WO2008068961A1

WO2008068961A1 - Optical film and polarizer and liquid-crystal display each employing the same

Info

Publication number: WO2008068961A1
Application number: PCT/JP2007/070131
Authority: WO
Inventors: Takatugu Suzuki; Takayuki Suzuki; Satomi Kawabe
Original assignee: Konica Minolta Opto, Inc.
Priority date: 2006-12-05
Filing date: 2007-10-16
Publication date: 2008-06-12
Also published as: JPWO2008068961A1; KR101314030B1; TW200846708A; KR20090095576A; JP5182098B2; TWI444668B

Abstract

An optical film which is free from film web deformation failures such as ridge failures and protrusion failures, has high flatness and high suitability for saponification, and is reduced in curling and retardation fluctuation; and a polarizer having satisfactory durability over long and a liquid-crystal display having a high contrast which both employ the optical film. The optical film is a film obtained by thermally melting a film-forming material comprising at least one plasticizer and a cellulose ester and forming the melt into a film by melt casting. It is characterized in that the cellulose ester used satisfies all of the following requirements (1) to (4) concerning the kinds of substituents and the degrees of substitution with these. Relationship (1) 1.25≤X≤1.43 Relationship (2) 1.15≤Y≤1.33 Relationship (3) 2.40≤X+Y<2.75 Relationship (4) -0.05≤X-Y<0.20 [X represents the degree of substitution with acetyl and Y represents the degree of substitution with propionyl.]

Description

Specification

Optical film, and polarizing plate and liquid crystal display device using the same

Technical field

[0001] The present invention relates to an optical film having a cellulose ester formed by a melt casting method, a polarizing plate using the same, and a liquid crystal display device.

Background art

An optical film having a cellulose ester (hereinafter also simply referred to as a cellulose ester film) is a photographic negative film because of its high transparency, low birefringence, and easy adhesion to a polarizer. As an optical film for protecting a polarizer used in a liquid crystal display device and a support used in a liquid crystal display device, it has been widely used in polarizing plates and the like. Other applications for liquid crystal display devices include various functional films such as retardation films, wide viewing angle films, antireflection films used in plasma displays, and various functional films used in organic EL displays. Etc. can also be used.

[0003] The production volume of liquid crystal display devices has greatly increased in recent years due to the thinness and lightness of the depth, and the demand is increasing. In addition, televisions using liquid crystal display devices are characterized by being thin and light, and large-scale television sets that have not been achieved with televisions using cathode ray tubes have been produced. Demand for constituent polarizers and polarizing plate protection films is increasing! As a polarizing plate protective film, a cellulose ester film is generally used because of its excellent optical properties!

[0004] Until now, these cellulose ester films have been produced exclusively by the solution casting method. The solution casting method is a film-forming method in which a solution obtained by dissolving a cellulose ester in a solvent is cast to obtain a film shape, and then the solvent is evaporated and dried to obtain a film. Since a film formed by the solution casting method has high flatness, a high-quality liquid crystal display device without unevenness can be obtained using this film.

[0005] The force and shim solution casting method requires a large amount of an organic solvent, and has a large environmental load. Cellulose ester films are formed using halogen-based solvents that have a large environmental impact because of their dissolution characteristics, and therefore reductions in the amount of solvent used are particularly required. Therefore, it has become difficult to increase the production of cellulose ester films by solution casting. For this reason, a film forming method that does not use an organic solvent, for example, a film forming method by heat melting is desired.

[0006] On the other hand, as a cellulose esterenorefinoleum used as a protective film used for a polarizing plate of a liquid crystal display device, conventional senorelose triacetate phenol is often used. In general, a polarizing plate has a structure in which both sides of a polarizing film made of polybulu alcohol alcohol or the like with iodine or dye adsorbed and oriented are laminated with a transparent resin layer, and the cellulose triacetate film is transparent. It has been often used as a flexible resin layer. However, when trying to apply cell mouth triacetate, which is commonly used in solution casting film formation, to melt film formation, cellulose triacetate has a melting start temperature higher than the decomposition start temperature. ! /, Because it is a cellulose ester, it is difficult to use for melt film formation.

[0007] In recent years, by replacing the cellulose ester not only with a acetyl group but also with a specific proportion of a propionyl group or a propylyl group, for silver salt photography (for example, see Patent Document 1) or for a polarizing plate protective film ( For example, as described in Patent Documents 2 and 3, an attempt is made to melt film-form such a cellulose ester. A high substitution degree of propionyl group or butyryl group is advantageous for melt film formation because the viscosity at the time of melting is small, but on the other hand, the mechanical strength as a film after film formation is inferior, for silver salt photography, It has been found that there is a problem that the polarizing plate protective film does not function. On the other hand, if the substitution degree of propionyl group or butyryl group is low, the mechanical strength increases. On the other hand, the viscosity at the time of melting increases, and it is difficult to level even if it is extruded from a die and cast on a cooling drum or cooling belt. The shape unevenness and the pressure unevenness are likely to occur. As a result, there are problems such as inferior flatness and curl properties, which are physical properties of the obtained film, and further, there is a large variation in retardation of the optical properties! /, Turned out to be.

[0008] It is known to add a specific deterioration inhibitor when melt-forming a cellulose ester (see, for example, Patent Document 4). It is well known to prevent deterioration of chemical properties (coloring and molecular weight) of high molecular weight materials by adding deterioration inhibitors. Reversely, the combination of polymer materials and deterioration inhibitors is not appropriate. Effect, ie polymer The problem is that the material is deteriorated instead. By the way, although there is no degradation of chemical properties, it may degrade optical properties. In such a case, when cellulose ester is used for optical applications, it is fatal, and it is a problem to select an appropriate degradation inhibitor suitable for the polymer material. On the other hand, not only the stability at the time of melt film formation, but also the stability after melt film formation is important for the cellulose ester formed by melt film formation. In other words, it is important that there is no problem during the period of assembling any product using cell mouth ester, the period during which the product is delivered to consumers, and is being used. In the conventionally known technology, there is a problem in achieving both long-term stability during melt film formation and after melt film formation, and it has been desired to construct a more advanced stabilization technique.

[0009] By the way, when a polarizing plate is produced by laminating a protective film and a polarizer, the triacetyl cellulose film is immersed in a high-temperature, high-concentration alkaline solution in order to make it easy to apply a water-soluble adhesive. Then, a so-called saponification treatment is performed to make the film surface hydrophilic, apply a force adhesive, and bond it to a polarizer.

[0010] Because of the easy adhesion to the polarizer, the transparent resin film for the protective film for polarizing plate has been exclusively used with triacetyl cellulose. One of the reasons why it is still not replaced with other films is a polyester film. However, other polymer films such as polycarbonate film or cyclic polyolefin resin film did not have easy adhesion to the polarizer even after saponification treatment.

[0011] Attempts have been made to improve various performances of cellulose ester films by defining the degree of substitution of fatty acids such as the acyl groups of cellulose esters, such as acetyl groups, propionyl groups, or butyryl groups. (For example, see Patent Document 5). A cellulose ester film substituted with a specific proportion of propionyl group or butyryl group in addition to such a acetyl group is more adhesive than polymer films other than cellulose ester, but the degree of substitution of propionyl group or butyryl group Is too high, the saponification process proceeds, and as a result, it has been found that there is a problem that the adhesiveness is inferior, and that mechanical properties and optical properties are also insufficient. . In particular, when propionyl and butyryl groups are compared, the mechanical and optical properties can be greatly degraded by the bonding of petityl groups despite the difference in carbon number. found.

[0012] Therefore, instead of the triacetylcellulose film formed by the solution casting method, it has excellent environmental suitability, flatness, high curability for saponification treatment, and small variation in retardation. Is waiting for the emergence of melt-formed optical films with good durability over a long period of time.

By the way, these cellulose ester films are usually wound around a winding core to form a film raw material, which is stored and transported. For this reason, if the film that has been melt-formed is stored for a long time in the state of the film roll wound on the core, the horse's spine failure or the core portion of the film roll may have a failure called core transfer or when winding starts. It has been found that there is a problem that the film tends to be wrinkled.

[0014] A horse's back failure is a failure in which the original film is deformed into a U-shape like a horse's back, and a belt-like convex part is formed at a pitch of about 2 to 3 cm near the center. Therefore, when processed into a polarizing plate, the surface appears distorted, which is a problem. Until now, horse back failure has been reduced by lowering the coefficient of dynamic friction between the bases and adjusting the height of the knurling on both sides.

[0015] Further, the core transfer is a failure due to film deformation caused by unevenness of the core or film.

[0016] The force that does not cause these problems to become a major problem in films produced by conventional solution casting. A film produced by melt film formation is a major problem because the flatness of the film is low. I got it.

[0017] In particular, with the recent increase in size of screens, it is desired to increase the width of the film and increase the winding length. For this reason, the original film becomes wider and the original film load tends to increase, and these faults are more likely to occur, so improvement is desired. Patent Document 1: Japanese Patent Publication No. 6-501040

Patent Document 2: Japanese Patent Laid-Open No. 2000-352620

Patent Document 3: Japanese Patent Laid-Open No. 2006-111796

Patent Document 4: Japanese Patent Laid-Open No. 2006-241428

Patent Document 5: Japanese Unexamined Patent Publication No. 2006-111842

Disclosure of the invention Problems to be solved by the invention

[0018] The present invention has been made in view of the above problems, and the object of the present invention is to form a melt film having excellent environmental suitability, good mechanical properties, optical properties, and good durability. Optical film, more specifically, optical film that does not cause deformation deformation of the film, such as horse back failure or convex failure, flatness, high saponification suitability, curl property, and variation in retardation It is an object of the present invention to provide a small optical film, a polarizing plate having excellent durability over a long period of time using the optical film, and a liquid crystal display device in which high contrast is achieved. Means for solving the problem

[0019] As a result of intensive investigations for solving the above-mentioned problems, the present inventors have found that all the problems are solved by using a film formed by melting a cellulose ester having a specific kind and amount of a specific substituent. The inventors have found that it can be solved and have completed the present invention.

That is, the above-described problem of the present invention is achieved by the following configuration.

[0021] 1. In an optical film obtained by heating and melting a film-forming material containing at least one plasticizer and a cellulose ester to form a film by a melt casting method, the types of substituents of the cellulose ester and the degree of substitution thereof An optical film formed by using a cell mouth ester that simultaneously satisfies the following formulas (1) to (4).

[0022] Equation (1) 1. 25≤X≤1.43

Formula (2) 1. 15≤Y≤1. 33

Equation (3) 2. 40≤Χ + Υ <2. 75

Formula (4) -0. 05≤Χ-Υ <0. 20

[In the formula, X represents the degree of substitution with a acetyl group, and Υ represents the degree of substitution with a propionyl group. ]

2. 1% mass loss temperature Td (l. 0) of the cellulose ester in air is 27

2. The optical film as described in 1 above, which is 0 ° C. or higher.

[0023] 3. The optical film as described in 1 or 2 above, wherein the film-forming material further contains at least one phenol-based compound.

[0024] 4. The optical film described in any one of the above !! to 3, characterized in that the film-forming material further contains at least one phosphorous compound. 5. The optical film as described in any one of 1 to 4, wherein the film-forming material further contains at least one alkyl radical scavenger.

6. The film forming material further comprises at least one phenol compound, at least one phosphorous compound, and at least one alkyl radical scavenger. Optical film.

7. The optical film as described in any one of 3 to 6 above, wherein the phenolic compound is a hindered phenolic compound.

8. The optical film as described in any one of 4 to 7 above, wherein the phosphorus compound is a phosphonite compound.

9. In any one of 5 to 8 above, wherein the alkyl radical scavenger is a compound represented by the following general formula (1) or a compound represented by the following general formula (2): The optical film as described.

[0025] [Chemical 1]

[In the formula, R represents a hydrogen atom or an alkyl group having 1 to 10 carbon atoms;

1 2 3 each independently represents an alkyl group having! To 8 carbon atoms. ]

[0027] [Chemical 2]

'Killing ceremony {2}

[Wherein, R 1 to R each independently represent a hydrogen atom or a substituent, and R represents water.

12 15 16 represents a primary atom or a substituent, and n represents an integer of 1 to 4. When n is 1, R is a substituent

11 and when n is an integer from 2 to 4, R is 2

Represents an 11 to 4 valent linking group. ]

10. The optical film as described in any one of 1 to 9 above, wherein the plasticizer is a polyhydric alcohol ester.

11. The optical film as described in any one of 1 to 10 above, wherein the film-forming material further contains a benzotriazole compound.

12. A polarizing plate comprising the optical film according to 1 to 11 above! /, Displacement force, and at least one surface of a polarizer.

13. A liquid crystal display device using the polarizing plate described in 12 above on at least one surface of a liquid crystal cell.

The invention's effect

[0029] According to the present invention, an optical film that does not cause deformation failure of the original film, such as a horse back failure or a convex failure, an optical film that has high flatness and suitability for saponification treatment, and that has little variation in curling properties and retardation. A polarizing plate having excellent durability over a long period of time using the optical film and a liquid crystal display device having high contrast can be provided.

[0030] FIG. 1 is a schematic flow sheet showing one embodiment of an apparatus for carrying out a method for producing a cellulose ester film according to the present invention.

FIG. 2 is an enlarged flow sheet of a main part of the manufacturing apparatus of FIG.

[FIG. 3] FIG. 3 (a) is an external view of the main part of the casting die, and FIG. 3 (b) is a sectional view of the main part of the casting die.

Yes

FIG. 4 is a cross-sectional view of the first embodiment of the pinching rotator.

FIG. 5 is a cross-sectional view taken along a plane perpendicular to the rotation axis of the second embodiment of the pinching rotator.

FIG. 6 is a cross-sectional view in a plane including a rotation axis of a second embodiment of the pinching rotator.

FIG. 7 is an exploded perspective view schematically showing a configuration diagram of a liquid crystal display device.

FIG. 8 is a view showing a state of storage of a cellulose ester film original fabric. Extruder

filter

Static mixer

Casting die

Rotating support (first cooling roll) Clamping rotating body (touch roll) Rotating support (second cooling roll) Rotating support (third cooling roll) 11, 13, 14, 15 Transport roll 0 Inolem stretching machine

6 Winding device

1a, 21b Protective film

2a, 22b Phase difference film 3a, 23b Film slow axis direction 4a, 24b Polarizer transmission axis direction 5a, 25b Polarizer

6a, 26b Polarizer

7 LCD cell

9 Liquid crystal display

1 Die body

2 Slit

1 Metal sleeve

2 Elastic roller

3 Metal inner cylinder

Rubber

5 Cooling water

1 outer cylinder 52 inner cylinder

53 space

54 Coolant

55a, 55b Rotating shaft

56a, 56b Flange support flange

60 Fluid shaft cylinder

61a, 61b Inner cylinder support flange

62a, 62b Intermediate passage

110 Core body

117 Support plate

118 frame

120 Cellulose ester film

BEST MODE FOR CARRYING OUT THE INVENTION

[0032] The best mode for carrying out the present invention will be described in detail below, but the present invention is not limited thereto.

[0033] The present invention provides an optical film having good mechanical and optical properties and good durability. By using such an optical film, it is possible to obtain a high-quality optical film such as a protective film for a polarizing plate, an antireflection film, a retardation film, and a liquid crystal display device having a high display quality. I can do it.

[0034] The present invention is characterized in that a cellulose ester film formed by melt casting is used as an optical film. In the present invention, without dissolving the film-forming material in a solvent as in the case of solution casting, the film-forming material is heated to become a flowable state, and casting is defined as a melt casting method. .

[0035] The molding method for heating and melting can be further classified into a melt extrusion molding method, a press molding method, an inflation method, an injection molding method, a blow molding method, a stretch molding method, and the like. Among these, in order to obtain an optical film excellent in mechanical strength and surface accuracy, the melt extrusion method is excellent.

[0036] Here, the film-forming material is heated to develop its fluidity, and then on the drum or A method of extrusion film formation on an endless belt is included in the melt casting method of the present invention as a melt casting film forming method.

[0037] The optical film of the present invention is obtained by melting a film-forming material containing at least one plasticizer and the following cellulose ester, preferably at a melting temperature of 200 ° C or higher and 270 ° C or lower. It is an optical film formed by a casting method.

[0038] Hereinafter, each film forming material will be described.

[0039] <Cellulose ester>

The cellulose ester used in the melt casting method of the present invention is a cellulose ester that simultaneously satisfies the following formulas (1) to (4) when the substitution degree of the acetyl group is X and the substitution degree of the propionyl group is Y. Such cellulose esters are usually referred to as cellulose acetate propionate. Note that satisfying any one, any two, or any three of the following formulas does not solve all of the above issues, but it is important to satisfy all four at the same time. is there.

[0040] Equation (1) 1. 25≤X≤1.43

Formula (2) 1. 15≤Y≤1. 33

Equation (3) 2. 40≤Χ + Υ <2. 75

Formula (4) -0. 05≤Χ-Υ <0. 20

In particular, for equation (1) it is preferable to set 1 · 30≤Χ≤1.42. For equation (2), 1. 18≤Υ≤1.32 For Equation (3), it is preferable to set 2.50≤Χ + Υ≤2.73. For Equation (4), 0 · 01≤Χ-Υ≤0.18 preferable.

[0041] Next, the degree of substitution of the acyl group (acetyl group and propionyl group) of the cellulose ester used in the present invention will be described in detail.

[0042] Cellulose has a total of three hydroxyl groups, one at the 2nd, 3rd and 6th positions of 1 glucose unit. The total degree of substitution is the number of acyl groups per 1 glucose unit on average. It is a numerical value that indicates whether they are combined. Therefore, the maximum degree of substitution is 3.00, and the portion not substituted with the acyl group is usually present as a hydroxyl group. In addition, the 2nd and 3rd positions are secondary hydroxyl groups, and the 6th position is the primary hydroxyl group. The higher-order structure of the cellulose ester depends on which position of the acetyl group and propionyl group is substituted at which ratio. Physical properties May vary slightly. However, in the optical film of the present invention, each of the substitution position and the ratio power of the acetylenol group and the propionyl group is a cellulose that simultaneously satisfies the conditions of the above formulas (1) to (4). If it is an ester, it can be preferably used. The degree of substitution between the acetyl group and the propionyl group was determined by the method prescribed in ASTM D817-96.

[0043] The cellulose ester used in the present invention preferably has a number average molecular weight (Mn) of 50000 to 150,000, preferably 55000 to 12000, and more preferably 6000 to 100,000. Most preferably, it has a number average molecular weight of

Furthermore, the cellulose ester used in the present invention preferably has a weight average molecular weight (Mw) / number average molecular weight (Mn) ratio of 1.3 to 5.5, particularly preferably 1.5. The cellulose ester is preferably from 5.0 to 3.5, more preferably from 1.7 to 4.0, and even more preferably from 2.0 to 3.5.

[0045] Mn and Mw / Mn are as follows, and gel permeation chromatography.

(GPC).

[0046] The measurement conditions are as follows.

[0047] Solvent: Tetohydrofuran

Equipment: HLC-8220 (manufactured by Tosoh Corporation)

Column: TSKgel SuperHM—M (manufactured by Tosohichi Corporation)

Column temperature: 40 ° C

Sample concentration: 0.1% by mass

Injection volume: 10 1

Direct flow: 0.6 ml / min

Calibration curve: Standard polystyrene: PS-1 (manufactured by Polymer Laboratories) Mw = 2, 5 60,000 to 580.

[0048] By setting the cellulose ester in the film-forming material in the range of 70% by mass to 99% by mass, an excellent melt flow can be obtained in the presence of additives such as a deterioration inhibitor, a plasticizer, and an ultraviolet absorber described later. It exhibits ductility and stability, and the resulting film can impart excellent performance as an optical film. When the content of cellulose ester is 70% by mass or less This is not preferable because the additive bleeds out or the mechanical strength of the film decreases. Further, when the amount of other additives required as an optical film is 1.0% by mass or less (the cellulose ester content is 99% or more), it is difficult to satisfy the required physical properties. More preferably, the cellulose ester content is 80 to 95% by mass.

[0049] The raw material cellulose of the cellulose ester used in the present invention may be wood pulp or cotton linter. The wood pulp may be softwood or hardwood, but softwood is more preferable. A cotton linter is preferably used from the viewpoint of peelability during film formation. Cellulose esters made from these can be mixed as appropriate, or can be used alone.

[0050] For example, the ratio of cellulose esters derived from cotton linter: cellulose esters derived from wood pulp (coniferous): cellulose esters derived from wood pulp (hardwood) is 100: 0: 0, 90: 10: 0, 85: 15: 0, 50 : 50: 0, 20: 80: 0, 10: 90: 0, 0: 100: 0, 0: 0: 100, 80:10:10, 85: 0: 15, 40:30:30 it can.

[0051] The cellulose ester of the present invention can be synthesized with reference to known methods.

For example, the hydroxyl group of the raw material cellulose can be acetylated and propionated by acetic anhydride and propionic anhydride by a conventional method to replace the acetyl group and propionyl group. The method for synthesizing such a cellulose ester is not particularly limited. For example, the cellulose ester can be synthesized with reference to the method described in JP-A-10-45804 or JP-A-6-501040. It should be noted that the amount of acetic anhydride and propionic anhydride to be used is appropriately changed to synthesize a cellulose ester that simultaneously satisfies the above formulas (1) to (4).

[0052] The alkaline earth metal content of the cellulose ester used in the present invention is preferably in the range of! If it exceeds 50 ppm, lip adhesion stains will increase or breakage will easily occur at the slitting part during or after hot drawing. Even if it is less than lppm, it breaks easily, but the reason is not well understood. Furthermore, the range of 1-30 ppm is preferable. The alkaline earth metal as used herein refers to the total content of Ca and Mg, and can be measured using an X-ray photoelectron spectrometer (XPS).

[0053] The residual sulfuric acid content in the cellulose ester used in the present invention is preferably in the range of 0.;! To 45 ppm in terms of elemental sulfur. These are thought to contain in the form of salt It is. If the residual sulfuric acid content exceeds 45 ppm, the deposit on the die lip during heat melting increases, which is not preferable. Further, it is not preferable because it easily breaks during hot stretching or slitting after hot stretching. Less is preferable, but if it is less than 0.1, it tends to break on the contrary, it is not preferable, but the reason is not well understood. Furthermore, the range of 1-30 ppm is preferable. Residual sulfuric acid content is measured by the force S measured by the method specified in ASTM D817-96.

[0054] The free acid content in the cellulose ester used in the present invention is preferably! -500 ppm. If it exceeds 500ppm, the deposit on the die lip will increase and breakage will easily occur. Further, it is preferably in the range of 1 to 100 ppm, and it is more difficult to break. The range of! -70 ppm is particularly preferable. The free acid content should be measured by the method specified in ASTM D817-96.

[0055] By washing the synthesized cellulose ester more thoroughly than when used in the solution casting method, the residual alkaline earth metal content, the residual sulfuric acid content, and the residual acid content Can be within the above range, which is preferable. For washing the cellulose ester, in addition to water, a poor solvent such as methanol or ethanol, or, as a result, a mixed solvent of a poor solvent and a good solvent can be used. , Low molecular organic impurities can be removed. Further, the cellulose ester is preferably washed in the presence of an anti-aging agent, which improves the heat resistance and film forming stability of the cellulose ester. The degradation inhibitor used is not limited as long as it is a compound that inactivates radicals generated in the cellulose ester or suppresses degradation of the cellulose ester caused by the addition of oxygen to the radical generated in the cellulose ester. be able to.

[0056] In order to improve the heat resistance, mechanical properties, optical properties, etc. of the cellulose ester, the cellulose ester is dissolved in a good solvent of cellulose ester, and then re-precipitated in a poor solvent and filtered. By stirring and suspending in the solution and filtering, low molecular weight components of cellulose ester and other impurities can be removed. At this time, it is preferable to carry out in the presence of a deterioration preventing agent as in the case of washing the cellulose ester described above!

[0057] The deterioration inhibitor used for washing the cellulose ester is cellulose ester after washing. You can remain in it. Residual amount (between 0.0;! And 2000 ppm, more preferably (between 0.05 and lOOOOppm. Further preferred <is 0 .;! And lOOppm.

[0058] Further, another polymer or a low molecular weight compound may be added after the re-precipitation treatment of the cellulose ester.

[0059] In addition, the cellulose ester used in the present invention preferably has few bright spot foreign matters when formed into a film. Bright spot foreign matter means that two polarizing plates are placed orthogonally (crossed Nicols), a cellulose ester film is placed between them, light from the light source is applied from one side, and the cellulose ester film is placed from the other side. This is the point where the light from the light source appears to leak when observed. The polarizing plate used for the evaluation at this time is preferably a glass plate used for protecting the polarizer, which is desirably composed of a protective film free from bright spot foreign matter. One of the causes of bright spot foreign substances is considered to be cellulose with unacetylated or low acetylated degree contained in cellulose esters. Use cellulose esters with few bright spot foreign substances (low dispersion of substitution degree! /, Cellulose ester And / or filtering the melted cellulose ester, or at least one of the process of late synthesis of cellulose ester and the process of obtaining precipitate It is also possible to remove bright spot foreign matter. Because the melted cellulose ester has a high viscosity! /, The latter method is more efficient! /.

[0060] The number of bright spot foreign materials per unit area decreases as the film thickness decreases, and the bright spot foreign materials tend to decrease as the cellulose ester content in the film decreases. The diameter of 0.01 mm or more is preferably 200 pieces / cm ² or less, more preferably 100 pieces / cm ² or less, more preferably 50 pieces / cm ² or less, more preferably 30 pieces or less. / cm ² but that it is more preferable even more preferably fixture 10 / cm ² or less is less, and most preferably none. In addition, it is preferable that the bright spot of 0.005-0.01mm or less is 200 pieces / cm ² or less, more preferably 100 pieces / cm ² or less, more preferably 50 pieces / cm ² or less. More preferably, the force is 30 pieces / cm ² or less, more preferably 10 pieces / cm ² or less, most preferably none.

[0061] When removing bright spot foreign matter by melt filtration, the cellulose ester is melted alone. It is preferable to filter the cellulose ester composition to which a deterioration inhibitor, a plasticizer, and the like are added and mixed, rather than filtering the soaked product, because the removal efficiency of bright spot foreign matter is high. Of course, it can be dissolved in a solvent during the synthesis of cellulose ester and reduced by filtration. A mixture of UV absorber and other additives as appropriate can be filtered. Filtration is preferably performed when the viscosity of the melt containing cellulose ester is less than lOOOOPa's, more preferably less than 5000 Pa's, more preferably less than lOOOPa's and less than 500 Pa's. Even more preferred. As the filter medium, conventionally known materials such as glass fibers, cellulose fibers, filter paper, and fluorine resins such as tetrafluoroethylene resin are preferably used, particularly ceramics, metals and the like are preferably used. The absolute filtration accuracy is preferably 50 in or less, more preferably 30 m or less, more preferably 10 m or less, and even more preferably 5 in or less. These can be used in appropriate combination. The filter medium can be either a surface type or a depth type, but the depth type is preferably used because it is relatively clogged.

[0062] In another embodiment, a cellulose ester obtained by dissolving the raw material cellulose ester at least once in a solvent and then drying the solvent may be used. In that case, cellulose ester that has been dissolved in a solvent together with at least one of a deterioration inhibitor, a plasticizer, an ultraviolet absorber, and a matting agent and then dried is used. As the solvent, a good solvent used in a solution casting method such as methylene chloride, methyl acetate, or dioxolane can be used, and a poor solvent such as methanol, ethanol, or butanol may be used at the same time. In the course of dissolution, it may be cooled to 20 ° C or lower or heated to 80 ° C or higher. When such a cellulose ester is used, it may be possible to uniformly block each additive when melted and make the optical properties uniform.

[0063] The optical film of the present invention may be appropriately mixed with polymer components other than cellulose ester! /. The polymer component to be mixed preferably has excellent compatibility with the cellulose ester, and the transmittance when it is made into a film is preferably 80% or more, more preferably 90% or more, and further preferably 92% or more. .

[0064] Since the cellulose ester of the present invention is used for melt film formation, the cellulose ester itself needs to be stable until it reaches heat-melting power film formation. In addition to the stability at the time of melt film formation, the cellulose ester film after melt film formation has a mechanical property, optical characteristics, and durability of 1% It was found that there is a relationship with the mass decrease temperature Td (l. 0). It should be noted that as long as the cell mouth sester satisfying the above formulas (1) to (4) according to the present invention is used, the force S, Td (l. 0) The higher Td (l. 0), which is preferable for solving the problem, is more preferably 270 ° C or higher, more preferably 280 ° C or higher, and most preferably 290 ° C or higher. In order to increase the Td (l. 0) of the cellulose ester, in the synthesis of the cellulose ester, in the operation of filtering and washing the cellulose ester at the time of the last removal, it is necessary to use enough water until the pH of the washing solution becomes neutral. Improve the power by washing. By the way, although the detailed reason is not well understood, depending on the type of the cellulose ester, there are some cases where mechanical properties such as being easily broken are deteriorated when washing is performed excessively. For cellulose esters that simultaneously satisfy the formulas (1) to (4), it has been found that the mechanical properties are not deteriorated by washing. Note that the 1% mass loss temperature Td (l. 0) under air is a force S that can be measured with a commercially available differential thermogravimetric analysis (TG-DTA) device, although cellulose ester is generally a small amount. Because it contains water, care must be taken during measurement. Specifically, hold the sample at 100 ° C for a while, confirm that the mass loss due to the volatilization of water has disappeared, and then measure the mass loss accompanying the temperature rise from that point. By the way, in consideration of avoiding an increase in the burden of the cellulose ester washing process, it is estimated that a higher upper limit is preferable for Td (l. 0). It is about 310 ° C.

[0065] The cellulose ester of the present invention has the ability to further improve the stability during heating by the combination with the deterioration inhibitor, and surprisingly, the combination with the deterioration inhibitor described below, Deformation failure of the original film such as failure or convex failure does not occur, flatness, suitability for saponification treatment, curlability, variability of retardation, and durability! It was found that an excellent cellulose ester film can be obtained.

Yes

[0066] << Deterioration preventive agent >> A degradation inhibitor is a material that suppresses the decomposition of polymers by heat, oxygen, moisture, acid, etc., by a chemical action. Since the optical film of the present invention is molded particularly at a high temperature of 200 ° C. or higher, it is a system in which the polymer is easily decomposed and deteriorated, and it is preferable to contain a deterioration inhibitor in the film-forming material.

[0067] Antioxidation of film-forming materials, capture of acid generated by decomposition, suppression or prohibition of decomposition reaction of radical species caused by light or heat, etc. Deterioration inhibitors are used to suppress the generation of volatile components due to alterations such as molecular weight reduction and decomposition of materials.

[0068] Examples of the degradation inhibitor include, but are not limited to, an antioxidant, a hindered amine light stabilizer, an acid scavenger, and a metal deactivator. These are described in JP-A-3-199201, JP-A-5-1907073, JP-A-5-194789, JP-A-5-271471, JP-A-6-107854 and the like. Among these, for the purpose of the present invention, it is preferable to contain an antioxidant as a deterioration preventing agent in the film forming material.

[0069] At least one or more kinds of deterioration preventing agents in the film-forming material used in the present invention can be selected, and the amount to be added is 0 with respect to the mass of the cellulose ester according to the present invention. More preferably, the content is from 0.1% by mass to 10% by mass, more preferably from 0.1% by mass to 5.0% by mass, and still more preferably from 0.2% by mass to 2.0% by mass.

[0070] If the addition amount of the deterioration inhibitor is larger than the above range, the transparency of the optical film may be lowered from the viewpoint of compatibility with the cellulose ester, and the finoleum may become brittle. Therefore, it is not preferable.

[0071] The film-forming material can be stored by dividing the material constituting the material into one kind or a plurality of kinds of pellets for the purpose of avoiding alteration of the material and hygroscopicity. Pelletization may improve the mixing or compatibility of the melt during heating, or may ensure optical uniformity of the resulting film.

[0072] When the film-forming material is heat-melted, and when the heat-melted material is used in a post-process, or when used as a product under the consumer, the above-described deterioration preventive agent is present. This is superior in terms of reducing the strength based on the degradation and decomposition of the material and the degradation of optical transparency, or maintaining the strength inherent to the material.

[0073] If the film-forming material is significantly deteriorated by heating, coloring may occur and it may become impossible to use as an optical film. In addition, when used as an optical compensation film for a liquid crystal display device, the force applied when the retardation applying step (stretching step) is performed after the casting step. May become brittle and may easily break during the stretching process, or the retardation value of the target optical compensation film may not be expressed. Furthermore, when used as a polarizing plate protective film for a liquid crystal display device, deterioration of the film-forming material is not preferable because it may interfere with bonding with a polarizer.

[0074] Therefore, the presence of the above-described deterioration preventing agent suppresses the generation of colored substances in the visible light region during heating and melting, or the material constituting the film during and after heating and melting. This is also preferable for optical films such as transmittance and haze value reduction caused by volatile components generated by the decomposition of benzene, and is excellent in that it can suppress or eliminate deterioration.

[0075] In the present invention, the display image of the liquid crystal display device is affected when the haze value exceeds 1% when the optical film of the present invention is used. Therefore, the haze value is preferably less than 1%, more preferably 0. Less than 5%. Further, yellowness (Yellow Index, YI) can be used as an index of colorability, preferably 3.0 or less, more preferably 1.0 or less. Yellowness can be measured according to JIS K7103.

[0076] In the above-described film forming material storage or film forming process, deterioration reactions due to oxygen or moisture in the air may occur simultaneously. In this case, in addition to stabilizing the above-described deterioration inhibitor, reducing the humidity and oxygen concentration in the air can be preferably used in combination for realizing the present invention. This includes the use of nitrogen or argon as an inert gas as a known technique, degassing operation under reduced pressure to vacuum, and operation in a sealed environment, and at least one of these three methods uses the above-mentioned stabilizer. Can be used in combination with the method of It is preferable to reduce the probability that the film-forming material comes into contact with oxygen in the air, so that deterioration of the material can be suppressed.

[0077] The optical film of the present invention is also used as a polarizing plate protective film. The presence of the above-described deterioration preventing agent in the film-forming material also plays an important role from the viewpoint of improving the storage stability with time of the polarizing plate and the polarizer constituting the polarizing plate.

[0078] In the liquid crystal display device using the polarizing plate of the present invention, when the above-described deterioration preventing agent is present in the optical film of the present invention, the temporal storage stability of the optical film is improved from the viewpoint of suppressing the above-mentioned deterioration and deterioration. In addition, it is excellent in that the optical compensation design can manifest its function over a long period of time in improving the display quality of liquid crystal display devices.

[0079] <Antioxidant>

Since cellulose ester is decomposed not only by heat but also by oxygen at a high temperature, the optical film of the present invention preferably contains an antioxidant as a deterioration preventing agent.

[0080] The antioxidant useful in the present invention is a force S that can be used without limitation as long as it is a compound that suppresses the deterioration of the film-forming material due to oxygen, and in particular, a phenol compound, a phosphorus compound, a thio compound. Alkyl radical scavengers, peroxide decomposers, oxygen scavengers, and the like. Of these, phenol compounds, phosphorus compounds, and alkyl radical scavengers are preferred, but it is more preferable to use a combination of the phenol compound and the phosphorus compound, the phenol compound, the phosphorus compound, and the alkyl. Most preferably, a triple combination of radical scavengers is used. By blending these compounds, it is possible to prevent coloring and strength reduction of the molded product due to heat and thermal oxidative degradation during melt molding without reducing transparency and heat resistance. Each of these compounds can be used alone or in combination of two or more, and the blending amount thereof is appropriately selected within a range not impairing the object of the present invention, but the mass of the cellulose ester according to the present invention. Is more preferably 0.01% by mass or more and 5.0% by mass or less, and still more preferably 0.2% by mass or more and 2.0% by mass. It is as follows.

[0081] (phenolic compound)

Phenolic compounds are known compounds and include alkyl group-substituted phenols such as para-t-butylphenol and para (1,1,3,3-tetramethylbutyl) phenol, for example, U.S. Pat. No. 4,839,405. Nos. 12 to 14; An enol derivative compound, a so-called hindered phenol compound, can be mentioned, and among these, a hindered phenol compound is preferable.

Specific examples of hindered phenolic compounds include: n-octadecyl 3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate, n-octadecyl-3 mono (3,5-di-tert-butyl-4-hydroxyphenyl) Acetate, n-octadecyl 3,5-di-tert-butyl-4-hydroxybenzoate, n-hexyl 3,5-di-tert-butyl 4-hydroxyphenyl benzoate, n-dodecyl 3,5-di-butynolate 4-hidroxif Enilbenzoate, neododecyl 3- (3,5-di-tert-butylenoyl 4-hydroxyphenenole) propionate, dodecinole / 3 (3,5-di-tert-butyl 4-hydroxyphenenole) propionate, ethinore α- (4-hydroxy 3, 5—Di-tert-butenoleveneol) isoptilate, octadecyl α- (4-hydroxy-3, 5— -T-butylphenyl) isobutyrate, octadecyl α- (4-hydroxy 3,5-di-butynolene 4-hydroxyphenyl) propionate, 2 -— (n-octylthio) ethyl 3,5-di-tert-butinole 4-hydroxymonobenzoate, 2 -— (n-octylthio) Ethyl 3,5-dibutyl 4-hydroxy monophenyl acetate, 2- (n octadecylthio) ethyl 3,5-dibutyl 4-hydroxyphenyl acetate, 2- (n octadecylthio) ethyl 3,5 di t -Butyl 4-hydroxy monobenzoate, 2— (2 hydroxyethylenolethio) ethenole 3,5—Gee butylinole 4-hydroxybenzoate, getinoreglycolone bisone (3,5 g tert-butyl 4-hydroxyphenol Nole) propionate, 2- (n-octadecylthio) ethyl 3 (3,5-di-tert-butyl-4-hydroxyphenyl) propionate, stearamide N, N bis- [ethylene 3- (3,5-di-tert-butynole 4-hydroxyphenyl) propionate], n-butylimino N , N Bis [ethylene 3— (3,5 di-tert-butyl-4-hydroxyphenenole) propionate], 2— (2 stealloy norekischinoretio) ethinore 3,5 G tert-butinole 4-hydroxybenzoate, 2 (2 stearoyloxychetylthio) ethyl 7- (3 methyl-5-tert-butyl-4-hydroxyphenyl) heptanoate, 1,2 propylene glycol bis [3- (3,5-diol t-butyl 4-hydroxyphenyl) propionate] , Ethylene glycol bis

[3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], neopen Tildaricol bis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], ethylene glycol bis (3,5-di-tert-butyl-4-hydroxyphenyl acetate), glycerin l- n o Kutadecanoate-2, 3 Bis (3, 5 di-tert-butyl 4-hydroxyphenylacetate), pentaerythritol-tetrakis [3— (3 ', 5'-zy tertinore 4 '-hydroxyphenol) Propionate], 3, 9-bis {2- [3- (3-tert-butyl-4-hydroxy-5-methylphenol) propionyl]] 1,1,1-dimethylethyl} -1,2,4,8,10 tetraoxaspiro [ 5.5] undecane, 1,1,1,1-trimethylolethane tris [3— (3,5-di-tert-butyl 4-hydroxyphenol) propionate], sorbitol hexer [3— (3, Five Di-tert-butylenoyl 4-hydroxyphenolate) propionate], 2-hydroxyethyl 7- (3 methyl-5-tert-butylphenol 4-hydroxyphenyl) propionate, 2 stearoyloxetyl 7- (3-methyl-5-tert-butyl 4 -Hydroxyphenol) heptanoate, 1, 6- n-hexanediol bis [(3 ', 5'-di-tert-butyl-4-hydroxyphenol) propionate], pentaerythritol-tetrakis (3,5-di-tert-butyl 4-) Hydroxyhydrocinnamate). The above type of phenolic compounds are commercially available, for example, from Ciba Specialty Chemicals under the trade names “IRGANOX1076” and “IRGANOX1010”.

(Phosphorus compounds)

Examples of phosphorus compounds useful in the present invention include phosphite compounds and phosphonate compounds. Specific examples of the phosphite compounds include triphenylphosphine urpheninole) phosphite, tris (dinouylfeninore) phosphite, tris (2,4 di-t-butylpheninole) phosphite, tris (2,4 di t-butyl-5-methylphenyl) phosphite, 10-(3,5 di-t-butyl 4-hydroxybenzyl) 9, 10 dihydro 9 oxa 10 phosphaphenanthrene 10 oxide, 6— [3— (3-t-butyl til 4 Hydroxy-1-5-methylphenol) propoxy] —2, 4, 8, 10 tetra-tert-butyldibenz [d, f] [l, 3, 2] dioxaphosphepine, tridecyl phosphite and other monophosphites Compound; 4, Α'-butylidene bis (3-methyl-6-t-butylphenol Diphosphite compounds such as 2,4'-isopropylidene monobis (phenyl-di-dialkyl (C12-C15) phosphite); and the like. The phosphite compounds of the above types are, for example, Sumitizer GP from Sumitomo Chemical Co., Ltd., ADK STAB PEP— 24G ”,“ ADK STAB PEP— 36 ”,“ ADK STAB 3010 ”,“ ADK ”from ADEKA Co., Ltd. Commercially available under the trade names STAB HP—10 ”and“ ADK STAB 21 1 2 ”.

Specific examples of the phosphonite compound include dimethyl-phenyl phosphonite, di-t-butyl-phenyl phosphonite, diphenylphenyl phosphonite, di (4 pentenoyl phenyl) monophenyl phosphonite, di ( 2-t butyl monophenyl) monophenyl phosphonite, G (2 methyl-3 pentyl roofenyl) phenyl phosphonite, Gee (2 methyl -4-octyl roofenyl) phenyl phosphonite, Gee (3 butyl-4-methyl-phenyl) Phenyl phosphonite, di (3-hexyl 4-ethyl monophenyl) Phenyl phosphonite, G (2, 4, 6 Trimethylphenyl) Phenyl phosphonite, G (2, 3 dimethyl-4-ethylrofurenyl) ) Phenylphosphonite, G (2, 6 Jetyl-3-butylphenyl) Phenylphosphona Di (2,3 dipropyl 5 butylphenyl) phenyl phosphonite, di (2, 4, 6 toly tert-butylphenol) phenyl phosphonite, bis (2,4 di tert-butyl-5 methylphenyl) biphenyl 4-ruluphosphonite, bis (2,4-di-tert-butyl-5-methylphenyl) -1,4- (bis (2,4-dibutyl-5-methylphenoxy) phosphino) biphenyl 4-ruluphosphonite, tetrakis (2 , 4 di-t-butyl-phenyl) 4, A 'biphenyl di-range phosphonite, tetrakis (2, 5 di-t-butyl-phenyl) 4, A'-bi-bi-di-range phosphonite, tetrakis (3, 5--di-t) Butylphenyl) 4,4'-biphenyl dirange phosphonite, tetrakis (2, 3, 4 trimethylphenyl) 4, A'-biphenyl dirange phosphonite, tetrakis (2, 3 dimethyl-5) 4, A'-biphenylenediphosphonite, tetrakis (2, 3 dimethyl-4-propylphenyl) 4, A'-biphenylenediphosphonite, tetrakis (2, 3 dimethyl-5-t-butylphenyl) 4, A'-biphenylenediene Phosphonite, Tetrakis (2, 5 Dimethinole 4 t butylphenyl) 4, A'-biphenyl dirange phosphonite, Tetrakis (2, 3— (Jetyl-5-methylphenyl) 4,4'-biphenyl dirange phosphonite, tetrakis (2, 6-jetyl-4-methylphenyl) 4, A'-biphenyl dirange phosphonite, tetrakis (2, 4, 5 triethyl phenyl) 4, A '-Biphenyl dirange phosphonite, tetrakis (2, 6 Jetyl 4 propyl phenyl) 4, A'-biphenyl dirange phosphonite, tetrakis (2, 5 Jetyl 6 butyl phenyl) 1, 4, A '— biphenyl dirange phosphonite , Tetrakis (2,3 Jetyl 5-t-butylphenyl) 1, 4, A'-Bihuylene diphosphonite, Tetrakis (2,5-Jetyl 6-t butylphenyl) 4, A 'Biphenyl di-range phosphonite, Tetrakis (2 , 3 dipropyl 5 methylphenyl) 4, '— biphenyl didiene phosphonite, tetrakis (2, 6 dipropyl monomethyl 4-methylphenol) 4, 4'-biphenyl dirange phosphonite, tetrakis (2, 6 dipropyl-5 ethylphenyl) 4, A'-biphenyl dirange phosphonite, tetrakis (2, 3 dipropyl-6 butyl phenyl) 4, A'-biphenyl dirange phosphonite, Tetrakis (2, 6 dipropyl 5 butylphenyl) 4, A'-biphenyl dirange phosphonite, tetrakis (2, 3 dibutyl-4 methyl phenyl) 4, A'-biphenyl dirange phosphonite, tetrakis (2, 5 dibutyl-3 methyl phenyl) 4, -Biphenyl dirange phosphonite, tetrakis (2, 6 dibutyl monomethyl 4-phenyl) 1, 4, A '— Biphenyl diphosphonate, tetrakis (2, 4 dibutyl t-methyl 3-methyl phenyl) 4, A' — Biphenyl Range Phosphonite, Tetrakis (2, 4 Di-tert-butyl-5-methylphenyl) 4, A 'Biphenyl di-range phosphonai , Tetrakis (2,4 di-tert-butyl-6-methylphenyl) 4, A'-biphenyl dirange phosphonite, tetrakis (2,5-di-tert-butyl-3-methyl phenyl) 4, A'-biphenyl di-range phosphonite, tetrakis (2,5 di) 4, A'-biphenylenediphosphonite, tetrakis (2, 5 di-tert-butyl-6-methylphenyl) 4, A'-biphenylenediphosphophosphonite, tetrax (2, 6 g tert-butyl-3-methylphenyl) 4, A'-biphenyl dirange phosphonate, tetrakis (2, 6 di-t-butyl 4-methyl phenyl) 1, 4, A '— bi-phenylene diphosphonite, tetrakis (2, 6 di-t-butyl-5-methyl phenyl) 4, Α 'Biphenyl dirange phosphonite, tetrakis (2, 3 dibutyl-4 ethenyl phenyl) 4, A'-Biphenyl dirange phosphonite, tetra Scan (2, 4 Jibuchiru 3 Echirufue two Norre) -4, '-biphenyl dirange phosphonite, tetrakis (2, 5 dibutyl-4 ethenyl phenyl) 4, A'-biphenyl dirange phosphonite, tetrakis (2, 4 di tert-butyl-3 ethenyl phenyl) 4, A '-biphenyl dirange phosphonite , Tetrakis (2,4 di-t-butyl-5-ethylphenyl) 4, A'-biphenyl dirange phosphonite, Tetrakis (2, 4 di-t-butyl 6 ethenyl phenyl) 1,4, A'- Biphenyl di-range phosphonite, tetrakis (2,5 di-tert-butyl 3-ethylphenyl) 1,4, A'-biphenylenediphosphonite, tetrakis (2,5-dibutyl-4-ethylphenyl) 4, A'-biphenylenediphosphophosphonite, tetrakis (2 , 5 di-tert-butyl-6-ethylphenyl) 4, A'-biphenyl dirange phosphonite, tetrakis (2,6-di-tert-butyl-3-ethyl phenyl) 4, A'-bi Ethylene diphosphonite, tetrakis (2, 6 di-tert-butylene 4-ethyl phenyl) 4, A'-biphenyl di-range phosphonite, tetrakis (2, 6 di-tert-butyl-5-ethyl diphenyl) 4, A'-biphenyl di-range phosphonite, Tetrax (2, 3, 4 tributyl phenyl) 1, 4, A '— Biphenyl dirange phosphonite, tetrakis (2, 4, 6 tri t butyl phenyl) 1, 4, Α' — Biphenyl dirange phosphonite Etc. Phosphorus compounds of the above type are commercially available, for example, from Ciba 'Specialty' Chemikanorezu Co., Ltd. under the trade name “IRGAFOS®-EPQ” and from Sakai Chemical Industry Co., Ltd. under the name “GSY-P 101”.

[0084] Among the phosphorus compounds useful in the present invention, even though phosphonite compounds are preferred, tetrakis (2, 4-di-tert-butylphenyl) 4, A'-biphenyl dirange phosphonite, etc. A particularly preferred one in which the two-range phosphonite compound is preferred is tetrakis (2,4 di-t-butyl-5-methylphenyl) -1,4 ′ A'-biphenyl di-phosphonate.

[0085] (Alkyl radical scavenger)

In the present invention, the “alkyl radical scavenger” means a compound having a group in which an alkyl radical can react rapidly and giving a stable product in which no subsequent reaction occurs after reaction with the alkyl radical.

[0086] Preferred alkyl radical scavengers in the present invention include compounds represented by the general formula (1) and compounds represented by the general formula (2). [0087] Hereinafter, the power to explain the compound represented by the general formula (1) used in the present invention in specific examples The present invention is not limited to these.

In the general formula (1), R represents a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, preferably a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, particularly preferably a hydrogen atom. Or it is a methyl group.

[0089] R and R each independently represent an alkyl group having from 8 to 8 carbon atoms,

twenty three

It may have a branched structure or a ring structure. R and R preferably include quaternary carbon

twenty three

C (CH) — R ′ ”structure (* represents the linking site to the aromatic ring, R ′ is carbon number 1

3 2

Represents an alkyl group of ~ 5. ). R is more preferably a tert butyl group, a tert amino group

2

Nore group. R is more preferably a tert butyl group, a tert amyl group or a tert ota group.

Three

A til group.

[0090] As a compound represented by the above general formula (1), Sumitomo Chemical Co., Ltd.

M "and" SumilizerGS "are commercially available.

[0091] Specific examples of the compound represented by the general formula (1) are illustrated below, but the present invention is not limited thereto.

[0092] [Chemical 3]

Next, specific examples of the compound represented by the general formula (2) used in the present invention will be described, but the present invention is not limited thereto.

[0097] In the general formula (2), R 1 to Ri are each independently a hydrogen atom or a substituent.

12 15

Or R and R may combine with each other to form a ring. . R represents a hydrogen atom or a substituent, n represents an integer of 1 to 4, and when n is 1, R

16 11 represents a substituent, and when n is an integer of 2 to 4, R represents a divalent to tetravalent linking group.

11

When R 1 to R 4 represent a substituent, the substituent is not particularly limited.

12 15

Group (for example, methyl group, ethyl group, propyl group, isopropyl group, t-butyl group, pentynole group, hexyl group, octyl group, dodecyl group, trifluoromethyl group, etc.), cycloalkyl group (for example, cyclopentyl group) Group, cyclohexyl group, etc.), aryl group (for example, phenyl group, naphthyl group, etc.), isylamino group (for example, acetylamino group, benzoylamino group, etc.), alkylthio group (for example, methylthio group, ethylthio group, etc.), arylthio Group (for example, phenylthio group, naphthylthio group, etc.), alkenyl group (for example, butyl group, 2-propenyl group, 3-buturyl group, 1-methyl-3-propenyl group, 3-pentyl group, 1-methyl-3) —Butul group, 4-hexenyl group, cyclohexenyl group, etc.), halogen atom (eg, fluorine atom, chlorine) Element, bromine atom, iodine atom etc.), alkynyl group (eg propargyl group etc.), heterocyclic group (eg pyridyl group, thiazolyl group, oxazolyl group, imidazolyl group etc.), alkylsulfonyl group (eg methylsulfonyl group) , Ethylsulfonyl group, etc.), arylsulfonyl group (for example, phenylsulfonyl group, naphthinoresulfonyl group, etc.), alkylsulfur group (for example, methylsulfuryl group, etc.), arylsulfifer group (for example, phenylsulfiyl group, etc.) L group, etc.), phosphono group, acyl group (for example, acetyl group, bivaloyl group, benzoyl group, etc.), strong rubamoyl group (for example, aminocarbonyl group, methylaminocarbonyl group, dimethylaminocarbonyl group, butylaminocarbonyl group). , Cyclohexylaminocarbonyl group, phenyl Aminocarbonyl group, 2-pyridylaminocarbonyl group, etc.), sulfamoyl group (eg, aminosulfonyl group, methylaminosulfonyl group, dimethylaminosulfonyl group, butylaminosulfonyl group, hexylaminosulfonyl group, cyclohexyl). Aminosulfonyl group, octylaminosulfonyl group, dodecylaminosulfonyl group, phenylaminosulfonyl group, naphthylaminosulfonyl group, 2-pyridylaminosulfonyl group, etc.), sulfonamide groups (for example, methanesulfonamide group, benzenesulfonamide) Group), cyano group, alkoxy group (e.g. methoxy group, ethoxy group, propoxy group etc.), arylenoxy group (e.g. phenoxy group, naphthinoreoxy group etc.), heterocyclic oxy group, siloxy group, acyloxy group (e.g. Asechiruo Xy group, benzoyl group, etc.), sulfonic acid group, sulfonic acid salt, aminocarbonyloxy group, amino group (eg, amino group, ethylamino group, dimethylamino group, butylamino group, cyclopentylamino group, 2-ethylhexylamino group) Group, dodecylamino group, etc.), anilino group (for example, phenylamino group, black-mouthed phenylamino group, toluidino group, anisidino group, naphthylamino group, 2-pyridylamino group, etc.), imide group, ureido group (for example, methylureido group, Ethylureido group, pentylureido group, cyclohexylureido group, octylureido group, dodecinoureido group, phenylenoureido group, naphthinoureido group, 2-pyridylaminoureido group, etc.), alkoxycarbonylamino groups (for example, , Methoxycarbonyl Group, phenoxycarbonylamino group, etc.), alkoxycarbonyl group (eg, methoxycarbonyl group, ethoxycarbonyl group, phenoxycarbonyl, etc.), aryloxycarbonyl group (eg, phenoxycarbonyl group, etc.) ), Heterocyclic thio group, thioureido group, carboxyl group, carboxylic acid salt, hydroxyl group, mercapto group, nitro group and the like. These substituents may be further substituted with similar substituents! /, Or even! /.

In the general formula (2), R 1 to R 5 are preferably a hydrogen atom or an alkyl group.

12 15

[0099] In the general formula (2), R represents a hydrogen atom or a substituent.

16 16

Examples of the substituent include the same groups as the substituents represented by R 1 to R 4. In particular, R is hydrogen

12 15 16 atoms are preferred.

[0100] In the general formula (2), n is a force S representing an integer of 1 to 4, and when n is 1, R is a substitution

11 represents a group, and examples of the substituent include the same groups as the substituents represented by R 1 to R 4.

12 15

. When n is an integer of 2 to 4, R 1 correspondingly represents a divalent to tetravalent linking group.

11

[0101] When the R force represents a quaternary to tetravalent linking group, the divalent linking group may have, for example, a substituent.

11

Examples thereof include a divalent alkylene group, a divalent arylene group which may have a substituent, an oxygen atom, a nitrogen atom, a sulfur atom, or a combination of these linking groups.

[0102] Examples of the trivalent linking group include, for example, a trivalent alkylene group which may have a substituent, a trivalent arylene group which may have a substituent, a nitrogen atom, or a group of these linking groups. It is possible to raise combinations, and as a tetravalent linking group, for example, a tetravalent alkylene group that may have a substituent, a tetravalent arylene group that may have a substituent, or a combination thereof. A combination of groups can be mentioned. [0103] In the general formula (2), n is preferably 1, and then R is a substituted or unsubstituted phenotype.

11

Preferred substituents for the phenyl group include alkyl groups having 1 to 18 carbon atoms, alkyl groups having 1 to 8 carbon atoms, preferably alkoxy groups having 1 to 18 carbon atoms, and carbon atoms 1 No! /, And 8 alkoxy groups are more preferred! /.

[0104] Specific examples of the compound represented by the general formula (2) in the present invention are shown below, but the present invention is not limited thereto.

[0105] [Chemical 7]

[8 ^] [Picture]

TCl0.0 / .00Zdf / X3d 38 Ϊ96890 / 800Ζ OAV

[0108] [Chemical 10]

1]

[0111] [Chemical 13]

[0112] [Chemical 14]

Compound

Mo, R ₄ R ₅

(2)-52 ― CHj — H — C ₄ ¾is) — H

(2 | -53 — ¾H _s (s> —H one ¾ day —H

(2) -5 — H — C _s H "(t >> — _H 2} -5S — C _s H _1t (— H — H"<< i >> — H

(2} ™ 56 ——H ~ ~ QsH ¾t) — H

(2 卜 S7 ——H —C ₄ H ₃ (s) — H

(2) -58 — C ₄ H #) — H —: H

(2) -59 — H — H

O

(2) 60 — ¾H) — H — H

(2) -61 ― C'i; jH — H — CH ₃ — H

(2) -62 —— CjiH ”— H ~ GH ₃ — H

(2} ~ 63 — H — CH _S One H} → 4 — H ™ ~ CH¾ — H

(2) -65 ~ C ₄ H ₉ (t) — H —CI .— H

(2) → — H ~ OCH ₃ — H

(2) -8? — CH ₉ (t) — H — GC ₈ H ₁₇ (n) — H

(2) -69 — H — H (2) -70 — H -OCH3 "" "" "j« j

(2}-71 — H “CH3 — H] iiwri K¾ N>f¾>N>

I I; i j

i ί I i

00 00 09 -s |

cs * m & W N> O φ W Mf] [(

7β

sο. , ί

{278 ~

¾. ~ To ΐ t Compound

No,

(2) 89 — N [-C it— <

H O

(2) "-90 — H CH ₃ — CH ₃ — H

-91 — H H — H

-92 — H n — H

(2) ~ -93 — H -H ~~ (CH ₂ ) ₃ OH — H

(2)--94 — Day of the week H — (GH _z ) ₂ OH — H

(2)--95 ー H ― iCH ₂ i _¾ OCOCH ₃ — H

{2 »--96 — H 0 (CH ₂ OH — C ₄ H ₉ (t) — H is)--97 — H -H ― C ₃ H ii — H

-98 —HO (CH ₂ } ₂ 0CH ₃ — H — H

] Compound

No. R ₂ R ₃ R ₄ R ₅

(2)-112 — H -H — CH ₂ OH — H

(2)-113 — H -H — CH ₂ OH — H

(2) _ 114 — H -H — S0 ₂ C ₈ H ₁₇ (i) — H

(2)-115 — H -C ₁₅ H ₃₁ (n) — H — H

(2)-116 — C ₉ H -H ― ^ 9Η ₉ — H

(2)-117 — CF ₃ -H — H — H

[0117] [Chemical 19]

[0118] [Chemical 20]

(Other antioxidants)

Specific examples of other antioxidants include dilauryl 3,3-thiodipropionate, dimyristyl 3,3'-thiodipropionate, distearyl 3,3-thiodipropionate, lauryl stearyl 3,3— Thiodipropionate, pentaerythritol-tetrax (/ 3 lauryl thiopropionate), 3, 9 bis (2 dodecylthioethyl) 2, 4, 8, 10-tetraoxaspiro [5, 5] undecane And the like compounds. The compounds of the above type are commercially available, for example, from Sumitomo Chemical Co., Ltd. under the trade names “Sumilizer TP L—R” and “Sumilizer TP—D”. Further, 3, 4 dihydro-1 2H-1-benzopyran compounds described in JP 08-27508, 3, 3′-spiro dichroman compounds, 1,1-spiroindane compounds, morpholine, thiomorpholine, Examples thereof include thiomorpholine oxide, thiomorpholine dioxide, compounds having a piperazine skeleton in the partial structure, oxygen scavengers such as dialkoxybenzene compounds described in JP-A-3-174150, and the like. These antioxidant partial structures can be part of the polymer or regularly pendant to the polymer.

[0120] Hindered amine light stabilizer

In the present invention, a hindered amine light stabilizer (as a deterioration preventing agent for heat-melting of a film-forming material and a deterioration preventing agent against external light exposed as a polarizer protective film after production or light from a backlight of a liquid crystal display) HALS) compounds, which are known compounds, such as US Pat. No. 4,619,956, column 5 to 11; and US Pat. No. 4,839,405, no. As described in columns 3-5, 2, 2, 6, 6-tetraalkylpiperidine compounds, or their acid addition salts or complexes of them with metal compounds are included.

[0121] Specific examples of hindered amine light stabilizers include bis (2, 2, 6, 6 tetramethyl-4-piperidyl) sebacate, bis (2, 2, 6, 6 tetramethyl-4-piperidyl) succinate, bis (1, 2, 2 , 6, 6-Pentamethyl-4-piperidyl) sebacate, bis (N oxytoxic 2, 2, 6, 6 tetramethyl-4-piperidyl) sebacate, bis (N benzyloxy 2, 2, 6, 6 tetramethyl-4-piperidyl) sebacate, bis ( N cyclohexyloxy 2, 2, 6, 6-tetramethyl-4-piperidyl) sebacate, bis (1, 2, 2, 6, 6 pentamethyl-4-piperidinole) 2— (3,5 di-tert-butyl-4-hydroxybenzenole) 2 Butyl malonate, bis (1-acroyl-2,2,6,6 tetramethyl-4-piperidinole) 2,2 bis (3,5 di-tert-butyl-4-hydroxybenzyl) -2 Til malonate, bis (1,2,2,6,6 pentamethyl-4-piperidyl) decandioate, 2,2,6,6 tetramethyl-4-piperidylmetatalylate, 4 [3— (3, (5,5 di-tert-butyl 4-hydroxyphenol Ninole) propionyloxy] -1 [2- (3- (3,5 di-t-butyl-4-hydroxyphenyl) propionyloxy) ethyl] -2, 2, 6, 6 tetramethylpiperidine, 2 methyl-2- (2, 2, 6, 6 tetramethyl-4-piperidyl) amino-N- (2, 2, 6, 6 tetramethyl-4-piperidyl) propionamide, tetrakis (2, 2, 6, 6, tetramethyl-4-piperidyl) 1, 2, 3, 4 Butanetetracarboxylate, Te Trakis (1, 2, 2, 6, 6 pentamethinore 4 piperidinoles) 1, 2, 3, 4 h, tan tetra force lupoxylate and the like.

[0122] In addition, as a specific example of a polymer type compound, N, N ', N ", N"' — Tetrakis [4, 6 bis [butyl (N methyl-2, 2, 6, 6 tetra Methylpiperidine—4-yl) amino] -triazine—2-yl] —4,7 diazadecane—1,10 diamine, dibutylamine and 1, 3,5 triazine N, N ′ bis (2, 2, 6, 6 Tetramethyl 4-piperidyl) -1, 6 Hexamethylenediamine and N— (2, 2, 6, 6 Tetramethyl 4-piperidyl) butyramine polycondensate, dibutylamine, 1, 3, 5-triazine and N , N 'Polycondensate with bis (2, 2, 6, 6 tetramethyl-4-piperidyl) butyramine, poly [{(1, 1, 3, 3 tetramethylbutyl) amino 1, 3, 5, triazine 1, 2, 4 Dil} {(2, 2, 6, 6 tetramethyl-4-piperidyl) imino} hexamethylene {(2, 2, 6, 6-tetramethyl mono-4-piperidi ) Imino}], 1, 6-hexanediamine mono N, N '— bis (2, 2, 6, 6-tetramethinole 4-piperidinole) and polyreforin 2,4,6-trichloro-1, 3, 5 triazine , Poly [(6 morpholino s triazine 1, 2, 4 dinole) [(2, 2, 6, 6, -tetramethyl-4-piperidyl) imino] monohexamethylene [(2, 2, 6, 6-tetramethyl-4-piperidyl) imino] ] High molecular weight HALS in which multiple piperidine rings are bonded via a triazine skeleton, such as a polymer of dimethyl succinate and 4-hydroxy 2, 2, 6, 6 tetramethyl-1-piperidine ethanol, 1, 2, 3 , 4-Butanetetracarboxylic acid, 1, 2, 2, 6, 6 Pentamethinoleol 4-piperidinanol and 3,9bis (2 hydroxy-1,1-dimethylethyl) 2, 4, 8, 10 Tetraoxaspiro [5, 5] Mixture with undecane Force S including, but not limited to, a compound in which a piperidine ring is bonded via an ester bond, and the like.

[0123] Among these, polycondensates of dibutylamine, 1, 3, 5 triazine and N, N ^f bis (2, 2, 6, 6-tetramethyl-4-piperidyl) ptyramine, poly [{(1, 1, 3, 3-tetramethylbutyl) amino-1, 3, 5 triazine-2,4 dil} {(2, 2, 6, 6 tetramethyl-4-piperidyl) imino} hexamethylene {(2, 2, 6, 6 tetramethyl-4-piperidyl) imino }), A polymer of dimethyl succinate and 4-hydroxy 2, 2, 6, 6 tetramethyl-1-piperidineethanol, etc., having a number average molecular weight (Mn) of 2,000-5,000 Is preferred.

[0124] Hinderdamine compounds of the above type are commercially available from, for example, Chino 'Specialty' Chemicals, "TINUVIN144" and "TINUVIN770", and ADEKA Co., Ltd. as "ADK STAB LA-52"! ! /

[0125] In the present invention, the hindered amine light stabilizer is preferably added in an amount of 0.2 to 5% by mass, more preferably 0.2 to 5% by mass based on the mass of the cellulose ester according to the present invention. Addition power S is preferable, and it is more preferable to add 0.5 to 2% by mass. Two or more of these may be used in combination.

[0126] <Acid scavenger>

Cellulose ester is preferably decomposed by an acid in a high temperature environment where melt film formation is performed. Therefore, the optical film of the present invention preferably contains an acid scavenger as a deterioration inhibitor. As an acid scavenger useful in the present invention, any compound that reacts with an acid to inactivate the acid can be used without limitation, and particularly described in US Pat. No. 4,137,201. A compound having an epoxy group is preferred. Epoxy compounds as such acid scavengers are known in the art and are derived by condensation of diglycidyl ethers of various polyglycols, especially about 8-40 moles of ethylene oxide per mole of polyglycol. Polyglycols, diglycidyl ethers of dalycerol, etc., metal epoxy compounds (for example, those conventionally used in and together with chlorinated polymer compositions), epoxidized ether condensation products, bis Phenolic A diglycidyl etherate (ie 4, 4'-dihydroxydiphenyldimethylmethane), epoxidized unsaturated fatty acid ester (especially about 4 to 2 carbon atoms of fatty acids of 2 to 22 carbon atoms) Esters of alkyl (eg, butyl epoxy stearate), and Epoxidized vegetable oils and other unsaturated natural oils, which are sometimes represented by the composition of various epoxidized long chain fatty acid triglycerides and the like (eg, epoxidized soybean oil, epoxidized linseed oil, etc.) Natural fatty glycerides or unsaturated fatty acids, and these fatty acids generally contain from 12 to 22 carbon atoms). In addition, as commercially available epoxy group-containing epoxide resin compounds, EPON 815C and other epoxidation processes are available. Ter oligomer oligomer condensation products can also be preferably used.

[0127] Further, acid scavengers that can be used in addition to the above include oxetane compounds, oxazoline compounds, alkaline earth metal organic acid salts and acetylacetonate complexes, and JP-A-5-194788. Including those described in paragraphs 68-105.

[0128] In the present invention, it is preferable to add the acid scavenger to the mass of the cellulose ester according to the present invention in an amount of 0.;! To 10% by mass. It is preferable to add 5% by mass, and it is more preferable to add 0.5-2% by mass. Two or more of these may be used in combination.

[0129] It should be noted that the acid scavenger can be used as an acid scavenger, an acid scavenger, an acid catcher or the like in the present invention.

[0130] <Metal deactivator>

A metal deactivator means a metal ion deactivating compound that acts as an initiator or catalyst in an oxidation reaction, and includes hydrazide compounds, oxalic acid diamide compounds, triazole compounds, and the like. , N'-bis [3- (3, (5-, 5-tert-butyl 4-hydroxyphenenole) propioninole] hydrazine, 2-hydroxyethyl oxalic acid diamide, 2-hydroxy-one N- (1H— 1, 2 , 4-triazole-1-3-inole) benzamide, N- (5-yert-butyl-2-ethoxyphenyl) -1-N, 1- (2-ethylphenyl) succinamide, and the like.

In [0131] the present invention, metal deactivators, for the mass of the cellulose ester of the present invention, from 0.0002 to 2 mass ^_0/0 that mosquito preferably be added Caro, further from 0.0005 to 2 mass ⁰ / Addition force of ₀ S is preferable, more preferably 0.00;! To 1% by mass is added. Two or more of these may be used in combination.

[0132] 《Plasticizer》

In forming an optical film by melt casting according to the present invention, it is necessary to add at least one plasticizer to the film-forming material.

[0133] The plasticizer is a force that is an additive having an effect of improving brittleness or imparting flexibility, generally by adding it to a polymer. An additive that lowers the melting temperature of the film, or at the same temperature! Used as an additive to lower the viscosity. By lowering the melting temperature or lowering the melt viscosity, it is possible to suppress degradation of the cellulose ester during the melting process. Therefore, in the present invention, any material having such an effect can be used as a plasticizer without limitation. Use power S. Such a melting point lowering effect / viscosity lowering effect is more likely to be obtained when a plasticizer to be added has a melting point or glass transition temperature lower than the glass transition temperature of cellulose ester.

[0134] In addition, the addition of a plasticizer may improve the mechanical properties of the cellulose ester film, improve the tearing strength, impart water resistance, and reduce moisture permeability. It is more preferable to use a material having an effect as a plasticizer.

[0135] The plasticizer also has the effect of suppressing deterioration of the cellulose ester in the hot-melting process by addition as described above, but the effect is due to the physical effect and is attributed to the chemical effect. Therefore, it is not classified as an anti-degradation agent in the present invention.

[0136] Plasticizers that satisfy the above-described conditions and are used in the present invention include, for example, phosphate ester plasticizers, polyhydric alcohol ester plasticizers (ethylene glycol ester plasticizers, glycerin ester plasticizers). Agents, diglycerin ester plasticizers, etc.), polyvalent rubonic acid ester plasticizers, carbohydrate ester plasticizers, polymer plasticizers and the like. Of these, polyhydric alcohol ester plasticizers and polyhydric carboxylic acid ester plasticizers are preferred, and polyhydric alcohol ester plasticizers are more preferred. The plasticizer may be liquid or solid, and is preferably colorless because of restrictions on the composition. The addition amount is good as long as it does not adversely affect the optical properties and mechanical properties, and the blending amount is appropriately selected within a range not impairing the object of the present invention, and preferably 1 to 25 with respect to the mass of the cellulose ester according to the present invention. mass ^_0/0 is a cellulose ester fill beam, characterized by containing. If the amount is less than 1% by mass, the effect of improving the flatness is not observed. If the amount is more than 25% by mass, bleeding out tends to occur and the stability of the film with time deteriorates. More preferably a cellulose ester fill beam contains a plasticizer from 3 to 20 weight ^_0/0, a cellulose ester film containing more preferably 5-15 wt%.

[0137] Hereinafter, the power to explain the plasticizer used in the present invention as a specific example. It is not limited to.

[0138] In the present invention, an ester plasticizer comprising a polyhydric alcohol and a monovalent carboxylic acid, and an ester plasticizer comprising a polyvalent carboxylic acid and a monohydric alcohol have high affinity with the cellulose ester. The ester plasticizer consisting of the preferred polyhydric alcohol and monovalent carboxylic acid is particularly preferred because it has a higher affinity with cellulose ester.

[0139] The polyhydric alcohol ester plasticizer refers to a compound obtained by condensing a compound having a plurality of hydroxyl groups in one molecule and a monovalent organic acid as a polyhydric alcohol ester plasticizer. The polycarboxylic acid ester plasticizer is a compound obtained by condensing a compound having a plurality of carboxylic acid groups in one molecule and a plurality of monovalent alcohols or phenols. Called.

[0140] Examples of polyhydric alcohols that are raw materials for ester plasticizers preferably used in the present invention include, for example, the following: The present invention is not limited to these.

[0141] Aditol, arabitol, ethylene glycol, glycerin, diglycerin, diethylene glycol, triethylene glycol, tetraethylenedaricol, 1,2-propanediol mono-ole, 1,3-propanediol, dipropylene Glycoleol, Tripropylene Glycolol, 1 Recall, 1, 2, 4-Butanetriol, 1,5-Pentanediol, 1,6-Hexanediole, Hexantrioneol, Galactitonor, Mannitore, 3-Methinorepentane 1, 3 , 5-triolinol, pinacol, sonorebitonole, trimethylolpropane, ditrimethylololepronone, trimethylololethane, pentaerythritol, dipentaerythritol, xylitol and the like. In particular, ethylene glycol, glycerin, and trimethylolpropane are preferable.

[0142] Examples of preferable organic acids include acetic acid, propionic acid, butyric acid, isobutyric acid, bivalic acid, acrylic acid, methacrylic acid, cyclohexanecarboxylic acid, benzoic acid, annic acid, 3, 4, 5— Trimethoxybenzoic acid, toluic acid, tert-butylbenzoic acid, naphthoic acid, picolinic acid, etc. Powerful effect of reducing the moisture permeability of cellulose ester! /, Unsaturation power Polycarboxylic acid, for example, aromatic carboxylic acid Forming an alcohol ester It is preferable.

[0143] The organic acid used in the polyhydric alcohol ester may be one kind or a mixture of two or more kinds. Also, all OH groups in polyhydric alcohols may be esterified, or some of them may be left as OH groups! /.

[0144] Specific examples of the ethylene glycol ester plasticizer, which is one of the polyhydric alcohol esters, include ethylene glycol alkyl ester plasticizers such as ethylene glycol diacetate and ethylene glycol dibutylate. , Ethylene glycol cycloalkyl ester plasticizers such as ethylene glycol di-cyclocarboxylate and ethylene glycol dicyclohexylcarboxylate, ethylene glycol dibenzoate, ethylene glycoloresin ethylene glycolo such as 4-methinolevenzoate Examples include rare-ester plasticizers. These alkylate groups, cycloalkylate groups, and arylate groups may be the same or different, and may be further substituted. Further, a mixture of alkylate group, cycloalkylate group and arylate group may be used, and these substituents may be covalently bonded. In addition, the ethylene glycol part may be substituted, and the partial structural strength of ethylene glycol ester S, part of the polymer, or may be regularly pendant, antioxidants, acid scavengers, UV absorbers Introduced into part of the molecular structure of additives such as! /

[0145] Specific examples of the glycerin ester plasticizer that is one of the polyhydric alcohol esters include glycerol such as triacetin, tributyrin, glycerol diacetate caprylate, glycerol carboxylate, and glycerol tricyclohexylcarboxylate. Diglycerin cycloalkyl esters such as cycloalkyl esters, glycerol tribenzoates, glycerol 4-methylbenzoates, etc., diglycerin acetate tricaprylate, diglycerin tetralaurate, etc. diglycerin cycloalkyl esters, diglycerin tetra Examples thereof include diglycerin aryl esters such as benzoate and diglycerin 3-methinolevenzoate. These alkylate groups, cycloalkylcarboxy The rate group and arylate group may be the same or different, and may be further substituted. Further, it may be a mixture of alkylate group, cycloalkyl carboxylate group and arylate group, and these substituents may be bonded by a covalent bond. In addition, the glycerin ester and diglycerin part may be substituted glycerin ester, and the diglycerin ester partial structure may be part of the polymer or regularly pendant. May be introduced into a part of the molecular structure of additives such as an agent and an ultraviolet absorber.

[0146] Specific examples of the other polyhydric alcohol ester plasticizers include the polyhydric alcohol ester plasticizers described in paragraphs 30 to 33 of JP-A-2003-12823.

[0147] These alkylate group, cycloalkyl carboxylate group and arylate group may be the same or different, and may be further substituted. In addition, a mixture of alkylate group, cycloalkylcarboxylate group and arylate group may be used, and these substituents may be bonded by a covalent bond. Furthermore, the polyhydric alcohol part may be substituted! /, Or the partial structural power of the polyhydric alcohol may be a part of the polymer or may be regularly pendant. Also, the antioxidant, the acid scavenger, the ultraviolet ray It may be introduced into a part of the molecular structure of an additive such as an absorbent.

[0148] Among the ester plasticizers composed of the polyhydric alcohol and the monovalent carboxylic acid, the alkyl polyhydric alcohol aryl ester is preferred. Specifically, the ethylene glycol dibenzoate and the glycerin tribe are preferred. Nzoate, diglycerin tetrabenzoate, exemplified compound 16 described in paragraph 31 of JP-A-2003-12823.

[0149] Specific examples of the dicarboxylic acid ester plasticizer that is one of the polyvalent carboxylic acid esters include alkyl dicarboxylic acid alkyl esters such as didodecyl malonate, dioctyl adipate, and dibutyl sebacate. Alkyl dicarboxylic acid cycloalkyl esters such as dicyclopentyl succinate, dicyclohexyl adipate, etc. Alkyl dicarboxylic succinate, diphenyl succinate, alkyl dicarboxylic acid aryl such as di-4-methylphenyl daltalate, etc. Ester plasticizers, dihexyl, 1,4-cyclohexane dicarboxylate, didecylbicyclo [2.2.1] heptane 2,3 dicarboxylate Cycloalkyldicarboxylic acid alkyl ester plasticizers such as dicyclohexyl-1,2-cyclobutanedicarboxylate, dicyclopropyl 1,2-cyclohexyl dicarboxylate, etc. Plasticizers such as diphenyl-1,1-cyclopropyldicarboxylate, di-2-naphthyl-1,4-cyclohexanedicarboxylate, etc., cycloalkyldicarboxylic acid aryl ester plasticizer, jetyl phthalate, Alyl dicarboxylic acid alkenyl ester plasticizers such as dimethyl phthalate, dioctyl phthalate, dibutyl phthalate and di-2-ethyl hexyl phthalate, and aryl carboxylic acid cycloalkyl esters such as dicyclopropyl phthalate and dicyclohexyl phthalate Tellurium plasticizers, diaryl phthalates, di-4-methylphenyl phthalates, etc. diaryl dicarboxylic acid aryl ester plasticizers acid ester plasticizers, acetyl trimethyl citrate, acetyl triethyl citrate, Examples thereof include citrate-based plasticizers such as acetyl butyl acetate. These alkoxy groups and cycloalkoxy groups may be the same or different, and these substituents, which may be mono-substituted, may be further substituted. The alkyl group and cycloalkyl group may be mixed, and these substituents may be bonded by a covalent bond. Further, the aromatic ring of phthalic acid may be substituted and a multimer such as a dimer, trimer or tetramer may be used. Also part of the phthalate ester partial polymer or part of the molecular structure of additives such as antioxidants, acid scavengers and UV absorbers that may be regularly pendant to the polymer Introduced! /

Examples of other polyvalent carboxylic acid ester plasticizers include alkyl polyvalent carboxylic acid alkyl ester plasticizers such as tridodecyl tri-force ruvalate and tributyl-meso butane 1, 2, 3, 4 tetracarboxylate. Alkyl polycarboxylic acid cycloalkyl ester type plasticizers such as tricyclohexyl tri-force ruvalate, tricyclopropyl-2-hydroxy 1,2,3-propane tricarboxylate, triphenyl 2-hydroxy 1, 2 , 3-propanetricarboxylate, tetra-3-methylphenyltetrahydrofuran 2, 3, 4, 5 Alkyl polycarboxylic acid arylene plasticizers such as tetracarboxylate, tetrahexyl, 1, 2, 3, 4 Cyclobutane tetracarboxylate Cycloalkyl polycarboxylic acid alkyl ester plasticizers such as tetrapentyl 1, 2, 3, 4 cyclopentane tetracarboxylate, tetracyclopropyl 1, 2, 3, 4-cyclobutane tetracarboxylate, tricyclohexyl 1 , 3,5-Cyclohexylolene tricarboxylate and other cycloalkyl polycarboxylic acid cycloalkyl ester-based plasticizers, triphenyl 1,3,5-cyclohexyl tricarboxylate, hex-4-methylphenol Nitrole 1, 2, 3, 4, 5, 6 Cycloalkyl polycarboxylic acid aryl ester plasticizer such as cyclohexylhexacarboxylate, tridodecylbenzene 1, 2, 4 tricarboxylate, tetraoctyl Benzyl 1, 2, 4, 5 Aryl polyalkyl carboxylic acid plastics such as tetracarboxylate Agent, tricyclopentinole benzene 1, 3, 5 tricarboxylate, tetracyclohexylbenzene 1, 2, 3, 5-tetracarboxylate, etc. Aryl polyvalent carboxylic acid aryl ester plasticizers such as 3,5-tetracarboxylate, hex-4-methylphenylbenzene 1, 2, 3, 4, 5, 6 hexacarboxylate and the like can be mentioned. These alkoxy groups and cycloalkoxy groups may be the same or different, and these substituents, which may be mono-substituted, may be further substituted. The alkyl group and cycloalkyl group may be mixed, or these substituents may be bonded by a covalent bond. Further, the aromatic ring of phthalic acid may be substituted and a multimer such as dimer, trimer or tetramer may be used. In addition, the partial structure of phthalate ester is part of the polymer, or part of the molecular structure of additives such as antioxidants, acid scavengers, and UV absorbers that may be regularly pendant to the polymer. It may be introduced.

[0151] Among the ester plasticizers composed of the polyvalent carboxylic acid and the monohydric alcohol, alkyl dicarboxylic acid alkyl esters are preferred. Specific examples include the dioctyl adipates.

[0152] Examples of other plasticizers used in the present invention include phosphate ester plasticizers, carbohydrate ester plasticizers, and polymer plasticizers.

[0153] Specific examples of phosphate ester plasticizers include phosphoric acid alkyl esters such as triacetyl phosphate and tributyl phosphate, tricyclobenzyl phosphate, cyclohexane and the like. Phosphoric acid cycloalkyl esters such as hexyl phosphate, triphenyl phosphate, tricresino rephosphate, credinole renin rephosphate, otachinoresi refineno rephosphate, diphen relevino reno phosphate, trioctino rephosphate, tri Examples include phosphate aryl esters such as butinorephosphate, trinaphthyl phosphate, trixylyl phosphate, trisorthobiphenyl phosphate. These substituents may be the same or different, and may be further substituted. Further, it may be a mix of an alkyl group, a cycloalkyl group, and an aryl group, and the substituents may be covalently bonded.

And phosphate esters such as arylene bis (diaryl phosphate) such as arylene bis (dialkyl phosphate), phenylene bis (diphenyl phosphate), and naphthylene bis (ditolyl phosphate). These substituents may be the same or different, and may be further substituted. A mixture of an alkyl group, a cycloalkyl group, and an aryl group may be used, and substituents may be covalently bonded.

[0155] Further, the partial structural strength of phosphate ester is a part of the polymer, or may be regularly pendant, and the molecular structure of additives such as antioxidants, acid scavengers, UV absorbers, etc. May be introduced to the part. Of the above compounds, aryl ester phosphate and arylene bis (diaryl phosphate) are preferred. Specifically, triphenyl phosphate and phenyl bis (diphenyl phosphate) are preferred!

[0156] Next, the carbohydrate ester plasticizer will be described. The carbohydrate means a monosaccharide, a disaccharide or a trisaccharide in which the saccharide is present in the form of a pyranose, a furanose half-membered ring or a five-membered ring. Non-limiting examples of carbohydrates include glucose, saccharose, ratatoose, cellobiose, mannose, xylose, ribose, galactose, arabinose, fructose, sorbose, cellotriose and raffinose. Carbohydrate ester refers to an ester compound formed by dehydration condensation of a hydroxyl group of a carbohydrate and a carboxylic acid, and more specifically, an aliphatic carboxylic acid ester of a carbohydrate or an aromatic Means carboxylic acid ester; Examples of the aliphatic carboxylic acid include acetic acid and propionic acid, and examples of the aromatic carboxylic acid include benzoic acid, toluic acid, and anilic acid. Carbohydrates have a number of hydroxyl groups depending on their type

Even if a part of 1S hydroxyl group reacts with carboxylic acid to form an ester compound, all hydroxyl groups react with carboxylic acid to form an ester compound! /. In the present invention, it is preferable that all the hydroxyl groups react with the carboxylic acid to form an ester compound.

[0157] Specific examples of the carbohydrate ester plasticizer include glucose pentaacetate, dalcose pentapropionate, gnolecose pentabtylate, saccharose octacetate, saccharose octabenzoate and the like. Of these, saccharose succinate benzoate is more preferred, and saccharose succinate benzoate is particularly preferred. For example, Daiichi Kogyo Seiyaku Co., Ltd. sells the above types of carbohydrate ester plasticizers under the trade names “Monopet SB” and “Monopet SOA”.

[0158] Specific examples of the polymer plasticizer include aliphatic hydrocarbon polymers, alicyclic hydrocarbon polymers, polyethyl acrylate, polymethyl methacrylate, methyl methacrylate and 2-hydroxy methacrylate. Copolymers with ethyl, acrylic polymers such as methyl methacrylate, methyl acrylate and 2-hydroxyethyl methacrylate, polybutyl isobutyl ether, poly N butyl pyrrolidone and other butyl polymers, polystyrene, Examples thereof include styrene polymers such as poly-4-hydroxystyrene, polyesters such as polybutylene succinate, polyethylene terephthalate and polyethylene naphthalate, polyethers such as polyethylene oxide and polypropylene oxide, polyamides, polyurethanes, and polyureas. The number average molecular weight is preferably about 1,000 to 500,000, particularly preferably 500 to 200,000. If it is less than 1000, there will be problems with volatilization, and if it exceeds 500,000, the aging ability will be reduced and the mechanical properties of the cellulose ester film will be adversely affected. These polymer plasticizers may be a homopolymer composed of one type of repeating unit or a copolymer having a plurality of repeating structures. Further, two or more of the above polymers may be used in combination.

[0159] In the cellulose ester film according to the present invention, a polyhydric alcohol and a monovalent carbon It is preferable to contain 1 to 25% by mass of an ester plasticizer comprising an acid, a polyvalent carboxylic acid and a monohydric alcohol or a tellurium plasticizer, but it may be used in combination with other plasticizers.

[0160] In the cellulose ester film according to the present invention, an ester plasticizer comprising a polyhydric alcohol and a monovalent carboxylic acid is more preferred, but an ester plasticizer comprising a trivalent or higher alcohol and a monovalent carboxylic acid. Is highly compatible with cellulose esters and can be added at a high addition rate, so that other types of plasticizers and additives can be used in combination with other types as necessary. This is the most preferred because plasticizers and additives can be used together easily.

[0161] <Ultraviolet absorber>

In the present invention, it is preferable that the film-forming material strength further contains an ultraviolet absorber from the viewpoint of improving durability. Ultraviolet absorbers are excellent in the ability to absorb ultraviolet rays with a wavelength of 370 nm or less from the viewpoint of preventing deterioration of polarizers and display devices with respect to ultraviolet rays, and from the viewpoint of liquid crystal display properties, they absorb little visible light with wavelengths of 400 nm or more. Those are preferred. Examples of the ultraviolet absorber used in the present invention include oxybenzophenone compounds, benzotriazole compounds, salicylic acid ester compounds, benzophenone compounds, cyanoacrylate compounds, nickel complex compounds, and triazine compounds. The ability to enumerate benzophenone compounds, less colored benzotriazole compounds, and triazine compounds are preferred. Further, UV absorbers described in JP-A-10-182621 and 8-337574, and polymer UV absorbers described in JP-A-6-148430 and JP-A-2003-113317 may be used. ,.

[0162] Specific examples of the benzotriazole compounds include 2- (2'-hydroxy 5'-methylphenol) benzotriazole, 2- (2'-hydroxy-3 ', 5'-di-tert-butinolephenol) benzo Triazole, 2— (2 ′ —hydroxyl 3 ′ —tert butyl 5 ′ —methylphenyl) benzotriazole, 2— (2 ′ —hydroxy 3 ′, 5 ′ di-tert butylphenyl) Benzotriazole, 2— (2 ′ —Hydroxyl 3 ′ — (3 ”, 4“, 5 ”, et al. —Tetrahydrophthalimidomethyl) 5 ′ —Methylphenyl) benzotriazole, 2, 2 Methylenebis (4— ( 1,1,3,3 tetramethylbutyl) -6- (2H-ben Zotriazole-2-phenol) phenol), 2— (2 ′ —hydroxy 3 ′ —tert butynole-5 —methylphenol) 1 5 clobenzobenzolazole, 2— (2 ′ —hydroxy 1 3 ′ tert butyl 5 ′ — (2-Octyloxycarbonylethyl) phenyl) 5— Chronobenzobenzotriazole, 2— (2 ′ —Hydroxy 1 3 ′ — (1-Methyl 1-phenylethyl) 5 ′-(1, 1, 3 , 3, —tetramethylbutyl) pheninole) benzotriazole, 2 (2H benzotriazole- 2 yl) -6 (straight and side chain dodecyl) -4 methyl phenol, octyl 3— [3— tert butyl 4 hydroxy 1 5— (black mouth 2H—benzotriazole-2-inole) phenyl] propionate and 2 ethylhexyl 3— [3-tert butyl 4 hydroxy 1 5— (5 black mouth 2H benzotriazole 2 — Gil) Phenyl ] A force S that can include a mixture of propionates S, but is not limited to these.

[0163] Moreover, TINUVIN 326, TINUVIN 109, TINUVIN 171, TINUVIN 900, TINUVIN 928, TINUVIN 928, TINUVIN 360 (V, deviation) are commercially available. And Chino 'Specialty' Chemicals), LA31 (A DEKA), Sumisorb250 (Sumitomo Chemical), and RUVA-100 (Otsuka Chemical).

[0164] Specific examples of benzophenone compounds include 2, 4-dihydroxybenzophenone, 2, 2'-dihydroxy-4-methoxybenzophenone, 2-hydroxy-4-methoxy-1-sulfo benzophenone, bis (2-methoxy-4-hydroxy) 1) Benzylphenylmethane) and the like S, but is not limited thereto.

In the present invention, the ultraviolet absorber is preferably a benzotriazole compound.

[0165] In the present invention, it is preferable that the UV absorber is added in an amount of 0.;! To 10% by mass based on the mass of the cellulose ester according to the present invention. It is preferable to add 5% by mass, and it is preferable to add 0.5 to 3% by mass. Two or more of these may be used in combination.

[0166] In addition, benzotriazole structure and triazine structural strength are part of the polymer, or other additives such as plasticizers, antioxidants and acid scavengers that may be regularly pendant to the polymer. Introduced into part of the additive's molecular structure!

[0167] The conventionally known UV-absorbing polymer is not particularly limited. For example, RUVA

Examples include a polymer obtained by homopolymerizing 93 (manufactured by Otsuka Chemical Co., Ltd.) and a polymer obtained by copolymerizing RUVA-93 with other monomers. Specifically, PUVA copolymerized with RUVA-93 and methyl methacrylate in a 3: 7 ratio (mass ratio) —30M, PUVA copolymerized with a ratio of 5: 5 (mass ratio) — 50M etc. are mentioned. Furthermore, the polymers described in JP-A-2003-113317 can be mentioned.

[0168] << Other additives >>

In the present invention, the cellulose ester can contain various additives in addition to the deterioration inhibitor, the plasticizer and the ultraviolet absorber. For example, matting agents, fillers, silica silicates and other inorganic compounds, dyes, pigments, phosphors, dichroic dyes, retardation control agents, refractive index regulators, gas permeation inhibitors, antibacterial agents, biodegradation Examples include a property-imparting agent. Moreover, an additive not classified into this can also be used if it has the said function.

[0169] And, as a method of incorporating these additives into the cellulose ester, the respective materials are mixed in a solid or liquid state, heated and melted and kneaded to obtain a uniform melt, and then cast. Even in the method of forming an optical film, all materials are dissolved in advance using a solvent to obtain a uniform solution, and then the solvent is removed to form a mixture of an additive and a cellulose ester. It may be melted by heating and cast to form an optical film.

[0170] (Matting agent)

The film according to the present invention can be applied with a matting agent in order to impart slipperiness, optical and mechanical functions. Examples of the matting agent include inorganic compound fine particles and organic compound fine particles.

[0171] The shape of the matting agent is preferably a spherical shape, a rod shape, a needle shape, a layer shape, a flat plate shape or the like. Examples of matting agents include metals such as silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide, calcium carbonate, kaolin, talc, calcined calcium silicate, hydrated calcium silicate, aluminum silicate, magnesium silicate, and calcium phosphate. It is possible to cite inorganic fine particles such as oxides, phosphates, silicates and carbonates and crosslinked polymer fine particles. Among these, silicon dioxide is preferable because it can reduce the haze of the film. These fine particles are preferably surface-treated with an organic substance and can reduce the haze of the film.

[0172] The surface treatment is preferably performed with halosilanes, alkoxysilanes, silazane, siloxane, or the like. The larger the average particle size of the fine particles, the greater the sliding effect. On the other hand, the smaller the average particle size, the better the transparency. The average primary particle size of the fine particles is in the range of 0.01 to 1.0 am. The average primary particle diameter of the preferred fine particles is preferably 550 nm, more preferably 714 nm. These fine particles are preferably used for generating irregularities of 0.01 to 1.0 m on the surface of the cellulose ester film.

[0173] Examples of silicon dioxide fine particles include Aerosil (AEROSIL) 200 200V 300 R972 R972V R974 R202 R812 0X50 TT600 NA X50 manufactured by Nippon Aerosil Co., Ltd. KE— P10 KE— P30 KE— manufactured by Nippon Shokubai Co., Ltd. P100 KE-P150 and the like can be used, and preferably, Aerosil 200V R972V NAX50 KE-P30 KE P100. Two or more of these fine particles may be used in combination.

[0174] When two or more kinds are used in combination, they can be mixed and used at an arbitrary ratio. Fine particles having different average particle diameters and materials, for example, Aerosil 200V and R972V can be used in a mass ratio of 0 · 1: 99. 9 99. 9: 0.1.

[0175] The matting agent is preferably added by kneading. As another form, a matting agent dispersed in advance in a solvent and a cellulose ester and / or a plasticizer and / or an antioxidant and / or an ultraviolet absorber are mixed and dispersed, and then the solid is obtained by volatilizing or precipitating the solvent. Power and use of this in the manufacturing process of the cellulose ester melt S, preferable from the viewpoint that the matting agent can be uniformly dispersed in the cellulose ester

[0176] The matting agent may be added to improve the mechanical, electrical, and optical properties of the film.

[0177] Note that, as these fine particles are added, the haze increases as the force to improve the slipperiness of the resulting film is added. Therefore, the content is preferably 0.00; more preferably 5% by mass. Preferably it is 0.005 1% by mass, more preferably 0.01-0.5% by mass. [0178] In the film according to the present invention, if the haze value exceeds 1.0%, the optical material is affected, so the haze value is preferably less than 1.0%, more preferably 0.5. Less than%. The haze value can be measured based on JIS-K7136.

[0179] In the storage or film-forming process of the film-forming material described above, deterioration reactions due to oxygen in the air may occur at the same time. In this case, the effect of reducing the oxygen concentration in the air can be used together with the stabilizing action of the additive in realizing the present invention. This includes the use of nitrogen or argon as an inert gas as a known technique, a degassing operation under reduced pressure to vacuum, and an operation in a sealed environment. At least one of these three methods can be used with the above additives. It can be used in combination with existing methods. By reducing the probability that the film forming material comes into contact with oxygen in the air, deterioration of the material can be suppressed, which is preferable for the purpose of the present invention.

[0180] 《Optical film》

Next, the details of the optical film of the present invention will be described.

[0181] In the present invention, the optical film is a functional film used in various display devices such as a liquid crystal display, a plasma display, and an organic EL display, and more specifically, a polarizing plate for a liquid crystal display device. Protective film, retardation film, antireflection film, brightness enhancement film, hard coat film, antiglare film, antistatic film, optical compensation film for expanding viewing angle, etc.

[0182] In the optical film according to the present invention, in addition to the cellulose ester according to the present invention, a cellulose ester resin, a cellulose ether resin, a bull resin (polyacetate bull resin, polybull alcohol) not related to the present invention Olefin resin (norbornene resin, monocyclic cyclic olefin resin, cyclic conjugated gen resin, vinyl alicyclic hydrocarbon resin, etc.), polyester resin (aromatic polyester) , Aliphatic polyesters or copolymers containing them), acrylic resins (including copolymers), polycarbonate resins, polystyrene resins, polysulfone resins, polyarylate resins, and the like. The content of the resin other than the cellulose ester is preferably 0.

[0183] The optical film according to the present invention includes a polarizing plate protective film, a retardation film, and an optical compensation film. It is preferably used for a film, and particularly preferably for a polarizing plate protective film.

[0184] <Melt casting method>

The optical film according to the present invention is manufactured by melt casting as described above. The molding method by melt casting that is heated and melted without using the solvent used in the solution casting method (for example, methylene chloride, etc.) is more specifically, melt extrusion molding method, press molding method, inflation method, They can be classified into injection molding methods, blow molding methods, stretch molding methods, and the like. Among these, in order to obtain a polarizing plate protective film having excellent mechanical strength and surface accuracy, the melt extrusion molding method is excellent.

[0185] The film-forming material is required to have little or no volatile component during the melting and film-forming process. This is for foaming during heating and melting to reduce or avoid deterioration of the planarity of the defects inside the film.

[0186] The content of the volatile component when the film-forming material is melted is 1% by mass or less, preferably 0.5% by mass or less, more preferably 0.2% by mass or less, and even more preferably 0. It is desired to be 1% by mass or less. In the present invention, using a differential thermogravimetric measuring device (TG / DTA200 manufactured by Seiko Denshi Kogyo Co., Ltd.), the heating loss from 30 ° C. to the temperature corresponding to the melt casting is obtained, and the amount is contained in the volatile component Amount.

[0187] The film-forming material to be used preferably removes volatile components typified by the moisture and the solvent before the film is formed or during heating. A known drying method can be applied to the removal method, and it can be performed by a heating method, a decompression method, a heating decompression method, or the like, or even in an atmosphere in which nitrogen is selected as the inert gas. Yo! / When these known drying methods are performed, it is preferable in terms of film quality that the film forming material is not decomposed in a temperature range.

[0188] By drying before film formation, generation of volatile components can be reduced. Cellulose ester alone or at least one mixture of cellulose ester and film forming material other than cellulose ester or It can also be divided into compatible materials and dried. The drying temperature is preferably 70 ° C or higher. When a material having a glass transition temperature exists in the material to be dried, heating to a drying temperature higher than the glass transition temperature may cause the material to melt and be difficult to handle. Below the transition temperature It is preferable. When multiple substances have glass transition temperatures, the glass transition temperature with the lower glass transition temperature is used as a reference. More preferably, it is 70 ° C. or higher and (glass transition temperature −5) ° C. or lower, more preferably 110 ° C. or higher and (glass transition temperature 20) ° C. or lower. The drying time is preferably 0.5 to 24 hours, more preferably 1 to; 18 hours, and further preferably 1.5 to 12 hours. If the drying temperature is too low, the removal rate of volatile components will be low, and it will take too much time to dry. In addition, the drying process may be divided into two or more stages. For example, the drying process includes a preliminary drying process for storing materials, and a immediately preceding drying process performed immediately before film formation to one week before. Also good.

[0189] (Melt extrusion method)

Hereinafter, the method for producing the cellulose ester film of the present invention will be described by taking the melt extrusion molding method as an example.

FIG. 1 is a schematic flow sheet showing the overall configuration of an apparatus for carrying out the method for producing a cellulose ester film according to the present invention, and FIG. 2 is an enlarged view of a cooling roll portion from a casting die.

In FIG. 1 and FIG. 2, the method for producing a cellulose ester film according to the present invention is performed by mixing film materials such as cellulose resin and then using an extruder 1 to the first cooling roll 5 from the casting die 4. It is melt-extruded on top and circumscribed on the first cooling roll 5, and further circumscribed on the three cooling rolls in total, the second cooling roll 7 and the third cooling roll 8, and then cooled and solidified to form a film 10. . Next, the film 10 peeled off by the peeling roll 9 is then stretched in the width direction by holding both ends of the film by the stretching device 12 and then wound by the winding device 16. Further, in order to correct the flatness, a touch roll 6 for pressing the molten film on the surface of the first cooling roll 5 is provided. The touch roll 6 has an elastic surface and forms a two-piece with the first cooling roll 5. Details of Touch roll 6 will be described later.

[0192] In the method for producing a cellulose ester film according to the present invention, the conditions for melt extrusion can be carried out in the same manner as the conditions used for other thermoplastic resins such as polyester. The material is preferably dried beforehand. Desirably, the moisture should be dried to lOOOppm or less, preferably 200ppm or less using a vacuum or vacuum dryer or dehumidifying hot air dryer. That's right.

[0193] For example, the cellulose ester dried under hot air, vacuum, or reduced pressure is melted at an extrusion temperature of about 200 to 300 ° C using an extruder 1, and filtered through a leaf disk type filter 2 to remove foreign matters. To do.

[0194] When being introduced into the extruder 1 from a supply hopper (not shown), it is preferable to prevent oxidative decomposition and the like under an inert gas atmosphere under vacuum or reduced pressure.

[0195] When additives such as a plasticizer are not mixed in advance, they may be kneaded in the middle of the extruder. In order to add uniformly, it is preferable to use a mixing apparatus such as Static Mixer 3.

[0196] In the present invention, the cellulose ester and other additives such as an anti-degradation agent added as necessary are preferably mixed before melting, and the cellulose ester and the additive are mixed before heating. More preferably. Mixing may be performed by a mixer or the like, or may be performed in the cellulose resin preparation process as described above. When a mixer is used, a general mixer such as a V-type mixer, a conical screw type mixer, a horizontal cylindrical type mixer, a Henschel mixer, or a ribbon mixer can be used.

[0197] After the film-forming material is mixed as described above, the mixture may be directly melted and formed into a film using the extruder 1, but once the film-forming material is pelletized, The pellets may be melted by the extruder 1 to form a film. In addition, when the film-forming material includes a plurality of materials having different melting points, a so-called braided semi-melt is once produced at a temperature at which only the material having a low melting point is melted, and the semi-melt is extruded 1 It is also possible to form a film by throwing it into the film. Easily thermally decomposed into film-forming materials! / If the material contains a material, it is possible to directly form a film without producing pellets in order to reduce the number of melting times, The method of making a film and making a film is preferred.

[0198] Extruder 1 can use various commercially available extruders. Melt kneading The extruder 1 may be a single-screw extruder or a twin-screw extruder, which is preferable for an extruder. When forming a film directly without producing pellets from a film-forming material, it is preferable to use a twin-screw extruder because an appropriate degree of kneading is required, but even with a single-screw extruder, the screw shape is Moderate kneading by changing to a kneading type screw such as mold, unimelt type, dull mage, etc. Can be used. Once pellets or braided semi-melts are used as film forming materials, they can be used with either single-screw extruders or twin-screw extruders.

[0199] In the extruder 1 and the cooling step after extrusion, the oxygen concentration is preferably lowered by substituting with an inert gas such as nitrogen gas or reducing the pressure.

[0200] The melting temperature of the film-forming material in the extruder 1 has different conditions depending on the viscosity and discharge amount of the film-forming material, the thickness of the sheet to be manufactured, etc. On the other hand, it is Tg or more and Tg + 130 ° C or less, preferably Tg + 10 ° C or more and Tg + 120 ° C or less.

[0201] The temperature at the time of melt extrusion of the present invention is preferably in the range of 200 ° C to 270 ° C. Furthermore, it is preferable to be in the range of 230-260 ° C!

[0202] The melt viscosity at the time of extrusion is 1 to 10,000 Pa-s, preferably 10 to lOOOPa's. In addition, a shorter residence time of the film forming material in the extruder 1 is preferably within 5 minutes, preferably within 3 minutes, and more preferably within 2 minutes. The residence time depends on the type of extruder 1 and the extrusion conditions, but it can be shortened by adjusting the material supply rate, L / D, screw rotation speed, screw groove depth, etc. Is possible.

[0203] The shape, rotation speed, and the like of the screw of the extruder 1 are appropriately selected depending on the viscosity, discharge amount, and the like of the film-forming material. In the present invention, the shear rate in the extruder 1 is 1 / second to 1000 / second, preferably 5 / second to 1000 / second, more preferably 10 / second to 100 / second.

[0204] The extruder 1 that can be used in the present invention is generally available as a plastic molding machine.

The film forming material extruded from the extruder 1 is sent to the casting die 4 and extruded from the slit of the casting die 4 into a film shape. The casting die 4 is not particularly limited as long as it is used for producing a sheet or a film. As the material of the casting die 4, hard chromium, chromium carbide, chromium nitride, titanium carbide, titanium carbonitride, titanium nitride, super steel, ceramic (tungsten carbide, aluminum oxide, chromium oxide), etc. are sprayed or plated. Buffing as surface treatment, lapping using # 1000 or higher whetstone, #cutting using diamond wheel of # 1000 or higher (cutting direction is perpendicular to resin flow direction) ), Those subjected to processing such as electrolytic polishing, electrolytic composite polishing, and the like. A preferred material for the rip portion of the casting die 4 is the same as that of the casting die 4. The surface accuracy of the lip is preferably 0.5S or less, more preferably 0.2S or less.

[0206] The slit of the casting die 4 is configured such that the gap can be adjusted. This is shown in Fig. 3. Of the pair of lips forming the slit 32 of the casting die 4, one is a flexible lip 33 having low rigidity and easily deformed, and the other is a fixed lip 34. A large number of heat bolts 35 are arranged with a constant pitch in the width direction of the casting die 4, that is, in the length direction of the slit 32. Each heat bolt 5 is provided with a block 36 having an embedded electric heater 37 and a cooling medium passage, and each heat bolt 35 penetrates each block 36 vertically. The base of the heat bolt 35 is fixed to the die body 31 and the tip is in contact with the outer surface of the flexible lip 33. While the block 36 is constantly air-cooled, the input to the embedded electric heater 37 is increased or decreased to increase or decrease the temperature of the block 36, thereby causing the heat bolt 35 to thermally expand and contract, thereby displacing the flexible lip 33 and the film thickness. Adjust. A thickness gauge is installed at the required location in the wake of the die, and the web thickness information detected by this is fed back to the control device, and this thickness information is compared with the set thickness information by the control device. It is also possible to control the power or the ON rate of the heat bolt heating element by the signal of the correction control amount that comes. The heat bolt preferably has a length of 20 to 40 cm and a diameter of 7 to 14 mm, and a plurality of, for example, several tens of heat bolts are preferably arranged at a pitch of 20 to 40 mm. Instead of a heat bolt, a gap adjustment member mainly composed of a bolt that adjusts the slit gap by moving it back and forth in the axial direction manually can be provided. The slit gap adjusted by the gap adjusting member is usually 200 to 1000 m, preferably 300 to 800 〃m, more preferably 400 to 600 〃111.

[0207] The first to third cooling rolls are made of seamless steel pipe with a wall thickness of about 20 to 30 mm, and the surface is mirror finished. Inside, a pipe for flowing the coolant is arranged, and it is configured so that heat can be absorbed from the film on the roll by the coolant flowing through the pipe. Of the first to third cooling rolls, the first cooling roll 5 corresponds to the rotating support of the present invention.

On the other hand, the touch roll 6 in contact with the first cooling roll 5 has an elastic surface and the first cooling roll 5 The pressing force applied to the roll 5 deforms along the surface of the first cooling roll 5 to form a two-pipe between the first roll 5 and the first cooling roll 5. That is, the touch roll 6 corresponds to the clamping rotary body of the present invention.

[0209] FIG. 4 shows a schematic cross section of one embodiment of the touch roll 6 (hereinafter, touch roll A). As shown in the figure, the Tachronole A has an elastic roller 42 disposed inside a flexible metal sleeve 41.

[0210] The metal sleeve 41 is made of stainless steel having a thickness of 0.3 mm and has flexibility. If the metal sleeve 41 is too thin, the strength will be insufficient, and if it is too thick, the elasticity will be insufficient. The thickness of the metal sleeve 41 is preferably 0.;! To 1.5 mm. The elastic roller 42 is a roll formed by providing a rubber 44 on the surface of a metal inner cylinder 43 that is rotatable through a bearing. When the touch roll A is pressed toward the first cooling roll 5, the elastic roller 42 presses the metal sleeve 41 against the first cooling roll 5, and the metal sleep 41 and the elastic roller 42 form the shape of the first cooling roll 5. It deforms while conforming to the familiar shape, and forms a two-pipe with the first cooling roll. Cooling water 45 flows in a space formed between the metal sleeve 41 and the elastic roller 42.

5 and 6 show a touch roll B which is another embodiment of the pinching rotary member. The touch roll B includes a flexible, seamless stainless steel pipe (thickness 4 mm) outer cylinder 51, and a high-rigidity metal inner cylinder 52 arranged coaxially inside the outer cylinder 51. It is roughly composed of A coolant 54 flows in a space 53 between the outer cylinder 51 and the inner cylinder 52. Specifically, in the touch roll B, outer cylinder support flanges 56a and 56b are attached to the rotating shafts 55a and 55b at both ends, and a thin metal outer cylinder 51 is attached between the outer peripheral portions of the both outer cylinder support flanges 56a and 56b. It has been. In addition, a fluid supply pipe 59 is arranged in the same axial center in a fluid discharge hole 58 formed in the axial center portion of one rotary shaft 55a and forming a fluid return passage 57, and the fluid supply pipe 59 is The thin metal outer cylinder 51 is connected and fixed to the fluid shaft cylinder 60 arranged at the shaft center portion. Inner cylinder support flanges 61a and 61b are attached to both ends of the fluid shaft cylinder 60, respectively, and approximately 15 to 20 mm from the outer peripheral part of the inner cylinder support flanges 61a and 61b to the outer cylinder support flange 56b on the other end side. A metal inner cylinder 52 having a certain thickness is attached. Between the metal inner cylinder 52 and the thin metal outer cylinder 51, for example, a coolant of about 10 mm An inflow space 53 is formed, and in the vicinity of both ends of the metal inner tube 52, an outflow port 52a and an inflow port 52b that connect the inflow passage 53 and the intermediate passages 62a, 62b outside the inner tube support flanges 61a, 61b. Are formed! /

[0212] Further, the outer cylinder 51 is designed to be thin as long as the thin cylinder theory of elastodynamics can be applied in order to have flexibility, flexibility, and resilience close to rubber elasticity. The flexibility evaluated by this thin-walled cylinder theory is expressed by the thickness t / roll radius r, and the smaller the t / r, the higher the flexibility. For Tachtrol B, flexibility is the optimal condition when t / r≤0.03. Normally, the commonly used touch rolls have a roll diameter R = 200 to 500 mm (roll radius r = R / 2), a roll width effective width L = 500 to; 1600 mm, r / L 1 Is. As shown in Fig. 6, for example, when the roll diameter is R = 300 mm and the effective roll width is L = 1200 mm, the appropriate thickness t is 150 X 0.03 = 4.5 mm or less, but the molten sheet width is 1300 mm. When the average linear pressure is 98 N / cm, the outer cylinder 51 and the cooling roll have the same spring constant by setting the thickness of the outer cylinder 51 to 3 mm compared to the rubber roll of the same shape. The two-pipe width k in the roll rotation direction is about 9mm, which is almost the same as the rubber roll's nip width of about 12mm, and can be pinched under similar conditions. It should be noted that the amount of deflection at the two-pipe width k is about 0.05 to 0.1 mm.

[0213] Here, t / r≤0.03 force When the general roll diameter R = 200-500mm, especially in the range of 2mm≤t≤5mm, sufficient flexibility is obtained, In addition, thinning by machining can be easily performed, and this is an extremely practical range. If the wall thickness is 2mm or less, high-precision machining cannot be performed due to elastic deformation during machining.

[0214] This conversion value of 2mm≤t≤5mm is 0.008≤t / r≤0.

However, in practical use, it is better to increase the wall thickness in proportion to the roll diameter under the condition of 03. For example, t = 2 to 3 mm for roll diameter: R = 200, and t = 4 to 5 mm for roll diameter: R = 500.

[0215] The touch rolls A and B are urged toward the first cooling roll by urging means (not shown). The urging force of the urging means is F, and the value F / W (linear pressure) of the film in the nip excluding the width W in the direction along the rotation axis of the first cooling roll 5 is 9.8 to 147N Set to / cm. According to the present embodiment, the nip between the touch rolls A and B and the first cooling roll 5 Is formed, and the flatness may be corrected while the film passes through the nip. Therefore, the film is sandwiched for a long time with a small linear pressure compared to the case where the touch roll is made of a rigid body and no ep is formed between the first cooling roll and the flatness can be more reliably corrected. Can do. In other words, if the linear pressure is less than 9.8 N / cm, the die line cannot be sufficiently eliminated. On the other hand, if the linear pressure is higher than 147 N / cm, the finoleum will not easily pass through the nip, resulting in unevenness in place of the film thickness.

[0216] In addition, since the surfaces of the touch rolls A and B are made of metal, the surfaces of the touch rolls A and B can be made smoother than when the surfaces of the touch rolls are rubber, so a film with high smoothness can be obtained. Obtainable. As a material of the elastic body 44 of the elastic roller 42, ethylene propylene rubber, neoprene rubber, silicon rubber or the like can be used.

[0217] Now, in order to satisfactorily eliminate the die line by the touch roll 6, it is important that the viscosity of the film when the pressure roll 6 is pressed is in an appropriate range. Cellulose esters are known to have a relatively large change in viscosity with temperature. Therefore, it is important to set the temperature of the film at which Tuttilol 6 clamps the cellulose film to an appropriate range in order to set the viscosity when Tutroll 6 clamps the cellulose ester film to an appropriate range. Become. Then, the present inventor assumes that when the glass transition temperature of the cell mouth ester film is Tg, the temperature T of the film immediately before the film is sandwiched between the touch rolls 6 satisfies Tg <T <Tg + 110 ° C. It was found that this should be set. If the film temperature is lower than T force STg, the viscosity of the film is too high and the die line cannot be corrected. On the other hand, if the temperature T force of the film is higher than STg + 110 ° C, the film surface and the roll do not adhere uniformly, and the die line cannot be corrected. Preferably more preferably Ji Ding _§ + 10 ° <Ding 2 <Ding _§ + 90 ° is Tg + 20 ° C <T2 rather Tg + 7 0 ° C. In order to set the temperature of the film when Tachiroll 6 clamps the cellulose ester film to an appropriate range, the melt extruded from the casting die 4 comes into contact with the first cooling hole 5 from the position P1 to the first. The length L of the nip between the cooling roll 5 and the touch roll 6 along the rotation direction of the first cooling roll 5 may be adjusted.

[0218] In the present invention, preferred materials for the first roll 5 and the second roll 6 include carbon steel, stainless steel, resin, and the like. Also, it is preferable to increase the surface accuracy, and the surface roughness should be 0 3S or less, more preferably 0.01S or less.

[0219] In the present invention, by reducing the pressure from the opening (lip) of the casting die 4 to the first roll 5 to 70 kPa or less, the above-described die line correction effect is more greatly expressed. discovered. The reduced pressure is preferably 50 to 70 kPa. There is no particular limitation on the method of keeping the pressure from the opening (lip) of the casting die 4 to the first roll 5 at 70 kPa or less. There is a way. At this time, the suction device is preferably subjected to a treatment such as heating with a heater so that the device itself does not become a place where the sublimate adheres. In the present invention, if the suction pressure is too small, the sublimate cannot be sucked effectively, so it is necessary to set the suction pressure to an appropriate value.

[0220] In the present invention, the film-like cellulose ester in a molten state is transferred from the T die 4 to the first roll (first cooling roll) 5, the second cooling roll 7, and the third cooling roll 8. The film is cooled and solidified while being brought into close contact with each other, and an unstretched cell mouth ester film 10 is obtained.

In the embodiment of the present invention shown in FIG. 1, the cooled and solidified unstretched film 10 separated from the third cooling roll 8 by the peeling roll 9 is provided with a dancer roll (film tension adjusting tool) 11. Then, the film is guided to a stretching machine 12, where the film 10 is stretched in the transverse direction (width direction). By this stretching, the molecules in the film are oriented.

[0222] As a method of stretching the film in the width direction, a known tenter or the like can be preferably used. In particular, it is preferable to set the stretching direction to the width direction because lamination with a polarizing film can be performed in a roll form. By stretching in the width direction, the slow axis of the cellulose ester film made of the cellulose ester film becomes the width direction.

[0223] On the other hand, the transmission axis of the polarizing film is also usually in the width direction. By incorporating into the liquid crystal display device a polarizing plate that is laminated so that the transmission axis of the polarizing film and the slow axis of the optical film are parallel, the display contrast of the liquid crystal display device can be increased and good A great viewing angle can be obtained.

[0224] The glass transition temperature Tg of the film-forming material can be controlled by varying the material type constituting the film and the ratio of the constituting material. When a phase difference film is produced as a cellulose ester film, Tg is preferably 120 ° C or higher, and more preferably 135 ° C or higher. In a liquid crystal display device, the temperature of the device itself in the image display state. The temperature environment of the film changes due to the rise, for example, the temperature rise from the light source. At this time, if the Tg of the film is lower than the use environment temperature of the film, the retardation value derived from the orientation state of the molecules fixed inside the film by stretching and the dimensional shape as the film are greatly changed. If the Tg of the film is too high, the temperature when the film forming material is filmed becomes high, so that the energy consumption for heating is high, and the material itself may be decomposed when it is filmed, resulting in coloring. Therefore, Tg is preferably 250 ° C or lower.

[0225] In addition, the stretching step may be appropriately adjusted so as to have the characteristics required for the target optical film, which may be subjected to known heat setting conditions, cooling, and relaxation treatment.

[0226] In order to impart physical properties of the retardation film and a function as a retardation film for expanding the viewing angle of the liquid crystal display device, the stretching step and the heat setting treatment are appropriately selected and performed. When such a stretching process and heat setting process are included, the heating and pressing process is performed before the stretching process and the heat setting process.

[0227] When a retardation film is produced as a cellulose ester film and further combined with the function of a polarizing plate protective film, it is necessary to control the refractive index. However, the refractive index can be controlled by a stretching operation. In addition, a stretching operation is a preferred method. The stretching method is described below!

[0228] Necessary by stretching 1.0 to 2.0 times in one direction of cellulose resin and 1.01 to 2.5 times in the direction perpendicular to the film plane in the stretching process of retardation film It is possible to control the return values Ro and Rt. Here, Ro indicates in-plane retardation, and Rt indicates thickness direction retardation.

[0229] Retardation Ro and Rt are obtained by the following equations.

[0230] Formula (i) Ro = (nx-ny) X d

Formula (ii) Rt = ((nx + ny) / 2 -nz) X d

(Where nx is the refractive index in the slow axis direction in the film plane, ny is the refractive index in the fast axis direction in the film plane, nz is the refractive index in the thickness direction of the film (refractive index is 23 ° C, 55 (Measured at a wavelength of 590 nm in an environment of% RH), d represents the film thickness (nm).

The refractive index of the optical film was measured using an Abbe refractometer (4T), and the thickness of the film was Using a micrometer, the retardation value can be measured using an automatic birefringence meter KOBRA-21AD H (manufactured by Oji Scientific Instruments) or the like.

[0231] Stretching can be performed sequentially or simultaneously, for example, in the longitudinal direction of the film and in the direction perpendicular to the longitudinal direction of the film, that is, in the width direction. At this time, if the stretching ratio in at least one direction is too small, a sufficient phase difference cannot be obtained, and if it is too large, stretching may become difficult and film breakage may occur.

[0232] For example, in the case of stretching in the melt casting direction, if the shrinkage in the width direction is too large, the value of nz becomes too large. In this case, it can be improved by suppressing the width shrinkage of the film or stretching in the width direction. When stretching in the width direction, the refractive index may be distributed in the width direction. This distribution may appear when the tenter method is used. When the film is stretched in the width direction, a shrinkage force is generated at the center of the film and the end is fixed. It is thought to be called the Boeing phenomenon. Even in this case, by stretching in the casting direction, the bowing phenomenon can be suppressed and the distribution of phase difference in the width direction can be reduced.

[0233] Stretching in biaxial directions perpendicular to each other can reduce the film thickness fluctuation of the obtained film. If the film thickness variation of the retardation film is too large, the retardation will become uneven, and unevenness such as coloring may be a problem when used in a liquid crystal display device.

[0234] The film thickness variation of the cellulose ester film is preferably in the range of ± 3%, more preferably ± 1%. For the purposes as described above, the method of stretching in the biaxial directions perpendicular to each other is effective, and the stretching ratio in the biaxial directions perpendicular to each other is finally 1.0 to 2.0 times in the casting direction. In the width direction, it is preferable to be in the range of 1.01-2.5 times in the casting direction 1.001 ~; 1.5 times in the width direction, 1.05-2. It is more preferable to obtain the required retardation value.

[0235] When the absorption axis of the polarizer exists in the longitudinal direction, the transmission axis of the polarizer coincides with the width direction. In order to obtain a long polarizing plate, it is preferable to extend the retardation film so as to obtain a slow axis in the width direction.

[0236] When a cellulose ester that obtains positive birefringence with respect to stress is used, the slow axis of the retardation film can be imparted in the width direction by stretching in the width direction from the above-described configuration. wear. In this case, in order to improve the display quality, it is preferable to be in the direction of the slow axial force width of the retardation film. In order to obtain the desired retardation value,

Formula, (stretch ratio in the width direction)> (stretch ratio in the casting direction)

It is necessary to satisfy the following conditions.

[0237] After stretching, the edge of the film was slit into a product width by slitter 13 and cut off, and then knurled (embavoding) by a knurling device consisting of embossing ring 14 and back roll 15 at both ends of the film. It is applied to the part and wound by the winder 16 to prevent sticking in the cellulose ester film (original winding) F and generation of scratches. The method of knurling can force a metal ring having an uneven pattern on its side surface by heating or pressing. Note that the clip grips at both ends of the film are usually deformed and cannot be used as film products, so they are cut out and reused as raw materials.

[0238] Next, in the film winding process, the film is wound while the shortest distance between the outer peripheral surface of the cylindrical wound film and the outer peripheral surface of the mobile transport roll immediately before this is kept constant. It is intended to be wound around. In front of the take-up roll, a means such as a static elimination blower for removing or reducing the surface potential of the film is provided.

[0239] The winder relating to the production of the optical film of the present invention is generally used, such as a constant tension method, a constant torque method, a taper tension method, a program tension control method with a constant internal stress, etc. It can be wound up by a winding method. It is preferable that the initial winding tension when winding the optical film is 90.2 to 30.8 N / m.

[0240] In the film winding step in the method of the present invention, the film is preferably wound under environmental conditions of a temperature of 20 to 30 ° C and a humidity of 20 to 60% RH. Thus, by specifying the temperature and humidity in the film winding process, the resistance to humidity change of the thickness direction retardation (Rt) is improved.

[0241] If the temperature in the winding step is less than 20 ° C, it will be unfavorable because it will cause scratches and will not be practically used due to deterioration in film winding quality. If the temperature and force in the film winding process exceeds 00 ° C, it is not preferable because it causes a crack and cannot be practically used due to deterioration in film winding quality. [0242] In addition, if the humidity in the film winding process is less than 20% RH, it is not preferable because the film winding quality is easily deteriorated and the film winding quality is not practical. If the humidity in the film winding process exceeds 60% RH, the winding quality, sticking failure, and transportability deteriorate, which is not preferable.

[0243] When winding the optical film into a roll, the winding core may be of any material as long as it is a cylindrical core, but is preferably a hollow plastic core and is made of plastic. The material may be any heat-resistant plastic that can withstand the heat treatment temperature, and examples thereof include resins such as phenol resin, xylene resin, melamine resin, polyester resin, and epoxy resin. A thermosetting resin reinforced with a filler such as glass fiber is preferred. For example, a hollow plastic core: a wound core made of FRP with an outer diameter of 6 inches (hereinafter, inch represents 2.54 cm) and an inner diameter of 5 inches is used.

[0244] The number of windings around these winding cores is preferably 100 windings or more, more preferably 500 windings or more, and the winding thickness is preferably 5 cm or more. The width is preferably 80 cm or more, particularly preferably lm or more.

[0245] The film thickness of the optical film according to the present invention varies depending on the intended use. In particular, the lower limit is 20 μm or more, preferably 35 μm or more. The upper limit is 150 111 or less, preferably 120 m or less. A particularly preferred range is 25 to 90 m. When the optical film of the present invention is a retardation film and also serves as a polarizing plate protective film, if the film is thick, the polarizing plate after polarizing plate processing becomes too thick, and the liquid crystal display used in the notebook type personal computer or mopile type electronic device. Is not particularly suitable for thin and lightweight purposes. On the other hand, if the film is thin, it will be difficult to develop retardation as a retardation film, and the moisture permeability of the film will be high, and the ability to protect the polarizer from humidity will be unfavorable.

[0246] When the slow axis or the fast axis of the retardation film exists in the film plane and the angle formed with the film forming direction is θ 1, θ 1 is 1;! To + 1 °, preferably 1 · 5 to + 0 · 5 °

[0247] This θ 1 can be defined as an orientation angle, and θ 1 can be measured using an automatic birefringence meter KOBRA-21AD Η (manufactured by Oji Scientific Instruments). [0248] Each of θ 1 satisfying the above relationship contributes to obtaining high luminance in a display image, suppressing or preventing light leakage, and contributing to faithful color reproduction in a color liquid crystal display device.

[0249] When the retardation film is used in the multi-domain VA mode, the retardation film is arranged in the above-mentioned region with the retardation film's fast axis as Θ1, thereby improving the display image quality. For example, when the MVA mode is used for the polarizing plate and the liquid crystal display device, the configuration shown in FIG. 7 can be taken.

[0250] Figure 7. The direction of the transmission axis of the polarizer, 26a and 26b are polarizing plates, 27 is a liquid crystal cell, and 29 is a liquid crystal display device.

[0251] The retardation Ro distribution in the in-plane direction of the cellulose ester film is preferably adjusted to 5% or less, more preferably 2% or less, and particularly preferably 1.5% or less. Further, it is preferable to adjust the retardation Rt distribution in the thickness direction of the film to 10% or less, more preferably 2% or less, and particularly preferably 1.5% or less.

[0252] When a polarizing plate including a retardation film is used in a liquid crystal display device in which a retardation film distribution fluctuation is preferably small in a retardation film, the retardation distribution fluctuation is small! /, This is preferable from the viewpoint of preventing color unevenness!

[0253] The retardation film is adjusted to have a retardation value suitable for improving the display quality of the VA mode or TN mode liquid crystal cell, and is divided into the above multi-domain as the VA mode, and the MVA mode is obtained. In order to be used preferably, it is required to adjust the in-plane retardation Ro to a value greater than 30 nm and 95 nm or less, and the thickness direction retardation Rt to a value greater than 70 nm and 400 nm or less.

[0254] The above in-plane retardation Ro is a method of the display surface when the two polarizing plates are arranged in crossed Nicols and the liquid crystal cell is arranged between the polarizing plates, for example, in the configuration shown in FIG. When observed in a crossed Nicol state relative to when observed from the line direction, when observed obliquely from the normal of the display surface, the polarizing plate deviates from the crossed Nicol state, and this causes light leakage, which is the main factor. To compensate. Retardation in the thickness direction is the above TN mode or VA mode. In particular, when the liquid crystal cell is in the black display state in the MVA mode, it contributes mainly to compensate for the birefringence of the liquid crystal cell that is also observed when viewed from an oblique direction.

[0255] As shown in Fig. 7, in the liquid crystal display device, when two polarizing plates are arranged above and below the liquid crystal cell, 22a and 22b in the figure represent the distribution of the thickness direction retardation Rt. It is preferable that the total value of both of the thickness direction retardation Rt is larger than 140 nm and 500 nm or less. In this case, the in-plane retardation Ro and the thickness direction retardation Rt of 22a and 22b are preferably the same for improving the productivity of the industrial polarizing plate. Particularly preferably, the in-plane retardation Ro is greater than 35 nm and less than or equal to 65 nm, and the thickness direction retardation Rt is greater than 90 nm and less than or equal to 180 nm, and is applied to an MVA mode liquid crystal cell with the configuration of FIG. is there.

[0256] In the liquid crystal display device, for example, as a commercially available polarizing plate protective film on one polarizing plate, in-plane retardation Ro = 0 to 4 nm and thickness direction retardation Rt = 20 to 50 nm and thickness 35 to 85 111 TAC film force For example, when it is used at the position 22b in FIG. 7, the polarizing film placed on the other polarizing plate, for example, the phase difference placed on 22a in FIG. Use of a film having a thickness direction retardation Rt greater than 140 nm and not greater than 95 nm and not greater than 140 nm and not greater than 400 nm is preferable from the viewpoint of improving the display quality and film production.

[0257] 《Recycling》

In the film forming process, the clip gripping portions at both ends of the cut film are pulverized or granulated as necessary, and then used as raw materials for the same type of film or for different types of film. It is preferable to reuse it as a raw material.

[0258] 《Functional layer》

In producing the optical film of the present invention, before and / or after stretching, an antistatic layer, a transparent conductive layer, a hard coat layer, an antireflection layer, an antifouling layer, a slippery layer, an easy adhesion layer, an antiglare layer, a gas Functional layers such as a noria layer and an optical compensation layer may be provided. In particular, it is preferable to provide at least one layer selected from an antistatic layer, a hard coat layer, an antireflection layer, an easy adhesion layer, an antiglare layer, and an optical compensation layer. At this time, corona discharge treatment, plasma treatment, chemical treatment, etc. Surface treatment can be applied as necessary.

[0259] 《Polarizing plate》

When using the optical film which concerns on this invention as a polarizing plate protective film, the preparation methods of a polarizing plate are not specifically limited, It can produce by a general method. The backside of the optical film of the present invention is subjected to alkali saponification treatment, and the treated optical film is immersed in an iodine solution and stretched on at least one surface of a polarizing film, and is completely saponified polybular alcohol. It is preferable to bond together using an aqueous solution. The optical film of the present invention may be used on the other side, or another polarizing plate protective film may be used. With respect to the optical film of the present invention, a commercially available cellulose ester film can be used as the polarizing plate protective film used on the other side. For example, commercially available cellulose ester films include KC8UX2M, KC4UX, KC5UX, KC4UY, KC8UY, KC12UR, KC8UCR-3, KC8UCR-4, KC4FR-1, KC8UY—HA, KC8UX—RHA (above, Konica Minoltobu Co., Ltd.) Etc. are preferably used. Alternatively, it is also preferable to use a polarizing plate protective film that also serves as an optical compensation film having an optically anisotropic layer formed by aligning liquid crystal compounds such as discotic liquid crystal, rod-shaped liquid crystal, and cholesteric liquid crystal. For example, the optically anisotropic layer can be formed by the method described in JP-A-2003-98348. By using it in combination with the optical film of the present invention, a polarizing plate having excellent flatness and a stable viewing angle expansion effect can be obtained. Alternatively, a film such as a cyclic olefin resin other than cellulose ester film, acrylic resin, polyester, polycarbonate, etc. may be used as a polarizing plate protective film on the other side.

[0260] Instead of the alkali treatment, it is described in JP-A-6-94915 and JP-A-6-118232! / .

[0261] A polarizing film, which is the main component of a polarizing plate, is an element that allows only light with a plane of polarization in a certain direction to pass through. A typical polarizing film that is currently known is a polybulualcohol-based polarizing film. There are two types: polybutalol-based films dyed with iodine and dichroic dyes. The polarizing film is formed by forming a polybulualcohol aqueous solution, uniaxially stretching it and dyeing it, and uniaxially stretching after dyeing, and preferably having been subjected to a durability treatment with a boron compound. Yes. The thickness of the polarizing film is 5-40 111, preferably It is 5-30 111, Most preferably, it is 5-20 111. On the surface of the polarizing film, one side of the cellulose ester film of the present invention is bonded to form a polarizing plate. Preferably, it is bonded with a water-based adhesive mainly composed of completely saponified polybulal alcohol.

Yes

[0262] Since the polarizing film is stretched in a uniaxial direction (usually the longitudinal direction), when the polarizing plate is placed in a high-temperature and high-humidity environment, the stretching direction (usually the longitudinal direction) shrinks, and the stretching and the perpendicular direction (usually normal Extends in the width direction). As the film thickness of the polarizing plate protective film becomes thinner, the expansion / contraction ratio of the polarizing plate increases, and in particular, the amount of contraction in the stretching direction of the polarizing film increases. Normally, the stretching direction of the polarizing film is bonded to the casting direction (MD direction) of the polarizing plate protective film. Therefore, when the polarizing plate protective film is thinned, the stretching rate in the casting direction can be suppressed. is important. Since the optical film of the present invention is extremely excellent in dimensional stability, it is preferably used as such a polarizing plate protective film.

[0263] That is, the optical film of the present invention may be a polarizing plate having an optical compensation film on the back surface side, in which wavy unevenness does not increase even by a durability test under conditions of 60 ° C and 90% RH. In addition, it is possible to provide good visibility without changing the viewing angle characteristics after the durability test.

[0264] The polarizing plate is composed of a polarizer and protective films for protecting both sides of the polarizer, and further comprises a protective film on one surface of the polarizing plate and a separate film on the other surface. I can do it. The protective film and separate film are used for the purpose of protecting the polarizing plate at the time of shipping the polarizing plate and at the time of product inspection. In this case, the protective film is bonded for the purpose of protecting the surface of the polarizing plate, and is used on the side opposite to the surface where the polarizing plate is bonded to the liquid crystal plate. The separate film is used for the purpose of covering the adhesive layer to be bonded to the liquid crystal plate, and is used on the surface side to bond the polarizing plate to the liquid crystal cell.

[0265] Liquid crystal display device

A polarizing plate including a polarizing plate protective film (including a case where it also serves as a retardation film) using the optical film of the present invention is high in comparison with a normal polarizing plate and can exhibit display quality. Suitable for use in a domain type liquid crystal display device, more preferably a multi-domain type liquid crystal display device by a birefringence mode. [0266] The polarizing plate of the present invention includes MVA (Multi-domein Vertical Alignment) mode, PV A (Patterned Vertical Alignment) mode, CPA (Continuous Pinwheel Alignment) mode, OCB (Optical Compensated Bend) mode, IPS (In Plane Switching mode, etc., and is not limited to a specific liquid crystal mode or the arrangement of polarizing plates.

[0267] Liquid crystal display devices are also being applied as devices for colorization and moving image display, and display quality has been improved by the present invention, and contrast has been improved and resistance to polarizing plates has been improved, resulting in less fatigue. A faithful moving image display becomes possible.

[0268] In the liquid crystal display device including at least the polarizing plate including the retardation film, one polarizing plate including the polarizing plate protective film as the optical film of the present invention is disposed with respect to the liquid crystal cell, or the liquid crystal Place two on each side of the cell. At this time, by using the polarizing plate protective film side included in the polarizing plate so as to face the liquid crystal cell of the liquid crystal display device, the display quality can be improved. In FIG. 7, the films 22a and 22b face the liquid crystal cell of the liquid crystal display device.

In such a configuration, the polarizing plate protective film as the optical film of the present invention can optically compensate the liquid crystal cell. When the polarizing plate of the present invention is used in a liquid crystal display device, at least one of the polarizing plates of the liquid crystal display device may be the polarizing plate of the present invention. By using the polarizing plate of the present invention, it is possible to provide a liquid crystal display device with improved display quality and excellent viewing angle characteristics.

[0270] In the polarizing plate of the present invention, a polarizing plate protective film of a cellulose derivative is used on the surface opposite to the polarizing plate protective film as the optical film of the present invention as viewed from the polarizer, and a general-purpose TAC film or the like is used. Can be used. The polarizing plate protective film located on the side far from the liquid crystal cell can be provided with another functional layer in order to improve the quality of the display device.

[0271] For example, a film containing a known functional layer as a display for the purpose of antireflection, antiglare, scratch resistance, dust adhesion prevention and luminance improvement, or the surface of the polarizing plate of the present invention This is not limited to these.

[0272] In general, the retardation film has little fluctuation in the above-mentioned retardation Ro or Rt! Are required to obtain stable optical characteristics. In particular, in a liquid crystal display device in a birefringence mode, these fluctuations may cause image unevenness.

[0273] The long polarizing plate protective film produced by the melt casting film formation method according to the present invention is mainly composed of a cellulose ester, and therefore, an alkali treatment step utilizing saponification inherent to cellulose ester. Can be utilized. This can be bonded to the polarizing plate protective film using a completely saponified polybulal alcohol aqueous solution in the same manner as a conventional polarizing plate protective film when the resin constituting the polarizer is polybulal alcohol. For this reason, the present invention is excellent in that a conventional polarizing plate processing method can be applied, and particularly in that a long roll polarizing plate can be obtained.

[0274] The production effect obtained by the present invention becomes more prominent particularly in a long roll of 100 m or more, and the longer the length is 1500 m, 2500 m, or 5000 m, the more the production effect of polarizing plate production is obtained.

[0275] For example, in the production of a polarizing plate protective film! /, The roll length is 10 to 5000 m, preferably 50 to 4500 m, considering the productivity and transportability. The width of the film at this time is The width of the polarizer and the width suitable for the production line can be selected. A film having a width of 0.5 to 4. Om, preferably 0.6 to 3. Om is manufactured, wound into a roll, and subjected to polarizing plate processing. After being manufactured and wound on a roll, it may be cut to obtain a roll having a desired width, and such a roll may be used for polarizing plate processing.

[0276] In the production of the polarizing plate protective film, functional layers such as an antistatic layer, a hard coat layer, a slippery layer, an adhesive layer, an antiglare layer, and a single layer of noble layer are applied before and / or after stretching. May be. At this time, various surface treatments such as corona discharge treatment, plasma treatment, and chemical treatment can be performed as necessary.

[0277] A cellulose ester film having a laminated structure can also be produced by coextruding compositions containing cellulose esters having different additive concentrations such as the above-mentioned plasticizer, ultraviolet absorber and matting agent. For example, a cellulose ester film having a structure of skin layer / core layer / skin layer can be produced. For example, the matting agent can be included in the skin layer more or only in the skin layer. Plasticizers and UV absorbers can be included in the core layer more than the skin layer, and may be included only in the core layer. Also, the core layer and skin layer are plasticizers, ultraviolet The type of the line absorber can also be changed. For example, the skin layer contains a low-volatile plasticizer and / or an ultraviolet absorber, and the core layer has an excellent plasticizer or an ultraviolet absorber. An ultraviolet absorber can also be added. The glass transition temperature of the core layer is preferably lower than the glass transition temperature of the skin layer, which may be different between the skin layer and the core layer. At this time, the glass transition temperatures of both the skin and the core are measured, and an average value calculated from these volume fractions is defined as the glass transition temperature Tg, which can be similarly obtained. In addition, the viscosity of the melt containing the cellulose ester during melt casting may be different between the skin layer and the core layer. The viscosity of the skin layer may be greater than the viscosity of the core layer or the viscosity of the core layer ≥ the viscosity of the skin layer. .

[0278] The cellulose ester film according to the present invention has a dimensional stability at a temperature of 80 ° C and 90% RH, based on the size of the film left for 24 hours at 23 ° C and 55% RH. The variation value is less than ± 2.0%, preferably less than 1.0%, and more preferably less than 0.5%.

[0279] When the cellulose ester film according to the present invention is used as a retardation film for a polarizing plate protective film, if the retardation film itself is within the above range, the absolute value of the retardation as a polarizing plate Since the initial setting of the value and the orientation angle does not deviate from each other, it is preferable because it does not cause a decrease in display quality improvement ability or a deterioration in display quality. Example

[0280] The present invention will be specifically described below with reference to examples, but the present invention is not limited thereto.

(Synthesis of cellulose ester 1)

80 g of acetic acid and 30 g of propionic acid were added to 30 g of cellulose (dissolved pulp manufactured by Nippon Paper Industries Co., Ltd.) and stirred at 54 ° C. for 30 minutes. After the mixture was cooled, esterification was carried out by adding 7 g of acetic anhydride, 120 g of propionic anhydride, and 1.2 g of sulfuric acid cooled in an ice bath. Stirring was carried out for 150 minutes while adjusting the esterification so that it did not exceed 40 ° C. After completion of the reaction, a mixture of 30 g of acetic acid and 10 g of water was added dropwise over 20 minutes to hydrolyze excess anhydride. While maintaining the temperature of the reaction solution at 40 ° C., 90 g of acetic acid and 30 g of water were added and stirred for 1 hour. The mixture was poured into an aqueous solution containing 2 g of magnesium acetate, stirred for a while, then filtered, washed thoroughly with water until the pH of the washing solution became neutral, and then dried to obtain cellulose ester 1. With respect to the obtained cellulose ester 1, the substitution degree (X) of the acetyl group and the substitution degree (Y) of the propionyl group were determined by the methods specified in the above-mentioned ASTM D817-96. = 1 · 23. Further, the number average molecular weight determined by gel permeation chromatography under the above-mentioned conditions is 66000. Furthermore, using a differential thermogravimetric analyzer, 1% mass reduction temperature Td (l. ) Was measured and found to be 292 ° C.

[0282] (Synthesis of cellulose ester 2 to 15)

For the synthesis of cellulose ester 1, the same synthesis operation as the synthesis of cellulose ester 1 was carried out except that the amounts used of acetic acid, acetic anhydride, propionic acid, and propionic anhydride were changed. Got.

[0283] For each of the cellulose esters 1 to 15, the degree of substitution of the acetyl group (X), the degree of substitution of the propionyl group (γ), the value of X + Y, the value of X—Y, the number average molecular weight (Mn), Table 1 shows the values of 1% mass loss temperature Td (l. 0).

[0284] (Synthesis of comparative cellulose esters 16-25)

Here, comparative cellulose esters 16 to 23 were synthesized in the same manner as cellulose ester 1 except that the amounts of acetic acid, acetic anhydride, propionic acid, and propionic anhydride were changed with respect to the synthesis of cellulose ester 1. Synthesized by performing the operation. On the other hand, the comparative cellulose esters 24 and 25 are the same as the synthesis of cellulose ester 1 except that a combination of acetic acid, acetic anhydride, butyric acid, and butyric anhydride was used, and the amounts used were further changed. The same synthesis operation was performed.

[0285] For each of the obtained comparative cellulose esters 16 to 25, the degree of substitution of the acetyl group (X), the degree of substitution of the propionyl group (Y), the value of X + Y, the value of X—Y or the butyryl group Table 1 shows the degree of substitution (Z), the value of X + Z, the value of X—Z, the number average molecular weight (Mn), and the value of 1% mass reduction temperature Td (1.0).

[0286] [Table 1] Cell CJ—ester ester substitution degree

Cell Ή—Sp Q Pionyl

Ester 'acetyl group conversion degree Y Χ + Υ x-y Remarks SO, group substitution degree X << petityl (χ-ί-ζ5 (Χ ~ Ζ)

Group substitution degree

1 1.31 1.23 2.54 0.08 66000 292 Present invention

2 1.3S 1.26 2.61 0.09 69000 293 The present invention

3 1.32 1.3ί 2.63 0.01 67000 300

4 1.35 1.3! 2.66 0.G4 80000 297 Main rope

5 1.39 1.3ί 2.70 0.Q8? 6000 294

6 t .41 1.32 2,73 0.09 70000 290 The present invention

7 1.38 1.30 2.68 0,08 74. 爾 302 The present invention

8 1.35 1.24 2.59 ο.η 74000 298 The present invention

1.32 1.18 2.50 0.14 86000 t The present invention

10 1.35 \.) 9 2,54 0,16 66000 2 0

11 1.25 1.15 2.40 0.10 91000 263 The present invention

12 1.34 1.15 2-49 0.19 62000 270 Invention

IS 1.28 1.33 2,6! -0.05 71000 275 The present invention

14 $ ί.31 2.74 0.12 68000 288 The present invention

15 1.34 ί.30 2.64 0.04 65000 2S1 The present invention

IS 1.90 0.80 2,70 1, 10 71000 273 Comparison 1? 1.SO ϊ U 2.6 0.39 65000 272 Comparison

18 1.40 1.35 2.7S 0,05 69000 272

19 1, 50 1.30 2.80 0.20 83000 261 Ratio 铰

20 1.40 1.15 2.55 Q.25 70000 274

b 1 Comparison

21 t, 25 1.35 2.60 -0.10 72000 2S0 ratio: 铰

22 t, 17 1.15 2.32 0.02 92000 255 Comparison

23 1.45 1.35 2.80 0.10 S3000 271 ratio 鲛

24 1, 40 (1.30) (2.70) (0.10)? 3000 260 comparison

25 1.20 (1-40) (2.60) ί-ΰ, 20) 68000 253 Comparison

[0287] Example 1

[Production of Optical Film Containing Cellulose Ester (hereinafter, simply referred to as Cellulose Ester Film) Sample 11]

As described below, the cell mouth ester film 1-1 of the present invention was produced by melt casting using the synthesized cellulose ester and various additives.

[0288] Cellulose ester 1 100 parts by mass

Plasticizer A 8 parts by mass

IRGANOX1010 (manufactured by Chinoku 'Specialty' Chemicals) 0 · 50 parts by mass GSY—P101 (manufactured by Sakai Chemical Industry) 0.25 parts by mass

SumilizerGS (Sumitomo Chemical Co., Ltd.) 0.25 parts by mass TINUVIN928 (manufactured by Chinoku 'Specialty' Chemicals) 1. 5 parts by weight Cellulose ester 1 was dried at 130 ° C for 4 hours under reduced pressure! / After cooling to room temperature, additives were mixed. The above mixture was melt-mixed at 230 ° C using a twin-screw extruder and pelletized. The pellets had a glass transition temperature Tg of 140 ° C.

[0289] The pellets were melted at 250 ° C in a nitrogen atmosphere and extruded from the casting die 4 onto the first cooling hole 5, and a film was formed between the first cooling roll 5 and the touch roll 6. Formed by pinching. Also, from the hopper opening in the middle of the extruder 1, silica particles as a slip agent, 0.22 parts by weight of Aerosil NAX50 (manufactured by Nippon Aerosil Co., Ltd.), and 0.02 mass of KE-P100 (manufactured by Nippon Shokubai Co., Ltd.) It added so that it might become a part.

[0290] The heat bolt was adjusted so that the gap width of the casting die 4 was 0.5 mm within 30 mm from the end in the width direction of the film, and lmm at other locations. As the touch roll, touch roll A was used, and 80 ° C water was poured into it as cooling water.

[0291] From the position P1 where the resin extruded from the casting die 4 contacts the first cooling roll 5 to the first cooling roll 5 of the first cooling roll 5 and the touch roll 6 at the upstream end position P2 The length L along the peripheral surface of the first cooling roller 5 was set to 20 mm. Thereafter, the touch roll 6 was separated from the first cooling roll 5, and the temperature T of the melted part immediately before being nipped between the first cooling roll 5 and the nipping roll 6 was measured. In this example, the temperature T of the melted part immediately before being sandwiched between the first cooling port 5 and the touch roll 6 is a position 1 mm upstream of the nip upstream end P2, and a thermometer It was measured by Keiki Co., Ltd. HA-200E). As a result of the measurement in this example, the temperature T was 141 ° C. The linear pressure of the touch roll 6 against the first cooling roll 5 was 14.7 N / cm. Furthermore, it was introduced into the tenter, stretched 1.3 times at 160 ° C in the width direction, cooled to 30 ° C while relaxing 3% in the width direction, then released from the clip, and the clip gripping part was cut off, Both ends of the film were knurled with a width of 10 mm and a height of 5 m, and wound on a core with a winding tension of 220 N / m and a taper of 40%. The extrusion amount and the take-up speed were adjusted so that the film had a thickness of 80 m, and the finished film width was slit and wound so that the width was 1430 mm. The winding core had an inner diameter of 152 mm, an outer diameter of 165 to 180 mm, and a length of 1550 mm. As this core material, glass fiber and carbon fiber impregnated with prepreg Resin was used. The core surface was coated with epoxy conductive resin, and the surface was polished to a surface roughness Ra of 0.3111. The roll length was 2500 m. This film original fabric sample of the present invention is referred to as cellulose ester film original fabric 1-1. Further, a part of the cellulose ester film is cut out from the original film sample, and this is designated as the cellulose ester film 1-1 of the present invention.

[0292] [Production of cellulose ester film 1-2 to 1-25]

In the production of the cellulose ester film original 1-1, except that the type of cellulose ester was changed as shown in Table 1, in the same manner, the cellulose ester film original 12- of the present invention; 15 and comparative cellulose ester film stock 116-125 were prepared. The amount of cellulose ester added in place of cellulose ester 1 used was the same mass part as cellulose ester 1. In addition, the cellulose ester film raw material of the present invention as described above 12! A part of cellulose ester film is cut out from 15 and comparative cellulose ester film stock 16-16-25, and each of them is cell mouth ester film 12- of the present invention; 1 and 15 for the comparison of the cell mouths, and the numbers are 16 to;

[0293] The structures of plasticizer A, IRGANOX1010, GSY-P101, SumilizerGS, and TINUVIN928 used in Example 1 are as follows. The cellulose esters;! To 23 are cellulose acetate propionate, and the cellulose esters 24 and 25 are cellulose acetate butyrate.

[0294] [Chemical 21]

GSY -P101

\

object

Sumili2erGS TINUVIN928

[0295] The obtained cellulose ester film original fabric sample and the cellulose ester film sample were evaluated by the following methods. The results are shown in Table 2.

[0296] 《Horse spine failure, core transfer》

Wrapped the cellulose ester film stock sample in a double layer with a polyethylene sheet and stored at 25 ° C and 50% under the conditions shown in Fig. 8 (a), (b) and (c). Stored for days. After that, take it out of the box, open the polyethylene sheet, light it on the surface of the original film sample, reflect the reflected fluorescent tube, and observe its distortion or fineness! / The following levels were used for evaluation of horse back failure.

[0297] ◎: The fluorescent lamp looks straight

△: Fluorescent light appears to be bent partially

X: Fluorescent lights appear to be reflected in mottle

In addition, when the original film sample after storage is rolled up, a core transfer that clearly shows a point-like deformation of 50 m or more or a band-like deformation in the width direction occurs up to how many meters from the core part! / Measured and ranked into the following levels.

[0298] ◎: Less than 15m from the core

〇: Less than 15-30m from the core

Δ: Less than 30-50m from the core

X: 50m or more from the core

《The beginning of winding》

The original film was wound around the core, and when it became defective due to the occurrence of a wrinkle at the beginning of the winding, the original film was removed from the core and then wound again. The number of defects at this time was counted. This work was averaged 10 times and ranked to the following levels.

[0299] (§): 0 times or more and less than 1 time

○: 1 or more and less than 3

△: 3 times or more and less than 5 times

X: 5 times or more

Cut each cellulose ester film sample into a size of 90cm in width and 100cm in length, and arrange 5 pieces of 50W fluorescent lamps, and fix the sample stand to a height of 1.5m so that it can be illuminated from a 45 ° angle. Each film sample was placed on a table, and the irregularities that appeared to be reflected on the film surface were visually observed and judged as follows. With this method, it is possible to judge “tsun” and “wrinkle”.

[0300] ◎: All five fluorescent lights looked straight

○: There is a place where the fluorescent light looks slightly bent △: The fluorescent light appears to be slightly bent as a whole

X: Fluorescent light appears to swell greatly

Cut out a 5 mm x 5 cm cellulose ester film sample, leave it in a constant temperature and humidity chamber at 28 ° C and 55% RH for 24 hours, place it on a flat plate, and use the curvature scale to have a curve that matches the sample The radius of curvature was determined, and the curl size and ease of handling were ranked as follows.

[0301] Curvature radius: 1 / radius of a circle with a curve that matches the sample (1 / m)

: 0 to less than 5

○: 5 to less than 10

Δ: Less than 10-30

X: 30 or more

Here, ◎ and ○ are easy to handle, but below △ are extremely difficult to handle.

[0302] 《Return coefficient of variation (CV)》

Retardation was measured at lcm intervals in the width direction of the cellulose ester film, and expressed by the coefficient of variation (CV) of the retardation obtained from the following formula. For measurement, an automatic birefringence meter KOBURA.21ADH (manufactured by Oji Scientific Instruments Co., Ltd.) was used, and the wavelength was 590 nm under an environment of 28 ° C and 55% RH. The dimensional double refractive index was measured and the measured value was substituted into the following equation.

[0303] In-plane retardance Ro = (nx-ny) X d

Thickness direction retardation Rt = ((nx + ny) / 2— nz) X d

Where d is the thickness of the film (nm), refractive index nx (the maximum refractive index in the plane of the film, also referred to as the refractive index in the slow axis direction), ny (the direction perpendicular to the slow axis in the film plane) Nz) (refractive index of the film in the thickness direction). The standard deviations obtained by the (n-1) method were respectively determined for the obtained in-plane and thickness direction retardations. For the retardation distribution, the coefficient of variation (CV) shown below was calculated and used as an index. In actual measurement, n was set to 130 to 140; [0304] Coefficient of variation (CV) = standard deviation / return average value

◎: Variation (CV) is less than 1.5%

○: Variation (CV) is 1.5% or more and less than 5%

Δ: Variation (CV) is 5% or more and less than 10%

X: Variation (CV) is 10% or more

《Saponification suitability》

A 120 μm-thick polybulal alcohol film is immersed in an aqueous solution containing 1 part by mass of iodine, 2 parts by mass of potassium iodide, and 4 parts by mass of boric acid, and stretched 4 times at 50 ° C to produce a polarizer. It was. The cellulose ester film sample was alkali-treated with a 2.5N sodium hydroxide aqueous solution at 40 ° C. for 60 seconds, further washed with water and dried to saponify the surface. The polarizing plate for evaluation was prepared by adhering the alkali-treated surface of the cellulose ester film on both surfaces of the polarizer from both sides using a completely saponified polybular alcohol 5% aqueous solution as an adhesive, and adhering a protective film.

Next, this polarizing plate for evaluation was treated at 80 ° C. and 90% RH for 1200 hours, and the state of bonding between the polarizer and the protective film was observed and ranked according to the following criteria.

[0306] A: No peeling

○: Slight peeling is observed, but there is no practical problem

Δ: Slightly peeled and practically problematic

X: Peeling occurred

Here, it was judged that ◯ or more was a practically satisfactory level in suitability for saponification treatment.

[0307] 《Polarizing plate durability test (whiteout)》

Longitudinal or lateral center line when two 500mm x 500mm polarizing plate samples prepared for the above saponification suitability evaluation are heat-treated (condition: left at 90 ° C for 120 hours) and placed in an orthogonal state The length of the white part of the larger edge was measured to calculate the ratio to the side length (500 mm), and the following determination was made according to the ratio. The white edge of the edge can be judged visually by the light passing through the edge of the polarizing plate that does not transmit light in an orthogonal state. In the state of the polarizing plate, the display of the edge portion becomes invisible.

[0308] ◎: White outline is less than 5% ◯: Edge blank is 5% or more and less than 10%

△: White edge of edge is 10% or more and less than 20%

X: White outline is 20% or more

Here, ○ and above were judged to be practically acceptable levels [Table 2]

[0310] From the results shown in Table 2, the cellulose ester film original samples 11 to 115 of the present invention are stored for a long period of time compared to the cellulose ester film original samples 1-16 to 1-25 of the comparative example. Even with this, it can be seen that this is a cellulose ester film that is less prone to deformation failures of the original film, such as a horse back failure and a winding start sheet with little core transfer. In addition, with respect to the cell mouth ester film itself cut out from the raw fabric, the cell mouth ester film of the present invention has a high flatness and suitability for saponification treatment, and has a curling property and a small change in retardation. It turns out that it is an ester film. Furthermore, it can be seen that the polarizing plate produced using the cellulose ester film of the present invention has good durability and is an optical film excellent in practical use.

[0311] Example 2

Except for changing to the combination of cellulose ester, plasticizer, anti-degradation agent and ultraviolet absorber listed in Table 3, the same procedure as in the original cellulose ester film 11 of Example 1 was used. Cellulose ester film original 2—;! To 2-18, and comparative cellulose ester film originals 2-19 and 2-20, and the cellulose ester film 11 of Example 1 were used in the same manner as in the present invention. Cellulose ester films 2—;! To 2-18 and comparative cellulose ester films 2-19 and 2-20 were prepared. Further, polarizing plates 2— ;! to 2-18 of the present invention and comparative polarizing plates 2-19 and 2-20 were produced in the same manner as the polarizing plate 11 of Example 1. In Table 3, the numerical values in parentheses in the columns of the plasticizer, the deterioration preventing agent, and the ultraviolet absorber represent the parts by mass of each material V and 100 parts by mass of the cellulose ester.

[0312] Plasticizer B, plasticizer C, plasticizer D, plasticizer E, plasticizer-F, plasticizer G, SumilizerGP (manufactured by Sumitomo Chemical Co., Ltd.), TINUVIN900 (Chinoku ') used in Example 2 The structures of Specialty Chemicals), Sumisorb250 (Sumitomo Chemical), and LA31 (ADEK A) are as follows.

[0313] [Table 3] ¾ []

Plasticizer I D

(Benzoic acid sucrose ester (react benzoic acid and sucrose,

1) A mixture composed mainly of a compound having the following structure

Plasticizer—Ε

Copolymer of methyl methacrylate, methyl acrylate, and 2-hydroxyalkylene methacrylate (composition ratio, weight average molecular weight see below) Composition ratio: p / q / r = 80/10/10 weight average molecular weight : 8,000

] Plasticizer Plasticizer I G

SumilizerGP

Four]

2007/070131

[0317] The same evaluation as in Example 1 was performed on the produced cellulose ester film, cellulose ester film, and polarizing plate. The results are shown in Table 4.

[0318] [Table 4]

[0319] From the results in Table 4, the cellulose ester film original fabric sample of the present invention 2 18 shows the deformation of the original film of the film, such as a winding start sheet with less horse back failure and less core transfer even when stored for a long period of time, compared to the cellulose ester film original samples 2-19 and 2-20 of the comparative example. It turns out that it is a cellulose-ester film which is hard to generate | occur | produce a failure. In addition, with respect to the cell mouth ester film itself cut out from the raw fabric, the cell mouth ester film of the present invention has a high flatness and suitability for saponification treatment, and has a curling property and a small change in retardation. It turns out that it is an ester film. Furthermore, it can be seen that the polarizing plate produced using the cellulose ester film of the present invention has good durability and is an optical film excellent in practical use. In addition, in the film original fabric sample 2-1, the film sample 2-1, and the polarizing plate sample 2-1, the same example is used, except that the exemplified compound (2) -8 is replaced by the same part by mass of the exemplified compound (2) -3. As a result of evaluation, the results were as good as those of each sample No. 2-1 in Table 4. As in the case of Sample No. 2-1, even when Exemplified Compound (2) -8 was replaced with Exemplified Compound (2) -45 having the same parts by mass as described above, good results were obtained. On the other hand, GSY-P 101 was mixed with the same part by weight of tetrakis (2,4-di-tert-butyl-phenyl) in film 2-5, film sample 2-5, and polarizing plate sample 2-5. ) 1, A'-Bifue Two Range Phosphonite was replaced with the same evaluation, and each sample No. 2-5 in Table 4 except that the evaluation result of white spots changed from ◎ to 〇 As well as good results. Furthermore, IRGANOX1010 is mixed with the same parts by weight of 1, 1, 1-trimethylolethane trisone in the original film sample 2-7, film sample 2-7, and polarizing plate sample 2-7 [3- (3 , 5-di-tert-butyl-4-hydroxyphenyl) propionate], the same evaluation was performed. As a result, each sample No. 2-7 in Table 4 showed good results. Example 3

The same procedure as in Example 1 was conducted except that the extrusion amount, the take-up speed, and the draw ratio were adjusted using a cellulose ester and various additives as described below so that the thickness force of the film was 0 μm. When the cellulose ester film raw fabric 3-1 of the present invention was prepared, the cellulose is less likely to cause deformation failure of the film original fabric such as a horse back failure, winding start sheet with less winding core transfer even if stored for a long period of time. It was a component that it was an ester film. In addition, when a cellulose ester film was cut out from the raw material and evaluated, the cellulose ester film had high flatness and suitability for saponification treatment, and curl and retardation fluctuations were small. It was found that the polarizing plate produced using the cellulose ester film had good durability and was an optical film excellent in practical use.

Cellulose ester 1 100 parts by mass

Plasticizer A 8 parts by mass

IRGANOX1010 (Chinoku 'Specialty' Chemicals) 0 · 50 parts by mass

GSY— P101 (manufactured by Sakai Chemical Industry Co., Ltd.) 0.25 parts by mass

Illustrative compound (2)-8 0. 30 parts by mass

TINUVIN928 (Chinoku 'Specialty' Chemicals) 2 · 25 parts by weight

Example 4

(Characteristic evaluation as a liquid crystal display device)

Remove the polarizing plate of the 32-inch TV AQ-32AD5 manufactured by Sharp Corporation, which is a VA-type liquid crystal display device, and remove each polarizing plate prepared in Examples;! To 3 (the cell port of the present invention prepared in Example 3). A polarizing plate 31 was prepared using the ester film 31 in the same manner as the polarizing plate 11. 1 was cut according to the size of the liquid crystal cell. The two polarizing plates produced as described above were pasted so that the polarizing axes of the polarizing plates were not perpendicular to each other so as to sandwich the liquid crystal cell, and a 32 type VA type color liquid crystal display was produced, and the cellulose ester film The properties of the polarizing plate were evaluated. As a result, the liquid crystal display device using the polarizing plate 1 of the present invention:! ~ 1 15, 2 — ;! ~ 2-18, 3-1 was a comparative polarizing plate 1 16. Compared with liquid crystal display devices using ˜125, 2-19, and 2-20, they exhibited excellent display properties with high contrast and no color unevenness. As a result, it was confirmed that it is excellent as a polarizing plate for an image display device such as a liquid crystal display.

Claims

The scope of the claims

[1] In an optical film obtained by heating and melting a film-forming material containing at least one plasticizer and a cellulose ester, and forming the film by a melt casting method, the type and degree of substitution of the cellulose ester are represented by the following formulae: An optical film formed by using a cellulose ester that simultaneously satisfies the conditions of (1) to (4).

Formula (1) 1. 25≤X≤1. 43

Formula (2) 1. 15≤Y≤1. 33

Equation (3) 2. 40≤Χ + Υ <2. 75

Formula (4) -0. 05≤Χ-Υ <0. 20

[2] The optical film according to [1], wherein the cellulose ester has a 1% mass reduction temperature Td (1.0) in the air of 270 ° C. or higher.

[3] The optical film according to [1] or [2], wherein the film-forming material further contains at least one phenol compound.

[4] The optical film according to any one of [1] to [3], wherein the film-forming material further contains at least one phosphorous compound.

[5] The optical film according to any one of claims 1 to 4, wherein the film-forming material further contains at least one alkyl radical scavenger.

[6] The film-forming material further contains at least one phenol-based compound, at least one phosphorus-based compound, and at least one alkyl radical scavenger. Item 3. The optical film according to Item 2.

[7] The optical film as described in [1], wherein the phenolic compound is a hindered phenolic compound.

8. The optical film according to any one of claims 4 to 7, wherein the phosphorus compound is a phosphonite compound.

9. The alkyl radical scavenger is a compound represented by the following general formula (1) or a compound represented by the following general formula (2): No! / 1. The optical film according to item 1.

[Chemical 1]

[Wherein R represents a hydrogen atom or an alkyl group having 1 to 10 carbon atoms;

1 2 3 each independently represents an alkyl group having! To 8 carbon atoms. ]

[Chemical 2]

'General formula << 2}

[Wherein R to R each independently represent a hydrogen atom or a substituent, and R represents water.

11 represents n, and when n is an integer of 2 to 4, R represents a divalent to tetravalent linking group. ]

11

[10] The optical film according to any one of [1] to [9], wherein the plasticizer is a polyhydric alcohol ester.

[11] The optical film as described in any one of [1] to [10], wherein the film-forming material further contains a benzotriazole-based compound.

[12] A polarizing plate comprising the optical film according to any one of claims 1 to 11 on at least one surface of a polarizer.

[13] A liquid crystal display device using the polarizing plate according to claim 12 on at least one surface of a liquid crystal cell.