JP2010234706A - Cellulose ester film and production method for cellulose ester film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cellulose ester film and a production method for the cellulose ester film, which can improve contrast performance, inhibit blocking like mutual sticking of films while excels in mat effect and further improves productivity by inhibiting filter clogging in an extrusion processing. <P>SOLUTION: The cellulose ester film is made through melt casting method, wherein there are 50-500 pieces/g of gel fillers with a gel size of 0.5-30 μm and 0-2 pieces/10 g of gel fillers with a gel size of 50 μm or more respectively in terms of a size of gel filler, in the melt-mixture containing the cellulose ester. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a cellulose ester film and a method for producing a cellulose ester film.

Conventionally, silica-based fine particles are often used among inorganic fine particles as a matting agent used in an optical film using a cellulose resin (see Patent Documents 1, 2, and 3).
In recent years, competition for contrast is intensifying in liquid crystal displays, but one factor that improves contrast is the transmittance of the film. The matting agent is important for maintaining the winding shape of the film, but since the composition is different from that of the film, the difference in refractive index and the size of the particle cause scattering, lowering the transmittance and deteriorating the contrast.
Among inorganic fine particles, silica-based fine particles have a refractive index close to that of cellulose ester. However, since inorganic fine particles have a refractive index specific to a substance, the refractive index cannot be made any closer. For this reason, the improvement in contrast has been attempted by reducing the amount of silica fine particles added, but if the amount is reduced too much, the mat effect cannot be exhibited, so the effect of improving the contrast by reducing the amount added has been limited.
Therefore, it is known to use organic fine particles as a method for eliminating the difference in refractive index (see Patent Document 4).
On the other hand, a solution film forming method is known as a method for producing cellulose, but a film forming method called a melt casting method considering an environment in which no solvent is used has been proposed (see Patent Document 5).
Organic fine particles are easy to adjust in the direction that eliminates the difference in refractive index from cellulose ester, but the resin temperature in the melt extrusion process is as high as 200 ° C. or higher. The organic fine particles are limited to those having a crosslinked structure because they cannot be tolerated and dissolve.

JP-A-7-11055 JP 2001-2799 A JP 2001-114907 A JP 2007-254727 A JP 2000-352620 A

However, those having a cross-linked structure are often hardened by cross-linking, and are likely to clog when passing through a filter in the extrusion process, and the pressure becomes unstable. Slow crosslinking is difficult to control, and the amount of addition increases due to the distribution of the degree of crosslinking. Therefore, since it becomes impossible to supply a certain amount of resin, there arises a problem that the film thickness fluctuates and the product does not become a product.
Furthermore, the clogged filter needs to be replaced, but in order to replace the filter, production must be stopped, and production efficiency is reduced due to the stoppage of production. In addition, the crosslinked organic fine particles have poor compatibility with the cellulose ester, and lower the transmittance than the inorganic fine particles, thereby degrading the contrast.
In the recent high contrast competition era, a decrease in transmittance is a major obstacle, but it has a matte effect (effect of making fine unevenness on the film to make it slippery) and anti-blocking effect (effect of preventing sticking between films). Both are required.

  The present invention has been made in view of the above circumstances, can improve the contrast performance, has an excellent mat effect and can prevent blocking such as sticking between films, and further prevents clogging of the filter in the extrusion process. It is an object of the present invention to provide a cellulose ester film and a method for producing the cellulose ester film that can improve productivity.

According to one aspect of the present invention, a cellulose ester film formed by a melt casting method,
Cellulose characterized in that the cellulose ester film has 50 to 500 gel fillers having a size of 0.5 to 30 μm and 0 to 2/10 g gel fillers having a size of 50 μm or more. An ester film is provided.

According to another aspect of the present invention, the cellulose ester film has 50 to 500 gel fillers having a size of 0.5 to 30 μm / g, and 0 to 2 gel fillers having a size of 50 μm or more. A method for producing a cellulose ester film having 10 pieces per piece,
Drying the pellets containing cellulose ester at 70 to 95 ° C. for 4 to 6 hours;
And a step of forming a film of the dried pellets by a melt casting method.

  According to the present invention, the cellulose ester film has 50 to 500 gel fillers having a size of 0.5 to 30 μm and 0 to 2 gel fillers having a size of 50 μm or more. By setting it to / 10 g, the gel filler has the same composition as the cellulose ester film, so that the refractive index can be made substantially equal, and light scattering due to the difference in refractive index can be prevented. As a result, contrast performance can be improved. Moreover, slipperiness becomes favorable by the fine unevenness | corrugation of a gel filler, and sticking of films can be prevented. Furthermore, since the gel filler is softer than the organic fine particles, the filter can be prevented from being clogged in the extrusion process, the film thickness hardly changes, and the productivity can be improved.

It is the figure which showed an example of the manufacturing apparatus for manufacturing the cellulose-ester film of this invention.

Hereinafter, preferred embodiments of the present invention will be described.
The cellulose ester film according to the present invention is formed by a melt casting method, and the cellulose ester film has 50 to 500 gel fillers having a size of 0.5 to 30 μm and a size of 50 μm or more. The number of gel fillers is 0 to 2/10 g.
Here, the gel filler is derived from the cellulose ester as the material of the film and has almost the same composition as the cellulose ester film, but by forming a cross-linked structure, the gel state in the molten composition It represents what has become. However, the gel is only in the molten resin, and is solidified in the raw material pellets and the film after film formation.
The size and number of gel fillers are counted as follows. First, a sample film is dissolved in tetrahydrofuran to make a 5% by weight solution, and left for about 20 hours to dissolve a clean film part naturally. Since foreign substances are difficult to dissolve, the gel-like portions remain undissolved. The gel filler contained in the undissolved solution is counted for size and number using a Beckman Coulter Coulter Counter (Z Series, Multisizer 3). The size is the diameter when the projected area of each particle is converted into a circle of the same area. In addition, when particles as large as the gel are added, the foreign material (in the state where there is no heat history that the gel is generated in the extruder) before the film is made into a solution as described above. Count particles with a Coulter counter. Thereafter, the number of gel fillers is determined by subtracting the number of foreign substances (particles) counted in advance from the number of gel fillers and foreign substances (particles) in the film.

  As for the magnitude | size of the gel filler contained in the cellulose-ester film of this invention, 0.5 micrometer-30 micrometers are preferable. In particular, the number of 20 μm to 30 μm is preferably as close to zero as possible.

  The cellulose ester film according to the present invention contains cellulose ester (or modified cellulose ester), a plasticizer and other additives as main raw materials. Hereinafter, each material will be described.

［式中、ＡとＢは、炭素数１〜１２の２価の炭化水素基、又は、ヒドロキシル基で置換された炭素数１〜１２の２価の炭化水素基を表す。ただし、ＡとＢは、同じであっても異なっていてもよい。］
以下に、Ａの具体例を挙げる。
Ａ−１ −ＣＨ_２ＣＨ_２−
Ａ−２ −ＣＨ_２ＣＨ_２ＣＨ_２−
Ａ−３ −ＣＨ＝ＣＨ−

Ａ−６ −ＣＨ_２Ｃ（ＣＨ_３）_２−
以下Ｂの具体例を挙げる。
Ｂ−１ −ＣＨ_２ＣＨ_２−
Ｂ−２ −ＣＨ_２ＣＨ_２ＣＨ_２ＣＨ_２−

一般式（１）又は（２）で表される繰り返し単位を少なくとも一つ有するセルロースエステルは、未置換のヒドロキシル基（水酸基）を有するセルロース、又はアセチル基、プロピオニル基、ブチリル基、フタリル基等のアシル基によってすでに一部のヒドロキシル基（水酸基）が置換されているセルロースエステルの存在下で、多塩基酸又はその無水物と多価アルコールとのエステル化反応、又はＬ−ラクチド、Ｄ−ラクチドの開環重合、Ｌ−乳酸、Ｄ−乳酸の自己縮合を行わせることによって得ることができる。
エステル化反応に用いる多塩基酸無水物として、無水マレイン酸、無水フタル酸、無水フマル酸が挙げられるが特に限定されない。
エステル化反応に用いることができる多価アルコールとして、グリセリン、エチレングリコール、プロピレングリコールなどが挙げられるが特に限定されない。 <Modified cellulose ester>
The modified cellulose ester is a cellulose ester having a repeating unit represented by the following general formula (1) or (2). Hereinafter, the modified cellulose ester will be described.

[In formula, A and B represent a C1-C12 bivalent hydrocarbon group or a C1-C12 bivalent hydrocarbon group substituted by the hydroxyl group. However, A and B may be the same or different. ]
Specific examples of A will be given below.
A-1-CH ₂ CH _{2-
A-2 -CH 2 CH 2 CH} 2 -
A-3 -CH = CH-

A-6 —CH ₂ C (CH ₃ ) ₂ —
Specific examples of B are given below.
B-1 _{-CH 2} CH 2 -
B-2-CH ₂ CH ₂ CH ₂ CH _2-

The cellulose ester having at least one repeating unit represented by the general formula (1) or (2) is a cellulose having an unsubstituted hydroxyl group (hydroxyl group), or an acetyl group, a propionyl group, a butyryl group, a phthalyl group, etc. In the presence of a cellulose ester in which a part of hydroxyl groups (hydroxyl groups) has already been substituted by an acyl group, an esterification reaction between a polybasic acid or an anhydride thereof and a polyhydric alcohol, or L-lactide or D-lactide It can be obtained by ring-opening polymerization, self-condensation of L-lactic acid and D-lactic acid.
Examples of the polybasic acid anhydride used in the esterification reaction include, but are not limited to, maleic anhydride, phthalic anhydride, and fumaric anhydride.
Examples of the polyhydric alcohol that can be used in the esterification reaction include glycerin, ethylene glycol, and propylene glycol, but are not particularly limited.

  As the catalyst used for the esterification reaction, the reaction can be carried out without a catalyst, but a known Lewis acid catalyst or the like can be used. Examples of catalysts that can be used include metals such as tin, zinc, titanium, bismuth, zirconium, germanium, antimony, sodium, potassium, and aluminum, and derivatives thereof. Particularly, the derivatives include metal organic compounds, carbonates, oxides, halides. Is preferred. Specific examples include octyl tin, tin chloride, zinc chloride, titanium chloride, alkoxy titanium, germanium oxide, zirconium oxide, antimony trioxide, and alkyl aluminum. Moreover, an acid catalyst typified by p-toluenesulfonic acid can also be used as the catalyst. Moreover, in order to accelerate | stimulate the dehydration reaction of carboxylic acid and alcohol, you may add well-known compounds, such as carbodiimide and dimethylaminopyridine.

  Such a reaction may be a reaction in an organic solvent capable of dissolving cellulose ester and other compounds to be reacted, or a reaction using a batch kneader capable of heating and stirring while adding a shearing force. It may be by reaction using a uniaxial or biaxial extruder.

The repeating unit represented by the general formula (1) or (2) can be appropriately contained in the range of 0.5 to 190% by mass with respect to cellulose.
Although the substitution degree of this cellulose ester can be selected suitably, it is preferable that it is 2.2-3 from the point of thermoplasticity and heat workability.
In the cellulose ester having at least one repeating unit represented by the general formula (1) or (2), when the hydrogen atom of the hydroxyl group (hydroxyl group) portion of the cellulose is a fatty acid ester with an aliphatic acyl group, an aliphatic group The acyl group has 2 to 20 carbon atoms and specifically includes acetyl, propionyl, butyryl, isobutyryl, valeryl, pivaloyl, hexanoyl, octanoyl, lauroyl, stearoyl and the like.

The polymerization degree of the cellulose ester having at least one repeating unit represented by the general formula (1) or (2) is not particularly limited, and is, for example, a viscosity average polymerization degree of 70 or more (for example, 80 to 800). It can be selected from a range, and may be 100 to 500, preferably 110 to 400, and more preferably about 120 to 350.
The repeating unit represented by the general formula (1) or (2) is, for example, 80 to 10,000, preferably 100 to 5000, more preferably about 200 to 2000, particularly 300 to 1500, as the number average molecular weight of the portion. Usually, it may be less than 1000. In addition, the number average molecular weight of only the repeating unit which the said cellulose ester has is compared by the GPC (gel permeation chromatograph) data which converted the cellulose ester before esterification reaction, and the cellulose ester after reaction into polystyrene, or 1H-NMR. And asked.
An oligomer or polyester having the repeating unit represented by the general formula (1) or (2) as a side reaction when the repeating unit represented by the general formula (1) or (2) is introduced into cellulose or cellulose ester. However, since these compounds act as plasticizers, they need not be completely removed by purification. If content is 30 mass% or less with respect to a cellulose ester, there will be little change in the property of a cellulose ester. From the viewpoint of plasticity, it is preferably 0.5 to 20% by mass. These oligomers and polyesters have a number average molecular weight of 300 to 10,000, and preferably 500 to 8,000 from the viewpoint of plasticity.

  In addition, a graft copolymerized modified glucan derivative (modified cellulose derivative) described in JP-A-2008-197561 is also a cellulose or cellulose ester film having a repeating unit represented by the general formula (1) or (2) of the present invention. Can be used as

Moreover, it is preferable that the cellulose-ester film which has a repeating unit represented by General formula (1) or (2) has the following characteristic.
Transmittance: 80% or more Film thickness: 20-90 μm
0nm ≦ Ro ≦ 330nm
−100 nm ≦ Rt ≦ 340 nm
Ro = (nx−ny) × d
Rt = ((nx + ny) / 2−nz) × d
(Where nx is the refractive index in the slow axis direction in the plane of the cellulose ester film, ny is the refractive index in the direction perpendicular to the slow axis in the plane, nz is the refractive index in the thickness direction, and d is the refractive index in the thickness direction) (Represents the thickness (nm) of the cellulose ester film. The refractive index is measured at 590 nm.)
The refractive index can be obtained at a wavelength of 590 nm under an environment of 23 ° C. and 55% RH using, for example, KOBRA-21ADH (Oji Scientific Instruments). The content of the solvent is preferably 0.01% by mass or less. In addition, the cellulose ester film preferably has a length of 100 m to 6000 m and a width of 1.2 m or more, more preferably 1.4 to 4 m. By making the length and width of the base film within the above ranges, the handleability and productivity are excellent.

The film containing a cellulose ester having a repeating unit represented by the general formula (1) or (2) is preferably one having few bright spot foreign substances. The bright spot foreign matter preferably has a bright spot diameter of 0.01 mm or more and 200 pieces / cm ² or less, more preferably 100 pieces / cm ² or less, and preferably 50 pieces / cm ² or less. 30 / cm ² or less, preferably 10 / cm ² or less, and most preferably none.
Moreover, it is preferable that it is 200 pieces / cm < ² > or less also about a bright spot of 0.005-0.01 mm or less, Furthermore, it is preferable that it is 100 pieces / cm < ² > or less, and it is 50 pieces / cm < ² > or less. The number is preferably 30 pieces / cm ² or less, more preferably 10 pieces / cm ² or less, and most preferably none.

《Cellulose ester》
In the present invention, unlike the modified cellulose ester, a cellulose ester having an average acyl group substitution degree of 2.0 to 2.5 may be contained.
The cellulose ester according to the present invention is not particularly limited as long as it is a cellulose ester conventionally used in the field of optical films.
As the compound constituting the resin, for example, cellulose diacetate, cellulose acetate propionate, cellulose acetate butyrate, or cellulose acetate propionate butyrate can be used. Cellulose diacetate, cellulose acetate propionate, and the like can be used. Nate is preferred. Two or more types of cellulose esters may be used in combination.

The cellulose used as a raw material for the cellulose ester is not particularly limited, and examples thereof include cotton linter, wood pulp (conifer pulp, hardwood pulp), and kenaf. Moreover, the cellulose ester obtained from them can be mixed and used in arbitrary ratios, respectively.
Cellulose esters are prepared by using an organic acid such as acetic acid or an organic solvent such as methylene chloride when the acylating agent is an acid anhydride (acetic anhydride, propionic anhydride, or butyric anhydride). Synthesize using a protic catalyst. When the acylating agent is acid chloride (CH ₃ COCl, C ₂ H ₅ COCl, C ₃ H ₇ COCl), the reaction is carried out using a basic compound such as an amine as a catalyst. Specifically, it can be synthesized by the method described in JP-A-10-45804. The acyl group is reacted with the hydroxyl group of the cellulose molecule. Cellulose molecules are composed of many glucose units linked together, and the glucose unit has three hydroxyl groups. The number of acyl groups derived from these three hydroxyl groups is called the degree of substitution. For example, cellulose triacetate has an acetyl group bonded to all three hydroxyl groups of the glucose unit.

The cellulose ester used in the present invention has an average acyl group substitution degree of 2.0 to 2.5 and an acyl group substitution degree of 3 to 7 carbon atoms of 0 to 0, particularly from the viewpoint of improving brittleness and transparency. Preferably it is 1.2. As the acyl group having 3 to 7 carbon atoms of the cellulose ester of the present invention, a propionyl group is particularly preferably used.
When the average acyl group substitution degree of the cellulose ester is less than 2.0, that is, when the residual degree of the hydroxyl groups (hydroxyl groups) at the 2, 3, and 6 positions of the cellulose ester molecule is more than 1.0, the modification When it is used as an optical film because it is not sufficiently compatible with cellulose ester, haze becomes a problem. Moreover, even if the average substitution degree of the acyl group is 2.0 or more, if the substitution degree of the acyl group having 3 to 7 carbon atoms exceeds 1.2, still sufficient compatibility cannot be obtained, Brittleness will decrease. For example, even when the average substitution degree of the acyl group is 2.0 or more, the substitution degree of the acyl group having 2 carbon atoms, that is, the acetyl group is low, and the substitution degree of the acyl group having 3 to 7 carbon atoms is 1. When it exceeds 2, compatibility falls and haze rises.
The acyl substitution degree of the cellulose ester of the present invention is 1 to 2, although the average substitution degree is 2.0 to 2.5 and the substitution degree of the acyl group having 3 to 7 carbon atoms is 0 to 1.2. When the film thickness is 2 or more, the elastic modulus of the film decreases, and when a polarizing plate produced using this film is exposed to high-humidity heat conditions, shrinkage increases.

In the present invention, the acyl group may be an aliphatic acyl group or an aromatic acyl group. In the case of an aliphatic acyl group, it may be linear or branched and may further have a substituent. The number of carbon atoms of the acyl group in the present invention includes an acyl group substituent.
When the cellulose ester has an aromatic acyl group as a substituent, the number of substituents X substituted on the aromatic ring is preferably 0 to 5. Also in this case, it is necessary to pay attention so that the substitution degree of the acyl group having 3 to 7 carbon atoms including the substituent is 0 to 1.2.
The cellulose ester in the present invention is preferably at least one selected from cellulose acetate propionate, cellulose acetate butyrate, cellulose acetate benzoate, cellulose propionate, and cellulose butyrate. Those having 4 acyl groups as substituents are preferred.
Among these, particularly preferred cellulose esters are cellulose acetate propionate and cellulose propionate.
In addition, the substitution degree of an acetyl group and the substitution degree of other acyl groups are obtained by a method prescribed in ASTM-D817-96.

  The weight average molecular weight (Mw) of the cellulose ester in the present invention is 75,000 or more from the viewpoint of improving brittleness, preferably in the range of 75,000 to 300,000, more preferably in the range of 100,000 to 24,000, and 160000. Those of ˜24,000 are particularly preferred. In the present invention, two or more kinds of cellulose resins can be mixed and used.

<Particulate matter>
The fine particles may be either inorganic compounds or organic compounds as long as they have heat resistance during melting. For example, talc, mica, zeolite, diatomaceous earth, calcined siliceous earth, kaolin, sericite, bentonite, smectite, clay, silica, Quartz powder, glass beads, glass powder, glass flake, milled fiber, wollastonite, boron nitride, boron carbide, titanium boride, magnesium carbonate, heavy calcium carbonate, light calcium carbonate, calcium silicate, aluminum silicate, magnesium silicate, Magnesium aluminosilicate, alumina, silica, zinc oxide, titanium dioxide, iron oxide, magnesium oxide, zirconium oxide, aluminum hydroxide, calcium hydroxide, magnesium hydroxide, calcium sulfate, barium sulfate, silicon carbide, aluminum carbide Titanium carbide, aluminum nitride, silicon nitride, titanium nitride, and white carbon.
Among these, silicon dioxide, which has a refractive index close to that of cellulose ester and is excellent in transparency (haze), is particularly preferably used. Specific examples of silicon dioxide include Aerosil 200V, Aerosil R972V, Aerosil R972, R974, R812, 200, 300, R202, OX50, TT600 (above Nippon Aerosil Co., Ltd.), Sea Hoster KEP-10, Sea Hoster KEP-30 , Seahoster KEP-50, Seahoster KE-P100 (made by Nippon Shokubai Co., Ltd.), Silo Hovic 100 (made by Fuji Silysia), Nip Seal E220A (made by Nippon Silica Industry), Admafine SO (made by Admatechs), etc. A commercially available product having a name can be preferably used.
The shape of the particles can be used without particular limitation, such as indefinite shape, needle shape, flat shape, spherical shape, etc. However, the use of spherical particles is particularly preferable because the transparency of the resulting film can be improved. When the particle size is close to the wavelength of visible light, light is scattered and the transparency is deteriorated. Therefore, the particle size is preferably smaller than the wavelength of visible light, and more preferably ½ or less of the wavelength of visible light. .
The size of the particles is preferably in the range of 0.05 μm to 3.0 μm.
These particulate substances can be used alone or in combination of two or more. By using particles having different particle sizes and shapes (for example, acicular and spherical), both transparency and slipperiness can be made highly compatible. These particulate substances can be contained in an amount of 0.01 to 5% by mass of the entire optical film.
The particle size means the size of the aggregate when the particle is an aggregate of primary particles. Moreover, when a particle is not spherical, it means the diameter of a circle corresponding to the projected area.

《Plasticizer》
Adding a compound known as a plasticizer to the cellulose ester film of the present invention is not only to obtain the effects of the present invention, but also to improve mechanical properties, impart flexibility, impart water resistance, reduce moisture permeability, etc. This is preferable from the viewpoint of film modification. Further, in the melt casting method carried out in the present invention, the plasticity is higher than that of cellulose ester for the purpose of lowering the melting temperature of the film constituting material by adding a plasticizer, or at the same heating temperature, rather than the glass transition temperature of the cellulose ester used alone. It is preferable at the point which can reduce the viscosity of the film constituent material containing an agent.

Here, in the present invention, the melting temperature of the film constituent material means a temperature at which the material is heated in a state where the material is heated and fluidity is developed.
If the cellulose ester alone is lower than the glass transition temperature, the fluidity for forming a film is not exhibited. However, the cellulose ester has a lower elastic modulus or viscosity due to heat absorption above the glass transition temperature and exhibits fluidity. In order to melt the film constituent material, the plasticizer to be added preferably has a melting point or glass transition temperature lower than the glass transition temperature of the cellulose ester in order to satisfy the above object.

  As the plasticizer, for example, phosphate ester derivatives and carboxylic acid ester derivatives are preferably used. Further, a polymer obtained by polymerizing an ethylenically unsaturated monomer having a weight average molecular weight of 500 to 10,000 described in JP-A-2003-12859, an acrylic polymer, an acrylic polymer having an aromatic ring in the side chain, or a cyclohexyl group An acrylic polymer or the like having in the side chain is also preferably used.

  Examples of phosphoric acid ester derivatives include phosphoric acid ester plasticizers, ethylene glycol ester plasticizers, glycerin ester plasticizers, diglycerin ester plasticizers (fatty acid esters), polyhydric alcohol esters. Examples thereof include plasticizers, dicarboxylic acid ester plasticizers, polycarboxylic acid ester plasticizers, and polymer plasticizers. Of these, polyhydric alcohol ester plasticizers, dicarboxylic acid ester plasticizers and polycarboxylic acid ester plasticizers are preferred. Further, the plasticizer may be a liquid or a solid, and is preferably colorless due to restrictions on the composition. Thermally, it is preferably stable at higher temperatures, and the decomposition start temperature is preferably 150 ° C. or higher, more preferably 200 ° C. or higher. The addition amount can be adjusted for various performances required for the cellulose ester film, and the blending amount is appropriately selected within a range not impairing the object of the present invention, and preferably 1 to 100 parts by mass of the cellulose ester resin. It is 50 mass%, More preferably, it is 3-30 mass%. 5-15 mass% is especially preferable.

Hereinafter, the plasticizer used in the present invention will be further described. Specific examples are not limited to these examples.
Polyhydric alcohol ester plasticizer: Specific examples include polyhydric alcohol ester plasticizers described in paragraphs 30 to 33 of JP-A No. 2003-12823.
These alkylate groups, cycloalkylcarboxylate groups, and arylate groups may be the same or different, and may be further substituted. Further, it may be a mixture of alkylate group, cycloalkylcarboxylate group, and arylate group, and these substituents may be bonded by a covalent bond. Furthermore, the polyhydric alcohol part may be substituted, the partial structure of the polyhydric alcohol may be a part of the polymer or regularly pendant, an antioxidant, an acid scavenger, an ultraviolet absorber, etc. It may be introduced into a part of the molecular structure of the additive.

  Dicarboxylic acid ester plasticizers: Specifically, alkyldocarboxylic acid alkyl ester plasticizers such as didodecyl malonate (C1), dioctyl adipate (C4), dibutyl sebacate (C8), dicyclopentyl succinate, Alkyl dicarboxylic acid cycloalkyl ester plasticizers such as dicyclohexyl adipate, alkyl dicarboxylic acid aryl ester plasticizers such as diphenyl succinate and di4-methylphenyl glutarate, dihexyl-1,4-cyclohexanedicarboxylate, Cycloalkyldicarboxylic acid alkyl ester plasticizers such as didecylbicyclo [2.2.1] heptane-2,3-dicarboxylate, dicyclohexyl-1,2-cyclobutanedicarboxylate, dicyclopropyl-1,2 Cycloalkyldicarboxylic acid cycloalkyl ester plasticizers such as cyclohexyl dicarboxylate, aryl cycloalkyldicarboxylates such as diphenyl-1,1-cyclopropyldicarboxylate, di2-naphthyl-1,4-cyclohexanedicarboxylate Ester plasticizers, aryl dicarboxylic acid alkyl ester plasticizers such as diethyl phthalate, dimethyl phthalate, dioctyl phthalate, dibutyl phthalate and di-2-ethylhexyl phthalate, and aryl dicarboxylic acid cycloalkyls such as dicyclopropyl phthalate and dicyclohexyl phthalate Examples include ester plasticizers and aryl dicarboxylic acid aryl ester plasticizers such as diphenyl phthalate and di4-methylphenyl phthalate. These alkoxy groups and cycloalkoxy groups may be the same or different, may be mono-substituted, and these substituents may be further substituted. The alkyl group and cycloalkyl group may be mixed, and these substituents may be bonded together by a covalent bond. Furthermore, the aromatic ring of phthalic acid may be substituted, and a multimer such as a dimer, trimer or tetramer may be used. In addition, the partial structure of phthalate ester may be part of the polymer or regularly pendant to the polymer, and introduced into part of the molecular structure of additives such as antioxidants, acid scavengers, UV absorbers, etc. May be.

  Polycarboxylic acid ester plasticizers: Specifically, alkyl polycarboxylic acid alkyl ester plastics such as tridodecyl tricarbarate and tributyl-meso-butane-1,2,3,4-tetracarboxylate Agents, alkyl polyvalent carboxylic acid cycloalkyl ester type plasticizers such as tricyclohexyl tricarbarate, tricyclopropyl-2-hydroxy-1,2,3-propanetricarboxylate, triphenyl 2-hydroxy-1,2 Alkyl polycarboxylic acid aryl ester plasticizers such as 1,3-propanetricarboxylate, tetra-3-methylphenyltetrahydrofuran-2,3,4,5-tetracarboxylate, tetrahexyl-1,2,3,4 -Cyclobutane tetracarboxylate, tetrabutyl-1,2, 1,4-cyclopentanetetracarboxylate and other cycloalkyl polycarboxylic acid alkyl ester plasticizers, tetracyclopropyl-1,2,3,4-cyclobutanetetracarboxylate, tricyclohexyl-1,3,5-cyclohexyl Cycloalkyl polycarboxylic acid cycloalkyl ester plasticizers such as tricarboxylate, triphenyl-1,3,5-cyclohexyl tricarboxylate, hexa-4-methylphenyl-1,2,3,4,5,6 -Cycloalkyl polycarboxylic acid aryl ester plasticizers such as cyclohexyl hexacarboxylate, tridodecylbenzene-1,2,4-tricarboxylate, tetraoctylbenzene-1,2,4,5-tetracarboxylate, etc. Aryl polycarboxylic acid Lester ester plasticizer, aryl polyvalent carboxylic acid cycloalkyl ester plasticizer tri such as tricyclopentylbenzene-1,3,5-tricarboxylate, tetracyclohexylbenzene-1,2,3,5-tetracarboxylate Aryl polycarboxylic acid aryl ester-based plasticizers such as phenylbenzene-1,3,5-tetracartoxylate and hexa-4-methylphenylbenzene-1,2,3,4,5,6-hexacarboxylate Can be mentioned. These alkoxy groups and cycloalkoxy groups may be the same or different, may be mono-substituted, and these substituents may be further substituted. The alkyl group and cycloalkyl group may be mixed, and these substituents may be bonded together by a covalent bond. Furthermore, the aromatic ring of phthalic acid may be substituted, and a multimer such as a dimer, trimer or tetramer may be used. In addition, the partial structure of phthalate ester may be part of the polymer or regularly pendant to the polymer, and introduced into part of the molecular structure of additives such as antioxidants, acid scavengers, UV absorbers, etc. May be.

  Polymer plasticizer: Specifically, aliphatic hydrocarbon polymer, alicyclic hydrocarbon polymer, acrylic polymer such as polyethyl acrylate and polymethyl methacrylate, polyvinyl isobutyl ether, poly N-vinyl pyrrolidone, etc. Examples include vinyl polymers, polystyrene, styrene polymers such as poly-4-hydroxystyrene, polybutylene succinate, polyesters such as polyethylene terephthalate and polyethylene naphthalate, polyethers such as polyethylene oxide and polypropylene oxide, polyamides, polyurethanes, and polyureas. It is done. The number average molecular weight is preferably about 1,000 to 500,000, particularly preferably 5,000 to 200,000. If it is 1000 or less, a problem arises in volatility, and if it exceeds 500,000, the plasticizing ability is lowered, which adversely affects the mechanical properties of the cellulose ester derivative composition. These polymer plasticizers may be a homopolymer composed of one type of repeating unit or a copolymer having a plurality of repeating structures. Two or more of the above polymers may be used in combination, and other plasticizers, antioxidants, acid scavengers, ultraviolet absorbers, slip agents, slip agents, and the like may be included.

  Among the plasticizers, it is generally preferable that no volatile component is generated during heat melting. Specific examples include nonvolatile phosphate esters described in JP-A-6-501040. For example, among arylene bis (diaryl phosphate) esters and the above exemplified compounds, trimethylolpropane tribenzoate is preferable. It is not limited to. When the volatile component is due to thermal decomposition of the plasticizer, the thermal decomposition temperature Td (1.0) of the plasticizer is higher than the melting temperature of the film-forming material when defined as the temperature at which the mass decreases by 1.0% by mass. Is required. This is because, for the above purpose, the plasticizer is added to the cellulose ester in a larger amount than other film constituent materials, and the presence of the volatile component has a great influence on the quality of the obtained film. The thermal decomposition temperature Td (1.0) can be measured with a commercially available differential thermogravimetric analysis (TG-DTA) apparatus.

《Acrylic polymer》
The cellulose ester film of the present invention may contain an acrylic polymer. Here, the acrylic polymer includes a methacrylic polymer. The total amount of the resin in the optical film may be an acrylic polymer, or may be used in combination with other resins, and the content can be arbitrarily selected within the range of 0 to 100%. In the present invention, it is most preferable to use in combination with a cellulose ester.

As an acrylic polymer used in the present invention, when used in combination with a cellulose ester film, it preferably exhibits negative birefringence as a function of the stretching direction, and the structure is not particularly limited. It is preferable that a polymer having a weight average molecular weight of 500 or more and 1000000 or less obtained by polymerizing a polymerizable unsaturated monomer is appropriately selected.
The proper molecular weight range of the acrylic polymer is as described above, but when it is contained in an amount of 30% by mass or more, the weight average molecular weight is preferably 80,000 to 1,000,000 from the viewpoint of compatibility with the cellulose ester.
The weight average molecular weight of the acrylic polymer of the present invention can be measured by gel permeation chromatography. The measurement conditions are as follows.
Solvent: Methylene chloride Column: Shodex K806, K805, K803G (Used by connecting three Showa Denko Co., Ltd.)
Column temperature: 25 ° C
Sample concentration: 0.1% by mass
Detector: RI Model 504 (manufactured by GL Sciences)
Pump: L6000 (manufactured by Hitachi, Ltd.)
Flow rate: 1.0ml / min
Calibration curve: Standard polystyrene STK standard polystyrene (manufactured by Tosoh Corp.) Mw = 2,800,000-500 calibration curves with 13 samples were used. The 13 samples are preferably used at approximately equal intervals.

The acrylic polymer can be directly added and dissolved as a material constituting the dope liquid described later, or can be added to the dope liquid after being previously dissolved in an organic solvent for dissolving the cellulose ester.
<Ester compound in which at least one of pyranose structure or furanose structure is 1 or more and 12 or less and all or part of OH groups of the structure are esterified>
When the optical film of the present invention is a cellulose ester film, it contains an ester compound in which at least one of the pyranose structure or furanose structure is 1 to 12, and all or part of the OH groups in the structure are esterified. It is characterized by.
The proportion of esterification is preferably 70% or more of the OH groups present in the pyranose structure or furanose structure.
In the present invention, ester compounds are collectively referred to as sugar ester compounds.

Examples of the ester compound of the present invention include the following, but the present invention is not limited thereto.
Glucose, galactose, mannose, fructose, xylose, or arabinose, lactose, sucrose or tose, 1F-fructosyl nystose, stachyose, maltitol, lactitol, lactulose, cellobiose, maltose, cellotriose, maltotriose, raffinose or kestose .
In addition, gentiobiose, gentiotriose, gentiotetraose, xylotriose, galactosyl sucrose, and the like are also included.
Among these compounds, compounds having both a pyranose structure and a furanose structure are particularly preferable.
As examples, sucrose, kestose, nystose, 1F-fructosyl nystose, stachyose and the like are preferable, and sucrose is more preferable.
Specifically, glucose pentaacetate, glucose pentapropionate, glucose pentabutyrate, saccharose octaacetate, saccharose octabenzoate and the like can be preferably mentioned, and among these, saccharose octaacetate and saccharose octabenzoate are more preferable, and saccharose Octabenzoate is particularly preferred.
Monopet SB (Daiichi Kogyo Seiyaku Co., Ltd.) etc. can be used as a commercial item.
The cellulose ester film of the present invention preferably contains the ester compound of the present invention in an amount of 1 to 30% by mass of the cellulose ester film in order to suppress the fluctuation of the retardation value and stabilize the display quality. 5 to 30% by mass is preferable.

《Polymer material》
In the cellulose ester film of the present invention, polymer materials and oligomers other than cellulose ester may be appropriately selected and mixed. The polymer materials and oligomers described above are preferably those having excellent compatibility with the cellulose ester, and the transmittance when formed into a film is preferably 80% or more, more preferably 90% or more, and further preferably 92% or more. The purpose of mixing at least one of polymer materials and oligomers other than cellulose ester includes meanings for controlling viscosity at the time of heating and melting and improving film physical properties after film processing. In this case, it can contain as an above-mentioned other additive.

上記一般式（４）中、Ｒ１及びＲ２は、Ｈまたは置換基である。ヒンダードアミン光安定剤化合物の具体例には、４−ヒドロキシ−２，２，６，６−テトラメチルピペリジン、１−アリル−４−ヒドロキシ−２，２，６，６−テトラメチルピペリジン、１−ベンジル−４−ヒドロキシ−２，２，６，６−テトラメチルピペリジン、１−（４−ｔ−ブチル−２−ブテニル）−４−ヒドロキシ−２，２，６，６−テトラメチルピペリジン、４−ステアロイルオキシ−２，２，６，６−テトラメチルピペリジン、１−エチル−４−サリチロイルオキシ−２，２，６，６−テトラメチルピペリジン、４−メタクリロイルオキシ−１，２，２，６，６−ペンタメチルピペリジン、１，２，２，６，６−ペンタメチルピペリジン−４−イル−β（３，５−ジ−ｔ−ブチル−４−ヒドロキシフェニル）−プロピオネート、１−ベンジル−２，２，６，６−テトラメチル−４−ピペリジニルマレイネート（ｍａｌｅｉｎａｔｅ）、（ジ−２，２，６，６−テトラメチルピペリジン−４−イル）−アジペート、（ジ−２，２，６，６−テトラメチルピペリジン−４−イル）−セバケート、（ジ−１，２，３，６−テトラメチル−２，６−ジエチル−ピペリジン−４−イル）−セバケート、（ジ−１−アリル−２，２，６，６−テトラメチル−ピペリジン−４−イル）−フタレート、１−アセチル−２，２，６，６−テトラメチルピペリジン−４−イル−アセテート、トリメリト酸−トリ−（２，２，６，６−テトラメチルピペリジン−４−イル）エステル、１−アクリロイル−４−ベンジルオキシ−２，２，６，６−テトラメチルピペリジン、ジブチル−マロン酸−ジ−（１，２，２，６，６−ペンタメチル−ピペリジン−４−イル）−エステル、ジベンジル−マロン酸−ジ−（１，２，３，６−テトラメチル−２，６−ジエチル−ピペリジン−４−イル）−エステル、ジメチル−ビス−（２，２，６，６−テトラメチルピペリジン−４−オキシ）−シラン，トリス−（１−プロピル−２，２，６，６−テトラメチルピペリジン−４−イル）−ホスフィット、トリス−（１−プロピル−２，２，６，６−テトラメチルピペリジン−４−イル）−ホスフェート，Ｎ，Ｎ′−ビス−（２，２，６，６−テトラメチルピペリジン−４−イル）−ヘキサメチレン−１，６−ジアミン、Ｎ，Ｎ′−ビス−（２，２，６，６−テトラメチルピペリジン−４−イル）−ヘキサメチレン−１，６−ジアセトアミド、１−アセチル−４−（Ｎ−シクロヘキシルアセトアミド）−２，２，６，６−テトラメチル−ピペリジン、４−ベンジルアミノ−２，２，６，６−テトラメチルピペリジン、Ｎ，Ｎ′−ビス−（２，２，６，６−テトラメチルピペリジン−４−イル）−Ｎ，Ｎ′−ジブチル−アジパミド、Ｎ，Ｎ′−ビス−（２，２，６，６−テトラメチルピペリジン−４−イル）−Ｎ，Ｎ′−ジシクロヘキシル−（２−ヒドロキシプロピレン）、Ｎ，Ｎ′−ビス−（２，２，６，６−テトラメチルピペリジン−４−イル）−ｐ−キシリレン−ジアミン、４−（ビス−２−ヒドロキシエチル）−アミノ−１，２，２，６，６−ペンタメチルピペリジン、４−メタクリルアミド−１，２，２，６，６−ペンタメチルピペリジン、α−シアノ−β−メチル−β−［Ｎ−（２，２，６，６−テトラメチルピペリジン−４−イル）］−アミノ−アクリル酸メチルエステル。好ましいヒンダードアミン光安定剤の例には、以下のＨＡＬＳ−１及びＨＡＬＳ−２が含まれる。

《Light stabilizer》
Light stabilizers include hindered amine light stabilizer (HALS) compounds, which are known compounds, such as columns 5-11 of US Pat. No. 4,619,956 and US Pat. , 839,405, as described in columns 3 to 5, including 2,2,6,6-tetraalkylpiperidine compounds, or acid addition salts thereof or complexes of them with metal compounds It is. Such a compound includes a compound represented by the following general formula (4).

In the general formula (4), R1 and R2 are H or a substituent. Specific examples of hindered amine light stabilizer compounds include 4-hydroxy-2,2,6,6-tetramethylpiperidine, 1-allyl-4-hydroxy-2,2,6,6-tetramethylpiperidine, 1-benzyl. -4-hydroxy-2,2,6,6-tetramethylpiperidine, 1- (4-t-butyl-2-butenyl) -4-hydroxy-2,2,6,6-tetramethylpiperidine, 4-stearoyl Oxy-2,2,6,6-tetramethylpiperidine, 1-ethyl-4-salicyloyloxy-2,2,6,6-tetramethylpiperidine, 4-methacryloyloxy-1,2,2,6 6-pentamethylpiperidine, 1,2,2,6,6-pentamethylpiperidin-4-yl-β (3,5-di-t-butyl-4-hydroxyphenyl) -propionate, -Benzyl-2,2,6,6-tetramethyl-4-piperidinyl maleate, (di-2,2,6,6-tetramethylpiperidin-4-yl) -adipate, (di- 2,2,6,6-tetramethylpiperidin-4-yl) -sebacate, (di-1,2,3,6-tetramethyl-2,6-diethyl-piperidin-4-yl) -sebacate, (di -1-allyl-2,2,6,6-tetramethyl-piperidin-4-yl) -phthalate, 1-acetyl-2,2,6,6-tetramethylpiperidin-4-yl-acetate, trimellitic acid- Tri- (2,2,6,6-tetramethylpiperidin-4-yl) ester, 1-acryloyl-4-benzyloxy-2,2,6,6-tetramethylpiperidine, dibutyl-malonic acid-di -(1,2,2,6,6-pentamethyl-piperidin-4-yl) -ester, dibenzyl-malonic acid-di- (1,2,3,6-tetramethyl-2,6-diethyl-piperidine- 4-yl) -ester, dimethyl-bis- (2,2,6,6-tetramethylpiperidine-4-oxy) -silane, tris- (1-propyl-2,2,6,6-tetramethylpiperidine- 4-yl) -phosphite, tris- (1-propyl-2,2,6,6-tetramethylpiperidin-4-yl) -phosphate, N, N′-bis- (2,2,6,6- Tetramethylpiperidin-4-yl) -hexamethylene-1,6-diamine, N, N'-bis- (2,2,6,6-tetramethylpiperidin-4-yl) -hexamethylene-1,6- Diacetamide, 1-acetyl -4- (N-cyclohexylacetamide) -2,2,6,6-tetramethyl-piperidine, 4-benzylamino-2,2,6,6-tetramethylpiperidine, N, N'-bis- (2, 2,6,6-tetramethylpiperidin-4-yl) -N, N'-dibutyl-adipamide, N, N'-bis- (2,2,6,6-tetramethylpiperidin-4-yl) -N , N'-dicyclohexyl- (2-hydroxypropylene), N, N'-bis- (2,2,6,6-tetramethylpiperidin-4-yl) -p-xylylene-diamine, 4- (bis-2 -Hydroxyethyl) -amino-1,2,2,6,6-pentamethylpiperidine, 4-methacrylamide-1,2,2,6,6-pentamethylpiperidine, α-cyano-β-methyl-β- [N- (2,2 6,6-tetramethyl-piperidin-4-yl)] - amino - acrylic acid methyl ester. Examples of preferred hindered amine light stabilizers include the following HALS-1 and HALS-2.

  These hindered amine light stabilizers can be used alone or in combination of two or more, and these hindered amine light stabilizers can be used in combination with additives such as plasticizers, acid scavengers, and UV absorbers. Alternatively, it may be introduced into a part of the molecular structure of the additive. The blending amount is appropriately selected within a range not impairing the object of the present invention, but is preferably 0.01 to 20 parts by mass, more preferably 0.02 to 15 parts by mass, with respect to 100 parts by mass of the cellulose ester resin. Especially preferably, it is 0.05-10 mass parts.

<Ultraviolet absorber>
The cellulose ester film of the present invention preferably contains an ultraviolet absorber, and examples of the ultraviolet absorber used include benzotriazole, 2-hydroxybenzophenone, and salicylic acid phenyl ester. For example, 2- (5-methyl-2-hydroxyphenyl) benzotriazole, 2- [2-hydroxy-3,5-bis (α, α-dimethylbenzyl) phenyl] -2H-benzotriazole, 2- (3 Triazoles such as 5-di-t-butyl-2-hydroxyphenyl) benzotriazole, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-octoxybenzophenone, 2,2′-dihydroxy-4-methoxybenzophenone And benzophenones.

Here, among ultraviolet absorbers, ultraviolet absorbers having a molecular weight of 400 or more are less likely to volatilize at a high boiling point and are difficult to disperse even during high-temperature molding, so that the weather resistance is effectively improved with a relatively small amount of addition. be able to.
Examples of the ultraviolet absorber having a molecular weight of 400 or more include 2- [2-hydroxy-3,5-bis (α, α-dimethylbenzyl) phenyl] -2-benzotriazole, 2,2-methylenebis [4- (1, 1,3,3-tetrabutyl) -6- (2H-benzotriazol-2-yl) phenol], bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate, bis ( Hindered amines such as 1,2,2,6,6-pentamethyl-4-piperidyl) sebacate and 2- (3,5-di-t-butyl-4-hydroxybenzyl) -2-n-butylmalonic acid Bis (1,2,2,6,6-pentamethyl-4-piperidyl), 1- [2- [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyloxy] ethyl L] -4- [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyloxy] -2,2,6,6-tetramethylpiperidine and the like, hindered phenol and hindered amine A hybrid system having both structures can be mentioned, and these can be used alone or in combination of two or more. Among these, 2- [2-hydroxy-3,5-bis (α, α-dimethylbenzyl) phenyl] -2-benzotriazole and 2,2-methylenebis [4- (1,1,3,3- Tetrabutyl) -6- (2H-benzotriazol-2-yl) phenol] is particularly preferred.

Furthermore, an antistatic agent can be added to the cellulose ester film of the present invention to impart antistatic performance to the cellulose ester film.
For the cellulose ester film of the present invention, a flame retardant acrylic resin composition containing a phosphorus flame retardant may be used.
Phosphorus flame retardants used here include red phosphorus, triaryl phosphate ester, diaryl phosphate ester, monoaryl phosphate ester, aryl phosphonate compound, aryl phosphine oxide compound, condensed aryl phosphate ester, halogenated alkyl phosphorus. Examples thereof include one or a mixture of two or more selected from acid esters, halogen-containing condensed phosphates, halogen-containing condensed phosphonates, halogen-containing phosphites, and the like.
Specific examples include triphenyl phosphate, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, phenylphosphonic acid, tris (β-chloroethyl) phosphate, tris (dichloropropyl). Examples thereof include phosphate and tris (tribromoneopentyl) phosphate.

The thickness of the cellulose ester film of the present invention is preferably 20 μm or more. More preferably, it is 30 μm or more.
The upper limit of the thickness is not particularly limited, but in the case of forming a film by a solution casting method, the upper limit is about 250 μm from the viewpoint of applicability, foaming, solvent drying, and the like. In addition, the thickness of a film can be suitably selected according to a use.
The cellulose ester film of the present invention preferably has a total light transmittance of 90% or more, more preferably 93% or more. Moreover, as a realistic upper limit, it is about 99%. In order to achieve excellent transparency expressed by such total light transmittance, it is necessary not to introduce additives and copolymerization components that absorb visible light, or to remove foreign substances in the polymer by high-precision filtration. It is effective to reduce the diffusion and absorption of light inside the film.
Also, reduce the surface roughness of the film surface by reducing the surface roughness of the film contact part (cooling roll, calender roll, drum, belt, coating substrate in solution casting, transport roll, etc.) during film formation. It is also effective to reduce the diffusion and reflection of light on the film surface by reducing the refractive index of the resin.
The cellulose ester film of the present invention can be particularly preferably used as a polarizing plate protective film for a large-sized liquid crystal display device or a liquid crystal display device for outdoor use as long as the above physical properties are satisfied.

上記一般式（６）中、ｎは０〜１２である。用いることができるさらに可能な酸捕捉剤としては、特開平５−１９４７８８号公報の段落８７〜１０５に記載されているものが含まれる。 <Acid scavenger>
The acid scavenger preferably comprises an epoxy compound as an acid scavenger described in US Pat. No. 4,137,201. Epoxy compounds as such acid scavengers are known in the art and are derived by condensation of various polyglycol diglycidyl ethers, particularly about 8 to 40 moles of ethylene oxide per mole of polyglycol. Glycol, diglycidyl ether of glycerol, etc., metal epoxy compounds (such as those conventionally used in and with vinyl chloride polymer compositions), epoxidized ether condensation products, diphenols of bisphenol A Glycidyl ether (i.e., 4,4'-dihydroxydiphenyldimethylmethane), epoxidized unsaturated fatty acid ester (especially an ester of an alkyl of about 4 to 2 carbon atoms of a fatty acid of 2 to 22 carbon atoms (e.g. butyl Epoxy stearate) , And various epoxidized long chain fatty acid triglycerides and the like (e.g., epoxidized vegetable oils and other unsaturated natural oils, which are represented and exemplified by compositions such as epoxidized soybean oil) These are referred to as unsaturated fatty acids and these fatty acids generally contain 12 to 22 carbon atoms)). Particularly preferred are commercially available epoxy group-containing epoxide resin compounds EPON 815c and other epoxidized ether oligomer condensation products represented by the following general formula (6).

In the general formula (6), n is 0-12. Further possible acid scavengers that can be used include those described in paragraphs 87 to 105 of JP-A-5-194788.

"Antioxidant"
In the present invention, the resin mixture such as cellulose ester preferably contains an antioxidant in order to improve the thermal decomposability and thermal colorability during the molding process.
In the present invention, a preferable antioxidant is a phosphorus-based or phenol-based antioxidant, and it is more preferable to combine a phosphorus-based and a phenol-based antioxidant at the same time.

一般式（ＡＯ１）中、Ｒ₁、Ｒ₂及びＲ₃は、さらに置換されているか又は置換されて
いないアルキル置換基を表す。フェノール系酸化防止剤の具体例には、ｎ−オクタデシル３−（３，５−ジ−ｔ−ブチル−４−ヒドロキシフェニル）−プロピオネート、ｎ−オクタデシル３−（３，５−ジ−ｔ−ブチル−４−ヒドロキシフェニル）−アセテート、ｎ−オクタデシル３，５−ジ−ｔ−ブチル−４−ヒドロキシベンゾエート、ｎ−ヘキシル３，５−ジ−ｔ−ブチル−４−ヒドロキシフェニルベンゾエート、ｎ−ドデシル３，５−ジ−ｔ−ブチル−４−ヒドロキシフェニルベンゾエート、ネオ−ドデシル３−（３，５−ジ−ｔ−ブチル−４−ヒドロキシフェニル）プロピオネート、ドデシルβ（３，５−ジ−ｔ−ブチル−４−ヒドロキシフェニル）プロピオネート、エチルα−（４−ヒドロキシ−３，５−ジ−ｔ−ブチルフェニル）イソブチレート、オクタデシルα−（４−ヒドロキシ−３，５−ジ−ｔ−ブチルフェニル）イソブチレート、オクタデシルα−（４−ヒドロキシ−３，５−ジ−ｔ−ブチル−４−ヒドロキシフェニル）プロピオネート、２−（ｎ−オクチルチオ）エチル３，５−ジ−ｔ−ブチル−４−ヒドロキシ−ベンゾエート、２−（ｎ−オクチルチオ）エチル３，５−ジ−ｔ−ブチル−４−ヒドロキシ−フェニルアセテート、２−（ｎ−オクタデシルチオ）エチル３，５−ジ−ｔ−ブチル−４−ヒドロキシフェニルアセテート、２−（ｎ−オクタデシルチオ）エチル３，５−ジ−ｔ−ブチル−４−ヒドロキシ−ベンゾエート、２−（２−ヒドロキシエチルチオ）エチル３，５−ジ−ｔ−ブチル−４−ヒドロキシベンゾエート、ジエチルグリコールビス−（３，５−ジ−ｔ−ブチル−４−ヒドロキシ−フェニル）プロピオネート、２−（ｎ−オクタデシルチオ）エチル３−（３，５−ジ−ｔ−ブチル−４−ヒドロキシフェニル）プロピオネート、ステアルアミドＮ，Ｎ−ビス−［エチレン３−（３，５−ジ−ｔ−ブチル−４−ヒドロキシフェニル）プロピオネート］、ｎ−ブチルイミノＮ，Ｎ−ビス−［エチレン３−（３，５−ジ−ｔ−ブチル−４−ヒドロキシフェニル）プロピオネート］、２−（２−ステアロイルオキシエチルチオ）エチル３，５−ジ−ｔ−ブチル−４−ヒドロキシベンゾエート、２−（２−ステアロイルオキシエチルチオ）エチル７−（３−メチル−５−ｔ−ブチル−４−ヒドロキシフェニル）ヘプタノエート、１，２−プロピレングリコールビス−［３−（３，５−ジ−ｔ−ブチル−４−ヒドロキシフェニル）プロピオネート］、エチレングリコールビス−［３−（３，５−ジ−ｔ−ブチル−４−ヒドロキシフェニル）プロピオネート］、ネオペンチルグリコールビス−［３−（３，５−ジ−ｔ−ブチル−４−ヒドロキシフェニル）プロピオネート］、エチレングリコールビス−（３，５−ジ−ｔ−ブチル−４−ヒドロキシフェニルアセテート）、グリセリン−ｌ−ｎ−オクタデカノエート−２，３−ビス−（３，５−ジ−ｔ−ブチル−４−ヒドロキシフェニルアセテート）、ペンタエリトリトール−テトラキス−［３−（３′，５′−ジ−ｔ−ブチル−４′−ヒドロキシフェニル）プロピオネート］、１，１，１−トリメチロールエタン−トリス−［３−（３，５−ジ−ｔ−ブチル−４−ヒドロキシフェニル）プロピオネート］、ソルビトールヘキサ−［３−（３，５−ジ−ｔ−ブチル−４−ヒドロキシフェニル）プロピオネート］、２−ヒドロキシエチル７−（３−メチル−５−ｔ−ブチル−４−ヒドロキシフェニル）プロピオネート、２−ステアロイルオキシエチル７−（３−メチル−５−ｔ−ブチル−４−ヒドロキシフェニル）ヘプタノエート、１，６−ｎ−ヘキサンジオール−ビス［（３′，５′−ジ−ｔ−ブチル−４−ヒドロキシフェニル）プロピオネート］、ペンタエリトリトール−テトラキス（３，５−ジ−ｔ−ブチル−４−ヒドロキシヒドロシンナメート）が含まれる。上記タイプのフェノール系化合物は、例えば、Ｃｉｂａ Ｓｐｅｃｉａｌｔｙ Ｃｈｅｍｉｃａｌｓから、“Ｉｒｇａｎｏｘ１０７６”及び“Ｉｒｇａｎｏｘ１０１０”という商品名で市販されている。 Hereinafter, the antioxidant that can be suitably used in the present invention will be described.
<Phenolic antioxidant>
In the present invention, a phenolic antioxidant represented by the following general formula (AO1) can be used.

In general formula (AO1), R ₁ , R ₂ and R ₃ represent an alkyl substituent which is further substituted or unsubstituted. Specific examples of phenolic antioxidants include n-octadecyl 3- (3,5-di-t-butyl-4-hydroxyphenyl) -propionate, n-octadecyl 3- (3,5-di-t-butyl). -4-hydroxyphenyl) -acetate, n-octadecyl 3,5-di-t-butyl-4-hydroxybenzoate, n-hexyl 3,5-di-t-butyl-4-hydroxyphenylbenzoate, n-dodecyl 3 , 5-di-t-butyl-4-hydroxyphenylbenzoate, neo-dodecyl 3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate, dodecyl β (3,5-di-t-butyl -4-hydroxyphenyl) propionate, ethyl α- (4-hydroxy-3,5-di-t-butylphenyl) isobutyrate, octadecyl α- (4-hydroxy-3,5-di-t-butylphenyl) isobutyrate, octadecyl α- (4-hydroxy-3,5-di-t-butyl-4-hydroxyphenyl) propionate, 2- (n- Octylthio) ethyl 3,5-di-t-butyl-4-hydroxy-benzoate, 2- (n-octylthio) ethyl 3,5-di-t-butyl-4-hydroxy-phenylacetate, 2- (n-octadecyl) Thio) ethyl 3,5-di-t-butyl-4-hydroxyphenyl acetate, 2- (n-octadecylthio) ethyl 3,5-di-t-butyl-4-hydroxy-benzoate, 2- (2-hydroxy Ethylthio) ethyl 3,5-di-t-butyl-4-hydroxybenzoate, diethyl glycol bis- (3,5-di-t-butyl-4- Droxy-phenyl) propionate, 2- (n-octadecylthio) ethyl 3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate, stearamide N, N-bis- [ethylene 3- (3,5 -Di-t-butyl-4-hydroxyphenyl) propionate], n-butylimino N, N-bis- [ethylene 3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], 2- ( 2-stearoyloxyethylthio) ethyl 3,5-di-tert-butyl-4-hydroxybenzoate, 2- (2-stearoyloxyethylthio) ethyl 7- (3-methyl-5-tert-butyl-4-hydroxy) Phenyl) heptanoate, 1,2-propylene glycol bis- [3- (3,5-di-t-butyl-4-hydroxypheny ) Propionate], ethylene glycol bis- [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], neopentyl glycol bis- [3- (3,5-di-t-butyl-4) -Hydroxyphenyl) propionate], ethylene glycol bis- (3,5-di-t-butyl-4-hydroxyphenylacetate), glycerin-ln-octadecanoate-2,3-bis- (3,5 -Di-t-butyl-4-hydroxyphenyl acetate), pentaerythritol-tetrakis- [3- (3 ', 5'-di-t-butyl-4'-hydroxyphenyl) propionate], 1,1,1- Trimethylolethane-tris- [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], sorbitol Oxa- [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], 2-hydroxyethyl 7- (3-methyl-5-tert-butyl-4-hydroxyphenyl) propionate, 2- Stearoyloxyethyl 7- (3-methyl-5-t-butyl-4-hydroxyphenyl) heptanoate, 1,6-n-hexanediol-bis [(3 ', 5'-di-t-butyl-4-hydroxy Phenyl) propionate], pentaerythritol-tetrakis (3,5-di-t-butyl-4-hydroxyhydrocinnamate). Phenol compounds of the above type are commercially available from Ciba Specialty Chemicals under the trade names “Irganox 1076” and “Irganox 1010”, for example.

<Phosphorus antioxidant>
As the phosphorus-based antioxidant that can be used in the present invention, a phosphorus-based compound such as phosphite, phosphonite, or phosphinite can be used.
Conventionally known compounds can be used as the phosphorus-based antioxidant. For example, Japanese Patent Application Laid-Open Nos. 2002-138188, 2005-344444, paragraph numbers 0022 to 0027, Japanese Patent Application Laid-Open No. 2004-18279, paragraph numbers 0023 to 0039, Japanese Patent Application Laid-Open No. 10-306175, Japanese Patent Application Laid-Open No. 1-254744, and Japanese Patent Application Laid-Open No. -270892, JP-A-5-202078, JP-A-5-178870, JP-T-2004-504435, JP-T-2004-530759, and JP-A-2005-353229 Is preferred.
Preferable phosphorus compounds include those described in paragraph 21 of JP-A-2008-257220, but are not limited thereto.

In addition to the above, specific examples of phosphorus compounds that can be used in the present invention include triphenyl phosphite, diphenylisodecyl phosphite, phenyl diisodecyl phosphite, tris (nonylphenyl) phosphite, tris (dinonylphenyl). ) Phosphite, Tris (2,4-di-t-butylphenyl) phosphite, 10- (3,5-di-t-butyl-4-hydroxybenzyl) -9,10-dihydro-9-oxa-10 -Phosphaphenanthrene-10-oxide, 6- [3- (3-t-butyl-4-hydroxy-5-methylphenyl) propoxy] -2,4,8,10-tetra-t-butyldibenz [d, f ] [1.3.2] Monophosphite compounds such as dioxaphosphine and tridecyl phosphite; Diphosphites such as -butylidene-bis (3-methyl-6-tert-butylphenyl-di-tridecyl phosphite), 4,4'-isopropylidene-bis (phenyl-di-alkyl (C12-C15) phosphite) Compounds; triphenylphosphonite, tetrakis (2,4-di-tert-butylphenyl) [1,1-biphenyl] -4,4'-diylbisphosphonite, tetrakis (2,4-di-tert-butyl) Phosphonite compounds such as -5-methylphenyl) [1,1-biphenyl] -4,4'-diylbisphosphonite; Phosphinite compounds such as triphenylphosphinite and 2,6-dimethylphenyldiphenylphosphinite Phosphine such as triphenylphosphine and tris (2,6-dimethoxyphenyl) phosphine Emissions-based compounds; and the like.
Phosphorus compounds of the above type are, for example, from Sumitomo Chemical Co., Ltd. “Sumilizer GP”, from ADEKA Co., Ltd. “ADK STAB PEP-24G”, “ADK STAB PEP-36”, “ADK STAB 3010”, “ADK STAB 2112”. “IRGAFOS P-EPQ” and “IRGAFOS 168” from Ciba Specialty Chemicals, Inc. and “GSY-P101” from Sakai Chemical Industry Co., Ltd.

<Other antioxidants>
Dilauryl-3,3′-thiodipropionate, dimyristyl-3,3′-thiodipropionate, distearyl-3,3′-thiodipropionate, pentaerythrityltetrakis (3-laurylthiopropioate) Nate) and the like, 2-tert-butyl-6- (3-tert-butyl-2-hydroxy-5-methylbenzyl) -4-methylphenyl acrylate, 2- [1- (2-hydroxy) 3,5-di-tert-pentylphenyl) ethyl] -4,6-di-tert-pentylphenyl acrylate, 3,4-dihydro-2H-1 described in JP-B-08-27508 -Benzopyran compounds, 3,3'-spirodichroman compounds, 1,1-spiroindane compounds, morpholine, thiomorpho Emissions, thiomorpholine oxide, thiomorpholine dioxide, a compound having a piperazine skeleton partial structure, oxygen scavenger dialkoxy benzene type compound in JP-03-174150 Patent describes the like. These antioxidant partial structures may be part of the polymer or regularly pendant into the polymer and introduced into part of the molecular structure of additives such as plasticizers, acid scavengers, and UV absorbers. It may be.

Next, the melt casting method will be described as a method for producing the cellulose ester film of the present invention.
<Melt casting method>
The manufacturing method of a cellulose-ester film can be manufactured, for example with the manufacturing apparatus shown in FIG. The production apparatus comprises a drying apparatus (not shown) for drying a pellet obtained by mixing and melting at least cellulose ester (or modified cellulose ester), a plasticizer, and other additives to obtain a molten mixture containing a gel filler, and a gel filler. Extruder 1 for extruding the molten mixture in a heated and melted state, a filtering device 2 for filtering the extruded molten mixture to remove foreign matters, a static mixer 3 for remixing, a casting die 4, and cooling and solidifying First to third cooling rolls 5, 7, 8 serving as a film, a peeling roll 9 for peeling the film, a stretching device 12 for stretching the peeled film, and knurling devices 14, 15 for knurling the stretched film And a winding device 16 for winding the film.

On the first cooling roll 5, it is extruded from the casting die 4 in a molten state, cooled and solidified, and further cooled and solidified on the second cooling roll 7 and the third cooling roll 8. In addition, a touch roll 6 is provided that clamps the molten film on the upper surface of the first cooling roll 5 in order to correct the flatness. The touch roll 6 has an elastic surface and forms a nip with the first cooling roll 5.
Further, the unstretched film 10 peeled off by the peeling roll 9 and cooled and solidified is guided to a stretching apparatus 12 through a dancer roll (film tension adjusting roll) 11. In the stretcher 12, the molecules in the film are oriented by gripping both ends of the film and stretching in the width direction. After stretching, after slitting the end of the film to a product width with a slitter 13, the film is subjected to knurling (embossing) consisting of an embossing ring 14 and a back roll 15 at both ends of the film. 16 is wound up. By taking up with the take-up device 16, it is possible to prevent the occurrence of peeling and scratches in the cellulose ester film (original winding).
The knurling method can process a metal ring having an uneven pattern on its side surface by heating or pressurizing.
In addition, since the grip part of the clip of both ends of a film is deform | transforming normally and cannot be used as a film product, it is cut out and reused as a return material.

Hereinafter, the melt casting method will be described in detail.
<Melted pellet manufacturing process>
The mixture of cellulose ester, plasticizer and other additives used for melt extrusion is usually preferably kneaded in advance and pelletized.
Pelletization may be performed by a known method. For example, a polymer, a plasticizer, and other additives that form a dry optical film are fed to an extruder with a feeder and kneaded using a single or twin screw extruder. Can be extruded into strands, cooled with water or air, and cut.
It is important to dry the raw material before extruding to prevent decomposition of the raw material. In particular, since the polymer forming the optical film is likely to absorb moisture, it is preferably dried at 70 to 140 ° C. for 1 hour or longer with a dehumidifying hot air drier or vacuum drier so that the moisture content is 500 ppm or less, and further 100 ppm or less.
The additives may be mixed before being supplied to the extruder, or may be supplied by individual feeders. A small amount of an additive such as an antioxidant is preferably mixed in advance in order to mix uniformly.
Mixing of the antioxidants may be performed by mixing solids, and if necessary, the antioxidant may be dissolved in a solvent and impregnated with a polymer forming an optical film, or may be mixed or sprayed. May be mixed.
A vacuum nauter mixer or the like is preferable because drying and mixing can be performed simultaneously. Moreover, when contacting with air, such as an exit from a feeder part or die, it is preferable that the atmosphere be dehumidified air or dehumidified nitrogen gas.
The extruder is preferably processed at as low a temperature as possible so that the shearing force is suppressed and the resin can be pelletized so as not to deteriorate (molecular weight reduction, coloring, gel formation, etc.). For example, in the case of a twin screw extruder, it is preferable to rotate in the same direction using a deep groove type screw. From the uniformity of kneading, the meshing type is preferable.
A film is formed using the pellets obtained as described above. It is also possible to feed the raw material powder directly to the extruder with a feeder and form a film as it is without pelletization.

<Pellet drying process>
A gel is formed in the molten mixture by pre-drying (hereinafter referred to as mild drying) the above-prepared pellets before feeding into a hopper of an extruder used in an extrusion process described later. The drying temperature of the hopper to be dried in advance is 70 to 95 ° C., and the drying time is 4 to 6 hours. The reason why the drying temperature is set to 70 to 95 ° C. is that when the drying temperature is set to a high temperature exceeding 95 ° C., the number of nuclei tends to increase during extrusion. The reason why the drying time is set to 4 to 6 hours is that the gel grows and becomes large when the drying time is longer than 6 hours.

In addition, as described above, only new pellets may be dried, and a cellulose ester film may be produced using this as a raw material. However, the return material discharged in the production process (for example, excision at the grip portions of the clips at both ends of the film) Part) may be used together with new pellets.
In this case, the recycled material is more than 0% and preferably 80% or less, particularly preferably 5% or more and 50% or less, and more preferably 10% or more and 30% or less with respect to the new pellets. Is preferred. That is, the number of gel fillers can be appropriately generated by setting the mixing ratio of the new pellets and the recycled material to 90:10 to 70:30.
Further, it is preferable that the returned material is dried at 100 ° C. for 1 to 3 hours, and the new pellets are dried at 85 ° C. for 3 hours. The reason why the drying temperature of the recycled material is higher than that of mild drying is that the moisture content of the recycled material after drying is 30 to 150 ppm and the number of new pellets is 150 to 500 ppm. This is because the mat effect can be exhibited. Further, since the returned material already contains the core of the gel filler, the gel filler is appropriately generated even if the drying time is shortened.

<Process for extruding molten mixture from die to cooling roll>
As described above, the melt mixture containing the gel filler is extruded using a single-screw or twin-screw type extruder, the melt temperature Tm when extruding is about 200 to 300 ° C. The film is cast from a die into a film, solidified on a cooling roll, and cast while pressing with an elastic touch roll.
When introducing from the supply hopper to the extruder, it is preferable to prevent oxidative decomposition or the like under vacuum or reduced pressure or in an inert gas atmosphere. Tm is the temperature of the die exit portion of the extruder.
When foreign matter such as scratches or plasticizer aggregates adheres to the die, streak-like defects may occur. Such defects are also referred to as die lines, but in order to reduce surface defects such as die lines, it is preferable to have a structure in which the resin retention portion is minimized in the piping from the extruder to the die. . It is preferable to use a die that has as few scratches as possible inside the lip.
The inner surface that contacts the molten resin such as an extruder or a die is preferably subjected to surface treatment that makes it difficult for the molten resin to adhere to the surface by reducing the surface roughness or using a material having a low surface energy. Specifically, a hard chrome plated or ceramic sprayed material is polished so that the surface roughness is 0.2 S or less.
There is no particular limitation on the cooling roll, but it is a roll having a structure in which a heat medium or a cooling medium whose temperature can be controlled flows with a high-rigidity metal roll, the size of which is not limited, but a melt-extruded film The diameter of the cooling roll is usually about 100 mm to 1 m.
Examples of the surface material of the cooling roll include carbon steel, stainless steel, aluminum, and titanium. Further, in order to increase the surface hardness or improve the releasability from the resin, it is preferable to perform a surface treatment such as hard chrome plating, nickel plating, amorphous chrome plating, ceramic spraying, or the like.
The surface roughness of the chill roll surface is preferably 0.1 μm or less in terms of Ra, and more preferably 0.05 μm or less. The smoother the roll surface, the smoother the surface of the resulting film. Of course, it is preferable that the surface processed is further polished to have the above-described surface roughness.
Examples of the elastic touch roll include JP 03-124425, JP 08-224772, JP 07-1000096, JP 10-272676, WO 97-028950, JP 11-235747, JP 2002-36332. No. 2005-172940 and JP-A 2005-280217 can use a thin-film metal sleeve-coated silicon rubber roll.
When peeling the film from the cooling roll, it is preferable to control the tension to prevent deformation of the film.

<Extension process>
In the present invention, it is preferable that the film obtained as described above is further stretched 1.01 to 3.0 times in at least one direction after passing through the step of contacting the cooling roll. The sharpness of the streaks becomes gentle by stretching and can be highly corrected.
Preferably, the film is stretched 1.1 to 2.0 times in both the longitudinal (film transport direction) and lateral (width direction) directions.
As a method of stretching, a known roll stretching machine or tenter can be preferably used. In particular, in the case where the optical film is a retardation film that also serves as a polarizing plate protective film, it is preferable to stack the polarizing film in a roll form by setting the stretching direction to the width direction.
By stretching in the width direction, the slow axis of the optical film becomes the width direction. On the other hand, the transmission axis of the polarizing film is also usually in the width direction. A good viewing angle can be obtained by incorporating in a liquid crystal display device a polarizing plate laminated so that the transmission axis of the polarizing film and the slow axis of the polarizing plate protective film are parallel to each other.

When the cellulose ester film of the present invention is used as a film having an optical compensation function, the temperature and magnification can be selected so that desired retardation characteristics can be obtained.
Usually, the draw ratio is 1.1 to 3.0 times, preferably 1.3 to 2.0 times, and the draw temperature is usually Tg to Tg + 50 ° C. of the resin constituting the film, preferably Tg to Tg + 40 ° C. In the temperature range.
The stretching is preferably performed under a uniform temperature distribution controlled in the width direction. The temperature is preferably within ± 2 ° C, more preferably within ± 1 ° C, and particularly preferably within ± 0.5 ° C.

For the purpose of adjusting the retardation of the cellulose ester film produced by the above method and reducing the dimensional change rate, the film may be contracted in the longitudinal direction or the width direction.
In order to shrink in the longitudinal direction, for example, there is a method of contracting the film by temporarily clipping out the width stretching and relaxing in the longitudinal direction, or by gradually narrowing the interval between adjacent clips of the transverse stretching machine.
The in-plane retardation (Ro) and thickness direction retardation (Rt) of the cellulose ester film of the present invention can be adjusted as appropriate, but Ro is preferably 0 to 200 nm and Rt is preferably −150 to 400 nm.

In addition, when the refractive index Nx in the slow axis direction of the film, the refractive index Ny in the fast axis direction, the refractive index Nz in the thickness direction, and the film thickness of the film are d (nm),
Ro = (Nx−Ny) × d
Rt = {(Nx + Ny) / 2−Nz} × d
Represented as: (Measurement wavelength 590nm)
The variation in retardation is preferably as small as possible, and is usually within ± 10 nm, preferably ± 5 nm or less, and more preferably ± 2 nm or less.
The uniformity in the slow axis direction is also important, and the angle is preferably −5 to + 5 ° with respect to the film width direction, more preferably in the range of −1 to + 1 °, and particularly −0. It is preferably in the range of 5 to + 0.5 °, particularly preferably in the range of −0.1 to + 0.1 °. These variations can be achieved by optimizing the stretching conditions.

In the cellulose ester film of the present invention, it is preferable that the height from the top of the adjacent mountain to the bottom of the valley is 300 nm or more, and there is no streak continuous in the longitudinal direction with an inclination of 300 nm / mm or more.
The shape of the streak was measured using a surface roughness meter, and specifically, Mitutoyo SV-3
Using 100S4, scanning in the width direction of the film at a measurement speed of 1.0 mm / sec while applying a load of 0.75 mN to a stylus (diamond needle) with a tip of 60 ° cone and a radius of curvature of 2 μm. Then, the cross-sectional curve is measured with a Z-axis (thickness direction) resolution of 0.001 μm.
From this curve, the streak height reads the vertical distance (H) from the top of the mountain to the bottom of the valley. The slope of the streak is obtained by reading the horizontal distance (L) from the top of the mountain to the bottom of the valley and dividing the vertical distance (H) by the horizontal distance (L).
After stretching, the stretched film is wound up by a winder.

<Cleaning equipment>
It is preferable to add a device for automatically cleaning the belt and the roll to the manufacturing apparatus used in the present invention. There are no particular restrictions on the cleaning device. For example, there are a method of niping a brush roll, a water absorbing roll, an adhesive roll, a wiping roll, an air blow method of blowing clean air, a laser incinerator, or a combination thereof. is there.
In the case where the cleaning roll is nipped, the cleaning effect is great if the belt linear velocity and the roller linear velocity are changed.

<< Use of cellulose ester film >>
The cellulose ester film of the present invention can be used as a functional film used in various displays such as a liquid crystal display, a plasma display, and an organic EL display, in particular, a liquid crystal display. It can be used for optical compensation films such as phase difference films, antireflection films, brightness enhancement films, and viewing angle expansions.

When used as a polarizing plate protective film, the polarizer has a structure in which both sides of the polarizer are sandwiched between the cellulose ester films of the present invention. A polarizing plate having such a structure can be produced by a general method. The cellulose ester film of the present invention is preferably subjected to alkali saponification treatment, and the treated film is bonded to at least one surface of a polarizer prepared by immersing and stretching in an iodine solution using a completely saponified polyvinyl alcohol aqueous solution. .
The polarizer of the present invention is a polyvinyl alcohol-based polarizer, which is one in which a polyvinyl alcohol-based film is dyed with iodine or one in which a dichroic dye is dyed. For the polarizer, a polyvinyl alcohol aqueous solution is formed into a film and dyed by uniaxial stretching or dyed or uniaxially stretched and then preferably subjected to a durability treatment with a boron compound. On the surface of the polarizer, one side of the cellulose ester film of the present invention is bonded to form a polarizing plate. It is preferably bonded with an aqueous adhesive mainly composed of completely saponified polyvinyl alcohol or the like.
Since the long cellulose ester film manufactured by the manufacturing method of the present invention can be bonded to a long polarizer (polarizing film) by alkali saponification treatment, 1500 m, 2500 m, 5000 m and more. The longer the length, the more productive effect of manufacturing the polarizing plate.

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

<Liquid crystal display device>
The polarizing plate is used for MVA (Multi-domain Vertical Alignment) mode, PVA (Patterned Vertical Alignment) mode, OCB (Optical Compensated InP mode), OCB (Optical Compensated InP mode), OCB (Optical Compensated InP mode). be able to.
The liquid crystal display device is applied as a device for colorization and moving image display, and the display quality is improved by the present invention, and the contrast is improved and the resistance of the polarizing plate is improved. .

EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto.
[Example 1]
<< Production of cellulose ester film >>
(1) Sample 1
First, pellets for melt casting film formation were prepared using the following cellulose ester and various additive compositions.
<Molten resin composition>
Cellulose acetate propionate (acetyl group substitution degree 1.41, propionyl group substitution degree 1.32, total substitution degree 2.73, Mn = 86,000, Mw / Mn = 2.5)
92 parts by weight pentaerythritol tribenzoate 8 parts by weight Irganox 1010 (manufactured by Ciba Specialty Chemicals) 0.5 parts by weight ADK STAB PEP-36 (ADEKA) 0.3 parts by weight Smither-GS (manufactured by Sumitomo Chemical) 0.3 parts by weight Part Tinuvin-928 (manufactured by Ciba Specialty Chemicals) 2 parts by mass The cellulose ester was dried under reduced pressure at 70 ° C. for 3 hours and cooled to room temperature, and then the additives were mixed.
The above mixture was melt-mixed at 230 ° C. using a twin-screw extruder and pelletized. In addition, the glass transition temperature Tg of this pellet was 136 degreeC.
Next, a cellulose ester film (sample 1) was produced by the following method using the production apparatus shown in FIG.

First, the prepared pellets were dried according to the drying temperature and drying time shown in Table 1 to form a gel filler, and further, melted at 250 ° C. under a nitrogen atmosphere, and then filtered through the gear pump through the gear pump. The film was extruded from the casting die 4 onto the first cooling roll 5, and the film was sandwiched between the first cooling roll 5 and the touch roll 6 to form.
The heat bolt was adjusted so that the gap width of the casting die 4 was 0.5 mm within 30 mm from the end in the width direction of the film and 1 mm at other locations.
The touch roll 6 was controlled at 100 to 130 ° C. by pouring oil inside.
From the position P1 at which the resin extruded from the casting die 4 contacts the first cooling roll 5 to the position P2 at the upstream end in the rotation direction of the first cooling roll 5 in the nip between the first cooling roll 5 and the touch roll 6. 1 The length L along the peripheral surface of the cooling roller 5 was set to 20 mm.
Thereafter, the touch roll 6 is separated from the first cooling roll 5, and the temperature T of the melted part immediately before being sandwiched between the first cooling roll 5 and the touch roll 6 is measured. As a result, the temperature T is 141 ° C. Met.
In addition, the temperature T of the melted part immediately before being squeezed by the nip between the first cooling roll 5 and the touch roll 6 is a thermometer (Anritsu Meter Co., Ltd.) at a position further 1 mm upstream from the nip upstream end P2. (Measured by HA-200E).
The linear pressure of the touch roll 6 against the first cooling roll 5 was 14.7 N / cm.
This film was hot-stretched in the longitudinal direction using the difference in roll peripheral speed. Heating was performed with an infrared heater, and the draw ratio was 1.5 times. Furthermore, after being introduced into a tenter and stretched 1.6 times at 160 ° C in the width direction, it was cooled to 30 ° C while relaxing 3% in the width direction, and then released from the clip. Was subjected to a knurling process with a width of 10 mm and a height of 5 μm, and wound on a winding core with a winding tension of 220 N / m and a taper of 40%.
The extrusion amount and take-up speed were adjusted so that the film had a thickness of 80 μm, and the finished film width was slit and wound up so that the width of the finished film was 1500 mm.
The winding core had an inner diameter of 152 mm, an outer diameter of 165 to 180 mm, and a length of 1550 mm.
A prepreg resin obtained by impregnating glass fibers and carbon fibers with an epoxy resin was used as the core material for the core. The surface of the core was coated with an epoxy conductive resin, the surface was polished, and the surface roughness Ra was finished to 0.3 μm. The winding length was 2500 m.

(2) Sample 2 to Sample 12
Cellulose ester films (Sample 2 to Sample 12) were obtained in the same manner as Sample 1 cellulose ester film except that the substitution degree of cellulose ester, drying temperature, drying time and the like were changed as shown in Table 1.

(3) Sample 13
<Synthesis of modified cellulose ester>
70 parts of cellulose acetate (L-20, acyl group substitution degree 2.417, propionyl substitution degree 0.9) manufactured by Daicel Chemical Industries, Ltd. was added to the reactor and dried under reduced pressure at 110 ° C. for 4 hours at 4 Torr. Thereafter, purging was performed with dry nitrogen, a reflux condenser was attached, 30 parts of ε-caprolactone and 67 parts of cyclohexanone that had been dried and distilled in advance were added, and the mixture was heated to 160 ° C. and stirred to dissolve cellulose acetate uniformly. To this reaction solution, 0.25 part of monobutyltin trioctylate was added and heated at 160 ° C. with stirring for 2 hours. Thereafter, the reaction solution was cooled to room temperature to terminate the reaction and obtain a reaction product. Furthermore, 10 parts of the reaction product was dissolved in 90 parts of chloroform, and then slowly dropped into 900 parts of a large excess of methanol, and the precipitated precipitate was filtered to remove the homopolymer of ε-caprolactone. . Furthermore, it heat-dried at 60 degreeC for 5 hours or more, and obtained the cellulose ester 1 which (epsilon) -caprolactone reacted with the cellulose acetate. And the primary structure of the cellulose ester obtained by 1H-NMR was analyzed. As a result, the average number of moles of ε-caprolactone reacted per mole of glucose unit was 0.86, the average degree of substitution was 0.12, and the average degree of polymerization was 7.4.

Subsequently, pellets for melt casting film formation were prepared using the composition of the modified cellulose ester, the following cellulose ester, and various additives.
<Molten resin composition>
Cellulose acetate propionate (acetyl group substitution degree 1.6, propionyl group substitution degree 1.2, Mn = 86,000, Mw / Mn = 2.5) 87 parts by weight Modified cellulose ester prepared as above 5 parts by weight Pentaeryth Llutol tribenzoate 8 mass Irganox 1010 (manufactured by Ciba Specialty Chemicals) 0.5 mass part ADK STAB PEP-36 (ADEKA) 0.3 mass part Smilizer-GS (manufactured by Sumitomo Chemical) 0.3 mass part Tinuvin-928 ( Ciba Specialty Chemicals) 2 parts by weight In the same manner as in Sample 1 above, the cellulose ester and the modified cellulose ester were dried at 70 ° C. under reduced pressure for 3 hours and cooled to room temperature, and then the additives were mixed.
The above mixture was melt-mixed at 230 ° C. using a twin-screw extruder and pelletized. In addition, the glass transition temperature Tg of this pellet was 136 degreeC.
Then, according to the drying temperature and drying time of Table 1, the cellulose-ester film (sample 13) was produced by the method similar to the said sample 1.

(4) Sample 14 to Sample 16
Cellulose ester films (samples 14 to 16) were produced by a conventional solution casting method instead of the melt casting method. The composition of the sample was the same as that of Sample 1 except that the substitution degree of cellulose ester was changed as shown in Table 1.
Specifically, a cellulose ester film dope was prepared by mixing various additives such as cellulose ester, plasticizer, and solvent in a melting pot. Further, the dope of the cellulose ester film was cast on a support by a casting die of a solution casting film forming apparatus (casting process), and heated to remove a part of the solvent (drying process on the support). Then, it peeled from the support body and the peeled film was dried (film drying process), and the cellulose-ester film was obtained.

In Sample 15, 0.5 part by mass of silica-based Seahoster KE-P30 (Nippon Catalyst Co., Ltd.) was added as a particulate material (mat agent) to the pellet material. In sample 16, the same modified cellulose ester as in sample 13 was used.

(5) Sample 17 to Sample 19
In Samples 17 to 19, 0.5 parts by mass of silica-based Seahoster KE-P30 (Nippon Shokubai Co., Ltd.) as a matting agent for the pellet material, acrylic fine sphere MG-151 (Nippon Paint Co., Ltd.) A cellulose ester film was produced in the same manner as in Sample 1 except that 0.5 part by mass was added.

<Evaluation>
The obtained cellulose ester films (Sample 1 to Sample 19) were evaluated for the following items.
<Gel filler count>
A sample of cellulose ester film is dissolved in tetrahydrofuran to make a 5 wt% solution. Therefore, it is allowed to stand for about 20 hours and the normal film portion is naturally dissolved.
Since the foreign matter is difficult to dissolve, the gel-like core remains, so the size and number of the solution are counted with a Beckman Coulter Coulter Counter (Z Series, Multisizer 3). When particles as large as the gel are added, the foreign material (particles) is made into a solution as described above only with the material before the film is formed (there is no heat history that the gel is generated in the extruder). Counted the number at the Coulter Counter.
Thereafter, the number of gel fillers is determined by subtracting the foreign substances (particles) measured in advance from the number of gel fillers and foreign substances (particles) in the film. Table 1 shows the number of gel fillers of 0.5 to 30 μm / g and the number of gel fillers of 50 μm / 10 g or more. In addition, the magnitude | size of the gel filler was taken as the diameter (micrometer) at the time of converting the projection area of each filler into the circle of the same area.

<blocking>
Each of the cellulose ester films (Sample 1 to Sample 19) prepared as described above is wound up by 2600 m, and visually evaluated whether there is any deformation of winding from the wound state.
○: No winding deformation ○ △: Almost no deformation of winding Δ: Winding is slightly deformed Δ ×: Deformation of winding is clearly seen ×: Large deformation is seen in winding Table 1 shows visual evaluation The result was shown.

<Slipperiness>
The slip property was evaluated by the value of the dynamic friction coefficient.
The dynamic friction coefficient of each sample stored for 24 hours or more in an atmosphere of 23 ° C. and 55% RH was measured in accordance with the method described in JIS-K-7125-ISO8295 in the same atmosphere.
Cut each film so that the front and back surfaces come into contact with each other, place a 200-g weight, pull the weight horizontally under the conditions of a moving speed of the film sample of 100 mm / min and a contact area of 80 mm × 200 mm, and the average load (F ) And the dynamic friction coefficient (μ) was determined from the following formula.
Coefficient of dynamic friction (μ) = F (g) / Weight of weight (g)
Passing line of dynamic friction coefficient (μ): μ ≦ 1.2

<Front contrast>
(A) Preparation of polarizing plate A polyvinyl alcohol film having a thickness of 120 μm was uniaxially stretched (temperature: 110 ° C., stretch ratio: 5 times). This was immersed in an aqueous solution composed of 0.075 g of iodine, 5 g of potassium iodide and 100 g of water for 60 seconds, and then immersed in an aqueous solution of 68 ° C. composed of 6 g of potassium iodide, 7.5 g of boric acid and 100 g of water. This was washed with water and dried to obtain a polarizer.
Next, a polarizer, the produced cellulose ester film (Sample 1 to Sample 19) according to the following steps 1 to 5, and Konica Minolta Tack KC4UY (Konica Minolta Opto's cellulose ester film) on the back side are optical compensation films. As a result, a polarizing plate was prepared.
Step 1: Soaked in a 2 mol / L sodium hydroxide solution at 60 ° C. for 90 seconds, then washed with water and dried to obtain a saponified cellulose ester film on the side to be bonded to the polarizer.
Process 2: The said polarizer was immersed in the polyvinyl alcohol adhesive tank of 2 mass% of solid content for 1-2 seconds.
Step 3: Excess adhesive adhered to the polarizer in Step 2 was lightly wiped off, and this was placed on the cellulose ester film treated in Step 1.
Process 4: The cellulose ester film laminated | stacked at the process 3, the polarizer, and the back side cellulose-ester film were bonded by the pressure of 20-30 N / cm <2>, and the conveyance speed about 2 m / min.
Step 5: A sample obtained by bonding the polarizer, the cellulose ester film, and Konica Minoltack KC4UY prepared in Step 4 in a dryer at 80 ° C. was dried for 2 minutes to prepare polarizing plates (Sample 1 to Sample 19). .

(B) Production of liquid crystal display device A liquid crystal panel for measuring the viewing angle was produced as follows, and the characteristics as a liquid crystal display device were evaluated. The polarizing plates on both sides of the SONY 40-type display KLV-40V2500 previously bonded were peeled off, and the prepared polarizing plates (sample 1 to sample 19) were respectively bonded to both surfaces of the glass surface of the liquid crystal cell. At that time, the direction of bonding of the polarizing plate is such that the surface of the cellulose ester film of the present invention is on the liquid crystal cell side, and the absorption axis is in the same direction as the polarizing plate previously bonded. Thus, liquid crystal display devices (Sample 1 to Sample 19) were produced.
The liquid crystal display device was evaluated for color variation and front contrast.

(C) Front contrast In the environment of 23 ° C. and 55% RH, the backlight of each liquid crystal display device was lit continuously for one week, and then measurement was performed. For measurement, EZ-Contrast 160D manufactured by ELDIM was used to measure the luminance from the normal direction of the display screen of white display and black display with a liquid crystal display device, and the ratio was defined as the front contrast.
Front contrast = (brightness of white display measured from normal direction of display device) / (brightness of black display measured from normal direction of display device)

<productivity>
When the filter in the extrusion process is clogged, the filter outlet pressure increases. When the pressure rises from the pressure at a constant flow rate, the fluctuation from the target film thickness is so large that it cannot be realized as a product, so the filter needs to be replaced. Since the film forming line is stopped at the time of replacement, the time required for the replacement and the time required for the film thickness fluctuation are lost times.
Therefore, it is preferable that the filter is not exchanged or the film thickness fluctuates as much as possible. The production amount can be increased by reducing time and material loss, and the production cost can be reduced. In this patent, this is referred to as productivity.
Evaluation of productivity 1 Filter replacement frequency and film thickness fluctuation during day and night factory operation: No filter replacement and no film thickness fluctuation at all.
○ △: No filter replacement and film thickness fluctuation hardly occurs.
Δ: Filter is easily changed once and film thickness fluctuation is likely to occur.
Δ ×: The filter is changed twice and the film thickness is likely to change.
X: Filter change occurs three times or more, and the film thickness fluctuates frequently.

以上のように表１の結果から、本発明のセルロースエステルフィルムで作製した偏光板
は滑り性、ブロッキング効果、正面コントラストに優れ、目詰まりが起こりにくく生産性が良好な偏光板であることが明らかである。

As described above, from the results shown in Table 1, it is clear that the polarizing plate produced from the cellulose ester film of the present invention is excellent in slipperiness, blocking effect and front contrast, and is a polarizing plate having good productivity with less clogging. It is.

[Example 2]
The recycled material was mixed with the new pellets used for the preparation of the cellulose ester film of Sample 1, and cellulose ester films (Sample 21 to Sample 26) were prepared by the same melt casting method as Sample 1. Then, the polarizing plate (Sample 21-Sample 26) was produced similarly to the polarizing plate (Sample 1-Sample 19) of Example 1. The moisture content and mixing ratio of the new pellets and the recycled material are as shown in Table 2.
And it evaluated about each item of the number of gel fillers, slipperiness, blocking, and front contrast like Example 1, and the result was shown in Table 2.

以上のように表２の結果から、返材を混合させた場合の方が返材を使用しない場合に比して、５０μｍ／１０ｇ以上のゲルフィラー数を減少させることができる。

As described above, from the results shown in Table 2, the number of gel fillers of 50 μm / 10 g or more can be reduced when the return material is mixed as compared with the case where the return material is not used.

DESCRIPTION OF SYMBOLS 1 Extruder 2 Filtration apparatus 3 Static mixer 4 Casting die 5 1st cooling roll 6 Touch roll 7 2nd cooling roll 8 3rd cooling roll 9 Peeling roll 10 Unstretched film 11 Dancer roll 12 Stretching apparatus 13 Slitter 14 Embossing ring 15 Back roll 16 Winding device

Claims (4)

A cellulose ester film formed by a melt casting method,
Cellulose characterized in that the cellulose ester film has 50 to 500 gel fillers having a size of 0.5 to 30 μm and 0 to 2/10 g gel fillers having a size of 50 μm or more. Ester film. Method for producing cellulose ester film having 50 to 500 gel fillers having a size of 0.5 to 30 μm and 0 to 2/10 gel fillers having a size of 50 μm or more in the cellulose ester film Because
Drying the pellets containing cellulose ester at 70 to 95 ° C. for 4 to 6 hours;
And a step of forming a film of the dried pellet by a melt casting method.   The method for producing a cellulose ester film according to claim 2, wherein a part of another cellulose ester film is mixed into the pellet as a recycled material. The mixing ratio of the pellets and the returned material is 90:10 to 70:30,
The method for producing a cellulose ester film according to claim 3, wherein the moisture content of the recycled material is less than the moisture content of the pellets.

Images