JP2003103545A - Method for manufacturing cellulose acylate film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cellulose acylate film improved in peelability at the time of production and film surface properties and having no problem from an aspect of durability. SOLUTION: In the method for manufacturing the cellulose acylate film by casting two or more layers by a co-casting method, an additive A selected from a partial ester of a polybasic acid of which the acid dissociation index (pKa) in an aqueous solution is 1.93-<4.50, an alkali metal salt thereof and an alkaline earth metal salt thereof is added to a solution prepared by dissolving cellulose acylate in a solvent substantially constituted of a non-chlorine type solvent and constituting either one of two or more layers and an additive B being an amine compound with pKa of 4.50 or more or an amine compound having no volatility substantially and having a molecular weight per one basic group of 200 or less is added to the solution constituting at least one layer containing no additive A.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art Cellulose acylate film is used in various photographic materials and optical materials because of its toughness and flame retardancy. Cellulose acylate film is a typical photographic light-sensitive material support. The cellulose acylate film is also used in liquid crystal display devices whose market is expanding recently due to its optical isotropy. Typical applications for liquid crystal display devices are protective films for polarizing plates and color filters.

The cellulose acylate film is generally produced by a solvent casting method or a melt casting method. In the solvent cast 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. Therefore, practically, the solvent casting method is usually adopted. The solvent cast method is described in many documents. In the recent solvent cast method, the problem is to improve the productivity of the film-forming process by shortening the time required from casting the dope onto the support to peeling the molding film on the support. Has become. For example, Japanese Examined Patent Publication No. 5-17844 proposes casting a high-concentration dope on a cooling drum to reduce the time required for stripping after casting.

The solvent used in the solvent casting method is required not only to dissolve the cellulose acylate but also to various conditions. In order to economically and efficiently produce a film having excellent flatness and a uniform thickness, it is necessary to prepare a solution (dope) having an appropriate viscosity and polymer concentration and excellent storage stability. For dope,
It is also required that gelation is easy and peeling from the support is easy. In order to prepare such a dope, the selection of solvent type is extremely important. The solvent is also 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. Although practically limited organic solvents are practically limited to methylene chloride, methylene chloride has problems such as environmental suitability and boiling point, and a solvent that can substitute for it has been searched. There is.

J. M. G. Papers by Cowie et al., Mak
romol, chem. , 143, p. 105 (197
1 year) is a cellulose acylate having a degree of substitution of 2.80 to 2.90 in acetone at −80 ° C. to −70 ° C.
It was reported that a dilute solution in which the cellulose acylate was dissolved in acetone in an amount of 0.5 to 5% by mass was obtained by cooling after cooling to 0. Is limited to acetyl groups). Less than,
A method of cooling a mixture of cellulose acylate and an organic solvent to obtain a solution in this manner is called a "cooling dissolution method". Regarding dissolution of cellulose acylate in acetone, Kenji Uede et al., "Dry-spinning of cellulose triacetate from acetone solution", Journal of the Textile Machinery Society, 34
Volume, page 57 (1981). As its title suggests, this paper applies the cooling dissolution method to the technical field of spinning method. In this paper, the cooling dissolution method is examined, paying attention to the mechanical properties, dyeability and cross-sectional shape of the fiber obtained. In this paper, a solution of cellulose acetate having a concentration of 10 to 25% by weight is used for fiber spinning. In addition to the above-mentioned cooling dissolution, a "high temperature melting method" has been proposed in which the mixture is melted under high temperature and high pressure conditions.

In this way, a cellulose acylate solution (dope) dissolved in various solvents is cast on a metal support, and the film is peeled from the support and dried to obtain a casting method. In many cases, the surface condition of the cellulose acylate film was not good, and the optical properties such as transparency were not good. Further, the peeling resistance from the metal support was high, and the film sometimes remained partially on the metal support.

[0007]

As a result of the study by the present inventors, the acid dissociation index pKa in an aqueous solution is 1.93 to 4.5.
It has been clarified that the releasability from the metal support can be improved by adding an additive selected from the partial ester form of polybasic acid which is 0, its alkali metal salt and its alkaline earth metal salt. However, these additives not only decrease the stability of the cellulose acylate solution and decrease the transparency of the film depending on the addition amount, but also
It has been found that it accelerates the deacylation of the film over time and reduces its durability. An object of the present invention is to provide a cellulose acylate solution which is free from problems in terms of releasability from a metal support in a practical dope concentration region having excellent stability over time by utilizing the above-mentioned release agent. is there. Furthermore, the object of the present invention is to
Another object is to produce a cellulose acylate film which is excellent in optical properties and film strength and has no problem of durability.

[0008]

The above objects of the present invention can be achieved by carrying out the following methods (1) to (13). (1) A method for producing a cellulose acylate film, which comprises casting two or more layers by a co-casting method, wherein the cellulose acylate is dissolved in a solvent composed essentially of a chlorine-free solvent, The acid dissociation index pKa in the aqueous solution is 1.93 to in the solution constituting one or more layers.
A solution containing at least one additive A selected from a partial ester of a polybasic acid of less than 4.50, an alkali metal salt thereof and an alkaline earth metal salt thereof, and having a pKa of 4 or more in a solution containing no additive A. .50 or more amine compounds,
Alternatively, the method for producing a cellulose acylate film is characterized by containing Additive B which is substantially amine-free and has a molecular weight of 200 or less per basic group. (2) The method for producing a cellulose acylate film according to (1), wherein the dry film thickness of the outer layer on at least one side of the cellulose acylate film is in the range of 1 to 50 μm.

(3) The cellulose acylate film has a multilayer structure of three or more layers, and the additive A is added only to a solution forming a layer in contact with the metal support (1) or The method for producing a cellulose acylate film according to (2). (4) The additive A is composed of a mixture of compounds selected from at least one partial ester of a polybasic acid, an alkali metal salt thereof and an alkaline earth metal salt thereof (1) to The method for producing a cellulose acylate film according to any one of (3).

(5) The addition amount of the additive A is in the range of 1 × 10 ^{-9 to} 3 × 10 ^-5 mol per 1 g of the cellulose acylate contained in the solution (1)
A method for producing a cellulose acylate film according to any one of (4) to (4). (6) The addition amount of the additive A is in the range of 1 × 10 ^{−10 to} 3 × 10 ⁻⁶ mol per 1 g of cellulose acylate film, among (1) to (5) The method for producing a cellulose acylate film according to any one of the above. (7) The additive A is an additive selected from oxalic acid, malonic acid, tartaric acid, citric acid, succinic acid, a partial ester of glutaric acid, an alkali metal salt thereof and an alkaline earth metal salt thereof, and these The method for producing a cellulose acylate film according to any one of (1) to (6), which is a mixture.

(8) The amount of the additive B added is 1 × 10 ^{-9 to} 3 × 1 per 1 g of the cellulose acylate in the solution.
The method for producing a cellulose acylate film according to any one of (1) to (7), which is in the range of 0 ^-5 mol. (9) The addition amount of the additive B is in the range of 1 × 10 ^{−10 to} 3 × 10 ⁻⁶ mol per 1 g of cellulose acylate film, among (1) to (8) The method for producing a cellulose acylate film according to any one of the above.

(10) The non-chlorine solvent comprises a mixed solvent of at least a ketone having a solubility parameter of 19 to 21 and an ester having a solubility parameter of 19 to 21. (1) to (9) The method for producing a cellulose acylate film according to any one of the above. (11) The chlorine-free solvent is 2 to 30 with respect to all the solvents.
A mixture of a solvent and a cellulose acylate containing 80% by mass of alcohol has a temperature of −80 to −10 ° C. or 80 to 2
The method for producing a cellulose acylate film according to any one of (1) to (10), wherein the cellulose acylate film is dissolved by being exposed to a temperature of 20 ° C.

(12) Substantially composed of cellulose acylate having a total acyl substitution degree of 2.75 or more and 2.90 or less and a 6-position acyl substitution degree of 0.90 or more. The method for producing a cellulose acylate film according to any one of (1) to (11) above. (13) A polarizing plate protective film formed from the cellulose acylate film according to any one of (1) to (12).

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION The cellulose acylate raw material cotton preferably used in the present invention is described in “4. Can be used.

The basic principle of the method for synthesizing cellulose acylate is described in Ueda et al., Wood Chemistry, pages 180-190 (Kyoritsu Shuppan, 1968). A typical synthesis method is a liquid phase acetylation method using an acetic anhydride-acetic acid-sulfuric acid catalyst. Specifically, after pre-treating a cellulose raw material such as wood pulp with an appropriate amount of an organic acid, it is put into a pre-cooled acylation mixture to be esterified to obtain a complete cellulose acylate (2nd, 3rd and 6th positions). The total degree of acyl substitution is about 3.00). The above acylation mixture is generally
It contains an organic acid as a solvent, an anhydrous organic acid as an esterifying agent and sulfuric acid as a catalyst. The organic acid anhydride is usually used in a stoichiometric excess amount over the total amount of the cellulose which reacts with the water and the water present in the system. After the completion of the acylation reaction, a neutralizing agent (for example, calcium, magnesium, iron, aluminum or zinc) is used for hydrolysis of excess organic acid anhydride remaining in the system and neutralization of a part of the esterification catalyst. Aqueous solution of carbonate, acetate or oxide).

Next, the obtained complete cellulose acylate is saponified and aged by keeping it at 50 to 90 ° C. in the presence of a small amount of an acetylation reaction catalyst (generally, residual sulfuric acid), to obtain a desired acyl. A cellulose acylate having a degree of substitution and a degree of polymerization is changed. At the time when the desired cellulose acylate is obtained, the catalyst remaining in the system is completely neutralized using the above-mentioned neutralizing agent, or
Without neutralization, the cellulose acylate solution is added to water or diluted sulfuric acid (or water or diluted sulfuric acid is added to the cellulose acylate solution) to separate the cellulose acylate, and washing and stabilization treatment are performed. Obtain cellulose acylate.

In the present invention, the cellulose acylate film is preferably produced by the solvent casting method, and the film is produced by using the cellulose acylate dope. The organic solvent used is not particularly limited,
It is a mixture of ketones and esters, and a solvent having a solubility parameter of 19 to 21 is preferably used. These esters and ketones may have a cyclic structure or may have two or more types of functional groups.

Next, the solubility parameter of the solvent will be described. Solubility parameter is calculated by
H is a quantity defined by (ΔH / V) ^1/2 where V is the molar volume, and the solubility increases as the difference between the solubility parameters of the two becomes smaller. There are many books that describe solubility parameters, but for example, J. Brandru
p, E. H et al.'S Polymer Handbook (fo
urth edition, VII / 671 to VII / 714).

Examples of the esters include methyl formate, ethyl formate, propyl formate, methyl acetate, ethyl acetate and the like. Of these, methyl acetate is particularly preferable. Examples of ketones include acetone, methyl ethyl ketone, diethyl ketone, methyl isobutyl ketone, cyclopentanone, cyclohexanone and the like. Of these, acetone, cyclopentanone, and cyclohexanone are particularly preferable.

By the way, from the viewpoint of the global environment and work environment,
The organic solvent preferably contains substantially no chlorine-based solvent. "Substantially free" means that the proportion of the chlorine-based solvent in the organic solvent is less than 10% by mass, preferably less than 5% by mass, more preferably less than 3% by mass. Further, it is preferable that no chlorine-based solvent such as methylene chloride is detected in the produced cellulose acylate film.

Examples of alcohols include methanol,
Ethanol, 1-propanol, 2-propanol, 1
-Butanol, 2-butanol and cyclohexanol, 2-fluoroethanol, 2,2,2-trifluoroethanol and the like. Of these, particularly preferred are methanol, ethanol, 1-propanol, 2-
Propanol and 1-butanol.

The actual solvent system is that the esters are 4% of the total solvent.
0 to 95% by mass, preferably 50 to 80% by mass,
The ketones are 5 to 50% by mass of the total solvent, preferably 10 to
It is preferably 40% by mass. Further, the amount of ketones and esters is preferably 70% by mass or more of the total solvent. Moreover, it is preferable that the alcohols are contained in an amount of 2 to 30% by mass of all the solvents.

Specific examples of combinations of these solvents which are preferable in the present invention are described in JIII Journal of Technical Disclosure, 2001-1745,
The first line on the right side of page 15 to the eighth line on the left side of page 16 can be mentioned. However, as described above, it is necessary to select a solvent that does not contain chlorine-based solvent in principle.

Next, the substitution degree of cellulose acylate will be described. The β-1,4-bonded glucose unit that constitutes cellulose has a free hydroxyl group at the 2-position, 3-position and 6-position. Cellulose acylate is a polymer in which some or all of these hydroxyl groups are esterified with acetic acid. The degree of acyl substitution is 2-, 3- and 6-
For each of the positions, the ratio of esterification of cellulose (100% esterification is 1.00) is meant. The cellulose acylate used in the present invention is not limited with respect to the degree of substitution, but the total degree of acyl substitution is 2.75 or more and 2.90 or less, and the degree of acyl substitution at the 6-position is 0.90 or more. Cellulose acylate can be preferably used.

When the total degree of all acyl substitution is 2.75 or less, the film is apt to absorb moisture and is easily hydrolyzed, so that the durability of the film is deteriorated. In addition, dimensional changes due to humidity and the like also increase. On the other hand, when it is 2.90 or more, the organicity of the cellulose acylate increases, the affinity with the solvent increases, the viscosity of the dope increases, and uniform dissolution becomes difficult. Therefore, the total degree of acyl substitution is 2.75.
As described above, it is preferably 2.90.

By the way, it has been found that the 6-position hydroxyl group is a primary hydroxyl group, unlike the 2- and 3-position hydroxyl groups, and therefore hydrogen bonds of the hydroxyl groups are extremely likely to occur. Therefore, by setting the degree of acyl substitution at the 6-position to 0.90 or more, the solubility in a solvent is remarkably improved and the viscosity is lowered, so that it becomes possible to obtain a dope which is preferable in casting suitability. The range of the degree of acyl substitution at the 6-position is 0.90 in consideration of suitability for synthesis and the like.
It is preferably 0.99 or more, and more preferably 0.92 or more and 0.98 or less. Further, the degree of acyl substitution at the 6-position is 0.
From the viewpoint of film strength, it is desirable that the number of carbon atoms of the acyl substituent in the cellulose acylate of 90 or more is smaller, and it is preferable that all of them are acetyl groups.

In order to prepare a cellulose acylate solution, the above-mentioned cellulose acylate is added to the solvent in a tank at room temperature with stirring to swell the solvent. The swelling time must be at least 10 minutes or longer, and if it is 10 minutes or less, insoluble matter remains. The temperature of the solvent is 0 to 4 in order to swell the cellulose acylate sufficiently.
0 ° C is preferred. When the temperature is 0 ° C. or lower, the swelling rate decreases and insoluble matter tends to remain, and when the temperature is 40 ° C. or higher, the swelling occurs rapidly and the central portion does not swell sufficiently. To dissolve the cellulose acylate after the swelling step, the cooling dissolution method,
It is preferable to use either or both of the high temperature melting methods.

Specific examples of the cooling melting method and the high temperature melting method are disclosed in JIII Journal of Technical Disclosure 2001-1745,
Examples thereof include those described in (Cooling melting method) and (High temperature melting method) on page 15, left column, line 15 to page 25, left column, line 9.

In some cases, the dope cellulose acylate of the present invention obtained above may be dissolved at a low concentration in order to make it more soluble, and then concentrated using a concentration means. As a specific method, the method described in JIII Journal of Technical Disclosure 2001-1745, page 25, left line, lines 10 to 28 (solution concentration) can be mentioned.

Prior to casting, it is preferable to remove foreign matters such as undissolved substances, dust and impurities by filtration using an appropriate filter material such as wire mesh, paper or flannel. As a specific method, there can be mentioned the method described in JIII Journal of Technical Disclosure 2001-1745, page 25, from the 29th line on the left side to the 33rd line on the right side (filtration).

Next, the additive A in the present invention will be shown. In forming the cellulose acylate film of the present invention, at least one additive is added before casting the cellulose acylate solution. The additive A is a compound selected from a partial ester of a polybasic acid having an acid dissociation index pKa in an aqueous solution of 1.93 to less than 4.50, an alkali metal salt thereof, and an alkaline earth metal salt thereof. is necessary. The "partial ester" means a part of the acid of the polybasic acid which is esterified, and in the case of citric acid, for example, a citric acid monoester body and a citric acid diester body are represented. The present inventors have used various acids (for example, oxalic acid, succinic acid, citric acid, etc.) as the additive A. However, when these acids form an alkali metal salt or an alkaline earth metal salt, they are in solution. Precipitation sometimes occurred. The studies conducted by the present inventors have revealed that derivatization of these acids into partial ester forms can avoid problems such as precipitation.

The type of the additive A used together with its pKa are shown below, but the additive A that can be used is not limited to this. For example, aliphatic polycarboxylic acids [monoethyl malonate (2.65) and monomethyl (2.6)
5), monopropyl succinate (4.00), monomethyl glutarate (4.13), monomethyl adipate (4.
26), monoethyl pimelic acid (4.31), monomethyl azelate (4.39), monobutyl fumarate (2.85), etc.], oxycarboxylic acid [monoethyl tartrate (2.89) and diethyl (2.82-). 2.9
9), monoethyl citrate (2.87), methyl ethyl citrate (2.87), etc.], aromatic polycarboxylic acid [monoethyl phthalate (2.75), monopropyl isophthalate (3.50)] , Monobutyl terephthalate (3.54), etc.], heterocyclic polycarboxylic acid [2,6
-Pyridine dicarboxylate monoethyl (2.09), etc.], amino acids [monoethyl glutamate (2.1
8) etc.] can be mentioned.

Also, two or more of these compounds may be used in combination. For example, a mixture of citric acid monoethyl ester and citric acid diethyl ester in a mass ratio of 5: 5,
Examples include a mixture of citric acid monomethyl ester and tartaric acid diethyl ester in a mass ratio of 8: 2. Actually, in the synthesis of partial ethyl ester form of citric acid, citric acid monoethyl ester form and citric acid diethyl ester form, and even a very small amount of citric acid triethyl ester form are produced. Further, a mixture of triesters, for which no peeling promoting effect is observed, can be used as the additive A. In addition, citric acid monoethyl ester and tartaric acid dimethyl ester may be intentionally mixed and used in terms of solubility.

Further, the above-mentioned additive A is sulfonic acid, phosphorus
Improved release can be expected by using an acid-based material together.
It These are in the form of surfactants because of their solubility.
Preferably there is. Specifically, JP-A-61-243
The material described in Japanese Patent No. 837 can be preferably used.
Wear. As a specific example, C₁₂H_{twenty five}OP (= O)-(O
K)₂, C₁₂H_{twenty five}OCH₂CH₂OP (= O)-(O
K)₂, (Iso-C ₉H₁₉)₂-C₆H₃-O- (C
H₂CH₂O)₃-(CH₂)_FourSO₃Na is mentioned
It

The acid may be used as a free acid, or as an alkali metal salt or an alkaline earth metal salt. Examples of the alkali metal include lithium, potassium and sodium, and examples of the alkaline earth metal include calcium, magnesium, barium and strontium. Preferred alkali metals include sodium, and preferred alkaline earth metals include calcium and magnesium. However, alkali metals are more preferable than alkaline earth metals. These alkali metals and alkaline earth metals can be used alone or in combination of two or more, and an alkali metal and an alkaline earth metal may be used in combination.

The total content of the above-mentioned additive A, acid and its metal salt
Amount is within the range that does not impair peelability and transparency, eg
For example, 1 x 10 per 1 g of cellulose acylate^-9~ 3
× 10 ^-FiveMol, preferably 1 × 10^-8~ 2 x 10^-FiveMole
(For example, 5 × 10^-7~ 1.5 × 10^-FiveMol), then
Preferably 1 × 10^-7~ 1 x 10^-FiveMoles (eg 5x
10^-6~ 8 × 10^-6It can be selected from the range of
Usually 5 × 10^-7~ 5 x 10^-6Mol (eg, 6 × 10^-7
~ 3 x 10^-6Mole).

However, when these acids are added, when they are sealed under high temperature and high humidity conditions and stored for a long time,
It has been found that hydrolysis of the acyl group tends to occur. The acid generated by the hydrolysis acts as a trigger to hydrolyze another acyl group, so that the hydrolysis proceeds at an accelerated rate. This is the so-called “vinegar syndrome”. As a countermeasure against this, the addition of an acid neutralizing agent is effective, but the addition of the neutralizing agent causes a dilemma that the effect of the additive A for promoting peeling is reduced. As a result of intensive studies by the present inventors, the additive A
It was clarified that this dilemma can be suppressed by adding the neutralizing agent of (1) to another layer, and the present invention has been completed.

The additive B used as the neutralizing agent will be described. What is used as the additive B is p
It was revealed that an amine compound having a Ka of 4.50 or more, or an amine compound having substantially no volatility and a molecular weight of 200 or less per basic group is particularly effective.

The amine compound of the present invention will be described in more detail. The amine compound of the present invention has a pKa of 4.50 or more, but from the viewpoint of the effect of the present invention, the pKa is preferably 4.50 or more and 9.00 or less, more preferably 5.0.
It is 0 or more and 8.00 or less. Most preferably pK
a is an amine compound in which a is 5.00 or more and 7.00 or less.

The amine compound of the present invention is preferably a lipophilic compound, and the total number of carbon atoms is preferably 8 or more, more preferably 15 or more.

Among the amine compounds of the present invention, preferred are tertiary amines represented by the following general formula (I), which are lipophilic and have a pKa of 4.50 or more.

[0042]

[Chemical 1]

In the formula, R ₁ , R ₂ and R _{3, which} may be the same or different, each represents a hydrogen atom, an aliphatic group, an aromatic group, a heterocyclic group or an amino group. At least two groups out of R ₁ , R ₂ and R ₃ may combine with each other to form a 5- to 8-membered ring, and R ₁ and R ₂ cooperate with each other to form an unsaturated group. And R ₃ may combine to form a 5- to 8-membered ring. However, R ₁ , R ₂ and R ₃ are not hydrogen atoms at the same time.

The aliphatic group referred to in the present invention is a linear, branched or cyclic alkyl group (for example, methyl, ethyl, propyl, i-propyl, t-butyl, cyclohexyl, t-).
Hexyl, t-octyl, dodecyl, hexadecyl, octadecyl, benzyl), an alkenyl group (for example, vinyl, allyl, 2-pentenyl, cyclohexenyl, hexenyl, dodecenyl, octadecenyl), an alkynyl group (for example, fropinyl, hexadecynyl), and these The group may be substituted with a substituent. The aromatic group in the present invention represents a benzene monocyclic or condensed polycyclic aryl group (eg, phenyl, naphthyl, anthranyl). These rings may have a substituent. The heterocyclic ring in the present invention is a 5- to 7-membered cyclic group containing at least one atom selected from a nitrogen atom, a sulfur atom, and an oxygen atom as a ring-constituting atom (for example, furyl, pyrrolyl, imidazolyl, pyridyl, purinyl, chromanyl). , Pyrrolidyl, and morpholinyl). The amino group in the present invention may be a simple amino group or an N-substituted amino group having a substituent. Examples of the substituent of the amino group include an aliphatic group, an aromatic group, a heterocyclic group, an acyl group, a sulfonyl group, a sulfamoyl group and a carbamoyl group. At least _{two of} R ₁ , R ₂ and R ₃ are bound together to form 5
A ~ 8-membered ring (eg, pyrrolidine ring, imidazoline ring, imidazolidine ring, pyrazolidine ring, piperazine ring, piperidine ring, morpholine ring, indoline ring, quinuclidine ring) may be formed. R ₁ and R ₂ may cooperate with each other to form an unsaturated group, and R ₃ and R ₃ may combine with each other to form a 5- to 8-membered ring (for example, a pyridine ring, a quinoline ring, a pteridine ring, or a phenanthroline ring).

Among the lipophilic compounds represented by the general formula (I), more preferable compounds have a pKa of 4.50 or more and 9.00 or less, more preferably 5.00 or more and 8.00 or less, Preferably, the compound has a pKa of 5.00 or more and 7.00 or less. Furthermore, the general formula (I)
Among the compounds represented by, more preferred are lipophilic compounds having a pKa of 4.50 or more represented by the general formula (II). Among the amine compounds represented by the general formula (II) of the present invention, the most preferable compounds are those having a molecular weight of 300 or more and having substantially no volatility.

[0046]

[Chemical 2]

Where R₁And R₂Is the same as general formula (I)
Represents the same group. R_{twenty one}~ R_{twenty five}Can be the same or different,
Hydrogen atom, aliphatic group, aromatic group, heterocyclic group, fat
Aliphatic oxy group, heterocyclic oxy group, aromatic oxy group, fat
Aliphatic thio group, aromatic thio group, heterocyclic thio group, hydroxy
Si group, halogen atom, cyano group, nitro group, substituent
Amino group, sulfonyl group, acyl group, acyl group
Xy group, sulfamoyl group, carbamoyl group, ester
Represents a group. R₁And R₂, R₁And R_{twenty five}, R₂And R _{twenty one}Or
R_{twenty one}~ R_{twenty five}Groups in the ortho position of
To form a 5- to 8-membered ring.

Of the compounds represented by the general formula (II), the pKa is more preferably 4.50 or more and 9.00 or less, still more preferably 5.00 or more and 8.00 or less, and most preferably pKa. Is 5.00 or more and 7.0
It is a compound of 0 or less.

Specific examples of preferable amine compounds include:
Paragraph number [0022] of JP-A-5-194789
Among the A-1 to A-73 shown below, one having a pKa of 4.50 or more and 9.00 or less is preferable. However, this does not limit the present invention.

The amount of the additive B to be added depends on the stability of the solution.
Range, which does not impair the transparency and transparency of the film, for example,
1 x 10 per 1 g of cellulose acylate^-9~ 3 x 1
0^-FiveMol, preferably 1 × 10^-8~ 2 x 10^-FiveMole (eg
For example, 5 × 10^-7~ 1.5 × 10^-FiveMol), more preferred
It is 1 × 10^-7~ 1 x 10^-FiveMoles (eg 5 × 10
^-6~ 8 × 10^-6Mol) range, usually,
5 x 10^-7~ 5 x 10 ^-6Mol (eg, 6 × 10^-7~ 3
× 10^-6Mole).

In the present invention, the additive is added only to a specific layer by using the co-casting method, so that the addition amount to the whole film can be secured while ensuring the addition amount enough to exert the peeling promoting effect on the solution. The point is that the amount can be suppressed and problems such as film durability deterioration and haze increase due to addition can be solved. By controlling the external and internal thicknesses using the co-casting method, the addition amount of Additive A and Additive B is 1 × 10 per 1 g of the cellulose acylate film.
It can be controlled within the range of ^{-10 to} 3 × 10 ^-6 mol.
The optimum addition amount of A and B cannot be said unconditionally, but for each additive, 1 g / g of cellulose acylate film is used.
More preferably, it is in the range of × 10 ^{-10 to} 5 × 10 ^-6 mol.

It is necessary to add the additive A and the additive B to at least one layer in the cellulose acylate film by co-casting. However, if both additives are mixed, the peeling effect disappears, so it is preferable to add both additives to different layers. In the case of two-layer co-casting, it is preferable to add the additive A to the outer layer and the additive B to the inner layer. In case of three-layer co-casting,
(1) Add additive A to the two outer layers, and add additive B to the inner layer of one layer. (2) Add additive A to the outer layer in contact with the metal support, opposite to the inner layer or the metal support. Outer layer on the side,
Alternatively, either method of adding the additive B to both layers is preferable. In the case of four-layer co-casting, the additive A is added to the outer layer in contact with the metal support, and the additive B is added from the metal support side to the third inner layer or the outer layer opposite to the metal support. Is preferred.

The cellulose acylate solution of the present invention contains
Various additives can be added in each preparation step depending on the application. These additives are plasticizers, UV inhibitors and deterioration inhibitors (eg, antioxidants, peroxide decomposers, radical inhibitors, metal deactivators), and fine particles. Specifically, the Invention Association Open Technical Report 2001-174
From the 28th line on the left side of page 5 and 16 to the 33rd line on the left side of page 20, (plasticizer), (UV inhibitor), (control agent of optical anisotropy), (fine particles) Items can be listed. These additives are
There is no particular limitation on the additive layer.

A method for producing a film using a cellulose acylate solution will be described. As the method and equipment for producing the cellulose acylate film of the present invention, the solution casting film forming method and the solution casting film forming apparatus conventionally used for the production of cellulose triacetate film are used. The dope (cellulose acylate solution) prepared from the dissolution tank (pot) is once stored in a stock tank, and the bubbles contained in the dope are removed or final preparation is performed. The dope is sent from the dope outlet to the pressurizing die through a pressurizing constant quantity gear pump that can deliver the dope with high accuracy by the number of rotations, and the dope of the casting part running endlessly from the die (slit) of the pressurizing die. The dope film (also referred to as a web), which is dry and dried, is peeled from the metal support at a peeling point which is evenly cast on the metal support and the metal support makes one round. Both ends of the obtained web are sandwiched by clips and conveyed by a tenter while keeping the width and dried, and then conveyed by rolls of a drying device to complete the drying and wound by a winder to a predetermined length. The combination of the tenter and the roll group drying device varies depending on the purpose. In the solution casting film forming method used for the silver halide photographic light-sensitive material and the functional protective film for electronic displays, in addition to the solution casting film forming device, an undercoat layer, an antistatic layer, an antihalation layer, a protective layer, etc. A coating device is often added for the surface treatment of the film.

In the present invention, the obtained cellulose acylate solution is co-cast with a plurality of cellulose acylate solutions having two or more layers on a smooth band or a drum as a metal support. For example, in the case of casting a plurality of cellulose acylate solutions, a film is formed while casting a solution containing cellulose acylate from a plurality of casting holes provided at intervals in the traveling direction of the metal support while laminating the solutions. It may be produced, and for example, the method described in JP-A No. 11-198285 can be applied. Further, there is a method of forming a film by casting a cellulose acylate solution from two casting ports, and the method described in JP-A-6-134933 can be used. In addition, JP-A-56-162
The method of casting a cellulose acylate film described in Japanese Patent No. 617, in which the flow of a high-viscosity cellulose acylate solution is wrapped with a low-viscosity cellulose acylate solution and the high- and low-viscosity cellulose acylate solutions are simultaneously extruded may be used.

By carrying out such co-casting, as mentioned above, the smoothing of the surface during drying progresses, so that a great improvement in surface condition can be expected. The thickness of each layer in the case of co-casting is not particularly limited, but it is preferable that the outer layer is thinner than the inner layer. In that case, the thickness of the outer layer is preferably 1 to 50 μm, particularly preferably 1 to 30 μm.
μm. Here, the outer 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 the completed film in the case of three or more layers. The inner layer is a band surface (drum surface) in the case of two layers. When the number of layers is three or more, the layer is inside the outer layer. Further, the cellulose acylate solution of the present invention has another functional layer (for example, an adhesive layer, a dye layer,
An antistatic layer, an antihalation layer, a UV absorbing layer, a polarizing layer, etc.) can also be cast at the same time.

For drying the dope on the metal support for producing the cellulose acylate film of the present invention, the drying temperature in the drying step is 30 to 250 ° C., especially 40 to 40 ° C.
180 ° C. is preferable, and it is described in JP-B-5-17844. Further, there is a method of positively stretching in the width direction, and in the present invention, for example, JP-A-62-115035 is used.
No. 4-152125 and 4-284111.
No. 4-298310, and No. 11-48271.
The method described in each publication of the issue can be used. The film may be stretched uniaxially or biaxially. It is preferable that the stretching ratio of the film (the ratio of the increase due to the stretching with respect to the original length) is 10 to 30%.

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

Here, in some cases, the surface treatment of the cellulose acylate film can improve the adhesion between the cellulose acylate film and each functional layer (for example, the undercoat layer and the back layer). Specific examples thereof include those described in JIII Journal of Technical Disclosure 2001-1745, page 32, left column, line 16 to page 32, right column, line 42.

Depending on the application, it is preferable to provide an antistatic layer on at least one layer of the cellulose acylate film or a hydrophilic binder layer for adhering to the polarizer. Specifically, the Invention Association Open Technical Report 2001
-1745, the 12th line from the bottom of the right side of page 32 to the 3rd line from the bottom of the left side of page 45 can be provided.

The cellulose acylate film composed of the cellulose acylate solution can be used for various purposes. Specifically, the Institute of Invention and Innovation Technical Report 2001-17
The items of "14. Use" described in the fifth and subsequent lines from the bottom on the right side of pages 45 and 45 can be mentioned.

[0062]

Examples In each example, cellulose acylate,
The chemical and physical properties of solutions and films are:
It was measured and calculated as follows.

(1) Substitution degree (%) of cellulose acylate The acetylation degree was measured by a saponification method. The dried cellulose acylate was precisely weighed, dissolved in a mixed solvent of acetone and dimethylsulfoxide (volume ratio 4: 1), added with a predetermined amount of 1N-sodium hydroxide aqueous solution, and saponified at 25 ° C. for 2 hours. did. Phenolphthalein was added as an indicator, and excess sodium hydroxide was titrated with 1N-sulfuric acid (concentration factor: F). A blank test was conducted by the same method as above. Then, the acetylation degree (%) was calculated according to the following formula. Acetylation degree (%) = (6.005 × (B−A) × F) / W In the formula, A is the amount of 1N-sulfuric acid (ml) required for titration of the sample,
B: 1N-sulfuric acid amount (ml) required for the blank test, F
Indicates a factor of 1N-sulfuric acid, and W indicates a sample mass. still,
For systems containing multiple acyl groups, the difference in their pKa was used to determine the amount of each acyl group. In addition, publicly known documents (T.Se
i, K.Ishitani, R.Suzuki, K.Ikematsu Polymer Journal 1
7 1065 (1985)).
Further, the degree of acetylation and the amount of other acyl groups obtained from these were converted into the degree of substitution in consideration of the molar molecular weight.
Further, the degree of acyl substitution at the 2-position, 3-position and 6-position of cellulose acylate can be determined by acylating cellulose acetate with an acyl group which is not used for acylation, followed by a paper by Tezuka et al. (Carbohydr. Res. 273 (1995). ) 83-91).

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

(3) Unpeeled film residue The surface of the support when the obtained film was removed from the metal support was visually observed, and the uncoated residue of the cellulose acylate film was evaluated as follows. A: No peeling residue is observed on the metal support. B: A slight peeling residue was observed on the metal support. C: A considerable amount of peeling residue was observed on the metal support. D: A large amount of peeling residue was observed on the metal support.

(4) Horizontal unevenness of film (abbreviated as unevenness) The obtained film was visually observed, and defects of the horizontal unevenness were evaluated as follows. A: No horizontal unevenness is observed in the film. B: Horizontal unevenness was slightly observed on the film. C: Horizontal unevenness was considerably observed on the film. D: A large amount of horizontal unevenness was observed on the film.

(5) Film lump (abbreviated as lump) The obtained film was visually observed, and the lump on the surface was evaluated as follows. A: No spots were found on the surface of the film. B: Some spots were found on the surface of the film. C: Significant spots were observed on the film surface. D: Unevenness was observed on the film surface, and many spots were recognized.

(6) Haze of film This was measured using a haze meter (1001DP type, manufactured by Nippon Denshoku Industries Co., Ltd.).

(7) Durability test of film A cellulose acylate film of 10 cm × 10 cm was used, under conditions of a temperature of 90 ° C. and a humidity of 100%.
It was placed in a cm stainless steel box and left for 3 days. The degree of polymerization of the film taken out was measured to calculate the degree of polymerization, and the ratio of the raw material cellulose acylate to the degree of polymerization was determined as a percentage.

Examples will be given below, but the present invention is not limited thereto. (1-1) Preparation of Cellulose Acylate Solution A cellulose acylate solution was prepared by the following two dissolution methods. The detailed solvent compositions of the present invention and comparative examples are shown in Table 1. Plasticizer A (ditrimethylolpropane tetraacetate), plasticizer B (triphenyl phosphate), UV agent a (2,4-bis- (n-octylthio) -6- (4-hydroxy-3,
5-di-tert-butylanilino) -1,3,5-triazine), UV agent b (2 (2'-hydroxy-3 ', 5
'-Di-tert-butylphenyl) -5-chlorobenzotriazole), UV agent c (2 (2'-hydroxy-
3 ', 5'-di-tert-amylphenyl) -5-chlorobenzotriazole), fine particles (silicon dioxide (particle size 2
0 nm), Mohs hardness: about 7), and 6% by mass, 6% by mass, 0.5% by mass and 0.
5% by mass, 0.5% by mass and 0.5% by mass were added. Further, depending on the layer, Additive A and Additive B were added at a specific ratio. As the liquid for forming the inner layer and the outer layer of the co-casting in the present invention, the above-mentioned cellulose acylate solution was used by changing the concentration and the solvent. Details are also shown in Table 1.

(1-1a) Cooling and Dissolving ("Cooling" in Table 1)
The cellulose acylate shown in Table 1 was gradually added to the solvent with good stirring and allowed to swell at room temperature (25 ° C.) for 3 hours. The resulting swelling mixture was slowly stirred and cooled to -30 ° C at -8 ° C / min, then the first
After cooling to the temperature shown in the table for 6 hours, + 8 ° C /
When the temperature was raised in minutes and the sol formation of the contents had progressed to some extent, stirring of the contents was started. The dope was obtained by heating to 50 ° C.

(1-1b) High-pressure and high-temperature dissolution (described as "high temperature" in Table 1) The cellulose acylate described in Table 1 was gradually added to a solvent while stirring well, and the mixture was mixed at room temperature (25 ° C). It was left to swell for 3 hours. The obtained swelling mixture was placed in a stainless steel closed container having a double structure. High-pressure steam is passed through the jacket on the outside of the container to heat it at + 8 ° C / min to 1 MPa.
Below, the temperature shown in Table 1 was maintained for 5 minutes. After that, water at 50 ° C. 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 dope thus obtained was subjected to absolute filtration accuracy of 0.0 at 50 ° C.
Filter with 1 mm filter paper (# 63 manufactured by Toyo Roshi Kaisha, Ltd.),
Further, filtration was performed with a filter paper (FH025, manufactured by Pall Ltd.) having an absolute filtration accuracy of 0.0025 mm.

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

(1-3) The resulting cellulose acylate solution and film were evaluated according to the above items. The evaluation results are shown in Table 2. The cellulose acylate film of the present invention showed no particular problems in peeling off, unevenness, spots, and haze, and durability. On the other hand, in Comparative Examples 1, 3, and 5, film peeling residue was generated, and a problem was recognized in the surface state of the obtained film, in particular, unevenness. In addition, Comparative Examples 2 and 4
Although the releasability was good, there was a problem in the surface state (transparency) of the film due to the precipitation of the additive in the liquid, and the durability was further lowered.

[0076]

[Table 1]

[0077]

[Table 2]

[0078]

[Table 3]

[0079]

[Chemical 3]

[0080]

[Chemical 4]

[0081]

[Chemical 5]

Further, these films were stretched online at 130 ° C. in both MD and TD in the range of 10% to 30% during the drying step in the film forming step. As a result, in proportion to the draw ratio, 40n
The retardation could be increased to m to 160 nm. The thus obtained cellulose acylate film contains the liquid crystal display device described in Example 1 of JP-A-10-48420 and the discotic liquid crystal molecule described in Example 1 of JP-A-9-26572. Optically anisotropic layer, alignment film coated with polyvinyl alcohol, VA shown in FIGS. 2 to 9 of JP-A-2000-154261.
Type liquid crystal display device, when used in the OCB type liquid crystal display device described in FIGS. 10 to 15 of JP-A-2000-154261, good performance was obtained. Further, JP-A-54-01
When used as the polarizing plate described in Japanese Patent No. 6575, good performance was obtained.

[0083]

[Table 4]

[0084]

EFFECTS OF THE INVENTION A method for producing a cellulose acylate film, which comprises casting two or more layers by a co-casting method, wherein the cellulose acylate is substantially composed of a non-chlorine solvent. An acid dissociation index p in an aqueous solution is dissolved in a solvent to form one or more layers.
At least one or more layers containing an additive A selected from a partial ester of a polybasic acid having a Ka of 1.93 to less than 4.50, its alkali metal salt and its alkaline earth metal salt, and not containing the additive A The solution is characterized by containing an amine compound having a pKa of 4.50 or more, or an additive B which is an amine compound having substantially no volatility and a basic group having a molecular weight of 200 or less. By the method for producing a cellulose acylate film, the peelability and surface condition of the film were improved, and a method for producing a cellulose acylate film having no problem in the durability of the film was achieved.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification symbol FI theme code (reference) B29L 7:00 B29L 7:00 F term (reference) 2H049 BA02 BA06 BB18 BB20 BB33 BC01 BC03 BC22 4F100 AB01A AH03H AH08H AJ06B AJ06C BA03 BA07 BA10A BA10C CA30B CA30C EG002 EH312 GB41 JB20B JB20C YY00B YY00C 4F205 AA01 AB19A AB20 AC05 AG01 AG03 AH73 AR20 GA07 GB02 GB26 EU560 EU0 EN026EN026EN026EN026

Claims (13)

[Claims] 1. A method for producing a cellulose acylate film, which comprises casting two or more layers by a co-casting method, wherein the cellulose acylate is dissolved in a solvent composed essentially of a non-chlorine solvent. A partial ester of a polybasic acid having an acid dissociation index pKa in the aqueous solution of 1.93 to less than 4.50 in a solution constituting one or more layers.
An amine compound having an additive A selected from the alkali metal salt and the alkaline earth metal salt and having a pKa of 4.50 or more in at least one or more solutions containing no additive A, or substantially volatile. Basic group 1 without
A method for producing a cellulose acylate film, which comprises an additive B which is an amine compound having a molecular weight of 200 or less per piece. 2. The method for producing a cellulose acylate film according to claim 1, wherein the dry film thickness of the outer layer on at least one side of the cellulose acylate film is in the range of 1 to 50 μm. 3. The cellulose acylate film has a multi-layer structure of three or more layers, and the additive A is added only to a solution forming a layer in contact with the metal support. The method for producing a cellulose acylate film according to item 1. 4. The additive A comprises a mixture of compounds selected from at least one partial ester of a polybasic acid, an alkali metal salt thereof and an alkaline earth metal salt thereof. 4. The method for producing a cellulose acylate film according to any one of 1 to 3. 5. The additive A is added in an amount of 1 × 10 ^{−9 to} 3 per 1 g of cellulose acylate contained in the solution.
The method for producing a cellulose acylate film according to any one of claims 1 to 4, wherein the amount is in the range of × 10 ^-5 mol. 6. The addition amount of the additive A is 1 × 10 ^{−10 to} 3 × 10 per 1 g of the cellulose acylate film.
^The method for producing a cellulose acylate film according to any one of claims 1 to 5, wherein the amount is in the range of ^-6 mol. 7. The additive A is an additive selected from oxalic acid, malonic acid, tartaric acid, citric acid, succinic acid, a partial ester of glutaric acid, an alkali metal salt thereof and an alkaline earth metal salt thereof, and The method for producing a cellulose acylate film according to any one of claims 1 to 6, which is a mixture thereof. 8. The amount of the additive B added is 1 × 10 ^{−9 to} 3 × 10 ⁻⁵ per 1 g of the cellulose acylate in the solution.
The method for producing a cellulose acylate film according to any one of claims 1 to 7, which is in a molar range. 9. The additive B is added in an amount of 1 × 10 ^{−10 to} 3 × 10 per 1 g of the cellulose acylate film.
^The method for producing a cellulose acylate film according to any one of claims 1 to 8, which is in a range of ^-6 mol. 10. The non-chlorinated solvent comprises a mixed solvent of at least a ketone having a solubility parameter of 19 to 21 and an ester having a solubility parameter of 19 to 21. The method for producing a cellulose acylate film according to item. 11. The non-chlorine solvent is 2 with respect to the total solvent.
Or 30 to 30% by mass of alcohol, and the mixture of the solvent and the cellulose acylate is dissolved by being exposed to the temperature of -80 to -10 ° C or 80 to 220 ° C. 1. The method for producing a cellulose acylate film according to any one of the items 1. 12. A cellulose acylate having a total acyl substitution degree of 2.75 or more and 2.90 or less and an acyl substitution degree of 6-position of 0.90 or more, and is substantially composed of cellulose acylate. The method for producing a cellulose acylate film according to any one of claims 1 to 11, wherein: 13. A polarizing plate protective film formed from the cellulose acylate film according to any one of claims 1 to 12.