KR20110128239A - Method of producing cellulose acylate film - Google Patents

Abstract

PURPOSE: A producing method of a cellulose acylate film is provided to prevent the insertion of foreign materials when producing the cellulose acylate film, and to offer the excellent optical isotropy of the cellulose acylate film to users. CONSTITUTION: A producing method of a cellulose acylate film(49) comprises the following steps: preparing a cellulose acylate solution by dissolving cellulose acylate in a solvent, and adding a compound having a recurring unit with an ester structure; flowing the cellulose acylate solution on a substrate for forming a soft film; drying the soft film, and separating the film from the supporter; and drying and returning the obtained film. The cellulose acylate solution contains 0.03-1 micromol per gram of acid derived from the compound having the recurring unit.

Description

Manufacturing method of cellulose acylate film {METHOD OF PRODUCING CELLULOSE ACYLATE FILM}

The present invention relates to a method for producing a cellulose acylate film, and more particularly, to a method for producing a cellulose acylate film by a solution casting method.

Various display films, such as a liquid crystal display, are using various polymer films, including a protective film of a polarizing plate and a viewing angle expansion film. In particular, since it is excellent in optical isotropy, the cellulose acylate film, especially the cellulose triacetate film (TAC film) is used as a polymer film.

As a manufacturing method of such an optical use polymer film, there exist a melt extrusion method, the solution casting method, etc. In the solution casting method, a polymer solution containing a polymer and a solvent (hereinafter, referred to as dope) is cast on a support that runs, to form a cast film, and then the cast film is peeled from the support and dried to produce a polymer film. Since there is no problem of thermal damage such as the melt extrusion method, the solution casting method is suitable as a method for producing a polymer film requiring high transparency and optical properties.

In preparing a dope in the solution casting method, a mixed solvent is often used. As the main solvent, dichloromethane (also referred to as methylene chloride, methylene chloride, etc.), a good solvent of TAC, is often used. Moreover, alcohol, ketones, etc. are also used together as a poor solvent. Moreover, the physical property of the film formed into a film by making an additive into dope make it a desired thing. A plasticizer is mentioned as an additive which expresses such a function. For example, triphenyl phosphate (TPP) and biphenyl diphenyl phosphate (BDP) of phosphate ester type are mentioned.

In addition, when forming a film from dope, the film formed by casting dope is dried, and volatilized solvent is collect | recovered from air. The solvent is recovered by a condensation recovery method, an adsorption recovery method, or the like. The recovered solvent is reused as a solvent for dope preparation.

However, when the recovery solvent is used as the solvent for the dope aid, the solvent (mainly an organic solvent is used) that recovers the solvent gas volatilized in the drying step of the film contains an acid component generated in the step. When a solvent containing a large amount of acid component is used as the dope preparation solvent, the acid may cause corrosion of the film forming line used in the solution film forming step. This corrosion may generate impurities of dark brown rust. If the impurities are mixed into the dope and are flexible, there is a problem that the impurities remain as foreign matter in the film.

As a method of solving this problem, Patent Literature 1 and Patent Literature 2 disclose adjusting the hydrogen ion index of the solvent of the recovered dope aid to a desired range.

In addition, as mentioned above, plasticizers, such as TPP, are added to dope. However, these plasticizers have problems from the viewpoint of process contamination, from the viewpoint of optical properties, and from the viewpoint of environmental regulatory substances, and new plasticizers are required. Patent document 3 discloses the plasticizer of the ester oligomer type which is high in optical expression, without polluting a process as a new plasticizer.

Japanese Patent No. 4175992 Japanese Patent Publication No. 2003-260303 Japanese Patent Publication No. 2009-155455

By the way, when an ester oligomer type plasticizer is added to dope, even if the hydrogen ion index of the solvent for dope adjustment is appropriate, a problem may arise that it remains as a dark brown foreign material in a film.

This invention is made | formed in view of such a situation, and an object of this invention is to provide the manufacturing method of the cellulose acylate film which can suppress generation | occurrence | production of a foreign material in a film.

MEANS TO SOLVE THE PROBLEM The present inventors earned the following knowledge as a result of earnestly researching in order to solve the said problem. Even when the hydrogen ion index in the solvent was controlled to a desired range, it was found that the iron ions imported from the cellulose acylate and the carboxylic acid remaining in the ester oligomer-based plasticizer were neutralized and condensed to generate foreign substances. MEANS TO SOLVE THE PROBLEM In order to prevent this, the present inventors discovered that it is good to control the quantity of iron ion and residual acid (carboxylic acid), and came to complete this invention.

According to one embodiment of the present invention, in the method for producing a cellulose acylate film, a step of preparing a cellulose acylate solution by dissolving cellulose acylate in a solvent and adding a compound having an ester structure of a repeating unit to the solvent; The cellulose acylate solution is casted on a support to form a cast film, and the step of peeling the cast film from the support as a film while drying, and the step of conveying while drying the film, from the compound in the cellulose acylate solution It is characterized by the presence of 0.03-1.0 micromol / g amount of derived acid, and 0.01-0.1 micromol / g amount of iron carried in cellulose acylate.

By controlling the amount of the acid derived from the compound in the solvent and the amount of iron carried from the cellulose acylate within the above-described ranges, generation of foreign matters in the film can be suppressed.

The acid value becomes higher than the initial stage when the compound having the above-described ester structure is used for several months or more after preparation or when the film is reused. Therefore, it is preferable that it is 0.4 or less as an initial value. Moreover, it is preferable that it is 0.1 or more economically.

According to another embodiment of the present invention, acetic acid is preferably present in an amount of 0.01 to 0.25 mol / g in the solvent for dissolving cellulose acylate. By setting the concentration of acetic acid in the solvent in the above-described range, foreign substances generated in the film can be reduced.

According to another embodiment of the present invention, acetic acid in the solvent is preferably derived from the reuse of the solvent volatilized from the cast film and / or the film as a solvent for dissolving cellulose acylate.

According to another embodiment of the present invention, the compound preferably has a molecular weight of 700 to 1500.

According to other embodiment of this invention, Preferably, the said solvent which melt | dissolves a cellulose acylate contains 15-25 mass% alcohol.

According to another embodiment of the present invention, the support is preferably controlled at a temperature of 10 ° C or less.

(Effects of the Invention)

According to this invention, the cellulose acylate film with little generation | occurrence | production of a foreign material can be manufactured.

1 is a schematic configuration diagram of a production line.
2 is a table showing the results of the examples.

EMBODIMENT OF THE INVENTION Hereinafter, preferred embodiment of this invention is described according to an accompanying drawing. Although this invention is demonstrated by the following preferable embodiment, a change can be made with many methods without deviating from the range of this invention, and other embodiments other than this embodiment can be used. Therefore, all changes within the scope of the present invention are included in the claims. In addition, the numerical range represented using "-" in this specification means the range containing the numerical value described before and after "-".

In the present embodiment, the amount of the acid derived from the ester oligomer in the dope cellulose acylate solution (also called dope) is 0.03 to 1.0 µmol / g, and the amount of iron introduced from the cellulose acylate is 0.01 to 0.1 µmol / g. By controlling to, the generation of foreign matter in the film is suppressed. In addition, the amount of acid is measured by the test method of the acid value of the chemical product of JISK0070.

Since the ester oligomer type plasticizer which controlled the amount of residual acid was added to dope, the cellulose acylate film which was high in optical expression property and suppressed generation | occurrence | production of a foreign material can be manufactured, without contaminating a process.

<Cellulose acylate (raw material)>

In the cellulose acylate film, the polymer as a main component is cellulose acylate. Here, "polymer as a main component" shows the polymer when it consists of a single polymer, and shows the polymer with the highest mass fraction among the polymers comprised when it consists of several polymer. As cellulose acylate, cellulose triacetate (TAC) is particularly preferable.

As a cellulose acylate used when manufacturing a cellulose acylate film, a powder and a granular thing can be used, and what pelletized can also be used. Moreover, it is preferable that the water content of cellulose acylate is 1.0 mass% or less, It is more preferable that it is 0.7 mass% or less, It is most preferable that it is 0.5 mass% or less. In addition, it is preferable that water content is 0.2 mass% or less in some cases. When the moisture content of cellulose acylate does not exist in a preferable range, it is preferable to use, after drying by heating etc.

These polymers may be used independently and may use two or more types of polymers together. As a cellulose acylate, the compound which has an acyl substituted cellulose skeleton obtained by introduce | transducing a functional group biologically or chemically from a cellulose acylate compound and cellulose as a raw material is mentioned.

Cellulose acylate is an ester of cellulose and carboxylic acid. Among the cellulose acylates, the ratio in which the hydroxyl group of cellulose is esterified with carboxylic acid, that is, the degree of substitution of acyl group (hereinafter referred to as acyl group substitution degree) satisfies all the conditions of the following formulas (I) to (III). It is more preferable to do. In the formulas (I) to (III), both A and B are acyl group substitution degrees, the acyl group in A is an acetyl group, and the acyl group in B is 3 to 22 carbon atoms.

2.5≤A + B≤3.0 (I)

0≤A≤3.0 (II)

0≤B≤2.9 ... (III)

The glucose units constituting cellulose to bind β-1,4 have hydroxyl groups liberated at 2, 3 and 6 positions. A cellulose acylate is a polymer (polymer) in which some or all of these hydroxyl groups have been esterified so that hydrogen of the hydroxyl group is substituted with an acyl group having 2 or more carbon atoms. In addition, when the esterification of one hydroxyl group in the glucose unit is 100%, the degree of substitution is 1. Therefore, in the case of cellulose acylate, the substitution degree is 3 when the 2, 3, and 6 position hydroxyl groups are each 100% esterified. .

Here, the acyl group substitution degree at the 2-position of the glucose unit is DS2, the acyl group substitution degree at the 3-position is DS3, and the acyl group substitution degree at the 6 position is DS6. It is preferable that all the acyl group substitution degree calculated | required by DS2 + DS3 + DS6 is 2.00-3.00, It is more preferable that it is 2.22-2.90, It is still more preferable that it is 2.40-2.88. Moreover, it is preferable that DS6 / (DS2 + DS3 + DS6) is 0.32 or more, It is more preferable that it is 0.322 or more, It is still more preferable that it is 0.324-0.40.

One type of acyl group may be sufficient, or two or more types may be sufficient as it. When there are two or more types of acyl groups, it is preferable that one is an acetyl group. The sum of the substitution degree by the acetyl group of the hydrogen of the hydroxyl groups of 2, 3, and 6 positions is DSA, and the sum of the substitution degree by acyl groups other than the acetyl group in 2, 3, and 6 positions is DSB. When the value of DSA + DSB is lower, it is preferable that it is 2.2-2.86, and it is especially preferable that it is 2.40-2.80. It is preferable that DSB is 1.50 or more, and it is especially preferable that it is 1.7 or more. It is preferable that at least 28% of the DSBs are substituents of the 6-position hydroxyl group, but more preferably at least 30%, still more preferably 31% or more, and particularly preferably at least 32% are substituents of the 6-position hydroxyl group. Do. Moreover, it is preferable that the value of DSA + DSB of the 6-position of a cellulose acylate is 0.75 or more, It is more preferable that it is 0.80 or more, It is especially preferable that it is 0.85 or more. By using the above cellulose acylate, dope with preferable solubility, dope with low viscosity, and good filterability can be manufactured. In particular, in the case of using a non-chlorinated organic solvent, cellulose acylate as described above is preferable.

The acyl group having 2 or more carbon atoms may be an aliphatic group or an aryl group, and is not particularly limited. For example, there may be mentioned alkylcarbonyl esters, alkenylcarbonyl esters or aromatic carbonyl esters of cellulose, aromatic alkylcarbonyl esters, and the like, which may each have a substituted group. Propionyl, butanoyl, pentanoyl, hexanoyl, octanoyl, decanoyl, dodecanoyl, tridecanoyl, tetradecanoyl, hexadecanoyl, octadecanoyl, iso-butanoyl, t -Butanoyl group, cyclohexanecarbonyl group, oleoyl group, benzoyl group, naphthylcarbonyl group, cinnamoyl group, etc. are mentioned. Among these, propionyl group, butanoyl group, dodecanoyl group, octadecanoyl group, t-butanoyl group, oleoyl group, benzoyl group, naphthylcarbonyl group, cinnamoyl group and the like are more preferable, and propionyl group and butanoyl group Particularly preferred.

The present invention is particularly effective when the cellulose acylate is a product by esterification of cellulose obtained from wood pulp. The cellulose obtained from the wood pulp has the advantage that it is easier to obtain than the cellulose obtained from cotton linter and the amount is easy to secure. However, cellulose acylate obtained by esterifying cellulose from wood pulp generally has a problem that tear strength is lower than that of cellulose acylate obtained by esterifying cellulose from cotton linter, and that the film is inferior in transport stability. When the film is produced from the cellulose acylate made of wood pulp according to the present invention, the effect of improving tear strength becomes more remarkable.

The basic principle of the method of synthesizing cellulose acylate is described in Migita Nakahiko et al., Wood Chemistry, pp. 180-190 (Kyoritsu Shotan, 1968). As a typical synthesis | combining method of a cellulose acylate, the liquid acylation method by a carboxylic anhydride-carboxylic acid monosulfate catalyst is mentioned. Specifically, first, a cellulose raw material such as cotton linter or wood pulp is pretreated with an appropriate amount of carboxylic acid such as acetic acid, and then introduced into a pre-cooled acylated mixture to be esterified, followed by complete cellulose acylate (2-position, 3-position and The sum of the acyl substitution degree at the 6 position is nearly 3.00). Acylation mixtures generally comprise carboxylic acid as a solvent, carboxylic anhydride as an esterifying agent and sulfuric acid as a catalyst. In addition, it is common to use carboxylic anhydride in an excess amount stoichiometrically than the sum total of the cellulose which reacts with this, and the moisture which exists in the system.

Next, in order to hydrolyze the excess carboxylic anhydride remaining in the system after completion of the acylation reaction, water or hydrous acetic acid is added. In addition, in order to partially neutralize the esterification catalyst, an aqueous solution containing a neutralizing agent (for example, a carbonate, acetate, hydroxide or oxide of calcium, magnesium, iron, aluminum or zinc) may be added. Further, the obtained complete cellulose acylate is saponified by maintaining at a temperature of 20 to 90 ° C in the presence of a small amount of acylation reaction catalyst (usually remaining sulfuric acid), and is changed to cellulose acylate having a desired acyl substitution degree and polymerization degree. Let's do it. When the desired cellulose acylate is obtained, the catalyst remaining in the system is neutralized completely with a neutralizing agent or the like, or a cellulose acylate solution is added to water or diluted acetic acid (or water in the cellulose acylate solution) without neutralizing the catalyst. Or dilute acetic acid) to separate the cellulose acylate, and cellulose acylate as a target can be obtained by washing and stabilizing treatment.

As for the polymerization degree of a cellulose acylate, 200-700 are preferable in a viscosity average polymerization degree. Viscosity average degree of polymerization can be measured according to the description of Uda's intrinsic viscosity method (Kadao Uda, Hideo Hideo, Textile Society, Vol. 18 No. 1, 105-120, 1962). The method of measuring the viscosity average degree of polymerization is also described in Japanese Patent Laid-Open No. 9-95538.

In this embodiment, the quantity of iron carried in from a cellulose acylate is adjusted to 0.01-0.1 micromol / g. In the final step of acylation of cellulose, acetone / water (0.2: 0.8 to 0.8: 0.2) mixed solvent is used at 30 ° C or more and 70 ° C or less, more preferably 35 ° C or more and 65 ° C or less, still more preferably 40 ° C. The amount of iron can be made into a desired range by fully stirring at 60 degreeC or less for 30 minutes or more and 3 hours or less, More preferably, 40 minutes or more and 2.5 hours or less, More preferably, 50 minutes or more and 2 hours or less. By swelling the cellulose acylate with acetone, the iron can be completely washed to the inside. This washing is preferably performed at least once and at most 5 times, more preferably at least 2 times and at most 5 times, even more preferably at least 2 times and 4 times. It is then filtered and dried to provide for dissolution. However, it is not limited to this.

<Solvent>

As a solvent for preparing dope, aromatic hydrocarbons (for example, benzene, toluene, etc.), halogenated hydrocarbons (for example, dichloromethane, chlorobenzene, etc.), alcohols (for example, methanol, ethanol, n-propanol, n-butanol, diethylene glycol, etc.), ketones (e.g. acetone, methyl ethyl ketone, etc.), esters (e.g. methyl acetate, ethyl acetate, propyl acetate, etc.) and ethers (e.g. tetrahydrofuran , Methyl cellosolve, and the like. In addition, dope means the polymer solution or dispersion liquid obtained by melt | dissolving or disperse | distributing a polymer in a solvent.

Among the halogenated hydrocarbons, halogenated hydrocarbons having 1 to 7 carbon atoms are preferably used, and dichloromethane is most preferably used. From the viewpoints of physical properties such as TAC solubility, peelability from the support of the flexible membrane, mechanical strength and optical properties of the film, it is preferable to mix one or several alcohols having 1 to 5 carbon atoms in addition to dichloromethane. As for content of alcohol, 2-25 mass% is preferable with respect to the whole solvent, More preferably, it is 15-25 mass%. Alcohols include methanol, ethanol, n-propanol, isopropanol, n-butanol and the like, but methanol, ethanol, n-butanol or a mixture thereof is preferably used.

In recent years, the solvent composition which does not use dichloromethane for the purpose of minimizing an environmental impact is also examined. In this case, ethers having 4 to 12 carbon atoms, ketones having 3 to 12 carbon atoms, esters having 3 to 12 carbon atoms, and alcohols having 1 to 12 carbon atoms are preferable, and these may be appropriately mixed. For example, a mixed solvent of methyl acetate, acetone, ethanol and n-butanol can be mentioned. These ethers, ketones, esters and alcohols may have a cyclic structure. Moreover, the compound which has two or more of functional groups of ether, ketone, ester, and alcohol (namely, -O-, -CO-, -COO-, and -OH) can also be used as a solvent.

When acetic acid is included in the solvent, the amount of acetic acid is preferably adjusted within the range of 0.01 to 0.25 mol / g.

As described later, a recovery solvent recovered when forming a film from dope can be used as a solvent. When dope containing cellulose acylate is used, acetic acid is included in the recovery solvent. Therefore, in the case of using a recovery solvent, it is preferable to adjust the amount of acetic acid in the recovery solvent within the range of 0.01 to 0.25 mol / g.

<Additive>

In the dope of this embodiment, an additive is added. Plasticizer is added as an additive. As a plasticizer, the thing obtained from the mixture containing aromatic dicarboxylic acid, aliphatic dicarboxylic acid, and diol, and a number average molecular weight 500-2000, etc. are used. Examples of the aromatic dicarboxylic acid include phthalic acid, terephthalic acid, isophthalic acid, 1,5-naphthalenedicarboxylic acid, 1,4-naphthalenedicarboxylic acid, 1,8-naphthalenedicarboxylic acid, 2,8-naphthalenedicar Acid, 2, 6- naphthalenedicarboxylic acid, etc. may be used and 2 or more types may be used. Aliphatic dicarboxylic acids are, for example, oxalic acid, malonic acid, succinic acid, maleic acid, fumaric acid, glutaric acid, adipic acid, pimeline acid, sublinic acid, azelaic acid, sebacic acid, dodecanedicarboxylic acid or 1, 4-cyclohexanedicarboxylic acid etc. are mentioned, You may use 2 or more types of aliphatic dicarboxylic acid. Examples of the diols include aliphatic diols and alkyldiols or alicyclic diols. Examples thereof include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, and 2 -Methyl-1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 2,2-dimethyl-1,3-propanediol (neopentylglycol), 2,2-diethyl-1, 3-propanediol (3,3-dimethylolpentane), 2-n-butyl-2-ethyl-1,3-propanediol (3,3-dimethylolheptane), 3-methyl-1,5-pentanediol , 1,6-hexanediol, 2,2,4-trimethyl-1,3-pentanediol, 2-ethyl-1,3-hexanediol, 2-methyl-1,8-octanediol, 1,9-nonane Diol, 1,10-decanediol, 1,12-octadecanediol, diethylene glycol, and the like, which are used together with ethylene glycol as one kind or a mixture of two or more kinds. Both ends of the polycondensation ester are used by reacting with monocarboxylic acid and being sealed or left with hydroxyl groups.

The following method can be employ | adopted as a method of adjusting the acid derived from a plasticizer to the range of 0.03-1.0 micromol / g. One method is to increase the molecular weight of the plasticizer having an ester structure. By increasing the molecular weight, the proportion of the acid at the terminal can be reduced. The molecular weight of a plasticizer can be enlarged by lengthening a polymerization reaction time.

Another method is to reduce the water present in the system in which the plasticizer is synthesized. As a method of reducing water, for example, a method of producing a compound under reduced pressure, or a method of producing a plasticizer by adding a dehydrating agent can be employed.

In addition, the method of adjusting the acid derived from a plasticizer to the range of 0.03-1.0 micromol / g is not limited to the method mentioned above.

As another additive, an ultraviolet absorber is added. For example, an oxybenzophenone type compound, a benzotriazole type compound, a salicylic acid ester type compound, a benzophenone type compound, a cyanoacrylate type compound, a nickel complex salt type compound, and other ultraviolet absorbers can be used. Particularly preferred ultraviolet absorbers are benzotriazole compounds and benzophenone compounds.

Moreover, various other additives, such as a mold release agent, a peeling accelerator, a hydrophobic agent, a fluorine-type surfactant, etc. are added to dope as needed at any stage before preparation of a dope.

<Preparation of dope>

The cellulose acylate and the solvent are mixed and stirred to swell, optionally cooled and heated to dissolve, and then filtered to obtain a dope.

In this embodiment, in order to improve the solubility of a cellulose acylate to the solvent, you may include the process of cooling and / or heating a mixture of a polymer and a solvent. When using a halogen type organic solvent as a solvent and cooling a mixture of a polymer and a solvent using a cellulose ester, it is preferable to cool the mixture to -100-10 degreeC. Moreover, it is preferable to include the process which swells at -10-39 degreeC in all processes rather than a cooling process, and includes the process heated to 0-39 degreeC in a process after cooling.

When heating the mixture of a cellulose ester and a solvent using a halogen type organic solvent as a solvent, it is preferable to include the process of melt | dissolving a cellulose ester in a solvent by one or more methods chosen from the following (a) or (b).

(a) It swells at -10-39 degreeC and the obtained mixture is heated to 0-39 degreeC.

(b) It swells at -10-39 degreeC, the obtained mixture is heated to 40-240 degreeC at 0.2-30 Mpa, and the heated mixture is cooled to 0-39 degreeC.

In addition, when cooling the mixture of a cellulose ester and a solvent using a non-halogen-type organic solvent as a solvent, it is preferable to include the process of cooling a mixture to -100--10 degreeC. Moreover, it is preferable to include the process of swelling at -10-55 degreeC in all processes rather than a cooling process, and the process of heating to 0-57 degreeC in a process after cooling.

When heating the mixture of a cellulose ester and a solvent using a non-halogen organic solvent as a solvent, it is preferable to include the process of melt | dissolving a cellulose ester in a solvent by one or more methods chosen from the following (c) or (d). .

(c) It swells at -10-55 degreeC and the obtained mixture is heated to 0-57 degreeC.

(d) It swells at -10-55 degreeC, the obtained mixture is heated to 40-240 degreeC at 0.2-30 MPa, and the heated mixture is cooled to 0-57 degreeC.

Moreover, additives, such as the plasticizer mentioned above, are added to a solvent.

<Film forming method and production line>

1 shows a production line 10 of a film using a rotating drum (also referred to as a flexible drum) as a support. The production line 10 includes a dope production line 20, a film forming line 40, a solvent recovery reuse line 60, and a solvent component adjusting device 70. The film forming line 40 includes a casting zone 41 and a drying zone 51.

The dope 21 manufactured by the dope manufacturing line 20 is supplied to the mixing tank 22. As described above, the residual acid derived from the additive (plasticizer) in the dope 21 is adjusted to an amount of 0.03-1.0 mol / g. The mixing tank 22 is provided with a stirring blade 24 which rotates in accordance with the rotation of the motor 23. As the stirring blade 24 rotates, the dope 21 becomes uniform. The dope 21 is sent to the filtration apparatus 26 by the pump 25. Impurities in the dope 21 are removed by the filtration device 26. In addition, the filtration device 26 preferably has a pore diameter (nominal pore diameter) of 1 µm or more and 50 µm or less, and more preferably 5 µm or more and 40 µm or less. The dope 21 which passed the filtration apparatus 26 is sent to the casting die 42 by constant flow volume.

In the casting zone 41, a casting die 42 and a rotating drum 43 serving as a support under the casting die 42 are disposed. The peeling roller 46, the roller 47, and the tenter dryer 48 are arrange | positioned downstream of the rotating drum 43 in this order. Instead of the rotating drum 43, a band can be used as the support.

The rotary drum 43 is rotated by a drive not shown. The temperature control device 44 is preferably connected to the rotating drum 43. The surface of the rotating drum 43 is adjusted to the desired temperature range by the temperature control device 44.

The surface temperature of the rotating drum 43 is not specifically limited. For example, when dope is gelled on the rotating drum 43 by the cooling casting method, the surface temperature is preferably adjusted to a temperature range of -50 ° C to 10 ° C. When the dope 21 containing dichloromethane as the main solvent is cast, the surface of the rotating drum 43 is preferably adjusted to a temperature range of -15 ° C to 3 ° C. Moreover, the rotational speed of the rotating drum 43 is not specifically limited, either. The rotation speed can be set within the range of 10 m / min to 200 m / min.

The dope 21 is cast on the rotating drum 43 from the casting die 42. The casting film 45 is formed on the rotating drum 43. In addition, the flexible width is not particularly limited, but may be preferably applied in the range of 1400 mm or more and 2000 mm or less. The casting film 45 is gradually dried until it has a self supporting property while being conveyed from the rotating drum 43. The flexible film 45 is peeled from the rotating drum 43 as the film 49 while being supported by the peeling roller 46. The film 49 is conveyed to the tenter type drier 48, The film 49 is dried, keeping both edges of the film 49 by the tenter type drier 48, and conveying. The film 49 can be extended in the longitudinal direction by adjusting the rotational speeds of the peeling roller 46 and the roller 47. Moreover, the tenter type dryer 48 is comprised so that it may extend | stretch in the width direction holding both edges of the film 49, and the tenter type dryer 48 can extend | stretch the film 49 in the width direction.

The film 49 which passed the tenter type dryer 48 is conveyed to the drying zone 51. A plurality of rollers 52 are installed in the drying zone 51. In the drying zone 51, the film 49 is dried while being wound and conveyed by the roller 52. After the amount of residual solvent of the film 49 falls to a desired quantity, it is wound up by the winding machine 53 in roll shape.

The solvent film volatilized from the casting film 45 and the film 49 formed of the dope 21 cast from the casting die 42 is recovered by the solvent recovery recycling line 60.

Air containing a large amount of volatilized organic solvent from the softening zone 41 is condensed and liquefied in the solvent recovery reuse line 60 to the condenser for condensation recovery. The liquid is condensed and recovered as a recovery solvent. Moreover, the air containing the volatilized solvent from the drying zone 51 is adsorbed and removed by the pretreatment activated carbon in the solvent recovery reuse line 60 by the compound which volatilized relatively large molecular weights, such as an additive. In addition, the volatile solvent contained in the air is adsorbed by the adsorption layer. The solvent adsorbed on the adsorption layer is desorbed by the desorption gas. The desorption gas is condensed and liquefied with a condenser, and the liquid is adsorbed and recovered as a recovery solvent.

The solvent recovered from the casting zone 41 is sent to a solvent treatment apparatus and separated into a purified solvent from which moisture is removed and a waste liquid. The waste liquid is disposed of. Separation of the purification solvent and the waste liquid in the solvent treatment apparatus is performed by a method of removing water by distillation separation using a difference in boiling points such as solvent and water. When forming a film from the dope 21 containing a cellulose acylate, acetic acid is contained in a collection solvent. By increasing the amount of distillation separated by distillation, a higher purity solvent can be recovered. Therefore, the amount of acetic acid in the solvent can be adjusted in the range of 0.01 to 0.25 mol / g.

The solvent recovered from the drying zone 51 is sent to an extraction tower and separated into an organic phase and an aqueous phase. At this time, the solvent can be sufficiently transferred to the organic phase by adding an alkaline solution. In addition, since the solvent becomes alkaline, the corrosion of metals such as stainless steel, which are materials of pipes and various devices, can be suppressed. Examples of the alkaline solution include sodium hydroxide (NaOH) aqueous solution, sodium carbonate (Na ₂ CO ₃ ) aqueous solution, calcium hydroxide (Ca (OH) ₂ ), calcium oxide (CaO), and the like, but are not limited thereto. The aqueous phase is extracted as waste liquid and discarded. In addition, the organic phase is fed to a dehydration apparatus, and water mixed in a small amount in the organic phase is removed to form a purification solvent.

The purification solvent is fed to the solvent component adjusting device 70. The recovered solvent is sent to the dope production line 20 after being adjusted by the solvent component adjusting device 70 to have a desired hydrogen ion concentration and water content, and reused as a solvent for dope preparation. The adjustment of the amount of acetic acid in the recovery solvent is performed in either the solvent recovery reuse line 60 or the solvent component adjustment device 70.

As mentioned above, although the manufacturing method of the functional film of this invention was demonstrated in detail, this invention is not limited to the said embodiment, You may make various improvements and changes in the range which does not deviate from the summary of this invention.

[Example]

Hereinafter, the present invention will be described in more detail with reference to specific examples of the present invention. However, it is not limited to these.

<Production of Examples 1 to 8 and Comparative Examples 1 to 3>

As a dope preparation solvent, the mixed solvent which consists of dichloromethane (85 weight%), methanol (12 weight%), and 1-butanol (3 weight%) was used. In addition, a recovery solvent was used as a solvent for dope preparation. Cellulose acetate (degree of substitution 2.84) was added to the mixed solvent as a polymer. Alcohol was added to the solvent. In addition, a plasticizer having an ester structure of the repeating unit was added to the mixed solvent.

The solvent was prepared according to Table 1 of FIG. 2 regarding the amount of acid derived from the plasticizer, the molecular weight of the plasticizer, the iron amount from the cellulose acylate, the acetic acid content in the solvent, and the alcohol ratio in the solvent.

<Evaluation method>

The produced film was evaluated by the factor of factor, solubility, and Rth. The factor used here was the number of foreign matters of the size of 100 micrometers or more existing per 1m <2> of film. (Circle), 51-100 of (circle), 101-300 of (triangle | delta), and (triangle | delta) and 301 or more of the number of foreign objects were evaluated by x.

Solubility was made into the number of days until after depositing the 20% dichloromethane solution of a plasticizer at 4 degreeC. (Circle) the days longer than 10 days, (triangle | delta) and 4 days less than 4 days were evaluated by x.

Rth means the retardation of the thickness direction at the time of creating the film of 40 micrometers in thickness. The case where retardation was 30 nm or more was made into (circle), the case where 20 nm or more and less than 30 nm was made (triangle | delta), and less than 20 nm was made into x.

<Evaluation>

As for Examples 1 to 8, at least the acid derived from the plasticizer in the cellulose acylate solution is in the range of 0.03 to 1.0 (μmol / g), and the iron introduced from the cellulose acylate is in the range of 0.01 to 0.1 (μmol / g). The above evaluation was obtained regarding solubility and Rth. In particular, the evaluation of the factor was ◎ for Example 1 in which the amount of acid derived from the plasticizer was 0.30 (μmol / g) and Example 2 in which the amount of acid derived from the plasticizer was 0.03 (μmol / g).

For Comparative Example 1, the amount of acid derived from the plasticizer was 0.01 (μmol / g). In order to make the amount of acid derived from the plasticizer 0.01 (μmol / g), it is necessary to increase the molecular weight of the plasticizer (for example, 3000 or more). Therefore, the plasticizer did not melt | dissolve in a solvent and the solubility evaluation was x.

Since the amount of the acid derived from the plasticizer about the comparative example 2 was 1.50 (micromol / g), evaluation of the factor was x. Moreover, since the quantity of iron carried in from the cellulose acylate about the comparative example 3 was 0.15 (micromol / g), evaluation of the factor was x.

From Example 5, it can understand that evaluation of a factor becomes low when there is much acetic acid content in a solvent. In addition, it can be understood from Example 6 that the evaluation of the factor is lowered when the alcohol ratio in the solvent is high. The reason for this is not clear, but it is assumed that the more polar solvent is, the easier the Fe ion and the carboxyl group are to be associated.

From Example 7, it can be understood that the solubility evaluation becomes low when the molecular weight of a plasticizer is large. In addition, from Example 8, when the molecular weight of a plasticizer is small, it can understand that evaluation of Rth becomes low. If the molecular weight is large, the solubility is considered to be low because the linkage between the plasticizer molecules is strong, and if the molecular weight is small, the evaluation of Rth is lowered because the intermolecular distance between aromatic groups advantageous for Rth expression is increased. .

10: manufacturing line 20: dope manufacturing line
21: dope 22: mixing tank
23: motor 24: stirring blade
25: pump 26: filter device
40: film forming line 41: flexible zone
42: flexible die 43: rotary drum
44: temperature control device 45: flexible film
46: peeling roller 47, 52: roller
48: tenter dryer 49: film
51: drying zone 53: winder
60: solvent recovery reuse line 70: solvent component adjusting device

Claims (6)

Dissolving cellulose acylate in a solvent and adding a compound having an ester structure of a repeating unit to the solvent to prepare a cellulose acylate solution,
Peeling the flexible film from the support as a film while forming the flexible film by drying the cellulose acylate solution on the support and drying;
As a manufacturing method of the cellulose acylate film which has the process of conveying, drying said film:
In the cellulose acylate solution, an acid derived from the compound is present in an amount of 0.03 to 1.0 µmol / g, and an iron carried in the cellulose acylate is present in an amount of 0.01 to 0.1 µmol / g. . The method of claim 1,
A method for producing a cellulose acylate film, wherein acetic acid is present in an amount of 0.01 to 0.25 mol / g in the solvent for dissolving cellulose acylate. The method of claim 2,
Acetic acid in the solvent is a solvent for dissolving cellulose acylate and is derived from the reuse of a solvent volatilized from the cast film and / or the film. The method according to any one of claims 1 to 3,
Said compound has a molecular weight of 700-1500, The manufacturing method of the cellulose acylate film characterized by the above-mentioned. The method according to any one of claims 1 to 3,
The said solvent which melt | dissolves a cellulose acylate contains 15-25 mass% alcohol, The manufacturing method of the cellulose acylate film characterized by the above-mentioned. The method according to any one of claims 1 to 3,
The support is a method for producing a cellulose acylate film, characterized in that controlled at a temperature of 10 ℃ or less.

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