JP2002212338A - Cellulose acylate, cellulose acylate solution and cellulose acylate film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a cellulose acylate solution having excellent stability with time and a low viscosity in a practicable dope concentration range. SOLUTION: A cellulose acylate in which the total of acyl substitution degree at the 2- and the 3-positions is >=1.70 and <=1.90 and the acyl substitution degree at the 6-position is >=0.88 is used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a cellulose acylate, a cellulose acylate solution, a method for preparing the same, a cellulose acylate film, and a method for producing the same.

[0002]

2. Description of the Related Art Cellulose acylate films are used for various photographic materials and optical materials because of their toughness and flame retardancy. Cellulose acylate film is a typical support for photographic light-sensitive materials. Further, the cellulose acylate film has been used in a liquid crystal display device whose market has been expanding in recent years due to its optical isotropy. As a specific application in the liquid crystal display device, a protective film of a polarizing plate and a color filter are typical.

[0003] Cellulose acylate films are generally produced by a solvent casting method or a melt casting method. In the solvent casting method, a solution (dope) in which cellulose acylate is dissolved in a solvent is cast on a support, and the solvent is evaporated to form a film. In the melt casting method, a film obtained by melting cellulose acylate by heating is cast on a support and cooled to form a film. The solvent cast method can produce a good film having higher flatness than the melt cast method. For this reason, practically, the solvent cast method is generally employed. The solvent casting method is described in many documents. In the recent solvent casting method, it is an issue to improve the productivity of the film forming process by reducing the time required from casting the dope on the support to peeling off the formed film on the support. Has become. For example, Japanese Patent Publication No. 17844/1993 proposes to reduce the time from casting to stripping by casting a high concentration dope on a cooling drum.

[0004] The solvent used in the solvent casting method requires various conditions in addition to simply dissolving cellulose acylate. In order to economically and efficiently produce a film having excellent flatness and uniform thickness, it is necessary to prepare a solution (dope) having an appropriate viscosity and a polymer concentration and having excellent storage stability. About dope,
It is also required that gelation is easy and separation from the support is easy. To prepare such a dope, the choice of solvent type is very important. The solvent is required to be easily evaporated and to have a small residual amount in the film. Various organic solvents have been proposed as solvents for cellulose acylate. Practical organic solvents are substantially limited to methylene chloride, but methylene chloride has problems such as its environmental suitability and boiling point, and a search has been made for alternative solvents. I have.

[0005] M. G. FIG. Cowie et al., Mak
romol, chem. 143, 105 (197
1 year) is obtained by converting cellulose acylate having a substitution degree of 2.80 to 2.90 into acetone from −80 ° C. to −70 ° C.
It was reported that a dilute solution in which cellulose acylate was dissolved in acetone at a concentration of 0.5 to 5% by mass was obtained by cooling and then heating (however, the acyl group here was used). Is limited to acetyl groups). Less than,
The method of cooling the mixture of the cellulose acylate and the organic solvent to obtain a solution is referred to as a “cooling dissolution method”. For dissolution of cellulose acylate in acetone, see Kenji Ude et al., "Dry spinning of cellulose triacetate from acetone solution", Journal of the Textile Machine Society, 34
Vol. 57, 1981. This paper, as its title, applied the cooling melting method to the technical field of spinning method. In the paper, the cooling dissolution method is studied while paying attention to the mechanical properties, dyeability and cross-sectional shape of the obtained fiber. In this paper, a solution of cellulose acetate having a concentration of 10 to 25% by weight is used for spinning the fibers. In addition to the above-mentioned cooling dissolution, a “high-temperature dissolution method” for dissolving a mixture under high-temperature and high-pressure conditions has been proposed.

[0006] In the casting method, a cellulose acylate solution (dope) dissolved in various solvents is cast on a support, the film is peeled off from the support and dried. In many cases, the surface state of the acylate film was not good. That is, since the viscosity of the dope is high, the streaks and the like at the time of casting remain without being smoothed, and the surface is not smooth or sometimes recognized as a streak failure. In order to obtain a good surface condition, the surface must be smoothed by diluting the dope or performing drying under mild conditions, and increasing the manufacturing cost and decreasing the manufacturing speed by taking measures against the surface condition Such problems occur, and countermeasures have been required.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide a cellulose acylate solution having excellent stability over time and having a low viscosity in a practical dope concentration region. Another object of the present invention is to produce a cellulose acylate film having excellent surface properties.

[0008]

The above objects can be attained by the following means (1) to (11). (1) The sum of the degree of acyl substitution at the 2-position and 3-position is 1.70 or more and 1.90 or less, and the degree of acyl substitution at the 6-position is 0.8
Cellulose acylate of 8 or more. (2) The cellulose acylate according to (1), wherein the acyl group is an acetyl group.

(3) A cellulose acylate having a total degree of acyl substitution at the 2- and 3-positions of 1.70 or more and 1.90 or less and a degree of acyl substitution at the 6-position of 0.88 or more is contained in a solvent. Dissolved cellulose acylate solution. (4) The cellulose acylate solution according to (3), wherein the solvent is a substantially chlorine-free solvent. (5) The cellulose acylate solution according to (3), containing silica particles having an average particle diameter of 0.1 μm or less, a plasticizer or an ultraviolet absorber. (6) The cellulose acylate solution according to (3), containing an acid having an acid dissociation index of 1.93 to 4.50 in an aqueous solution, an alkali metal salt thereof, or an alkaline earth metal salt thereof.

(7) A mixture of a cellulose acylate having a total degree of acyl substitution at the 2- and 3-positions of 1.70 or more and 1.90 or less and a degree of acyl substitution at the 6-position of 0.88 or more and a solvent. Is cooled to a temperature of -80 to -10C, or
Alternatively, a method for preparing a cellulose acylate solution, wherein the cellulose acylate is dissolved in a solvent by heating to a temperature of 80 to 220 ° C.

(8) A cellulose acylate containing a cellulose acylate having a total degree of acyl substitution at the 2- and 3-positions of 1.70 or more and 1.90 or less, and a degree of acyl substitution at the 6-position of 0.88 or more. Rate film. (9) The cellulose acylate film according to (8), wherein the cellulose ester film has a multilayer structure of two or more layers, and the thickness of the outer layer on at least one side of the cellulose ester film is 1 to 50 μm.

(10) Cellulose acylate having a total degree of acyl substitution at the 2- and 3-positions of 1.70 to 1.90 and a degree of acyl substitution at the 6-position of 0.88 or more is contained in the solvent. A method for producing a cellulose acylate film, comprising casting a dissolved cellulose acylate solution on a support to form a cellulose acylate film. (11) Cast two or more layers by co-casting (1)
0) The method for producing a cellulose acylate film according to the above.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Cellulose Acylate Raw Material Cell
Loin includes cotton linters and wood pulp. two kinds
You may mix and use the above-mentioned raw material cellulose. cell
Loose acylate has an acetyl group or a carbon number of 3 to
It is a cellulose acylate having 22 acyl groups.
Examples of acyl groups having 3 to 22 carbon atoms include propanoyl
Group (C _TwoH_FiveCO-), butanoyl group (C_ThreeH₇CO
-) (N-, iso-), valeroyl group (C_FourH₉CO-)
(N-, iso-, sec-, tert-), octanoyl, dodeca
Contains noyl, octadecanoyl and oleoloyl
You. Propanoyl and butanoyl are preferred. Cellulo
Ostriacetate is the most preferred cellulose acylate
It is.

When the acylating agent for the acyl group is an acid anhydride or an acid chloride, an organic solvent is used as a reaction solvent. Examples of the organic solvent include an organic acid (eg, acetic acid) and methylene chloride. The degree of substitution of the hydroxyl group is 2.6
-3.0 is preferred. The polymerization degree (viscosity average) of the cellulose acylate is preferably from 200 to 700, and more preferably from 250 to
550 is more preferred. The water content of the cellulose acylate is preferably 2% by mass or less.

In the present invention, a cellulose acylate having a total degree of acyl substitution at the 2- and 3-positions of 1.70 to 1.90 and a degree of acyl substitution at the 6-position of 0.88 or more is used. The glucose units forming cellulose having β-1,4 bond have free hydroxyl groups at the 2-, 3- and 6-positions. Cellulose acylate is a polymer obtained by esterifying some or all of these hydroxyl groups with acetic acid. The degree of acyl substitution is 2-position, 3-position and 6-position.
For each of the positions, the ratio of esterification of cellulose (100% esterification is 1.00). In the cellulose acylate used in the present invention, the second position,
The total degree of acyl substitution at the 3-position is 1.70 or more and 1.90 or less, and the degree of acyl substitution at the 6-position is 0.88 or more.

The sum of the degree of acyl substitution at the 2-position and 3-position is 1.7.
When the value is 0 or less, the film easily absorbs moisture and is easily subjected to hydrolysis, so that the durability of the film decreases. In addition, dimensional changes due to humidity and the like also increase. Conversely, 1.9
If it is 0 or more, the organicity of the cellulose acylate increases, so that the affinity with the solvent increases and the viscosity of the dope increases. Therefore, the sum of the degree of acyl substitution at the 2- and 3-positions is preferably 1.70 or more and 1.90 or less,
More preferably, it is 1.75 or more and 1.88 or less. On the other hand, the degree of acyl substitution at the 6-position must be 0.88 or more, and if it is less than 0.88, the solubility in a solvent is significantly reduced, which is not preferable. This is because the hydroxyl group at the 6-position is a primary hydroxyl group, unlike the hydroxyl groups at the 2- and 3-positions, so that hydrogen bonding of the hydroxyl groups is extremely easy to occur. In addition, the range of the degree of acyl substitution at the 6-position is preferably from 0.88 to 0.99 in consideration of synthesis suitability,
0.89 or more and 0.98 or less are more preferable.

Incidentally, Japanese Patent Application Laid-Open No. 11-5851 discloses that
The sum of the acetyl substituents at the 2-, 3-, and 6-positions is 2.67 or more, and the sum of the acetyl substituents at the 2-, 3-position is 1.9.
Seven or less cellulose acetates are described. The range where the sum of the 2-position and the 3-position exceeds 1.90 is preferable from the optical aptitude of the film. However, from the viewpoint of the viscosity of the dope, 1.90 or less is more preferable.

The basic principle of the method for synthesizing cellulose acylate is described in Migita et al., Wood Chemistry, pp. 180-190 (Kyoritsu Shuppan, 1968). A typical synthesis method is a liquid phase acetylation method using an acetic anhydride-acetic acid-sulfuric acid catalyst. Specifically, after a cellulose raw material such as wood pulp is pre-treated with an appropriate amount of an organic acid, it is put into a pre-cooled acylation mixed solution to be esterified, and complete cellulose acylate (2nd, 3rd and 6th positions) The sum of the degree of acyl substitution is approximately 3.00). The acylation mixture is generally
It contains an organic acid as a solvent, an organic acid anhydride as an esterifying agent and sulfuric acid as a catalyst. The anhydrous organic acid is usually used in a stoichiometric excess of the sum of the cellulose that reacts with it and the water present in the system. After the completion of the acylation reaction, a neutralizing agent (for example, calcium, magnesium, iron, aluminum or zinc) is used to hydrolyze the excess organic anhydride remaining in the system and neutralize a part of the esterification catalyst. (Carbonate, acetate or oxide). Next, the obtained complete cellulose acylate is added to a small amount of an acetylation reaction catalyst (generally,
By maintaining the temperature at 50 to 90 ° C. in the presence of (sulfuric acid remaining), saponification aging is performed to change the cellulose acylate to a desired acyl substitution degree and polymerization degree. When the desired cellulose acylate is obtained, the catalyst remaining in the system may be completely neutralized with the neutralizing agent as described above, or may be neutralized with water or dilute sulfuric acid. A cellulose acylate solution is put therein (or water or dilute sulfuric acid is put into the cellulose acylate solution) to separate the cellulose acylate, and the cellulose acylate is obtained by washing and stabilizing treatment.

In the ordinary method for synthesizing cellulose acylate, the degree of acyl substitution at the 2- or 3-position is higher than the degree of acyl substitution at the 6-position. Therefore, in order to make the sum of the degree of acyl substitution at the 2- and 3-positions 1.90 or less and to make the degree of acyl substitution at the 6-position 0.88 or more, it is necessary to adjust the above reaction conditions in particular. is there. As specific reaction conditions, it is preferable to reduce the amount of the sulfuric acid catalyst and lengthen the time of the acylation reaction. When the amount of the sulfuric acid catalyst is large, the progress of the acylation reaction is accelerated, but a sulfate ester is generated between the cellulose and the cellulose in accordance with the amount of the catalyst, and is liberated at the end of the reaction to generate a residual hydroxyl group. Sulfate is highly reactive 6
Generates more in place. Therefore, if there is much sulfuric acid catalyst, 6
The degree of acyl substitution at the position. Therefore, in order to synthesize the cellulose acylate used in the present invention, it is necessary to reduce the amount of the sulfuric acid catalyst as much as possible, thereby extending the reaction time in order to compensate for the reduced reaction rate.

The cellulose acylate film preferably has a polymer component constituting the film substantially composed of cellulose acetate having the above definition. "Substantially" means at least 90% by weight of the polymer component (preferably at least 95% by weight, more preferably at least 98% by weight, most preferably at least 99% by weight). As a raw material for producing a film, it is preferable to use cellulose acetate particles. 90% by weight of the particles used
The above preferably has a particle diameter of 1 to 4 mm. Also, 50% by weight or more of the particles used is 2 to 3 m.
It preferably has a particle size of m. It is preferable that the cellulose acetate particles have a shape as close to spherical as possible.

It is preferable to produce a cellulose acylate film by a solvent casting method. In the solvent casting method, a film is manufactured using a cellulose acylate dope. The organic solvent used for preparing the dope is preferably a substantially non-chlorine solvent.
“Substantially non-chlorinated” refers to a solvent containing at least one chlorine atom in the structural formula (eg, dichloromethane, dichloroethane,
Chlorobenzene) is preferably 40 vol% or less, more preferably 15 vol% or less, and more preferably 5 vol% or less.
It is more preferably at most vol%, more preferably at most 1 vol%, most preferably at 0 vol%. The non-chlorinated solvent may be composed of a compound having 3 to 12 carbon atoms. The solvent is preferably selected from the group consisting of esters, ethers, ketones and alcohols. Esters, ethers, ketones and alcohols may have a linear, branched or cyclic structure. Functional groups of esters, ethers, ketones and alcohols (i.e., -COO-, -O-, -CO-
And -OH) can also be used as the solvent.

Examples of esters include methyl formate, ethyl formate, propyl formate, methyl acetate and ethyl acetate. Methyl formate, ethyl formate and methyl acetate are preferred, and methyl acetate is more preferred. Examples of ketones include:
Acetone, methyl ethyl ketone, diethyl ketone, methyl isobutyl ketone, cyclopentanone and cyclohexanone. Acetone, cyclopentanone and cyclohexanone are preferred, and acetone and cyclopentanone are more preferred. Examples of ethers include dibutyl ether, dimethoxymethane, dimethoxyethane, 1,4-dioxane, 1,3-dioxolan, tetrahydrofuran, anisole and phenetole. Examples of alcohol include methanol, ethanol,
1-propanol, 2-propanol, 1-butanol, 2-butanol, cyclohexanol, 2-fluoroethanol, 2,2,2-trifluoroethanol are included. Methanol, ethanol, 1-propanol, 2-propanol and 1-butanol are preferred, and methanol and ethanol are more preferred. Esters and ketones preferably have a solubility parameter of 19-21.

Two or more kinds of solvents may be used as a mixture. It is preferable to use a mixture of an ester having a solubility parameter of 19 to 21 and a ketone having a solubility parameter of 19 to 21. It is preferable to mix an alcohol in addition to the ester and the ketone. As a combination of solvents, methyl acetate / cyclopentanone / acetone / methanol / ethanol (60/15/1
5/5/5, parts by mass), methyl acetate / acetone / methanol / ethanol (75/15/5/5, parts by mass), methyl acetate / cyclohexanone / methanol / 1-butanol (70/20/5/5, Parts by mass) and methyl formate / methyl ethyl ketone / acetone / methanol / ethanol (50/20/20/5/5, parts by mass), preferably methyl acetate / acetone / methanol / ethanol
(75/15/5/5, parts by mass), methyl acetate / cyclopentanone / methanol / ethanol (80/10/5
/ 5, parts by mass).

In order to prepare a cellulose acylate solution, the above-mentioned cellulose acylate is added while stirring the solvent in the tank at room temperature to first swell the solvent. The swelling time must be at least 10 minutes or more, and if it is less than 10 minutes, insoluble matter remains. Further, in order to sufficiently swell the cellulose acylate, the temperature of the solvent is 0 to 40 ° C.
Is preferred. At 0 ° C. or lower, the swelling rate tends to decrease and insolubles tend to remain. At 40 ° C. or higher, the swelling occurs rapidly and the central portion does not swell sufficiently. In order to dissolve the cellulose acylate after the swelling step, it is preferable to use one or both of a cooling dissolution method and a high temperature dissolution method.

In the cooling dissolution method, first, a temperature around room temperature (-1)
(0 to 40 ° C.), the cellulose acylate is gradually added to the organic solvent with stirring. After adding the cellulose acylate to the main solvent (eg, ester, ketone), an auxiliary solvent (eg, alcohol) may be added. The main solvent may be added after moistening the cellulose acylate in advance with an auxiliary solvent (eg, alcohol). It is preferable to adjust the amount of cellulose acylate so that the amount is 10 to 40% by mass in the mixture. More preferably, the amount of cellulose acylate is 10 to 30% by mass. Further, an optional additive described below may be added to the mixture. Next, the mixture is -100 to -10
° C, more preferably -80 to -10 ° C, still more preferably -50 to -20 ° C, and most preferably -50 to-
Cool to 30 ° C. Cooling, for example, dry ice
It can be carried out in a methanol bath (−75 ° C.) or a cooled diethylene glycol solution (−30 to −20 ° C.). The faster the cooling rate, the better, and preferably 100 ° C./sec or more. In addition, it is desirable to use a closed container in order to avoid water contamination due to dew condensation during cooling. After cooling, 0-20
0 ° C. (preferably 0 to 150 ° C., more preferably 0 ° C.
To 120 ° C., most preferably 0 to 50 ° C.), a solution in which cellulose acylate is dissolved in an organic solvent is obtained. The heating may be simply left at room temperature. Also, the cooled mixture may be heated in a warm bath. When the pressure is increased during cooling and the pressure is decreased during heating, the dissolution time can be shortened. In order to perform pressurization and decompression, it is desirable to use a pressure-resistant container. The operation of cooling and heating may be repeated two or more times.

In the high-temperature melting method, the temperature around room temperature (−10
-40 ° C.), and slowly add the cellulose acylate to the organic solvent with stirring. After adding the cellulose acylate to the main solvent (eg, ester, ketone), an auxiliary solvent (eg, alcohol) may be added. The main solvent may be added after moistening the cellulose acylate in advance with an auxiliary solvent (eg, alcohol). Cellulose acylate can be added to a mixed organic solvent in advance to cause swelling. In any solvent at −10 to 40 ° C., cellulose acylate may be gradually added with stirring, or may be swelled in advance with a specific solvent in some cases, and then added with another combined solvent and mixed. And the remaining solvent may be added after swelling with two or more solvents. The dissolution concentration of cellulose acylate is 5% by mass
To 30% by mass, more preferably 15% by mass to
30% by mass, more preferably 17% by mass to 25% by mass. Next, the cellulose acylate and the solvent mixture are
70 under pressure of 0.2Mpa-30MPa in pressure vessel
To 240 ° C, more preferably 80 to 220 ° C, still more preferably 100 to 200 ° C, and most preferably 100 to 19 ° C.
Heat to 0 ° C. Thereafter, the mixture is cooled to a temperature lower than the lowest boiling point of the solvent used. In that case, it is common to cool to −10 to 50 ° C. and return to normal pressure. The cooling may be performed only at room temperature, and more preferably a coolant such as cooling water may be used. The operation of heating and cooling may be repeated two or more times.

The cellulose acylate may be dissolved at a low concentration and then concentrated. When preparing the cellulose acylate solution, it is preferable to fill the inside of the container with an inert gas such as a nitrogen gas to cope with explosion-proof. The viscosity of the cellulose acylate solution immediately before film formation is adjusted within a range that can be cast during film formation. Viscosity is 10 Pa · s to 2000 Pa
· S, preferably 30 Pa · s to 40
More preferably, it is 0 Pa · s. The temperature during casting is preferably -5 to 70C, and -5 to 70C.
More preferably, it is 55 ° C. The concentration of the cellulose acylate solution is preferably 5 to 40% by mass,
30 mass% is more preferable.

Various additives depending on the application can be added to the cellulose acylate solution in each preparation step. These additives are plasticizers, UV inhibitors and deterioration inhibitors (eg, antioxidants, peroxide decomposers, radical inhibitors, metal deactivators, acid scavengers, amines). Examples of plasticizers include triphenyl phosphate (TP
P), diphenylbiphenyl phosphate, tricresyl phosphate (TCP), dioctyl phthalate (D
OP), tributyl O-acetylcitrate (OACT
B) and acetyltriethyl citrate. As plasticizers for reducing optical anisotropy, (di) pentaerythritol esters (described in JP-A-11-124445) and glycerol esters (described in JP-A-11-2)
46704), diglycerol esters (described in JP-A-2000-63560), citrate esters (described in JP-A-11-92574), or substituted phenylphosphate esters (described in JP-A-11-909).
No. 46) may be used. Two or more plasticizers may be used in combination. The amount of the plasticizer is preferably 5 to 30% by mass based on the cellulose acylate,
-16 mass% is more preferable.

As for the deterioration inhibitor and the ultraviolet inhibitor, JP-A-60-235852 and JP-A-3-199201.
No., 5-1907073, 5-194789,
5-271471, 6-107854, 6-
Nos. 118233, 6-148430, 7-110
Nos. 56, 7-11055, 7-11056, 8-29619, 8-239509, JP-A-200
It is described in each publication of JP-A No. 0-204173. Examples of the deterioration inhibitor include butylated hydroxytoluene (BHT). The ultraviolet absorbent is preferably a compound having an ability to absorb ultraviolet light having a wavelength of 370 nm or less and having little absorption of visible light having a wavelength of 400 nm or more. Examples of UV absorbers include
Oxybenzophenone compounds, benzotriazole compounds, salicylate compounds, benzophenone compounds, cyanoacrylate compounds, and nickel complex compounds are included. Benzotriazole compounds and benzophenone compounds are preferred. The addition amount of the deterioration inhibitor and the ultraviolet inhibitor is preferably from 1 ppm to 10000 ppm, more preferably from 10 to 1000 ppm by mass ratio to the cellulose acylate.

The in-plane retardation (Re) of the cellulose acylate film is preferably in the range of 0 to 300 nm. Film thickness direction retardation (Rth)
Is preferably 0 nm to 600 nm, more preferably 0 nm to 400 nm, and most preferably 0 nm to 250 nm per 100 μm thickness.

A release agent can be added before casting the cellulose acylate solution. The release agent is preferably an acid having an acid dissociation index (pKa) of 1.93 to 4.50 in an aqueous solution, or an alkali metal salt or an alkaline earth metal salt thereof. As the acid, any of an inorganic acid and an organic acid can be used. Examples of inorganic acids include HClO ₂ (2.3
1), HOCN (3.48), molybdic acid (H ₂ Mo)
O ₄ , 3.62), HNO ₂ (3.15), phosphoric acid (H
₃ PO ₄ , 2.15), triphosphoric acid (H ₅ P ₃ O ₁₀ ,
2.0) and vanadate (H ₃ VO _4, 3.78) are included. The values in parentheses are the acid dissociation index (pKa) in an aqueous solution (the same applies to the following acids). As organic acids, carboxylic acids, sulfonic acids and phosphoric acids are representative. The carboxylic acids include aliphatic monocarboxylic acids, aliphatic polycarboxylic acids, oxycarboxylic acids, aldehyde acids,
Ketone acids, aromatic monocarboxylic acids, aromatic polycarboxylic acids, heterocyclic monocarboxylic acids, heterocyclic polycarboxylic acids and amino acids are included.

Examples of the aliphatic monocarboxylic acids include formic acid (3.55), oxaloacetic acid (2.27), cyanoacetic acid (2.47), phenylacetic acid (4.10), and phenoxyacetic acid (2.99). ), Fluoroacetic acid (2.59), chloroacetic acid (2.68), bromoacetic acid (2.72), iodoacetic acid (2.98), mercaptoacetic acid (3.43), vinylacetic acid (4.12), Chloropropionic acid (2.71-
3.92), 4-aminobutyric acid (4.03) and acrylic acid (4.26). Examples of the aliphatic polycarboxylic acid include malonic acid (2.65) and succinic acid (4.0).
0), glutaric acid (4.13), adipic acid (4.2)
6), pimelic acid (4.31), azelaic acid (4.3)
9) and fumaric acid (2.85). Examples of oxycarboxylic acids include glycolic acid (3.63) and lactic acid (3.
66), malic acid (3.24), tartaric acid (2.82-
2.99) and citric acid (2.87), examples of aldehyde acids include glyoxylic acid (3.18). Examples of ketone acids include pyruvate (2.26) and levulinic acid (4.44).

Examples of the aromatic monocarboxylic acid include anilinesulfonic acid (3.74-3.23) and benzoic acid (4.2).
0), aminobenzoic acid (2.02-3.12), chlorobenzoic acid (2.92-3.99), cyanobenzoic acid (3.60-3.55), nitrobenzoic acid (2.17-
3.45), hydroxybenzoic acid (4.08-4.5).
8), anisic acid (4.09-4.48), fluorobenzoic acid (3.27-4.14), chlorobenzoic acid, bromobenzoic acid (2.85-4.00), iodobenzoic acid (2 86-4.00), salicylic acid (2.81), naphthoic acid (3.70-4.16), cinnamic acid (3.8)
8) and mandelic acid (3.19). Examples of aromatic polycarboxylic acids include phthalic acid (2.75), isophthalic acid (3.50) and terephthalic acid (3.54)
Is included. Examples of heterocyclic monocarboxylic acids include nicotinic acid (2.05) and 2-furancarboxylic acid (2.9)
7) is included. Examples of heterocyclic polycarboxylic acids include:
2,6-pyridinedicarboxylic acid (2.09) is included.

The amino acids include, in addition to ordinary amino acids,
Amino acid derivatives (including substituted amino acids and oligopeptides. Examples of amino acids include asparagine (2.14), aspartic acid (1.93), adenine (4.07), alanine (2.30), β-alanine (3.53), arginine (2.05), isoleucine (2.32), glycine (2.36), glutamine (2.17), glutamic acid (2.18), serine (2.13) , Tyrosine (2.17), tryptophan (2.35), threonine (2.21), norleucine (2.30), valine (2.26), phenylalanine (2.26), methionine (2.15), Lysine (2.
04), leucine (2.35), adenosine (3.5)
0), adenosine triphosphate (4.06), adenosine phosphate (3.65-3.80), L-alanyl-L-alanine (3.20), L-alanylglycine (3.1)
0), β-alanylglycine (3.18), L-alanylglycylglycine (3.24), β-alanylglycylglycine (3.19), L-alanylglycylglycylglycine (3.18) ), Glycyl-L-alanine (3.07), glycyl-β-alanine (3.91),
Glycylglycyl-L-alanine (3.18), glycylglycylglycine (3.20), glycylglycylglycylglycine (3.18), glycylglycyl-L-
Histidine (2.72), glycylglycylglycyl-
L-histidine (2.90), glycyl-DL-histidylglycine (3.26), glycyl-L-histidine (2.54), glycyl-L-leucine (3.09),
γ-L-glutamyl-L-cysteinylglycine (2.
03), N-methylglycine (sarcosine, 2.2
0), N, N-dimethylglycine (2.08), citrulline (2.43), 3,4-dihydroxyphenylalanine (2.31), L-histidylglycine (2.8)
4), L-phenylalanylglycine (3.02), L
-Prolylglycine (3.07) and L-leucyl-
L-tyrosine (3.15) is included.

Also, sulfonic acid and phosphoric acid can be used as a release agent. Surfactants (JP-A-61-24)
3837) can also be used as a release agent. Examples of surfactants used as release agents include C
_{12 H 25 O-P (=} O) - (OK) 2, C 12 H 25 OCH 2
_{CH 2 O-P (= O} ) - (OK) 2 and (iso-C ₉ H
_{19) 2 -C 6 H 3 -O-} (CH 2 CH 2 O) 3 - (CH
₂ ) Contains ₄ SO ₃ Na.

The acid may be used in the form of an alkali metal salt or an alkaline earth metal salt instead of the free acid. Examples of the alkali metal include lithium, potassium and sodium. Sodium is particularly preferred. Examples of alkaline earth metals include calcium, magnesium, barium and strontium. Calcium and magnesium are particularly preferred. Alkali metals are more preferred than alkalinity metals. Alkali metals or alkaline earth metals may be used in combination of two or more. An alkali metal and an alkaline earth metal may be used in combination.

The total content of the acid or metal salt is determined within a range that does not impair the releasability or transparency. The content is 1 × 10 ^{−9 to} 3 × 10 ⁻⁵ per 1 g of cellulose acylate.
Mol, preferably 1 × 10 ⁻⁸ to 2 × 10 ⁻⁵ mol, more preferably 1 × 10 ^{−7 to} 1.5 × 1 mol.
More preferably from 0 ^-5 mol, 5 × 10 ^-7 ~1
X 10 ^-5 mol is still more preferable, and 6 x 1
Most preferably, it is 0 ^-7 to 8 × 10 ^-6 mol.

Addition of fine particles (matting agent)
It can also prevent creaking. Fine particles are made from inorganic substances
Preferably, Examples of inorganic substances include silica and chao.
Phosphorus, talc, diatomaceous earth, quartz, calcium carbonate, sulfur
Barium acid, titanium oxide, alumina, manganese colloid
, Titanium dioxide, strontium barium sulfate, diacid
Silicon oxide, alkaline earth metal (eg, calcium, magne
Salt). Film by adding fine particles
The average height of the surface projections is 0.005 to 10 μm.
Is preferably 0.01 to 5 μm.
Preferred. The shape of the particles is spherical or amorphous
Is preferred. The content of the fine particles in the film is 0.
5 to 600 mg / m^TwoAnd preferably 1 to 40
0mg / m ^TwoIs more preferable.

The solution before casting may be treated with a suitable filter medium (eg, wire mesh,
It is preferable to remove foreign matter (eg, undissolved matter, dust, impurities) using paper or flannel. The absolute filtration accuracy of the filter used for solution filtration is preferably 0.05 to 100 μm, and more preferably 0.5 to 10 μm. The filtration pressure is preferably at most 16 kg / cm ^2, more preferably at most 12 kg / cm ² , still more preferably at most 10 kg / cm ² , most preferably at most ² kg / cm ^2. .

As a method and equipment for producing a cellulose acylate film, a conventional solution casting film forming method and a conventional solution casting film forming apparatus used for producing a conventional cellulose triacetate film can be used. The dope (cellulose acylate solution) prepared from the dissolving tank (tank) is temporarily stored in a stock tank, and bubbles contained in the dope are defoamed or final prepared. The dope is fed from the dope discharge port to the pressurized die through a pressurized metering gear pump capable of, for example, high-precision quantitative liquid feeding according to the number of rotations, and the dope of the casting section running endlessly from the die (slit) of the pressurized die. At the peeling point where the support is evenly cast on the support and the support substantially makes a round, the freshly dried dope film (also referred to as a web) is peeled from the support. Clip the ends of the resulting web with clips,
While maintaining the width, the sheet is conveyed by a tenter and dried. Subsequently, the sheet is conveyed by a group of rolls of a drying device, dried, and wound up to a predetermined length by a winder. The combination of the tenter and the roll group drying device varies depending on the purpose. In a solution casting film forming method used for a silver halide photographic material or a functional protective film for an electronic display, in addition to a solution casting film forming apparatus, various layers (undercoat layer, antistatic layer, antihalation layer, etc.) , A protective layer) on the support is often provided with a coating device.

The obtained cellulose acylate solution is cast on a smooth band or a drum as a support. A plurality of cellulose acylate liquids may be successively cast or co-cast to produce two or more cellulose acylate films. For example, when casting a plurality of cellulose acylate solutions, a film containing cellulose acylate is cast from a plurality of casting ports provided at intervals in the traveling direction of the support, and a film is produced while being laminated. (Described in JP-A-11-198285). Also, a method of casting a cellulose acylate solution from two casting ports to form a film (described in JP-A-6-134933) can be performed. A cellulose acylate film casting method comprising wrapping a flow of a high-viscosity cellulose acylate solution with a low-viscosity cellulose acylate solution and simultaneously extruding the high- and low-viscosity cellulose acylate solutions (Japanese Patent Application Laid-Open No. 56-162617). Gazette). By performing such co-casting, as described above, smoothing in the drying of the surface proceeds, so that a significant improvement in the surface state can be expected. In the case of co-casting, the thickness of each layer is not particularly limited, but preferably the outer layer is preferably thinner than the inner layer. In this case, the thickness of the outer layer is preferably from 1 to 50 μm, particularly preferably from 1 to 30 μm. Here, the surface layer means a non-band surface (drum surface) in the case of two layers, and a layer on both surface sides of a completed film in the case of three or more layers. The inner layer is a band surface (drum surface) in the case of two layers. In the case of three or more layers, a layer inside the surface layer is shown. Cellulose acylate solution is used for other functional layers (eg, adhesive layer, dye layer, antistatic layer, antihalation layer, UV absorbing layer, polarizing layer)
It can be cast at the same time.

The drying temperature in the drying step is 30 to 25.
0 ° C is preferable, and 40 to 180 ° C is more preferable. The drying step is described in JP-B-5-17844. A method of positively stretching the film in the width direction (Japanese Patent Application Laid-Open No. 62-115035, Japanese Patent Application Laid-Open No.
No. 5, 4-284221, 4-298310,
11-48271). Uniaxial stretching or biaxial stretching can be employed for stretching the film. The stretching ratio of the film (ratio of increase by stretching to the original length) is preferably 10 to 30%.

The thickness of the finished (after drying) cellulose acylate film varies depending on the purpose of use, but is usually in the range of 5 to 500 μm, and more preferably 20 to 250 μm.
Is particularly preferable, and the range of 30 to 180 μm is most preferable. In addition, the range of 30 to 110 μm is particularly preferable for optical use. The film thickness may be adjusted by adjusting the concentration of the solid content contained in the dope, the slit gap of the die, the extrusion pressure from the die, and the speed of the support so as to obtain the desired thickness.

The surface treatment of the cellulose acylate film may improve the adhesion between the cellulose acylate film and each functional layer (for example, an undercoat layer and a back layer). The surface treatment includes glow discharge treatment, ultraviolet irradiation treatment, corona treatment, flame treatment, acid or alkali treatment. Acid or alkali treatment is preferred, and alkali treatment is more preferred. The acid or alkali treatment functions as a saponification treatment for the cellulose acylate film. The alkali saponification treatment is preferably performed by immersing the film surface in an alkaline solution, neutralizing the film surface with an acidic solution, washing with water, and drying. Examples of the alkaline solution include a potassium hydroxide solution and a sodium hydroxide solution, and the specified concentration of the hydroxide ion is 0.1N to 3.0N.
Is preferable, and 0.5N to 2.0N is more preferable. The temperature of the alkali solution is preferably from room temperature to 90 ° C, more preferably from 30 ° C to 70 ° C. Next, the cellulose acylate film is generally washed with water and then passed through an acidic aqueous solution and then washed with water to obtain a surface-treated cellulose acylate film.
At this time, the acid includes hydrochloric acid, nitric acid, sulfuric acid, acetic acid, formic acid, chloroacetic acid, oxalic acid, etc., and the concentration thereof is 0.01N.
-3.0N is preferable and 0.05N-2.0N is more preferable. In order to achieve adhesion between the cellulose acylate film support and the functional layer, it is also preferable to provide an undercoat layer (adhesive layer) and apply the functional layer thereon.

In the construction of the protective film for a polarizing plate, it is preferable that at least one layer of the cellulose acylate film is provided with an antistatic layer or a hydrophilic binder layer for bonding to a polarizer. As a conductive material,
Conductive metal oxides and conductive polymers are preferred. In addition,
A transparent conductive film formed by vapor deposition or sputtering may be used. The conductive layer may be the outermost layer or the inner layer without any problem.
Regarding the power transmission of the conductive layer, the resistance is preferably from 10 ⁰ to 10 ¹² Ω, and particularly preferably from 10 ⁰ to 10 ¹⁰ Ω. Metal oxides are preferred. Examples of metal oxides include Z
nO, TiO ₂ , SnO ₂ , Al ₂ O ₃ , In ₂ O ₃ ,
SiO ₂ , MgO, BaO, MoO ₂ , V ₂ O ₅ and composite oxides are included. ZnO, SnO ₂ and V ₂ O
₅₅ is preferred. Examples of the conductive ionic polymer compound include an ionene-type polymer having a dissociating group in the main chain and a cationic pendant polymer having a cationic dissociating group in a side chain. As the conductive material, an organic electron conductive material is preferable. Examples of the organic electron conductive material include a polyaniline derivative, a polythiophene derivative, a polypyrrole derivative, and a polyacetylene derivative.

A surfactant can be preferably added to any of the functional layers of the cellulose acylate film. Nonionic, cationic and betaine surfactants are preferred. Fluorinated surfactants can also be used. The surfactant can function as a coating agent or an antistatic agent in an organic solvent. It is preferable to include a slipping agent in any of the layers above the cellulose acylate film. Examples of the slipping agent include polyorganosiloxane (described in JP-B-53-292), higher fatty acid amide (described in U.S. Pat. No. 4,275,146), and higher fatty acid ester (British patent 927446, described in JP-B-58-33541). No., JP-A-55-126
238 and 58-90633). The higher fatty acid ester has 10 to 2 carbon atoms.
An ester of a fatty acid having 4 and an alcohol having 10 to 24 carbon atoms.

The cellulose acylate film formed from the cellulose acylate solution can be used for various purposes. The cellulose acylate film is particularly effective when used as an optical compensation sheet for a liquid crystal display. As the cellulose acylate film, the film itself can be used as an optical compensation sheet. When the film itself is used as the optical compensation sheet, the transmission axis of the polarizing element (described later) and the slow axis of the optical compensation sheet made of the cellulose acylate film are arranged so as to be substantially parallel or perpendicular. Is preferred. The arrangement of such a polarizing element and an optical compensation sheet is described in JP-A-10-48420.
The liquid crystal display device has a liquid crystal cell holding liquid crystal between two electrode substrates, two polarizing elements disposed on both sides thereof,
And at least one optical compensatory sheet is disposed between the liquid crystal cell and the polarizing element. The liquid crystal layer of a liquid crystal cell is usually formed by enclosing liquid crystal in a space formed by sandwiching a spacer between two substrates. The transparent electrode layer is formed on a substrate as a transparent film containing a conductive substance. The liquid crystal cell may further be provided with a gas barrier layer, a hard coat layer or an undercoat layer (used for bonding the transparent electrode layer). These layers are usually provided on a substrate. The substrate of the liquid crystal cell is generally 80 to 5
It has a thickness of 00 μm.

The optical compensation sheet is a birefringent film for removing coloring of the liquid crystal screen. The cellulose acylate film can be used as an optical compensation sheet. Further, a function may be provided as an antireflection layer, an antiglare layer, a λ / 4 layer, or a biaxially stretched cellulose acylate film. Also, to improve the viewing angle of the liquid crystal display device,
A cellulose acylate film and a film exhibiting the opposite birefringence (in a positive / negative relationship) may be overlapped and used as an optical compensation sheet. The range of the thickness of the optical compensation sheet is the same as the preferable thickness of the film described above. Examples of the polarizing film of the polarizing element include an iodine-based polarizing film, a dye-based polarizing film using a dichroic dye, and a polyene-based polarizing film. All polarizing films are generally manufactured using a polyvinyl alcohol-based film. The protective film of the polarizing plate preferably has a thickness of 25 to 350 μm, more preferably 30 to 200 μm. The liquid crystal display device may be provided with a surface treatment film. The functions of the surface treatment film include a hard coat, an anti-fog treatment, an anti-glare treatment and an anti-reflection treatment. As described above, an optical compensatory sheet in which an optically anisotropic layer containing a liquid crystal (particularly discotic liquid crystal molecules) is provided on a support has been proposed (JP-A-3-932).
Nos. 5, 6-148429, 8-50206, and 9-26572). A cellulose acylate film can also be used as a support for such an optical compensation sheet.

The cellulose acylate film is composed of a support of an optical compensation sheet of a VA type liquid crystal display device having a VA mode liquid crystal cell, and an O.sub.2 mode having an OCB mode liquid crystal cell.
Support for optical compensation sheet of CB type liquid crystal display device or HAN type liquid crystal display device having HAN mode liquid crystal cell, ASM (Axially Symmetric Aligned Microcell)
It is preferably used as a support for an optical compensation sheet of an ASM type liquid crystal display device having a mode liquid crystal cell.

[0050]

EXAMPLES In each of the examples, cellulose acylate,
The chemical and physical properties of solutions and films are
It was measured and calculated as follows.

(1) Degree of substitution (%) of cellulose acylate The degree of acetylation was measured by a saponification method. The dried cellulose acylate is precisely weighed and dissolved in a mixed solvent of acetone and dimethylsulfoxide (volume ratio: 4: 1), and then a predetermined amount of a 1N aqueous solution of sodium hydroxide is added thereto, followed by saponification at 25 ° C for 2 hours. did. Phenolphthalein was added as an indicator, and excess sodium hydroxide was titrated with 1N-sulfuric acid (concentration factor: F). A blank test was performed in the same manner as described above. Then, the degree of acetylation (%) was calculated according to the following equation. Degree of acetylation (%) = (6.05 × (BA) × F) / W In the formula, A is the amount of 1N-sulfuric acid (ml) required for titration of the sample
B is the amount of 1N sulfuric acid (ml) required for the blank test, F
Represents a factor of 1N-sulfuric acid, and W represents a sample weight. In the case of a system containing a plurality of acyl groups, the amount of each acyl group was determined using the difference in pKa. In addition, literature (T.Se
i, K.Ishitani, R.Suzuki, K.Ikematsu PolymerJournal 17
1065, 1985). Further, the degree of substitution was converted into the degree of substitution from the determined degree of acetylation and the amount of other acyl groups in consideration of the molar molecular weight. Further, after the acyl substitution degree at the 2-, 3- and 6-positions of the cellulose acylate is acylated with an acyl group not used for the acylation of the cellulose acetate, Carbohydr.
es. 273 (1995) 83-91 (Tezuka et al.).
Determined by MR.

(2) Viscosity-average degree of polymerization (DP) of cellulose acylate Approximately 0.2 g of absolutely dried cellulose acylate is precisely weighed and dissolved in 100 ml of a mixed solvent of methylene chloride: ethanol = 9: 1 (weight ratio). did. This was measured for drop seconds at 25 ° C. using an Ostwald viscometer, and the degree of polymerization was determined by the following equation. ηrel = T / T0 T: Falling seconds of the measured sample [η] = (1nηrel) / C T0: Falling seconds of the solvent alone DP = [η] / Km C: Concentration (g / l) Km: 6 × 10 ^-Four

(3) Solution Stability The state of the obtained solution or slurry was observed while standing at room temperature (23 ° C.) for 20 days, and the following A, B, C,
D was evaluated in four stages. A: Shows transparency and liquid uniformity. B: There is some undissolved residue or slight cloudiness is observed. C: There is a clear undissolved residue or the solution is gelled. D: The liquid is opaque and non-uniform with no swelling / dissolution.

(4) Viscosity of Solution The viscosity of the obtained cellulose acylate solution at 40 ° C. was measured with a Rheometer manufactured by TA Instruments.

(5) Film surface condition The film was visually observed, and the surface condition was evaluated as follows. A: The film surface is smooth and the surface state is very good. B: The film surface is smooth, but irregularities are rarely observed. C: The film surface is smooth, but relatively many weak irregularities are observed. D: Weak irregularities are observed on the entire surface of the film. E: Strong irregularities are seen on the film, and foreign matter is seen.

(6) The haze of the film was measured using a haze meter (Model 1001DP, manufactured by Nippon Denshoku Industries Co., Ltd.).

(1-1) Preparation of Cellulose Acylate Solution A cellulose acylate solution was prepared by the following two dissolution methods. Table 1 shows the detailed solvent composition.
In addition, silica particles (particle size: 20 nm), triphenyl phosphate / biphenyl diphenyl phosphate (1
/ 2), 2,4-bis- (n-octylthio) -6
(4-Hydroxy-3,5-di-tert-butylanilino) -1,3,5-triazine was added to each of 0.5% by mass, 10% by mass, and 1.0% by mass of cellulose acylate.
Was added. Further, 200 ppm of citric acid was added to cellulose acylate as a release agent. In addition, as a liquid for forming the inner layer and the outer layer of co-casting, the above-mentioned cellulose acylate solution was used while changing its concentration. Details are shown in Table 1.

(1-1a) Dissolution by cooling (described as "cooling" in Table 1) Cellulose acylate shown in Table 1 was gradually added to a solvent with good stirring, and the mixture was stirred at room temperature (25 ° C.) for 3 hours. Leave to swell. The resulting swelled mixture was cooled to −30 ° C. at −8 ° C./min with slow stirring, then cooled to the temperature shown in Table 1, and after 6 hours, the temperature was raised at + 8 ° C./min to increase the sol content. At a stage where the conversion to a certain extent proceeded, stirring of the contents was started. The mixture was heated to 50 ° C. to obtain a dope.

(1-1b) High pressure and high temperature melting (Table 1 shows "high temperature")
The cellulose acylate shown in Table 1 was gradually added to the solvent with good stirring, and allowed to stand at room temperature (25 ° C.) for 3 hours to swell. The obtained swollen mixture was placed in a double-walled stainless steel closed container. The mixture was heated at + 8 ° C./min by passing high-pressure steam through the outer jacket of the vessel, and kept at 1 Mpa at the temperature shown in Table 1 for 5 minutes. Thereafter, water at 50 ° C is passed through the outer jacket and cooled to 50 ° C at -8 ° C / min.
A dope was obtained.

(1-2) Filtration of Cellulose Acylate Solution Next, the obtained dope was filtered at 50 ° C. at an absolute filtration accuracy of 0.0
Filter with 1 mm filter paper (Toyo Roshi Kaisha, Ltd., # 63),
Further, the solution was filtered through a filter paper (FH025, manufactured by Pall Corporation) having an absolute filtration accuracy of 0.0025 mm.

(1-3) Preparation of Cellulose Acylate Film The solution of (1-2) was cast using a casting machine described in JP-A-56-162617, and the solution was heated at 120 ° C. for 30 minutes.
After drying for a minute, the solvent was evaporated to obtain a cellulose acylate film. In the present invention, the layer structure is a two-layer or three-layer structure. The two layers have a structure of an inner layer / outer layer from the band surface, and the three layers have a sandwich-type structure of an outer layer / inner layer / outer layer. Details are shown in Table 1.

[0062]

[Table 1]

(1-4) Result The obtained cellulose acylate solution and film were evaluated according to the above-mentioned items. The cellulose acylate solution and the film of the present invention did not show any particular problems in solution stability, mechanical properties and optical properties of the film. On the other hand, in the comparative example, a problem was recognized in the surface state of the obtained film.

These films were stretched 10% to 30% MD and TD at 130 ° C. online or during the drying process during the film forming process. These are 40 nm to 160 nm in proportion to the draw ratio.
The retardation could be increased. The cellulose acylate film thus obtained contains the liquid crystal display device described in Example 1 of JP-A-10-48420 and the discotic liquid crystal molecules described in Example 1 of JP-A-9-26572. Optically anisotropic layer, alignment film coated with polyvinyl alcohol, JP-A-2000-15
VA type liquid crystal display device described in FIGS. 2 to 9 of JP-A-4261, and FIGS. 10 to 15 of JP-A-2000-154261.
When used in the OCB type liquid crystal display device described in (1), good performance was obtained. Further, when used as a polarizing plate described in JP-A-54-016575, good performance was obtained.

[0065]

[Table 2]

[0066]

According to the present invention, the total degree of acyl substitution at the 2-position and 3-position is 1.
A cellulose acylate having a degree of acyl substitution at the 6-position of 70 to 1.90 and a degree of acyl substitution of 0.88 or more, a cellulose acylate solution and a cellulose acylate film using the same, and a cellulose acylate solution obtained by the method for producing the same. The production method of reducing the viscosity of the film and improving the surface condition of the film was achieved.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C08J 5/18 CEP C08J 5/18 CEP C08K 3/36 C08K 3/36 5/00 5/00 // B29K 1:00 B29K 1:00 B29L 9:00 B29L 9:00 F term (reference) 4C090 AA02 AA05 BA25 BA26 BD08 BD18 BD36 DA31 4F071 AA09 AB26 AC09 AC15 AE04 AE05 AE17 AH12 BA02 BB02 BC01 4F205 AA01 AB07 AB12 AB14 A17 AC05 AG GA07 GB01 GB26 GC07 GE22 4J002 AB021 DJ016 EE038 EH087 EH147 EU178 EW047 FD016 FD027 FD058

Claims (11)

[Claims] 1. The sum of the degree of acyl substitution at the 2-position and 3-position is 1.
A cellulose acylate having a degree of acyl substitution at the 6-position of 70 to 1.90 and 0.88 or more. 2. The cellulose acylate according to claim 1, wherein the acyl group is an acetyl group. 3. The sum of the degree of acyl substitution at the 2-position and 3-position is 1.
A cellulose acylate solution in which a cellulose acylate having a degree of acyl substitution at the 6-position of not less than 70 and not more than 1.90 and not less than 0.88 is dissolved in a solvent. 4. The cellulose acylate solution according to claim 3, wherein the solvent is a substantially non-chlorinated solvent. 5. The cellulose acylate solution according to claim 3, further comprising silica particles having an average particle diameter of 0.1 μm or less, a plasticizer or an ultraviolet absorber. 6. An acid dissociation index in an aqueous solution of 1.93 or more.
4. The cellulose acylate solution according to claim 3, which contains an acid which is 4.50, an alkali metal salt thereof or an alkaline earth metal salt thereof. 7. The sum of the degree of acyl substitution at the 2-position and 3-position is 1.
A mixture of a cellulose acylate and a solvent having a degree of acyl substitution at the 6-position of not less than 70 and not more than 1.90 and not less than 0.88 is cooled to a temperature of -80 to -10 ° C, or 80 to 220 ° C. A method for preparing a cellulose acylate solution, comprising dissolving cellulose acylate in a solvent by heating the solution to a temperature. 8. The sum of the degree of acyl substitution at the 2-position and 3-position is 1.
A cellulose acylate film comprising a cellulose acylate having a degree of acyl substitution at the 6-position of 70 or more and 1.90 or less and 0.88 or more. 9. The cellulose acylate film according to claim 8, wherein the cellulose ester film has a multilayer structure of two or more layers, and the thickness of the outer layer on at least one side of the cellulose ester film is 1 to 50 μm. 10. A cellulose acylate having a total degree of acyl substitution at the 2- and 3-positions of 1.70 or more and 1.90 or less and a degree of acyl substitution at the 6-position of 0.88 or more dissolved in a solvent. A method for producing a cellulose acylate film, comprising casting the cellulose acylate solution on a support to form a cellulose acylate film. 11. The method for producing a cellulose acylate film according to claim 10, wherein two or more layers are cast by a co-casting method.