JP5571637B2 - Casting equipment and solution casting method - Google Patents

Description

The present invention relates to a flow extends 備及 beauty solution casting method.

  Polymer films having light permeability (hereinafter referred to as films) are lightweight and easy to mold, and thus are widely used as optical films. Among these, cellulose ester films using cellulose acylate are used as optical films (polarizing plate protective films, retardation films, etc.) for liquid crystal display devices in addition to photographic photosensitive films.

  The film is produced by a solution casting method. In the solution casting method, the temperature of a polymer solution containing a polymer and a solvent (hereinafter referred to as a dope) was adjusted using a casting die disposed in a casting chamber toward a moving support. The film is poured toward the support to form a belt-like cast film on the support (hereinafter referred to as a film forming step). Next, the solvent is evaporated from the casting film until the casting film can be conveyed (hereinafter referred to as a film drying step). Thereafter, the cast film that can be conveyed is peeled off from the support to form a wet film (hereinafter referred to as a peeling step). Then, the solvent is evaporated from the wet film to form a film (hereinafter referred to as a film drying process).

  As a support used in this solution casting method, an annular band that is looped around a plurality of rollers is known. By using this annular band, the film formation process, the film drying process and the stripping process can be repeated, and as a result, the production efficiency of the film can be improved.

  However, when the solution casting method is performed for a long time, the annular band may be detached from the predetermined annular path. When the solution casting method is performed in a state where the annular band is out of the annular path, the uniformity of the obtained film, in particular, the thickness in the width direction, the surface state, and the uniformity of the optical characteristics are impaired.

  As a method for adjusting the moving direction of the annular band, there is known an invention in which a driving drum or a driven drum around which the annular band is wound is changed (for example, Patent Documents 1 and 2).

Japanese Patent Laid-Open No. 2002-245452 JP-A-10-202722

However, in the method for controlling the moving direction of the annular band in Patent Documents 1 and 2, in the following cases (1) to (3), the accuracy of controlling the moving direction of the annular band is lowered. As a result, it becomes difficult not only to return the annular band to the annular path, but also the annular band comes off from the annular path more greatly.
(1) When the moving speed of the annular band is improved for the purpose of improving the production efficiency of the solution casting method, etc. (2) When the moving speed of the annular band changes (3) Film forming process, film drying When the amount of fluctuation in the temperature of the annular band is large during the repeated process and stripping process

  Thus, there is a need for a method for controlling the direction of movement of an annular band that can more reliably place the moving annular band in the annular path.

  The present invention solves such a problem, and an object thereof is to provide a moving direction control device for an annular band, a casting facility, and a solution casting method.

Casting apparatus of the present invention, wound around the drive drum and a driven drum arranged horizontally and parallel to one another, moved by the rotation of the driving motion the drum a preset cyclic path in the width direction, cast polymer And an annular band that supports the film made of the dope containing the solvent, a casting die that flows out the dope toward the portion of the annular band that is wound around the drive drum, and a solvent from the film by applying dry air to the film a membrane dryer to evaporate and a stripping device for stripping the film from the annular band, is arranged in the both widthwise outer at the lower portion of the ring watering, annular band guide for guiding the widthwise end face of the ring-shaped band and a mechanism, the band guide mechanism includes a roller body which can guide the widthwise end face of the annular band in the circumferential surface, and a roller shaft for supporting the roller body, toward its drive drum from the driven drum A plurality of guide rollers arranged so as to approach the center in the width direction of the annular path, and a support groove capable of guiding the width direction end surface of the annular band is formed on the peripheral surface of the roller body. The guide rollers are alternately arranged on one end side and the other end side in the width direction of the annular path in the moving direction of the annular band, and the distance between the bottom surface of the support groove of each guide roller and the annular path is 0 mm or more. 20 mm or less.

Guide rollers movably disposed between a retreated position away from the proximity position and proximity position close to the ring-shaped path, the spacing between the bottom surface and the annular passage when the guide roller is in the close position It is preferable that the distance is . The guide roller is preferably biased toward the center in the width direction of the ring-shaped path.

A driven drum transition portion one end to change the Supporting dynamic drum between the second posture closer to the drive moving the drum than the first position及beauty other end one end close to the drive moving the drum than the other end, the ring-shaped bands and disengaged direction detection unit for detecting a direction that deviates from a ring-shaped path, that a driven drum posture control unit for controlling the Supporting dynamic drum transition portion based on the direction outer Re direction detection unit is outside of detecting Is preferred.

Drive moving the drum is provided with a drive drum body capable of supporting a rear surface of the ring-shaped band in the circumferential surface, and a drum driving shaft for supporting the driving dynamic drum body, driving dynamic drum body is provided in the width direction central portion and a large-diameter drum portion provided on the widthwise ends small diameter drum portion, it is preferable that the ring-shaped path is set on the circumferential surface of the small diameter roller portion.

The solution casting method of the present invention, wound around the drive drum and a driven drum arranged horizontally and parallel to one another, of the annular band to move by the rotation of the drive drum a preset cyclic path in the width direction, drive towards wound around portions dynamic drum, and discharging the dope containing a polymer and a solvent, a film forming step of forming a film made of de-loop in the ring-shaped band, the drying air to the film on the annular band a film drying step of evaporating the film or al SOLVENTS addressed, a peeling step of peeling a film formed through the film drying step from the ring-shaped band, and guide the widthwise end face of the annular band by an annular band guide mechanism, have a movement control step for controlling the moving direction of the ring-shaped band, the band guide mechanism includes a guide capable roller body width direction end face of the annular band in the circumferential surface and a roller shaft for supporting the roller body Have A plurality of guide rollers arranged so as to approach the center in the width direction of the annular path from the drum toward the drive drum, and a support groove capable of guiding the end surface in the width direction of the annular band is formed on the peripheral surface of the roller body The plurality of guide rollers are alternately arranged in the moving direction of the annular band on one end side and the other end side in the width direction of the annular path, and the bottom surface of the support groove of each guide roller and the annular path The interval is 0 mm or more and 20 mm or less.

  According to the present invention, the moving annular band can be more reliably accommodated in the annular path regardless of the magnitude of the movement speed of the annular band, the fluctuation of the movement speed of the annular band, the amount of fluctuation of the temperature of the annular band, and the like. .

It is explanatory drawing which shows the outline | summary of solution casting apparatus. It is a side view which shows the outline | summary of a casting apparatus. It is a perspective view which shows the outline | summary of each component distribute | arranged in the casing of the casting apparatus. It is a block diagram which shows the outline | summary of a band moving part, a band moving direction control part, and a control part. It is explanatory drawing which shows the outline | summary of a one end disconnection detection part and an other end disconnection detection part. It is a top view which shows the outline | summary of the horizontal drum in which a rotating shaft exists in a reference position. It is a top view which shows the outline | summary of a horizontal drum when the one end side of a rotating shaft leaves | separates from a drive shaft rather than the other end side of the rotating shaft. It is a top view which shows the outline | summary of a horizontal drum when the other end side of a rotating shaft has left | separated from the drive shaft rather than the one end side of the rotating shaft. It is a perspective view which shows the outline | summary of a band guide mechanism. It is a perspective view which shows the outline | summary of the other end side guide roller. It is a side view which shows the outline | summary of an other end side guide roller. It is a top view which shows the outline | summary of the guide roller main body which can rock | fluctuate freely. It is a side view which shows the outline | summary of an other end side guide roller. It is a perspective view which shows the outline | summary of a stepped drum. It is a side view which shows the outline | summary of a stepped drum.

(Solution casting equipment)
As shown in FIG. 1, the solution casting apparatus 10 performs a casting apparatus 15 that creates a wet film 13 from a dope 12, a clip tenter 17 that obtains a film 16 by drying the wet film 13, and a wet film 13. A drying device 18 and a winding device 19 for winding the film 16 around a winding core are provided.

(Casting device)
As shown in FIG. 2, the casting apparatus 15 includes a casing 23 and a casting apparatus body disposed in the casing 23. The casting apparatus main body includes a casting support unit, a partition unit, a casting unit, a membrane drying unit, and a peeling member.

(Casting support unit)
The casting support unit includes horizontal drums 24 and 25 arranged horizontally and parallel to each other in the casing 23, a casting band 26 stretched over the horizontal drums 24 and 25, and a band moving unit.

  As shown in FIG. 3, the horizontal drum 24 includes a drive shaft 24A, a stainless steel drum body 24B attached to the drive shaft 24A, and a bearing (not shown) of the drive shaft. The horizontal drum 25 includes a rotating shaft 25A, a stainless steel drum body 25B that is pivotally attached to the rotating shaft 25A, and bearings 25AS provided at both ends of the rotating shaft 25A. An annular casting band 26 is wound around the horizontal drums 24 and 25. The casting band 26 is obtained by connecting both ends of a strip-shaped sheet material.

  Here, “horizontal” means that the crossing angles of the horizontal drums 24 and 25 with respect to the horizontal plane are 0 ° or more and 0.05 ° or less, respectively. The term “parallel” means that the crossing angle between the horizontal drums 24 and 25 is 0 ° or more and 0.05 ° or less.

  The casting band 26 is preferably made of stainless steel (for example, SUS316) having sufficient corrosion resistance and strength. For example, the width of the casting band 26 is preferably 1.1 to 2.0 times the casting width of the dope 12. The length of the casting band 26 is preferably 20 m or more and 200 m or less, for example. The thickness of the casting band 26 is preferably 0.5 mm to 2.5 mm, for example. The thickness unevenness of the casting band 26 is preferably 0.5% or less with respect to the total thickness. Further, the surface 26A on which the cast film is formed (hereinafter referred to as the cast surface) and the back surface 26B in contact with the drum bodies 24B and 25B are formed flat. In particular, the casting surface 26A is preferably polished, and the surface roughness of the casting surface 26A is preferably 0.05 μm or less.

  As shown in FIGS. 3 and 4, the band moving unit 27 includes a band moving unit 28 that moves the casting band 26 wound around the horizontal drums 24 and 25, and a band that regulates the moving direction of the casting band 26. A moving direction control unit 29 and a control unit 30 are provided.

  The band moving unit 28 includes a drive motor 28M, an axis shift unit 28AS, and a load cell 28LC.

  The drive motor 28M is connected to the drive shaft 24A. The controller 30 controls the driving motor 28M to rotate the drum body 24B at a predetermined speed. The casting band 26 circulates and moves in a predetermined direction as the drum body 24B rotates, and the drum body 25B rotates according to the movement of the casting band 26. Hereinafter, the moving direction of the casting band 26 is referred to as the X direction, the width direction of the casting band 26 is referred to as the Y direction, and the vertical direction is referred to as the Z direction.

The moving speed V _26A of the casting surface 26A of the casting band 26 is preferably 150 m / min or less. If the moving speed _V26A exceeds 150 m / min, it becomes difficult to stably form the beads. The lower limit value of the moving speed V _26A may be determined in consideration of the target film productivity. The lower limit value of the moving speed V _26A is, for example, 10 m / min.

  The drive shaft 24A includes a tension application position where a predetermined moving tension is applied to the casting band 26 stretched over the drum bodies 24B, 25B, and a slackening loosening of the casting band 26 stretched over the drum bodies 24B, 25B. It is movable between positions. The shaft shift unit 28AS can shift the drive shaft 24A between the tension application position and the slack position under the control of the control unit 30. The shaft shift unit 28AS preferably shifts the drive shaft 24A while maintaining a state parallel to the rotation shaft 25A.

  The load cell 28LC is attached to the drive shaft 24A. The load cell 28LC detects an external force received by the drive shaft 24A. The control unit 30 reads an external force received by the drive shaft 24A from the load cell 28LC. Next, the control unit 30 moves the shaft shift unit 27AS so that the moving tension applied to the casting band 26 becomes a predetermined value based on the read external force and the value of the cross-sectional area of the built-in casting band 26. Control. In this way, a uniform moving tension in the Y direction can be applied to the casting band 26.

(Band movement direction controller)
The band movement direction control unit 29 includes a drum rocking mechanism 35 that rocks the horizontal drum 25 in accordance with the direction in which the casting band 26 deviates from the moving path 26R, and bands that guide both Y-direction end faces of the casting band 26. And a guide mechanism 36.

(Drum swing mechanism)
The drum rocking mechanism 35 includes a disengagement detection unit 35K that detects that the casting band 26 has disengaged from the movement path 26R, and a bearing shift unit 35S that can move the pair of bearings 25AS independently in the X direction. Prepare.

  The disconnection detector 35K is provided in the drying chamber 23B. The detachment detection unit 35K includes a detachment detection unit 35KP provided at one end of the casting band 26 and a detachment detection unit 35KQ provided at the other end of the casting band 26.

  As shown in FIG. 5, the one-end-off detector 35KP includes a light source, a light emitting unit 40PA that emits inspection light from the light source to the outside, and a light sensor that can receive the inspection light, and the light sensor emits light. A light receiving unit 40PB that determines whether or not inspection light from the unit 40PA is detected. When the light receiving unit 40PB detects the inspection light, the light receiving unit 40PB outputs a detection signal. The light emitting unit 40PA and the light receiving unit 40PB are provided so that the optical path 40PX of the inspection light from the light emitting unit 40PA to the light receiving unit 40PB passes through one end in the Y direction of the moving path 26R of the casting band 26 set in advance.

  The other end disconnection detection unit 35KQ, like the one end disconnection detection unit 35KP, includes a light source, a light emitting unit 40QA that emits inspection light from the light source to the outside, and an optical sensor that can receive inspection light. And a light receiving unit 40QB that determines whether or not the sensor has detected inspection light from the light emitting unit 40QA. When the light receiving unit 40QB detects the inspection light, the light receiving unit 40QB outputs a detection signal. The light emitting unit 40QA and the light receiving unit 40QB are provided so that the optical path 40QX of the inspection light from the light emitting unit 40QA to the light receiving unit 40QB passes through the other end in the Y direction of the moving path 26R of the casting band 26 set in advance. .

  The moving path 26R is a reference path of the casting band 26 that is preset in the Y direction and wound around the horizontal drums 24 and 25, and is formed in an annular shape. The width of the movement path 26 </ b> R is obtained by adding a predetermined play width to the width of the casting band 26.

  3 and 4, the bearing shift unit 35S includes one end side bearing shift unit 35SP for moving the one end side bearing 25AS and the other end side bearing shift unit 35SQ for moving the other end side bearing 25AS. . Under the control of the control unit 30, the one end side bearing shift unit 35SP and the other end side bearing shift unit 35SQ each independently move the bearing 25AS in a predetermined direction.

  The control unit 30 performs a removal direction determination process. In the removal direction determination process, first, the control unit 30 determines whether or not a detection signal is output from the light receiving units 40PB and 40QB (see FIG. 5). And when it determines with the detection signal having been output from both light-receiving part 40PB * 40QB (refer FIG. 5), the control part 30 determines with the casting band 26 being in the movement path 26R. On the other hand, when it is determined that the detection signal is output from the light receiving unit 40QB (see FIG. 5) and the detection signal is not output from the light receiving unit 40PB (see FIG. 5), the control unit 30 It is determined that the extension band 26 has detached from the moving path 26R to one end side. When the detection signal is output from the light receiving unit 40PB (see FIG. 5) and it is determined that the detection signal is not output from the light receiving unit 40QB (see FIG. 5), the control unit 30 performs the casting. It is determined that the band 26 has detached from the moving path 26R to the other end side.

  Further, the control unit 30 performs a driven drum transition process for adjusting the posture of the horizontal drum 25 based on the result of the removal direction determination process. In the driven drum transition process, the control unit 30 controls the bearing shift unit 35S based on the result of the removal direction determination process. For example, when it is determined that the casting band 26 is in the movement path 26R, the control unit 30 includes the one end side bearing shift unit 35SP and the other end so that the rotation shaft 25A is parallel to the drive shaft 24A. The side bearing shift unit 35SQ is controlled. A position parallel to the drive shaft 24A is set as a reference position (see FIG. 6). On the other hand, when it is determined that the casting band 26 has deviated from the moving path 26R to the one end side, the one end side bearing is arranged so that one end side of the rotating shaft 25A is further away from the driving shaft 24A than the other end side of the rotating shaft 25A. The shift unit 35SP and the other end side bearing shift unit 35SQ are controlled (see FIG. 7). Conversely, when it is determined that the casting band 26 has moved away from the moving path 26R to the other end side, the other end side of the rotating shaft 25A is moved to the drive shaft 24A farther than the one end side of the rotating shaft 25A. The side bearing shift unit 35SP and the other end side bearing shift unit 35SQ are controlled (see FIG. 8).

(Band guide mechanism)
As shown in FIGS. 9 and 10, the band guide mechanism 36 is disposed on both outer sides in the Y direction of the moving path 26 </ b> R. The band guide mechanism 36 includes one end side guide rollers 36PA to 36PB which are one end side guide tools disposed on one end side in the Y direction of the lower portion of the moving path 26R, and the other end side in the Y direction of the lower portion of the moving path 26R. The other end side guide rollers 36QA to 36QC, which are the other end side guide tools, are provided. Here, the lower part of the movement path 26R is a casting in which the casting band 26 wound around the drum body 25B moves from the position P25 (see FIG. 2) away from the drum body 25B toward the drum body 24B. This refers to the period up to the position P24 (see FIG. 2) where the band 26 contacts the drum body 24B. The one end side guide rollers 36PA and 36PB are sequentially arranged from the upstream side in the X direction toward the downstream side. Similarly, the other end side guide rollers 36QA, 36QB, 36QC are sequentially arranged from the upstream side in the X direction toward the downstream side.

  The guide rollers 36PA to 36PB and 36QA to 36QC are preferably arranged alternately in the X direction. Thereby, the casting band 26 can be guided so as to be accommodated in the moving path 26 </ b> R while minimizing the force applied to the casting band 26.

  As shown in FIGS. 10 and 11, the other end side guide roller 36QA pivotally supports the guide roller main body 51 and the guide roller main body 51 that guides the band end surface 26E in the Y direction of the casting band 26 with the peripheral surface 51S. And a guide roller shaft 52. The guide roller shaft 52 extends in the Z direction. The guide roller body 51 or the peripheral surface portion of the guide roller body 51 is preferably formed of a material such as Teflon (registered trademark). A support groove 51D for guiding the band end surface 26E in the Y direction of the casting band 26 is preferably formed on the peripheral surface 51S of the guide roller body 51. The support groove 51D extends in the circumferential direction and is formed in an annular shape. The support groove 51D includes a bottom surface 51DD that guides the band end surface 26E in the Y direction of the casting band 26, and a side surface 51DS.

  Further, the other end side guide roller 36QA may include a swing shaft 55 disposed in parallel to the guide roller shaft 52, and a connecting arm 56 that connects the guide roller shaft 52 and the swing shaft 55. One end of the connecting arm 56 is fixed to the guide roller shaft 52, and the other end is pivotally supported by the swing shaft 55. The connecting arm 56 allows the guide roller main body 51 to swing between a proximity position P1 close to the end 26RE in the Y direction of the moving path 26R and retreat positions P2 to P3 retracted from the proximity position P1 ( (See FIG. 12). The retracted position P2 is upstream in the X direction with respect to the proximity position P1, and the retracted position P3 is downstream in the X direction with respect to the proximity position P1. The rocking shaft 55 and the connecting arm 56 can guide the casting band 26 so as to be within the moving path 26 </ b> R while minimizing the force applied to the casting band 26. An urging member for urging the guide roller main body 51 may be provided so as to be in the proximity position P1.

  Further, the other end side guide roller 36QA includes a shaft shift portion 61 (see FIGS. 9 and 10) that shifts the swing shaft 55 in the Z direction, and a spring 62 that biases the guide roller body 51 toward the center in the Y direction. (See FIG. 11). The control unit 30 controls the shaft shift unit 61 so that the guide roller main body 51 can support the band end surface 26E in the Y direction of the casting band 26 on the circumferential surface 51S (see FIG. 4). It is preferable that the control unit 30 controls the shaft shift unit 61 so that the casting band 26 does not contact the side surface 51DS. For example, one end of the spring 62 is fixed to the swing shaft 55, and the other end is fixed to the inner wall surface 23 </ b> S of the casing 23. The spring 62 can guide the casting band 26 so as to be within the moving path 26 </ b> R while minimizing the force applied to the casting band 26.

  Since the one end side guide rollers 36PA to PB and the other end side guide rollers 36QB to 36QC have the same structure as the other end side guide roller 36QA, detailed description thereof is omitted.

The distance CL (see FIG. 11) between the bottom surface 51DD of the support groove 51D of the guide roller body 51 and the Y-direction end 26RE of the moving path 26R at the proximity position P1 is such that the guide roller body 51 is arranged on one end side. Regardless of whether it is arranged on the other end side, it is preferable to gradually decrease from the upstream side in the X direction toward the downstream side. The interval CL (see FIG. 11) is, for example, 0 mm or more and 20 mm or less. For example, the interval CL _QA for the other end side guide roller 36QA shown in FIG. 9, the interval CL _{PA for} the one end side guide roller 36PA, the interval CL _QB for the other end side guide roller 36QB, and the interval CL for the one end side guide roller 36PB _{It is} preferable that the interval CL _QC for _PB and the other end side guide roller 36QC satisfy the relational expression (1).
_{CL QA> CL PA> CL QB} > CL PB> CL QC ··· relationship (1)

(Partition unit)
Returning to FIG. 2, the partition unit includes first to third seal members 71 to 73. The first to third seal members 71 to 73 are sequentially arranged in the casing 23 from the upstream side in the X direction toward the downstream side. The first to third seal members 71 to 73 are provided so as to protrude from the inner wall surface of the casing 23, and the projecting ends are close to the casting surface 26 </ b> A of the casting band 26. The area surrounded by the first to third seal members 71 to 73 in the casing 23, that is, the inner wall surface of the casing 23 and the casting surface 26A, is the casting chamber 23A from the upstream side in the X direction toward the downstream side. And partitioned into a drying chamber 23B and a stripping chamber 23C. And the airtightness of 23 A of casting chambers is maintained by the 1st-2nd seal members 71-72. Moreover, the airtightness of the drying chamber 23B is maintained by the second to third seal members 72 to 73. The distance between the first to third seal members 71 to 73 and the casting surface 26A is, for example, not less than 1.5 mm and not more than 2.0 mm.

(Casting unit)
A casting unit for forming a casting film 76 from the dope 12 (see FIG. 1) is disposed in the casting chamber 23A. The casting unit includes a casting die 77 and a decompressor 78. The casting die 77 has a dope outlet 77A that flows out of the dope 12 (see FIG. 1). The casting die 77 is disposed above the horizontal drum 24 so that the portion of the casting band 26 wound around the drum body 24B is close to the dope outlet 77A.

  The casting die 77 flows out the dope 12 (see FIG. 1) from the dope outlet 77A toward the casting band 26. The dope 12 (see FIG. 1) flowing out from the dope outlet 77A and reaching the casting surface 26A forms a bead. The dope 12 that has reached the casting surface 26A is caused to flow in the X direction, and as a result, a belt-like casting film 76 is formed.

  The decompressor 78 is for decompressing the upstream side of the bead in the X direction, and includes a decompression chamber 78A disposed on the upstream side in the X direction from the dope outlet 77A of the casting die 77, and the decompression chamber 78A. A decompression fan 78B for sucking the gas, and a suction pipe 78C connecting the decompression fan 78B and the decompression chamber 78A.

(Membrane drying unit)
The drying chamber 23B is provided with a film drying unit for drying the cast film. The membrane drying unit includes a first dryer 81 to a second dryer 82 that supply predetermined drying air to the casting membrane 76, and a drying controller (not shown). The first dryer 81 to the second dryer 82 are sequentially provided from the upstream side in the X direction toward the downstream side in the drying chamber 23B. The first dryer 81 is disposed above the casting band 26 that is stretched over the horizontal drums 24 and 25. The second dryer 82 is disposed below the casting band 26 that is stretched over the horizontal drums 24 and 25.

  The first dryer 81 includes a first air supply duct 81A and a first exhaust duct 81B. The first air supply duct 81A and the first exhaust duct 81B are sequentially provided from the upstream side in the X direction toward the downstream side. The first air supply duct 81A and the first exhaust duct 81B are arranged separately from the casting band 26, respectively. The first air supply duct 81A is provided with a first air supply port through which the first drying air 81DA is sent out. The first air supply opening that opens toward the downstream side in the X direction extends from one end of the casting film 76 to the other end. The first exhaust duct 81B is provided with a first exhaust port for exhausting the first dry air 81DA. The first exhaust opening that opens toward the upstream side in the X direction extends from one end of the casting film 76 to the other end.

  The second dryer 82 includes a second exhaust duct 82A and a second air supply duct 82B. The second exhaust duct 82A and the second air supply duct 82B are sequentially provided from the upstream side in the X direction toward the downstream side. The second exhaust duct 82A and the second air supply duct 82B are disposed separately from the casting band 26, respectively. The second exhaust duct 82A is provided with a second exhaust port for exhausting the second dry air 82DA. The second exhaust opening that opens toward the downstream side in the X direction extends from one end of the casting film 76 to the other end. The second air supply duct 82B is provided with a second air supply port through which the second dry air 82DA is sent out. The second air supply opening that opens toward the upstream side in the X direction extends from one end of the casting film 76 to the other end.

  The drying controller adjusts the temperature and the wind speed of the first drying air 81DA and the second drying air 82DA independently, and adjusts the temperature of the first drying air 81DA and the second drying air 82DA. A two-temperature controller (not shown), first and second blower fans (not shown) for adjusting the air volume of the first drying air 81DA and the second drying air 82DA, and a controller (not shown) are provided. The first to second temperature controllers and the first to second blower fans are provided in each duct of the first dryer 81 to the second dryer 82. The controller controls the first and second temperature controllers and the first and second blower fans, and independently adjusts the temperature and wind speed of the first dry air 81DA and the second dry air 82DA.

(Peeling member)
A peeling roller 86 as a peeling member is disposed in the peeling chamber 23C. The peeling roller 86 peels off the casting film 76 that has been peeled off from the casting band 26 to form the wet film 13, and sends the wet film 13 from the outlet 23 </ b> CO provided in the peeling chamber 23 </ b> C.

  The casting device 15 may be provided with a condensing device for condensing the solvent contained in the atmosphere in the casing 23 and a collecting device for collecting the condensed solvent. Thereby, the density | concentration of the solvent contained in the atmosphere in the casing 23 can be kept in a fixed range.

  Returning to FIG. 1, a plurality of support rollers 87 that support the wet film 13 are arranged in a transition portion between the casting device 15 and the clip tenter 17. The support roller 87 is rotated around an axis by a motor (not shown). The support roller 87 supports the wet film 13 fed from the casting device 15 and guides it to the clip tenter 17. Although FIG. 1 shows a case where two support rollers 87 are arranged in the transition portion, the present invention is not limited to this, and one or three or more support rollers 87 may be arranged in the transition portion. . Further, the support roller 87 may be a free roller.

  The clip tenter 17 has a number of clips that grip both side edges of the wet film 13 in the width direction, and these clips move on the stretching track. Dry air is sent to the wet film 13 held by the clip, and the wet film 13 is subjected to a drying process as well as a stretching process in the width direction.

  An ear clip device 88 is provided between the clip tenter 17 and the drying device 18. At both ends in the width direction of the film 16 fed to the ear-cutting device 88, grip marks formed by clips are formed. The ear clip device 88 cuts off both end portions having the grip marks. This separated part is sequentially sent to a cut blower (not shown) and a crusher (not shown) by air blowing, cut into small pieces, and reused as a raw material such as a dope.

  The drying device 18 includes a casing having a conveyance path for the film 16, a plurality of rollers 18 </ b> A that form the conveyance path for the film 16, and an air conditioner (not shown) that adjusts the temperature and humidity of the atmosphere in the casing. The film 16 introduced into the casing is conveyed while being wound around the plurality of rollers 18A. By adjusting the temperature and humidity of the atmosphere, the remaining solvent evaporates from the film 16 conveyed in the casing. Further, an adsorption recovery device for recovering the solvent evaporated from the film 16 by adsorption is connected to the drying device 18.

  Between the drying device 18 and the winding device 19, a cooling chamber 89, a static elimination bar (not shown), a knurling roller 90, and an ear clip device (not shown) are provided in this order from the upstream side. The cooling chamber 89 cools the film 16 until the temperature of the film 16 reaches substantially room temperature. The neutralization bar is discharged from the cooling chamber 89 and performs a neutralization process for removing electricity from the charged film 16. The knurling application roller 90 applies a winding knurling to both ends of the film 16 in the width direction. The edge-cutting device cuts both ends in the width direction of the film 16 so that knurling remains at both ends in the width direction of the film 16 after cutting.

  The winding device 19 includes a press roller 19A and a winding core 19B. The film 16 sent to the winding device 19 is wound around the winding core 19B while being pressed by the press roller 19A, and becomes a roll.

  Next, the operation of the present invention will be described. As shown in FIGS. 3 and 4, a predetermined moving tension is applied to the casting band 26 by the shaft shift unit 28 AS, the load cell 28 LC, and the control unit 30. Then, the horizontal drum 24 is rotated by the driving motor 28M and the control unit 30. As a result, the casting band 26 moves on the moving path 26 </ b> R, i.e., sequentially moves through the chambers 23 </ b> A to 23 </ b> C on the moving path 26 </ b> R in the casing 23.

(Film formation process)
As shown in FIG. 2, in the casting chamber 23A, a casting process for forming a casting film 76 made of the dope 12 on the casting band 26 is performed. The casting die 77 continuously flows out the dope 12 from the dope outlet 40A. The dope 12 that has flowed out forms a bead from the casting die 77 to the casting band 26, and is spread on the casting band 26. Thus, a casting film 76 made of the dope 12 is formed on the casting band 26.

(Film drying process)
In the drying chamber 23 </ b> B, a film drying process is performed in which a predetermined drying air is applied to the casting film 76 to evaporate the solvent from the casting film 76. The film drying process is performed until the cast film 76 is in a state where it can be independently carried. In the film drying process, a first film drying process in which the first drying air 81DA is applied to the casting film 76 and a second film drying process in which the second drying air 82DA is applied to the casting film 76 are sequentially performed.

  The first film drying step is preferably performed on the cast film 76 having a solvent content of 250% by mass or more and 400% by mass or less, and the solvent content is 300% by mass or more and 350% by mass or less. More preferably, it is performed on 76. The temperature of the first drying air 81DA is preferably 30 ° C. or higher and 80 ° C. or lower. Moreover, it is preferable that the wind speed of 1st drying wind 81DA is 5 m / sec or more and 25 m / sec or less.

  In the second film drying step, the temperature of the second drying air 53DA is preferably 30 ° C. or higher and 80 ° C. or lower. Moreover, it is preferable that the wind speed of 2nd dry wind 53DA is 5 m / sec or more and 25 m / sec or less.

  Here, the content of the solvent indicates the amount of the solvent contained in the cast film and each film on a dry basis, and a sample is taken from the target film, and the weight of this sample is x, When the weight after drying is y, {(xy) / y} × 100.

(Stripping process)
In the stripping chamber 23 </ b> C, a stripping process is performed for stripping the casting film 76 that is in a strippable state from the casting band 26. The stripping roller 86 strips the cast film 76 that has been peeled off from the casting band 26 to form the wet film 13, and sends the wet film 13 from the outlet 23 </ b> CO provided in the stripping chamber 23 </ b> C. The stripping step is preferably performed on the cast film 76 having a solvent content of 20% by mass to 80% by mass.

  Then, after the stripping process, the film forming process is performed again on the casting band 26. Thus, in the casting apparatus 15, the film forming process, the film drying process, and the stripping process are repeatedly performed. With the casting apparatus 15, the wet film 13 can be continuously produced from the dope 12.

Here, when the control unit 30 detects that the casting band 26 is detached from the moving path 26R, the control unit 30 controls the bearing shift unit 35S based on the result of the removal direction determination process. (See FIGS. 6 to 8). The casting band 26 can be returned to the moving path 26R by the driven drum transition process. However, when the moving speed of the casting band 26 is high (for example, 50 m / min or more), when a large fluctuation (for example, 2 m / min ² or more) occurs in the moving speed of the casting band 26, When the fluctuation amount of the temperature of the casting band 26 is large (for example, 30 ° C. or more) during the repeated drying process and stripping process, the casting band 26 is returned to the moving path 26R only by the removal direction determination process. In addition to this, the casting band 26 is more disengaged from the moving path 26R.

  In the casting apparatus 15, the band guide mechanism 36 can maintain the casting band 26 within a range in which a certain amount of play is added to the width of the moving path 26R. Therefore, the casting band 26 is moved from the moving path 26R. It is possible to avoid a large deviation. Then, by performing the driven drum transition process in such a state, it is possible to avoid that the casting band 26 is detached from the moving path 26R. In this manner, the casting band 26 can be accommodated in the moving path 26R at the casting position CP (see FIG. 8) where the dope 12 (see FIG. 1) flowing out from the casting die 77 lands on the casting surface 26A. it can.

  The drum swing mechanism 35 may be omitted. When the drum rocking mechanism 35 is omitted, the distance CL between the bottom surface 51DD and the Y direction end portion 26RE of the moving path 26R may be 0 (see FIG. 13).

  When the drum swing mechanism 35 (see FIG. 4) is used, the guide roller closest to the horizontal drum 25 needs to be separated from the horizontal drum 25 to the extent that it does not come into contact with the swinging horizontal drum 25. Is omitted, the guide roller closest to the horizontal drum 25 can be brought closer to the horizontal drum 25.

Further, a stepped drum 124 shown in FIGS. 14 and 15 may be used instead of the horizontal drum 24. The stepped drum 124 is horizontal in the casing 23 and is arranged in parallel with the horizontal drum 25, and includes a drive shaft 124A and a stainless steel drum main body 124B attached to the drive shaft 124A. The drum main body 124B includes a small-diameter drum portion 124BC at the center in the Y direction, and includes large-diameter drum portions 124BE at both ends in the Y direction. The length of the small-diameter drum portion 124BC in the Y direction is equal to the width of the moving path 26R. The moving path 26R is set on the circumferential surface of the small diameter drum portion 124BC. The depth D _124M of the support groove 124M of the casting band 26 formed by the large diameter drum portion 124BE and the small diameter drum portion 124BC, that is, the difference between the radius of the large diameter drum portion 124BE and the radius of the small diameter drum portion 124BC is the small diameter drum. The casting band 26 wound around the peripheral surface of the portion 124BC may be of a size that does not ride on the large-diameter drum portion 124BE. For example, the thickness D26 of the casting band ₂₆ is 0.5 times or more and 5 times or less. I just need it. The stepped drum 124 can prevent the casting band 26 from being detached from the moving path 26R.

  When the stepped drum 124 is used, the drum swing mechanism 35 and the band guide mechanism 36 may be omitted.

  The film 16 obtained by the present invention can be used particularly for a retardation film and a polarizing plate protective film.

  The width of the film 16 is preferably 600 mm or more, and more preferably 1400 mm or more and 2500 mm or less. The present invention is also effective when the width of the film 16 is larger than 2500 mm. The film 16 preferably has a thickness of 20 μm or more and 80 μm or less.

  The in-plane retardation Re of the film 16 is preferably 20 nm or more and 300 nm or less, and the thickness direction retardation Rth of the film 16 is preferably −100 nm or more and 300 nm or less.

The method for measuring the in-plane retardation Re is as follows. In-plane retardation Re is a letter obtained by conditioning a sample film at a temperature of 25 ° C. and a humidity of 60% RH for 2 hours, and measuring it from the vertical direction at 632.8 nm with an automatic birefringence meter (KOBRA21DH Oji Scientific Co., Ltd.). The foundation value was used. Re is expressed by the following equation.
Re = | n1-n2 | × d
n1 is the refractive index of the slow axis, n2 is the refractive index of the fast axis 2, and d is the thickness (film thickness) of the film.

The measuring method of the thickness direction retardation Rth is as follows. The sample film was conditioned at a temperature of 25 ° C. and a humidity of 60% RH for 2 hours, and measured in the same manner while tilting the film surface with an ellipsometer (M150 manufactured by JASCO Corporation) measuring 632.8 nm from the vertical direction. It calculated according to the following formula from the extrapolated value of the retardation value.
Rth = {(n1 + n2) / 2−n3} × d
n3 represents the refractive index in the thickness direction.

(polymer)
In the said embodiment, the polymer used as the raw material of a polymer film is not specifically limited, For example, there exist a cellulose acylate, cyclic polyolefin, etc.

(Cellulose acylate)
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 ratio in which the hydroxyl group of cellulose is esterified with carboxylic acid, that is, the substitution degree of the acyl group satisfies all of the following formulas (I) to (III) is preferable. In the following formulas (I) to (III), A and B represent the substitution degree of the acyl group, A is the substitution degree of the acetyl group, and B is the substitution degree of the acyl group having 3 to 22 carbon atoms. It is. In addition, it is preferable that 90 weight% or more of a triacetyl cellulose (TAC) is 0.1 mm-4 mm particle | grains.
(I) 2.0 ≦ A + B ≦ 3.0
(II) 1.0 ≦ A ≦ 3.0
(III) 0 ≦ B ≦ 2.0

  The total substitution degree A + B of the acyl group is more preferably 2.20 or more and 2.90 or less, and particularly preferably 2.40 or more and 2.88 or less. Further, the substitution degree B of the acyl group having 3 to 22 carbon atoms is more preferably 0.30 or more, and particularly preferably 0.5 or more.

  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 polymer, peelability from cast film support, mechanical strength of film and optical properties of film. It is preferable to mix several kinds. The content of the alcohol is preferably 2% by weight to 25% by weight and more preferably 5% by weight to 20% by weight with respect to the whole solvent. Specific examples of the alcohol include methanol, ethanol, n-propanol, isopropanol, n-butanol and the like, but methanol, ethanol, n-butanol or a mixture thereof is preferably used.

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

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

DESCRIPTION OF SYMBOLS 10 Solution film forming equipment 15 Casting apparatus 26 Casting band 27 Band moving unit 28 Band moving part 29 Band moving direction control part 30 Control part 35 Drum rocking | fluctuation mechanism 35K Detachment detection part 35S Bearing shift part 36 Band guide mechanisms 36PA-PB , 36QA ~ QC Guide roller

Claims (6)

A film made of a dope containing a polymer and a solvent which is wound around a driving drum and a driven drum arranged in parallel with each other in a horizontal direction and moves on an annular path preset in the width direction by the rotation of the driving drum. an annular band that supports the,
A casting die that flows out the dope toward a portion of the annular band wound around the drive drum,
A membrane drying device that applies drying air to the membrane to evaporate the solvent from the membrane;
A stripping device for stripping the membrane from the annular band;
An annular band guide mechanism that is disposed on both outer sides in the width direction in the lower part of the annular path, and that guides the end surface in the width direction of the annular band ;
The band guide mechanism is
A roller body capable of guiding the end surface in the width direction of the annular band on the peripheral surface, and a roller shaft that pivotally supports the roller body, and a central portion in the width direction of the annular path from the driven drum toward the drive drum A plurality of guide rollers arranged so as to approach
A support groove capable of guiding the end surface in the width direction of the annular band is formed on the circumferential surface of the roller body.
The plurality of guide rollers are alternately arranged on one end side and the other end side in the width direction of the annular path in the moving direction of the annular band,
The casting equipment, wherein a distance between the bottom surface of the support groove of each guide roller and the annular path is 0 mm or more and 20 mm or less. The guide roller is provided movably between a proximity position close to the annular path and a retracted position away from the proximity position ;
The casting apparatus according to claim 1 , wherein the distance is a distance between the bottom surface and the annular path when the guide roller is in the close position . The casting equipment according to claim 1 or 2, wherein the guide roller is urged toward the center in the width direction of the annular path. A driven drum transition section that shifts the driven drum between a first posture in which one end is closer to the driving drum than the other end and a second posture in which the other end is closer to the driving drum than the one end;
A detachment direction detection unit that detects a direction in which the annular band is detached from the annular path;
The off-direction detection unit according to any one of the three claims 1, characterized in that a driven drum posture control unit for controlling said driven drum transition portion, based on the deviated direction detected Casting equipment . The drive drum includes a drive drum body capable of supporting the back surface of the annular band on a circumferential surface, and a drum drive shaft that pivotally supports the drive drum body,
The drive drum body has a small-diameter drum portion provided at the center in the width direction and large-diameter drum portions provided at both ends in the width direction,
The casting facility according to any one of claims 1 to 4 , wherein the annular path is set on a circumferential surface of the small diameter roller portion. Of an annular band that is wound around a driving drum and a driven drum that are horizontally and parallel to each other, and moves on a predetermined annular path in the width direction by the rotation of the driving drum, the portion that is wound around the driving drum The film forming step of flowing out the dope containing a polymer and a solvent toward the annular band to form a film made of the dope,
A membrane drying step in which drying air is applied to the membrane on the annular band to evaporate the solvent from the membrane;
A stripping step of stripping the membrane that has undergone the membrane drying step from the annular band;
Annular band guide mechanism guides the widthwise end face of the annular band by, have a movement control step for controlling the moving direction of the circular band,
The band guide mechanism is
A roller body capable of guiding the end surface in the width direction of the annular band on the peripheral surface, and a roller shaft that pivotally supports the roller body, and a central portion in the width direction of the annular path from the driven drum toward the drive drum A plurality of guide rollers arranged so as to approach
A support groove capable of guiding the end surface in the width direction of the annular band is formed on the circumferential surface of the roller body.
The plurality of guide rollers are alternately arranged on one end side and the other end side in the width direction of the annular path in the moving direction of the annular band,
The solution casting method , wherein a distance between a bottom surface of the support groove of each guide roller and the annular path is 0 mm or more and 20 mm or less .

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