JP2008056890A - Cellulose acylate composition, cellulose acylate film, method for producing the same, polarizing plate, optical compensation film, antireflection film and liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To control thickness unevenness of a melt cast cellulose acylate film. <P>SOLUTION: The cellulose acylate film has an apparent activation energy of E<SB>0</SB>(5) 160-240 (kJ/mol) measured five minutes after melting at 220°C, and the longest relaxation time τ (5) of 4-50 (msec). <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a cellulose acylate composition, a cellulose acylate film, and a method for producing the same. In particular, it relates to producing a cellulose acylate film by a melt casting method and a raw material used therefor. The present invention also relates to a polarizing plate, an optical compensation film, an antireflection film, and a liquid crystal display device using the cellulose acylate film.

  Conventionally, when manufacturing a cellulose ester film used in a liquid crystal display device, a solution stream is prepared by dissolving a cellulose ester in a chlorinated organic solvent such as dichloromethane, casting it on a substrate, and drying it to form a film. The enrollment method is mainly implemented. Among chlorinated organic solvents, dichloromethane is preferably used because it is a good solvent for cellulose esters, has a low boiling point (about 40 ° C.), and can be easily dried in a film forming process or a drying process. On the other hand, in recent years, it has been strongly demanded to suppress discharge of organic solvents such as chlorinated organic solvents from the viewpoint of environmental conservation. For this reason, a more strict closed system is adopted to prevent the organic solvent from leaking from the manufacturing process, or even if the organic solvent leaks from the film forming process, the organic solvent is adsorbed through the gas absorption tower before it is released to the outside air. Measures are taken so that the organic solvent is hardly discharged by performing a process such as burning with thermal power or decomposing with an electron beam. However, even if these measures were taken, further non-emission was not achieved, so further improvement was required.

Thus, as a film forming method that does not use an organic solvent, a melt film forming method has been developed in which cellulose ester is melted and cast on a substrate to form a film (see Patent Document 1). In this method, the melting point is lowered by elongating the carbon chain of the ester group of cellulose ester to facilitate melt film formation. Specifically, melt film formation is enabled by changing the cellulose acetate conventionally used to cellulose propionate or the like.
JP 2000-352620 A

However, the film in which cellulose acetate is melt-formed by the method described in Patent Document 1 has fine thickness unevenness. This minute thickness unevenness is confirmed when the film surface is observed with a surface shape / roughness measuring instrument. The fine thickness unevenness causes a problem in that the display unevenness occurs when the film is used in a high-quality liquid crystal display device such as a television.
Accordingly, the inventors of the present invention have an object to solve such problems of the prior art, and an object of the present invention is to suppress fine thickness unevenness generated on the surface of a melt-cast cellulose acylate film. Set.

  As a result of intensive studies, the present inventors have found that the problems of the prior art can be solved by controlling the apparent activation energy and relaxation time. That is, the following present invention has been provided as means for solving the problems.

(1) Apparent activation energy E ₀ (5) measured 5 minutes after melting at 220 ° C. is 160 to 240 (kJ / mol), and longest relaxation time τ (5) is 4 to 50 (msec) A cellulose acylate composition comprising: a cellulose acylate.
(2) Apparent activation energy E ₀ (5) and longest relaxation time τ (5) measured after 5 minutes after melting the cellulose acylate at 220 ° C., and melting the cellulose acylate at 220 ° C. The cellulose acylate composition according to (1), wherein the apparent activation energy E ₀ (30) and the longest relaxation time τ (30) measured after 30 minutes satisfy the following formulas: .
| E ₀ (30) −E ₀ (5) | ≦ 30 (kJ / mol)
| Τ (30) −τ (5) | ≦ 5 (msec)
(3) The content of hemicellulose in the cellulose constituting the cellulose acylate is 0.1 to 3% by mass, and the weight average degree of polymerization (DPw) of the cellulose acylate is 300 to 550, The cellulose acylate composition according to (1) or (2).
(4) The weight average polymerization degree / number average polymerization degree (DPw / DPn) of the cellulose acylate is 1.7 to 5.0, according to any one of (1) to (3) The cellulose acylate composition described.
(5) The cellulose acylate composition according to any one of (1) to (4), wherein the cellulose acylate satisfies the following formulas (S-1) to (S-3).
Formula (S-1): 2.60 ≦ X + Y <3.00
Formula (S-2): 0 ≦ X ≦ 1.80
Formula (S-3): 1.00 ≦ Y <3.00
(In the formula, X represents the substitution degree of the acetyl group, and Y represents the total substitution degree of the propionyl group, butyryl group, pentanoyl group, and hexanoyl group.)
(6) The cellulose acylate composition according to any one of (1) to (5), wherein the cellulose acylate satisfies the following formulas (T-1) and (T-2).
Formula (T-1): 2.5 <= X + Z <3.0
Formula (T-2): 0.1 ≦ Z <2
(In the formula, X represents the degree of substitution of the acetyl group, and Z represents a substituted or unsubstituted aromatic acyl group.)
(7) The total content of Na, Ca, K, and Mg is 300 ppm or less, the residual sulfate radical amount is 300 ppm or less, and the molar content ratio of (Na + Ca + K + Mg) / S is 0.7 to 2.0. The cellulose acylate composition according to any one of (1) to (6), wherein the cellulose acylate composition is present.
(8) 0.1 to 3.0% by mass of a thermal stabilizer having a molecular weight of 500 or more having at least one of a hydroxyphenyl group or a phosphite group in the same molecule (1) to ( The cellulose acylate composition according to any one of 7).
(9) The cellulose acylate composition according to any one of (1) to (8), wherein the shape is a pellet.
(10) A method for producing a cellulose acylate film, comprising a step of melting the cellulose acylate composition according to any one of (1) to (9) to form a film.
(11) The cellulose acylate composition is melted at 200 ° C. to 250 ° C. in an atmosphere having an oxygen concentration of 0.1% to 19% to form a film. A method for producing a cellulose acylate film.
(12) The cellulose according to (10) or (11), comprising a step of extruding the cellulose acylate composition onto a casting drum after melting and forming a film on the casting drum using a touch roll. A method for producing an acylate film.
(13) A cellulose acylate film produced by the production method according to any one of (10) to (12).
(14) Apparent activation energy E ₀ (5) measured 5 minutes after melting at 220 ° C. is 160 to 240 (kJ / mol), and longest relaxation time τ (5) is 4 to 50 (msec) A cellulose acylate film having a residual solvent amount of 0.01% by mass or less.
(15) A cellulose acylate film obtained by stretching the cellulose acylate film according to (13) or (14) in at least one direction.
(16) The cellulose acylate film according to any one of (13) to (15) is stretched so that the aspect ratio L / W exceeds 2 and is 50 or less, or 0.01 to 0.3. A cellulose acylate film characterized by that.
(17) A cellulose acylate film obtained by preheating the cellulose acylate film according to any one of (13) to (16) at a temperature higher by 1 ° C. to 50 ° C. than the stretching temperature before transverse stretching. .
(18) A cellulose acylate film obtained by heat-treating the cellulose acylate film according to any one of (13) to (17) at a temperature 1 ° C. to 50 ° C. lower than the stretching temperature after transverse stretching.
(19) After the cellulose acylate film according to any one of (13) to (18) is subjected to longitudinal stretching and / or lateral stretching, at a temperature of Tg−50 ° C. to Tg + 30 ° C., 0.1 kg / A cellulose acylate film characterized by being thermally relaxed while being conveyed with a tension of m to 20 kg / m.
(20) A polarizing plate produced using the cellulose acylate film according to any one of (13) to (19).
(21) An optical compensation film produced using the cellulose acylate film according to any one of (13) to (19).
(22) An antireflection film produced using the cellulose acylate film according to any one of (13) to (19).
(23) The cellulose acylate film according to any one of (13) to (19), the polarizing plate according to (20), the optical compensation film according to (21), and the antireflection according to (22). A liquid crystal display device manufactured using at least one of films.

  According to the present invention, it is possible to suppress fine thickness unevenness generated on the surface of a melt-cast cellulose acylate film. A polarizing plate, an optical compensation film and an antireflection film produced using the cellulose acylate film of the present invention are excellent in optical properties. Moreover, the liquid crystal display device manufactured using the cellulose acylate film of the present invention has reduced display unevenness.

  Hereinafter, the cellulose acylate film of the present invention and the production method thereof will be described in detail. The description of the constituent elements described below may be made based on typical embodiments of the present invention, but the present invention is not limited to such embodiments. In the present specification, a numerical range represented by using “to” means a range including numerical values described before and after “to” as a lower limit value and an upper limit value.

<Features of the present invention>
The present invention has been provided for the purpose of suppressing fine thickness unevenness generated on the surface of a melt-cast cellulose acylate film. The fine thickness unevenness referred to here is thickness unevenness that can be confirmed when the film surface is observed with a surface shape / roughness measuring instrument, although it cannot be confirmed directly with the naked eye. As a result of analyzing the cause of the occurrence of this fine thickness unevenness, it was found that it was caused by the kneadability and fluidity of cellulose acylate.

(Improvement of materials)
In order to suppress fine thickness unevenness, it is important to knead cellulose acylate well and to flow uniformly. Therefore, in the present invention, the apparent activation energy and the longest relaxation time are controlled.
That is, in the present invention, the activation energy E ₀ (5) of the flow 5 minutes after melting at 220 ° C. is 160 to 240 (kJ / mol), and the longest relaxation time τ (5) is 4 to 50. Cellulose acylate (msec) is used. The activation energy E0 (5) is 170 to 230 (kJ / mol), the longest relaxation time τ (5) is preferably 4 to 25 (msec), and the activation energy E0 (5) is 180 to 220. In (kJ / mol), the longest relaxation time τ (5) is more preferably 5 to 10 (msec).
In the present invention, activation energy E ₀ (5), longest relaxation time τ (5), activation energy E ₀ (30) 30 minutes after melting at 220 ° C. and longest relaxation time τ (30) Preferably satisfies the following formula.
| E ₀ (30) −E ₀ (5) | ≦ 30 (kJ / mol)
| Τ (30) −τ (5) | ≦ 5 (msec)
It is more preferable to satisfy the following formula.
| E ₀ (30) −E ₀ (5) | ≦ 20 (kJ / mol)
| Τ (30) −τ (5) | ≦ 5 (msec)
Further, it is more preferable to satisfy the following formula.
| E ₀ (30) −E ₀ (5) | ≦ 10 (kJ / mol)
| Τ (30) −τ (5) | ≦ 4 (msec)
Furthermore, it is particularly preferable to satisfy the following formula.
| E ₀ (30) −E ₀ (5) | ≦ 5 (kJ / mol)
| Τ (30) −τ (5) | ≦ 4 (msec)

The reason why the melt viscoelasticity is set within the above range is as follows. Apparent activation energy E ₀ is energy required for the molecule to change its position, and if this value is small, the kneadability between the polymers increases. However, if this value is too low, the polymer moves with a small disturbance, which causes the smoothness of the film to deteriorate. Considering the above, in the present invention, the optimum range of the activation energy E ₀ was found and set within the above range.
The longest relaxation time τ corresponds to the shear rate at which the polymer main chain escapes from the entanglement. In the shear region below this τ, the entanglement of the molecular difference does not escape and the fluidity is low. Therefore, it is important to make this value as small as possible. However, if the flow rate is too low, unstable flow tends to occur. For example, the neck-in of the film during film formation [the die exit width is W0, and the cellulose acylate composition discharged from the die first comes into contact with the casting drum. When the width at the point is W1, it is represented by (W0−W1) / W0. ] Increases. Then, it becomes difficult to form a wide film, and industrial productivity falls. Considering the above, in the present invention, the optimum range of the longest relaxation time τ is found and set within the above range.
Furthermore, it is important for maintaining kneadability and fluidity that the activation energy E ₀ and the longest relaxation time τ do not change during the film forming process. Therefore, the optimum range of the change amount of activation E ₀ and the longest relaxation time τ after 5 minutes and 30 minutes after melting was found and set within the above range.

  In order to adjust the melt viscoelasticity to the above preferable range, it is preferable to improve the chemical composition of the cellulose acylate raw material as follows. As a result of intensive studies, the researchers of the present invention have found that the apparent activation energy and the longest relaxation time are controlled by controlling the amount of hemicellulose in the cellulose constituting the cellulose acylate and the weight average molecular weight within an appropriate range. I found out that it can be reduced unexpectedly. In addition, wood pulp (hardwood pulp, softwood pulp), cotton linter, etc. used as cellulose acylate raw materials usually contain components such as hemicellulose (glucomannan, xylan, arabinoxylan, glucuronoxylan, etc.) and lignin in addition to cellulose. is doing. In the present invention, hemicellulose is used as a general term including components other than these celluloses. These preferable ranges will be described in detail below.

(1) Hemicellulose content In the present invention, the amount of hemicellulose in the cellulose constituting the cellulose acylate is preferably 0.1 to 3 mass%, more preferably 0.1 to 2 mass%, and still more preferably 0.1. The one which is ˜1% by mass is used. If the amount of hemicellulose is 3% by mass or less, the activation energy E ₀ and the relaxation time τ can be prevented from increasing rapidly, and if it is 0.1% by mass or more, the smoothness of the film and the instability during film formation Easy to avoid flow. Such an effect is not observed in cellulose triacetate (CTA), and is manifested by changing the substituent of CTA to propionyl (Pr) group, butyryl (Bu) group, etc., and in particular, the degree of substitution of Pr and Bu groups is 1 When the weight average polymerization degree is in the range of 250 to 550, the effect is remarkable.
The reason why the content of hemicellulose has a positive effect on the melt properties of cellulose acylate is not clear, but the melting point and melting of hemicellulose acylate (such as glucomannan acetate propionate) that is purified simultaneously with the manufacture of cellulose acylate It is estimated that one of the causes is that the viscoelasticity of the product is different from the acylate of cellulose alone.
The amount of hemicellulose can be adjusted by purifying cellulose raw materials derived from hardwood pulp, softwood pulp, and cotton linter by an appropriate method. Specifically, by strengthening the refined bleaching process that combines the pulp raw material with sulfite digestion, kraft digestion, etc., bleaching with oxygen or chlorine bleach, and alkali refining, The content of lignin and hemicellulose can be reduced to the above range. In order to adjust the amount of hemicellulose to the above-mentioned preferable range, when carrying out the alkali purification step at the final stage of the purification bleaching step, a 3-25 mass% strong alkaline aqueous solution is used and purification is performed at a low temperature of 20-40 ° C. It is preferable to process. In this invention, although a cellulose raw material may be used independently, the quantity of hemicellulose can also be adjusted by mixing and using. Incidentally, the amount of hemicellulose is about 5 to 10% when purified by a conventional method.
The hemicellulose content can be quantified by performing a sugar analysis by the alditol acetate method (Borchadt, LG; Piper, CV: Tappi, 53, 257-260 (1970)).

(2) Degree of polymerization The weight average degree of polymerization (DPw) of the cellulose acylate with adjusted hemicellulose content is preferably 300 to 550, more preferably 300 to 450, and even more preferably 350 to 400. By adjusting both the amount of hemicellulose and the weight average degree of polymerization, it is particularly preferable because the range of the apparent activation energy E ₀ and the longest relaxation time τ can be easily adjusted to a preferable range at the same time. In the present application, the weight average degree of polymerization means a value obtained by dividing the weight average molecular weight determined by the GPC method by the average molecular weight of the glucose repeating unit of cellulose acylate.

(3) Molecular weight distribution It is preferable that the weight average polymerization degree / number average polymerization degree of the cellulose acylate used by this invention is 1.7-5.0, More preferably, it is 2.0-4.0. By adjusting the molecular weight distribution to these preferred ranges, it is easy to optimize the apparent activation energy E ₀ to the above preferred range.

(4) Degree of substitution The cellulose acylate used in the present invention preferably satisfies the following degree of substitution.
2.60 ≦ X + Y ≦ 3.00
0.00 ≦ X ≦ 1.80
1.00 ≦ Y ≦ 3.00
(X represents the substitution degree of the acetyl group with respect to the hydroxyl group of cellulose, and Y represents the total substitution degree of the propionyl group, butyryl group, pentanoyl group, and hexanoyl group with respect to the hydroxyl group of cellulose.)

Moreover, it is more preferable to satisfy the following substitution degree.
2.70 ≦ X + Y ≦ 3.00
0.00 ≦ X ≦ 1.20
1.50 ≦ Y ≦ 3.00

In the present invention, it is also preferable to use cellulose acylate having a composition satisfying the following formulas (T-1) and (T-2).
Formula (T-1): 2.5 ≦ X + Z ≦ 3.0
Formula (T-2): 0.1 ≦ Z ≦ 2
More preferably,
Formula (T-3): 2.6 ≦ X + Z ≦ 3.0
Formula (T-4): 0.1 ≦ Z ≦ 1.5
More preferably,
Formula (T-3): 2.7 ≦ X + Z ≦ 3.0
Formula (T-4): 0.1 ≦ Z ≦ 1.0
It is.
In the formula, X represents the degree of substitution of the acetyl group, and Z represents a substituted or unsubstituted aromatic acyl group.
Here, examples of the substituted or unsubstituted aromatic acyl group include groups represented by the following general formula (I).

Furthermore, it is more preferable to satisfy the following substitution degree.
2.70 ≦ X + Y ≦ 3.00
0.00 ≦ X ≦ 1.20
2.00 ≦ Y ≦ 3.00

By adjusting the substitution degree of cellulose acylate, the longest relaxation time τ can be optimized to a more preferable range.
The “degree of substitution” referred to in the present application means the total ratio of substitution of hydrogen atoms of hydroxyl groups at the 2-position, 3-position and 6-position of cellulose. When the hydrogen atoms of all hydroxyl groups at the 2-position, 3-position and 6-position are substituted with an acyl group, the substitution degree is 3. The acyl group may have a substituent.

(5) Content of metal and sulfur It is preferable that the apparent activation energy E ₀ and the longest relaxation time τ optimized in this way are not excessively varied in the film forming process. For that purpose, it is preferable to prevent the chemical composition of cellulose acylate from changing, more specifically, to prevent thermal decomposition, crosslinking, and coloring of cellulose acylate.
For such purposes, the cellulose acylate used in the present invention preferably has a residual sulfate radical amount (as S atom content) and a total amount of residual Na, Ca, K, and Mg of 0 to 300 ppm. . The total amount of residual sulfate radicals and residual Na, Ca, K, and Mg is more preferably 0 to 200 ppm, and still more preferably 0 to 100 ppm. Furthermore, the molar content ratio of (Na + Ca + K + Mg) / S is preferably 0.7 to 2.0, more preferably 0.8 to 1.5, still more preferably 0.9 to 1.2. . The residual sulfate radical as used herein refers to the sum of all the amounts present in cellulose acylate in the form of free sulfuric acid, salt, ester, complex, etc., and the amount is defined by the content of sulfur atoms. That is, for example, 98 g of sulfuric acid is converted to 32 g of sulfur atoms to determine the sulfur atom content.

  By setting the content and molar content ratio of sulfate radicals, Na, Ca, K, and Mg to the above preferred ranges, oxidation of cellulose acylate, molecular weight change, chemical composition change, coloring, and gelation when heated It can suppress more effectively and can make it easy to manufacture the cellulose acylate film which was further excellent in the optical property.

(6) Thermal stabilizer In order to further enhance the thermal stability of the cellulose acylate having the above composition, it is preferable to add a thermal stabilizer in the present invention. In the present application, the term “thermal stabilizer” means one having a property of suppressing decomposition and coloring of a resin caused by heating.
As the thermal stabilizer, it is preferable to add at least one phenol-based stabilizer and at least one selected from a phosphite-based stabilizer or a thioether-based stabilizer having a molecular weight of 500 or more. It is preferable that it is 1-3.0 mass%, More preferably, it is 0.1-1.0 mass%. Details and preferred examples of the heat stabilizer will be described later.

(Improved film forming process)
Using the cellulose acylate with an improved composition as described above, when producing a cellulose acylate film by the melt film forming method, a film that further meets the object of the present invention is produced by improving the process conditions. It becomes possible to do. That is, it is preferable to make the following adjustments in order to suppress fine thickness unevenness.

The temperature of the melt extrusion die used when melt-extruding the cellulose acylate composition is preferably 200 ° C to 250 ° C, more preferably 210 ° C to 240 ° C, and further preferably 220 ° C to 235 ° C. In order to suppress the thermal decomposition of cellulose acylate, it is necessary to lower the melting temperature. On the other hand, to make the apparent activation energy E ₀ and the longest relaxation time τ within the range of the present invention, the melting temperature is increased. This is because it is necessary. If it is said melting | fusing temperature range, the objective of this invention can be achieved more effectively.
The melt is preferably transported under a low oxygen concentration, and the oxygen concentration at that time is preferably 0.1% to 18%, more preferably 0.1% to 10%, and still more preferably. 0.1% to 5% or less. As described above, it is preferable in the present invention to slightly mix oxygen during melt conveyance. If the oxygen concentration is 0.1% or more, the recombination reaction of the molecular chain is difficult to occur, so that it is easy to suppress the generation of the microgel and to express more excellent optical properties, and when the oxygen concentration is 18% or less. If present, it is possible to more effectively suppress the cleavage of the molecular chain due to thermal decomposition.

  In the present invention, it is preferable to form a film using a touch roll on a casting drum after extrusion from a die after melting. In this method, the melt discharged from the die is sandwiched between a casting drum and a touch roll to be cooled and solidified. By this touch roll, the micro gel on the film surface generated inside the die can be embedded inside the film. As a result, a cellulose acylate film having high smoothness and no optical unevenness can be achieved.

Furthermore, the effect which improves a brittleness is also seen unexpectedly by using a touch roll. The cellulose acylate of the present invention tends to be brittle because crystallization is likely to proceed. This is because, when the touch roll as described above is used, crystallization is difficult to proceed because the film is rapidly cooled from both surfaces. When cellulose acylate having a low polymerization degree is used as in the present invention, embrittlement is particularly likely to occur and is effective.
In such a touch roll, an elastic body layer is provided on a metal shaft, an outer cylinder is covered thereon, and a liquid medium layer is filled between the elastic body layer and the outer cylinder. The wall thickness Z of the outer cylinder is preferably 0.05 mm to 7.0 mm, more preferably 0.2 mm to 5.0 mm. The casting roll and touch roll preferably have a mirror surface, and the arithmetic average height Ra is usually 100 nm or less, preferably 50 nm or less, more preferably 25 nm or less. Specifically, for example, JP-A-11-314263, JP-A-2002-36332, JP-A-2002-235747, JP-A-2004-216717, JP-A-2003-145609, International Publication No. 97/28950 pamphlet. The one described in can be used.

  Thus, since the touch roll is filled with the fluid inside the thin outer cylinder, when it is brought into contact with the casting roll, it is elastically deformed into a concave shape by the pressing. Accordingly, since the touch roll and the casting roll are in surface contact, the pressure is dispersed, and a low surface pressure can be achieved. For this reason, only the unevenness | corrugation of the surface can be corrected, without leaving a residual distortion in the film pinched | interposed between. The linear pressure of the preferred touch roll is 3 kg / cm to 100 kg / cm, more preferably 5 kg / cm to 80 kg / cm, and still more preferably 5 kg / cm to 60 kg / cm. The linear pressure here is a value obtained by dividing the force applied to the touch roll by the width of the discharge port of the die. The touch roll and casting roll are preferably set to 60 ° C to 160 ° C, more preferably 70 ° C to 150 ° C, still more preferably 80 ° C to 140 ° C. Such temperature control can be achieved by passing a temperature-controlled liquid or gas through these rolls.

《Cellulose acylate》
Regarding the method for synthesizing the cellulose acylate used in the present invention, it is possible to refer to the description on pages 7 to 12 of the Japan Institute of Invention and Technology (Public Technical Number 2001-1745, published on March 15, 2001, Japan Society of Invention). . In addition, the addition amount here is the mass% with respect to a cellulose acylate.

(material)
As the cellulose raw material for synthesizing cellulose acylate, those derived from hardwood pulp, softwood pulp and cotton linter are preferably used. By using these raw materials singly or in combination of two or more, the amount of hemicellulose can be adjusted as described above.

(activation)
Prior to acylation, the cellulose raw material is preferably subjected to a treatment (activation) for contact with an activator. As the activator, acetic acid, propionic acid, or butyric acid is preferable, and acetic acid is particularly preferable. The addition amount of the activator is preferably 5% to 10000%, more preferably 10% to 2000%, and further preferably 30% to 1000%.
The addition method can be selected from methods such as spraying, dripping and dipping. The activation time is preferably 20 minutes to 72 hours or less, particularly preferably 20 minutes to 12 hours. The activation temperature is preferably 0 ° C to 90 ° C, particularly preferably 20 ° C to 60 ° C. Furthermore, 0.1 mass%-10 mass% of acylation catalysts, such as a sulfuric acid, can also be added to an activator.

(Acylation)
It is preferable to acylate the hydroxyl group of cellulose by reacting cellulose with a carboxylic acid anhydride using a Bronsted acid or a Lewis acid (see “Science and Chemistry Dictionary”, fifth edition (2000)) as a catalyst.

  In order to control the temperature rise due to the heat of reaction of acylation, it is preferable to cool the acylating agent in advance. The acylation temperature is preferably -50 ° C to 50 ° C, more preferably -30 ° C to 40 ° C, particularly preferably -20 ° C to 35 ° C. The minimum reaction temperature is preferably −50 ° C. or higher, more preferably −30 ° C. or higher, and particularly preferably −20 ° C. or higher. The acylation time is preferably 0.5 hours to 24 hours, more preferably 1 hour to 12 hours, and particularly preferably 1.5 hours to 10 hours.

  A method for obtaining a cellulose acylate is a method in which two carboxylic anhydrides are reacted as an acylating agent by mixing or sequential addition, and a mixed acid anhydride of two carboxylic acids (for example, acetic acid / propionic acid mixed acid anhydride). ), A mixed acid anhydride (for example, acetic acid / propionic acid mixed acid anhydride) in a reaction system using a carboxylic acid and an acid anhydride of another carboxylic acid (for example, acetic acid and propionic acid anhydride) as a raw material. A method of forming and reacting with cellulose, a method of once synthesizing cellulose acylate having a degree of substitution of less than 3, and further acylating the remaining hydroxyl group with an acid anhydride or acid halide can be used.

  The synthesis of cellulose acylate having a high degree of substitution at the 6-position is described in JP-A-11-5851, JP-A-2002-212338, JP-A-2002-338601, and the like.

(Acid anhydride)
As an acid anhydride of carboxylic acid, a carboxylic acid having 2 to 22 carbon atoms can be preferably used. Particularly preferred are acetic anhydride, propionic anhydride, and butyric anhydride. The acid anhydride is preferably added in an amount of 1.1 to 50 equivalents, more preferably 1.2 to 30 equivalents, and particularly preferably 1.5 to 10 equivalents based on the hydroxyl group of cellulose.

(catalyst)
The acylation catalyst is preferably a Bronsted acid or a Lewis acid, more preferably sulfuric acid or perchloric acid, and a preferred addition amount is 0.1 to 30% by mass, more preferably 1 to 15% by mass. And particularly preferably 3 to 12% by mass.

(solvent)
Carboxylic acid is preferable as the acylating solvent, more preferably carboxylic acid having 2 to 7 carbon atoms, and particularly preferably acetic acid, propionic acid, and butyric acid. These solvents may be used as a mixture.

(Reaction terminator)
It is preferable to add a reaction terminator after the acylation reaction. The reaction terminator is not particularly limited as long as it decomposes acid anhydrides, and examples thereof include water, alcohol (having 1 to 3 carbon atoms), and carboxylic acids (acetic acid, propionic acid, butyric acid, etc.). Among them, water and carboxylic acid ( A mixture with acetic acid) is more preferred. The composition of water and carboxylic acid is preferably 5% by mass to 80% by mass, more preferably 10% by mass to 60% by mass, and particularly preferably 15% by mass to 50% by mass of water.

(Neutralizer)
A neutralizing agent may be added after the acylation reaction is stopped. Preferred examples of the neutralizing agent include ammonium, organic quaternary ammonium, alkali metal, group 2 metal, group 3-12 metal, or group 13-15 element carbonate, bicarbonate, organic acid salt, water. An oxide or an oxide can be given. Particularly preferred are sodium, potassium, magnesium or calcium carbonates, bicarbonates, acetates or hydroxides.

(Partial hydrolysis)
The cellulose acylate thus obtained has a total degree of substitution close to 3. However, for the purpose of obtaining a desired degree of substitution, a small amount of catalyst (generally, acylation of remaining sulfuric acid or the like) is performed. In the presence of catalyst) and water, the ester bond is partially hydrolyzed by maintaining at 20 to 90 ° C. for several minutes to several days, thereby reducing the acyl substitution degree of cellulose acylate to a desired degree. Thereafter, partial hydrolysis of the remaining catalyst is stopped using the neutralizing agent.

(Filtration)
Filtration may be performed at any step between the completion of acylation and reprecipitation. It is also preferred to dilute with a suitable solvent prior to filtration.

(Reprecipitation)
The cellulose acylate solution is mixed with water or an aqueous solution of carboxylic acid (for example, acetic acid, propionic acid, etc.) and reprecipitated. Reprecipitation may be either continuous or batch.

(Washing)
The cellulose acylate produced is particularly preferably washed. The washing solvent is not particularly limited as long as it has low solubility in cellulose acylate and can remove impurities, but water or warm water is usually used. The temperature of the washing water is preferably 25 ° C to 100 ° C, more preferably 30 ° C to 90 ° C, and particularly preferably 40 ° C to 80 ° C. The washing treatment may be performed by a so-called batch method in which filtration and replacement of the washing liquid are repeated, or may be carried out using a continuous washing apparatus. It is also preferable to reuse the waste liquid generated in the reprecipitation and washing steps as a poor solvent in the reprecipitation step, or to recover and reuse a solvent such as carboxylic acid by means such as distillation.
The progress of washing may be traced by any means, but preferred examples include methods such as hydrogen ion concentration, ion chromatography, electrical conductivity, ICP, elemental analysis, and atomic absorption spectrum. By performing such tracking, the amount of residual carboxylic acid can be adjusted.
Through the above treatment, the catalyst (sulfuric acid, perchloric acid, trifluoroacetic acid, p-toluenesulfonic acid, methanesulfonic acid, zinc chloride, etc.) in the cellulose acylate, neutralizing agent (for example, calcium, magnesium, iron, aluminum) Or zinc carbonate, acetate, hydroxide or oxide), a reaction product of a neutralizing agent and a catalyst, a carboxylic acid (such as acetic acid, propionic acid, or butyric acid), a reaction product of a neutralizing agent and a carboxylic acid Etc., which is effective for increasing the stability of cellulose acylate.

(Aromatic acylated cellulose acylate)
In the present invention, it is also preferable to use an aromatic acylated cellulose acylate having a composition satisfying the following formulas (T-1) and (T-2).
Formula (T-1): 2.5 <= X + Z <3.0
Formula (T-2): 0.1 ≦ Z <2
More preferably,
Formula (T-3): 2.6 <= X + Z <3.0
Formula (T-4): 0.1 ≦ Z <1.5
More preferably,
Formula (T-3): 2.7 ≦ X + Z <3.0
Formula (T-4): 0.1 ≦ Z <1.0
It is.
In the formula, X represents the degree of substitution of the acetyl group, and Z represents a substituted or unsubstituted aromatic acyl group.
Examples of the substituted or unsubstituted aromatic acyl group include groups represented by the following general formula (I).

First, general formula (I) will be described. X is a substituent, and examples of the substituent include a halogen atom, a cyano group, an alkyl group, an alkoxy group, an aryl group, an aryloxy group, an acyl group, a carbonamido group, a sulfonamido group, a ureido group, an aralkyl group, and a nitro group. Group, alkoxycarbonyl group, aryloxycarbonyl group, aralkyloxycarbonyl group, carbamoyl group, sulfamoyl group, acyloxy group, alkenyl group, alkynyl group, alkylsulfonyl group, arylsulfonyl group, alkyloxysulfonyl group, aryloxysulfonyl group, alkyl Sulfonyloxy group and aryloxysulfonyl group, —S—R, —NH—CO—OR, —PH—R, —P (—R) ₂ , —PH—O—R, —P (—R) (— O -R), -P (-O-R) ₂ , -PH (= O) -RP (= O) (-R) ₂ , -PH (= O) -O-R, -P (= O) (-R) (-O-R), -P (= O) (-O-R) ₂ , -O-PH (= O) -R, -O- P (═O) (— R) ₂ —O—PH (═O) —O—R, —O—P (═O) (— R) (— O—R), —O—P (═O) (—O—R) ₂ , —NH—PH (═O) —R, —NH—P (═O) (— R) (— O—R), —NH—P (═O) (— O— _{R) 2, -SiH 2 -R,} -SiH (-R) 2, -Si (-R) 3, -O-SiH 2 -R, -O-SiH (-R) 2 and -O-Si (- R) ₃ is included. R is an aliphatic group, an aromatic group or a heterocyclic group. The number of substituents is preferably 1 to 5, more preferably 1 to 4, further preferably 1 to 3, and most preferably 1 or 2. As the substituent, a halogen atom, a cyano group, an alkyl group, an alkoxy group, an aryl group, an aryloxy group, an acyl group, a carbonamido group, a sulfonamide group, and a ureido group are preferable, and a halogen atom, a cyano group, an alkyl group, an alkoxy group Group, aryloxy group, acyl group and carbonamido group are more preferred, halogen atom, cyano group, alkyl group, alkoxy group and aryloxy group are more preferred, and halogen atom, alkyl group and alkoxy group are most preferred.

The halogen atom includes a fluorine atom, a chlorine atom, a bromine atom and an iodine atom.
The alkyl group may have a cyclic structure or a branched structure. The number of carbon atoms in the alkyl group is preferably 1-20, more preferably 1-12, still more preferably 1-6, and most preferably 1-4. When the alkyl group has a substituent, the number including the number of carbon atoms of the substituent is preferably the number of carbon atoms (hereinafter, the same applies to other groups). Examples of the alkyl group include methyl group, ethyl group, propyl group, isopropyl group, butyl group, tert-butyl group, hexyl group, cyclohexyl group, octyl group and 2-ethylhexyl group.
The alkoxy group may have a cyclic structure or a branch. The number of carbon atoms in the alkoxy group is preferably 1-20, more preferably 1-12, still more preferably 1-6, and most preferably 1-4. The alkoxy group may be further substituted with another alkoxy group. Examples of the alkoxy group include methoxy group, ethoxy group, 2-methoxyethoxy group, 2-methoxy-2-ethoxyethoxy group, butyloxy group, hexyloxy group and octyloxy group.

The number of carbon atoms of the aryl group is preferably 6-20, and more preferably 6-12. Examples of the aryl group include a phenyl group and a naphthyl group. The aryloxy group preferably has 6 to 20 carbon atoms, more preferably 6 to 12 carbon atoms.
Examples of the aryloxy group include a phenoxy group and a naphthoxy group. The number of carbon atoms in the acyl group is preferably 1-20, and more preferably 1-12.
Examples of the acyl group include a formyl group, an acetyl group, and a benzoyl group.
The carbon atom number of the carbonamide group is preferably 1-20, and more preferably 1-12. Examples of the carbonamido group include an acetamide group and a benzamide group. The number of carbon atoms in the sulfonamide group is preferably 1-20, and more preferably 1-12.
Examples of the sulfonamide group include a methanesulfonamide group, a benzenesulfonamide group, and a p-toluenesulfonamide group.
The number of carbon atoms in the ureido group is preferably 1-20, and more preferably 1-12. Examples of ureido groups include (unsubstituted) ureido groups.

The number of carbon atoms in the aralkyl group is preferably 7-20, and more preferably 7-12. Examples of the aralkyl group include a benzyl group, a phenethyl group, and a naphthylmethyl group. The number of carbon atoms in the alkoxycarbonyl group is preferably 1-20, and more preferably 2-12.
Examples of the alkoxycarbonyl group include a methoxycarbonyl group. The number of carbon atoms of the aryloxycarbonyl group is preferably 7-20, and more preferably 7-12. Examples of the aryloxycarbonyl group include a phenoxycarbonyl group. The number of carbon atoms in the aralkyloxycarbonyl group is preferably 8-20, and more preferably 8-12. Examples of the aralkyloxycarbonyl group include a benzyloxycarbonyl group. The number of carbon atoms of the carbamoyl group is preferably 1-20, and more preferably 1-12. Examples of the carbamoyl group include a (unsubstituted) carbamoyl group and an N-methylcarbamoyl group. The number of carbon atoms in the sulfamoyl group is preferably 20 or less, and more preferably 12 or less. Examples of the sulfamoyl group include a (unsubstituted) sulfamoyl group and an N-methylsulfamoyl group.
The number of carbon atoms in the acyloxy group is preferably 1-20, and more preferably 2-12. Examples of the acyloxy group include an acetoxy group and a benzoyloxy group.

The alkenyl group has preferably 2 to 20 carbon atoms, and more preferably 2 to 12 carbon atoms. Examples of the alkenyl group include a vinyl group, an allyl group, and an isopropenyl group. The alkynyl group preferably has 2 to 20 carbon atoms, and more preferably 2 to 12 carbon atoms.
Examples of the alkynyl group include a thienyl group. The number of carbon atoms in the alkylsulfonyl group is preferably 1-20, and more preferably 1-12. The number of carbon atoms of the arylsulfonyl group is preferably 6-20, and more preferably 6-12.
The number of carbon atoms in the alkyloxysulfonyl group is preferably 1-20, and more preferably 1-12.
The number of carbon atoms of the aryloxysulfonyl group is preferably 6-20, and more preferably 6-12.
The number of carbon atoms of the alkylsulfonyloxy group is preferably 1-20, and more preferably 1-12. The number of carbon atoms of the aryloxysulfonyl group is preferably 6-20, and more preferably 6-12.

  Such compounds are obtained by substituting an aromatic acyl group for the hydroxyl group of cellulose and generally use symmetric acid anhydrides and mixed acid anhydrides derived from aromatic carboxylic acid claloids or aromatic carboxylic acids. Methods and the like. Particularly preferred is a method using an acid anhydride derived from an aromatic carboxylic acid (Journal of Applied Polymer Science, Vol. 29, 3981-3990 (1984)). As a method for producing the cellulose mixed acid ester compound of the present invention as the above method, (1) once the cellulose fatty acid monoester or diester is produced, the remaining hydroxyl group is an aromatic acyl represented by the above general formula (I) And (2) a method of reacting a mixed acid anhydride of an aliphatic carboxylic acid and an aromatic carboxylic acid directly with cellulose. In the method (1), a known method can be adopted as the method for producing cellulose fatty acid ester or diester, and the subsequent reaction for further introducing an aromatic acyl group is appropriately determined depending on the kind of the aromatic acyl group. The reaction temperature is preferably 0 to 100 ° C., more preferably 20 to 50 ° C., and the reaction time is preferably 30 minutes or more, more preferably 30 to 300 minutes. In the method using the mixed acid anhydride (2), the reaction conditions can be appropriately determined depending on the type of the mixed acid anhydride, but the reaction temperature is preferably 0 to 100 ° C., more preferably 20 to 50. C. and the reaction time are preferably 30 to 300 minutes, more preferably 60 to 200 minutes. In any of the above reactions, the reaction may be carried out either without a solvent or in a solvent, but is preferably carried out using a solvent. As the solvent, dichloromethane, chloroform, dioxane and the like can be used.

Specific examples of the aromatic acyl group represented by the general formula (I) are shown below, but the present invention is not limited thereto.

  Among these substituents, the substituents of 1 to 9, 18 to 19, and 27 to 28 are preferable, more preferably 1 to 3 substituents, and most preferably 1 substituent.

(Stabilization)
The cellulose acylate after washing is preferably added with a weak alkali (carbonates such as Na, K, Ca and Mg, bicarbonates, hydroxides and oxides) for stabilization.

(Dry)
It is preferable to dry the moisture content of the cellulose acylate at 50 to 160 ° C. to 2% by mass or less.

"Additive"
(Heat stabilizer)
In order to further increase the thermal stability of cellulose acylate, it is particularly effective to add a thermal stabilizer in the present invention. In particular, it is preferable to add at least one selected from a phenol-based stabilizer having a molecular weight of 500 or more, and a phosphite-based stabilizer having a molecular weight of 500 or more or a thioether-based stabilizer having a molecular weight of 500 or more.

  As the preferred phenol-based stabilizer, any known phenol-based stabilizer can be used. Preferable phenolic stabilizers include hindered phenolic stabilizers. In particular, it is preferable to have a substituent at a site adjacent to the hydroxyphenyl group. In this case, the substituent is preferably a substituted or unsubstituted alkyl group having 1 to 22 carbon atoms, such as a methyl group, an ethyl group, a propionyl group, An isopropionyl group, a butyl group, an isobutyl group, a tert-butyl group, a pentyl group, an isopentyl group, a tert-pentyl group, a hexyl group, an octyl group, an isooctyl group, and a 2-ethylhexyl group are more preferable. In addition, a stabilizer having a hydroxyphenyl group and a phosphite group in the same molecule is also mentioned as a preferable material.

  These are readily available as commercial products and are sold by the following manufacturers. From Ciba Specialty Chemicals, Irganox 1076, Irganox 1010, Irganox 3113, Irganox 245, Irganox 1135, Irganox 1330, Irganox 259, Irganox 565, Irganx 565, Irganx 565, Ir35x10 Moreover, it can obtain from Asahi Denka Kogyo Co., Ltd. as ADK STAB AO-50, ADK STAB AO-60, ADK STAB AO-20, ADK STAB AO-70, and ADK STAB AO-80. Furthermore, from Sumitomo Chemical Co., Ltd., it can obtain as Sumilizer BP-76, Sumilizer BP-101, Sumilizer GA-80. Also available from Sipro Kasei Co., Ltd. as Sinox 326M and Sinox 336B.

  A phosphite ester stabilizer having a molecular weight of 500 or more has an antioxidant effect. For example, compounds described in JP-A-2004-182979, [0023] to [0039], JP-A-51-70316. Examples thereof include compounds described in JP-A-10-306175, JP-A-57-78431, JP-A-54-157159, and JP-A-55-13765. In addition, as other stabilizers, it is selected from the materials described in detail on pages 17 to 22 of the Japan Institute of Invention Information (Public Technical Number 2001-1745, published on March 15, 2001, Japan Institute of Invention). Can be used. These are commercially available from Asahi Denka Kogyo Co., Ltd. as ADK STAB 1178, 2112, PEP-8, PEP-24G, PEP-36G, and HP-10, and Sandostab P-EPQ from Clariant. Is possible.

  In the present invention, any known thioether stabilizer can be used as the thioether stabilizer. For example, it is marketed by Sumitomo Chemical Co., Ltd. as Sumilizer TPL, TPM, TPS, TDP. It is also available from Asahi Denka Kogyo Co., Ltd. as ADK STAB AO-412S.

  In the use of these stabilizers, at least one phenol-based stabilizer and at least one selected from a phosphite-based stabilizer or a thioether-based stabilizer are each 0.02 to 3% by mass with respect to cellulose acylate. It is preferable to use so that it may be contained, and it is made to contain 0.05-1 mass% especially. The content ratio of the phenol-based stabilizer and the phosphite-based stabilizer or the thioether-based stabilizer is not particularly limited, but is preferably 1/10 to 10/1 (mass ratio), more preferably 1/5 to 5/5. 5/1 (mass ratio), more preferably 1/3 to 3/1 (mass ratio), and particularly preferably 1/3 to 2/1 (mass ratio).

  In the present invention, it is also recommended to use a stabilizer having a hydroxyphenyl group and a phosphite group in the same molecule. Those materials are described in JP-A-10-273494. As a commercially available product, Sumilyzer GP (Sumitomo Chemical Co., Ltd.) can be mentioned.

Further, a long-chain aliphatic amine described in JP-A-61-63686, a compound containing a sterically hindered amine group described in JP-A-6-329830, and a hindered dye described in JP-A-7-90270. Peridinyl light stabilizers, organic amines described in JP-A-7-278164, and the like can also be used.
Preferred amine stabilizers are ADK STAB LA-57, LA-52, LA-67, LA-62, LA-77 from Asahi Denka, and TINUVIN 765, 144 from Ciba Specialty Chemicals. Commercially available. The ratio of amines to stabilizers is usually about 0.01 to 25% by weight.

(Plasticizer)
If a plasticizer is added to cellulose acylate, the crystal melting temperature (Tm) of cellulose acylate can be lowered. Although the molecular weight of the plasticizer used for this invention is not specifically limited, Preferably high molecular weight is mentioned, For example, molecular weight 500 or more is preferable, More preferably, it is 550 or more, Furthermore, 600 or more is preferable. Examples of the plasticizer include phosphate esters, alkylphthalylalkyl glycolates, carboxylic acid esters, and fatty acid esters of polyhydric alcohols. These plasticizers may be solid or oily. That is, the melting point and boiling point are not particularly limited. When performing melt film formation, those having non-volatility can be particularly preferably used.

(UV absorber)
An ultraviolet inhibitor may be added to the cellulose acylate. With respect to the ultraviolet ray inhibitor, JP-A-60-235852, JP-A-3-199201, JP-A-51907073, JP-A-5-194789, JP-A-5-271471, JP-A-6-107854, JP-A-6-118233. 6-148430, 7-11056, 7-11055, 7-11056, 8-29619, 8-239509, and JP-A-2000-204173. . The addition amount is preferably 0.01 to 2% by mass, and more preferably 0.01 to 1.5% by mass, based on the melt (melt) to be prepared.

  These ultraviolet absorbers are available as the following commercial products. As benzotriazoles, TINUBIN P (Ciba Specialty Chemicals), TINUBIN 234 (Ciba Specialty Chemicals), TINUBIN 320 (Ciba Specialty Chemicals), TINUBIN 326 (Ciba Specialty Chemicals) TINUBIN 327 (Ciba Specialty Chemicals), TINUBIN 328 (Ciba Specialty Chemicals), Sumisorb 340 (Sumitomo Chemical), Adekas Type LA-31 (Asahi Denka Kogyo Co., Ltd.), etc. . In addition, as benzophenone-based ultraviolet absorbers, Seasorb 100 (manufactured by Sipro Kasei Co., Ltd.), Seasorb 101 (manufactured by Sipro Kasei Co., Ltd.), Seasorb 101S (manufactured by Sipro Kasei Co., Ltd.), Seasorb 102 (manufactured by Sipro Kasei Chemical), Seasorb 103 (Sipro Kasei Co., Ltd.), Adekas Type LA-51 (Asahi Denka Kogyo Co., Ltd.), Chemisorp 111 (Chemipro Kasei Co., Ltd.), UVINUL D-49 (BASF Corp.), and the like. Examples of oxalic acid anilide UV absorbers include TINUBIN 312 (manufactured by Ciba Specialty Chemicals) and TINUBIN 315 (manufactured by Ciba Specialty Chemicals). In addition, as a salicylic acid ultraviolet absorber, Seasorb 201 (manufactured by Sipro Kasei) and Seasorb 202 (manufactured by Sipro Kasei) are marketed, and as a cyanoacrylate ultraviolet absorber, Seasorb 501 (manufactured by Sipro Kasei), UVINUL N-539 (BASF) is available.

(Fine particles)
In the present invention, fine particles can be added to cellulose acylate. Examples of the fine particles include fine particles of an inorganic compound or fine particles of an organic compound. The average primary particle size of preferable fine particles contained in the cellulose acylate in the present invention is 5 nm to 3 μm, preferably 5 nm to 2.5 μm, and particularly preferably 20 nm to 2.0 μm. The addition amount of the fine particles is 0.005 to 1.0% by mass with respect to cellulose acylate, more preferably 0.01 to 0.8% by mass, and further preferably 0.02 to 0.4% by mass. %.

Examples of the inorganic compound include SiO ₂ , ZnO, TiO ₂ , SnO ₂ , Al ₂ O ₃ , ZrO ₂ , In ₂ O ₃ , MgO, BaO, MoO ₂ , V ₂ O ₅ , talc, clay, calcined kaolin, and calcined. Examples thereof include calcium silicate, hydrated calcium silicate, aluminum silicate, magnesium silicate, and calcium phosphate. _{Preferably, SiO2, ZnO, TiO 2,} SnO 2, Al 2 O 3, ZrO 2, In 2 O 3, MgO, BaO, is preferably at least one MoO _2, and V ₂ O _5, more preferably SiO _{2, TiO 2, SnO 2, Al 2} O 3, a ZrO _2.

  As the SiO2 fine particles, for example, commercially available products such as Aerosil R972, R972V, R974, R812, 200, 200V, 300, R202, OX50, TT600 (above, manufactured by Nippon Aerosil Co., Ltd.) can be used. As the ZrO2 fine particles, commercially available products such as Aerosil R976 and R811 (manufactured by Nippon Aerosil Co., Ltd.) can be used. Seahoster KE-E10, E30, E40, E50, E50, E70, E150, W10, W30, W50, P10, P30, P50, P100, P150, P250 ) Etc. are also used. Further, silica microbeads P-400 and 700 (catalyst chemical industry products) can also be used. SO-G1, SO-G2, SO-G3, SO-G4, SO-G5, SO-G6, SO-E1, SO-E2, SO-E3, SO-E4, SO-E5, SO-E6, SO- It can also be used as C1, SO-C2, SO-C3, SO-C4, SO-C5, SO-C6 (manufactured by Admatechs Co., Ltd.). Furthermore, silica particles (a powdered water dispersion) 8050, 8070, 8100, and 8150 manufactured by Moritex Corporation can also be used.

  Next, as the fine particles of the organic compound that can be used in the present invention, for example, polymers such as silicone resins, fluororesins, and acrylic resins are preferable, and silicone resins are particularly preferable. The silicone resin preferably has a three-dimensional network structure, such as Tospearl 103, 105, 108, 120, 145, 3120, and 240 (above, manufactured by Toshiba Silicone Co., Ltd.). Commercial products having a trade name can be used.

Further, it is preferable to use fine particles made of an inorganic compound that have been surface-treated in order to stably exist in the cellulose acylate film. The inorganic fine particles are also preferably used after surface treatment. As the surface treatment method, there are chemical surface treatment using a coupling agent and physical surface treatment such as plasma discharge treatment and corona discharge treatment. In the present invention, it is preferable to use a coupling agent. . As the coupling agent, an organoalkoxy metal compound (for example, a silane coupling agent, a titanium coupling agent, etc.) is preferably used. When inorganic fine particles are used as the fine particles (especially when SiO ₂ is used), treatment with a silane coupling agent is particularly effective. An organosilane compound can be used as the silane coupling agent. Although the usage-amount of the said coupling agent is not specifically limited, Preferably it is recommended to use 0.005-5 mass% with respect to an inorganic fine particle, Furthermore, 0.01-3 mass% is preferable.

(Release agent)
A release agent can be added to the cellulose acylate in the present invention. As the release agent, a compound having a fluorine atom is preferable. The compound having a fluorine atom can exhibit an action as a release agent, and may be a low molecular weight compound or a polymer. Examples of the polymer include the polymers described in JP-A No. 2001-269564. A polymer having a fluorine atom is preferably a polymer obtained by polymerizing a monomer containing a fluorinated alkyl group-containing ethylenically unsaturated monomer as an essential component. The fluorinated alkyl group-containing ethylenically unsaturated monomer related to the polymer is not particularly limited as long as it is a compound having an ethylenically unsaturated group and a fluorinated alkyl group in the molecule. A surfactant having a fluorine atom can also be used, and a nonionic surfactant is particularly preferable.

<< Manufacture of cellulose acylate film >>
(Pelletized)
The cellulose acylate and additives are preferably mixed and pelletized prior to melt film formation.
Pelletization is achieved by melting the cellulose acylate and the additive at 150 ° C. to 250 ° C. using a biaxial or uniaxial extruder (kneading extruder), then extruding the noodle into solid and cutting. Can be created. Pelletization may be performed by an underwater cut method in which the material is cut while being directly extruded into water. More preferably, the kneading and extruding machine is a vent type and is pelletized while decompressing. Further, it is more preferable to pelletize the inside of the kneading extruder while substituting with nitrogen.
Preferably, the pellet size is such cross-sectional area is 1 mm ² to 300 mm ^2, a length 1Mm～30mm, and more preferably the cross-sectional area of 2 mm ² 100 mm ^2, length 1.5Mm～10mm.
The number of revolutions of the extruder is preferably 10 rpm to 1000 rpm, more preferably 30 rpm to 500 rpm. The extrusion residence time in pelletization is usually 10 seconds to 30 minutes, preferably 30 seconds to 3 minutes.

(Dry)
Prior to melt film formation, the moisture in the pellets is dried so that the water content is 0.1% by mass or less, more preferably 0.01% by mass or less.
Drying temperature is preferably 40 to 180 ° C. for this, amount of drying air is preferably available in 20 to 400 m ³ / hour, and particularly preferably 100 to 250 m ³ / hour. The dew point of the drying wind is preferably 0 to -60 ° C, more preferably -20 to -40 ° C.

(Melt extrusion)
Dry cellulose acylate resin is fed into the cylinder from the feed port of the extruder.
The screw compression ratio of the extruder is preferably 2.5 to 4.5, more preferably 3.0 to 4.0. L (screw length) / D (screw diameter) is preferably 20 to 70. More preferably, it is 24-50. The melting temperature is preferably performed at the above-described temperature.
As the screw, a full flight, a mudock, a dull image, or the like can be used.
In order to prevent the oxidation of the resin, it is more preferable that the inside of the extruder is carried out in an inert (nitrogen or the like) air flow so as to have the above preferable oxygen concentration, or while being evacuated using a vented extruder.

(filtration)
It is preferable to perform breaker plate type filtration at the outlet of the extruder.
For high-precision filtration, it is preferable to provide a leaf type disk filter type filtration device after passing through the gear pump. Filtration may be performed in a single stage or in multiple stages. The filtration accuracy of the filter medium is preferably 3 μm to 15 μm, more preferably 3 μm to 10 μm. The filter medium is preferably stainless steel or steel, and stainless steel is particularly preferable. As the filter medium, a knitted wire or a sintered metal filter medium can be used, and the latter is particularly preferable.

(Gear pump)
It is preferable to install a gear pump between the extruder and the die in order to improve the thickness accuracy (reduction in fluctuation of the discharge amount). Thereby, the resin pressure fluctuation width of the die portion can be within ± 1%.
In order to improve the quantitative supply performance by the gear pump, a method of controlling the pressure before the gear pump to be constant by changing the number of rotations of the screw is also preferable. A high-precision gear pump using three or more gears is also effective. Since the staying part in the gear pump causes resin deterioration, a structure with less staying is preferable.
In order to stabilize the extrusion pressure, it is preferable to reduce the temperature fluctuation of the adapter connecting the extruder and the gear pump and the gear pump and the die. For this purpose, it is more preferable to use an aluminum cast heater.

(Die)
Any type of commonly used T-die, fishtail die, and hanger coat die may be used as long as the molten resin stays in the die. Also, there is no problem to insert a static mixer for improving the uniformity of the resin temperature immediately before the T die. The clearance of the T-die exit portion is generally 1.0 to 5.0 times the film thickness, more preferably 1.3 to 2 times.
The die clearance is preferably adjustable at intervals of 40 to 50 mm, more preferably at most 25 mm. A method of measuring the downstream film thickness and feeding it back to the die thickness adjustment is also effective in reducing the thickness variation.
Since the functional layer is provided on the outer layer, it is possible to produce a film having two or more kinds of structures using a multilayer film forming apparatus.
The preferred residence time of the resin from the supply port through the extruder until it exits the die is 2 minutes to 60 minutes, preferably 4 minutes to 30 minutes.

(cast)
The molten resin extruded from the die onto the sheet is cooled and solidified on a casting drum to obtain a film. At this time, it is preferable to use a touch roll as described above.
The casting drum is preferably 1-8, more preferably 2-5, and a method of slow cooling is preferred. The diameter of the casting roll and the touch roll is preferably 50 mm to 5000 mm, more preferably 150 mm to 1000 mm. The interval between the plurality of casting rolls is preferably 0.3 mm to 300 mm, more preferably 3 mm to 30 mm.
Then, it peels off from a casting drum, winds up after passing through a nip roll. Thus, the film-forming width | variety of the unstretched film obtained is 0.7m-5m normally, Preferably it is 1m-4m, More preferably, it is 1.3m-3m. The thickness of the unstretched film is preferably 20 μm to 400 μm, more preferably 25 μm to 300 μm, and even more preferably 30 μm to 200 μm. When using it without extending | stretching especially, 30 micrometers-100 micrometers are preferable, and 30 micrometers-60 micrometers are more preferable. Such a thin film is uniformly cooled in the film thickness direction simultaneously from the surface on the cast drum side to the opposite surface when the melt (melt) from the die during melt film formation is cooled and solidified on the cast drum. Therefore, residual strain hardly remains in the film, and retardation change with time does not easily occur. On the other hand, since the thick film is gradually cooled from the cast drum side having a large heat capacity toward the opposite surface, the heat contraction on the cast drum side is larger than that on the opposite surface and distortion is likely to occur. As a result, the retardation change with time tends to increase.

(Winding)
It is preferable to trim both ends before winding. The trimmed portion may be reused as a film raw material. As the trimming cutter, any rotary cutter, shear blade, knife, or the like may be used. Regarding the material, carbon steel, stainless steel, and ceramic can be used.
A preferable winding tension is 1 kg / m width to 50 kg / width, more preferably 3 kg / m width to 20 kg / m width. The take-up tension may be taken up with a constant take-up tension, but it is more preferable that the take-up tension be taper according to the take-up diameter.
It is also necessary to adjust the draw ratio between the nip rolls so that the film does not receive a tension higher than the specified tension in the middle of the line.
Prior to winding, a laminated film may be attached to at least one side.

  FIG. 1 shows a schematic view of an apparatus for carrying out melt film formation that can be preferably employed in the present invention. In the figure, 101 is an extruder, 102 is a gear pump, 103 is a filtration unit (filter), 104 is a die, 105 is a touch roll, 106 is a cast drum (casting cooling drum), 107 is cellulose acylate, and 108 is a longitudinal stretching unit. , 109 is a transversely extending portion, and 110 is a winding portion. The stretching will be described later.

<Physical properties of unstretched cellulose acylate film>
The unstretched cellulose acylate film thus obtained preferably has Re = 0 to 20 nm and Rth = 0 to 80 nm, more preferably Re = 0 to 10 nm and Rth = 0 to 60 nm.
In the present application, Re and Rth respectively represent in-plane retardation and retardation in the thickness direction at a wavelength of 590 ± 5 nm (hereinafter referred to as wavelength λ). Re is measured in KOBRA 21ADH or WR (manufactured by Oji Scientific Instruments) by making light having a wavelength of λ nm incident in the normal direction of the film.
When the film to be measured is represented by a uniaxial or biaxial refractive index ellipsoid, Rth is calculated by the following method.
Rth is defined as Re, with the in-plane slow axis (determined by KOBRA 21ADH or WR) as the tilt axis (rotation axis) (in the absence of the slow axis, any direction in the film plane is the rotation axis). )) At a step of 10 degrees from the normal direction to 50 degrees on one side with respect to the film normal direction, light of wavelength λ nm is incident from each inclined direction, and a total of 6 points are measured, and the measured retardation value KOBRA 21ADH or WR is calculated based on the assumed average refractive index and the input film thickness value.
In the above case, in the case of a film having a direction in which the retardation value is zero at a certain tilt angle with the in-plane slow axis from the normal direction as the rotation axis, retardation at a tilt angle larger than the tilt angle. The value is calculated by KOBRA 21ADH or WR after changing its sign to negative.
In addition, the retardation value is measured from the two inclined directions, with the slow axis as the tilt axis (rotation axis) (in the absence of the slow axis, the arbitrary direction in the film plane is the rotation axis), Rth can also be calculated from the following formula (21) and formula (22) based on the value, the assumed value of the average refractive index, and the input film thickness value.

上記のＲｅ（θ）は法線方向から角度θ傾斜した方向におけるレターデーション値を表す。
式（２１）におけるｎｘは面内における遅相軸方向の屈折率を表し、ｎｙは面内においてｎｘに直交する方向の屈折率を表し、ｎｚはｎｘおよびｎｙに直交する方向の屈折率を表す。
Ｒｔｈ＝（（ｎｘ＋ｎｙ）／２−ｎｚ）×ｄ −−− 式（２２）
測定されるフィルムが１軸や２軸の屈折率楕円体で表現できないもの、いわゆる光学軸（ｏｐｔｉｃ ａｘｉｓ）がないフィルムの場合には、以下の方法によりＲｔｈは算出される。
Ｒｔｈは前記Ｒｅを、面内の遅相軸（ＫＯＢＲＡ ２１ＡＤＨまたはＷＲにより判断される）を傾斜軸（回転軸）としてフィルム法線方向に対して−５０度から＋５０度まで１０度ステップで各々その傾斜した方向から波長λｎｍの光を入射させて１１点測定し、その測定されたレターデーション値と平均屈折率の仮定値および入力された膜厚値を基にＫＯＢＲＡ ２１ＡＤＨまたはＷＲが算出する。
上記の測定において、平均屈折率の仮定値は ポリマーハンドブック（ＪＯＨＮ ＷＩＬＥＹ＆ＳＯＮＳ，ＩＮＣ）、各種光学フィルムのカタログの値を使用することができる。平均屈折率の値が既知でないものについてはアッベ屈折計で測定することができる。主な光学フィルムの平均屈折率の値を以下に例示する： セルロースアシレート（１．４８）、シクロオレフィンポリマー（１．５２）、ポリカーボネート（１．５９）、ポリメチルメタクリレート（１．４９）、ポリスチレン（１．５９）である。これら平均屈折率の仮定値と膜厚を入力することで、ＫＯＢＲＡ ２１ＡＤＨまたはＷＲはｎｘ、ｎｙ、ｎｚを算出する。この算出されたｎｘ、ｎｙ、ｎｚよりＮｚ＝（ｎｘ−ｎｚ）／（ｎｘ−ｎｙ）がさらに算出される。

The above Re (θ) represents a retardation value in a direction inclined by an angle θ from the normal direction.
In formula (21), nx represents the refractive index in the slow axis direction in the plane, ny represents the refractive index in the direction perpendicular to nx in the plane, and nz represents the refractive index in the direction perpendicular to nx and ny. .
Rth = ((nx + ny) / 2−nz) × d −−− Formula (22)
In the case where the film to be measured cannot be expressed by a uniaxial or biaxial refractive index ellipsoid, that is, a film having no so-called optical axis, Rth is calculated by the following method.
Rth is the Re in 10 degree steps from −50 degrees to +50 degrees with respect to the normal direction of the film, with the in-plane slow axis (determined by KOBRA 21ADH or WR) as the tilt axis (rotation axis). Eleven light points having a wavelength of λ nm are incident from the inclined direction, and KOBRA 21ADH or WR is calculated based on the measured retardation value, the assumed average refractive index, and the input film thickness value.
In the above measurement, the assumed value of the average refractive index may be a value in a polymer handbook (John Wiley & Sons, Inc.) or a catalog of various optical films. Those whose average refractive index is not known can be measured with an Abbe refractometer. The average refractive index values of the main optical films are exemplified below: cellulose acylate (1.48), cycloolefin polymer (1.52), polycarbonate (1.59), polymethyl methacrylate (1.49), Polystyrene (1.59). By inputting these assumed values of average refractive index and film thickness, KOBRA 21ADH or WR calculates nx, ny, and nz. Nz = (nx−nz) / (nx−ny) is further calculated from the calculated nx, ny, and nz.

The total light transmittance of the unstretched cellulose acylate film is preferably 90% to 100%. The haze is usually 0 to 1%, preferably 0 to 0.6%.
The tensile elastic modulus is preferably 1.0 kN / mm ^{2 to} 3.5 kN / mm ² , more preferably 1.4 kN / mm ^{2 to} 2.6 kN / mm ² . The elongation at break is preferably 8% to 400%, more preferably 10% to 300%, and even more preferably 15% to 200%.
Tg is preferably 95 ° C to 145 ° C. The thermal dimensional change at 80 ° C. for one day is preferably 0% to ± 1% in both the vertical and horizontal directions, and more preferably 0% to ± 0.3%.
40 ° C., water permeability at 90% relative humidity, preferably 300 g / m ² · day to 1000 g / m ² · day, more preferably from 500 g / m ² · day ~800g / m ² · day. The equilibrium water content at 25 ° C. and 80% relative humidity is preferably 1% by mass to 4% by mass, and more preferably 1.5% by mass to 2.5% by mass.

<Physical properties of stretched and stretched cellulose acylate film>
<Extension>
The reason why the film of the present invention is easy to stretch is that the film of the present invention has a small apparent activation energy, that is, the position of the polymer main chain can be changed with low tension because the position of the polymer main chain can be changed with small energy. It can be oriented. In addition, since the film produced according to the present invention has small thickness unevenness and uniform tension, occurrence of thickness unevenness in the stretching process can be suppressed.
Therefore, it is preferable that the cellulose acylate film of the present invention is longitudinally stretched and / or laterally stretched. Either one of the longitudinal stretching and the lateral stretching may be performed, or both may be performed. Further, the longitudinal stretching and the lateral stretching may each be performed once, or may be performed a plurality of times, and the longitudinal stretching and the lateral stretching may be performed simultaneously.

The draw ratio in this invention is calculated | required using the following formula | equation.
Elongation ratio (%) = 100 × {(Length after stretching) − (Length before stretching)} / (Length before stretching)

  Such stretching may be performed in the longitudinal direction using two or more pairs of nip rolls with increased peripheral speed on the outlet side (longitudinal stretching), and both ends of the film are gripped with chucks and are orthogonally crossed (longitudinal). In a direction perpendicular to the direction) (lateral stretching). Moreover, you may use the simultaneous biaxial stretching method as described in Unexamined-Japanese-Patent No. 2000-37772, Unexamined-Japanese-Patent No. 2001-113591, and Unexamined-Japanese-Patent No. 2002-103445.

Specifically, it is preferable to use the following stretching method.
(1) Longitudinal Stretching Longitudinal stretching can be achieved by installing two pairs of nip rolls and heating the gap between them so that the peripheral speed of the outlet side nip roll is faster than the peripheral speed of the inlet side nip roll. At this time, the expression of retardation (Rth) in the thickness direction can be changed by changing the distance (L) between the nip rolls and the film width (W) before stretching. When L / W (referred to as aspect ratio) exceeds 2 and is 50 or less (long span stretching), Rth can be decreased, and when the aspect ratio is 0.01 to 0.3 (short span stretching), Rth can be increased. These are appropriately used according to the purpose (target value of Rth). Details will be described below.

(1-1) Long span stretching The film is stretched as it is stretched. At this time, the film is reduced in thickness and width to reduce the volume change. At this time, shrinkage in the width direction is limited by friction between the nip roll and the film. For this reason, when the nip roll interval is increased, it is easy to contract in the width direction, and thickness reduction can be suppressed. When the thickness reduction is large, the same effect as that in which the film is compressed in the thickness direction is obtained. On the contrary, when the aspect ratio is large and the thickness reduction is small, Rth hardly appears and low Rth can be realized.
Furthermore, if the aspect ratio is long, the uniformity in the width direction can be improved. This is due to the following reason.
• The film tends to shrink in the width direction as it is stretched. At the central portion in the width direction, both sides thereof also try to contract in the width direction, so that it becomes a tug of war and cannot be contracted freely.
-On the other hand, the film width direction end part is in a tug-of-war state only on one side and can contract relatively freely.
-The difference in shrinkage behavior associated with the stretching between both ends and the central portion becomes stretching unevenness in the width direction.
Due to such non-uniformity between both ends and the center, retardation in the width direction and axial deviation (orientation angle distribution of slow axis) occur. On the other hand, since long span stretching is performed slowly between two long nip rolls, uniformity of these non-uniformities (molecular orientation becomes uniform) proceeds during stretching. On the other hand, in normal longitudinal stretching (aspect ratio = more than 0.3 and less than 2), such homogenization does not occur.

The aspect ratio exceeds 2 and is preferably 50 or less, more preferably 3 to 40, and still more preferably 4 to 20. The stretching temperature is preferably (Tg−5 ° C.) to (Tg + 100) ° C., more preferably (Tg) to (Tg + 50) ° C., and further preferably (Tg + 5) to (Tg + 30) ° C. The draw ratio is preferably 1.05 to 3 times, more preferably 1.05 to 1.7 times, and still more preferably 1.05 to 1.4 times. Such long span stretching may be performed in multiple stages with three or more pairs of nip rolls as long as the longest aspect ratio is within the above range.
Such long span stretching may be performed by heating the film between two pairs of nip rolls separated by a predetermined distance. The heating method is a heater heating method (infrared heater, halogen heater, panel heater, etc. above or below the film). Or heating by radiant heat) or a zone heating method (heating in a zone in which hot air or the like is blown and adjusted to a predetermined temperature) may be used. In the present invention, the zone heating method is preferable from the viewpoint of uniformity of the stretching temperature. At this time, the nip roll may be installed in the stretching zone or out of the zone, but in order to prevent the film and the nip roll from sticking, it is preferably out of the zone. It is also preferable to preheat the film before such stretching, and the preheating temperature in this case is preferably (Tg−80 ° C.) to (Tg + 100 ° C.).

By such stretching, a film having an Re value of preferably 0 to 200 nm, more preferably 10 to 200 nm, and even more preferably 15 to 100 nm is obtained. Further, by such stretching, a film having an Rth value of preferably 30 to 500 nm, more preferably 50 to 400 nm, and still more preferably 70 to 350 nm is obtained. By this stretching method, the ratio of Rth and Re (Rth / Re) can be, for example, 0.4 to 0.6, preferably 0.45 to 0.55. Furthermore, by such stretching, both the Re value and the Rth value can be changed to, for example, 5% or less, preferably 4% or less, more preferably 3% or less.
By such stretching, the ratio of the film width before and after stretching (film width after stretching / film width before stretching) is, for example, 0.5 to 0.9, preferably 0.6 to 0.85, more preferably It can be set to 0.65 to 0.83.

(1-2) Short span stretching The aspect ratio (L / W) is, for example, more than 0.01 and less than 0.3, preferably 0.03 to 0.25, more preferably 0.05 to 0.2. Perform longitudinal stretching (short span stretching). By performing stretching at an aspect ratio (L / W) in such a range, neck-in (shrinkage in the direction orthogonal to stretching accompanying stretching) can be reduced. Although the width and thickness are reduced to compensate for stretching in the stretching direction, such short span stretching suppresses width shrinkage and preferentially reduces the thickness. As a result, the film is compressed in the thickness direction, and the orientation (plane orientation) in the thickness direction proceeds. As a result, the Rth value, which is a measure of the anisotropy in the thickness direction, tends to increase. On the other hand, conventionally, the aspect ratio (L / W) is generally about 1 (0.7 to 1.5). This is usually done by installing a heater for heating between the nip rolls, but if the L / W becomes too large, the film cannot be heated uniformly with the heater, uneven stretching tends to occur, and if the L / W is too small. This is because the heater is difficult to install and cannot be heated sufficiently.
The short span stretching described above can be carried out by changing the conveying speed between two or more pairs of nip rolls, but unlike the normal roll arrangement (FIG. 2), the two pairs of nip rolls are slanted (the rotation axes of the front and rear nip rolls are aligned). This can be achieved by shifting it up and down (FIG. 3). Accordingly, since a heater for heating cannot be installed between the nip rolls, it is preferable to raise the temperature of the film by flowing a heating medium in the nip rolls. Furthermore, it is also preferable to provide a preheating roll in which a heating medium is flowed inside before the entrance side nip roll, and to heat the film before stretching.
The stretching temperature is preferably (Tg-5 ° C) to (Tg + 100) ° C, more preferably (Tg) to (Tg + 50) ° C, still more preferably (Tg + 5) to (Tg + 30) ° C, and a preferable preheating temperature. Is Tg-80 ° C to Tg + 100 ° C.

Here, the long span stretching and the short span stretching will be described in detail.
FIG. 2 is a schematic configuration diagram of the film manufacturing apparatus 10 in the case of manufacturing a thermoplastic film by melt film formation when performing long span stretching.
The film manufacturing apparatus 10 is an apparatus for manufacturing a thermoplastic film F that can be used in a liquid crystal display device or the like. After the pelletized cellulose acylate resin or cycloolefin resin, which is a raw material of the thermoplastic film F, is introduced into the dryer 12 and dried, the pellet is extruded by the extruder 14 and supplied to the filter 18 by the gear pump 16. Next, the foreign matter is filtered by the filter 18 and pushed out from the die 20. Thereafter, the film is sandwiched between the cast drum 28 and the touch roll 24, passes between the cast drums 26 to 28, and solidifies to form an unstretched film Fa having a predetermined surface roughness. And this unstretched film Fa is supplied to the longitudinal stretch part 30 which performs long span stretching.
In the longitudinal stretching section 30, the unstretched film Fa is stretched in the transport direction between the inlet side nip roll 32 and the outlet side nip roller 34 to obtain a longitudinally stretched film Fb. FIG. 3 is a perspective explanatory view of the longitudinal stretching unit 30, and the longitudinal stretching aspect ratio (L / W) is determined by the distance L between the inlet-side nip roll 32 and the outlet-side nip roller 34 and the inlet-side nip roll 32. And the width W of the outlet side nip roller 34 in the length direction. Next, the longitudinally stretched film Fb is adjusted to a predetermined preheating temperature by passing through the preheating unit 36 and then supplied to the lateral stretching unit 42.
In the laterally stretched portion 42, the longitudinally stretched film Fb is stretched in the width direction orthogonal to the transport direction to form a laterally stretched film Fc. Then, the laterally stretched film Fc is supplied to the heat fixing unit 44 and wound up by the winding unit 46, whereby the thermoplastic film F that is the final product in which the orientation angle and retardation are adjusted is manufactured. The transversely stretched film Fc may be further subjected to heat relaxation treatment after passing through the heat fixing portion 44.

On the other hand, FIG. 4 is a schematic configuration diagram of a film manufacturing apparatus 10a in which a longitudinal stretching unit 30a that performs short span stretching is used instead of the longitudinal stretching unit 30 that performs long span stretching shown in FIGS.
In this film manufacturing apparatus 10a, the unstretched film Fa is preheated to a predetermined temperature by the preheating rolls 33 and 35 and then supplied between the two sets of nip rolls 37 and 39 for longitudinal stretching. In this case, the nip rolls 37 and 39 are disposed in the vicinity of the transport direction of the unstretched film Fa and are disposed so that the height differs by a predetermined distance in the vertical direction. By disposing the nip rolls 37 and 39 in this way, the transport distance of the unstretched film Fa in the longitudinal stretching portion 30a can be secured, and the distance between the mechanisms disposed before and after the longitudinal stretching portion 30a can be shortened. The manufacturing apparatus 10a can be downsized.
FIG. 5 is an explanatory perspective view of the longitudinally stretched portion 30a, and the longitudinal stretch aspect ratio (L / W) is the distance L in the transport direction of the unstretched film Fa nipped by the nip rolls 37 and 39. , And the width W in the length direction of the nip rolls 37 and 39.

(2) Lateral stretching Re and Rth can be adjusted by combining longitudinal stretching and lateral stretching. Either longitudinal stretching or lateral uniaxial stretching may be used, but by combining the stretching in both directions, it is easy to adjust that the orientation in the stretching direction advances and the absolute value of Re increases excessively. Further, by combining the longitudinal stretching and the lateral stretching, there is an advantage that the longitudinal orientation and the lateral orientation are offset and Re can be reduced. Furthermore, since the film is stretched in both the vertical and horizontal directions, the thickness reduction is increased, the plane orientation is advanced, and Rth can be increased.
Either the longitudinal stretching or the lateral stretching may be performed first and may be performed at the same time, but a method of performing lateral stretching after the longitudinal stretching is more preferable. Thereby, an installation can be made compact. Although longitudinal stretching and lateral stretching may be performed independently or continuously, it is more preferable to perform them continuously.
The transverse stretching can be performed using, for example, a tenter. That is, the film is stretched by holding both ends in the width direction with clips and widening the film in the lateral direction. At this time, the stretching temperature can be controlled by sending wind at a desired temperature into the tenter. The stretching temperature is preferably (Tg-10) ° C to (Tg + 60) ° C, more preferably (Tg-5) ° C to (Tg + 45) ° C, and still more preferably (Tg) to (Tg + 30) ° C. A preferable draw ratio is 1.01 times to 4 times, more preferably 1.03 times to 3.5 times, and still more preferably 1.05 times to 2.5 times. The ratio of transverse stretching to longitudinal stretching (lateral stretching ratio / longitudinal stretching ratio) is preferably 1.1 to 100 or 0.9 to 0.01, more preferably 2 to 60 or 0.5 to 0.017, Preferably it is 4-40 or 0.25-0.025.

Preheating can be performed before such stretching, and heat treatment can be performed after stretching. By adopting such means, the Re and Rth distribution after stretching can be reduced, and the variation in orientation angle associated with bowing can be reduced. Either preheating or heat treatment may be performed, but it is more preferable to perform both. These preheating and heat treatment are preferably performed by holding with a clip, that is, preferably performed continuously with stretching.
Preheating is preferably performed at a temperature higher than the stretching temperature by 1 ° C to 50 ° C, more preferably 2 ° C to 40 ° C, and even more preferably 3 ° C to 30 ° C. The preheating time is preferably 1 second to 10 minutes, more preferably 5 seconds to 4 minutes, and further preferably 10 seconds to 2 minutes.
The heat treatment is preferably performed at a temperature lower than the stretching temperature by 1 ° C to 50 ° C, more preferably 2 ° C to 40 ° C, and even more preferably 3 ° C to 30 ° C. More preferably, the temperature is not more than the stretching temperature and not more than Tg. The preheating time is preferably 1 second to 10 minutes, more preferably 5 seconds to 4 minutes, and further preferably 10 seconds to 2 minutes.
Such preheating and heat treatment can reduce the variation in orientation angle and Re and Rth for the following reasons.
The film is stretched in the width direction and tends to become thin (neck-in) in the orthogonal direction (longitudinal direction).
-For this reason, the film before and after transverse stretching is pulled and stress is generated. However, both ends in the width direction are fixed by chucks and are not easily deformed by stress, and the central portion in the width direction is easily deformed. As a result, the stress caused by the neck-in is deformed into a bow shape and bowing occurs. As a result, in-plane Re and Rth unevenness and distribution of orientation axes occur.
In order to suppress this, if the temperature on the preheating side (before stretching) is increased and the temperature on the heat treatment (after stretching) is lowered, neck-in occurs on the high temperature side (preheating) with a lower elastic modulus, and heat treatment ( It becomes difficult to occur after stretching). That is, when heat setting is not performed, as shown in FIG. 6, a convex bowing is generated on the upstream side in the conveyance direction near the exit of the transverse stretching zone of the film F after transverse stretching. By performing heat fixing in the heat fixing part 44 immediately after the extending part 42, as shown in FIG. 7, it is possible to suppress the occurrence of bowing that is convex on the upstream side in the transport direction. Further, when preheating is performed in the preheating section 36 immediately before the lateral stretching section 42, the resin distribution easily spreads in the transport direction downstream near the entrance of the lateral stretching section 42, and uniform lateral stretching becomes possible. Convex bowing hardly occurs on the upstream side in the transport direction near the exit of the laterally extending portion 42. As a result, bowing after stretching can be suppressed.

  By such stretching, the fluctuations of Re and Rth depending on the location in the width direction and the longitudinal direction are both preferably 5% or less, more preferably 4% or less, and still more preferably 3% or less. Further, the orientation angle is preferably 90 ° ± 5 ° or less or 0 ° ± 5 ° or less, more preferably 90 ° ± 3 ° or less or 0 ° ± 3 ° or less, and 90 ° ± 1 ° or less. Or it is more preferable to set it as 0 degrees ± 1 degrees or less.

(3) Relaxation Further, dimensional stability can be improved by performing a relaxation treatment after the stretching. The thermal relaxation is preferably performed after longitudinal stretching, either after lateral stretching, or both, and more preferably after lateral stretching. The relaxation treatment may be performed online continuously after stretching, or may be performed offline after winding after stretching.
The thermal relaxation is preferably (Tg-50) ° C to (Tg + 30) ° C, more preferably (Tg-30) ° C to (Tg + 20) ° C, more preferably (Tg-15) ° C to (Tg + 10) ° C, preferably 1 second to 10 minutes, more preferably 5 seconds to 4 minutes, even more preferably 10 seconds to 2 minutes, preferably 0.1 kg / m to 20 kg / m, more preferably 1 kg / m to 16 kg / m, still more preferably 2 kg It is carried out while transporting at a tension of / m to 12 kg / m.

(Physical properties after stretching)
The physical properties of the stretched cellulose acylate film are preferably in the following ranges.
The tensile modulus is preferably 1.0 kN / mm ² or more and less than 3.0 kN / mm ² , more preferably 1.3 kN / mm ^{2 to} 2.6 kN / mm ² .
The breaking elongation is preferably 3% to 200%, more preferably 8% to 150%.
Tg is preferably 95 ° C to 145 ° C, more preferably 105 ° C to 135 ° C.
The thermal dimensional change after standing at 80 ° C. for 1 day is preferably 0% to ± 1% in both the vertical and horizontal directions, and more preferably 0% to ± 0.3%.
40 ° C., water permeability at 90% relative humidity, 300 g / m ² · day to 1000 g / m ² · day is preferred, more preferably 500 g / m ² · day ~800g / m ² · day.
The equilibrium moisture content at 25 ° C. and 80% relative humidity is preferably 1 to 4% by mass, more preferably 1.5 to 2.5% by mass.
The haze is preferably 0% to 3%, more preferably 0% to 1% or less. The total light transmittance is preferably 90% to 100%.
The amount of residual solvent is 0.01% by mass or less, preferably zero. Unlike the solution casting method using a solvent, if the film is formed by the above melt casting method, the amount of residual solvent becomes zero because no solvent is used.
Re and Rth preferably satisfy the following formulas (R-1) and (R-2).
Formula (R-1): 0 nm ≦ Re ≦ 200 nm
Formula (R-2): 0 nm ≦ Rth ≦ 600 nm
(In the formula, Re represents in-plane retardation of the thermoplastic film, and Rth represents the thickness direction retardation of the thermoplastic film.)

More preferably,
Rth ≧ Re × 1.1
180 ≧ Re ≧ 10
400 ≧ Rth ≧ 50
And more preferably
Rth ≧ Re × 1.2
150 ≧ Re ≧ 20
300 ≧ Rth ≧ 100
It is.

The angle θ formed by the film forming direction (longitudinal direction) and the slow axis of Re of the film is preferably closer to 0 °, + 90 °, or −90 °. That is, in the case of longitudinal stretching, the closer to 0 °, the more preferable. Specifically, it is preferably 0 ± 3 °, more preferably 0 ± 2 °, and further preferably 0 ± 1 °. In the case of transverse stretching, 90 ± 3 ° or −90 ± 3 ° is preferable, 90 ± 2 ° or −90 ± 2 ° is more preferable, and 90 ± 1 ° or −90 ± 1 ° is further preferable.
As for the thickness of the cellulose acylate film after extending | stretching, 15 micrometers-200 micrometers are all preferable, 20 micrometers-100 micrometers are more preferable, and 30 micrometers-60 micrometers are still more preferable. The thickness unevenness is preferably within 3% in both the longitudinal direction and the width direction, more preferably within 2%, and even more preferably within 1%.
By using a thin film, residual strain is less likely to remain in the film, and retardation changes with time are less likely to occur. This is because when cooling after stretching, if the thickness is thick, the internal cooling is delayed as compared to the surface, and residual strain due to the difference in thermal shrinkage tends to occur.

<Treatment for cellulose acylate film>
Next, the treatment that can be performed on the cellulose acylate film of the present invention will be described with reference to preferred embodiments.

(surface treatment)
The cellulose acylate film can achieve improved adhesion between the cellulose acylate film and each functional layer (for example, the undercoat layer and the back layer) by optionally performing a surface treatment. For example, glow discharge treatment, ultraviolet irradiation treatment, corona treatment, flame treatment, acid or alkali treatment can be used. The glow discharge treatment here may be low-temperature plasma that occurs in a low-pressure gas of 10 ^{−3 to} 20 Torr, or may be plasma treatment under atmospheric pressure. Plasma-excitable gas refers to gas that is plasma-excited under the above conditions, and includes chlorofluorocarbons such as argon, helium, neon, krypton, xenon, nitrogen, carbon dioxide, tetrafluoromethane, and mixtures thereof. Can be mentioned. Details of these are described in detail in pages 30 to 32 of the Japan Society of Invention Disclosure Technical Bulletin (Public Technical Number 2001-1745, published on March 15, 2001, Japan Institute of Invention). In the plasma treatment at atmospheric pressure, which has been attracting attention in recent years, for example, irradiation energy of 20 to 500 kGy is used under 10 to 1000 keV, and more preferably irradiation energy of 20 to 300 kGy is used under 30 to 500 keV. Among these, an alkali saponification treatment is particularly preferable, and it is extremely effective as a surface treatment of a cellulose acylate film.

  The alkali saponification treatment may be immersed in a saponification solution or coated with a saponification solution. In the case of the immersion method, it is achieved by passing an aqueous solution of pH 10 to 14 such as NaOH or KOH through a bath heated to 20 ° C. to 80 ° C. for 0.1 minutes to 10 minutes, followed by neutralization, washing with water and drying. it can.

  In the case of the coating method, a dip coating method, a curtain coating method, an extrusion coating method, a bar coating method, and an E-type coating method can be used. The solvent of the alkali saponification coating solution has good wettability because it is applied to the transparent support of the saponification solution, and the surface state remains good without forming irregularities on the surface of the transparent support by the saponification solution solvent. It is preferred to select a solvent to keep. Specifically, an alcohol solvent is preferable, and isopropyl alcohol is particularly preferable. An aqueous solution of a surfactant can also be used as a solvent. The alkali of the alkali saponification coating solution is preferably an alkali that dissolves in the above solvent, and more preferably KOH or NaOH. The pH of the saponification coating solution is preferably 10 or more, more preferably 12 or more. The reaction conditions at the time of alkali saponification are preferably 1 second to 5 minutes at room temperature, more preferably 5 seconds to 5 minutes, and particularly preferably 20 seconds to 3 minutes. After the alkali saponification reaction, it is preferable to wash the surface on which the saponification solution is applied with water or with an acid and then with water. Further, the coating-type saponification treatment and the alignment film uncoating described later can be performed continuously, and the number of steps can be reduced. Specifically, these saponification methods are described in, for example, JP-A No. 2002-82226 and WO 02/46809 pamphlet.

  It is also preferable to provide an undercoat layer for adhesion to the functional layer. This layer may be applied after the above surface treatment or may be applied without the surface treatment. The details of the undercoat layer are described on page 32 of the Japan Society for Invention and Innovation (Public Technical Number 2001-1745, published on March 15, 2001, Japan Institute of Invention).

  These surface treatment and undercoating processes can be incorporated at the end of the film forming process, can be performed alone, or can be performed in the functional layer application process described later.

<< Use of Cellulose Acylate Film of the Present Invention >>
The cellulose acylate film of the present invention is combined with the functional layer described in detail on pages 32 to 45 of the Japan Society for Invention and Technology (Public Technical Number 2001-1745, issued on March 15, 2001, Japan Society of Invention). It is preferable. Among these, application of a polarizing film (polarizing plate), application of an optical compensation layer (optical compensation sheet), and application of an antireflection layer (antireflection film) are preferable. This will be described in order below.

(1) Application of polarizing film (preparation of polarizing plate)
(Material used)
At present, commercially available polarizing films are generally prepared by immersing a stretched polymer in a solution of iodine or dichroic dye in a bath and allowing the iodine or dichroic dye to penetrate into the binder. is there. As the polarizing film, a coating type polarizing film represented by Optiva Inc. can also be used. The iodine and the dichroic dye in the polarizing film develop polarizing performance by being oriented in the binder. As the dichroic dye, an azo dye, stilbene dye, pyrazolone dye, triphenylmethane dye, quinoline dye, oxazine dye, thiazine dye or anthraquinone dye is used. The dichroic dye is preferably water-soluble. The dichroic dye preferably has a hydrophilic substituent (for example, sulfo, amino, hydroxyl). For example, the Japan Society of Invention Disclosure Technique (Public Technical Number 2001-1745, Issue Date 200
Examples of the compounds described on page 58, March 15, 1).

  As the binder for the polarizing film, either a polymer that can be crosslinked by itself or a polymer that is crosslinked by a crosslinking agent can be used, and a plurality of combinations thereof can be used. Examples of the binder include methacrylate copolymer, styrene copolymer, polyolefin, polyvinyl alcohol and modified polyvinyl alcohol, poly (N-methylolacrylamide) described in paragraph No. [0022] of JP-A-8-338913. , Polyester, polyimide, vinyl acetate copolymer, carboxymethyl cellulose, polycarbonate and the like. Silane coupling agents can be used as the polymer. Water-soluble polymers (for example, poly (N-methylolacrylamide), carboxymethylcellulose, gelatin, polyvinyl alcohol, and modified polyvinyl alcohol) are preferable, gelatin, polyvinyl alcohol, and modified polyvinyl alcohol are more preferable, and polyvinyl alcohol and modified polyvinyl alcohol are most preferable. . It is particularly preferable to use two types of polyvinyl alcohol or modified polyvinyl alcohol having different degrees of polymerization. The saponification degree of polyvinyl alcohol is preferably 70 to 100%, more preferably 80 to 100%. It is preferable that the polymerization degree of polyvinyl alcohol is 100-5000. The modified polyvinyl alcohol is described in JP-A-8-338913, JP-A-9-152509 and JP-A-9-316127. Two or more kinds of polyvinyl alcohol and modified polyvinyl alcohol may be used in combination.

  The lower limit of the binder thickness is preferably 10 μm. The upper limit of the thickness is preferably as thin as possible from the viewpoint of light leakage of the liquid crystal display device. It is preferably not more than a commercially available polarizing plate (about 30 μm), preferably 25 μm or less, and more preferably 20 μm or less.

  The binder of the polarizing film may be cross-linked. A polymer or monomer having a crosslinkable functional group may be mixed in the binder, or a crosslinkable functional group may be imparted to the binder polymer itself. Crosslinking can be performed by light, heat, or pH change, and a binder having a crosslinked structure can be formed. The crosslinking agent is described in US Reissue Patent 23297. Boron compounds (for example, boric acid and borax) can also be used as a crosslinking agent. The addition amount of the crosslinking agent in the binder is preferably 0.1 to 20% by mass with respect to the binder. The orientation of the polarizing element and the wet heat resistance of the polarizing film are improved.

  Even after the crosslinking reaction is completed, the unreacted crosslinking agent is preferably 1.0% by mass or less, and more preferably 0.5% by mass or less. By doing in this way, a weather resistance improves.

(Stretching)
The polarizing film is preferably dyed with iodine or a dichroic dye after the polarizing film is stretched (stretching method) or rubbed (rubbing method).

  In the stretching method, the stretching ratio is preferably 2.5 to 30.0 times, and more preferably 3.0 to 10.0 times. Stretching can be performed by dry stretching in air. Moreover, you may implement wet extending | stretching in the state immersed in water. The stretch ratio of dry stretching is preferably 2.5 to 5.0 times, and the stretch ratio of wet stretching is preferably 3.0 to 10.0 times. These stretching operations may be performed once or divided into several times. By dividing into several times, it is possible to stretch more uniformly even at high magnification. Stretching can be carried out by the following method.

  Prior to stretching, the PVA film is swollen. The degree of swelling is 1.2 to 2.0 times (mass ratio before swelling and after swelling). Thereafter, the film is stretched at a bath temperature of 15 to 50 ° C., particularly 17 to 40 ° C. in an aqueous medium bath or a dye bath for dissolving a dichroic substance while being continuously conveyed through a guide roll or the like. Stretching can be achieved by gripping with two pairs of nip rolls and increasing the conveyance speed of the subsequent nip roll to be higher than that of the previous nip roll. The draw ratio is based on the length ratio after stretching / initial state (hereinafter the same), but the preferred draw ratio is 1.2 to 3.5 times, particularly 1.5 to 3.0 times in view of the above-mentioned effects. . Thereafter, the film is dried at 50 ° C. to 90 ° C. to obtain a polarizing film.

[Lamination]
The saponified cellulose acylate film and a polarizing film prepared by stretching are bonded to prepare a polarizing plate. The laminating direction is preferably such that the casting axis direction of the cellulose acylate film and the stretching axis direction of the polarizing plate are 45 degrees.

  The adhesive for bonding is not particularly limited, but examples thereof include PVA resins (including modified PVA such as acetoacetyl group, sulfonic acid group, carboxyl group, oxyalkylene group) and boron compound aqueous solution. preferable. The thickness of the adhesive layer is preferably 0.01 to 10 μm, and particularly preferably 0.05 to 5 μm after drying.

  The polarizing plate thus obtained preferably has a higher light transmittance, and preferably has a higher degree of polarization. The transmittance of the polarizing plate is preferably in the range of 30 to 50%, more preferably in the range of 35 to 50%, and most preferably in the range of 40 to 50% in light having a wavelength of 550 nm. . The degree of polarization is preferably in the range of 90 to 100%, more preferably in the range of 95 to 100%, and most preferably in the range of 99 to 100% in light having a wavelength of 550 nm.

  Furthermore, the polarizing plate thus obtained can be laminated with a λ / 4 plate to produce circularly polarized light. In this case, lamination is performed so that the slow axis of λ / 4 and the absorption axis of the polarizing plate are 45 degrees. At this time, λ / 4 is not particularly limited, but more preferably has a wavelength dependency such that the lower the wavelength, the smaller the retardation. Furthermore, it is preferable to use a polarizing film having an absorption axis inclined by 20 ° to 70 ° with respect to the longitudinal direction and a λ / 4 plate made of an optically anisotropic layer made of a liquid crystalline compound.

(2) Application of optical compensation layer (creation of optical compensation sheet)
The optically anisotropic layer is for compensating the liquid crystal compound in the liquid crystal cell in the black display of the liquid crystal display device, and forms an alignment film on the cellulose acylate film, and further provides an optically anisotropic layer. It is formed by doing.

(Alignment film)
An alignment film is provided on the surface-treated cellulose acylate film. This film has a function of defining the alignment direction of liquid crystalline molecules. However, if the alignment state is fixed after aligning the liquid crystalline compound, the alignment film plays the role, and thus is not necessarily an essential component of the present invention. That is, it is possible to produce the polarizing plate of the present invention by transferring only the optically anisotropic layer on the alignment film in which the alignment state is fixed onto the polarizer.

  The alignment film is an organic compound (for example, ω-tricosanoic acid) formed by rubbing treatment of an organic compound (preferably a polymer), oblique deposition of an inorganic compound, formation of a layer having a microgroove, or Langmuir-Blodget method (LB film). , Dioctadecylmethylammonium chloride, methyl stearylate). Furthermore, an alignment film in which an alignment function is generated by application of an electric field, application of a magnetic field, or light irradiation is also known.

  The alignment film is preferably formed by polymer rubbing treatment. In principle, the polymer used for the alignment film has a molecular structure having a function of aligning liquid crystal molecules.

  In the present invention, in addition to the function of aligning liquid crystalline molecules, a crosslink having a function of aligning a side chain having a crosslinkable functional group (for example, a double bond) to the main chain or aligning liquid crystalline molecules. It is preferable to introduce a functional functional group into the side chain.

  As the polymer used for the alignment film, either a polymer that can be crosslinked by itself or a polymer that is crosslinked by a crosslinking agent can be used, and a plurality of combinations thereof can be used. Examples of the polymer include methacrylate copolymers, styrene copolymers, polyolefins, polyvinyl alcohol and modified polyvinyl alcohol, poly (N-methylol) described in paragraph No. [0022] of JP-A-8-338913. Acrylamide), polyester, polyimide, vinyl acetate copolymer, carboxymethylcellulose, polycarbonate and the like. Silane coupling agents can be used as the polymer. Water-soluble polymers (for example, poly (N-methylolacrylamide), carboxymethylcellulose, gelatin, polyvinyl alcohol, and modified polyvinyl alcohol) are preferable, gelatin, polyvinyl alcohol, and modified polyvinyl alcohol are more preferable, and polyvinyl alcohol and modified polyvinyl alcohol are most preferable. . It is particularly preferable to use two types of polyvinyl alcohol or modified polyvinyl alcohol having different degrees of polymerization. The saponification degree of polyvinyl alcohol is preferably 70 to 100%, more preferably 80 to 100%. It is preferable that the polymerization degree of polyvinyl alcohol is 100-5000.

  A side chain having a function of aligning liquid crystal molecules generally has a hydrophobic group as a functional group. The specific type of functional group is determined according to the type of liquid crystal molecule and the required alignment state. For example, the modifying group of the modified polyvinyl alcohol can be introduced by copolymerization modification, chain transfer modification or block polymerization modification. Examples of modifying groups include hydrophilic groups (carboxylic acid groups, sulfonic acid groups, phosphonic acid groups, amino groups, ammonium groups, amide groups, thiol groups, etc.), hydrocarbon groups having 10 to 100 carbon atoms, fluorine atoms Substituted hydrocarbon groups, thioether groups, polymerizable groups (unsaturated polymerizable groups, epoxy groups, azirinidyl groups, etc.), alkoxysilyl groups (trialkoxy, dialkoxy, monoalkoxy) and the like can be mentioned. As specific examples of these modified polyvinyl alcohol compounds, for example, paragraph numbers [0022] to [0145] in JP-A No. 2000-155216 and paragraph numbers [0018] to [0018] in JP-A No. 2002-62426 are described. [0022] and the like.

  When a side chain having a crosslinkable functional group is bonded to the main chain of the alignment film polymer, or a crosslinkable functional group is introduced into a side chain having a function of aligning liquid crystalline molecules, the alignment film polymer and the optically anisotropic film The polyfunctional monomer contained in the conductive layer can be copolymerized. As a result, not only between the polyfunctional monomer and the polyfunctional monomer, but also between the alignment film polymer and the alignment film polymer and between the polyfunctional monomer and the alignment film polymer is firmly bonded by a covalent bond. Therefore, the strength of the optical compensation sheet can be remarkably improved by introducing the crosslinkable functional group into the alignment film polymer.

  The crosslinkable functional group of the alignment film polymer preferably contains a polymerizable group in the same manner as the polyfunctional monomer. Specific examples include those described in paragraphs [0080] to [0100] in JP-A-2000-155216. Apart from the crosslinkable functional group, the alignment film polymer can also be crosslinked using a crosslinking agent.

  Examples of the crosslinking agent include aldehydes, N-methylol compounds, dioxane derivatives, compounds that act by activating carboxyl groups, active vinyl compounds, active halogen compounds, isoxazole and dialdehyde starch. Two or more kinds of crosslinking agents may be used in combination. Specific examples include compounds described in paragraphs [0023] to [024] in JP-A-2002-62426. Aldehydes having high reaction activity, particularly glutaraldehyde are preferred.

  0.1-20 mass% is preferable with respect to a polymer, and, as for the addition amount of a crosslinking agent, 0.5-15 mass% is more preferable. The amount of the unreacted crosslinking agent remaining in the alignment film is preferably 1.0% by mass or less, and more preferably 0.5% by mass or less. By adjusting in this way, even if the alignment film is used for a long time in a liquid crystal display device or left in a high-temperature and high-humidity atmosphere for a long time, sufficient durability without generation of reticulation can be obtained.

  The alignment film can be basically formed by applying the polymer on the transparent support containing the alignment film forming material and the crosslinking agent, followed by drying by heating (crosslinking) and rubbing treatment. As described above, the crosslinking reaction may be performed at any time after coating on the transparent support. When a water-soluble polymer such as polyvinyl alcohol is used as the alignment film forming material, the coating liquid is preferably a mixed solvent of an organic solvent (for example, methanol) having a defoaming action and water. The ratio of water: methanol is preferably 0: 100 to 99: 1, and more preferably 0: 100 to 91: 9. Thereby, generation | occurrence | production of a bubble is suppressed and the defect of the layer surface of an alignment film and also an optical anisotropic layer reduces remarkably.

  The alignment film is preferably applied by spin coating, dip coating, curtain coating, extrusion coating, rod coating, or roll coating. A rod coating method is particularly preferable. The film thickness after drying is preferably 0.1 to 10 μm. Heating and drying can be performed at 20 ° C to 110 ° C. In order to form sufficient cross-linking, 60 ° C to 100 ° C is preferable, and 80 ° C to 100 ° C is particularly preferable. The drying time can be 1 minute to 36 hours, preferably 1 minute to 30 minutes. The pH is preferably set to an optimum value for the crosslinking agent to be used. When glutaraldehyde is used, the pH is 4.5 to 5.5, and 5 is particularly preferable.

  The alignment film is provided on the transparent support or the undercoat layer. The alignment film can be obtained by rubbing the surface after crosslinking the polymer layer as described above.

  For the rubbing treatment, a treatment method widely adopted as a liquid crystal alignment treatment process of LCD can be applied. That is, a method of obtaining the orientation by rubbing the surface of the orientation film in a certain direction using paper, gauze, felt, rubber, nylon, polyester fiber or the like can be used. Generally, it is carried out by rubbing several times using a cloth or the like in which fibers having a uniform length and thickness are planted on average.

When industrially implemented, this is achieved by bringing a rotating rubbing roll into contact with the film with the polarizing film being transported. However, the roundness, cylindricity, and deflection (eccentricity) of the rubbing roll can be any. Is preferably 30 μm or less. The film wrap angle on the rubbing roll is preferably 0.1 to 90 °. However, as described in JP-A-8-160430, a stable rubbing treatment can be obtained by winding 360 ° or more. As for the conveyance speed of a film, 1-100 m / min is preferable. It is preferable to select an appropriate rubbing angle in the range of 0 to 60 °. When used for a liquid crystal display device, 40 to 50 ° is preferable. 45 ° is particularly preferred.
The thickness of the alignment film thus obtained is preferably in the range of 0.1 to 10 μm.

  Next, the liquid crystalline molecules of the optically anisotropic layer are aligned on the alignment film. Thereafter, as necessary, the alignment film polymer and the polyfunctional monomer contained in the optically anisotropic layer are reacted, or the alignment film polymer is crosslinked using a crosslinking agent.

  The liquid crystalline molecules used in the optically anisotropic layer include rod-like liquid crystalline molecules and discotic liquid crystalline molecules. The rod-like liquid crystal molecules and the disk-like liquid crystal molecules may be high-molecular liquid crystals or low-molecular liquid crystals, and further include those in which low-molecular liquid crystals are cross-linked and no longer exhibit liquid crystallinity.

(Rod-like liquid crystalline molecules)
Examples of rod-like liquid crystalline molecules include azomethines, azoxys, cyanobiphenyls, cyanophenyl esters, benzoic acid esters, cyclohexanecarboxylic acid phenyl esters, cyanophenylcyclohexanes, cyano-substituted phenylpyrimidines, alkoxy-substituted phenylpyrimidines. , Phenyldioxanes, tolanes and alkenylcyclohexylbenzonitriles are preferably used.

  The rod-like liquid crystalline molecule includes a metal complex. In addition, a liquid crystal polymer containing a rod-like liquid crystalline molecule in a repeating unit can also be used as the rod-like liquid crystalline molecule. In other words, the rod-like liquid crystal molecule may be bonded to a (liquid crystal) polymer.

  For rod-like liquid crystalline molecules, see Chapter 4, Chapter 7 and Chapter 11 of the Chemistry of the Quarterly Chemistry Vol. 22 (1994) The Chemical Society of Japan, and the 142th Committee of the Japan Society for the Promotion of Science. Described in Chapter 3.

  The birefringence of the rod-like liquid crystal molecule is preferably in the range of 0.001 to 0.7.

  The rod-like liquid crystalline molecule preferably has a polymerizable group in order to fix its alignment state. The polymerizable group is preferably a radically polymerizable unsaturated group or a cationically polymerizable group. Specifically, for example, the polymerizable group described in paragraphs [0064] to [0086] of JP-A-2002-62427 is described. And polymerizable liquid crystal compounds.

(Discotic liquid crystalline molecules)
For discotic liquid crystal molecules, C.I. Destrade et al., Mol. Cryst. 71, 111 (1981), benzene derivatives described in C.I. Destrade et al., Mol. Cryst. 122, 141 (1985), Physics lett, A, 78, 82 (1990); Kohne et al., Angew. Chem. 96, page 70 (1984) and the cyclohexane derivatives described in J. Am. M.M. Lehn et al. Chem. Commun. , 1794 (1985), J. Am. Zhang et al., J. Am. Chem. Soc. 116, 2655 (1994), azacrown type and phenylacetylene type macrocycles are included.

  As a discotic liquid crystalline molecule, a compound having liquid crystallinity having a structure in which a linear alkyl group, an alkoxy group, and a substituted benzoyloxy group are radially substituted as a side chain of the mother nucleus with respect to the mother nucleus at the center of the molecule Is also included. The molecule or the assembly of molecules is preferably a compound having rotational symmetry and imparting a certain orientation. In the optically anisotropic layer formed from the discotic liquid crystalline molecules, the compound finally contained in the optically anisotropic layer does not need to be a discotic liquid crystalline molecule. Also included are compounds having a group that reacts with heat or light and, as a result, polymerized or cross-linked by reaction with heat or light, resulting in a high molecular weight and loss of liquid crystallinity. Preferred examples of the discotic liquid crystalline molecules are described in JP-A-8-50206. The polymerization of discotic liquid crystalline molecules is described in JP-A-8-27284.

  In order to fix the discotic liquid crystalline molecules by polymerization, it is necessary to bond a polymerizable group as a substituent to the discotic core of the discotic liquid crystalline molecules. A compound in which the discotic core and the polymerizable group are bonded via a linking group is preferable, whereby the orientation state can be maintained even in the polymerization reaction. Examples thereof include compounds described in paragraph numbers [0151] to [0168] in JP-A 2000-155216.

  In the hybrid alignment, the angle between the major axis (disk surface) of the discotic liquid crystalline molecule and the surface of the polarizing film increases or decreases in the depth direction of the optically anisotropic layer and with increasing distance from the surface of the polarizing film. is doing. The angle preferably decreases with increasing distance. Further, the change in angle can be a continuous increase, a continuous decrease, an intermittent increase, an intermittent decrease, a change including a continuous increase and a continuous decrease, or an intermittent change including an increase and a decrease. The intermittent change includes a region where the inclination angle does not change in the middle of the thickness direction. Even if the angle includes a region where the angle does not change, the angle only needs to increase or decrease as a whole. Furthermore, it is preferable that the angle changes continuously.

  The average direction of the major axis of the discotic liquid crystalline molecules on the polarizing film side can be generally adjusted by selecting a discotic liquid crystalline molecule or an alignment film material, or by selecting a rubbing treatment method. In addition, the major axis (disk surface) direction of the surface-side (air-side) discotic liquid crystalline molecules is generally adjusted by selecting the type of additive used together with the discotic liquid crystalline molecules or discotic liquid crystalline molecules. be able to. Examples of the additive used together with the discotic liquid crystalline molecule include a plasticizer, a surfactant, a polymerizable monomer and a polymer. The degree of change in the orientation direction of the major axis can also be adjusted by selecting liquid crystalline molecules and additives as described above.

(Other composition of optically anisotropic layer)
Along with the liquid crystal molecules, a plasticizer, a surfactant, a polymerizable monomer, etc. can be used in combination to improve the uniformity of the coating film, the strength of the film, the orientation of the liquid crystal molecules, and the like. It is preferable that the compound has compatibility with the liquid crystal molecules and can change the tilt angle of the liquid crystal molecules or does not inhibit the alignment.

  Examples of the polymerizable monomer include radically polymerizable or cationically polymerizable compounds. Preferably, it is a polyfunctional radically polymerizable monomer and is preferably copolymerizable with the above-described polymerizable group-containing liquid crystal compound. Examples thereof include those described in paragraph numbers [0018] to [0020] in JP-A No. 2002-296423. The amount of the compound added is generally in the range of 1 to 50% by mass and preferably in the range of 5 to 30% by mass with respect to the discotic liquid crystalline molecules.

  Examples of the surfactant include conventionally known compounds, and fluorine compounds are particularly preferable. Specific examples include compounds described in paragraph numbers [0028] to [0056] in JP-A-2001-330725.

  The polymer used together with the discotic liquid crystalline molecule is preferably capable of changing the tilt angle of the discotic liquid crystalline molecule.

  A cellulose ester can be mentioned as an example of a polymer. Preferable examples of the cellulose ester include those described in paragraph [0178] of JP-A No. 2000-155216. The addition amount of the polymer is preferably in the range of 0.1 to 10% by mass, and in the range of 0.1 to 8% by mass with respect to the liquid crystal molecule so as not to inhibit the alignment of the liquid crystal molecules. It is more preferable.

  The discotic nematic liquid crystal phase-solid phase transition temperature of the discotic liquid crystalline molecules is preferably 70 to 300 ° C, more preferably 70 to 170 ° C.

(Formation of optically anisotropic layer)
The optically anisotropic layer can be formed by applying a coating liquid containing liquid crystalline molecules and, if necessary, a polymerization initiator described later and optional components on the alignment film.

  As a solvent used for preparing the coating solution, an organic solvent is preferably used. Examples of organic solvents include amides (eg N, N-dimethylformamide), sulfoxides (eg dimethyl sulfoxide), heterocyclic compounds (eg pyridine), hydrocarbons (eg benzene, hexane), alkyl halides (eg , Chloroform, dichloromethane, tetrachloroethane), esters (eg, methyl acetate, butyl acetate), ketones (eg, acetone, methyl ethyl ketone), ethers (eg, tetrahydrofuran, 1,2-dimethoxyethane). Alkyl halides and ketones are preferred. Two or more organic solvents may be used in combination.

The coating liquid can be applied by a known method (for example, a wire bar coating method, an extrusion coating method, a direct gravure coating method, a reverse gravure coating method, or a die coating method).
The thickness of the optically anisotropic layer is preferably 0.1 to 20 μm, more preferably 0.5 to 15 μm, and most preferably 1 to 10 μm.

(Fixing the alignment state of liquid crystalline molecules)
The aligned liquid crystal molecules can be fixed while maintaining the alignment state. The immobilization is preferably performed by a polymerization reaction. The polymerization reaction includes a thermal polymerization reaction using a thermal polymerization initiator and a photopolymerization reaction using a photopolymerization initiator. A photopolymerization reaction is preferred.

  Examples of the photopolymerization initiator include α-carbonyl compounds (described in US Pat. Nos. 2,367,661 and 2,367,670), acyloin ether (described in US Pat. No. 2,448,828), α-hydrocarbon substituted aromatic acyloin. Compound (described in US Pat. No. 2,722,512), polynuclear quinone compound (described in US Pat. Nos. 3,046,127 and 2,951,758), a combination of triarylimidazole dimer and p-aminophenyl ketone (US Pat. No. 3,549,367) Acridine and phenazine compounds (JP-A-60-105667, U.S. Pat. No. 4,239,850) and oxadiazole compounds (U.S. Pat. No. 4,212,970).

  The amount of the photopolymerization initiator used is preferably in the range of 0.01 to 20% by mass, more preferably in the range of 0.5 to 5% by mass, based on the solid content of the coating solution.

It is preferable to use ultraviolet rays for light irradiation for polymerization of liquid crystalline molecules. The irradiation energy is preferably in the range of ^{20mJ / cm 2 ~50J / cm 2} , more preferably in the range of 20~5000mJ / cm ^2, more preferably in the range of 100 to 800 mJ / cm ² . In order to accelerate the photopolymerization reaction, light irradiation may be performed under heating conditions.
A protective layer may be provided on the optically anisotropic layer.

  It is also preferable to combine this optical compensation film and a polarizing film. Specifically, the optically anisotropic layer is formed by applying the coating liquid for the optically anisotropic layer as described above to the surface of the polarizing film. As a result, without using a polymer film between the polarizing film and the optically anisotropic layer, a thin polarizing plate having a small stress (strain × cross-sectional area × elastic modulus) associated with the dimensional change of the polarizing film is produced. . When the polarizing plate according to the present invention is attached to a large liquid crystal display device, an image with high display quality can be displayed without causing problems such as light leakage.

  The tilt angle of the polarizing film and the optical compensation layer may be stretched so as to match the angle formed by the transmission axis of the two polarizing plates bonded to both sides of the liquid crystal cell constituting the LCD and the vertical or horizontal direction of the liquid crystal cell. preferable. A normal inclination angle is 45 °. Recently, however, devices that are not necessarily 45 ° have been developed in transmissive, reflective, and transflective LCDs, and it is preferable that the stretching direction can be arbitrarily adjusted according to the design of the LCD.

(3) Application of antireflection layer (antireflection film)
The antireflection film generally includes a low refractive index layer which is also an antifouling layer, and at least one layer having a higher refractive index than that of the low refractive index layer (that is, a high refractive index layer and a medium refractive index layer). It has the structure provided above.

  Colloidal metal by multilayer deposition of transparent thin films of inorganic compounds (metal oxides, etc.) with different refractive indexes by chemical vapor deposition (CVD) method, physical vapor deposition (PVD) method, sol-gel method of metal compounds such as metal alkoxides Examples include a method of forming a thin film by post-processing (ultraviolet irradiation: JP-A-9-157855, plasma processing: JP-A-2002-327310) after forming an oxide particle film.

  On the other hand, various antireflection films formed by laminating thin films in which inorganic particles are dispersed in a matrix have been proposed as antireflection films with high productivity.

  The antireflection film which consists of an antireflection film which gave the anti-glare property which the surface of the uppermost layer has the shape of a fine unevenness to the antireflection film by application | coating as mentioned above is also mentioned.

  The cellulose acylate film of the present invention can be applied to any of the above methods, but a coating method (coating type) is particularly preferable.

(Layer structure of coating type antireflection film)
An antireflection film having a layer structure of at least a medium refractive index layer, a high refractive index layer, and a low refractive index layer (outermost layer) on the substrate is designed to have a refractive index satisfying the following relationship.

  Refractive index of high refractive index layer> refractive index of medium refractive index layer> refractive index of transparent support> refractive index of low refractive index layer Also, a hard coat layer is provided between the transparent support and the intermediate refractive index layer. Also good. Furthermore, it may consist of a medium refractive index hard coat layer, a high refractive index layer and a low refractive index layer.

Examples thereof include JP-A-8-122504, JP-A-8-110401, JP-A-10-300902, JP-A-2002-243906, JP-A-2000-11706, and the like.
Other functions may be imparted to each layer, for example, an antifouling low refractive index layer or an antistatic high refractive index layer (for example, JP-A-10-206603, JP-A-2002). -243906 publication etc.) etc. are mentioned.

  The haze of the antireflection film is preferably 5% or less, more preferably 3% or less. The strength of the film is preferably H or higher, more preferably 2H or higher, and most preferably 3H or higher in a pencil hardness test according to JIS K5400.

(High refractive index layer and medium refractive index layer)
The layer having a high refractive index of the antireflection film is composed of a curable film containing at least an inorganic compound ultrafine particle having a high refractive index having an average particle size of 100 nm or less and a matrix binder.

  Examples of the high refractive index inorganic compound fine particles include inorganic compounds having a refractive index of 1.65 or more, preferably those having a refractive index of 1.9 or more. Examples thereof include oxides such as Ti, Zn, Sb, Sn, Zr, Ce, Ta, La, and In, and composite oxides containing these metal atoms.

  In order to obtain such ultrafine particles, the surface of the particles is treated with a surface treatment agent (for example, as described in JP-A Nos. 11-295503, 11-153703, and 2000-9908). Silane coupling agent, etc .: Anionic compounds or organometallic coupling agents described in JP 2001-310432 A, etc., and a core-shell structure with high refractive index particles as a core (JP 2001-166104 A) Etc.) and specific dispersants (for example, JP-A-11-153703, US Pat. No. 6,210,858B1, JP-A-2002-27776069, etc.) and the like.

  Examples of the material forming the matrix include conventionally known thermoplastic resins and curable resin films.

  Furthermore, it is selected from a polyfunctional compound-containing composition containing at least two radically polymerizable and / or cationically polymerizable groups, an organometallic compound containing a hydrolyzable group, and a partial condensate composition thereof. At least one composition is preferred. Examples thereof include compounds described in JP-A Nos. 2000-47004, 2001-315242, 2001-31871, and 2001-296401.

  A curable film obtained from a colloidal metal oxide obtained from a hydrolyzed condensate of metal alkoxide and a metal alkoxide composition is also preferred. For example, it describes in Unexamined-Japanese-Patent No. 2001-293818.

  The refractive index of the high refractive index layer is generally 1.70 to 2.20. The thickness of the high refractive index layer is preferably 5 nm to 10 μm, and more preferably 10 nm to 1 μm.

  The refractive index of the middle refractive index layer is adjusted to be a value between the refractive index of the low refractive index layer and the refractive index of the high refractive index layer. The refractive index of the middle refractive index layer is preferably 1.50 to 1.70.

(Low refractive index layer)
The low refractive index layer is sequentially laminated on the high refractive index layer. The refractive index of the low refractive index layer is usually 1.20 to 1.55. Preferably it is 1.30-1.50.

  It is preferable to construct as the outermost layer having scratch resistance and antifouling property. As means for greatly improving the scratch resistance, imparting slipperiness to the surface is effective, and conventionally known means for thin film layers including introduction of silicone, introduction of fluorine, and the like can be applied.

  The refractive index of the fluorine-containing compound is preferably 1.35 to 1.50. More preferably, it is 1.36-1.47. The fluorine-containing compound is preferably a compound containing a crosslinkable or polymerizable functional group containing fluorine atoms in the range of 35 to 80% by mass.

  For example, paragraph numbers [0018] to [0026] of Japanese Patent Application Laid-Open No. 9-222503, paragraph numbers [0019] to [0030] of Japanese Patent Application Laid-Open No. 11-38202, and paragraph numbers of Japanese Patent Application Laid-Open No. 2001-40284. [0027] to [0028], JP-A 2000-284102, and the like.

  The silicone compound is a compound having a polysiloxane structure, preferably containing a curable functional group or a polymerizable functional group in the polymer chain and having a crosslinked structure in the film. For example, reactive silicone (for example, Silaplane (manufactured by Chisso Corporation), silanol group-containing polysiloxane (Japanese Patent Laid-Open No. 11-258403, etc.) and the like can be mentioned.

  The crosslinking or polymerization reaction of the fluorine-containing and / or siloxane polymer having a crosslinking or polymerizable group is carried out at the same time or after the coating composition for forming the outermost layer containing a polymerization initiator, a sensitizer, etc. It is preferable to carry out by light irradiation or heating.

  Also preferred is a sol-gel cured film in which an organometallic compound such as a silane coupling agent and a specific fluorine-containing hydrocarbon group-containing silane coupling agent are cured by a condensation reaction in the presence of a catalyst.

  For example, a polyfluoroalkyl group-containing silane compound or a partially hydrolyzed condensate thereof (Japanese Patent Laid-Open Nos. 58-142958, 58-147483, 58-147484, Japanese Patent Laid-Open Nos. 9-157582, 11) -106704), silyl compounds containing a poly "perfluoroalkyl ether" group which is a fluorine-containing long chain group (Japanese Patent Application Laid-Open Nos. 2000-117902, 2001-48590, 2002) 53804), and the like.

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

  When the low refractive index layer is located below the outermost layer, the low refractive index layer may be formed by a vapor phase method (vacuum deposition method, sputtering method, ion plating method, plasma CVD method, etc.). The coating method is preferable because it can be manufactured at a low cost.

  The film thickness of the low refractive index layer is preferably 30 to 200 nm, more preferably 50 to 150 nm, and most preferably 60 to 120 nm.

(Hard coat layer)
The hard coat layer is provided on the surface of the transparent support in order to impart physical strength to the antireflection film. In particular, it is preferably provided between the transparent support and the high refractive index layer.

  The hard coat layer is preferably formed by a crosslinking reaction or a polymerization reaction of a light and / or heat curable compound. The curable functional group is preferably a photopolymerizable functional group, and the hydrolyzable functional group-containing organometallic compound is preferably an organic alkoxysilyl compound.

Specific examples of these compounds are the same as those exemplified for the high refractive index layer.
Specific examples of the constituent composition of the hard coat layer include those described in JP-A Nos. 2002-144913, 2000-9908, and WO 00/46617.

  The high refractive index layer can also serve as a hard coat layer. In such a case, it is preferable to form fine particles dispersed in the hard coat layer using the method described for the high refractive index layer.

  The hard coat layer can also serve as an antiglare layer (described later) provided with particles having an average particle size of 0.2 to 10 μm to provide an antiglare function (antiglare function).

  The film thickness of the hard coat layer can be appropriately designed depending on the application. The film thickness of the hard coat layer is preferably 0.2 to 10 μm, more preferably 0.5 to 7 μm.

The strength of the hard coat layer is preferably H or higher, more preferably 2H or higher, and most preferably 3H or higher in a pencil hardness test according to JIS K5400. Further, in the Taber test according to JIS K5400, the smaller the wear amount of the test piece before and after the test, the better.

(Forward scattering layer)
The forward scattering layer is provided in order to give a viewing angle improvement effect when the viewing angle is inclined in the vertical and horizontal directions when applied to a liquid crystal display device. By dispersing fine particles having different refractive indexes in the hard coat layer, it can also serve as a hard coat function.

  For example, Japanese Patent Application Laid-Open No. 11-38208 specifying a forward scattering coefficient, Japanese Patent Application Laid-Open No. 2000-199809 having a relative refractive index of a transparent resin and fine particles in a specific range, and Japanese Patent Application Laid-Open No. 2002 specifying a haze value of 40% or more. -107512 gazette etc. are mentioned.

(Other layers)
In addition to the above layers, a primer layer, an antistatic layer, an undercoat layer, a protective layer, and the like may be provided.

(Application method)
Each layer of the antireflection film is formed by dip coating, air knife coating, curtain coating, roller coating, wire bar coating, gravure coating, micro gravure method or extrusion coating method (US Pat. No. 2,681,294). According to the specification, it can be formed by coating.

(Anti-glare function)
The antireflection film may have an antiglare function that scatters external light. The antiglare function is obtained by forming irregularities on the surface of the antireflection film. When the antireflection film has an antiglare function, the haze of the antireflection film is preferably 3 to 30%, more preferably 5 to 20%, and most preferably 7 to 20%.

  As a method for forming irregularities on the surface of the antireflection film, any method can be applied as long as these surface shapes can be sufficiently maintained. For example, a method of forming irregularities on the film surface using fine particles in the low refractive index layer (for example, JP 2000-271878 A), a lower layer of the low refractive index layer (high refractive index layer, medium refractive index layer) Alternatively, a small amount (0.1 to 50% by mass) of relatively large particles (particle size 0.05 to 2 μm) is added to the hard coat layer to form a surface uneven film, and these shapes are maintained thereon. A method of providing a low refractive index layer (for example, JP 2000-281410 A, JP 2000-95893 A, JP 2001-100004 A, 2001-281407, etc.), an uppermost layer (antifouling layer) A method of physically transferring an uneven shape onto the surface after coating (for example, as an embossing method, JP-A-63-278839, JP-A-11-183710, JP-A-2000-275401) Wherein) and the like.

<Liquid crystal display device>
The cellulose acylate film of the present invention can be suitably used for a liquid crystal display device. In particular, the cellulose acylate film of the present invention is effective when used as an optical compensation sheet for liquid crystal display devices. When the film itself is used as an optical compensation sheet, the transmission axis of a polarizing element (described later) and the slow axis of an optical compensation sheet made of a cellulose acylate film are arranged so as to be substantially parallel or perpendicular. It is preferable. Such an arrangement of the polarizing element and the optical compensation sheet is described in JP-A-10-48420. The liquid crystal display device includes a liquid crystal cell having a liquid crystal supported between two electrode substrates, two polarizing elements disposed on both sides thereof, and at least one sheet between the liquid crystal cell and the polarizing element. An optical compensation sheet is arranged.
Below, the kind of liquid crystal display device which can apply the cellulose acylate film of this invention is demonstrated.

(TN mode liquid crystal display)
It is most frequently used as a color TFT liquid crystal display device and is described in many documents. The alignment state in the liquid crystal cell in the TN mode black display is an alignment state in which the rod-like liquid crystalline molecules rise at the center of the cell and the rod-like liquid crystalline molecules lie in the vicinity of the cell substrate.

(OCB mode liquid crystal display)
This is a bend alignment mode liquid crystal cell in which rod-like liquid crystal molecules are aligned in a substantially opposite direction (symmetrically) between the upper part and the lower part of the liquid crystal cell. Liquid crystal display devices using a bend alignment mode liquid crystal cell are disclosed in US Pat. Nos. 4,583,825 and 5,410,422. Since the rod-like liquid crystal molecules are symmetrically aligned at the upper and lower portions of the liquid crystal cell, the bend alignment mode liquid crystal cell has a self-optical compensation function. Therefore, this liquid crystal mode is also called an OCB (Optically Compensatory Bend) liquid crystal mode.

  Similarly to the TN mode, the liquid crystal cell in the OCB mode is in a black display, and the alignment state in the liquid crystal cell is such that the rod-like liquid crystalline molecules rise at the center of the cell and the rod-like liquid crystalline molecules lie near the cell substrate. .

(VA mode liquid crystal display device)
The feature is that the rod-like liquid crystalline molecules are oriented substantially vertically when no voltage is applied. In the VA mode liquid crystal cell, (1) the rod-like liquid crystalline molecules are oriented substantially vertically when no voltage is applied. In addition to a narrowly defined VA mode liquid crystal cell (described in JP-A-2-176625) that is aligned substantially horizontally when a voltage is applied, (2) the VA mode is multi-domained to expand the viewing angle ( Liquid crystal cell (in MVA mode) (SID97, Digest of tech. Papers 28 (1997) 845), (3) Rod-like liquid crystal molecules are substantially vertically aligned when no voltage is applied, and twisted A liquid crystal cell in a domain alignment mode (n-ASM mode) (described in the proceedings 58-59 (1998) of the Japanese Liquid Crystal Society) and (4) a SURVAVAL mode liquid crystal cell (LCD interface) Announced at National 98).

(Other liquid crystal display devices)
The ECB mode and STN mode liquid crystal display devices can be optically compensated in the same way as described above.

It should be noted that the present invention and the techniques disclosed in the following patent publications can be used in combination without departing from the spirit of the present invention.
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<< Measurement method and evaluation method >>
(1) Thickness unevenness It samples by 35 mm width over the full width of a film (TD sample). The central part in the width direction is sampled 2 mm long with a width of 35 mm (MD sample). Next, the 7 mm x 7 mm range of the TD sample and the MD sample was continuously measured with a surface shape / roughness measuring instrument (NewView 6000, manufactured by Zygo), and the maximum height (the height from the lowest valley bottom to the highest peak) ) And the mean square roughness (the square root of the value obtained by averaging the squares of deviations of the measurement curve from the mean line) was defined as thickness unevenness.

(2) Apparent activation energy E _{0 Using a} plate rheometer (for example, Physica, MCR301 type) at temperatures of 210, 220, 225, 230, 235, and 240 ° C., 5 minutes after setting the sample Then, the storage elastic modulus and the loss elastic modulus are measured, and the master curve at 220 ° C. is obtained using the time-temperature conversion rule. The apparent activation energy E ₀ was determined from the slope of the shift factor with respect to each temperature used in the determination of the master curve. The experimental conditions of the apparatus are as follows.
Plate: 25mmφ parallel plate
Gap: 1mm
Frequency: 0.1-500 (Hz)
As a measurement sample, a melt-formed film was used. If this is in the above range, the kneadability of the cellulose acylate in the melt extruder at the time of film formation becomes appropriate, and the effect of the present invention is examined. Can do.

(3) Longest relaxation time τ
In the same apparatus and experimental conditions used for measuring the apparent activation energy E ₀ above, a sample was set at 220 ° C., and after 5 minutes, the storage elastic modulus and the loss elastic modulus were measured, The longest relaxation time τ is obtained from the frequency.

(4) Hemicellulose amount Sugar analysis is performed by the alditol acetate method (Borchadt, LG; Piper, CV: Tappi, 53, 257-260 (1970)) to determine the hemicellulose amount.

(5) Acyl group substitution degree of cellulose acylate Measured by a method according to ASTM D-817-91 (cellulose acylate is completely hydrolyzed, and free carboxylic acid or a salt thereof is determined by GC or LC).

(6) Weight average degree of polymerization (DPw) and number average degree of polymerization (DPn)
Dissolve the resin in tetrahydrofuran (THF) to make a 0.5 wt% sample solution. This sample solution is measured using GPC under the following conditions to determine the weight average molecular weight (Mw) and the number average degree of polymerization (Mn). The calibration curve is prepared using polystyrene (TSK standard polystyrene: molecular weight 1050, 5970, 18100, 37900, 190000, 706000). A value obtained by dividing the weight average molecular weight (Mw) and the number average polymerization degree (Mn) by the molecular weight per segment obtained from the substitution degree determined by the above method is the weight average polymerization degree (DPw) and the number average polymerization degree ( DPn).
Column: TSK GEL Super HZ4000, TSK GEL Super HZ2000,
TSK GEL Super HZM-M, TSK Guard Column Super HZ-L
Column temperature: 40 ° C
Eluent: THF
Flow rate: 1 ml / min Detector: RI

(7) Residual sulfate radical amount and residual metal (Ca, Na, K) content The sulfate radical content is measured according to ASTM D-817-96. The amount of residual metal is quantified by analyzing by ion chromatography, atomic absorption spectrum analysis, ICP analysis, ICP-MS analysis or the like.

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

1. Formation of unstretched cellulose acylate film (1) Synthesis of cellulose acylate After spraying 0.1 parts by mass of acetic acid and 2.7 parts by mass of propionic acid to 10 parts by mass of cellulose (hardwood pulp), 1 hour at room temperature. saved. Separately, a mixture of 1.2 parts by mass of acetic anhydride, 61 parts by mass of propionic anhydride, and 0.7 parts by mass of sulfuric acid was prepared, cooled to -10 ° C, and then mixed in the reaction vessel with the pretreated cellulose. did. After 30 minutes, the external temperature was raised to 30 ° C. and reacted for 4 hours. 46 parts by mass of 25% aqueous acetic acid was added to the reaction vessel, the internal temperature was raised to 60 ° C., and the mixture was stirred for 2 hours. 6.2 parts by mass of a solution prepared by mixing equal parts of magnesium acetate tetrahydrate, acetic acid and water was added and stirred for 30 minutes. The reaction solution was subjected to pressure filtration sequentially with a sintered metal filter having a retention particle size of 40 μm, 10 μm, and 5 μm to remove foreign matters. The reaction solution after filtration was mixed with 75% aqueous acetic acid to precipitate cellulose acetate propionate, and then washed with warm water at 70 ° C. until the pH of the washing solution reached 6-7. Furthermore, after performing the process stirred for 0.5 hour in 0.001% calcium hydroxide aqueous solution, it filtered. The obtained cellulose acetate propionate was dried at 70 ° C. ^From the measurement of ¹ H-NMR, the obtained cellulose acetate propionate has an acetyl substitution degree of 0.15, a propionyl substitution degree of 2.60, a total substitution degree of 2.75, a number average degree of polymerization (DPn) of 118, and a mass average. The degree of polymerization (DPw) was 380, the residual sulfuric acid content was 100 ppm, the magnesium content was 20 ppm, the calcium content was 50 ppm, the sodium content was 1 ppm, the potassium content was 1 ppm, and the iron content was 2 ppm. As a result of observing the film cast from the dichloromethane solution of this sample with a polarizing microscope, almost no foreign matter was observed when the polarizers were made orthogonal or parallel. This cellulose acetate propionate was used as a raw material for producing the cellulose acylate film of Example 39 shown in Table 1.
Further, by changing the amount of acetic anhydride and propionic anhydride charged, the degree of acetyl substitution was 0.40, the degree of propionyl substitution was 2.45, the number average degree of polymerization (DPn) 136, and the mass average degree of polymerization (DPw) 380. Cellulose acetate propionate was obtained. The residual sulfuric acid content was 60 ppm, the magnesium content was 25 ppm, the calcium content was 54 ppm, the sodium content was 2 ppm, the potassium content was 2 ppm, and the iron content was 1 ppm. As a result of observing the film cast from the dichloromethane solution of this sample with a polarizing microscope, almost no foreign matter was observed when the polarizers were made orthogonal or parallel. This cellulose acetate propionate was used as a raw material for producing the cellulose acylate film of Example 1 shown in Table 1.

In addition, an acylating agent for cellulose (from acetic acid, acetic anhydride, propionic acid, propionic acid anhydride, butyric acid, butyric acid anhydride, valeric acid, valeric acid anhydride to achieve each acyl substitution degree described in Table 1) Acylation was carried out while mixing the sulfuric acid as the catalyst and keeping the reaction temperature at 40 ° C. or lower. After the cellulose as a raw material disappeared and acylation was completed, heating was further continued at 40 ° C. or lower to adjust to a desired degree of polymerization. The remaining acid anhydride was hydrolyzed by adding an acetic acid aqueous solution, and then heated at 60 ° C. or lower to perform partial hydrolysis, thereby adjusting the desired total substitution degree (X + Y). The remaining sulfuric acid was neutralized with an excess amount of magnesium acetate. Reprecipitation from an aqueous acetic acid solution, and further repeating washing with water, the types of acyl groups, substitution degree, polymerization degree, residual carboxylic acid in Examples 2 to 38 and Comparative Examples 1 to 5 described in Table 1 Different amounts of cellulose acylate were obtained. To each cellulose acylate, 0.3% by mass of heat stabilizer (Sumitomo Chemical, Sumilizer GP), 0.05% by mass of silicon dioxide particles (Aerosil R972V), absorbent (Asahi Denka Kogyo Co., Ltd., ADK STAB) LA-31) 1% by mass was added and stirred well. Further, Adeka Scab AO-60 and PEP-36G manufactured by Asahi Denka Kogyo Co., Ltd. were mixed as a heat stabilizer in an amount of 0.15% by mass. In addition, cellulose acylate was also purified.
In addition, cellulose acylate esterified with benzoic acid and acetic acid was synthesized as cellulose acylate having a substituted or unsubstituted aromatic acyl group bonded thereto in accordance with Example 1 of JP-A No. 2002-3201. However, 2.0-substituted and 2.45-substituted cellulose acetate was used as the raw material cellulose acylate. As a result, an aromatic acyl group-substituted cellulose acylate having an acetic acid substitution degree (acetyl substitution degree) of 2.0, a benzoic acid substitution degree (aromatic acyl group substitution degree) of 1.0, and an acetic acid substitution degree of 2.45. An aromatic acyl group-substituted cellulose acylate having a benzoic acid substitution degree of 0.55 was obtained. These cellulose acylates were used in Examples 40 and 41 described in Table 1, respectively.

(2) Melt film formation The cellulose acylate was formed into a cylindrical pellet having a diameter of 3 mm and a length of 5 mm, and then dried by a vacuum dryer at 110 ° C. to obtain raw materials having different water contents as shown in Table 1. It was. This was put into a hopper adjusted to Tg-10 ° C., and under a nitrogen stream, a full flight screw with a compression ratio of 4 at a melting temperature (die temperature) and an oxygen concentration shown in Table 1 was used. ) / D (screw diameter) = 30. Furthermore, after the breaker plate type filtration was performed at the outlet of the extruder, it was passed through a gear pump and passed through a 4 μm stainless steel leaf type disk filter type filtration device.
Next, it was extruded through a T-die, and a film was formed at the linear pressure shown in Table 1 using the touch roll described in Example 1 of JP-A-11-235747. Then, it peeled off and wound up from the casting roll, and obtained the film of 40 micrometers-300 micrometers. In addition, after trimming both ends (each 3% of the total width) of the film just before winding, the film was wound after applying thickness processing (knurling) with a width of 10 mm and a height of 50 μm at both ends. In each level, the width was 1.5 m, and 3000 m was wound at 30 m / min.
The apparent activation energy, longest relaxation time, hemicellulose amount, weight average degree of polymerization, number average degree of polymerization, residual sulfuric acid amount, residual metal amount, thickness unevenness of each unstretched cellulose acylate film thus obtained are as described above. Measured by the method. In Table 1, DPw represents the weight average polymerization degree, DPn represents the number average polymerization degree, thickness PV represents the maximum height, and thickness RMS represents the mean square roughness.

2. Production of Stretched Cellulose Acylate Film The unstretched cellulose acylate film of the present invention produced above was stretched at (Tg + 10) ° C. at a rate of 300% / min so as to achieve the magnification described in Table 2. Tg is the glass transition temperature of the film, which is measured at 10 ° C./min using differential scanning calorimetry (DSC) and refers to the temperature at which the baseline starts to deviate from the low temperature side.
Re and Rth of the stretched film were measured at 25 ° C. and a relative humidity of 60% using an automatic birefringence meter (KOBRA-21ADH: manufactured by Oji Scientific Instruments), and the results are shown in Table 2. Table 2 shows the results of stretching the unstretched cellulose acylate film of Example 1. Similar results were obtained when the unstretched cellulose acylate films of other Examples were used.
(8) Production / Evaluation of Stretched Film The unstretched sheet of the present invention 1 and the unstretched sheet of the present invention 41 in Table 1 were stretched at the following magnification at 3000% / min at a glass transition temperature (Tg + 10) ° C. of each film ( A film having the following Re and Rth was obtained. The draw ratio here is defined by the following formula.
Stretch ratio (%) = 100 × {(Length after stretching) − (Length before stretching)} / (Length before stretching)

In the above table, the Re and Rth fluctuations (variations) and the orientation angle in the width direction and the longitudinal direction were measured by the following methods.
(1) MD direction (longitudinal direction) sampling was cut into a size of 100 points and 1 cm square at intervals of 0.5 m in the longitudinal direction. The sampling in the TD direction (width direction) was cut out at equal intervals of 50 points in the size of 1 cm square over the entire width of film formation.
(2) Re and Rth were measured according to the above methods. The orientation angle can be determined by setting and measuring the MD side of the sample film parallel to the measuring instrument insertion direction of the sample holder when performing the above measurement.
(3) For Re and Rth fluctuations, the difference between each maximum value and minimum value at 100 points in the MD direction and 50 points in the TD direction was divided by each average value, and expressed as a percentage, was designated as Re and Rth fluctuations. Regarding the orientation angle, the difference between the maximum value and the minimum value of the absolute value of each point was shown.

Moreover, the thermal dimensional change rate of Table 2 was measured with the following method.
(1) The sample is cut into 5 cm × 25 cm in the MD and TD directions, and holes with an interval of 20 cm are formed.
(2) After adjusting the humidity at 25 ° C. and 60% relative humidity for 2 hours, the distance between the two holes is measured using a pin gauge in this environment (this is defined as L ¹ ).
(3) Place the sample in an 80 ° C. air constant temperature bath for 5 hours.
(4) Take this out and adjust the humidity at 25 ° C. and 60% relative humidity for 3 hours, and then measure the distance between the two holes using a pin gauge in this environment (this is L ² ).
(5) 100 × (L ¹ −L ² ) / L ¹ is defined as a dimensional change rate (%).
Table 2 shows the results of stretching the unstretched sheet of the present invention 1 and the unstretched sheet of the present invention 41, but also when other unstretched cellulose acylate films of the present invention were used. Similar results were obtained.

3. Preparation of Polarizing Plate (1) Saponification of Cellulose Acylate Film The following immersion saponification was performed on an unstretched cellulose acylate film and a stretched cellulose acylate film. A sample subjected to coating saponification instead of immersion saponification was also prepared. When saponified by any method, similar results were obtained in the subsequent production and effect confirmation tests.
(Immersion saponification)
A 1.5 mol / L NaOH aqueous solution adjusted to 60 ° C. was prepared as a saponification solution, and a cellulose acylate film was immersed in the solution for 2 minutes. Then, after being immersed in 0.05 mol / L sulfuric acid aqueous solution for 30 seconds, it was passed through a water washing bath.
(Coating saponification)
20 parts by mass of water was added to 80 parts by mass of isopropanol, and KOH was dissolved in this at 1.5 mol / L and the temperature was adjusted to 60 ° C. to obtain a saponification solution. This saponification solution was applied onto a cellulose acylate film at 60 ° C. at 10 g / m ² and saponified for 1 minute. Thereafter, a 50 ° C. hot water spray was sprayed at 10 L / m ² · min for 1 minute for cleaning.

(2) Preparation of Polarizing Film According to Example 1 of Japanese Patent Application Laid-Open No. 2001-141926, a peripheral speed difference was given between two pairs of nip rolls, and a polarizing film having a thickness of 20 μm was prepared by stretching in the longitudinal direction.

(3) Bonding The polarizing film obtained in this way and the saponified unstretched or stretched cellulose acylate film were bonded with a 3% aqueous solution of polyvinyl alcohol (manufactured by Kuraray Co., Ltd., PVA-117H) as an adhesive. The polarizing axis and the cellulose acylate film were laminated so that the longitudinal direction was 45 degrees. The polarizing plate thus prepared is attached to the 20-inch VA liquid crystal display device described in FIGS. 2 to 9 of Japanese Patent Laid-Open No. 2000-154261, visually observed from an oblique angle of 32 degrees where the projected parallel streaks are most visible, and displayed. The degree of occurrence of unevenness was evaluated in five stages from 1 (good) to 5 (bad). The results are shown in Table 1. A practically acceptable level is 1 to 3.

4). Creation of optical compensation film (unstretched film)
When each unstretched cellulose acylate film of the example was used as the first transparent support of Example 1 of JP-A-11-316378, a good optical compensation film could be produced.

(Stretched cellulose acylate film)
When the stretched cellulose acylate film of Example was used instead of the cellulose acetate film coated with the liquid crystal layer of Example 1 of JP-A-11-316378, a good optical compensation film could be produced.
Moreover, when the stretched cellulose acylate film of Example was used instead of the cellulose acetate film coated with the liquid crystal layer of Example 1 of JP-A-7-333433, a good optical compensation filter film could be produced.
On the other hand, when a film outside the range of the present invention was used, the optical properties of the obtained optical compensation film were deteriorated. In particular, the sample No. in the example of JP 2000-352620 A is disclosed. What was implemented according to 3-1, especially the fall of the optical characteristic was remarkable.

5. Preparation of anti-reflection film According to Example 47, published technical bulletin (public technical number 2001-1745, published on March 15, 2001, Society of Invention) Example 47, each stretched cellulose acylate film and each unstretched cellulose acylate of Examples When an antireflection film (low reflection film) was prepared using the film, good optical performance was obtained.

6). Preparation of Liquid Crystal Display Element The polarizing plate of the above example was prepared by using the liquid crystal display device described in Example 1 of JP-A-10-48420 and the discotic liquid crystal molecule described in Example 1 of JP-A-9-26572. Including an optically anisotropic layer, an alignment film coated with polyvinyl alcohol, a 20-inch VA liquid crystal display device described in FIGS. 2 to 9 of JP-A-2000-154261, and FIGS. 10 to 10 of JP-A-2000-154261. 15 in the 20-inch OCB type liquid crystal display device. Furthermore, when the antireflection film of an Example was stuck on the outermost layer of these liquid crystal display devices and visual evaluation was performed, favorable visual recognition performance was obtained.

As is apparent from Table 1, the cellulose acylate film that satisfies the conditions of the present invention has small thickness unevenness, and the liquid crystal display device manufactured using the film has suppressed display unevenness. On the other hand, the cellulose acylate film that does not satisfy the conditions of the present invention has a large thickness unevenness, resulting in an unacceptable display unevenness when used in a liquid crystal display device. In particular, the sample No. of Example of Japanese Patent Laid-Open No. 2000-352620 (Patent Document 1). 5 and no. The films of Comparative Examples 6 and 7 prepared according to No. 6 had particularly large thickness unevenness, and the display unevenness of the liquid crystal display device using these films was considerably large.
In addition, in order to further reduce the thickness unevenness and further reduce the display unevenness when used in a liquid crystal display device, the amount of metal in the production of cellulose acylate film, the amount of residual sulfate radical, the molar content ratio thereof, etc. It has been confirmed that it is effective to control within the preferable range of the present invention. Furthermore, it was confirmed that it is preferable to form a film using a touch roll.

  ADVANTAGE OF THE INVENTION According to this invention, the cellulose acylate film with small thickness nonuniformity can be provided by the environmentally friendly melt film-forming method. In addition, according to the present invention, it is possible to provide a polarizing plate, an optical compensation film, an antireflection film, and a liquid crystal display device in which display unevenness is suppressed. Therefore, the present invention has very high industrial applicability.

It is the schematic of the example of an apparatus for implementing the melt film forming of this invention. The schematic block diagram of the film manufacturing apparatus which manufactures the thermoplastic film in the case of performing long span stretching is shown. FIG. 3 is a perspective explanatory view of a longitudinally extending portion in FIG. 2. The schematic block diagram of the film manufacturing apparatus which manufactures the thermoplastic film in the case of performing short span stretching is shown. The perspective explanatory view of the longitudinal extension part of Drawing 4 is shown. It is explanatory drawing of the bowing generate | occur | produced with the manufacturing method which does not heat-set. It is explanatory drawing which shows suppression of generation | occurrence | production of the bowing by heat setting.

Explanation of symbols

101 Extruder 102 Gear Pump 103 Filtration Unit (Filter)
DESCRIPTION OF SYMBOLS 104 Die 105 Touch roll 106 Cast drum 107 Cellulose acylate 108 Longitudinal stretch part 109 Lateral stretch part 110 Winding part 10, 10a Film production apparatus 12 Dryer 14 Extruder 16 Gear pump 18 Filter 20 Die 22 Cooling part 24 Touch roll 26 Roll 28 Cast drum 30, 30a Longitudinal stretched portion 32 Inlet side nip roll 33 Preheated roll 34 Outlet side nip roller 35 Preheated roll 36 Preheated portion 37 Nip roll 39 Nip roll 42 Lateral stretched portion 44 Heat fixing portion 46 Winding portion Fa Unstretched film Fb Longitudinal stretched film F Thermoplastic film Lb curve

Claims (23)

Cellulose having an apparent activation energy E ₀ (5) of 160 to 240 (kJ / mol) measured at 5 minutes after melting at 220 ° C. and a longest relaxation time τ (5) of 4 to 50 (msec) A cellulose acylate composition comprising an acylate. Apparent activation energy E ₀ (5) and longest relaxation time τ (5) measured after 5 minutes of melting the cellulose acylate at 220 ° C., and 30 times by melting the cellulose acylate at 220 ° C. The cellulose acylate composition according to claim 1, wherein the apparent activation energy E ₀ (30) and the longest relaxation time τ (30) measured after minutes satisfy the following formulas.
| E ₀ (30) −E ₀ (5) | ≦ 30 (kJ / mol)
| Τ (30) −τ (5) | ≦ 5 (msec)   The content of hemicellulose in the cellulose constituting the cellulose acylate is 0.1 to 3% by mass, and the weight average degree of polymerization (DPw) of the cellulose acylate is 300 to 550. The cellulose acylate composition according to 1 or 2.   The cellulose acylate according to any one of claims 1 to 3, wherein the cellulose acylate has a weight average degree of polymerization / number average degree of polymerization (DPw / DPn) of 1.7 to 5.0. Composition. The cellulose acylate composition according to any one of claims 1 to 4, wherein the cellulose acylate satisfies the following formulas (S-1) to (S-3).
Formula (S-1): 2.60 ≦ X + Y <3.00
Formula (S-2): 0 ≦ X ≦ 1.80
Formula (S-3): 1.00 ≦ Y <3.00
(In the formula, X represents the substitution degree of the acetyl group, and Y represents the total substitution degree of the propionyl group, butyryl group, pentanoyl group, and hexanoyl group.) The cellulose acylate composition according to any one of claims 1 to 5, wherein the cellulose acylate satisfies the following formulas (T-1) and (T-2).
Formula (T-1): 2.5 <= X + Z <3.0
Formula (T-2): 0.1 ≦ Z <2
(In the formula, X represents the degree of substitution of the acetyl group, and Z represents a substituted or unsubstituted aromatic acyl group.)   The total content of Na, Ca, K, Mg is 300 ppm or less, the residual sulfate radical amount is 300 ppm or less, and the molar content ratio of (Na + Ca + K + Mg) / S is 0.7 to 2.0. The cellulose acylate composition according to any one of claims 1 to 6.   The thermal stabilizer having a molecular weight of 500 or more having at least one of a hydroxyphenyl group or a phosphite group in the same molecule is contained in an amount of 0.1 to 3.0% by mass. The cellulose acylate composition according to one item.   The cellulose acylate composition according to claim 1, wherein the cellulose acylate composition has a pellet shape.   A method for producing a cellulose acylate film, comprising the step of melting the cellulose acylate composition according to any one of claims 1 to 9 to form a film.   The cellulose acylate according to claim 10, wherein the cellulose acylate composition is melted at 200 ° C to 250 ° C in an atmosphere having an oxygen concentration of 0.1% to 19% to form a film. A method for producing a film.   The process for producing a cellulose acylate film according to claim 10 or 11, comprising a step of extruding the cellulose acylate composition onto a casting drum after melting and forming a film on the casting drum using a touch roll. Method.   The cellulose acylate film manufactured by the manufacturing method as described in any one of Claims 10-12. The apparent activation energy E ₀ (5) measured 5 minutes after melting at 220 ° C. is 160 to 240 (kJ / mol), and the longest relaxation time τ (5) is 4 to 50 (msec), And the amount of residual solvents is 0.01 mass% or less, The cellulose acylate film characterized by the above-mentioned.   A cellulose acylate film obtained by stretching the cellulose acylate film according to claim 13 or 14 in at least one direction.   The cellulose acylate film according to any one of claims 13 to 15 is stretched so that the aspect ratio L / W exceeds 2 and is 50 or less, or 0.01 to 0.3. Cellulose acylate film.   A cellulose acylate film obtained by preheating the cellulose acylate film according to any one of claims 13 to 16 at a temperature higher by 1 to 50 ° C than a stretching temperature before transverse stretching.   The cellulose acylate film according to any one of claims 13 to 17, wherein the cellulose acylate film is heat-treated at a temperature lower by 1 ° C to 50 ° C than the stretching temperature after transverse stretching.   The cellulose acylate film according to any one of claims 13 to 18 is subjected to longitudinal stretching and / or lateral stretching, and then at a temperature of Tg-50 ° C to Tg + 30 ° C, 0.1 kg / m to 20 kg / m. A cellulose acylate film characterized by being thermally relaxed while being conveyed with a tension of.   The polarizing plate produced using the cellulose acylate film as described in any one of Claims 13-19.   The optical compensation film produced using the cellulose acylate film as described in any one of Claims 13-19.   The antireflection film produced using the cellulose acylate film as described in any one of Claims 13-19.   At least one of the cellulose acylate film according to any one of claims 13 to 19, the polarizing plate according to claim 20, the optical compensation film according to claim 21, and the antireflection film according to claim 22. A liquid crystal display device manufactured using the same.

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