JP2002187149A - Method for manufacturing cellulose acrylate film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To manufacture a high-quality plane cellulose acrylate film without using a chlorine organic solvent like a methylene chloride. SOLUTION: The cellulose acrylate film is manufactured by casting a cellulose acrylate solution of a cellulose acrylate dissolved in a non-chlorine mixed solution containing keytone with a solubility parameter of 19 to 21 and an ester with a solubility parameter of 19 to 21 in more than one layer by a cocasting process.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[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, but practically used organic solvents have been substantially limited to methylene chloride.

However, in recent years, the use of chlorinated solvents such as methylene chloride has been significantly restricted from the viewpoint of protecting the global environment. In addition, since methylene chloride has a low boiling point (41 ° C.), it is easy to volatilize in the production process. For this reason, it is also a problem in the working environment. In order to prevent these problems, the manufacturing process is closed, but there is a technical limit even if it is hermetically closed. Therefore, there is an urgent need to search for a solvent for cellulose acylate that can substitute for methylene chloride.

Incidentally, acetone (boiling point: 56 ° C.), which is a general-purpose organic solvent, has a relatively low boiling point, and the drying load is not so large. Also, there are fewer problems with respect to the human body and the global environment as compared with chlorine-based organic solvents. However, acetone has low solubility in cellulose acylate. Acetone shows some solubility in cellulose acetate having a degree of substitution of 2.70 (degree of acetylation: 58.8%) or less. When the degree of substitution of cellulose acylate exceeds 2.70, the solubility of acetone is further reduced. 1. Substitution degree
When the cellulose acylate is 80 (acetylation degree: 60.1%) or more, acetone only shows a swelling action and does not show solubility.

[0007] 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.

Meanwhile, the cellulose acylate film is produced by a casting method in which the cellulose acylate solution (dope) is cast on a support and the film is peeled from the support. However, it has been clarified that the production of a cellulose acylate film using a non-chlorine solvent is disadvantageous in terms of production. That is, unlike the currently used chlorine-based solvent methylene chloride, it has been clarified that the dope has a structural viscosity in a non-chlorine-based solvent capable of dissolving cellulose acylate. If the dope has a structural viscosity, it is difficult for the surface to be smooth during drying, and the surface condition is deteriorated. Therefore, a measure for obtaining a good surface condition was required.

[0009]

SUMMARY OF THE INVENTION An object of the present invention is to prepare a cellulose acylate solution having excellent stability over time without using a chlorine-based organic solvent such as methylene chloride. Is to manufacture. Another object of the present invention is to produce a cellulose acylate film having excellent planarity without using a chlorine-based organic solvent such as methylene chloride.

[0010]

The object of the present invention has been attained by the following production methods (1) to (12). (1) Two layers of cellulose acylate are prepared by co-casting from a cellulose acylate solution dissolved in a non-chlorinated mixed solvent containing a ketone having a solubility parameter of 19 to 21 and an ester having a solubility parameter of 19 to 21. A method for producing a cellulose acylate film, comprising casting the above film.

(2) The method for producing a cellulose acylate film according to (1), wherein the non-chlorine mixed solvent further contains 2 to 30% by mass of an alcohol. (3) The ketone is selected from the group consisting of acetone, methyl ethyl ketone, cyclopentanone and cyclohexanone, the ester is selected from the group consisting of methyl formate, ethyl formate and methyl acetate, and the alcohol is a compound having 6 or less carbon atoms. The method for producing a cellulose acylate film according to (2), which is an alcohol.

(4) The method for producing a cellulose acylate film according to (1), wherein the non-chlorine mixed solvent comprises only a solvent selected from the group consisting of ketones, esters and alcohols. (5) The method for producing a cellulose acylate film according to (1), wherein the cellulose acylate is dissolved in a non-chlorinated mixed solvent at a temperature of -80 to -10 ° C or 80 to 220 ° C.

(6) In a structure of two or more layers of a cellulose acylate film formed by a co-casting method, the outermost layer on at least one side is cast so as to have a thickness of 1 to 50 μm ( The method for producing a cellulose acylate film according to 1). (7) The structure described in (6), wherein three or more layers are formed on the cellulose acylate film by a co-casting method, and the thickness of the outermost layer on at least one side is in the range of 1 to 50 μm. A method for producing a cellulose acylate film. (8) The thickness of the outermost layer on at least one side is 1 to 20 μm
m. The method for producing a cellulose ester film according to (6), wherein m is in the range of m.

(9) A solution in which three or more layers are formed on a cellulose acylate film by co-casting, and the solution forming the outermost layer has the same or lower concentration than the solution forming the inner layer. (1) The method for producing a cellulose acylate film according to (1). (10) The cellulose acylate solution forming the outermost layer has a concentration of 0.99 to 0.80 times the concentration of the cellulose acylate solution forming the inner layer. A method for producing a cellulose acylate film.

(11) The method for producing a cellulose acylate film according to (1), wherein each layer is simultaneously cast. (12) The method for producing a cellulose acylate film according to (1), wherein a silica particle, a plasticizer, or an ultraviolet absorber is added to the solution to be cast.

[0016]

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. Cellulose acylate is commercially available from Daicel Chemical Industries, Ltd., Coatles, Hoechst and Eastman Kodak. Photographic grade cellulose acylate is preferred. The water content of the cellulose acylate is preferably 2% by mass or less.

A cellulose acylate film is produced 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 a mixed solvent of a ketone and an ester. The solubility parameters for ketones and esters are 19-21. Esters and ketones may have a cyclic structure. A compound having a functional group other than the functional groups of ester and ketone (ester bond and carbonyl group) may be used.

Examples of esters include ethyl formate (19.
2), propyl formate (18.4), n-pentyl formate (18.1), methyl acetate (19.6), ethyl acetate (18.2) and n-pentyl acetate (17.6). The numbers in parentheses are the solubility parameters. Methyl formate, ethyl formate and methyl acetate are preferred. Examples of ketones include acetone (20.3), methyl ethyl ketone (19.0), diethyl ketone (18.
2), diisobutyl ketone (18.0), cyclopentanone (20.9), cyclohexanone (20.3) and methylcyclohexanone (20.1). The numbers in parentheses are the solubility parameters. Acetone, cyclopentanone and cyclohexanone are preferred.

The solubility parameter is an amount defined by (ΔH / V) ^1/2 where ΔH is the molar evaporation heat of the liquid and V is the molar volume. The solubility increases as the difference between the two solubility parameters decreases. For the solubility parameter, see various literatures (eg, J. Brandrup, EH et al., Polymer).
Handbook (fourth edition), VII / 671 to VII / 714).

The mixed solvent of the ester and the ketone is non-chlorine. Technically, a chlorinated solvent such as methylene chloride can be used without any problem, but it is preferable that a chlorinated solvent is not substantially used from the viewpoint of the global environment and working environment. "Non-chlorine solvent" means that the proportion of the chlorine solvent in the organic solvent is less than 10% by mass (preferably less than 5% by mass). Further, it is preferable that no chlorine-based solvent such as methylene chloride is detected from the produced cellulose acylate film. The mixed solvent may further include an alcohol. Examples of alcohols include methanol, ethanol, 1-propanol, 2-
Includes propanol, 1-butanol, 2-butanol and cyclohexanol, 2-fluoroethanol and 2,2,2-trifluoroethanol. Methanol, ethanol, 1-propanol, 2-propanol and 1-butanol are preferred. The proportion of the ester in the mixed solvent is preferably from 40 to 95% by mass of the total solvent, more preferably from 50 to 80% by mass. Ketone is preferably 5 to 50% by mass of the total solvent, more preferably 10 to 40% by mass. The total amount of ketones and esters is preferably at least 70% by mass of the total solvent. The alcohol is preferably contained in an amount of 2 to 30% by mass of the total solvent.

Examples of solvent combinations include methyl acetate /
Cyclopentanone / acetone / methanol / ethanol (60/15/15/5/5, parts by mass), methyl acetate /
Acetone / methanol / ethanol (75/15/5 /
5, mass parts), methyl acetate / cyclohexanone / methanol / 1-butanol (70/20/5/5, mass parts), methyl formate / methyl ethyl ketone / acetone / methanol / ethanol (50/20/20/5/5, Parts by mass). Methyl acetate / acetone / methanol / ethanol (75/15/5/5, parts by mass) and methyl acetate / cyclopentanone / methanol / ethanol (80/10/5/5, parts by mass) are preferred.

In the preparation of a cellulose acylate solution, the solvent is first swelled by adding the cellulose acylate while stirring the solvent in the tank at room temperature. The swelling time must be at least 10 minutes or more, and if it is less than 10 minutes, insoluble matter remains. Further, the temperature of the solvent is preferably 0 to 40 ° C. in order to sufficiently swell the cellulose acylate. 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. When a plurality of solvents are used, the order of addition is not particularly limited. For example, after the cellulose acylate is added to the solvent, another solvent (for example, a gelling solvent such as alcohol) may be added, or after the gelling solvent is wetted in advance by the cellulose acylate. A solvent may be added, which is effective in preventing heterogeneous dissolution. It is preferable to adjust the amount of cellulose acylate so that the mixture contains 10 to 40% by mass. 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 heated to -100 to -10C, more preferably to -80 to -1.
It is cooled to 0 ° C, more preferably to -50 to -20 ° C, most preferably to -50 to -30 ° C. Cooling, for example,
It can be carried out in a dry ice / 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. 0 after cooling
When heated to 200 ° C. (preferably 0 ° C. to 150 ° C., more preferably 0 ° C. to 120 ° C., and most preferably 0 ° C. to 50 ° C.), a solution in which cellulose acylate flows in an organic solvent is obtained. The temperature can be raised by simply leaving it at room temperature,
It may be heated in a warm bath. Further, if the pressure is increased during cooling using a pressure-resistant container and the pressure is reduced during heating, the dissolution time can be shortened. These cooling and heating operations may be repeated two or more times.

In the high-temperature melting method, the temperature around room temperature (−10 to
At 40 ° C.), the cellulose acylate is gradually added to the organic solvent with stirring. When a plurality of solvents are used, the order of addition is not particularly limited. For example, after the cellulose acylate is added to the solvent, another solvent (for example, a gelling solvent such as alcohol) may be added, or after the gelling solvent is wetted in advance by the cellulose acylate. A solvent may be added, which is effective in preventing heterogeneous dissolution. The cellulose acylate solution of the present invention is preferably added with cellulose acylate in a mixed organic solvent containing various solvents and swelled in advance. In that case, -10
In any solvent at 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 to obtain a uniform swelling liquid. Alternatively, after swelling with two or more solvents, the remaining solvent may be added. The dissolution concentration of cellulose acylate is 5% by mass to 30% by mass.
Is preferable, more preferably 15% by mass to 30% by mass,
More preferably, it is 17% by mass to 25% by mass. Next, the cellulose acylate and the solvent mixture are heated at 70 to 240 ° C. under a pressure of 0.2 Mpa to 30 Mpa in a pressure vessel.
More preferably 80 to 220 ° C, further preferably 100
~ 200 ° C, most preferably 100-190 ° 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.
These heating and cooling operations may be repeated two or more times.

The cellulose acylate may be dissolved at a low concentration at which it is easily dissolved, and then concentrated. When preparing the cellulose acylate solution of the present invention, it is preferable that the container is filled with an inert gas such as nitrogen gas to cope with explosion proof. The viscosity immediately before film formation of the cellulose acylate solution is
It may be in a range that can be cast at the time of film formation, and is usually 10 Pa
· S to 2000 Pa · s, preferably 30 Pa · s to 400 Pa · s.
The temperature at this time is not particularly limited as long as it is the temperature at the time of casting, but is preferably -5 to 70C, more preferably -5 to 55C. The concentration of the cellulose acylate in the solution is preferably 5 to 40% by mass, more preferably 10 to 40% by mass.
-30% by mass is preferred.

Various additives can be added to the cellulose acylate solution in each preparation step according to the use. 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), acetyltriethyl citrate. As plasticizers for reducing optical anisotropy, (di) pentaerythritol esters (described in JP-A-11-124445) and glycerol esters (described in JP-A-11-246)
704), diglycerol esters (described in JP-A-2000-63560), citrates (described in JP-A-11-92574), and substituted phenyl phosphates (described in JP-A-11-90946). Description) may be used. Two or more plasticizers may be used in combination. The added amount of the plasticizer is preferably 5 to 30% by mass, more preferably 8 to 16% by mass, based on the cellulose acylate.

As for the anti-deterioration agent and the anti-ultraviolet ray, 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
No. 56, No. 7-11055, No. 7-11056,
Nos. 8-29619 and 8-239509, JP-A-20
It is described in each publication of 00-204173. Examples of the deterioration inhibitor include butylated hydroxytoluene (BH
T). The UV absorber has a wavelength of 37
Excellent absorption of ultraviolet light of 0 nm or less and wavelength of 400 n
Those having little absorption of visible light of m or more are preferable. Examples of the ultraviolet absorber include oxybenzophenone-based compounds, benzotriazole-based compounds, salicylate-based compounds, benzophenone-based compounds, cyanoacrylate-based compounds, and nickel complex-based compounds. Benzotriazole compounds and benzophenone compounds are particularly preferred. The amount of the ultraviolet absorber to be added is preferably from 1 ppm to 10,000 ppm, more preferably from 10 to 1000 ppm by mass ratio to the cellulose acylate. The in-plane retardation (Re) of the film is 0 to 300 nm
Is preferable. The retardation (Rth) in the thickness direction of the film is 0 nm to 600 per 100 μm in thickness.
nm, more preferably 0 nm to 400 nm, and most preferably 0 nm to 250 nm.

Before the casting of the cellulose acylate solution, a release agent can be added. As the release agent, an acid, an alkali metal salt or an alkaline earth metal salt thereof can be used. Acid dissociation index (pKa) 1.93-4.50
It is preferred that Examples of inorganic acids include HClO
₂ (2.31), HOCN (3.48), molybdic acid (H ₂ MoO ₄ , 3.62), HNO ₂ (3.15),
Phosphoric acid (H ₃ PO ₄ , 2.15), triphosphoric acid (H ₅ P
_{2. 3} O ₁₀ , 2.0) and vanadic acid (H ₃ VO ₄ , 3.
78) is 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. Examples of carboxylic acids include aliphatic monocarboxylic acids, aliphatic polycarboxylic acids, oxycarboxylic acids, aldehyde acids, ketone acids, aromatic monocarboxylic acids, aromatic polycarboxylic acids, heterocyclic monocarboxylic acids, and heterocyclic rings. Formula 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 aromatic monocarboxylic acids 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.

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.

As the acid, other than carboxylic acid, sulfonic acid,
Use of a phosphoric acid-based material can be expected to improve peelability. These are preferably in the form of a surfactant from the viewpoint of solubility. Specifically, JP-A-61-2438
The material described in JP-A No. 37 can be suitably used. Examples of _{surfactants, 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} - include _{(CH 2) 4 SO 3 Na} .

The organic acid which functions as a stripping agent is an aliphatic monocarboxylic acid having 1 to 3 carbon atoms (eg, formic acid, chloroacetic acid, halopropionic acid, acrylic acid), or an aliphatic acid having 2 to 4 carbon atoms. Group polycarboxylic acids (eg, malonic acid,
Preferred are succinic acid, glutaric acid, fumaric acid, oxycarboxylic acids having 1 to 6 carbon atoms (eg, glycolic acid, lactic acid, malic acid, tartaric acid, citric acid) and amino acids (including derivatives thereof). Sulfonic or phosphoric acid surfactants (described in JP-A-61-243837)
Are also preferred release agents. Preferred materials are preferred.

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.

Fine particles can be added to prevent creaking of the film. Inorganic fine particles are preferred. Examples of the inorganic substance constituting the fine particles include silica, kaolin, talc, diatomaceous earth, quartz, calcium carbonate, barium sulfate, titanium oxide, alumina, manganese colloid, titanium dioxide, strontium barium sulfate, and silicon dioxide. The inorganic fine particles may be formed from an alkaline earth metal salt (eg, calcium or magnesium). The average height of the protrusions on the film surface containing the fine particles is preferably 0.005 to 10 μm,
More preferably, it is 0.01 to 5 μm. The protrusions can be formed with a spherical or amorphous matting agent. The content of the fine particles is preferably 0.5~600mg / m ^2, further preferably 1 to 400 mg / m ^2.

Before the casting, the solution is subjected to a suitable filter medium (eg, wire mesh,
Foreign matter (undissolved matter, trash, impurities) using paper, flannel)
Is preferably removed. Absolute filtration accuracy is 0.05 to 100 μm for filtration of cellulose acylate solution
It is preferable to use a filter of More preferably, the absolute filtration accuracy is 0.5 to 10 μm. preferable. The filtration pressure is preferably 16 kg / cm ² or less, more preferably 12 kg / cm ² or less, still more preferably 10 kg / cm ² or less, and most preferably ² kg / cm ² or less.

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. Both ends of the obtained web are sandwiched by clips, transported by a tenter while maintaining the width, and dried. Subsequently, the web is transported 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 light-sensitive material or a functional protective film for an electronic display, in addition to a solution casting film forming apparatus, an undercoat layer, an antistatic layer, an antihalation layer, and a protective layer. A coating device is often added for surface processing on the support.

The obtained cellulose acylate solution is co-cast with two or more layers of a plurality of cellulose acylate solutions on a smooth band or drum as a support. For example, when casting a plurality of cellulose acylate solutions,
Films can be produced while casting and laminating solutions containing cellulose acylate from a plurality of casting ports provided at intervals in the direction of travel of the support, respectively (described in JP-A-11-198285). . Further, a method of casting a film by casting a cellulose acylate solution from two casting ports (described in JP-A-6-134933) may 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-viscosity, low-viscosity cellulose acylate solution (see JP-A-56-162617). ) Can also be adopted. By performing co-casting, smoothing in drying of the surface proceeds, so that significant improvement of the surface state can be expected. In the case of co-casting, the thickness of each layer is not particularly limited, but preferably the outermost layer is preferably thinner than the inner layer. At this time, the thickness of the outermost layer is preferably from 1 to 50 μm, particularly preferably from 1 to 20 μm. Here, the outermost layer means a layer which is not a 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 indicates a band surface (drum surface) in the case of two layers, and a layer located inside the outermost layer in the case of three or more layers. The viscosity of the cellulose acylate solution is preferably the same or lower for the solution for the outermost layer than for the inner layer. Regarding the concentration of the cellulose acylate solution, the concentration for the outer layer is preferably the same or lower than the concentration for the inner layer, more preferably 0.99 to 0.80 times. The cellulose acylate solution can be cast simultaneously with the coating liquid of another functional layer (eg, an adhesive layer, a dye layer, an antistatic layer, an antihalation layer, a UV absorbing layer, a polarizing layer).

The drying temperature in the step of drying the dope on the support is preferably from 30 to 250 ° C.
The temperature is more preferably 0 to 180 ° C. The drying temperature is described in JP-B-5-17844.
A method of positively stretching in the width direction (JP-A-62-1150)
No. 35, JP-A-4-152125, JP-A-4-28421
1, No. 4-298310, and No. 11-48271). The stretching of the film is uniaxial stretching or biaxial stretching. The stretching ratio of the film (the ratio of the increase by stretching to the original length) is 10 to 3
It is preferably 0%.

The finished (after drying) cellulose acylate film preferably has a thickness of 5 to 500 μm, more preferably 20 to 250 μm, and more preferably 30 to 250 μm.
The range of 180 μm is most preferred. For optical applications, 30
A thickness of １１０110 μm is particularly preferred. The film thickness is
It can be adjusted by adjusting the concentration of the solid content contained in the dope, the slit gap of the die cap, the extrusion pressure from the die, and the speed of the support.

By subjecting the cellulose acylate film to a surface treatment, the adhesion between the cellulose acylate film and each functional layer (for example, an undercoat layer and a back layer) can be improved. The surface treatment includes glow discharge treatment, ultraviolet irradiation treatment, corona treatment, flame treatment, acid or alkali treatment. Alkali (saponification) treatment is preferred. In the alkali (saponification) treatment, the film surface is preferably immersed in an alkaline solution, neutralized with an acidic solution, washed with water, and dried. Examples of the alkaline solution include a potassium hydroxide solution and a sodium hydroxide solution, and the specified concentration of hydroxide ions is preferably 0.1 N to 3.0 N, and more preferably 0.5 N to
2.0N is more preferred. 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 and the like, and the concentration thereof is preferably 0.01 N to 3.0 N, and more preferably 0.05 N.
~ 2.0N is more preferred. 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 constitution 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.

[0049]

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.

(0) 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 a predetermined amount of a 1N aqueous solution of sodium hydroxide is added thereto.
For 2 hours. 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)), and it was separately confirmed that the value was correct. Further, the degree of acetylation and the amount of the other acyl groups obtained in this manner were converted into the degree of substitution in consideration of the molar molecular weight.

(1) 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

(2) Stability of Solution 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.

(3) 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.

(7) 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 dissolving methods. Table 1 shows the detailed solvent composition of each of the present invention and Comparative Examples. In addition, silica particles (particle diameter 20n)
m), 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 at 0.5% by mass, 10% by mass and 1.0% by mass of cellulose acylate, respectively. 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 ("High temperature" is shown in Table 1)
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 (1 Mpa) steam through the outer jacket of the vessel, and kept at the temperature shown in Table 1 for 5 minutes. Thereafter, 50 ° C. water was passed through the outer jacket and cooled to −50 ° C. at −8 ° C./min to obtain a dope.

(1-2) Filtration of Cellulose Acylate Solution The obtained dope was treated at 50 ° C. with an absolute filtration accuracy of 0.01 m.
m filter paper (manufactured by Toyo Roshi Kaisha Co., Ltd., # 63), and a filter paper having an absolute filtration accuracy of 0.0025 mm (manufactured by Pall Corporation,
FH025).

(1-3) Formation of Cellulose Acylate Film The solution of (1-2) is cast on a casting machine (JP-A-56-162617).
No. 30) in an environment of 120 ° C.
After drying for a minute, the solvent was evaporated to obtain a cellulose acylate film. Table 1 shows details of the layer structure. Two layers have a structure of an inner layer / outer layer from the band surface, and three layers have a sandwich type structure of an outer layer / inner layer / outer layer.

[0060]

[Table 1]

(1-4) Result The obtained cellulose acylate solution and film were evaluated in accordance with 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 step of the film forming step. 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.

[0063]

[Table 2]

[0064]

According to the present invention, there is provided a method for producing a cellulose acylate film, comprising simultaneously casting two or more layers by co-casting, wherein the cellulose acylate solution is substantially non-chlorinated. A non-chlorinated solvent comprising a mixed solvent of at least a ketone having a solubility parameter of 19 to 21 and a solubility parameter of 19 to 21 esters. And a method for producing a cellulose acylate film having no problem in mechanical properties and the like.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G02B 5/30 G02B 5/30 // B29K 1:00 B29K 1:00 B29L 9:00 B29L 9: 00F Term (reference) 2H049 BA02 BA06 BB13 BB33 BB49 BB67 BC09 BC22 4F071 AA09 AA81 AB26 AC15 AC19 AE04 AE05 AE17 AF30 AH12 BA02 BB02 BC01 4F205 AA01 AB07 AB11 AB14 AC05 AG03 GA07 GB02 GB26 GC02 GC07 GE22 EB01 4G01 EG01 GF01 FD027 FD057 GP00

Claims (12)

[Claims] 1. A cellulose acylate is prepared by co-casting from a cellulose acylate solution dissolved in a non-chlorinated mixed solvent containing a ketone having a solubility parameter of 19 to 21 and an ester having a solubility parameter of 19 to 21. A method for producing a cellulose acylate film, comprising casting two or more layers to form a film. 2. The non-chlorine mixed solvent further comprises 2 to 30.
The method for producing a cellulose acylate film according to claim 1, wherein the cellulose acylate film contains alcohol by mass. 3. The ketone is selected from the group consisting of acetone, methyl ethyl ketone, cyclopentanone and cyclohexanone; the ester is selected from the group consisting of methyl formate, ethyl formate and methyl acetate; The method for producing a cellulose acylate film according to claim 2, wherein the alcohol is the following alcohol. 4. The method for producing a cellulose acylate film according to claim 1, wherein the non-chlorine mixed solvent comprises only a solvent selected from the group consisting of ketones, esters and alcohols. 5. -80 to -10 ° C or 80 to 220 ° C
The method for producing a cellulose acylate film according to claim 1, wherein the cellulose acylate is dissolved in the non-chlorine-based mixed solvent at a temperature of (1). 6. A structure comprising two or more layers of a cellulose acylate film formed by a co-casting method, wherein the outermost layer on at least one side has a thickness of 1 to 50 μm. 2. The method for producing a cellulose acylate film according to item 1. 7. A cellulose acylate film having a three or more layer structure formed by co-casting, wherein the outermost layer on at least one side has a thickness of 1 to 50 μm. 3. The method for producing a cellulose acylate film according to item 1. 8. The outermost layer on at least one side has a thickness of 1
The method for producing a cellulose ester film according to claim 6, wherein the thickness is in the range of 20 to 20 µm. 9. A solution in which three or more layers are formed on a cellulose acylate film by a co-casting method, and the solution forming the outermost layer has the same concentration or a lower concentration as the solution forming the inner layer. A method for producing a cellulose acylate film according to claim 1. 10. The method according to claim 9, wherein the cellulose acylate solution forming the outermost layer has a concentration of 0.99 to 0.80 times the concentration of the cellulose acylate solution forming the inner layer. A method for producing the cellulose acylate film as described above. 11. The method for producing a cellulose acylate film according to claim 1, wherein each layer is simultaneously cast. 12. The method for producing a cellulose acylate film according to claim 1, wherein a silica particle, a plasticizer, or an ultraviolet absorber is added to the solution to be cast.