WO2012035838A1

WO2012035838A1 - Cellulose ester film, production method therefor, polarizing plate provided therewith, and liquid crystal display

Info

Publication number: WO2012035838A1
Application number: PCT/JP2011/064004
Authority: WO
Inventors: 美典玉川
Original assignee: コニカミノルタオプト株式会社
Priority date: 2010-09-15
Filing date: 2011-06-20
Publication date: 2012-03-22
Also published as: JPWO2012035838A1

Abstract

Provided are a cellulose ester film with high transmittance, and a production method therefor. Further, provided are a polarizing plate provided with the cellulose ester film, and a liquid crystal display with high contrast. This cellulose ester film contains a cellulose ester including an acyl group having 2 to 4 carbon atoms, and the substitution degree of the acyl group is 2.0 to 2.5. The cellulose ester film is characterized in that the number of foreign bodies having a diameter translated into circle in the range of 60 to 100 μ is 10 pieces or less per 10 cm², the number of foreign bodies having a diameter translated into circle in the range of 10 to 50 μ is 10 pieces or less per 10 cm², the internal haze is 0.1 or less, and the thickness is in the range of 20 to 50 μm.

Description

Cellulose ester film, method for producing the same, polarizing plate provided with the same, and liquid crystal display device

The present invention relates to a cellulose ester film, a method for producing the same, a polarizing plate provided with the cellulose ester film, and a liquid crystal display device. More specifically, the present invention relates to a cellulose ester film having a high transmittance, a production method thereof, a polarizing plate provided with the cellulose ester film, and a liquid crystal display device having a high contrast.

Demand for liquid crystal display devices is expanding for applications such as liquid crystal televisions and personal computer liquid crystal displays. Usually, a liquid crystal display device is composed of a liquid crystal cell in which a transparent electrode, a liquid crystal layer, a color filter, etc. are sandwiched between glass plates, and two polarizing plates provided on both sides thereof. The child is sandwiched between two optical films. A cellulose ester film is usually used for this optical film.

This optical film for liquid crystal display devices is increasing in production year by year due to the increase in size and spread of liquid crystal display devices. In order to cope with this, the film width is increased, the film length is increased, and the film forming process associated therewith is increased. Speeding up is being studied.

Also, due to recent technological advancement, liquid crystal display devices have been increased in size and functionality, and there has been a demand for improved contrast.

However, when the cellulose ester film is formed, unacetylated material that is insufficiently esterified becomes insoluble, and the refractive index of the foreign matter is different from the refractive index of the main cellulose ester, thereby inhibiting the polarization state, It was a defect that caused abnormal light emission.

Patent Document 1 describes a method of degassing cellulose ester dope under reduced pressure and improving the transparency of the film by using a filter aid, but filtration with a small particle size in the dope after filtration. It was found that the film remained cloudy because the auxiliary agent remained, and it did not directly lead to improvement in contrast.

On the other hand, Patent Document 2 describes a method of installing a filter so that the filter aid is not mixed into the dope after filtration. However, cellulose triacetate (TAC) having a high degree of substitution is sufficient. However, diacetylcellulose (DAC), cellulose acetate propionate (CAP), and the like having a low degree of substitution are required to be further improved because the amount of non-acetylated product increases. It has also been found that the filter aid is clogged with the filter, resulting in a decrease in filtration efficiency and no improvement in productivity.

JP 2007-69420 A JP 2004-107629 A

The present invention has been made in view of the above-described problems and situations, and a solution to that problem is to provide a cellulose ester film having a high transmittance and a method for producing the same. Another object of the present invention is to provide a polarizing plate provided with the cellulose ester film and a liquid crystal display device with high contrast.

The above-mentioned problem according to the present invention is solved by the following means.

1. A cellulose ester film containing a cellulose ester having an acyl group having a carbon number in the range of 2 to 4 and an acyl group substitution degree in the range of 2.0 to 2.5, and having a diameter in terms of a circle Is 10 or less per 10 cm square, and 10 or less foreign matter is 10 to 50 μm in diameter, and the internal haze is 0.1 or less. And a cellulose ester film having a thickness in the range of 20 to 50 μm.

2. The said 1st item | term characterized by being the cellulose ester film by which the core layer containing the cellulose ester which satisfy | fills following formula (1), and the skin B layer containing the cellulose ester which satisfy | fills following formula (2) were laminated | stacked and formed. The cellulose ester film described in 1.
Formula (1): 2.0 <Z ₁ <2.5
(In the formula (1), Z ₁ represents a total acyl group substitution degree of the cellulose ester of the core layer.)
Formula (2): 2.7 <Z ₂ <3.0
(In the formula (2), Z ₂ represents a total acyl group substitution degree of the cellulose ester of the skin layer.)
3. The said 1st item | term characterized by having the skin A layer containing the cellulose ester which satisfy | fills following formula (2) on the surface on the opposite side to the surface with the skin B layer of the said laminated | stacked core layer. Or the cellulose-ester film of a 2nd term | claim.
Formula (2): 2.7 <Z ₂ <3.0
(In the formula (2), Z ₂ represents a total degree of acyl substitution of the cellulose ester of the skin layer.)
4). The length of the film is in the range of 5000 to 10,000 m, and the width of the film is in the range of 1.9 to 2.5 m. The cellulose ester film of item.

5. Filtering using a filter aid having an average particle size in the range of 5 to 20 μm, a particle size standard deviation of 0.5 times or less of the average particle size, and a filter having a filtration accuracy in the range of 1 to 5 μm The cellulose ester film according to any one of Items 1 to 4, wherein the cellulose ester film is produced through the process.

6. A method for producing a cellulose ester film according to any one of items 1 to 5, wherein the average particle size is in the range of 5 to 20 μm, and the standard deviation of particle size A method for producing a cellulose ester film, comprising a step of filtering using a filter aid having a mean particle size of 0.5 times or less and a filter having a filtration accuracy in the range of 1 to 5 μm.

7. A polarizing plate comprising the cellulose ester film according to any one of items 1 to 5 above.

8. A liquid crystal display device comprising the cellulose ester film according to any one of items 1 to 5.

The above-described means of the present invention can provide a cellulose ester film having a high transmittance and a method for producing the same. In addition, a polarizing plate provided with the cellulose ester film and a liquid crystal display device with high contrast can be provided.

Co-casting die and a diagram showing a multi-layered web formed by casting

The cellulose ester film of the present invention contains a cellulose ester having an acyl group having a carbon number in the range of 2 to 4 and an acyl group substitution degree in the range of 2.0 to 2.5. The number of foreign matters having a circle-equivalent diameter in the range of 60 to 100 μm is 10 or less per 10 cm square, and the number of foreign matters having a circle-equivalent diameter in the range of 10 to 50 μm is 10 or less per 10 cm square. The internal haze is 0.1 or less and the thickness is in the range of 20 to 50 μm. This feature is a technical feature common to the inventions according to claims 1 to 8.

As an embodiment of the present invention, a skin B layer containing a cellulose ester satisfying the above formula (2) is laminated as a core layer containing a cellulose ester satisfying the above formula (1) from the viewpoint of the effect of the present invention. The film is preferably a formed cellulose ester film. Furthermore, it is preferable to have the skin A layer containing the cellulose ester which satisfy | fills said Formula (2) on the surface on the opposite side to the surface with the skin B layer of the core layer formed by said lamination | stacking.

In the present invention, the length of the film is preferably in the range of 5000 to 10000 m, and the width of the film is preferably in the range of 1.9 to 2.5 m. Further, filtration is performed using a filter aid having an average particle size in the range of 5 to 20 μm, a particle size standard deviation of 0.5 times or less of the average particle size, and a filter having a filtration accuracy in the range of 1 to 5 μm. It is preferable that it is manufactured through the process of performing.

Therefore, as a method for producing a cellulose ester film of the present invention, a filter aid having an average particle diameter in the range of 5 to 20 μm and a particle diameter standard deviation of 0.5 times or less of the average particle diameter is used. It is preferable that the production method has an aspect including a step of filtering using an agent and a filter having a filtration accuracy within the range of 1 to 5 μm.

In addition, in this application, a "core layer" means the layer which exists in the inside among the laminated | stacked layers, when a cellulose ester film is comprised by the layer laminated | stacked three or more layers. The layer thickness is preferably thicker than the skin layer on the outside. When the cellulose ester film has a two-layer structure, the thickest layer is referred to as a “core layer”.

On the other hand, the “skin layer” refers to a layer on the outer surface side of the laminated layers when the cellulose ester film is composed of three or more layers. The layer thickness is preferably thinner than the core layer on the inner side.

In the present application, the term “skin layer” refers to both “skin A layer” and “skin B layer”. However, the “skin A layer” may be referred to as an “air surface layer”, and the “skin B layer” may be referred to as a “support surface layer”. Furthermore, the “core layer” may be referred to as a “base layer”.

Further, in the present invention, the film sample is observed with an optical microscope at a magnification of 150 times, and the number of bright spot foreign matters within the range of a circle converted diameter of 60 to 100 μm and a circle converted diameter of 10 to 50 μm within 100 mm ² is counted. Was the number of foreign objects on the film. Here, “bright spot foreign matter” means a spot formed by light transmitted through the polarizing plate when two polarizing plates are arranged on both sides of the cellulose ester film so as to block the transmitted light. In general, the polarizing action does not function sufficiently due to the presence of foreign matter in the film. The number of the bright spot foreign matters can be measured with an optical microscope.

Further, the “circle converted diameter” means a diameter obtained by converting the projected area of the bright spot foreign matter observed with an optical microscope as the area of the circle.

In addition, “filter aid having a particle size standard deviation of 0.5 times or less of the average particle size” means a filter aid having a standard deviation of particle size of the average particle size × 0.5 or less. The smaller the standard deviation, the smaller the variation in the particle size of the filter aid, so that it is difficult for the film to become cloudy or to reduce the filtration efficiency.

Hereinafter, the present invention, its components, and modes and modes for carrying out the present invention will be described in detail. In the present application, “˜” is used to mean that the numerical values described before and after it are included as a lower limit value and an upper limit value.

(Cellulose ester film)
The cellulose ester film of the present invention contains a cellulose ester having an acyl group having a carbon number in the range of 2 to 4 and an acyl group substitution degree in the range of 2.0 to 2.5. The film has 10 or less foreign matter with a circle converted diameter of 60 to 100μ per 10 cm square, and 10 or less foreign materials with a circle converted diameter of 10 to 50μ per 10 cm square. The haze is 0.1 or less and the thickness is in the range of 20 to 50 μm.

As an embodiment of the present invention, a core layer containing a cellulose ester satisfying the following formula (1) and a skin B layer containing a cellulose ester satisfying the following formula (2) are laminated from the viewpoint of manifesting the effects of the present invention. It is preferable that it is a film-formed cellulose ester film.

Formula (1): 2.0 <Z ₁ <2.5
(In the formula (1), Z ₁ represents a total acyl group substitution degree of the cellulose ester of the core layer.)
Formula (2): 2.7 <Z ₂ <3.0
(In the formula (2), Z ₂ represents a total acyl group substitution degree of the cellulose ester of the skin layer.)
In the present invention, a skin A layer containing a cellulose ester satisfying the formula (2) may be further provided on a surface opposite to the surface on which the skin B layer of the core layer formed by lamination is provided. From the viewpoint of suitably controlling the physical properties (curl) of the film.

In addition, it is also a preferable aspect to add a retardation adjusting agent to at least one of the core layer or the skin layer and stretch it, and the co-casting causes technically inevitable partial variations in the thickness of the core layer and the skin layer. Even if it is a case, the influence which the optical characteristic of the whole laminated film receives is suppressed, and the variation of Ro and Rt can be suppressed.

Therefore, compared with the conventional cellulose ester film, the cellulose ester laminated film of the present invention has high expression of optical properties and very little variation in optical properties.

Hereinafter, the features and preferred embodiments of the film of the present invention will be described in detail.

(Cellulose ester)
The cellulose ester film of the present invention contains a cellulose ester having an acyl group having 2 to 4 carbon atoms and an acyl group substitution degree of 2.0 to 2.5. In short, examples of the acyl group having 2 to 4 carbon atoms include an acetyl group, a propionyl group, and a butanoyl group.

The β-1,4-bonded glucose unit constituting cellulose has free hydroxy groups (hydroxyl groups) at the 2nd, 3rd and 6th positions. The cellulose ester is a polymer obtained by acylating part or all of these hydroxy groups (hydroxyl groups) with an acyl group. The total acyl group substitution degree is the ratio in which all of the hydroxy groups (hydroxyl groups) of cellulose located at the 2nd, 3rd and 6th positions are acylated per glucose unit (100% acylation has a degree of substitution of 3). Means.

An embodiment of the present invention is a cellulose ester film in which a core layer containing a cellulose ester satisfying the following formula (1) and a skin B layer containing a cellulose ester satisfying the following formula (2) are laminated and formed. It is preferable that

The Z ₁ preferably satisfies 2.1 ≦ Z ₁ ≦ 2.45.

The Z ₂ preferably satisfies 2.75 ≦ Z ₂ ≦ 2.95, and particularly preferably satisfies 2.80 ≦ Z2 ≦ 2.95.

In the present invention, as long as the above requirements are satisfied, the cellulose ester contained in the skin layer and the core layer can have the following acyl group, and may be an aliphatic group or an aryl group, and is not particularly limited. For example, cellulose alkylcarbonyl ester, alkenylcarbonyl ester, aromatic carbonyl ester, aromatic alkylcarbonyl ester and the like, each of which may further have a substituted group.

Examples of preferred acyl groups include acetyl, propionyl, butanoyl, heptanoyl, hexanoyl, octanoyl, decanoyl, dodecanoyl, tridecanoyl, tetradecanoyl, hexadecanoyl, octadecanoyl, Examples thereof include an isobutanoyl group, a tert-butanoyl group, a cyclohexanecarbonyl group, an oleoyl group, a benzoyl group, a naphthylcarbonyl group, and a cinnamoyl group. Among these, an acetyl group, a propionyl group, a butanoyl group, a dodecanoyl group, an octadecanoyl group, a tert-butanoyl group, an oleoyl group, a benzoyl group, a naphthylcarbonyl group, a cinnamoyl group, and the like are more preferable, and an acetyl group is particularly preferable. A propionyl group and a butanoyl group (when the acyl group has 2 to 4 carbon atoms) are more preferable, and an acetyl group (when the cellulose ester is cellulose acetate) is more preferable.

In the acylation of cellulose, when an acid anhydride or acid chloride is used as an acylating agent, an organic acid such as acetic acid or methylene chloride is used as an organic solvent as a reaction solvent.

As the catalyst, when the acylating agent is an acid anhydride, a protic catalyst such as sulfuric acid is preferably used, and when the acylating agent is an acid chloride (for example, CH ₃ CH ₂ COCl), Basic compounds are used.

The number average molecular weight (Mn) of the cellulose ester used in the present invention is preferably in the range of 30000 to 300000, since the mechanical strength of the resulting film is strong. Further, those having 50000-200000 are preferably used.

The ratio Mw / Mn of the weight average molecular weight (Mw) and the number average molecular weight (Mn) of the cellulose ester is preferably 1.4 to 3.0.

The most common industrial synthesis method of mixed fatty acid esters of cellulose is cellulose mixed organics containing fatty acids corresponding to acetyl groups and other acyl groups (acetic acid, propionic acid, valeric acid, etc.) or acid anhydrides thereof. This is a method of acylating with an acid component.

The cellulose ester used in the present invention can be synthesized, for example, by the method described in JP-A-10-45804.

Commercially available products include L20, L30, L40, and L50 from Daicel Chemical Industries, and Ca398-3, Ca398-6, Ca398-10, Ca398-30, and Ca394-60S from Eastman Chemical.

In the cellulose ester film of the present invention, a retardation adjusting agent (a retardation developing agent and a retardation reducing agent), a plasticizer such as a phthalate ester and a phosphate ester, an ultraviolet absorber, an antioxidant, a matting agent, etc. Additives can also be added.

<Additives>
<Retardation adjuster>
The retardation adjusting agent is not particularly limited, and when additives such as a plasticizer, an ultraviolet absorber, an antioxidant, and a matting agent are also used as the retardation adjusting agent, these additives are used in the present invention. Included in modifier.

(Retardation expression agent)
In this invention, in order to express a retardation value, what consists of a rod-shaped or a disk shaped compound can be mentioned. As the rod-like or discotic compound, a compound having at least two aromatic rings can be preferably used as a retardation developer.

The addition amount of the retardation developer composed of a rod-shaped compound is preferably 0.1 to 30 parts by mass, and preferably 0.5 to 20 parts by mass with respect to 100 parts by mass of the polymer component containing cellulose acylate. Is more preferable. The disk-like retardation developer is preferably used in the range of 0.05 to 20 parts by mass, and in the range of 1.0 to 15 parts by mass with respect to 100 parts by mass of the polymer component containing cellulose acylate. It is more preferable to use in the range of 3.0 to 10 parts by mass.

Since a discotic compound is superior to a rod-shaped compound in terms of retardation development, it is preferably used when particularly large retardation is required. Two or more types of retardation developing agents may be used in combination.

The retardation developer preferably has a maximum absorption in the wavelength region of 250 to 400 nm, and preferably has substantially no absorption in the visible region.

The discotic compound will be described. As the discotic compound, a compound having at least two aromatic rings can be used.

In the present specification, the “aromatic ring” includes an aromatic heterocycle in addition to an aromatic hydrocarbon ring.

The aromatic hydrocarbon ring is particularly preferably a 6-membered ring (that is, a benzene ring).

The aromatic heterocycle is generally an unsaturated heterocycle. The aromatic heterocycle is preferably a 5-membered ring, 6-membered ring or 7-membered ring, more preferably a 5-membered ring or 6-membered ring. Aromatic heterocycles generally have the most double bonds. As the hetero atom, a nitrogen atom, an oxygen atom and a sulfur atom are preferable, and a nitrogen atom is particularly preferable. Examples of aromatic heterocycles include furan ring, thiophene ring, pyrrole ring, oxazole ring, isoxazole ring, thiazole ring, isothiazole ring, imidazole ring, pyrazole ring, furazane ring, triazole ring, pyran ring, pyridine ring , Pyridazine ring, pyrimidine ring, pyrazine ring and 1,3,5-triazine ring.

As the aromatic ring, a benzene ring, a condensed benzene ring and biphenyls are preferable. In particular, 1,3,5-triazine ring is preferably used. Specifically, for example, compounds disclosed in JP-A No. 2001-166144 are preferably used.

The number of carbon atoms in the aromatic ring of the retardation developer is preferably 2 to 20, more preferably 2 to 12, still more preferably 2 to 8, and more preferably 2 to 6. Most preferred.

The bonding relationship between two aromatic rings can be classified into (a) when forming a condensed ring, (b) when directly connecting with a single bond, and (c) when connecting via a linking group (for aromatic rings). , Spiro bonds cannot be formed). The bond relationship may be any of (a) to (c).

Examples of the condensed ring (a condensed ring of two or more aromatic rings) include an indene ring, a naphthalene ring, an azulene ring, a fluorene ring, a phenanthrene ring, an anthracene ring, an acenaphthylene ring, a biphenylene ring, a naphthacene ring, Pyrene ring, indole ring, isoindole ring, benzofuran ring, benzothiophene ring, indolizine ring, benzoxazole ring, benzothiazole ring, benzimidazole ring, benzotriazole ring, purine ring, indazole ring, chromene ring, quinoline ring, isoquinoline Ring, quinolidine ring, quinazoline ring, cinnoline ring, quinoxaline ring, phthalazine ring, pteridine ring, carbazole ring, acridine ring, phenanthridine ring, xanthene ring, phenazine ring, phenothiazine ring, phenoxathiin ring, phenoxazine ring and thiant It includes emissions ring. Naphthalene ring, azulene ring, indole ring, benzoxazole ring, benzothiazole ring, benzimidazole ring, benzotriazole ring and quinoline ring are preferred.

(B) The single bond is preferably a bond between carbon atoms of two aromatic rings. Two aromatic rings may be bonded by two or more single bonds to form an aliphatic ring or a non-aromatic heterocyclic ring between the two aromatic rings.

(C) The linking group is also preferably bonded to carbon atoms of two aromatic rings. The linking group is preferably an alkylene group, an alkenylene group, an alkynylene group, —CO—, —O—, —NH—, —S—, or a combination thereof. Examples of linking groups composed of combinations are shown below. In addition, the relationship between the left and right in the following examples of the linking group may be reversed.

c1: —CO—O—
c2: —CO—NH—
c3: -alkylene-O-
c4: —NH—CO—NH—
c5: —NH—CO—O—
c6: —O—CO—O—
c7: —O-alkylene-O—
c8: -CO-alkenylene-
c9: —CO-alkenylene-NH—
c10: —CO-alkenylene-O—
c11: -alkylene-CO-O-alkylene-O-CO-alkylene-
c12: —O-alkylene-CO—O-alkylene-O—CO-alkylene-O—
c13: —O—CO-alkylene-CO—O—
c14: —NH—CO-alkenylene—
c15: —O—CO-alkenylene—
The aromatic ring and the linking group may have a substituent.

Examples of substituents include halogen atoms (F, Cl, Br, I), hydroxy groups, carboxy groups, cyano groups, amino groups, nitro groups, sulfo groups, carbamoyl groups, sulfamoyl groups, ureido groups, alkyl groups, alkenyls. Group, alkynyl group, aliphatic acyl group, aliphatic acyloxy group, alkoxy group, alkoxycarbonyl group, alkoxycarbonylamino group, alkylthio group, alkylsulfonyl group, aliphatic amide group, aliphatic sulfonamido group, aliphatic substituted amino group An aliphatic substituted carbamoyl group, an aliphatic substituted sulfamoyl group, an aliphatic substituted ureido group, and a non-aromatic heterocyclic group.

The number of carbon atoms in the alkyl group is preferably 1-8. A chain alkyl group is preferable to a cyclic alkyl group, and a linear alkyl group is particularly preferable. The alkyl group may further have a substituent (for example, a hydroxy group, a carboxy group, an alkoxy group, an alkyl-substituted amino group). Examples of alkyl groups (including substituted alkyl groups) include methyl, ethyl, n-butyl, n-hexyl, 2-hydroxyethyl, 4-carboxybutyl, 2-methoxyethyl and 2-methoxyethyl. Each group of a diethylaminoethyl group is included.

The alkenyl group preferably has 2 to 8 carbon atoms. A chain alkenyl group is preferable to a cyclic alkenyl group, and a linear alkenyl group is particularly preferable. The alkenyl group may further have a substituent. Examples of the alkenyl group include a vinyl group, an allyl group, and a 1-hexenyl group.

The number of carbon atoms of the alkynyl group is preferably 2-8. A chain alkynyl group is preferable to a cyclic alkynyl group, and a linear alkynyl group is particularly preferable. The alkynyl group may further have a substituent. Examples of the alkynyl group include ethynyl group, 1-butynyl group and 1-hexynyl group.

The number of carbon atoms in the aliphatic acyl group is preferably 1-10. Examples of the aliphatic acyl group include an acetyl group, a propanoyl group, and a butanoyl group.

The number of carbon atoms in the aliphatic acyloxy group is preferably 1-10. Examples of the aliphatic acyloxy group include an acetoxy group.

The number of carbon atoms of the alkoxy group is preferably 1-8. The alkoxy group may further have a substituent (for example, an alkoxy group). Examples of the alkoxy group (including a substituted alkoxy group) include a methoxy group, an ethoxy group, a butoxy group, and a methoxyethoxy group.

The number of carbon atoms of the alkoxycarbonyl group is preferably 2 to 10. Examples of the alkoxycarbonyl group include a methoxycarbonyl group and an ethoxycarbonyl group.

The number of carbon atoms of the alkoxycarbonylamino group is preferably 2 to 10. Examples of the alkoxycarbonylamino group include a methoxycarbonylamino group and an ethoxycarbonylamino group.

The number of carbon atoms of the alkylthio group is preferably 1-12. Examples of the alkylthio group include a methylthio group, an ethylthio group, and an octylthio group.

The number of carbon atoms of the alkylsulfonyl group is preferably 1-8. Examples of the alkylsulfonyl group include a methanesulfonyl group and an ethanesulfonyl group.

The number of carbon atoms in the aliphatic amide group is preferably 1-10. Examples of the aliphatic amide group include acetamide.

The number of carbon atoms in the aliphatic sulfonamide group is preferably 1-8. Examples of the aliphatic sulfonamido group include a methanesulfonamido group, a butanesulfonamido group, and an n-octanesulfonamido group.

The number of carbon atoms of the aliphatic substituted amino group is preferably 1-10. Examples of the aliphatic substituted amino group include a dimethylamino group, a diethylamino group, and a 2-carboxyethylamino group.

The number of carbon atoms in the aliphatic substituted carbamoyl group is preferably 2 to 10. Examples of the aliphatic substituted carbamoyl group include a methylcarbamoyl group and a diethylcarbamoyl group.

The number of carbon atoms of the aliphatic substituted sulfamoyl group is preferably 1-8. Examples of the aliphatic substituted sulfamoyl group include a methylsulfamoyl group and a diethylsulfamoyl group.

The number of carbon atoms of the aliphatic substituted ureido group is preferably 2 to 10. Examples of the aliphatic substituted ureido group include a methylureido group.

Examples of non-aromatic heterocyclic groups include piperidino groups and morpholino groups.

The molecular weight of the retardation developer is preferably 300 to 800.

It is preferable to use a triazine compound represented by the following general formula (I) as the discotic compound.

In the general formula (I), each R ¹ independently represents an aromatic ring or a heterocyclic ring having a substituent in at least one of the ortho position, the meta position, and the para position.

Each X independently represents a single bond or NR ² —. Here, each R ² independently represents a hydrogen atom, a substituted or unsubstituted alkyl group, an alkenyl group, an aryl group, or a heterocyclic group.

The aromatic ring represented by R ¹ is preferably phenyl or naphthyl, and particularly preferably phenyl. The aromatic ring represented by R ¹ may have at least one substituent at any substitution position. Examples of the substituent include a halogen atom, hydroxy group, cyano group, nitro group, carboxy group, alkyl group, alkenyl group, aryl group, alkoxy group, alkenyloxy group, aryloxy group, acyloxy group, alkoxycarbonyl group, Alkenyloxycarbonyl group, aryloxycarbonyl group, sulfamoyl group, alkyl-substituted sulfamoyl group, alkenyl-substituted sulfamoyl group, aryl-substituted sulfamoyl group, sulfonamide group, carbamoyl, alkyl-substituted carbamoyl group, alkenyl-substituted carbamoyl group, aryl-substituted carbamoyl group, amide Groups, alkylthio groups, alkenylthio groups, arylthio groups and acyl groups.

The heterocyclic group represented by R ¹ preferably has aromaticity. The heterocycle having aromaticity is generally an unsaturated heterocycle, preferably a heterocycle having the largest number of double bonds. The heterocyclic ring is preferably a 5-membered ring, 6-membered ring or 7-membered ring, more preferably a 5-membered ring or 6-membered ring, and most preferably a 6-membered ring. The hetero atom of the heterocyclic ring is preferably a nitrogen atom, a sulfur atom or an oxygen atom, and particularly preferably a nitrogen atom. As the heterocyclic ring having aromaticity, a pyridine ring (2-pyridyl or 4-pyridyl as the heterocyclic group) is particularly preferable. The heterocyclic group may have a substituent. Examples of the substituent of the heterocyclic group are the same as the examples of the substituent of the aryl moiety.

When X is a single bond, the heterocyclic group is preferably a heterocyclic group having a free valence on the nitrogen atom. The heterocyclic group having a free valence on the nitrogen atom is preferably a 5-membered ring, 6-membered ring or 7-membered ring, more preferably a 5-membered ring or 6-membered ring, and a 5-membered ring. Is most preferred. The heterocyclic group may have a plurality of nitrogen atoms. Further, the heterocyclic group may have a hetero atom other than the nitrogen atom (for example, O, S). Examples of heterocyclic groups having free valences on nitrogen atoms are shown below. Here, —C ₄ H ₉ n represents nC ₄ H ₉ .

The alkyl group represented by R ² may be a cyclic alkyl group or a chain alkyl group, but a chain alkyl group is preferable, and a linear alkyl group is more preferable than a branched chain alkyl group. preferable. The alkyl group preferably has 1 to 30 carbon atoms, more preferably 1 to 20, more preferably 1 to 10, still more preferably 1 to 8, and further preferably 1 to 6. Most preferred. The alkyl group may have a substituent. Examples of the substituent include a halogen atom, an alkoxy group (for example, methoxy group, ethoxy group) and an acyloxy group (for example, acryloyloxy group, methacryloyloxy group).

The alkenyl group represented by R ² may be a cyclic alkenyl group or a chain alkenyl group, but preferably represents a chain alkenyl group, and is a straight chain alkenyl group rather than a branched chain alkenyl group. More preferably it represents a group. The number of carbon atoms of the alkenyl group is preferably 2 to 30, more preferably 2 to 20, further preferably 2 to 10, still more preferably 2 to 8, and further preferably 2 to 6 is most preferred. The alkenyl group may have a substituent. Examples of the substituent are the same as those of the alkyl group described above.

The aromatic ring group and heterocyclic group represented by R ² are the same as the aromatic ring and heterocyclic ring represented by R ¹ , and the preferred range is also the same. The aromatic ring group and the heterocyclic group may further have a substituent, and examples of the substituent are the same as those of the aromatic ring and heterocyclic ring of R ¹ .

Specific examples of the compound represented by the general formula (I) are given below, but are not limited thereto.

As the discotic compound, a triphenylene compound represented by the following general formula (II) can also be preferably used.

In the general formula (II), R ¹ to R ⁶ each independently represents a hydrogen atom or a substituent.

The substituent represented by each of R ¹ to R ⁶ is an alkyl group (preferably an alkyl group having 1 to 40 carbon atoms, more preferably 1 to 30 carbon atoms, and particularly preferably 1 to 20 carbon atoms. Group, ethyl group, isopropyl group, tert-butyl group, n-octyl group, n-decyl group, n-hexadecyl group, cyclopropyl group, cyclopentyl group, cyclohexyl group, etc.), alkenyl group (preferably carbon An alkenyl group having 2 to 40 carbon atoms, more preferably 2 to 30 carbon atoms, particularly preferably 2 to 20 carbon atoms, and examples thereof include a vinyl group, an allyl group, a 2-butenyl group, and a 3-pentenyl group. An alkynyl group (preferably an alkynyl group having 2 to 40 carbon atoms, more preferably 2 to 30 carbon atoms, particularly preferably 2 to 20 carbon atoms, For example, a propargyl group, a 3-pentynyl group, etc.), an aryl group (preferably an aryl group having 6 to 30 carbon atoms, more preferably 6 to 20 carbon atoms, particularly preferably 6 to 12 carbon atoms, , Phenyl group, p-methylphenyl group, naphthyl group, etc.), substituted or unsubstituted amino group (preferably having 0 to 40 carbon atoms, more preferably 0 to 30 carbon atoms, and particularly preferably 0 to carbon atoms). 20 amino groups, such as an unsubstituted amino group, a methylamino group, a dimethylamino group, a diethylamino group, and an anilino group), an alkoxy group (preferably having 1 to 40 carbon atoms, more preferably 1 carbon atom). To 30 and particularly preferably an alkoxy group having 1 to 20 carbon atoms, and examples thereof include a methoxy group, an ethoxy group, and a butoxy group). A reeloxy group (preferably an aryloxy group having 6 to 40 carbon atoms, more preferably 6 to 30 carbon atoms, particularly preferably 6 to 20 carbon atoms, and examples thereof include a phenyloxy group and a 2-naphthyloxy group. An acyl group (preferably an acyl group having 1 to 40 carbon atoms, more preferably 1 to 30 carbon atoms, particularly preferably 1 to 20 carbon atoms, for example, an acetyl group, a benzoyl group, a formyl group, a pivaloyl group) An alkoxycarbonyl group (preferably an alkoxycarbonyl group having 2 to 40 carbon atoms, more preferably 2 to 30 carbon atoms, particularly preferably 2 to 20 carbon atoms, such as a methoxycarbonyl group, ethoxycarbonyl group, etc.) Groups), aryloxycarbonyl groups (preferably having 7 to 40 carbon atoms, more preferably carbon numbers) An aryloxycarbonyl group having 7 to 30 carbon atoms, particularly preferably 7 to 20 carbon atoms, such as a phenyloxycarbonyl group, and an acyloxy group (preferably 2 to 40 carbon atoms, more preferably 2 to 2 carbon atoms). 30, particularly preferably an acyloxy group having 2 to 20 carbon atoms, such as an acetoxy group and a benzoyloxy group), an acylamino group (preferably having 2 to 40 carbon atoms, more preferably 2 to 30 carbon atoms, Particularly preferred are acylamino groups having 2 to 20 carbon atoms, such as acetylamino group and benzoylamino group, and alkoxycarbonylamino groups (preferably having 2 to 40 carbon atoms, more preferably 2 to 30 carbon atoms, Particularly preferred is an alkoxycarbonylamino group having 2 to 20 carbon atoms, for example, methoxy A sulfonylamino group), an aryloxycarbonylamino group (preferably an aryloxycarbonylamino group having 7 to 40 carbon atoms, more preferably 7 to 30 carbon atoms, particularly preferably 7 to 20 carbon atoms, , A phenyloxycarbonylamino group, etc.), a sulfonylamino group (preferably a sulfonylamino group having 1 to 40 carbon atoms, more preferably 1 to 30 carbon atoms, particularly preferably 1 to 20 carbon atoms, A methanesulfonylamino group, a benzenesulfonylamino group, etc.), a sulfamoyl group (preferably a sulfamoyl group having 0 to 40 carbon atoms, more preferably 0 to 30 carbon atoms, particularly preferably 0 to 20 carbon atoms, , Sulfamoyl group, methylsulfamoyl group, dimethylsulfamo A carbamoyl group (preferably having 1 to 40 carbon atoms, more preferably 1 to 30 carbon atoms, and particularly preferably 1 to 20 carbon atoms). An unsubstituted carbamoyl group, a methylcarbamoyl group, a diethylcarbamoyl group, a phenylcarbamoyl group, and the like), an alkylthio group (preferably having 1 to 40 carbon atoms, more preferably 1 to 30 carbon atoms, and particularly preferably 1 to carbon atoms). 20, for example, methylthio group, ethylthio group, propylthio group, butylthio group, pentylthio group, hexylthio group, heptylthio group, octylthio group and the like, arylthio group (preferably having 6 to 40 carbon atoms, more preferably 6 to 30 carbon atoms, particularly preferably 1 to 20 carbon atoms, such as Fe A sulfonyl group (preferably 1 to 40 carbon atoms, more preferably 1 to 30 carbon atoms, particularly preferably 1 to 20 carbon atoms, such as mesyl group and tosyl group). A sulfinyl group (preferably a sulfinyl group having 1 to 40 carbon atoms, more preferably 1 to 30 carbon atoms, particularly preferably 1 to 20 carbon atoms, such as a methanesulfinyl group and a benzenesulfinyl group). Ureido groups (preferably ureido groups having 1 to 40 carbon atoms, more preferably 1 to 30 carbon atoms, particularly preferably 1 to 20 carbon atoms, such as unsubstituted ureido groups, methylureido groups, Phenylureido group, etc.), phosphoric acid amide group (preferably having 1 to 40 carbon atoms, more preferably 1 to 30 carbon atoms, A phosphoric acid amide group having 1 to 20 carbon atoms is preferable, and examples thereof include a diethylphosphoric acid amide group and a phenylphosphoric acid amide group, a hydroxy group, a mercapto group, a halogen atom (for example, a fluorine atom, a chlorine atom, Bromine atom, iodine atom), cyano group, sulfo group, carboxy group, nitro group, hydroxamic acid group, sulfino group, hydrazino group, imino group, heterocyclic group (preferably having 1 to 30 carbon atoms, more preferably 1 to 12 carbon atoms). A heterocyclic group having a heteroatom such as a nitrogen atom, an oxygen atom or a sulfur atom, such as an imidazolyl group, a pyridyl group, a quinolyl group, a furyl group, a piperidyl group, a morpholino group, a benzoyl group, (Oxazolyl group, benzimidazolyl group, benzthiazolyl group, 1,3,5-triazyl group, etc.) Silyl group (preferably a silyl group having 3 to 40 carbon atoms, more preferably 3 to 30 carbon atoms, particularly preferably 3 to 24 carbon atoms, and examples thereof include a trimethylsilyl group and a triphenylsilyl group) Is included. These substituents may be further substituted with these substituents. Moreover, when it has two or more substituents, they may be the same or different. If possible, they may be bonded to each other to form a ring.

The substituent represented by each of R ¹ to R ⁶ is preferably an alkyl group, an aryl group, a substituted or unsubstituted amino group, an alkoxy group, an alkylthio group, or a halogen atom. Although the specific example of a compound represented by general formula (II) below is given, it is not limited to this.

The compound represented by the general formula (I) is, for example, a method described in JP-A-2003-344655, and the compound represented by the general formula (II) is, for example, a method described in JP-A-2005-134484. Can be synthesized by a known method.

In the present invention, rod-like compounds having a linear molecular structure can be preferably used in addition to the above-mentioned discotic compounds. The linear molecular structure means that the molecular structure of the rod-like compound is linear in the most thermodynamically stable structure. The most thermodynamically stable structure can be obtained by crystal structure analysis or molecular orbital calculation. For example, molecular orbital calculation is performed using molecular orbital calculation software (for example, WinMOPAC2000, manufactured by Fujitsu Limited), and a molecular structure that minimizes the heat of formation of a compound can be obtained. The molecular structure being linear means that in the thermodynamically most stable structure obtained by calculation as described above, the angle of the main chain constituting the molecular structure is 140 degrees or more.

The rod-shaped compound having at least two aromatic rings is preferably a compound represented by the following general formula (11).

Formula (11): Ar ₁ -L ₁ -Ar ₂
In the general formula (11), Ar ₁ and Ar ₂ are each independently an aromatic group.

In the present specification, the aromatic group includes an aryl group (aromatic hydrocarbon group), a substituted aryl group, an aromatic heterocyclic group, and a substituted aromatic heterocyclic group.

An aryl group and a substituted aryl group are more preferable than an aromatic heterocyclic group and a substituted aromatic heterocyclic group. The heterocyclic ring of the aromatic heterocyclic group is generally unsaturated. The aromatic heterocycle is preferably a 5-membered ring, 6-membered ring or 7-membered ring, more preferably a 5-membered ring or 6-membered ring. Aromatic heterocycles generally have the most double bonds. As a hetero atom, a nitrogen atom, an oxygen atom or a sulfur atom is preferable, and a nitrogen atom or a sulfur atom is more preferable.

As the aromatic ring of the aromatic group, a benzene ring, a furan ring, a thiophene ring, a pyrrole ring, an oxazole ring, a thiazole ring, an imidazole ring, a triazole ring, a pyridine ring, a pyrimidine ring and a pyrazine ring are preferable, and a benzene ring is particularly preferable. .

Examples of the substituent of the substituted aryl group and the substituted aromatic heterocyclic group include a halogen atom (F, Cl, Br, I), a hydroxy group, a carboxy group, a cyano group, an amino group, an alkylamino group (for example, methyl Amino group, ethylamino group, butylamino group, dimethylamino group), nitro group, sulfo group, carbamoyl group, alkylcarbamoyl group (for example, N-methylcarbamoyl group, N-ethylcarbamoyl group, N, N-) Dimethylcarbamoyl group), sulfamoyl group, alkylsulfamoyl group (eg, N-methylsulfamoyl group, N-ethylsulfamoyl group, N, N-dimethylsulfamoyl group), ureido Group, alkylureido group (for example, N-methylureido group, N, N-dimethylureido group, N, N, N′-trimethyl) Each group of ureido group), alkyl group (for example, methyl group, ethyl group, propyl group, butyl group, pentyl group, heptyl group, octyl group, isopropyl group, s-butyl group, tert-amyl group, cyclohexyl group, cyclopentyl) Group), alkenyl group (for example, vinyl group, allyl group, hexenyl group), alkynyl group (for example, ethynyl group, butynyl group), acyl group (for example, formyl group, acetyl group, butyryl group, Hexanoyl group, lauryl group), acyloxy group (for example, acetoxy group, butyryloxy group, hexanoyloxy group, lauryloxy group), alkoxy group (for example, methoxy group, ethoxy group, propoxy group, butoxy group) Pentyloxy group, heptyloxy group, octyloxy group), aryloxy Group (for example, phenoxy group), alkoxycarbonyl group (for example, methoxycarbonyl group, ethoxycarbonyl group, propoxycarbonyl group, butoxycarbonyl group, pentyloxycarbonyl group, heptyloxycarbonyl group), aryloxycarbonyl group (for example, , Phenoxycarbonyl group), alkoxycarbonylamino group (for example, butoxycarbonylamino group, hexyloxycarbonylamino group), alkylthio group (for example, methylthio group, ethylthio group, propylthio group, butylthio group, pentylthio group, heptylthio group, octylthio group) Each group), arylthio group (for example, phenylthio group), alkylsulfonyl group (for example, methylsulfonyl group, ethylsulfonyl group, propylsulfonyl group, butylsulfonyl) Group, pentylsulfonyl group, heptylsulfonyl group, octylsulfonyl group), amide group (for example, acetamido group, butyramide group, hexylamide group, laurylamide group) and non-aromatic heterocyclic group (for example, , Morpholyl group, and pyrazinyl group).

Among these, preferable substituents include halogen atoms, cyano groups, carboxy groups, hydroxy groups, amino groups, alkylamino groups, acyl groups, acyloxy groups, amide groups, alkoxycarbonyl groups, alkoxy groups, alkylthio groups, and alkyl groups. Can be mentioned.

The alkyl moiety of the alkylamino group, alkoxycarbonyl group, alkoxy group, and alkylthio group and the alkyl group may further have a substituent. Examples of the alkyl moiety and the substituent of the alkyl group include a halogen atom, hydroxy group, carboxy group, cyano group, amino group, alkylamino group, nitro group, sulfo group, carbamoyl group, alkylcarbamoyl group, sulfamoyl group, alkylsulfur group. Famoyl group, ureido group, alkylureido group, alkenyl group, alkynyl group, acyl group, acyloxy group, alkoxy group, aryloxy group, alkoxycarbonyl group, aryloxycarbonyl group, alkoxycarbonylamino group, alkylthio group, arylthio group, An alkylsulfonyl group, an amide group and a non-aromatic heterocyclic group are included. As the substituent for the alkyl moiety and the alkyl group, a halogen atom, a hydroxy group, an amino group, an alkylamino group, an acyl group, an acyloxy group, an acylamino group, an alkoxycarbonyl group, and an alkoxy group are preferable.

In the general formula (11), L1 is a divalent linking group selected from an alkylene group, an alkenylene group, an alkynylene group, —O—, —CO— and a combination thereof.

The alkylene group may have a cyclic structure. As the cyclic alkylene group, cyclohexylene is preferable, and 1,4-cyclohexylene is particularly preferable. As the chain alkylene group, a linear alkylene group is more preferable than a branched alkylene group.

The number of carbon atoms of the alkylene group is preferably 1-20, more preferably 1-15, still more preferably 1-10, still more preferably 1-8, and most preferably 1-6. It is.

The alkenylene group and the alkynylene group preferably have a chain structure rather than a cyclic structure, and more preferably have a linear structure rather than a branched chain structure.

The number of carbon atoms of the alkenylene group and the alkynylene group is preferably 2 to 10, more preferably 2 to 8, further preferably 2 to 6, further preferably 2 to 4, and most preferably 2. (Vinylene group or ethynylene group).

The arylene group preferably has 6 to 20 carbon atoms, more preferably 6 to 16, and still more preferably 6 to 12.

In the molecular structure of the general formula (11), the angle formed by Ar ₁ and Ar ₂ across L ₁ is preferably 140 degrees or more.

As the rod-like compound, a compound represented by the following formula (12) is more preferable.

Formula (12): Ar ₁ -L ₂ -XL ₃ -Ar ₂
In the general formula (12), Ar ₁ and Ar ₂ are each independently an aromatic group. The definition and examples of the aromatic group are the same as those of Ar ₁ and Ar _{2 in} the general formula (12).

In the general formula (12), L ₂ and L ₃ are each independently a divalent linking group selected from an alkylene group, —O—, —CO— and a group consisting of a combination thereof.

The alkylene group preferably has a chain structure rather than a cyclic structure, and more preferably has a linear structure rather than a branched chain structure.

The number of carbon atoms of the alkylene group is preferably 1 to 10, more preferably 1 to 8, still more preferably 1 to 6, further preferably 1 to 4, and 1 or 2 (methylene group). Or an ethylene group) is most preferable.

L ₂ and L ₃ are particularly preferably —O—CO— or CO—O—.

In the general formula (12), X represents a 1,4-cyclohexylene group, a vinylene group or an ethynylene group.

Specific examples of the compound represented by the general formula (11) or (12) include compounds described in [Chemical Formula 1] to [Chemical Formula 11] of JP-A No. 2004-109657.

Two or more rod-like compounds having a maximum absorption wavelength (λmax) longer than 250 nm in the ultraviolet absorption spectrum of the solution may be used in combination.

The rod-like compound can be synthesized with reference to the methods described in the literature. As literature, Mol. Cryst. Liq. Cryst. 53, 229 (1979), 89, 93 (1982), 145, 111 (1987), 170, 43 (1989), J. Am. Am. Chem. Soc. 113, p. 1349 (1991), p. 118, p. 5346 (1996), p. 92, p. 1582 (1970). Org. Chem. 40, 420 pages (1975), Tetrahedron, Vol. 48, No. 16, page 3437 (1992).

Also, the rod-like aromatic compounds described on pages 11 to 14 of JP-A-2004-50516 may be used as the Ro enhancer.

Further, as the retardation developer, one kind of compound can be used alone, or two or more kinds of compounds can be mixed and used. It is preferable to use two or more different compounds as the retardation enhancer because the retardation adjustment range is widened and can be easily adjusted to a desired range.

The amount of addition of the retardation developer is preferably 0.1 to 20% by mass, more preferably 0.5 to 10% by mass with respect to 100 parts by mass of cellulose acylate. When the cellulose acylate film is produced by a solvent cast method, the retardation developer may be added to the dope. The addition may be performed at any timing, for example, the retardation developer may be dissolved in an organic solvent such as alcohol, methylene chloride, dioxolane, and then added to the cellulose acylate solution (dope), or You may add directly in dope composition.

In particular, the ratio of the discotic compound is preferably 0.1 to 20%, more preferably 0.5 to 15%, more preferably 1 to 10 based on the total mass of the discotic compound and the rod-shaped compound. % Is particularly preferred.

Other specific examples of preferable rod-like compounds other than those described in the above-mentioned publications are shown below.

Specific examples (1) to (34), (41), and (42) have two asymmetric carbon atoms at the 1-position and the 4-position of the cyclohexane ring. However, since the specific examples (1), (4) to (34), (41), (42) have a symmetrical meso type molecular structure, there are no optical isomers (optical activity), and geometric isomers (trans Type and cis type). The trans type (1-trans) and cis type (1-cis) of specific example (1) are shown below.

As described above, the rod-like compound preferably has a linear molecular structure. Therefore, the trans type is preferable to the cis type.

Specific examples (2) and (3) have optical isomers (a total of four isomers) in addition to geometric isomers. As for geometric isomers, the trans type is similarly preferable to the cis type. The optical isomer is not particularly superior or inferior, and may be D, L, or a racemate.

In specific examples (43) to (45), the central vinylene bond includes a trans type and a cis type. For the same reason as above, the trans type is preferable to the cis type.

As the retardation developer according to the present invention, a polymer additive can be used as in the case of the low molecular weight compound. The polymer additive is selected from polyester polymers, styrene polymers, acrylic polymers, and copolymers thereof, and aromatic polyesters are preferred.

The aromatic polyester polymer used in the present invention is obtained by copolymerizing a monomer having an aromatic ring with the polyester polymer. The monomer having an aromatic ring is at least one monomer selected from aromatic dicarboxylic acids having 8 to 20 carbon atoms and aromatic diols having 6 to 20 carbon atoms.

Examples of the aromatic dicarboxylic acid having 8 to 20 carbon atoms include phthalic acid, terephthalic acid, isophthalic acid, 1,5-naphthalenedicarboxylic acid, 1,4-naphthalenedicarboxylic acid, 1,8-naphthalenedicarboxylic acid, 2,8- There are naphthalenedicarboxylic acid and 2,6-naphthalenedicarboxylic acid. Among these, preferable aromatic dicarboxylic acids are phthalic acid, terephthalic acid, and isophthalic acid.

Examples of the aromatic diol having 6 to 20 carbon atoms include, but are not limited to, bisphenol A, 1,2-hydroxybenzene, 1,3-hydroxybenzene, 1,4-hydroxybenzene, and 1,4-benzenedimethanol. Of these, bisphenol A, 1,4-hydroxybenzene, and 1,4-benzenedimethanol are preferred.

In the present invention, the aforementioned polyester is used in combination with at least one of aromatic dicarboxylic acid or aromatic diol, but the combination is not particularly limited, and there is no problem even if several kinds of each component are combined. . In the present invention, as described above, a high molecular weight additive whose end is sealed with an alkyl group or an aromatic group is particularly preferable, and the above-described method can be used for sealing.

The polyester polymer used in the present invention is described below, but the present invention is not limited thereto.

Examples of the retardation developing agent according to the present invention include, for example, a discotic compound and a rod-like compound among the retardation developing agents, among which triazine compounds and rod-like compounds having a plurality of aromatic rings (1 ) To (7) are preferred.

(Other additives)
In the present invention, a plasticizer, a deterioration inhibitor, an ultraviolet absorber, a peeling accelerator, a matting agent, a lubricant, the above-described plasticizer, and the like can be appropriately used as necessary.

(Plasticizer)
As the plasticizer, phosphoric acid ester or carboxylic acid ester is used. Examples of phosphate esters include triphenyl phosphate (TPP) and tricresyl phosphate (TCP). Representative examples of the carboxylic acid ester include phthalic acid esters and citric acid esters. Examples of phthalic acid esters include dimethyl phthalate (DMP), diethyl phthalate (DEP), dibutyl phthalate (DBP), dioctyl phthalate (DOP), diphenyl phthalate (DPP) and diethyl hexyl phthalate (DEHP). Examples of citrate esters include triethyl O-acetylcitrate (OACTE) and tributyl O-acetylcitrate (OACTB). Examples of other carboxylic acid esters include butyl oleate, methylacetyl ricinoleate, dibutyl sebacate, and various trimellitic acid esters. Phthalate plasticizers (DMP, DEP, DBP, DOP, DPP, DEHP) are preferably used. DEP and DPP are particularly preferred. The addition amount of the plasticizer is preferably from 0.1 to 25% by mass, more preferably from 1 to 20% by mass, and most preferably from 3 to 15% by mass based on the mass of the cellulosic resin.

(Deterioration inhibitor)
In the present invention, a known deterioration (oxidation) inhibitor such as 2,6-di-tert-butyl-4-methylphenol, 4,4′-thiobis- (6-tert-butyl-3-) is added to the cellulose ester solution. Methylphenol), 1,1'-bis (4-hydroxyphenyl) cyclohexane, 2,2'-methylenebis (4-ethyl-6-tert-butylphenol), 2,5-di-tert-butylhydroquinone, pentaerythrityl A phenolic or hydroquinone antioxidant such as tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate] can be added. Further, tris (4-methoxy-3,5-diphenyl) phosphite, tris (nonylphenyl) phosphite, tris (2,4-di-tert-butylphenyl) phosphite, bis (2,6-di-tert) Phosphorus antioxidants such as -butyl-4-methylphenyl) pentaerythritol diphosphite and bis (2,4-di-tert-butylphenyl) pentaerythritol diphosphite are preferably used. The deterioration inhibitor is added in an amount of 0.05 to 5.0 parts by mass with respect to 100 parts by mass of the cellulose resin.

(UV absorber)
In the present invention, an ultraviolet absorber is preferably used for the cellulose ester solution from the viewpoint of preventing deterioration of a polarizing plate or liquid crystal. As the ultraviolet absorber, those excellent in the ability to absorb ultraviolet rays having a wavelength of 370 nm or less and having little absorption of visible light having a wavelength of 400 nm or more are preferably used from the viewpoint of good liquid crystal display properties. Specific examples of ultraviolet absorbers preferably used in the present invention include, for example, hindered phenol compounds, hydroxybenzophenone compounds, benzotriazole compounds, salicylic acid ester compounds, benzophenone compounds, cyanoacrylate compounds, nickel complex compounds Etc. Examples of hindered phenol compounds include 2,6-di-tert-butyl-p-cresol, pentaerythrityl-tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate]. N, N'-hexamethylenebis (3,5-di-tert-butyl-4-hydroxy-hydrocinnamide), 1,3,5-trimethyl-2,4,6-tris (3,5-di-tert) -Butyl-4-hydroxybenzyl) benzene, tris- (3,5-di-tert-butyl-4-hydroxybenzyl) -isocyanurate and the like. Examples of benzotriazole compounds include 2- (2′-hydroxy-5′-methylphenyl) benzotriazole, 2,2-methylenebis (4- (1,1,3,3-tetramethylbutyl) -6- (2H-benzotriazol-2-yl) phenol), (2,4-bis- (n-octylthio) -6- (4-hydroxy-3,5-di-tert-butylanilino) -1,3,5- Triazine, triethylene glycol-bis [3- (3-tert-butyl-5-methyl-4-hydroxyphenyl) propionate], N, N′-hexamethylenebis (3,5-di-tert-butyl-4- Hydroxy-hydrocinnamide), 1,3,5-trimethyl-2,4,6-tris (3,5-di-tert-butyl-4-hydroxybenzyl) benzene 2- (2'-hydroxy-3 ', 5'-di-tert-butylphenyl) -5-chlorobenzotriazole, (2- (2'-hydroxy-3', 5'-di-tert-amylphenyl) -5-chlorobenzotriazole, 2,6-di-tert-butyl-p-cresol, pentaerythrityl-tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate] The addition amount of these ultraviolet light inhibitors is preferably 1 ppm to 1.0%, more preferably 10 to 1000 ppm by weight in the whole cellulose ester film.

(Peeling accelerator)
It is preferable that the film of the present invention contains a release accelerator from the viewpoint of more releasability. The release accelerator can be included, for example, in a proportion of 0.001 to 1% by mass, and the addition of 0.5% by mass or less is preferable because separation of the release agent from the film hardly occurs. 005% by mass or more is preferable because a desired peeling reduction effect can be obtained. Therefore, it is preferably included at a rate of 0.005 to 0.5% by mass, and at a rate of 0.01 to 0.3% by mass. More preferably. As the peeling accelerator, known ones can be adopted, and organic and inorganic acidic compounds, surfactants, chelating agents and the like can be used. Among them, polyvalent carboxylic acids and esters thereof are effective, and in particular, ethyl esters of citric acid can be used effectively.

The film of the present invention preferably contains a peeling accelerator in the skin B layer.

(Matting agent)
In particular, the film of the present invention is generally added with fine particles in order to prevent the film from being scratched or deteriorated in transportability. They are called matting agents, anti-blocking agents or anti-scratching agents and have been used conventionally. They are not particularly limited as long as they have the above-described functions, and may be an inorganic compound matting agent or an organic compound matting agent.

Specific examples of the inorganic compound matting agent include silicon-containing inorganic compounds (for example, silicon dioxide, calcined calcium silicate, hydrated calcium silicate, aluminum silicate, magnesium silicate, etc.), titanium oxide, and zinc oxide. , Aluminum oxide, barium oxide, zirconium oxide, strongtium oxide, antimony oxide, tin oxide, tin oxide / antimony, calcium carbonate, talc, clay, calcined kaolin, calcium phosphate, etc., more preferably silicon-containing inorganic compounds and oxides Although it is zirconium, since the turbidity of the cellulose ester film can be reduced, silicon dioxide is particularly preferably used. As the silicon dioxide fine particles, for example, commercially available products having trade names such as Aerosil R972, R974, R812, 200, 300, R202, OX50, TT600 (manufactured by Nippon Aerosil Co., Ltd.) can be used. As the zirconium oxide fine particles, for example, those commercially available under trade names such as Aerosil R976 and R811 (manufactured by Nippon Aerosil Co., Ltd.) can be used.

Preferred examples of the organic compound matting agent include, for example, polymers such as silicone resin, fluorine resin, and acrylic resin, and among them, silicone resin is preferably used. Among the silicone resins, those having a three-dimensional network structure are particularly preferable. For example, Tospearl 103, Tospearl 105, Tospearl 108, Tospearl 120, Tospearl 145, Tospearl 3120 and Tospearl 240 (manufactured by Toshiba Silicone Co., Ltd.) A commercial product having a trade name can be used.

When these matting agents are added to the cellulose ester solution, the method is not particularly limited, and there is no problem as long as a desired cellulose ester solution can be obtained by any method. For example, an additive may be included at the stage of mixing the cellulose ester and the solvent, or the additive may be added after preparing a mixed solution with the cellulose ester and the solvent. Further, it may be added and mixed immediately before casting the dope, which is a so-called immediately preceding addition method, and the mixing is used by installing screw-type kneading online. Specifically, a static mixer such as an inline mixer is preferable.

The film of the present invention contains a matting agent in at least one of the skin A layer and the skin B layer, and is generated when a wide film is wound long by reducing the friction coefficient of the film surface. It is preferable from the viewpoint of prevention of creaking and prevention of film breakage, and it is particularly preferable from the viewpoint of effectively reducing scratch resistance and blemishes that both the skin A layer and the skin B layer contain a matting agent.

In the film of the present invention, when the matting agent is not added in a large amount, the haze of the film does not increase, and when actually used in an LCD, inconveniences such as a decrease in contrast and generation of bright spots are unlikely to occur. If the amount is too small, the above-mentioned creaking and scratch resistance can be realized. From these viewpoints, it is preferably included in a proportion of 0.01 to 5.0% by mass, more preferably included in a proportion of 0.03 to 3.0% by mass, and a proportion of 0.05 to 1.0% by mass. It is particularly preferable to include

(Haze)
The cellulose ester film of the present invention preferably has a haze of less than 1%, more preferably less than 0.5%. By setting the haze to less than 1%, there is an advantage that the transparency of the film becomes higher and it becomes easier to use as a cellulose ester film.

(Film thickness)
In the film of the present invention, the film thickness of the single film is preferably 20 to 50 μm, the average film thickness of the core layer at the time of lamination is preferably 20 to 50 μm, more preferably 20 to 45 μm, and more preferably 30 to More preferably, it is 45 μm. By setting it to 20 μm or more, the handling property when producing a web-like film is improved, which is preferable. Moreover, by setting it as 50 micrometers or less, it is easy to respond to a humidity change and it is easy to maintain an optical characteristic.

The film of the present invention may have an average film thickness of at least one of the skin A layer or the skin B layer of 0.2% or more and less than 25% of the average film thickness of the core layer. If it is less than 25%, the optical performance of the core layer can be effectively utilized, and the laminate film can be effectively used. Is preferable from the viewpoint of obtaining sufficient optical characteristics, more preferably 0.5 to 15%, and particularly preferably 1.0 to 10%. Moreover, it is more preferable that the average film thickness of the skin A layer and the skin B layer are both 0.2% or more and less than 25% of the average core layer film thickness.

(Film length and width)
In the cellulose ester film of the present invention, the length of the film is preferably in the range of 5000 to 10,000 m, and the width of the film is preferably in the range of 1.9 to 2.5 m.

[Method for producing cellulose ester film]
The film production method of the present invention comprises a step of dissolving a polymer in an organic solvent to prepare a dope (dope preparation step), a step of filtering the dope (filtration step), and casting the dope on a support. A process (casting process), a process of drying the obtained film (drying process), a process of stretching the obtained film (stretching process), and other processes as necessary.

Moreover, the manufacturing method of the cellulose-ester laminated film of this invention is a dope containing the cellulose ester which satisfy | fills said Formula (2), and the dope containing the cellulose ester which satisfy | fills said Formula (1) on a support body in this order. The method includes a step of performing multilayer casting simultaneously or sequentially, a step of drying the multilayer cast dope and peeling it from the support, and a step of stretching the peeled film.

(Dope preparation process)
Specifically, in the production method according to the present invention, the film of the present invention is produced using a solution (dope) obtained by dissolving a cellulose ester in an organic solvent by a solvent cast method.

The organic solvent is selected from ethers having 3 to 12 carbon atoms, ketones having 3 to 12 carbon atoms, esters having 3 to 12 carbon atoms, and halogenated hydrocarbons having 1 to 6 carbon atoms. It is preferable to include a solvent. The ether, ketone and ester may have a cyclic structure. A compound having two or more functional groups of ether, ketone and ester (that is, —O—, —CO— and COO—) can also be used as the organic solvent. The organic solvent may have another functional group such as an alcoholic hydroxy group (hydroxyl group). In the case of an organic solvent having two or more types of functional groups, the number of carbon atoms may be within the specified range of the compound having any functional group.

Examples of ethers having 3 to 12 carbon atoms include diisopropyl ether, dimethoxymethane, dimethoxyethane, 1,4-dioxane, 1,3-dioxolane, tetrahydrofuran, anisole and phenetole.

Examples of ketones having 3 to 12 carbon atoms include acetone, methyl ethyl ketone, diethyl ketone, diisobutyl ketone, cyclohexanone and methylcyclohexanone.

Examples of esters having 3 to 12 carbon atoms include ethyl formate, propyl formate, pentyl formate, methyl acetate, ethyl acetate and pentyl acetate.

Examples of the organic solvent having two or more kinds of functional groups include 2-ethoxyethyl acetate, 2-methoxyethanol and 2-butoxyethanol.

The number of carbon atoms of the halogenated hydrocarbon is preferably 1 or 2, and most preferably 1. The halogen of the halogenated hydrocarbon is preferably chlorine. The proportion of halogen atoms in the halogenated hydrocarbon substituted with halogen is preferably 25 to 75 mol%, more preferably 30 to 70 mol%, and more preferably 35 to 65 mol%. More preferably, it is most preferably 40 to 60 mol%. Methylene chloride is a representative halogenated hydrocarbon.

Two or more organic solvents may be mixed and used.

A cellulose ester solution can be prepared by a general method. A general method means processing at a temperature of 0 ° C. or higher (ordinary temperature or high temperature). The solution can be prepared by using a dope preparation method and apparatus in a normal solvent cast method. In the case of a general method, it is preferable to use a halogenated hydrocarbon (particularly, methylene chloride) as the organic solvent.

The amount of cellulose ester is adjusted so as to be contained in the obtained solution in an amount of 10 to 40% by mass. The amount of cellulose ester is more preferably 10 to 30% by mass. Arbitrary additives may be added to the organic solvent (main solvent).

The solution can be prepared by stirring the cellulose ester and the organic solvent at room temperature (0 to 40 ° C.). The high concentration solution may be stirred under pressure and heating conditions. Specifically, the cellulose ester and the organic solvent are placed in a pressure vessel and sealed, and stirred while heating to a temperature not lower than the boiling point of the solvent at normal temperature and in a range where the solvent does not boil. The heating temperature is usually 40 ° C. or higher, preferably 60 to 200 ° C., more preferably 80 to 110 ° C.

Each component may be roughly mixed in advance and then placed in a container. Moreover, you may put into a container sequentially. The container needs to be configured so that it can be stirred. The container can be pressurized by injecting an inert gas such as nitrogen gas. Moreover, you may utilize the raise of the vapor pressure of the solvent by heating. Or after sealing a container, you may add each component under pressure.

When heating, it is preferable to heat from the outside of the container. For example, a jacket type heating device can be used. The entire container can also be heated by providing a plate heater outside the container and piping to circulate the liquid.

It is preferable to stir using a stirring blade provided inside the container. The stirring blade preferably has a length that reaches the vicinity of the wall of the container. A scraping blade is preferably provided at the end of the stirring blade in order to renew the liquid film on the vessel wall.

容器 In the container, instruments such as a pressure gauge and a thermometer may be installed. Each component is dissolved in a solvent in a container. The prepared dope is taken out of the container after cooling, or taken out and then cooled using a heat exchanger or the like.

The solution can also be prepared by a cooling dissolution method. In the cooling dissolution method, the cellulose ester can be dissolved in an organic solvent that is difficult to dissolve by a normal dissolution method. In addition, even if it is a solvent which can melt | dissolve a cellulose ester with a normal melt | dissolution method, there exists an effect that a uniform solution can be obtained rapidly according to a cooling melt | dissolution method.

(Filtering process)
Various known filtration devices can be used for filtering the cellulose ester solution. That is, when roughly classified as a filter, it can be divided into a continuous filter and a batch pressure filter, and as a continuous filter, it can be divided into a belt type, a multiple disk type, a screw press type, a filter press type, etc. Examples of the batch pressure filter include a leaf type and a candle type.

A filter press device, a paper filter device, a leaf filter device, a drum filter device, a precoat filter device, or the like can be used. The industrially most advantageous product is a filter press apparatus, and the filter press apparatus may be pre-coated and used. As an example of the filter press apparatus, 40 to 50 plates of about 60 cm square are used, and a net is attached to each plate, and a filter paper or cotton cloth is installed between the nets. A plurality of these filter press apparatuses may be used for filtration in multiple stages.

Also, the leaf filter device can be suitably used.

As the filter material, a sintered metal filter, a non-woven metal filter, a cotton cloth filter, a paper filter, or the like may be used.

If it is a filter press type, the filter medium to be used can be a natural fiber or a synthetic fiber. In general, polypropylene, polyester (tetron), and nylon can be used as the material of the synthetic fiber used for the filter cloth. Vinylon, acrylic, saran, etc. can also be used depending on the solvent. Each of these materials has characteristics on the material and can be used according to the characteristics. If it is a natural fiber, cotton can be mentioned as a typical material. Monofilaments, multifilaments, spun yarns and the like can be used as the type of raw yarn used for the filter cloth. When a monofilament is used, the cake peelability is excellent and clogging is small, but there is a disadvantage that the fine particles are poorly captured. When multifilaments are used, the strongest filter cloth is obtained and the cake peelability is good. In the case of a spun yarn, cake peeling is poor and clogging is slightly faster. The filter cloth weave includes plain weave, twill weave, and satin weave. In the case of plain weave, particles are easily collected but clogging is accelerated. In the case of twill weave, a filter cloth having a good balance between collection and clogging can be obtained. In the case of satin weaving, particles are less clogged, but the ability to collect particles is poor. In the present invention, plain or twill filter cloth is suitable.

For cotton cloth filters, cotton flannel (No. 10 B, plain weave diameter No. 20 single yarn 63, weft No. 10 single yarn 46), gold width (No. 11, plain weave diameter No. 40 single yarn 100, weft No. 40 single yarn 98 pieces ), Thick twill (26, twill, 12-3, 64, 12-4, 32) may be used. In the paper filter, filter paper (300 g / m ² ) or the like may be used. These filter media may be used in combination (for example, the first filter media is one cotton flannel filter paper, the second filter media is two cotton flanks, one gold width, and the third filter media is one cotton flannel one filter paper and one gold width).

The retention average particle size (filtration accuracy) of the filter medium is preferably 1 to 50 μm, more preferably 1 to 20 μm, and most preferably 1 to 5 μm. Further, the standard deviation of the particle diameter is preferably 0.5 times or less of the average particle diameter, and more preferably 0.3 times or less of the average particle diameter. By using such a filter medium, filterability is improved and productivity is improved.

The bulk density of the filter aid is more preferably in the range of 0.1 to 0.5 g / cm ³ , and still more preferably in the range of 0.3 to 0.4 g / cm ³ . When the bulk density is smaller than this range, the gap of the cake becomes large and the filtration accuracy is lowered. Conversely, if the bulk density is large, the filtration resistance increases and the apparatus becomes large.

Further, the addition amount of the filter aid was regulated to 0.01 to 10% by mass with respect to the cellulose acylate solution. When the addition amount of the filter aid is smaller than this range, the clogging prevention effect by the filter aid is hardly obtained. Conversely, if the amount of filter aid added is large, the rate of increase in the thickness of the cake layer increases, and the resistance of the cake layer increases rapidly with this, so the cake must be washed and discharged frequently. Don't be. Therefore, the amount of filter aid added is preferably in the above range. The addition amount of the filter aid is more preferably in the range of 0.05 to 5% by mass, and further preferably in the range of 0.1 to 0.5% by mass.

The pressure in the filtration step can be appropriately set in consideration of the filtration efficiency. Specifically, the filter medium may be pressurized to 5 to 18 atmospheres (for example, 8 to 18 atmospheres, for example, 10 to 18 atmospheres). The shape of the cellulose mixed fatty acid ester composition obtained by dissolving cellulose ester in an organic solvent, filtering and drying may be a filament. In the step of dissolving the cellulose mixed fatty acid ester according to the present invention in an organic solvent and filtering, kaolin, titanium oxide, clay or the like may be used as a filter aid. The filtrate may be kept at a temperature of about 40 to 50 ° C. The filter medium may be pressurized to 5 to 18 atmospheres (eg, 8 to 18 atmospheres, eg, 10 to 18 atmospheres). Filtering is not performed once but multiple times (for example, the first filter medium is one cotton flannel, the second filter medium is two cotton flannels, one gold width, the third filter medium is one cotton flannel, one filter paper, one gold width, one filter medium structure) In the same configuration, the first filtration may be performed at 12 to 18 atm, the second filtration at 8 to 14 atm, and the third filtration at 5 to 9 atm). When the same filter medium configuration is used, the filtration pressure may be changed between the first time and the second time (for example, the second filtration is performed at a lower pressure).

The temperature at the time of filtration can be any temperature as long as filtration is possible, but it is preferably 30-100 ° C, more preferably 35-80 ° C, and even more preferably 40-70 ° C. This is preferable because the viscosity of the solution can be lowered.

The filtration pressure is preferably in the range of 0.001 MPa to 10 MPa, more preferably in the range of 0.001 MPa to 5 MPa, and more preferably in the range of 0.01 MPa to 1 MPa.

The type of filter aid is not particularly limited, but cellulose, diatomaceous earth, pearlite, activated carbon, and powdered charcoal are preferably used, and among them, diatomaceous earth is preferred.

For example, Celite (for example, Filter-Cel, Celite 505, Standard Super-Cel, Celite 512, Hyflo Super-Cel1, Celite 501 manufactured by Johns-Manville Sales Corp.) , Celite 535, Celite 545, Celite 560, etc.), Dicalite (Superref, UF, Speedflow, Special Speed, Speed, etc., manufactured by Grefco, Inco, USA) Radio lights (RADIOLITE # 100, RA manufactured by Showa Chemical Industry Co., Ltd. IOLITE # 200, RADIOLITE # 500, RADIOLITE # 600, RADIOLITE # 700, RADIOLITE # 900, RADIOLITE # 1100, RADIOLITE # 100), layered clay mineral (preferably talc, mica, kaolinite), silicon dioxide fine particles (for example, Silicon dioxide fine particles (for example, silica gel MB-300, MB-500 manufactured by Fuji Silysia Co., Ltd., Fuji Silica Gel AB Type, Fuji Silica Gel A Type, Fuji Silica Gel RD Type, BW-25K, Merck Silica Gel 40, Silica Gel 60, Silica Gel 100, etc.) These filter aids may be mixed with a cellulose ester solution and subjected to cake filtration. Was collected, the solution may be filtered cellulose ester is dissolved.

In the present invention, from the viewpoint of manifestation of the effects of the present invention, a filter aid and a filtration agent having an average particle diameter in the range of 5 to 20 μm and a particle diameter standard deviation of 0.5 times or less in average particle diameter. It is preferable to perform filtration using a filter having an accuracy in the range of 1 to 5 μm.

(Casting process)
The solution casting method used in the method for producing a film of the present invention is a glass plate or metal plate having a high smoothness after the dope is prepared in a glass or metal container and filtered after being carried out in a small amount. The film is cast to a desired film thickness on a support such as a small die or a doctor blade. After casting, primary drying is performed, and the film is peeled off from the support, framed as necessary, and post-dried.

In addition, when a film is obtained in a large amount, particularly continuously, a solution casting film forming method and a solution casting film forming apparatus conventionally used for producing a cellulose triacetate film can be used. The dope prepared in the dissolving machine (kettle) is filtered, and the dope is finally prepared. After that, the dope is sent from the dope discharge port to the pressure die through a pressure metering gear pump capable of delivering a constant amount of liquid with high accuracy, for example, by the rotational speed, and the dope is run endlessly from the die (slit) of the pressure die. The dope film (also referred to as a web) is peeled off from the support at a peeling point that is uniformly cast on the support (drum or band) and the support has almost gone around. Both ends of the obtained web are sandwiched between clips, transported by a tenter while keeping the width, dried, then transported by a roll group of a drying device, dried, and wound up to a predetermined length by a winder. The combination of the tenter and the roll group dryer varies depending on the purpose. The surface of the drum or band is preferably finished in a mirror state. The casting and drying methods in the solvent casting method are described in U.S. Pat. Nos. 2,336,310, 2,367,603, 2,492,078, 2,492,977. No. 2,492,978, No. 2,607,704, No. 2,739,069, No. 2,739,070, British Patent No. 640731 No. 736892, JP-B 45-4554, 49-5614, JP-A-60-176834, 60-203430, and 62-1115035. The dope is preferably cast on a drum or band adjusted to an arbitrary surface temperature.

In the case of a laminated film, a cellulose acylate film can be produced from two or more kinds of prepared cellulose ester solutions (dope) by a solvent cast method.

The dope is cast on a drum or band, and the solvent is evaporated to form a film. The dope before casting is preferably adjusted in concentration so that the solid content is 18 to 35% by mass. The surface of the drum or band is preferably finished in a mirror state. Regarding casting and drying methods in the solvent casting method, U.S. Pat. Nos. 2,336,310, 2,367,603, 2,429,078, 2,429,297, 2,429,978, 2,607,704, 2,37,069, 2,273,070, British Patent 6,407,331, It is described in each specification of JP-A-736892, JP-B-45-4554, JP-A-49-5614, JP-A-60-176834, JP-A-60-203430, and JP-A-62-115035.

The dope is preferably cast on a drum or band having a surface temperature of 10 ° C. or lower. After casting, it is preferable to dry it by applying air for 2 seconds or more. The obtained film can be peeled off from the drum or band and further dried with high-temperature air whose temperature is successively changed from 100 ° C. to 160 ° C. to evaporate the residual solvent. The above method is described in Japanese Patent Publication No. 5-17844. According to this method, it is possible to shorten the time from casting to stripping. In order to carry out this method, it is necessary for the dope to gel at the surface temperature of the drum or band during casting.

In the present invention, the obtained cellulose ester solution (dope) is formed by casting the two or more cellulose ester solutions on a smooth band or drum as a support. There is no restriction | limiting in particular as a manufacturing method of the film of this invention other than the above, A well-known co-casting method can be used. For example, a film may be produced by laminating and laminating a solution containing a cellulose ester from a plurality of casting openings provided at intervals in the traveling direction of the metal support. The methods described in JP-A Nos. 158414, 1-122419, and 11-198285 can be applied. A film may be formed by casting a cellulose ester solution from two casting ports. For example, JP-B-60-27562, JP-A-61-94724, JP-A-61-947245, It can be carried out by the methods described in JP-A Nos. 61-104813, 61-158413, and 6-134933. Also, the cellulose ester film casting method described in JP-A-56-162617 is a method of wrapping a flow of a high-viscosity cellulose ester solution with a low-viscosity cellulose ester solution and simultaneously extruding the high- and low-viscosity cellulose ester solution. Good. Furthermore, it is also a preferred embodiment that the outer solution described in JP-A-61-94724 and JP-A-61-94725 contains a larger amount of an alcohol component which is a poor solvent than the inner solution.

Alternatively, by using two casting ports, the film cast on the metal support is peeled off by the first casting port, and the second casting is performed on the side that is in contact with the metal support surface. Further, a film may be produced, for example, a method described in Japanese Patent Publication No. 44-20235. The cellulose ester solution to be cast may be the same solution or different cellulose ester solutions and is not particularly limited. In order to give a function to a plurality of cellulose ester layers, a cellulose ester solution corresponding to the function may be extruded from each casting port. Further, the cellulose ester solution according to the present invention can be cast simultaneously with other functional layers (for example, an adhesive layer, a dye layer, an antistatic layer, an antihalation layer, a UV absorbing layer, a polarizing layer). As a method for producing the film of the present invention, it is preferred that the film formation is simultaneous or sequential multilayer casting film formation.

In conventional single-layer liquids, it is necessary to extrude a high-concentration and high-viscosity cellulose ester solution to obtain the required film thickness. In this case, the stability of the cellulose ester solution is poor and solids are generated. In many cases, however, it becomes a problem due to a failure or poor flatness. As a solution to this, by casting multiple cellulose ester solutions from the casting port, a highly viscous solution can be extruded onto a metal support at the same time. In addition to being able to reduce the drying load by using a concentrated cellulose ester solution, the production speed of the film could be increased.

In the case of co-casting, the inner and outer thicknesses are not particularly limited, but preferably the outer side is preferably 0.2 to 50% of the total film thickness, more preferably 2 to 30%. . Here, in the case of co-casting with three or more layers, the total thickness of the layer in contact with the metal support and the layer in contact with the air side is defined as the outer thickness.

In the case of co-casting, a cellulose ester film having a laminated structure can be produced by co-casting cellulose ester solutions having different additive concentrations such as the above-mentioned plasticizer, ultraviolet absorber and matting agent. For example, a cellulose ester film having a structure of skin layer / core layer / skin layer can be produced. For example, the matting agent can be contained in the skin layer in a large amount or only in the skin layer. The plasticizer and the ultraviolet absorber can be contained in the core layer more than the skin layer, and may be contained only in the core layer. In addition, the type of plasticizer and ultraviolet absorber can be changed between the core layer and the skin layer. For example, the skin layer contains a low-volatile plasticizer and / or an ultraviolet absorber, and the core layer has excellent plasticity. It is also possible to add a plasticizer or an ultraviolet absorber excellent in ultraviolet absorption. Moreover, it is also a preferable aspect that a release agent is contained only in the skin layer on the metal support side. It is also preferable to add more alcohol, which is a poor solvent, to the skin layer than the core layer in order to cool the metal support by the cooling drum method to gel the solution. The Tg of the skin layer and the core layer may be different, and the Tg of the core layer is preferably lower than the Tg of the skin layer. Further, the viscosity of the solution containing the cellulose ester during casting may be different between the skin layer and the core layer, and the viscosity of the skin layer is preferably smaller than the viscosity of the core layer. It may be smaller than the viscosity.

(Drying process)
A method for drying a web that has been dried on a drum or belt and peeled off will be described. The web peeled at the peeling position just before the drum or belt makes one round is conveyed by alternately passing through a group of rolls arranged in a staggered manner, or the both ends of the peeled web are gripped by clips or the like and are not contacted. It is conveyed by the method of conveying it automatically. Drying is performed by a method of applying wind at a predetermined temperature to both sides of the web (film) being conveyed or a method using a heating means such as a microwave. Since rapid drying may impair the flatness of the film to be formed, it is preferable to dry at a temperature at which the solvent does not foam in the initial stage of drying, and to dry at a high temperature after the drying proceeds. In the drying process after peeling from the support, the film tends to shrink in the longitudinal direction or the width direction by evaporation of the solvent. Shrinkage increases with drying at higher temperatures. Drying while suppressing this shrinkage as much as possible is preferable for improving the flatness of the finished film. From this point, for example, as shown in Japanese Patent Application Laid-Open No. 62-46625, a method in which all or part of the drying process is performed while holding the width at both ends of the web with clips or pins in the width direction. (Tenter method) is preferred. The drying temperature in the drying step is preferably 100 to 145 ° C. The drying temperature, the amount of drying air, and the drying time vary depending on the solvent used, but may be appropriately selected according to the type and combination of the solvents used. In the production of the film of the present invention, the web (film) peeled from the support is preferably stretched when the amount of residual solvent in the web is less than 120% by mass.

The residual solvent amount can be expressed by the following formula.

Residual solvent amount (% by mass) = {(MN) / N} × 100
Here, M is the mass of the web at an arbitrary point in time, and N is the mass when the web of which M is measured is dried at 110 ° C. for 3 hours.

(Stretching process)
In the present invention, in order to improve the film performance, it may be positively stretched in the width direction. For example, JP-A-62-115035, JP-A-4-152125, JP-A-4-284221, The methods described in JP-A-4-298310 and JP-A-11-48271 can be applied. In many cases, the film is stretched at a temperature 10 to 20 ° C. higher than Tg (glass transition temperature). However, the film of the present invention has a high glass transition temperature and is heated to a temperature higher than the glass transition temperature. Decomposition may begin. In such a case, in the present invention, it is particularly effective to stretch the film of the present invention by treatment during drying. That is, by performing stretching in a state where the apparent glass transition temperature containing the solvent is low, stretching can be performed at a temperature at which the polymer does not decompose. As the stretching method, for example, in the case of stripping, the film is stretched by adjusting the speed of the film transport roller so that the film winding speed is higher than the film stripping speed. In the case of drying after peeling, the film is stretched by increasing the transport speed of the transport roller at the transport destination relative to the transport speed of the transport roller on the near side in the transport direction. Further, the film can be stretched in the width direction by conveying the film while holding the film with a tenter and gradually increasing the width of the tenter.

The stretching ratio of the film (the ratio of the length after stretching relative to the original length) is preferably 1.03 to 3 times, more preferably 1.05 to 2.5 times, and more preferably 1.05 to 1.8 times. At this time, the stretching direction may be the casting direction, may be stretched in a direction perpendicular to the casting direction, or may be stretched in both directions depending on circumstances. At this time, stretching may be performed simultaneously, or stretching in one direction and then stretching in another direction.

The winding machine relating to the production of the cellulose ester film in the present invention may be generally used, such as a constant tension method, a constant torque method, a taper tension method, a program tension control method with a constant internal stress, and the like. Can be rolled up. The thickness of the polymer film in the present invention (after drying) varies depending on the purpose of use, but is usually preferably in the range of 20 to 500 μm, more preferably in the range of 30 to 250 μm, particularly in the range of 30 to 150 μm. Most preferred. The film thickness may be adjusted by adjusting the solid content concentration contained in the dope, the slit gap of the die base, the extrusion pressure from the die, the support speed, and the like so as to obtain a desired thickness.

The stretching speed is preferably 5% / min to 1000% / min, more preferably 10% / min to 500% / min. The stretching is preferably performed by a heat roll or / and a radiant heat source (such as an IR heater) or warm air. Moreover, you may provide a thermostat in order to improve the uniformity of temperature. When uniaxial stretching is performed by roll stretching, L / W, which is a ratio of the distance between rolls (L) and the film width (W), is preferably 2.0 to 5.0. Furthermore, in order to prevent foaming of the tenter-dried web, improve detachability, and prevent dust generation, the width of the dryer should be set so that the hot air and heat source of the dryer do not hit the edges of the web in the dryer. However, it is also preferable that the length is shorter than the width of the web. Moreover, you may install a shielding board inside web both ends so that a hot air and a heat source may not hit a holding | maintenance part of a tenter.

The stretch ratio for the stretched film should be a predetermined thickness. Further, by stretching, it may be preferable that an improvement in planarity such as flatness can be achieved. Furthermore, in order to reduce the unevenness in thickness, by providing a gradient in the width direction of the stretching temperature, it may be possible to achieve more uniform stretching than stretching at a constant temperature.

(Description of optical member)
[Polarizer]
Since the cellulose ester film of the present invention has high optical expression, it is preferably used as a retardation film as a protective film for a polarizing plate. The polarizing plate is formed by laminating and laminating a protective film on at least one surface of the polarizer. A conventionally known polarizer can be used. For example, a hydrophilic polymer film such as a polyvinyl alcohol film is treated with a dichroic dye such as iodine and stretched. The bonding of the cellulose ester film and the polarizer is not particularly limited, but can be performed with an adhesive made of an aqueous solution of a water-soluble polymer. The water-soluble polymer adhesive is preferably a completely saponified polyvinyl alcohol aqueous solution.

The film of the present invention is a protective film for polarizing plate / polarizer / protective film for polarizing plate / liquid crystal cell / film of the present invention / polarizer / protective film for polarizing plate, or protective film for polarizing plate / polarizer / It can use preferably by the structure of the film / liquid crystal cell of this invention / film of this invention / polarizer / protective film for polarizing plates. In particular, by bonding to a liquid crystal cell such as a TN type, a VA type, or an OCB type, it is possible to provide a display device that is further excellent in viewing angle and visibility with little coloring. In particular, a polarizing plate using the protective film for a polarizing plate according to the present invention has little deterioration under high temperature and high humidity conditions, and can maintain stable performance for a long time.

[Liquid Crystal Display]
The cellulose ester film of the present invention and the polarizing plate using the film can be used for liquid crystal cells and liquid crystal display devices in various display modes. TN (Twisted Nematic), IPS (In-Plane Switching), FLC (Ferroelectric Liquid Crystal), AFLC (Anti-Frequential Liquid Nyst) Various display modes such as HAN (Hybrid Aligned Nematic) have been proposed.

The OCB mode liquid crystal cell is a liquid crystal display device using a bend alignment mode liquid crystal cell in which rod-like liquid crystalline molecules are aligned in a substantially opposite direction (symmetrically) between the upper part and the lower part of the liquid crystal cell. OCB mode liquid crystal cells are disclosed in US Pat. Nos. 4,583,825 and 5,410,422. Since the rod-like liquid crystal molecules are aligned symmetrically between the upper part and the lower part of the liquid crystal cell, the bend alignment mode liquid crystal cell has a self-optical compensation function. The bend alignment mode liquid crystal display device has an advantage of high response speed.

In a VA mode liquid crystal cell, rod-like liquid crystal molecules are aligned substantially vertically when no voltage is applied.

The VA mode liquid crystal cell includes: (1) a narrowly defined VA mode liquid crystal cell in which rod-like liquid crystalline molecules are aligned substantially vertically when no voltage is applied, and substantially horizontally when a voltage is applied (Japanese Patent Laid-Open No. Hei 2-). (2) described in (2) liquid crystal cell (SID97, Digest of tech. Papers 28 (1997) 845 with VA mode multi-domain (MVA mode) for viewing angle expansion. ), (3) a liquid crystal cell (n-ASM mode) in which rod-like liquid crystalline molecules are substantially vertically aligned when no voltage is applied and twisted multi-domain alignment is applied when a voltage is applied (Sharp Technical Report No. 80, page 11); (4) A SURVAVAL mode liquid crystal cell (Monthly Display May 14th page (1999)) is included.

The VA mode liquid crystal display device comprises a liquid crystal cell and two polarizing plates disposed on both sides thereof. The liquid crystal cell carries a liquid crystal between two electrode substrates. In one aspect of the transmission type liquid crystal display device of the present invention, the film of the present invention is disposed between the liquid crystal cell and one polarizing plate, or between the liquid crystal cell and both polarizing plates. Arrange two.

In another aspect of the transmissive liquid crystal display device according to the present invention, an optical compensation sheet made of the film of the present invention is used as a transparent protective film for a polarizing plate disposed between a liquid crystal cell and a polarizer. The above optical compensation sheet may be used only for the protective film (between the liquid crystal cell and the polarizer) of one polarizing plate, or two (between the liquid crystal cell and the polarizer) of both polarizing plates. You may use said optical compensation sheet for a sheet of protective film. When the optical compensation sheet is used for only one polarizing plate, it is particularly preferable to use it as a protective film for the liquid crystal cell side of the backlight side polarizing plate of the liquid crystal cell. For the lamination to the liquid crystal cell, the film of the present invention is preferably on the VA cell side. The protective film may be a normal cellulose ester film, and is preferably thinner than the film of the present invention. For example, 40 to 80 μm is preferable, and examples thereof include, but are not limited to, commercially available KC4UY (40 μm manufactured by Konica Minolta Opto), KC5UX (60 μm manufactured by Konica Minolta Opto), TD80 (80 μm manufactured by Fujifilm), and the like.

Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto. “Part” described below represents “part by mass”.

Example 1
(Dope preparation)
<1-1> Cellulose Ester Solution The following composition was placed in a mixing tank, stirred to dissolve each component, and further heated at 90 ° C. for about 10 minutes. Celite (average particle size 10 μm, particle size standard deviation 3 μm) was used as a filter aid. 0.2% of this filter aid was added to the cellulose ester solution for body feed. Further, a precoat solution having an end speed of 10 ⁻³ cm / s was prepared for precoat, and a precoat layer having a thickness of 2 mm and 0.8 kg / m ² was formed. Then, filtration was started at a filtration flow rate of 0.4 cm / hr and an initial pressure of 0.3 MPa, and filtration was performed until the final thickness of the cake layer was 40 mm. As the support for the cake layer, a sintered metal filter having an average filtration accuracy of 3 μm was used.

Cellulose ester 1 listed in Table 3 100 parts by mass Additive 1 10 parts by mass Dichloromethane 406 parts by mass Methanol 61 parts by mass In addition, the cellulose ester resin and various additives used as the raw material of the dope were previously prepared by Nara Machinery Co., Ltd. A product obtained by drying at 120 ° C. for 2 hours using a silo made by the method was used.

(Casting)
The above dope was cast using a band casting machine. After drying at a supply temperature of 80 to 130 ° C. (exhaust temperature is 75 to 120 ° C.) on the band, a film peeled off from the band with a residual solvent amount of 25 to 35% by mass is supplied to a supply temperature of 130 ° C. (exhaust temperature). A cellulose ester film was produced by stretching in the width direction at a stretching ratio of 30% in a tenter zone having a temperature ranging from 90 to 125 ° C. At this time, the cast film thickness was adjusted so that the film thickness after stretching was 45 μm.

For the purpose of producing films having the compositions shown in Tables 3, 4, 5, and 6 and judging the suitability for production, a roll having a roll width of 2.5 m and a film length of 5000 m was produced. It was. Moreover, the residual solvent amount of the obtained film was 0.01 mass%.

[Example 2, Comparative Examples 11 to 14]
As described in Tables 3, 4, 5, and 6, films of each example and comparative example were obtained in the same manner as in Example 1 except that cellulose ester, additives, filter aids, filters, and the like were changed. It was. In addition, the content of the additive 1 described in Table 4 is as follows.

Additive 1: Succinic acid / adipic acid / ethylene glycol copolymer. Copolymerization ratio 3: 2: 5. Molecular weight 2000.

[Example 3]
The following composition was put into a mixing tank, stirred to dissolve each component, and further heated at 90 ° C. for about 10 minutes. Celite (average particle size 5 μm, particle size standard deviation 1.5 μm) was used as a filter aid. 0.2% of this filter aid was added to the cellulose ester solution for body feed. Further, a precoat solution having an end speed of 10 ⁻³ cm / s was prepared for precoat, and a precoat layer having a thickness of 2 mm and 0.8 kg / m ² was formed. Then, filtration was started at a filtration flow rate of 0.4 cm / hr and an initial pressure of 0.3 MPa, and filtration was performed until the final thickness of the cake layer was 40 mm. As the support for the cake layer, a sintered metal filter having an average filtration accuracy of 2 μm was used.

(Adjustment of cellulose ester dope for core layer)
Cellulose ester resin: those listed in Table 3 100 parts by mass Additive 1: those listed in Table 4 Amounts listed in Table 4 (unit: parts by mass)
Dichloromethane 406 parts by mass Methanol 61 parts by mass (adjustment of cellulose ester dope for skin B layer)
Cellulose ester resin: those listed in Table 3 100 parts by mass Additive A: those listed in Table 5 Amounts listed in Table 5 (unit: parts by mass)
Matting agent: silica particles having an average particle diameter of 16 nm (aerosil R972)
Nippon Aerosil Co., Ltd.) 0.05 parts by weight Peeling accelerator: partial ethyl ester compound of citric acid 0.05 parts by weight dichloromethane 406 parts by weight methanol 61 parts by weight (adjustment of cellulose ester dope for skin A layer)
Cellulose ester resin: those listed in Table 3 100 parts by mass Additive A: those listed in Table 5 Amounts listed in Table 5 (unit: parts by mass)
Matting agent: silica particles having an average particle diameter of 16 nm (aerosil R972)
Nippon Aerosil Co., Ltd.) 0.05 parts by weight Dichloromethane 406 parts by weight Methanol 61 parts by weight When dope is cast, as shown in FIG. The dope was cast together. Here, the core layer is made thickest by adjusting the casting amount of each dope, and as a result, simultaneous multilayer casting is performed so that the film thickness of the stretched film becomes the value shown in Table 4 below. Formed.

Next, this cast film was peeled off from the cast band, widened to a stretch rate of 30% using a tenter, and then relaxed at 140 ° C. for 60 seconds. Thereafter, the film was sent to a drying chamber and sufficiently dried while being conveyed while being wound around a roller.

Thus, a laminated cellulose ester film 3 having a dry film thickness of 45 μm was obtained.

[Examples 4 to 10, 15, 16, 20 and Comparative Examples 17 to 19]
As described in Table 3 and Tables 4 to 6 below, in the same manner as in Example 3 except that the cellulose ester, additive, film thickness, filter aid, filter, etc. were changed, A film was obtained.

In addition, the content of the additive A described in Table 5 is as follows.
Additive A: [Chemical Formula 3] I- (2)

(Evaluation)
(Number of foreign objects on the film)
After arranging two polarizing plates on both sides of the film to block the transmitted light, irradiate light from one side, and observe from the opposite side with an optical microscope at a magnification of 150 times, and the diameter in terms of circle within 100 mm ² is 60-100 μm The number of bright spot foreign matter within the range of 10 to 50 μm was counted, and this was taken as the number of foreign matters on the film.

(Measure haze)
Using a turbidimeter (NDH2000, Nippon Denshoku Industries Co., Ltd.), haze measurement of the film was performed in the same environment for 23 hours at 23 ° C. and 55% RH.

First, the blank haze 1 of a measuring instrument other than a film is measured.
1. Drip a drop (0.05 ml) of glycerin on a cleaned glass slide. At this time, care is taken so that bubbles do not enter the droplet. Be sure to use glass that has been cleaned with a detergent because it may look dirty even if it looks clean.
2. Place the cover glass on top of it. Glycerin spreads without pressing the cover glass.
3. Set on a haze meter and measure blank haze 1. Next, the haze 2 including the sample is measured.
4). Glycerin (0.05 ml) is dropped on a slide glass.
5. A sample film to be measured is placed thereon.
6). Glycerin (0.05 ml) is dropped on the sample film.
7. Place the cover glass on top of it.
8). Set in a haze meter and measure haze 2.
9. (Haze 2) − (Haze 1) = (Internal haze according to the present invention) is calculated.

The glass and glycerin used in the above measurement are as follows.
Glass: MICRO SLIDE GLASS S9213 MATUNAMI
Glycerin: Deer special grade manufactured by Kanto Chemical Co., Ltd. The above measurement results are shown in Table 6.

As is clear from the results shown in Table 6, it can be seen that the cellulose ester film according to the present invention exhibits high transparency.

<Preparation of polarizing plate>
Using the cellulose ester films 1 to 20 obtained in the respective examples and comparative examples, polarizing plates were produced by the following method.

A 120 μm thick polyvinyl alcohol film 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, according to the following steps 1 to 5, a polarizer, the cellulose ester films 1 to 20, and a commercially available cellulose ester film (KC4UY, manufactured by Konica Minolta Opto Co., Ltd.) are bonded as a polarizing plate protective film on the back side. A plate was made.

Step 1: Cellulose ester films 1 to 20 were immersed in a 2 mol / l potassium hydroxide solution at 50 ° C. for 30 seconds, then washed with water and dried to obtain a cellulose ester film having a saponified surface.

Step 2: The polarizer was immersed in a polyvinyl alcohol adhesive tank having a solid content of 2% by mass for 1 to 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, and further placed on the back side cellulose ester film.

Step 4: The cellulose ester films 1 to 20, the polarizer and the back side cellulose ester film laminated in Step 3 were bonded at a pressure of 20 to 30 N / cm ² and a conveying speed of about 2 m / min.

Step 5: A sample obtained by bonding the polarizer prepared in Step 4 with the cellulose ester films 1 to 20 and the back side cellulose ester film in a drier at 80 ° C. was dried for 2 minutes to prepare a polarizing plate.

<Production of liquid crystal display device>
A liquid crystal panel for viewing angle measurement was produced as follows, and the characteristics as a liquid crystal display device were evaluated.

Remove the polarizing plates on both sides of the VA mode type liquid crystal display device (Sony BRAVIAV1, 40-inch type) previously bonded, and place the prepared polarizing plate on the glass surface of the liquid crystal cell on the cellulose ester film 1-20 side. It was pasted on both sides.

At that time, the liquid crystal display devices 101 to 120 were manufactured by performing the absorption axis in the same direction as the polarizing plate bonded in advance.

The liquid crystal display device was evaluated for contrast, and the results are shown in Table 7.

<Evaluation of liquid crystal display device>
[Front contrast]
The contrast characteristic of the liquid crystal display device was evaluated by using EZ-contrast 160D manufactured by ELDIM, the luminance from the normal direction of the display screen of white display and black display was measured with the 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)
The evaluation rank of contrast was determined as follows.
A: 1100 to 1200 or more ○: 1000 to less than 1100 ×: less than 1000 ○ If it is greater than or equal to ○, there is no practical problem.

The evaluation results are shown in Table 7.

From the results shown in Table 7, it can be seen that the liquid crystal display device using the cellulose ester film of the present invention has high contrast.

DESCRIPTION OF SYMBOLS 10 Co-casting die 11

Base part

13, 15 Surface layer slit 14 Base layer slit 16 Metal support 17, 19 Surface layer dope 18 Base layer dope 20 Multi-layer structure web 21 Skin B layer 22 Core layer 23 Skin A layer

Claims

A cellulose ester film containing a cellulose ester having an acyl group having a carbon number in the range of 2 to 4 and an acyl group substitution degree in the range of 2.0 to 2.5, and having a diameter in terms of a circle Is 10 or less per 10 cm square, and 10 or less foreign matter is 10 to 50 μm in diameter, and the internal haze is 0.1 or less. And a cellulose ester film having a thickness in the range of 20 to 50 μm.
2. A cellulose ester film in which a core layer containing a cellulose ester satisfying the following formula (1) and a skin B layer containing a cellulose ester satisfying the following formula (2) are laminated and formed: The cellulose ester film as described.
Formula (1): 2.0 <Z 1 <2.5
(In the formula (1), Z 1 represents a total acyl group substitution degree of the cellulose ester of the core layer.)
Formula (2): 2.7 <Z 2 <3.0
(In the formula (2), Z 2 represents a total acyl group substitution degree of the cellulose ester of the skin layer.)
The skin A layer containing a cellulose ester satisfying the following formula (2) is provided on the surface opposite to the surface on which the skin B layer of the core layer formed by lamination is present. The cellulose ester film according to claim 2.
Formula (2): 2.7 <Z 2 <3.0
(In the formula (2), Z 2 represents a total degree of acyl substitution of the cellulose ester of the skin layer.)
The length of the film is in the range of 5000 to 10000 m, and the width of the film is in the range of 1.9 to 2.5 m. The cellulose ester film described in 1.
Filtering using a filter aid having an average particle size in the range of 5 to 20 μm, a particle size standard deviation of 0.5 times or less of the average particle size, and a filter having a filtration accuracy in the range of 1 to 5 μm The cellulose ester film according to any one of claims 1 to 4, wherein the cellulose ester film is produced through a process.
A method for producing a cellulose ester film for producing a cellulose ester film according to any one of claims 1 to 5, wherein the average particle size is in the range of 5 to 20 µm, and the particle size standard deviation is A method for producing a cellulose ester film, comprising a step of filtering using a filter aid having a mean particle size of 0.5 times or less and a filter having a filtration accuracy within a range of 1 to 5 μm.
A polarizing plate comprising the cellulose ester film according to any one of claims 1 to 5.
A liquid crystal display device comprising the cellulose ester film according to any one of claims 1 to 5.