JP5162144B2 - Solution casting method and solution casting equipment - Google Patents

Description

  The present invention relates to a solution casting method and solution casting equipment.

  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 light weight thinning. Among them, cellulose ester films using cellulose acylate and the like have toughness and low birefringence. Therefore, liquid crystal display devices (hereinafter referred to as LCDs), which have recently been expanding the market, including photographic photosensitive films. It is used as an optical functional film such as a protective film for a polarizing plate or an optical compensation film, which is a constituent member of a display device.

  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 film thickness accuracy, and because fine lines (die lines) can be formed on the film, it is difficult to produce a high-quality film that can be used for optical functional films. is there. On the other hand, since the solution casting method is excellent in optical isotropy and thickness uniformity as compared with the melt extrusion method, and can obtain a film with few contained foreign substances, the optical functional film used for a display device or the like is It is mainly manufactured by a solution casting method.

  An outline of this solution casting method will be described. First, a polymer such as cellulose triacetate is dissolved in a mixed solvent containing methylene chloride or methyl acetate as a main solvent to prepare a dope. Next, a predetermined additive is mixed with this dope to prepare a casting dope. Thirdly, the casting dope is cast from the outlet of the casting die onto a traveling support such as a casting drum or an endless band (hereinafter referred to as a casting step). At this time, the casting dope between the outlet of the casting die and the support forms a casting bead. Thus, a casting film is formed on the support in the casting step. Fourth, the support conveys the casting membrane at a predetermined traveling speed. Then, the casting film that has become self-supporting by cooling on the support or drying is peeled off from the support as a wet film, and the wet film is dried (hereinafter referred to as a drying step). Finally, the dried wet film is wound up as a film. In this casting step, in order to prevent solidification of the casting dope at both ends of the casting die outlet, a solution for preventing solidification (hereinafter referred to as a solution) is applied to both ends of the casting bead. (Hereinafter, this method is referred to as a liquid method), and using a decompression chamber, the upstream side in the running direction of the support (hereinafter referred to as the back surface side) is reduced to a predetermined pressure with respect to the casting bead. The adhesion between the dope and the surface of the support can be improved, and bubbles and the like can be prevented from being mixed between the support and the cast film.

In recent years, with the rapid growth of demand for thin display devices such as LCDs and organic EL displays, it is strongly desired to increase the film forming speed of a solution film forming method which is a film manufacturing method. Patent Document 1 proposes to use a mixed solution in which a good solvent for a casting dope solute (polymer) and a poor solvent for a casting dope solute (polymer) are mixed as a solution used in the liquid method. And when using a mixed liquid with a low proportion of the poor solvent, the ear of the casting bead supplied with the mixed liquid becomes flexible, so that the casting bead flickering caused by suction air in the decompression chamber is reduced. It becomes possible to suppress. For this reason, Patent Document 1 reports that this liquid method is effective in increasing the film forming speed.
Japanese Patent Laying-Open No. 2005-104148

  It is known that the casting process is rate-limiting for shortening the time required for film formation by the solution casting method. That is, it is possible to improve the film-forming time in the solution film-forming method by increasing the speed of travel of the support in the casting process. However, as the traveling speed of the support increases (running speed of 80 m / min or more), the adhesion between the casting film and the peripheral surface of the casting drum decreases. In order to compensate for this decrease in adhesion, it is necessary to further reduce the pressure on the back side of the casting bead. However, when the solution casting method is performed in a state where the back side of the casting bead is decompressed to -100 Pa or less, the solution is scattered by this decompression, and the solution is transferred to the casting membrane via a decompression chamber or a support. mixing. The surface of the casting film was deformed due to the scattering of the scattered solution into the casting film, and as a result, planar failures such as deformation of the film surface occurred frequently.

  As a result of earnest examination of the cause of the occurrence of the surface failure of the film, the present inventor, as the degree of decompression of the decompression chamber increases, the solution is sucked into the decompression chamber, and further, a windshield seal provided in the decompression chamber It was found out that the cause was that the product was scattered on the product part of the casting bead via the plate, the side wall, or the support.

  In view of the above problems, an object of the present invention is to provide a solution casting method that enables high-speed film formation while avoiding surface failure of the film.

In the solution casting method of the present invention, a dope containing a polymer and a solvent is cast on a traveling support using a die, a cast film is formed from the dope on the support, and the dope The solution for preventing solidification of the dope is supplied to the side end of the casting bead formed by the dope from the die to the support, and the casting bead is viewed from the running direction of the support. The upstream side of the support is depressurized, and the solidification preventing solution is prevented from splashing on the upstream side of the support on the upstream side of the side end portion of the casting bead as viewed from the traveling direction of the support. A prevention member is arranged .

  The scattering prevention member preferably includes a partition plate to which the solidification preventing solution adheres and a recovery pipe that collects the solidification preventing solution attached to the partition plate.

  It is preferable that the running speed of the support is 80 m / min or more, and the upstream side of the casting bead is decompressed to -100 Pa or less. The support is preferably a peripheral surface of a casting drum.

  The main component of the solvent and the solidification preventing solution is preferably a good solvent for the polymer. The polymer preferably contains any of cellulose acylate and cyclic polyolefin. The good solvent preferably contains methylene chloride or methyl acetate.

The solution casting apparatus of the present invention includes a die for casting a dope containing a polymer and a solvent, a support for forming a casting film from the dope that has traveled and flowed out of the die, and solidification of the dope. The solidification prevention solution supply means for supplying the solidification prevention solution to be prevented to the side end of the casting bead formed by the dope from the die to the support, as viewed from the running direction of the support, A decompression chamber for depressurizing the upstream side of the casting bead, and an upstream side of the side end of the casting bead as viewed from the traveling direction of the support, and the solidification preventing solution is disposed on the upstream side of the support And a scattering prevention member for preventing scattering to the side .

  The scattering prevention member preferably includes a partition plate to which the solidification preventing solution adheres and a recovery pipe that collects the solidification preventing solution attached to the partition plate.

  It is preferable that the travel speed of the support is 80 m / min or more, and the decompression chamber decompresses the upstream side of the casting bead to -100 Pa or less. It is preferable that the support is a peripheral surface of a casting drum.

  The main component of the solvent and the solidification preventing solution is preferably a good solvent for the polymer. The polymer preferably contains any of cellulose acylate and cyclic polyolefin. The good solvent preferably contains methylene chloride or methyl acetate.

  According to the solution casting method of the present invention, in order to dispose the scattering prevention member in the scattering path of the solidification preventing solution sucked by the pressure reduction on the back side of the casting bead, the surface of the support for the solidification preventing solution, Scattering to the casting bead or casting film can be prevented. In particular, in the case of high-speed film formation in which the running speed of the support in the casting process is 80 m / min or more, it is necessary to depressurize the depressurization chamber to -100 Pa or less, and thus the effects of the present invention are more remarkably exhibited. . That is, according to the present invention, it is possible to perform solution film formation with high yield and high production efficiency.

  Since the anti-scattering member has a partition plate to which the solidification preventing solution adheres and a recovery pipe for collecting the solidification preventing solution attached to the partition plate, the solution sucked by the decompression chamber is separated from the partition plate. The adhering solution can be collected, and as a result, scattering of the solidification preventing solution can be prevented.

  The support is a peripheral surface of a rotating drum, and the traveling speed of the peripheral surface is 80 m / min or more. Since the pressure is reduced to -100 Pa or less using the pressure reducing chamber, the film forming speed is increased and the pressure reducing chamber is increased. Thus, it is possible to avoid a surface failure of the film that occurs with an increase in the degree of decompression of the film, and it is possible to perform solution casting with high yield and high production efficiency.

  Since the main component of the solvent and the solidification preventing solution is a good solvent for the polymer, solidification of the casting bead ears can be prevented, and fluttering of the casting bead ears can be suppressed.

  In addition, according to the solution casting apparatus of the present invention, since the anti-solidification solution has the scattering prevention member arranged in the scattering path of the anti-solidification solution sucked by the pressure reduction on the back side of the casting bead, It is possible to prevent the scattering to the surface of the support, to obtain a solution film with high yield and high production efficiency.

  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]
In FIG. 1, the schematic of the film manufacturing line 10 used by this embodiment is shown. The film production line 10 includes a stock tank 11, a casting chamber 12, a pin tenter 13, a clip tenter 14, a drying chamber 15, a cooling chamber 16, and a winding chamber 17.

  The stock tank 11 is provided with a stirring blade 11b rotated by a motor 11a and a jacket 11c, and a dope 21 serving as a raw material for the film 20 is stored therein. The stock tank 11 is always adjusted so that the temperature of the dope 21 is substantially constant by the jacket 11c provided on the outer peripheral surface thereof. The rotation of the stirring blade 11b suppresses aggregation of polymers and the like, and the quality of the dope 21 is kept homogeneous. Further, a pump 25 and a filtration device 26 are provided downstream of the stock tank 11. The method for preparing the dope 21 will be described later in detail.

  In the casting chamber 12, a casting die 30 for casting the dope 21, a casting drum (hereinafter referred to as a casting drum) 32 as a support, and a peripheral surface 32a of the casting drum 32 are disposed. A stripping roller 34 for stripping the casting film 33 from the casting drum 32 and a temperature adjusting device 35 for adjusting the internal temperature of the casting chamber 12 are provided. The decompression chamber 36 is disposed in the vicinity of the peripheral surface 32 a of the casting drum 32 between the casting die 30 and the peeling roller 34.

  An outlet 30 a (FIG. 2) that flows out of the dope 21 is provided at the tip of the casting die 30. The outflow port 30a casts the dope 21 on the peripheral surface 32a of the casting drum 32 disposed below the outlet 30a.

As a material of the casting die 30, precipitation hardening type stainless steel is preferable, and its thermal expansion coefficient is preferably 2 × 10 ⁻⁵ (° C. ⁻¹ ) or less. And what has corrosion resistance substantially the same as that made of SUS316 in a forced corrosion test with an electrolyte aqueous solution can be used as the material of the casting die 30, and further, in a mixed solution of dichloromethane, methanol and water for 3 months. Those having corrosion resistance that do not cause pitting (perforation) at the gas-liquid interface even when immersed are used. Furthermore, it is preferable that the casting die 30 is manufactured by grinding a material that has passed one month or more after casting. This prevents the dope 21 from flowing uniformly in the casting die 30 and prevents streaks or the like from occurring in the casting film described later. The finishing accuracy of the wetted surface of the casting die 30 is preferably 1 μm or less in terms of surface roughness and the straightness is 1 μm / m or less in any direction. The clearance of the slit of the outflow port 30a (FIG. 2) can be adjusted in the range of 0.5 mm to 3.5 mm by automatic adjustment. About the corner | angular part of the liquid-contacting part of the lip | tip end of the casting die 30, R is 50 micrometers or less over the whole width. The shear rate in the casting die 30 is preferably adjusted to be 1 (1 / second) to 5000 (1 / second). By using such a casting die 30, a casting film 33 without streaks and unevenness can be formed on the peripheral surface 32 a of the casting drum 32.

  The width of the casting die 30 is not particularly limited, but is preferably 1.1 to 2.0 times the width of the film as the final product. Moreover, it is preferable to attach a temperature controller (not shown) to the casting die 30 so that the temperature during film formation is maintained at a predetermined temperature. The casting die 30 is preferably a coat hanger type. Furthermore, it is more preferable that thickness adjusting bolts (heat bolts) are provided at predetermined intervals in the width direction of the casting die 30 and the casting die 30 is provided with an automatic thickness adjusting mechanism using heat bolts. The heat bolt is preferably formed into a film by setting a profile according to the amount of pump 25 (preferably a high precision gear pump) according to a preset program. Further, feedback control may be performed by an adjustment program based on a profile of a thickness meter (for example, an infrared thickness meter) (not shown) in the film production line 10. The thickness difference between any two points in the width direction of the product film, excluding the casting edge portion, is adjusted within 1 μm, and the difference between the minimum value and the maximum value in the width direction thickness is 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.

More preferably, a cured film is formed at the lip tip of the casting die 30. A method for forming the cured film is not particularly limited, and examples thereof include ceramic coating, hard chrome plating, and a nitriding method. In the case of using ceramics as the cured film, it is preferable to use a ceramic that can be ground, has low porosity, is not brittle, has good corrosion resistance, has good adhesion to the casting die 30, and does not have adhesion to the dope 21. Specific examples include tungsten carbide (WC), Al ₂ O ₃ , TiN, Cr ₂ O _{3 and the} like, and WC is particularly preferable. The WC coating can be performed by a thermal spraying method.

  The casting drum 32 formed in a substantially cylindrical or columnar shape is rotated around its axis 32b by a driving device. With this driving device, the peripheral surface 32a of the casting drum 32 rotates in a predetermined traveling direction Z1 at a predetermined speed (10 to 300 m / min). The peripheral surface 32a of the casting drum 32 is subjected to a chrome plating process and has sufficient corrosion resistance and strength. In order to keep the temperature of the peripheral surface 32 a of the casting drum 32 at a desired temperature, a heat transfer medium circulation device 37 is attached to the casting drum 32. The heat transfer medium maintained at a desired temperature by the heat transfer medium circulation device 37 passes through the heat transfer medium flow path in the casting drum 32, so that the temperature of the peripheral surface 32a of the casting drum 32 is increased. It can be maintained at a desired temperature.

  As shown in FIG. 2, in the casting process, the dope 21 (FIG. 1) is cast from the casting die 30 to the peripheral surface 32 a of the casting drum 32. At this time, the dope 21 (FIG. 1) cast from the casting die 30 forms a casting bead 21a over the peripheral surface 32a of the casting drum 32, and the dope 21 (FIG. 1) on the peripheral surface 32a. Becomes the casting film 33. The casting film 33 is conveyed at a predetermined traveling speed in the traveling direction Z <b> 1 by the rotation of the casting drum 32. The decompression chamber 36 creates a negative pressure on the back side of the casting bead 21a in order to stabilize the casting bead 21a. The decompression chamber 36 can be decompressed in the range of −2000 Pa to −10 Pa. As shown in FIG. 1, the casting film 33 having self-supporting property by cooling on the casting drum 32 is peeled off from the casting drum 32 by the peeling roller 34 to become a wet film 38.

  Further, the internal temperature of the casting chamber 12 is adjusted by the temperature control equipment 35 so as to be substantially constant within a predetermined range. The internal temperature of the casting chamber 12 is preferably 10 ° C or higher and 30 ° C or lower. In the casting chamber 12, a condenser (condenser) 39 for condensing and recovering the evaporated organic solvent and a recovery device 40 for recovering the condensed and liquefied solvent are provided. The organic solvent condensed and liquefied by the condenser 39 is recovered by the recovery device 40. The solvent is regenerated as a solvent for preparing a dope after being regenerated by a regenerator. The recovery device 40 preferably sets the saturation temperature of the solvent contained in the atmosphere in the casting chamber 12 to −10 ° C. or higher and 10 ° C. or lower.

  A pin tenter 13 that dries the wet film 38 to form the film 20 and a clip tenter 14 that stretches while drying the film 20 are provided downstream of the casting chamber 12. Desired optical properties are imparted to the film 20 by stretching the clip tenter 14 under predetermined conditions. The pin tenter 13 is a drying device having a plurality of pins as fixing means, and the clip tenter 14 is a drying device having a clip as gripping means. The clip tenter 14 may be omitted.

  An ear clip device 43 is provided downstream of the clip tenter 14. The edge-cutting device 43 is provided with a crusher 44. Here, both end portions of the film 20 are cut and then fed into the crusher 44 to be crushed. The crushed film strip is reused as a raw material dope.

  The drying chamber 15 is provided with a number of rollers 47 and an adsorption / recovery device 48. Further, a forced static elimination device (static elimination bar) 49 is provided downstream of the cooling chamber 16 provided in the drying chamber 15. In the present embodiment, a knurling roller 50 is provided on the downstream side of the forced static elimination device 49. Inside the winding chamber 17, a winding roller 51 and a press roller 52 are provided.

  As shown in FIGS. 1 and 2, the liquid method apparatus 60 includes nozzles 61a and 61b, a tank 62, and pipes 62a and 62b. The nozzles 61 a and 61 b are arranged at both ends of the outlet 30 a of the casting die 30. The tank 62 stores a solidification preventing solution (hereinafter referred to as a solution) for preventing the dope 21 from solidifying. The tank 62 is provided with a temperature controller (not shown) that keeps the temperature of the solution within a predetermined range. The pipes 62 a and 62 b connect the nozzles 61 a and 61 b and the tank 62. Further, the pipes 62a and 62b are provided with valves, pumps, flow meters, and the like, and by these operations, a desired amount of solution can be sent from the tank 62 to the nozzles 61a and 61b at a predetermined flow rate.

  It is preferable to supply this solution to the vicinity of the peripheral portion of the three-phase contact line formed by the both end portions 21b, the lip tip portion, and the outside air of the casting bead 21a. In addition, it is preferable to supply this solution to each side of the both end portions 21b at a rate of 0.1 mL / min to 1.0 mL / min in order to prevent foreign matter from mixing into the cast film. In addition, as a pump which supplies this solution, it is preferable to use a pump with a pulsation rate of 5% or less.

  The supply ports 61c (FIG. 4) of the nozzles 61a and 61b are formed in a substantially circular shape. 2 shows the nozzle 61a and the pipe 62a provided on one end side of the outlet 30a of the casting die 30. Similarly, the nozzle 61b and the pipe 62b are also provided on the casting die 30. Provided on the other end side. Details of the method for producing the solution will be described later.

  As shown in FIG. 3, the decompression chamber 36 includes an upper part 70 and a lower part 71. The upper part 70 is formed in a substantially rectangular parallelepiped shape having a hollow part 70 a, and connection holes 70 b and 70 c connected to the hollow part 70 a are provided on the upper surface of the upper part 70. In addition, an opening 70d connected to the hollow portion 70a is formed on the bottom surface of the upper portion 70.

  Pipes 72b and 72c are inserted into connection holes 70b and 70c provided on the upper surface of the upper part 70, respectively. The pipe 72b is connected to the suction device 73b (FIG. 1), and the pipe 72c is connected to the suction device 73c (FIG. 1).

  The lower portion 71 is formed on a box shape having a hollow portion 71d by an upper seal plate 75, a front seal plate 76, a pair of side seal plates 77 on the left and right sides, and an end seal plate 78. One side has an opening 71b and the bottom has an opening 71c. A packing 80 (FIG. 2) is provided between the front seal plate 76 and the casting die 30 to close the gap between the two.

  In the hollow portion 71d, a plurality of partition plates 85, 86a, 86b are arranged from the side seal plate 77 side toward the center side so as to be parallel to the side seal plate 77. These partition plates 85, 86 a, 86 b are fixedly attached to the upper seal plate 75 and the front seal plate 76. A holding plate 87 is fixed to the rear ends of the partition plates 86a and 86b so as to hold the interval between the partition plates 86a and 86b. A windshield seal plate 88 is provided between the holding plate 87 and the end seal plate 78 so as to be parallel to the side seal plate 77. By these partition plates 85, 86a, 86b, the airflow at both ends in the hollow portion 71d is substantially opposite to the traveling direction of the peripheral surface 32a. In addition, it is preferable that the partition plate 86b increases / decreases suitably according to the width | variety of the casting bead 21a, and makes the airflow in the hollow part 71d substantially reverse to the running direction Z1 of the surrounding surface 32a.

  The decompression chamber 36 is formed by fitting the upper portion 70 and the lower portion 71 so that the opening portion 70d and the opening portion 71a are hermetically connected. In addition, as shown in FIG. 2, the decompression chamber 36 is disposed so that the packing 80 abuts on the casting die 30 and eliminates the gap in the decompression zone composed of the opening 71b and the hollow portions 71d and 70a. ing.

  As shown in FIG. 3, a flange 85 a is provided at the lower end of the partition plate 85. The flange 85a is formed from the end surface on the opening 71b side of the partition plate 85 to the end surface on the hollow portion 71d side. The hollow portion 71d side of the jar 85a is connected to a liquid reservoir portion 85b for accumulating liquid that travels through the basin 85a. Further, in order to suck the liquid accumulated in the liquid reservoir 85b by the pipe 72b, the pipe 72b is arranged so that the liquid suction port provided at the tip of the pipe 72b is in the vicinity of the liquid reservoir 85b. The liquid reservoir 85 may be provided on both sides of the partition plate 85 as shown in FIG. 3, or may be provided only on one side. Therefore, the location where the liquid reservoir 85 is provided may be appropriately determined according to the decompression conditions in the casting process, the travel speed of the peripheral surface 32a, the position of the decompression chamber 36 and the nozzle 61a, and the like.

  The lower ends of the seal plates 75 to 78, the partition plates 85, 86a, 86b, the holding plate 87, and the wind-shielding seal plate 88 constituting the lower portion 71 are close to the peripheral surface 32a of the casting drum 32. It may be curved (FIG. 2).

  The suction devices 73b and 73c (FIG. 1) suck the air in the hollow portions 70a and 71d through the pipes 72b and 72c in accordance with a preset reduced pressure value. By the suction of the suction devices 73b and 73c, the internal pressure of the hollow portions 70a and 71d of the decompression chamber 36 is reduced to a predetermined pressure. Along with this pressure reduction, the vicinity of the opening 71b is also reduced to a predetermined pressure similarly to the hollow portions 70a and 71d. Thus, the decompression chamber 36 can decompress the back side of the casting bead 21a to a desired pressure. The reduced pressure value of the suction device 73b is set to be smaller than the reduced pressure value of the suction device 73c. In this specification, the reduced pressure value is expressed using a negative sign and a pressure difference.

  In the present specification, “reducing the pressure on the back side of the casting bead 21 a by −X (Pa) or less” is lower by X (Pa) or more than the downstream side in the running direction of the support (hereinafter referred to as the front side). This means that the back side is depressurized.

  As shown in FIG. 4, the seal plates 75 to 78, the partition plates 85, 86 a, 86 b, the holding plate 87, and the wind shielding seal plate 88 arranged in the decompression chamber 36 serve as rectifying plates. In addition, the decompression chambers 95 and 96 are formed in the hollow portion 71d by these seal plates 75 to 78. A region surrounded by the seal plates 75 and 76, the holding plate 87, and the partition plate 86a is defined as a decompression chamber 95. The decompression chamber 96 includes a region 96a and a region 96b, and a region sandwiched between the side seal plate 77 and the partition plate 85 and a region sandwiched between the partition plate 85 and the partition plate 86a are referred to as a region 96a. A region that is connected to the region 96a and surrounded by the side seal plate 77, the end seal plate 78, the holding plate 87, and the wind shield plate 88 is defined as a region 96b.

  The casting bead 21a is composed of both side end portions (hereinafter referred to as ear portions) 99a and a central portion (hereinafter referred to as product portion) 99b of the casting bead 21a. The ear | edge part 99a is a part cut out by the ear-cutting apparatus 43 after a drying process when it becomes the film 20 later. On the other hand, the product portion 99 b is a portion that finally becomes the film 20 wound up by the winding roller 51. In this specification, from the boundary line between the ear part 99a and the product part 99b and the extension line of the boundary line, an area located on the ear part 99a side and an area located on the product part 99b side are respectively It is referred to as an ear region and a product region.

  The supply ports 61c of the nozzles 61a and 61b for supplying the solution to the ear portion 99a are disposed in the vicinity of the side end portion 21b of the casting bead 21a. Further, the solution flows out from the supply port 61c provided at the tip of the nozzles 61a and 61b to the side end portion 21b of the casting bead 21a at a desired flow rate. The solution flowing out from the supply port 61c is supplied to the side end portion 21b through the lip portion in the vicinity of the casting port 30a. A part of the solution supplied to the side end portion 21 b is scattered in a predetermined direction by the air flow generated by the decompression chamber 36. The supply port 61c and the partition plate 85 are disposed at a position where the solution reaches the substantially central portion of the end surface 85c on the opening 71b side of the partition plate 85 when the solution is scattered along the airflow in the vicinity of the supply port 61c.

  The wind-shielding seal plate 88 is provided on the ear region of the hollow portion 71d, and is disposed so that the end surface thereof is in perpendicular contact with the surface of the end seal plate 78 and the surface of the holding plate 87. The pipe 72b is disposed in the vicinity of the end face 85d on the hollow portion 71d side of the partition plate 85 provided on the ear region of the hollow portion 71d.

  Next, an example of a method for manufacturing the film 20 using the film manufacturing line 10 will be described with reference to FIG. In the stock tank 11, the temperature of the dope 21 is adjusted to 25 to 35 ° C. by flowing a heat transfer medium inside the jacket 11c, and is always uniformed by the rotation of the stirring blade 11b. An appropriate amount of the dope 21 is appropriately sent from the stock tank 11 to the filtering device 26 by the pump 25 and filtered to remove impurities in the dope 21.

  The casting drum 32 travels at a predetermined traveling speed (80 m / min or more and 300 m / min or less) in the traveling direction Z1 by the driving device. Further, the temperature of the peripheral surface 32a of the casting drum 32 is adjusted by the heat transfer medium circulating device 37 so as to be substantially constant within a range of −10 ° C. to 10 ° C. Further, the dope 21 held in the range of 30 ° C. or more and 35 ° C. or less is cast from the casting die 30 onto the peripheral surface 32 a of the casting drum 32. The dope 21 forms a casting film 33 on the peripheral surface 32 a of the casting drum 32. Thus, on the peripheral surface 32a of the casting drum 32, the casting film 33 is cooled and solidified (gelled), and the casting film 33 can be provided with a self-supporting property. As the casting film 33 is cooled, a cross-linking point serving as a crystal base is formed, and gelation of the casting film 33 is promoted. Using the peeling roller 34, the casting film 33 that has become self-supporting due to gelation and the progress of gelation is peeled off from the casting drum 32 to form a wet film 38. The peeling roller 34 guides the wet film 38 to the pin tenter 13.

  In the pin tenter 13, a large number of pins are inserted and fixed at both end portions of the wet film 38, and then drying is promoted while the wet film 38 is conveyed to form the film 20. Then, the film 20 still containing the solvent is fed into the clip tenter 14.

  In the clip tenter 14, drying is promoted while the film 20 is transported after the both ends of the film 20 are sandwiched by a number of clips that run endlessly by the movement of the chain. At this time, the film 20 is stretched by expanding the width of the facing clip and applying tension in the width direction of the film 20. As described above, the stretching treatment in the width direction of the film 20 allows the molecules in the film 20 to be oriented, so that a desired retardation is imparted to the film 20 or the retardation of the film 20 can be adjusted.

  The film 20 sent out from the clip tenter 14 is cut at both end portions by the edge-cutting device 43. The film 20 whose both ends are cut is taken up by the take-up roller 51 in the take-up chamber 17 via the drying chamber 15 and the cooling chamber 16. Note that both end portions cut by the edge-cutting device 43 are crushed by the crusher 44 and reused as a dope preparation chip.

  The film 20 wound around the winding roller 51 is preferably at least 100 m in the longitudinal direction (casting direction). Moreover, it is preferable that the width | variety of the film 20 is 600 mm or more, and it is more preferable that they are 1400 m or more and 2500 m or less. The present invention is also effective when it is larger than 2500 mm. The present invention is also applied when manufacturing a thin film having a thickness of 15 μm or more and 100 μm or less.

  2 and 4, the dope 21 flows out from the outlet 30a of the casting die 30 onto the casting drum 32 while forming the casting bead 21a. By suction from the outflow pipe 72c (FIG. 3), the back side of the casting bead 21a is reduced to a predetermined pressure (−100 Pa or less) with respect to the front side of the casting bead 21a. Thus, the adhesion between the casting film 33 and the peripheral surface 32a of the casting drum 32 can be maintained even under high-speed film formation. The air sucked by the decompression is sucked into the decompression chamber 95 or the decompression chamber 96 through the opening 71 b of the decompression chamber 36.

  By suction from the suction device 73c, an airflow is formed from the back surface of the casting bead 21a to the hollow portion 71d of the decompression chamber 36 in a direction substantially opposite to the traveling direction of the casting drum 32. On the other hand, in the region 96b, an air flow from the ear region to the product region is generated by the arrangement position of the pipe 72c and the outer width seal 76.

  The solution flowing out from the supply port 61c flows down to the side end portion 21b of the casting bead 21a. At this time, a part of the solution flowing out from the supply port 61c is scattered into the decompression chamber 36 due to the airflow generated in the vicinity of the supply port 61c of the nozzle 61a. The solution scattered along the airflow reaches the end face 85c of the partition plate 85 provided in the vicinity of the nozzle 61a. Thus, the partition plate 85 can prevent the solution from flowing down directly to the peripheral surface 32 a of the casting drum 32.

  In addition, the pipe 72b disposed in the vicinity of the end face 85d sucks air or a solution near the tip of the pipe 72b according to the suction pressure value set by the suction device 73b. In this way, the solution adhering to the end face 85c and accumulating in the liquid reservoir 85b via the gutter 85a and the solution splashing in the vicinity of the pipe 72b are sucked through the pipe 72b. In this way, the pipe 72b can prevent the solution from flowing down directly to the peripheral surface 32a of the casting drum 32.

  Furthermore, of the solution that scatters in the decompression chamber 36, the solution that has not been sucked by the pipe 72b reaches the region 96b. The solution scattered according to the airflow in the region 96b reaches the windshield seal plate 88 provided on the ear region side. The solution that has reached the windshield seal plate 88 flows down to the casting drum 32 on the ear region directly below the windshield seal plate 88 while traveling along the lower end of the windshield seal plate 88. The solution that has flowed down to the casting drum 32 is scattered by the ear 99a of the casting bead 21a by the rotation of the casting drum 32. Thus, the wind-shielding sealing plate 88 can prevent the solution from splashing on the product part 99b of the casting bead 21a.

  When the degree of decompression by the decompression chamber 36 is −100 Pa or less with respect to the front surface side of the casting bead 21 a, the end surface 88 a (FIG. 2) on the upper portion 70 side of the wind shielding seal plate 88 and the circumference of the casting drum 32. It is preferable that the distance L1 (FIG. 2) with the surface 32a is 30 mm or more. Moreover, when this pressure reduction degree is -300 Pa or less, since solution scattering becomes remarkable, the effect of this invention becomes more remarkable. Note that when the degree of vacuum is −300 Pa or less, L1 is preferably 80 mm or more. The wind-shielding seal plate 88 that satisfies such conditions can prevent the solution sucked into the decompression chamber 36 from scattering to the product part 99b.

  In the present invention, the solution flowing out from the supply port 61c is sucked into the decompression chamber 36, and the sucked solution is finally prevented from scattering to the casting bead 21a and the casting film 33. The solution scattering path means from the supply port 61c to the casting bead 21a. By disposing a scattering preventing member such as the partition plate 85 and the wind shielding seal plate 88 on the scattering path, the surface of the film 20 is provided. State failure can be avoided.

  Moreover, the effect of the present invention is more remarkably exhibited by providing not only the scattering prevention member described above but also suction means capable of sucking the solution on the scattering path. For example, suction means such as piping capable of sucking the solution scattered in the decompression chamber 96b may be provided on the inner surface side of the end seal plate 78 in contact with the decompression chamber 96b.

  In the above embodiment, the pipe 72b capable of sucking the solution is disposed in the vicinity of the end face 85d of the partition plate 85. However, the present invention is not limited to this, and suction means capable of sucking the solution attached to the windshield seal plate 88 and the partition plate 86a. May be provided. In addition to this suction means, a tub and a liquid reservoir similar to the tub 85a and the liquid reservoir 85b may be provided on the windshield seal plate 88 and the partition plate 86a.

  In the above embodiment, the decompression chamber 36 is composed of the upper part 70 and the lower part 71. However, the decompression chamber 36 in the present invention is not limited to this, and the upper part 70 and the lower part 71 are integrally formed. May be. In other words, the decompression chamber 36 has an opening 71b for decompressing the back side of the casting bead 21a, and hollow portions 70a and 70d for sending air sucked from the opening 71b to the pipes 72b and 72c. It ’s fine.

  In the solution casting method of the present invention, when casting a dope, two or more types of dopes are simultaneously co-cast and laminated, or a plurality of dopes are sequentially co-cast. Sequential lamination co-casting can be performed. In addition, you may combine both casting. When performing simultaneous lamination and co-casting, a casting die to which a feed block is attached may be used, or a multi-manifold casting die may be used. However, it is preferable that at least one of the thickness of the layer on the air surface side and the thickness of the layer on the support side is 0.5 to 30% of the thickness of the entire film of the film composed of multiple layers by co-casting. . In addition, when performing simultaneous lamination and co-casting, it is preferable that the high-viscosity dope is enveloped by the low-viscosity dope when the dope is cast from the die slit to the support, and is formed from the die slit to the support. Of the casting beads, the dope in contact with the outside world preferably has a higher alcohol composition ratio than the inner dope.

  In the above embodiment, it has been described that the shape of the supply port 61c of the nozzle 61a is formed in a substantially circular shape. However, the shape is not limited to this, and other shapes such as an ellipse or an ellipse may be used. Further, the solution scattered in the decompression chamber 36 may be sucked together with the decompression of the back surface of the casting bead 21a by using the suction device 72c and the pipe 72c without providing the suction device 72b and the pipe 72b.

  The present invention can also be applied to a solution casting method using a casting band that moves over a rotating roller instead of the casting drum 32.

  Hereinafter, the raw materials used when preparing the dope 21 in the present invention will be described.

In the present embodiment, cellulose acylate is used as the polymer, and cellulose triacetate (TAC) is particularly preferable as the cellulose acylate. Among cellulose acylates, those in which the substitution degree of the acyl group to 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 in the hydroxyl group of cellulose, A is the substitution degree of the acetyl group, and B is 3 carbon atoms. The substitution degree of the acyl group of ˜22. In addition, it is preferable that 90 mass% or more of TAC is a particle | grain of 0.1-4 mm. However, the polymer that can be used in the present invention is not limited to cellulose acylate, and the same effect can be obtained even when a polymer containing cellulose acetate, propionate, cellulose acetate butyrate, or the like is used.
(I) 2.5 ≦ A + B ≦ 3.0
(II) 0 ≦ A ≦ 3.0
(III) 0 ≦ B ≦ 2.9

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

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

  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. The sum of the degree of substitution of the hydroxyl groups at the 2nd, 3rd and 6th positions by acetyl groups is DSA, and the sum of the degree of substitution of the hydroxyl groups at the 2nd, 3rd and 6th positions by acyl groups other than acetyl groups When DSB is DSB, the value of DSA + DSB is preferably 2.22 to 2.90, and particularly preferably 2.40 to 2.88.

  The DSB is preferably 0.30 or more, particularly preferably 0.7 or more. Further, 20% or more of DSB is preferably a substituent at the 6-position hydroxyl group, more preferably 25% or more, further preferably 30% or more, and particularly preferably 33% or more. Further, the value of DSA + DSB at the 6-position of cellulose acylate is 0.75 or more, more preferably 0.80 or more, and particularly preferably cellulose acylate of 0.85 or more. These cellulose acylates By using, a solution (dope) having better solubility can be produced. In particular, when a non-chlorine organic solvent is used, a dope having excellent solubility, low viscosity and excellent filterability can be produced.

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

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

  Solvents for preparing the dope include aromatic hydrocarbons (eg, benzene, toluene, etc.), halogenated hydrocarbons (eg, methylene chloride, 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 the above halogenated hydrocarbons, halogenated hydrocarbons having 1 to 7 carbon atoms are preferably used, and methylene chloride is most preferably used. In addition to methylene chloride, one to several kinds of alcohols having 1 to 5 carbon atoms from the viewpoint of physical properties such as solubility of TAC, peelability from cast film support, mechanical strength and optical properties of the film It is preferable to mix. As for content of alcohol, 2-25 mass% is preferable with respect to the whole solvent, More preferably, it is 5-20 mass%. Examples of the alcohol include methanol, ethanol, n-propanol, isopropanol, n-butanol, etc., but methanol, ethanol, n-butanol, or a mixture thereof is preferably used.

  Recently, solvent compositions that do not use methylene chloride have been studied for the purpose of minimizing environmental impact. In this case, an ether having 4 to 12 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 preferable. Sometimes used. 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 a solvent.

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

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

(Cyclic polyolefin)
In the said embodiment, although it described that a cellulose acylate was used as a raw material used when preparing dope 21, this invention is not restricted to this, You may use cyclic polyolefin. Hereinafter, the cyclic polyolefin that can be used as the polymer of the present invention will be described.

  The cyclic polyolefin in the present invention is a polymer having a cyclic olefin structure. Examples thereof include (1) a norbornene-based polymer, (2) a monocyclic olefin polymer, and (3) a cyclic conjugated diene. There are polymers, (4) vinyl alicyclic hydrocarbon polymers, hydrides of (1) to (4), and any of these can be used in the present invention.

  Next, details of the solution for preventing immobilization of the dope 21 in the present invention will be described. As the solution supplied to the side end portion 21b of the bead 21a, a good solvent for the solute (polymer) of the dope or a mixed solution in which a poor solvent is mixed with the good solvent (polymer) is used. Moreover, when mixing a poor solvent with a good solvent, it is good to make the ratio of all the poor solvents to mix into less than 20 weight% with respect to all the solutions, Preferably it is 13 weight% or less. The good solvent and the poor solvent are not limited to the above-described embodiments. Moreover, it is preferable that the solution contains the same component as the good solvent and the poor solvent contained in the dope to be used.

(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. Among these, it is more preferable to use a halogenated hydrocarbon having 1 to 7 carbon atoms, and it is most preferable to use dichloromethane.

(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. Among these, it is more preferable to use alcohol having 1 to 12 carbon atoms, and it is most preferable to use methanol. In addition, as a good solvent or a poor solvent constituting the solution, a mixture of a plurality of compounds may be used.

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

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

[composition]
The prescription of the compound used for the preparation of the dope 21 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
The solid content (solute) with the composition ratio of 87% by weight of dichloromethane
Methanol 12% by weight
n-Butanol 1% by weight
The dope 21 was prepared by appropriately adding to a mixed solvent consisting of The solid content concentration of the dope 21 was adjusted to 19.3% by weight. The dope 21 was filtered with a filter paper (Toyo Filter Paper Co., Ltd., # 63LB), further filtered with a sintered metal filter (Nihon Seisen Co., Ltd. 06N, nominal pore size 10 μm), and further filtered with a mesh filter. Placed in tank 11.

[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.

[Preparation of dope]
A dope 21 was prepared using a dope production line (not shown). The plurality of solvents were mixed and stirred well in a 4000 L stainless steel dissolution tank having a stirring blade to obtain a mixed solvent. In addition, as each raw material of a solvent, the thing whose water content is 0.5 weight% or less was used. Next, TAC flaky powder was gradually added from the hopper. The TAC powder is placed in a dissolution tank and initially stirred under a condition in which a dissolver type eccentric agitator that stirs at a peripheral speed of 5 m / sec and a stirrer having an anchor blade on the central axis are agitated at a peripheral speed of 1 m / sec. Dispersed for minutes. The temperature at the start of dispersion was 25 ° C., and the final temperature reached 48 ° C. Further, the amount of the additive solution prepared in advance was adjusted from the additive tank with a valve so that the total amount became 2000 kg. After finishing the dispersion of the additive solution, the high speed stirring was stopped. Then, the peripheral speed of the anchor blade of the stirrer was set to 0.5 m / sec, and the mixture was further stirred for 100 minutes to swell the TAC flakes to obtain a swelling liquid. Until the end of swelling, the inside of the dissolution tank was pressurized to 0.12 MPa with nitrogen gas. The inside of the dissolution tank at this time was kept in a state where there was no problem in terms of explosion prevention because the oxygen concentration was less than 2 vol%. The amount of water in the swelling liquid was 0.3% by weight.

  The swelling liquid was sent from the dissolution tank to the jacketed pipe using a pump. The swelling liquid was heated to 50 ° C. with a jacketed pipe, and further heated to 90 ° C. under a pressure of 2 MPa to completely dissolve. The heating time at this time was 15 minutes. Next, the temperature of the dissolved liquid was lowered to 36 ° C. with a temperature controller, and the solution was passed through a filtration device having a filter medium having a nominal pore diameter of 8 μm to obtain a dope (hereinafter referred to as a dope before concentration). At this time, the primary pressure in the filtration device was 1.5 MPa, and the secondary pressure was 1.2 MPa. The filters, housings and pipes exposed to high temperatures were made of Hastelloy (trade name) alloy and had excellent corrosion resistance, and were equipped with a jacket for circulating a heat transfer medium for heat insulation and heating.

The pre-concentration dope thus obtained was flash evaporated in a flash device at 80 ° C. and normal pressure, and the evaporated solvent was recovered by a condenser. The solid concentration of the dope 21 after the flash was 21.8% by weight. The condensed solvent was recovered with a recovery device to be reused as a dope preparation solvent. Then, after regenerating with a regenerating apparatus, the solution was sent to the solvent tank 11. Distillation and dehydration were performed in the recovery device and the regeneration device. The flash tank of the flash device was equipped with a stirrer (not shown) having an anchor blade on the stirring shaft, and the dope flashed at a peripheral speed of 0.5 m / second was stirred by the stirrer to perform defoaming. The temperature of the dope in this flash tank was 25 ° C., and the average residence time of the dope in the tank was 50 minutes. The dope 21 was sampled and the shear viscosity measured at 25 ° C. was 450 Pa · s at a shear rate of 10 (sec ⁻¹ ).

  Next, bubbles were removed by irradiating the dope 21 with weak ultrasonic waves. Thereafter, the filter was passed through the pump while being pressurized to 1.5 MPa using a pump. In the filtration apparatus, first, a sintered fiber metal filter having a nominal pore diameter of 10 μm was passed, and then a sintered fiber filter having a same pore diameter of 10 μm was passed. Respective primary pressures were 1.5 MPa and 1.2 MPa, and secondary pressures were 1.0 MPa and 0.8 MPa. The dope temperature after filtration was adjusted to 36 ° C., and the dope 21 was sent and stored in a 2000 L stainless steel stock tank. In the stock tank 11, the dope 21 was constantly stirred by the rotation of the stirrer 11b with a peripheral speed of 0.3 m / sec. In addition, when the dope was prepared from the dope before concentration, no problem such as corrosion occurred at all in the wetted part of the dope.

  Using the film production line 10, the film 20 was made from the dope 21 described above. The gear pump 25 has a function of increasing the pressure on the primary side by an inverter motor. The gear pump 25 is fed by performing feedback control so that the pressure on the primary side becomes 0.8 MPa. A gear pump 25 having a volumetric efficiency of 99.2% and a flow rate fluctuation rate of 0.5% or less was used. The outflow pressure was 1.5 MPa. Under the control of a control unit (not shown), the gear pump 25 sent the dope 21 of the stock tank 11 to the casting die 30 via the filtration device 26. In the filtering device 26, the dope 21 was filtered.

  The temperature of the casting die 30 and the piping during film formation was kept at approximately 36 ° C. by the temperature controller provided in the casting die 30. The casting die 30 was a coat hanger type die. The casting die 30 was provided with thickness adjusting bolts at a pitch of 20 mm and equipped with an automatic thickness adjusting mechanism using a heat bolt. The heat bolt can set a profile according to the liquid feed amount of the gear pump 25 by a preset program, and is fed back by an adjustment program based on a profile of an infrared thickness meter (not shown) installed in the film production line 10. The thing which has the performance which can also be controlled was used. In the film excluding the end portion of 20 mm, the thickness difference between two arbitrary points separated by 50 mm was within 1 μm, and the thickness variation in the width direction was adjusted to 3 μm / m or less. The overall thickness was adjusted to ± 1.5% or less.

As a material for forming the casting die 30, precipitation hardening stainless steel having a thermal expansion coefficient of 2 × 10 ⁻⁵ (° C. ⁻¹ ) or less was used. This had a corrosion resistance substantially equal to that of SUS316 in a forced corrosion test with an aqueous electrolyte solution. Further, even when immersed in a mixed solution of dichloromethane, methanol and water for 3 months, it had corrosion resistance that did not cause pitting (opening) at the gas-liquid interface. The finishing accuracy of the liquid contact surface of the casting die 30 was 1 μm or less in terms of surface roughness, the straightness was 1 μm / m or less in any direction, and the slit clearance was adjusted to 1.5 mm. About the corner | angular part of the liquid-contact part of the lip tip of the casting die 30, what was processed so that R might be set to 50 micrometers or less over the full width of a slit was used. The shear rate of the casting dope 51 inside the casting die 30 was in the range of 1 (1 / second) to 5000 (1 / second). Further, a WC (tungsten carbide) coating was performed on the lip end of the casting die 30 by a thermal spraying method to provide a cured film.

  A cylindrical casting drum 32 was used as a support. The peripheral surface 32a of the casting drum 32 was subjected to chrome plating and mirror finishing, and the surface roughness of the peripheral surface 32a was 0.05 μm or less. The material is made of SUS316 and has sufficient corrosion resistance and strength. The casting drum 32 was rotated by driving the shaft 32b under the control of a control unit (not shown). The casting speed, that is, the speed in the traveling direction of the peripheral surface 32b was set to about 100 m / min. At this time, the speed fluctuation of the casting drum 32 was set to 0.5% or less. Further, both end positions of the casting drum 32 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 fluctuation in the vertical direction between the tip of the die lip and the casting drum 32 immediately below the casting die 30 was set to 200 μm or less. The casting drum 32 was installed in the casting chamber 12 having wind pressure fluctuation suppressing means (not shown).

The casting drum 32 used was capable of feeding a heat transfer medium inside so that the temperature T1 of the peripheral surface 32a could be adjusted. The heat transfer medium circulation device 37 caused the heat transfer medium to flow through the casting drum 32. The temperature of the central portion of the peripheral surface 32a immediately before casting was 0 ° C., and the temperature difference between both ends of the peripheral surface 32a was 6 ° C. or less. The casting drum 32 preferably has no surface defects, has no pinholes of 30 μm or more, has 1 to 30 μm pinholes / m ² or less, and has 2 pinholes of less than 10 μm / Those with m ² or less were used.

  The oxygen concentration in the dry atmosphere on the casting drum 32 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 12, a condenser (condenser) 39 was provided, and its outlet temperature was set to -3 ° C. Static pressure fluctuations in the vicinity of the casting die 30 were suppressed to ± 1 Pa or less.

  In addition, a decompression chamber 36 for decompressing the back side of the casting bead 21a was installed on the primary side of the casting die 30 (upstream in the running direction of the peripheral surface 32a). Moreover, the decompression chamber 36 provided with the wind-shielding sealing board 88 and the piping 72b was used. The nozzle 61a and the partition plate 85 were respectively arranged at positions where the solution from the supply port 61c was scattered in the substantially central portion of the end surface of the partition plate 85 by the airflow in the vicinity of the supply port 61c. The distance L1 between the end surface 88a of the windshield seal plate 88 and the peripheral surface of the casting drum 32 was 80 mm. The degree of decompression of the decompression chamber 36 is adjusted so that a pressure difference of 1 Pa to 5000 Pa is generated between the front side and the back side of the casting bead, and the degree of decompression is adjusted according to the traveling speed of the peripheral surface 32a. . At that time, the pressure difference on both sides of the casting bead 21a was set so that the length of the casting bead 21a was 20 mm to 50 mm. A jacket (not shown) was attached to make the internal temperature of the decompression chamber 36 constant at a predetermined temperature. A heat transfer medium adjusted to 35 ° C. was supplied into the jacket. The decompression chamber 36 is provided with a mechanism that can be set to a temperature higher than the condensation temperature of the gas around the casting portion. Labyrinth packing (not shown) was provided on the front and back of the bead at the outlet 30a.

  Further, a mixed solvent A containing 50% by weight of dichloromethane and 50% by weight of n-butanol was prepared and used as a solution. This solution was stored in the tank 62 of the liquid method apparatus 60, and the temperature of the solution was maintained in the range of 20 ° C to 30 ° C.

  Nozzles 61 a and 61 b for supplying a solution for preventing the dope 21 from solidifying were disposed at both ends of the casting die 30. The nozzles 61a and 61b are arranged so that the distance CL1 between the supply port 61c and the position 90 is 2 mm and the distance CL2 between the supply port 61c and the side end 21b of the casting bead 21a in the width direction of the casting film 33 is 2 mm. Were arranged respectively.

  In the film production line 10, the dope 21 was cast at a dry thickness of 80 μm from the casting die 32 onto the peripheral surface 32 a to form a casting film 33. A casting bead 21a was formed from the outlet 30a to the peripheral surface 32a. The decompression chamber 36 decompressed the back side of the casting bead 21a with a predetermined decompression value. The liquid method apparatus 61 supplied the solution to both end portions 21b of the casting bead 21a.

  In the film production line 10, the dope 21 was cast from the casting die 30 onto the peripheral surface 32 a of the casting drum 32 with a dry thickness of 80 μm to form a casting film 33. The casting film 33 having self-supporting property was peeled off by the peeling roller 34 to obtain a wet film 38. With the pin tenter 13 and the clip tenter 14, the wet film 38 was dried to a predetermined residual solvent amount to obtain a film 20. The decompression chamber 36 decompressed the back side to −550 Pa with respect to the front side of the casting bead 21a. The reduced pressure value of the suction device 73b was −600 Pa. At this time, the solution did not scatter to the casting bead 21a, and the surface failure of the film 20 due to the scatter did not occur.

  The pipe 72b was removed from the casting die 30 in Example 1, and the solution casting method was performed under the same conditions as in Example 1. At this time, the solution did not scatter to the casting bead 21a, and the surface failure of the film 20 due to the scatter did not occur.

  In the film production line 10 in Example 2, the positions of the nozzles 61a and 61b were disposed away from the ears 99a. Otherwise, the solution casting method was performed under the same conditions as in Example 1. At this time, some solution was scattered to the casting bead 21a (only the ear portion 99a), but no surface failure of the film 20 due to this scattering occurred.

  The windshield seal plate 88 was removed from the decompression chamber 36 in Example 2, and the solution casting method was performed under the same conditions as in Example 1 except that. At this time, some solution was scattered to the casting bead 21a (only the ear portion 99a), but no surface failure of the film 20 due to this scattering occurred.

<Comparative Example 1>
In Example 3, the windshield seal plate 88 was removed from the decompression chamber 36. The traveling speed of the peripheral surface of the casting drum 32 was 100 m / min, and the reduced pressure value of the suction device 73b was −550 Pa. The decompression chamber 36 decompressed the back side of the casting bead 21a with a predetermined decompression value. This reduced pressure value was -500 Pa with respect to the front side of the casting bead 21a. For these three kinds of reduced pressure values, the solution casting method was carried out under the same conditions as in Example 1. At this time, the solution splattered to the product part 99b, and a planar failure due to the splattering occurred.

  By the solution casting method or the solution casting equipment of the present invention, scattering of the solidification preventing solution that induces a surface failure of the film to the support surface can be prevented. In particular, the effect of the present invention is more remarkably exhibited under high-speed film formation in which it is necessary to increase the degree of decompression of the decompression chamber. That is, according to the present invention, it is possible to perform solution deposition with a high yield and a short deposition time.

It is explanatory drawing which shows the outline | summary of a film manufacturing line. It is a sectional side view of the decompression chamber in a casting process. It is a perspective view which shows the outline | summary of a pressure reduction chamber. It is the IV-IV sectional view taken on the line of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Film production line 21 Dope 21a Casting bead 21b Side edge part 30 Casting die 32 Casting drum 33 Casting film 34 Stripping roller 36 Decompression chamber 60 Liquid method apparatus 61b, 61b Nozzle 72c, 72c Piping 73b, 73c Suction apparatus 85 Ear side seal 85a 樋 85b Liquid reservoir 88 Wind shield plate 95, 96 Decompression chamber 96a, 96b Area 99a Ear 99b Product part

Claims (14)

A dope containing a polymer and a solvent is cast on a traveling support using a die,
Forming a cast film from the dope on the support;
A solution for preventing solidification of the dope is supplied to the side end of the casting bead formed by the dope from the die to the support;
Depressurizing the upstream side of the casting bead as viewed from the traveling direction of the support,
Spattering that prevents the solution for preventing solidification from splashing on the upstream side of the product part of the casting bead on the support, on the upstream side of the side end of the casting bead as viewed from the traveling direction of the support. A solution casting method comprising disposing a prevention member.   2. The solution manufacturing method according to claim 1, wherein the scattering prevention member includes a partition plate to which the solidification preventing solution adheres and a recovery pipe that collects the solidification preventing solution attached to the partition plate. Membrane method. The traveling speed of the support is 80 m / min or more,
The solution casting method according to claim 1 or 2, wherein the upstream side of the casting bead is decompressed to -100 Pa or less.   The solution casting method according to claim 1, wherein the support is a peripheral surface of a casting drum.   The solution casting method according to any one of claims 1 to 4, wherein the main component of the solvent and the solidification preventing solution is a good solvent for the polymer.   The solution casting method according to any one of claims 1 to 5, wherein the polymer contains any of cellulose acylate and cyclic polyolefin.   The solution casting method according to claim 5 or 6, wherein the good solvent contains methylene chloride or methyl acetate. A die for casting a dope comprising a polymer and a solvent;
A support that travels and forms a cast film from the dope flowing out of the die;
A solidification preventing solution supply means for supplying a solidification preventing solution for preventing solidification of the dope to a side end portion of a casting bead formed by the dope from the die to the support;
A decompression chamber for decompressing the upstream side of the casting bead as viewed from the traveling direction of the support;
It is arranged on the upstream side of the side end portion of the casting bead as viewed from the traveling direction of the support, and the solidification preventing solution is scattered on the upstream side of the product portion of the casting bead on the support. An anti-scattering member to prevent,
A solution casting apparatus comprising:
The scattering prevention member includes a partition plate to which the solidification preventing solution adheres;
The solution casting apparatus according to claim 8, further comprising a recovery pipe that recovers the solidification preventing solution attached to the partition plate. The traveling speed of the support is 80 m / min or more,
The solution casting apparatus according to claim 8 or 9, wherein the decompression chamber decompresses the upstream side of the casting bead to -100 Pa or less.   The solution casting apparatus according to claim 8, wherein the support is a peripheral surface of a casting drum.   The solution casting apparatus according to any one of claims 8 to 11, wherein a main component of the solvent and the solidification preventing solution is a good solvent for the polymer.   The solution casting apparatus according to any one of claims 8 to 12, wherein the polymer contains one of cellulose acylate and cyclic polyolefin.   The solution casting apparatus according to claim 12 or 13, wherein the good solvent contains methylene chloride or methyl acetate.

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