KR20130136915A - Solution film forming method and facility - Google Patents

Abstract

The present invention uses a band (33) of a ring shape, as a flexible supporter, in which a central part (33c) and a side part (33s) are integrated by a welding part (33w). The band (33) is circulated by the rotation of a drum (34) and moves in a longitudinal direction (A direction). The present invention makes a dope flexible in order to form a flexible layer (39) on the central part (33c) and side part (33s) of the band (33) from a flexible die (38), performs slight compulsory deviation so that the band (33) located at a flexible position oscillates in a width direction on a regular cycle by a BEP controller (54) uniformly maintaining the edge position of the band (33). A region, which is the part of the flexible layer (39) located on the welding part (33w), becomes a slightly deviated form by the slight compulsory deviation. When a film is rolled, a black line in a film roll is removed since the region located on the welding part is rolled in the deviated form. [Reference numerals] (54) BEP controller;(55) Compulsory performance seting part;(61) Shift equipment

Description

SOLUTION FILM FORMING METHOD AND FACILITY

TECHNICAL FIELD This invention relates to the solution film forming method and installation which use the annular band which has the welding part extended in the longitudinal direction on both sides as a flexible support body.

With large screens of liquid crystal displays (LCDs), large areas are also required for optical films used in LCDs. The optical film is made into a long film and then cut into a predetermined size to correspond to the LCD. Therefore, in order to manufacture an optical film of a larger area, it is necessary to manufacture so that width may become larger in manufacturing a long optical film.

As a typical manufacturing method of a long optical film, there exists a solution film forming method of a continuous system. The solution film-forming method is a method of manufacturing a film from the dope which a polymer melt | dissolved in a solvent like well-known. In the continuous solution formation method, dope is continuously flown on the flexible support which runs. On the flexible support body, the flexible film which is dope in a film form is solidified by drying etc., and then peeled off from a flexible support body. The film roll is obtained by drying the peeled cast film and winding up the obtained film in roll shape.

As the flexible support, there is an endless (endless) band made of metal. The width of the film that can be produced is constrained by the width of the band, and in order to produce a larger film, a larger band is required. However, so far, only bands up to 2 m in width have been obtained.

Therefore, in Korean Patent Publication No. 2009-0110082, a band having a width of 2200 mm, which is larger than the conventional one, is welded in the longitudinal direction to the center band serving as the center portion in the width direction and the pair of side bands serving as the side portions of the band. Getting it. By this band, a long optical film with a wider width than before can be produced.

By the way, when using the band by which such center band and the side band were welded in the longitudinal direction in a solution film forming method, a black stripe appears in the obtained film roll. The black stripe extends in the circumferential direction as if the film roll is rotated once, and occurs on both sides of the film roll. This black stripe is in the shape of a band having a width of about 10 mm. Thus, the film roll which a black strip | line shows is inferior in commodity value in an external surface, a performance surface, etc. As a problem in performance, when apply | coating a coating liquid to the film unwound from this film roll, and forming a coating film, what is called application | coating deviation which a coating film is not formed uniformly may arise, for example. Thus, the phenomenon in which black streaks appear on a film roll can be considered that the area | region on the weld part of a side band and a center part band of a flexible film is contained in the product area | region of a film.

However, the strip | belt-shaped black stripe extended in the circumferential direction may be confirmed also by the film roll in the case of using the conventional band manufactured without welding in a longitudinal direction. The phenomenon in which such band-shaped black streaks arise is called black band failure. In order to suppress such black belt failure, for example, in Japanese Patent Laid-Open Publication No. 2003-147092, a knurled portion (unevenness) is formed at an end portion in the width direction, and the thickness of the cross section in the width direction of the film is 2 than the thickness of the knurled portion. The method of winding by displacing a long elongate film with a displacement amount of 1.0 to 4.0 mm in the width direction is small.

Korean Patent Laid-Open Publication No. 2009-0110082 suggests that the region on the welded portion between the center band and the side band of the flexible film is included in the product region of the film. However, Korean Patent Laid-Open Publication No. 2009-0110082 discloses that in a film forming solution using a band, in which a center band and a side band are welded in the longitudinal direction, as a flexible support, black streaks appear on the obtained film roll, and the black streaks appear. There is no mention of the cause and the method of preventing the occurrence of this black line. In addition, in the solution film formation using the band described in Korean Patent Laid-Open Publication No. 2009-0110082 as a flexible support, black streaks still appear on the obtained film roll even when the method of Japanese Patent Laid-Open Publication No. 2003-147092 is applied.

Therefore, an object of this invention is to provide the solution film forming method and installation which do not have black streaks extended in the circumferential direction in the film roll obtained when using the band in which the weld part extended in the longitudinal direction is used as a flexible support body.

The solution film forming method of the present invention includes a traveling step, a forced meandering step, a flexible film forming step, a film forming step, and a winding step. The traveling step causes the annular metal bands to travel over the circumferential surface of the pair of drums. The band has a side portion which is integrated by welding at both ends of the center portion and the center portion. The forced meandering step performs a forced meandering in which the band while traveling is displaced at a constant amplitude in the width direction. In the cast film forming step, the dope in which the polymer is dissolved in the solvent is cast into a band to form a cast film. The dope is flexible to the band displaced in the width direction. The dope is flexible to a wider width than the center portion, so that the flexible film is formed on the center portion and on the side portion. In the film forming step, the cast film is peeled off from the band and dried to obtain a film. The winding-up step winds up a film in roll shape.

It is preferable that the constant amplitude of a band is more than the width in the flexible film width direction of the area | region on the weld part of the flexible film formed on the welding part extended in the running direction of a band.

The pair of drums are a first drum and a second drum farther from the dope casting position than the first drum. On the plane including the rotating shaft of the first drum and the rotating shaft of the second drum, it is preferable to incline the rotating shaft of the second drum in the width direction of the band to displace the band in the width direction.

It is preferable to vary the inclination angle of the rotating shaft of the second drum by a sine wave or a triangle wave.

It is preferable that the displacement period of the band is not less than half of the turn time of the band, or less than two turns of time.

It is preferable to change the inclination angle of the rotational axis of the second drum by using a band edge position control unit that changes the inclination angle of the rotational axis of the second drum and keeps the band edge position at the flexible position relative to the band of the dope. Do.

The solution film forming equipment of the present invention includes a first drum and a second drum, an annular metal band, a casting die, a casting film drying portion, a peeling roller, and a drum rotation shaft inclination portion. The band travels rotationally over the first drum and the second drum. The band has a pair of side parts integrated by welding at both ends of the center part and the center part. A casting die casts the dope which the polymer melt | dissolved in the solvent on the band containing both sides, and forms a casting film. The second drum is farther from the die than the first drum. The casting film drying unit evaporates the solvent from the casting film to dry the casting film. The peeling roller peels off the cast film dried by the cast film drying part from the band. The drum rotation shaft inclination portion inclines the rotation shaft of the second drum to displace the band with a constant amplitude in the width direction of the band. The axis of rotation of the second drum is inclined on a plane including the axis of rotation of the first drum and the axis of rotation of the second drum.

According to this invention, when using the band which has a welding part extended in the running direction as a flexible support body, the film roll without a black stripe extending in a circumferential direction is obtained.

The above objects and advantages will be readily understood by those skilled in the art by reading the detailed description of the preferred embodiment with reference to the accompanying drawings.
1 is a side view showing an outline of a solution film production facility.
2 is a plan view of the band and the flexible membrane.
Fig. 3 shows the relationship between the welded part of the band and the region on the welded part of the film, (A) is a plan view showing the relationship between the welded part of the band and the flexible film, and (B) is a plan view of the film obtained from the flexible film of (A).
4 is a plan view of a BEP control unit;
Fig. 5 is a graph showing the relationship between the inclination angle θ1 of the second drum rotating shaft and the band edge position at the time of band length travel when the inclination angle θ1 is used.
Fig. 6 is a plan view showing the welded phase region of the film obtained by forced trace meandering of the band.
FIG. 7 is a graph showing the band edge position in the flexible position when the inclination angle θ1 of the second drum rotational axis in the BEP control unit is sine wave forcibly traced in the flexible position in band circumference. .
Fig. 8 is a graph showing the band edge position in the flexible position in the case of forced trace meandering with the oscillation angle of the second drum rotating shaft being a triangular waveform in the same manner.

As shown in FIG. 1, the solution film forming equipment 10 includes the casting apparatus 11, the first slitter 12, the first tenter 13, the roller drying apparatus 16, and the second tenter. (17), the 2nd slitter 18, and the winding device 19 are provided in order from an upstream side, and these are connected in series.

The casting apparatus 11 forms the cellulose acylate film (hereinafter simply referred to as "film") 25 from the dope 24 in which the cellulose acylate 22 is dissolved in the solvent 23. The first slitter 12 cuts off both side edges of the film 25. The first tenter 13 sends drying air from the duct 29 to advance drying while supporting both edges of the film 25 with the clip 28. The roller drying apparatus 16 dries while supporting the film 25 with the some roller 30. The 2nd tenter 17 supports the both edges of the film 25 with the clip 31, and gives the film 25 the tension | tensile_strength in the width direction. Moreover, dry air is sent from the duct 32, and the film 25 is kept at a fixed temperature. The 2nd slitter 18 cuts off the support trace of each side part supported by the clip 31 of the 2nd tenter 17. As shown in FIG. The winding device 19 winds the film 25 around the core 26 to form a film roll 27.

The flexible apparatus 11 has a pair of 1st drum 34 and the 2nd drum 35, and the endless band (henceforth a band | band) 33 interposed between them. The 1st drum 34 is a drive drum rotationally driven by a motor. The second drum 35 is a driven drum that is free to rotate.

As shown in FIG. 2, the band 33 consists of the center part 33c and a pair of side part 33s formed in the both sides of the center part 33c, and the center part 33c and the side part 33s are welded parts. It is welded integrally by 33w. The band 33 travels in the longitudinal direction (A direction) by the rotation of the first drum 34.

The width Wc of the center portion 33c is wider than the width Ws of the side portion 33s. The center portion 33c is formed from a band member having a width of approximately 1500 mm or more and 2100 mm or less, which is conventionally widely used as a flexible support. The side portions 33s are formed from a band member having a width of about 50 mm or more and 500 mm or less. The width | variety of the band 33 is the range of 2000 mm or more and 3000 mm or less.

As shown in FIG. 1, the casting die 38 is provided above the 1st drum 34. As shown in FIG. As shown in FIG. 2, the casting die 38 has a slit-shaped outlet 38a through which the dope 24 flows out. The casting die 38 is arrange | positioned in the state which made the outlet 38a adjoining the band 33, and made the longitudinal direction of the outlet 38a coincide with the band width direction (henceforth B direction). By continuously flowing the dope 24 from the casting die 38 into the band 33, the dope 24 is cast on the band 33 to form the casting film 39.

The length of the outlet 38a in the B direction is larger than the width Wc of the central portion 33c, and the flexible die 38 has one end in the longitudinal direction of the outlet 38a on the other side 33s and the other end. It is arrange | positioned so that it may become on this other side part 33s. Thereby, the dope 24 which flowed out from the outlet 38a of the casting die 38 forms the casting film 39 on both the center part 33c and the side part 33s. Thereby, the flexible area | region Ac in which the flexible film 39 is formed extends from one side part 33s to the other side part 33s so that one welding part 33w and the other welding part 33w may be included. However, both sides of the flexible surface of the band 33 are non-flexible regions An in which the flexible film 39 is not formed and is exposed.

When the flexible region Ac is set in this manner, the region on the welded portion 33w of the flexible film 39 is different in thickness, such as being inflated compared with other regions. The nonuniformity of the thickness in this width direction is so slight that it is not visually recognized. The nonuniformity of the thickness difference between the area | region on the weld part 33w of the flexible film 39 and another area | region is a very slight swelling of the weld part 33w of the band 33, or 1st, 2nd drum ( And fluctuations in contact pressure with 34, 35). Very slight swelling of the welded part 33w can be confirmed even after post-processing, such as grinding | polishing, after welding.

As shown in FIG. 3, since the flexible film 39 is formed in the range which extends from one side 33s of the band 33 to the other, it is also formed on the welding part 33w. The weld part 33w has a substantially constant width. The width of the weld portion 33w is about 10 mm even when the band 33 is manufactured with high accuracy. However, depending on the precision of the band 33, the width of the weld part 33w may become nonuniform in the longitudinal direction, or may become larger than 10 mm. This welding part 33w is an area | region formed as a welding bead when welding the side part 33s and the center part 33c in manufacturing the band 33. As shown in FIG. The area | region formed on the weld part 33w among the flexible films 39 is called weld part upper area | region 39w.

However, in FIG. 3, when each part is displayed by the actual ratio, since welding part 33w, the welding part upper region 39w, and the welding part upper region 25w becomes difficult to display, each width | variety of these is made into the band ( 33) The width | variety of the flexible film 39 and the film 25 is exaggerated and drawn.

As shown in FIG. 1, in the flexible device 11, a plurality of ducts 44 for sending dried gas are arranged along the traveling path of the band 33. In each of the ducts 44, a plurality of outlets (not shown) through which the dried gas flows out are formed to face the traveling path of the band 33, respectively. Thereby, when gas is supplied to the duct 44, dry gas is sent from the outlet of the duct 44 toward the casting film 39, and drying of a casting film advances.

The duct 44 is connected to a blower (not shown), respectively. The blower supplies gas to the duct 44. A blower controller (not shown) that independently controls the temperature, humidity, and flow rate of the gas supplied to each of the plurality of ducts 44 is connected to the blower. The gas from the duct 44 is heated warm air, for example, and heats the casting film 39 by this warm air. The temperature of the casting film 39 is adjusted by controlling the temperature and flow rate of the warm air and the temperature control of the first and second drums 34 and 35.

In order to improve the manufacturing speed, the casting film 39 facing the peeling roller 43 is heated by the second drum 35 and the band 33. Moreover, in the flexible position PC, the band 33 is cooled by the 1st drum 34 so that the band 33 may not heat up excessively. For this reason, each drum 34, 35 is temperature-controlled by the thermostat not shown.

After drying the casting film 39 to the extent that the transfer to the first tenter 13 can be made and hardened, the cast film 39 is peeled off from the band 33 in the state containing the solvent 23. The peeling roller 43 is arrange | positioned facing the peeling position which peels the casting film 39 from the band 33. As shown in FIG. As the film 25 is supported by the peeling roller 43, the peeling position PP is kept constant.

The exfoliated cast film 39, that is, the film 25, is guided to the first tenter 13 via the first slitter 12. The first slitter 12 is provided on both sides of the conveyance path of the film 25. The first slitter 12 continuously cuts both edges of the film 25 in the longitudinal direction and cuts off both edges deformed in a wave shape. However, when the 1st slitter 12 is provided as needed, and the deformation of both edges is a range which does not adversely affect the grip by the clip 28 of the 1st tenter 13, 1st slitter In (12), you may send to the 1st tenter 13 as it is, without cutting both sides of the film 25.

The first tenter 13 provides the tension in the width direction (B direction) while supporting the film 25 with the clip 28 and conveying it in the longitudinal direction (A direction), thereby increasing the width of the film 25. Widen The first tenter 13 is divided into a preheating area, a drawing area, and a relaxation area in order from the upstream side. However, there may be no relaxation area.

The first tenter 13 includes a pair of rails (not shown) and a chain (not shown). The rails are provided on both sides of the conveyance path of the film 25. The spacing of these rails is constant in the preheating area, gradually widens in the stretching area toward the downstream, and is constant in the relaxation area. However, the rail spacing of the relaxation area may be gradually narrowed toward the downstream.

The chain spans the prime sprocket and the driven sprocket (not shown) and is guided along the rail. The plurality of clips 28 are attached to the chain at predetermined intervals. By rotation of the prime sprocket, the clip 28 circulates along the rail.

The clip 28 starts the support of the film 25 guided in the vicinity of the inlet of the first tenter 13, moves toward the outlet, and releases the support in the vicinity of the outlet. The clip 28 which release | released support moves to the vicinity of an entrance again, and supports the film 25 newly guided.

The preheating area, the stretching area, and the relaxation area are formed as spaces by the delivery of the drying wind from the duct 29, and there is no clear boundary between them. The duct 29 is provided above the conveyance path of the film 25. The duct 29 has a slit for sending dry air and is supplied from a blower (not shown). The blower sends the drying air adjusted to the predetermined temperature and humidity to the duct 29. The film 25 is dried by the drying wind from the duct 29 while conveying the film 25 with this 1st tenter 13.

The roller drying apparatus 16 is equipped with a temperature controller (not shown). When the atmosphere inside the roller drying apparatus 16 is guided from the inside of the roller drying apparatus 16, a temperature controller adjusts the temperature, humidity, etc. of this gas, and sends it to the inside of the roller drying apparatus 16. . Thereby, temperature, humidity, etc. of the inside of the roller drying apparatus 16 are adjusted. In the roller drying apparatus 16, the film 25 is wound and conveyed by many rollers 30, and the solvent 23 evaporates from the film 25 during this conveyance.

The second tenter 17 has the same structure as the first tenter 13. The duct 32 provided in the 2nd tenter 17 flows out the drying air heated at predetermined temperature from the slit (not shown), and flows toward the film 25. The second tenter 17 extends the film 25. By this stretching, a film 25 having desired optical properties is obtained. The film 25 obtained is used as a retardation film for liquid crystal displays, for example. However, depending on the optical characteristics of the film 25 for manufacturing purposes, the second tenter 17 may not be used.

The second slitter 18 downstream of the second tenter 17 continuously cuts the film 25 in the longitudinal direction. The second slitters 18 are disposed on both sides of the conveyance path of the film 25. As a result, when the film 25 is guided, the second slitter 18 includes respective side portions including support marks by the clips 28 and 31 of the first tenter 13 or the second tenter 17. Ablate. The film 25 which cut out the side part is sent to the winding-up apparatus 19, is wound up in roll shape, and becomes the film roll 27. As shown in FIG.

As mentioned above, after the flexible film 39 is peeled off at the peeling position PP shown by the dashed-dotted line, it is conveyed, and the 1st slitter 12, the 1st tenter 13, the 2nd tenter 17, Various processes are performed by the second slitter 18. By these treatments, the film 25 is tensioned in the A direction or the B direction, or the side end portions in the B direction are cut out. Thus, the film 25 is stretched in the longitudinal direction, dried to shrink in the width direction, or stretched in the width direction until the film 25 is peeled off at the peeling position PP and wound up, or is enlarged. It may be narrowed by temperance.

For this reason, the case where the width | variety of the flexible film 39 and the film 25 differs is common. Correspondingly, the position and the width W39 of the weld zone upper region 39w in the width direction of the flexible film 39, and the position and the width of the weld zone upper region 25w in the width direction of the film 25 ( W25) is usually different from each other. However, when the film 25 obtained in this way is wound up to the core 26 by the winding apparatus 19, the welding part upper region 25w will be located in the fixed position of a core direction, and a black band failure will arise.

In this embodiment, as shown in FIG. 4, BEP is fluctuate | varied by the constant width in the width direction using the function of one part of the band edge position (henceforth BEP) control unit 51 of the flexible apparatus 11. Forces a small amount of meandering. The original purpose of the BEP control unit 51 is to detect the BEP by the BEP sensor 52 to suppress the meandering of the band 33 within a predetermined range, and to the flexible film at a substantially constant position in the width direction of the band 33. Form 39.

The BEP control unit 51 has a BEP sensor 52, a second drum rotary shaft inclined portion 53, and a BEP controller 54. The BEP sensor 52 detects a BEP near the flexible position. The 2nd drum rotation shaft inclination part 53 has the shift mechanism 61 which moves each bearing 60 provided in the both ends of the 2nd drum rotation shaft 35a individually to A direction. By the individual movement of each bearing 60 by this shift mechanism 61, the 2nd drum 35 is the width direction reference line in the horizontal surface containing the 1st drum rotation shaft 34a and the 2nd drum rotation shaft 35a. It is inclined with respect to BL1. According to the angle of inclination θ1 formed by the width direction reference line BL1 and the axial direction CL2 of the inclined second drum rotation shaft 35a, the band 33 moves in the B direction on the first drum 34. .

The BEP sensor 52 always detects BEP, and operates each shift mechanism 61 so that the BEP does not fluctuate and controls the inclination angle θ1 of the second drum 35. Control to support the BEP at a predetermined position is well known meandering prevention control that is generally performed. Specifically, the shift amount 61 is detected by the BEP sensor 52 to detect the shift amount with respect to the BEP target value, and the shift mechanism 61 is inclined so as to tilt the second drum rotating shaft 35a so as to become the BEP target value according to the shift amount. .

FIG. 5 shows the inclination angle θ1 of the second drum rotating shaft 35a and the BEP when the band 33 at the inclination angle θ1 travels a unit length. The unit of the inclination angle θ1 on the horizontal axis is °, and the unit of BEP on the vertical axis is mm. When the inclination angle θ1 of the second drum rotation shaft 35a is an inclination angle θ1 within 0.1 °, it can be seen that the change in BEP is linear (proportional). Therefore, when the shift amount is detected with respect to the BEP target value, the inclination angle θ1 of the second drum rotary shaft 35a corresponding to the shift amount is obtained from the relationship in Fig. 5, and the respective shift mechanisms are set to be the inclination angle θ1. By operating the 61, the deviation can be corrected.

As shown in FIG. 4, in the forced micro meander control, the band 33 in the flexible position PC is used by controlling the change of the inclination angle of the second drum rotating shaft 35a by the BEP control unit 51. Move in the B direction by a certain width. In this embodiment, the fixed width (meander width) is set to approximately 10 mm that is substantially the same as the width W33 in the band width direction of the weld portion 33w.

The BEP controller 54 has a forced meandering amount setting unit 55. The forced meandering amount setting unit 55 calculates the meandering amount in the forced micromeander control based on the meandering width and, for example, a sinusoidal waveform (sine curve). For example, while the band is turned once, the meandering amount for forced meandering determined by the sinusoidal curve of 0 ° to 360 ° is added to the target set value of the BEP controller 54. In the BEP controller 54, the meandering amount is added and meandering control is performed by the corrected target set value. Therefore, forcible trace meandering control is performed in which the width W33 of the weld portion 33w is the amplitude while suppressing the meandering occurring suddenly.

Due to the variation (forced meandering) due to the constant amplitude Am of the band 33, the flexible film 39 is formed on the band 33 meandering with the constant amplitude Am as a result. Thereby, corresponding to the forced trace meander of the band 33, as shown in FIG. 6, the welding part upper area | region 25w on the film 25 also has the same wavelength WL and wave height WH (= 2 * Am). You will meander. However, strictly speaking, the film 25 has a wavelength WL in the flexible film 39 due to expansion and contraction in the A direction and the BEP direction (the width direction of the band 33 and the B direction), or the ablation of both edges. Crest height WH is different.

In FIG. 6, the B direction length (width) is exaggerated and enlarged with respect to the A direction length of the film 25 so that the meandering of the weld part upper region 25w can be known. In reality, the wavelength WL of the forced meandering corresponds to the circumferential length of the band 33. In this way, corresponding to the meandering of the welded portion 33w, the welded upper region 39w of the flexible film 39 formed thereon also meanders in the same manner. Therefore, when this flexible film 39 is dried and wound up to the core as the film 25, it is wound up as the film roll 27 in the state in which the welding part upper area | region 25w of the film 25 meandered at the crest WH. do. For this reason, unlike the conventional one, it is different from the vertical weld line corresponding part on a straight line, and a black band failure does not arise.

In each of the slitters 12 and 18, both edges of the film 25 are cut in a slit shape, and the film 25 is formed to have a constant width. At this time, even if both edges are formed in a sinusoidal shape, for example, by forced trace meandering, both side edges are cut out in a straight line by the slits 12 and 18.

However, even if both edges of the film 25 are formed by the slits 12 and 18 in a straight line shape, the welded area formed on the meandering longitudinal weld line is meandered under the influence of forced trace meandering. have. For this reason, when the film 25 is wound up to the core 26, the welding part upper area | region 25w does not concentrate in the fixed location of the core 26, and a welding part is carried out by the constant vibration width (amplitude) of forced trace meandering. Since the image area 25w is distributed and wound up, black band failure does not occur.

7 shows the transition of the inclination angle of the second drum rotation shaft 35a when the sinusoidal waveform is used as the amount of meandering correction, and the BEP on the first drum 34 of the band 33 corresponding thereto. It shows the trend of. However, in FIG. 7, it is shown as an abnormal state in which meandering does not occur. In reality, meandering occurs unexpectedly in the band 33 due to the uneven distribution of the temperature caused by the drying wind in the band width direction.

8 shows the correspondence relationship between the inclination angle θ1 of the second drum rotary shaft inclination portion 53 when the triangular waveform is used as the amount of meandering correction and the BEP shift amount at the flexible position at this time. It is shown. In the case of this triangular waveform, since the band position fluctuates in a quadratic function, the BEP fluctuates suddenly, or the amplitude of the band position becomes smaller than the amplitude of the inclination angle θ1 compared to the sinusoidal curve. There is a disadvantage.

It is preferable that the period of the displacement with the amplitude due to the forced meandering is not less than two rounds or more than the time when the traveling band 33 turns half a turn. If the period is too short, such as less than half a turn, there is a possibility of damaging the band 33. If the cycle is too long, such as more than two turns, the effect of acylate is reduced, which is undesirable. In the present embodiment, the period of displacement is the time when the band 33 turns one turn. The time when the band 33 turns around can be obtained from the circumferential length of the band 33 and the traveling speed. Therefore, the film roll 27 which has the displacement amount which the position of the welding part upper area | region 25w of the film 25 amplitudes in the width direction on the basis of the length obtained by the time when the band 33 turns one round is obtained. Thereby, generation | occurrence | production of the black line in the film roll 27 is prevented more reliably.

In addition, you may change the amplitude of the displacement in the B direction of the weld part upper region 39w according to the width W39 of the weld part upper region 39w. Specifically, the larger the width W39 of the welded portion region 39w, the larger the amplitude of the displacement in the B direction of the welded portion region 39w. This is especially effective when the weld part 33w is a substantially straight line extending in the longitudinal direction of the band 33. That the welded part 33w is a substantially straight line extending in the longitudinal direction of the band 33 means the case where the amplitude of the welded part 33w in the B direction is within about 2 mm.

Although the case where the polymer component of the dope 24 is used as the cellulose acylate 22 is shown in this embodiment, even if the polymer different from the cellulose acylate 22 is used as the polymer component of the dope 24, this invention It is effective enough. For example, if it is a well-known polymer which can manufacture a film by solution film forming, cyclic polyolefin etc. can be mentioned as a polymer component.

In addition, the cellulose acylate 22 is not particularly limited. The acyl group of the cellulose acylate 22 may be only one type, or may have two or more types of acyl groups. When an acyl group is two or more types, it is preferable that one is an acetyl group. It is preferable that the ratio which esterifies the hydroxyl group of a cellulose with carboxylic acid, ie, the substitution degree of an acyl group, satisfy | fills all in following formula (I)-(III). In the following formulas (I) to (III), A and B represent a degree of substitution of an acyl group, A is a degree of substitution of an acetyl group, and B is a degree of substitution of an acyl group having 3 to 22 carbon atoms. to be.

(I) 2.0? A + B? 3.0

(II) 1.0? A? 3.0

(III) 0≤B≤2.9

It is more preferable that all substitution degrees A + B of an acyl group are 2.20 or more and 2.90 or less, and it is especially preferable that they are 2.40 or more and 2.88 or less. Moreover, it is more preferable that substitution degree B of the acyl group of C3-C22 is 0.30 or more, and it is especially preferable that it is 0.5 or more. Especially, this invention has a big effect especially when cellulose diacetate (DAC) is used as the cellulose acylate 22.

Hereinafter, embodiments of the present invention will be described. However, this invention is not limited to a following example, Each following example is given as an example of this invention. The detail is demonstrated in an Example, and, about the comparative example with respect to this invention, only the conditions different from an Example are shown.

[Example]

The film 25 was manufactured from the dope 24 by the solution film forming facility shown in FIG. The used cellulose acylate 22 is cellulose diacetate (DAC). This film 25 is used as a retardation film for what is called VA (Vertical Alignment) system of LCD. The diameters of the drums 34 and 35 are 2 m.

A band 33 formed of SUS316 was used. The width of each side portion 33s is 150 mm, and the width of the center portion 33c is 2000 mm. The circumferential length of the band 33 is 100 m, and thickness is 1.5 mm. As for the weld part 33w, the amplitude of the sinusoidal meander in the B direction was less than or equal to 2 mm, and was substantially straight in the longitudinal direction of the band 33.

Flexible film 39 while forcibly meandering band 33 in B direction so that weld-side region 39w is displaced in B direction at a displacement of amplitude 10 mm with a period corresponding to 100 m of circumferential length of band 33. Formed. The flexible film 39 is peeled off from the band 33, so that the first slitter 12, the first tenter 13, the roller drying apparatus 16, the second tenter 17, and the second slitter 18 Each process was performed and it wound up by the winding-up apparatus 19, and the film roll 27 was obtained.

When the obtained film roll 27 was observed visually, the black line which extended in the circumferential direction was not confirmed in both sides.

[Comparative Example 1]

The film 25 was wound around the core 26 without displacing the weld zone upper region 39w in the B direction, that is, without reciprocating the band 33 in the B direction. Other than this is the same conditions as Example 1.

When the obtained film roll was visually observed, the black strip | line which extended in the circumferential direction was confirmed on both sides.

Claims (10)

Running an annular metal band spanning the circumferential surface of the pair of drums;
Forcing meandering to displace the band while traveling in a constant amplitude in the width direction;
Forming a flexible film by casting dope dissolved in a solvent into the band;
Peeling the flexible film from the band to dry the film; and
Winding the film into a roll shape;
And,
The band has a central portion and side portions integrally welded to both side ends of the central portion;
And the dope is pliable to the band displaced in the width direction, and the dope is pliable to a width wider than the central portion, so that the flexible film is formed on the central portion and the side portion. The method of claim 1, wherein
The constant amplitude of the said band is more than the width in the flexible film width direction of the area | region on the weld part of the said flexible film formed on the welding part extended in the running direction of the said band, The solution film forming method characterized by the above-mentioned. 3. The method according to claim 1 or 2,
The pair of drums are a first drum and a second drum farther from the dope flexible position than the first drum, and on a plane including a rotation axis of the first drum and a rotation axis of the second drum, the rotation axis of the second drum. Is inclined in the width direction of the band to displace the band in the width direction. 3. The method according to claim 1 or 2,
The inclination angle of the rotating shaft of the second drum is varied by a sine wave or a triangle wave. The method of claim 3, wherein
The inclination angle of the rotating shaft of the second drum is varied by a sine wave or a triangle wave. 3. The method according to claim 1 or 2,
The period of displacement of the band is a solution film forming method, characterized in that the band is more than half a turn time, less than two turns. The method of claim 3, wherein
The period of displacement of the band is a solution film forming method, characterized in that the band is more than half a turn time, less than two turns. The method of claim 3, wherein
The inclination angle of the rotation axis of the second drum is adjusted by using a band edge position control unit that changes the inclination angle of the rotation axis of the second drum to maintain the band edge position at the flexible position with respect to the band of the dope. The solution film forming method characterized by the above-mentioned. 5. The method of claim 4,
The inclination angle of the rotation axis of the second drum is adjusted by using a band edge position control unit that changes the inclination angle of the rotation axis of the second drum to maintain the band edge position at the flexible position with respect to the band of the dope. The solution film forming method characterized by the above-mentioned. First drum and second drum;
An annular metal band rotatably traveling across the first drum and the second drum;
A casting die which casts a dope in which a polymer is dissolved in a solvent on the band including both sides to form a casting film;
A flexible membrane drying unit configured to dry the flexible membrane by evaporating a solvent from the flexible membrane;
A peeling roller separating the flexible film dried in the flexible film drying unit from the band; and
Inclined drum rotation shaft to incline the rotation axis of the second drum to displace the band in a constant amplitude in the width direction of the band
And,
The band has a central portion and a pair of side portions welded to both ends of the central portion,
The second drum is farther from the flexible die than the first drum,
The rotating shaft of the second drum is inclined on a plane including the rotating shaft of the first drum and the rotating shaft of the second drum.

Images