JP2008265313A - Method for producing cellulose acylate film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent stain adhesion to the surface of a support. <P>SOLUTION: A dope 70 containing a cellulose acylate and a solvent is prepared. The cellulose acylate is produced from wood as a raw material. The molar equivalent of a compound or a bonded carboxylic acid group contained in the cellulose acylate in relation to the cellulose acylate is 3-15. The mass concentration of a Ca component is 0-5 ppm, and the mass concentration of an Mg component is 50-100 ppm. The dope 70 is cast on an endlessly traveling casting drum 34 to form a gelatinous cast film 40. After that, the cast film 40 is stripped off from the casting drum 34 and dried to obtain a film 51. Oxygen radicals are supplied from a drum washing machine 44 onto the surface of the casting drum 34. Organic substances on the casting drum 34 are decomposed/removed. In this way, since the production of a fatty acid calcium etc., which can be stain is suppressed, stain adhesion to the casting drum 34 can be prevented. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  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 used for an optical product such as a liquid crystal display device.

  Cellulose acylate films are used, for example, as protective films for polarizing plates, optical compensation films, and viewing angle widening films in liquid crystal display devices because of their high transparency and excellent toughness and optical isotropy. In general, a cellulose acylate film is produced by a solution casting method. With the solution casting method, a cast film is formed by casting a dope containing cellulose acylate and a solvent on a support that is run endlessly, and then the cast film is peeled off from the support. In contrast to the melt film forming method known as a film forming method, the film is dried to form a film without causing thermal damage, so that a film having high transparency can be obtained.

  By the way, in the solution casting method, if the film formation is continued, the surface of the support is contaminated. It is thought that the organic matter insoluble in the solvent in the casting film is deposited on the surface of the support. However, if the dirty support is used continuously, the casting film is removed from the support at the location where the dirt is generated. It becomes difficult to peel off the film smoothly, and in the worst case, the film cannot be removed and the film formation must be interrupted. In addition, various problems occur, such as transfer of dirt onto the surface of the casting film and causing optical unevenness of the completed film. Therefore, at the film forming site, measures are taken such as keeping the surface clean by wiping the surface of the support with a nonwoven fabric or the like periodically soaked with a solvent. However, in this method, it is necessary to reduce the film forming speed or to stop the production line once, so that a decrease in productivity is regarded as a problem. Is required.

Therefore, various methods for preventing the surface of the support from being contaminated have been studied for a long time by the solution casting method. For example, in Patent Document 1, it is assumed that the main component of dirt is a salt containing Ca and Mg components in cellulose acylate, and the occurrence of dirt is caused by using cellulose acylate having a low content of Ca and Mg components. A method of suppressing this has been proposed. Moreover, in patent document 2, it discovers that a stain | pollution | contamination is a thing produced | generated by the coupling | bonding of specific components, such as a fatty acid resulting from a cellulose acylate, and Ca, Mg component, and the compound and Ca, Mg component which can become a stain | pollution | contamination A method of using cellulose acylate having a reduced concentration has been proposed.
JP 2006-095971 A JP 2006-199029 A

  At present, with respect to the solution film forming method, improvement of productivity is desired as compared with the related art with the development of liquid crystal display devices and the like, and studies on increasing the film forming speed are being actively conducted. For this reason, it is necessary to further suppress the occurrence of contamination on the surface of the support. However, as described in Patent Documents 1 and 2, it is difficult to sufficiently prevent the occurrence of contamination only by reducing the Ca and Mg components in the cellulose acylate. Further, Patent Document 1 does not propose an effective method for increasing the film forming speed. On the other hand, in Patent Document 2, a drum casting method, that is, using a drum whose surface is cooled as a support, a casting film in which the dope is cooled and gelled in a short time to have self-supporting properties. There has been proposed a method of increasing the speed by forming. However, in the drum casting method, since the drum is rotated at a high speed, the surface of the support is more likely to become dirty than in the past.

  Then, this invention aims at provision of the method which can manufacture a cellulose acylate film, making high-speed film-forming speed | velocity and preventing generation | occurrence | production of the stain | pollution | contamination on the surface of a support body.

  The method for producing a cellulose acylate film of the present invention comprises forming a casting film by casting a dope containing cellulose acylate and a solvent from a casting die on a support that is endless running, and then from the support. In the method for producing a cellulose acylate film by peeling off a cast film and drying to form a film, the cellulose acylate is produced by an esterification reaction of cellulose obtained from wood, and is included in the cellulose acylate. The molar equivalent of the compound or bonded carboxylic acid group to cellulose acylate is in the range of 3 to 15, the mass concentration of Ca component in the cellulose acylate is 0 ppm to 5 ppm, and the mass concentration of Mg component is 50 ppm to 100 ppm. Which is generated from the casting membrane by supplying oxygen radicals to the surface of the support. And removing the organic substances adhering to the surface of the lifting body.

  The wood is preferably a conifer.

  It is preferable that the surface temperature of the support is cooled substantially uniformly within a range of −20 ° C. or more and 0 ° C. or less.

  It is preferable to supply oxygen radicals to the surface of the support after the cast film is stripped and before the dope is cast.

  The film thickness after drying is preferably 20 μm or more and 70 μm or less.

  The support is a casting drum having a peripheral surface, and the rotation speed is preferably 60 m / min or more.

  ADVANTAGE OF THE INVENTION According to this invention, a cellulose acylate film can be manufactured, making high-speed film formation speed | velocity and preventing generation | occurrence | production of the stain | pollution | contamination on the surface of a support body.

  Hereinafter, embodiments of the present invention will be described in detail. However, the form shown here is an example according to the present invention and does not limit the present invention.

[Cellulose acylate]
In the present invention, cellulose acylate obtained from wood is used as a dope raw material. Some woods consist of broad-leaved trees and conifers depending on the type of tree, but those made of softwoods are preferred to prevent the adhesion of dirt on the surface of the support. Although elucidation of the reason why coniferous trees are effective in preventing soiling compared with broadleaf trees is not sufficient, as one of the reasons, cellulose obtained from coniferous trees can be analyzed from component analysis by, for example, NMR or FT-IR method, It is presumed that since the content of fatty acid esters is small as compared with cellulose made from hardwood, the production of organic substances that can become dirty is small. In addition, coniferous trees are considered to be caused by differences in fiber shape and cellulose composition as compared with broadleaf trees. In addition, the kind of wood used as a raw material can be estimated by performing the sugar analysis which comprises the cellulose acylate made into a sample as a sample.

  In addition, as the cellulose acylate, the molar concentration of the compound contained in the cellulose acylate or the bound carboxylic acid group with respect to the cellulose acylate is 3 to 15, and the mass concentration of the Ca component in the cellulose acylate is 0 ppm or more. The mass concentration of the Mg component is 50 ppm or more and 100 ppm or less. In addition, this density | concentration means what combined the compound in a cellulose acylate, and a coupling | bonding carboxylic acid group. Thus, this invention prescribes | regulates the molar equivalent of the carboxylic acid group with respect to a cellulose acylate, and lowers | hangs the mass concentration of Ca component and makes the mass concentration of Mg component in a cellulose acylate more than Ca component. As a result, the bond between the carboxylic acid group and Ca is inhibited by Mg, and the production of fatty acid Ca or the like that can become a soil is suppressed, so that the soil is effectively prevented from adhering to the surface of the support. Here, when the upper limit value of each component in the cellulose acylate is exceeded, it is difficult to suppress the bonding between the Ca component and the fatty acid due to the Mg component, and it is impossible to prevent the adhesion of dirt. On the other hand, when the lower limit is viewed, the smaller the Ca component, the better. However, the Mg component is difficult to obtain the effect of inhibiting the binding between the fatty acid and the Ca component. For this reason, it is preferable to adjust each component while appropriately balancing the Mg component within a predetermined range, such as being closer to the upper limit value within a predetermined range.

  The bonded carboxylic acid group is a carboxyl group bonded to cellulose acylate. In addition, the molar equivalent of the compound contained in cellulose acylate or the bound carboxylic acid group to cellulose acylate is 3 or more and 15 or less means that the amount of compound or carboxyl group contained in 1 kg of cellulose acylate is 3 mmol or more and 15 mmol. Equal to a range that is

  The carboxylic acid group in the present invention can be measured according to the sodium hydrogen carbonate-sodium chloride method specified in ASTM D-1926 as a method for measuring the carboxylic acid group. The Ca and Mg components in the present invention are values determined by an analysis method such as ion chromatography, atomic absorption spectrum, ICP, ICP-MS, etc., using the target cellulose acylate as a sample.

  In order to reduce the target component contained in the cellulose acylate to a predetermined range, there are mainly two methods. (1) Adjust the conditions for producing cellulose acylate. (2) Thoroughly wash the cellulose acylate.

In the case of (1), the method for producing cellulose acylate is not particularly limited, and a known method including a sulfuric acid method can be used. Among these, it is preferable to suitably adjust the type and amount of the neutralizing agent for neutralizing the acylating agent used for esterification and the product obtained by the acylation reaction. Usually, carboxylic acid compounds are used as the acylating agent and the neutralizing agent. As the acylating agent, a carboxylic acid anhydride is generally used, and acetic anhydride is the mainstream among them. On the other hand, as the neutralizing agent, for example, carbonates such as Ca, Mg, Fe, Al, and Zn, acetates, hydroxides, oxides, and solutions thereof are used. This solution is a mixture of a desired metal and a solvent. Examples of the solvent include water, alcohol (eg, methanol, ethanol, propanol, etc.), carboxylic acid (eg, acetic acid, propionic acid, etc.), ketone (eg, acetone, ethyl methyl ketone, etc.), and the like. Therefore, for example, after esterifying the acylating agent as acetic anhydride while adjusting the amount as appropriate, at the time of neutralization, more Mg (CH ₃ COO) ₂ is used than Mg containing a Ca component, and Ca is replaced with Mg. If replaced, the desired cellulose acylate is obtained.

  In addition, a cellulose acylate for industrial use usually contains a heat-resistant stabilizer for the purpose of improving heat-resistant stability. Examples of the heat stabilizer include alkali metals (Li, K, Na, etc.), alkaline earth metals (Ca, Mg, Ba, etc.), salts thereof and compounds thereof. Therefore, if a large amount of salt containing Mg component is included as a heat stabilizer relative to the Ca component, a cellulose acylate suitable for the present invention can be obtained.

  In the case of (2), before preparing the dope, after preparing a liquefied product by dissolving cellulose acylate in a solvent, a method of performing filtration by a filtering means at least once or a method of flowing on a support. A method of filtering the dope before spreading at least once by a filtering means is suitable. The solvent for preparing the liquefied product is preferably the same as the solvent used for the dope from the viewpoint of compatibility with the dope. The solvent used for the dope will be described in detail later.

Moreover, the thing whose mass concentration of the sulfuric acid in a cellulose acylate is 0.005 ppm or more and 0.020 ppm or less is preferable. As the mass concentration of sulfuric acid in cellulose acylate is decreased, the heat resistance of the film can be improved. In addition, when sulfuric acid is contained in cellulose acylate, a free sulfonic acid group and a metal ion (for example, Ca ²⁺ ) and the like in cellulose acylate are combined to produce a gel-like impurity. This impurity can be one of the causative substances that reduce the strippability. For this reason, if the mass concentration of sulfuric acid is suppressed as described above, the generation of the impurities can be suppressed, so that the peelability can be prevented from being lowered. The sulfuric acid includes a sulfonic acid group bonded to a sulfate, a sulfonate, and a cellulose acylate.

Although the elucidation of the mechanism of the generation of gel-like impurities by sulfuric acid is not sufficient, it is presumed as follows, for example. Since a polar solvent is used for the preparation of the dope, sulfuric acid is ionized by this polar solvent to generate SO ₄ ²⁻ and HSO ₄ ⁻ . Then, in the dope, these ions are combined with the functional group of cellulose acylate which is energetically unstable to form a composite. During film formation, this complex is modified into a gel by shear stress, temperature, etc. applied to the dope. The shear stress may occur when the dope is fed into the pipe or passed through the filtration device.

  The mass concentration of sulfuric acid contained in cellulose acylate can be determined by the following method. First, cellulose acylate as a sample is burned in an oxygen atmosphere to generate sulfur gas. Here, the sulfur gas is trapped, and the sulfur is oxidized with hydrogen peroxide to generate an acid. And the amount of sulfur is calculated | required by carrying out the neutralization titration of this sulfuric acid with sodium hydroxide, and is the value calculated | required from this value and the sampled mass. Therefore, when the sampling mass is X2 and the sulfur mass is Y2, the sulfuric acid concentration in the present invention is a value obtained by {(98/32) × Y2 / X2} × 100.

  In order to reduce the mass concentration of sulfuric acid in cellulose acylate, it is effective to suitably adjust various conditions during the production process. For example, (1) the amount of sulfuric acid used as a catalyst is reduced, (2) cellulose is acylated, and then hydrolyzed, so-called bound sulfuric acid bonded to cellulose acylate is cut off, (3) after acylation The cellulose ester is washed with water, and the washing time here is longer than that of the conventional one. However, it is not limited to the methods listed here.

Further, the cellulose acylate is more preferably one in which the substitution degree of the acyl group to the hydroxyl group of cellulose satisfies all of the following formulas (1) to (3). In the formulas (1) to (3), A and B represent the substitution degree of the acyl group with respect to the hydrogen atom in the hydroxyl group of cellulose, A is the substitution degree of the acetyl group, and B is the acyl group having 3 to 22 carbon atoms. The degree of substitution of the group. In addition, it is preferable that 90 weight% or more of a cellulose acylate is 0.1-4 mm particle | grains.
(1) 2.5 ≦ A + B ≦ 3.0
(2) 0 ≦ A ≦ 3.0
(3) 0 ≦ B ≦ 2.9

  Glucose units having β-1,4 bonds constituting cellulose have free hydroxyl groups at the 2nd, 3rd and 6th positions. Cellulose acylate is a polymer obtained by esterifying some or all of these hydroxyl groups with an acyl group having 2 or more carbon atoms. The degree of acyl substitution means the ratio at which the hydroxyl groups of cellulose are esterified at each of the 2-position, 3-position and 6-position (the substitution degree is 1 in the case of 100% esterification).

  The total degree of acylation substitution, that is, the value of DS2 + DS3 + DS6 is preferably 2.00 to 3.00, more preferably 2.22 to 2.90, and particularly preferably 2.40 to 2.88. Further, the value of DS6 / (DS2 + DS3 + DS6) is preferably 0.28 or more, more preferably 0.30 or more, and particularly preferably 0.31 to 0.34. Here, DS2 is the ratio of the hydrogen of the hydroxyl group at the 2-position in the glucose unit (hereinafter referred to as the acyl substitution degree at the 2-position), and DS3 is the hydroxyl group at the 3-position in the glucose unit. This is the rate at which hydrogen is substituted by an acyl group (hereinafter referred to as the 3-position acyl substitution degree), and DS6 is the rate at which the hydrogen at the 6-position hydroxyl group is substituted by an acyl group in a glucose unit (hereinafter, (Referred to as the degree of acyl substitution at the 6-position).

  However, the acyl group used in the cellulose acylate of the present invention may be only one type, or two or more types of acyl groups may be used. When two or more kinds of acyl groups are used, it is preferable that one of them is an acetyl group. The sum of the degree of substitution of the hydroxyl groups at the 2nd, 3rd and 6th positions by acetyl groups is DSA, and the sum of the degree of substitution of the hydroxyl groups at the 2nd, 3rd and 6th positions by acyl groups other than acetyl groups When DSB is DSB, the value of DSA + DSB is preferably 2.22 to 2.90, and particularly preferably 2.40 to 2.88.

  The DSB is preferably 0.30 or more, particularly preferably 0.7 or more. Further, 20% or more of DSB is preferably a substituent at the 6-position hydroxyl group, more preferably 25% or more, further preferably 30% or more, and particularly preferably 33% or more. Further, the value of DSA + DSB at the 6-position of cellulose acylate is 0.75 or more, more preferably 0.80 or more, and particularly preferably cellulose acylate of 0.85 or more. These cellulose acylates By using, a dope with high solubility can be obtained.

  The acyl group having 2 or more carbon atoms of cellulose acylate may be an aliphatic group or an aryl group, and is not particularly limited. Examples thereof include cellulose alkylcarbonyl esters, alkenylcarbonyl esters, aromatic carbonyl esters, aromatic alkylcarbonyl esters, and the like, each of which may further have a substituted group. Preferred examples of these include propionyl group, butanoyl group, pentanoyl group, hexanoyl group, octanoyl group, decanoyl group, dodecanoyl group, tridecanoyl group, tetradecanoyl group, hexadecanoyl group, octadecanoyl group, iso-butanoyl group. , T-butanoyl group, cyclohexanecarbonyl group, oleoyl group, benzoyl group, naphthylcarbonyl group, cinnamoyl group and the like. Among these, a propionyl group, a butanoyl group, a dodecanoyl group, an octadecanoyl group, a t-butanoyl group, an oleoyl group, a benzoyl group, a naphthylcarbonyl group, a cinnamoyl group, and the like are more preferable, and a propionyl group and a butanoyl group are particularly preferable. It is.

  A solvent suitable as a raw material for the dope is preferably a solvent capable of dissolving cellulose acylate. Specifically, aromatic hydrocarbons (eg, benzene, toluene, etc.), halogenated hydrocarbons (eg, methylene chloride, chloroform, chlorobenzene, etc.), alcohols (eg, methanol, ethanol, n-propanol, n-butanol, Diethylene glycol, etc.), ketones (eg, acetone, methyl ethyl ketone, etc.), esters (eg, methyl acetate, ethyl acetate, propyl acetate, etc.) and ethers (eg, tetrahydrofuran, methyl cellosolve, etc.). In said halogenated hydrocarbon, a C1-C7 thing is preferable. In the present invention, the dope means a polymer solution or dispersion obtained by dissolving or dispersing a polymer in a solvent.

  Especially, as a solvent, a hydrophobic thing is preferable. In particular, methylene chloride is preferred from the viewpoints of solubility in the polymer and, when fine particles are used as an additive in the dope, this dispersibility is excellent. In addition, from the viewpoints of solubility of cellulose acylate, peelability between the cast film and the support, mechanical strength of the film, optical properties, etc., one kind of alcohol having 1 to 5 carbon atoms in addition to methylene chloride, or It is preferable to mix several types. The content of alcohol is preferably 2 to 25% by weight, more preferably 5 to 20% by weight, based on the entire solvent. Examples of the alcohol include methanol, ethanol, n-propanol, isopropanol, and n-butanol. Among these, methanol, ethanol, n-butanol, or a mixture thereof is preferable.

  Recently, a solvent composition that does not use methylene chloride has also been proposed to minimize environmental impact. For this purpose, ethers having 4 to 12 carbon atoms, ketones having 3 to 12 carbon atoms, and esters having 3 to 12 carbon atoms are preferable, and these are used by being appropriately mixed. These ethers, ketones, and esters may have a cyclic structure, and two or more functional groups of ethers, ketones, and esters (that is, —O—, —CO—, and —COO—) may be used. You may have. Moreover, you may have another functional group like an alcoholic hydroxyl group. In addition, when it has two or more types of functional groups, the carbon atom number should just be in the prescription | regulation range in the case of having any functional group, and it does not specifically limit.

〔Additive〕
An additive may be added to the dope depending on the application. Examples of the additive include plasticizers, deterioration inhibitors, ultraviolet absorbers, optical anisotropy control agents, retardation control agents, matting agents such as dyes and fine particles, release agents, release accelerators, and the like. These additives are not particularly limited, and those known as various additives may be used.

  It is preferable to add fine particles to the dope for the purpose of preventing adhesion between films. As the fine particles, silicon dioxide derivatives are suitable. The silicon dioxide derivative in the present invention includes silicon dioxide and a silicone resin having a three-dimensional network structure. In addition, the surface is preferably subjected to alkylation treatment. When fine particles that have been subjected to a hydrophobic treatment such as an alkylation treatment are used, dispersibility in a solvent is improved.

  When the surface of the fine particles is subjected to an alkylation treatment, the alkyl group introduced to the surface of the fine particles preferably has 1 to 20 carbon atoms. More preferably, the alkyl group to be introduced has 1 to 12 carbon atoms, and particularly preferably 1 to 8 carbon atoms. The fine particles into which such an alkyl group is introduced suppresses aggregation between the fine particles and improves dispersibility. Examples of the fine particles having an alkyl group having 1 to 20 carbon atoms on the surface include those obtained by treating fine particles of silicon dioxide with octylsilane. In addition, as an example of the silicon dioxide derivative which has an octyl group on the surface, it is marketed with the brand name of Aerosil R805 (made by Nippon Aerosil Co., Ltd.), and can be used conveniently in this invention.

  The fine particle content is preferably 0.2% or less with respect to the solid content of the dope. Thus, since the dope in which the content of the fine particles is controlled suppresses aggregation of the fine particles, a film having high transparency and excellent optical characteristics can be produced. The fine particles preferably have an average particle size of 1.0 μm or less in order to suppress high transparency of the film, optical characteristics, or aggregation of the fine particles. More preferably, it is 0.3-1.0 micrometer, Most preferably, it is 0.4-0.8 micrometer.

  Details of the cellulose acylate other than the features of the present invention are described in paragraphs [0140] to [0195] of JP-A-2005-104148, and these descriptions can also be applied to the present invention. The solvent and various additives are also described in detail in paragraphs [0196] to [0516] of JP-A-2005-104148, and these descriptions can also be applied to the present invention.

  Next, the film manufacturing method according to the present invention will be described. However, this embodiment is an example according to the present invention and does not limit the present invention.

  As shown in FIG. 1, the film manufacturing equipment 10 used in the present embodiment includes a casting chamber 12, a crossing portion 13, a tenter 14, a drying chamber 15, a cooling chamber 16, and a winding chamber 17. It is configured.

  The casting chamber 12 includes a casting die 31 to which a feed block 30 is attached, a decompression chamber 32, a heat transfer medium circulation device 33, a casting drum 34, a condenser 35, a stripping roller 36, and the like. In addition, a temperature control facility 37 is attached to the outside of the casting chamber 12 so that the internal temperature of the casting chamber 12 is kept substantially constant within a predetermined range.

  The feed block 30 is connected to the stock tank 60 via the pipes L1 to L3, and joins the dope that is appropriately fed into a desired arrangement according to the layer structure of the casting film. Among the pipes, the pipe L1 is a base layer dope for forming a base layer, L2 is a support layer dope, and L3 is a surface layer dope channel. Here, the base layer is a layer that exists farthest from the support when it becomes a cast film and exists between the surface layer and the casting drum 34 that is the support when facing the air. Is a layer that is in contact with the base layer and the casting drum 34. The dope in the present invention is a mixed solution containing a solid content composed of a polymer or an additive and a solvent. The dope casting and its preparation will be described in detail later.

  The casting die 31 is provided with a dope discharge port, and this discharge port is installed in a state of opening toward the casting drum 34. The casting die 31 is provided with a solvent supply device (not shown) at both ends of the discharge port. This solvent supply device supplies a solvent for solubilizing the dope to both ends of the casting bead formed between the discharge port and the casting drum 34 and the gas-liquid interface between the discharge port and the outside air. Examples of the solvent include a mixed solvent of 86.5 parts by weight of dichloromethane, 13 parts by weight of methanol, and 0.5 parts by weight of n-butanol. When supplying the solvent, it is preferable to use a pump having a pulsation rate of 5% or less. Thereby, while casting the dope from the discharge port, it is possible to suppress the local drying of the dope and form a stable casting bead. Although the supply amount of the solvent is not particularly limited, the supply amount for each side of the discharge port end portion is suppressed in order to suppress the drying of the dope and prevent foreign matters such as the solidified product of the dope from entering the casting film 40. It is preferable that it is 0.1-1.0 mL / min.

  The decompression chamber 32 is connected to a decompression device (not shown), and decompresses the back surface of the casting bead while adjusting the degree of decompression. The degree of pressure reduction on the back surface of the casting bead is preferably (atmospheric pressure −2000 Pa) or more and (atmospheric pressure −10) Pa or less.

  The casting drum 34 is rotated endlessly about the axis of the cylinder by a driving device (not shown). The casting drum 34 has a cylindrical shape or a columnar shape, and the surface thereof is plated with chromium for the purpose of imparting sufficient corrosion resistance and strength. A flow path for the heat transfer medium is formed inside the casting drum 34. The heat transfer medium is supplied from a heat transfer medium circulation device 33 attached to the casting drum 34. The surface temperature of the casting drum 34 is maintained at a desired temperature by circulating or passing the heat transfer medium through the flow path. From the viewpoint of corrosion resistance and heat resistance, the material is preferably made of metal. Among these, a metal drum made of stainless steel and made of SUS316 is preferable. In the present invention, a casting band that is stretched around a rotating roller and moves endlessly may be used as a support instead of the casting drum 34.

Regardless of the drum and band and their form, the width of the support is preferably in the range of 1.05 to 1.5 times the casting width of the dope. In order to form a casting film having excellent flatness, the peripheral surface of the casting drum 34 is preferably polished so that the surface roughness is 0.05 μm or less, and the surface defects are minimized. Suppressed ones are preferred. Specifically, it is preferable that there are no pinholes of 30 μm or more, pinholes of 10 μm or more and less than 30 μm are 1 / m ² or less, and pinholes of less than 10 μm are 2 / m ² or less.

  The condenser 35 condenses and liquefies the gas containing the organic solvent volatilized from the dope or the casting film 40. The recovery device 39 recovers the condensed and liquefied solvent. The recovered solvent is regenerated by a regenerator (not shown) and reused as a dope preparation solvent. The stripping roller 36 supports the casting film 40 when the casting film 40 is stripped from the casting drum 34. Here, the casting film 40 is peeled off from the casting drum 34 to form a wet film 41 containing a solvent.

  In the vicinity of the surface of the casting drum 34 between the decompression chamber 32 and the peeling roller 36, a drum washer 44 is installed. The drum cleaner 44 is connected to a plasma generator 46 installed outside the casting chamber 12. The plasma generator 46 includes a gas filling chamber and a timer (not shown). The gas filling chamber is filled with a predetermined gas containing oxygen, and stores an electrode pair therein. The timer is for generating and supplying oxygen radicals for a predetermined time. In the gas filling chamber, a predetermined voltage is applied between the electrodes to generate oxygen radicals from oxygen molecules contained in the filled gas.

  Oxygen radicals generated by the plasma generator 46 are supplied to the surface of the casting drum 34 after being sent to the drum cleaner 44 via the pipe 46a. Oxygen radicals that have reached the surface of the casting drum 34 react with organic substances adhering to the surface, and decompose these organic substances into low-molecular compounds and the like. Thereby, the effect which removes and wash | cleans the organic substance adhering to the surface of the casting drum 34 is acquired.

  The crossover part 13 is composed of a plurality of rollers and a blower device 13a, and while the wet film 41 is supported and transported by each roller, drying air is supplied from the blower device 13a to promote drying of the wet film 41. Let

  The tenter 14 is provided with a pin plate having a plurality of pins therein and a drying device (both not shown) for supplying drying air, and each pin is inserted and held at both end portions of the wet film 41. Then, during the conveyance, drying of the wet film 41 is further promoted to obtain the film 51.

  On the downstream side of the tenter 14, an ear clip device 47 equipped with a cutter is installed. Both end portions of the film 51 are cut by the edge cutting device 47. Further, the crusher 48 connected to the ear clip device 47 crushes the cut piece of the film 51 into chips.

  The drying chamber 15 is provided with a large number of rollers 50 and a blower (not shown) for supplying drying air, where the film 51 is sufficiently dried. An adsorption recovery device 52 that recovers the solvent gas in the drying chamber 15 is connected to the outside of the drying chamber 15.

  The cooling chamber 16 provided in the drying chamber 15 cools the film 51 heated in the drying chamber 15 to approximately room temperature. The method for cooling the film 51 is not particularly limited, and the film 51 may be naturally cooled by being left in a room at approximately room temperature, or may be cooled artificially by supplying cold heat or cooling air. A forced static elimination device 53 for adjusting the charged voltage of the film 51 is installed downstream of the cooling chamber 16. Further, in the present embodiment, a knurling application roller 54 for applying knurling to the film 51 is provided on the downstream side of the forced static elimination device 53. Inside the winding chamber 17, a winding device 55 for winding the film 51 and a press roller 56 for applying pressure to the film 51 are provided.

  The stock tank 60 is provided with a jacket 61 and a stirrer 63 that is rotated by a motor 62. The stock tank 60 agitates the stored dope 70 by allowing a heat transfer medium whose temperature is adjusted to pass through the jacket 61 to keep the internal temperature substantially constant within a predetermined range and rotating the stirrer 63 constantly. And maintaining a uniform state while suppressing the aggregation of foreign matter.

  Tanks 71 to 73 are connected to the pipes L1 to L3, and static mixers 77 to 79 and filtration devices 80 to 82 are attached downstream of the connection points of the tanks 71 to 73.

  In the tanks 71 to 73, additive solutions 71a to 73a obtained by mixing an additive and a solvent in advance are placed. The additive solutions 71a to 73a are sent to the dope 70 that flows through the pipes L1 to L3 with the liquid feeding amount adjusted by the pumps P1 to P3. As the additive, those appropriately selected according to the desired film properties are used, and examples thereof include a plasticizer, an ultraviolet absorber, a release agent, a release accelerator, and a fluorine-based surfactant. Although the above-mentioned solvent is not particularly limited, the same solvent as used for preparing the dope is preferable from the viewpoint of compatibility with the dope 70. Here, the viscosity and the like of the dope 70 can be suitably controlled by adjusting the amount of the solvent. The method of adding the additive into the dope 70 is not particularly limited. For example, when a solid additive is used, the dope 70 may be put into the dope flowing in the pipe with a hopper or liquid at room temperature. In the case of using the additive, it may be added as it is without using a solvent.

  The static mixers 77 to 79 stir and mix the dope 70 containing the additive solution. As the static mixers 77 to 79, for the purpose of efficiently and effectively dispersing the additive solution in the dope 70, those having an element in which a rectangular plate is twisted are suitable. If the stirring speed and residence time are adjusted here, the mixing condition of dope 70 and an additive solution can be controlled suitably, and if the mixing condition is controlled, the viscosity of dope 70 can be adjusted appropriately. However, the shape and structure of the static mixer are not particularly limited. For example, it is conceivable to use a slewer mixer having elements formed by combining a plurality of strip-shaped plates in a lattice pattern. . In this embodiment, the same shape is used for all, but the same shape is not necessarily used. Moreover, the filtration apparatuses 80-82 remove a foreign material by filtering dope.

  Next, the effect | action of said film manufacturing equipment 10 is demonstrated. In addition, since the procedure for preparing the dope in each of the pipes L1 to L3 is the same, in the following description, the procedure for preparing the base layer dope in the pipe L1 will be described as a representative.

  In the stock tank 60, a heat transfer medium is caused to flow inside the jacket 61 and the temperature of the dope 70 is adjusted to 25 to 35 ° C. The stirrer 63 is always turned to maintain the quality of the dope 70. After the opening and closing of the four-way valve 84 is adjusted and the stock tank 60 and the pipe L1 are connected, an appropriate amount of dope 70 is sent from the stock tank 60 into the pipe L1. Here, the flow rate of the dope 20 is adjusted by the pump P4.

  The additive solution 72a is sent from the additive tank 72 to the dope 70 flowing through the pipe L1 by the pump P2. Thereafter, the dope 70 is stirred and uniformed by the static mixer 78, and then the foreign matter in the dope 70 is removed by the filtering device 81. In addition, it is preferable that the additive concentration in each dope finally subjected to casting is 1 to 20 wt% with respect to the entire solid content in the dope 70.

  Three kinds of dopes of a surface layer dope, a base layer dope, and a support layer dope are sent into the feed block 30 through the pipes L1 to L3. After the dopes merge at the feed block 31, the dopes are sent to the casting die 31 while maintaining the three-layer state, and then co-cast on the casting drum 34 from the discharge port of the casting die 31. The surface of the casting drum 34 is held so as to be substantially constant in the range of −20 ° C. to 0 ° C. The dope that has reached the surface of the casting drum 34 is quickly cooled, and a gel-like casting film 40 is formed within a short time. As the casting film 40 stays on the casting drum 34, the cooling progresses and the gelation of the casting film 40 progresses. If the casting drum 34 whose surface is cooled in this way is used as a support, the casting film 40 having self-supporting properties can be formed in a short time, and therefore the production speed can be improved.

  The rotation speed of the continuously rotating casting drum 34 is preferably maintained at 60 m / min or more. Thereby, it is possible to form a casting bead having a stable shape without reducing the production rate, and to obtain a casting film 40 having excellent flatness. As the rotational speed is increased, there is a concern that accompanying wind is generated around the casting drum 34 or the casting drum 34 itself vibrates. For this reason, the rotational speed is appropriately adjusted according to the state of the casting drum 34. The rotation speed of the casting drum 34 is more preferably in the range of 60 m / min to 150 m / min. The rotational speed of the casting drum 34 is a moving speed at an arbitrary point on the peripheral surface where the dope is cast. When a casting band is used as the support, the rotational speed is equal to the traveling speed of the casting band. The stability of the support during high-speed rotation is superior to that of the casting band. The casting drum as in this embodiment is stable at a rotational speed of 60 m / min or more. Thus, the casting film 40 can be formed. Then, the casting drum 34 is continuously rotated to repeat the casting and stripping of the dope. Further, the internal temperature of the casting chamber 12 is kept substantially constant by the temperature control equipment 37 in the range of 10 ° C. to 30 ° C.

  The casting film 40 having the self-supporting property is peeled off from the casting drum 34 while being supported by the peeling roller 36 to form a wet film 41. In the present invention, since cellulose acylate containing wood as a dope material and containing a specific component in a predetermined range is used as a dope material, the adhesion of dirt on the surface of the casting drum 34 is prevented. In the case where a multi-layer casting film is formed as in this embodiment, the above cellulose acylate is used in at least the dope contacting the casting drum 34 as a support.

  The wet film 41 containing a large amount of the solvent is sent to the tenter 14 after drying is promoted in the transfer section 13. In the tenter 14, drying is performed while the pins are inserted and held at both end portions of the wet film 41 to form the film 51. Here, tension can be applied to the width direction of the wet film 41 by adjusting the interval between the pins facing each other. By appropriately adjusting the magnitude of this tension, the molecular orientation of the wet film 41 can be suitably controlled, and as a result, a desired retardation value can be expressed in the film.

  In the present invention, for the purpose of imparting optical properties to the film, a clip tenter may be installed as necessary. The clip tenter means a stretching dryer provided with a large number of clips as a gripping means for the wet film 41 and a drying device. Tension is applied in the width direction of the wet film by expanding and contracting the interval. Regardless of the form of the gripping means such as pins and clips, tension can be applied in the transport direction of the wet film 41 by adjusting the transport speed of the wet film 41 and the spacing of the grip means in the transport direction in the tenter. Therefore, it is possible to adjust the retardation value more preferably by controlling the molecular orientation in the transport direction. In addition, when using a pin tenter and a clip tenter together, it is not necessary to use each device continuously. For example, after winding a wet film that has been dried with a pin tenter into a roll, the roll film May be used for a clip tenter to continue the subsequent steps.

  The film 51 is cut at both ends by the ear-cutting device 47 to remove pin puncture scratches and the like. The cut pieces are sent to the crusher 48 and crushed into chips. In addition, since this chip can be reused as the raw material of the film, the raw material cost can be reduced.

  In the drying chamber 15, the film surface temperature of the film 51 that is wound around and conveyed by each roller 50 is heated to 60 to 145 ° C. to sufficiently advance the drying of the film 51. The film surface temperature can be measured by providing a thermometer such as an infrared sensor near the conveyance path of the film 51. After the film 51 exiting the drying chamber 15 is cooled to approximately room temperature in the cooling chamber 16, the charged voltage is adjusted to a predetermined range (for example, −3 kV to +3 kV) by the forced static elimination device 53, and the knurling roller 54 Gives a knurling.

  The film 51 sent to the take-up chamber 17 is taken up by the take-up device 55 while being pressed by the press roller 56 in the center direction. As a result, a roll-shaped film having no surface wrinkles or twists and having a good surface shape is produced. The film 51 to be wound is preferably at least 100 m or more in the transport direction, and the width direction is preferably 1400 to 2500 mm. However, the present invention can also be effective when the width direction is larger than 2500 mm. The thickness of the film 51 after drying is preferably 20 μm or more and 70 μm. As described above, the present invention also exhibits an excellent effect when manufacturing a thin film having a wide width.

  In the present embodiment, in order to prevent dirt from adhering to the surface of the casting drum 34 or to remove the adhered dirt, the casting drum 34 is washed by the drum washing machine 44. As shown in FIG. 2, the drum cleaner 44 includes a nozzle 44a attached to the tip of a pipe 46a, a cover 44b covering the outer periphery of the nozzle 44a, and the like. A supply port 44c opened to the casting drum 34 is formed at the tip of the nozzle 44a. The nozzle 44a is connected to a shift unit that can freely adjust the position of the nozzle 44a, and the distance L1 between the supply port 44c and the casting drum 34 is suitably adjusted.

  If necessary, oxygen radicals are sent from the plasma generator 46 into the pipe 46a for a time determined by the operation of the timer, and oxygen radicals are further supplied from the supply port 44c to the surface of the casting drum 34. Is done. In order to remove organic substances effectively, oxygen radicals are removed from the surface of the casting drum 34 after the casting film 40 is peeled off from the casting drum 34 and before the dope 70 is cast again. It is preferable to supply. Note that the supply of oxygen radicals may be always (continuous) or intermittent. However, if it is always performed, an effect of suppressing the growth of organic matter can be obtained.

Oxygen radicals react with organic substances attached to the surface of the casting drum 34. Organic substances mainly composed of fatty acid esters or the like are decomposed into CO ₂ , CO, H ₂ O, low molecular compounds, etc., and are efficiently removed. In addition to fatty acid esters, organic substances such as fatty acids and metal fatty acid salts are also efficiently decomposed by oxygen radicals. The substance generated by the oxygen radical is recovered by the condenser 35 together with the organic solvent gas present in the casting chamber 12. On the other hand, since the low molecular weight compound dissolves in the dope 70 on the casting drum 34 and becomes a new casting film 40, the quality of the film is not adversely affected. The oxygen molecules that generate oxygen radicals may be either floating in the casting chamber or supplied from outside the casting chamber.

  The organic substance decomposition effect due to the supply of oxygen radicals includes the supply distance L1 between the surface of the casting drum 34 and the supply port 44c of the nozzle 44a, the angle θ1 between the direction of supplying oxygen plasma and the surface of the casting drum 34, and the supply. Depends on time etc. In the present invention, the distance L1 is preferably 2 mm or more and 15 mm or less, and more preferably 2 mm or more and 5 mm or less. Here, when L1 is less than 2 mm, the casting drum 34 may be damaged by bringing the nozzle 44a closer to the casting drum 34. Furthermore, if the nozzle 44a of high temperature (250 degreeC-350 degreeC) is made to approach the casting drum 34, the temperature of the casting drum 34 will rise, and it originates in deterioration of the drum surface by thermal history, and the temperature difference on a drum. There is concern about changes in film thickness. On the other hand, when the distance L1 is greater than 15 mm, oxygen radicals are not sufficiently supplied to the surface of the casting drum 34, and thus the effect of decomposing the fatty acid ester by the oxygen radicals is not sufficiently exhibited.

  The angle θ1 formed between the direction in which the oxygen plasma is supplied and the surface of the casting drum 34 is preferably 30 ° to 150 °, more preferably 45 ° to 135 °, and most preferably 85 ° to 95 °. It is as follows. In particular, oxygen radicals can be supplied to the surface of the casting drum 34 as the angle θ1 is made closer to a right angle. The supply time for supplying oxygen radicals to the surface of the casting drum 34 is preferably 0.025 seconds or more and 0.05 seconds or less, more preferably 0.375 seconds or more and 0.05 seconds or less. When the supply time is 0.025 seconds, the fatty acid ester decomposition effect of the casting drum 34 is partially observed. On the other hand, a supply time of 0.05 seconds is sufficient to decompose all the fatty acid esters on the surface of the casting drum 34.

  In the above embodiment, the oxygen radical is generated by the plasma generator 46 installed outside the casting chamber 12. However, the present invention is not limited to this, and oxygen molecules floating in the casting chamber 12 are used. Even if oxygen radicals are generated and supplied to the surface of the casting drum 34, the same effect can be obtained. Further, it is preferable to attach a suction pipe to the cover 44b constituting the drum washer 44 and suck the air in the vicinity of the supply port 44c because the low-molecular compounds and the like generated by the decomposition of organic substances can be effectively recovered.

  If the method of cleaning the casting drum 34 using oxygen radicals as in the present invention is used, organic substances can be removed without leaving a cleaning mark on the surface of the casting drum 34 as compared with cleaning means such as a nonwoven fabric. The risk of damaging the surface of the casting drum 34 is also reduced. Further, if the drum washer 44 is installed between the decompression chamber 32 and the peeling roller 36 and in the vicinity of the surface of the casting drum 34, the film can be washed without stopping.

  The drum cleaning machine according to the present invention is preferably a contact type with respect to the casting drum, and can supply oxygen radicals uniformly to the casting drum in the width direction. As a suitable example, the thing which has a supply port substantially equivalent to the width direction full length of a support body is mentioned, for example. Moreover, in the said embodiment, although what was called online form which removes the organic substance on the surface of a casting drum in a film manufacturing facility was described, what is called offline which performs the same removal process on the surface of the casting drum taken out from the film manufacturing facility. Organic matter may be removed in the form.

  Further, the number of installed drum washing machines is not particularly limited, and one or more machines may be used. When using multiple drum washers, these may be juxtaposed in the width direction of the casting drum, or the place where organic substances are expected to adhere is specified by casting the dope on a small scale in advance. In addition, the target may be set at random and set at random. In the case of a single machine, it is preferable to use a scanning type washing machine capable of traveling over the entire drum width. Thereby, organic substances can be removed over a wide area. Note that the effect of the present invention is exhibited even when a casting band that runs around an endlessly wound on a rotating roller is used as a support that replaces the casting drum.

  In the present invention, the effect can be obtained whether the target film is a single layer or a multilayer. In the case of forming a film having a multilayer structure, in this embodiment, a co-casting form in which a plurality of dopes are cast at the same time is shown, but there is no particular limitation. For example, a plurality of dopes are sequentially flowed on a support. The method of extending may be sufficient and you may combine these methods. When sequentially casting a plurality of dopes on a support, a casting die having a feed block having a desired flow path may be used, or a multi-manifold casting die may be used. Also good. In this case, when forming a multilayer film by co-casting, it is preferable that at least one of the thickness of the surface layer and the thickness of the support layer be 0.5 to 30% of the total thickness of the film. . Moreover, when casting dope simultaneously, when casting a dope on a support body from a die slit, it is preferable that a high viscosity dope wraps with a low viscosity dope. Furthermore, it is preferable that the composition ratio of alcohol in the dope in contact with the outside of the casting bead formed from the die slit to the support is larger than that in the dope inside.

  Among the film production equipment according to the present invention, the structure of casting die, decompression chamber, support, etc., co-casting, peeling method, stretching, drying conditions of each process, handling method, curling, winding after flatness correction From method to solvent recovery method and film recovery method are described in detail in paragraphs [0617] to [0889] of JP-A-2005-104148, and these descriptions can also be applied to the present invention.

  Next, the preparation method of the dope concerning this invention is demonstrated concretely. As shown in FIG. 3, the dope manufacturing facility 100 used in the present embodiment includes a solvent tank 101, a hopper 102, an additive tank 103, a mixing tank 105, a heating device 106, a temperature control device 107, It comprises a filtration device 109, a flash device 110, and the like. The dope manufacturing facility 100 is connected to the film manufacturing facility 10 via a stock tank 60.

  The solvent tank 101 contains a solvent that acts as a solvent for the dope. In this embodiment, a mixture of dichloromethane and methanol in a predetermined ratio is added. In the case of using a plurality of solvents, a tank may be prepared according to the type of the desired solvent without using a mixture, and sent to the mixing tank as appropriate. The hopper 102 contains a polymer that is a raw material of the film, and in this embodiment, TAC is contained. In the additive tank 103, an additive selected according to a desired function to be applied to the film is placed. As described above, this additive is an additive commonly used for the base layer dope, the support layer dope, and the surface layer dope.

  The mixing tank 105 includes a jacket 110 provided so as to wrap around the outer surface of the mixing tank 105, a first stirrer 112, a second stirrer 113, and the like. The internal temperature of the mixing tank 105 is kept substantially constant within a predetermined range by allowing the heat transfer medium whose temperature is adjusted to pass through the jacket 110. The first stirrer 112 and the second stirrer 113 are respectively rotated by the motors 115 and 116 to stir the dope raw material. Thereby, the liquid mixture 120 is produced in the mixing tank 105. The first stirrer 112 is preferably an anchor blade, and the second stirrer 113 is preferably a dissolver type eccentric stirrer. If different types of stirrers are appropriately selected as described above, the dope raw material can be efficiently and effectively stirred.

  As the heating device 106, a jacketed pipe capable of temperature control is suitably used, and the mixed liquid 120 is heated in a predetermined temperature range to dissolve a solid content such as a polymer in a solvent. The heating temperature of the mixed liquid 120 by the heating device 106 is 0 to 97 ° C. In order to improve the solubility, the heating device 106 is preferably provided with a pressurizing means. Thereby, solubility can be improved, reducing a thermal damage. In the present invention, the heating by the heating device 106 does not mean that the mixed liquid 120 is heated to a temperature equal to or higher than room temperature, but means that the temperature of the mixed liquid 120 is increased. For example, when the temperature of the mixed liquid 120 when it is sent to the heating device 106 is −7 ° C., it is heating to 0 ° C.

  In order to improve the solubility of the mixed liquid 120, cooling dissolution may be used instead of the above-described heating dissolution. The cooling dissolution is to improve the solubility by cooling the mixed liquid 120 to −100 to −10 ° C. Note that the solubility of the mixed liquid 120 can be suitably controlled by appropriately selecting the heat dissolution and the cooling dissolution according to the dope raw material and the like. The temperature control device 107 is provided with a temperature control function, and the mixed liquid 120 is set to approximately room temperature to form the dope 70. In this embodiment, the liquid after exiting the temperature control device 107 is referred to as a dope 70.

  A porous filter is provided inside the filtering device 109, and foreign substances are removed by allowing the dope 70 to pass through the filter. The filter is not particularly limited, but a filter having an average pore diameter of 100 μm or less is preferable for efficient and effective filtration. Further, in order to efficiently remove foreign matters without prolonging the filtration time, it is preferable to set the filtration flow rate of the dope 70 by the filtration device 109 to 50 L / hour or more. The filtration device 113 installed downstream of the flash tank 110 has the same shape as described above. The filtration conditions of each filtration device are the same.

  Each member constituting the dope manufacturing facility 100 is connected by a stainless steel pipe because of advantages such as excellent corrosion resistance and heat resistance. Moreover, pumps P5 and P6 and valves V1 and V2 are arbitrarily attached to each pipe, and the flow rate of the raw material dope etc. sent into the pipe is adjusted as appropriate. In addition, the number of pumps and valves installed in the dope manufacturing facility 100 and the installation locations are not particularly limited, and may be appropriately selected and used.

  Next, the effect | action of said dope manufacturing equipment 100 is demonstrated.

  An appropriate amount of solvent, TAC, is appropriately sent from the solvent tank 101 and the hopper 102 into the mixing tank 105. The order of sending the solvent and TAC is not limited, and the order of TAC and solvent may be used, or they may be sent simultaneously. Further, an appropriate amount of additive is appropriately sent from the additive tank 103 into the mixing tank 105. In the mixing tank 105, the first stirrer 112 and the second stirrer 113 are rotated to stir the solvent, TAC, and additive. As a result, a mixed liquid 120 in which various dope raw materials are mixed is prepared. In addition, the mixing tank 105 flows the heat-transfer medium which adjusted temperature inside the jacket 110, and hold | maintains substantially constant in the range of -10-55 degreeC.

  The mixed liquid 120 is sent to the heating device 106 and heated in a predetermined temperature range, so that the solubility is increased. Thereafter, the mixed liquid 120 is brought to substantially room temperature by the temperature control device 107 to obtain the dope 70. The dope 70 is sent to a filtration device 109 having a filter with an average pore diameter of 100 μm to remove foreign substances. If the concentration of the dope 70 is a desired value at this time, it is sent to the stock tank 60 and stored until it is cast. In the stock tank 60, the dope 70 is constantly stirred by the stirrer 63 rotated by the motor 62, and a uniform state is maintained. When TAC is used as in this embodiment, the concentration of TAC in the dope 70 is preferably 5 to 40% by weight, more preferably 15 to 30% by weight, and particularly preferably 17%. ~ 25% by weight.

  As described above, in the method of preparing the mixed solution 120 and then preparing the desired concentration of the dope 70, the higher the concentration of the desired dope 70, the longer the time required for the preparation, which increases the manufacturing cost. Problems arise. In order to improve this problem, it is preferable to prepare a dope 70 having a concentration lower than the desired concentration and then concentrate the dope 70 to a desired concentration. In this embodiment, this method is adopted, and the details of the concentration method will be described below.

  The dope 70 having a concentration lower than the desired value is prepared by the above-described procedure. After the foreign substance of the dope 70 is removed by the filtering device 109, the dope 70 is sent to the flash device 110 by opening and closing the valve V2. In the flash device 110, a part of the solvent contained in the dope 70 is evaporated to concentrate the dope 70 to a desired concentration. Thereby, a high concentration dope can be prepared in a short time. The concentrated dope 70 is extracted from the flash device 110 by the pump P6 and then passed through the filtration device 113 to remove foreign substances. In the filtration device 113, the temperature of the dope 70 is preferably set to 0 to 200 ° C. The dope 70 after filtration is stored in the stock tank 60 until it becomes necessary. The solvent gas evaporated from the dope 70 is condensed and liquefied by a condenser (not shown) and then recovered by the recovery device 117. Thereafter, when the solvent regenerated by the regenerator 118 is used for the preparation of the dope, the raw material cost can be reduced. When extracting the dope 70 from the flash device 110, it is preferable to perform a bubble removing process in order to remove bubbles generated in the dope 70. As a method for removing bubbles, a known method can be applied, and examples thereof include an ultrasonic irradiation method.

  The dope production method (for example, raw material, raw material dissolution method, addition method, filtration method, defoaming, etc.) according to the present invention is described in detail in paragraphs [0517] to [0616] of JP-A-2005-104148. These descriptions can also be applied to the present invention.

[Performance / Measurement method]
(Curl degree / thickness)
The performance of the film obtained by the present invention and the measuring method thereof are described in paragraphs [0112] to [0139] of JP-A-2005-104148, and these descriptions can also be applied to the present invention. .

[surface treatment]
Moreover, it is preferable that at least one surface of the completed film is surface-treated. This surface treatment is preferably at least one of vacuum glow discharge treatment, atmospheric pressure plasma discharge treatment, ultraviolet irradiation treatment, corona discharge treatment, flame treatment, acid treatment or alkali treatment.

[Functional layer]
(Antistatic, hardened layer, antireflection, easy adhesion, antiglare)
At least one surface of the completed film may be undercoated.

Moreover, it is preferable to use as a functional material which provided the other functional layer based on the film concerning this invention. As the functional layer, it is preferable to provide at least one of an antistatic layer, a cured resin layer, an antireflection layer, an easy adhesion layer, an antiglare layer, and an optical compensation layer. Then, the functional layer, at least one surfactant preferably contains 0.1 to 1000 mg / ^{m 2,} it is preferable that at least one 0.1 to 1000 mg / ^{m 2} containing a slip agent. Functional layer preferably contains 0.1 to 1000 mg / ^{m 2} at least one matting agent, preferably contains 1 to 1000 mg / ^{m 2} at least one antistatic agent. In addition to the above, the method for providing a surface-treated functional layer for realizing various functions and properties on the film is described in detail in paragraphs [0890] to [1087] of JP-A-2005-104148. Conditions and methods are also described, and these descriptions can also be applied to the present invention.

  The use of the film obtained by the present invention will be described. Since the film has excellent planarity and excellent optical properties, it is useful as a protective film for polarizing plates. A liquid crystal display device produced by sticking two polarizing plates on which a film is attached to a polarizer to a liquid crystal layer exhibits features such as excellent liquid crystal display capability. However, the arrangement of the liquid crystal layer and the polarizing plate is not limited, and various known arrangements can be employed. In JP-A-2005-104148, for example, in the paragraph [1088] to [1265], TN type, STN type, VA type, OCB type, reflective type, and other examples are described in detail as liquid crystal display devices. This method can also be applied to the present invention. The application also describes a film provided with an optically anisotropic layer, a description of a film provided with antireflection and antiglare functions, and a use as an optical compensation film provided with appropriate optical performance. . These descriptions can also be applied to the present invention.

  Next, the present invention will be described in detail with reference to examples according to the present invention. In this example, Experiments 1 to 5 were performed by changing the type of TAC. Among them, Experiment 2, Experiment 4, and Experiment 5 are comparative experiments for the present invention. However, the forms shown in Experiments 1 and 3 are examples related to the present invention and do not limit the present invention. In addition, since the method for producing a film other than those listed in Table 1 is common to each experiment, it will be described below in Experiment 1 and will be omitted for the rest.

[Experiment 1]
In the film manufacturing facility 10, the surface was subjected to chromium plating and mirror finishing, and a base layer dope, a surface layer dope, and a support layer dope were cast on the surface of a cylindrical casting drum 34 having a diameter of 1000 mm. At this time, the casting amount of each dope was adjusted so that the film thickness of the completed film was 60 μm. The surface of the casting drum 34 was set to −12 ° C., and the temperature was controlled so that the temperature was maintained in the range of the set temperature ± 1 ° C. Thereby, each cast dope was cooled and the gel-like casting film 40 was formed. The casting film 40 that had been sufficiently cooled and provided with self-supporting property was peeled off from the casting drum 34 while being supported by the peeling roller 36, thereby forming a wet film 41. The wet film 41 was dried to a predetermined residual solvent amount through the transfer part 13 and the tenter 14 to obtain a film 51. Thereafter, the film 51 was sufficiently dried in the drying chamber 15.

  Further, during film formation, after the casting film 40 is peeled off from the casting drum 34 at all times, before the dope 70 is cast again, oxygen is applied from the drum washing machine 44 to the surface of the casting drum 34. Radicals were supplied to decompose and remove organic matter. As the plasma generator 46, Aiplasma (registered trademark) manufactured by Matsushita Electric Works Co., Ltd. was used. The distance L1 between the nozzle supply port attached to the plasma generator 46 and the surface of the casting drum 34 was 7 mm, and the angle θ1 formed by the nozzle and the casting drum 34 was 90 °.

Film formation was carried out continuously for 200 hours, and oxygen radicals were supplied to the casting drum 34 only once every 72 hours from the start of film formation. One time means that the casting drum 34 is continuously supplied for one rotation, and this means that the oxygen plasma is in contact with the entire circumference of the casting drum 34 only once. The cleaning time of the casting drum by supplying oxygen plasma is 0.0375 seconds. In addition, oxygen gas for generating oxygen radicals was supplied to an electrode part provided in the plasma generator 46 from a cylinder as a supply source. The flow rate of the gas flowing from the plasma generator 46 to the drum cleaning machine 44c was set to 2.1 × 10 ⁻³ m ³ / min. The flow rate of oxygen gas supplied to the electrode part of the plasma generator 46 was set to 0.03 × 10 ⁻³ m ³ / min.

  Table 1 summarizes the TAC conditions and evaluation results for each experiment. Further, in order to know the effect of the present invention, the degree of contamination on the surface of the casting drum after a lapse of a certain time from the start of film formation was evaluated. And the heat resistance was evaluated as a characteristic of the completed film. Each evaluation method is as follows.

[Drum dirt]
After 200 hours had elapsed from the start of production, whether or not dirt was attached to the surface of the casting drum 34 was visually confirmed. Here, the case where almost no adhesion of dirt was confirmed was rated as ◎, and the case where it was very small was marked as ◯. In addition, the case where dirt was attached without waiting for 200 hours from the start of production (actually after 48 hours had elapsed) was marked with x.

〔Heat-resistant〕
A sample obtained by cutting out a part of the completed film was taken as a sample and evaluated for heat resistance. Here, ◯ indicates that the heat resistance is good and satisfies the product level, and X indicates that the heat resistance does not satisfy the product level.

  Cleaning time (unit: second) by oxygen radicals, number of cleanings (unit: times), angle θ1 (unit: °) formed by the direction of supplying oxygen radicals and the surface of the casting drum 34, and distance L1 (mm) The experiment 1 to the experiment 11 were carried out by replacing at least any one of the conditions with) as shown in Table 2. Other conditions are the same as those in Experiment 1 of Example 1. The number of cleanings is “one time” when cleaning with oxygen radicals is continuously performed while the casting drum 34 rotates once. In addition, when the frequency | count of washing | cleaning was multiple times, the predetermined number of washing | cleaning was continuously implemented for every 72-hour progress from casting start. The evaluation criteria for drum stains are the same as those in Table 1, and the case where no stains were confirmed was designated as “「 ”.

  From the above results, according to the present invention, a thin cellulose acylate film can be produced without attaching dirt to the surface of the support. Moreover, since the completed film has favorable heat resistance, it can be said that it can be suitably used as an optical film for liquid crystal display devices and the like.

It is the schematic of an example of the film manufacturing equipment concerning this invention. It is the schematic of the casting drum periphery using a drum washing machine. It is the schematic of an example of the dope manufacturing equipment concerning this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Film production equipment 12 Casting chamber 31 Casting die 34 Casting drum 40 Casting film 44 Drum cleaning machine 46 Plasma generator 51 Film

Claims (6)

After forming a casting film by casting a dope containing cellulose acylate and a solvent from a casting die on the endless running support, the casting film is peeled off from the support and dried. In the method for producing a cellulose acylate film as a film,
The cellulose acylate is produced by an esterification reaction of cellulose obtained from wood, and the molar equivalent of the compound or the bound carboxylic acid group contained in the cellulose acylate to the cellulose acylate is 3 or more and 15 or less. Within the range, the mass concentration of the Ca component in the cellulose acylate is 0 ppm or more and 5 ppm or less, and the mass concentration of the Mg component is 50 ppm or more and 100 ppm or less,
A method for producing a cellulose acylate film, wherein oxygen radicals are supplied to the surface of the support to remove organic substances generated from the cast film and adhered to the surface of the support.   The method for producing a cellulose acylate film according to claim 1, wherein the wood is a conifer.   3. The method for producing a cellulose acylate film according to claim 1, wherein the surface temperature of the support is cooled substantially constant within a range of −20 ° C. to 0 ° C. 3.   4. The oxygen radical is supplied to the surface of the support after the casting film is peeled off and before the dope is cast. 5. A method for producing a cellulose acylate film.   The method for producing a cellulose acylate film according to any one of claims 1 to 4, wherein the film thickness after drying is 20 µm or more and 70 µm or less.   The method for producing a cellulose acylate film according to any one of claims 1 to 5, wherein the support is a casting drum having a peripheral surface, and the rotation speed thereof is 60 m / min or more.

Images