JP5384582B2 - Device and method for controlling band position of solution casting equipment and solution casting method - Google Patents

Description

The present invention relates to a band position control device and method for solution casting equipment and a solution casting method .

  As a typical method for producing a long optical film, there is a continuous solution casting method. As is well known, in the solution casting method, a solution (dope) in which a polymer is dissolved in a solvent is cast on a running casting support, and the dope is formed into a film by casting. This is a method for producing a film by peeling a cast film from a casting support and drying it.

  Casting supports include metal bands and drums. In the case of a drum, since the distance from casting to peeling is shorter than that of the band, it is disadvantageous when drying so that the casting film has a self-supporting property that can be peeled off from the support. For this reason, a band system that can support the cast film at a long distance is often used. By the way, the width of the film that can be manufactured is limited by the width of the band. To produce a wider film, a wider band is required. However, up to now, only a band with a width of up to about 2 m has been obtained due to problems in the manufacturing technology of the band.

JP-A-6-297486 Japanese Patent Laid-Open No. 2002-245452

  In Patent Document 1, meandering in a film manufacturing apparatus is controlled as follows. First, when the endless belt (band) is displaced to the right from the regular travel path, this displacement is detected by the first detection means. When the first detection means detects a positional shift, it outputs a right correction command signal and fixes the right bearing member by the right expansion / contraction means. In this state, the left bearing member is maintained in a free state, so that the rotation shaft of the turn pulley (turn drum) is inclined by the tension from the band that has been displaced. By this inclination, the band moves to the side where the tension is smaller, and the positional deviation of the band is corrected. Similarly, when the band is displaced to the left from the normal travel path, the second detector detects this and performs the same operation, thereby correcting the displacement.

  In Patent Document 2, first belt position detection means for detecting the position of the belt edge near the first drum holding the endless belt, and second belt position detection for detecting the position of the belt edge near the second drum. And a belt position adjusting mechanism is controlled according to the difference between the position detection information of each detecting means and the reference position. The belt position adjusting mechanism displaces one end of the second drum by a cylinder to incline the drum shaft, and suppresses meandering as in Patent Document 1.

  By the way, since there was no requirement for a wide width conventionally, the meandering amount of the band was allowed to be about 50 mm in the band width direction, for example, in the case of a band width of 2 m. Therefore, it is possible to cope with the meandering control method as described above. However, if the non-casting region is narrowed due to a demand for widening, for example, in the case of a bandwidth of 2 m, it becomes necessary to suppress the meandering amount to about 2 mm. For this reason, for example, as described in the prior art documents 1 and 2, the end of one shaft is displaced to incline the turn drum shaft, and the band is moved on the turn drum using the band tension to correct the positional deviation. However, there is a problem that the method cannot correct the positional deviation quickly and accurately, and cannot respond to the request for widening.

  Further, a decompression chamber having a negative pressure inside is provided on the upstream side in the band running direction of the casting die in order to stabilize the bead that is a dope flow from the casting die to the band. In this decompression chamber, in order to keep the negative pressure constant, it is necessary to keep the gap with the band constant. Therefore, when the amount of meandering of the band increases, the side edge of the band may be located in the decompression chamber. In this case, there is a problem that a gap corresponding to the thickness of the band is formed at the side edge of the decompression chamber, and a sudden fluctuation of the negative pressure occurs and the bead becomes unstable.

  Furthermore, in a solution casting apparatus, the use of a band for a long time may cause unevenness in thickness or surface characteristics on the film. As a result of intensive studies, it has been found that this unevenness in thickness and the like is caused by long-term use of the band, particularly due to stress caused by meandering on the drum of the band. That is, when the band meanders, the band slides and moves in the direction of the rotation axis of the drum, for example, on the circumferential surface of the drum. Due to the movement in the drum rotation axis direction on the drum peripheral surface, stress is applied to the band, and a stripe-like thickness unevenness (peak) that is long in the running direction occurs mainly on the back surface. It was transferred to the casting film on the band, and it was found that the film appeared as uneven thickness and surface characteristics. For this reason, in order to reduce stress on the band, it is necessary to effectively suppress the meandering of the band.

  However, as shown in Patent Documents 1 and 2, in the conventional meander control, the meander of the band at the casting position is changed by changing the inclination angle of the rotation shaft of the free rotating drum opposite to the driving drum. Even if accurate control is performed in order to suppress this, when the distance between the drums is as long as several tens of meters, for example, there is a problem that responsiveness decreases and accurate meandering control cannot be performed. In addition, it is necessary to shift the drum having many tons and perform meandering control, and it is difficult to move the bearing smoothly under the influence of friction. Moreover, there is a problem that the accuracy of meandering control is reduced due to mechanical loss due to the influence of friction or the like, or due to the influence of bending of the driving member that shifts the bearing.

An object of the present invention is to provide a band position control device and method for a solution casting apparatus and a solution casting method that can easily cope with the widening of the film and can perform meandering control with high accuracy.

In order to solve the above problems, the present invention provides a polymer on a band that runs between a first drum and a second drum and travels in a first direction from the first drum toward the second drum. There was casting a dope prepared by dissolving in a solvent from a casting die to form a casting film on the band, solution casting apparatus of the band edge position control apparatus for the casting film to the film dried peeled from the band A first drum band edge position sensor for detecting an edge position in a second direction which is a width direction of the band by the first drum, and an inner peripheral surface of a lower band between the first drum and the second drum a steering roll in contact with, the center line of the steering roller is inclined with respect to the second direction of the reference line, the steering of the lower band according to the inclination of the steering roller A steering roller tilting mechanism for moving along said center line over Lumpur, based on the band edge positions of the first drum band edge position sensors, so as to suppress the variation of the band edge positions, of the inclination of the steering roller A band edge position controller for controlling the angle .

  The steering roll is disposed near the band entrance of the first drum, and the steering roll tilting mechanism includes a roll bearing that rotatably holds both ends of the steering roll, and the roll bearing that is connected to the inner periphery of the lower band. A vertical shift unit that individually shifts in a direction intersecting the surface, or the steering roll tilt mechanism is configured to cause a roll bearing that rotatably supports both ends of the steering roll to contact the band with the steering roll. It is preferable to have a lateral shift part that individually shifts the roll bearing in a direction parallel to the inner peripheral surface of the lower band. Furthermore, it is preferable that the steering roll tilt mechanism has a lateral shift portion that individually shifts the roll bearing in a direction parallel to the inner peripheral surface of the lower band.

  The band edge position controller obtains a moving speed of the band edge in the second direction based on a band edge position signal from the first drum band edge position sensor, and based on the band edge moving speed and the traveling speed of the band. It is preferable that the steering roll tilt mechanism is controlled to tilt the steering roll in a direction to reduce the moving speed of the band edge.

  A drum bearing that rotatably supports both shaft end portions of the second drum, a shift mechanism that shifts the drum bearing in the first direction, a tension sensor that detects the tension of the band, and a tension of the tension sensor It is preferable to have a tension controller that operates the shift mechanism based on the signal to make the tension constant. Further, it is preferable that the tension sensor is provided at an intermediate position between the first drum and the second drum, and detects the tension from the amount of suspension of the lower band. In addition, a drum bearing that rotatably supports both shaft ends of the second drum, a right shift mechanism and a left shift mechanism that individually shift the drum bearing in the first direction, and the first of the drum bearing. A second drum right position sensor and a second drum left position sensor for detecting a position in the direction, a second drum band edge position sensor for detecting a band edge position in the second direction by the second drum, and the drum bearing And a right-side tension sensor and a left-side tension sensor provided between the shift mechanisms and a band tension based on a tension signal from the tension sensor, and a band edge position variation in the second drum is suppressed. The bearing position correction signal is output to the right shift mechanism and the left shift mechanism. It is preferred to have a tension controller.

In the band edge position control method for a solution casting apparatus of the present invention, the first drum detects an edge position in a second direction which is the width direction of the band, and based on the detection signal of the band edge position, the first The center line of the steering roll contacting the inner peripheral surface of the lower band between the first drum and the second drum is inclined with respect to the reference line in the second direction, and the lower band is steered according to the inclination of the steering roll. It moves along the center line on the roll to suppress fluctuations in the band edge position . In the solution casting method of the present invention, solution casting is performed using the band edge position control method.

  According to the present invention, the steering roll is disposed so as to contact the inner peripheral surface of the lower band between the first drum and the second drum, and the tilt angle of the steering roll is changed based on the band edge position signal in the first drum. Therefore, the meandering of the band in the first drum can be quickly and accurately suppressed. Therefore, the position control of the band can be performed with high accuracy, and for example, it can be suppressed to a swing width of about 2 to 3 mm for a 2000 mm wide band. As a result, the amount of movement of the band in the drum axis direction is reduced, and the width of the non-casting region between the both side edges of the band and the both side edges of the casting film can be narrowed. It can be manufactured efficiently. Moreover, since the band meandering is suppressed by the steering roll, the band meandering can be suppressed quickly and accurately, and the band shift amount on the drum during the meandering control can be small. Therefore, the occurrence of a streak-like peak in the band due to the secular change caused by the meandering of the band can be suppressed. Thereby, the lifetime improvement of a band and the thickness nonuniformity of the film formed can be eliminated.

It is the schematic of solution casting apparatus. It is the block diagram which looked at the band edge position control apparatus from the plane. It is the block diagram similarly seen from the side. It is the same block diagram seen from the front. It is a front view for demonstrating operation | movement of a steering roll. It is a top view for demonstrating operation | movement of the steering roll of another embodiment. It is the same side view. It is a side view for demonstrating operation | movement of the steering roll of another embodiment.

  As shown in FIG. 1, the solution casting apparatus 10 includes a casting device 11, a first tenter 12, a roll drying device 13, a second tenter 14, a slitter 15, and a winding device 16 on the upstream side. Are connected in series.

  The casting apparatus 11 includes a band 23 wound around the drums 21 and 22, a casting die 24, a duct 25, a decompression chamber 26, a stripping roll 27, and a band edge position (BEP) control device ( (Hereinafter referred to as a BEP control device) 28. The band 23 is an endless metal casting support body formed in an annular shape, and is wound around the peripheral surfaces of the first drum 21 and the second drum 22. The band 23 positioned on the upper side of each of the drums 21 and 22 is referred to as an upper band 23A, and the band 23 positioned on the lower side is referred to as a lower band 23B. The first drum 21 is rotationally driven by a motor (see FIG. 2) 29, whereby the band 23 travels in the first direction indicated by the arrow A.

  A casting die 24 is disposed above the first drum 21. The casting die 24 continuously flows the dope 30 with respect to the traveling band 23. Thereby, the casting film 31 is formed on the band 23. The dope 30 is obtained by, for example, dissolving cellulose acylate in a solvent, manufactured by a dope manufacturing line (not shown), and supplied to the casting die 24.

  A decompression chamber 26 is provided upstream of the bead 34 from the casting die 24 in the traveling direction of the band 23. The decompression chamber 26 sucks the atmosphere in the upstream area of the bead 34 to decompress the area and reduce the vibration of the bead 34.

  In order to improve the manufacturing speed, the casting film 31 toward the peeling roll 27 is heated by the second drum 22 and the band 23. Further, at the casting position, the band 23 is cooled by the first drum 21 so that the temperature of the band 23 does not rise excessively. For this reason, each drum 21 and 22 has a temperature control device (not shown).

  A plurality of ducts 25 are provided side by side along the traveling path of the band 23. Each duct 25 is connected to a hot air controller (both not shown) having a blower, and blows dry air from the outlet. The hot air controller controls the temperature, humidity, and flow rate of the drying air independently. The temperature of the casting film 31 is adjusted by controlling the temperature and flow rate of the drying air and the temperature control of the drums 21 and 22 themselves, and the drying of the casting film 31 proceeds. Then, the casting film 31 is solidified to such an extent that it can be conveyed by the first tenter 12, and self-supporting property is imparted.

  A stripping roll 27 is provided on the upstream side in the traveling direction of the casting die 24 of the first drum 21. The peeling roll 27 supports the casting film 31 when the casting film 31 that has been dried in a state containing a solvent is peeled off from the band 23. The cast film 31 that has been peeled off, that is, the film 32 is guided to the first tenter 12.

  In the first tenter 12, the side edges of the film 32 are gripped by the clip 33, and the tension in the second direction (the film width direction) indicated by the arrow B is applied while the film 32 is being conveyed. Expand. In the first tenter 12, a preheating area, an extension area, and a relaxation area are formed in order from the upstream side. The relaxation area is provided as necessary.

  The first tenter 12 has a pair of rails and a chain (both not shown). The rails are arranged on both sides of the conveyance path of the film 32 so as to be separated at a predetermined interval. This rail interval is constant in the preheating area, gradually becomes wider in the extension area as it goes downstream, and constant in the relaxation area, or becomes gradually narrower as it goes downstream. Clips 33 are attached to the chain at regular intervals.

  The preheating area, the extension area, and the relaxation area are formed as spaces by sending dry air from the duct 35, and there is no clear boundary between these areas. From the slit of the duct 35, dry air adjusted to a predetermined temperature and humidity is sent toward the film 32.

  In the roll drying device 13, the film 32 is wound around a large number of rolls 36 and conveyed. The atmosphere inside the roll dryer 13 is adjusted by a temperature controller (not shown) such as temperature and humidity, and the solvent evaporates from the film 32 while the film 32 is being transported.

  The second tenter 14 has the same structure as the first tenter 12 and includes a clip 38 and a duct 39. The second tenter 14 stretches while holding the film 32 with a clip 38. By this stretching, a film 32 having desired optical properties is obtained. The obtained film 32 can be used, for example, as a retardation film for a liquid crystal display. Depending on the optical characteristics of the film 32, the second tenter 14 may not be used.

  The slitter 15 cuts out the side portion including the holding marks by the clips 33 and 38 of the first tenter 12 and the second tenter 14. The film 32 whose side portion has been cut off is wound into a roll by the winding device 16.

  As shown in FIGS. 2 and 3, the first drum 21 is rotatably supported by the bearing 17 at both ends of the drum rotation shaft 21 </ b> A. A drum rotation motor 29 is connected to one end. A TG (tacho generator) 18 is connected to the drum rotation motor 29, and the TG 18 detects the rotation speed of the first drum 21. The drum rotation motor 29 is connected to the system controller 20 via the driver 19. The TG 18 is also connected to the system controller 20. The system controller 20 controls the rotation of the drum rotation motor 29 so that the band 23 rotates at a constant speed. The system controller 20 changes the traveling speed and drying temperature of the band 23 according to the film forming conditions.

  As shown in FIGS. 3 and 4, the BEP control device 28 includes a first BEP control unit 28A and a second BEP control unit 28B. The first BEP control unit 28 </ b> A includes a steering roll 40, a first drum band edge position sensor (hereinafter referred to as a first drum BEP sensor) 41, a steering roll tilt mechanism 42, and a BEP controller 43. The BEP controller 43 holds the BEP constant by inclining the steering roll 40 in the second direction B (see FIG. 2) in the vertical plane based on the signal of the first drum BEP sensor 41.

  As shown in FIGS. 2 and 3, the second BEP control unit 28B includes shift mechanisms 45R and 45L, bearing position sensors 46R and 46L of the second drum 22, tension sensors 47R and 47L, and a second drum band edge position. A sensor (hereinafter referred to as a second drum BEP sensor) 48 and a tension controller 51 are included.

  As shown in FIG. 2, the tension controller 51 causes the center line CL2 of the second drum 22 to be inclined at an inclination angle θ2 with respect to the reference line BL2 in the horizontal plane. This eliminates the tension difference between the left and right sides of the band 23, suppresses the meandering of the band 23 in the second drum 22 due to the tension difference, and keeps the BEP in the second drum 22 constant. In the present embodiment, regarding members that need to be described by identifying left and right, “R” is added to the reference numerals of the members on the right side with reference to the direction in the first direction A. The members on the left side have “L” added to the reference numerals of the members.

  As shown in FIG. 4, the steering roll 40 rotates in contact with the inner peripheral surface 23C of the lower band 23B. The steering roll 40 is made of metal, and a surface-treated one such as rubber lining is used as necessary. The steering roll tilt mechanism 42 includes roll bearings 40BR and 40BL, and shift portions 55R and 55L that shift the roll bearings 40BR and 40BL. The roll bearings 40BR and 40BL are attached to both shaft ends of the steering roll 40 and rotatably support the steering roll 40. The shift portions 55R and 55L individually shift the roll bearings 40BR and 40BL in the vertical direction intersecting the inner peripheral surface 23C of the lower band 23B. Accordingly, the center line CL1 of the steering roll 40 is inclined at the inclination angle θ1 with respect to the reference line BL1 in the second direction. As the steering roll 40 is tilted, the lower band 23B where the inner peripheral surface 23C contacts the steering roll 40 moves on the steering roll 40 according to the tilt angle θ1 of the steering roll 40. By this movement, meandering of the lower band 23B on the first drum 21 is suppressed.

  Based on the BEP signal from the first drum BEP sensor 41, the BEP controller 43 operates the shift portions 55R and 55L to keep the BEP in the first drum BEP sensor 41 at a fixed position, thereby suppressing the occurrence of meandering. . For this reason, the band travel speed command signal and the BEP position command signal are input to the BEP controller 43 from the system controller 20.

  Based on the BEP signal from the first drum BEP sensor 41, the BEP controller 43 obtains the band edge moving speed Ve1 in the second direction B of the first drum 21. Based on the BE moving speed Ve1 and the speed command signal from the system controller 20, the target tilt angle of the steering roll 40 is obtained so that the BE moving speed Ve1 becomes “0” and the target BEP. Then, the shift amount of each shift unit 55R, 55L is calculated based on the obtained target inclination angle, and a shift control signal is sent to each shift unit 55R, 55L so as to be this shift amount. The shift units 55R and 55L adjust the shift amount based on the shift control signal. Thereby, based on the current BEP, a correction is made to bring it closer to the target BEP. It should be noted that the relationship among the BE moving speed Ve1, the band traveling speed VB, and the inclination angle θ1 is obtained in advance by experiments using an actual machine, and these relationships are stored as, for example, look-up table data.

  For example, as shown in FIG. 5, when it is detected that the lower band 23B starts to move to the right on the first drum 21 based on the signal of the first drum BEP sensor 41, a shift is made to correct this. The portions 55R and 55L lower the bearing 40BL, raise the bearing 40BR, and tilt the steering roll 40. As a result, the lower band 23B shifts to the left on the steering roll 40, and the BEP in the first drum 21 is quickly positioned to the target BEP. Therefore, the meandering of the band 23 on the first drum 21 can be suppressed quickly and efficiently. When the band edge moving speed Ve1 is high, the tilt angle θ1 of the steering roll 40 is increased, and when the band edge moving speed Ve1 is low, the tilt angle θ1 is decreased.

  As described above, the steering roll 40 can correct the position of the BEP near the first drum close to the casting position, and the band 22 is formed by inclining the rotating shaft 22A of the second drum 22 like the conventional casting apparatus. The meandering can be suppressed quickly and easily as compared with the one that suppresses meandering. That is, when the rotation axis 22A of the second drum 22 is inclined to suppress the meandering of the band 23 as in the prior art, the distance between the first and second drums 21 and 22 is as long as several tens of meters, for example. Therefore, the mechanical loss and the bending increase as the band 23 becomes longer. The load applied to the bearing of the second drum is, for example, about 5 tons. When this is moved by the shift mechanisms 45R and 45L, the friction becomes high and the movement is difficult. Moreover, due to the occurrence of mechanical loss, the amount of bending, etc., the reproducibility is lowered and the accuracy of meandering suppression is lowered, and meandering cannot be suppressed quickly. On the other hand, in this embodiment, since the meandering of the lower band 23B is corrected by the steering roll 40 in the vicinity of the first drum 21, the meandering can be corrected quickly. In addition, since the band 23 is tilted by the steering roll 40 on the band entrance side of the first drum 21 to correct the meandering, a small force is required with a small shift amount and compared with the tilting of the second drum rotating shaft 22A. The meandering can be corrected efficiently and quick and accurate meandering control becomes possible.

  As shown in FIG. 2, in the second BEP control unit 28B, both end portions of the drum rotation shaft 22A of the second drum 22 are rotatably supported by bearings 52R and 52L. These bearings 52R and 52L are provided so as to be movable in a first direction A toward the first drum 21 within a horizontal plane including the drum rotation shafts 21A and 22A. And it shifts to the 1st direction A individually by the shift mechanisms 45R and 45L, respectively. The shift mechanisms 45R and 45L and the shift portions 55R and 55L of the first BEP control unit 28A may be any mechanism that can move the bearings 52R, 52L, 40BR, and 40BL. A worm shaft or a screw rod driven by rotation is appropriately selected.

  A right bearing position sensor 46R is attached to the right bearing 52R, and a left bearing position sensor 46L is attached to the left bearing 52L. These bearing position sensors 46R and 46L detect the positions of the bearings 52R and 52L in the first direction A. Instead of detecting each bearing position by the bearing position sensors 46R and 46L, any sensor that can detect the displacement of the shaft end of the second drum 22 in the first direction may be used. Is not particularly limited.

  A right tension sensor 47R and a left tension sensor 47L are attached between the bearings 52R, 52L and the shift mechanisms 45R, 45L. The right tension sensor 47R and the left tension sensor 47L detect the tension of the band 23 and output it as a tension signal.

  A second drum band edge position sensor (hereinafter referred to as a second drum BEP sensor) 48 is provided on the second drum 22. The second drum BEP sensor 48 detects one side edge of the band 23, for example, the left edge position in the film width direction (second direction B), and a second band edge position signal (hereinafter, second BEP signal) in the second drum. Output).

  The tension controller 51 eliminates the difference between the left and right tensions based on the signals of the bearing position sensors 46R and 46L, the tension sensors 47R and 47L, and the second drum BEP sensor 48, and shifts the mechanism 45R, Actuate 45L. For this reason, the sum of the signals of the left and right tension sensors 47R and 47L is used as the band tension, and the band tension is held constant based on the tension command from the system controller 20. Further, the difference between the signals of the left and right tension sensors 47R and 47L is used as the left and right tension difference of the band, and the meandering is controlled based on the left and right tension difference.

  The shift mechanisms 45R and 45L incline the second drum 22 at an arbitrary inclination angle θ2 with respect to the reference line BL2 in the horizontal plane by the individual displacement of the bearings 52R and 52L in the first direction A. By this inclination, the uneven tension in the second direction B is eliminated, and the meandering of the band due to the uneven tension is suppressed. Further, the tension of the band 23 is adjusted to a constant value by the individual movement of the bearings 52R and 52L by the shift mechanisms 45R and 45L.

  The shift amount of each of the shift mechanisms 45R and 45L for suppressing the meandering of the band 23 based on the tension difference is obtained in advance by experiments or simulations in an actual machine corresponding to the band traveling speed, and this is expressed in a look-up table format. Stored in memory. Therefore, when the left and right tension signals and the band traveling speed are input, a shift amount for suppressing meandering based on the tension difference is calculated. And each shift mechanism 45R and 45L operate | move so that it may become this shift amount.

  Further, the tension controller 51 operates the shift mechanisms 45R and 45L based on the tension command signal from the system controller 20, and performs tension control so that the tension of the band 23 becomes a value instructed by the command signal. For example, when the band tension is small, the shift amount of each shift mechanism 45R, 45L is increased, and when the band tension is large, the shift amount of each shift mechanism 45R, 45L is decreased to keep the tension constant.

  As described above, in the second BEP control unit 28B, by controlling the tension by individually shifting the bearings 52R and 52L of the second drum 22, the tension fluctuation at the time when the temperature distribution of the band 23 is unstable is caused. Since it can be efficiently suppressed, the meandering of the band 23 can be efficiently suppressed at the start of casting, changing the casting speed, changing the drying temperature of the casting film, and the like.

  The meandering correction control of the band 23 caused by the tension fluctuation is particularly effective at the start of casting. At the beginning of casting, unlike the steady state, the temperature distribution in the width direction of the band 23 is not uniform, so the length in the first direction of the band 23 partially varies in the second direction due to the nonuniform temperature distribution. Cheap. This partial tension variation can be detected as meandering factor components by the left and right tension sensors 47R and 47L, and meandering caused by uneven temperature distribution in the band 23 can be effectively removed. Therefore, the meandering control at the start of casting can be performed with high accuracy. When the difference between the left and right tensions is within a predetermined range, and the influence of meandering due to the difference between the left and right tensions is reduced, the control for suppressing the meandering by inclining the second drum rotating shaft 22A is stopped, and the first BEP control unit The meandering may be suppressed only by 28A.

  In the first embodiment, the second BEP control unit 28B performs the meandering suppression based on the difference between the left and right tensions in addition to the tension control that keeps the band tension constant, and the first BEP control unit 28A removes the meandering that cannot be suppressed yet. However, instead of this, the second BEP control unit 28B may perform only control for keeping the band tension constant.

  Furthermore, instead of or in addition to detecting the band tension based on the sum of signals from the left and right tension sensors 47R and 47L in the second BEP control unit 28B, the lower band 23B at the intermediate position in the band traveling direction is used. The tension fluctuation may be suppressed based on a signal from the tension sensor 49 (see FIG. 3) based on the suspension amount.

In this case, an intermediate tension sensor 49 is provided near the left edge of the lower band 23B at an intermediate position between the first drum 21 and the second drum 22. The intermediate tension sensor 49 obtains the tension of the band 23 from the amount of suspension at the center position of the lower band 23B. Between the tension of the band 23 and the amount of suspension, there is a relationship in which the amount of suspension decreases as the tension increases. Equation (1) represents this relationship, where T is the band tension (N), Ld is the distance between the drum centers (m), Wb is the band width (mm), t is the band thickness (mm), γ is the density of the band (kg / dm ³ ), g is the acceleration of gravity (9.81 m / s ² ), and D is the amount of natural suspension (mm) at the intermediate position of the drum.
T = (Ld ² · Wb · t · γ · g) / (8 · D) (1)

  As described above, the amount of suspension at the center of the band may be a natural amount of suspension due to the weight of the band itself, or may be the amount of suspension in a state of being biased downward by a pressing roll or the like. Good. In this case, the calculation is performed by adding a correction amount corresponding to the pressing force to the value obtained by the above equation (1). By changing the displacement amount of each of the bearings 52R and 52L so that the tension signal from the intermediate portion tension sensor 49 becomes constant, the suspension amount can be always kept within a certain range, and the tension of the band 23 is also substantially reduced. Can be kept constant.

  Furthermore, in addition to the tension signals of the right and left tension sensors 47R and 47L, the tension signal of the intermediate tension sensor 49 is input to the tension controller 51, and the meandering control is performed in consideration of the tension signal of the intermediate tension sensor 49. May be. In this case, meandering control can be performed more accurately by changing and adding the weights of the tension signals of the right and left tension sensors 47R and 47L and the tension signal of the intermediate tension sensor 49.

  Further, instead of the method of controlling the tension of the band 23 by shifting the bearings 52R and 52L of the second drum rotating shaft 22A, the band tension may be controlled by the inclination of the steering roll 40 of the first BEP control unit 28A. . In this case, the band tension control can be performed together with the meander control by adding the shift amount for keeping the band tension constant to the shift amount corresponding to the meander suppression.

  In addition, in the said 1st Embodiment shown in FIGS. 2-4, although the new casting apparatus which consists of 1st BEP control unit 28A and 2nd BEP control unit 28B was demonstrated to the example, with respect to the existing casting apparatus, By newly installing the first BEP control unit 28A, it is possible to perform meandering control with high accuracy for existing equipment in the same manner. In this case, the existing meander control is stopped and only tension control is performed, and meander control is performed by the first BEP control unit 28A. Further, after the band position control on the second drum is also performed by the existing meandering control, the sudden meandering that still occurs may be suppressed by the first BEP control unit 28A.

  As shown in FIGS. 4 and 5, in the above embodiment, the steering roll 40 uses a full width roll that contacts the inner peripheral surface 23 </ b> C of the lower band 23 </ b> B, but the roll 40 contacts the full width of the band 23. In addition, a plurality of rollers that are spaced apart from and in contact with part of the band 23 in the width direction may be arranged in the axial direction. Further, it may be anything as long as it can slide with less resistance with respect to the band 23, and is not particularly limited to the roll form, and the steering guide can tilt the band 23 to suppress meandering. May be used.

  The steering roll tilting mechanism 42 displaces the steering roll 40 in a vertical plane perpendicular to the inner peripheral surface 23C of the lower band 23B, and tilts the lower band 23B in the second direction B, but the bearings 40BR, The shift direction of 40BL is not limited to the vertical plane, but may be any that can be displaced in any direction that intersects the inner peripheral surface 23C of the lower band 23B.

  6 and 7 show a steering roll tilt mechanism 62 according to another embodiment, which has a lateral shift portion 60 and a longitudinal shift portion 61. The vertical shift unit 61 brings the steering roll 40 into contact with the inner peripheral surface 23C of the lower band 23B and winds the lower band 23B around the steering roll 40 within a predetermined range. Next, the bearings 40BR and 40BL are individually displaced by the lateral shift unit 60, and the steering roll 40 is swung in a horizontal plane. Thus, the meandering can be efficiently suppressed by changing the vertical shift amount and the horizontal shift amount of the bearings 40BR and 40BL according to the meandering amount. 6 and 7, the steering roll 40 and the vertical shift unit 61 are collectively shifted by the horizontal shift unit 60. However, the connection order of the shift units 60 and 61 may be reversed. When the connection is established, the steering roll 40 and the horizontal shift unit 60 are collectively shifted by the vertical shift unit 61. Therefore, the vertical shift amount is arbitrarily set by the vertical shift unit 61 in a state where the steering roll 40 is swung in the horizontal plane by the horizontal shift unit 60. Also, the vertical shift unit 61 is omitted, and the steering roll 40 is held in a horizontal plane only by the horizontal shift unit 60 in a state where the steering roll 40 is kept in contact with the lower band 23B at a predetermined winding angle. It may be swung.

  FIG. 8 shows a steering roll in which bearings 40BR and 40BL are individually displaced to an arbitrary position in an arcuate locus 67 by a swing mechanism 66 having a swing arm 65 instead of using the lateral shift unit 60 and the vertical shift unit 61. An inclination mechanism 68 is shown. By this steering roll tilt mechanism 68, the steering roll 40 can be tilted in a desired direction, and the meandering of the band 23 is suppressed by the same action as described above.

  In the above embodiment, the casting die 24 is provided so that the casting position is on the region where the band 23 is wound around the first drum 21, but the position of the casting die 24 may be changed as appropriate. For example, the casting die 24 may be provided between the drums 21 and 22 so that the casting position is on the band 23 from the first drum 21 to the second drum 22. In this case, it is preferable to provide a support roll under the band 23 from the drum 21 to the drum 22 and dispose the casting die 24 so as to face the band 23 on the support roll. In this case, the first drum BEP sensor 41 may be provided near the casting position instead of being provided near the first drum 21.

  The width of the band 23 is not particularly limited, but those having a width Wb of 1500 mm or more and 2100 mm or less are preferably used, and those having a wide width are used in order to increase the width of the film 32 to be manufactured. The length of the band 23 is determined according to the casting speed and drying conditions.

  The dope cast on the band 23 may be a dope in which a polymer capable of solution film formation is dissolved in a solvent, but cellulose acylate is preferably used. The cellulose acylate may have only one type of acyl group or may have two or more types of acyl groups. When there are two or more acyl groups, one of them is preferably 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.

(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. Among these, cellulose diacetate (DAC) is preferably used as the cellulose acylate.

DESCRIPTION OF SYMBOLS 10 Solution casting equipment 11 Casting apparatus 21 1st drum 22 2nd drum 21A, 22A Drum rotation shaft 23 Band 30 Dope 31 Casting film 32 Film 40 Steering roll 40BR, 40BL Bearing 41 1st drum BEP (band edge position) Sensor 42, 62, 68 Steering roll tilt mechanism 43 BEP controller 45R, 45L Shift mechanism 46R, 46L Bearing position sensor 47R, 47L Tension sensor 48 Second drum BEP sensor 51 Tension controller 52R, 52L Bearing 55R, 55L Shift section 60 Side shift Section 61 Vertical shift section 66 Swing mechanism

Claims (17)

A dope, in which a polymer is dissolved in a solvent, is flowed from a casting die on a band that is stretched between a first drum and a second drum and travels in a first direction from the first drum toward the second drum. extending to form a casting film on the band, in-band edge position control apparatus for solution casting apparatus for the casting film to the film dried peeled from the band,
A first drum band edge position sensor for detecting an edge position in a second direction which is a width direction of the band by the first drum;
A steering roll in contact with the inner peripheral surface of the lower band between the first drum and the second drum;
A steering roll tilt mechanism that tilts the center line of the steering roll with respect to the reference line in the second direction and moves the lower band along the center line on the steering roll in accordance with the tilt of the steering roll. When,
And a band edge position controller for controlling an angle of inclination of the steering roll so as to suppress fluctuation of the band edge position based on a band edge position of the first drum band edge position sensor. Band edge position control device for membrane equipment. The steering roll is disposed near the band entrance of the first drum;
The steering roll tilt mechanism includes a roll bearing that rotatably holds both ends of the steering roll, and a shift unit that individually shifts the roll bearing in a direction intersecting the inner peripheral surface of the lower band. The band edge position control device for a solution casting apparatus according to claim 1.   The band edge of the solution casting apparatus according to claim 2, wherein the steering roll tilt mechanism includes a lateral shift portion that individually shifts the roll bearing in a direction parallel to the inner peripheral surface of the lower band. Position control device. The steering roll is disposed near the band entrance of the first drum;
The steering roll tilt mechanism includes a roll bearing that rotatably holds both ends of the steering roll, and the roll bearing that is parallel to the inner peripheral surface of the lower band while the steering roll is in contact with the band. 2. The band edge position control device for a solution casting apparatus according to claim 1, further comprising a lateral shift unit that shifts the direction individually. The band edge position controller obtains a moving speed of the band edge in the second direction based on a band edge position signal from the first drum band edge position sensor, and determines the moving speed of the band edge and the traveling speed of the band. 5. The solution casting apparatus according to claim 1, wherein the steering roll tilt mechanism is controlled to tilt the steering roll in a direction in which the moving speed of the band edge is reduced. Band edge position control device. A drum bearing that rotatably supports both shaft ends of the second drum;
A shift mechanism for shifting the drum bearing in the first direction;
A tension sensor for detecting the tension of the band;
6. The band edge position control of the solution film-forming facility according to claim 1, further comprising: a tension controller that operates the shift mechanism based on a tension signal of the tension sensor to make the tension constant. apparatus.   7. The band for a solution casting apparatus according to claim 6, wherein the tension sensor is provided at an intermediate position between the first drum and the second drum, and detects the tension from the amount of suspension of the lower band. Edge position control device. A drum bearing that rotatably supports both shaft ends of the second drum;
A right shift mechanism and a left shift mechanism that individually shift the drum bearing in the first direction;
A second drum right position sensor and a second drum left position sensor for detecting the position of the drum bearing in the first direction;
A second drum band edge position sensor for detecting a band edge position in the second direction by the second drum;
A right side tension sensor and a left side tension sensor respectively provided between the drum bearing and the shift mechanism;
A tension controller that keeps the band tension constant based on the tension signal of the tension sensor and outputs a bearing position correction signal for suppressing fluctuations in the band edge position in the second drum to the right shift mechanism and the left shift mechanism. The band edge position control device for a solution casting apparatus according to any one of claims 1 to 5, wherein: A dope, in which a polymer is dissolved in a solvent, is flowed from a casting die on a band that is stretched between a first drum and a second drum and travels in a first direction from the first drum toward the second drum. In the band edge position control method of the solution casting equipment to form a cast film on the band, peel the cast film from the band and dry to form a film,
An edge position in a second direction which is a width direction of the band is detected by the first drum;
Based on the detection signal of the band edge position, the center line of the steering roll contacting the inner peripheral surface of the lower band between the first drum and the second drum is inclined with respect to the reference line in the second direction. A method for controlling a band edge position of a solution casting apparatus, wherein a fluctuation of the band edge position is suppressed by moving a lower band on the steering roll along the center line in accordance with an inclination of a steering roll . The steering roll is disposed near the band entrance of the first drum;
Both ends of the steering roll are rotatably supported by bearings, the bearing is shifted by a shift portion in a direction intersecting the plane of the band, and the lower band is moved along the center line on the steering roll. band edge position control method of a solution casting apparatus of claim 9, wherein Rukoto the moved.   The method of claim 10, wherein the shift unit individually shifts the roll bearing in a direction parallel to the inner peripheral surface of the lower band. The steering roll is disposed near the band entrance of the first drum;
Both ends of the steering roll are rotatably supported by bearings, and the bearing is shifted by a shift portion in a direction parallel to the surface of the band while the steering roll is in contact with the band, and the lower band band edge position control method of a solution casting apparatus of claim 9, wherein Rukoto is moved along said center line on said steering roll. The seek moving speed of the band edge in said second direction based on the first drum band edge positions, based on the traveling speed of the moving speed of the band edge bands, the direction of reducing the moving speed of the band edge 13. The method for controlling the band edge position of a solution casting apparatus according to claim 9, wherein the steering roll is inclined. Both shaft ends of the second drum are rotatably supported by drum bearings;
The tension of the band is detected by a tension sensor,
14. The band edge position of the solution casting apparatus according to claim 9, wherein the drum bearing is shifted in the first direction by a shift mechanism based on a tension signal of the tension sensor to make the tension constant. Control method.   15. The band edge position control method for a solution casting apparatus according to claim 14, wherein the tension is detected from a suspended amount of a lower band at an intermediate position between the first drum and the second drum. Both shaft end portions of the second drum are rotatably supported by drum bearings,
A position of the drum bearing in the first direction is detected by a second drum right position sensor and a second drum left position sensor;
The drum bearings are individually shifted in the first direction by a right shift mechanism and a left shift mechanism,
A band edge position in the second direction is detected by the second drum by a second drum band edge position sensor;
The tension controller keeps the band tension constant based on the tension signals of the right tension sensor and the left tension sensor provided between the drum bearing and the shift mechanism, respectively, and changes the band edge position in the second drum. 14. The method for controlling the band edge position of a solution film-forming facility according to claim 9, wherein a bearing position correction signal for suppression is output to the right shift mechanism and the left shift mechanism. A solution casting method for forming a solution using the band edge position control method according to claim 9.

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