KR101314030B1 - Optical film and polarizer and liquid-crystal display each employing the same - Google Patents

Abstract

SUMMARY OF THE INVENTION An object of the present invention is to use an optical film having a low variation in curling property and retardation while having high planarity and saponification ability without generating deformation failure such as a U-shaped failure or a convex failure. It is to provide a liquid crystal display device in which a durable polarizing plate and high contrast are achieved over a long period of time.

The optical film of this invention heat-melts the film forming material containing 1 or more types of plasticizers and a cellulose ester, and forms the film by the melt casting method, WHEREIN: The kind of substituents of the said cellulose ester, and its substitution degree are represented by the following mathematics It formed into a film using the cellulose ester which satisfy | fills the conditions of Formula 1-4 simultaneously.

&Quot; (1) "

1.25≤X≤1.43

&Quot; (2) "

1.15≤Y≤1.33

&Quot; (3) "

2.40≤X + Y <2.75

&Quot; (4) &quot;

-0.05≤X-Y <0.20

[X represents substitution degree by an acetyl group, Y represents substitution degree by propionyl group]

Optical film, polarizing plate, liquid crystal display device, cellulose ester, melt casting method

Description

Optical film, and polarizing plate and liquid crystal display using the same {OPTICAL FILM AND POLARIZER AND LIQUID-CRYSTAL DISPLAY EACH EMPLOYING THE SAME}

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

The optical film which has a cellulose ester (henceforth simply called a cellulose ester film) is used for the support of a negative film for photographs, or a liquid crystal display device from the viewpoint of its high transparency, low birefringence, and easily adhesiveness with a polarizer. As an optical film which protects the polarizer used, it has been used a lot in polarizing plates. Moreover, as another use with respect to a liquid crystal display device, it can use also in various functional films, such as a retardation film, a viewing angle expansion film, an antireflection film used for a plasma display, and also various functional films used for organic electroluminescent displays, etc.

Since the liquid crystal display device is thin and light in its thickness, the production volume has been greatly increased in recent years, and the demand is increasing. In addition, the TV using the liquid crystal display device has a feature of being thin and light, so that a large size TV which has not been achieved in a TV using the CRT has been produced. Accordingly, the demand for the polarizer and the polarizing plate protective film constituting the liquid crystal display device has increased. have. As a polarizing plate protective film, the cellulose ester film is generally used from the standpoint of the outstanding optical characteristic.

These cellulose ester films have been produced only by solution casting method until now. The solution casting method is a film forming method of a system in which a solution obtained by dissolving 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 the film formed by the solution casting method has high planarity, it is possible to obtain a high-definition liquid crystal display device without any unevenness by using the film.

However, the solution casting method requires a large amount of organic solvent, and a large environmental load also poses a problem. Since the cellulose ester film is formed into a film using the halogen-type solvent which has a large environmental load from the viewpoint of its dissolution characteristic, reduction of the amount of solvent used is especially required, and it is difficult to increase the cellulose ester film by solution casting film forming. have. For this reason, the film forming method which does not use an organic solvent, for example, heat-melting, is desired.

On the other hand, the cellulose ester film used as a protective film used for the polarizing plate of a liquid crystal display device has conventionally used the cellulose triacetate film frequently. The polarizing plate generally has the structure which laminated | stacked both the front and back sides of the polarizing film which consists of polyvinyl alcohol films etc. which adsorbed and oriented iodine or dye with the transparent resin layer, and the cellulose triacetate film has been used frequently as this transparent resin layer. However, in the case where cellulose triacetate, a cellulose ester generally used in solution casting, is to be applied to the melt film formation, the cellulose triacetate is a cellulose ester whose melting start temperature is higher than the decomposition start temperature. it's difficult.

In recent years, by replacing cellulose ester with not only an acetyl group but also a propionyl group or butyryl group in a specific ratio, for silver salt photographs (for example, see Patent Document 1 below) or for polarizing plate protective films (for example, Patent Document 2 below) , (3), attempts have been made to melt-deposit such cellulose esters. If the degree of substitution of the propionyl group or the butyryl group is high, the viscosity at the time of melting decreases, which is advantageous for melt film formation, while the mechanical strength of the film after film formation is poor, and both the silver salt photograph and the polarizing plate protective film do not function. It turned out to have On the other hand, when the degree of substitution of the propionyl group or the butyryl group is low, the mechanical strength is increased, while the viscosity at the time of melting increases, so that it is difficult to level even if it is extruded from the die and cast on the cooling drum or the cooling belt, resulting in uneven shape or pressure unevenness. This is easy to occur. As a result, it turned out that it has the subject that the planarity and curling property which are the physical characteristics of the film obtained are inferior, and the subject that the variation of retardation which is an optical characteristic is large is large.

It is known to add a specific deterioration inhibitor in melt-forming a cellulose ester (for example, refer following patent document 4). It is well known to add deterioration inhibitors to prevent deterioration of the chemical properties (coloring, molecular weight reduction) of the polymer material, but if the combination of the polymer material and the deterioration inhibitor is not appropriate, the adverse effect, that is, deterioration of the polymer material is rather challenging. to be. By the way, although there is no deterioration of a chemical characteristic, it can deteriorate an optical characteristic. In such a case, when cellulose ester is used for optical use, it is fatal, and it is a subject to select the suitable antideterioration agent suitable for it for a polymeric material. On the other hand, not only the stability at the time of melt-forming but also the stability after melt-forming is important for the cellulose ester to be melt-formed. In other words, it is important that there is no obstacle during the time of assembling any product using cellulose ester and the time when the product goes to the consumer and is using it. In the conventionally known technique, there is a problem in achieving long-term stability at the time of melt film formation and after melt film formation, and construction of a more advanced stabilization technology has been desired.

By the way, when manufacturing a polarizing plate by bonding a protective film and a polarizer, in order to make it easy to apply a water-soluble adhesive, the said triacetyl cellulose film is immersed in high-temperature, high concentration alkali liquid, and so-called saponification process makes a film surface hydrophilic, Then, an adhesive agent is applied and bonded to the polarizer.

In terms of easy adhesion with the polarizer, as the transparent resin film for the polarizing plate protective film, only triacetyl cellulose has been used, but is not yet replaced with another film, a polyester film, a polycarbonate film or a cyclic olefin resin There existed a reason that the other polymer films, such as a film, did not acquire adhesiveness with a polarizer even if it saponified.

Attempts have been made to improve various performances of cellulose ester films by defining the degree of substitution of fatty acids such as acyl groups of cellulose esters, for example, acetyl, propionyl or butyryl groups (for example, Patent Document 5 below). Reference). The cellulose ester film substituted with a specific ratio of propionyl group or butyryl group as well as the acetyl group is easily adhesive as compared with polymer films other than cellulose ester, but if the degree of substitution of propionyl group or butyryl group is too high, saponification treatment It did not progress well, and as a result, it turned out that it has a subject with inferior adhesiveness, and is inadequate also about a mechanical characteristic and an optical characteristic. In particular, when comparing the propionyl group and the butyryl group, it was found that although the carbon number is only one difference, the mechanical and optical properties are greatly deteriorated by the bonding of the butyryl group.

Therefore, instead of the triacetyl cellulose film formed by the solution casting method, it has excellent environmental aptitude, high planarity and saponification treatment aptitude, small curling and retardation variation, and furthermore, excellent durability for a long time. The appearance of an optical film is expected.

By the way, these cellulose ester films are normally wound up to the core and become a film disk, and are preserve | saved and transported. For this reason, when the film melt-formed is preserve | saved for a long time in the film disk state wound around the core, the film | membrane in a U-shaped malfunction or the core part of a film disk tends to generate | occur | produce wrinkles in a film called a core transfer and the start of winding. It turns out that there is a problem.

U-shaped failure is a failure in which the film disk is deformed into a U-shape and a strip-shaped convex part is formed at a pitch of about 2 to 3 cm near the center part, and deformation is left in the film. This is a problem because it looks crooked. Until now, U-shaped failures have been reduced by lowering the coefficient of kinetic friction between the bases or by adjusting the heights of the knurling (embossing) on both sides.

In addition, the core transfer is a failure due to the deformation of the film due to the core and the unevenness of the film.

In the film produced by the conventional solution casting, these failures did not become a big problem, but in the film manufactured by melt film forming, it turned out that it is a big problem because the planarity of a film is low.

In particular, in recent years, it is desired to increase the width of the film disk and lengthen the winding length according to the large screen. For this reason, the film disk has a wider width, the film disk load tends to increase, and improvement is desired because of the situation in which these failures are more likely to occur.

Patent Document 1: Japanese Patent Publication No. 6-501040

Patent Document 2: Japanese Patent Application 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 Patent Application Laid-Open No. 2006-111842

<Start of invention>

[PROBLEMS TO BE SOLVED BY THE INVENTION]

The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a melt-filmed optical film having excellent environmental aptitude, good mechanical properties, and optical properties, and excellent durability, and specifically, a film such as a U-shaped failure or a convex failure. An optical film that does not cause deformation failure of the disc, an optical film having high planarity and saponification ability, and small curling and retardation fluctuation, and a polarizing plate and a high contrast with good durability for a long time using this optical film It is to provide the achieved liquid crystal display device.

MEANS FOR SOLVING THE PROBLEMS [

MEANS TO SOLVE THE PROBLEM As a result of earnestly examining in order to solve the said subject, the present inventors discovered that all the subjects can be solved by using the film melt-molded by the cellulose ester which has the kind and quantity of a certain substituent, and came to complete this invention. .

That is, the said subject of this invention is achieved by the following structures.

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 a film by a melt casting method, the type and the degree of substitution of the substituents of the cellulose ester are represented by the following formulas (1) to (4). It formed into a film using the cellulose ester which simultaneously satisfy | fills the conditions of the optical film characterized by the above-mentioned.

1.25≤X≤1.43

1.15≤Y≤1.33

2.40≤X + Y <2.75

-0.05≤X-Y <0.20

[Wherein X represents a degree of substitution by an acetyl group, and Y represents a degree of substitution by a propionyl group]

2. The 1% mass reduction temperature Td (1.0) in the air of the said cellulose ester is 270 degreeC or more, The said optical film of 1 characterized by the above-mentioned.

3. Said film formation material contains 1 or more types of phenolic compound further, The said 1 or 2 optical film characterized by the above-mentioned.

4. Said film formation material contains 1 or more types of phosphorus compound further, The optical film in any one of said 1-3 characterized by the above-mentioned.

5. Said film formation material contains 1 or more types of alkyl radical scavengers further, The optical film in any one of said 1-4 characterized by the above-mentioned.

6. Said film formation material contains 1 or more types of phenolic compounds, 1 or more types of phosphorus compounds, and 1 or more types of alkyl radical trapping agents, The said optical film of 1 or 2 characterized by the above-mentioned.

7. Said phenolic compound is hindered phenolic compound, The optical film in any one of said 3-6 characterized by the above-mentioned.

8. Said phosphorus compound is phosphonite type compound, The optical film in any one of said 4-7 characterized by the above-mentioned.

9. Said alkyl radical capture agent is a compound represented by following formula (1), or a compound represented by following formula (2), The optical film in any one of said 5-8 characterized by the above-mentioned.

[Wherein, R ₁ represents a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, and R ₂ and R ₃ each independently represent an alkyl group having 1 to 8 carbon atoms]

[Wherein, R ₁₂ to R ₁₅ each independently represent a hydrogen atom or a substituent, R ₁₆ represents a hydrogen atom or a substituent, n represents an integer of 1 to 4, and when n is 1, R ₁₁ is When n is an integer of 2 to 4, R ₁₁ represents a 2 to tetravalent linking group.]

10. Said plasticizer is polyhydric alcohol ester, The optical film in any one of said 1-9 characterized by the above-mentioned.

11. Said film formation material contains benzotriazole type compound further, The optical film in any one of said 1-10 characterized by the above-mentioned.

12. The optical film according to any one of 1 to 11 above is provided on at least one surface of the polarizer.

13. The polarizing plate of said 12 is used for at least one surface of a liquid crystal cell, The liquid crystal display device characterized by the above-mentioned.

EFFECTS OF THE INVENTION [

INDUSTRIAL APPLICABILITY According to the present invention, an optical film having no deformation failure of a film disc such as a U-shaped failure or a convex failure, an optical film having a small variation in curling property and retardation while having high planarity and saponification treatment aptitude, and this optical film It is possible to provide a liquid crystal display device in which a durable polarizing plate and high contrast are achieved over a long period of time.

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic flow sheet which shows one Embodiment of the apparatus which implements the manufacturing method of the cellulose ester film which concerns on this invention.

FIG. 2 is an enlarged flow sheet of the main part of the manufacturing apparatus of FIG. 1. FIG.

Fig. 3 (a) is an external view of the main part of the flexible die, and Fig. 3 (b) is a sectional view of the main part of the flexible die.

It is sectional drawing of 1st Embodiment of a pinching rotary body.

It is sectional drawing in the plane perpendicular | vertical to the rotating shaft of 2nd Embodiment of a pinching rotary body.

It is sectional drawing in the plane containing the rotating shaft of 2nd Embodiment of a pinching rotary body.

7 is an exploded perspective view illustrating an outline of a configuration diagram of a liquid crystal display device.

It is a figure which shows the storage state of the cellulose-ester film disk.

Explanation of symbols

1: extruder

2: Filter

3: static mixer

4: flexible die

5: rotating support (first cooling roll)

6: pinching rotary body (touch roll)

7: rotating support (second cooling roll)

8: rotating support (third cooling roll)

9, 11, 13, 14, 15: conveying roll

10: cellulose acylate film

12: drawing machine

16: winding device

21a, 21b: protective film

22a, 22b: retardation film

23a, 23b: slow axis direction of film

24a, 24b: transmission axis direction of polarizer

25a, 25b: polarizer

26a, 26b: polarizing plate

27: liquid crystal cell

29: liquid crystal display device

31: die body

32: slit

41: metal sleeve

42: elastic roller

43: metal inner cylinder

44: rubber

45: coolant

51: outer cylinder

52: inner tube

53: space

54: coolant

55a, 55b: axis of rotation

56a, 56b: outer cylinder support flange

60: fluid cylinder

61a, 61b: inner cylinder support flange

62a, 62b: intermediate passage

110: core body

117: support plate

118: trestle

120: cellulose ester film disc

BEST MODE FOR CARRYING OUT THE INVENTION [

Best Mode for Carrying Out the Invention Hereinafter, the best mode for carrying out the present invention will be described in detail, but the present invention is not limited thereto.

The present invention is to obtain an optical film having good mechanical characteristics and optical characteristics and good durability. By using such an optical film, optical films, such as a high-quality polarizing plate protective film, an antireflection film, and a retardation film, can be obtained, and also the liquid crystal display device with high display quality can be obtained.

This invention uses the cellulose ester film formed by melt casting as an optical film, It is characterized by the above-mentioned. In this invention, what melt | dissolves in the state which can flow by heating the said film forming material, without dissolving a film forming material in a solvent like solution casting, is defined as melt casting method.

The shaping | molding method which heat-melts can be classified in more detail into the melt extrusion molding method, the press molding method, the inflation method, the injection molding method, the blow molding method, the extending molding method, etc. Among them, the melt extrusion method is excellent in order to obtain an optical film having excellent mechanical strength, surface precision and the like.

Here, the film forming material is heated to express its fluidity, and a method of extrusion film forming on a drum or an endless belt is included in the melt casting method of the present invention as a melt casting film forming method.

And the optical film of this invention heat-melts the film forming material containing 1 or more types of plasticizers and the following cellulose ester, Preferably it melts at 200 degreeC or more and 270 degrees C or less, and the optical film formed by the melt casting method It is a feature.

Hereinafter, each film forming material is demonstrated.

<< cellulose ester >>

The cellulose ester used for the melt casting method of the present invention is a cellulose ester which satisfies the following formulas 1 to 4 simultaneously when the degree of substitution of the acetyl group is X and the degree of substitution of the propionyl group is Y. Such cellulose esters are commonly called cellulose acetate propionate. In addition, it is important to satisfy all four at the same time without satisfying any of the above problems only by satisfying any one, any two, or any three of the following equations.

&Quot; (1) &quot;

1.25≤X≤1.43

&Quot; (2) &quot;

1.15≤Y≤1.33

&Quot; (3) &quot;

2.40≤X + Y <2.75

&Quot; (4) &quot;

-0.05≤X-Y <0.20

Among them, it is preferable to set 1.30 ≦ X ≦ 1.42 for the equation (1), 1.18 ≦ Y ≦ 1.32 for the equation (2), and 2.50 ≦ X + Y ≦ 2.73 for the equation (3). It is preferable to set it to 0.01≤XY≤0.18 with respect to equation (4).

Next, the substitution degree of the acyl group (acetyl group and propionyl group) of the cellulose ester used for this invention is demonstrated in detail.

The cellulose has three hydroxyl groups in total, one each at the 2-position, the 3-position, and the 6-position of 1 glucose unit, and the total degree of substitution is a numerical value indicating how many acyl groups are bonded to 1 glucose unit on average. Therefore, the maximum substitution degree is 3.00 and the part which is not substituted by the said acyl group exists normally as a hydroxyl group. In addition, positions 2 and 3 are secondary hydroxyl groups, and positions 6 are primary hydroxyl groups, and the higher order structure or physical properties of the cellulose ester may change slightly depending on which position the acetyl group and propionyl group are substituted in each proportion. have. However, in the optical film of the present invention, any of the substitution positions and ratios of the acetyl group and the propionyl group may be preferably used as long as the cellulose ester satisfies the conditions of the above formulas (1) to (4). In addition, substitution degree of an acetyl group and a propionyl group is calculated | required by the method prescribed | regulated to ASTMD817-96.

The cellulose ester used in the present invention preferably has a number average molecular weight (Mn) of 50000 to 150000, more preferably a number average molecular weight of 55000 to 120000, and most preferably a number average molecular weight of 60000 to 100000. It is right.

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 to 5.0, and more preferably 1.7 to 4.0. More preferably, the cellulose ester of 2.0-3.5 is used preferably.

In addition, Mn and Mw / Mn can be computed by gel permeation chromatography (GPC) by the following method.

Measurement conditions are as follows.

Solvent: tetrahydrofuran

Apparatus: HLC-8220 (manufactured by Tosoh Corporation)

Column: TSK Gel Super HM-M (manufactured by Tosoh Corporation)

Column temperature: 40 ° C

Sample concentration: 0.1% by mass

Injection volume: 10 μl

Flow rate: 0.6 ml / min

Calibration curve: Standard polystyrene: PS-1 (manufactured by Polymer Laboratories) Mw = a calibration curve with nine samples from 2,560,000 to 580 was used.

The cellulose ester in the film forming material is in the range of 70% by mass to 99% by mass, thereby exhibiting excellent melt flexibility and stability in the presence of additives such as a deterioration inhibitor, a plasticizer, and an ultraviolet absorber described later, and the resulting film is used as an optical film. Excellent performance can be given. When content of a cellulose ester is 70 mass% or less, since an additive bleeds out or the mechanical strength of a film becomes small, it is not preferable. Moreover, if the addition amount of the other additive required as an optical film is 1.0 mass% or less (if content of a cellulose ester is 99% or more), it is difficult to satisfy | fill the requested physical property. More preferably, content of a cellulose ester is 80-95 mass%.

The raw cellulose of the cellulose ester used in the present invention may be wood pulp or cotton linter, and the wood pulp may be coniferous or hardwood, but conifers are more preferred. A cotton linter is preferably used in terms of peeling property at the time of film formation. The cellulose esters made from these can be mixed as appropriate or used alone.

For example, the ratio of cellulose ester derived from cotton linter: cellulose ester derived from wood pulp (softwood): cellulose ester derived from wood pulp (softwood) 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, and 40:30:30.

The cellulose ester of the present invention can be synthesized with reference to a known method. For example, the hydroxyl group of a raw material cellulose can be acetylated and propionylated by a conventional method using acetic anhydride and propionic anhydride, and an acetyl group and a propionyl group can be substituted. Although the synthesis | combining method of such a cellulose ester does not have limitation in particular, For example, it can synthesize | combine with reference to the method of Unexamined-Japanese-Patent No. 10-45804 or Unexamined-Japanese-Patent No. 6-501040. Moreover, the cellulose ester which satisfy | fills said Formula (1)-4 simultaneously can be synthesize | combined by suitably changing the usage-amount of acetic anhydride and propionic anhydride used.

The alkaline earth metal content of the cellulose ester used in the present invention is preferably in the range of 1 to 50 ppm. When it exceeds 50 ppm, lip adhesion contamination increases or breaks easily in the slitting portion during or after thermal stretching. Although it is easy to break even below 1 ppm, the reason is not well known. Moreover, the range of 1-30 ppm is preferable. An alkaline earth metal here means total content of Ca and Mg, and can measure it using an X-ray photoelectron spectroscopy (XPS).

The residual sulfuric acid content in the cellulose ester used in the present invention is preferably in the range of 0.1 to 45 ppm in terms of elemental sulfur. They are thought to be contained in salt form. If the residual sulfuric acid content exceeds 45 ppm, since the deposit of the die lip portion at the time of hot melting increases, it is not preferable. Moreover, since it becomes easy to fracture at the time of thermal stretching or the slitting after thermal stretching, it is not preferable. Although less is preferable, when it is less than 0.1, it may become easy to break on the contrary, but it is not preferable, but the reason is not well known. Moreover, the range of 1-30 ppm is preferable. The residual sulfuric acid content can be measured by the method specified in ASTM D817-96.

It is preferable that the free acid content in the cellulose ester used for this invention is 1-500 ppm. If it exceeds 500 ppm, deposits on the die lip portion increase and breakage becomes easy. It is more preferable that it is in the range of 1 to 100 ppm, and it will not break more easily. In particular, the range of 1-70 ppm is preferable. The free acid content can be measured by the method specified in ASTM D817-96.

Since the washing | cleaning of the synthesized cellulose ester is performed more fully compared with the case used for the solution casting method, residual alkaline-earth metal content, residual sulfuric acid content, and residual acid content can be made into the said range, and it is preferable. In addition, the cellulose ester can be washed with a poor solvent such as methanol or ethanol, or consequently a poor solvent and a mixed solvent of a poor solvent and a good solvent in addition to water, and can remove inorganic impurities other than residual acid and low molecular weight organic impurities. Can be. Moreover, washing | cleaning of a cellulose ester is also performed in presence of a degradation inhibitor, and the heat resistance and film forming stability of a cellulose ester improve. The deterioration inhibitor to be used can be used without limitation so long as it is a compound which inactivates radicals generated in the cellulose ester or inhibits deterioration of the cellulose ester resulting from the addition of oxygen to the radicals generated in the cellulose ester.

In order to improve the heat resistance, mechanical properties, optical properties, and the like of the cellulose ester, the cellulose ester is dissolved in a good solvent of the cellulose ester, and then reprecipitated and filtered in the poor solvent, or stirred and suspended in the poor solvent and filtered. Low molecular weight components and other impurities can be removed. At this time, it is preferable to carry out in presence of a deterioration inhibitor similarly to washing of the cellulose ester mentioned above.

The deterioration inhibitor used for washing the cellulose ester may remain in the cellulose ester after washing. The remaining amount is preferably 0.01 to 2000 ppm, more preferably 0.05 to 1000 ppm. More preferably, it is 0.1-100 ppm.

In addition, other polymers or low molecular weight compounds may be added after the reprecipitation treatment of the cellulose ester.

Moreover, it is preferable that the cellulose ester used by this invention has few bright point foreign substances when it is set as a film. When a bright point foreign substance is arrange | positioned two polarizing plates orthogonally (cross nicol), arrange | positions a cellulose ester film between them, irradiates the light of a light source from one side, and observes a cellulose ester film from the other side, The light leaks out. At this time, it is preferable that the polarizing plate used for the evaluation is composed of a protective film free from foreign matters with a bright spot, and a glass plate is preferably used for protecting the polarizer. The bright point foreign matter is considered to be one of the causes of the microacetization or low acetylated cellulose contained in the cellulose ester, and the use of a cellulose ester having a small amount of the bright point foreign matter (using a cellulose ester with a low dispersion of substitution degree) and melting In at least one of filtering a cellulose ester, a process of late synthesis | combination of a cellulose ester, or a process of obtaining a precipitate, it can also be made into a solution state, and similarly removes a bright point foreign material via a filtration process. Since the molten cellulose ester has a high viscosity, the latter method is more efficient.

The thinner the film thickness, the smaller the number of bright spot foreign matters per unit area, and the smaller the content of cellulose ester contained in the film, the lower the bright spot foreign matters, but the bright spot foreign matters have 200 or more diameters of 0.01 mm or more. / cm ² or less is preferable, and 100 / cm ² or less is more preferable, and 50 / cm ² or less is more preferable, and 30 / cm ² is further more preferably not more than, and 10 / cm ² or less is more Although preferred, none is most preferred. Moreover, it is preferable that it is 200 pieces / cm <^2> or less also about the bright spot of 0.005-0.01 mm or less, It is more preferable that it is 100 pieces / cm <^2> or less, It is still more preferable that it is 50 pieces / cm <^2> or less, It is 30 pieces / cm <^2> or less It is more preferable, and it is more preferable that it is 10 pieces / cm <^2> or less, but nothing is most preferable.

In the case where the bright spot foreign matter is removed by melt filtration, it is preferable to filter the cellulose ester composition to which the deterioration inhibitor, the plasticizer and the like is added and mixed rather than to filter the melted cellulose ester alone. Of course, it can also be dissolved by a solvent in the synthesis of cellulose esters and reduced by filtration. What mixed suitably also a ultraviolet absorber and other additives can be filtered. As for filtration, the viscosity of the melt containing cellulose ester is preferably filtered at 10000 Pa · s or less, more preferably 5000 Pa · s or less, still more preferably 1000 Pa · s or less, and further 500 Pa · s or less More preferred. As a filter medium, although conventionally well-known things, such as fluororesins, such as glass fiber, a cellulose fiber, a filter paper, and tetrafluoroethylene resin, are used preferably, especially a ceramic, a metal, etc. are used preferably. As absolute filtration precision, 50 micrometers or less are used preferably, 30 micrometers or less are more preferable, 10 micrometers or less are more preferable, 5 micrometers or less are used more preferably. These can also be used combining them suitably. The filter medium may be used as a surface type or a depth type, but the depth type is preferably used because it is relatively unobstructed.

In another embodiment, the cellulose ester of a raw material may be dissolved at least once in a solvent, and the cellulose ester which dried the solvent may be used. At this time, after dissolving in a solvent with at least 1 or more of a degradation inhibitor, a plasticizer, a ultraviolet absorber, and a mat agent, the dried cellulose ester is used. As a solvent, a good solvent used by solution casting method, such as methylene chloride, methyl acetate, dioxolane, etc. can be used, and poor solvents, such as methanol, ethanol, butanol, can also be used. In the dissolution process, it may be cooled to −20 ° C. or lower, or may be heated to 80 ° C. or higher. When such a cellulose ester is used, each additive at the time of being melted can be made uniform, and optical characteristic can be made uniform.

The optical film of the present invention may be a mixture of polymer components other than cellulose esters as appropriate. The polymer component to be mixed is preferably excellent in compatibility with the cellulose ester, and it is preferable that the transmittance when formed into a film is 80% or more, more preferably 90% or more, further preferably 92% or more.

Since the cellulose ester of the present invention is used for melt film formation, it is necessary that the cellulose ester itself be stable from heating melting to film formation. However, the inventors of the present invention not only provide stability at the time of melt film formation, but also provide With regard to the mechanical properties, the optical properties, and the durability, it was found to be related to the 1% mass reduction temperature Td (1.0) under air of the cellulose ester before heat melting. In addition, while it is possible to solve the above problems as long as cellulose esters satisfying the above Equations 1 to 4 according to the present invention can be solved, Td (1.0) is preferable for solving the higher problem, and Td (1.0). Silver is more preferably at least 270 ° C, still more preferably at least 280 ° C, and most preferably at least 290 ° C. In order to raise Td (1.0) of a cellulose ester, in the operation | movement which filters and washes the cellulose ester at the time of last extraction in the synthesis | combination of a cellulose ester, it can improve by wash | cleaning with water sufficiently until pH of a washing | cleaning liquid becomes neutral. . By the way, although the detailed reason is not well known, depending on the kind of cellulose ester, when the washing | cleaning is performed excessively, the mechanical characteristics, such as being easy to break, may deteriorate, but the said Formulas 1-4 concerning this invention are simultaneously As for the cellulose ester to be satisfied, it was found that the deterioration of the mechanical properties caused by the washing did not occur. In addition, although the 1% mass reduction temperature Td (1.0) under air can be measured by a commercially available differential thermogravimetric analysis (TG-DTA) apparatus, in general, since the cellulose ester contains a small amount but contains water, Needs attention. Specifically, the sample is held at 100 ° C. for a while, and after confirming that there is no loss of mass due to volatilization of water, a method of measuring mass loss with temperature rise from that point is taken. By the way, although there is no upper limit in Td (1.0) and it is assumed that it is so preferable that it is high, a realistic upper limit is about 300-310 degreeC considering that avoiding the burden of the washing process of a cellulose ester becoming large.

The cellulose ester of the present invention can further improve stability upon heating by combining with a deterioration inhibitor, but surprisingly, the combination of the cellulose ester with a deterioration inhibitor described below prevents deformation failures of film discs such as U-shaped and convex failures. It turned out that the cellulose ester film which is excellent in any of planarity, saponification process suitability, curling property, the retardation variability, and durability is obtained.

<< deterioration inhibitor >>

The deterioration inhibitor refers to a material that inhibits the decomposition of a polymer by heat, oxygen, moisture, acid, or the like by chemical action. Since the optical film of this invention is shape | molded especially at the high temperature 200 degreeC or more especially, it is a system in which decomposition | disassembly and deterioration of a polymer are easy to occur, and it is preferable to contain a degradation inhibitor in a film formation material.

Deterioration or materials typified by coloration or molecular weight reduction, including decomposition reactions that are not elucidated, such as prevention of oxidation of film forming materials, capture of acids generated by decomposition, and inhibition or inhibition of decomposition reactions due to radical species due to light or heat. In order to suppress generation | occurrence | production of the volatile component by the decomposition | disassembly of the deterioration inhibitor, it uses.

Examples of the deterioration inhibitor include antioxidants, hindered amine light stabilizers, acid trapping agents, metal deactivators, and the like, but are not limited thereto. These are Japanese Patent Laid-Open No. 3-199201, Japanese Patent Laid-Open No. 5-1907073, Japanese Patent Laid-Open No. 5-194789, Japanese Patent Laid-Open No. 5-271471, Japan Japanese Patent Application Laid-Open No. Hei 6-107854 and the like. Among these, for the purpose of this invention, it is preferable to contain antioxidant as a deterioration inhibitor in a film formation material.

At least 1 type or more of antideterioration agents in the film formation material used for this invention can be selected, The addition amount of the deterioration inhibitor with respect to the mass of the cellulose ester which concerns on this invention is preferably 0.01 mass% or more and 10 mass% or less, More preferably, they are 0.1 mass% or more and 5.0 mass% or less, More preferably, they are 0.2 mass% or more and 2.0 mass% or less.

Moreover, when the addition amount of a deterioration inhibitor is more than the range of the said addition amount, it is unpreferable since it may cause the fall of transparency as an optical film in terms of compatibility with a cellulose ester, and also may weaken a film.

A film forming material can be divided | segmented and preserve | saved into the 1 type or multiple types of pellets in order to avoid the deterioration of a material, and hygroscopicity. Pelletization can improve the mixing property or compatibility of the melt at the time of heating, or can secure the optical uniformity of the obtained film.

When heat-melting the film forming material, and when using the heat-melted in a subsequent process, and also when used under the consumer as a product, the presence of the above-described deterioration inhibitors may indicate the deterioration of strength or optical transparency based on material degradation or degradation. It is excellent in terms of reducing or maintaining the inherent strength of the material.

If the film forming material is significantly degraded by heating, coloration may occur and it may become unusable as an optical film. In addition, when using as an optical compensation film for liquid crystal display devices, although the retardation provision process (stretching process) is performed after a casting | flow_spread process, when the film forming material deteriorates remarkably by heating, the formed film will become weak and it will break at the said extending process. This may easily occur or may not be able to express the retardation value of the desired optical compensation film. Moreover, when using as a polarizing plate protective film for liquid crystal display devices, since deterioration of a film formation material may cause trouble to bonding with a polarizer, it is not preferable.

Therefore, the presence of the above-described deterioration inhibitor suppresses the formation of colored substances in the visible region at the time of heat melting, or transmittance and haze caused by volatile components generated by decomposition of the material constituting the film at the time of heat melting and heat melting. It is also excellent in the point which can suppress or eliminate undesirable deterioration as an optical film like a value fall.

In this invention, since the display image of a liquid crystal display device affects when a haze value exceeds 1%, when using the optical film of this invention, haze value is less than 1%, More preferably, it is less than 0.5%. . In addition, yellowness (yellow index, YI) can be used as an index of colorability, Preferably it is 3.0 or less, More preferably, it is 1.0 or less. Yellowness can be measured based on JIS-K7103.

In the above-mentioned preservation or film forming process of the film forming material, deterioration reaction due to oxygen or moisture in the air may coexist. In this case, reducing the humidity and oxygen concentration in the air together with the stabilizing action of the deterioration inhibitor can be preferably used in combination with the present invention. This includes the use of nitrogen or argon as an inert gas, a degassing operation under reduced pressure or vacuum, and an operation under a closed environment as a known technique, and one or more of these three methods may be used in the presence of the stabilizer and It can be used together. It is preferable because the deterioration of the material can be suppressed by reducing the probability that the film forming material is in contact with oxygen in the air.

In addition, since the optical film of this invention is utilized also as a polarizing plate protective film, the presence of the above-mentioned antideterioration agent in a film formation material plays an important role also in the point which improves preservation | temporal retention with respect to the polarizer which comprises the polarizing plate and polarizing plate of this invention. In charge of.

In the liquid crystal display device using the polarizing plate of this invention, when the above-mentioned deterioration inhibitor exists in the optical film of this invention, the time-lapse preservability of an optical film can be improved and a liquid crystal display can be improved from a viewpoint of suppressing the said deterioration and deterioration. Also in the improvement of the display quality of an apparatus, it is excellent at the point which can make an optical compensation design function for a long time.

<< Antioxidants >>

Since cellulose ester accelerates decomposition not only by heat but also by oxygen under high temperature, it is preferable to contain antioxidant as a deterioration inhibitor in the optical film of this invention.

The antioxidant useful in the present invention can be used without limitation as long as it is a compound that suppresses deterioration of the film forming material due to oxygen, and among these, a phenol compound, a phosphorus compound, a sulfur compound, an alkyl radical scavenger, a peroxide decomposing agent, and an oxygen Cabins and the like. Among these, phenolic compounds, phosphorus compounds and alkylradical scavengers are preferred, but it is more preferable to use a combination of two of a phenolic compound and a phosphorus compound, and a combination of a phenolic compound, a phosphorus compound and an alkylradical scavenger is used. Most preferred. By mix | blending these compounds, the coloring of a molded object and the fall of intensity | strength by heat, thermal oxidation deterioration, etc. at the time of melt molding can be prevented, without reducing transparency, heat resistance, etc .. These compounds can be used individually or in combination of 2 or more types, respectively, Although the compounding quantity is suitably selected in the range which does not impair the objective of this invention, It is 0.01 mass% or more and 10 mass mass with respect to the mass of the cellulose ester which concerns on this invention. % Or less is preferable, More preferably, they are 0.1 mass% or more and 5.0 mass% or less, More preferably, they are 0.2 mass% or more and 2.0 mass% or less.

(Phenolic compound)

The phenolic compound is a known compound, and in addition to alkyl group-substituted phenols such as para-t-butylphenol and para- (1,1,3,3-tetramethylbutyl) phenol, for example, those described in US Pat. No. 4,839,405 Although the 2, 6- dialkyl phenol derivative compound and what is called a hindered phenol type compound as described in columns 12-14 are mentioned, A hindered phenol type compound is preferable among these.

Specific examples of the hindered phenol phenolic compound include n-octadecyl 3- (3,5-di-t-butyl-4-hydroxyphenyl) -propionate and n-octadecyl 3- (3,5-di -t-butyl-4-hydroxyphenyl) -acetate, n-octadecyl 3,5-di-t-butyl-4-hydroxybenzoate, n-hexyl 3,5-di-t-butyl-4- Hydroxyphenylbenzoate, n-dodecyl 3,5-di-t-butyl-4-hydroxyphenylbenzoate, neo-dodecyl 3- (3,5-di-t-butyl-4-hydroxyphenyl Propionate, dodecyl β- (3,5-di-t-butyl-4-hydroxyphenyl) propionate, ethyl α- (4-hydroxy-3,5-di-t-butylphenyl) Isobutyrate, Octadecyl α- (4-hydroxy-3,5-di-t-butylphenyl) Isobutyrate, Octadecyl α- (4-hydroxy-3,5-di-t-butyl-4-hydrate Hydroxyphenyl) propionate, 2- (n-octylthio) ethyl 3,5-di-t-butyl-4-hydroxy-benzoate, 2- (n-octylthio) ethyl 3,5-di-t -Butyl-4-hydroxy-phenylacetate, 2- (n-octadecylthio) ethyl 3,5-di-t -Butyl-4-hydroxyphenylacetate, 2- (n-octadecylthio) ethyl 3,5-di-t-butyl-4-hydroxy-benzoate, 2- (2-hydroxyethylthio) ethyl 3 , 5-di-t-butyl-4-hydroxybenzoate, diethylglycolbis- (3,5-di-t-butyl-4-hydroxy-phenyl) propionate, 2- (n-octadecyl Thio) ethyl 3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate, stearamide N, N-bis- [ethylene 3- (3,5-di-t-butyl-4 -Hydroxyphenyl) propionate], n-butylimino N, N-bis- [ethylene 3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], 2- ( 2-stearoyloxyethylthio) ethyl 3,5-di-t-butyl-4-hydroxybenzoate, 2- (2-stearoyloxyethylthio) ethyl 7- (3-methyl-5-t -Butyl-4-hydroxyphenyl) heptanoate, 1,2-propylene glycolbis- [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], ethylene glycol bis- [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], Neopentylglycolbis- [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], ethylene glycol bis- (3,5-di-t-butyl-4-hydroxyphenyl Acetate), glycerin-1-n-octadecanoate-2,3-bis- (3,5-di-t-butyl-4-hydroxy phenylacetate), pentaerythritol-tetrakis- [3- ( 3 ', 5'-di-t-butyl-4'-hydroxyphenyl) propionate], 3,9-bis- {2- [3- (3-tert-butyl-4-hydroxy-5- Methylphenyl) propionyloxy] -1,1-dimethylethyl} -2,4,8,10-tetraoxaspiro [5.5] undecane, 1,1,1-trimethylolethane-tris- [3- (3, 5-di-t-butyl-4-hydroxyphenyl) propionate], sorbitol hexa- [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], 2-hydroxy Hydroxyethyl 7- (3-methyl-5-t-butyl-4-hydroxyphenyl) propionate, 2-stearoyloxyethyl 7- (3-methyl-5-t-butyl-4-hydroxyphenyl ) Heptanoate, 1,6-n-hexanediol-bis [(3 ', 5'-di-t-butyl-4-hydroxyphenyl) prop Onate], pentaerythritol-it includes tetrakis (3,5-di -t- butyl-4-hydroxy-dihydro-cinnamate). Phenolic compounds of this type are commercially available, for example, under the trade names "IRGANOX 1076" and "Irganox 1010" from Ciba Specialty Chemicals.

(Phosphorus compound)

Examples of the phosphorus compound useful in the present invention include phosphite compounds and phosphonite compounds. Specific examples of the phosphite-based compound include triphenylphosphite, diphenylisodecylphosphite, phenyldiisodecylphosphite, tris (nonylphenyl) phosphite, tris (dinonylphenyl) phosphite, and tris (2,4- Di-t-butylphenyl) 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-4-hydroxy-5-methylphenyl) propoxy] -2,4 Monophosphite compounds such as 8,10-tetra-t-butyldibenz [d, f] [1,3,2] dioxaphosphine and tridecylphosphite; 4,4'-butylidene-bis (3-methyl-6-t-butylphenyl-di-tridecylphosphite), 4,4'-isopropylidene-bis (phenyl-di-alkyl (C12 to Diphosphite compounds such as C15) phosphite); and the like. The phosphite compound of this type is, for example, "Sumilizer GP" from Sumitomo Chemical Co., Ltd., ADK STAB PEP-24G from ADEKA Corporation, "ADK STAB PEP- 36 "," ADK STAB 3010 "," ADK STAB HP-10 "and" ADK STAB 2112 ".

Specific examples of the phosphonite-based compound include dimethyl-phenylphosphonite, di-t-butyl-phenylphosphonite, diphenyl-phenylphosphonite, di- (4-pentyl-phenyl) -phenylphosphonite, Di- (2-t-butyl-phenyl) -phenylphosphonite, di- (2-methyl-3-pentyl-phenyl) -phenylphosphonite, di- (2-methyl-4-octyl-phenyl)- Phenylphosphonite, Di- (3-butyl-4-methyl-phenyl) -phenylphosphonite, di- (3-hexyl-4-ethyl-phenyl) -phenylphosphonite, di- (2,4, 6-trimethylphenyl) -phenylphosphonite, di- (2,3-dimethyl-4-ethyl-phenyl) -phenylphosphonite, di- (2,6-diethyl-3-butylphenyl) -phenylforce Ponyite, di- (2,3-dipropyl-5-butylphenyl) -phenylphosphonite, di- (2,4,6-tri-t-butylphenyl) -phenylphosphonite, bis (2, 4-di-t-butyl-5-methylphenyl) biphenyl-4-yl-phosphonite, bis (2,4-di-t-butyl-5-methylphenyl) -4 '-(bis (2,4- Di-t-butyl-5-methylphenoxy) phosphino) biphenyl-4-yl-phosphona , Tetrakis (2,4-di-t-butyl-phenyl) -4,4'-biphenylenediphosphonite, tetrakis (2,5-di-t-butyl-phenyl) -4,4 ' -Biphenylenediphosphonite, tetrakis (3,5-di-t-butyl-phenyl) -4,4'-biphenylenediphosphonite, tetrakis (2,3,4-trimethylphenyl) -4 , 4'-biphenylenediphosphonite, tetrakis (2,3-dimethyl-5-ethyl-phenyl) -4,4'-biphenylenediphosphonite, tetrakis (2,3-dimethyl-4 -Propylphenyl) -4,4'-biphenylenediphosphonite, tetrakis (2,3-dimethyl-5-t-butylphenyl) -4,4'-biphenylenediphosphonite, tetrakis (2 , 5-dimethyl-4-t-butylphenyl) -4,4'-biphenylenediphosphonite, tetrakis (2,3-diethyl-5-methylphenyl) -4,4'-biphenylenediphospho Nitrate, tetrakis (2,6-diethyl-4-methylphenyl) -4,4'-biphenylenediphosphonite, tetrakis (2,4,5-triethylphenyl) -4,4'-biphenyl Rendiphosphonite, tetrakis (2,6-diethyl-4-propylphenyl) -4,4'-bipe Rendiphosphonite, tetrakis (2,5-diethyl-6-butylphenyl) -4,4'-biphenylenediphosphonite, tetrakis (2,3-diethyl-5-t-butylphenyl) -4,4'-biphenylenediphosphonite, tetrakis (2,5-diethyl-6-t-butylphenyl) -4,4'-biphenylenediphosphonite, tetrakis (2,3- Dipropyl-5-methylphenyl) -4,4'-biphenylenediphosphonite, tetrakis (2,6-dipropyl-4-methylphenyl) -4,4'-biphenylenediphosphonite, tetrakis ( 2,6-dipropyl-5-ethylphenyl) -4,4'-biphenylenediphosphonite, tetrakis (2,3-dipropyl-6-butylphenyl) -4,4'-biphenylenedipo Sponite, tetrakis (2,6-dipropyl-5-butylphenyl) -4,4'-biphenylenediphosphonite, tetrakis (2,3-dibutyl-4-methylphenyl) -4,4 ' -Biphenylenediphosphonite, tetrakis (2,5-dibutyl-3-methylphenyl) -4,4'-biphenylenediphosphonite, tetrakis (2,6-dibutyl-4-methylphenyl)- 4,4'-biphenylenediphosphonite, tete Keith (2,4-di-t-butyl-3-methylphenyl) -4,4'-biphenylenediphosphonite, tetrakis (2,4-di-t-butyl-5-methylphenyl) -4,4 '-Biphenylenediphosphonite, tetrakis (2,4-di-t-butyl-6-methylphenyl) -4,4'-biphenylenediphosphonite, tetrakis (2,5-di-t- Butyl-3-methylphenyl) -4,4'-biphenylenediphosphonite, tetrakis (2,5-di-t-butyl-4-methylphenyl) -4,4'-biphenylenediphosphonite, tetra Keith (2,5-di-t-butyl-6-methylphenyl) -4,4'-biphenylenediphosphonite, tetrakis (2,6-di-t-butyl-3-methylphenyl) -4,4 '-Biphenylenediphosphonite, tetrakis (2,6-di-t-butyl-4-methylphenyl) -4,4'-biphenylenediphosphonite, tetrakis (2,6-di-t- Butyl-5-methylphenyl) -4,4'-biphenylenediphosphonite, tetrakis (2,3-dibutyl-4-ethylphenyl) -4,4'-biphenylenediphosphonite, tetrakis ( 2,4-dibutyl-3-ethylphenyl) -4,4'-biphenylenediphosphonite, tetrakis (2,5-dibutyl-4- Tilphenyl) -4,4'-biphenylenediphosphonite, tetrakis (2,4-di-t-butyl-3-ethylphenyl) -4,4'-biphenylenediphosphonite, tetrakis ( 2,4-di-t-butyl-5-ethylphenyl) -4,4'-biphenylenediphosphonite, tetrakis (2,4-di-t-butyl-6-ethylphenyl) -4,4 '-Biphenylenediphosphonite, tetrakis (2,5-di-t-butyl-3-ethylphenyl) -4,4'-biphenylenediphosphonite, tetrakis (2,5-di-t -Butyl-4-ethylphenyl) -4,4'-biphenylenediphosphonite, tetrakis (2,5-di-t-butyl-6-ethylphenyl) -4,4'-biphenylenediphospho Nitrate, tetrakis (2,6-di-t-butyl-3-ethylphenyl) -4,4'-biphenylenediphosphonite, tetrakis (2,6-di-t-butyl-4-ethylphenyl ) -4,4'-biphenylenediphosphonite, tetrakis (2,6-di-t-butyl-5-ethylphenyl) -4,4'-biphenylenediphosphonite, tetrakis (2, 3,4-tributylphenyl) -4,4'-biphenylenediphosphonite, tetrakis (2,4,6-tri-t-butylphenyl) -4,4'-biphenylenedi Phosphonite and the like. Phosphorus-based compounds of this type are commercially available, for example, under the trade names "GSY-P101" from "IRGAFOS P-EPQ" from Shiva Specialty Chemicals Co., Ltd., and from Sakai Chemical Co., Ltd ..

As the phosphorus compound useful in the present invention, a phosphonite compound is preferable, and among these, 4, such as tetrakis (2,4-di-t-butyl-phenyl) -4,4'-biphenylenediphosphonite, etc. 4'-biphenylenediphosphonite compounds are preferred, and particularly preferred is tetrakis (2,4-di-t-butyl-5-methylphenyl) -4,4'-biphenylenediphosphonite.

(Alkyl radical scavengers)

The term "alkyl radical scavenging agent" in the present invention means a compound which has a group capable of rapidly reacting an alkyl radical and provides a stable product in which no subsequent reaction occurs after the reaction with the alkyl radical.

As a preferable alkyl radical scavenging agent in this invention, the compound represented by the said General formula (1) and the compound represented by the said General formula (2) are mentioned.

Hereinafter, although the compound represented by the said General formula (1) used for this invention is demonstrated to a specific example, this invention is not limited to these.

In said Formula (1), R <_1> represents a hydrogen atom or a C1-C10 alkyl group, Preferably it is a hydrogen atom or a C1-C4 alkyl group, Especially preferably, it is a hydrogen atom or a methyl group.

R ₂ and R ₃ each independently represent an alkyl group having 1 to 8 carbon atoms, may be linear, or may have a branched structure and a ring structure. R ₂ and R _3, preferably _{"* -C (CH 3) 2 -R} '" containing a quaternary carbon structure (represented by the * represents a connecting part of the aromatic ring, R' is C 1 To an alkyl group of 5 to 5). R ₂ is more preferably a tert-butyl group and a tert-amyl group. R ₃ is more preferably a tert-butyl group, a tert-amyl group or a tert-octyl group.

As a compound represented by the said Formula (1), it is marketed by Sumitomo Chemical Co., Ltd. under the brand names "Sumilizer GM" and "Smallizer GS."

Although the specific example of a compound represented by the said General formula (1) below is illustrated, this invention is not limited to these.

Next, although the compound represented by the said General formula (2) used for this invention is demonstrated to a specific example, this invention is not limited to these.

In formula (2), R ₁₂ to R ₁₅ each independently represent a hydrogen atom or a substituent. R ₁₂ and R ₁₃ , R ₁₃ and R ₁₄ , or R ₁₄ and R ₁₅ may be bonded to each other to form a ring. R ₁₆ represents a hydrogen atom or a substituent, n represents an integer of 1 to 4, when n is 1, R ₁₁ represents a substituent, and when n is an integer of 2 to 4, R ₁₁ is a bivalent to tetravalent It represents a linking group.

When R <_12> -R <_15> represents a substituent, there is no restriction | limiting in particular as said substituent, For example, an alkyl group (for example, a methyl group, an ethyl group, a propyl group, an isopropyl group, t-butyl group, a pentyl group, a hexyl group, Octyl group, dodecyl group, trifluoromethyl group, etc.), cycloalkyl group (e.g., cyclopentyl group, cyclohexyl group, etc.), aryl group (e.g., phenyl group, naphthyl group, etc.), acylamino group (e.g., , 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, Vinyl group, 2-propenyl group, 3-butenyl group, 1-methyl-3-propenyl group, 3-pentenyl group, 1-methyl-3-butenyl group, 4-hexenyl group, cyclohexenyl group, etc.) , Halogen atom (for example, fluorine atom, chlorine atom, bromine atom, iodine atom, etc.), alkynyl group (for example, propargyl group, etc.), complex Ventilation (for example, pyridyl group, thiazolyl group, oxazolyl group, imidazolyl group, etc.), alkylsulfonyl group (for example, methylsulfonyl group, ethylsulfonyl group, etc.), arylsulfonyl group (for example, Phenylsulfonyl group, naphthylsulfonyl group, and the like), alkylsulfinyl group (for example, methylsulfinyl group, etc.), arylsulfinyl group (for example, phenylsulfinyl group, etc.), phosphono group, acyl group (for example, Acetyl group, pivaloyl group, benzoyl group, etc.), carbamoyl group (for example, aminocarbonyl group, methylaminocarbonyl group, dimethylaminocarbonyl group, butylaminocarbonyl group, cyclohexylaminocarbonyl group, phenylaminocarbonyl group, 2-pyridylaminocarbonyl group) Sulfamoyl group (e.g., aminosulfonyl group, methylaminosulfonyl group, dimethylaminosulfonyl group, butylaminosulfonyl group, hexylaminosulfonyl group, cyclohexylaminosulfonyl group, octylaminosulfonyl group, dodecylamino, etc.) Ponyl group, phenylaminosulfonyl group, naphthylaminosulfonyl group, 2-pyridylaminosulfonyl group, etc.), sulfonamide group (for example, methanesulfonamide group, benzenesulfonamide group, etc.), cyano group, alkoxy group ( For example, methoxy group, ethoxy group, propoxy group, etc.), aryloxy group (for example, phenoxy group, naphthyloxy group, etc.), heterocyclic oxy group, siloxy group, acyloxy group (for example, acetyl Oxy group, benzoyloxy group, etc.), sulfonic acid group, salt of sulfonic acid, aminocarbonyloxy group, amino group (for example, amino group, ethylamino group, dimethylamino group, butylamino group, cyclopentylamino group, 2-ethylhexylamino group, dode Silamino group, etc.), anilino group (for example, phenylamino group, chlorophenylamino group, toludino group, anisidino group, naphthylamino group, 2-pyridylamino group, etc.), imide group, ureide group (for example, For example, methyl urea group, ethyl urea group, pen Aurade group, cyclohexyl uraide group, octyl uraide group, dodecyl uraide group, phenyl uraide group, naphthyl uraide group, 2-pyridylamino uraide group, etc.), alkoxycarbonylamino group (for example, Oxycarbonylamino group, phenoxycarbonylamino group, etc.), alkoxycarbonyl group (for example, methoxycarbonyl group, ethoxycarbonyl group, phenoxycarbonyl, etc.), aryloxycarbonyl group (for example, phenoxycarbonyl group, etc.), Groups, such as a summoned thio group, a thiourade group, a carboxyl group, the salt of a carboxylic acid, a hydroxyl group, a mercapto group, and a nitro group, are mentioned. These substituents may be further substituted by the same substituent.

In Chemical Formula 2, R ₁₂ to R ₁₅ are preferably a hydrogen atom or an alkyl group.

In said Formula (2), R <_16> represents a hydrogen atom or a substituent, The substituent represented by R <_16> can mention the same group as the substituent which R <_12> -R <_15> represents. In particular, R ₁₆ is preferably a hydrogen atom.

In the formula (2), n represents an integer of 1 to 4, but when n is 1, R ₁₁ represents a substituent, and examples of the substituent include the same groups as the substituents represented by R ₁₂ to R ₁₅ . When n is an integer of 2-4, R <_11> correspondingly represents a 2-4 tetravalent linking group.

When R ₁₁ represents a divalent to tetravalent linking group, for example, as a divalent linking group, a divalent alkylene group which may have a substituent, a divalent arylene group which may have a substituent, an oxygen atom, a nitrogen atom, a sulfur atom, or And combinations of these linking groups.

As a trivalent coupling group, the trivalent alkylene group which may have a substituent, the trivalent arylene group which may have a substituent, a nitrogen atom, or a combination of these coupling groups is mentioned, for example, As a tetravalent coupling group, a substituent is mentioned, for example. And tetravalent alkylene groups which may have a substituent, tetravalent arylene groups which may have a substituent, or a combination of these linking groups.

In Formula 2, n is preferably 1, and R ₁₁ at this time is preferably a substituted or unsubstituted phenyl group, and as a substituent, an alkyl group having 1 to 18 carbon atoms and an alkoxy group having 1 to 18 carbon atoms are preferable. And, a C1-C8 alkyl group and a C1-C8 alkoxy group are more preferable.

Although the specific example of the compound represented by the said General formula (2) in this invention is shown below, this invention is not limited to this.

(Other antioxidants)

Specific examples of other antioxidants include dilauryl 3,3-thiodipropionate, dimyristyl 3,3'-thiodipropionate, distearyl 3,3-thiodipropionate and lauryl Stearyl 3,3-thiodipropionate, pentaerythritol-tetrakis (β-lauryl-thio-propionate), 3,9-bis (2-dodecylthioethyl) -2,4,8 And sulfur compounds such as 10-tetraoxaspiro [5,5] undecane. Sulfur compounds of this type are commercially available, for example, from Sumitomo Chemical Co., Ltd. under the trade names " Smallizer TPL-R " and " Smallizer TP-D. &Quot; In addition, 3,4-dihydro-2H-1-benzopyran-based compound, 3,3'-spirodichroman-based compound, 1,1-spiroin stage compound described in Japanese Patent Publication No. 08-27508, Oxygen compounds such as morpholine, thiomorpholine, thiomorpholine oxide, thiomorpholine dioxide, a compound having a piperazine skeleton in its partial structure, and dialkoxybenzene-based compounds described in JP-A 3-174150. Cabins and the like. The partial structure of these antioxidants may be pendant to a portion of the polymer, or regularly to the polymer.

<< hindered amine light stabilizer >>

In the present invention, a hindered amine light stabilizer (HALS) compound is used as a deterioration inhibitor at the time of thermal melting of the film forming material, and as a deterioration inhibitor against external light exposed to the polarizer protective film after production or light from the backlight of the liquid crystal display. And as known compounds, for example, as described in US Pat. Nos. 4,619,956, 5-11, and US Pat. No. 4,839,405, 3-5, 2,2,6. , 6-tetraalkylpiperidine compounds, or acid addition salts thereof or complexes thereof with metal compounds.

Specific examples of the hindered amine light stabilizer include bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate and bis (2,2,6,6-tetramethyl-4-piperidyl) Succinate, bis (1,2,2,6,6-pentamethyl-4-piperidyl) sebacate, bis (N-octoxy-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-piperidyl) -2- (3,5-di-t-butyl-4-hydroxybenzyl ) -2-butylmalonate, bis (1-acroyl-2,2,6,6-tetramethyl-4-piperidyl) -2,2-bis (3,5-di-t-butyl-4 -Hydroxybenzyl) -2-butylmalonate, bis (1,2,2,6,6-pentamethyl-4-piperidyl) decanedioate, 2,2,6,6-tetramethyl-4- Piperidyl methacrylate, 4- [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyloxy] -1- [2- (3- (3,5-di-t -Butyl-4-hydroxyphenyl) propionyloxy) Tyl] -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 And tetrakis (1,2,2,6,6-pentamethyl-4-piperidyl) -1,2,3,4-butanetetracarboxylate and the like.

In addition, a polymer type compound may be used, and specific examples include N, N ', N' ', N' ''-tetrakis- [4,6-bis- [butyl- (N-methyl-2,2,6, 6-tetramethylpiperidin-4-yl) amino] -triazin-2-yl] -4,7-diazadecan-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-pi Polycondensate with ferridyl) butylamine, dibutylamine with 1,3,5-triazine and N, N'-bis (2,2,6,6-tetramethyl-4-piperidyl) butylamine Polycondensate, poly [{(1,1,3,3-tetramethylbutyl) amino-1,3,5-triazine-2,4-diyl} {(2,2,6,6-tetramethyl-4 -Piperidyl) imino} hexamethylene {(2,2,6,6-tetramethyl-4-piperidyl) imino}], 1,6-hexanediamine-N, N'-bis (2, Polycondensate of 2,6,6-tetramethyl-4-piperidyl) with morpholine-2,4,6-trichloro-1,3,5-triazine, poly [(6-morpholino-s -Triazine-2,4-diyl) [(2,2,6,6, -tetrame Piperidine ring such as -4-piperidyl) imino] -hexamethylene [(2,2,6,6-tetramethyl-4-piperidyl) imino]] is plurally bonded through a triazine skeleton High molecular weight HALS; Polymer of dimethyl succinate and 4-hydroxy-2,2,6,6-tetramethyl-1-piperidineethanol, 1,2,3,4-butanetetracarboxylic acid and 1,2,2,6, Of 6-pentamethyl-4-piperidinol with 3,9-bis (2-hydroxy-1,1-dimethylethyl) -2,4,8,10-tetraoxaspiro [5,5] undecane Although the compound etc. which the piperidine ring couple | bonded, such as mixed esterification, through the ester bond are mentioned, It is not limited to these.

Among these, polycondensates of dibutylamine, 1,3,5-triazine and N, N'-bis (2,2,6,6-tetramethyl-4-piperidyl) butylamine, poly [{( 1,1,3,3-tetramethylbutyl) amino-1,3,5-triazine-2,4-diyl} {(2,2,6,6-tetramethyl-4-piperidyl) imino } Hexamethylene {(2,2,6,6-tetramethyl-4-piperidyl) imino}], dimethyl succinate and 4-hydroxy-2,2,6,6-tetramethyl-1-piperi As a polymer with diethanol, the number average molecular weight (Mn) is preferably 2,000 to 5,000.

Hindered amine compounds of this type are commercially available, for example, from Tiba Specialty Chemicals under the trade names "ADK STAB LA-52" from "TINUVIN 144" and "Tinuvin 770", Adeka Co. have.

In the present invention, the hindered amine light stabilizer is preferably added in an amount of 0.1 to 10% by mass, more preferably 0.2 to 5% by mass, more preferably 0.5 to 2% by mass, based on the mass of the cellulose ester according to the present invention. Even more preferred. These may be used in combination of two or more.

<< Mountain catcher >>

In the optical film of this invention, it is preferable to contain an acid capture | acquisition agent in the optical film of this invention, since a cellulose ester accelerates decomposition | disassembly also by acid in the high temperature environment in which melt film forming is performed. As the acid trapping agent useful in the present invention, any compound that reacts with an acid to inactivate the acid can be used without limitation, but among these, a compound having an epoxy group as described in US Patent No. 4,137,201 is preferable. Epoxy compounds as such acid trapping agents are known in the art, and polyglycol derived by condensation of various polyglycol diglycidyl ethers, in particular about 8 to 40 moles of ethylene oxide per mole of polyglycol, Metal epoxy compounds (eg, those conventionally used in vinyl chloride polymer compositions and with vinyl chloride polymer compositions) such as diglycidyl ether of glycerol, epoxidized ether condensation products, and diglyins of bisphenol A Cydyl ether (i.e. 4,4'-dihydroxydiphenyldimethylmethane), epoxidized unsaturated fatty acid esters (especially esters of alkyl of about 4 to 2 carbon atoms of fatty acids of 2 to 22 carbon atoms) Butyl epoxy stearate) and the like, and various epoxidized long chain fatty acid triglycerides such as epoxidized soybean oil and epoxidized linseed oil. Epoxidized vegetable oils and other unsaturated natural oils (sometimes referred to as epoxidized natural glycerides or unsaturated fatty acids, which generally contain 12 to 22 carbon atoms), which may be represented and exemplified by the composition of Included. Moreover, EPON 815C and other epoxidized ether oligomer condensation products can also be used suitably as a commercial epoxy group containing epoxide resin compound.

As an acid scavenger which can be used in addition to the above, oxetane compounds, oxazoline compounds, organic acid salts or acetylacetonato complexes of alkaline earth metals, and paragraphs 68 to 105 of JP-A-5-194788 What is described is included.

In this invention, it is preferable to add 0.1-10 mass% with respect to the mass of the cellulose ester which concerns on this invention, It is more preferable to add 0.2-5 mass%, It is preferable to add 0.5-2 mass% Even more preferred. These may be used in combination of two or more.

In addition, although an acid trapping agent may be called an acid scavenger, an acid trapping agent, an acid catcher, etc., in this invention, it can use without difference by these names.

<< metal deactivator >>

The metal inert agent means a compound which inactivates metal ions which act as an initiator or a catalyst in an oxidation reaction, and examples thereof include a hydrazide compound, an oxalic acid diamide compound, a triazole compound, and the like. N'-bis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyl] hydrazine, 2-hydroxyethyloxalic acid diamide, 2-hydroxy-N- (1H-1, 2,4-triazol-3-yl) benzamide, N- (5-tert-butyl-2-ethoxyphenyl) -N '-(2-ethylphenyl) oxalic acid amide, etc. are mentioned.

In this invention, it is preferable to add 0.0002-2 mass% with respect to the mass of the cellulose ester which concerns on this invention, It is more preferable to add 0.0005-2 mass%, It is preferable to add 0.001-1 mass% Even more preferred. These can use 2 or more types together.

<< Plasticizer >>

In formation of the optical film by melt casting of this invention, it is necessary to add 1 or more types of plasticizers in a film formation material.

A plasticizer is an additive which generally has the effect of improving fragility or imparting flexibility by adding it to a polymer, but in the present invention, an additive which lowers the melting temperature of the film forming material or the viscosity of the film forming material at the same temperature. It is used as an additive which lowers. Since the deterioration of the cellulose ester in the melting process can be suppressed by lowering the melting temperature or lowering the melt viscosity, in the present invention, any material having such an effect can be used as a plasticizer without limitation. When the plasticizer to be added has a melting point lower than the glass transition temperature of the cellulose ester or the glass transition temperature, such a melting | fusing point fall effect and a viscosity reduction fall, a larger effect is easy to be acquired.

Moreover, since addition of a plasticizer may show effects, such as improvement of the mechanical properties of a cellulose ester film, improvement of tear strength, provision of water absorption, and reduction of moisture permeability, it is more preferable to use the material which has such an effect as a plasticizer.

In addition, although the plasticizer also has the effect of suppressing deterioration in the thermomelting step of the cellulose ester by addition as described above, the effect is due to a physical effect and not due to a chemical effect. It does not classify as a degradation inhibitor.

As the plasticizer which satisfies the above conditions and is used in the present invention, for example, a phosphate ester plasticizer, a polyhydric alcohol ester plasticizer (ethylene glycol ester plasticizer, glycerin ester plasticizer, diglycerin ester plasticizer, and the like) Carboxylic acid ester plasticizers, carbohydrate ester plasticizers, polymer plasticizers, etc. are mentioned. Among these, polyhydric alcohol ester plasticizers and polyhydric carboxylic acid ester plasticizers are preferable, and polyhydric alcohol ester plasticizers are more preferable. In addition, the plasticizer may be liquid or solid, and it is preferred that the composition is pharmaceutically colorless. The addition amount should not have an adverse effect on optical and mechanical properties, and the compounding amount thereof is appropriately selected within a range that does not impair the object of the present invention, and preferably contains 1 to 25% by mass relative to the mass of the cellulose ester according to the present invention. It is a cellulose ester film characterized by the above-mentioned. When it is less than 1 mass%, a planarity improvement effect is not seen, and when it is more than 25 mass%, bleed out will arise easily and it is unpreferable since the aging stability of a film falls. More preferably, it is a cellulose ester film containing 3-20 mass% of plasticizers, More preferably, it is a cellulose ester film containing 5-15 mass%.

Hereinafter, although the plasticizer used for this invention is demonstrated to a specific example, this invention is not limited to these.

In the present invention, an ester plasticizer composed of a polyhydric alcohol and a monovalent carboxylic acid, and an ester plasticizer containing a polyhydric carboxylic acid and a monohydric alcohol are preferable because they have high affinity with cellulose esters. Ester plasticizers containing carboxylic acids are particularly preferred because of their higher affinity with cellulose esters.

The polyhydric alcohol ester plasticizer refers to a compound having a plurality of hydroxyl groups in one molecule and a compound condensed with a monovalent organic acid as a polyhydric alcohol ester plasticizer, and a polycarboxylic acid ester plasticizer in one molecule. The compound which has a some carboxylic acid group, and the compound in which some monohydric alcohol or phenol condensed is called polyhydric carboxylic acid ester plasticizer.

Although the following are mentioned as an example of the polyhydric alcohol which is a raw material of the ester plasticizer used preferably in this invention, For example, this invention is not limited to these.

Adonitol, arabitol, ethylene glycol, glycerin, diglycerin, diethylene glycol, triethylene glycol, tetraethylene glycol, 1,2-propanediol, 1,3-propanediol, dipropylene glycol, tripropylene glycol, 1 , 2-butanediol, 1,3-butanediol, 1,4-butanediol, dibutylene glycol, 1,2,4-butanetriol, 1,5-pentanediol, 1,6-hexanediol, hexanetriol, Galactitol, mannitol, 3-methylpentane-1,3,5-triol, pinacol, sorbitol, trimethylolpropane, ditrimethylolpropane, trimethylolethane, pentaerythritol, dipentaerythritol, xylitol and the like Can be. Ethylene glycol, glycerin, and trimethylolpropane are particularly preferable.

Examples of preferred organic acids include acetic acid, propionic acid, butyric acid, isobutyric acid, pivalic acid, acrylic acid, methacrylic acid, cyclohexanecarboxylic acid, benzoic acid, aniseic acid, 3,4,5-trimethoxybenzoic acid, toluic acid, tert-butylbenzoic acid, naphthoic acid, picolinic acid, and the like, but a polyhydric alcohol ester is formed by an unsaturated carboxylic acid having high effect of reducing the moisture permeability of the cellulose ester, for example, an aromatic carboxylic acid. desirable.

The organic acid used for the polyhydric alcohol ester may be one kind or a mixture of two or more kinds. In addition, all the OH groups in the polyhydric alcohol may be esterified, and some may be left as OH groups.

As an ethylene glycol ester plasticizer which is one of polyhydric alcohol ester system, specifically, the plasticizer of ethylene glycol alkyl esters, such as ethylene glycol diacetate and ethylene glycol dibutyrate, ethylene glycol dicyclopropyl carboxylate, ethylene glycol dicyclo And ethylene glycol aryl ester plasticizers such as ethylene glycol cycloalkyl ester plasticizers such as hexyl carboxylate, ethylene glycol dibenzoate and ethylene glycol di4-methylbenzoate. These alkylate groups, cycloalkylate groups, and arylate groups may be the same or different and may be further substituted. Moreover, the mixture of an alkylate group, a cycloalkylate group, and an arylate group may be sufficient, and these substituents may be couple | bonded with a covalent bond. In addition, the ethylene glycol moiety may also be substituted, and the partial structure of the ethylene glycol ester may be part of the polymer, or may be periodically pendant, and may also be introduced into part of the molecular structure of additives such as antioxidants, acid removers, ultraviolet absorbers, and the like. have.

As a glycerol ester plasticizer which is one of polyhydric-alcohol ester system, specifically, glycerol alkyl ester, glycerol tricyclopropyl carboxylate, such as a triacetin, a tributyline, glycerine diacetate caprylate, and glycerol oleate propionate Glycerin aryl esters such as glycerin cycloalkyl esters such as glycerin tricyclohexyl carboxylate, glycerin tribenzoate, glycerin 4-methylbenzoate, diglycerine tetraacetylate, diglycerine tetrapropionate, diglycerine acetate trica To diglycerin cycloalkyl esters such as diglycerin alkyl esters such as phthalates and diglycerin tetralaurate, diglycerin tetracyclobutyl carboxylate and diglycerin tetracyclopentyl carboxylate, and diglycerin tetrabenzo Diglycerol aryl esters, such as dihydrate and diglycerin 3-methylbenzoate, etc. are mentioned. These alkylate groups, cycloalkylcarboxylate groups, and arylate groups may be the same or different and may be further substituted. Moreover, the mixture of an alkylate group, a cycloalkylcarboxylate group, and an arylate group may be sufficient, and these substituents may be couple | bonded with a covalent bond. In addition, the glycerin and diglycerin moiety may be substituted, and the partial structure of the glycerin ester and the diglycerin ester may be a part of the polymer or a pendant regularly, and also the molecular structure of additives such as antioxidants, acid removers, ultraviolet absorbers, etc. May be introduced in some.

As another polyhydric-alcohol ester plasticizer, the polyhydric-alcohol ester plasticizer of Paragraph 30-33 of Unexamined-Japanese-Patent No. 2003-12823 is mentioned specifically ,.

These alkylate groups, cycloalkylcarboxylate groups, and arylate groups may be the same or different and may be further substituted. Moreover, the mixture of an alkylate group, a cycloalkylcarboxylate group, and an arylate group may be sufficient, and these substituents may be couple | bonded with a covalent bond. In addition, the polyhydric alcohol moiety may also be substituted, and the partial structure of the polyhydric alcohol may be part of the polymer, or may be pendant regularly, and may also be introduced into part of the molecular structure of additives such as antioxidants, acid removers, ultraviolet absorbers, and the like. have.

Of the ester plasticizers containing the polyhydric alcohol and monovalent carboxylic acid, alkyl polyhydric alcohol aryl esters are preferable, and specifically, the ethylene glycol dibenzoate, glycerin tribenzoate, diglycerin tetrabenzoate, and Japanese Patent Laid-Open. The exemplary compound 16 of Paragraph 31 of Unexamined-Japanese-Patent No. 2003-12823 is mentioned.

As a dicarboxylic acid ester plasticizer which is one of polyhydric carboxylic acid ester system, the plasticizer of alkyl dicarboxylic acid alkyl ester system, such as didodecyl malonate, a dioctyl adipate, a dibutyl sebacate, and a dish, Alkyl dicarboxylic acid aryl ester plasticizers, such as alkyl dicarboxylic acid cycloalkyl ester plasticizers, such as clopentyl succinate and dicyclohexyl adipate, diphenyl succinate, and di 4-methylphenyl glutarate, and di Cycloalkyl dicarboxylic acid alkyl ester plasticizers, such as hexyl-1, 4- cyclohexanedicarboxylate and didecyl bicyclo [2.2.1] heptane-2,3- dicarboxylate, dicyclohexyl-1 Cycloalkyldicarboxylic acid cycloalkyl ester plasticizers, such as 2-cyclobutanedicarboxylate and dicyclopropyl-1,2-cyclohexyldicarboxylate, diphenyl-1,1-cyclopropyldi Cycloalkyl dicarboxylic acid aryl ester plasticizers, such as carboxylate and di 2-naphthyl- 1, 4- cyclohexane dicarboxylate, diethyl phthalate, dimethyl phthalate, dioctyl phthalate, dibutyl phthalate, di Plasticizers of aryldicarboxylic acid alkyl esters such as 2-ethylhexyl phthalate, plasticizers of aryldicarboxylic acid cycloalkyl esters such as dicyclopropyl phthalate, dicyclohexyl phthalate, diphenylphthalate, and di4 Glycolic acid ester plasticizers, such as aryl dicarboxylic acid aryl ester plasticizers, such as methylphenyl phthalate, butylphthalyl butyl glycolate, and ethyl phthalyl ethyl glycolate, acetyl trimethyl citrate, acetyl triethyl citrate, and acetyl citrate Citric acid plasticizers, such as butyl, etc. are mentioned. These alkoxy groups and cycloalkoxy groups may be the same or different, and may be 1 substitution, and these substituents may be further substituted. An alkyl group and a cycloalkyl group may be mixed, and these substituents may be bonded by a covalent bond. Furthermore, the aromatic ring of phthalic acid may also be substituted, and multimers, such as a dimer, a trimer, and a tetramer, may be sufficient. In addition, the partial structure of the phthalic acid ester may be part of the polymer, or may be pendant to the polymer on a regular basis, and may be incorporated into part of the molecular structure of additives such as antioxidants, acid removers, ultraviolet absorbers and the like.

As another polyhydric carboxylic acid ester type plasticizer, Alkyl polyhydric carboxylic acid alkyl ester, such as a tridodecyl tricarbarate and a tributyl- meso- butane- 1,2,3,4- tetracarboxylate, specifically, Alkaline polyhydric carboxylic acid cycloalkyl ester plasticizers, such as a plasticizer of a type | system | group, a tricyclohexyl tricarbarate, and a tricyclo propyl- 2-hydroxy-1,2,3- propane tricarboxylate, and a triphenyl 2- Alkyl polyhydric carboxylic acid aryl ester plasticizers, such as hydroxy-1,2,3-propanetricarboxylate and tetra 3-methylphenyl tetrahydrofuran-2,3,4,5-tetracarboxylate, tetrahexyl Plasticizers of cycloalkyl polyhydric carboxylic acid alkyl esters such as -1,2,3,4-cyclobutanetetracarboxylate and tetrabutyl-1,2,3,4-cyclopentanetetracarboxylate, tetracyclopropyl -1,2,3,4-cyclobutanetetra Cycloalkyl polyhydric carboxylic acid cycloalkyl ester plasticizers, such as carboxylate and tricyclohexyl-1,3,5-cyclohexyl tricarboxylate, triphenyl-1,3,5-cyclohexyl tricarboxylate Cycloalkyl polyhydric carboxylic acid aryl ester plasticizers such as hexa 4-methylphenyl-1,2,3,4,5,6-cyclohexyl hexacarboxylate, tridodecylbenzene-1,2,4-tri Aryl polyhydric carboxylic acid alkyl ester plasticizers such as carboxylate and tetraoctylbenzene-1,2,4,5-tetracarboxylate, tricyclopentylbenzene-1,3,5-tricarboxylate, tetra Aryl polyhydric carboxylic acid cycloalkyl ester plasticizers such as cyclohexylbenzene-1,2,3,5-tetracarboxylate, triphenylbenzene-1,3,5-tetracarboxylate, hexa 4-methylphenylbenzene Of aryl polyvalent carboxylic acid aryl esters such as -1,2,3,4,5,6-hexacarboxylate It may be the problem. These alkoxy groups and cycloalkoxy groups may be the same or different, and may be substituted one by one, and these substituents may be further substituted. An alkyl group and a cycloalkyl group may be mixed, and these substituents may be bonded by a covalent bond. Furthermore, the aromatic ring of phthalic acid may also be substituted, and multimers, such as a dimer, a trimer, and a tetramer, may be sufficient. In addition, the partial structure of the phthalic acid ester may be part of the polymer, or may be pendant to the polymer on a regular basis, and may be incorporated into part of the molecular structure of additives such as antioxidants, acid removers, ultraviolet absorbers and the like.

In the ester plasticizer containing the said polyhydric carboxylic acid and monohydric alcohol, alkyl dicarboxylic acid alkyl ester is preferable and the said dioctyl adipate is mentioned specifically ,.

As another plasticizer used for this invention, a phosphate ester plasticizer, a carbohydrate ester plasticizer, a polymer plasticizer, etc. are mentioned.

Specific examples of the phosphate ester plasticizer include phosphoric acid cycloalkyl esters such as alkyl phosphates such as triacetyl phosphate and tributyl phosphate, tricyclopentyl phosphate and cyclohexyl phosphate, triphenyl phosphate, tricresyl phosphate and cresyl phenyl. Phosphate aryl esters such as phosphate, octyl diphenyl phosphate, diphenyl biphenyl phosphate, trioctyl phosphate, tributyl phosphate, trinaphthyl phosphate, trixyl yl phosphate and trisortho-biphenyl phosphate. These substituents may be the same or different and may be further substituted. Moreover, the mixture of an alkyl group, a cycloalkyl group, and an aryl group may be sufficient, and substituents may be couple | bonded with a covalent bond.

Moreover, alkylene bis (dialkyl phosphate), such as ethylene bis (dimethyl phosphate) and butylene bis (diethyl phosphate), alkylene bis (such as ethylene bis (diphenyl phosphate), and propylene bis (dinaphthyl phosphate) Arylene bis (dialkyl phosphate) such as diaryl phosphate), phenylene bis (dibutyl phosphate) and biphenylene bis (dioctyl phosphate), phenylene bis (diphenyl phosphate), naphthylene bis (ditolyl phosphate) Phosphoric acid ester, such as arylene bis (diaryl phosphate), such as), is mentioned. These substituents may be the same or different and may be further substituted. Moreover, the mixture of an alkyl group, a cycloalkyl group, and an aryl group may be sufficient, and substituents may be couple | bonded with a covalent bond.

In addition, the partial structure of the phosphate ester may be part of the polymer, or may be pendant regularly, and may also be incorporated into part of the molecular structure of additives such as antioxidants, acid removers, ultraviolet absorbers and the like. Among these compounds, aryl phosphate esters and arylene bis (diaryl phosphates) are preferable, and triphenyl phosphate and phenylene bis (diphenyl phosphate) are particularly preferable.

Next, a carbohydrate ester plasticizer is demonstrated. By carbohydrate is meant monosaccharides, disaccharides or trisaccharides in which sugars are present in the form of pyranose or furanose (six- or five-membered rings). Non-limiting examples of carbohydrates include glucose, sucrose, lactose, cellobiose, mannose, xylose, ribose, galactose, arabinose, fructose, sorbose, cellotriose, and raffinose. The carbohydrate ester refers to the dehydration condensation of the hydroxyl group and the carboxylic acid of the carbohydrate to form an ester compound, and in detail, refers to an aliphatic carboxylic acid ester or an aromatic carboxylic acid ester of a carbohydrate. As aliphatic carboxylic acid, acetic acid, propionic acid, etc. are mentioned, for example, As aromatic carboxylic acid, benzoic acid, toluic acid, aniseic acid, etc. are mentioned, for example. Carbohydrates have a number of hydroxyl groups according to their type, but a portion of the hydroxyl groups and the carboxylic acid may react to form an ester compound, or all of the hydroxyl groups and the carboxylic acid may react to form an ester compound. In the present invention, it is preferable that all of the hydroxyl groups react with the carboxylic acid to form an ester compound.

Specific examples of the carbohydrate ester plasticizer include glucose pentaacetate, glucose pentapropionate, glucose pentabutyrate, sucrose octaacetate, sucrose octabenzoate, and the like, and sucrose octaacetate and sucrose octabenzoate. Is more preferable, and sucrose octabenzoate is particularly preferable. Carbohydrate ester plasticizers of this type are commercially available from Daiichi Kogyo Seiyaku Co., Ltd. under the trade names " monopet SB " and " monopet SOA ".

Specific examples of the polymer plasticizer include aliphatic hydrocarbon polymers, alicyclic hydrocarbon polymers, ethyl polyacrylate, methyl polymethacrylate, copolymers of methyl methacrylate and 2-hydroxyethyl methacrylate, and methacrylic acid. Acrylic polymers, such as a copolymer of methyl, methyl acrylate, and 2-hydroxyethyl methacrylate; vinyl polymers such as polyvinyl isobutyl ether and poly N-vinylpyrrolidone; polystyrene; poly 4-hydroxystyrene Polyesters such as styrene-based polymers, polybutylene succinate, polyethylene terephthalate, polyethylene naphthalate, polyethers such as polyethylene oxide and polypropylene oxide, polyamides, polyurethanes, polyureas, and the like. . As for a number average molecular weight, about 1000-50000 are preferable, Especially preferably, it is 5000-20000. If it is 1000 or less, a problem arises in volatility, and when it exceeds 500000, a plasticization capacity falls and it adversely affects the mechanical property of a cellulose ester film. These polymer plasticizers may be homopolymers composed of one type of repeating unit, or may be a copolymer having a plurality of repeating structures. These polymers may be used in combination of two or more.

In the cellulose ester film according to the present invention, it is preferable to contain 1 to 25% by mass of an ester plasticizer containing a polyhydric alcohol and a monovalent carboxylic acid, and an ester plasticizer containing a polyhydric carboxylic acid and a monohydric alcohol. It can also be used together with other plasticizers.

In the cellulose ester film according to the present invention, an ester plasticizer containing a polyhydric alcohol and a monovalent carboxylic acid is more preferred, but an ester plasticizer containing a trivalent or higher alcohol and a monovalent carboxylic acid is used for cellulose ester. Because of its high compatibility and the ability to be added at a high addition rate, it is most preferable because other plasticizers and additives can be easily used together without causing bleed-out even if other plasticizers or additives are used in combination. .

<< UV absorber >>

In this invention, it is preferable that a film forming material contains a ultraviolet absorber further at the point which improves durability. It is preferable that a ultraviolet absorber is excellent in the absorption ability of the ultraviolet-ray of wavelength 370 nm or less from the viewpoint of the degradation of the polarizer and the ultraviolet-ray of a display apparatus, and the absorption of the visible light of wavelength 400nm or more from the viewpoint of liquid crystal display. As an ultraviolet absorber used for this invention, an oxybenzophenone type compound, a benzotriazole type compound, a salicylic acid ester type compound, a benzophenone type compound, a cyanoacrylate type compound, a nickel complex salt type compound, a triazine type compound etc. are mentioned, for example. Although it is mentioned, a benzophenone type compound, a benzotriazole type compound with few coloring, and a triazine type compound are preferable. Moreover, the ultraviolet absorber of Unexamined-Japanese-Patent No. 10-182621, 8-337574, the polymeric ultraviolet absorber of Unexamined-Japanese-Patent No. 6-148430, and Unexamined-Japanese-Patent No. 2003-113317. Can also be used.

Specific examples of the benzotriazole-based compound include 2- (2'-hydroxy-5'-methylphenyl) benzotriazole and 2- (2'-hydroxy-3 ', 5'-di-tert-butylphenyl) benzo Triazole, 2- (2'-hydroxy-3'-tert-butyl-5'-methylphenyl) benzotriazole, 2- (2'-hydroxy-3 ', 5'-di-tert-butylphenyl) -5-chlorobenzotriazole, 2- (2'-hydroxy-3 '-(3 ", 4", 5 ", 6" -tetrahydrophthalimidemethyl) -5'-methylphenyl) benzotriazole, 2,2-methylenebis (4- (1,1,3,3-tetramethylbutyl) -6- (2H-benzotriazol-2-yl) phenol), 2- (2'-hydroxy-3 ' -tert-butyl-5'-methylphenyl) -5-chlorobenzotriazole, 2- (2'-hydroxy-3'-tert-butyl-5 '-(2-octyloxycarbonylethyl) -phenyl)- 5-chlorobenzotriazole, 2- (2'-hydroxy-3 '-(1-methyl-1-phenylethyl) -5'-(1,1,3,3, -tetramethylbutyl) -phenyl) Benzotriazole, 2- (2H-benzotriazol-2-yl) -6- (straight and branched dodecyl) -4-methylphenol, octyl-3- [3-tert-butyl-4-hydroxy-5 -(Chloro-2H-benzotriazol-2-yl) phen ] Propionate and a mixture of 2-ethylhexyl-3- [3-tert-butyl-4-hydroxy-5- (5-chloro-2H-benzotriazol-2-yl) phenyl] propionate, etc. Although it is mentioned, it is not limited to these.

In addition, as a commercial item, TINUVIN 326, TINUVIN 109, TINUVIN 171, TINUVIN 900, TINUVIN 928, TINUVIN 360 (all Shiva Specialty) Chemicals, Inc.), LA31 (made by Adeka Co., Ltd.), Sumisorb 250 (manufactured by Sumitomo Chemical Co., Ltd.), and RUVA-100 (manufactured by Otsuka Chemical Co., Ltd.).

As a specific example of a benzophenone type compound, 2, 4- dihydroxy benzophenone, 2, 2'- dihydroxy-4- methoxy benzophenone, 2-hydroxy-4- methoxy-5- sulfo benzophenone And bis (2-methoxy-4-hydroxy-5-benzoylphenylmethane) and the like, but are not limited thereto.

In this invention, it is preferable that a ultraviolet absorber is a benzotriazole type compound.

In this invention, it is preferable to add 0.1-10 mass% with respect to the mass of the cellulose ester which concerns on this invention, It is more preferable to add 0.2-5 mass%, It is more preferable to add 0.5-3 mass% More preferred. These may be used in combination of two or more.

In addition, the benzotriazole structure or the triazine structure may be part of the polymer, or may be pendant to the polymer on a regular basis, or may be incorporated into part of the molecular structure of other additives such as plasticizers, antioxidants, acid removers and the like.

Although it does not specifically limit as a conventionally well-known ultraviolet absorbing polymer, For example, the polymer which superposed | polymerized RUVA-93 (manufactured by Otsuka Chemical Co., Ltd.) and the polymer which copolymerized RUVA-93 and another monomer etc. are mentioned. Specifically, PUVA-30M which copolymerized RUVA-93 and methyl methacrylate in the ratio (mass ratio) of 3: 7, PUVA-50M etc. which copolymerized in the ratio (mass ratio) of 5: 5 are mentioned. Furthermore, the polymer described in Unexamined-Japanese-Patent No. 2003-113317 can be mentioned.

<< other additive >>

In the present invention, the cellulose ester may contain various additives in addition to the deterioration inhibitor, the plasticizer and the ultraviolet absorber. For example, a mat agent, a filler, inorganic compounds, such as a silica and a silicate, a dye, a pigment, a fluorescent substance, a dichroic dye, a retardation control agent, a refractive index regulator, a gas permeation inhibitor, an antimicrobial agent, a biodegradability giver, etc. are mentioned. . Moreover, as long as it has the said function, the additive which is not classified here can also be used.

The method of incorporating these additives into the cellulose ester may be a method of mixing each material as a solid or a liquid, heat melting and kneading to form a uniform melt, and then flexibly forming an optical film. After dissolving all materials using a solvent etc. to make a homogeneous solution, a solvent is removed, a mixture of an additive and a cellulose ester can be formed, this is heated and melted, it can be cast, and an optical film can be formed.

(Made by Matt)

In the film according to the present invention, a matting agent may be added to impart slippage, optical and mechanical functions. As a mat agent, the microparticles | fine-particles of an inorganic compound or the microparticles | fine-particles of an organic compound are mentioned.

The shape of the mat is preferably a spherical shape, a rod shape, a needle shape, a layer shape, or a flat plate shape. Examples of the mat agent include oxides of metals such as silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide, calcium carbonate, kaolin, talc, calcined calcium silicate, calcium silicate hydrate, aluminum silicate, magnesium silicate, calcium phosphate, Inorganic fine particles and crosslinked polymer fine particles such as silicates and carbonates. Especially, since silicon dioxide can make the haze of a film low, it is preferable. Since these microparticles | fine-particles are surface-treated by the organic substance, since they can reduce the haze of a film, it is preferable.

Surface treatment is preferably performed with halosilanes, alkoxysilanes, silazanes, siloxanes, and the like. The larger the average particle size of the fine particles is, the larger the slippery effect is, and the smaller the average particle size is, the more excellent the transparency. In addition, the average particle diameter of the primary particle of microparticles | fine-particles is the range of 0.01-1.0 micrometer. 5-50 nm is preferable and, as for the average particle diameter of the primary particle of preferable microparticles | fine-particles, More preferably, it is 7-14 nm. These microparticles | fine-particles are used preferably because they produce 0.01-1.0 micrometer of unevenness | corrugation on the surface of a cellulose ester film.

As fine particles of silicon dioxide, Nihon Shokubai Co., Ltd. (AEROSIL) 200, 200V, 300, R972, R972V, R974, R202, R812, OX50, TT600, NAX50 manufactured by Nippon Aerosol Co., Ltd. KE-P10, KE-P30, KE-P100, KE-P150, etc. are manufactured, Preferably they are aerosol 200V, R972V, NAX50, KE-P30, KE-P100. These microparticles | fine-particles can also be used together 2 or more types.

When two or more of them are used in combination, they can be mixed and used at an arbitrary ratio. Particles having different average particle diameters or materials, for example, aerosil 200V and R972V, may be used in the range of 0.1: 99.9 to 99.9: 0.1 by mass ratio.

It is preferable to perform these addition methods of a mat agent by kneading | mixing. In another embodiment, the mixture of the mat agent and the cellulose ester and / or plasticizer and / or the antioxidant and / or the ultraviolet absorber previously dispersed in the solvent is mixed and dispersed to obtain a solid obtained by volatilizing or precipitating the solvent. It is preferable to use in a manufacturing process from the viewpoint that a mat agent can be disperse | distributed uniformly in a cellulose ester.

The mat agent may be added to improve the mechanical, electrical, and optical properties of the film.

Moreover, although the slip property of the film obtained improves so that these microparticles | fine-particles are added, since haze rises as it adds, content becomes like this. Preferably it is 0.001-5 mass%, More preferably, it is 0.005-1 mass%, More Preferably it is 0.01-0.5 mass%.

Moreover, as a film which concerns on this invention, since a haze value exceeds 1.0%, it affects as an optical material, Preferably haze value is less than 1.0%, More preferably, it is less than 0.5%. The haze value can be measured based on JIS-K7136.

The deterioration reaction by oxygen in air may coexist in the storage or film forming process of the film formation material mentioned above. In this case, the use of the effect of reducing the oxygen concentration in the air together with the stabilizing action of the additive can also be used in embodying the present invention. This can be exemplified by the use of nitrogen or argon as an inert gas, a degassing operation by depressurization or vacuum, and an operation by an enclosed environment as a known technique. can do. By reducing the probability that the film forming material is in contact with oxygen in the air, deterioration of the material can be suppressed, which is preferable for the purposes of the present invention.

<< optical film >>

Next, the detail of the optical film of this invention is demonstrated.

In this invention, an optical film means the functional film used for various display apparatuses, such as a liquid crystal display, a plasma display, and an organic electroluminescent display, Specifically, the polarizing plate protective film, retardation film, antireflection film, brightness for liquid crystal display devices Optical compensation films such as an enhancement film, a hard coat film, an antiglare film, an antistatic film, and an enlarged viewing angle.

In the optical film according to the present invention, in addition to the cellulose ester according to the present invention, cellulose ester-based resins, cellulose ether-based resins, and vinyl-based resins (polyvinyl acetate-based resins, polyvinyl alcohol-based resins, etc.) not included in the present invention are also included. ), Olefin resins (norbornene resins, monocyclic cyclic olefin resins, cyclic conjugated diene resins, vinyl alicyclic hydrocarbon resins, and the like), polyester resins (aromatic polyesters, aliphatic polyesters, or the like) Copolymer), acrylic resin (including copolymer), polycarbonate resin, polystyrene resin, polysulfone resin, polyarylate resin and the like. As for content of resin other than a cellulose ester, 0.1-30 mass% is preferable.

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

<< Melting and Flexing Method >>

The optical film according to the present invention is produced by melt casting as described above. The molding method by melt casting that is heated and melted without using a solvent (for example, methylene chloride, etc.) used in the solution casting method is more specifically a melt extrusion molding method, a press molding method, an inflation method, an injection molding method, a blow molding method, It can classify by the extending molding method. Among these, in order to obtain the polarizing plate protective film which is excellent in mechanical strength, surface precision, etc., the melt extrusion method is excellent.

The film forming material is required to have little or no volatile components in the melting and film forming process. This is for foaming at the time of heat melting to reduce or avoid defects in the film and planar deterioration of the film surface.

Content of the volatile component at the time of melting a film forming material is 1 mass% or less, Preferably it is 0.5 mass% or less, More preferably, it is 0.2 mass% or less, More preferably, it is required to be 0.1 mass% or less. In the present invention, using a differential thermogravimetric measuring device (TG / DTA200 manufactured by Seiko Denshi Kogyo Co., Ltd.), heating loss from 30 ° C. to a temperature equivalent to that at the time of melt casting is obtained, and the amount is defined as the content of the volatile component. Doing.

It is preferable to remove the volatile component represented by the said water | moisture content, the said solvent, etc. before using into a film forming material, or at the time of heating. The method of removal can apply a well-known drying method, can be performed by methods, such as a heating method, a pressure reduction method, and a heating pressure reduction method, and can also be performed in air or in the atmosphere which selected nitrogen as an inert gas. When performing these well-known drying methods, it is preferable on the quality of a film to perform in the temperature range where a film formation material is not decomposed.

By drying before film forming, generation | occurrence | production of a volatile component can be reduced, and it can also divide and dry it in at least 1 sort (s) or more of mixtures or commercial things other than a cellulose ester among cellulose ester alone or a cellulose ester and a film forming material. As for a drying temperature, 70 degreeC or more is preferable. When there is a thing which has a glass transition temperature in the material to dry, when heating to the drying temperature higher than the glass transition temperature, since a material may fuse and handling becomes difficult, it is preferable that a drying temperature is below a glass transition temperature. When a some substance has a glass transition temperature, it is based on the glass transition temperature of the one with the lower glass transition temperature. More preferably, it is 70 degreeC or more, (glass transition temperature-5) degrees C or less, More preferably, it is 110 degreeC or more and (glass transition temperature-20) degrees C or less. Drying time becomes like this. Preferably it is 0.5 to 24 hours, More preferably, it is 1 to 18 hours, More preferably, it is 1.5 to 12 hours. If the drying temperature is too low, the removal rate of the volatile components is low, and it takes too long to dry. In addition, a drying process may be divided into two or more steps, for example, a drying process may include the preliminary drying process for storage of a material, and the drying process just before performing between film forming and 1 week ago. .

(Melt extrusion molding method)

Hereinafter, the manufacturing method of the cellulose ester film of this invention is demonstrated, taking the melt-extrusion molding method as an example.

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic flow sheet which shows the whole structure of the apparatus which enforces the manufacturing method of the cellulose ester film which concerns on this invention, and FIG. 2 is an enlarged view of a cooling roll part from a casting die.

In FIG. 1 and FIG. 2, in the manufacturing method of the cellulose ester film which concerns on this invention, after mixing film materials, such as a cellulose resin, using the extruder 1, the 1st cooling roll 5 from the casting die 4 is carried out. ) And extruded onto the first cooling roll (5), and externally contacted in the order of three cooling rolls in total: second cooling roll (7), third cooling roll (8). It cools and solidifies and it is set as the film 10. Subsequently, the film 10 peeled by the peeling roll 9 is then gripped by the winding device 16 after gripping both ends of the film by the stretching device 12 and stretching in the width direction. Moreover, in order to correct planarity, the touch roll 6 which presses a molten film on the surface of the 1st cooling roll 5 is provided. This touch roll 6 has elasticity on the surface, and forms the nip between the 1st cooling rolls 5. Details of the touch roll 6 will be described later.

In the manufacturing method of the cellulose ester film which concerns on this invention, conditions of melt extrusion can be performed similarly to the conditions used for thermoplastic resins, such as another polyester. It is preferable to dry material beforehand. It is preferable to dry the moisture to 1000 ppm or less, preferably 200 ppm or less, using a vacuum or reduced pressure drier, a dehumidifying hot air drier, or the like.

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 with a leaf disc type filter 2 to remove foreign substances.

When introducing into the extruder 1 from a feed hopper (not shown), it is preferable to prevent oxidative decomposition or the like under vacuum or reduced pressure but under an inert gas atmosphere.

When additives, such as a plasticizer, are not mixed previously, these may be kneaded in the middle of an extruder. In order to add uniformly, it is preferable to use mixing apparatuses, such as the static mixer 3 and the like.

In this invention, it is preferable to mix cellulose ester and additives, such as a deterioration inhibitor added as needed, before mixing, and it is more preferable to mix cellulose ester and an additive before heating. The mixing may be performed by a mixer or the like, or may be mixed in the cellulose resin production process as described above. When using a mixer, general mixers, such as a Henschel mixer and a ribbon mixer, can be used, such as a V-type mixer, a conical screw type mixer, and a horizontal cylindrical mixer.

After mixing the film forming material as described above, the mixture can be directly melted and formed using the extruder 1, but once the film forming material is pelletized, the pellet is melted in the extruder 1 You can also make a film. In addition, when the film forming material contains a plurality of materials having different melting points, a so-called solid semi-melt is first produced at a temperature at which only the low melting point material is melted, and the semi-melt is introduced into the extruder 1 to form a film. It is also possible. When the film-forming material contains a material that is likely to be thermally decomposed, a method of directly forming a film without producing pellets for the purpose of reducing the number of melting, or a method of forming a steel semi-melt as described above and then forming the film is preferable.

The extruder 1 may use a variety of extruders available on the market, but melt kneading extruders are preferred and may be single screw extruders or twin screw extruders. In the case of directly forming a film without producing pellets from a film forming material, it is preferable to use a twin screw extruder because proper kneading degree is required, but the shape of the screw can be changed into a screw type, a unimelt, a dulmadge even with a single screw extruder. Since proper kneading is obtained by changing to a kneading screw such as the above, it can be used. As the film constituent material, both a single screw extruder and a twin screw extruder can be used when a pellet or steel semi-melt is used.

In the extruder 1 and after the extrusion, the cooling step is preferably replaced with an inert gas such as nitrogen gas or reduced pressure to lower the concentration of oxygen.

In the extruder 1 and after the extrusion, the cooling step is preferably replaced with an inert gas such as nitrogen gas or by reducing the oxygen concentration.

Melting temperature of the film forming material in the extruder 1 varies depending on the viscosity of the film forming material, the discharge amount, the thickness of the sheet to be produced, and the like, but generally Tg or more and Tg + 130 ° C. with respect to the glass transition temperature Tg of the film. Hereinafter, Preferably it is Tg + 10 degreeC or more and Tg + 120 degreeC or less.

It is preferable that the temperature at the time of melt extrusion of this invention is 200 degreeC or more and 270 degrees C or less. More preferably, it is the range of 230-260 degreeC.

The melt viscosity at the time of extrusion is 1-10000 Pa.s, Preferably it is 10-1000 Pa.s. In addition, the shorter residence time of the film forming material in the extruder 1 is preferably within 5 minutes, preferably within 3 minutes, more preferably within 2 minutes. Although the residence time depends on the kind of extruder 1 and the conditions to extrude, it can shorten by adjusting material supply amount, L / D, screw rotation speed, the depth of the groove | channel of a screw, etc.

The shape, rotation speed, etc. of the screw of the extruder 1 are suitably selected according to the viscosity, discharge amount, etc. of a film forming material. In the present invention, the shearing rate in the extruder 1 is 1 / sec to 10000 / sec, preferably 5 / sec to 1000 / sec, and more preferably 10 / sec to 100 / sec.

As the extruder 1 which can be used for this invention, it 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 is extruded into a film form from the slit of the casting die 4. 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 carbide nitride, titanium nitride, super steel, ceramic (tungsten carbide, aluminum oxide, chromium oxide), etc. are sprayed or plated, and the surface processing is performed. For example, buffing, lapping using # 1000 or later grindstones, planar cutting using diamond grindstones # 1000 or greater (cutting direction is perpendicular to the flow direction of the resin), electrolytic polishing, electrolytic composite polishing, etc. Can be mentioned. The preferred material of the lip portion of the flexible die 4 is the same as that of the flexible die 4. Moreover, 0.5S or less is preferable and, as for the surface precision of a lip | rip part, 0.2S or less is more preferable.

The slit of this flexible die 4 is comprised so that the gap can be adjusted. This is shown in FIG. 3. Of the pair of ribs forming the slit 32 of the flexible die 4, one is a soft lip 33 which is easily deformed with low rigidity, and the other is a fixed lip 34. A plurality of heat bolts 35 are arranged at a constant pitch in the width direction of the flexible die 4, that is, in the longitudinal direction of the slit 32. Each heat bolt 5 is provided with a block 36 provided with an embedded electric heater 37 and a cooling medium passage, and each heat bolt 35 penetrates each block 36 vertically. The base part of the heat bolt 35 is fixed to the die main body 31, and the front end is in contact with the outer surface of the flexible lip 33. As shown in FIG. The input of the embedded electric heater 37 is increased or decreased while the block 36 is always air-cooled, thereby raising and lowering the temperature of the block 36, thereby thermally stretching the heat bolts 35 to form a flexible lip 33 ) To adjust the thickness of the film. A thickness meter is provided at a required portion of the die wake, and the web thickness information detected thereby is fed back to the control device, and the thickness information is compared with the set thickness information in the control device, and a signal of the correction control amount coming from the device is provided. It is also possible to control the power or the heating rate of the heating element of the heat bolt. The heat bolts preferably have a length of 20 to 40 cm and a diameter of 7 to 14 mm, and a plurality of, for example, tens of heat bolts are preferably arranged at a pitch of 20 to 40 mm. Instead of the heat bolt, a gap adjusting member mainly composed of a bolt for adjusting the slit gap by manually moving back and forth in the axial direction may be provided. The slit gap controlled by the gap adjusting member is usually 200 to 1000 mu m, preferably 300 to 800 mu m, more preferably 400 to 600 mu m.

The 1st to 3rd cooling rolls are seamless steel pipes whose thickness is about 20-30 mm, and the surface is mirror-finished. The inside which the piping which flows a cooling liquid is arrange | positioned, and is comprised so that heat may be absorbed from the film on a roll by the cooling liquid which flows through a piping. Among these first to third cooling rolls, the first cooling roll 5 corresponds to the rotary support of the present invention.

On the other hand, the touch roll 6 which contacts the 1st cooling roll 5 has elasticity, and is deformed along the surface of the 1st cooling roll 5 by the pressing force to the 1st cooling roll 5, A nip is formed between 1 roll 5. That is, the touch roll 6 corresponds to the pinching rotary body of this invention.

4, the schematic cross section of one Embodiment (henceforth Touch Roll A) of the touch roll 6 is shown. As shown in the figure, the touch roll A arrange | positions the elastic roller 42 in the inside of the flexible metal sleeve 41. As shown in FIG.

The metal sleeve 41 is made of stainless steel with a thickness of 0.3 mm, and has flexibility. If the metal sleeve 41 is too thin, the strength is insufficient, on the contrary, too thick, the elasticity is insufficient. In these respects, the thickness of the metal sleeve 41 is preferably 0.1 mm or more and 1.5 mm or less. The elastic roller 42 is provided in the shape of a roll by providing the rubber 44 on the surface of the inner cylinder 43 made of metal which can be rotated through the bearing. And when the touch roll A is pressed toward the 1st cooling roll 5, the elastic roller 42 presses the metal sleeve 41 to the 1st cooling roll 5, and the metal sleeve 41 and elasticity The roller 42 is deformed while corresponding to the shape harmonious with the shape of the 1st cooling roll 5, and forms a nip between it and a 1st cooling roll. The cooling water 45 flows in the space formed between the elastic roller 42 in the inside of the metal sleeve 41.

5 and 6 show a touch roll B which is another embodiment of the pinching rotary member. The touch roll (B) is flexible and has an outer cylinder 51 of a seamless stainless steel pipe (4 mm thick), and a highly rigid metal inner cylinder 52 arranged coaxially inside the outer cylinder 51. It is composed roughly. The cooling liquid 54 flows into the space 53 between the outer cylinder 51 and the inner cylinder 52. Specifically, the touch roll B has outer cylinder support flanges 56a and 56b attached to the rotation shafts 55a and 55b at both ends, and a thin metal outer cylinder 51 between the outer peripheral portions of these outer cylinder support flanges 56a and 56b. ) Is attached. Further, the fluid supply pipe 59 is arranged coaxially in the fluid discharge hole 58 formed in the shaft center portion of one rotation shaft 55a to form the fluid return passage 57, and the fluid supply pipe 59 is thin. It is connected and fixed to the fluid cylinder 60 arrange | positioned at the shaft center part in the metal outer cylinder 51. As shown in FIG. Inner cylinder support flanges 61a and 61b are attached to both ends of the fluid cylinder 60, respectively, and are about 15 to 20 mm from the outer peripheral portion of these inner cylinder support flanges 61a and 61b to the other end outer cylinder support flange 56b. The metal inner cylinder 52 which has the thickness of the grade is attached. Then, between the metal inner cylinder 52 and the thin metal outer cylinder 51, a flow space 53 for a coolant of about 10 mm is formed, and a flow path 53 is provided near the both ends in the metal inner cylinder 52. ) And outlet port 52a and inlet port 52b communicating with intermediate passages 62a and 62b outside the inner cylinder support flanges 61a and 61b are formed, respectively.

In addition, the outer cylinder 51 is designed to be thinned within the range in which the thin cylinder theory of elastic mechanics can be applied in order to have flexibility, flexibility, and resilience close to rubber elasticity. The flexibility evaluated by this thin cylinder theory is represented by the thickness t / roll radius r, and the smaller the t / r, the higher the flexibility. In this touch roll (B), flexibility is an optimal condition when t / r≤0.03. Usually, the touch roll generally used is roll diameter R = 200-500 mm (roll radius r = R / 2), roll effective width L = 500-1600 mm, and is horizontally long shape with r / L <1. And, as shown in FIG. 6, for example, in the case of roll diameter R = 300 mm and roll effective width L = 1200 mm, the suitable range of thickness t is 150 * 0.03 = 4.5 mm or less, but melt sheet width is 1300 mm. When the average linear pressure is clamped at 98 N / cm, the spring constant of the outer cylinder 51 is 3 mm as compared with the rubber roll of the same shape, so that the corresponding spring constant is the same, and the nip between the outer cylinder 51 and the cooling roll The nip width k in the roll rotation direction is also about 9 mm, showing a value nearly close to the nip width of about 12 mm of this rubber roll, and it can be seen that it can be pinched under the same conditions. Moreover, the curvature amount in this nip width k is about 0.05-0.1 mm.

Here, although t / r ≦ 0.03, in the case of general roll diameter R = 200 to 500 mm, especially when it is in the range of 2 mm ≦ t ≦ 5 mm, flexibility is sufficiently obtained, and thickness reduction by machining is also easy. It can implement and becomes the very practical range. If the thickness is 2 mm or less, high precision processing cannot be performed due to elastic deformation during processing.

Although this converted value of 2 mm <= t <= 5mm becomes 0.008 <= t / r <0.05 with respect to a general roll diameter, in practice, it is good to make thickness thick in proportion to a roll diameter on the condition of t / r_0.03. For example, it selects in the range of t = 2-3 mm at roll diameter: R = 200, and t = 4-5 mm at roll diameter: R = 500.

These touch rolls A and B are pressed toward the first cooling roll by pressing means (not shown). The value F / W (linear pressure) obtained by dividing the pressing force of the pressing means by the width W in the direction along the rotation axis of the first cooling roll 5 of F and the film in the nip is set to 9.8 to 147 N / cm. According to the present embodiment, a nip is formed between the touch rolls A and B and the first cooling roll 5, and the planarity may be corrected while the film passes through the nip. Therefore, compared with the case where a touch roll is comprised from a rigid body and a nip is not formed between a 1st cooling roll, since a film is pinched for a long time with a small linear pressure, planarity can be corrected more reliably. In other words, when the linear pressure is less than 9.8 N / cm, the die line cannot be sufficiently resolved. In contrast, when the linear pressure is greater than 147 N / cm, the film becomes difficult to pass through the nip, resulting in rather unevenness in the film thickness.

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 the case where the surface of the touch rolls are rubber, so that a film having high smoothness can be obtained. In addition, as a material of the elastic body 44 of the elastic roller 42, ethylene propylene rubber, neoprene rubber, silicone rubber, etc. can be used.

On the other hand, in order to satisfactorily eliminate the die line by the touch roll 6, it is important that the viscosity of the film when the touch roll 6 pinches the film is in an appropriate range. It is also known that the cellulose ester has a relatively large change in viscosity due to temperature. Therefore, in order to set the viscosity when the touch roll 6 pinches the cellulose ester film to an appropriate range, it is important to set the temperature of the film when the touch roll 6 pinches the cellulose film to an appropriate range. . And when this inventor sets the glass transition temperature of a cellulose-ester film to Tg, if the temperature T of the film just before the film is pinched by the touch roll 6 is set so that Tg <T <Tg + 110 degreeC may be satisfied. Found. If the film temperature T is lower than Tg, the viscosity of the film is too high to correct the die line. On the contrary, when the temperature T of the film is higher than Tg + 110 ° C., the film surface and the roll do not adhere uniformly, and thus the die line cannot be corrected. Preferably it is Tg + 10 degreeC <T2 <Tg + 90 degreeC, More preferably, it is Tg + 20 degreeC <T2 <Tg + 70 degreeC. In order to set the temperature of the film when the touch roll 6 pinches the cellulose ester film to an appropriate range, the melt extruded from the casting die 4 is contacted with the first cooling roll 5 from the first position P1. What is necessary is just to adjust the length L along the rotation direction of the 1st cooling roll 5 of the nip of the cooling roll 5 and the touch roll 6.

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. Moreover, it is preferable to make surface precision high, and as surface roughness, it is 0.3S or less, More preferably, you may be 0.01S or less.

In this invention, it discovered that the correction effect of the said die line is expressed more by reducing the part from the opening part (lip) of the casting die 4 to the 1st roll 5 to 70 kPa or less. Preferably the reduced pressure is from 50 to 70 kPa. Although there is no restriction | limiting in particular as a method of maintaining the pressure of the part from the opening part (lip) of the casting die 4 to 70 kPa or less, but the periphery of the roll from the casting die 4 is covered with a pressure-resistant member, There is a method such as reducing the pressure. At this time, it is preferable that the suction device is subjected to treatment such as heating with a heater so that the device itself does not become a place where the sublimate is attached. In the present invention, if the suction pressure is too small, the sublimation can not be sucked effectively, so it is necessary to set it to a suitable suction pressure.

In the present invention, the film-type cellulose ester in the molten state from the T die 4 is formed into a first roll (first cooling roll) 5, a second cooling roll 7, and a third cooling roll 8. It is solidified by cooling while adhering closely to and sequentially to obtain the unstretched cellulose ester film 10.

In embodiment of this invention shown in FIG. 1, the cooling solidified unstretched film 10 which peeled with the peeling roll 9 from the 3rd cooling roll 8 passes through the dancer roll (film tension adjusting roll) 11 It guides to the stretching machine 12, and extends the film 10 in a horizontal direction (width direction) from it. The molecules in the film are oriented by this stretching.

As a method of extending | stretching a film in the width direction, a well-known tenter etc. can be used preferably. Since the lamination with a polarizing film can be performed in roll form by making an extending | stretching direction into a width direction especially, it is preferable. By extending | stretching in the width direction, the slow axis of the cellulose ester film which consists of a cellulose ester film becomes a width direction.

In addition, the transmission axis of a polarizing film is also the width direction normally. By assembling the polarizing plates laminated so that the transmission axis of the polarizing film and the slow axis of the optical film are parallel to the liquid crystal display device, the display contrast of the liquid crystal display device can be increased and a good viewing angle can be obtained.

The glass transition temperature Tg of a film forming material can be controlled by changing the kind of material which comprises a film, and the ratio of the material which comprises. When manufacturing retardation film as a cellulose ester film, Tg is 120 degreeC or more, Preferably it is 135 degreeC or more. In a liquid crystal display device, in the display state of an image, the temperature environment of a film changes with the temperature rise of the apparatus itself, for example, the temperature rise derived from a light source. At this time, when Tg of a film is lower than the use environment temperature of a film, a big change will be made to the retardation value resulting from the orientation state of the molecule fixed inside the film by extending | stretching, and the dimensional shape as a film. If the Tg of the film is too high, the energy consumption for heating becomes high because the temperature becomes high when filming the film forming material, and also the decomposition of the material itself and the coloring according to the filming may occur, so that the Tg is 250 ° C. or less. desirable.

In addition, well-known heat setting conditions, cooling, and a relaxation process can be performed to an extending process, and it can adjust suitably so that it may have a characteristic calculated | required by the target optical film.

In order to provide the function of the retardation film and the function as a retardation film for the viewing angle expansion of a liquid crystal display device, the said extending process and the heat setting process are selected suitably and are performed. In the case of including such a drawing process and a heat setting process, the heating and pressing process is performed before these drawing process and heat setting process.

When manufacturing a retardation film as a cellulose ester film and combining the function of a polarizing plate protective film further, although refractive index control needs to be performed, the refractive index control can be performed by an extending | stretching operation, and extending | stretching operation is preferable. It is a way. Hereinafter, the stretching method will be described.

In the stretching step of the retardation film, the retardation Ro and Rt required can be controlled by stretching 1.0 to 2.0 times in one direction of the cellulose resin and 1.01 to 2.5 times in the direction orthogonal to this in the film plane. Here, Ro represents in-plane retardation, and Rt represents thickness direction retardation.

Retardation Ro and Rt are calculated | required by the following formula.

Ro = (nx-ny) xd

Rt = ((nx + ny) / 2-nz) × d

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

The refractive index of the optical film uses an Abbe refractometer (4T), the thickness of the film uses a commercially available micrometer, and the retardation value is an automatic birefringence cobra (KOBRA) -21ADH (manufactured by Oji Keisoku Kiki Co., Ltd.) It can measure each using etc.

Stretching can be performed sequentially or simultaneously with respect to the longitudinal direction of a film, and the direction orthogonal in this film surface, ie, the width direction. At this time, if the draw ratio in at least one direction is too small, a sufficient phase difference cannot be obtained. If the draw ratio is too large, stretching may be difficult and film breakage may occur.

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 improve by suppressing the width shrinkage of a film or extending | stretching also in the width direction. When extending | stretching in the width direction, distribution may arise in refractive index in the width direction. This distribution can be seen when the tenter method is used, and the film is drawn in the width direction, whereby a shrinkage force is generated in the center portion of the film, and an end portion is fixed, which is called a so-called boeing phenomenon. Also in this case, by extending | stretching to a casting | flow_spread direction, a bowing phenomenon can be suppressed and distribution of the phase difference of the width direction can be reduced.

By extending | stretching to the biaxial direction which is perpendicular to each other, the film thickness variation of the film obtained can be reduced. If the film thickness variation of the retardation film is too large, the retardation becomes uneven, and when used in a liquid crystal display device, unevenness such as coloring may become a problem.

It is preferable to make the film thickness variation of a cellulose ester film into the range of +/- 3% and +/- 1%. For the above purposes, the method of stretching in the biaxial directions perpendicular to each other is effective, and the stretching ratios in the biaxial directions perpendicular to each other are finally 1.0 to 2.0 times in the flexible direction and 1.01 to 2.5 times in the width direction, respectively. It is preferable to set it as the range of, and it is more preferable to carry out in the range of 1.01 to 1.5 times in the casting | flow_spread direction, and 1.05 to 2.0 times in the width direction in order to acquire the required retardation value.

When the absorption axis of the polarizer exists in the longitudinal direction, the transmission axis of the polarizer coincides in the width direction. In order to obtain a long polarizing plate, it is preferable that the retardation film is stretched to obtain a slow axis in the width direction.

When using the cellulose ester which acquires positive birefringence with respect to a stress, the slow axis of a retardation film can be provided in the width direction by extending | stretching in the width direction from the structure mentioned above. In this case, in order to improve the display quality, it is preferable that the slow axis of the retardation film is in the width direction, and in order to obtain the target retardation value

Expression (stretching ratio in the width direction)> (drawing ratio in the flexible direction)

Is satisfied.

After extending | stretching, the edge part of a film is slit to the width which becomes a product by the slitter 13, and it cuts out, and then knurling process (embossing process) is performed by the knurling processing apparatus which consists of the embossing ring 14 and the back roll 15. It is carried out at both ends and wound up by the winding device 16, and the generation | occurrence | production of the bonding and abrasion in the cellulose-ester film (circle winding) F is prevented. In the knurling processing method, a metal ring having a pattern of irregularities on its side can be processed by heating or pressing. In addition, since the holding part of the clip of film both ends is deformed normally and cannot be used as a film product, it is excised and recycled as a raw material.

Next, the winding process of a film winds a film in a winding roll, keeping the shortest distance between the outer peripheral surface of a cylindrical winding film and the outer peripheral surface of the mobile conveyance roll immediately before this. Moreover, in front of a winding roll, means, such as an antistatic blower which removes or reduces the surface potential of a film, are provided.

The winding machine according to the production of the optical film of the present invention may be generally used, and may be wound by a winding method such as a normal tension method, a constant torque method, a tapered tension method, or a program tension adjustment method having a constant internal stress. Moreover, it is preferable that the initial winding tensions at the time of winding up of an optical film are 90.2-300.8 N / m.

In the winding-up process of the film in the method of this invention, it is preferable to wind up a film in the environment conditions of 20-30 degreeC of temperature, and 20-60% RH of humidity. Thus, by specifying the temperature and humidity in the winding process of a film, the tolerance of the humidity change of thickness direction retardation Rt improves.

If the temperature in the winding step is less than 20 ° C., wrinkles may occur, which may not be practical because of deterioration of the film winding quality. If the temperature in the winding process of the film exceeds 30 ° C., wrinkles may occur, too, and thus it is not preferable because it is not practical for the film winding quality deterioration.

Moreover, when the humidity in the winding process of a film is less than 20% RH, it is easy to charge and it is unpreferable for practical use because of film winding quality deterioration. When the humidity in the winding process of the film exceeds 60% RH, the winding quality, the bonding failure, and the transportability deteriorate, which is not preferable.

The winding core at the time of winding the optical film in a roll shape may be any material as long as it is a cylindrical core. Preferably, it is a hollow plastic core, and any plastic material may be any heat-resistant plastic that can withstand the heat treatment temperature. And resins such as xylene resin, melamine resin, polyester resin and epoxy resin. Moreover, the thermosetting resin reinforced by fillers, such as glass fiber, is preferable. For example, a hollow plastic core: a 6-inch outer diameter made of FRP (hereinafter, inch represents 2.54 cm) and a winding core having an inner diameter of 5 inches are used.

It is preferable that the winding number to these winding cores is 100 windings or more, It is more preferable that it is 500 windings or more, It is preferable that the winding thickness is 5 cm or more, It is preferable that the width of a film base material is 80 cm or more, It is especially 1 m or more desirable.

Although the thickness of the film | membrane of the optical film which concerns on this invention changes with a use purpose, 10-500 micrometers is preferable as a finishing film. In particular, a minimum is 20 micrometers or more, Preferably it is 35 micrometers or more. An upper limit is 150 micrometers or less, Preferably it is 120 micrometers or less. A particularly preferred range is 25 to 90 μm. In the case where the optical film of the present invention is a retardation film and also serves as a polarizing plate protective film, when the film is thick, the polarizing plate after polarizing plate processing becomes too thick and is not particularly suitable for the purpose of thin and lightweight for liquid crystal displays used in notebook computers or mobile electronic devices. not. On the other hand, when a film is thin, it is difficult to express retardation as a retardation film, in addition, since the moisture permeability of a film becomes high and the ability to protect a polarizer from humidity falls, it is unpreferable.

When the slow axis or fast axis of a retardation film exists in a film surface, and makes the angle with the film forming direction into (theta) 1, (theta) 1 may be -1 to +1 degree, Preferably it is -0.5 to +0.5 degree.

This (theta) 1 can be defined as an orientation angle, and measurement of (theta) 1 can be performed using automatic birefringence cobra-21ADH (made by Oji Keisoku Kiki Co., Ltd.).

θ1 satisfying the above relationship contributes to obtaining high luminance in the display image, suppressing or preventing light leakage, and contributing to faithful color reproduction in the color liquid crystal display device.

When the retardation film is used in the multi-domainized VA mode, the arrangement of the retardation film is disposed in the region with the fast axis of the retardation film at θ1, thereby contributing to the improvement of display image quality, and in the MVA mode as the polarizing plate and the liquid crystal display device. When it does, the structure shown in FIG. 7 can be taken, for example.

In Fig. 7, 21a and 21b are protective films, 22a and 22b are retardation films, 25a and 25b are polarizers, 23a and 23b are slow axis directions of the film, 24a and 24b are the transmission axis directions of the polarizers, and 26a and 26b are polarizers. And 27 denote a liquid crystal cell, and 29 denote a liquid crystal display device.

It is preferable to adjust the retardation Ro distribution of the in-plane direction of a cellulose ester film to 5% or less, More preferably, it is 2% or less, Especially preferably, it is 1.5% or less. Moreover, although it is preferable to adjust the retardation Rt distribution of the thickness direction of a film to 10% or less, More preferably, it is 2% or less, Especially preferably, it is 1.5% or less.

In the retardation film, the smaller the variation in distribution of the retardation value is preferable, and when the polarizing plate containing the retardation film is used for the liquid crystal display device, the smaller the variation in the retardation distribution is preferable in terms of preventing color unevenness. .

In-plane retardation Ro to adjust the retardation film so as to have a retardation value suitable for the improvement of the display quality of the liquid crystal cell in VA mode or TN mode, and in particular to divide it into the multi-domain as VA mode so that it is preferably used in MVA mode. Is required to be greater than 30 nm, 95 nm or less, and the thickness direction retardation Rt to be greater than 70 nm and to a value of 400 nm or less.

Said in-plane retardation Ro is a cross nicol based on when it observes from the normal direction of a display surface, when two polarizing plates are arrange | positioned in cross nicol and a liquid crystal cell is arrange | positioned between polarizing plates, for example in FIG. When in the state, when viewed obliquely from the normal of the display surface, a deviation from the cross nicol state of the polarizing plate occurs, and this mainly compensates for light leakage, which is a factor. Thickness direction retardation contributes mainly to the compensation of the birefringence of the liquid crystal cell seen when it is obliquely similarly when a liquid crystal cell is black display state in said TN mode or VA mode, especially MVA mode.

As shown in FIG. 7, in the liquid crystal display device, when the polarizing plates are arranged on the upper and lower sides of the liquid crystal cell, 22a and 22b in the drawing can select the distribution of the thickness direction retardation Rt and satisfy the above range. While the total value of both of the thickness direction retardation Rt is larger than 140 nm, it is preferable to be 500 nm or less. At this time, it is preferable in the productivity improvement of an industrial polarizing plate that both in-plane retardation Ro of 22a and 22b and thickness direction retardation Rt are the same. Especially preferably, in-plane retardation Ro is 65 nm or less, larger than 35 nm, and thickness direction retardation Rt is larger than 90 nm and 180 nm or less, and is applied to the liquid crystal cell of MVA mode by the structure of FIG.

In the liquid crystal display device, a TAC film having an in-plane retardation Ro = 0 to 4 nm and a thickness direction retardation Rt = 20 to 50 nm and a thickness of 35 to 85 µm as an example of a commercially available polarizing plate protective film on one polarizing plate is an example. For example, when it is used at the position of 22b in FIG. 7, the in-plane retardation Ro is greater than 30 nm and 95 nm or less in the polarizing film disposed on the other polarizing plate, for example, the phase difference film disposed in 22a of FIG. If the thickness direction retardation Rt is larger than 140 nm and 400 nm or less, the display quality is improved and the production of the film is also preferable.

<< recycling >>

In the film forming step, it is preferable that the clip gripping portions at both ends of the cut film are pulverized or subjected to granulation as necessary, and then reused as raw materials for films of the same variety or as raw materials for films of different varieties.

<< functional layer >>

Functionality of the optical film of the present invention, such as an antistatic layer, a transparent conductive layer, a hard coating layer, an antireflection layer, an antifouling layer, an active layer, an easily adhesive layer, an antiglare layer, a gas barrier layer, an optical compensation layer, and the like before and / or after stretching. The layer can be laid. In particular, it is preferable to provide at least one layer selected from an antistatic layer, a hard coating layer, an antireflection layer, an easily adhesive layer, an antiglare layer, and an optical compensation layer. At this time, various surface treatments, such as a corona discharge treatment, a plasma treatment, and a chemical liquid treatment, can be performed as needed.

<< polarizing plate >>

When using the optical film which concerns on this invention as a polarizing plate protective film, the manufacturing method of a polarizing plate is not specifically limited, It can manufacture by a general method. It is preferable to bond together the back surface side of the optical film of this invention by alkali saponification treatment, and to the at least one surface of the polarizing film produced by immersion stretching in the iodine solution using the fully saponified polyvinyl alcohol aqueous solution. . The optical film of this invention can also be used for the other surface, and another polarizing plate protective film can also be used. For the optical film of the present invention, a commercially available cellulose ester film can be used for the polarizing plate protective film used for the other side. For example, as a commercially available cellulose ester film, KC8UX2M, KC4UX, KC5UX, KC4UY, KC8UY, KC12UR, KC8UCR-3, KC8UCR-4, KC4FR-1, KC8UY-HA, KC8UX-RHA (above, Konica Minolta Opto Corporation) Production) and the like. Or it is also preferable to use the polarizing plate protective film which also serves as the optical compensation film which has the optically anisotropic layer formed by orienting liquid crystal compounds, such as a discotic liquid crystal, a rod-shaped liquid crystal, and a cholesteric liquid crystal. For example, an optically anisotropic layer can be formed by the method described in Japanese Patent Application Laid-Open No. 2003-98348. By using in combination with the optical film of this invention, the polarizing plate which is excellent in planarity and has a stable viewing angle enlargement effect can be obtained. Alternatively, films such as cyclic olefin resins, acrylic resins, polyesters, and polycarbonates other than cellulose ester films may be used as polarizing plate protective films on the other side.

Instead of the alkali treatment, an easy-adhesion process as described in Japanese Patent Application Laid-Open No. Hei 6-94915 and 6-118232 may be performed to perform polarizing plate processing.

The polarizing film, which is a main component of the polarizing plate, is a device which allows only light of a polarization plane in a certain direction to pass through. A representative polarizing film currently known is a polyvinyl alcohol-based polarizing film, which is obtained by dyeing iodine on a polyvinyl alcohol-based film. Some dyes are colored. The polarizing film forms a polyvinyl alcohol aqueous solution, uniaxially stretches this dye, or dyes and uniaxially stretches after dyeing, and then preferably a durable treatment with a boron compound is used. The film thickness of a polarizing film is 5-40 micrometers, Preferably it is 5-30 micrometers, Especially preferably, it is 5-20 micrometers. On the surface of the said polarizing film, one surface of the cellulose ester film of this invention is bonded together, and a polarizing plate is formed. Preferably, it joins by the water-based adhesive which has a fully saponified polyvinyl alcohol etc. as a main component.

Since the polarizing film is stretched in the uniaxial direction (usually in the longitudinal direction), when the polarizing plate is placed under a high temperature and high humidity environment, the stretching direction (usually in the longitudinal direction) is reduced, and in the stretching and vertical direction (usually in the width direction). To stretch. As the film thickness of the polarizing plate protective film becomes thinner, the stretching ratio of the polarizing plate becomes larger, and in particular, the amount of shrinkage in the stretching direction of the polarizing film is large. Usually, since the extending | stretching direction of a polarizing film bonds with the casting | flow_spread direction (MD direction) of the film for polarizing plate protection, when thinning the film for polarizing plate protection, it is especially important to suppress the elongation rate of a casting direction. Since the optical film of this invention is very excellent in dimensional stability, it is used suitably as such a polarizing plate protective film.

That is, even if the optical film of this invention does not increase a wavy nonuniformity by the durability test on 60 degreeC and 90% RH conditions, even if it is a polarizing plate which has an optical compensation film in the back side, a viewing angle characteristic fluctuates after durability test. Good visibility can be provided without.

The polarizing plate is composed of a polarizer and a protective film for protecting both surfaces thereof, and a protective film is bonded to one side of the polarizing plate and a separate film is bonded to the opposite side of the polarizing plate. A protective film and a separate film are used for the purpose of protecting a polarizing plate at the time of a polarizing plate shipment, a product inspection, etc. In this case, a protective film is bonded in order to protect the surface of a polarizing plate, and is used for the opposite surface side of the surface which bonds a polarizing plate to a liquid crystal plate. In addition, a separator film is used for the purpose of covering the contact bonding layer bonded to a liquid crystal plate, and is used for the surface side which bonds a polarizing plate to a liquid crystal cell.

<< liquid crystal display device >>

The polarizing plate including the polarizing plate protective film (including the case where it also serves as a phase difference film) using the optical film of this invention can express high display quality compared with the normal polarizing plate, and is especially a multi-domain type liquid crystal display device, Preferably, the birefringence mode is suitable for use in a multi-domain type liquid crystal display device.

The polarizer of the present invention can be used for MVA (multi-area vertical alignment) mode, PVA (imitation vertical alignment) mode, CPA (continuous fillwheel alignment) mode, OCB (optical compensation bend) mode, IPS (plane alignment switching) mode, etc. It is not limited to arrangement | positioning of a specific liquid crystal mode and a polarizing plate.

The liquid crystal display device is also applied as a device for colorization and moving picture display, and the display quality is improved by the present invention, and the improvement of contrast and the resistance of the polarizing plate are improved, thereby making it possible to faithfully display a moving picture without fatigue.

In the liquid crystal display device which contains at least the polarizing plate containing retardation film, one polarizing plate containing the polarizing plate protective film as an optical film of this invention is arrange | positioned with respect to a liquid crystal cell, or two sheets are arrange | positioned at both sides of a liquid crystal cell. . At this time, it can contribute to the improvement of display quality by using so that the polarizing plate protective film side contained in a polarizing plate may face the liquid crystal cell of a liquid crystal display device. In FIG. 7, the films of 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 using the polarizing plate of this invention for a liquid crystal display device, what is necessary is just to make at least one polarizing plate of the polarizing plate of a liquid crystal display device as the polarizing plate of this invention. By using the polarizing plate of this invention, display quality can improve and the liquid crystal display device excellent in viewing angle characteristic can be provided.

In the polarizing plate of this invention, the polarizing plate protective film of a cellulose derivative is used for the surface on the opposite side to the polarizing plate protective film as an optical film of this invention from a polarizer, and a general purpose TAC film etc. can be used. The polarizing plate protective film located on the side far from the liquid crystal cell can also arrange other functional layers in improving the quality of the display device.

For example, although it can also adhere to the film which contains a well-known functional layer as a structure, or the surface of the polarizing plate of this invention for reflection prevention, anti-glare, anti-scratches, dust adhesion prevention, and brightness improvement, it is limited to these It is not.

In general, in the retardation film, it is required to obtain stable optical characteristics with little variation in the retardation Ro or Rt described above. In particular, in the birefringent mode liquid crystal display device, these fluctuations may cause an unevenness of the image.

Since the long polarizing plate protective film produced by the melt casting film forming method according to the present invention is mainly composed of cellulose esters, an alkali treatment process can be utilized by utilizing saponification inherent in cellulose esters. This can be bonded with a polarizing plate protective film using the fully saponified polyvinyl alcohol aqueous solution like the conventional polarizing plate protective film, when resin which comprises a polarizer is polyvinyl alcohol. For this reason, this invention is excellent in the point which the conventional polarizing plate processing method can be applied, and is especially excellent in the point which a long roll polarizing plate is obtained.

The manufacturing effect obtained by this invention becomes more remarkable especially in the long winding of 100 m or more, and when it is extended to 1500 m, 2500 m, and 5000 m, the manufacturing effect of polarizing plate manufacture is acquired.

For example, in manufacturing a polarizing plate protective film, in consideration of productivity and transportability, the roll length is 10 to 5000 m, preferably 50 to 4500 m, and the width of the film at this time is the width of the polarizer and the production line. A suitable width can be selected. The film may be prepared in a width of 0.5 to 4.0 m, preferably 0.6 to 3.0 m, and rolled into a roll to be used for polarizing plate processing. Further, a film having a multiply or larger width of a desired width may be prepared and wound on a roll, and then cut. It is also possible to obtain a roll having a desired width and to use such a roll for polarizing plate processing.

In manufacturing a polarizing plate protective film, you may coat functional layers, such as an antistatic layer, a hard coat layer, an active layer, an adhesive layer, an anti-glare layer, a barrier layer, before and / or after extending | stretching. At this time, various surface treatments, such as a corona discharge treatment, a plasma treatment, and a chemical liquid treatment, can be performed as needed.

The composition containing the cellulose ester from which additive concentrations, such as a plasticizer, an ultraviolet absorber, and a mat agent, differs may be coextruded, and a cellulose ester film of a laminated structure can also be manufactured. For example, a cellulose ester film of the same structure as the skin layer / core layer / skin layer can be made. For example, there are many matting agents in a skin layer, or can put only a skin layer. A plasticizer and a ultraviolet absorber can be put in a core layer more than a skin layer, and can also be put only in a core layer. In addition, the kind of the plasticizer and the ultraviolet absorber may be changed in the core layer and the skin layer. For example, a low volatility plasticizer and / or an ultraviolet absorber may be included in the skin layer, and the plasticizer having excellent plasticity or ultraviolet absorbency may be included in the core layer. Excellent ultraviolet absorbers may also be added. The glass transition temperature of a skin layer and a core layer may differ, and it is preferable that the glass transition temperature of a core layer is lower than the glass transition temperature of a skin layer. At this time, the glass transition temperature of both a skin and a core is measured, and the average value computed from these volume fractions can also be defined as said glass transition temperature Tg, and can be handled similarly. The viscosity of the melt containing cellulose ester during melt casting may also be different in the skin layer and the core layer, the viscosity of the skin layer> the viscosity of the core layer, or the viscosity of the core layer ≥ the viscosity of the skin layer. have.

The cellulose ester film according to the present invention has a dimensional stability of less than ± 2.0% when the dimensional stability is based on the dimensions of the film left at 23 ° C. and 55% RH for 24 hours, at 80 ° C. and 90% RH. Preferably it is less than 1.0%, More preferably, it is less than 0.5%.

When using the cellulose ester film which concerns on this invention for a polarizing plate protective film as retardation film, if the retardation film itself is a fluctuation within the said range, since the absolute value and orientation angle of retardation as a polarizing plate do not differ from original setting, display quality It is preferable because it does not cause a decrease in the improvement ability of or cause deterioration of the display quality.

Although an Example is given to the following and this invention is concretely demonstrated to it, this invention is not limited to these.

&Lt; Synthesis of cellulose ester >

(Synthesis of cellulose ester 1)

80 g of acetic acid and 30 g of propionic acid were added to 30 g of cellulose (dissolution pulp manufactured by Nippon Seishi Co., Ltd.), and the mixture was stirred at 54 ° C for 30 minutes. After the mixture was cooled, 7 g of acetic anhydride, 120 g of propionic anhydride and 1.2 g of sulfuric acid cooled in an ice bath were added to effect esterification. In esterification, stirring was performed for 150 minutes, adjusting so that it may not exceed 40 degreeC. 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 the excess anhydride. 90 g of acetic acid and 30 g of water were added and the mixture was stirred for 1 hour while maintaining the temperature of the reaction solution at 40 ° C. The mixture was emptied in an aqueous solution containing 2 g of magnesium acetate and stirred for a while, followed by filtration and washing with water sufficiently until the pH of the washing liquid became neutral, followed by drying to obtain cellulose ester 1. About the obtained cellulose ester 1, substitution degree (X) of an acetyl group and substitution degree (Y) of a propionyl group were calculated | required by the method of the above-mentioned ASTM D817-96, It was X = 1.31 and Y = 1.23. . When the number average molecular weight was determined by gel permeation chromatography under the above-mentioned conditions, it was 66000, and the 1% mass reduction temperature Td (1.0) was measured at 292 ° C under air using a differential thermogravimetric analyzer. It was.

(Synthesis of cellulose esters 2 to 15)

Synthesis | combination operation similar to the synthesis of cellulose ester 1 was performed except having changed the usage-amount of acetic acid, acetic anhydride, propionic acid, and propionic anhydride with respect to the synthesis | combination of cellulose ester 1, and cellulose esters 2-15 were obtained.

Substitution degree (X) of acetyl group, substitution degree (Y) of propionyl group, value of X + Y, value of XY, number average molecular weight (Mn), and 1% mass reduction for each of cellulose esters 1 to 15 The value of the temperature Td (1.0) is shown in Table 1.

(Synthesis of Comparative Cellulose Esters 16 to 25)

Here, the cellulose esters 16-23 of the comparison were synthesize | combined by performing the same synthetic | combination operation as the cellulose ester 1 except having changed the usage-amount of acetic acid, acetic anhydride, propionic acid, and propionic anhydride with respect to the synthesis | combination of cellulose ester 1. On the other hand, the cellulose esters 24 and 25 of the comparison are the same synthesis | combination as cellulose ester 1 except using the combination of acetic acid, acetic anhydride, butyric acid, and butyric anhydride with respect to the synthesis | combination of cellulose ester 1, and changing these usage amounts further. It synthesize | combined by performing operation.

For each of the cellulose esters 16 to 25 of the obtained comparisons, the degree of substitution (X) of the acetyl group, the degree of substitution (Y) of the propionyl group, the value of X + Y, the value of XY or the degree of substitution (Z) of the butyryl group , The value of X + Z, the value of XZ, the number average molecular weight (Mn), and the value of the 1% mass reduction temperature Td (1.0) are shown in Table 1.

Example 1

[Production of Optical Film Having a Cellulose Ester (Hereinafter, simply referred to as Cellulose Ester Film) Sample 1-1]

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

Cellulose ester 1 100 parts by mass

Plasticizer-A 8 parts by mass

Irganox 1010 (manufactured by Ciba Specialty Chemicals) 0.50 parts by mass

0.25 parts by mass of GSY-P101 (manufactured by Sakai Chemical Industries, Ltd.)

0.25 parts by mass of GS (Sumitomo Chemical Co., Ltd.)

Tinuvin 928 (manufactured by Ciba Specialty Chemicals) 1.5 parts by mass

The cellulose ester 1 was dried at 130 degreeC under reduced pressure for 4 hours, cooled to room temperature, and the additive was mixed. The mixture was pelletized by melt mixing at 230 ° C. using a twin screw extruder. In addition, the glass transition temperature Tg of this pellet was 140 degreeC.

The pellets were melted at 250 ° C. under a nitrogen atmosphere, extruded from the casting die 4 onto the first cooling roll 5, and the film was pressed between the first cooling roll 5 and the touch roll 6. Molded. Moreover, 0.2 mass part of silica particles, aerosil NAX50 (made by Nippon Aerosil Co., Ltd.), and KE-P100 (made by Nippon Shokubai Co., Ltd.) were 0.02 mass as a slip agent from the hopper opening part of the intermediate part of the extruder 1. Add to add.

The heat bolt was adjusted so that the width | variety of the gap of the casting die 4 might be 0.5 mm within 30 mm from the width direction edge part of a film, and 1 mm in other places. Touch roll A was used as a touch roll, and 80 degreeC water was made to flow inside as cooling water.

1st cooling roll 5 rotation direction upstream of the nip of the 1st cooling roll 5 and the touch roll 6 from the position P1 which resin extruded from the casting die 4 contact | connects the 1st cooling roll 5 The length L along the peripheral surface of the 1st cooling roll 5 to the position P2 of a stage was set to 20 mm. Thereafter, the touch roll 6 was spaced apart from the first cooling roll 5, and the temperature T of the melted portion immediately before being pressed by the nip between the first cooling roll 5 and the touch roll 6 was measured. In the present embodiment, the temperature T of the molten portion immediately before being pressed by the nip between the first cooling roll 5 and the touch roll 6 is 1 mm upstream from the nip upstream end P2, and the thermometer (Anritsu) It measured with HA-200E) manufactured by Keiki Corporation. In the present Example, the measurement result showed that the temperature T was 141 degreeC. The linear pressure with respect to the 1st cooling roll 5 of the touch roll 6 was 14.7 N / cm. Furthermore, after introduction into the tenter and stretching 1.3 times at 160 ° C in the width direction, it is cooled to 30 ° C with 3% relaxation in the width direction, then opened from the clip, the clip grip is cut out, and the width 10 is applied to both ends of the film. mm and a knurling process of 5 micrometers in height were performed, and it wound up to the core by 220 N / m of winding tensions, and 40% of taper. Moreover, the extrusion amount and the take-out speed were adjusted so that a film might be set to 80 micrometers in thickness, and the film was slit and wound up so that the film width of finishing might be 1430 mm width. The size of the core was 152 mm in inner diameter, 165 to 180 mm in outer diameter, and 1550 mm in length. As this core material, the prepreg resin in which epoxy resin was impregnated into glass fiber and carbon fiber was used. The core surface was coated with an epoxy conductive resin, the surface was polished, and the surface roughness Ra was finished to 0.3 µm. In addition, the winding length was 2500 m. Let the film master sample of this invention be a cellulose ester film master 1-1. In addition, some cellulose-ester films are cut out from this film original sample, and let this be the cellulose-ester film 1-1 of this invention.

[Production of Cellulose Ester Films 1-2 to 1-25]

In the production of cellulose ester film master 1-1, the cellulose ester film masters 1-2 to 1-15 of the present invention and the cellulose ester film of the comparison were made in the same manner except that the kind of cellulose ester was changed as shown in Table 1. Discs 1-16 to 1-25 were prepared. In addition, the addition amount of the cellulose ester replacing the used cellulose ester 1 was made into the mass part similar to the cellulose ester 1. In addition, as described above, some cellulose ester films are cut out from the cellulose ester film masters 1-2 to 1-15 of the present invention and the cellulose ester film masters 1-16 to 1-25 of the comparative examples, respectively, and these are the cellulose esters of the present invention, respectively. It is set as the film 1-2-1-15, and the cellulose ester film 1-16-1-25 of the comparison.

The structures of Plasticizer-A, Irganox 1010, GSY-P101, Smeizer GS, and Tinuvin 928 used in Example 1 are as follows. In addition, cellulose esters 1-23 are cellulose acetate propionate, and cellulose esters 24 and 25 are cellulose acetate butyrate.

The following method was evaluated about the obtained cellulose ester film original sample and cellulose ester film sample. The results are shown in Table 2.

<< U-shaped breakdown, core transfer >>

The wound cellulose ester film original sample was double wrapped with a polyethylene sheet, and stored for 30 days under 25 degreeC and 50% by the preservation method as shown to FIG. 8 (a), (b), (c). Then, the polyethylene sheet was taken out from the box, the polyethylene sheet was unfolded, the tube of a fluorescent lamp lit on the surface of the film master sample was reflected, and its deformation or fine confusion was observed, and it was classified by the following level as an evaluation of the U-shaped failure.

(Double-circle): fluorescent lamp looks straight

△: fluorescent light partially bent

×: Fluorescent light is spotted

In addition, the film disk sample after storage was rewound to measure the number of meters of core windings in which a point-like deformation of 50 µm or more or a band-shaped deformation in the width direction was clearly observed. It was done.

◎: less than 15 m from the core part

○: less than 15 to 30 m from the core part

△: less than 30 to 50 m from the core part

×: 50 m or more from the core part

<< winding start wrinkle >>

The winding film was wound around the core, and when wrinkles occurred at the winding start portion and the defect became defective, the film was removed from the winding core and wound again. The number of defects at this time was counted. This operation was carried out ten times to obtain an average value, and ranking was performed at the following levels.

◎: 0 or more times and less than 1 time

○: 1 or more times less than 3 times

△: 3 or more times less than 5 times

×: 5 or more times

<< flatness >>

Each cellulose ester film sample is cut out to a size of 90 cm in width and 100 cm in length, and 5 50W fluorescent lamps are arranged and fixed at a height of 1.5 m so as to shine at a 45 ° angle to the sample table, and each film is placed on the sample table. The sample was placed and the unevenness reflected by the film surface was visually determined as follows. By this method, determination of "drag" and "wrinkle" can be made.

◎: All five fluorescent lamps appear straight

○: some fluorescent light bends

(Triangle | delta): A fluorescent lamp looks a little bent overall.

×: fluorescent lamp looks large

<< evaluation of curling property >>

A 5 mm × 5 cm cellulose ester film sample was cut out and left for 24 hours in a constant temperature and humidity chamber at a temperature of 28 ° C. and 55% RH, and then placed on a plate and curvature having a curve matching the sample using a curvature scale. The radius was calculated | required and the magnitude | size of the curling and the handling goodness were ranked as follows.

Radius of curvature: radius of a circle with a curve matching 1 / sample (1 / m)

◎: 0 to less than 5

○: less than 5 to 10

△: 0 to less than 30

×: 30 or more

Here, ◎, ○ are easy to handle, but △ or less, handling becomes very difficult.

<< variation coefficient (CV) of retardation >>

The retardation is measured at intervals of 1 cm in the width direction of the cellulose ester film, and is represented by the coefficient of variation (CV) of the retardation obtained from the following equation. For the measurement, using an automatic birefringence cobra 21ADH (manufactured by Oji Keisokuki Co., Ltd.), three-dimensional scanning at 1 cm intervals in the width direction of the sample at a wavelength of 590 nm under an environment of 28 ° C and 55% RH. The refractive index was measured and the measured value was substituted into the following formula to obtain.

In-plane retardation Ro = (nx-ny) × d

Thickness Direction Retardation Rt = ((nx + ny) / 2-nz) × d

Where d is the thickness of the film (nm), the refractive index nx (the largest refractive index in the plane of the film, also called the refractive index in the slow axis direction), ny (the refractive index in the direction perpendicular to the slow axis in the film plane), nz (thickness) Refractive index of the film in the direction). The standard deviation by the (n-1) method was calculated | required about the obtained in-plane and thickness direction retardation, respectively. The retardation distribution calculated | required the coefficient of variation (CV) shown below, and made it into the index. In actual measurement, it set to 130-140 as n.

Coefficient of variation (CV) = standard deviation / retardation mean

(Double-circle): Variation (CV) is less than 1.5%

○: The variation (CV) is 1.5% or more but less than 5%

(Triangle | delta): 5% or more and less than 10% of fluctuations (CV)

X: 10% or more of variation (CV)

<< saponification treatment aptitude >>

A 120-micrometer-thick polyvinyl alcohol film was immersed in the aqueous solution containing 1 mass part of iodine, 2 mass parts of potassium iodide, and 4 mass parts of boric acid, and it extended | stretched 4 times at 50 degreeC, and manufactured the polarizer. The cellulose-ester film sample was alkali-treated with 40 degreeC 2.5N- sodium hydroxide aqueous solution for 60 second, washed with water further, and the surface was saponified. On both sides of the polarizer, the alkali-treated surface of the cellulose ester film was bonded on both sides with a fully saponified polyvinyl alcohol 5% aqueous solution as an adhesive to prepare an evaluation polarizing plate to which a protective film was adhered.

Subsequently, this polarizing plate for evaluation was processed at 80 degreeC and 90% RH for 1200 hours, the bonding state of a polarizer and a protective film was observed, and it ranked by the following reference | standard.

◎: no peeling

(Circle): Although a peeling is seen slightly, practically no problem level

(Triangle | delta): The level which shows a peeling slightly and becomes a problem in practical use

X: peeling occurrence

Here, it was judged that (circle) or more is a level which is satisfactory practically in saponification process suitability.

<< polarizer durability test (white spot) >>

Two 500 mm x 500 mm polarizing plate samples prepared at the time of saponification treatment aptitude were subjected to heat treatment (conditions: left at 90 ° C for 120 hours), and the larger one of the vertical or horizontal center line portions when placed in an orthogonal state. The length of the white spot part of the side edge was measured, and the ratio with respect to the side length (500 mm) was computed, and it determined as follows according to the ratio. The white spots at the edges can be visually determined by the edge portions of the polarizing plates which do not pass light in the orthogonal state to pass the light. In the state of the polarizing plate, the display of the edge portion becomes invisible.

◎: white spot of edge is less than 5%

○: white spots at the edges of 5% or more and less than 10%

(Triangle | delta): The white spot of an edge is 10% or more and less than 20%

X: 20% or more of the white spots of the edges

Here, it judged that (circle) abnormality is a level which is satisfactory practically.

As described above, from the results in Table 2, the cellulose ester film master samples 1-1 to 1-15 of the present invention are U-shaped failure and core transfer, even if stored for a long time with respect to the cellulose ester film master samples 1-16 to 1-25 of the comparative example. It turns out that it is a cellulose-ester film which is few, and deformation | transformation failure of the film originals, such as winding start wrinkles, does not occur easily. Moreover, also about the cellulose-ester film itself cut out from the disk, it turns out that the cellulose-ester film of this invention is a cellulose-ester film with small fluctuation | variation in curling property and retardation, while having high planarity and saponification processability. In addition, it can be seen that the polarizing plate manufactured by using the cellulose ester film of the present invention has excellent durability and is excellent in practical use.

Example 2

Cellulose ester film masters 2-1 to 2 of the present invention in the same manner as in the cellulose ester film master 1-1 of Example 1 except for changing to a combination of the cellulose esters, plasticizers, deterioration inhibitors, and ultraviolet absorbers shown in Table 3. -18, and the cellulose ester film master 2-19, 2-20 of the comparative, and the cellulose ester film 2-1 to 2-18 of the present invention, and the same method as the cellulose ester film 1-1 of Example 1, and Comparative cellulose ester films 2-19 and 2-20 were prepared. In addition, polarizing plates 2-1 to 2-18 of the present invention and comparative polarizing plates 2-19 and 2-20 were manufactured by the same method as the polarizing plate 1-1 of Example 1. In addition, the numerical value in parentheses described in the column of the plasticizer, deterioration inhibitor, and ultraviolet absorber of Table 3 shows the mass part of each material used with respect to 100 mass parts of cellulose esters.

In addition, plasticizer-B, plasticizer-C, plasticizer-D, plasticizer-E, plasticizer-F, plasticizer-G, plasticizer-G, manufactured by Sumitomo Chemical Co., Ltd., Tinuvin 900 (Chiba Specialty Chemical) Suzu Corporation), Smithsorb 250 (manufactured by Sumitomo Chemical Industries, Ltd.), and LA31 (manufactured by Adeka Corporation) are as follows.

Evaluation similar to Example 1 was performed about the produced cellulose ester film master, a cellulose ester film, and a polarizing plate. The results are shown in Table 4.

As described above, from the results in Table 4, the cellulose ester film master samples 2-1 to 2-18 of the present invention are U-shaped failure and core transfer, even if stored for a long time as compared to the cellulose ester film master samples 2-19 and 2-20 of the comparative example. It turns out that it is a cellulose-ester film which is few, and deformation | transformation failure of the film originals, such as winding start wrinkles, does not occur easily. Moreover, also about the cellulose-ester film itself cut out from the disk, it turns out that the cellulose-ester film of this invention is a cellulose-ester film with small fluctuation | variation in curling property and retardation, while having high planarity and saponification processability. In addition, it can be seen that the polarizing plate manufactured by using the cellulose ester film of the present invention has excellent durability and is excellent in practical use. In addition, in the film master sample 2-1, the film sample 2-1, and the polarizing plate sample 2-1, the same evaluation was performed by replacing exemplary compound (2) -8 with exemplary compound (2) -3 of the same mass part. And similar results to Sample No. 2-1 in Table 4, respectively. As in the above, even when Exemplified Compound (2) -8 was replaced with Exemplary Compound (2) -45 by mass part, similar results as in Sample No. 2-1 were obtained. On the other hand, in the film master sample 2-5, the film sample 2-5, and the polarizing plate sample 2-5, GSY-P101 is a tetrakis (2,4-di-t-butyl-phenyl) -4,4 part by mass. When the same evaluation was performed instead of "-biphenylenediphosphonite, the evaluation result of white spots was favorable result similarly to each sample No. 2-5 of Table 4 except the evaluation result of (circle) being (circle). In addition, in the raw film sample 2-7, the film sample 2-7, and the polarizing plate sample 2-7, Irganox 1010 was used as the 1,1,1-trimethylol ethane-tris- [3- (3, 5-di-t-butyl-4-hydroxyphenyl) propionate] was evaluated in the same manner, and the results were good as in Sample No. 2-7 in Table 4.

Example 3

Using the cellulose ester and various additives as described below, the cellulose ester film master 3 of the present invention was carried out in the same manner as in Example 1 except that the extrusion amount, the take-up speed, and the draw ratio were adjusted so that the film had a thickness of 40 µm. When -1 was produced, it was found that even if stored for a long period of time, it was a cellulose ester film with little U-shape failure, winding core transfer, and deformation failure of the film disc such as winding start wrinkles. Moreover, when the cellulose ester film was cut out from this disk and evaluated, it is a cellulose ester film with high planarity and saponification ability, and small curling property and the retardation fluctuation, and the polarizing plate manufactured using the said cellulose ester film is durable. This was favorable and it turned out that it is an optical film excellent in practical use.

Cellulose ester 1 100 parts by mass

Plasticizer-A 8 parts by mass

Irganox 1010 (manufactured by Ciba Specialty Chemicals) 0.50 parts by mass

0.25 parts by mass of GSY-P101 (manufactured by Sakai Chemical Industries, Ltd.)

Exemplary Compound (2) -8 0.30 parts by mass

Tinuvin 928 (manufactured by Ciba Specialty Chemicals) 2.25 parts by mass

Example 4

(Characteristic evaluation as a liquid crystal display device)

The polarizing plate of 32 type television AQ-32AD5 by Sharp Co., Ltd. which is a VA type liquid crystal display device was removed, and each polarizing plate (Cellulose ester film 3- of this invention manufactured in Example 3) manufactured in Examples 1-3. 1 to prepare a polarizing plate 3-1 in the same manner as in the polarizing plate 1-1) was cut to fit the size of the liquid crystal cell. The two polarizers prepared above were sandwiched between the liquid crystal cells so as to be perpendicular to each other so that the polarization axes of the polarizers were not changed from the originals. Thus, a 32 type VA type color liquid crystal display was produced to evaluate the characteristics of the cellulose ester film as a polarizer. The liquid crystal display device using the polarizing plates 1-1 to 1-15, 2-1 to 2-18, and 3-1 of this invention used the comparative polarizing plates 1-16 to 1-25, 2-19, and 2-20. The liquid crystal display device exhibited excellent contrast and high displayability without color unevenness. This confirmed that it was excellent as a polarizing plate for image display apparatuses, such as a liquid crystal display.

Claims (13)

In the optical film which melt | dissolved the film forming material containing 1 or more types of plasticizers and a cellulose ester, and formed into a film by the melt casting method, the kind of substituent of the said cellulose ester and its substitution degree are the conditions of the following formula (1)-(4). It formed into a film using the cellulose ester which satisfy | fills simultaneously, The optical film characterized by the above-mentioned. &Quot; (1) &quot; 1.25≤X≤1.43 &Quot; (2) &quot; 1.15≤Y≤1.33 &Quot; (3) &quot; 2.40≤X + Y <2.75 &Quot; (4) &quot; -0.05≤X-Y <0.20 [Wherein X represents a degree of substitution by an acetyl group, and Y represents a degree of substitution by a propionyl group] The optical film according to claim 1, wherein the 1% mass reduction temperature Td (1.0) in the air of the cellulose ester is at least 270 ° C. The optical film according to claim 1, wherein the film forming material further contains at least one of phenolic compounds. The optical film according to claim 1, wherein the film forming material further contains at least one of phosphorus compounds. The optical film according to claim 1, wherein the film forming material further contains at least one kind of alkyl radical scavenger. The optical film according to claim 1, wherein the film forming material further contains at least one of a phenolic compound, at least one of a phosphorus compound, and at least one of an alkyl radical scavenger. The optical film according to claim 3, wherein the phenolic compound is a hindered phenolic compound. The optical film according to claim 4, wherein the phosphorus compound is a phosphonite compound. The optical film according to claim 5, wherein the alkyl radical scavenger is a compound represented by the following formula (1) or a compound represented by the following formula (2). &Lt; Formula 1 >

[Wherein, R ₁ represents a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, and R ₂ and R ₃ each independently represent an alkyl group having 1 to 8 carbon atoms] (2)

[Wherein, R ₁₂ to R ₁₅ each independently represent a hydrogen atom or a substituent, R ₁₆ represents a hydrogen atom or a substituent, n represents an integer of 1 to 4, and when n is 1, R ₁₁ is When n is an integer of 2 to 4, R ₁₁ represents a 2 to tetravalent linking group.] The optical film according to claim 1, wherein the plasticizer is a polyhydric alcohol ester. The optical film according to claim 1, wherein the film forming material further contains a benzotriazole compound. The optical film of Claim 1 has on at least one surface of a polarizer, The polarizing plate characterized by the above-mentioned. The polarizing plate of Claim 12 is used for at least one surface of a liquid crystal cell, The liquid crystal display device characterized by the above-mentioned.

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