JP2008260925A - Method of manufacturing cellulose acylate film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent fouling from adhering on the surface of a support while producing a film. <P>SOLUTION: A dope 70 is made using a cellulose acylate originated from a conifer. In the cellulose acylate, the molar equivalent of a compound contained in the cellulose acylate or of a bonded carboxylic acid group to the cellulose acylate is within the range of 3-15, the mass concentration of a Ca constituent in the cellulose acylate is 0-5 ppm, and the mass concentration of a Mg constituent is 10-70 ppm. A gel-like casted film 40 is formed by casting the dope 70 on an endlessly-running casting drum 34 having a cooled surface. A cleaning gas containing dry ice particles is blown on the surface of the casting drum 34 from a drum cleaning device 44. A film 51 is obtained by peeling the casted film 40 from the casting drum 34, and thereafter drying. The adhesion of fouling can be prevented by suppressing generation of a fatty acid Ca and the like, and by cleaning the surface of the casting drum 34 with the cleaning gas. <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. The cellulose acylate film is generally 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. It is a method of drying into a film.

  By the way, in the solution casting method, if the film formation is continued, dirt is generated on the surface of the support, and it becomes difficult to smoothly peel the casting film from the support at the place where the dirt is generated. Has a problem that it is impossible to peel off and the film formation must be suspended. If the substrate on which the dirt is adhered is used continuously, in addition to the above problems, organic substances are transferred to the surface of the casting film, thereby causing optical unevenness of the completed film. For this reason, at the film production 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 productivity is lowered, and there is a concern that the surface of the support is damaged, so that improvement is required.

So far, various methods for forming a film without attaching dirt to the surface of the support have been studied, and the dirt is mainly composed of a salt containing Ca and Mg components in cellulose acylate as a main component. Is known to be organic. Thus, for example, Patent Document 1 discloses a method for preventing adhesion to the surface of a support by using cellulose acylate having a low Ca or Mg component content as a film raw material to suppress generation of dirt. Proposed. Moreover, in patent document 2, it discovered that organic substance produced | generated by the coupling | bonding with specific components, such as a fatty acid resulting from a cellulose acylate, fatty acid metal salt, fatty acid alcohol, and Ca, Mg component, A method of using cellulose acylate in which the concentrations of Ca and Mg components are lowered has been proposed.
JP 2006-095971 A JP 2006-199029 A

  However, as in Patent Documents 1 and 2, it is difficult to prevent the adhesion of dirt on the surface of the support only by using cellulose acylate in which the concentration of the specific component and Ca and Mg components is low. In addition, with respect to the solution film-forming method, it is desired to increase the film-forming speed as compared with the related art with the development of liquid crystal display devices and the like. However, in Patent Document 1, the film-forming speed is increased. An effective method for this has not been proposed. On the other hand, Patent Document 2 proposes a method for realizing high speed by adopting a drum casting method. The drum casting method can form a gel-like casting film in a short time by using a drum whose surface is cooled as a support and cooling the dope, so that the production time is shortened. Can be realized. However, the drum casting method has a problem that dirt adheres to the surface of the drum as the manufacturing time elapses, and improvement is desired.

  Accordingly, an object of the present invention is to provide a method capable of producing a cellulose acylate film by increasing the film forming speed while preventing the adhesion of dirt on the surface of a support.

  In the method for producing a cellulose acylate film of the present invention, a cast film is formed by casting a dope containing cellulose acylate and a solvent on an endless running support, and then forming the cast film from the support. In the method for producing a cellulose acylate film that is peeled off and dried to form a film, the cellulose acylate is produced by esterifying cellulose obtained from wood, and the compound contained in the cellulose acylate or the bound carboxylic acid group The molar equivalent to the cellulose acylate is within the range of 3 to 15, and the mass concentration of the Ca component in the cellulose acylate is 0 ppm to 5 ppm and the mass concentration of the Mg component is 10 ppm to 70 ppm. And spraying a cleaning gas containing granular dry ice on the surface of the support. And removing the organic substances adhering to the surface of the support resulting from more casting film.

  The wood is preferably a conifer.

  It is preferable that the surface temperature of the support is −20 ° C. or more and 0 ° C. or less.

  It is preferable to spray the cleaning gas on the surface of the support after the cast film is peeled off and before the dope is cast.

  The support is a casting drum having a peripheral surface, and the rotation speed is preferably 80 m / min or more.

  The cast film preferably has a surface layer in contact with air on the support and an inner layer in contact with the surface layer and the support.

  According to the present invention, a film can be produced without attaching dirt to the surface of a cooled support. For this reason, it becomes possible to manufacture a film by increasing the film forming speed without damaging the surface of the support.

  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 made from wood is used as a dope 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 10 ppm or more and 70 ppm or less. In addition, the compound in a cellulose acylate or what combined carboxylic acid group is meant. Thus, this invention prescribes | regulates the molar equivalent of the carboxylic acid group with respect to a cellulose acylate, and makes more mass concentration of Mg component in a cellulose acylate than Ca component. This point is greatly different from the conventional method in which the content of Ca and Mg components in cellulose acylate is simply reduced. By the above, the coupling | bonding of a carboxylic acid group and Ca is inhibited by Mg and generation | occurrence | production of fatty acid Ca etc. which can become a dirt is suppressed. For this reason, the adhesion of dirt to the surface of the support is effectively prevented. 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.

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 removes organic substances by spraying a predetermined cleaning gas onto the surface of the casting drum 34. As the cleaning gas, a gas containing dry ice particles in air is suitable, but a gas such as nitrogen or an inert gas may be used instead of air. An air supply device 46 for supplying air is connected to the drum cleaning machine 44 through a pipe 46a. The dry ice supply device 45 is connected to the pipe 46a via the pipe 45a. The dry ice supply device 45 is provided with a timer and a flow rate controller for controlling the size and ratio of the dry ice particles, and the dry ice particles whose particle size is adjusted for a predetermined time and minutes are connected to the pipe 45a. To supply. The air supply device 46 is provided with a timer for controlling the air supply time and a pressure regulator, and supplies air by adjusting the pressure to the pipe 46a for the time set by the timer. . Examples of the pressure regulator include those having a cylinder filled with air and a temperature controller for adjusting the temperature of the air in the cylinder.

  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 fixed to 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.

  An additive is suitably determined according to the use etc. of the layer to form. Moreover, when preparing several types of dope for using for casting like this embodiment, it is not necessary to make all the same. For example, if the granular silicon dioxide derivative is included only in the additive solution 71a for preparing the support layer dope, the peelability when the cast film is peeled off from the support is improved. High transparency is secured in a base layer or the like that does not contain a silicon dioxide derivative. One or more additives may be selected and used according to the purpose. 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 dope used for casting preferably contains a plasticizer, an ultraviolet absorber and fine particles from the viewpoints of the properties of the completed film and the handleability in the process of producing the film. At this time, the proportion of the plasticizer with respect to the total weight of the cellulose acylate contained in the film is 3% by weight to 20% by weight, and the ultraviolet absorber is 1 × 10 ⁻³ % by weight to 5% by weight. The fine particles are preferably 1 × 10 ⁻³ wt% or more and 5 wt% or less. These additives may be added as an additive solution, or may be added when the dope 70 is prepared in advance.

  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 80 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. In addition, although the film-forming speed can be increased as the rotational speed is increased, there is a concern about the rotation support structure of the casting drum 34, the accompanying wind suppression during high-speed rotation, or the vibration of the support itself. For this reason, the rotational speed of the casting drum 34 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 80 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. Note that the stability of the support during high-speed rotation is superior to that of the casting band by the casting drum. If the casting drum is used as in this embodiment, the rotational speed is stabilized at 80 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, as the dope raw material, cellulose acylate is used as the raw material of conifers and the ratio of the specific component is within a predetermined range. Therefore, 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 fixed to both side ends 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 30 μm or more and 80 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 and a suction cover 44b provided around the nozzle 44a. The nozzle 44a blows the cleaning gas sent from the blower opening 44c formed at the tip thereof via the pipe 46a to the casting drum 34. The suction cover 44b sucks air in the vicinity of the nozzle 44a through a suction pipe 303 connected to a suction device (not shown). The drum cleaner 44 is connected to a shift unit (not shown). For the purpose of efficiently blowing the cleaning gas to the surface of the casting drum 34 by the operation of the shift portion, the distance L1 from the air blowing port 44c formed at the tip of the nozzle 44a to the casting drum 34, or the casting drum The angle θ1 at which the cleaning gas is sprayed onto 34 is appropriately adjusted.

  The cleaning gas is blown from the blower port 44c to the surface of the casting drum 34 as appropriate. When the dry ice particles in the cleaning gas collide with the surface of the casting drum 34, the organic matter attached to the surface of the casting drum 34 is pulverized. Since the surface of the casting drum 34 of the present embodiment is cooled in a predetermined temperature range, the dry ice does not sublimate and collides with the casting drum 34. While the organic matter is being pulverized and removed, the air around the cleaning portion is sucked by the suction cover 44b, so that the organic matter crushed and scattered around the surface of the casting drum 34 is recovered. For this reason, the pulverized organic matter does not adhere to the surface of the casting film 40 and the surface is not damaged. The suction force is not particularly limited as long as it is appropriately adjusted within a range smaller than the spraying pressure of the cleaning gas.

  The effects of pulverizing the organic matter include the average particle diameter of dry ice, the pressure for spraying the cleaning gas, the spray angle θ1 between the cleaning gas and the surface of the casting drum 34, the distance L1 between the surface of the casting drum 34 and the nozzle 44a, and the like. It can improve by adjusting suitably. The average particle size of dry ice is preferably 5 μm or more and 20 μm or less. If the particle diameter exceeds 20 μm, the dry ice particles may be too large and damage the support surface. On the other hand, if the particle size is less than 5 μm, the efficiency of pulverizing the organic matter is too small. In addition, it is preferable that the particle size of dry ice is appropriately selected according to the growth of organic matter.

  The pressure for blowing the cleaning gas is preferably 600 kPa to 4000 kPa, more preferably 1000 kPa to 2500 kPa. When the spraying pressure exceeds 4000 kPa, there is a possibility that dry ice particles are clogged in the nozzle 44b, and the surface of the casting drum 34 may be damaged. On the other hand, if it is less than 600 kPa, since the energy generated at the time of gas collision is small, the effect of pulverizing organic substances is weak.

  The angle θ1 formed by the direction in which the cleaning gas is blown and the surface of the casting drum 34 is preferably 45 ° or more and 135 ° or less, more preferably 70 ° or more and 110 ° or less, and most preferably 85 ° or more and 95 °. It is as follows. This angle θ1 is appropriately adjusted according to the shape of the organic substance. Furthermore, the distance L1 between the air outlet 44c of the nozzle 44a and the surface of the casting drum 34 is preferably 0.1 mm or more and 15.0 mm or less, more preferably 0.1 mm or more and 10.0 mm or less, and particularly preferably. Is 0.1 mm or more and 2.0 mm or less. The above L1 is equal to the length until the cleaning gas exiting from the blower port 44c collides with the surface of the casting drum 34. As L1 becomes longer than 15 mm, there is a concern that dry ice particles sublime before reaching the surface of the casting drum 34, and it is difficult to secure energy necessary for pulverizing the organic matter. On the other hand, if L1 is less than 0.1 mm, the energy at the time of collision cannot be ensured, and installation of the device is difficult.

  The method of spraying the cleaning gas as in the present invention is useful for removing organic substances adhering to the surface of the casting drum 34. Organic substances are mainly composed of fatty acid esters, and are pulverized by spraying dry ice particles in addition to fatty acids and fatty acid metal salts, or dissolved in liquid carbon dioxide and evaporated together with liquid carbon dioxide. Things are the subject. Moreover, although it described that the cleaning gas which consists of dry ice and air was used in the said embodiment, not only this but nitrogen, an inert gas, etc. may be used instead of air.

  The cleaning gas is blown before the casting film 40 is formed on the casting drum 34 or after the casting film 40 is peeled off from the casting drum 34. At this time, spraying is performed constantly (continuously) or intermittently. If the cleaning gas is blown as soon as possible after the casting film 40 has been peeled off, the organic matter does not grow, so that the organic matter can be crushed and removed efficiently. The time for spraying the cleaning gas is preferably 0.001 seconds or more and 5 seconds or less, more preferably 0.01 seconds or more and 5 seconds or less for the purpose of efficiently and effectively pulverizing the organic matter. Further, in the present embodiment, a so-called online format is shown in which organic substances on the surface of the casting drum 34 are removed during film formation. However, after the casting drum 34 is once taken out, the same removal treatment is performed on the surface thereof. The foreign matter may be removed in a so-called off-line manner. In this case, if an alternative casting drum 34 is installed, a reduction in productivity can be suppressed as much as possible.

  If the method of cleaning the casting drum 34 using a cleaning gas 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 method of spraying dry ice particles can be applied as a means for cleaning the surface of the casting drum 34 under explosion-proof management.

  The apparatus for supplying the cleaning gas in which the dry ice particles as described above are mixed with air is not particularly limited. For example, the cleaning gas may be obtained by using dry ice particles generated by spraying liquid carbon dioxide. Next, with reference to FIG. 3, an embodiment of a drum washer when liquid carbon dioxide is used will be described. As shown in FIG. 3, the drum cleaner 150 includes a first nozzle 151 and a second nozzle 152.

  The first nozzle 151 includes a carrier gas inlet 162 into which the carrier gas 300 is introduced, a carbon dioxide inlet 163 into which the liquid carbon dioxide 310 is introduced, a cleaning gas blowing port 164 that sends out the cleaning gas 320, and a carrier gas. A carrier gas channel 165 that communicates the inlet 162 and the cleaning gas blower 164 and a carbon dioxide channel 166 that communicates the carbon dioxide inlet 163 and the carrier gas channel 165 are provided. The carrier gas channel 165 has a particle forming unit 167 that creates a cleaning gas 320 containing dry ice particles 311 from the liquid carbon dioxide 310 from the carrier gas 300 and the carbon dioxide channel 166. Further, the carbon dioxide channel 166 has an orifice 168 on the outlet 166a side. Further, the carrier gas channel 165 has a rectifying pocket 169 having a cross-sectional area larger than the cross-sectional area of the carrier gas channel 165 on the upstream side of the particle forming unit 167.

  The second nozzle 152 includes a cleaning gas introduction port 175 into which the cleaning gas 320 from the cleaning gas blowing port 164 is introduced, a cleaning gas supply port 176 that sends out the cleaning gas 320, a carrier gas introduction port 175, and a cleaning gas blowing port 176. And a cleaning gas flow path 177 for communicating with each other. The cleaning gas channel 177 has a rectifying pocket 178 having a cross-sectional area larger than that of the cleaning gas channel 177.

  The second nozzle 152 is attached to the first nozzle 151 such that the cleaning gas blowing port 164 and the cleaning gas introduction port 175 are connected. Then, the drum washer 150 is arranged so that the distance L1 between the peripheral surface 34b of the casting drum 34 and the cleaning gas blowing port 176 and the spray angle θ1 have desired values. In addition, since the installation conditions (L1, θ1, etc.) of the drum washer for the vicinity of the casting drum may be the same as described above, the description thereof is omitted here.

  The carrier gas inlet 162 is connected via a pipe 180 to a carrier gas tank 181 that is a supply source of the carrier gas 300. The pipe 180 is provided with a throttle valve 182 that adjusts the flow rate of the carrier gas 300. The carbon dioxide inlet 163 is connected to a carbon dioxide tank 191 that is a supply source of the liquid carbon dioxide 310 via the pipe 190. The pipe 190 is provided with a throttle valve 192 that adjusts the flow rate of the liquid carbon dioxide 310.

  These throttle valves 181 and 191 are adjusted by a controller 195. Under the control of the controller 195, the openings of the throttle valves 181 and 191 are adjusted to desired ranges, respectively. By adjusting the opening degree of the throttle valves 181 and 191, the spray pressure of the cleaning gas 320, the particle size of the dry ice 311, the mixing ratio of the carrier gas 300 and the liquid carbon dioxide 310 can be adjusted.

  As the carrier gas 300, for example, air is used. The carrier gas tank 181 may store the carrier gas 300 in a state compressed to a predetermined pressure. As the liquid carbon dioxide 310, it is preferable to use one having high purity. Further, the conditions of the carbon dioxide tank 191 and the pipe 190 may be any as long as the liquid carbon dioxide 310 sent from the carbon dioxide tank 191 can maintain the liquid state before reaching the particle forming unit 167. .

Next, the operation of the drum washer 150 will be described. Under the control of the controller 195, the openings of the throttle valves 181 and 191 are adjusted to desired ranges, respectively. The carrier gas 300 is introduced from the carrier gas tank 181 to the carrier gas inlet 162 via the pipe 180 at a predetermined flow rate Q1 (m ³ / mm · min) and sent to the particle forming unit 167 of the carrier gas channel 165. The liquid carbon dioxide 310 is introduced from the carbon dioxide tank 191 to the carbon dioxide inlet 163 via the pipe 190 at a predetermined mass flow rate Q2 (kg / mm · min), and sent to the carbon dioxide channel 166. The liquid carbon dioxide 310 sent to the carbon dioxide channel 166 is sent to the particle forming unit 167 via the orifice 163. The liquid carbon dioxide 310 sent to the particle forming unit 167 becomes carbon dioxide gas and dry ice particles 311 due to phase change. The carbon dioxide gas and the dry ice particles 311 collide with the organic substance X1 deposited on the peripheral surface 34b by the flow of the carrier gas 300. The organic substance X1 is removed from the peripheral surface 34b by the collision between the dry ice particles 311 and the organic substance X1.

  The removal action of the organic substance X1 includes (1) the kinetic energy of the dry ice particles sprayed by the collision between the dry ice particles and the organic substance X1 is used to destroy the organic substance X1 attached to the peripheral surface 34b, and (2) the organic substance Dry ice particles become liquid carbon dioxide due to collision with X1, and this liquid carbon dioxide dissolves organic substance X1, and (3) volume expansion due to vaporization of liquid carbon dioxide and dry ice particles is an organic substance. The synergistic effect by blowing off X1 and the combination of (1)-(3) is mentioned. The organic matter X1 removed from the peripheral surface 34b due to the effect caused by the collision with the dry ice particles is refined and circulated together with the atmospheric gas, which leads to the occurrence of thickness unevenness and deposit failure due to the organic matter X1 and the residue. There is no. Moreover, even if it remains on the peripheral surface 34b, it is a minute object and does not develop into a precipitate failure due to this.

  In the second embodiment, the drum cleaner 150 including the first nozzle 151 and the second nozzle 152 is used. However, the present invention is not limited to this, and only the first nozzle 151 may be used as the drum cleaner. .

  The drum cleaning machine according to the present invention is preferably of a contact type with respect to the casting drum, and can uniformly spray the cleaning gas in the width direction with respect to the casting drum. As a suitable example, what has a ventilation port substantially equivalent to the width direction full length of a support body is mentioned, for example. In addition, a point where organic substances are likely to be generated on the surface of the support is specified in advance by casting a dope on a small scale, and a drum washer may be randomly installed with the aim at this point. .

  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. Furthermore, 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 matter can be pulverized in 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. 4, 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 [1073] to [1087] 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 applying a surface treatment functional layer for realizing various functions and properties on the film is described in detail in paragraphs [0890] to [1072] 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 addition, the form shown here is an example concerning this invention, Comprising: This invention is not limited.

[Film production]
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.

  A drum washer 44 was installed between the peeling roller 36 and the decompression chamber 32 and in the vicinity of the surface of the casting drum 34 to clean the casting drum 34 online. The drum washer 44 was a snocle manufactured by Linkstar Japan, and the nozzle 44a was a nozzle with an orifice made of Teflon (registered trademark). The cleaning gas spray angle θ1 with respect to the surface of the casting drum 34 was set to 85 °. The distance L1 between the blowing port 44c of the nozzle 44a and the surface of the casting drum 34 is 15 mm, the cleaning gas spraying pressure is 896.35 kPa, and the continuous spraying time for the rotating casting drum 34 is 5 seconds. did. Thereby, the spraying time of the cleaning gas to an arbitrary point on the circumferential surface of the casting drum 34 is about 0.01 seconds.

  In Example 1, TAC using softwood as a raw material was used. Moreover, Ca component in TAC was 5 ppm, and Mg component was 40 ppm.

  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, ◎ is the case where the adhesion of dirt is hardly confirmed, ◯ is the case where it is very small, △ is slightly confirmed, △ is the case where the level is not a problem in manufacturing, △, the case where very much dirt is confirmed X. As a result, no stain was observed in Example 1 (◎). Moreover, when the heat resistance of the completed film 51 was evaluated, it showed a good value (◯) satisfying the product level.

  In Example 2, a film was produced in the same manner as in Example 1 except that the content of the Mg component in TAC was 30 ppm. As a result, even after 200 hours from the start of production, only a very small amount of dirt was observed on the casting drum (◯). Moreover, the heat resistance of the completed film (film thickness 60 micrometers) was also favorable.

  In Example 3, films were produced in the same manner as in Example 1 except that TAC made from hardwood was used. As a result, organic substances were confirmed when 200 hours passed from the start of production (×).

[Comparative Example 1]
In Comparative Example 1, a film was produced in the same manner as in Example 1 except that the casting drum 34 was not washed by the drum washer 44 and the film was produced. As a result, when 200 hours passed from the start of production, a very small amount of dirt was confirmed (Δ). On the other hand, when the heat resistance of the completed film (film thickness 60 μm) was confirmed, it showed a good value (◯).

[Comparative Example 2]
In Comparative Example 2, the content of the Ca component in TAC was 70 ppm, and the content of the Mg component was 5 ppm. In addition, a film was produced in the same manner as in Example 1 except that the film was produced without using the drum washer 44. As a result, it was confirmed that the surface of the casting drum 34 was contaminated 48 hours after the start of production. Moreover, when the heat resistance of the completed film (film thickness of 60 μm) was confirmed, the product level was not satisfied (×).

[Comparative Example 3]
In Comparative Example 3, a film was produced in the same manner as in Example 1 except that TAC having a Ca component content of 30 ppm was used. As a result, when the heat resistance of the completed film (film thickness: 60 μm) was evaluated, the product level was good (◯), but when 200 hours passed from the start of production, the adhesion of dirt was confirmed ( ×).

  Next, Experiments 1 to 5 were performed by changing at least one of the thickness of the film to be completed, the surface temperature of the casting drum 34, and the spraying time in Example 1 as shown in Table 1. The spraying time is the sum of the spraying time during which the production of the film is continued for 200 hours. Other conditions are the same as those in the first embodiment. Each experiment 1-5 was also carried out in the same manner as in Examples 1 to 3 and Comparative Examples 1 to 3. The evaluation results are also shown in Table 1.

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 the drum washing machine which is 1st Embodiment. It is the schematic of the casting drum periphery using the drum washing machine which is 2nd Embodiment. 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, 150 Drum washing machine 51 Film

Claims (6)

Cellulose is formed by casting a dope containing cellulose acylate and a solvent on an endless running support to form a cast film, and then peeling off the cast film from the support and drying it. In the method for producing an acylate film,
The cellulose acylate is produced by esterifying cellulose obtained from wood, and the molar equivalent of the compound contained in the cellulose acylate or the bound carboxylic acid group to the cellulose acylate is in the range of 3 to 15. The mass concentration of the Ca component in the cellulose acylate is from 0 ppm to 5 ppm, and the mass concentration of the Mg component is from 10 ppm to 70 ppm,
A method for producing a cellulose acylate film, wherein organic substances adhering to the surface of the support produced by the casting film are removed by spraying a cleaning gas containing granular dry ice on the surface of the support.   The method for producing a cellulose acylate film according to claim 1, wherein the wood is a conifer.   The method for producing a cellulose acylate film according to claim 1 or 2, wherein the support has a surface temperature of -20 ° C to 0 ° C.   The cellulose according to any one of claims 1 to 3, wherein the cleaning gas is sprayed on a surface of the support after the casting film is peeled off and before the dope is cast. A method for producing an acylate film.   The method for producing a cellulose acylate film according to any one of claims 1 to 4, wherein the support is a casting drum having a peripheral surface, and a rotation speed thereof is 80 m / min or more.   The cellulose acylate film according to any one of claims 1 to 5, wherein the cast film has a surface layer in contact with air on the support and an inner layer in contact with the surface layer and the support. Manufacturing method.

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