JP2009078371A - Method for casting dope, solution film forming method, and casting apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To efficiently form a film while evading a peeling failure and a thickness unevenness failure. <P>SOLUTION: A casting die 39 comprises: an inflow port 39a; an outflow port 39b; and a flow passage 39c communicating the inflow port 39a and the outflow port 39b. Inner deckle plates 88, 89 are provided at the edge parts on both sides of the flow passage 39c. The partition part 94 of the inner deckle plate 88 partitions the flow passage 39c and a flow passage 90, and an acute tip part 94a is formed at the tip. Pumps 26a, 26c are connected to the flow passage 39c and the flow passage 90. A casting bead 40 formed from the outflow port 39b toward the outer circumferential face 43a is subjected to free face side curve discrimination processing, and the flow rate of a third casting dope 30c to be formed as the side edge parts 40a of the casting bead 40 is reduced till the curve volume of the side edge parts 40a reaches prescribed value. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a dope casting method, a solution casting method, and a casting apparatus.

  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. Also, because TAC film has excellent optical isotropy, it is used for optical functional films such as polarizing film protective films, optical compensation films, and viewing angle expansion films for liquid crystal display devices whose market is rapidly expanding. It has been.

  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 accuracy of the film thickness, and fine lines (die lines) are easily formed on the film, so that a high-quality film that can be used as an optical functional film is manufactured. Is difficult. On the other hand, in the solution casting method, a polymer solution containing a polymer and a solvent (hereinafter referred to as a dope) is cast as a casting bead on a support to form a casting film, and the casting film is self-supporting. After the film has the property, the cast film is peeled off from the support, dried, and wound up as a film. This solution casting method is superior in optical isotropy and thickness uniformity as compared with the melt extrusion method, and can obtain a film with less contained foreign substances. Therefore, as a method for producing a film, particularly an optical functional film, A solution casting method is employed.

  Due to the viscoelasticity of the dope, it is known that a so-called neck-in occurs in which the width of the casting bead flowing out from the die is narrower than the width of the outlet. When this neck-in occurs, the thickness of the casting bead is thin at the central portion, and the portion (hereinafter referred to as the ear portion) of approximately 1% or less of the total width is thick from both ends. The occurrence of this neck-in generally correlates with the processing conditions (such as casting bead length and casting die slit width) in addition to the physical properties of the polymer. It is known that neck-in occurs more significantly when the take-up tension of the rolled bead, the length of the cast bead, and the slit width of the cast die increase. If the ear becomes excessively thick due to this neck-in, a peeling failure such as tearing when the cast film is peeled off as a wet film frequently occurs. Therefore, in order to avoid this peeling failure, it is necessary to adjust the thickness of both ends of the casting bead.

Patent Documents 1 and 2 disclose a method of adjusting the thickness of the ear portion of the casting bead. Patent Document 1 discloses a method using a deckle that regulates the width of a dope channel provided inside a casting die so as to gradually widen toward the outlet. In Patent Document 2, the dope flowing in the casting die is divided into a dope flow (main stream) that forms the center of the casting bead and a dope stream (secondary stream) that forms the ear of the casting bead. A method for adjusting the flow rate of a stream is disclosed.
JP 2005-007808 A JP-A-2005-279956

  In recent years, with the rapid increase in demand for liquid crystal display devices, a solution casting method with high production efficiency is strongly desired. In addition, liquid crystal display devices are shifting to being thinner and lighter. Therefore, a solution casting method and a solution casting equipment that can efficiently produce a thin optical functional film have been studied.

  In order to improve the production efficiency of the solution casting method, improvement of the deposition rate has been studied. It is well known that the film forming speed is rate-limiting in the casting process, and the production efficiency can be improved by increasing the speed of travel of the support in the casting process (for example, 40 m / min or more). . However, as the running speed of the support increases, the adhesion between the casting membrane and the peripheral surface of the casting drum decreases. When the adhesion between the casting film and the peripheral surface decreases, the accompanying air generated by the running of the peripheral surface of the casting drum flows between the casting film and the peripheral surface, resulting in a failure in thickness unevenness of the casting film. Therefore, in order to compensate for this decrease in adhesion, it is necessary to decompress the surface of the casting bead (hereinafter referred to as the back surface) on the upstream side in the running direction of the support.

  However, when the solution film forming method is performed in a state where the back side of the casting bead is decompressed, the casting bead vibrates and becomes unstable due to an air flow generated by the decompression. When the casting bead becomes unstable, unevenness occurs in the thickness of the casting film, resulting in a failure in uneven thickness of the film. In particular, the ear part of the casting bead is more likely to vibrate than the central part. Therefore, when making a film thinner than the conventional one (for example, 60 μm or less), the thickness of the casting bead is also thinner than the conventional one. Therefore, the instability of the casting bead becomes more prominent, resulting in a thickness unevenness failure. It tends to occur.

  Therefore, in order to efficiently manufacture the film while avoiding the peeling failure and the thickness unevenness failure, the thickness of the ear part of the casting bead is adjusted as in the inventions described in Patent Documents 1 and 2. It is also possible to stabilize the casting bead.

  However, in the method for adjusting the thickness of the ear described in Patent Document 1, it is necessary to replace the dickel provided in the casting die or the casting die or to adjust the deck, and to adjust the thickness of the ear appropriately. A huge amount of time is spent on the process. Therefore, each time the composition of the dope is changed or the production conditions of the film are changed, it is necessary to adjust the thickness of the ears. Therefore, the production efficiency is low, and it is particularly suitable for producing a variety of films. Absent.

  In addition, the method for adjusting the thickness of the ear described in Patent Document 2 cannot adjust the dope pressure in the main flow and the sub flow independently, so the film production conditions (film forming speed, film width, film thickness, etc.) ), It is difficult to adjust only the thickness of the ear part to a desired condition.

  The present invention solves the above-described problems, and a dope casting method, a solution casting method, and a flow casting method that can efficiently produce an optical functional film while avoiding a peeling failure and a thickness unevenness failure. A rolling device is provided.

  In the present invention, a dope containing a polymer and a solvent is supplied to a slot provided in a casting die, and the dope flows out onto a support that runs from an outlet of the slot. In a dope casting method in which a casting bead is formed over a support and a casting film is formed from the dope on the support, the slot is formed using a partition member disposed in the vicinity of the outlet of the slot. In the width direction of the casting die, at least two side edge slots and a center slot are divided into three sections, a side edge dope is supplied to the side edge slot, and a center dope is supplied to the center slot. Supply and merge the side edge dope that has passed through the side edge slot and the center dope that has passed through the center slot using an acute-angled tip provided in the partition member A side edge portion in the width direction of the casting bead on a contact surface side that contacts the support when the casting bead becomes the casting membrane or a free surface side opposite to the contact surface. When the side edge is curved toward the contact surface side, it is determined whether the side edge is curved, and the extensional viscosity at the side edge slot of the side edge dope forming the side edge is increased. And when the said side edge part curves to the said free surface side, the elongational viscosity in the said side edge part slot of the said side edge part dope which forms the said side edge part is made small, It is characterized by the above-mentioned.

  When the side edge is curved to the free surface side, the flow rate of the side edge dope is increased by using a side edge extruder that supplies the side edge dope to the side edge slot. From the flow rate adjustment process, the partition member shifting process in which the dope flows in the slot in the liquid feeding direction, and increasing the distance from the outlet to the tip, and the side edge dope It is preferable to perform at least one of a new side edge dope supply process for supplying a dope having a low elongation viscosity as a new side edge dope to the side edge slot.

  In the partition member shifting process, the distance is preferably set to 0.1 mm or more and 40 mm or less. The side edge dope includes the polymer, a good solvent, and a poor solvent. In the new side edge dope supply process, the concentration of the poor solvent with respect to the good solvent and the poor solvent is set to the side edge dope. Preferably, the higher new side edge dope is supplied to the side edge slot. Further, in the new side edge dope supply process, it is preferable that the new side edge dope having a lower concentration of the polymer than the side edge dope is supplied to the side edge slot.

  When the side edge is curved toward the contact surface side, the flow rate of the side edge dope is decreased using a side edge extruder that supplies the side edge dope to the side edge slot. The flow rate adjusting process, the partition member is shifted in the liquid feeding direction in which the dope flows in the slot, and the partition member shift process for reducing the distance from the outlet to the tip part, and the side edge part It is preferable to perform at least one of the new side edge dope supply process for supplying a dope having a higher extensional viscosity than the dope as a new side edge dope to the side edge slot.

  Further, the solution casting method of the present invention uses any one of the dope casting methods described above, peels off the casting film after having the self-supporting property from the support, and dries the film. It is characterized by.

  Further, the present invention provides a dope supplied to a slot provided in a casting die, flows out from the outlet of the slot on a traveling support, and flows from the outlet to the support by the dope. In a casting apparatus for forming a bead and forming a casting film from the dope on the support, the slot is disposed in the slot, and the slot is arranged in at least two side edge slots in the width direction of the casting die. And the central slot is divided into three sections, and the downstream end in the liquid feeding direction in which the dope flows through the slot is formed at an acute angle, and the side edge slot and the center are formed through the distal end. A partition member that joins the dope that has passed through the slot, and a contact surface side that contacts the support when the casting bead becomes the casting film, or a free surface side opposite to the contact surface, A curve discriminating unit for discriminating whether or not a side edge portion of the casting bead in the width direction is curved; and when the curve discriminating unit discriminates that the side edge portion is curved toward the free surface side Reduces the extensional viscosity at the side edge slot of the side edge dope forming the side edge, and determines that the curve determining part is curved toward the contact surface side. When it does, it is provided with the extension viscosity adjustment part which enlarges the extension viscosity in the said side edge slot of the said side edge part dope which forms the said side edge part, It is characterized by the above-mentioned.

  When the bending determination unit determines that the side edge is curved toward the free surface side, the elongational viscosity adjusting unit uses an extruder that supplies the side edge dope to the side edge slot. A flow rate adjusting unit that increases the flow rate of the side edge dope, and a partition member shift unit that shifts the partition member downstream in the liquid feeding direction and increases the distance from the outlet to the acute-angled tip. And a new side edge dope supply part for supplying a dope having a lower extensional viscosity than the side edge dope as a new side edge dope to the side edge slot. preferable.

  It is preferable that the distance between the tip portion and the outlet is 0.1 mm or more and 40 mm or less. In addition, when the curvature determining unit determines that the side edge is curved toward the contact surface, the elongational viscosity adjusting unit reduces the flow rate of the side edge dope using the extruder. The flow rate adjusting part, the partition member shifting part that shifts the partition member upstream in the liquid feeding direction, and reducing the distance from the outlet to the tip part, and the extension viscosity of the side edge dope. It is preferable to have at least one of the new side edge dope supply section for supplying a high dope as a new side edge dope to the side edge slot.

  The partition member has a movable member having the tip at the downstream end in the liquid feeding direction, and the partition member shift unit moves the movable member upstream or downstream in the liquid feeding direction. It is preferable to have a movable plate shifter that shifts.

  According to the present invention, it is determined whether or not the side edge portion of the casting bead is curved, and when the side edge portion is curved, the side edge slot of the side edge dope forming the side edge portion is determined. It is possible to increase the elongational viscosity at, so that the vibration of the side edge of the casting bead can be suppressed and the casting bead can be stabilized easily. Therefore, according to the present invention, it is possible to efficiently produce a film having a desired film thickness while avoiding a peeling failure and a thickness unevenness failure under any film forming conditions.

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

(Solution casting method)
FIG. 1 shows a schematic diagram of a film production line 10 used in the present embodiment. The film production line 10 includes a casting chamber 11, a pass roller 12, a pin tenter 13, an edge cutting device 14, a drying chamber 15, a cooling chamber 16, and a winding chamber 17.

  The stock tank 20 is provided with a stirring blade 20b that is rotated by a motor 20a and a jacket 20c, in which a raw material dope 23 that is a raw material of the film 57 is stored. The stock tank 20 is always adjusted so that the temperature of the raw material dope 23 becomes substantially constant by the jacket 20c provided on the outer peripheral surface of the stock tank 20 and the stirring blade 20b is rotated. Thus, the uniform quality of the raw material dope 23 is maintained.

  The stock tank 20 is connected to the casting chamber 11 by pipes 25a to 25c. The pipe 25a is provided with a gear pump 26a, a filtering device 27a, and an inline mixer 28a. Similarly, the pipe 25b includes a gear pump 26b, a filtering device 27b, and an inline mixer 28b, and the piping 25c includes a gear pump 26c, a filtering device 27c, and an inline mixer 28c. An additive liquid supply device 29 is connected to the upstream side of the in-line mixers 28a to 28c of the pipes 25a to 25c. Under the control of the control unit 35, the additive liquid supply device 29 is a liquid containing a predetermined amount of polymer or solvent (hereinafter referred to as a polymer solution), or an ultraviolet absorber, a matting agent, a retardation control agent, or the like. The polymer solution containing the agent is added to the raw material dope 23 in the pipe 25a. The in-line mixer 28a stirs and mixes the raw material dope 23 and the polymer solution to prepare the first casting dope 30a. Similarly, the additive solution supply device 29 adds a suitably prepared polymer solution or the like to the raw material dope 23 in the pipe 25b or the pipe 25c. The in-line mixers 28b and 28c stir and mix the raw material dope 23 and these polymer solutions to prepare the second casting dope 30b and the third casting dope 30c.

  The gear pumps 26 a to 26 c are connected to the control unit 35. Under the control of the control unit 35, the gear pumps 26 a to 26 c send the first to third casting dopes 30 a to 30 c at a predetermined flow rate to the casting die 39 arranged in the casting chamber 11.

  The casting chamber 11 includes a casting die 39 that flows out the first to third casting dopes 30a to 30c as a casting bead 40 (see FIG. 2), a support, and the first to third casting dopes. A casting drum (hereinafter referred to as a casting drum) 43 that forms a casting film 42 from 30a to 30c, a stripping roller 44 that peels the casting film 42 from the casting drum 43, and an internal temperature of the casting chamber 11 Is provided with a temperature control equipment 45 for maintaining the temperature within a predetermined range, a condenser (condenser) 46 for condensing and recovering the solvent vaporized in the casting chamber 11, and a recovery device 47 for recovering the condensed liquid solvent. It has been. The condensed and liquefied solvent is recovered by the recovery device 47 and regenerated, and then reused as a dope preparation solvent. Thus, the recovery device 47 keeps the vapor pressure of the solvent contained in the atmosphere in the casting chamber 11 within a predetermined range.

(Casting drum)
Below the casting die 39, a casting drum 43 formed in a substantially columnar shape or a substantially cylindrical shape is provided. The casting drum 43 has a shaft 43 a connected to the control unit 35. Under the control of the control unit 35, the casting drum 43 rotates around the shaft 43a so that the outer peripheral surface 43b travels at a predetermined speed in the traveling direction Z1.

  Further, in order to keep the temperature T1 of the outer peripheral surface 43b of the casting drum 43 at a desired temperature, a heat transfer medium circulation device 48 is attached to the casting drum 43. The heat transfer medium maintained at a desired temperature by the heat transfer medium circulation device 48 passes through the heat transfer medium flow path in the casting drum 43, so that the temperature T1 of the outer peripheral surface 43b of the casting drum 43 is reached. Can be maintained at a desired temperature.

The width of the casting drum 43 is not particularly limited, but it is preferable to use a casting drum having a width in the range of 1.1 to 2.0 times the width of the casting bead 40. It is preferable to use one that has been polished so that the outer surface 43b has a surface roughness of 0.01 m or less. It is necessary to suppress surface defects on the outer peripheral surface 43b to a 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 positional fluctuation in the vertical direction of the outer peripheral surface 43b accompanying the rotation of the casting drum 43 is preferably 200 μm or less. The speed fluctuation of the casting drum 43 is preferably 3% or less, and the meandering in the width direction when the casting drum 43 rotates once is preferably 3 mm or less.

  The material of the casting drum 43 is preferably made of stainless steel, and more preferably made of SUS316 so as to have sufficient corrosion resistance and strength. The outer peripheral surface 43b of the casting drum 43 is preferably subjected to chrome plating. Thereby, the outer peripheral surface 43b has sufficient corrosion resistance and strength for casting the casting dope 30.

(Peeling roller)
The stripping roller 44 is disposed on the downstream side in the traveling direction Z1 with respect to the casting die 39 and in the vicinity of the outer peripheral surface 43 b of the casting drum 43. The peeling roller 44 peels off the casting film 42 on the casting drum 43 to form a wet film 55.

  A pin tenter 13 and an edge-cutting device 14 are sequentially provided downstream of the casting chamber 11 to dry the plurality of pass rollers 12 and the wet film 55 to form the film 57.

  The stripping roller 44 guides the wet film 55 to the pass roller 12. The pass roller 12 guides the wet film 55 sent from the casting chamber 11 to the pin tenter 13. Although illustration is omitted, a dry air supply device is provided in the vicinity of the pass roller 12. The drying air supply device applies the drying air to the wet film 55 on the pass roller 12 to dry the wet film 55.

  The pin tenter 13 has a plurality of pins (not shown) which are fixing means for the wet film 55. These pins are attached to an annular chain. As the chain travels, the pin travels endlessly. The pin tenter 13 fixes the wet film 55 by piercing both side edges of the wet film 55 sent from the peeling roller 44 with pins. Then, the pin tenter 13 conveys the two chains in a predetermined direction. The pin tenter 13 is provided with a dry air supply device (not shown). The dry air supply device applies the dry air to the wet film 55 in the pin tenter 13 to dry the wet film 55. By this drying, the residual solvent amount of the wet film 55 is reduced, and the wet film 55 becomes the film 57.

  An ear clip device 14 is provided between the pin tenter 13 and the drying chamber 15. The ear opener 14 is provided with a crusher 59. The ear clip device 14 cuts both side edges of the film 57 and sends the cut side edges to the crusher 59. The crusher 59 pulverizes the cut edges on both sides to form film strips. The film strip is dissolved in a solvent, subjected to an additive removal treatment, sent to a hopper, etc., and reused as a raw material for the raw material dope 23.

  A clip tenter 60 that extends the film 57 while drying may be provided between the pin tenter 13 and the ear clip device 14. The clip tenter 60 is a drying device having a clip as a gripping means for the film 57. Desired optical characteristics can be imparted to the film 57 by the stretching process of the clip tenter 60 under predetermined conditions.

  The drying chamber 15 is provided with a number of rollers 65 and an adsorption recovery device 66. Further, a forced static elimination device (static elimination bar) 68 is provided downstream of the cooling chamber 16 provided in the drying chamber 15. In this embodiment, a knurling roller 69 is provided on the downstream side of the forced static elimination device 68.

  Although the temperature in the drying chamber 15 is not specifically limited, It is preferable that it is the range of 50 to 160 degreeC. In the drying chamber 15, the film 57 is conveyed while being wound around a roller 65, and the solvent compound, which is a solvent component generated by evaporation here, is adsorbed and recovered by the adsorption recovery device 66. The air from which the solvent compound has been removed is blown again as dry air inside the drying chamber 15. The drying chamber 15 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 14 and the drying chamber 15 and the film 57 is preliminarily dried, the film temperature is prevented from rising rapidly in the drying chamber 15. The shape change of the film 57 can be further suppressed.

  The cooling chamber 16 cools the film 57 to approximately room temperature. A humidity control chamber (not shown) may be provided between the drying chamber 15 and the cooling chamber 16. Air adjusted to a desired humidity and temperature is blown onto the film 57 in the humidity control chamber. Thereby, the occurrence of curling of the film 57 and the occurrence of winding failure when winding can be suppressed.

  The forced static elimination device 68 sets the charged voltage of the film 57 being conveyed to a predetermined range (for example, not less than −3 kV and not more than +3 kV). Further, the knurling roller 69 applies knurling to both edges of the film 57 by embossing. The unevenness of the knurled portion is preferably 1 μm or more and 200 μm or less.

  Inside the winding chamber 17, a winding roller 71 and a press roller 72 are provided. At this time, the press roller 72 winds up while applying a desired tension.

(Casting die)
3 and 4, the casting die 39 includes lip plates 80 and 81 and side plates 82 and 83, and an inlet 39a into which the casting dope 30a sent from the pipe 25a flows, and an inlet The first to third casting dopes 30 a to 30 c that are joined to 39 a and have the outlet 39 b that flows out as the casting bead 40.

  On the lip plate 80, liquid contact surfaces 80a and 80b are sequentially formed from the inlet 39a to the outlet 39b. The lip plate 81 is formed with liquid contact surfaces 81a to 81d that come into contact with the first to third casting dopes 30a to 30c from the inlet 39a to the outlet 39b. The flow path 39c formed from each liquid contact surface 80a-80b and 81a-81d connects the inflow port 39a and the outflow port 39b. The liquid contact surface in the direction TH of the manifold 85 includes a liquid contact surface 80a and a liquid contact surface 81a, and the liquid contact surface in the direction TH of the slit 86 includes a liquid contact surface 80b and liquid contact surfaces 81b to 81d.

  The liquid contact surface 80b and the liquid contact surface 81b form the slit width of the slit 86 in the direction TH, and the liquid contact surface 80b and the liquid contact surface 81d form the slit width of the slit 86 in the direction TH at SW2. . The liquid contact surface 81c and the liquid contact surface 80b are formed so that the slit width of the slit 86 in the direction TH is changed from SW1 to SW2 as it goes from the inflow port 39a to the outflow port 39b.

  Inner deckle plates 88 and 89 are provided at both ends of the flow path 39 c with respect to the width direction TD of the casting die 39. The inner deckle plates 88 and 89 are provided so as to be in close contact with the lip plates 80 and 81 and the side plates 82 and 83 through packing (not shown).

  The inner deckle plate 88 has liquid contact surfaces 88a and 88b. Similarly, the inner deckle plate 89 has liquid contact surfaces 89a and 89b. The liquid contact surfaces 88a and 89a are formed so that the width of the flow path 39c in the direction TD is substantially constant. The liquid contact surfaces 88b and 89b are formed so that the width of the flow path 39c gradually increases as the width from the inlet 39a toward the outlet 39b is increased. The liquid contact surfaces 88a, 88b, 89a, 89b constitute the liquid contact surfaces in the direction TD of the manifold 85 and the slit 86.

  Channels 90 and 91 are formed in the inner deckle plate 88 and the side plate 82, respectively. The flow path 90 formed in the width W1 with respect to the width direction TD of the casting die 39 communicates the slit 86 and the flow path 91, and the flow path 91 communicates the flow path 90 and the pipe 25b. Further, the outlet 90a of the channel 90 is provided on the liquid contact surface 88b. The inner deckle plate 88 includes a partition portion 94 that partitions the flow path 90 and the flow path 39c. A sharp tip portion 94a is formed at the tip of the partition portion 94 on the outlet 39b side, and at the substantially central portion of the tip in the width direction TD. Moreover, the front-end | tip part 94a is formed so that the space | interval with the outflow port 39b may become CL1.

  Similarly, channels 96 and 97 are formed in the inner deckle plate 89 and the side plate 83, respectively. The channel 96 communicates the slit 86 and the channel 97, and the channel 97 communicates the channel 96 and the pipe 25c. Further, an outlet 96a of the channel 96 is provided on the liquid contact surface 89b. The inner deckle plate 89 has a partition 98 that partitions the flow path 96 and the flow path 39c. A sharp tip portion 98a is formed at the tip of the partition portion 98 on the outlet 39b side, and at the substantially central portion of the tip in the width direction TD. Moreover, the front-end | tip part 98a is formed so that the space | interval with the outflow port 39b may become CL1.

  Further, the thickness D1 of the partition portions 94 and 98 with respect to the width direction TD of the casting die 39 is preferably 5 mm or less, and more preferably 2 mm or less. This is because the casting bead 40 cannot be stably formed when the thickness D1 exceeds 5 mm. Moreover, the lower limit of the thickness D1 should just be what does not deform | transform or break by the pressure from casting dope 30a-30c.

(material)
As a material required for the material forming the lip plates 80 and 81 and the inner deckle plates 88 and 89 constituting the casting die 39, it can withstand oxidation and corrosion due to contact with the casting dope 30, and In the extending step, it is preferable to use a material that does not easily change in dimensions. That is, it is preferable to use a material satisfying the following (Condition 1) to (Condition 3) as a material for forming the lip plates 80 and 81 and the inner deckle plates 88 and 89.
(Condition 1) In a forced corrosion test with an aqueous electrolyte solution, it has a corrosion resistance substantially equivalent to that of SUS316.
(Condition 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.
(Condition 3) The coefficient of thermal expansion is 2 × 10 ⁻⁵ (° C. ⁻¹ ) or less.
Therefore, as materials for forming the lip plates 80 and 81 and the inner deckle plates 88 and 89, ceramics and stainless steel, in particular, austenitic stainless steel, particularly SUS316, SUS316L, etc., and precipitation hardening type stainless steel SUS630. SUS631 etc. are preferable.

Furthermore, in addition to the above (Condition 1) to (Condition 3), it is preferable that the following conditions are satisfied as materials required for the material for forming the lip plates 80 and 81 and the inner deckle plates 88 and 89.
(Condition 4) The volume change rate of the lip plates 80 and 81 and the inner deckle plates 88 and 89 during processing is 0.05% or less.
(Condition 5) The hardness of the inner deckle plates 88 and 89 is such that the lip plates 80 and 81 are not damaged.

From the above condition (4), the materials of the lip plates 80 and 81 and the inner deckle plates 88 and 89 may be any materials whose volume change rate satisfies the above conditions. Here, the volume change rate is the maximum value of the dimensional change amount a _x , dimensional change amount a _y , and dimensional change amount a _z of the inner deckle plates 88 and 89 in the orthogonal coordinate system of the x-axis, y-axis, and z-axis. It is. Further, the dimensional change amount a _x is the amount of dimensional change of the inner deckle plates 88 and 89 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 88 and 89 when applying 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 88 and 89 when applying 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 above condition (5), for example, when precipitation hardening stainless steel is used as the material of the lip plates 80 and 81, the Vickers hardness is 200 Hv or more as the material for forming the inner deckle plates 88 and 89. 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 88 and 89. In addition, it is preferable to use a magnetic material as the material of the inner deckle plates 88 and 89.

  The finishing accuracy of each liquid contact surface of the flow paths 39c, 90, 96 is preferably 1 μm or less in terms of surface roughness and the straightness is 1 μm / m or less in any direction. Due to the finishing accuracy, it is possible to prevent generation of streaks and unevenness in the casting film 42 formed from the first to third casting dopes 30a to 30c flowing out from the outlet 39b. The smoothness of the end surfaces of the lip plates 80 and 81 and the inner deckle plates 88 and 89 on the outlet 39b side is preferably 2 μm or less at maximum. An average value of the gaps SW1 and SW2 of the slit 86 that can be adjusted within a range of 0.5 mm to 3.5 mm by automatic adjustment is used. As for the corner portion of the liquid contact portion at the tip of the lip of the casting die 39, R is 50 μm or less over the entire width of the slit 86.

Moreover, it is more preferable to form a cured film on the end faces of the lip plates 80 and 81 and the inner deckle plates 88 and 89 on the outlet 39b side. 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 39, 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.

  Moreover, it is preferable that the liquid contact surfaces of the partition portions 94 and 98 are coated with a polymer compound or the like. Examples of the polymer compound include Teflon (registered trademark). The thickness of the coating film formed on the wetted surface by the coating treatment is preferably 10 μm or more. The film thickness distribution of the casting bead 40 in the width direction TD is correlated with the flow velocity distribution in the width direction TD of the merged dope composed of the first cast dope 30a to the third cast dope 30c, and the flow velocity of the merged dope is small. The film thickness of the casting bead 40 formed from the region is reduced, and the film thickness of the casting bead 40 in the region where the flow rate of the combined dope is large is increased. Therefore, by using the inner deckle plates 88 and 89 having a wetted surface coated with a polymer compound, the flow velocity distribution in the width direction TD of the flow velocity of the combined dope can be made substantially uniform, and the film thickness can be reduced. A substantially uniform casting bead 40 can be formed in the width direction TD.

  The width of the casting die 39 is not particularly limited, but is preferably 1.1 times or more and 2.0 times or less the width of the film to be the final product. A jacket (not shown) through which the heat transfer medium passes is provided on the outer peripheral surface of the casting die 39. Further, a temperature controller 100 (see FIG. 1) is attached to the casting die 39. The temperature controller 100 supplies a heat transfer medium having a predetermined temperature to the jacket. Further, it is more preferable that thickness adjusting bolts (heat bolts) are provided at predetermined intervals in the width direction TD of the casting die 39 and the casting die 39 is provided with an automatic thickness adjusting mechanism using a heat bolt. With the heat bolt, the slit width SW1, SW2 of the casting die 39 or the width W1 of the flow path 90 or the flow path 96 can be set to a desired value. The heat bolt is preferably subjected to film formation by setting a profile according to the liquid feeding amount of the gear pumps 26a to 26c by a preset program. Further, feedback control may be performed by an adjustment program based on the profile of a thickness meter (for example, an infrared thickness meter) (not shown) in the film production line 10. 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 first to third casting dopes 30a to 30c in the casting die 39 is preferably adjusted to be 1 (1 / second) or more and 5000 (1 / second) or less.

(Decompression chamber)
As shown in FIG. 1, the decompression chamber 102 is disposed upstream of the casting die 39 in the traveling direction Z1. The decompression chamber 102 decompresses the back side of the casting bead 40 in a range of −10 Pa to −2000 Pa below the pressure on the downstream side surface (hereinafter referred to as the front side) of the casting bead 40 in the traveling direction Z1. Can do. The decompression chamber 102 is connected to a control unit (not shown). Under the control of a control unit (not shown), the decompression chamber 102 decompresses at a predetermined pressure. In this specification, “reducing the pressure on the back side of the casting bead 40 to −X (Pa) or less” means that the back side is lower than the front side of the casting bead 40 by X (Pa) or more. Is reduced in pressure.

  It is preferable that a jacket (not shown) is attached to the decompression chamber 102 and the temperature is controlled so that the internal temperature is kept at a predetermined temperature. The temperature of the decompression chamber 102 is not particularly limited, but is preferably set to be equal to or higher than the condensation point of the organic solvent used.

  As shown in FIGS. 2 and 5, the imaging device 110 has an area sensor 110a, and the imaging device 111 has an area sensor 111a. Then, the imaging device 110 and the imaging device 111 are arranged along the width direction TD through the casting bead 40 so that the area sensors 110a and 111a face the side edge portion 40a of the casting bead 40. . In addition, a curvature detection device 112 is connected to the imaging device 110, and a curvature detection device 113 is connected to the imaging device 111.

  The area sensor 110a generates an imaging signal for the image of the side edge 40a of the casting bead 40. The imaging device 110 generates image data from the imaging signal obtained by the area sensor 110 a at regular intervals, and sends this image data to the curvature detection device 112. The curvature detection device 112 performs a predetermined image analysis process on the image data obtained from the imaging device 110, and performs a free surface side curvature determination process. Similarly, the area sensor 111a generates an imaging signal for the image of the side edge 40a of the casting bead 40. The imaging device 111 generates image data from the imaging signal obtained by the area sensor 111 a at regular intervals, and sends this image data to the curvature detection device 113. The curvature detection device 113 performs predetermined image analysis processing on the image data obtained from the imaging device 111 and performs free-surface-side curvature determination processing.

  In the free-surface-side curvature determination processing, the reference image data for the side edge portion 40a that is not curved is compared with the image data obtained by the area sensors 110a and 111a, and the difference between the two image data is set to a predetermined amount. When exceeded, it is determined that the side edge portion 40a is curved toward the free surface. Here, the free surface 40b is a surface on the opposite side to the contact surface 40c which contacts the outer peripheral surface 43b, when the casting bead 40 becomes the casting film 42 among the flow surface beads 40. In the free-surface-side curvature determination process, a known image analysis method may be used instead of the above method.

  Further, the imaging device 110 and the imaging device 111 are connected to the control unit 35 (see FIG. 1). Under the control of the control unit 35, the imaging device 110 performs free surface side bending determination processing, and when it is determined that the side edge portion 40 a is curved to the free surface side, a free surface side bending signal is sent to the control unit 35. Output.

  Next, an example of a method for manufacturing the film 57 using the above-described film manufacturing line 10 will be described below. As shown in FIG. 1, the raw material dope 23 in the stock tank 20 is always made uniform by the rotation of the stirring blade 20b. The raw material dope 23 can be mixed with an additive such as a plasticizer during the stirring. Further, a heat transfer medium is supplied into the jacket 20c, and the temperature of the raw material dope 23 is kept substantially constant in a range of 25 ° C. or more and 35 ° C. or less.

  Under the control of the control unit 35, the gear pumps 26a to 26c send the raw material dope 23 to the pipes 25a to 25c via the filtering devices 27a to 27c. In the filtering devices 27a to 27c, the raw material dope 23 is filtered. The additive solution supply device 29 is a polymer solution prepared for the first to third casting dopes 30a to 30c or a polymer solution containing necessary additives under the control of the control unit 35. The liquid is appropriately fed to the pipes 25a to 25c, respectively. The in-line mixers 28a to 28c stir and mix the raw material dope 23 and the polymer solution to produce the first to third cast dopes 30a to 30c. In the in-line mixers 28a to 28c, it is preferable that the temperature of the raw material dope 23 is maintained substantially constant in the range of 30 ° C. or higher and 40 ° C. or lower. Then, the first to third casting dopes 30a to 30c are sent to the casting die 39 in the casting chamber 11 by the gear pumps 26a to 26c.

  The recovery device 47 keeps the vapor pressure of the solvent contained in the atmosphere in the casting chamber 11 substantially constant within a predetermined range. The temperature control equipment 45 keeps the temperature of the atmosphere in the casting chamber 11 substantially constant in the range of −10 ° C. to 57 ° C.

  The temperature controller 100 maintains the temperature of the heat transfer medium at approximately 36 ° C., and supplies the heat transfer medium to the jacket. As a result, the temperature of the casting die 39 is maintained at approximately 36 ° C.

  Under the control of the control unit 35, the casting drum 43 rotates about the shaft 43a. By this rotation, the outer peripheral surface 43b travels in the traveling direction Z1 at a predetermined speed (from 50 m / min to 200 m / min). Further, the temperature T1 of the outer peripheral surface 43b is maintained substantially constant within a range of −10 ° C. or more and 10 ° C. or less by the heat transfer medium circulation device 48.

The casting die 39 flows out of the first to third casting dopes 30a to 30c from the outlet 39b.
The 1st-3rd casting dope 30a-30c which flowed out from the outflow port 39b forms the casting bead 40 over the outer peripheral surface 43b (refer FIG. 2). A casting film 42 is formed from the first to third casting dopes 30 a to 30 c on the outer peripheral surface 43 b of the casting drum 43. The cast film 42 is cooled on the outer peripheral surface 43b, and gelation proceeds. The details when the first to third casting dopes 30a to 30c flow out from the outlet 39b will be described later.

  After the casting film 42 has self-supporting properties, it is peeled off from the outer peripheral surface 43 b while being supported by the peeling roller 44 as a wet film 55, and sent to the pass roller 12. The pass roller 12 sends the wet film 55 to the pin tenter 13 while the drying of the wet film 55 proceeds by blowing dry air of a desired temperature from the blower.

  The wet film 55 sent to the pin tenter 13 is held at both edges by a fixing means such as a pin at the entrance. By this fixing means, the wet film 55 is dried under predetermined conditions while being transported through the pin tenter 13 to become a film 57. Then, the film 57 released from the fixing by the fixing means is sent to the clip tenter 60. In the clip tenter 60, both side edges are supported at the entrance by a supporting means such as a clip. By this supporting means, the film 57 is dried under predetermined conditions while being transported through the clip tenter 60. The film 57 being transported by the clip tenter 60 is subjected to a stretching process by a supporting means in a predetermined direction.

  The film 57 is dried to a predetermined residual solvent amount by the clip tenter 60 or the like, and then sent to the ear clip device 14. Both edge portions of the film 57 are cut at both edges by the ear clip device 14. The cut side edge is sent to the crusher 59 by a cutter blower (not shown). The crusher 59 pulverizes both side edges of the film 57 into film strips. The film strip is dissolved in a solvent, subjected to an additive removal process, sent to the hopper 14 (see FIG. 1), and the like, and reused as a raw material for the raw material dope 23.

  The film 57 from which both side edges have been cut off is sent to the drying chamber 15 and further dried. By this drying, it is preferable that the residual solvent amount of the film 57 is 5% by weight or less based on the dry amount. The residual solvent amount on the basis of the dry amount is a value calculated by {(xy) / y} × 100, where x is the film weight at the time of sampling and y is the weight after the sampling film is dried. . The sufficiently dried film 57 is sent to the cooling chamber 16. The film 57 is cooled to approximately room temperature in the cooling chamber 16.

  In addition, the forcible static eliminator 68 sets the charged voltage while the film 57 is being conveyed to a predetermined range (for example, −3 kV to +3 kV). The knurling roller 69 applies knurling to both edges of the film 57 by embossing. Finally, the film 57 is taken up by the take-up roller 71 in the take-up chamber 17 while applying a desired tension by the press roller 72. More preferably, the tension at the time of winding is gradually changed from the start to the end of winding.

  The film 57 wound around the winding roller 71 is preferably at least 100 m in the longitudinal direction (casting direction). The width of the film 57 is preferably 600 mm or more, and more preferably 1400 mm or more and 3000 mm or less. The present invention is also effective when it is larger than 3000 mm. Since the effect of the present invention is exhibited as the film thickness becomes thinner, the present invention is preferably used when, for example, a film 57 having a thickness of 20 μm or more and 80 μm or less is used. For example, the thickness is 20 μm or more and 60 μm or less. It is more preferable to use the present invention when manufacturing the film 57, and it is more preferable to use the present invention when manufacturing the film 57 having a thickness of 20 μm to 40 μm.

  As shown in FIGS. 4 and 5, the first casting dope 30 a flows into the manifold 85 from the inlet 39 a through the pipe 25 a and then flows into the slit 86 by the gear pump 26 a (see FIG. 1). The second casting dope 30b flows to the flow path 90 via the pipe 25b by the gear pump 26b (see FIG. 1). The second casting dope 30b flowing through the flow path 90 flows from the outlet 90a to the slit 86, and merges with the first casting dope 30a in the vicinity of the tip portion 94a. Similarly, the 3rd casting dope 30c flows into the flow path 96 via the piping 25c by the gear pump 26c (refer FIG. 1). The third casting dope 30c flowing through the flow channel 96 flows from the outlet 96a to the slit 86, and merges with the first casting dope 30a in the vicinity of the front end portion 98a. And the 1st casting dope 30a-the 3rd casting dope 30c form the casting bead 40 from the outflow port 39b to the outer peripheral surface 43b.

  When the tip portion 94a and the tip portion 98a are not formed at an acute angle, the first casting dope 30a to the third casting dope 30c are stagnated in the vicinity of the tip portions 94a and 98a. Since streaks are formed in the vicinity of the interfaces 30a to 30c, they cannot flow out as one casting dope 40 from the outlet 39b. In the present invention, since the tip portions 94a and 98a are formed at an acute angle, the first casting dope 30a and the second casting dope 30b join together without staying in the vicinity of the tip portion 94a, and the first casting The dope 30a and the third casting dope 30c merge without staying in the vicinity of the tip end portion 98a. Accordingly, the first casting dope 30a to the third casting dope 30c are joined by the tip portions 94a and 98a, and one casting bead 40 can be formed from the outlet port 39b to the outer peripheral surface 43b.

  While the casting bead 40 is formed, the curvature detection devices 112 and 113 perform a free surface side curvature determination process under the control of the control unit 35 (see FIG. 1). When the control unit 35 detects the free surface side bending signal from the bending detection devices 112 and 113, the side of the bending detection device 112 or 113 that outputs the free surface side bending signal under the control of the control unit 35. A flow rate adjustment process and a new side edge dope supply process are performed on the edge 40a. If the free surface side bending signal is not detected from the bending detection devices 112 and 113, the free surface side bending determination process is repeated again.

  Next, details of the flow rate adjustment process and the new side edge dope supply process will be described. In the flow rate adjustment process, under the control of the control unit 35, the pumps 26a to 26c independently reduce the flow rate of the second casting dope 30b or the third casting dope 30c. By reducing the flow rate of the second cast dope 30b or the third cast dope 30c, the shear strain rate of the second cast dope 30b or the third cast dope 30c in the slit 86 is reduced. The elongational viscosity of the second casting dope 30b or the third casting dope 30c can be increased. In the new side edge dope supply process, under the control of the control unit 35, the additive solution supply device 29 adds a predetermined polymer solution or the like to the raw material dope 23 in the pipes 25b and 25c, respectively. As a result, immediately before the casting die 39, the new second casting dope 30b or the third casting with a higher elongational viscosity in the slit 86 than the previous second casting dope 30b or the third casting dope 30c. A dope 30c can be prepared. The components such as the polymer solution will be described later.

  In this way, while it is determined that the side edge 40a of the casting bead 40 is curved toward the free surface 40b in the free surface side bending determination process, the flow rate adjustment process and the new side edge dope supply process are performed. Is repeatedly performed, the elongation viscosity of the second casting dope 30b and the third casting dope 30c in the slit 86 is individually increased to suppress the bending generated in the side edge portion 40a of the casting bead 40, and the casting bead 40 can be stabilized. Therefore, according to the present invention, it is possible to stabilize the casting bead 40 formed from the outlet port 39b to the outer peripheral surface 43b, and to suppress the occurrence of uneven thickness failure and peeling failure.

  Moreover, since the width W1 of the flow paths 90 and 96 is adjusted to a predetermined range, the casting bead 40 can be formed stably. The width W1 is preferably 0.1 mm or more. When the width W1 is less than 0.1 mm, the second casting dope 30b and the third casting dope 30c do not flow out as one casting bead 40 together with the first casting dope 30a, which is not preferable.

  Further, since the distance CL1 between the tip 94a and the outlet 39b is adjusted to a predetermined range, the tip 94a flows out from the outlet 39b while maintaining the pressure of the second casting dope 30b and the third casting dope 30c. Can be made.

  The interval CL1 is preferably 40 mm or less. In consideration of the pressure loss at the outlet 39b of the casting die 39, the distance CL1 is more preferably 20 mm or less, and preferably 10 mm or less. When the distance CL1 exceeds 40 mm, the flow rates of the second casting dope 30b and the third casting dope 30c adjusted independently of the flow rate of the first casting dope 30a forming the central portion flow out from the outlet 39b. This is because the thickness of the ear part of the casting bead 40 cannot be adjusted independently. Further, when the tip 94a protrudes outside the casting die 39, that is, closer to the outer peripheral surface 43b of the casting drum 43 than the outlet 39b, the first casting dope 30a to the third casting dope. 30c divides and flows out, and cannot flow out as one casting bead. Note that the lower limit of the interval CL1 may be determined based on the processing accuracy of the outlet 39b, the tip portion 94a, and the like, and is preferably 0.1 mm or more, for example.

  In the above embodiment, the wall thickness D1 of the partition portion 94 and the wall thickness D1 of the partition portion 98 are made equal. However, the present invention is not limited to this, and the wall thickness D1 of the partition portion 94 is within the predetermined range. The wall thickness D1 of the partition portion 98 may be different. Similarly, in the above embodiment, the distance CL1 between the tip portion 94a and the outlet port 39b and the distance CL1 between the tip portion 98a and the outlet port 39b are made equal, but the present invention is not limited to this, and within a predetermined range. If there is, the distance CL1 between the tip portion 94a and the outlet port 39b and the interval CL1 between the tip portion 98a and the outlet port 39b may be different.

  In the above embodiment, the tip portion 94a and the tip portion 98a are formed at an acute angle, but the angle θ1 of the tip portions 94a and 98a is preferably 10 ° or more and 90 ° or less, and 30 ° or more and 45 ° or less. It is more preferable that Here, the angle θ1 refers to the angle of the distal end portion 94a or the distal end portion 98a on the cut surface of the IV-IV line (see FIG. 3) or a surface substantially parallel to the cut surface.

  In the said embodiment, although the control part 35 performed the flow control apparatus and the new side edge dope supply process, this invention is not restricted to this, The partition member which adjusts the space | interval of the front-end | tip part of a partition part, and an outflow port Shift processing may be performed.

  In the above embodiment, the tip portions 94a and 98a are formed at the substantially central portion in the width direction TD at the tip of the partition portion 94 on the outlet 39b side. However, the present invention is not limited to this, and the tip portions 94a and 98a are wetted. It may be provided on the surfaces 88a and 88a. Further, the width of the flow paths 90, 96 in the vicinity of the outlets 90a, 96a is formed so as to expand, but the present invention is not limited to this, and the width of the flow paths 90, 96 in the vicinity of the outlets 90a, 96a is substantially the same. It may be uniform.

  In the above embodiment, the two partition members 94 and 98 are used to divide the slot 86 into three flow paths. However, the present invention is not limited to this, and three or four or more partition members are used. It may be divided into one or four or more flow paths.

  Next, the partition member shift process will be described. The same members and the same devices as those in the above embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  As shown in FIGS. 6 and 7, the casting die 139 includes a lip plate 81, a side plate 183, and the like, and has an inlet 39a (see FIG. 4), an outlet 39b, and a channel 39c. Inner deckle plates 189 are provided at both end portions of the flow path 39c with respect to the width direction TD of the casting die 139. The inner deckle plate 189 is provided so as to be in close contact with the lip plate 81, the side plate 183, and the like via a packing (not shown).

  The inner deckle plate 189 has liquid contact surfaces 189a and 189b. The liquid contact surface 189a is formed so that the width of the flow path 39c in the direction TD is substantially constant. The liquid contact surface 189b is formed so as to gradually widen as the width of the flow path 39c moves from the inflow port 39a to the outflow port 39b.

  Flow paths 190 and 191 are formed in the inner deckle plate 189 and the side plate 183, respectively. The flow path 190 formed in the width W1 with respect to the width direction TD of the casting die 139 communicates the flow path 39c and the flow path 191, and the flow path 191 communicates the flow path 190 and the pipe 25b. Further, an outlet 190a of the channel 190 is provided on the liquid contact surface 189b. The inner deckle plate 189 is formed so as to extend along the direction B1 in which the first casting dope 30a flows in the slit 86, and has a partition portion 194 that partitions the flow path 190 and the flow path 39c.

  A movable plate 195 is provided in the partition part 194. A sharp tip 195a is formed at the tip of the movable plate 195 on the outlet 39b side. In addition, innumerable fitting holes 197 are provided in the side surface of the movable plate 195 along the direction B1. Further, the casting die 139 is provided with a gear 198. On the outer peripheral surface of the gear 198, teeth 198a that can be fitted into the fitting holes 197 are provided. The gear 198 is connected to the shaft 199. The shaft 199 is connected to the control unit 35 via a motor or the like (not shown). Thus, under the control of the control unit 35, the movable plate 195 moves upstream or downstream along the direction B1.

  In the partition member shift process, first, the shaft 199 rotates the gear 198 in a predetermined direction under the control of the control unit 35. Then, by the rotation of the gear 198, the movable plate 195 can be moved upstream or downstream in the direction B1, and the distance CL2 between the outlet port 39b and the tip portion 195a can be adjusted to a desired range. By reducing the distance CL2, the shear stress that the third casting dope 30c receives from the first casting dope 30a at the interface between the first casting dope 30a and the third casting dope 30c is reduced. The elongational viscosity of the third casting dope 30c in the path 39c can be increased. Therefore, it is possible to stabilize the casting bead 40 by suppressing the bending generated in the side edge portion 40a of the casting bead 40 by the partition member shifting process.

  In the present invention, for the purpose of increasing the extensional viscosity of the third casting dope 30c in the slit 39c, at least one of a flow control device, a new side edge dope supply process, and a partition member shift process is performed. Just do it. In addition, the flow control device, the new side edge dope supply process, and the partition member shift process may be performed only on one side edge 40a or on both side edges 40a.

  In the above embodiment, the free-surface-side curve determination processing is performed using the imaging devices 110 and 111 and the curvature detection devices 112 and 113. However, the present invention is not limited to this, and the imaging devices 110 and 111 and the curvature detection device 112 are used. , 113 may be used to perform the contact surface side curvature discrimination processing.

  As shown in FIG. 8, while the casting bead 40 is formed, the curvature detection devices 112 and 113 perform the contact surface side curvature determination process under the control of the control unit 35 (see FIG. 1). When the control unit 35 detects the contact surface side curvature signal from the curvature detection devices 112 and 113, under the control of the control unit 35, the flow on the curvature detection devices 112 and 113 side that has output the contact surface side curvature signal. At least one of the flow rate adjustment process, the new side edge dope supply process, and the partition member shift process is performed on the side edge 40a of the extended bead 40. Note that when the contact surface side curvature signal is not detected from the curvature detection devices 112 and 113, the contact surface side curvature determination process is repeated again.

  In the contact surface side curvature determination processing, as in the free surface side curvature determination processing, the reference image data for the side edge portion 40a that is not curved is compared with the image data of the imaging signals obtained by the area sensors 110a and 111a, When the difference between the two image data exceeds a predetermined amount, it is determined that the side edge portion 40a is curved toward the contact surface.

  Next, the details of the flow rate adjustment process, the new side edge dope supply process, and the partition member shift process will be described. In the flow rate adjusting process, under the control of the control unit 35, the pumps 26a to 26c independently increase the flow rate of the second casting dope 30b or the third casting dope 30c. Increasing the flow rate of the second casting dope 30b or the third casting dope 30c increases the shear strain rate in the slit 86, so that the extensional viscosity in the slit 86 can be reduced. In the new side edge dope supply process, under the control of the control unit 35, the additive solution supply device 29 adds a predetermined polymer solution or the like to the raw material dope 23 in the pipes 25b and 25c, respectively. Thereby, the new 2nd casting dope 30b or the 3rd casting dope 30c whose extensional viscosity is lower than the conventional 2nd casting dope 30b or the 3rd casting dope 30c can be prepared. The components such as the polymer solution will be described later. Further, in the partition member shift process, the shaft 199 rotates the gear 198 in a predetermined direction under the control of the control unit 35. Then, by rotating the gear 198, the movable plate 195 is shifted in the direction B1, and the distance CL2 between the outlet 39b and the tip 195a can be adjusted to a desired range (see FIG. 6). Increasing the distance CL2 increases the shear stress that the third casting dope 30c receives from the first casting dope 30a at the interface between the first casting dope 30a and the third casting dope 30c. The extensional viscosity of the third casting dope 30c in the path 39c can be reduced.

  In this way, while it is determined that the side edge portion 40a of the casting bead 40 is curved toward the contact surface 40c side in the contact surface side bending determination processing, the flow rate adjustment processing and the new side edge dope supply processing are performed. Since at least one of the partition member shifting processes is repeatedly performed, the extension viscosity of the second casting dope 30b and the third casting dope 30c in the slit 86 is individually reduced, and the side edge portion of the casting bead 40 is reduced. The bending produced in 40a can be suppressed and the casting bead 40 can be stabilized. Therefore, according to this invention, the curvature produced in the side edge part 40a of the casting bead 40 can be suppressed, and the casting bead 40 can be stabilized. Therefore, the present invention can stabilize the casting bead 40 and suppress occurrence of thickness unevenness failure and peeling failure.

  In the above-described embodiment, the contact surface side curvature determination process is performed on the casting bead 40. However, the free surface side curvature determination process is performed together with the contact surface side curvature determination process, and the side edge portion 40a is on the free surface 40b side. Alternatively, in the case of bending toward the contact surface 40c, at least one of a flow rate adjustment process, a new side edge dope supply process, and a partition member shift process may be performed. Further, if necessary, the free side curvature determination process may be performed on one side edge portion 40a, and the contact surface side curvature determination process may be performed on the other side edge portion 40a.

  In addition, although the imaging devices 110 and 111 are used for the free-surface-side curvature determination processing and the contact surface-side curvature determination processing, the present invention is not limited to this, and a transmitter that transmits light and laser and the light and laser are received. The sensor pair including the receiving unit may be arranged in the width direction TD via the casting bead 40, or a distance measuring sensor may be used instead of the imaging devices 110 and 111. Further, the imaging devices 110 and 111 and the distance measuring sensor may be arranged along the width direction TD so as to face the contact surface 40c of the casting bead 40. Further, a plurality of imaging devices 110 and 111 and distance measuring sensors may be arranged along the width direction TD.

  Since the flow rate of the first casting dope 30a to the third casting dope 30c can be adjusted independently, the casting die of the present invention increases the extensional viscosity in the slit at one side end. Each process may be performed, and each process for decreasing the extensional viscosity in the slit may be performed on the other side end part, or each process for increasing or decreasing the extensional viscosity in the slit may be performed only on one side end part. Also good.

  The value of Df1 / Df2 is set to 0.75 or more and 3 or less by adjusting the flow rate per width of the first to third casting dopes 30a to 30c in the flow paths 25a to 25c using the gear pumps 26a to 26a. Is preferable, and it is more preferable to set it to 1 or more and 2 or less. This is preferable because it is possible to better avoid a peeling failure and a thickness unevenness failure. Here, Df1 is the thickness at the ear portion of the film 57, and Df2 is the thickness at the product portion of the film 57. Further, the adjustment of the thickness of the ear portion with respect to the central portion is not limited to the thickness of the film 57, and may be adjusted based on the thickness of the casting bead 40. Furthermore, you may adjust the thickness of the ear | edge part of the casting bead 40 in order to improve the conveyance property after peeling. Further, by appropriately selecting the additives of the first casting dope 30a, the second casting dope 30b, and the third casting dope 30c, a film having required optical characteristics and the like can be obtained as shown in FIG. The film production line 10 can be easily produced. For example, an additive that improves the optical properties and the like of the film can be added to the first casting dope 30a, and an additive that improves the peelability from the outer peripheral surface 43b and the transportability after peeling can be used. Thereby, a film excellent in optical characteristics can be produced with high production efficiency.

  Further, by making the additive of the second casting dope 30b and the third casting dope 30c into a compound having a good recyclability, the film strips obtained by the ear clip device 14 and the crusher 59 can be easily reused. The compound having good recyclability is not particularly limited as long as it is a compound that can easily extract the additive in a method for taking out a known additive.

  In the above embodiment, the outlets 90a and 96a of the channels 90 and 96 are provided on the liquid contact surfaces 88b and 89b, but the outlets 90a and 96a may be provided on the liquid contact surfaces 88a and 89a. In the above embodiment, the liquid contact surfaces 88b and 89b are formed so as to gradually widen as the width of the flow path 39c moves from the inflow port 39a to the outflow port 39b. However, the present invention is not limited to this and is substantially constant. You may form so that it may become.

  The first casting dope 30a to the third casting dope 30c include a polymer and a solvent, and additives are appropriately added as necessary. The first dope 30a to the third cast dope 30c may be the same dope or different dopes. The present invention is not limited to independently adjusting the flow rates of the first casting dope 30a to the third casting dope 30c, which are the same dope, but the composition of the first casting dope 30a to the third casting dope 30c. The flow rate may be adjusted depending on the ratio. Therefore, the polymer contained in the first casting dope 30a may be the same polymer as the second casting dope 30b and the third casting dope 30c, or may be a different polymer. The polymer contained in the second casting dope 30b may be the same polymer as the third casting dope 30c or may be a different polymer. Similarly, the same compound may be sufficient as the solvent and additive which are contained in the 1st casting dope 30a-the 3rd casting dope 30c, respectively, and a different compound may be sufficient as them.

  The solvent includes a good solvent that dissolves the polymer. The good solvent may be a mixture of a plurality of good solvents or a single good solvent. The solvent may be a mixture of a good solvent and a poor solvent. The poor solvent may be a mixture of a plurality of poor solvents, and details of the good solvent and the poor solvent will be described later.

  In order to increase the elongation viscosity of the second casting dope 30b in the slit 86b, the concentration of the poor solvent with respect to the solvent in the second casting dope 30b is set higher than the concentration of the poor solvent with respect to the solvent in the first casting dope 30a. Higher is preferred. On the other hand, in order to reduce the extensional viscosity of the second casting dope 30b in the slit 86b, the concentration of the poor solvent with respect to the solvent in the second casting dope 30b is set to be less than that of the poor solvent with respect to the solvent in the first casting dope 30a. What is necessary is just to make it lower than a density | concentration.

  In addition to increasing the concentration of the poor solvent relative to the solvent in the second casting dope 30b, by reducing the concentration of the polymer in the second casting dope 30b, adverse effects due to neck-in can be suppressed, and the concentration of the polymer can be reduced. It is possible to compensate for the decrease in elongational viscosity due to the decrease, and to improve the elongational viscosity of the second casting dope 30b as a whole. Therefore, it is possible to stabilize the casting bead 40 while minimizing the adverse effects caused by neck-in.

  The conditions such as the extension viscosity, the polymer concentration, and the poor solvent concentration of the second casting dope 30b described above can be applied to the third casting dope 30c as they are. The conditions such as the extensional viscosity, polymer concentration, and poor solvent concentration of the second casting dope 30b and the third casting dope 30c may be equal or different.

Extensional viscosity of the dope 51a~30c is given by three times the zero shear viscosity mu _0, zero shear viscosity mu ₀ can be determined by JIS K 7199.

(Good solvent)
When cellulose acylate is used as the polymer, the good solvent component of the polymer includes aromatic hydrocarbons (eg, benzene, toluene, etc.), halogenated hydrocarbons (eg, dichloromethane, chlorobenzene, etc.), esters (eg, methyl acetate, acetic acid). Ethyl, propyl acetate, etc.) and ether (eg, tetrahydrofuran, methyl cellosolve, etc.) are preferably used.

(Poor solvent)
When cellulose acylate is used as the polymer, alcohol (eg, methanol, ethanol, n-propanol, n-butanol, diethylene glycol, etc.) or ketone (eg, acetone, methyl ethyl ketone, etc.) is used as the poor solvent component of the polymer. preferable.

  Whether a certain compound is a good solvent compound or a poor solvent compound is determined by mixing the compound and the polymer so that the polymer is 5% by weight of the total weight. If it is a compound and there is no insoluble matter, it can be determined that the compound is a good solvent compound.

  When the weight ratio of the poor solvent compound of the second and third casting dopes 30b and 30c is HCe, and the weight ratio of the poor solvent compound of the first casting dope 30a is HCc, the value of HCe / HCc is It is preferable to set it to 1.05 or more and 3 or less. Thereby, since the ear | edge part of the casting film 42 becomes easy to gelatinize, peelability can be improved. HCc is the concentration of the poor solvent relative to the solvent in the first casting dope 30a, and HCe is the concentration of the poor solvent relative to the solvent in the second casting dope 30b.

  The elongation viscosity of the second casting dope 30b is preferably higher than the elongation viscosity of the first casting dope 30a. As the extension viscosity of the second casting dope 30b becomes higher than the extension viscosity of the first casting dope 30a, both side edges of the casting bead 40 are stabilized. The vibration of the casting bead 40 due to disturbance such as the vibration of the support can be suppressed. When the elongation viscosity of the first casting dope 30a is ηc and the elongation viscosity of the second casting dope 30b is ηe, the value of ηe / ηc is preferably greater than 1 and 3 or less, and preferably 1 or more and 2 or less. Is more preferable.

  It should be noted that the same applies to the solvent for the dope even if the polymer is a compound other than cellulose acylate, and the poor solvent and the good solvent may be the compounds determined by the poor solvent and good solvent determination methods described above. Good.

(polymer)
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.

(solvent)
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.

  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. The following experiments 1 to 8 are examples of embodiments of the present invention, and comparative experiments 1 to 6 are comparative experiments with respect to experiments 1 to 8. The description will be made in detail in Experiment 1. For Experiments 2 to 8 and Comparative Experiments 1 to 6 according to the present invention, descriptions of the same conditions as in Experiment 1 are omitted.

[Experiment 1]
Next, Experiment 1 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 preparation of the raw material dope 23 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
A solid content A (solute) having a composition ratio of 87% by weight of dichloromethane
Methanol 12% by weight
n-Butanol 1% by weight
The material dope 23 was prepared by appropriately adding to the mixed solvent A consisting of the above and stirring and dissolving (hereinafter referred to as the material dope 23 having the composition A). The solid content concentration of the raw material dope 23 having the composition A was adjusted to 19.3% by weight. The raw material dope 23 of composition A is filtered with a filter paper (Toyo Filter Paper Co., Ltd., # 63LB) and further filtered with a sintered metal filter (Nippon Seisen Co., Ltd. 06N, nominal pore size 10 μm), and further with a mesh filter. After filtration, it was placed in the stock tank 20.

[Cellulose triacetate]
The cellulose triacetate used here has a residual acetic acid content of 0.1% by weight or less, a Ca content of 58 ppm, a Mg content of 42 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.

  A film 57 was manufactured using the film manufacturing line 10. The gear pumps 26a to 26c have inverter motors that increase the pressure on the primary side. Feedback control was performed by the inverter motor so that the primary pressure became a predetermined pressure, and the raw material dope 23 of the composition A was fed to the pipes 25a to 25a. The gear pumps 26a to 26c used were those having a volumetric efficiency of 99.2% and a flow rate fluctuation rate of 0.5% or less. The outflow pressure was 1.5 MPa. Under the control of the control unit 35, the gear pumps 26a to 26c sent the raw material dope 23 having the composition A to the in-line mixers 28a to 28c. In the filtering devices 27a to 27c, the material dope 23 having the composition A was filtered.

  The additive liquid supply device 29 sent each additive into the pipes 25a to 25c. The raw material dope 23 having the composition A and this additive were mixed and stirred by the in-line mixers 28a to 28c to obtain first to third cast dopes 30a to 30c.

  As an outflow device, a casting die 39 including lip plates 80 and 81, side plates 82 and 83, and inner deckle plates 88 and 89 formed of precipitation hardening stainless steel having a volume change rate of 0.002% is used. Using. The casting die 39 is subjected to a casting process by adjusting the slit widths SW1 and SW2 and the flow rates of the first to third casting dopes 30a to 30c so that the film thicknesses Df1 and Df2 of the film 57 are 80 μm. It was. In order to adjust the temperature of the first to third casting dopes 30 a to 30 c to 36 ° C., a jacket (not shown) is provided on the casting die 39 and the temperature of the heat transfer medium supplied into the jacket is about 36 ° C. did. The widths W1 of the flow paths 90 and 96 were 5 mm, and the distance CL1 between the front end portion 94a and the outflow port 39b and the front end portion 98a and the outflow port 39b was 10 mm. Moreover, thickness D1 of the partition parts 94 and 150 was 2 mm. A microscope with a resolution of 1 μm was used to measure the dimensions of the lip plates 80 and 81 and the inner deckle plates 88 and 89 for calculating the volume change rate and the amount of change.

  In addition, a decompression chamber 102 for decompressing this portion was installed on the primary side of the casting die 39. The degree of decompression of the decompression chamber 102 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 1 mm to 50 mm.

  A stainless steel cylinder having a width of 3.0 m was used as the casting drum 43 as a support. The peripheral surface 82a of the casting drum 43 is polished so that the surface roughness is 0.05 μm or less. The material of the casting drum 43 was made of SUS316, and a material having sufficient corrosion resistance and strength was used. The thickness unevenness in the radial direction of the casting drum 43 was 0.5% or less. The casting drum 43 was rotated by driving the shaft 43 a under the control of the control unit 35. The casting speed, that is, the speed ZV in the traveling direction Z1 of the outer peripheral surface 43b was set to about 50 m / min. At this time, the speed fluctuation of the outer peripheral surface 43b was set to 0.5% or less. Further, both end positions of the casting drum 43 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 outer peripheral surface 43b immediately below the casting die 39 was set to 200 μm or less. The casting drum 43 was installed in the casting chamber 11 having wind pressure fluctuation suppressing means (not shown). The surface temperature of the central portion of the casting drum 43 immediately before casting was 0 ° C., and the temperature difference between both side edges was 6 ° C. or less.

  The oxygen concentration in the dry atmosphere on the casting drum 43 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 11, a condenser (condenser) 87 was provided, and its outlet temperature was set to -3 ° C. The static pressure fluctuation in the vicinity of the casting die 39 was suppressed to ± 1 Pa or less.

  In the casting die 39, the casting dope 30 was cast on the outer peripheral surface 43b, and the casting bead 40 was formed from the outlet 39b to the outer peripheral surface 43b. A casting film 42 was formed on the outer peripheral surface 43 b of the casting drum 43.

  The control unit 35 performed a free surface side curvature discrimination process on the casting bead 40. In the free-surface-side curvature determining process, it was determined that the side edge portion 40a is curved toward the free surface 40b side, and therefore flow rate adjustment processing or new-side edge dope supply processing was performed. When the flow rate of the second casting dope 30b before the flow rate adjusting process is Q0 and the flow rate of the second casting dope 30b after the flow rate adjusting process is Q1, RQ = Q1 / Q0 is 1.1. When the extension viscosity of the second cast dope 30b before the new side edge dope supply process is η0 and the extension viscosity of the second cast dope 30b after the new side edge dope supply process is η1, Rη = η1 / η0 Was 0.9.

  After the casting film 42 had a self-supporting property, it was peeled off as a wet film 55 while being supported by the peeling roller 44 from the casting drum 43. The wet film 55 was conveyed through the two rollers of the pass roller 12 and sent to the pin tenter 13. In the pass roller 12, 60 ° C. dry air was blown from the blower to the wet film 55.

  The wet film 55 sent to the pin tenter 13 sequentially passed through each section provided in the pin tenter 13 while being supported at both ends by pins. During the transport in the pin tenter 13, the wet film 55 was subjected to a predetermined drying process, and then sent out from the pin tenter 13 to the ear clip device 14 as a film 57 having a residual solvent amount of 5 wt% or less.

  The solvent evaporated in the pin tenter 13 was condensed and recovered at a temperature of −3 ° C. by providing a condenser (condenser) for condensation recovery. The condensed solvent was reused after adjusting the water content to 0.5 wt% or less.

Within 30 seconds from the exit of the pin tenter 13, the ears were cut at both ends of the film 57 with the ear-cleaver 14. Ears 50 mm on both sides were cut with an NT-type cutter, and the cut ears were blown to a crusher 59 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 the drying chamber 15 described later, the film 57 was preheated in a predrying chamber (not shown) supplied with 100 ° C. drying air.

  The film 57 was dried at a high temperature in the drying chamber 15. The drying chamber 15 was divided into four sections, and drying air of 120 ° C., 130 ° C., 130 ° C., and 130 ° C. was supplied from the blower (not shown) from the upstream side. The conveying tension of the film 57 by the roller 65 was set to 100 N / m, and the film was dried for about 5 minutes until the residual solvent amount finally became 0.3% by weight.

  The dried film 57 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 15 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 57 was conveyed to a second humidity control chamber (not shown) that suppresses the curling of the film 57. In the second humidity control chamber, air of 90 ° C. and humidity of 70% was directly applied to the film 57.

  The film 57 after humidity control was cooled to 30 ° C. or lower in the cooling chamber 16, and then the ears were cut again at both ends with an ear-cutting device (not shown). The forced static eliminating device 68 was installed so that the charged voltage of the film 57 during conveyance was always in the range of -3 kV to +3 kV. Further, knurling was applied to both ends of the film 57 by a knurling roller 69. The knurling is applied by embossing from one side of the film 57, the width for applying the knurling is 10 mm, and the knurling is pressed by the knurling application roller 69 so that the height of the unevenness is 12 μm higher than the average thickness of the film 57 on average. The pressure was set.

  Then, the film 57 was conveyed to the winding chamber 17. The winding chamber 17 was kept at a room temperature of 28 ° C. and a humidity of 70%. Inside the winding chamber 17, an ion wind neutralization device (not shown) was also installed so that the charged voltage of the film 57 was −1.5 kV to +1.5 kV. Finally, the film 57 was taken up by the take-up roller 71 in the take-up chamber 17 while applying a desired tension with the press roller 72.

[Experiment 2]
A film 57 was manufactured in the same manner as in Experiment 1 except that the speed ZV was set to about 100 m / min.

[Experiments 3-8]
A film 57 was produced in the same manner as in Experiments 1 and 2, except that the combination of Df1, Df2, RQ, and Rη was changed. The values of Df1, Df2, RQ, and Rη in each experiment are shown in Table 1.

[Comparative Experiments 1-6]
A film was produced in the same manner as in Experiments 1 to 8, except that the free surface side curvature discrimination process, the flow rate adjustment process, or the new side edge dope supply process was not performed.

[Evaluation of film]
In the above experiments and comparative experiments, the following method was used to evaluate whether or not there was a failure in thickness unevenness due to inflow of accompanying air and instability of casting beads. The following measurements are common to all of Experiments 1 to 8 and Comparative Experiments 1 to 6, 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. Presence or absence of peeling failure When the casting film 42 was peeled off from the outer peripheral surface 43b, the presence or absence of the remaining peeling of the casting film 42 on the outer peripheral surface 43b was visually examined, and the following evaluation was performed.
No peeling of the casting film 42 could be confirmed on the outer peripheral surface 43b (◯).
A small amount of the cast film 42 remained on the outer peripheral surface 43b (Δ).
A large amount of the cast film 42 remained on the outer peripheral surface 43b (×).

2. Thickness nonuniformity evaluation The following evaluation was performed by measuring the thickness nonuniformity of the obtained film by the following method. As a measuring method, the film thickness of the film was measured at five locations using an electronic micrometer manufactured by Anritsu Electric Co., Ltd. at 25 ° C. and 60 RH%. The relative standard deviation RSD (= deviation / average value × 100%) was calculated from the average value and deviation of the measured values. The film thickness unevenness was determined based on the following relative standard deviation.
Less than 10% ・ Excellent thickness uniformity (◯).
10% or more and 15% or less ··· The thickness is substantially uniform (Δ).
15% or more ··· Thickness unevenness occurs (x).

3. Manufacturability The adjustment time T1 required for adjusting the thickness of the ear part of the casting bead 40 was measured, and the following evaluation was performed.
The time T1 was less than 20% of the conventional adjustment time (◯).
The time T1 was 20% or more and less than 100% of the conventional adjustment time (Δ).
The time T1 was 100% or more of the conventional adjustment time (×).

  Therefore, the present invention can independently adjust the elongation viscosity of the side edge of the casting bead, thereby suppressing the curvature of the side edge of the casting bead, resulting in a stripping failure or thickness unevenness failure. Thus, it is possible to efficiently manufacture a thin film or a wide film.

It is explanatory drawing which shows the outline | summary of a film manufacturing line. It is explanatory drawing which shows the outline | summary of a casting process. It is sectional drawing of the 1st casting die. It is the IV-IV sectional view taken on the line shown in FIG. (A) is the VV sectional view taken on the line of FIG. 2 about the casting bead which the side edge part curves, (B) is about the casting bead from which the curvature of the side edge part was eliminated. It is the VV sectional view taken on the line shown in FIG. It is sectional drawing of the movable plate vicinity provided in the 2nd casting die. It is a side view of the movable plate vicinity provided in the 2nd casting die. FIG. 5 is a cross-sectional view taken along the line V-V shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Film production line 11 Casting chamber 23 Raw material dope 30a-30c Casting dope 35 Control part 39, 139 Casting die 39b Outlet 39c Flow path 40 Casting bead 40a Side edge 40b Free surface 40c Contact surface 40d Center part 42 Casting film 55 Wet film 57 Film 90, 96, 190 Flow path 94, 98, 194 Partition part 94a, 98a, 195a Tip part 194 Movable plate

Claims (12)

A dope containing a polymer and a solvent is supplied to a slot provided in a casting die, the dope flows out onto a support running from the outlet of the slot, and flows from the outlet to the support by the dope. In a dope casting method of forming a bead and forming a cast film from the dope on the support,
Using a partition member disposed in the vicinity of the outlet of the slot, the slot is divided into at least two side edge slots and a central slot in the width direction of the casting die;
Supplying a side edge dope to the side edge slot;
Supplying a central dope to the central slot;
Using an acute-angled tip provided in the partition member, the side edge dope that has passed through the side edge slot and the center dope that has passed through the center slot are merged,
A side edge portion in the width direction of the casting bead is curved on a contact surface side that comes into contact with the support when the casting bead becomes the casting membrane or on a free surface side opposite to the contact surface. Whether or not
When the side edge is curved toward the contact surface, the extensional viscosity of the side edge dope forming the side edge is increased in the side edge slot, and the side edge is the free surface. A dope casting method characterized in that, when curved to the side, the elongational viscosity at the side edge slot of the side edge dope forming the side edge is reduced. When the side edge is curved to the free surface side,
Using a side edge extruder that supplies the side edge dope to the side edge slot, a flow rate adjusting process for increasing the flow rate of the side edge dope,
The partition member is shifted in the liquid feeding direction in which the dope flows in the slot, and the partition member shifting process is performed to increase the distance from the outlet to the tip.
A new side edge dope supply process for supplying a dope having a lower extensional viscosity than the side edge dope as a new side edge dope to the side edge slot,
The dope casting method according to claim 1, wherein at least one treatment is performed.   3. The dope casting method according to claim 2, wherein, in the partition member shift process, the distance is set to 0.1 mm or more and 40 mm or less. The side edge dope includes the polymer, a good solvent, and a poor solvent,
In the new side edge dope supply process, the concentration of the poor solvent with respect to the good solvent and the poor solvent is higher than the side edge dope, and the new side edge dope is supplied to the side edge slot. 4. The dope casting method according to claim 2, wherein the dope is cast.   The said new side edge dope supply process supplies the said new side edge dope whose density | concentration of the said polymer is lower than the said side edge dope to the said side edge slot. The dope casting method according to any one of them. When the side edge is curved toward the contact surface side,
Using the side edge extruder that supplies the side edge dope to the side edge slot, the flow rate adjusting process for reducing the flow rate of the side edge dope;
The partition member shifting process in which the partition member is shifted in the liquid feeding direction in which the dope flows in the slot, and the distance from the outlet to the tip is reduced.
The new side edge dope supply process for supplying a dope having a higher elongational viscosity than the side edge dope as a new side edge dope to the side edge slot,
6. The dope casting method according to claim 2, wherein at least one treatment is performed.   The dope casting method according to any one of claims 1 to 6, wherein the cast film having self-supporting property is peeled off from the support and dried to form a film. A solution casting method. A dope is supplied to a slot provided in a casting die, and the dope flows out from an outlet of the slot on a traveling support, and a casting bead is formed from the outlet to the support by the dope, In a casting apparatus for forming a casting film from the dope on the support,
It is disposed in the slot, and the slot is divided into three sections of at least two side edge slots and a central slot in the width direction of the casting die, and the dope flows downstream in the liquid feeding direction. A partition member that joins the dope that has passed through the side edge slot and the central slot through the tip is formed with an acute tip on the side,
A side edge portion in the width direction of the casting bead is curved on a contact surface side that comes into contact with the support when the casting bead becomes the casting membrane or on a free surface side opposite to the contact surface. A curvature discriminating unit for discriminating whether or not
When the bending determination unit determines that the side edge is curved toward the free surface, the elongational viscosity in the side edge slot of the side edge dope forming the side edge is reduced. And when the curve determining unit determines that the side edge is curved toward the contact surface, the extensional viscosity in the side edge slot of the side edge dope forming the side edge is determined. An elongational viscosity adjusting unit for increasing
A casting apparatus comprising: When the curve determining unit determines that the side edge is curved toward the free surface side,
The elongational viscosity adjusting part is
Using an extruder that supplies the side edge dope to the side edge slot, a flow rate adjustment unit that increases the flow rate of the side edge dope,
A partition member shift unit that shifts the partition member downstream in the liquid feeding direction and increases the distance from the outlet to the acute-angled tip;
A new side edge dope supply unit for supplying a dope having a lower extensional viscosity than the side edge dope as a new side edge dope to the side edge slot;
The casting apparatus according to claim 8, comprising at least one of the following.   The casting apparatus according to claim 8 or 9, wherein a distance between the tip portion and the outlet is 0.1 mm or more and 40 mm or less. When the curve determining unit determines that the side edge is curved toward the contact surface side,
The elongational viscosity adjusting part is
The flow rate adjusting unit for reducing the flow rate of the side edge dope using the extruder,
The partition member shift unit that shifts the partition member upstream in the liquid feeding direction and reduces the distance from the outlet to the tip part;
The new side edge dope supply section that supplies a dope having a higher extensional viscosity than the side edge dope as a new side edge dope to the side edge slot,
The casting apparatus according to claim 9, wherein at least one of the casting apparatus is provided. Provided in the partition member, having a movable member having the tip at the tip on the downstream side in the liquid feeding direction;
The casting according to any one of claims 9 to 11, wherein the partition member shift section includes a movable plate shifter that shifts the movable member to the upstream side or the downstream side in the liquid feeding direction. apparatus.

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