JP2003033998A - Cellulose ester film, manufacturing method therefor, optical film using the same, polarizing plate and display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical film for a display device providing a high quality polarizing plate or laminated article having an excellent moisture permeability, dimensional stability and low haze, and hardly having irregularity in drying or creases when a polarizing protective film and a polarizer are bonded with an adhesive in a cellulose ester film with a multilayer structure having a layer containing a high concentrated non-phosphoric plasticizer, and a manufacturing method therefor. SOLUTION: The cellulose ester film with multiple layers has at least a base layer and a surface layer, and contains at least minute particles in the one side surface layer, and the non-phosphoric plasticizer and an ultraviolet absorbent in the base layer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cellulose ester film used for optical films, polarizing plates, display devices and the like and a method for producing the same.

[0002]

2. Description of the Related Art In recent years, personal computers, word processors, liquid crystal displays used in watches and calculators, plasma displays, and organic ELs have been increasingly used in harsh environments. Therefore, of course, optical films such as polarizing plates, polarizing plate protective films, retardation films, front filters for plasma display panels, front films for organic EL panels and the like used in display devices such as liquid crystal displays used for this are also severe. Durability such as no deterioration under high temperature and high humidity and excellent dimensional stability is required so that the characteristics do not change even in an environment.

The polarizing plate used for the above liquid crystal display has a structure in which a protective film is adhered to a polarizing film and one or both surfaces thereof, and the protective film is cellulose having good light transmittance and small birefringence. Triacetate (TAC) is commonly used. Since the characteristics of this protective film dominate the durability of the polarizing plate, the protective film has good wet heat resistance such as no deterioration under high temperature and high humidity and excellent dimensional stability. Is naturally required.

The conventional protective film of cellulose triacetate contains a plasticizer such as phosphoric acid ester in the protective film in order to impart appropriate flexibility to the film. However,
When such a polarizing plate is used under high temperature and high humidity, problems such as cracking of the protective film, peeling of the protective film from the polarizing film, and coloring of the protective film may occur.

In order to solve the above problems, a polarizing plate using a protective film in which the amount of a plasticizer such as phosphoric acid ester is reduced has been proposed (Japanese Patent Laid-Open No. 61-243407). Further, a polarizing plate using a protective film containing no plasticizer has been proposed (JP-A 1-214802), but none of them is sufficient. Further, JP-A-8-207210 proposes a method of using cellulose acetate having different acetylation degrees, but it is not sufficient. In addition, Japanese Patent Laid-Open No. 2001-
No. 71418 describes that a matting agent is added to the surface layer and not to the base layer at all.
No. 54936 shows that the bleed-out additive is added only to the base layer. However, these do not have satisfactory moisture permeability.

[0006]

DISCLOSURE OF THE INVENTION The present invention is a cellulose ester film having a multilayer structure having a layer containing a high concentration of a non-phosphate ester plasticizer, which has excellent moisture permeability and dimensional stability and low haze, Provided is an optical film for a display device or a method for producing the same, which is resistant to drying unevenness or wrinkles when a polarizing plate protective film and a polarizer are bonded by an adhesive, and which gives a high-quality polarizing plate or a laminate. That is.

[0007]

The above object of the present invention can be achieved by the following means.

(1) A cellulose ester film having a multilayer structure having at least a base layer and a surface layer, wherein at least one surface layer contains fine particles, and the base layer contains a non-phosphate ester plasticizer and an ultraviolet absorber. A cellulose ester film characterized by:

(2) A cellulose ester film having a multilayer structure having at least a base layer and a surface layer, wherein at least one surface layer contains fine particles, and the base layer has three or more aromatic rings or cycloalkyl rings in the molecule. A cellulose ester film containing an additive.

(3) The cellulose ester film according to (2), wherein the additive is a non-phosphate ester plasticizer or an ultraviolet absorber.

(4) The content of the non-phosphate ester plasticizer in the surface layer is less than 10% by mass, the content of the non-phosphate ester plasticizer in the base layer is 10 to 30% by mass, and the content of the surface layer and the base layer is The cellulose ester film according to (1) or (3), wherein the difference in the added amount is 2 to 30% by mass.

(5) The total content of the additives in the surface layer is less than 10% by mass, the total content of the additives in the base layer is 10 to 30% by mass, and the difference between the total addition amounts of the surface layer and the base layer is It is 5 to 30 mass%, The cellulose ester film of (2) description characterized by the above-mentioned.

(6) The content of the fine particles in at least one surface layer is 0.1% by mass or more, and the content of the fine particles in the base layer is less than 0.01% by mass.
The cellulose ester film according to any one of (5).

(7) The film thickness is 10 to 60 μm, 25 ° C.,
Water vapor transmission rate at 90% RH is 20 to 250 g / m ² ; 2
It is 4 hours, The cellulose-ester film in any one of (1)-(6) characterized by the above-mentioned.

(8) A method for producing a cellulose ester film having a multilayer structure having at least a base layer and a surface layer by a solution casting method, wherein the primary particle diameter is 1 to 20 in the dope.
nm dope for the surface layer containing 0.02% by mass or more of the non-phosphate ester plasticizer in an amount of 0 to less than 2% by mass, and 2 to 10% by mass of the non-phosphate ester plasticizer. A method for producing a cellulose ester film, which comprises co-casting or sequentially casting a base layer dope.

(9) The method for producing a cellulose ester film according to (8), wherein the non-phosphate ester plasticizer has three or more aromatic rings or cycloalkyl rings in the molecule.

(10) A method for producing a cellulose ester film having a multilayer structure having at least a base layer and a surface layer by a solution casting method, wherein the drying time on the cast support is 30 to 120 seconds. (8) or the manufacturing method of the cellulose ester film of (9) characterized by the above-mentioned.

(11) An optical film using the cellulose ester film described in any one of (1) to (6) above.

(12) A polarizing plate comprising the cellulose ester film according to any one of (1) to (6) above.

(13) A display device using the optical film as described in (11) above.

The present invention is characterized by containing a non-phosphate ester plasticizer and an additive such as an ultraviolet absorber in the base layer and containing fine particles in the surface layer. The content of these additives in the base layer is preferably 10% by mass or more, and more preferably 13 to 30% by mass. In the present invention, unless otherwise specified, the content is based on the solid content in the film. This can reduce the moisture permeability of the cellulose ester film.

In the present invention, as the non-phosphate ester type plasticizer, an aliphatic polyhydric alcohol ester or three aromatic rings (eg, benzene ring) or cycloalkyl rings (eg, cyclohexane ring) in the molecule are used. The non-phosphate ester plasticizer having the above is preferably used. The aromatic ring or cycloalkyl ring as used herein may contain only either the aromatic ring or the cycloalkyl ring, and has both the aromatic ring and the cycloalkyl ring at the same time. May be. In addition, 3 in these molecules
There is no particular upper limit on the number of aromatic rings or cycloalkyl rings with one having at least one aromatic ring or cycloalkyl ring, but it is preferably 20 or less, more preferably 1
It is 0 or less. These aromatic rings (for example, benzene ring etc.) or cycloalkyl rings (for example, cyclohexane ring etc.) may have an arbitrary substituent.

In the present invention, fine particles are added to the surface layer in order to impart slipperiness. However, when fine particles are added to the surface layer, this may cause a film failure or increase haze. The amount of the fine particles added to the surface layer is preferably 0.1% by mass or more, more preferably 0.15% by mass or more for imparting slipperiness.
When the content is more than 10% by mass, failures on the film surface tend to increase. Further, when the content is 0.12% by mass or more, the tendency becomes strong, and particularly when 0.15% by mass or more. As a result of extensive studies to solve this problem, aliphatic polyhydric alcohol ester type or has three or more aromatic rings (eg, benzene ring) or cycloalkyl rings (eg, cyclohexane ring) in the molecule. It has been found that it is effective to set the addition amount of the non-phosphate ester plasticizer to less than 10% by mass. Although the reason is not completely clear, it is considered that the reduction of the addition amount of the non-phosphate ester plasticizer makes it difficult for the fine particles to agglomerate. Therefore, the amount of the non-phosphate ester plasticizer added to the surface layer is particularly preferably less than 10% by mass, more preferably less than 5% by mass, and particularly preferably 0 to 2% by mass.

By the way, an aliphatic polyhydric alcohol ester-based plasticizer or a non-phosphate ester plasticizer having three or more aromatic rings (eg, benzene rings) or cycloalkyl rings (eg, cyclohexane rings) in the molecule or It has been found that in a cellulose ester film containing an ultraviolet absorber and having reduced moisture permeability, drying unevenness or wrinkles are likely to occur when the polarizing plate protective film and the polarizer are bonded together. As a result of extensive studies to solve this problem, as a result, an aliphatic polyhydric alcohol ester system added to the surface layer or an aromatic ring (eg, benzene ring) or cycloalkyl ring (eg, cyclohexane ring) in the molecule has been added. It has been found that it is effective to set the total content of the non-phosphate ester plasticizer or the ultraviolet absorber having three or more) to less than 10% by mass. Although the cause is not clear, it is presumed that it is effective that the surface of the cellulose ester film has high moisture permeability or high water absorption. In particular, an aliphatic polyhydric alcohol ester-based or non-phosphate ester plasticizer or ultraviolet absorber having three or more aromatic rings (eg, benzene ring) or cycloalkyl rings (eg, cyclohexane ring) in the molecule is used. When used, the water vapor permeability is remarkably reduced, but it is considered preferable that the surface layer has a property of easily absorbing water. More preferably, the total content of these non-phosphate ester plasticizers or ultraviolet absorbers in the surface layer is less than 5% by mass, and particularly preferably 0 to 2% by mass. The difference in the total content between the base layer and the surface layer is preferably 5 to 30% by mass. As a result, even in the case of a cellulose ester film whose moisture permeability was reduced by the non-phosphate ester plasticizer and the ultraviolet absorber, it was possible to significantly reduce unevenness in dryness or wrinkles when it was attached to a polarizer or the like.

The present invention will be described in more detail below. The plasticizer used in the present invention is an aliphatic polyhydric alcohol ester type or non-phosphate ester type plasticizer. It does not substantially contain a phosphate ester plasticizer having a phosphate ester structure in the molecule such as triphenyl phosphate and tricresyl phosphate. Substantially means a content of less than 1%, more preferably less than 0.1% by mass, and most preferably not contained at all.

80 when the phosphoric acid ester plasticizer is contained
It is not preferable because it has a function of decomposing the cellulose ester under high temperature and high humidity conditions such as ° C and 90% RH.

As the non-phosphate ester plasticizer, an ester having three or more aromatic rings (eg, benzene ring) or cycloalkyl rings (eg, cyclohexane ring) in the molecule, or an aliphatic polyhydric alcohol Esters are preferably used.

Examples of the ester having three or more aromatic rings (eg, benzene ring) or cycloalkyl rings (eg, cyclohexane ring) in the molecule include, for example, phthalic acid ester, citric acid ester, glycolic acid ester. , Fatty acid ester, pyromellitic acid ester, trimellitic acid ester and the like. For example, dibenzyl phthalate, dibenzyl isophthalate, dibenzyl terephthalate, diphenyl phthalate, diphenyl isophthalate, diphenyl terephthalate, dicyclohexyl phthalate, dicyclohexyl isophthalate, dicyclohexyl terephthalate, phenyl cyclohexyl isophthalate, phenyl cyclohexyl terephthalate, phenyl cyclohexyl phthalate, benzyl cyclohexyl Examples thereof include phthalic acid esters such as phthalate, benzylcyclohexyl terephthalate, and benzylcyclohexyl isophthalate, but are not limited thereto.

Abietic acid, dehydroabietic acid, parastophosphoric acid, KE-604 (manufactured by Arakawa Kagaku), KE-8
5 (manufactured by Arakawa Chemical), Araldide EPN1139 (manufactured by Asahi Chiba Co., Ltd.), Araldide GY260 (Asahi Chiba Co., Ltd.)
(Made by Hitachi Chemical Co., Ltd.), Hirac 110H (made by Hitachi Chemical Co., Ltd.), Hirac 111 (made by Hitachi Chemical Co., Ltd.)
Ketone resins and the like are also preferably used.

The aliphatic polyhydric alcohol ester preferably used in the present invention is an ester of a dihydric or higher polyhydric alcohol and one or more monocarboxylic acids.

The polyhydric alcohol is represented by the following general formula (A). In formula (A) R _1- (OH) _n , R ₁ represents an n-valent aliphatic organic group, and n represents a positive integer of 2 or more.

Examples of the n-valent aliphatic organic group include an alkylene group (eg, methylene group, ethylene group, trimethylene group, tetramethylene group, etc.) and alkenylene group (eg,
Ethenylene group etc.), alkynylene group (eg ethynylene group etc.), alkanetriyl group (eg 1,2,3-
Propanetriyl group). The n-valent aliphatic organic group includes those having a substituent (for example, a hydroxy group, an alkyl group, a halogen atom, etc.). n is preferably 2 to 20.

Examples of preferred polyhydric alcohols include adonitol, arabitol, ethylene glycol, triethylene glycol, tetraethylene glycol, 1,
2-propanediol, 1,3-propanediol, dipropylene glycol, tripropylene glycol,
1,2-butanediol, dibutylene glycol, 1,
2,4-butanetriol, 1,5-pentanediol, 1,6-hexanediol, hexanetriol,
Examples thereof include sorbitol, galactitol, mannitol, trimethylolpropane, trimethylolethane, xylitol and the like. In particular, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol, sorbitol, trimethylolpropane and xylitol are preferable.

The monocarboxylic acid in the polyhydric alcohol ester is not particularly limited, and known aliphatic monocarboxylic acids, alicyclic monocarboxylic acids, aromatic monocarboxylic acids and the like can be used. It is preferable to use an alicyclic monocarboxylic acid or an aromatic monocarboxylic acid in terms of improving moisture permeability and retention.

Examples of preferable monocarboxylic acid include the followings, but the present invention is not limited thereto.

The aliphatic monocarboxylic acid has 1 carbon atom.
A fatty acid having a straight chain or side chain of ˜32 can be preferably used. The carbon number is more preferably 1 to 20, and particularly preferably 1 to 10. It is preferable to contain acetic acid because the compatibility with cellulose ester is increased, and it is also preferable to use acetic acid and another monocarboxylic acid as a mixture.

The preferred aliphatic monocarboxylic acid is
Acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, 2-
Ethyl-hexanecarboxylic acid, undecylic acid, lauric acid, tridecylic acid, myristic acid, pentadecyl acid, palmitic acid, heptadecyl acid, stearic acid, nonadecanoic acid, arachidic acid, behenic acid, lignoceric acid, serotic acid, heptacosanoic acid, montanic acid Saturated fatty acids such as melissic acid and laxeric acid, undecylenic acid, oleic acid,
Examples thereof include unsaturated fatty acids such as sorbic acid, linoleic acid, linolenic acid, and arachidonic acid. These may further have a substituent.

Examples of preferable alicyclic monocarboxylic acid include cyclopentanecarboxylic acid, cyclohexanecarboxylic acid, cyclooctanecarboxylic acid, and derivatives thereof.

Preferred examples of the aromatic monocarboxylic acid include benzoic acid, toluic acid and other benzoic acid having a benzene ring to which an alkyl group is introduced, and biphenylcarboxylic acid, naphthalenecarboxylic acid, tetralincarboxylic acid and the like. Examples thereof include aromatic monocarboxylic acids having two or more, or derivatives thereof. Benzoic acid is particularly preferable.

The molecular weight of the polyhydric alcohol ester used in the present invention is not particularly limited, but is preferably 300 to 1500, more preferably 350 to 750. In terms of retention, the larger the better, the more breathable,
From the viewpoint of compatibility with cellulose ester, the smaller one is preferable.

The carboxylic acid in the polyhydric alcohol ester of the present invention may be one kind or a mixture of two or more kinds. Further, all the OH groups in the polyhydric alcohol may be esterified, or a part thereof may be left as it is. It is preferable to have three or more aromatic rings or cycloalkyl rings (eg, cyclohexane ring) in the molecule.

Examples of non-phosphate ester plasticizers (including polyhydric alcohol esters) having 3 or more aromatic rings or cycloalkyl rings in the molecule used in the present invention are shown below.

[0043]

[Chemical 1]

[0044]

[Chemical 2]

[0045]

[Chemical 3]

[0046]

[Chemical 4]

[0047]

[Chemical 5]

Further, examples of polyhydric alcohol ester-based plasticizers other than the above are shown below.

[0049]

[Chemical 6]

[0050]

[Chemical 7]

[0051]

[Chemical 8]

The amount of the non-phosphate ester plasticizer used is preferably 3 to 30% by mass, more preferably 5 to 25% by mass, and particularly preferably 5 to 20% by mass, based on the cellulose ester.

JP-A-11-124445 and 11-9.
2574, 11-246704, 11-635.
No. 60, the non-phosphate ester plasticizers described in JP 2001-48840 A can also be used. These are preferably used alone or in combination.

When a cellulose ester film containing a high concentration of a non-phosphate ester plasticizer is used as a polarizing plate protective film, it tends to be uneven in dryness or wrinkles when the polarizer and the polarizing plate protective film are bonded together. There was found. Especially moisture vapor transmission rate (25 ℃, 90% RH) is 250g /
It is recognized when using a cellulose ester film of less than m ² · 24 hr, and especially the water vapor transmission rate is 220 g / m ² · 2.
It became remarkable when a cellulose ester film having a low moisture permeability of less than 4 hr was used. As a result of extensive studies to solve this problem, the base layer contains a high concentration of non-phosphate ester plasticizer, and the addition amount of the non-phosphate ester plasticizer in the surface layer to be bonded in contact with the polarizer It has been found effective to reduce

In particular, it is preferable to use an additive having three or more aromatic rings (eg, benzene ring, naphthalene ring, etc.) or cycloalkyl rings (eg, cyclohexane ring, etc.) per molecule in order to improve the moisture permeability of the cellulose ester film. It is effective for reducing the amount, and in that case, it is extremely preferable to reduce the addition amount of the surface layer rather than the base layer because it is less likely to cause unevenness in drying and wrinkles when the polarizer and the cellulose ester film are bonded. As the additive having three or more aromatic rings or cycloalkyl rings (for example, cyclohexane ring etc.) per molecule, a non-phosphate ester plasticizer or an ultraviolet absorber is particularly exemplified. The aromatic ring is a benzene ring or a naphthalene ring which may have a substituent, and a cycloalkyl ring (for example, a cyclohexane ring etc.) may also have a substituent. The substituent is not particularly limited, but an alkyl group, an aryl group, an alkoxy group and the like are preferable.

The plasticizer used in the present invention preferably does not contain P or S in the molecule.

The content of these non-phosphate ester plasticizers in the base layer is preferably 10 to 30% by mass.

Specific examples of the ultraviolet absorber preferably used in the present invention include oxybenzophenone compounds, benzotriazole compounds, salicylate compounds, benzophenone compounds, cyanoacrylate compounds, nickel complex salt compounds and the like. However, the ultraviolet absorber is not particularly limited to these, and other ultraviolet absorbers may be used.

As the benzotriazole type ultraviolet absorber, a compound represented by the following general formula [1] can be used.

[0060]

[Chemical 9]

In the formula, R ₁ , R ₂ , R ₃ , R ₄ and R ₅ may be the same or different and each is a hydrogen atom, a halogen atom, a nitro group, a hydroxyl group, an alkyl group, an alkenyl group, an aryl group or an alkoxy group. Represents a group, an acyloxy group, an aryloxy group, an alkylthio group, an arylthio group, a mono- or dialkylamino group, an acylamino group or a 5- or 6-membered heterocyclic group, and R ₄ and R ₅ are ring-closed to form a 5- or 6-membered carbon. You may form a ring.

Specific examples of the ultraviolet absorber according to the present invention will be given below, but the present invention is not limited thereto. UV-1: 2- (2'-hydroxy-5'-methylphenyl) benzotriazole UV-2: 2- (2'-hydroxy-3 ', 5'-di-
tert-Butylphenyl) benzotriazole UV-3: 2- (2'-hydroxy-3'-tert-
Butyl-5'-methylphenyl) benzotriazole UV-4: 2- (2'-hydroxy-3 ', 5'-di-
tert-Butylphenyl) -5-chlorobenzotriazole UV-5: 2- (2'-hydroxy-3 '-(3 ",
4 ", 5", 6 "-tetrahydrophthalimidomethyl)
-5'-Methylphenyl) benzotriazole UV-6: 2,2-methylenebis (4- (1,1,3,3)
3-tetramethylbutyl) -6- (2H-benzotriazol-2-yl) phenol) UV-7: 2- (2'-hydroxy-3'-tert-
Butyl-5'-methylphenyl) -5-chlorobenzotriazole Further, as the benzophenone-based UV absorber which is one of the UV absorbers according to the present invention, a compound represented by the following general formula [2] can be used.

[0063]

[Chemical 10]

In the formula, Y represents a hydrogen atom, a halogen atom or an alkyl group, an alkenyl group, an alkoxy group, and a phenyl group, and these alkyl group, alkenyl group and phenyl group may have a substituent. A is a hydrogen atom,
An alkyl group, an alkenyl group, a phenyl group, a cycloalkyl group, an alkylcarbonyl group, an alkylsulfonyl group or a -CO (NH) _n-1 -D group, where D is an alkyl group,
It represents an alkenyl group or a phenyl group which may have a substituent. m and n represent 1 or 2.

In the above, the alkyl group represents, for example, a linear or branched aliphatic group having up to 24 carbon atoms, the alkoxy group has, for example, an alkoxy group having 18 carbon atoms, and the alkenyl group has, for example, carbon atoms. Number 1
Up to 6 alkenyl groups represent, for example, an allyl group and a 2-butenyl group. Further, as a substituent for an alkyl group, an alkenyl group, or a phenyl group, a halogen atom such as chlor, bromine, or a fluorine atom, a hydroxy group, a phenyl group, or the like (this phenyl group is substituted with an alkyl group or a halogen atom, etc. May be used).

Specific examples of the benzophenone compound represented by the general formula [2] are shown below, but the invention is not limited thereto. UV-8: 2,4-dihydroxybenzophenone UV-9: 2,2'-dihydroxy-4-methoxybenzophenone UV-10: 2-hydroxy-4-methoxy-5-sulfobenzophenone UV-11: bis (2-methoxy) -4-hydroxy-5
-Benzoylphenylmethane) In the present invention, it is preferable to mainly contain an ultraviolet absorber in the base layer, and in particular, three or more aromatic rings (eg, benzene ring) or cycloalkyl rings (eg, cyclohexane ring) are included in the molecule. It is preferable that the base layer contains an ultraviolet absorber having the same). Thereby, the water vapor permeability can be further reduced.

Examples of the additive having 3 or more aromatic rings or cycloalkyl rings in the molecule include 2,2'-
Methylenebis [6- (2H-benzotriazol-2-
Yl) -4- (1,1,3,3-tetramethylbutyl)
Phenol], 2- (2H-benzotriazol-2-
Yl) -4,6-bis (1-methyl-1-phenylethyl) phenol (TINUVIN 234), 1,3,5
-Tris (3,5-di-tert-butyl-4-hydroxybenzyl) -1,3,5-triazine-2,4,6
(1H, 3H, 5H) -trione, 1,3,5-tris [(4-tert-butyl-3-hydroxy-2,6-)
Xylyl) methyl] -1,3,5-triazine-2,
4,6 (1H, 3H, 5H) -trione, 2- (4,6
-Diphenyl-1,3,5-triazin-2-yl)-
5-[(hexyl) oxy] phenol, RUVA-1
00/110 (Otsuka Chemical Co., Ltd.), RUVA-206
(Manufactured by Otsuka Chemical Co., Ltd.), ADEKA STAB LA-31 (manufactured by Asahi Denka Kogyo KK), ADEKA STAB LA-31RG (manufactured by Asahi Denka Kogyo KK), and the like. Alternatively, JP-A-6
A polymer UV absorber having a plurality of UV absorbing groups represented by the general formulas (1) to (5) described in JP-A-148430 may be used, and specifically, PU described in JP-A-6-148430.
The polymeric UV absorbers having a plurality of UV absorbing groups represented by V-1 to V22 are used as the UV absorber having three or more aromatic rings in one molecule. Alternatively, the ultraviolet absorber described in Japanese Patent Application No. 2001-122573 is also preferably used, and in particular, the ultraviolet absorbers represented by the general formulas (1) to (8), for example, Chemical formulas 10 and 11 shown in this Example, UV absorbers such as Chemical formulas 13 and 15 are preferably used. Alternatively, Japanese Patent Laid-Open No. 2000-2734
The ultraviolet absorber represented by the general formula (1) described in No. 37 is also preferably used.

As the ultraviolet absorber used in the present invention, those having excellent absorption of ultraviolet rays having a wavelength of 370 nm or less and little absorption of visible light having a wavelength of 400 nm or more are preferably used from the viewpoint of good liquid crystal display property. . It is desired that the ultraviolet absorption capacity of the film is 380 nm and the transmittance is 10% or less. The transmittance is more preferably less than 6%, and further preferably the transmittance is less than 0 to 4%.

The cellulose ester film of the present invention contains fine particles on at least one surface layer. More preferably, it is added to the surface layers on both sides. The coefficient of kinetic friction is the coefficient of kinetic friction between the front and back of the film.
-When measured according to K-7125 (1987),
It is preferably 1.5 or less, more preferably 1.0 or less, and further preferably 0.5 or less.

The dynamic friction coefficient can be lowered by increasing the addition amount of fine particles, but since the haze value of the film tends to increase, the addition amount is determined by the balance between the two. It is preferable to add 0.1% by mass or more.

When the content of the non-phosphate ester plasticizer is large, the added fine particles are likely to aggregate, causing a film failure or increasing haze. Since the content of the fine particles becomes remarkable when the content of the fine particles is 0.1% by mass or more, and particularly 0.15% by mass or more, the content of the non-phosphate ester plasticizer in the surface layer is preferably less than 10% by mass.

Fine particles may be added to the base layer, but the addition amount is preferably less than 0.1% by mass. More preferably, the addition amount of the fine particles contained in the base layer is less than 0.05% by mass, and further preferably less than 0.03% by mass.
The addition amount may be 0, but 0.0001 to 0.01
It is particularly preferable that the content of the fine particles is about% by mass, and if a minute amount of fine particles is contained, the generation of gel-like foreign matter is suppressed in the dope, and the failure of the film due to this is reduced.

Examples of fine particles include inorganic fine particles such as silicon dioxide, titanium dioxide, calcined calcium silicate, hydrated calcium silicate, aluminum silicate, magnesium silicate and calcium phosphate, and fine particles such as crosslinked polymers. Is preferred.

Further, in order to reduce the haze of the film,
The fine particles such as silicon dioxide are preferably surface-treated with an organic substance. Preferred organic substances for the surface treatment include halosilanes, alkoxysilanes, silazanes, siloxanes and the like. The larger the average diameter of the fine particles, the greater the matte effect, and the smaller the average diameter, the better the transparency. Therefore, the average diameter of the primary particles of the fine particles is 0.1 μm.
Below, preferably 1 to 50 nm, more preferably 1 to 2
It is 0 nm. The fine particles of silicon dioxide include AEROSIL 200, 200V, 3 manufactured by Nippon Aerosil Co., Ltd.
00, R972, R974, R202, R812, OX
50, TT600, etc., preferably AERO
SIL200V, R972, R974, R202, R8
12 and the like. The amount of the fine particles added to the base layer is preferably 0.1 to 0.5% by mass, and more preferably 0.15 to 0.5% by mass, based on the solid content forming the surface layer.

The primary average particle diameter of the fine particles is measured by observing the particles with a transmission electron microscope (magnification: 500,000 to 2,000,000 times), observing 100 particles, and averaging the average value to 1
The following average particle diameter was used.

The apparent specific gravity of the fine particles is preferably 70 g / liter or more, more preferably 90 to 200.
g / liter, particularly preferably 100 to 200
g / liter. The higher the apparent specific gravity is, the higher the concentration of the dispersion liquid can be made, which is preferable because the haze and the aggregates are improved.

The silicon dioxide fine particles having an average primary particle diameter of 20 nm or less and an apparent specific gravity of 70 g / liter or more are, for example, one obtained by mixing vaporized silicon tetrachloride and hydrogen.
It can be obtained by burning in air at 000 to 1200 ° C. Further, for example, they are commercially available under the trade names of Aerosil 200V and Aerosil R972V (all manufactured by Nippon Aerosil Co., Ltd.), and they can be used.

In the present invention, the apparent specific gravity described above was calculated by the following formula by taking a certain amount of silicon dioxide fine particles in a graduated cylinder and measuring the weight at this time. Apparent specific gravity (g / liter) = mass of silicon dioxide (g) / volume of silicon dioxide (liter) As a method for preparing the dispersion liquid of fine particles according to the present invention, there are, for example, the following three kinds.

(Preparation method A) The solvent and the fine particles are mixed by stirring and then dispersed by a disperser. This is referred to as a fine particle dispersion liquid. The fine particle dispersion liquid is added to the dope liquid and stirred.

(Preparation Method B) The solvent and the fine particles are mixed by stirring and then dispersed by a disperser. This is referred to as a fine particle dispersion liquid. Separately, a small amount of cellulose triacetate is added to the solvent and dissolved by stirring.

The fine particle dispersion is added to this and stirred. This is used as a fine particle addition liquid. The fine particle added liquid is thoroughly mixed with the dope liquid by an in-line mixer.

(Preparation method C) A small amount of cellulose triacetate is added to a solvent and dissolved by stirring. Fine particles are added to this and dispersed by a disperser. This is used as a fine particle addition liquid.
The fine particle added liquid is thoroughly mixed with the dope liquid by an in-line mixer.

Preparation method A is excellent in dispersibility of fine particles of silicon dioxide, and preparation method C is excellent in that fine particles of silicon dioxide are unlikely to reaggregate. Preparation method B is a preferable preparation method which is excellent in both the dispersibility of the silicon dioxide fine particles and the difficulty of re-aggregation of the silicon dioxide fine particles.

(Dispersion method) When the silicon dioxide fine particles are mixed with a solvent and dispersed, the concentration of silicon dioxide is 5 to 30.
Mass% is preferable, 10-25 mass% is more preferable, and 15-20 mass% is the most preferable. The higher the dispersion concentration, the more the liquid turbidity with respect to the added amount tends to be low, and the haze and the aggregates are improved, which is preferable.

The solvent used is a lower alcohol, preferably methyl alcohol, ethyl alcohol,
Propyl alcohol, isopropyl alcohol, butyl alcohol and the like can be mentioned. The solvent other than the lower alcohol is not particularly limited, but it is preferable to use the solvent used when forming the cellulose ester film.

As the disperser, an ordinary disperser can be used. Dispersers are roughly divided into media dispersers and medialess dispersers. A medialess disperser is preferable for dispersing silicon dioxide fine particles because of its low haze. Examples of the media disperser include a ball mill, a sand mill and a dyno mill. Ultrasonic type, centrifugal type,
Although there are high pressure types and the like, a high pressure dispersion device is preferred in the present invention. The high-pressure dispersing device is a device that creates special conditions such as high shear and high-pressure state by passing a composition obtained by mixing fine particles and a solvent at high speed through a thin tube.

In the case of processing with a high-pressure dispersion apparatus, it is preferable that the maximum pressure condition inside the apparatus is 10 MPa or more in a thin tube having a tube diameter of 1 to 2000 μm. More preferably, it is 20 MPa or more. At that time, the maximum reaching speed reaches 100 m / sec or more, the heat transfer speed is 420 kJ.
/ Hour or more is preferable. Microfluidics Corpo is used for the high-pressure dispersing device as described above.
ultra high pressure homogenizer (trade name: Microfluidizer) or Nanomizer manufactured by Nanomizer Co., Ltd., and other Manton-Gaulin type high-pressure disperser, for example, Izumi Food Machinery homogenizer, Sanwa Machinery Co., Ltd. UHN-01 Etc.

Other additives can be added to the surface layer or the base layer of the present invention, if necessary. Examples thereof include antistatic agents, conductive fine particles, antioxidants, various dyes, and deterioration inhibitors, but are not particularly limited thereto.

The cellulose ester used in the present invention is preferably a lower fatty acid ester. The lower fatty acid in the lower fatty acid ester of cellulose ester means a fatty acid having 6 or less carbon atoms, for example,
Cellulose diacetate, cellulose triacetate,
Cellulose propionate, cellulose butyrate and the like are mentioned as preferred examples of the lower fatty acid ester of cellulose. In addition to the above, JP-A-10-4580
4, No. 8-231761, U.S. Pat. No. 2,319,
A mixed fatty acid ester such as cellulose acetate propionate and cellulose acetate butyrate described in No. 052 can be used. Among the above-mentioned, the lower fatty acid ester of cellulose which is particularly preferably used is cellulose triacetate or cellulose acetate propionate. Cellulose acetate propionate containing a propionate group as a substituent has excellent water resistance and is useful as an optical film for a display device.

Further, from the viewpoint of base strength, a polymerization degree of 250 to 400 and an amount of bound acetic acid of 54 to 62.5% are preferably used, and more preferably, an amount of bound acetic acid of 58 to
62.5% cellulose triacetate. The acyl group substitution degree can be measured according to the standard of ASTM-D817-96. The number average molecular weight of cellulose ester is 70,000 to 250,000,
The mechanical strength of the molded product is strong, and the dope viscosity is appropriate, and more preferably 80,000 to
It is 150,000.

Here, the number average molecular weight of the cellulose ester described above is determined as follows.

<< Measurement of Number Average Molecular Weight of Cellulose Ester >> It is measured by high performance liquid chromatography under the following conditions.

Solvent: Acetone column: MPW × 1 (manufactured by Tosoh Corporation) Sample concentration: 0.2 mass / v% Flow rate: 1.0 ml / min Sample injection amount: 300 μl Standard sample: Polymethylmethacrylate (Mw =) 188,
200) Temperature: 23 ° C. Further, the ratio Mw / Mn of the weight average molecular weight Mw of the cellulose ester to the number average molecular weight Mn of 1.0 to 5.0 is used, preferably 1.4 to 3.5. Cellulose ester of is used.

As the cellulose ester according to the present invention, either a cellulose ester synthesized from cotton linter or a cellulose ester synthesized from wood pulp can be used alone or in combination. If the peelability from the belt or drum becomes a problem, it is preferable to use a large amount of a cellulose ester synthesized from cotton linter, which has good peelability from the belt or drum, because the productivity is high. When a cellulose ester synthesized from wood pulp is mixed and used, the ratio of the cellulose ester synthesized from cotton linter is 40% or more, the peeling effect becomes remarkable, and it is more preferably 60% or more, Most preferably used alone.

As will be described later, the cellulose ester of the present invention is a support for casting a cellulose ester solution (dope), which is generally called a casting method, for example, an endless metal belt for infinite transfer or a rotating metal drum. A dope is cast from a pressure die onto a body (hereinafter sometimes simply referred to as a support) to form a film, but a co-casting method or a sequential casting method is used to form a multilayer structure. It is preferably made by

The organic solvent used for the preparation of these dopes is preferably one which can dissolve the cellulose ester and has an appropriate boiling point. For example, methylene chloride, methyl acetate, ethyl acetate, amyl acetate, acetone,
Tetrahydrofuran, 1,3-dioxolane, 1,4-
Dioxane, cyclohexanone, ethyl formate, 2,2
2-trifluoroethanol, 2,2,3,3-hexafluoro-1-propanol, 1,3-difluoro-2
-Propanol, 1,1,1,3,3,3-hexafluoro-2-methyl-2-propanol, 1,1,1,
3,3,3-hexafluoro-2-propanol, 2,
2,3,3,3-pentafluoro-1-propanol,
Examples thereof include nitroethane, 1,3-dimethyl-2-imidazolidinone, and methyl acetoacetate, and organic halogen compounds such as methylene chloride, dioxolane derivatives, methyl acetate, ethyl acetate, acetone, etc. , Good solvent).

Further, as shown in the following film forming step, when the solvent is dried from the web (dope film) formed on the support in the solvent evaporation step, it is used from the viewpoint of preventing foaming in the web. The boiling point of the organic solvent used is
30-80 degreeC is preferable, for example, the boiling point of the above-mentioned good solvent is methylene chloride (boiling point 40.4 ° C), methyl acetate (boiling point 56.32 ° C), acetone (56.3).
C.), ethyl acetate (76.82 ° C.) and the like.

Among the above-mentioned good solvents, methylene chloride and methyl acetate, which are excellent in solubility, are preferably used,
Particularly, it is preferable that methylene chloride is contained in an amount of 50% by mass or more based on the total organic solvent.

In addition to the above-mentioned organic solvent, it is preferable to contain 0.1 to 30% by mass of alcohol having 1 to 4 carbon atoms, based on 100% by mass of the total organic solvent in the dope. Particularly preferably, the alcohol is contained in an amount of 5 to 30% by mass. After casting the dope described above on the casting support, the web (dope film) gels when the solvent starts to evaporate and the ratio of alcohol increases, and the web is toughened and separated from the casting support. Is also used as a gelling solvent for facilitating dissolution, and when the proportion of these is small, it also has a role of promoting dissolution of the cellulose ester of the non-chlorine organic solvent.

As the alcohol having 1 to 4 carbon atoms,
Methanol, ethanol, n-propanol, iso-
Propanol, n-butanol, sec-butanol,
Examples thereof include tert-butanol.

Of these, ethanol is preferable because the dope is stable, the boiling point is relatively low, the drying property is good, and there is no toxicity. Preferably methylene chloride 70
It is preferable to use a solvent containing 5 to 30 mass% of ethanol with respect to ˜95 mass%. Methyl acetate may be used in place of methylene chloride when a solvent containing halogen is avoided due to environmental restrictions. In this case, -1
The cellulose ester solution can be prepared by using a cooling dissolution method in which it is cooled to 00 ° C to -10 ° C and dissolved.

The method for producing the cellulose ester film of the present invention will be described. The method for producing the cellulose ester laminated film of the present invention will be described with reference to the process diagrams shown in FIGS. 1 and 2. FIG. 1 is a process diagram showing an example of a manufacturing apparatus for a cellulose ester laminated film of the present invention, and FIG. 2 is a sectional view of the slit die 6 of FIG. The dope liquid tank 1 for preparing the cellulose ester dope liquid contains the dope liquid 1a, and the particle addition liquid tank 2 contains the particle addition liquid 2a. The dope liquid 1a is sent to the in-line mixers 5a and 5b by the liquid sending pumps 4b and 4c, and the fine particle added liquid 2
a is sent to the in-line mixer 5a by the pump 4a. The dope solution 1a and the fine particle additive solution 2a are sufficiently mixed by the in-line mixer 5a and sent to the slit 13 of the slit die 6. Similarly, the dope liquid 1 a and the ultraviolet absorber additive liquid 3 a put in the ultraviolet absorber additive liquid tank 3 are sufficiently mixed by the in-line mixer 5 b and sent to the slit 12 of the slit die 6. The layers on the upper and lower surfaces of the slit die 6 are composed of a mixed solution of the dope solution 1a and the fine particle additive solution 2a, and the middle layer is a mixture solution of the dope solution 1a and the ultraviolet absorber additive solution 3a. A casting belt 8 that is co-cast from the drum 7 and continuously moves from the drum 7.
Cast on top. The three-layered cast cellulose ester dope layer is dried and then peeled from the casting belt by the roller 9 as the cellulose ester laminated film 10.

A casting method according to the manufacturing method of the present invention will be described. In order to produce the cellulose ester film having a multilayer structure of the present invention, a sequential multilayer casting method in which two or three or more layers are formed through different dies, and each dope is added in a die having two or three or more slits. Either a simultaneous multi-layer casting method in which two or three layers or three or more layers are merged to form a combination, or a multi-layer casting method in which sequential multi-layer casting and simultaneous multi-layer casting are combined is preferably used. A simultaneous multi-layer casting method is preferably used in which each dope is merged in a die having two or three or more slits to form a two-layer, three-layer or three-layer or more structure, which is also called co-casting. is there.

In the present invention, a surface layer dope containing at least fine particles, a cellulose ester and an organic solvent as main components, a base layer containing at least a non-phosphate ester plasticizer, an ultraviolet absorber, a cellulose ester and an organic solvent as main components. It is preferable to use a dope. By using these, the multilayer structure cellulose ester film of the present invention can be obtained by a co-casting method. The concentration of cellulose ester in the dope is preferably 10 to 30% by mass, more preferably 18 to 20% by mass. When producing the dope, it is preferable to add the cut product of the produced cellulose ester film to the base layer dope or the surface layer dope as a part of the raw material. In particular, when added to the base layer dope, the stability of the dope is improved. When a cut product of a cellulose ester film is used, it can be prepared by calculating the amount of the additive contained in the film and increasing or decreasing the amount of the additive added when preparing the dope. The amount of the cut product of the cellulose ester film to be added as a part of the raw material is 1 to 50 as a ratio to the solid content in the dope.
Mass% is preferable, and 10-30 mass% is especially preferable.

As the solvent used in the present invention, the above-mentioned solvents are used. Examples of the good solvent used in the present invention include organic halogen compounds such as methylene chloride and methyl acetate,
Dioxolanes may be mentioned. Further, as the poor solvent used in the present invention, for example, methanol, ethanol,
N-butanol, cyclohexane and the like are preferably used. When preparing the dope solution described above, as a method for dissolving the cellulose ester, a general method can be used, but as a preferable method, the cellulose ester is mixed with a poor solvent, wetted or swollen, and A method of mixing with a good solvent is preferably used. At this time, under pressure, a method of heating at a temperature not lower than the boiling point of the solvent at room temperature and a range in which the solvent does not boil, and dissolving while stirring,
It is more preferable because it prevents the generation of undissolved lumps called gels and mamako. The pressurization may be carried out by a method of injecting an inert gas such as nitrogen gas or by increasing the vapor pressure of the solvent by heating. Heating is preferably performed from the outside. For example, a jacket type is preferable because temperature control is easy.

The heating temperature after the addition of the solvent is preferably a temperature above the melting point of the solvent used and within the range in which the solvent does not boil, for example, it is preferably set in the range of 60 ° C. or higher and 70 to 110 ° C. is there. Also, the pressure is adjusted at the set temperature so that the solvent does not boil.

After the dissolution, the product is taken out from the container while being cooled, or is taken out from the container by a pump or the like and cooled by a heat exchanger or the like, and is used for film formation. The cooling temperature at this time may be room temperature, but it is more preferable to cool to a temperature lower than the boiling point by 5 to 10 ° C. and perform casting at that temperature because the dope viscosity can be reduced. The concentration of cellulose ester in the dope of the base layer is preferably higher than the concentration of cellulose ester in the dope of the surface layer. As for the dope viscosity, it is desirable that the dope viscosity of the surface layer is lower than that of the base layer, so that the sharkskin and the like of the resulting cellulose ester film can be prevented and the surface quality can be improved. The support used in the casting step is preferably a support formed by mirror-finishing belt-shaped or drum-shaped stainless steel.

The surface temperature of the support on the casting side is preferably 10 to 55 ° C. The higher the temperature of the support, the faster the drying rate of the solvent, which is preferable. However, if the temperature is too high, foaming or flatness may occur. A more preferable range of the temperature of the support is 20 to 20.
40 ° C. Moreover, the support temperature at the time of peeling is 10 to
A temperature of 40 ° C., more preferably 15 to 30 ° C. is preferable because the adhesion between the film and the support can be reduced.

When the cellulose ester film having a multi-layer structure of the present invention is produced, it is particularly preferable that it is peeled after being dried on the support for 30 to 120 seconds. If the time is shorter than 30 seconds, unevenness during casting is likely to remain, and streaks and step unevenness are likely to occur. Further, if it takes 120 seconds or more, it is not preferable because the additive diffuses more than necessary between the base layer and the surface layer. Particularly preferably, it is dried on the support for 30 to 90 seconds and peeled off during co-casting.

The average amount of residual solvent contained in the film when the dope is cast and peeled from the support is 20 to 1
It is preferably 60% or less, particularly 40 to 120%
Is preferred.

In the present invention, the residual solvent amount is defined by the following formula. Amount of residual solvent = (mass before heat treatment-mass after heat treatment) /
(Mass after heat treatment) × 100% When the amount of residual solvent is measured, the heat treatment means that the film is subjected to heat treatment at 115 ° C. for 1 hour.

The peeling tension for peeling the support from the film is usually 200 to 250 N / m.

In the step of drying the cellulose ester film, it is preferable that the film peeled from the support is further dried so that the residual solvent amount is 3% by mass or less, more preferably 0.5% by mass or less. is there. Particularly preferably, it is dried to 0.01% by mass or less.

In the film drying step, generally, a roll suspension method or a tenter method is used in which the film is dried while being conveyed. For a liquid crystal display member, it is preferable to dry while holding the width by a tenter method in order to improve dimensional stability. In particular, it is particularly preferable to hold the width at a place where the residual solvent amount is large immediately after peeling from the support, because the effect of improving the dimensional stability is further exhibited. More preferably, stretching in the width direction in the range of 1.01 to 1.5 times is particularly preferable because a film having excellent flatness can be obtained. The means for drying the film is not particularly limited, and generally, hot air, infrared rays, heating rolls, microwaves or the like is used. It is preferable to use hot air for the sake of simplicity. The drying temperature is preferably 40 to 150 ° C., divided into 3 to 5 stages, and gradually increased.
It is more preferable to carry out the treatment in the range of 140 ° C. in order to improve the dimensional stability.

In the production of the optical film of the present invention, it is preferable to maintain higher flatness by casting a dope and then applying a tenter when peeling it from the belt or drum and drying.

[0116] Cellulose ester film of the present invention is in-plane retardation R _o is ones obtained preferably from 0 to 500 nm, the retardation R _t in the thickness direction 0-3
Those of 00 nm are preferably obtained.

For example, according to the method described in Japanese Patent Application No. 2001-293650, a biaxial retardation film having R _o of 45 nm and R _t of 130 nm can be produced.

The cellulose ester film of the present invention is a multi-layered cellulose ester film having a surface layer and a base layer, and particularly preferably 3 having surface layers on both sides of the base layer.
It is a cellulose ester film having a layer structure. The base layer may be formed of a plurality of layers. The surface layer is a layer that forms the surface of the film and has a thickness corresponding to about 1 to 25% of the film thickness. The film thickness of the cellulose ester of the present invention is 10 to 1000 μm, preferably 10 to 300 μm,
The thickness of the surface layer is particularly preferably 10 to 60 μm, but is preferably 1 to 20 μm from the surface, more preferably 3 to 15 μm, and particularly preferably 5 to 10 μm. If the film thickness is within this range from the surface, the surface layer may be formed of a plurality of layers.

Further, the cellulose ester film of the present invention comprises an antistatic layer, an ultraviolet curable resin layer, a thermosetting resin layer, an antireflection layer, a clear hard coat layer, an easily adhesive layer, an antiglare layer,
An alignment layer, a liquid crystal layer, a back coat layer, an optical anisotropic layer, etc. can be provided. The cellulose ester film of the present invention has excellent coatability for various coating layers.

Alternatively, the metal oxide layer can be formed uniformly by vapor deposition or plasma CVD.

The cellulose ester film of the present invention is a polarizing plate protective film, retardation film, optical compensation film, brightness enhancement film, antireflection film, antiglare film, conductive film, antistatic film, antiglare antireflection film, etc. Can be used as various optical films.

The cellulose ester film of the present invention is extremely excellent as a polarizing plate protective film. The polarizing plate is
It can be manufactured by a general method. For example, there is a method of laminating a cellulose ester laminated film of the present invention with an alkali saponification treatment, dipping and stretching it in an iodine solution, and attaching it to both surfaces of a polarizing film using a completely saponified polyvinyl alcohol aqueous solution. In the alkali saponification treatment, in order to improve the wetting of the water-based adhesive at this time and improve the adhesiveness, the cellulose ester film is treated at 40 to 65 ° C.
It refers to the process of dipping in a strong alkaline solution.

The polarizing film, which is the main constituent element of the polarizing plate, is an element that allows only the light having a polarization plane in a certain direction to pass therethrough. A typical polarizing film currently known is a polyvinyl alcohol type polarizing film. There are a polyvinyl alcohol film dyed with iodine and a dye dyed with a dichroic dye. Those used are those obtained by forming a polyvinyl alcohol aqueous solution into a film and dyeing it by uniaxially stretching it, or dyeing it and then uniaxially stretching it, and then preferably subjecting it to a durability treatment with a boron compound. The cellulose ester film of the present invention is laminated on the surface of the polarizing film to form a polarizing plate. It is preferably laminated with a water-based adhesive containing polyvinyl alcohol or the like as a main component, but the cellulose ester film of the present invention has low moisture permeability and excellent durability. Since the content of the absorbent is small, it is possible to provide a polarizing plate which is excellent in productivity and durability without causing unevenness or wrinkles during the production of the polarizing plate. A display device using the polarizing plate of the present invention is excellent in durability and can display a high contrast for a long period of time.

[0124]

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

Example 1 (Preparation of Dope Liquids D-1 to 18) (Dope Liquid D-1) Cellulose triacetate synthesized from linter cotton (acetyl substitution degree 2.90) 85 parts by mass Cellulose synthesized from wood pulp Triacetate (acetyl substitution degree 2.90) 15 parts by mass Methylene chloride 407 parts by mass Ethanol 35 parts by mass or more are charged into a closed container, completely dissolved while heating and stirring, and Azumi filter paper manufactured by Azumi Filter Paper Co., Ltd. No. A dope solution was prepared by filtration using 244.

Dope solutions D-2 to 18 having the following compositions were prepared in the same manner as dope solution D-1.

(Dope Liquid D-2) Cellulose triacetate synthesized from linter cotton (acetyl substitution degree 2.90) 85 parts by weight Cellulose triacetate synthesized from wood pulp (acetyl substitution degree 2.90) 15 parts by weight E- 15 1 part by mass Methylene chloride 407 parts by mass Ethanol 35 parts by mass (Dope solution D-3) Cellulose triacetate synthesized from linter cotton (acetyl substitution degree 2.90) 85 parts by mass Cellulose triacetate synthesized from wood pulp (acetyl substitution) 2.90) 15 parts by mass E-15 3 parts by mass Methylene chloride 407 parts by mass Ethanol 35 parts by mass (dope liquid D-4) Cellulose triacetate synthesized from linter cotton (acetyl substitution degree 2.90) 85 parts by mass Wood Cell synthesized from pulp Loose triacetate (acetyl substitution degree 2.90) 15 parts by mass E-15 5 parts by mass Methylene chloride 407 parts by mass Ethanol 35 parts by mass (dope solution D-5) Cellulose triacetate synthesized from linter cotton (acetyl substitution degree 2.90). ) 85 parts by mass Cellulose triacetate synthesized from wood pulp (acetyl substitution degree 2.90) 15 parts by mass E-15 15 parts by mass Methylene chloride 350 parts by mass Ethanol 30 parts by mass (dope liquid D-6) Synthesized from linter cotton Cellulose triacetate (acetyl substitution degree 2.90) 85 parts by weight Cellulose triacetate synthesized from wood pulp (acetyl substitution degree 2.90) 15 parts by weight E-15 15 parts by weight Methylene chloride 407 parts by weight Ethanol 35 parts by weight (dope) Liquid D 7) Cellulose triacetate synthesized from linter cotton (acetyl substitution degree 2.90) 85 parts by weight Cellulose triacetate synthesized from wood pulp (acetyl substitution degree 2.90) 15 parts by weight E-15 18 parts by weight Methylene chloride 350 parts by weight Parts ethanol 30 parts by weight (dope liquid D-8) cellulose triacetate synthesized from linter cotton (acetyl substitution degree 2.90) 85 parts by weight cellulose triacetate synthesized from wood pulp (acetyl substitution degree 2.90) 15 parts by weight E-15 20 parts by mass Methylene chloride 350 parts by mass Ethanol 30 parts by mass (Dope solution D-9) Cellulose triacetate synthesized from linter cotton (acetyl substitution degree 2.90) 85 parts by mass Cellulose triacetate synthesized from wood pulp Acetyl substitution degree 2.90) 15 parts by mass E-15 10 parts by mass Methylene chloride 407 parts by mass Ethanol 35 parts by mass (Dope solution D-10) Cellulose triacetate synthesized from linter cotton (acetyl substitution degree 2.90) 85 parts by mass Parts Cellulose triacetate synthesized from wood pulp (acetyl substitution degree 2.90) 15 parts by mass E-15 12 parts by mass Methylene chloride 407 parts by mass Ethanol 35 parts by mass (dope liquid D-11) Cellulose triacetate synthesized from linter cotton (Acetyl substitution degree 2.90) 85 parts by weight Cellulose triacetate synthesized from wood pulp (Acetyl substitution degree 2.90) 15 parts by weight Triphenyl phosphate 10 parts by weight Methylene chloride 407 parts by weight Ethanol 35 parts by weight (Dope solution D 12) Cellulose triacetate synthesized from linter cotton (acetyl substitution degree 2.90) 85 parts by weight Cellulose triacetate synthesized from wood pulp (acetyl substitution degree 2.90) 15 parts by weight Triphenyl phosphate 15 parts by weight Methylene chloride 350 parts by weight Parts ethanol 30 parts by weight (dope solution D-13) cellulose triacetate synthesized from linter cotton (acetyl substitution degree 2.90) 85 parts by weight cellulose triacetate synthesized from wood pulp (acetyl substitution degree 2.90) 15 parts by weight Triphenyl phosphate 3 parts by weight Methylene chloride 350 parts by weight Ethanol 30 parts by weight (Dope solution D-14) Cellulose triacetate synthesized from linter cotton (acetyl substitution degree 2.90) 85 parts by weight From wood pulp Synthesized cellulose triacetate (acetyl substitution degree 2.90) 15 parts by weight Return material (the film of Sample 13 was crushed to a size of 1 cm ² or less) 10 parts by weight E-15 14 parts by weight Methylene chloride 350 parts by weight Ethanol 30 parts by mass (dope solution D-15) Cellulose triacetate synthesized from linter cotton (acetyl substitution degree 2.90) 85 parts by mass Cellulose triacetate synthesized from wood pulp (acetyl substitution degree 2.90) 15 parts by mass E- 14 20 parts by mass Methylene chloride 350 parts by mass Ethanol 30 parts by mass (Dope solution D-16) Cellulose triacetate synthesized from linter cotton (acetyl substitution degree 2.90) 85 parts by mass Cellulose triacetate synthesized from wood pulp (acetyl substitution) 2.90) 1 Parts by mass E-13 20 parts by mass Methylene chloride 350 parts by mass Ethanol 30 parts by mass (Dope solution D-17) Acetyl substitution degree 1.95, propionyl substitution degree 0.7, number average molecular weight 75,000 cellulose acetate propionate 100 parts by mass Part E-15 20 parts by mass Methyl acetate 250 parts by mass Ethanol 50 parts by mass (Dope solution D-18) Acetyl substitution degree 1.95, propionyl substitution degree 0.7, 100 parts by weight of cellulose acetate propionate having a number average molecular weight of 75,000. Methyl acetate 300 parts by mass Ethanol 60 parts by mass (Silicon oxide dispersion A) Aerosil 200V (manufactured by Nippon Aerosil Co., Ltd.) (Average diameter of primary particles 12 nm, apparent specific gravity 100 g / liter) 10 parts by mass Dissolver ethanol 90 parts by mass or more Stir and mix for 30 minutes at After that, dispersion was carried out with manton-goulin to obtain a silicon oxide dispersion liquid A.

(Silicon Oxide Dispersion Liquid B) Aerosil TT600 (manufactured by Nippon Aerosil Co., Ltd.) (average particle diameter of primary particles: 40 nm, apparent specific gravity: 60 g / liter) 10 parts by mass Ethanol 90 parts by mass or more was stirred and mixed for 30 minutes with a dissolver. After that, dispersion was performed with manton-goulin to obtain a silicon oxide dispersion liquid B.

(Preparation of Additive Solution M-1) Cellulose triacetate synthesized from linter cotton 4 parts by mass Methylene chloride 100 parts by mass or more was charged into a closed container, heated, stirred and completely dissolved, and filtered. .

To this, 12 parts by mass of the silicon oxide dispersion A was added with stirring, and the mixture was stirred for another 30 minutes, then filtered with a polypropylene wind cartridge filter TCW-PPS manufactured by Advantech Toyo Co., Ltd. to obtain an additive M-1.
Was prepared.

(Preparation of Addition Solution M-2) Cellulose triacetate synthesized from linter cotton 4 parts by mass Methylene chloride 100 parts by mass or more is charged into a closed container, and heated and stirred to be completely dissolved and filtered. .

To this, 12 parts by mass of the silicon oxide dispersion B was added with stirring, and the mixture was further stirred for 30 minutes, then filtered through a polypropylene wind cartridge filter TCW-PPS manufactured by Advantech Toyo Co., Ltd. to obtain an additive M-2.
Was prepared.

(Preparation of Additive Solution M-3) Acetyl substitution degree 1.95, propionyl substitution degree 0.7, cellulose acetate propionate having a number average molecular weight of 75,000 4 parts by mass Methylene chloride 100 parts by mass or more is charged into a closed container. The solution was then heated, stirred and completely dissolved and filtered.

12 parts by mass of Silicon Oxide Dispersion A was added thereto with stirring, and the mixture was further stirred for 30 minutes, then filtered through a polypropylene wind cartridge filter TCW-PPS manufactured by Advantech Toyo Co., Ltd. to obtain Additive M-3.
Was prepared.

(Preparation of Additive Liquid U-1) Cellulose triacetate synthesized from linter cotton (acetyl substitution degree 2.90) 4 parts by mass Tinuvin-109 (manufactured by Ciba Specialty Chemicals Co., Ltd.) 8 parts by mass Methylene chloride 100 parts by mass or more are put into a closed container, heated and completely dissolved with stirring, and polypropylene wind cartridge filter TCW-PPS (10) manufactured by Advantech Toyo Co., Ltd.
N, 20N to increase the filtration accuracy in sequence, and use) to prepare the additive liquid U-1.

Additives U-2 to 6 having the following compositions were prepared in the same manner as additive U-1. (Preparation of additive liquid U-2) PUVA-30M (manufactured by Otsuka Chemical Co., Ltd.) 10 parts by mass Methylene chloride 100 parts by mass (Preparation of additive liquid U-3) Cellulose triacetate synthesized from linter cotton (acetyl substitution degree 2 .90) 4 parts by mass LA-31 (manufactured by ADEKA CORPORATION) 6 parts by mass Methylene chloride 100 parts by mass (Preparation of additive liquid U-4) Cellulose triacetate synthesized from linter cotton (acetyl substitution degree 2.90) 4. Mass part Tinuvin-326 (manufactured by Ciba Specialty Chemicals Co., Ltd.) 2 parts by mass Tinubin-109 (manufactured by Ciba Specialty Chemicals Co., Ltd.) 3 parts by mass Tinubin-171 (manufactured by Ciba Specialty Chemicals Co., Ltd.) 3 parts by mass Methylene chloride 100 parts by mass (Preparation of additive liquid U-5) Synthesized from linter cotton Cellulose triacetate (acetyl substitution degree 2.90) 4 parts by mass 2,2'-dihydroxy-4,4'-dimethoxybenzophenone 8 parts by mass Methylene chloride 100 parts by mass (Preparation of additive liquid U-6) Acetyl substitution degree 1. 95, propionyl substitution degree 0.7, cellulose acetate propionate having a number average molecular weight of 75,000 4 parts by mass Tinuvin-109 (manufactured by Ciba Specialty Chemicals Co., Ltd.) 8 parts by mass Methylene chloride 100 parts by mass <Samples 1-24 Preparation> Each of the dope solution and the additive solution described in Tables 1 to 3 was filtered with Finemet NF (absolute filtration accuracy 50 μm) manufactured by Nippon Seisen Co., Ltd. in a film-forming line, and the results are shown with respect to 100 parts by mass of the dope solution. Addition amount of 1 to 3 to the solid content of the dope liquid, the addition amount of the ultraviolet absorber or fine particles of Tables 1 to 3 In-line mixer (Toray static type in-pipe mixer Hi-Mixer, S
WJ) and mixed well. Then, using a belt casting apparatus, a simultaneous multi-layer casting method is performed in a die having two or three slits to form a two-layer or three-layer structure.
The surface was co-cast uniformly in the order of the surface layer, the base layer and the surface A surface. The solvent was evaporated on a stainless steel band support for the times listed in Tables 1-3. Then, it was peeled from the stainless band support. The peeled cellulose triacetate film is slit into a width of 1550 mm, and then stretched 1.05 times in the width direction with a tenter, and the temperature is 120 ° C., 135
Drying is completed while being conveyed by a number of rolls in a drying zone of ℃, slitting to a width of 1330 mm, and knurling with a width of 10 mm and a height of 5 μm on both ends of the film,
Cellulose triacetate laminated film samples 1 to 24 were obtained. At this time, the film thickness of the cellulose triacetate film was 40 μm, and the winding length was 4000 m.

The prepared samples were evaluated according to the measurement methods shown below. The results are shown in Table 4. << Measurement method >> [Storage durability] In a glass container of 50 ml which can be sealed,
Insert a film sample of 50 cm ² and leave it unsealed 8
Leave for 24 hours at 0 ° C and 90%, then seal and
The state of the film sample after being forcibly deteriorated for 750 hours under the condition of 0 ° C. and 90% was classified into the following levels.

[0138] ◎: No change in film ○: The film is white overall X: The film is discolored brown or black.

[Dynamic Friction Coefficient] The dynamic friction coefficient between the front surface and the back surface of the film was cut according to JIS-K-7125 (1987) so that the front and back surfaces of the film were in contact with each other, and 20
Place a weight of 0g, sample moving speed 100mm / min,
The weight was pulled horizontally under the condition that the contact area was 80 mm × 200 mm, the average load (F) during the movement of the weight was measured, and the dynamic friction coefficient (μ) was calculated from the following formula.

Coefficient of dynamic friction = F (N) / weight of weight (N) [haze] Sample 1 according to ASTM-D1003-52
The haze of each sheet was measured.

[Moisture Permeability] According to the method described in JIS-Z-0208, the temperature and humidity of the constant temperature bath are set at 25 ± 0.5 ° C. and the humidity of 9
The moisture permeability of each sample was measured at 0 ± 2% RH.

[Flatness] A tube of a fluorescent lamp that was turned on was reflected on the surface of the film sample, and the distortion or fine disturbance was observed, and the flatness was classified into the following levels.

[0143] ◎: Fluorescent lamp can be seen straight ○: The fluorescent lamp looks partially bent ×: Fluorescent light appears to be spotted.

[Polarizing Plate Yield] Using an original sample of a cellulose ester film of 4000 m roll, the alkali saponification treatment described below and the production of a polarizing plate were performed. The produced polarizing plate was punched out into 15 inches, and a visual inspection was performed one by one. The appearance inspection was determined to be a defective product when wrinkles and uneven adhesive were observed on the polarizing plate. The yield was calculated by the following formula.

Yield (%) = number of non-defective products / (number of non-defective products + number of defective products) × 100 <Alkali saponification treatment> Saponification process 2M-NaOH 50 ° C. 90 seconds water washing process Water 30 ° C. 45 seconds neutralization process 10 mass % HCl 30 ° C. 45 seconds water washing step Water 30 ° C. 45 seconds Under the above conditions, the film sample was saponified, washed with water, neutralized, washed with water in this order, and then dried at 80 ° C.

(Production of Polarizing Plate) Using a polyvinyl alcohol film having a thickness of 120 μm, 1 kg of iodine and 4 kg of boric acid were used.
Was dipped in 100 kg of an aqueous solution containing and was stretched 6 times at 50 ° C. to form a polarizing film. Cellulose ester film samples that had been subjected to alkali saponification treatment on both sides of this polarizing film were attached to each other using a fully saponified polyvinyl alcohol 5% aqueous solution as an adhesive to prepare a polarizing plate.

[Polarizing Plate Storability] First, the parallel transmittance and the orthogonal transmittance were measured for the polarizing plates that were good in the evaluation of the polarizing plate yield, and the degree of polarization was calculated according to the following formula.
After that, each polarizing plate was forcibly deteriorated under the conditions of 60 ° C. and 90% for 500 hours, and then the parallel transmittance and the orthogonal transmittance were measured again, and the polarization degree was calculated according to the following formula. The amount of change in the degree of polarization was determined by the following formula.

Degree of polarization P = ((H ₀ −H ₉₀ ) / (H ₀ +
H ₉₀ )) ^1/2 × 100 Polarization degree change = P ₀ −P ₅₀₀ H ₀ : Parallel transmittance H ₉₀ : Orthogonal transmittance P ₀ : Polarization degree before forced deterioration P ₅₀₀ : Polarization after 500 hours of forced deterioration Degree ◎: Polarization degree change rate less than 10% ◯: Polarization degree change rate 10% or more and less than 25% ×: Polarization degree change rate 25% or more.

[0149]

[Table 1]

[0150]

[Table 2]

[0151]

[Table 3]

[0152]

[Table 4]

Example 2 Commercially available liquid crystal display panel (NEC color liquid crystal display MultiSync LCD1525J Model name
The outermost polarizing plate of LA-1529HM) was carefully peeled off. The polarizing plate sample prepared in Example 1 was attached to the liquid crystal display panel in the same polarization direction. 40 ° C 80%
The liquid crystal display panel using the polarizing plate of the present invention is a liquid crystal display panel using the polarizing plate of the comparative example. On the other hand, it was confirmed that the high contrast was maintained over a long period of time.

[0154]

EFFECT OF THE INVENTION The cellulose ester film of the present invention has a low moisture permeability, does not cause cracking or coloring under high temperature and high humidity, and has an ultraviolet absorbing ability. When laminating with various optical elements, the occurrence of unevenness and wrinkles is small, and especially a polarizing plate using this cellulose ester film as a polarizing plate protective film, under high temperature and high humidity, peeling of the protective film, coloring, etc. It has almost no generation and has excellent resistance to moist heat. Therefore, the liquid crystal display in which the polarizing plate of the present invention is incorporated does not deteriorate even if it is used for a long time under high temperature and high humidity.

[Brief description of drawings]

FIG. 1 is a process drawing showing an example of an apparatus for producing a cellulose ester laminated film of the present invention.

FIG. 2 shows a sectional view of a slit die.

[Explanation of symbols]

1 Dope liquid tank 1a Dope solution 2 Fine particle additive liquid tank 3 UV absorber additive liquid tank 4b, 4c Liquid feed pump 5a, 5b In-line mixer 6 slit die 7 drums 8 casting belt 9 Laura 10 Cellulose ester laminated film 11 casting mouth 12,13 slit

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) B29L 9:00 B29L 9:00 F term (reference) 2H049 BA02 BA06 BB33 BB49 BB62 4F100 AA04A AA04H AA20 AJ07A AJ07B AL05A AL05B BA02 BA25 CA04 CA07 DE01A EH46 EH462 EJ37 EJ372 GB41 JD04 JL04 YY00A YY00B 4F205 AA01 AB07 AB11 AG03 AH73 GA07 GB02 GB26 GC07 GE24 GF02 GN21

Claims (13)

[Claims] 1. A multilayer cellulose ester film having at least a base layer and a surface layer, wherein at least one surface layer contains fine particles, and the base layer contains a non-phosphate ester plasticizer and an ultraviolet absorber. Characterized cellulose ester film. 2. A cellulose ester film having a multilayer structure having at least a base layer and a surface layer, wherein at least one surface layer contains fine particles and the base layer has three or more aromatic rings or cycloalkyl rings in the molecule. A cellulose ester film containing an agent. 3. The cellulose ester film according to claim 2, wherein the additive is a non-phosphate ester plasticizer or an ultraviolet absorber. 4. The non-phosphate ester plasticizer content of the surface layer is less than 10% by mass, the non-phosphate ester plasticizer content of the base layer is 10 to 30% by mass, and the surface layer and the base layer are added. The cellulose ester film according to claim 1 or 3, wherein the difference in the amount is 2 to 30% by mass. 5. The total content of additives in the surface layer is less than 10% by mass, and the total content of additives in the base layer is 10 to 30% by mass.
And the difference in the total addition amount between the surface layer and the base layer is 5 to 30% by mass.
The cellulose ester film according to claim 2, wherein 6. The content of fine particles in at least one surface layer is 0.1% by mass or more, and the content of fine particles in the base layer is less than 0.01% by mass.
The cellulose ester film according to any one of 5 above. 7. A film thickness of 10 to 60 μm, 25 ° C., 90
The water vapor transmission rate in% RH is 20-250 g / m < ² >; 24 hours, The cellulose-ester film of any one of Claims 1-6 characterized by the above-mentioned. 8. A method for producing a cellulose ester film having a multilayer structure having at least a base layer and a surface layer by a solution casting method, wherein a primary particle diameter in the dope is 1 to 20 nm.
For the surface layer containing 0.02% by mass or more of the fine particles of non-phosphate ester plasticizer in an amount of 0 to less than 2% by mass, and a base layer containing 2 to 10% by mass of the non-phosphate ester plasticizer. A method for producing a cellulose ester film, which comprises co-casting or sequentially casting a dope. 9. The method for producing a cellulose ester film according to claim 8, wherein the non-phosphate ester plasticizer has three or more aromatic rings or cycloalkyl rings in the molecule. 10. A method for producing a cellulose ester film having a multilayer structure having at least a base layer and a surface layer by a solution casting method, wherein the drying time on the cast support is 30 to 120 seconds. The method for producing a cellulose ester film according to claim 8 or 9, which is characterized in that. 11. An optical film using the cellulose ester film according to any one of claims 1 to 6. 12. A polarizing plate comprising the cellulose ester film according to any one of claims 1 to 6. 13. A display device using the optical film according to claim 11.