cellulose Ester Film 25 >> Cellulose Acetate Propionate Used for Preparation of Cellulose Ester Film 1 The degree of substitution of acetyl group is 1.9 The degree of substitution of propionyl group is 0.75 Except that the cellulose ester film 2 of Example 8 was used
Cellulose Ester Film 2
Got 5. The physical properties of the obtained film are summarized below.

Nx 1.4781 Ny 1.4772 Nz 1.4758 R ₀ 70 nm R _t 150 nm R _t / R ₀ 2.1 R ₄₅₀ / R ₀ 0.91 R ₆₅₀ / R ₀ 1.04 Orientation angle distribution ± 0 Within 0.5 ° Retardation distribution (R ₀ ) 1.2% Retardation distribution (R _t ) 1.5% Film thickness R (ave) 80.0 μm Maximum film thickness R (max) 80.6 μm Minimum film thickness R ( min) 79.4 μm Film thickness distribution R (%) 1.5% Transmittance (500 nm) 92.1% Transmittance (400 nm) 58.4% Transmittance (380 nm) 2.3% Haze 0.1% Center line Average roughness (Ra) 1.66 nm Dimensional change rate (Smd) -0.05% Dimensional change rate (Std) -0.08% Hygroscopic expansion coefficient (MD) 0.1% Hygroscopic expansion coefficient (TD) 0.07 % Tear strength (MD) 2.3 N / μm Tear strength (TD) 2.0 N / μm Stress at break (MD) 91 MPa Stress at break (TD) 87 MPa Elongation at break (MD) 39% Elongation at break (TD) 45% Elastic modulus (MD) 2.8 GPa Elastic modulus (TD) 3.0 GPa Curl (23 ° C. 55% RH) 8 m ⁻¹ bright spot foreign substance 23 / cm ² plasticizer content ratio (G2 / G1) 0.99 Contact angle after saponification 18 ° Moisture vapor transmission 248 g / M ² · 24h From the above, the cellulose ester film 25 of the present invention
It can be seen that has excellent optical characteristics suitable for applications such as a retardation film and an optical compensation sheet.

Example 12 << Preparation of viewing angle compensation elliptically polarizing plate F (comparative example) >> Example 7
In the production of the viewing angle compensation circularly polarizing plate A, the viewing angle compensation circularly polarizing plate F is produced in the same manner except that the cellulose ester film 3 described in Example 3 is used in place of the cellulose ester film 1. did.

Using the obtained viewing angle compensation elliptically polarizing plate F, viewing angle characteristics were evaluated in the same manner as in Example 7. As a result, the viewing angle characteristics were not improved, and the viewing angle was uneven, which left a problem in practical use.

Example 13 << Preparation of viewing angle compensation elliptically polarizing plate G (comparative example) >> (Preparation of alkali saponification-treated transparent support G) In the process of obtaining the alkali saponification-treated transparent support B described in Example 9, Instead of the cellulose ester film 24, the cellulose ester film 3 obtained in Example 3 (comparative example) was used to obtain an alkali saponification-treated transparent support G.

(Preparation of viewing angle compensation elliptically polarizing plate G) In preparation of the viewing angle compensation elliptically polarizing plate D described in Example 9, instead of the alkali saponification treated transparent support B, the alkali saponification treated transparent substrate obtained above was used. A viewing angle compensation elliptically polarizing plate G was prepared in the same manner except that the support G was used.

Using the obtained viewing angle compensation elliptically polarizing plate G, viewing angle characteristics were evaluated in the same manner as in Example 7. As a result, the viewing angle characteristics were not improved, and the viewing angle was uneven, which left a problem in practical use.

Example 14 << Preparation of Cellulose Ester Film 26 >> Cellulose acetate propionate used for preparation of cellulose ester film 1 has a degree of substitution of acetyl groups of 1.9 and a degree of substitution of propionyl groups of 0.75. A cellulose ester film 26 was obtained using the ester. Casting was performed in a manner similar to that in Example 1.

Details regarding the conditions during casting are summarized below. Residual solvent amount at peeling 80% by mass D0 zone tension 100 N / m D0 zone ethanol / (methylene chloride + ethanol) 70% by mass Stretching speed in step B 200% / min Step B film atmosphere temperature 110 ° C. Step B stretching ratio 1. 2 times Stretching start film temperature 65 ° C Stretching start film residual solvent amount 22% Stretching end film temperature 80 ° C Stretching end residual solvent amount / Stretching start residual solvent amount 72% Stretching end (ethanol) / (ethanol + Methylene chloride) 94% by mass Step C relaxation rate 97% Step A methylene chloride atmosphere concentration 4000 ppm Step B methylene chloride atmosphere concentration 4000 ppm Step C methylene chloride atmosphere concentration 60% or less of saturation amount Film elastic modulus at the end of step B 800 N / mm film elasticity 2200N / mm ² obtained at the time of ^two steps D1 starts The physical properties of the obtained film are shown below.

Nx 1.4776 Ny 1.4773 Nz 1.4761 R ₀ 30 nm R _t 105 nm R _t / R ₀ 3.5 R ₄₅₀ / R ₀ 0.91 R ₆₅₀ / R ₀ 1.04 Orientation angle distribution ± 0 Within 0.5 ° Retardation distribution (R ₀ ) 1.3% Retardation distribution (R _t ) 1.6% Film thickness R (ave) 80.0 μm Maximum film thickness R (max) 80.4 μm Minimum film thickness R ( min) 79.4 μm Film thickness distribution R (%) 1.3% Transmittance (500 nm) 92.1% Transmittance (400 nm) 58.4% Transmittance (380 nm) 2.3% Haze 0.1% Center line Average roughness (Ra) 1.54 nm Dimensional change rate (Smd) -0.05% Dimensional change rate (Std) -0.08% Hygroscopic expansion coefficient (MD) 0.12% Hygroscopic expansion coefficient (TD) 0.07 % Tear strength (MD) 2.1 N / μ m Tear strength (TD) 2.0 N / μm Stress at break (MD) 91 MPa Stress at break (TD) 87 MPa Elongation at break (MD) 40% Elongation at break (TD) 45% Elastic modulus (MD) 2. 8 GPa elastic modulus (TD) 2.9 GPa curl (23 ° C., 55% RH) 6 m ⁻¹ bright spot foreign matter 21 / cm ² plasticizer content ratio (G2 / G1) 0.99 contact angle after saponification treatment 19 ° transmission From the humidity of 247 g / m ² · 24 h or more, the cellulose ester film 26 of the present invention
It can be seen that has excellent optical characteristics suitable for applications such as a retardation film and an optical compensation sheet.

Example 15 Preparation of Viewing Angle Compensating Elliptical Polarizing Plate H (Invention) (Preparation of Alkali Saponification Treated Triacetyl Cellulose Support) Alkali saponification treated triacetyl cellulose support was carried out in the same manner as in Example 7. Got the body

(Preparation of Cellulose Ester Film 27) Alkali saponification-treated cellulose ester film 27 was prepared by treating with alkali in the same manner as cellulose ester film 26 prepared in Example 14. The optical characteristics of the alkali-saponification-treated cellulose ester film 27 were not different from those of the cellulose ester film 26.

(Production of Polarizer 1) Polarizer 1 was produced in the same manner as in Example 7.

(Production of Viewing Angle Compensating Elliptical Polarizing Plate H)
One side of the polarizer 1 is laminated with an alkali-saponified triacetyl cellulose support, the other side is an alkali-saponified cellulose ester film 27, and a fully saponified polyvinyl alcohol 5% aqueous solution is used as an adhesive to bond the respective viewing angles. A compensating elliptically polarizing plate H was produced.

The viewing angle characteristics of the obtained viewing angle compensation elliptically polarizing plate H were evaluated in the same manner as in Example 7. still,
The cellulose ester film 27 was attached and evaluated so that the side of the film was in contact with the cell side of the liquid crystal panel. As a result, the sample of the present invention had an extremely high viewing angle improving property.

Example 16 << Preparation of viewing angle compensation elliptically polarizing plate I >> In preparation of the viewing angle compensation elliptically polarizing plate I, the cellulose ester film 26 was prepared.
A viewing angle compensation elliptically polarizing plate I was prepared in the same manner except that the comparative cellulose ester film 3 described in Example 3 was used instead of.

With respect to the obtained viewing angle compensation elliptically polarizing plate I, viewing angle characteristics were evaluated in the same manner as in Example 7.
As a result, the viewing angle characteristics were insufficient and there was a practical problem.

[0298]

The present invention can provide a cellulose ester film having excellent optical properties, a method for producing the film, a retardation film having the film, an elliptically polarizing plate, an optical compensation sheet and a display device. It was

[Brief description of drawings]

FIG. 1 is a diagram illustrating a stretching angle in a stretching process.

FIG. 2 is a schematic view showing an example of a tenter process used in the present invention.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) // B29K 1:00 B29K 1:00 B29L 7:00 B29L 7:00 C08L 1:00 C08L 1:00 ( 72) Inventor Noriyasu Kuzuhara 1st Sakura-cho, Hino City, Tokyo Konica Stock Association In-house F-term (reference) 2H049 BA06 BA42 BB03 BB33 BC03 2H091 FA08X FA08Z FA11X FA11Z FB02 FB12 FB13 FC01 FC08 FC09 FD06 HA07 HA09 KA02 LA19 A07 LA10 LA12 LA19 4A07 AF09 AF16 AF20 AF21 AF30 AF31 AF43 AH12 4F210 AA24 AG01 AH73 AR04 AR12 QA02 QC03 QD01 QG01 QG18 QL01 QW17

Claims (50)

[Claims] 1. When Nx, Ny, and Nz are the refractive indices in the width, length, and film thickness directions, respectively, Nx>Ny> Nz, and the in-plane retardation is R ₀ (nm),
In the method for producing a cellulose ester film, wherein R _t / R ₀ is 0.8 to 3.5, where R _t (nm) is the retardation in the thickness direction, cellulose peeled off after casting on a support Step D0 of transporting the ester film, Step A of gripping the end portion of the width,
Production of a cellulose ester film having a step B of stretching in the width direction, wherein the residual solvent amount of the film represented by the following general formula (1) at the start of stretching is 90% by mass to 5% by mass. Method. General formula (1) Residual solvent amount (% by mass) of film = {(M−N) / N}
× 100 [In the formula, M is the mass of the web at the time of measurement, and N is the mass of the web for which M was measured, and dried at 110 ° C. for 3 hours. ] _{R 0 = (Nx-Ny)} × d R t = ((Nx + Ny) / 2-Nz) × d wherein, Nx is the refractive index in the width direction of the film, Ny is the refractive index in the longitudinal direction of the film, Nz is the refractive index in the film thickness direction, and d is the film thickness (nm). ] 2. The method for producing a cellulose ester film according to claim 1, wherein the transport tension of the film in the step D0 is in the range of 30 N / m to 300 N / m. 3. At the end of the step D0, the following general formula (2)
The poor solvent content (%) in the residual solvent in the film represented by is 15 mass% to 95 mass%, The manufacturing method of the cellulose-ester film of Claim 2 characterized by the above-mentioned. General formula (2) Poor solvent content (%) in the residual solvent in the film =
{(Mass of poor solvent in residual solvent amount of film) / (mass of poor solvent in residual solvent amount of film + mass of good solvent)}
× 100 4. The method has a step B of stretching the peeled cellulose ester film in the width direction after casting on a support, and the retardation in the film plane is R ₀ (nm),
In the method for producing a cellulose ester film in which R _t / R ₀ is 0.8 to 3.5 when the retardation in the thickness direction is R _t (nm), the residual solvent amount B 0% of the film at the start of step B Is 90% by mass to 10% by mass, the temperature of the film is 30 ° C. to 140 ° C., and the film temperature at the end of step B is 70 ° C. to 140 ° C.
C, and when the residual solvent amount of the film at the end of step B is B1%, B0% and B1% are 0.4 × B
A method for producing a cellulose ester film, which satisfies the relationship of 0 ≦ B1 ≦ 0.8 × B0. 5. The cellulose ester film according to claim 4, wherein the poor solvent content (%) in the residual solvent in the film at the end of step B is in the range of 15% by mass to 95% by mass. Production method. 6. The method has a step B of stretching the peeled cellulose ester film in the width direction after casting on a support, and the retardation in the film plane is R ₀ (nm),
When the retardation in the thickness direction is R _t (nm), in the method for producing a cellulose ester film having R _t / R ₀ of 0.8 to 3.5, the residual solvent amount of the film at the start of step B is 90. Mass% to 10 mass%, the temperature of the film is 30 ° C to 130 ° C, the film temperature at the end of step B is 60 ° C to 130 ° C, and
The residual solvent amount of the film at the end of the process B is B1%,
When the residual solvent amount of the film at the start is B0%, B
0% and B1% are 0.8 × B0 ≦ B1 ≦ 0.99 × B
A method for producing a cellulose ester film, which satisfies the relationship of 0. 7. The method for producing a cellulose ester film according to claim 6, wherein the poor solvent content (%) in the residual solvent in the film at the end of step B is 15% by mass to 95% by mass. . 8. The method has a step B of stretching the peeled cellulose ester film in the width direction after casting on a support, and the retardation in the film plane is R ₀ (nm),
When the retardation in the thickness direction is R _t (nm), in the method for producing a cellulose ester film having R _t / R ₀ of 0.8 to 3.5, the film atmosphere temperature in step B is 110 ° C. to 140 ° C. And the residual solvent amount of the film at the end of step B is B3%, and the residual solvent amount of the film at the start of step B is B2%, B3%
And B2% satisfy the relationship of 0.4 × B2 ≦ B3 ≦ 0.8 × B2. 9. The method for producing a cellulose ester film according to claim 8, wherein the poor solvent content (%) in the residual solvent in the film at the end of step B is 15% by mass to 95% by mass. . 10. Cellulose peeled after casting on a support
Step B of stretching the ester ester film in the width direction
Has a retardation in the film plane of R ₀(N
m), the retardation in the thickness direction is R_t(Nm)
When the R_t/ R₀Of 0.8 to 3.5
In the method for producing a steal film, the film of step B
The ambient temperature is in the range of 30 ° C to 130 ° C, and
At the end of step B, the residual solvent amount of the film is set to B1%, step B
When the residual solvent amount of the film at the start was set to B0%,
B1% and B0% are 0.8 × B0 ≦ B1 ≦ 0.9.
Cellulose E characterized by satisfying the relationship of 9 × B0
Manufacturing method of steal film. 11. The poor solvent content (%) in the residual solvent in the film in step B is 15% by mass to 95% by mass.
The method for producing a cellulose ester film according to claim 10, wherein 12. The stretching speed represented by the following general formula (3) in the width direction of the film in step B is 50% /
It is min-500% / min, The manufacturing method of the cellulose-ester film of any one of Claims 1-11 characterized by the above-mentioned. General formula (3) Stretching speed (% / min) = {(width dimension after stretching / width dimension before stretching) -1} × 100 (%) / time required for stretching (min) 13. After casting on a support, the method comprises a step A of gripping the peeled cellulose ester film, a step B of stretching the film in the width direction, and a grip relaxation step C, and the retardation in the plane of the film is R _0. (Nm) and the retardation in the thickness direction is R _t (nm), R _t / R ₀ is 0.
In the method for producing a cellulose ester film of 8 to 3.5, the good solvent concentration of the atmosphere in steps A and B is 2000 pp.
A method for producing a cellulose ester film, which is m or more and less than a saturated vapor amount. 14. Cellulose that has been peeled off after casting on a support.
Step B of stretching the ester ester film in the width direction
Has a retardation in the film plane of R ₀(N
m), the retardation in the thickness direction is R_t(Nm)
When the R_t/ R₀Of 0.8 to 3.5
In the manufacturing method of the steal film, In step B, the film stretching ratio in the width direction is 1.1 to 2.5.
Cellulose ester powder characterized in that
Rum manufacturing method. 15. A step B of stretching the peeled cellulose ester film in the width direction after casting on a support.
After the grip relaxation step C, there is a step D1 of further drying,
When the retardation in the film plane is R ₀ (nm) and the retardation in the thickness direction is R _t (nm), R _{t is}
In the method for producing a cellulose ester film in which / R ₀ is 0.8 to 3.5, DB <D <D when the film elastic moduli in the longitudinal direction at the end of step B and at the start of step D1 are DB and DD1, respectively.
A method for producing a cellulose ester film, which comprises drying under the condition of D1. 16. Cellulose peeled off after casting on a support
Step B of stretching the ester ester film in the width direction
Has a retardation in the film plane of R ₀(N
m), the retardation in the thickness direction is R_t(Nm)
When the R_t/ R₀Of 0.8 to 3.5
In the manufacturing method of the steal film, Cut off the edge of the film with a slitter before starting process B
Production of cellulose ester film characterized by
Method. 17. After casting on a support, the method has a step A of gripping the peeled cellulose ester film in the width direction, a step B of stretching, and a step C of relaxing the grip, and the retardation in the plane of the film is R. _{In the} method for producing a cellulose ester film having R _t / R ₀ of 0.8 to 3.5, where ₀ (nm) and the retardation in the thickness direction are R _t (nm), steps A, B, and C are performed. A method for producing a cellulose ester film, which comprises providing a neutral zone therebetween. 18. A method for producing a cellulose ester film, which comprises a step A of gripping a peeled cellulose ester film in a width direction after casting on a support, a step B of stretching, and a step C of relaxing gripping. , B, and C have a neutral zone, The manufacturing method of the cellulose-ester film of any one of Claims 1-16 characterized by the above-mentioned. 19. After being cast on a support, the peeled cellulose ester film is stretched in the width direction, the retardation in the film plane is R ₀ (nm), and the retardation in the thickness direction is R _t (nm). In the method for producing a cellulose ester film having R _t / R ₀ of 0.8 to 3.5, the tear strength in the width direction and the tear strength in the longitudinal direction are Htd and Hmd, respectively. / Hmd is 0.
A method for producing a cellulose ester film, which comprises adjusting to 62 to 1.0. 20. After casting on a support, the peeled cellulose ester film is stretched in the width direction, the retardation in the film plane is R ₀ (nm), and the retardation in the thickness direction is R _t (nm). In the method for producing a cellulose ester film having R _t / R ₀ of 0.8 to 3.5, the dimensional change rate in the width direction before and after the treatment at 60 ° C. and 90% RH for 24 hours and the longitudinal direction. Dimensional change rate of Std%,
Std is in the range of −0.4 to 0.4% when Smd% is set, and Smd is adjusted to −0.4 to 0.4%. 21. After being cast on a support, the peeled cellulose ester film is stretched in the width direction, the retardation in the film plane is R ₀ (nm), and the retardation in the thickness direction is R _t (nm). In the method for producing a cellulose ester film having R _t / R ₀ of 0.8 to 3.5, the plasticizer content during casting is G1, and the plasticizer content after D1 is G2. At this time, G2 / G1 is adjusted to 0.9-1.0, The manufacturing method of the cellulose ester film characterized by the above-mentioned. 22. After casting on a support, the peeled cellulose ester film is stretched in the width direction, the retardation in the film plane is R ₀ (nm), and the retardation in the thickness direction is R _t (nm). In the method for producing a cellulose ester film having R _t / R ₀ of 0.8 to 3.5, the maximum value, the minimum value and the average value of the film thickness in the width direction are respectively Rmax, Rmin, A method for producing a cellulose ester film, characterized in that when Rave is used, the film thickness distribution represented by the following general formula (4) is adjusted to 0 to 8%. General formula (4) R (%) = (R (max) -R (min)) / R (av
e) × 100 (wherein R (max): maximum film thickness, R (min): minimum film thickness, R (ave): average film thickness. ] 23. After being cast on a support, the peeled cellulose ester film is stretched in the width direction, the retardation in the film plane is R ₀ (nm), and the retardation in the thickness direction is R _t (nm). In the method for producing a cellulose ester film having R _t / R ₀ of 0.8 to 3.5, the orientation angle distribution should be adjusted to 90 ± 1 degrees with respect to the casting direction (longitudinal direction). A method for producing a cellulose ester film, which comprises: 24. After casting on a support, the peeled cellulose ester film is stretched in the width direction, the retardation in the film plane is R ₀ (nm), and the retardation in the thickness direction is R _t (nm). In the method for producing a cellulose ester film having R _t / R ₀ of 0.8 to 3.5, it is necessary to adjust the retardation (R ₀ ) distribution in the in-plane direction of the film to 5% or less. A method for producing a characteristic cellulose ester film. 25. After being cast on a support, the peeled cellulose ester film is stretched in the width direction, the retardation in the film plane is R ₀ (nm), and the retardation in the thickness direction is R _t (nm). In the method for producing a cellulose ester film having R _t / R ₀ of 0.8 to 3.5, the retardation (R _t ) distribution in the thickness direction of the film is adjusted to 10% or less. And a method for producing a cellulose ester film. 26. A method for producing a cellulose ester film, which comprises casting the peeled cellulose ester film in the width direction after casting on a support, and setting the haze value to 0.
It adjusts to 2%, The manufacturing method of the cellulose-ester film of any one of Claims 1-25 characterized by the above-mentioned. 27. The cellulose acylate film having a total acyl group substitution degree of 2.3 to 2.85 and an acetyl group substitution degree of 1.4 to 2.85. The method for producing a cellulose ester film according to any one of 1. 28. A cellulose ester film manufactured by using the method for manufacturing a cellulose ester film according to claim 1. 29. A retardation film comprising the cellulose ester film according to claim 28. 30. An optical compensatory sheet having an optically anisotropic layer on the cellulose ester film according to claim 28. 31. An optical anisotropy on the surface side of the cellulose ester film produced by the method for producing a cellulose ester film according to claim 1, which is in contact with the support during casting. An optical compensation sheet having a layer. 32. An elliptically polarizing plate comprising the cellulose ester film according to claim 28. 33. A display device comprising the elliptically polarizing plate according to claim 32. 34. The peeled cellulose ester film after casting on a support has tear strengths in the width and longitudinal directions with respect to the casting direction of Htd and Hm, respectively.
When defined as d, Htd / Hmd is in a range of 0.62 to 1.0, which is a cellulose ester film. 35. A cellulose ester film which has been peeled off after casting on a support has Nx, Ny and N as refractive indexes in the width direction, longitudinal direction and film thickness direction, respectively, with respect to the casting direction.
The cellulose ester film according to claim 34, wherein Nx>Ny> Nz when z is set. 36. The retardation in the film plane is R
₀ (nm), and the retardation value in the thickness direction is R _t (n
The cellulose ester film according to claim 34 or 35, wherein R _t / R ₀ is in the range of _0.8 to 3.5 when m). 37. The total acyl group substitution degree of cellulose ester is in the range of 2.3 to 2.85, and the acetyl group substitution degree is in the range of 1.4 to 2.85. The cellulose ester film according to any one of 34 to 36. 38. The orientation angle distribution is 90 in the longitudinal direction.
It is within the range of ± 1 degree.
7. The cellulose ester film according to any one of 7. 39. A maximum value and a minimum value of the film thickness in the width direction,
The cellulose ester film according to any one of claims 34 to 38, wherein (Rmax-Rmin) / Rave is in the range of 0 to 8% when the average values are Rmax, Rmin, and Rave, respectively. . 40. In-plane retardation (R
₀ ) The distribution is 5% or less.
The cellulose ester film according to any one of 4 to 39. 41. The cellulose ester film according to claim 34, wherein the retardation (R _t ) distribution in the film thickness direction is 10% or less. 42. A cellulose ester film which has been peeled off after being cast on a support is treated at 60 ° C. and 90% RH for 24 hours, and then the dimensional change rate in the width direction relative to the casting direction and the longitudinal direction. The dimensional change rate is Std%,
When Smd%, Std is −0.4% to 0.4%, and Smd is −0.4% to 0.4%. 43. Nx, Ny, and Nz, where Nx is the refractive index in the width direction, Nx is the refractive index in the film thickness direction, and Nz is the refractive index in the film thickness direction with respect to the casting direction.
The cellulose ester film according to claim 42, wherein>Ny> Nz. 44. The retardation in the film plane is R
₀ (nm), and the retardation value in the thickness direction is R _t (n
The cellulose ester film according to claim 42 or 43, wherein R _t / R ₀ is in the range of _0.8 to 3.5 when m). 45. The total degree of substitution of cellulose ester is 2.
It is in the range of 3 to 2.85, and the substitution degree of the acetyl group is 1.
43. The range of 4 to 2.85.
The cellulose ester film according to any one of to 44. 46. The orientation angle distribution is 90 ± with respect to the longitudinal direction.
46. It is within the range of 1 degree.
The cellulose ester film according to any one of 1. 47. A retardation film comprising the cellulose ester film according to any one of claims 34 to 46. 48. An optical compensatory sheet having an optically anisotropic layer on the cellulose ester film according to claim 34. 49. An elliptically polarizing plate comprising the cellulose ester film according to any one of claims 34 to 46. 50. A display device comprising the elliptically polarizing plate according to claim 49.