JP5001088B2 - Casting die, solution casting equipment and solution casting method - Google Patents

Description

  The present invention relates to a casting die that flows out a viscoelastic fluid, a solution casting apparatus, and a solution casting method. In particular, the present invention relates to a casting die that flows out a dope containing a polymer that is a raw material of the film, and a solution casting apparatus and a solution casting method for producing a film from the dope.

  Polymer films (hereinafter referred to as films) are widely used as optical functional films because of their features such as excellent light transmittance, flexibility, and reduction in weight of thin films. Among them, TAC film formed from cellulose acylate, particularly cellulose triacetate (hereinafter referred to as TAC) having an average degree of acetylation of 57.5% to 62.5%, is a photograph because of its toughness and flame retardancy. It is used as a film support for photosensitive materials. In addition, since the TAC film is excellent in optical isotropy, it is used for a protective film for a polarizing plate of a liquid crystal display device whose market is rapidly expanding, an optical compensation film (for example, a viewing angle expansion film, etc.), and the like. ing.

  The main film production methods include a melt extrusion method and a solution casting method. The melt-extrusion method is a method in which a polymer is heated and dissolved as it is and then extruded with an extruder to produce a film, which has features such as high productivity and relatively low equipment cost. However, it is difficult to adjust the thickness accuracy of the film, and because fine lines (die lines) are formed on the film, it is difficult to produce a high-quality film that can be used for optical films. It is. On the other hand, in the solution casting method, after a cast film formed by casting a polymer solution containing a polymer and a solvent (hereinafter referred to as a dope) on a support has self-supporting properties, This is peeled off from the support to form a wet film, and both ends of the wet film are supported by a tenter, and while being transported in a predetermined direction, a stretching process and a relaxation process are performed at the same time, and the wet film is sufficiently dried. It is a method of winding up as a film. This solution casting method is superior to the melt extrusion method in terms of optical isotropy and thickness uniformity, and can obtain a film with a small amount of contained foreign matter. Therefore, as a method for producing a film, particularly an optical film, A membrane method is employed.

  The outline of the casting process which is one process of this solution casting method will be described. As shown in FIG. 12, in the casting process, the dope 801 flows out from the die 800, which is an outflow device, to the traveling support 802. The dope 801 flowing out to the support body 802 is flow-extended on the support body 802 as the support body 802 travels in the direction X1 to form a casting film 803.

  The die 800 includes an outlet 800 a that flows out of the dope 801. As shown in FIG. 13, the die 800 includes lip plates 810 and 811, side plates 812 and 813, and inner deckle plates 814 and 815. The lip plates 810 and 811 and the inner deckle plates 814 and 815 include liquid contact surfaces 810a, 811a, 814a, and 815a that are in contact with the dope 801, and the liquid contact surfaces 810a, 811a, 814a, and 815a are provided. The outflow port 800a is formed.

  When the dope 801 flows out from the outlet 800a, the dope 801 is cast on the support 802 to form a casting bead from the outlet 800a to the support 802, and a casting film 803 is formed on the support 802. Form. However, in the vicinity of both ends (the inner deckle plates 814 and 815 side) of the outlet 800a, the dope 801 is likely to stay and the dope 801 is likely to be dried, and skinning occurs. When the dope 801 is cast, the skin grows in a wiggle shape at both ends of the outlet 800 a, disturbs the flow of the dope 801 from the outlet 800 a, and forms a casting bead or a casting film 803. Inhibit. Therefore, when this skinning occurs, the casting speed must be reduced to a speed at which the casting bead or casting film 803 does not cut, and the skinning must be removed. This was a cause of significant reduction in productivity.

Conventionally, as a countermeasure for preventing the occurrence of skinning, a method of flowing down a solvent soluble in the dope in order to prevent the dope from drying, and a method of preventing stagnation of the dope in the vicinity of the outlet are known. Patent Documents 1 and 2 disclose a method for preventing the occurrence of skinning by supplying a solvent such as methylene chloride to both ends of a dope such as cellulose triacetate cast from a casting die (hereinafter referred to as a liquid method). Is disclosed. Patent Document 3 discloses a solution casting method that suppresses the occurrence of dope skinning by setting the angle θ between the lip surface and the lip side surface in the cross-sectional shape at both ends of the lip tip of the casting die to be 120 degrees or more. ing.
Japanese Patent No. 2687260 JP 2002-337173 A JP 2002-103361 A

  However, it is difficult to control the wind speed in the vicinity of the outlet 800a and the supply amount of the solvent used in the liquid method in a desired range in the casting process. In the case of using the methods described in Patent Documents 1 and 2, if the wind speed in the vicinity of the outlet 800a and the supply amount of the solvent are not properly controlled, the flowing solvent scatters on the support, and the plane of the film Cause a flatness failure that loses its property, and an excessive supply of solvent causes a foreign matter adhesion failure. And if a foreign material adheres on a support body, a casting speed must be decelerated and a support body must be wash | cleaned, and productivity will fall remarkably. Furthermore, establishment of a high-speed solution casting method is demanded in order to respond to a significant increase in demand for liquid crystal display devices, but it is more difficult to control the wind speed and temperature in the vicinity of the outlet 800a as the film-forming speed increases. Therefore, it is difficult to apply the above method. In addition, in the case of using the method described in Patent Document 3, it is very difficult to obtain the processing accuracy of the shape of the outlet that can prevent the occurrence of skinning. The effect is not sufficient.

  As a result of intensive studies, the inventor has a high flatness of the outlet 800a, that is, a deviation between the end surfaces of the lip plates 810 and 811 and the end surfaces of the inner deckle plates 814 and 815 in the outflow direction of the dope 801 (hereinafter, It was found that the retention of the dope 801 that induces the occurrence of skinning can be suppressed when the unevenness) is below a certain value.

  An object of the present invention is to provide a casting die that prevents the occurrence of skinning in the casting process, a solution casting apparatus with high production efficiency, and a solution casting method.

The present invention provides a casting die for flowing out a dope containing a polymer and a solvent from a slit, a pair of first slit members forming a longitudinal flow path surface of the slit, and a pair of second slits forming a width direction flow path surface of the slit. A slit member, wherein the first and second slit members are made of a material having a volume change rate of 0.05% or less, and a second slit relative to the first slit member in the outflow direction of the dope. projecting amount of members, or the amount of projection of the first slit member relative to the second slit member, wherein the is at 9μm or less, a.

  A pair of said 1st slit member is comprised from the lip plate arrange | positioned facing so that the clearance gap of a fixed space | interval may be formed, and a pair of said 2nd slit member is on the both ends of the said lip plate and the said lip plate. It is preferable that it is comprised from the inner deckle board arrange | positioned so that the said side plate may be contact | connected within the clearance gap surrounded by the attached side plate.

  Preferably, the lip plate and the side plate are made of stainless steel, and the inner deckle plate is made of one of stainless steel and ceramics. Moreover, it is preferable that a pair of said 2nd slit member has an expansion surface from which the casting width | variety of the said dope becomes large gradually as the said dope flows out.

  The solution casting apparatus of the present invention includes the casting die, a support that forms a casting film from the dope that runs and flows out of the slit, and the casting film on the support is peeled off and dried. And a drying device.

  The solution casting method of the present invention includes a step of forming a casting film by causing the dope to flow out from the slit on a traveling support using the casting die, and the casting on the support. And a step of peeling and drying the film.

  According to the casting die of the present invention, since the dope retention at the outlet is suppressed due to the die swell phenomenon in which the diameter of the dope flowing out of the slit is larger than the diameter of the outlet of the slit, Occurrence can be prevented. In addition, the solution casting apparatus and the solution casting method provided with such a casting die do not require the removal work of the skinning generated in the conventional casting process, and perform solution casting with high production efficiency. Can do.

  Hereinafter, embodiments of the present invention will be described in detail. However, the present invention is not limited to the embodiments listed here.

[material]
In the present embodiment, cellulose acylate is used as the polymer, and triacetyl cellulose (TAC) is particularly preferable as the cellulose acylate. Among the cellulose acylates, those in which the substitution degree of the acyl group with respect to the hydrogen atom of the hydroxyl group of cellulose satisfies all of the following formulas (I) to (III) are more preferable. In the following formulas (I) to (III), A and B represent the substitution degree of the acyl group with respect to the hydrogen atom of the hydroxyl group of cellulose, A represents the substitution degree of the acetyl group, and B represents 3 to 3 carbon atoms. 22 is the substitution degree of the acyl group. In addition, it is preferable that 90 weight% or more of TAC is a particle | grain of 0.1 mm-4 mm.
(I) 2.5 ≦ A + B ≦ 3.0
(II) 0 ≦ A ≦ 3.0
(III) 0 ≦ B ≦ 2.9
The polymer used in the present invention is not limited to cellulose acylate.

  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 of the hydroxyl group of cellulose esterified at each of the 2-position, 3-position and 6-position (100% esterification has a substitution degree of 1).

  The total acylation substitution degree, that is, 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, 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 degree of substitution of the hydroxyl group at the 2-position of the glucose unit with an acyl group (hereinafter also referred to as “degree of acyl substitution at the 2-position”), and DS3 is the degree of substitution of the hydroxyl group at the 3-position with an acyl group (hereinafter, referred to as “acyl group”). DS6 is the substitution degree of the hydroxyl group at the 6-position with an acyl group (hereinafter also referred to as “acyl substitution degree at the 6-position”).

  Only one type of acyl group may be used in the cellulose acylate of the present invention, 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. When the sum of the substitution degrees by the hydroxyl groups at the 2nd, 3rd and 6th positions is DSA, and the sum of the substitution degree by an acyl group other than the acetyl group at the 2nd, 3rd and 6th hydroxyl groups is DSB, the value of DSA + DSB is More preferably, it is 2.22 to 2.90, and particularly preferably 2.40 to 2.88. The DSB is 0.30 or more, particularly preferably 0.7 or more. Further, 20% or more of DSB is a substituent at the 6-position hydroxyl group, more preferably 25% or more is a substituent at the 6-position hydroxyl group, more preferably 30% or more, and particularly 33% or more is a 6-position hydroxyl group. It is preferable that it is a substituent. Furthermore, the cellulose acylate having a substitution degree of 6-position of cellulose acylate of 0.75 or more, further 0.80 or more, and particularly 0.85 or more can be mentioned. With these cellulose acylates, a solution having a preferable solubility (dope) can be produced. In particular, in a non-chlorine organic solvent, a good solution can be produced. Furthermore, it is possible to produce a solution having a low viscosity and good filterability.

  Cellulose, which is a raw material for cellulose acylate, may be obtained from either linter or pulp.

  The acyl group having 2 or more carbon atoms of the cellulose acylate of the present invention may be an aliphatic group or an aryl group and is not particularly limited. These are, for example, 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, butanoyl, pentanoyl, hexanoyl, octanoyl, decanoyl, dodecanoyl, tridecanoyl, tetradecanoyl, hexadecanoyl, octadecanoyl, iso-butanoyl, t-butanoyl, cyclohexanecarbonyl, oleoyl, benzoyl , Naphthylcarbonyl, cinnamoyl group and the like. Among these, propionyl, butanoyl, dodecanoyl, octadecanoyl, t-butanoyl, oleoyl, benzoyl, naphthylcarbonyl, cinnamoyl and the like are more preferable, and propionyl and butanoyl are particularly preferable.

  Solvents for preparing the dope include aromatic hydrocarbons (eg, benzene, toluene, etc.), halogenated hydrocarbons (eg, dichloromethane, 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 the present invention, the dope means a polymer solution or dispersion obtained by dissolving or dispersing a polymer in a solvent.

  Among these, halogenated hydrocarbons having 1 to 7 carbon atoms are preferably used, and dichloromethane is most preferably used. In addition to dichloromethane, one kind of alcohol having 1 to 5 carbon atoms is used from the viewpoint of physical properties such as solubility of TAC, peelability from cast film support, mechanical strength of film, and optical properties of film. It is preferable to mix several kinds. The content of the alcohol is preferably 2% by weight to 25% by weight and more preferably 5% by weight to 20% by weight with respect to the whole solvent. Specific examples of the alcohol include methanol, ethanol, n-propanol, isopropanol, n-butanol and the like, but methanol, ethanol, n-butanol or a mixture thereof is preferably used.

  By the way, recently, for the purpose of minimizing the influence on the environment, studies have been conducted on the solvent composition when dichloromethane is not used. For this purpose, ethers having 4 to 12 carbon atoms, carbon atoms A ketone having 3 to 12 carbon atoms, an ester having 3 to 12 carbon atoms, and an alcohol having 1 to 12 carbon atoms are preferably used. These may be used in combination as appropriate. For example, a mixed solvent of methyl acetate, acetone, ethanol, and n-butanol can be mentioned. These ethers, ketones, esters and alcohols may have a cyclic structure. A compound having two or more functional groups of ether, ketone, ester, and alcohol (that is, —O—, —CO—, —COO—, and —OH) can also be used as the solvent.

  The details of cellulose acylate are described in paragraphs [0140] to [0195] of JP-A-2005-104148. These descriptions are also applicable to the present invention. The same applies to additives such as solvents and plasticizers, deterioration inhibitors, UV absorbers (UV agents), optical anisotropy control agents, retardation control agents, dyes, matting agents, release agents, release accelerators, etc. JP-A-2005-104148 describes in detail in paragraphs [0196] to [0516].

[Dope production method]
First, a dope is manufactured using the above raw materials. The dope production line includes a solvent tank for storing the solvent, a dissolution tank for mixing the solvent and TAC, a hopper for supplying TAC, and an additive tank for storing the additive. ing. Furthermore, a heating device for heating the swelling liquid described later, a temperature controller for adjusting the temperature of the prepared dope, and a filtration device are provided. Further, a recovery device for recovering the solvent and a regeneration device for regenerating the recovered solvent are provided. The dope production line is connected to a film production facility 40 via a stock tank 39 (see FIG. 2).

  First, the valve is opened and the solvent is sent from the solvent tank to the dissolution tank. Next, it is put in the hopper, but it is fed into the dissolution tank while being weighed. The additive solution (mainly containing the plasticizer) is sent from the additive tank to the dissolution tank by opening and closing the valve. In addition to the method of sending the additive as a solution, for example, when the additive is liquid at room temperature, it can be sent to the dissolution tank in the liquid state. Further, when the additive is solid, a method of feeding into the dissolution tank using a hopper or the like is also possible. When a plurality of types of additives are added, a solution in which a plurality of types of additives are dissolved can be placed in the additive tank. Alternatively, a solution in which an additive is dissolved can be put in each of a plurality of additive tanks, and sent to the dissolution tank through independent pipes.

  In the above description, the order of putting into the dissolution tank is the solvent (used in the meaning including the case of the mixed solvent), TAC, and additive, but is not limited to this order. For example, a preferred amount of solvent can be fed after the TAC is metered into the dissolution tank. The additive does not necessarily need to be put in the dissolution tank in advance, and can be mixed in a mixture of TAC and a solvent (hereinafter, these mixtures may also be referred to as a dope) in a later step.

  The dissolution tank is provided with a jacket that wraps around its outer surface and a first stirrer that is rotated by a motor. Furthermore, it is preferable that the 2nd stirrer rotated by a motor is attached. The first stirrer is preferably provided with anchor blades, and the second stirrer is preferably a dissolver type eccentric stirrer. And the temperature of the dissolution tank is adjusted by flowing a heat transfer medium inside the jacket, and the preferred temperature range is -10 ° C to 55 ° C. By appropriately selecting and using the types of the first stirrer and the second stirrer, a swelling liquid in which TAC is swollen in a solvent is obtained.

  Next, the swelling liquid is sent to a heating device by a pump. The heating device is preferably a jacketed pipe, and further preferably has a configuration capable of pressurizing the swelling liquid. By using such a heating apparatus, the dope is obtained by dissolving the solid content in the swelling liquid under heating conditions or under pressure heating conditions. Hereinafter, this method is referred to as a heating dissolution method. In this case, the temperature of the swelling liquid is preferably 50 ° C to 120 ° C. Moreover, the cooling dissolution method which cools a swelling liquid to the temperature of -100 degreeC--30 degreeC can also be performed. TAC can be sufficiently dissolved in a solvent by appropriately selecting the heating dissolution method and the cooling dissolution method. After the dope is brought to about room temperature with a temperature controller, the impurities contained in the dope are removed by filtration with a filtration device. The filtration filter used in the filtration device preferably has an average pore diameter of 100 μm or less. The filtration flow rate is preferably 50 L / hour or more. The dope 11 after filtration (see FIG. 2) is sent to the stock tank 39 in the film production facility 40 and stored therein.

  By the way, as described above, the method of once preparing the swelling liquid and then using the swelling liquid as a dope increases the time required as the concentration of TAC is increased, which may be problematic in terms of manufacturing cost. . In that case, it is preferable to prepare a dope having a concentration lower than the target concentration and then perform a concentration step for obtaining the target concentration. When using such a method, the dope filtered by the filtration device is sent to the flash device, and a part of the solvent in the dope is evaporated in the flash device. The solvent gas generated by the evaporation is condensed by a condenser (not shown) to become a liquid and recovered by a recovery device. The recovered solvent is regenerated and reused as a solvent for preparing a dope by a regenerator. This reuse is effective in terms of cost.

  Further, the concentrated dope is extracted from the flash device by a pump. Furthermore, it is preferable that a bubble removal process is performed to remove bubbles generated in the dope. As this defoaming method, various known methods are applied, for example, an ultrasonic irradiation method. The dope is then sent to a filtration device to remove foreign matter. In addition, it is preferable that the temperature of dope at the time of filtration is 0 degreeC-200 degreeC. And the dope 11 (refer FIG. 2) after filtration is sent to the stock tank 39, and is stored.

  By the above method, the dope 11 having a TAC concentration of 5 wt% to 40 wt% can be manufactured. More preferably, the TAC concentration is in the range of 15% by weight to 30% by weight, and most preferably in the range of 17% by weight to 25% by weight. The concentration of the additive (mainly a plasticizer) is preferably in the range of 1% by weight to 20% by weight when the total solid content in the dope is 100% by weight. In addition, from the [0517] paragraph of Unexamined-Japanese-Patent No. 2005-104148 about the manufacturing method of dope, such as the raw material in the solution casting method which obtains a TAC film, a raw material, the additive dissolution method and addition method, a filtration method, and defoaming [0616] The paragraph is detailed. These descriptions are also applicable to the present invention.

(Film production process)
Next, the film manufacturing process 10 of the present invention will be described. As shown in FIG. 1, the film manufacturing process 10 includes a casting dope preparation process 15 for preparing a casting dope 14 from the dope 11 obtained above, and casting the casting dope 14 on a support. A casting process 17 for forming the film 16, a stripping process 19 for stripping the casting film 16 having a self-supporting property from the support to form a wet film 18, and drying the wet film 18 to obtain a film 22. And a drying step 20. In addition, you may perform the winding process which winds up this film 22 and uses it as a film roll.

(Solution casting method)
Next, a film manufacturing facility 40 that manufactures the film 22 using the dope 11 will be described. FIG. 2 is a schematic view showing the film manufacturing facility 40. However, the present invention is not limited to a film manufacturing facility as shown in FIG. The film production facility 40 includes a stock tank 39, a casting die 41, a casting band 44 stretched over rotating rollers 42, 43, a tenter drying chamber 45, an ear clip device 46, a drying chamber 47, a cooling chamber 48, and a winding A chamber 49 and the like are provided.

  An agitator 56 that is rotated by a motor 55 is attached to the stock tank 39. The stock tank 39 is connected to the casting die 41 via a pipe 61 including a pump 58, a filtration device 59, and a static mixer 60.

  In the pipe 61, an additive solution containing a matting agent solution and an ultraviolet absorber solution is added to the dope 11. The dope 11 containing the additive solution is mixed and stirred by the static mixer 60 to become a uniform solution. Hereinafter, this liquid is referred to as a casting dope 14.

  The casting die 41 as an outflow device includes an outflow port 41 a (FIG. 3) through which the casting dope 14 flows out, and is arranged so that the outflow port 41 a faces the casting band 44. Thus, the casting die 41 can flow out the casting dope 14 from the outlet 41 a onto the casting band 44. Details of the casting die 41 will be described later.

  As shown in FIG. 2, a casting band 44 is provided below the casting die 41 so as to span the rotating rollers 42 and 43. The rotating rollers 42 and 43 are rotated by a driving device (not shown), and the casting band 44 travels endlessly with this rotation. It is preferable that the casting band 44 can move at a moving speed, that is, a casting speed of 10 m / min to 200 m / min. Further, in order to set the surface temperature of the casting band 44 to a predetermined value, it is preferable that the heat transfer medium circulation device 80 is attached to the rotary rollers 42 and 43. It is preferable that the surface temperature of the casting band 44 can be adjusted to -20 ° C to 40 ° C. A heat transfer medium flow path (not shown) is formed in the rotating rollers 42 and 43 used in this embodiment, and the heat transfer medium maintained at a predetermined temperature passes through the flow path. The temperatures of the rotating rollers 42 and 43 are held at a predetermined value.

  The width of the casting band 44 is not particularly limited, but it is preferable to use a casting band having a width in the range of 1.1 to 2.0 times the casting width of the casting dope 14. Further, it is preferable that the length is 20 m to 200 m, the thickness is 0.5 mm to 2.5 mm, and the surface roughness is polished to be 0.05 μm or less. The casting band 44 is preferably made of stainless steel, and more preferably made of SUS316 so as to have sufficient corrosion resistance and strength. Further, it is preferable to use a non-uniform thickness of the entire casting band 44 of 0.5% or less.

It is also possible to use the rotating rollers 42 and 43 directly as a support. In this case, it is preferable that the rotation can be performed with high accuracy so that the rotation unevenness is 0.2 mm or less. In this case, it is preferable that the average roughness of the surfaces of the rotating rollers 42 and 43 is 0.01 μm or less. Therefore, the surface of the rotating roller is subjected to chrome plating or the like so as to have sufficient hardness and durability. In addition, it is necessary to suppress the surface defects of the support (the casting band 44 and the rotating rollers 42 and 43) to the minimum. Specifically, there is no pinhole of 30 μm or more, and the number of pinholes of 10 μm or more and less than 30 μm is 1 / m ² or less, and the number of pinholes of less than 10 μm is preferably ² / m ² or less.

  The casting die 41, the casting band 44, etc. are accommodated in the casting chamber 81. The casting chamber 81 is provided with a temperature control facility (not shown) for keeping the internal temperature at a predetermined value, and a condenser (condenser) 82 for condensing and recovering the volatile organic solvent. Yes. A recovery device 83 for recovering the condensed and liquefied organic solvent is provided outside the casting chamber 81. Further, it is preferable that a decompression chamber 85 for controlling the pressure of the back surface of the casting bead formed from the casting die 41 to the casting band 44 is disposed, and this is also used in this embodiment. .

  Air blowing ports 87 a, 87 b and 87 c are provided near the peripheral surface of the casting band 44 in order to evaporate the solvent contained in the casting film 16. Further, it is preferable that the wind shielding plate 87d is provided on the downstream side in the vicinity of the casting die 41. Since the wind shielding plate 87d blocks dry air, it is possible to prevent the surface variation of the casting film 16 immediately after casting. In the casting chamber 81, a path (hereinafter referred to as a transport path) through which the casting film 16 is transported by the traveling of the casting band 44 is formed. A stripping roller 89 is provided in the vicinity of the downstream conveyance path. The stripping roller 89 strips off the casting film 16 conveyed by the casting band 44 and sends it as a wet film 18 to the outside of the casting chamber 81.

  The transition portion 90 downstream of the casting chamber 81 is provided with a blower 91, and this blower 91 sends dry air to the wet film 18. The wet film 18 that has passed through the crossing portion 90 is sent to the tenter drying chamber 45 where the end in the width direction is gripped by gripping means such as a clip or a pin, and stretching is performed in the width direction. Further, drying air is introduced into the tenter drying chamber 45, whereby the wet film 18 is dried under certain conditions. It is preferable to divide the inside of the tenter drying chamber 45 into different temperature zones and adjust the drying conditions appropriately for each of the zones. Thus, the tenter drying chamber 45 dries the wet film 18 to obtain the film 22. The film 22 is sent to the ear opener 46. Further, a crusher 93 for finely cutting the waste at the side end portion (referred to as an ear) of the cut film 22 is connected to the ear cutting device 46 downstream of the tenter drying chamber 45.

  The drying chamber 47 is provided with a large number of rollers 100, and an adsorption recovery device 101 for adsorbing and recovering the solvent gas generated by evaporation is attached. The cooling chamber 48 is provided downstream of the drying chamber 47, but a humidity control chamber (not shown) may be provided between the drying chamber 47 and the cooling chamber 48. A forced static elimination device (static elimination bar) 102 for adjusting the charged voltage of the film 22 to a predetermined range (for example, −3 kV to +3 kV) is provided downstream of the cooling chamber 48. Although the forced static elimination apparatus 102 has illustrated the example made into the downstream of the cooling chamber 48, it is not limited to this installation position. Furthermore, in this embodiment, a knurling roller 103 for applying knurling to both edges of the film 22 by embossing is appropriately provided downstream of the forced static elimination device 102. The winding chamber 49 is provided with a winding roller 110 for winding the film 22 and a press roller 111 for controlling the tension at the time of winding.

(Casting die)
As shown in FIGS. 4 and 5, the casting die 41 which is a casting apparatus has lip plates 210 and 211. The lip plates 210 and 211 are each formed with a predetermined hole. By combining the lip plates 210 and 211 so that these holes face each other, the holes provided in the lip plates 210 and 211 form a manifold 215 and a slit 216.

  As shown in FIGS. 5 and 6, side plates 218 and 219 are disposed at both ends of the lip plates 210 and 211. The packing is disposed between the lip plates 210 and 211 and the side plates 218 and 219, and brings the lip plates 210 and 211 and the side plates 218 and 219 into close contact with each other. The manifold 215 has a coat hanger shape. The manifold 215 is provided with a supply port 220 connected to the pipe 61. A slit 216 is formed below the manifold 215. Inner deckle plates 223 and 224 are disposed at both ends of the slit 216 so as to be in close contact with the packing described above. The upstream end 223x (see FIG. 4) of the inner deckle plate 223 extends to the middle of the slit 216. However, the present invention is not limited to this, and the upstream end 223x is the upstream end of the manifold 215. May extend to the middle of the manifold 215 or to the downstream end of the manifold 215. Further, when the adhesion between the lip plates 210 and 211 and the side plates 218 and 219 is high and sufficient sealing properties such as the manifold 215 and the slit 216 can be secured, the packing need not be used.

  The lip plates 210 and 211 have liquid contact surfaces 210a and 211a that are in contact with the casting dope 14 and are flow paths in the longitudinal direction LD of the slits 216, respectively. The inner deckle plates 223 and 224 are cast dope. 14, the liquid contact surfaces 223 a and 224 a, which are the flow path surfaces in the width direction WD of the slits 216, can be contacted. The portions surrounded by the liquid contact surfaces 210a, 211a, 223a, and 224a form the slit 216 and the outlet 41a. The casting dope 14 flowing into the manifold 215 from the supply port 220 flows out from the outflow port 41a in the outflow direction A1 through the slit 216.

  Here, the outflow direction A1 is a direction in which the casting dope 14 flows out from the outflow port 41a. In addition, the downstream end surfaces of the lip plate 211 and the inner deckle plate 223 in the outflow direction A1 are the end surfaces 211b and 223b, the ridges 211c formed by the liquid contact surface 211a and the end surface 211b, and the liquid contact surface 223a and the end surface 223b. A ridge 223c formed by At this time, the lip plate 211 and the inner deckle plate 223 are such that the unevenness of the outlet 41a from which the casting dope 14 flows out, that is, the distance CL1 between the ridge 211c and the ridge 223c in the outflow direction A1 is 9 μm or less. Arranged. Similarly, end surfaces of the lip plate 210 and the inner deckle plate 224 on the downstream side in the outflow direction A1 are end surfaces 210b and 224b, a ridge 210c formed by the liquid contact surface 210a and the end surface 210b, and the liquid contact surface 224a. When the ridge 224c is formed by the edge 224b, the distance CL2 between the ridge 210c and the ridge 223c, the distance CL3 between the ridge 211c and the ridge 224c, and the distance CL4 between the ridge 210c and the ridge 224c are respectively Lip plates 210 and 211 and inner deckle plates 223 and 224 are arranged so as to be 9 μm or less.

  Here, the outflow direction A1 is a direction in which the casting dope 14 flows out from the outflow port 41a. In the outflow direction A1, a tracer substance is injected into the casting dope 14, and an injection trace method for examining the trace by observing the movement trace of each tracer substance or a flow sub-refraction phenomenon of a polymer solution is used. It can be determined by an iso-shear stress surface obtained by a photoelastic device.

(material)
As a material required for the material for forming the lip plates 210 and 211 and the inner deckle plates 223 and 224 constituting the casting die 41, it can withstand oxidation and corrosion due to contact with the casting dope 14, and the like. In order to maintain the distances CL1 to CL4 within a predetermined range, it is preferable to use a material that is less likely to change in dimensions in the casting process. That is, it is preferable to use a material that satisfies the following conditions as a material for forming the lip plates 210 and 211 and the inner deckle plates 223 and 224.
(1) A material having a corrosion resistance substantially equivalent to that of SUS316 in a forced corrosion test with an aqueous electrolyte solution.
(2) Corrosion resistance that does not cause pitting (opening) at the gas-liquid interface even when immersed in a mixed solution of dichloromethane, methanol and water for 3 months.
(3) The coefficient of thermal expansion is 2 × 10 ⁻⁵ (° C. ⁻¹ ) or less.
Therefore, as materials for forming the lip plates 210 and 211 and the inner deckle plates 223 and 224, ceramics and stainless steel, in particular, austenitic stainless steel, particularly SUS316, SUS316L, etc., and precipitation hardening type stainless steel SUS630. SUS631 etc. are preferable.

  An example of the adjustment method of the distances CL1 to CL4 described above will be described. The present invention is not limited to the following adjustment method. First, the lip plates 210 and 211 and the inner deckle plates 223 and 224 are processed into predetermined shapes. Secondly, the lip plates 210 and 211 and the inner deckle plates 223 and 224 are combined (FIG. 7A). Third, distances CL1 to CL4 at the time of combination are measured. In this measurement, the distances CL1 to CL4 are measured in a state where a force is applied from the direction A2 to the inner deckle plate 223 so that the end surface 223d of the inner deckle plate 223 and the surface 211d of the lip plate 211 are in contact with each other. It is preferable to do. The measurement of the distances CL1 to CL4 is the same for the inner deckle plate 224 (not shown). Fourth, the inner deckle plates 223 and 224 are removed, and the end faces 223b and 224b are processed so that the distances CL1 to CL4 are 9 μm or less, respectively. In this way, the unevenness of the outlet formed by the lip plates 210 and 211 and the inner deckle plates 223 and 224, that is, the distances CL1 to CL4 can be adjusted so as to satisfy a predetermined condition (FIG. 7B).

When the above adjustment method is used, the following conditions are satisfied in addition to the conditions (1) to (3) as materials required for the forming material of the lip plates 210 and 211 and the inner deckle plates 223 and 224. preferable.
(4) The volume change rate of the lip plates 210 and 211 and the inner deckle plates 223 and 224 during processing is 0.05% or less.
(5) The hardness of the inner deckle plates 223 and 224 is such that the lip plates 210 and 211 are not damaged.

From the above condition (4), the materials of the lip plates 210 and 211 and the inner deckle plates 223 and 224 may be any material whose volume change rate satisfies the above conditions. Here, the volume change rate is the maximum value of the dimensional change amount a _x , the dimensional change amount a _y , and the dimensional change amount a _z of the inner deckle plates 223 and 224 in the x-axis, y-axis, and z-axis orthogonal coordinate systems. It is. In addition, the dimensional change amount a _x is the amount of dimensional change of the inner deckle plates 223 and 224 when an external force F (approximately 90 N) per unit area (per 1 mm ² ) is applied to the x-axis, and Δb _x is applied. When the previous dimension in the x-axis direction is b _x , it is expressed as Δb _x / b _x . Similarly, the amount of dimensional change a _y, a dimensional change of the inner deckle plates 223, 224 upon application of an external force F in the y-axis and [Delta] b _y, the y-axis direction dimension before the external force F applied b _y when the, as [Delta] b _y / _{b y,} the amount of dimensional change _{a z,} the dimensional change of the inner deckle plates 223, 224 upon application of an external force F in the z-axis and [Delta] b _z, the external force F applied before When the dimension in the z-axis direction is b _z , it is expressed as Δb _z / b _z .

  For the condition (5), for example, when precipitation hardening stainless steel or the like is used as the material of the lip plates 210 and 211, the Vickers hardness is 200 Hv or more as the forming material of the inner deckle plates 223 and 224. It is preferable to use the one with 1000 Hv or less. Therefore, it is preferable to use stainless steel, ceramics, or the like as a material for forming the inner deckle plates 223 and 224. Furthermore, it is preferable to use a magnetic material as the material of the inner deckle plates 223 and 224. When the end faces 223b and 224b are processed, the inner deckle plates 223 and 224 can be fixed by the magnet, so that the processing accuracy of the distances CL1 to CL4 can be further increased.

  The finishing accuracy of the liquid contact surfaces 210a, 211a, 223a, and 224a of the lip plates 210 and 211 and the inner deckle plates 223 and 224 is 1 μm or less in surface roughness, and the straightness is 1 μm / m or less in any direction. It is preferable. Due to the above-mentioned finishing accuracy of the liquid contact surfaces 210a, 211a, 223a, and 224a, it is possible to prevent generation of streaks and unevenness in the casting film formed from the casting dope 14 flowing out from the outlet 41a. The smoothness of the end faces 210b, 211b, 223b, and 224b of the lip plates 210 and 211 and the inner deckle plates 223 and 224 is preferably 2 μm or less at maximum.

Moreover, it is more preferable to form a cured film on the end faces 210b, 211b, 223b, and 224b. A method for forming the cured film is not particularly limited, and examples thereof include ceramic coating, hard chrome plating, and a nitriding method. When ceramics are used as the cured film, those that can be ground, have low porosity, are not brittle, have good corrosion resistance, have good adhesion to the casting die 41, and have no adhesion to the dope are preferable. Examples of the composition of the cured film include tungsten carbide (WC), Al ₂ O ₃ , TiN, Cr ₂ O _{3 and the} like, and WC is particularly preferable. The WC coating can be performed by a thermal spraying method.

  The width of the casting die 41 is not particularly limited, but is preferably 1.1 to 2.0 times the width of the film to be the final product. Moreover, it is preferable to attach a temperature controller to the casting die 41 so that the temperature during film formation is maintained at a predetermined temperature. Furthermore, it is more preferable that thickness adjusting bolts (heat bolts) are provided at predetermined intervals in the width direction of the casting die 41 and the casting die 41 is provided with an automatic thickness adjusting mechanism using a heat bolt. The heat bolt is preferably formed into a film by setting a profile according to the amount of pump 58 (preferably a high precision gear pump) according to a preset program. Further, feedback control may be performed by an adjustment program based on a profile of a thickness meter (for example, an infrared thickness meter) (not shown) in the film manufacturing facility 40. The thickness difference between any two points in the width direction of the product film, excluding the casting edge portion, can be adjusted within 1 μm, and the difference between the minimum value and the maximum value in the width direction thickness can be adjusted to 3 μm or less. Preferably, adjusting to 2 μm or less is more preferable. Moreover, it is preferable to use the one whose thickness accuracy is adjusted to ± 1.5 μm or less. The shear rate of the casting dope 14 in the casting die 41 is preferably adjusted to be 1 (1 / second) to 5000 (1 / second).

  Next, an example of a method for manufacturing the film 22 using the film manufacturing facility 40 as described above will be described below. The dope 11 is always made uniform by the rotation of the stirrer 56. The dope 11 may be mixed with an additive such as a plasticizer during the stirring.

  The dope 11 is sent to the filtration device 59 by the pump 58 and filtered there. The matting agent solution and the ultraviolet absorber solution are mixed in a pipe (not shown), and then stirred and mixed by a static mixer (not shown) to form a uniform additive solution. The additive solution is added to the dope 11 being fed into the pipe 61 (FIG. 1). Thereafter, the mixture is agitated and mixed by the static mixer 60 to form the casting dope 14 having a substantially uniform composition. The mixing ratio of the dope 11, the matting agent solution, and the ultraviolet absorber solution is not particularly limited, but 90 wt%: 5 wt%: 5 wt% to 99 wt%: 0.5 wt%: 0.5 It is preferably in the range of% by weight.

The driving of the rotary rollers 42 and 43 is preferably adjusted so that the tension generated in the casting band 44 is 10 ⁴ N / m to 10 ⁵ N / m. Further, the relative speed difference between the casting band 44 and the rotary rollers 42 and 43 is adjusted to be 0.01 m / min or less. The speed fluctuation of the casting band 44 is preferably 0.5% or less, and the meandering in the width direction when the casting band 44 makes one rotation is preferably 1.5 mm or less. In order to control this meandering, a detector (not shown) for detecting the positions of both ends of the casting band 44 is provided, and feedback control is performed on a position controller (not shown) of the casting band 44 based on the measured value. More preferably, the position of the casting band 44 is adjusted. Furthermore, it is preferable to adjust the casting band 44 immediately below the casting die 41 so that the positional fluctuation in the vertical direction accompanying the rotation of the rotary rollers 42 and 43 is 200 μm or less. Moreover, it is preferable that the temperature of the casting chamber 81 is -10 degreeC-57 degreeC with temperature control equipment (not shown). The solvent evaporated in the casting chamber 81 is condensed and liquefied by the condenser 82 and then recovered by the recovery device 83, and then regenerated and reused as a dope preparation solvent.

  The casting die 41 flows out the casting dope 14 from the outlet 41a. A casting bead is formed from the casting die 41 to the casting band 44, and the casting film 16 is formed on the casting band 44. The temperature of the casting dope 14 during casting is preferably -10 ° C to 57 ° C. Further, in order to stabilize the casting bead, the back surface of the casting bead is preferably controlled to a desired pressure value by the decompression chamber 85. The back surface of the bead is preferably decompressed in the range of −2000 Pa to −10 Pa than the front surface. Further, it is preferable that a jacket (not shown) is attached to the decompression chamber 85 and the temperature is controlled so that the internal temperature is kept at a predetermined temperature. The temperature of the decompression chamber 85 is not particularly limited, but is preferably set to be equal to or higher than the condensation point of the organic solvent used. In order to keep the shape of the casting bead desired, it is preferable to attach a suction device (not shown) to the edge portion of the casting die 41. The edge suction air volume is preferably in the range of 1 L / min to 100 L / min. The details when the casting dope 14 flows out from the outlet 41a will be described later.

  The casting film 16 moves as the casting band 44 travels. At this time, drying air is applied to the casting film 16 through the air blowing ports 87a to 87c to promote evaporation of the solvent. And although the surface shape of the casting film 16 may fluctuate by blowing of this dry wind, the wind-shielding board 87d has suppressed this fluctuation | variation. The surface temperature of the casting band 44 is preferably −20 ° C. to 40 ° C.

  After the casting film 16 has a self-supporting property, the casting film 16 is peeled off from the casting band 44 while being supported by the peeling roller 89 as the wet film 18, and is sent to the transfer portion 90. The amount of residual solvent at the time of stripping is preferably 20% by weight to 250% by weight on a dry basis. In the transfer section 90, the wet film 18 is sent to the tenter drying chamber 45 using a large number of rollers while the drying of the wet film 18 is advanced by blowing dry air at a desired temperature from the blower 91. In the transition section 90, it is also possible to apply a draw tension to the wet film 18 by making the rotational speed of the downstream roller faster than the rotational speed of the upstream roller.

  The wet film 18 sent to the tenter drying chamber 45 is supported at both ends by a holding means such as a clip at the entrance. By this supporting means, the wet film 18 is dried under predetermined conditions while moving in the tenter drying chamber 45, and becomes a film 22. Then, the film 22 released from the carrying by the carrying means is sent out to the crusher 93 by the roller.

  The wet film 18 is dried to a predetermined residual solvent amount in the tenter drying chamber 45, and then sent out as a film 22 to a downstream ear cutting device 46. Both side edges of the film 22 are cut at both edges by the edge-cutting device 46. The cut side end portion is sent to the crusher 93 by a cutter blower (not shown). By the crusher 93, the film side end is crushed into chips. Since this chip is reused for dope preparation, this method is effective in terms of cost. In addition, although it can also be skipped about the cutting process of this film both ends, it is preferable to carry out in any one from the said casting process to the process of winding up the said film.

  The film 22 from which both side ends have been removed is sent to the drying chamber 47 and further dried. Although the temperature in the drying chamber 47 is not specifically limited, It is preferable that it is the range of 50 to 160 degreeC. In the drying chamber 47, the film 22 is conveyed while being wound around the roller 100, and the solvent gas generated by evaporation is adsorbed and recovered by the adsorption recovery device 101. The air from which the solvent component has been removed is blown again as dry air inside the drying chamber 47. The drying chamber 47 is more preferably divided into a plurality of sections in order to change the drying temperature. In addition, when a preliminary drying chamber (not shown) is provided between the ear opener 46 and the drying chamber 47 and the film 22 is preliminarily dried, the film temperature is prevented from abruptly rising in the drying chamber 47. The shape change of the film 22 can be further suppressed.

  The film 22 is cooled to approximately room temperature in the cooling chamber 48. Note that a humidity control chamber (not shown) may be provided between the drying chamber 47 and the cooling chamber 48, and it is preferable to blow air adjusted to a desired humidity and temperature onto the film 22 in the humidity control chamber. . Thereby, generation | occurrence | production of the curling of the film 22 or the winding defect at the time of winding can be suppressed.

  Further, the forcible static elimination device (static elimination bar) 102 sets the charged voltage while the film 22 is being conveyed to a predetermined range (for example, −3 kV to +3 kV). Although FIG. 3 illustrates an example provided on the downstream side of the cooling chamber 48, the position is not limited thereto. Furthermore, it is preferable to provide a knurling roller 103 so as to give knurling to both edges of the film 22 by embossing. In addition, it is preferable that the unevenness | corrugation of the knurled location is 1 micrometer-200 micrometers.

  Finally, the film 22 is taken up by the take-up roller 110 in the take-up chamber 49. At this time, it is preferable to wind the sheet while applying a desired tension with the press roller 111. More preferably, the tension at the time of winding is gradually changed from the start to the end of winding. The film 22 wound around the winding roller 110 is preferably at least 100 m in the longitudinal direction (casting direction). The width of the film 22 is preferably 600 mm or more, and more preferably 1400 mm or more and 2500 mm or less. The present invention is also effective when it is larger than 2500 mm. The present invention is also applied when manufacturing a thin film having a thickness of 20 μm or more and 80 μm or less.

  Next, details of when the casting die 41 flows out of the casting dope 14 in the casting step 17 (see FIG. 1) will be described. As shown in FIGS. 3 and 6, in the casting process 17 (see FIG. 1), the casting dope 14 passes through the supply port 220, the manifold 215, and the slit 216. In the slit 216, the casting dope 14 flows toward the outlet 41a while the width is regulated by the liquid contact surfaces 223a and 224a and the thickness is regulated by the liquid contact surfaces 210a and 211a. The casting dope 14 flows out from the outflow port 41a of the casting die 41 in the outflow direction A1. Since the unevenness of the outlet 41a, that is, the distances CL1 to CL4 between the edges 210c and 211c and the edges 223c and 224c are 9 μm or less in the outlet direction A1, the casting dope 14 flowing out from the outlet 41a is in the vicinity of the outlet 41a. It flows out on the casting band 44 without staying in the area. Thus, the casting die 41 can form the casting film 16 on the casting band 44 without forming a skin.

  Although detailed knowledge about the size of the distances CL1 to CL4 and the causal relationship of the occurrence of skinning of the casting dope 14 has not been obtained, the following can be considered for the effect of the present invention. A die swell phenomenon occurs when the dope 14 which is a viscoelastic fluid flows out from the outlet 41a. This die swell phenomenon is said to occur because the viscoelastic fluid is subjected to elastic shear strain due to the flow in the tube, and this strain is recovered near the outlet of the tube. Generally, the distances CL1 to CL4 are not 0 in a casting die composed of a pair of lip plates and an inner deckle plate. The casting dope flowing out from the outlet of the casting die in the outflow direction A1 passes through a state where it is in contact with the liquid contact surface in one direction but is not in contact with the liquid contact surface in the other direction. Among the casting dopes in such a state, the casting dope not in contact with the liquid contact surface expands as a result of recovery of elastic shear strain due to the die swell phenomenon, while the casting dope in contact with the liquid contact surface. Does not recover elastic shear strain. As described above, when the state in which the elastic shear strain is locally recovered continues for a certain period, the entire flow of the casting dope is disturbed, and the disturbance of the flow of the casting dope is caused on the wetted surface. It induces the residence of the casting dope in contact. Further, the disturbance of the flow of the casting dope increases as CL1 to CL4 increase. In the present invention, since the distances CL1 to CL4 are 9 μm or less, retention of the casting dope due to the die swell phenomenon can be prevented. Therefore, according to the present invention, the change in the shape of the casting dope 14 caused by the die swell phenomenon is suppressed, and as a result, the adhesion and retention of the casting dope 14 to the lip plates 210 and 211 that induce skinning are avoided. be able to.

  The present invention does not depend on the outflow speed at which the casting dope 14 flows out from the outlet 41a, the shape of the outlet 41a, and the viscoelasticity of the casting dope 14 used for solution casting, in any case. An effect of suppressing the occurrence of skinning can be expressed. Therefore, the present invention can be widely applied to a solution casting method for producing various films.

  The solution casting method, the solution casting apparatus, and the casting die 41 of the present invention can perform the casting step 17 while suppressing the retention of the casting dope 14 that induces the occurrence of skinning. There is no need to remove the skin during film formation, such as washing the support. Therefore, according to this invention, a film can be manufactured efficiently. Considering speeding up of the solution casting method, speeding up the casting process is one of the major problems. In order to increase the speed, it is unavoidable to increase the degree of decompression of the decompression chamber 85 as well as to increase the transport speed of the casting band 44. However, the present invention is also effective in increasing the speed of solution casting. The stable casting process 17 can be performed without generating. Furthermore, since the effect of the present invention is exhibited even in an outflow device having an outlet 41a of any shape, an outflow having an outlet having a rectangular shape, which has conventionally been considered to cause retention of the casting dope 14 easily. It is also possible to apply to an apparatus or the like. Furthermore, the present invention can eliminate not only the occurrence of skinning, but also a factor that occurs due to dope retention and adversely affects the solution casting method. As an unfavorable factor, for example, there is a die line formed inside the vicinity of the die lip, that is, a dope nucleus formed on the liquid contact surfaces 210a, 211a, 223a, and 224a.

  Furthermore, the present invention is not limited to casting dies, solution casting equipment, and solution casting methods, and is preferably caused by die swell phenomenon or dwell caused by die swell phenomenon in the step of flowing out the viscoelastic fluid. Non-existent factors (eg die line etc.) can be eliminated.

  In the above-described embodiment, the case where the end faces 210b, 211b, 223b, and 224b of the members 210, 211, 223, and 224 forming the outlet 41a are parallel is illustrated and described. The cases where the end faces 210b, 211b, 223b, 224b of the members 210, 211, 223, 224 are parallel are rare. However, the present invention can be applied even when the end faces 210b, 211b, 223b, and 224b are not parallel. That is, among the members constituting the outlet 41a, a ridge formed from the liquid contact surface and end surface of one member and a ridge formed from the liquid contact surface and end surface of another member adjacent to the one member. If the distance between and the amount of protrusion is 9 μm or less in the outflow direction A1, the effect of the present invention can be exhibited. Therefore, even when the inner deckle plates 223 and 224 are provided so as to protrude with respect to the side plates 210 and 211 in the outflow direction A1, the side plates 210 and 211 are in contact with the inner deckle plates 223 and 224 in the outflow direction A1. Even if it is provided so as to protrude, the effect of the present invention can be exhibited if the protruding amount is 9 μm or less. In addition, when there is no unevenness in the outflow direction A1 of the outflow port, such as when the outflow port is formed from one outflow forming member, this “unevenness is 9 μm or less”. The effect of the invention is manifested.

  In order to shorten the state in which elastic shear strain recovery locally occurs that induces dope retention, the amount of protrusion as described above is not limited to a predetermined value or less. Regardless of whether the number of members to be formed is one or more, attention should be paid to the bending amount of the downstream end in the outflow direction A1 on the inner peripheral surface of the dope channel. For example, when the downstream end of the outflow direction A1 of the inner peripheral surface of the dope channel is bent in the outflow direction A1, the bending amount in the outflow direction A1 may be 9 μm or less. Here, in the case where inner deckle plates 223 and 224 are provided at the downstream end of the inner peripheral surface of the dope channel in the outflow direction A1 so as to protrude from the side plates 210 and 211 in the outflow direction A1, the ridge 210c, In addition to 211c, 223c, and 224c, liquid contact surface end portions 223x, 223y, 224x, and 224y that connect these edges 210c, 211c, 223c, and 224c are included. The liquid contact surface end 223x is the end of the liquid contact surface 223a connecting the ridge 210c and the ridge 223c, and the liquid contact surface end 223y is the end of the liquid contact surface 223a connecting the ridge 211c and the ridge 223c, The liquid contact surface end 224x is an end of the liquid contact surface 224a connecting the ridge 210c and the ridge 224c, and the liquid contact surface end 224y is an end of the liquid contact surface 224a connecting the ridge 211c and the ridge 224c. Similarly, when the side plates 210 and 211 are provided so as to protrude in the outflow direction A1 from the inner deckle plates 223 and 224, the ridge 210c is formed at the downstream end in the outflow direction A1 of the inner peripheral surface of the dope channel. , 211c, 223c, and 224c, and end portions in the longitudinal direction LD of the liquid contact surfaces 210a and 211a that connect these ridges 210c, 211c, 223c, and 224c. In addition, it is preferable that the downstream end of the outflow direction A1 of the inner peripheral surface of the dope channel is formed in a curved shape.

  Since the dope used in the solution casting method is a viscoelastic fluid, both ends of the casting bead formed from the outlet to the support become thick due to the neck-in phenomenon (hereinafter referred to as ear thickness failure). Even if a film is produced from such a casting bead, both ends of the film cannot be used as a product and are discarded, resulting in a reduction in the production efficiency of the film. In addition, in a film manufacturing process, a cast film having a thick film at both ends induces a decrease in adhesion to the support, does not sufficiently develop self-support on the support, or a transport roller, etc. It will cause wrapping around.

  It is known that the neck-in phenomenon that induces the ear thickness failure is more prominent as the viscosity of the dope increases and the air gap from the outlet to the support increases. In order to reduce the viscosity of the dope, it is necessary to change the composition of the polymer or use a dope having a low polymer concentration. Changing the composition of the polymer is undesirable because it imposes limitations on the optical properties of the resulting film, and using a dope with a low polymer concentration makes it difficult to develop self-supporting properties in the cast film, resulting in production. Sex goes down.

  Therefore, in order to prevent the adverse effects caused by the neck-in phenomenon of the casting dope 14, the air gap AG (see FIG. 3) is preferably 100 mm or less, more preferably 10 mm or less, and 5 mm or less. Is more preferable. The air gap AG is the shortest distance between the surface of the support body such as the casting band 44 and the ridges 210 c, 211 c, 223 c, 224 c formed on the casting die 41. In order to avoid damage to the casting band 44 due to contact between the casting band 44 and the inner deckle plates 223 and 224 formed of a hard material, the air gap AG is preferably 0.1 mm or more. The adjustment of the air gap AG may be determined by the arrangement position of the casting die 41, the size of the above-described CL1 to CL4, the vertical position fluctuation of the casting band 44 caused by traveling, and the like.

  Furthermore, in order to reduce the air gap AG, the liquid contact surfaces 210a, 211a, 223a, and 224a are preferably formed so that the edges 223c and 224c are closer to the casting band 44 than the edges 210c and 211c. For the purpose of preventing the occurrence of skinning only, the liquid contact surfaces 210a, 211a, 223a, and 224a are formed so that the ridges 210c and 211c are closer to the casting band 44 than the ridges 223c and 223c. May be.

  Conventionally, when the air gap AG is made small, in order to avoid damage to the casting band 44 due to contact with the inner deckle plates 223 and 224 when the air gap AG is adjusted or when the casting dope 14 is cast. In addition, a resin-made inner deckle plate such as Teflon (registered trademark) is provided. However, since the present invention provides the inner deckle plate from a hard material such as stainless steel or ceramic, CL1 as shown in FIG. High accuracy can be achieved in the adjustment of CL4 and the adjustment of the air gap AG. Therefore, according to the present invention, it is possible to prevent the occurrence of skinning while preventing the harmful effects caused by the neck-in phenomenon.

  In order to avoid adverse effects due to the die swell phenomenon and the neck-in phenomenon, the viscosity of the casting dope 14 flowing out from the outlet 41a of the casting die 41 is preferably 10 Pa · s or more and 200 Pa · s or less.

  In the above embodiment, the casting die 41 having the inner deckle plates 223 and 224 in which the distance between the liquid contact surface 223a and the liquid contact surface 224a is substantially constant is used, but the present invention is limited to this. Absent. Below, the 2nd-4th casting die of this invention is demonstrated. The same parts and members as those of the casting die 41 described above are denoted by the same reference numerals, and detailed description thereof is omitted.

  As shown in FIGS. 8 and 9, the casting die 400 is provided with a supply port 220 connected to the pipe 61 into which the casting dope flows, and an outlet 400 a through which the casting dope flows through the supply port 220. The casting die 400 includes a pair of lip plates 410 and 411 and a pair of side plates 218 and 219. Furthermore, inner deckle plates 423 and 424 are arranged via packings between the side plates 219 and 218 arranged to face each other. The liquid contact surfaces 410a and 411a are formed on the pair of lip plates 410 and 411, respectively. Liquid contact surfaces 423a and 424a are formed on the pair of inner deckle plates 423 and 424, respectively. The liquid contact surfaces 410a and 411a and the liquid contact surfaces 423a and 424a form a manifold 415 connected to the supply port 220 and a slit 416 connecting the manifold 415 and the outlet 400a.

  Further, the liquid contact surface 411a is provided with an upper liquid contact surface 450, a middle indirect liquid surface 451 is provided on the downstream side of the upper liquid contact surface 450 in the outflow direction A1, and a lower portion from the downstream side toward the outlet 400a. A liquid contact surface 452 is provided. When the interval between the upper liquid contact surface 450 and the liquid contact surface 410a is TH1, and the interval between the lower liquid contact surface 452 and the liquid contact surface 410a is TH2, the upper liquid contact surface 450 and the lower liquid contact surface 452 are Each is formed so that TH1> TH2. Further, the intermediate indirect liquid surface 451 is formed such that the distance from the liquid contact surface 410a gradually decreases from the upstream side to the downstream side in the outflow direction A1, that is, from TH1 to TH2. Thus, the casting dope has the slit 416 while the thickness is limited to TH1 by the upper liquid contact surface 450 and the liquid contact surface 410a, while the thickness is limited to TH2 by the lower liquid contact surface 452 and the liquid contact surface 410a. Then, it is guided to the outlet 400a.

  Further, the interval W1 between the liquid contact surface 423a and the liquid contact surface 424a is substantially constant as a whole between the manifold 415 and the slit 416, and the slit 416 near the outlet 400a is substantially constant as the outlet 400a is approached. The liquid contact surface 423a and the liquid contact surface 424a are formed so as to be gradually widened at the ratio. Such liquid contact surfaces 423a and 424a can reduce the thickness of both ends of the casting bead, so that an ear thickness failure can be avoided.

  In the above embodiment, the intermediate indirect liquid level 451 is downstream from the position where the interval W1 between the liquid contact surface 423a and the liquid contact surface 424a begins to increase when viewed from the outflow direction A1 (hereinafter referred to as the widening start position). However, the present invention is not limited to this, and the mid-indirect liquid level may be formed to extend from the position upstream of the widening start position toward the outlet 400a. Good.

  Instead of the casting die 400 described above, as shown in FIG. 10, the liquid contact surface 523a and the liquid contact surface 524a are gradually widened toward the outlet 500a, and in the vicinity of the outlet 500a. The casting die 500 that is formed may be used so that the change rate of the interval W1 is gradually reduced.

  In the above embodiment, the interval between the liquid contact surfaces of the inner deckle plate is gradually increased near the outlet, but the present invention is not limited to this, and as shown in FIG. The casting die 600 is such that the interval W1 between the liquid contact surfaces 623a and 624a of the holes 623 and 624 increases at a predetermined rate from the upstream end of the slit 616 connected to the manifold 615 to the outlet port 600a. It may be used.

  In the above embodiment, a plate-like inner deckle plate is used, but the present invention is not limited to this, and the inner deckle member having a liquid contact surface that regulates the width of the dope flowing out from the outlet is also in its shape. Regardless, it is included naturally.

  In the above embodiment, the casting film 16 formed on the casting band 44 is dried to allow the casting film 16 to exhibit self-supporting properties. However, the present invention is not limited thereto, and the casting film 16 is cooled by cooling. It can also be applied to a solution casting method in which a gel is gelled to develop self-supporting properties. In particular, the method of gelling the cast film 16 by cooling requires a shorter time to develop self-supporting properties than the method of drying the cast film and has less adverse effects due to rapid cooling. Suitable for In addition, the traveling casting band 44 (see FIG. 3) is used as the support, but instead, a casting drum that rotates about an axis may be used as the support.

  The present invention is not limited to the above embodiment, and when flowing out the dope 11, a method of simultaneously laminating or co-casting two or more kinds of dopes may be used. When performing simultaneous lamination and co-casting, a casting die to which a feed block is attached may be used, or a multi-manifold casting die may be used. As for the film which consists of a multilayer by co-casting, it is preferable that any one of the two layers exposed on the surface is 0.5% to 30% of the total thickness of the film. Further, in the case of simultaneous lamination co-casting, the concentration of each dope is set in advance so that when the dope is cast from the die slit to the support, the high-viscosity dope is wrapped and cast by the low-viscosity dope. It is preferable to adjust. In the case of simultaneous lamination and co-casting, the bead formed from the die slit to the support is in contact with the outside world, that is, the exposed dope has a larger proportion of the poor solvent than the internal dope. It is preferable.

  From decompression chamber, support structure etc., co-casting, peeling method, stretching, drying conditions of each process, handling method, curling, winding method after flatness correction, solvent recovery method, film recovery method, etc. The details are described in paragraphs [0617] to [0889] of 2005-104148. These descriptions are also applicable to the present invention.

[Performance / Measurement method]
The performance of the wound cellulose acylate film and the measuring method thereof are described in paragraphs [0112] to [0139] of JP-A-2005-104148. These are also applicable to the present invention.

[surface treatment]
It is preferable that at least one surface of the cellulose acylate film is surface-treated. The 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 cellulose acylate film may be undercoated.

  Further, it is preferable to use the cellulose acylate film as a base film as a functional material provided with another functional layer. The functional layer is preferably provided with at least one layer selected from an antistatic layer, a cured resin layer, an antireflection layer, an easy adhesion layer, an antiglare layer and an optical compensation layer.

The functional layers preferably contain at least one surfactant 0.1mg ^{/ m 2} ~1000mg ^/ m 2 containing. Further, the functional layers preferably contain at least one sort of plasticizers in the 0.1mg ^{/ m 2} ~1000mg ^/ m 2 containing. Further, the functional layers preferably contain at least one sort of matting agents in the 0.1mg ^{/ m 2} ~1000mg ^/ m 2 containing. Further, the functional layers preferably contain at least one sort of antistatic agents ^1mg / ^{m 2 ~1000mg} / m 2 containing. In addition to the above, the method for applying a surface-treated functional layer to cellulose acylate film to realize various functions and characteristics is described in detail in paragraphs [0890] to [1087] of JP-A-2005-104148. It also includes the conditions and methods. These are also applicable to the present invention.

(Use)
The cellulose acylate film is particularly useful as a polarizing plate protective film. Usually, two polarizing plates each having a cellulose acylate film bonded to a polarizer are bonded to a liquid crystal layer to produce a liquid crystal display device. However, the arrangement of the liquid crystal layer and the polarizing plate is not limited, and various known arrangements can be employed. Japanese Patent Application Laid-Open No. 2005-104148 describes in detail TN type, STN type, VA type, OCB type, reflective type, and other examples of liquid crystal display devices. This method can also be applied to the present invention. The application also describes a cellulose acylate film provided with an optically anisotropic layer and a cellulose acylate film provided with antireflection and antiglare functions. Furthermore, the use as an optical compensation film is also described as a biaxial cellulose acylate film imparting appropriate optical performance. This can also be used as a polarizing plate protective film. These descriptions are also applicable to the present invention. Details are described in paragraphs [1088] to [1265] of JP-A-2005-104148.

  Moreover, the cellulose triacetate film (TAC film) which is excellent in an optical characteristic by the manufacturing method of this invention can be obtained. The TAC film can be used as a polarizing plate protective film or a base film of a photographic photosensitive material. Further, it can be used as an optical compensation film for improving the viewing angle dependency of a liquid crystal display device for television. In particular, it is effective for applications that also serve as a protective film for a polarizing plate. Therefore, it is used not only in the conventional TN mode but also in the IPS mode, OCB mode, VA mode, and the like. Moreover, you may comprise a polarizing plate using the said film for polarizing plate protective films.

  In addition to the optical film as described above, the present invention may be a polymer film produced by a solution casting method. For example, there is a solid electrolyte film as a proton conductive material used in a fuel cell. In addition, the polymer used for this invention is not limited to a cellulose acylate, A well-known polymer can be used.

  Next, examples of the present invention will be described. In the following Examples, Examples 1 and 2 are examples of the embodiment of the present invention, and Examples 3 to 5 are comparative experiments with respect to Examples 1 and 2. The description will be made in detail in the first embodiment, and in the second to fifth embodiments according to the present invention, the description of the same conditions as in the first embodiment will be omitted.

  Next, Example 1 of the present invention will be described. The formulation for preparing the polymer solution (dope) used for film production is shown below.

[Preparation of dope]
The prescription of the compound used for the preparation of the dope 11 is shown below.
Cellulose triacetate (substitution degree 2.8) 89.3% by weight
Plasticizer A (triphenyl phosphate) 7.1% by weight
Plasticizer B (biphenyldiphenyl phosphate) 3.6% by weight
92% by weight of solid content (solute) having a composition ratio of dichloromethane
8% by weight of methanol
The dope 11 was prepared by appropriately adding to a mixed solvent consisting of The solid content concentration of the dope 11 was adjusted to 19.3% by weight. The dope 11 is filtered through a filter paper (Toyo Filter Paper Co., Ltd., # 63LB), further filtered through a sintered metal filter (Nihon Seisen Co., Ltd. 06N, nominal pore size 10 μm), and further filtered through a mesh filter. Placed in tank 39.

[Cellulose triacetate]
The cellulose triacetate used here has a residual acetic acid content of 0.1% by weight or less, a Ca content of 5 ppm, a Mg content of 70 ppm, a Fe content of 0.5 ppm, free acetic acid of 40 ppm, It contained 15 ppm of sulfate ion. The degree of substitution of the acetyl group with respect to the hydrogen at the 6-position hydroxyl group was 0.91. Further, 32.5% of all acetyl groups were acetyl groups in which the hydrogen of the hydroxyl group at the 6-position was substituted. Moreover, the acetone extraction part which extracted this TAC with acetone was 8 weight%, and the weight average molecular weight / number average molecular weight ratio was 2.5. The obtained TAC had a yellow index of 1.7, a haze of 0.08, and a transparency of 93.5%. This TAC is synthesized using cellulose collected from cotton as a raw material. In the following description, this is called cotton raw material TAC.

[Preparation of matting agent solution]
A matting agent solution was prepared from the following formulation. In addition, the same thing as what was used for preparation of dope 11 was used for TAC.
Silica (Aerosil R972 manufactured by Nippon Aerosil Co., Ltd.) 0.67% by weight
Cellulose triacetate 2.93% by weight
Triphenyl phosphate 0.23% by weight
Biphenyl diphenyl phosphate 0.12% by weight
Dichloromethane 88.37 wt%
Methanol 7.68% by weight
A matting agent solution was prepared from the above formulation, dispersed with an attritor so that the volume average particle size was 0.7 μm, and then filtered with an Astropore filter manufactured by Fuji Photo Film Co., Ltd. And it put into the tank for mat agent liquids.

[Preparation of UV absorber solution]
An ultraviolet absorber solution was prepared from the following formulation. In addition, the same thing as what was used for preparation of dope 11 was used for TAC.
2 (2′-hydroxy-3 ′, 5′-di-tert-butylphenyl) -5-chlorobenzotriazole 5.83% by weight
2 (2′-hydroxy 3 ′, 5′-di-tert-amylphenyl) benzotriazole 11.66% by weight
Cellulose triacetate 1.48% by weight
Triphenyl phosphate 0.12% by weight
Biphenyl diphenyl phosphate 0.06% by weight
Dichloromethane 74.38 wt%
Methanol 6.47% by weight
An ultraviolet absorber solution was prepared from the above formulation, filtered through an astropore filter manufactured by Fuji Photo Film Co., Ltd., and then placed in a tank for an ultraviolet absorber solution.

  Moreover, the mixed solvent A of 86.5 weight part of dichloromethane, 13 weight part of acetone, and 0.5 weight part of 1-butanol was produced.

  The matting agent solution was mixed with the ultraviolet absorber solution, and the mixture was stirred with a static mixer to obtain an additive solution. The dope 11 was fed into the pipe 61 by the pump 58, filtered through the filtration device 59, and then mixed with the additive solution. The solution was mixed and stirred with a static mixer 60 to obtain a casting dope 14.

  The film 22 was manufactured using the film manufacturing equipment 40 shown in FIG. The pump 58 has a function of increasing the pressure on the primary side, and liquid was fed by performing feedback control on the upstream side of the pump 58 with an inverter motor so that the pressure on the primary side became 0.8 MPa. A pump 58 having a volume efficiency of 99.2% and a flow rate fluctuation rate of 0.5% or less was used. The outflow pressure was 1.5 MPa.

  As an outflow device, a casting die 41 including lip plates 210 and 211 formed of SUS316 having a volume change rate of 0.002%, side plates 218 and 219, and inner deckle plates 223 and 224 was used. The finishing accuracy of the liquid contact surfaces 210a, 211a, 223a, and 224a of the lip plates 210 and 211 and the inner deckle plates 223 and 224 is 1 μm or less in terms of surface roughness, and the straightness is 1 μm / m or less in any direction. It was. About this casting die 41, distance CL1-CL4 was adjusted to 2 micrometers or less. And the casting process was performed by adjusting the flow rate of the casting dope 14. The casting width of the casting dope 14 from the outlet 41a of the casting die 41 was 1700 mm. The casting speed was 45 m / min to 55 m / min. In order to adjust the temperature of the casting dope 14 to 36 ° C., a jacket (not shown) is provided on the casting die 41 and the inlet temperature of the heat transfer medium supplied into the jacket is set to approximately 36 ° C.

  A microscope with a resolution of 1 μm was used to measure the dimensions of the lip plates 210 and 211 and the inner deckle plates 223 and 224 for calculating the volume change rate and the amount of change.

  The casting die 41 and the piping were all kept at approximately 36 ° C. during film formation. As the casting die 41, a coat hanger type die was used. The casting die 41 was provided with thickness adjusting bolts provided at a pitch of 20 mm and equipped with an automatic thickness adjusting mechanism using a heat bolt. This heat bolt can also set a profile according to the amount of liquid delivered by the pump 58 by a preset program, and is fed back by an adjustment program based on the profile of an infrared thickness meter (not shown) installed in the film manufacturing facility 40. The thing which has the performance which can also be controlled was used. In the film excluding the end portion of 20 mm, the thickness difference between two arbitrary points separated by 50 mm was within 1 μm, and the thickness variation in the width direction was adjusted to 3 μm / m or less. The overall thickness was adjusted to ± 1.5% or less.

  Further, a decompression chamber 85 for decompressing this portion was installed on the primary side of the casting die 41. The degree of decompression of the decompression chamber 85 is adjusted so that a pressure difference of 1 Pa to 5000 Pa is generated before and after the casting bead, and this adjustment is made according to the casting speed. At that time, the pressure difference on both sides of the casting bead was set so that the length of the casting bead was 20 mm to 50 mm. A jacket (not shown) was attached to make the internal temperature of the decompression chamber 85 constant at a predetermined temperature. A heat transfer medium adjusted to 35 ° C. was supplied into the jacket. Further, the decompression chamber 85 used was equipped with a mechanism that can be set to a temperature higher than the condensation temperature of the gas around the casting part. Labyrinth packings (not shown) were provided on the front and back portions of the beads at the outlet 41a.

As a material for forming the lip plates 210 and 211, the side plates 218 and 219, and the inner deckle plates 223 and 224, stainless steel having a thermal expansion coefficient of 2 × 10 ⁻⁵ (° C. ⁻¹ ) or less was used. This had a corrosion resistance substantially equal to that of SUS316 in a forced corrosion test with an aqueous electrolyte solution. Further, even when immersed in a mixed solution of dichloromethane, methanol and water for 3 months, it had corrosion resistance that did not cause pitting (opening) at the gas-liquid interface. The finishing precision of the wetted surface of the casting die 41 was 1 μm or less in terms of surface roughness, the straightness was 1 μm / m or less in any direction, and the slit clearance was adjusted to 1.5 mm. About the corner | angular part of the liquid-contact part of the lip tip of the casting die 41, what was processed so that R might be set to 50 micrometers or less over the full width of a slit was used. The shear rate of the casting dope 14 inside the casting die 41 was in the range of 1 (1 / second) to 5000 (1 / second). Further, a WC (tungsten carbide) coating was applied to the lip end of the casting die 41 by a thermal spraying method to provide a cured film.

  A stainless steel endless band having a width of 1.9 m and a length of 70 m was used as the casting band 44 as a support. The casting band 44 was polished so that the thickness was 1.5 mm and the surface roughness was 0.05 μm or less. The material is made of SUS316 and has sufficient corrosion resistance and strength. The thickness unevenness of the entire casting band 44 was 0.5% or less. The casting band 44 was driven by two rotating rollers 42 and 43. Further, the relative speed difference between the casting band 44 and the rotating rollers 42 and 43 was adjusted to be 0.01 m / min or less. At this time, the speed fluctuation of the casting band 44 was set to 0.5% or less. Further, both end positions of the casting band 44 were detected and controlled so that the meandering in the width direction of one rotation was limited to 1.5 mm or less. The positional variation in the vertical direction between the tip of the die lip and the casting band 44 immediately below the casting die 41 was set to 200 μm or less. The casting band 44 was installed in a casting chamber 81 having wind pressure fluctuation suppressing means (not shown).

As the rotating rollers 42 and 43, those capable of feeding a heat transfer medium therein were used so that the temperature of the casting band 44 could be adjusted. A 5 ° C. heat transfer medium was passed through the rotating roller 42 on the casting die 41 side, and a 40 ° C. heat transfer medium was passed through the other rotating roller 43 for drying. The surface temperature of the central part of the casting band 44 immediately before casting was 15 ° C., and the temperature difference between both side ends was 6 ° C. or less. The casting band 44 preferably has no surface defects, has no pinholes of 30 μm or more, has no pinholes of 10 μm to 30 μm, 1 pin / m ² or less, and ² pinholes of less than 10 μm / Those with m ² or less were used.

  The casting film 16 formed from the casting dope 14 cast on the casting band 44 was first fed with drying air flowing parallel to the casting film 16 to dry the casting film 16. As for the temperature of the drying air, 140 ° C. drying air was blown from the upstream air blowing port 87 a above the casting band 44. Further, 140 ° C. dry air was blown from the air blowing port 87b on the downstream side, and 65 ° C. dry air was blown from the air blowing port 87c below the casting band 44. The oxygen concentration in the dry atmosphere on the casting band 44 was kept at 5 vol%. In order to maintain this oxygen concentration at 5 vol%, the air was replaced with nitrogen gas. Further, in order to condense and recover the solvent in the casting chamber 81, a condenser (condenser) 82 was provided, and its outlet temperature was set to -3 ° C.

  The static pressure fluctuation in the vicinity of the casting die 41 was suppressed to ± 1 Pa or less. After the casting film 16 had a self-supporting property, it was peeled off as the wet film 18 while being supported by the peeling roller 89 from the casting band 44. In order to suppress the peeling failure, the peeling speed (peeling roller draw) was appropriately adjusted in the range of 100.1% to 110% with respect to the speed of the casting band 44. The solvent gas generated by drying was condensed and liquefied by a condenser 82 at -3 ° C. and recovered by a recovery device 83. The recovered solvent was adjusted so that the water content was 0.5% or less. The drying air from which the solvent was removed was heated again and reused as drying air. The wet film 18 was conveyed through the two rollers of the cross section 90 and sent to the tenter drying chamber 45. In the crossing section 90, 60 ° C. dry air was blown from the blower 91 to the wet film 18. The magnification (tenter driving draw) from the peeling roller 89 to the entrance of the tenter drying chamber 45 was 103.0%.

  The wet film 18 sent to the tenter drying chamber 45 sequentially passed through each section provided in the tenter drying chamber 45 while both ends thereof were supported by clips. During the transport in the tenter drying chamber 45, the wet film 18 was subjected to a predetermined drying process and a stretching process, and then sent out as a film 22 from the tenter drying chamber 45 to the ear clip device 46.

  The solvent evaporated in the tenter drying chamber 45 was provided with a condenser (condenser) for condensation and recovery, condensed at a temperature of −3 ° C., liquefied and recovered. The condensed solvent was reused after adjusting the water content to 0.5 wt% or less.

Within 30 seconds from the exit of the tenter drying chamber 45, the ears were cut at both ends of the film 22 with the ear-cleaving device 46. Ears 50 mm on both sides were cut with an NT-type cutter, and the cut ears were blown to a crusher 93 with a cutter blower (not shown) and crushed into chips of about 80 mm ² on average. This chip was used again as a raw material for dope production together with TAC flakes as a raw material for dope preparation. Before drying at a high temperature in a drying chamber 47 described later, the film 22 was preheated in a predrying chamber (not shown) to which 100 ° C. drying air was supplied.

  The film 22 was dried at a high temperature in a drying chamber 47. The drying chamber 47 was divided into four sections, and drying air at 120 ° C., 130 ° C., 130 ° C., and 130 ° C. was supplied from a blower (not shown) from the upstream side. The conveying tension of the film 22 by the roller 100 was set to 100 N / m, and the film was dried for about 5 minutes until the residual solvent amount finally reached 0.3% by weight. The wrap angle (film winding center angle) of the roller 100 was set to 80 ° to 190 °. The material of the roller 100 was made of aluminum or carbon steel, and hard chrome plating was applied to the surface. The roller 100 has a flat surface shape and a dimple processed surface shape. Film position fluctuations due to the rotation of the roller 100 were all 50 μm or less. The roller deflection at a tension of 100 N / m was selected to be 0.5 mm or less.

  The solvent gas contained in the drying wind was removed by adsorption using the adsorption / recovery device 101. The adsorbent used here was activated carbon, and desorption was performed using dry nitrogen. The recovered solvent was reused as a dope preparation solvent after adjusting the water content to 0.3 wt% or less. The drying air contains plasticizers, UV absorbers and other high-boiling substances in addition to the solvent gas, so these were removed by a cooler and pre-adsorber to be removed by cooling and used for recycling. And adsorption / desorption conditions were set so that VOC (volatile organic compound) in the outdoor exhaust gas was finally 10 ppm or less. Moreover, the solvent amount collect | recovered by a condensation method among all the evaporation solvents was 90 weight%, and most of the remainder was collect | recovered by adsorption collection.

  The dried film 22 was conveyed to a first humidity control chamber (not shown). A drying air of 110 ° C. was supplied to the transition portion between the drying chamber 47 and the first humidity control chamber. Air having a temperature of 50 ° C. and a dew point of 20 ° C. was supplied to the first humidity control chamber. Further, the film 22 was conveyed to a second humidity control chamber (not shown) that suppresses the curling of the film 22. In the second humidity control chamber, air of 90 ° C. and humidity 70% was directly applied to the film 22.

  The film 22 after humidity control was cooled to 30 ° C. or lower in the cooling chamber 48 and then subjected to ear cutting at both ends again with an ear cutting device (not shown). The forced charge removal device (charge removal bar) 102 was installed so that the charged voltage of the film 22 during conveyance was always in the range of -3 kV to +3 kV. Further, knurling was applied to both ends of the film 22 by a knurling roller 103. The knurling is applied by embossing from one side of the film 22, the width for applying the knurling is 10 mm, and the knurling is applied by the knurling application roller 103 so that the height of the unevenness is 12 μm higher than the average thickness of the film 22. The pressure was set.

  Then, the film 22 was conveyed to the winding chamber 23. The winding chamber 23 was kept at a room temperature of 28 ° C. and a humidity of 70%. An ion wind neutralization device (not shown) was also installed in the winding chamber 23 so that the charged voltage of the film 22 was -1.5 kV to +1.5 kV. A film roll was obtained from the film 22 using the winding roller 110 and the press roller 111. The film 22 had a thickness of 70 μm and a width of 1500 mm.

  In Example 1, a casting die including an inner deckle plate made of ceramics having a volume change rate of 0.002% was used. Other than that was carried out similarly to Example 1, and manufactured the film by the solution casting method.

  In Example 1, the casting process was performed using a casting die in which the distances CL1 to CL4 were adjusted to 10 μm or more. Other than that was carried out similarly to Example 1, and manufactured the film by the solution casting method.

  In Example 2, the casting process was performed using a casting die in which the distances CL1 to CL4 were adjusted to 30 μm or more. Other than that was carried out similarly to Example 1, and manufactured the film by the solution casting method.

  In Example 1, a casting die including an inner deckle plate made of Teflon (registered trademark) having a volume change rate of 2% was used. Other than that was carried out similarly to Example 1, and manufactured the film by the solution casting method.

[Evaluation of film]
In the above examples, the presence or absence of skinning and the flatness of the film were evaluated by the following methods. The following measurements are common to all Examples 1 to 5, and the evaluation results in each example are summarized in Table 1. The numbers of the evaluation items in Table 1 correspond to the numbers given to the following evaluation items.

1. In the casting process, when the casting dope flowed out from the casting die for 2 minutes or more, it was visually checked whether the casting dope had any skinning. In the case where there was no skinning on the casting dope, the symbol was “◯”, in the case where there was slight skinning, “△”, and when the casting dope was skinned, the symbol was “X”.

2. Planarity of film The degree of unevenness on the surface of the film produced in each example when the reflected light was applied to the sample, which was cut out to have a size of film width × 1.5 m. Was observed visually from an oblique direction. At this time, the level of unevenness on the surface of the film is small, and the level where there is no problem as a product is rated as ○, and there is no problem as a product. Films that could not be evaluated were evaluated as x, and the flatness of the film was evaluated in three stages.

  As is apparent from Table 1, in Examples 1 and 2 to which the present invention was applied, films having excellent flatness could be produced. Moreover, since the occurrence of skinning was suppressed in the casting process, it was not necessary to clean each part in the casting chamber such as a casting die or a casting band, and a solution casting method with high production efficiency could be performed. . On the other hand, the surfaces of the films produced in Examples 3 to 5 had irregularities and did not reach the level of flatness required as a product. Further, since the occurrence of skinning frequently occurs in the casting process, each part in the casting chamber, such as a casting die and a casting band, must be frequently cleaned, and the production efficiency of the solution casting method is lowered.

  From these results, the casting die of the present invention makes it possible to prevent the occurrence of casting dope skinning, and the solution casting method using this casting die and the solution casting equipment provided with this casting die It was confirmed that a film having excellent flatness can be produced efficiently.

It is explanatory drawing which shows the outline | summary of a film manufacturing process. It is explanatory drawing which shows the outline | summary of a film manufacturing equipment. It is explanatory drawing which shows the outline | summary of a casting process. It is sectional drawing of a casting die. It is the VV sectional view taken on the line shown in FIG. It is a perspective view which shows the outflow port of a casting die, and the outline | summary of the circumference | surroundings. (A) is a side view which shows the outline | summary of adjustment of the end surface of a lip board and an inner deckle board. (B) is a side view showing an outline of a casting die formed by combining an inner deckle plate and a lip plate whose end surfaces are adjusted. It is sectional drawing which shows the outline | summary of the 2nd casting die of this invention. It is the IX-IX sectional view taken on the line of FIG. 8 about the 2nd casting die of this invention. It is sectional drawing which shows the outline | summary of the 3rd casting die of this invention. It is sectional drawing which shows the outline | summary of the 4th casting die of this invention. It is explanatory drawing which shows the outline | summary of the conventional casting process. It is a top view which shows the outline of the outflow port of the conventional casting die, and its periphery.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Film manufacturing process 11 Dope 16 Casting film 17 Casting process 18 Wet film 20 Drying process 22 Film 40 Film manufacturing equipment 41 Casting die 41a Outlet 44 Casting band 210, 211 Lip plate 216 Slit 223, 224 Inner deckle Plate 210a, 211a, 223a, 224a Liquid contact surface 210b, 211b, 223b, 224b End face 210c, 211c, 223c, 224c Edge A1 Outflow direction CL1-CL4 Distance

Claims (4)

In a casting die in which a dope containing a polymer and a solvent flows out of the slit,
It na longitudinal channel surface of the slit, a pair of lip plates arranged opposite so as to form a gap of predetermined distance,
It Na widthwise channel surface of the slit, in the gap surrounded by the side plates attached to both ends of the lip plate and the lip plate, a pair of inner deckle plates disposed so as to be in contact with the side plate Have
The lip plate and the side plate are made of stainless steel having a volume change rate of 0.05% or less,
The inner deckle plate is formed from one of stainless steel and ceramics having a volume change rate of 0.05% or less,
In the outflow direction of the doping amount of protrusion of the pair of inner deckle plates relative to the pair of lip plates, or that the amount of protrusion of the pair of lip plates relative to the pair of inner deckle plate is 9μm or less A characteristic casting die. 2. The casting die according to claim 1, wherein the pair of inner deckle plates have an expanded surface in which a casting width of the dope gradually increases as the dope flows out. A casting die according to claim 1 or 2 ,
A support that runs and forms a cast film from the dope that flows out of the slit;
A solution casting apparatus comprising: a drying device that peels off the cast film on the support and dries it. Using the casting die according to claim 1 or 2, a step of causing the dope to flow out of the slit and forming a casting film on a traveling support;
And a step of peeling off the cast film on the support and drying the cast film.

Images