JP5719709B2 - Band position control apparatus and method for solution casting equipment - Google Patents

Description

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

  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, the conventional meandering control focuses only on the viewpoint of reducing the fluctuation of the band at the casting position, so that the fluctuation of the casting position can be reduced, but the film thickness unevenness is eliminated. Did not pay attention to. For this reason, measures against thickness unevenness due to secular change are insufficient, and it has been desired to reduce thickness unevenness.

  Therefore, the present invention provides a band position control device and method for a solution film-forming facility that suppresses stress on the band as much as possible to eliminate band unevenness and streak-like thickness unevenness, and can also cope with widening. The purpose is to provide.

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. A band edge position control device for a solution casting apparatus in which a dope dissolved in a solvent is cast from a casting die to form a casting film on the band, and the casting film is peeled off from the band and dried to form a film. A right side moving mechanism and a left side moving mechanism for individually moving both bearings at both shaft end portions of the second drum in the first direction, and positions of both bearings of the second drum in the first direction. a second drum right position sensor and the second drum left position sensor for detecting a second drum band edge position sensor for detecting a band edge position in the second drum in the second direction is the width direction of the band, the A band edge moving speed in the second direction of the second drum is detected based on a band edge position signal from a two-drum band edge position sensor, and an inclination of the second drum is obtained based on the band edge moving speed; A band edge position that operates the right side moving mechanism and the left side moving mechanism to incline the second drum in a direction that makes the band edge moving speed zero based on the inclination of the second drum, and suppresses fluctuations in the band edge position. And a controller.

  The band edge position controller includes a second drum band edge moving speed detector that detects a moving speed of the band edge in the second direction of the second drum, and a second drum band edge moving speed detector from the second drum band edge moving speed detector. A second drum tilt calculating unit for determining the tilt of the second drum based on the moving speed of the drum band edge position, and drums of the right moving mechanism and the left moving mechanism based on the tilt of the second drum from the second drum tilt calculating unit. It is preferable that a drum position difference calculation unit for obtaining a position difference is provided, the right side movement mechanism and the left side movement mechanism are operated based on the drum position difference, and the band edge movement speed is converged to zero.

  The present invention includes a first drum band edge position sensor that detects an edge position of the band in the second drum in the second direction, and the band edge position controller is configured to output a first drum band edge position sensor from the first drum band edge position sensor. A second drum bearing position correction signal that feeds back a difference between the first edge position signal and the target edge position signal in the first drum band edge position sensor to change the position of the bearing of the second drum in the first direction. Preferably, the band edge position of the first drum edge position sensor is constant in the second direction.

  The band edge position controller includes a band edge position compensator, and the band edge position compensator includes signals from the second drum band edge position sensor and the first drum band edge position sensor and travel of the band. It is preferable that an edge position in the second direction of the band in the first drum is predicted based on the speed signal, and the difference is corrected based on the predicted edge position value.

In the band edge position control method of the solution casting apparatus of the present invention, the band is stretched between the first drum and the second drum and travels in the first direction from the first drum toward the second drum. In addition, a dope in which a polymer is dissolved in a solvent is cast from a casting die to form a casting film on the band, and the casting film is peeled off from the band and dried to form a film. In the position control method, a position in the first direction of both bearings of the second drum is detected by a second drum right position sensor and a second drum left position sensor, and a second direction which is a width direction of the band. The band edge position at the second drum is detected by the second drum band edge position sensor, and the band edge position controller detects the band edge position from the second drum band edge position sensor. Detecting a moving speed of the band edge in said second direction of said second drum on the basis of the band edge position signal, determine the slope of the second drum based on the band edge moving speed, both axial end portions of the second drum By actuating the right side moving mechanism and the left side moving mechanism that individually move both the bearings in the first direction, the second drum is inclined in a direction that makes the band edge moving speed zero based on the inclination of the second drum. Let

  According to the present invention, the position control of the band can be performed with high accuracy, and can be suppressed to a deflection width of about 2 to 3 mm for a band of 2000 mm width, for example. Accordingly, the amount of movement of the band in the drum axis direction is reduced. Thereby, the width | variety of the non-casting area | region between the both-sides edge of a band and the both-sides edge of a casting film can be narrowed, and a wide elongate film can be manufactured efficiently. In addition, the meandering of the band can be suppressed quickly and accurately, and the amount of band shift on the drum during meandering control is also reduced. 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 also a control block diagram. It is a graph which shows the relationship between the 1st, 2nd band relative position and BE moving speed. It is a graph which shows the relationship between the drum angle of a 2nd drum, and a band edge moving speed. It is a top view which shows the principle which changes the drum angle (theta) 1 of a 2nd drum, and changes the moving speed Ve of a band edge. It is a graph which shows the relationship between the drum position of a 2nd drum, and tension. It is a graph which shows a dead zone in control of the 2nd drum band edge position. It is a flowchart which shows a band edge position control method. It is explanatory drawing which shows transition of an edge position, and has shown an example of the meandering period and amplitude. It is explanatory drawing which shows an example of transition of the edge position in 2nd condition meander control. It is a graph which shows an example of the BEP fluctuation | variation with the comparative example which does not perform BEP control based on tension at the time of casting start, and this embodiment method which performs BEP control which considered tension.

  As shown in FIG. 1, the solution casting apparatus 10 includes a casting device 11, a first tenter 12, a roller 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 peeling roller 27, and a band edge position (BEP) control device ( (Hereinafter referred to as a BEP control device) 28. The band 23 is an endless 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 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 roller 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 roller 27 is provided on the upstream side in the traveling direction of the casting die 24 of the first drum 21. The peeling roller 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 roller drying device 13, the film 32 is wound around a large number of rollers 36 and conveyed. The atmosphere inside the roller drying device 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 BEP control device 28 includes bearings 40 </ b> R and 40 </ b> L, shift mechanisms 41 </ b> R and 41 </ b> L provided at both ends of the drum shaft 22 a of the second drum 22, and bearing positions of the second drum 22. Sensors 42R, 42L, tension sensors 43R, 43L, first drum band edge position sensor (hereinafter referred to as first drum BEP sensor) 44, second drum band edge position sensor (hereinafter referred to as second drum BEP sensor) 45 An intermediate portion tension sensor 46 and a band edge position controller (hereinafter referred to as a BEP controller) 47. In FIG. 2, with reference to the direction of the first direction A that is the traveling direction of the band 23, the members on the right side are denoted by “R” in the reference numerals of the members, and the members on the left side. The symbol of each member is marked with “L”.

  The first drum 21 is rotatably supported by bearings 51 at both ends of the drum shaft 21a. A drum rotation motor 29 is connected to one end. A TG (tacho generator) 50 is connected to the drum rotation motor 29, and the TG 50 detects the rotation speed of the first drum 21. The drum rotation motor 29 is connected to the system controller 48 via a driver 49. The TG 50 is also connected to the system controller 48. The system controller 48 controls the rotation of the drum rotation motor 29 so that the band 23 rotates at a constant speed. The system controller 48 changes the traveling speed and drying temperature of the band 23 according to the film forming conditions.

Both end portions of the drum shaft 22a (rotating shaft) of the second drum 22 are rotatably held by bearings 40R and 40L. These bearings 40R and 40L are provided movably in a first direction toward the first drum 21 within a horizontal plane including the drum shafts 21a and 22a. And it shifts to the 1st direction A each independently by the shift mechanisms 41R and 41L. The bearings 40R and 40L are attached to the shift mechanisms 41R and 41L so as to be rotatable in a horizontal plane. As shown in FIG. 7, due to the independent displacement of the bearings 40R and 40L in the first direction, the center line CL2 of the second drum 22 is inclined at an arbitrary drum angle θ1 with respect to the reference line BL1 in the horizontal plane. . By this inclination, the meandering of the band 23 in the first drum 21 is corrected and the tension of the band 23 is adjusted. In addition, since the positions of the bearings 40R and 40L can be individually changed on both the left and right sides, tension unevenness in the second direction (bandwidth direction) B can be eliminated.

  The shift mechanisms 41R and 41L are only required to be able to move the bearings 40R and 40L, and those using a hydraulic cylinder and those driven by rotation of the worm shaft are appropriately selected.

  A right bearing position sensor 42R is attached to the right bearing 40R, and a left bearing position sensor 42L is attached to the left bearing 40L. These bearing position sensors 42R and 42L detect the positions of the bearings 40R and 40L in the first direction A, output this position signal, and function as a second drum right position sensor and a second drum left position sensor. Instead of detecting the bearing positions by the bearing position sensors 42R and 42L, 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 43R and a left tension sensor 43L are attached between the bearings 40R, 40L and the shift mechanisms 41R, 41L. The right tension sensor 43R and the left tension sensor 43L detect the tension of the band 23 and output it as a tension signal.

  A first drum band edge position sensor sensor (hereinafter referred to as a first drum BEP sensor) 44 is provided in the vicinity of the first drum 21. A second drum band edge position sensor (hereinafter referred to as a second drum BEP sensor) 45 is provided on the second drum 22. The first and second drum BEP sensors 44 and 45 detect one side edge of the band 23, for example, the left edge position in the film width direction (second direction B), and a first band edge position signal (hereinafter referred to as a first band edge position signal). 1BEP signal) and a second band edge position signal (hereinafter referred to as a second BEP signal).

An intermediate tension sensor 46 is provided near the left edge of the lower band 23 at an intermediate position between the first drum 21 and the second drum 22. The intermediate portion tension sensor 46 determines the tension of the band 23 from the amount of suspension at the center position of the lower band 23. 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 suspension amount at the center of the band may be a natural suspension amount due to the weight of the band itself, or may be a suspension amount in a state of being biased downward by a pressing roller 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 40R and 40L so that the tension signal from the intermediate portion tension sensor 46 is 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.

  Signals from the sensors 42R, 42L, 43R, 43L, 44 to 46 are sent to a band edge position controller (hereinafter referred to as a BEP controller) 47. The BEP controller 47 includes signals from the sensors 42R, 42L, 43R, 43L, 44, and 45, a first band edge position command signal (hereinafter referred to as a first BEP command signal) from the system controller 48, a speed command signal, a tension Based on the command signal, position signals of the bearings 40R and 40L of the second drum 22 are output, and the band edge position is controlled so that the edge of the band 23 in the first drum 21 is always within a certain range in the second direction. .

  As shown in FIG. 4, the BEP controller 47 includes a first drum band edge position compensator (hereinafter referred to as a first drum BEP compensator) 56, a second drum band edge position command controller (hereinafter referred to as a second drum BEP command). 57), second drum position command controller 58, tension controller 59, first adder 61, second adder 62, third adders 63R and 63L, fourth adder 64, second drum band. An edge moving speed detector 65 (hereinafter referred to as a second drum BE moving speed detector) and a tension controller 59 are provided.

  The first drum BEP compensator 56 includes a first drum band edge position signal from the first drum BEP sensor 44, a second drum band edge position signal from the second drum BEP sensor 45, and a band running from the system controller 48. Receives input of speed command signal. First, the band edge moving speed Ve1 in the second direction B in the second drum is obtained from the fluctuation amount of the second drum band edge position, and the moving speed diagram of FIG. 5 is created. Since the band edge moving speed Ve1 changes in proportion to the traveling speed of the band 23, a band traveling speed command signal is also used. The band edge moving speed Ve1 is a moving speed in a long period such that the band makes one round, for example.

  FIG. 5 shows the relationship between the relative positions of the first and second bands and the band edge moving speed Ve. Here, the first and second band relative positions are obtained from (first drum BEP−second drum BEP) / band travel speed, and indicate the inclination angle of the band 23 as viewed from the second drum 22. Yes. The proportional expression Y = a1 · X displayed by the solid line SL is obtained in advance by experiments and simulations in an actual machine. In the equilibrium state, the relative positions of the first and second bands are at the reference position “0”, and the BE moving speed Ve is “0”. When the equilibrium state collapses due to the temperature distribution unevenness of the band due to the temperature rise from this equilibrium state, the proportional relationship shifts upward by, for example, the Y component b1, as indicated by the broken line BRL. When the first and second band relative positions change, for example, to the right side, the BE movement speed Ve also increases in proportion to the proportional coefficient a1, and the first and second band relative positions change to the left side. The relative positions of the first and second bands are also reduced in proportion.

  The first drum BEP compensator 56 receives the first BEP signal and the second BEP signal from the first and second drum BEP sensors 44 and 45, and the traveling speed of the band 23 is input from the system controller 48. Yes. Then, the current second drum band edge moving speed Ve1 is obtained from the fluctuation amount of the BEP signal from the second drum BEP sensor 45, and the obtained second drum band edge moving speed Ve1 is set as a shift amount b1 with respect to the solid line SL. A broken line BRL composed of a proportional expression of Y = a1 · X + b1 is created. From this broken line BRL, the first and second relative positions at which the BE moving speed Ve becomes “0”, for example, “−0.2” in the case of FIG.

Next, based on the obtained first and second relative position signals “−0.2”, the current speed command, the first drum BEP signal from the first drum BEP sensor 44, and the second drum BEP sensor 45 From the second drum BEP signal, a target second BEP signal is obtained with respect to the current first BEP signal. this is,
(Relative position of first and second bands) = (first drum BEP−second drum BEP) / band running speed (2)
Substituting “−0.2” of the relative position between the first and second bands, the current band traveling speed, and the current first drum BEP signal into the formula, the target second drum BEP signal is obtained. . Then, the obtained second BEP signal is set as a target BEP signal in the second drum. Next, a deviation between the target BEP signal and the actual BEP signal from the second drum BEP sensor is obtained, and this deviation is output to the second drum BEP command controller 57 as a position compensation value.

  The first adder 61 obtains a deviation between the first BEP signal from the first drum BEP sensor 44 and the position command signal as a target value from the system controller 48, and inputs this deviation to the second drum BEP command controller 57. To do.

  The second drum BEP command controller 57 uses the deviation signal input from the first adder 61 as a PID control signal, adds the compensation value from the first drum BEP compensator 56 to this PID control signal, and outputs the second drum It outputs to the adder 62 as a BEP command signal.

  The second adder 62 adds the second BEP signal from the second drum BEP sensor 45 and the second BEP command signal from the second drum BEP command controller 57. The signal after the addition is input to the second drum position command controller 58.

Based on the BEP signal from the second drum BEP sensor 45, the second drum BE moving speed detector 65 obtains the moving speed Ve2 of the band edge in the second direction of the second drum 22. The determined BE moving speed Ve2 is sent to the second drum position command controller 58. The BE moving speed Ve2 obtained here is a moving speed in a shorter time than the BE moving speed Ve1 obtained by the first drum BEP compensator 56. For example, the BE moving speed Ve2 is based on data for each rotation of the second drum. Calculated.

The second drum position command controller 58 rotates the second drum in a direction to set the BE moving speed Ve2 to “0” based on the BE moving speed Ve2 and the bearing position signal from each of the bearing position sensors 42R and 42L. Each bearing position signal for tilting the shaft is output to the shift mechanisms 41R and 41L.

  For this reason, the second drum position command controller 58 has a second drum inclination calculation unit 58A and a drum position difference calculation unit 58B. The second drum tilt calculation unit 58A stores a table showing the relationship between the drum angle θ1 and the BE moving speed Ve2 as shown in FIG. The proportionality coefficient a2 of the solid line SL formed of the proportional expression in the above table is obtained in advance by experiments or simulations using an actual machine. The solid line SL represents the relationship of the BE moving speed Ve2 corresponding to the drum angle θ1 when the drum angle θ1 changes. Using this solid line SL, a target drum angle θ1 for converging the BE moving speed Ve to “0” is obtained from the BE moving speed Ve2. Then, the obtained target drum angle θ1 is sent to the drum position difference calculation unit 58B.

  In FIG. 6, in the equilibrium state, when the drum angle θ1 of the second drum 22 is “0”, the BE moving speed Ve2 is also “0”. When the equilibrium state collapses due to the temperature distribution unevenness of the band due to the temperature rise from this equilibrium state, the proportional relationship shifts upward by, for example, the Y component b2, as indicated by the broken line BRL. When the drum angle θ1 changes, for example, to the right side, the BE movement speed Ve2 also increases in proportion to the proportional coefficient a2, and when the drum angle θ1 changes to the left side, the BE movement speed Ve2 also increases in proportion. Decrease.

  Therefore, as shown in FIG. 6, a broken line BRL including a proportional expression of Y = a2 · X + b2 in which the shift amount with respect to the solid line SL is b2 is created. From this broken line BRL, the drum angle θ1 at which the BE moving speed Ve2 becomes “0”, for example, “−0.2” in the case of FIG. 6 is obtained. The obtained drum angle θ1 is output to the drum position difference calculation unit 58B as a target drum angle signal.

  The drum position difference calculator 58B calculates a correction amount based on the position difference between the bearings on both sides based on the target drum angle θ1 (= −0.2). In this case, in the present embodiment, the right bearing position difference correction amount MR1 and the left bearing position difference correction amount ML1 are respectively obtained with reference to a certain position of the second drum BEP sensor 45, and these are obtained as the third adder 63R. , 63L. Specifically, as shown in FIG. 7, the position difference correction amount MR1 of the right bearing is obtained from (MR1 = LR1 · tan θ1) with reference to the second drum BEP sensor 45. Similarly, the position difference correction amount ML1 of the left bearing is obtained from (ML1 = LL1 · tan θ1). In the present embodiment, the position difference correction amounts MR1 and ML1 of each bearing are obtained based on the mounting position of the second drum BEP sensor 45, but the center portion of the second drum 22 in the second direction is used as a reference. The position difference correction amounts MR1 and ML1 may be obtained.

  The third adders 63R and 63L add a compensation signal for making the tension of the tension controller 59 constant to the position difference correction amounts MR1 and ML1. The fourth adder 64 obtains the difference between the added value of the left and right tension signals from the right tension sensor 43R and the left tension sensor 43L and the tension command signal as the target value from the system controller 48, and uses this signal as a tension control. Output to the instrument 59.

  The tension controller 59 is composed of a drum position compensator 59a, and outputs a drum position compensation value that cancels the tension fluctuation. Therefore, the drum position compensator 59a receives the right bearing position signal PR1 from the right bearing position sensor 42R, the left bearing position signal PL1 from the left bearing position sensor 42L, and the tension command difference signal T1 from the fourth adder 64. Each is entered.

  The tension controller 59 stores a table showing the relationship between the drum position P and the tension T as shown in FIG. The proportionality coefficient a3 of the solid line SL made up of the proportional expression in the above table is obtained in advance by experiments or simulations using actual machines. This solid line SL shows the fluctuation of the tension T corresponding to the drum position P when the drum position P changes. Using this proportional expression SL, drum position difference correction amounts MR2 and ML2 corresponding to the tension command difference signal T1 are obtained.

  In FIG. 8, in the equilibrium state, the tension T is also “0” when the drum position P of the second drum 22 is “0”. When the equilibrium state collapses due to the temperature distribution unevenness of the band due to the temperature rise from this equilibrium state, the proportional relationship shifts upward by, for example, the Y component b3 as indicated by the broken line BRL. When the drum position P changes to the right side, for example, the tension T increases in proportion to the proportional coefficient a3 according to this change, and when the drum position P changes to the left side, the tension T decreases in the same proportional relationship.

  Therefore, as shown in FIG. 8, a broken line BRL made of a proportional expression of Y = a3 · X + b3 where b is the shift amount with respect to the solid line SL is created. From this broken line BRL, the drum position P at which the tension T becomes “0”, for example, “−0.1” in the case of FIG. 8, is obtained, and this obtained drum position P is set as the target drum position difference correction amount. Then, the drum position difference correction amounts MR2 and ML2 are added to the position signal PR1 of the right bearing position sensor 42R to obtain a right bearing compensation value signal (PR1 + MR2) and a left bearing compensation value signal (PL1 + ML2). Output to 63R and 63L.

  Since the third adders 63R and 63L output the right bearing position difference correction amount MR1 and the left bearing position difference correction amount ML1 from the second drum position command controller 58, respectively, the shift mechanisms 41R and 41L include A right bearing position signal (PR1 + MR1 + MR2) and a left bearing position signal (PL1 + ML1 + ML2) are output.

  The shift mechanisms 41R and 41L move the bearings 40R and 40L (see FIG. 2) based on the right bearing position signal (PR1 + MR1 + MR2) and the left bearing position signal (PL1 + ML1 + ML2). As a result, the drum shaft 22a of the second drum 22 is inclined at the drum angle θ1 with respect to the reference line BL1 in the horizontal plane, and the band 23 is displaced on the second drum 22 by an amount corresponding to the inclination. The band edge position in the BEP sensor 44 is changed to the target position. In this way, the left and right shift mechanisms 41R and 41L can be used to instantly change the drum axis of the second drum 22, so that even if the band 23 travels at a high speed, it can meander quickly and reliably. Can be suppressed.

  As a result of the series of operations described above, both end portions of the drum shaft 22a of the second drum 22 change to positions corresponding to the respective signals, so that the band edge position in the first drum 21 is always kept within a constant range. Therefore, the fluctuation of the band edge position in the first drum can be suppressed, and the bead can be cast to a fixed position of the band with high accuracy. Since fluctuations in the band edge position can be suppressed, the film can be cast near the edge of the band 23, and the film 32 can be easily widened.

  In particular, a first drum BEP sensor 44 and a second drum BEP sensor 45 are provided, and a signal from the second drum BEP sensor 45 and the first drum BEP sensor 44 and a traveling speed signal of the band 23 are provided by the first drum BEP compensator 56. Based on the above, the edge in the second direction of the band 23 in the first drum 21 is predicted, and the difference is compensated by this predicted value, so that the meandering can be suppressed before the meandering actually occurs, and The meandering width can also be kept small. Therefore, the edge of the band 23 in the first drum 21 can be held at a fixed position with a narrow range.

  Further, a right tension sensor 43R and a left tension sensor 43L that are provided at both ends of the drum shaft 22a of the second drum 22 and detect the tension of the band 23 on the right and left sides, respectively, and a tension controller 59 are provided. The controller 59 outputs a bearing position correction signal for the second drum 22 based on the tension signals of the right tension sensor 43R and the left tension sensor 43L and the target tension so as to achieve the target tension. Control becomes possible, and the edge of the band 23 in the first drum 21 can be positioned at a substantially constant position with higher accuracy.

  In addition, the tension controller 59 can efficiently suppress the tension fluctuation when the temperature distribution of the band 23 is unstable. Therefore, when the casting is started, the casting speed is changed, the drying temperature of the casting film is changed, and the like. The band meandering can be efficiently suppressed. As described above, the fluctuation range in the film width direction of the band edge position on the first drum 21 is conventionally changed even at the time when the temperature distribution of the band is likely to change at the start of casting or the like by the multiple loop considering the tension fluctuation. When the band width is 2000 mm, which is smaller than that of the above-mentioned one, for example, the fluctuation width can be suppressed to 2 mm, and the meandering control is performed with high accuracy by this amount.

  As described above, meandering correction control for 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 43R and 43L, 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.

  In the above embodiment, the control for suppressing meandering is performed using the position signals of the bearing position sensors 42R and 42L that can be directly used as a control factor without using the second drum angle θ itself. Any factor can be used as long as the second drum angle θ can be changed, and the second drum angle θ may be used as it is to control the meandering.

  In the above-described embodiment, the relationship is described as a proportional relationship in which each relationship is represented by a straight line in FIGS. 5, 6, and 8. However, this relationship is not limited to a proportional relationship, and may be a relationship represented by various curves. .

  In the above-described embodiment, meandering control is performed in consideration of tension fluctuations on the left and right of the band 23 by the tension signals from the tension sensors 43R and 43L provided on the drum shaft 22a of the second drum 22. The meandering control may be performed in consideration of the tension variation based on the signal from the tension sensor 46 based on the amount of suspension of the lower band at the intermediate position in the band traveling direction. In this case, in FIG. 4, the right and left tension sensors 43R and 43L are omitted, and the tension signal from the intermediate tension sensor 46 is input to the fourth adder 64 instead of the tension signals from these sensors.

  Further, in addition to the tension signals of the right and left tension sensors 43R and 43L, the tension signal of the intermediate tension sensor 46 is input to the fourth adder 64, and the meandering is performed with the tension signal of the intermediate tension sensor 46 taken into account. You may control. In this case, meandering control can be performed more accurately by changing the weights of the tension signals of the right and left tension sensors 43R and 43L and the tension signal of the intermediate portion tension sensor 46 and adding them.

  As shown in FIG. 9, when the second drum BEP is in a certain range of the dead zone Z1, the bearing position signals are set so as not to change. Therefore, when the second drum BEP comes out from the dead zone Z1, drum tilt control (drum tilt control by individual movement of the bearing positions on both sides) is started. If control is performed for each variation in the dead zone Z1, even greater variation may be induced. Therefore, control is performed only for the variation exceeding the dead zone Z1. As a result, a large fluctuation is not induced, and the band edge position can be accurately suppressed within a predetermined control width.

  As described above, meandering control can be performed with high accuracy in response to various changes such as when the drying conditions are changed, when the casting speed is changed, and when the dope component is switched, in addition to when casting starts. In addition, when a certain period of time has elapsed from the start of casting or the condition change and the temperature unevenness of the band 23, the temperature unevenness of the drying air, and the like are reduced, the meandering is reduced and the traveling of the band 23 is also stabilized. In such a case, the tension fluctuation due to the temperature fluctuation of the band and the temperature fluctuation of the drying air is eliminated, so that the meandering control due to the tension fluctuation may be stopped. The life of the shift mechanism can be extended by stopping the meandering control due to the tension fluctuation.

  In this case, as shown in FIG. 10, from the first condition meandering control step S1 performed at the start of casting or at the time of changing the film forming conditions, the meandering control due to the tension variation is not performed, and the first drum BEP sensor 44, automatically switching to the second condition meandering control step S2 in which only the BEP control based on the signal of the second drum BEP sensor 45 is performed. This switching is performed after the temperature distribution of the band 23 becomes uniform and the state shifts to a steady state. Detection of the transition to the steady state is performed based on the transition time to the steady state based on the experience value. In the second condition meandering control step S2, meandering control for reducing stress on the band 23 is performed.

  Switching from the first condition meandering control step S1 to the second condition meandering control step S2 is performed in place of or in addition to whether or not a certain time has passed, and the meandering amplitude Wm1 (see FIG. 11) is within a certain range. When the convergence time has passed a predetermined time, the second condition meandering control step S2 may be switched.

The stress applied to the band 23 can be obtained by K · Wm / Tm ² . K is a correction coefficient, Wm is the meandering amplitude, and Tm is the meandering period (see FIG. 11). As is clear from the above equation, as the amplitude Wm increases, the stress increases in proportion thereto. Further, as the period Tm becomes longer, the stress decreases in inverse proportion to the square of the period Tm.

  In the present embodiment, since the meandering control due to the tension fluctuation is stopped in the steady state, the bearing position change that suppresses the tension fluctuation is not generated. 23 can be reduced. Accordingly, it is possible to suppress the occurrence of a streak-like peak in the band 23 due to the secular change caused by the meandering of the band 23, and to extend the life.

  FIG. 11 shows the meander period Tm1 and the amplitude Wm1 based on the BEP signal at the start of casting. FIG. 12 shows the meandering period Tm2 and the amplitude Wm1 based on the BEP signal after shifting to the steady state. Thus, in a steady state, the meandering cycle Tm2 is longer than the meandering cycle Tm1 at the start of casting, and stress is reduced. FIG. 13 shows an example of meandering by BEP when the conventional method and the method of the present embodiment are performed at the start of casting. In the conventional method, since the BEP control in consideration of the tension is not performed, it is understood that the tension fluctuation due to the temperature distribution unevenness of the band 23 is added and the amplitude is increased. On the other hand, by performing BEP control that takes tension into consideration as in this embodiment, the amount of tension fluctuation due to uneven temperature distribution of the band 23 is effectively suppressed, and the amplitude width is suppressed to a narrow range. .

  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 roller 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 roller. In this case, the first drum BEP sensor 44 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 apparatus 11 Casting apparatus 21 1st drum 22 2nd drum 21a Drum shaft 23 Band 30 Dope 31 Casting film 32 Film 40R, 40L Bearing 41R, 41L Shift mechanism 42R, 42L Bearing position sensor 43R, 43L Tension sensor 44 First drum BEP sensor 45 Second drum BEP sensor 46 Intermediate section tension sensor

Claims (8)

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 device of the solution casting equipment for forming a cast film on the band, peeling the cast film from the band and drying to form a film,
A right side moving mechanism and a left side moving mechanism for individually moving both bearings at both shaft end portions of the second drum in the first direction;
A second drum right side position sensor and a second drum left side position sensor for detecting positions of both bearings of the second drum in the first direction;
A second drum band edge position sensor for detecting a band edge position in a second direction which is a width direction of the band by the second drum;
A band edge moving speed in the second direction of the second drum is detected based on a band edge position signal from the second drum band edge position sensor, and an inclination of the second drum is obtained based on the band edge moving speed. The band that suppresses the fluctuation of the band edge position by operating the right side moving mechanism and the left side moving mechanism to incline the second drum in a direction to make the band edge moving speed 0 based on the inclination of the second drum. An edge position controller, and a band edge position control apparatus for a solution casting apparatus. The band edge position controller is
A second drum band edge moving speed detector that detects a moving speed of the band edge in the second direction of the second drum;
A second drum tilt calculating unit for determining the tilt of the second drum based on the second drum band edge position moving speed from the second drum band edge moving speed detecting unit;
A drum position difference calculation unit that obtains a drum position difference between the right side movement mechanism and the left side movement mechanism based on the inclination of the second drum from the second drum inclination calculation unit;
2. The band edge position control device for a solution casting apparatus according to claim 1, wherein the right side moving mechanism and the left side moving mechanism are operated based on the drum position difference to converge the band edge moving speed to zero. A first drum band edge position sensor for detecting an edge position in the second direction of the band in the first drum;
The band edge position controller feeds back a difference between a first edge position signal from the first drum band edge position sensor and a target edge position signal in the first drum band edge position sensor, and 2. A bearing position correction signal for a second drum that changes a bearing position in the first direction is output, and a band edge position in a first drum edge position sensor is made constant in the second direction. Or the band edge position control apparatus of the solution film-forming equipment of 2. The band edge position controller has a band edge position compensator,
The band edge position compensator is configured to control the second band of the first drum based on each signal of the second drum band edge position sensor and the first drum band edge position sensor and a traveling speed signal of the band. 4. The band edge position control device for a solution casting apparatus according to claim 3, wherein an edge position in a direction is predicted, and the difference is corrected based on the predicted edge position value. 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,
Detecting positions of both bearings of the second drum in the first direction by a second drum right position sensor and a second drum left position sensor;
A band edge position in a second direction which is a width direction of the band is detected by the second drum band edge position sensor in the second drum;
A band edge position controller detects a moving speed of the band edge in the second direction of the second drum based on a band edge position signal from the second drum band edge position sensor, and based on the band edge moving speed, 2 tilts of the two drums are obtained, and a right side moving mechanism and a left side moving mechanism that individually move both bearings at both shaft end portions of the second drum in the first direction are operated, and based on the tilt of the second drum A method of controlling a band edge position of a solution casting apparatus, wherein the second drum is inclined in a direction in which a band edge moving speed is set to 0 to suppress fluctuations in the band edge position. A second drum band edge moving speed detector detects a moving speed of the band edge in the second direction on the second drum;
Based on the detected movement speed signal of the band edge, a second drum inclination detector determines an inclination of the second drum with respect to a reference line in the second direction of the second drum, and the right side is determined based on the obtained second drum inclination. 6. The method for controlling the band edge position of a solution casting apparatus according to claim 5, wherein the moving mechanism and the left moving mechanism are operated to converge the band edge moving speed to zero. An edge position in the second direction of the band in the first drum is detected by a first drum band edge position sensor;
The band edge position controller feeds back a difference between a first band edge position signal from the first drum band edge position sensor and a target edge position signal in the first drum band edge position sensor, and The bearing position is changed in the first direction, a bearing position correction signal for the second drum is output, and the band edge position in the first drum band edge position sensor is held constant in the second direction. The band edge position control method of the solution casting apparatus according to claim 5 or 6. The band edge position controller has a band edge position compensator;
By means of the band edge position compensator, the second drum right position sensor, the second drum left position sensor, the second drum band edge position sensor, the first drum band edge position sensor and the traveling speed signal of the band. 8. The band edge of the solution casting apparatus according to claim 7, wherein a band edge position in the second direction of the band on the first drum is predicted, and the difference is corrected by the predicted edge position value. Position control method.

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