JP2001200097A - Cellulose mixed acylate, method for preparing cellulose mixed acylate dope, method for manufacturing cellulose mixed acylate film, and cellulose mixed acylaet film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a cellulose mixed acylate excellent in solubility and easily peelable from a casted support, a cellulose mixed acylate having a small retardation and a wide angle of visual field and suitable for a liquid crystal image display unit, and a cellulose mixed acylate film not easily broken. SOLUTION: The cellulose mixed acylate has acetyl group and propionyl group and/or butylyl group as a substituent, and has the propionyl group and/or the butylyl group at Y6, and has an average substitution satisfying the following equations: 3.00>=(total average substitution)>=2.45, and 0.95>=(average substitution at Y6)>=0.10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for preparing a cellulose-mixed acylate, a cellulose-mixed acylate dope, a method for producing a cellulose-mixed acylate film, and a cellulose-mixed acylate useful for a silver halide photosensitive material and a liquid crystal image display device. About the film.

[0002]

2. Description of the Related Art A solution casting method of a cellulose triacetate film, which is usually used, is schematically described with reference to FIG. FIG. 1 is a schematic drawing of a solution casting film forming apparatus. A solution of cellulose triacetate (called a dope) is cast from a die 2 onto a casting support 3 as a dope film, and the solvent in the dope is evaporated to obtain a web 1 (a dried dope film is called a web). The web 1 is peeled from the casting support 3 by the peeling roll 4 when the web 1 becomes peelable. At this point, the solvent in the web
About 100% remains and needs further drying. The web 1 peeled from the casting support 3 is conveyed by a plurality of rolls 6 and the drying apparatus 5 is used to remove 2% of the solvent.
It is dried to the following cellulose triacetate film. 7 is a drying wind.

[0003] Cellulose triacetate films have been used for supports of silver halide photographic materials and protective films of liquid crystal image display devices because of their excellent properties such as toughness, water resistance and optical isotropy. It is predicted that the demand for cellulose triacetate film itself will further increase in the future due to the recent increase in the number of photographing shots, diversification of liquid crystal display screens, and rapid spread.

Generally, as described above, a cellulose triacetate film is produced by a solution casting method in which a dope in which cellulose triacetate is dissolved using methylene chloride as a main solvent. However, in recent years, chlorine-based organic solvents such as methylene chloride have been regulated in consideration of environmental issues. Under such circumstances, it has been considered to further increase the concentration of the dope and use a non-chlorine organic solvent. For example, when dissolving cellulose triacetate using a non-halogen-based organic solvent, it cannot be dissolved at around normal pressure and room temperature, and is cooled by a cooling dissolution method of cooling to zero or less, and also in a high pressure state described below. There is a method of preparing a dope by a high-pressure melting method in which the dope is dissolved. It was something.

On the other hand, in recent years, the development of computers and information communication and the use of display devices have been rapidly expanding, and various problems have emerged. For example, in a VA-type liquid crystal image display device (to be described later), when the cellulose triacetate film used for the device becomes thicker than a certain thickness, the cellulose triacetate film is liable to be broken or lacks flexibility and is difficult to process. It came out.

[0006] Liquid crystal image display devices are widely used in word processors, personal computers, and the like because they can be directly connected to IC circuits with low voltage and low power consumption and can be made particularly thin. . The basic configuration of such a liquid crystal image display device is such that, for example, polarizing plates are provided on both sides of a liquid crystal cell. In such a liquid crystal image display device, from the viewpoint of contrast, a liquid crystal image display device using a twisted nematic (TN) liquid crystal having a twist angle of 90 ° uses a super twisted nematic (STN) liquid crystal having a twist angle of 160 ° or more. The liquid crystal image display device used is changing.

However, the liquid crystal image display device using the STN utilizes the birefringence of the liquid crystal.
There is a problem that a normal white in a liquid crystal image display device using a blue color or a white background is colored in blue or yellow. There is a problem that there is a difficult task.

As a means for solving these problems, there has been proposed a technique of using a retardation plate below an upper polarizing plate to compensate for birefringence. According to this technology,
Although the problem of coloring is solved, the viewing angle has hardly been improved. Furthermore, in order to solve this problem, a technique has been proposed in which a birefringent film having a refractive index in the thickness direction larger than a refractive index in a direction perpendicular to the birefringent optical axis is used and used as a retardation plate. Was.

By the way, in view of low voltage, low power consumption, and thinness, a liquid crystal image display device has great features not found in other display devices. However, the biggest problem in the liquid crystal image display device is that the viewing angle is narrow. Therefore, the demand for the improvement regarding the viewing angle is increasing. One technology for this is TN or STN
A different type of liquid crystal, for example, a vertical alignment type liquid crystal has been proposed. The liquid crystal cell of the TN or STN type is a type in which liquid crystal molecules are parallel to the alignment plate when the voltage is turned off, and the liquid crystal molecules are aligned perpendicular to the alignment plate when the voltage is turned on. When the voltage is turned off, the liquid crystal molecules are perpendicular to the alignment plate, and when the voltage is turned on, the liquid crystal molecules are parallel, and a negative type liquid crystal having a negative dielectric anisotropy is used. Since the vertical alignment (VA) type liquid crystal image display device has the above-described alignment mode, black is displayed firmly as black, the contrast is high, and the viewing angle is higher than that of the TN or STN type. It has the advantage of being relatively wide. However,
As the size of the liquid crystal screen increases, there is an increasing demand for a wider viewing angle.
Conventionally, since a cellulose triacetate film has been used, there is a limit in increasing the retardation value in the thickness direction. Then, in order to obtain a larger retardation value in the thickness direction, it was necessary to further increase the thickness of the film. However, portability of liquid crystal image display devices has recently been demanded, and miniaturization, particularly thinning of the liquid crystal image display device is also required. That is, a polarizing plate protective film having a small thickness and a large retardation value in the thickness direction is required.

Therefore, a film that replaces the cellulose triacetate film has been demanded.

First, a film material having transparency and excellent mechanical properties, and a film material which can be formed using a non-chlorine-based organic solvent. In order to further improve the solubility, cellulose triacetate is used. A method using a cellulose mixed acylate obtained by substituting a part of the acetyl group with another acyl group, for example, a propionyl group or a butyryl group has also been devised.

On the other hand, recently, there has been disclosed a technique for cellulose triacetate in which an acetyl group is introduced at a specific ratio at the position of a hydroxyl group of two glucose units in cellobiose units constituting cellulose. JP-A-9-28
No. 6801 discloses that the total average degree of substitution of acetyl groups at all substitution positions of cellulose triacetate is 2.60 or more, the total average degree of substitution at positions 2 and 3 is 1.97 or less, and the average degree of substitution at position 6 is Is the total average degree of substitution.
It is described that by setting the content to 0% or less, cellulose triacetate having excellent solubility and having a low solution viscosity when formed into a concentrated solution can be obtained. Further, Japanese Unexamined Patent Application Publication No. 11-5851
The publication discloses that the total degree of substitution of acetyl groups at the 2-, 3- and 6-positions of cellulose triacetate is 2.67 or more, and the degree of acetyl substitution at the 2- and 3-positions is 1.97 or less. It discloses that the film has a low retardation value in the thickness direction when formed into a film.

The two glucose units in the cellobiose unit constituting cellulose have three hydroxyl groups at the 2-, 3- and 6-positions respectively (general formula (I) below). Those obtained by substituting these hydroxyl groups with acyl groups are referred to as cellulose acylates. Those in which all acyl groups are acetyl groups are cellulose triacetates, and acetyl groups each having 2
The total average degree of substitution of the acetyl group of cellulose triacetate which is substituted at the 3-, 3-, and 6-positions and is used for a silver halide photographic light-sensitive material or a polarizing plate of a liquid crystal image display device is usually 2.6 to 3. 0 (the following general formula (I
I)). However, not all acetyl groups are equivalently substituted at these positions, and they differ slightly depending on the substitution positions.

[0014]

Embedded image

[0015]

Embedded image

Here, Acy is an acyl group and COC
H _3, a _{COC 2 H 5, COC 3 H} 7, numbers 1 to 6 indicate the positions of carbon atoms in the glucose unit.

A method for determining the substitution position of the hydroxyl group of glucose is described in Y. Tezuka & Y. Tsuchiya,
Carbhydrate Research, No. 273
Winding, are described in pp. 83-91 (1995), ¹³
A method for measuring the state of substitution of an acetyl group and a propionyl group or a butyryl group at the 2-, 3- and 6-positions using a C-NMR method is reported.

Further, Japanese Patent Application Laid-Open Nos.
Japanese Patent Application No. 0-45804 discloses a range of an acetyl group and an acyl group having 3 or more carbon atoms of a cellulose mixed fatty acid ester as an average degree of substitution without specifying a substitution position. The properties of the cellulose-mixed acylate films produced by the methods described therein for obtaining an acyl group having 3 or more carbon atoms (actually, a propionyl group or a butyryl group) having an average degree of substitution, JP-A-9-95544 and JP-A-9-95557 disclose that the properties of the dope dissolved by the method of cooling and dissolving the cellulose mixed acylate are as follows. Dope turbidity or gelation occurred, and it was difficult to stably store the dope for a long time.

[0019]

However, when a cellulose-mixed acylate film is produced by a solution casting method, there is a disadvantage that the releasability of the web from the stainless steel belt support is deteriorated. It is thought that the introduction of a propionyl group or a butyryl group having a larger number of carbon atoms than that of cellulose triacetate resulted in the adhesion of the stainless steel belt support of the web being too good. When the residual solvent of the web at the time is reduced, the film forming speed becomes slow and the productivity is lowered. In the case of a finished film, there is a problem that the elastic modulus is reduced.

The present invention has been made in view of the above, and a first object of the present invention is to provide a cellulose-mixed acylate having excellent solubility and easy to peel off from a casting support. A second object of the present invention is to provide a cellulose-mixed acylate which has a large retardation in the thickness direction even when thinned, and is suitable for a liquid crystal image display device. Furthermore,
A third object of the present invention is to provide a cellulose mixed acylate film which is hard to be broken and is easy to process.

[0021]

The present inventors have studied a cellulose mixed acylate in which the hydroxyl groups at the 2-, 3- and 6-positions of the glucose unit have been substituted with acetyl, propionyl and / or butyryl groups. Acetyl group and propionyl group and / or butyryl group.

As a result of these studies, the present inventors have found that the cellulose-mixed acylate has a large retardation in the thickness direction, and that the film thickness for obtaining the same viewing angle expanding effect as cellulose triacetate can be significantly reduced. Was found. Further, it was also found that the cellulose mixed acylate of the present invention has a very high folding resistance and is flexible, so that even if the thickness is increased, the workability is excellent and the productivity is not reduced.

The present invention has the following constitution. (1) A mixed cellulose acylate having an acetyl group, a propionyl group and / or a butyryl group as a substituent, wherein Y6 has at least a propionyl group and / or a butyryl group and has an average degree of substitution satisfying the following formula. Cellulose mixed acylate to be used.

3.00 ≧ (X2 + X3 + X6 + Y2 + Y
3 + Y6) ≧ 2.45 0.95 ≧ (X6 + Y6) ≧ 0.10 where X2 is the 2-position, X3 is the 3-position, and X6 is the average degree of substitution of the acetyl group substituted for each hydroxyl group at the 6-position. , Y2 is the 2-position, Y3 is the 3-position, and Y6 is the average degree of substitution of the propionyl and / or butyryl groups substituted for the respective hydroxyl groups at the 6-position, and (X6 + Y6) substituted the 6-position hydroxyl group. It is the average degree of substitution of an acyl group (acetyl group and propionyl group and / or butyryl group).

(2) The cellulose mixed acylate according to (1), wherein (X6 + Y6) has an average degree of substitution satisfying the following formula.

0.87 ≧ (X6 + Y6) ≧ 0.10 (3) A cellulose mixed acylate having an acetyl group, a propionyl group and / or a butyryl group as a substituent has an average degree of substitution satisfying the following formula. Cellulose mixed acylate to be used.

3.00 ≧ (X2 + X3 + X6 + Y2 + Y
3 + Y6) ≧ 2.45 0.95 ≧ (X6 + Y6) ≧ 0.10 0.34 ≧ Y6 ≧ 0.10 Here, X2 is a 2-position, X3 is a 3-position, and X6 is a 6-position hydroxyl group. , Y2 is the 2-position, Y3 is the 3-position, and Y6 is the average degree of substitution of the propionyl group and / or butyryl group at the 6-position, (X6 + Y6 ) Is the average degree of substitution of the acyl group (acetyl group and propionyl group and / or butyryl group) substituted for the hydroxyl group at the 6-position.

(4) The cellulose mixed acylate according to (3), wherein (X6 + Y6) has an average degree of substitution satisfying the following formula:

0.87 ≧ (X6 + Y6) ≧ 0.10 (5) The cellulose mixed acylate according to any one of (1) to (4) is at least one selected from methylene chloride, methyl acetate and fluoroalcohol. Is dissolved as a main solvent, thereby preparing a cellulose mixed acylate dope.

(6) The method for preparing a cellulose mixed acylate dope according to (5), wherein the dope contains 2 to 30% by mass of an alcohol having 4 or less carbon atoms.

(7) Using the cellulose mixed acylate dope prepared by the method described in (5) or (6),
A method for producing a cellulose-mixed acylate film, wherein the film is produced by a solution casting method.

(8) A cellulose-mixed acylate film produced by the method described in (7).

The present invention will be described in detail. In the cellulose mixed acylate of the present invention, an acetyl group, a propionyl group, and / or a butyryl group are represented by the following at the 2-, 3-, and 6-hydroxyl groups of the two glucose units of the cellobiose unit constituting cellulose. It has a substitution degree that satisfies the formula. Here, the average degree of substitution at the 2-, 3-, and 6-positions of the acetyl group is X2, X3, and X6, respectively.
The average degree of substitution at the 2-, 3-, and 6-positions of the propionyl group or butyryl group is defined as Y2, Y3, and Y6, respectively (the unsubstituted positions that are still hydroxyl groups are not shown).

3.00 ≧ (X2 + X3 + X6 + Y2 + Y
3 + Y6) ≧ 2.45 0.95 ≧ (X6 + Y6) ≧ 0.10 (provided that Y6 has at least a propionyl group and / or a butyryl group) or 3.00 ≧ (X2 + X3 + X6 + Y2 + Y3 + Y6) ≧
2.45 0.95 ≧ (X6 + Y6) ≧ 0.10 0.34 ≧ Y6 ≧ 0.10.

(X2 + X3 + X6 + Y2 + Y3 + Y6)
Represents the total average degree of substitution in which the acetyl group and the propionyl group and / or the butyryl group are completely or partially substituted at all positions of the hydroxyl group, and (X6 + Y6) represents that the hydroxyl group at the 6-position is a propionyl group and / or a butyryl group. Represents the average degree of substitution, wholly or partially substituted, and Y6
Is the average degree of substitution of the 6-position acyl group.

Each position of the glucose unit of the acyl group of the present invention
For the method of measuring the degree of substitution to the Tez
uka & Y. As described in Tsuchiya's dissertation
Is ¹³It can be performed by a C-NMR method. This way
With the use of¹³C-NMR signal and
The signal of the lopionyl group and the signal of the butyryl group are clear.
It is clearly separated, and the signals of the 2nd, 3rd and 6th positions are close
Divided into three adjacent peaks, each identified and the peak height
From this, the degree of substitution is known.

The method for producing the cellulose mixed acylate of the present invention, for example, cellulose acetate propionate,
Pyridine and 4-
Under a catalyst such as (N, N-dimethylamino) pyridine,
A method obtained by reacting propionic anhydride, a method of partially hydrolyzing cellulose triacetate with sulfuric acid, a method obtained by the above method, a method of reacting cellulose with propionic anhydride using acetic acid or propionic acid and sulfuric acid as a catalyst. First, a method capable of producing cellulose propionate and then performing acetylation with acetic anhydride (in this case, controlling the amount of sulfuric acid catalyst, the reaction temperature and the reaction time so that the position can be specified), acetic anhydride and A method in which propionyl anhydride or butyric anhydride is obtained by changing the amount of a sulfuric acid catalyst, the reaction temperature, the amount of a neutralizing agent such as magnesium acetate added, or the like.
(N, N-dimethylamino) pyridine was added, acetylation was performed with acetic anhydride, detritylation was performed in an acetic acid solution of hydrobromic acid, and subsequently, 4- (N, N-dimethylamino) pyridine catalyst propionyl Examples of the method include a method that can be used, and any production method that can achieve the object of the present invention can be used without limitation. Also,
Cellulose acetate butyrate and cellulose acetate propionate butyrate can be produced in a similar manner.

The present inventors have found that the degree of substitution at the 6-position is significantly related to the solubility and the stagnant stability of the dope. The present inventors believe that the solubility and the stagnant stability of the dope are determined by the balance between the cohesive strength of the cellulose mixed acylate and the magnitude of the interaction between the solvent and the solute (in this case, the cellulose mixed acylate). In the cellulose mixed acylate of the present invention, a propionyl group at the 6-position and / or
Alternatively, it is particularly important to control the average degree of substitution of the butyryl group (Y6) and the average degree of substitution of the acyl group at the 6-position (X6 + Y6). The properties of the cellulose mixed acylate of the present invention are as follows.
+ Y6), but also the degree of the unsubstituted hydroxyl group at the 6-position,
Alternatively, it is affected by the degree of hydrolysis after acylation. 6
In the acylation reaction, the acyl group reacts faster than the other 2- or 3-position, and in the hydrolysis, the acyl group is easily eliminated earlier than the other position, and the acyl group at the 6-position reacts during the hydrolysis or in the hydrolysis. Make a specific reaction. In addition, the 6-position protrudes by one carbon from the pyranose ring forming the glucose unit, and its steric structure causes steric hindrance of the substituent, weakens the intermolecular hydrogen bond of the hydroxyl group, and reduces the cohesive force of the cellulose mixed acylate. And by introducing a group that is sterically bulkier than an acetyl group, such as a propionyl group or a butyryl group, at the 6-position, and by appropriately having a hydroxyl group at the position, The present inventors believe that the following unique properties may appear. On the other hand, in such a sense, cellulose triacetate has too strong aggregating power and dissolves in a good solvent such as methylene chloride even if an acetyl group is specifically arranged at the 6-position. The inventor believes that gelation is likely to occur if the dope is not dissolved in the system solvent by a usual method, and the dope dissolved by a special dissolution method such as the cooling dissolution method or the high-pressure dissolution method described below is kept stagnant. Is thinking.

The present invention is characterized in that another propionyl group and / or a butyryl group other than an acetyl group are present at the above-mentioned specific positions in the above-mentioned ratio, that is, the acyl group at the 6-position (X6 + Y6 ) Is from 0.10 to 0.95, preferably from 0.10 to 0.87.
In particular, a cellulose mixed acylate having an average degree of substitution (Y6) of a propionyl group and / or a butyryl group at the 6-position of 0.10 to 0.34 has solubility of the dope, releasability, and retardation in the thickness direction. Even a thin film is large, and the effect of significantly improving the folding resistance of the film is remarkable.

In the present invention, the average degree of substitution of the acetyl group, propionyl group and butyryl group at other positions is not specified in the present invention, but, for example, (Y2 + Y3 +
(Y6) / (X2 + X3 + X6) is preferably from 0.03 to 1.32, and more preferably from 0.20 to 0.40.

The viscosity average polymerization degree of the cellulose mixed acylate of the present invention is preferably 200 or more. More preferably 4
00 to 800.

A method for preparing a dope of the cellulose mixed acylate of the present invention will be described. The main organic solvent that can be used in the cellulose mixed acylate dope of the present invention is
It is a good solvent for cellulose mixed acylate, and examples thereof include methyl acetate, ethyl acetate, methyl formate, ethyl formate, 1,3-dioxolan, 1,4-dioxane, methyl acetoacetate, fluoroalcohol, and methylene chloride. I can do it. The above organic solvents may be used as a mixture of two or more kinds. In the present invention, among the above,
Preferred organic solvents include methyl acetate, fluoroalcohol and methylene chloride. However, as described above, methylene chloride, which is frequently used for dissolving cellulose triacetate, dissolves the cellulose mixed acylate of the present invention without any problem, as described above.However, the amount to be used should be as small as possible from the viewpoints of global environment protection and work environment safety. It is preferable to refrain. The fluoroalcohol may be any one which can be easily evaporated and dried in the film drying step. Such a fluoroalcohol has a boiling point of 165 ° C or lower, preferably 111 ° C or lower, more preferably 80 ° C or lower. . The fluoroalcohol has about 2 to 10 carbon atoms, preferably about 2 to 8 carbon atoms. Further, the fluoroalcohol is a fluorine atom-containing aliphatic alcohol and may or may not have a substituent. As the substituent, an aliphatic substituent with or without a fluorine atom, an aromatic substituent and the like are preferable. Examples of such a fluoroalcohol (hereinafter, the boiling point in the parenthesis is), 2-fluoroethanol (103 ° C), 2,2,2-trifluoroethanol (80 ° C), 2,2,3,3- Tetrafluoro-1-propanol (109 ° C.), 1,3-difluoro-2-propanol (55 ° C.), 1,1,1,3,3
3-hex-2-methyl-2-propanol (62
° C), 1,1,1,3,3,3-hexafluoro-2-
Propanol (59 ° C), 2,2,3,3,3-pentafluoro-1-propanol (80 ° C), 2,2,3
4,4,4-hexafluoro-1-butanol (114
° C), 2,2,3,3,4,4,4-heptafluoro-
1-butanol (97 ° C), perfluoro-t-butanol (45 ° C), 2,2,3,3,4,4,5,5-octafluoro-1-pentanol (142 ° C),
2,3,3,4,4-hexafluoro-1,5-pentanediol (111.5 ° C.), 3,3,4,4,5
5,6,6,7,7,8,8,8-tridecafluoro-
1-octanol (95 ° C), 2,2,3,3,4
4,5,5,6,6,7,7,8,8,8-pentadecafluoro-1-octanol (165 ° C), 1- (pentafluorophenyl) ethanol (82 ° C), 2,3
4,5,6-pentafluorobenzyl alcohol (11
5 ° C.). These fluoroalcohols may be used as a mixture of two or more.

A poor solvent or a solvent similar thereto may be added to the good solvent for the cellulose mixed acylate of the present invention. The poor solvent or a similar solvent may have 3 to 12 carbon atoms excluding the above solvent. Ethers, ketones having 3 to 12 carbon atoms, esters having 4 to 12 carbon atoms, alcohols having 1 to 8 carbon atoms, nitrohydrocarbons having 1 to 12 carbon atoms, or 5 to 5 carbon atoms
8 hydrocarbons can be used. For example, as ethers, tetrahydrofuran, diisopropyl ether, ethylene glycol monomethyl ether, ethylene glycol monoisopropyl ether, ethylene glycol dimethyl ether, ethylene glycol monobutyl ether, anisole, or phenetole,
Ketones, such as acetone, methyl ethyl ketone, methyl isobutyl ketone, or cyclohexanone; esters, such as propyl formate, butyl formate, propyl acetate, butyl acetate, or ethylene glycol diacetate; alcohols, such as methanol, ethanol, Propanol, isopropanol, n-butanol, s-butanol, t-butanol, 2-methyl-2
Nitro hydrocarbons such as butanol or cyclohexanol, such as nitromethane or nitroethane;
Examples of the hydrocarbons include cyclohexane, cyclopentane, cycloheptane and the like. Among these organic solvents, it is preferable to include a lower alcohol having 1 to 6 carbon atoms, and methanol, ethanol,
More preferred are n-propanol, i-propanol, s-propanol, n-butanol, i-butanol, s-butanol and t-butanol. Also, cyclohexane can be preferably used together with these alcohols. The content of the non-solvent or an equivalent organic solvent is 2 to 30% by mass based on the total amount of the organic solvent.
Is preferable, and 5 to 25 mass% is more preferable.

A cellulose mixed acylate dope (hereinafter sometimes simply referred to as a dope) using these poor solvents together with the main solvent is cast on a support, and then evaporation of the main solvent proceeds. By lowering the temperature of the support, the dope gels and the film-forming speed can be increased, and also the effect of improving the flatness of the resulting film is improved. It is preferable to use a mixture of solvents or similar solvents.

The method for preparing the cellulose mixed acylate dope of the present invention can be used without any limitation.
8. a method of dissolving the cellulose triacetate solution under the pressure of 1013 to 3040 Pa, which is used at a temperature around the boiling point of the main solvent, a method of cooling and dissolving the dope in a cooled state of a mixture of the solvent and the cellulose mixed acylate,
A high-pressure dissolution method of dissolving under a pressure of 8 × 10 ^{5 to} 4.9 × 10 ⁸ Pa can be used.

The usual dissolution method is to mix the cellulose mixed acylate in a mixed solvent of a good solvent and a poor solvent (the good solvent or the poor solvent may be mixed separately after mixing the cellulose mixed acylate). This is a method in which the pressure is changed in the vicinity of the boiling point of the main solvent according to the atmospheric pressure in a pressure-resistant closed container of 3040 Pa, and the mixture is dissolved with stirring. In this case, it is preferable to use at least one organic solvent selected from methylene chloride, methyl acetate and fluoroalcohol as the main solvent.

In the present invention, the dope can be prepared by a cooling dissolution method. The cooling dissolution method is
J. M. G. FIG. Cowie et al., Die Makromol
ekulare Chemie, Vol. 143, 105-1
Cellulose acetate (degree of acetylation: 60.1% to 61.3%) according to p.
After cooling to −70 ° C., 0.5 to
A method for obtaining a dilute solution in which 5% by mass is dissolved, and a paper by Kenji Ude et al., "Dry spinning of cellulose triacetate from acetone solution" (Journal of the Textile Society of Japan, vol.
To obtain a cellulose triacetate solution of 10 to 25% by mass according to JP-A-9-9
Nos. 5544, 9-95557 and 9-95538, and Japanese Patent Application Nos. 9-218567 and 10-11.
No. 0789 can be used. One example of the cooling and melting method in the present invention will be described. Total average substitution degree of acyl group ((Y2 + Y3 + Y6)
80% of / (X2 + X3 + X6 + Y2 + Y3 + Y6))
When the above is occupied by acetyl groups, by cooling dissolution method,
It is better to dissolve. First, a cellulose mixed acylate is gradually added to an organic solvent, for example, methyl acetate, or a mixed solvent of methyl acetate and a lower alcohol at room temperature while stirring. At this stage, the cellulose mixed acylate is almost dissolved, but depending on the degree of acetylation, it remains in a swollen state, or there is a mixed solution having a somewhat high haze, but by filtering, a clear dope can be obtained. . In the cooling dissolution method, the cellulose mixed acylate may be added to and mixed with the organic solvent in which the organic solvent has been cooled in advance, or may be cooled after being mixed, as long as the mixture is in a cooled state. The cooling temperature may be a temperature equal to or higher than the freezing point of the solvent used.
A temperature range of 0 ° C. is used. After cooling, the mixture is then brought to 0
When heated to a temperature of ５０50 ° C., a homogeneous solution with very high transparency is obtained. In addition, in order to enhance the effect of cooling and melting, the operation of cooling and heating may be repeated. Examples of the organic solvent that can be used in the cooling dissolution method include methyl formate, ethyl formate, methyl acetate, ethyl acetate, 1,3-dioxolan, 1,4-dioxane, and fluoroalcohol as main solvents. And fluoroalcohols are preferred. The fluoroalcohol is the same as described above. The main solvent refers to one having 50% by mass or more of the total organic solvent. Other organic solvents that may be mixed include methanol, ethanol, butanol, cyclohexane and the like in order to improve the film formation rate as described above.
To 30% by mass, preferably 10 to 25% by mass.

In the present invention, a dope can be prepared by a high-pressure dissolution method. The high-pressure melting method is described in Japanese Patent Application Nos. 9-178284 and 10-131999.
And Nos. 10-132000, which can be preferably used in the present invention.
The high-pressure dissolving method of cellulose mixed acylate can be usually dissolved by mixing with a solvent at room temperature. However, when the acetyl group accounts for 80% or more of the acyl substituents to be introduced, if the acetyl group is dissolved by the high-pressure method, more excellent physical properties can be obtained. A film can be obtained. It is considered that this method facilitates the penetration of the organic solvent into the solid or swollen cellulose mixed acylate under a pressurized state, and facilitates loosening and solvation of the molecules of the cellulose mixed acylate.

The high-pressure melting method according to the present invention comprises the steps of
Main solvent in the container (eg, methyl acetate)
The cellulose mixed acylate was added to the organic solvent, and 9.8 ×
10 ^Five~ 4.9 × 10⁸Pressurize Pa and return to normal pressure
The dope can be prepared by heating. High pressure melting vessel
9.8 × 1
0^Five~ 4.9 × 10⁸Even if the pressure is Pa
I just need. Pressurization pressure is 9.8 × 10^Five~ 4.9 × 10⁸Pa
But preferably 4.9 × 10⁶~ 2.9 ×
10⁸Pa, more preferably 9.8 × 10⁶~ 2.0 ×
10⁸Pa. Pressurizing method and pressurizing device
There is no particular limitation as long as the method is performed with a device that can
The method and the pressurizing device are the methods and equipment used in other industries.
Can be used, for example for molding ceramics
Cold Isostatic Pressing Method (Cold Isosatic P
Less, CIP for short, or rubber press method
Is included) and a method that can safely apply high pressure
And equipment. Pressurizing method by this hydrostatic pressure and
The device is used to mix cellulose acylate and organic solvent.
Hydrostatic pressure can be applied uniformly from all directions,
A cellulose-mixed acylate dope with excellent dissolution state was obtained.
This is preferred. Mixed in hydrostatic pressurization method
Easily deformed due to rubber or pressure in the material of the container enclosing the compound
A possible metal, for example, an aluminum container may be used.
Also, seal the mixture in a sealed container that is easily deformed, such as rubber.
To move and transfer in a closed container while applying hydrostatic pressure
According to the method, an intermittent preparation method can be adopted.
Also mixed in a container with a lid that can slide up and down
Hand to put the material and compress the mixture by pushing in the lid
Steps can also be taken. Also, using a pressurized extruder,
The mixture may be kneaded and extruded. Cellulose of the present invention
Intermittent pressurization during preparation of mixed acylate dope
The dissolution rate can be increased by repeatedly applying pressure and normal pressure.
You can increase it. The pressurizing device is equipped with a stirrer
It may or may not be present. This high-pressure melting method uses high pressure
Dissolution time can be shortened as much as possible, but if it is too high the equipment
Becomes large, and the effect of shortening the dissolution time is diminished.
9.8 × 10⁷~ 2.9 × 10⁸Pa is enough effect
Is obtained. Organic used in the high-pressure dissolution method in the present invention
As the solvent, those similar to the above-mentioned cooling dissolution method are preferable.
No.

In the present invention, the dope is filtered by a filter, left to stand and defoamed, and then immediately sent to a solution casting film forming apparatus, or is sent after being stored for a while. As the filter, a filter press in which frames sandwiching filter paper are stacked in many stages or a leaf disk filter in which metal cotton such as stainless steel is sintered is preferably used. Two or more of these filters may be used in combination. Recently, the demand for film quality has become more severe with the improvement in photographic image quality and the higher definition of liquid crystal displays, and the disadvantages of small insolubles are not allowed. To eliminate such drawbacks, the filter used to filter the dope is made finer or the filter is stacked many times.However, the dope with poor solubility immediately increases the filtration pressure, resulting in extremely low productivity. Will be dropped. Further, if the dope changes during the stagnation after the filtration, it affects not only the film forming property but also the quality of the film after the film forming. If the filtered dope undergoes gelation during stagnation, the dope cannot be sent to the casting device, so that filtration is necessary again. However, the gel is difficult to filter and passes through the filter medium to reduce the quality of the film, so that a dope that does not gel during storage is required.

The dope using the cellulose mixed acylate of the present invention does not cause gelation during storage, does not increase the filtration pressure, changes the filter material less frequently, has a smooth peeling property, and degrades the flatness due to peeling. And a film of excellent quality can be obtained.

As the equipment for producing the cellulose-mixed acylate film of the present invention, those used in the production of conventional cellulose triacetate films, such as the above-mentioned solution casting film forming apparatus, can be used. The outline of the equipment and the manufacturing method is as follows. The dope after filtration is sent from the die of the pressurized die (slit), which is sent to the pressurized die from the pressurized precision precision pump, which can send a fixed amount of liquid with high precision by the number of rotations, for example. It is evenly cast on the casting support that is rotating endlessly, and when the casting support has almost completed one round, it is rotating from the casting support as a dry cellulose mixed acylate film. The cellulose-mixed acylate film dried while being passed through a roll group is conveyed and wound up to a predetermined length by a winding machine after transport.

As the endless casting support used for producing the cellulose mixed acylate film of the present invention, a drum whose surface is mirror-finished by chrome plating or a stainless steel belt whose surface is mirror-finished by surface polishing ( Band (which may be referred to as a band).

As a casting method useful in the present invention, a method in which the prepared dope is uniformly extruded from a die onto a casting support while adjusting the flow rate by a gear pump or the like, or a method in which the dope is once cast on the casting support, is used. There is a method using a doctor blade for adjusting the film thickness of the spread dope with a blade, a method using a reverse roll coater for adjusting with a roll rotating in the reverse direction, and the like, and a method using a die is preferable. The die is also called an extrusion die, and includes a coat hanger type and a T-die type, and any of them can be preferably used.

The die for use in the production of the cellulose-mixed acylate film of the present invention may be disposed on the casting support on one or more dies. Preferably, it is one or two. When two or more units are installed, the amount of the dope to be cast may be divided into various ratios for each die, and the dope is sent from the plurality of precision quantitative pumps to the die at the respective ratios.

The drying of the solution on the casting support in the production of the cellulose-mixed acylate film of the present invention is generally carried out by using a web (dope) from the surface side of the drum or belt which is the casting support. The film between the time of casting and close contact with the support for casting and the time from peeling to drying may be referred to as a web), a method of applying hot air to the surface, a method of applying hot air from the back of the drum or belt, and temperature control. There is a liquid heat transfer method in which the liquid is brought into contact with the belt or drum from the back surface opposite to the solution casting surface, and the drum or belt is heated by heat transfer to control the surface temperature, but the back surface liquid heat transfer method is preferable. . The speed of producing the cellulose-mixed acylate film varies depending on the length of the belt, the drying method, the solution solvent composition, and the like,
It is largely determined by the amount of residual solvent when the web is peeled from the belt. In other words, if the solvent concentration in the vicinity of the belt surface in the thickness direction of the solution film is too high, the solution will remain on the belt when peeled, and it will hinder the next casting, and the remaining peeling will be absolute. This is because the cellulose-mixed acylate film must be strong enough to withstand the peeling force. The amount of residual solvent at the time of peeling differs depending on the method of drying on the belt or drum, and the method of transferring heat from the belt or drum back is more effective than the method of drying by blowing air from the solution surface. The amount can be reduced. The residual solvent amount of the web at the time of peeling is 20 to 150% by mass, preferably 50 to 100% by mass. The amount of residual solvent can be expressed by the following equation.

Residual solvent amount (% by mass) = {(M−N) / N} × 100 where M is the mass of the web at any time, and N is M
The mass when dried at 0 ° C. for 3 hours.

The surface temperature of the casting support and the temperature of the dope before casting are preferably from 20 ° C. to the boiling point of the main solvent. The higher the dope temperature and the temperature of the support for casting, the higher the drying speed of the solvent can be made, which is preferable. However, if the temperature is too high, foaming or flatness may deteriorate. Further, by setting the temperature of the casting support at the time of peeling to 10 ° C. to the boiling point of the main solvent, the adhesion between the web and the casting support can be reduced, which is preferable.

Usually, when a dope is cast and peeled as a web from a casting support, it is often difficult to peel a dope having good solubility as a web after casting, but the cellulose mixed acylate of the present invention is often used. Is good in solubility and excellent in peelability.

The method for setting the temperature of the casting support to different temperature conditions in the solution casting section and the web peeling section is not particularly limited. For example, when the casting support is an endless belt, the casting method is not limited. It can be easily implemented by separately installing the temperature control units in the part and the peeling part.

A method for drying a cellulose-mixed acylate film according to the present invention will be described. One casting support
The web peeled at the peeling position just before it goes around is transported alternately through a group of rolls arranged in a staggered manner, or the paper is transported non-contact by gripping both ends of the peeled web with clips Drying is performed by a method of blowing air at a predetermined temperature on both sides of the web being conveyed, or a method using a heating means such as a microwave while being conveyed. In the initial stage of drying, it is preferable to dry at a temperature that does not cause foaming of the solvent, and to perform drying at a high temperature after the drying proceeds.

In the drying step after peeling from the casting support, the web tends to shrink in the width direction due to evaporation of the solvent. The higher the temperature, the greater the shrinkage. Drying while suppressing this shrinkage as much as possible is preferable from the viewpoint of improving the flatness of the resulting cellulose mixed acylate film. From this point, for example, Japanese Patent Application Laid-Open
A method (tenter method) of drying the entire width of the web or a part of the web in the width direction while holding both ends of the width of the web with clips in the width direction as shown in JP-A-46625 can also be preferably used.

In the present invention, the drying temperature of the cellulose mixed acylate film (web) in the drying step is preferably from the boiling point of the main solvent to 250 ° C., particularly preferably 180 ° C. The drying temperature, the amount of drying air, and the drying time vary depending on the solvent used, and may be appropriately selected according to the type and combination of the solvents used.

The cellulose-mixed acylate film obtained as described above has a residual solvent content of 2.0% by mass or less, more preferably 0.4% by mass or less, in the final finished cellulose-mixed acylate film. This is preferable for obtaining a cellulose mixed acylate film having good stability.

The steps from casting to drying may be performed in an air atmosphere or an inert gas atmosphere such as nitrogen gas.

In the present invention, the winding machine for the cellulose-mixed acylate film may be any of those generally used, such as a constant tension method, a constant torque method, a taper tension method, and a program tension control method with a constant internal stress. It can be wound by a winding method.

The thickness of the finished cellulose-mixed acylate film of the present invention (after drying) varies depending on the purpose of use, but is in the range of 30 to 200 μm, and 50 to 150 μm for the film for a silver halide photographic light-sensitive material. Preferably, it is more preferably from 80 to 130 μm. The film for a liquid crystal image display device preferably has a thickness of 20 to 120 μm, more preferably 30 to 100 μm. The thickness of the cellulose-mixed acylate film is adjusted to a desired thickness by adjusting the solid content concentration in the solution, the slit gap of the die cap, the extrusion pressure from the die, the casting support for casting. What is necessary is just to adjust the speed of the body.

In the cellulose mixed acylate dope according to the present invention, a plasticizer, an antioxidant, a colorant, organic or inorganic fine particles and the like may be added.

For silver halide photographic light-sensitive materials, a plasticizer is added for improving mechanical properties or imparting flexibility, and for other colorants for preventing light piping, a dye or an ultraviolet inhibitor is added. You. Further, for a liquid crystal display device, it is preferable to add fine particles as a plasticizer, an antioxidant, an ultraviolet ray inhibitor, a slipping agent or an abrasion inhibitor.

As the plasticizer for the cellulose mixed acylate dope according to the present invention, phosphate esters, carboxylate esters, glycolate esters and the like are preferably used. Examples of phosphate esters include triphenyl phosphate (TPP), tricresyl phosphate (TC
P), cresyl diphenyl phosphate (CDPP),
Octyl diphenyl phosphate (ODPP), diphenyl biphenyl phosphate (DPBPP), trioctyl phosphate (TOP), tributyl phosphate (TBP), 2,2'-methylenebis (4,6-
Examples of carboxylic acid esters such as di-t-butylphenyl) sodium include dimethyl phthalate (DMP),
Diethyl phthalate (DEP), dibutyl phthalate (DBP), dioctyl phthalate (DOP), diethylhexyl phthalate (DEHP), acetyl triethyl citrate (TEAC), acetyl tributyl citrate (TBAC), butyl oleate (BO), ricinoleic acid Methylacetyl (AML), dibutyl sebacate (D
Examples of glycolic acid esters such as BS) and the like include triacetin (TA), tributyrin (TB), butylphthalylbutyl glycolate (BPBG), ethylphthalylethyl glycolate (EPEG), and methylphthalylethyl glycolate (MPEG). Examples of sorbitols include bis (p-methylbenzylidene) sorbitol,
Bis (p-ethylbenzylidene) sorbitol and the like can be mentioned. Among them, TPP, TCP, CDPP, T
BP, DMP, DEP, DBP, DOP, DEHP, T
A, EPEG, BPBG, DPBPP are preferred. Particularly, TPP, DEP, EPEG, BPBG, and BDP are preferable. Two or more of these plasticizers may be used in combination. The addition amount of the plasticizer is 2 to 30 with respect to the cellulose mixed acylate.
% By mass, particularly preferably 8 to 16% by mass. These compounds may be added together with the cellulose mixed acylate or the solvent during the preparation of the dope, or may be added during or after the solution preparation.

The coloring agent is preferably a dye which can be colored in gray as seen in a usual support for a silver halide photographic light-sensitive material, and its content is preferably from 10 to 1000 ppm by mass relative to the cellulose mixed acylate, and from 50 to 1,000 ppm. 5
00 ppm is more preferred. By including a dye in this way, light enters the cut end of the film support of the silver halide photographic light-sensitive material, causing a light piping phenomenon, and eliminating fog in which light enters the middle of the silver halide photographic light-sensitive material. Can be done. Preferred dyes include
The colorants for preventing light piping described in Japanese Patent Application No. 9-355097 can be exemplified. These compounds are
When preparing the dope, it may be added together with the cellulose mixed acylate or the solvent, or may be added during or after the preparation of the dope.

As antioxidants, hindered phenol compounds are preferably used, and 2,6-di-t-butyl-p-cresol, pentaerythrityl-tetrakis [3- (3,5-di-t- -Butyl-4-hydroxyphenyl) propionate], triethylene glycol-
Bis [3- (3-t-butyl-5-methyl-4-hydroxyphenyl) propionate], 1,6-hexanediol-bis [3- (3,5-di-t-butyl-4-hydroxyphenyl) Propionate], 2,4-bis-
(N-octylthio) -6- (4-hydroxy-3,5
-Di-t-butylanilino) -1,3,5-triazine, 2,2-thio-diethylenebis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], octadecyl-3- (3,5-di-t-butyl-
4-hydroxyphenyl) propionate, N, N'-
Hexamethylene bis (3,5-di-t-butyl-4-hydroxy-hydrocinnamamide), 1,3,5-trimethyl-2,4,6-tris (3,5-di-t-butyl-
4-hydroxybenzyl) benzene, tris- (3,5
-Di-t-butyl-4-hydroxybenzyl) -isocyanurate and the like. Especially 2,6-di-
t-butyl-p-cresol, pentaerythrityl-tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], triethylene glycol-bis [3- (3-t-butyl- 5-methyl-4-
Hydroxyphenyl) propionate] is preferred. Further, for example, a hydrazine-based metal deactivator such as N, N'-bis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionyl] hydrazine or tris (2,4
A phosphorus-based processing stabilizer such as (-di-t-butylphenyl) phosphite may be used in combination. The amount of addition of these compounds is 1 ppm to
1.0% is preferable, and 10 to 1000 ppm is more preferable.

The cellulose-mixed acylate film of the present invention can be used as an anti-scratching agent or a slipping agent by adding fine particles which are effective for improving the dynamic friction coefficient of the film, reducing the load in the winding step and increasing the scratch resistance. Good. The fine particles are selected from fine particles having an average particle size of 1.0 μm or less, which do not dissolve or swell in the organic solvent used, and inorganic fine particles are preferable. For example, fine particle silicon dioxide, titanium dioxide,
Aluminum oxide, zirconium oxide, talc, clay, calcined kaolin, calcined calcium silicate, hydrated calcium silicate, aluminum magnesium silicate,
Calcium phosphate and the like. Fine particles of an inorganic compound may be imparted with functions such as dispersion stability by surface treatment. Further, in addition to the above-mentioned inorganic compound fine particles, crosslinked organic polymer-based fine particles may be used. These may be mixed and used according to the purpose. Examples of the crosslinked organic polymer include, for example, crosslinked polymethyl methacrylate, crosslinked polyethyl methacrylate, crosslinked polybutyl methacrylate, crosslinked polystyrene, crosslinked polyamideimide, benzoguanamine-formaldehyde condensate, melamine-formaldehyde condensate, benzoguanamine-melamine-formaldehyde condensate Etc. can be used. The average particle diameter of the fine particles is preferably 1.0 μm or less, and the average particle diameter is 0.1 to 1.0 μm.
μm is more preferred. The fine particles are preferably added to the cellulose mixed acylate in an amount of 0.001 to 0.5% by mass, more preferably 0.01 to 0.3% by mass. The fine particles may be added at any stage in the preparation of the dope.In particular, in the case of a dope by a high-pressure dissolution method or a cooling dissolution method, the dope may be added after the dope is manufactured and then sufficiently stirred. Alternatively, the dope may be prepared at a high concentration, fine particles may be dispersed in a diluting solvent and added, and the dope may be diluted and stirred.

A cellulose-mixed acylate film having an ultraviolet light inhibitor can cut ultraviolet rays harmful to silver halide photographic materials, or deteriorate in a liquid crystal display even if the apparatus is exposed to ultraviolet rays for a long time. Not with time stability. Examples of the UV inhibitor include benzophenone compounds such as 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone,
-Hydroxy-4-n-octoxybenzophenone, 4
-Dodecyloxy-2-hydroxybenzophenone,
Benzotriazole compounds such as 2,2 ', 4,4'-tetrahydroxybenzophenone and 2,2'-dihydroxy-4,4'-dimethoxybenzophenone
2- (2'-hydroxy-5-methylphenyl) benzotriazole, 2- (2'-hydroxy-3 ', 5'-
Di-t-butylphenyl) benzotriazole, 2-
Examples of salicylic acid compounds such as (2'-hydroxy-3'-di-t-butyl-5'-methylphenyl) benzotriazole include phenyl salicylate and methyl salicylate. The amount of the UV inhibitor added is 0.5 to 20 with respect to the cellulose mixed acylate film.
%, More preferably 1 to 10% by mass.

The cellulose mixed acylate dope of the present invention may further contain an antistatic agent, a flame retardant,
Lubricants, oils and the like may be added.

[0076]

EXAMPLES The present invention will be described below with reference to examples.
The present invention is not limited to these.

[Evaluation Method / Measurement Method] <Viscosity Average Polymerization Degree (DP)> The viscosity average polymerization degree can be measured by an Ostwald viscometer, and the following method is used based on the measured intrinsic viscosity [h] of the cellulose mixed acylate. Can be obtained by

The dried cellulose mixed acylate was approximately 0.1%.
2 g was precisely weighed, and methylene chloride: ethanol = 9:
Dissolve in 100 ml of 1 (mass ratio) mixed solvent. This is measured with an Ostwald viscometer at 25 ° C for several seconds to fall,
The degree of polymerization is determined by the following equation.

H _rel = T / Ts [h] = (ln h _rel ) / CDP = [h] / Km where T: several seconds of falling of the sample to be measured Ts: several seconds of falling of the solvent alone C: concentration (g / g / l) Km: 6 × 10 ^-4 .

<Measurement of average degree of substitution> Tezuk
a¹³According to the method described in the C-NMR method,
Acetyl and propionyl groups at positions and / or
Is the average degree of butyryl substitution. ¹³Power of C-NMR spectrum
It is calculated and calculated from the area of the signal of rubonyl carbon.

<Evaluation of Solubility> After filtering the prepared dope, 800 ml was placed in a 1-liter transparent bottle with a lid, covered, and allowed to stand at 25 ° C. for 2 weeks to obtain transparency and uniformity of the dope. The occurrence of gel was observed by turning the bottle upside down. A: No transparency, no uniformity, and no sign of gelation. B: Good transparency, but slight slight unevenness. C: Transparency. Although it has good properties, there is a slight unevenness, and when the bottle is turned upside down, there is a gel that feels lumpy.

D: There is transparency, but when the bottle is turned upside down, the whole is crushed, and it comes down as a lump with a feeling of falling. E: It has a little transparency and is cloudy, and the whole is gel. F: Evaluated as if it was slightly white and gelled so that the whole could not move.

<Evaluation of Peeling Property> The dope is cast on a casting support (stainless steel belt), and a stripping position (a position with a peeling roll) before the casting support makes one rotation while evaporating the solvent. When the web is peeled off and transported through a peeling roll, the relationship between the peeling roll and the position at which the web separates from the casting support (the positional relationship between the casting support and the horizontal line of the peeling roll center axis) ：: Below the intersection of the casting support and the horizontal line of the center axis of the peeling roll, the web was peeled from the casting support uniformly without any change in the peeling point. ○: The web was separated from the casting support and the peeling roll. Near the intersection with the horizontal axis of the central axis, the web peeled from the casting support with almost no change in the peeling point. Δ: The flow was centered around the intersection of the horizontal axis of the support with the central axis of the peeling roll. Peeling point so that the web breathes from the spreading support The upper limit while peeling ×: upwards from the intersection of the casting support and the horizontal line of the center axis of the peeling roll, the web is evaluated as the peel while greatly varies point of separation from the casting support.

<Measurement of Retardation> Using an automatic birefringence meter KOBRA-21ADH (manufactured by Oji Scientific Instruments) at a wavelength of 590 nm at 23 ° C. and 55% RH.
, A three-dimensional refractive index measurement is performed to find refractive indexes nx, ny, and nz in each of the vertical, horizontal, and thickness directions. The retardation value (Rt value) is calculated according to the following formula: Rt value (nm) = {(nx + ny) / 2−nz} × d.
Here, nx is the refractive index in the direction parallel to the film forming direction of the film, ny is the refractive index in the direction parallel to the width direction with respect to the film forming direction, and nz is the refractive index in the thickness direction of the film. Represent.

<Measurement and Evaluation of Viewing Angle> A liquid crystal display device sample prepared as described below was provided with VG3 manufactured by AMT Co., Ltd.
White display with 65N video pattern generator,
Performs black display and 8-stage gray display, and adjusts the contrast ratio in white / black display by LCD-70 manufactured by Otsuka Electronics Co., Ltd.
At 00, the measurement was made in the range of 60 ° in the vertical and horizontal directions. An angle indicating a contrast ratio ≧ 10 is defined as a viewing angle. Also,
The viewing angle is visually observed separately from the above measurement values. ：: The contrast is clear in the range of the viewing angle of 60 ° ：: The contrast is almost clear in the range of the viewing angle of 60 ° Δ: The range of the viewing angle of 60 ° And the contrast was considerably unclear X: The contrast was evaluated as unclear in the range of the angle of view of 60 °.

<Measurement of Folding Resistance> ASTM D2176-6
According to 9, the film thickness is unified to 100 μm, the tension is set at 19.6 N, and the number of times until the film is torn is counted. The greater the number of times to break, the better.

Example 1 A mixture obtained by uniformly stirring and mixing 100 parts by mass of cellulose from linter pulp and 100 parts by mass of glacial acetic acid with respect to cellulose at room temperature was mixed with 245 parts by mass of acetic anhydride and 36 parts of acetic acid.
5 parts by mass and 15 parts by mass of sulfuric acid of the catalyst were charged into a cooled mixture in a reaction vessel, and an acetylation reaction was carried out at 47 ° C. for 60 minutes. At the end of the acetylation reaction, an aqueous solution of magnesium acetate (30% by mass) for hydrolysis and neutralization of 45.5 parts by mass was added to hydrolyze excess acetic anhydride and neutralize sulfuric acid. Then, while heating the reaction solution to 60 ° C.,
2.8 parts by weight of an aqueous magnesium acetate solution (30% by weight) for ripening were added. Then, after adding water,
The aging reaction was performed at 70 ° C. for 40 minutes. After the aging reaction,
About 20 parts by mass of a magnesium acetate aqueous solution (30% by mass) after the completion of the reaction was added to completely neutralize sulfuric acid to stop the reaction. After completion of the reaction, precipitation, washing and drying were performed with a large excess of water. In order to convert the remaining hydroxyl groups of the obtained cellulose acetate into a propionate, 1000 parts by mass of cellulose acetate, 1000 parts by mass of pyridine, 1500 parts by mass of propionic anhydride, and 50 parts by mass of 4- (N, N-dimethylamino) pyridine were added. Mix and stir with 10
After heating at 0 ° C. for 1 hour, the reaction mixture was poured into a large excess of methanol for precipitation, and further washed with methanol.
The obtained flakes were dried under vacuum to obtain cellulose acetate propionate. 19.2 parts by mass of the obtained cellulose acetate propionate was added to a mixed solution of 76.8 parts by mass of a mixed solvent of methyl acetate / ethanol (mixing ratio 80/20% by mass) and 1.2 parts by mass of ethylphthalylethyl glycolate. It was charged while stirring. Continue stirring for 1
After a period of time, a transparent and uniform cellulose acetate propionate solution (dope) was obtained. The film thickness after drying was 100 μm on a mirror belt at 35 ° C.
, Dried, peeled at a residual solvent amount of 60% by mass, maintained in width, dried at 110 ° C., and obtained a rolled-up cellulose acetate propionate film. The residual solvent amount of the film immediately before winding was 0.15% by mass.

Example 2 11 parts by mass of sulfuric acid as a catalyst, 35.5 parts by mass of an aqueous solution of magnesium acetate for hydrolysis and neutralization, 9.8 parts by mass of an aqueous solution of magnesium acetate for aging, and acetic acid after completion The procedure was performed in the same manner as in Example 1, except that the magnesium aqueous solution was changed to 10 parts by mass and the propionic anhydride was changed to 1500 parts by mass.

Example 3 17 parts by mass of sulfuric acid as a catalyst, 46.5 parts by mass of an aqueous solution of magnesium acetate for hydrolysis and neutralization, 10.8 parts by mass of an aqueous solution of magnesium acetate for aging, and acetic acid after completion Example 1 was repeated except that the aqueous magnesium solution was 13.5 parts by mass and the propionic anhydride was 1800 parts by mass.

Example 4 The procedure of Example 1 was repeated except that the catalyst was changed to 11 parts by mass of sulfuric acid, 10 parts by mass of an aqueous solution of magnesium acetate after completion, and 1500 parts by mass of propionic anhydride. Performed in the same manner as in Example 1.

Example 5 10 parts by mass of sulfuric acid as a catalyst and a reaction temperature of 45 ° C., and an aqueous solution of magnesium acetate for hydrolysis and neutralization of 30.
Cellulose acetate propionate was obtained by the same synthesis method as in Example 1, except that 5 parts by mass, 10 parts by mass of the aqueous magnesium acetate solution after completion, and 1800 parts by mass of propionic anhydride were used. The average degree of substitution is shown in Table 1. 19.2 parts by mass of the obtained cellulose acetate propionate was mixed with methylene chloride / ethanol (85/15).
8 parts by mass and ethylphthalylethyl glycolate
The mixture was added to 2 parts by mass of the mixed solution with stirring. When stirring was continued for 2 hours, a transparent and uniform cellulose acetate propionate dope was obtained. Using this dope, solution casting was performed in the same manner as in Example 1 to obtain a cellulose acetate propionate film.

Example 6 A mixture obtained by uniformly stirring and mixing 100 parts by mass of cellulose from linter pulp and 100 parts by mass of glacial acetic acid at room temperature with respect to cellulose was mixed with 300 parts by mass of acetic anhydride, 200 parts by mass of butyric anhydride, 75 parts by mass, 50 parts by mass of butyric acid and 10 parts by mass of sulfuric acid as a catalyst were put into a cooled mixture in a reaction vessel, and an acetylation reaction was carried out at 47 ° C. for 60 minutes. continue,
While the reaction solution was raised to 60 ° C., 200 parts by mass of 50 parts by mass of an aqueous acetic acid solution were added thereto, and an aging reaction was performed at 70 ° C. for 40 minutes. After the completion of the reaction, 230 parts by mass of a 30% by mass aqueous solution of magnesium acetate was added to completely neutralize sulfuric acid to stop the reaction. Thereafter, the precipitate was washed with a large excess of water, washed, and dried to obtain cellulose acetate butyrate. The average degree of substitution is shown in Table 1. 19.2 parts by mass of the obtained cellulose acetate butyrate was stirred in a mixed solution of 76.8 parts by mass of a mixed solvent of methyl acetate / ethanol (mixing ratio 80/20% by mass) and 1.2 parts by mass of ethylphthalylethyl glycolate. We put in while. When stirring was continued for 2 hours, a transparent and uniform cellulose acetate butyrate dope was obtained. Using this dope, solution casting was performed in the same manner as in Example 1 to obtain a cellulose acetate butyrate film.

Comparative Example 1 100 parts by mass of cellulose from linter pulp and cellulose
100 parts by weight of glacial acetic acid with respect to
The mixture obtained by stirring and mixing was mixed with 260 parts by mass of acetic anhydride and 36 parts of acetic acid.
Cooling 5 parts by weight and 10 parts by weight of sulfuric acid of the catalyst in the reactor
Into the mixture, and the acetylation reaction was carried out at 45 ° C for 60 minutes.
Was. At the end of the acetylation reaction, 27.7 parts by mass of hydrolysis and
Magnesium acetate aqueous solution (30% by mass) for neutralization
In addition, hydrolysis of excess acetic anhydride and neutralization of sulfuric acid
Was done. Then, while heating the reaction solution to 60 ° C.
9.5 parts by weight of magnesium acetate aqueous solution for aging
(30% by mass) was added. After that, the concentration is about 85 mass
% And then aged at 70 ° C for 40 minutes
The reaction was performed. After the aging reaction, about 10 parts by mass of the reaction
After the addition of the aqueous magnesium acetate solution (30% by mass),
The reaction was stopped by completely neutralizing the sulfuric acid. After the reaction,
Perform precipitation, washing and drying with excess water,
I got the acetate. No propionylation was performed. average
The substitution degree is shown in Table 1. Cellulose acetate obtained
19.2 parts by weight of a methyl acetate / ethanol mixed solvent (mixed
80/20% by mass) 76.8 parts by mass and ethyl acetate
Stir into a mixed solution of 1.2 parts by mass of taryl ethyl glycolate.
It was charged with stirring. The stirring was continued for 1 hour.
A slightly cloudy cellulose acetate solution was formed. Change
The mixture was stirred for 1 hour.
A acetate solution was obtained. The resulting solution was
Fill the aluminum container with aluminum to prevent air from entering.
It was covered with a minium foil and sealed by swaging. This dense
Pack the closed container in a rubber bag, gently deaerate
Enclosed. This rubber bag is made of ceramic mold
Set in a pressure and pressure device (made by Kobe Steel) and keep it at 20 ° C
9.8 × 10 ⁷It was pressurized at a pressure of Pa for 2 hours. That
Thereafter, the pressure was slowly returned to the atmospheric pressure, and the mixture was allowed to stand for 30 minutes. This pressurization
The release cycle was repeated three times to obtain a dope. this
A solution casting film was formed in the same manner as in Example 1 using the dope.
A cellulose acetate film having a thickness of 100 μm was obtained.

Comparative Example 2 A mixture obtained by uniformly stirring and mixing 100 parts by mass of cellulose from linter pulp and 100 parts by mass of glacial acetic acid with respect to cellulose at room temperature was mixed with 280 parts by mass of acetic anhydride and 36 parts of acetic acid.
5 parts by mass and 10 parts by mass of sulfuric acid as a catalyst were charged into a cooled mixture in a reaction vessel, and an acetylation reaction was carried out at 47 ° C. for 60 minutes. At the end of the acetylation reaction, 27.7 parts by mass of an aqueous solution of magnesium acetate (30% by mass) for hydrolysis and neutralization was added to hydrolyze excess acetic anhydride and neutralize sulfuric acid. Thereafter, while heating the reaction solution to 60 ° C., about 9.5 parts by mass of an aqueous solution of magnesium acetate (30% by mass) for aging was added. Then, after adding water,
The aging reaction was performed at 70 ° C. for 40 minutes. After the aging reaction,
About 10 parts by mass of an aqueous magnesium acetate solution (30% by mass) after the completion of the reaction was added to completely neutralize sulfuric acid to terminate the reaction. After completion of the reaction, precipitation, washing and drying were performed with a large excess of water to obtain cellulose triacetate. No propionylation was performed. A mixed solution of 76.8 parts by mass of a mixed solvent of methyl acetate / ethanol (mixing ratio 80/20% by mass) and 1.2 parts by mass of ethylphthalylethyl glycolate was cooled to -70 ° C, and stirred therewith for 19 hours. .2
Parts by weight of the resulting cellulose acetate were added. After about 10 minutes, the cellulose acetate swelled, so stirring was stopped, and the mixture was left at -70 ° C for 1 hour. Thereafter, the cooled mixture was heated to 50 ° C. and allowed to stand for 30 minutes.
The cooling-warming cycle of the mixture was repeated twice to obtain a transparent and uniform dope. Using this dope, solution casting was performed in the same manner as in Example 1 to obtain a cellulose acetate film having a thickness of 100 μm.

For the samples of Examples 1 to 6, the average degree of substitution of the acetyl group and propionyl group at the 2-, 3- and 6-positions of cellulose acetate propionate and cellulose butyrate was determined by ¹³ C-NMR measurement. Asked,
Total average substitution degree (X2 + X3 + X6 + Y2 + Y3 + Y
6), the average degree of substitution of the acetyl group and propionyl group at the 6-position (X6 + Y6), and the average degree of substitution of the propionyl group at the 6-position are shown in Table 1. The viscosity average polymerization degrees were all 400.

For the samples of Comparative Examples 1 and 2, the degree of substitution of the acetyl group at the 2-, 3- and 6-positions of cellulose triacetate was determined by ¹³ C-NMR measurement, and the total average degree of substitution (X2 + X3 + X6), 6 Table 1 shows the degree of substitution of the acetyl group at the position (X6 + Y6, where Y6 = 0).

<Preparation of Sample for Liquid Crystal Display> The films of Examples 1 to 6 and Comparative Examples 1 and 2 were prepared at 40 ° C.
A saponification treatment was carried out with a 5 mol / l sodium hydroxide aqueous solution for 60 seconds, and the surface was saponified by washing with water for 3 minutes to obtain a saponified film. Next, a polyvinyl alcohol film having a thickness of 120 μm was immersed in 100 parts by mass of an aqueous solution containing 1 part by mass of iodine and 4 parts by mass of boric acid, and stretched 4 times at 50 ° C. to produce a polarizing film. The saponified film was bonded to both sides of the polarizing film using an aqueous solution of 5% by mass of polyvinyl alcohol having a complete saponification degree as an adhesive to prepare a polarizing plate.
Next, this was installed on both sides of a VA type liquid crystal cell, and a liquid crystal image display device sample was produced.

The solubility of the cellulose mixed acylates of Examples 1 to 6 and Comparative Examples 1 and 2 was examined, and the dope was cast on a casting support and then peeled at the peeling point to examine the peelability. Table 1 shows the results of measuring the folding resistance of the resulting film, evaluating the retardation, and measuring and evaluating the viewing angle (up, down, left, and right) with a liquid crystal image display device sample.

[0099]

[Table 1]

(Results) 6 of glucose units of cellulose
The cellulose mixed acylate in which the acetyl group and the propionyl group and / or the butyryl group are substituted within the scope of the present invention with respect to the cellulose triacetate substituted only with the acetyl group at the position is soluble, peelable, retardation, viewing angle, folding resistance. The degree was found to be excellent. It was also found that the preparation of a dope and the production of a film using a chlorine-based organic solvent were possible.

[0101]

According to the substitution position and the degree of substitution of the glucose unit of the propionyl group and / or butyryl group of the cellulose mixed acylate at 6-position and the degree of substitution, the dope is stable and the dope is stable, retardation, viewing angle, folding resistance. Is obtained, and an excellent film for a liquid crystal image display device can be provided.

[Brief description of the drawings]

FIG. 1 is a schematic drawing of a solution casting film forming apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Web 2 Die 3 Casting support 4 Peeling roll 5 Drying device 6 Roll group 7 Dry air

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) G03C 1/795 G03C 1/795 4J002 F-term (Reference) 2H023 FA01 FA13 2H049 AA43 BB49 2H091 FA50X FB02 HA07 HA10 LA30 4F071 AA09 AC03 AC05 AC10 AE19 AH12 BA02 BB02 BC01 4F205 AA01 AC05 AG01 AH42 GA07 GB02 GC02 GC07 GE22 GE24 GF24 4J002 AB021 FD020 FD050 FD070 FD170 GP03 GQ00 HA05

Claims (8)

[Claims] 1. A cellulose mixed acylate having an acetyl group, a propionyl group and / or a butyryl group as a substituent, wherein Y6 has at least a propionyl group and / or a butyryl group and has an average degree of substitution satisfying the following formula. A cellulose mixed acylate characterized by the following: 3.00 ≧ (X2 + X3 + X6 + Y2 + Y3 + Y6) ≧
2.45 0.95 ≧ (X6 + Y6) ≧ 0.10 (where X2 is second, X3 is third, and X6 is six
Average substitution degree of acetyl group substituted for each hydroxyl group, Y2 is 2-position, Y3 is 3-position, and Y6 is average substitution degree of propionyl group and / or butyryl group substituted for each hydroxyl group at 6-position. And (X6 + Y6) is the average degree of substitution of the acyl group (acetyl group and propionyl group and / or butyryl group) substituted for the hydroxyl group at the 6-position. ) 2. The cellulose mixed acylate according to claim 1, wherein (X6 + Y6) has an average degree of substitution satisfying the following expression. 0.87 ≧ (X6 + Y6) ≧ 0.10 3. A mixed cellulose acylate having an acetyl group, a propionyl group and / or a butyryl group as a substituent, wherein the mixed cellulose acylate has an average degree of substitution satisfying the following formula. 3.00 ≧ (X2 + X3 + X6 + Y2 + Y3 + Y6) ≧
2.45 0.95 ≧ (X6 + Y6) ≧ 0.10 0.34 ≧ Y6 ≧ 0.10 (where X2 is second, X3 is third, and X6 is six
Average substitution degree of acetyl group substituted for each hydroxyl group, Y2 is 2-position, Y3 is 3-position, and Y6 is average substitution degree of propionyl group and / or butyryl group substituted for each hydroxyl group at 6-position. And (X6 + Y6) is the average degree of substitution of the acyl group (acetyl group and propionyl group and / or butyryl group) substituted for the hydroxyl group at the 6-position. ) 4. The cellulose mixed acylate according to claim 3, wherein (X6 + Y6) has an average degree of substitution satisfying the following expression. 0.87 ≧ (X6 + Y6) ≧ 0.10 5. The cellulose mixed acylate according to claim 1, wherein the cellulose mixed acylate is at least one selected from methylene chloride, methyl acetate and fluoroalcohol.
A method for preparing a cellulose-mixed acylate dope, comprising dissolving one as a main solvent. 6. The dope is 2 to 30% by mass and has 4 carbon atoms.
6. The composition according to claim 5, which comprises the following alcohol:
The method for preparing a cellulose-mixed acylate dope according to the above item. 7. A method for producing a cellulose-mixed acylate film, comprising forming a film by a solution casting method using the cellulose-mixed acylate dope prepared by the method according to claim 5 or 6. 8. A cellulose mixed acylate film produced by the method according to claim 7.