JP2012061842A - Solution film forming method, and casting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To manufacture a long film larger in width and uniform in thickness in a width direction.SOLUTION: An annular band 33 having a center part 33c integrated with a side part 33s by welding is used as a casting support body. The wide center part 33c has a band width Wc used conventionally as the casting support body, and the side part 33s is narrower than the center part 33c in its width Ws. The band 33 is conveyed along a longitudinal direction to be circulated. Dope is casted to form a casting film 39 on the center part 33c and on a welding part 33w. The side part 33s and the welding part 33w are pressed from a casting face side, by a pair of first rollers 52 provided to face the band 33 from a separating position toward a casting position PC, to correct raise of the side part 33s so that the height of a casting face is the same as that of the center part 33c.

Description

  The present invention relates to a solution casting method using an annular band having welds extending in a longitudinal direction on both sides as a casting support, and a casting apparatus including the band.

  With the increase in the screen size of a liquid crystal display (LCD), an optical film used for the LCD is also required to have a large area. The optical film is manufactured in a long length and then cut into a predetermined size so as to correspond to the LCD. Therefore, in order to produce an optical film having a larger area, it is necessary to produce a longer optical film so that the width becomes larger.

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

  A band made of metal is used as a casting support. The width of the film that can be produced is constrained by the width of this band, and a larger width band is required to produce a larger width film. However, until now, only bands with a width of up to about 2 m have been obtained.

  Therefore, in Patent Document 1, by welding a central band that is a central portion in the width direction and a pair of side bands that are each side portion of the band in the longitudinal direction, the width is 2200 mm, which is larger than the conventional one. I'm getting a band.

Korean Patent Publication No. 2009-0110082

  The band proposed in Patent Document 1 is meaningful in that it produces a long optical film having a larger width than conventional bands. However, the band formed by extending the welded portion in the longitudinal direction as in Patent Document 1 has a side region formed from the side band warped and floated more than the central region formed from the central band. As a result, the casting surface (one surface on which the dope is cast) may be high. Thus, when dope is cast on a band whose casting surface is not constant, there is a problem that a film having a uniform thickness cannot be manufactured. For example, if the height of the casting surface is different between the side region and the central region, a film having a uniform thickness in the width direction cannot be produced. A film having a non-uniform thickness has non-uniform optical characteristics such as the direction of the optical axis. However, Patent Document 1 does not disclose a film forming method based on such a problem.

  Therefore, the present invention uses a band having a welded portion extending in the longitudinal direction on the side as a casting support, and a cast film is also formed on the welded portion. Another object of the present invention is to provide a solution casting method and a casting apparatus for producing a long film having a wide width.

  In order to solve the above-mentioned problems, the present invention flows a dope in which a polymer is dissolved in a solvent into an annular metal band that is wound around a peripheral surface of a pair of rollers and conveyed in a longitudinal direction so as to circulate. In a solution casting method in which a cast film is formed by stretching, and the cast film is peeled off from the band and dried to form a film, the band is integrated by welding at a wide central portion and both side ends thereof. It is arranged so as to face the band from the peeling position where the casting film is peeled off to the casting position where the dope is cast, and the longitudinal direction coincides with the width direction of the band. The first roller provided so as to be rotatable allows the welded portion extending in the longitudinal direction of the band and the side portion lifted from the pair of rollers to be pressed from one band surface side where the dope is cast. , Side uplifting And, casting film so formed on the upper weld of the upper and both side central portion, and is configured as characterized by casting the dope.

  It is preferable that the full width region of the band is pressed by the first roller longer than the full width of the band. It is preferable that the first roller having a driving unit and having a resin processed peripheral surface is rotated in the circumferential direction by the driving unit at the same speed as the transport speed of the band.

  The casting film of the one band surface is arranged by a second roller that is arranged so as to face the band from the casting position to the peeling position, and is rotatably provided with the longitudinal direction coinciding with the width direction of the band. It is preferable to suppress the non-casting area that is exposed without being formed.

  (A) The band is conveyed by the pair of rollers rotating in the circumferential direction, and the dope flows out from a casting die provided facing the band on one of the pair of rollers. (B) The band is transported by the pair of rollers rotating in the circumferential direction, and the band from one of the pair of rollers toward the other is supported. It is preferable that the casting position is set on the support roller by flowing out the dope from a casting die supported by a roller and provided facing the band on the support roller.

  In the casting apparatus of the present invention, a pair of rollers and a dope that dissolves a polymer in a solvent are cast around a pair of rollers and a circumferential surface of the pair of rollers to form a casting film. A pair of narrow side portions that are conveyed in the longitudinal direction so as to circulate between the casting position and the peeling position where the casting film is peeled off, and are integrated by welding to the wide central portion and both sides thereof. An annular metal band comprising: a welding portion extending in the longitudinal direction of the band from the peeling position to the casting position; and the pair of rollers. A casting die that flows out the dope so as to form a casting film on the central portion and on the welded portions on both sides, and a first roller that presses the raised side portion to correct the lifting of the side portion. And is characterized by comprising.

  The first roller is preferably longer than the width of the band so as to press the entire width region of the band. It is preferable that the first roller has a driving means and the peripheral surface is processed with resin.

  A second member that is rotatably provided with its longitudinal direction aligned with the width direction of the band, and that presses a non-casting region that is exposed without forming a casting film, out of the band from the casting position toward the peeling position. It is preferable to provide a roller.

  According to the present invention, when a band having a welded portion extending in the longitudinal direction is used as a casting support and a cast film is formed on the welded portion, the thickness is more uniform than in the conventional case. A long film having a wide width can be produced.

It is the schematic of solution casting apparatus. It is a schematic perspective view of the band wound around the roller and the first roller. It is explanatory drawing of the floating of the side part of a band. It is a side view of the 1st embodiment of the present invention using the 1st roller. It is a top view of the 1st embodiment. It is a perspective view of a 1st roller. It is a top view of the 2nd embodiment using a full width press roller. It is a side view of the 3rd embodiment using the 1st roller and the 2nd roller. It is a top view of the 3rd embodiment. It is a side view of the 4th embodiment using a full width press roller. It is a top view of the 4th embodiment. It is explanatory drawing of curvature angle | corner (theta). It is explanatory drawing of the floating part of the welding part of a band, and its vicinity.

  As shown in FIG. 1, the solution casting apparatus 10 includes a casting device 11, a first slitter 12, a first tenter 13, a roller drying device 16, a second tenter 17, a second slitter 18, The winding device 19 is provided in order from the upstream side, and these are connected in series.

  The casting apparatus 11 forms a cellulose acylate film (hereinafter simply referred to as “film”) 27 from a dope 24 in which the cellulose acylate 22 is dissolved in a solvent 23. The first slitter 12 cuts out each side of the film 27. The first tenter 13 proceeds with drying while holding each side of the film 27 with a clip 28 as a holding means. The roller drying device 16 dries while supporting the film 27 with a plurality of rollers 29. The second tenter 17 holds each side portion of the film 27 with a clip 32 as a holding means, and applies a tension in the width direction to the film 27. The second slitter 18 cuts off the holding marks on each side held by the clip 32 of the second tenter 17. The winding device 19 rolls the film 27 around a winding core.

  Each apparatus and the film forming method which comprise the solution casting apparatus 10 are demonstrated below. In the present specification, the solvent content (unit:%) is a value based on the dry weight. Specifically, when the mass of the solvent 23 is x and the mass of the film 27 is y, {x / (Y−x)} × 100.

  The casting apparatus 11 includes a band 33 as a casting support and a pair of rollers 34 and 35 that rotate in the circumferential direction. The band 33 is an endless casting support formed in an annular shape, and is wound around the circumferential surfaces of the rollers 34 and 35. Since the band 33 may be plastically deformed if the diameters of the rollers 34 and 35 are too small, the diameter of the rollers 34 and 35 is preferably 1.5 m or more. At least one of the rollers 34 and 35 is a driving roller having driving means. As the drive roller rotates in the circumferential direction, the band 33 in contact with the circumferential surface is conveyed.

  Above the band 33, a casting die 38 that flows out of the dope 24 is provided. By continuously flowing out the dope 24 from the casting die 38 to the band 33 being conveyed, the dope 24 is cast on the band 33 and a casting film 39 is formed. In the present embodiment shown in FIG. 1, the casting die 38 is provided above the band 33 on one roller 34.

  Regarding the dope 24 from the casting die 38 to the band 33, a so-called bead, a decompression chamber 40 is provided upstream in the traveling direction of the band 33. The decompression chamber 40 sucks the atmosphere in the area upstream of the dope 24 that has flowed out to decompress the area.

  The cast film 39 is hardened to such an extent that it can be conveyed to the first tenter 13, and then peeled off from the band 33 in a state containing the solvent 23. At the time of stripping, the film 27 is supported by a stripping roller (hereinafter referred to as stripping roller) 43, and the stripping position where the casting film 39 is stripped from the band 33 is kept constant. The stripping roller 43 may be a driving roller that includes driving means and rotates in the circumferential direction.

  The casting apparatus 11 is provided with a plurality of ducts 44 for sending out the dried gas along the traveling path of the band 33. Each duct 44 has a plurality of outlets (not shown) through which the dried gas flows out so as to face the traveling path of the band 33. Thereby, dry gas is sent out toward the casting film 39, and the drying of the casting film is promoted.

  The ducts 44 are each connected to a blower (not shown), and the gas supplied from the blower flows out from the outlet. A blower controller (not shown) that independently controls the temperature, humidity, and flow rate of 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, and the casting film 39 is heated by the warm air. The temperature of the casting film 39 is adjusted by controlling the temperature and flow rate of the hot air and controlling the temperatures of the rollers 34 and 35, which will be described later.

  The cast film 39 that has been peeled off, that is, the film 27 is guided to the first tenter 13.

  The first tenter 13 applies a tension in the width direction (hereinafter referred to as the B direction) while holding the film 27 with the clip 28 and transporting the film 27 in the longitudinal direction (hereinafter referred to as the A direction). Increase the width. In the first tenter 13, a preheating area, an extension area, and a relaxation area are formed in this order from the upstream side. 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 installed on both sides of the conveyance path of the film 27, and the pair of rails are arranged at a predetermined interval. This rail interval is constant in the preheating area, gradually increases in the extending area as it goes downstream, and is constant in the relaxation area. In addition, you may make it the rail space | interval of a relaxation area become narrow gradually as it goes downstream.

  The chain is stretched over a driving sprocket and a driven sprocket (not shown), and is attached so as to be movable along the rail. The plurality of clips 28 are attached to the chain at a predetermined interval. As the driving sprocket rotates, the clip 28 circulates along the rail.

  The clip 28 starts holding the guided film 27 in the vicinity of the inlet of the first tenter 13, moves toward the outlet, and releases the holding in the vicinity of the outlet. The clip 28 released from the holding moves again to the vicinity of the entrance, and holds the newly guided film 27.

  The preheating area, the stretching area, and the relaxation area are formed as spaces by sending dry air from the duct 45 and do not have a clear boundary. The duct 45 is provided above the conveyance path of the film 27. The duct 45 has a slit for sending dry air, and is supplied from a blower (not shown). The blower sends dry air adjusted to a predetermined temperature and humidity to the duct 45. The duct 45 is arranged so that the slit faces the conveyance path of the film 27. Each slit has a shape extending in the width direction of the film 27 and is formed at a predetermined interval in the transport direction. The duct 45 may be provided below the transport path of the film 27 or may be provided both above and below the transport path of the film 27.

  While the film 27 is being transported by the first tenter 13, drying is promoted by the drying air from the duct 45, and the width can be changed at a predetermined timing by the clip 28.

  The solvent content of the film 27 in the stretching area is preferably 2% by mass or more and 250% by mass or less, and more preferably 2% by mass or more and 100% by mass or less. The stretching ratio ER1 (= {(width after stretching) / (width before stretching)} × 100) in the stretching treatment is preferably greater than 100% and 140% or less. The temperature of the film 27 in the stretching process is preferably 95 ° C. or higher and 150 ° C. or lower.

  The atmosphere inside the roller drying device 16 is controlled by a temperature controller (not shown) such as temperature and humidity. In the roller drying device 16, the film 27 is wound around a large number of rollers 29 and conveyed, and the solvent 23 evaporates from the film 27 during this conveyance. In the roller drying apparatus 16, it is preferable to perform a drying process until a solvent content rate will be 5 mass% or less.

  When the film 27 coming out from the roller drying device 16 is curled, a curl correcting device (illustrated) for correcting the curl and flattening the film 27 between the roller drying device 16 and the second tenter 17. None) may be provided.

  The second tenter 17 extends the film 27. By this stretching, the film 27 having desired optical properties is obtained. The obtained film 27 can be used, for example, as a retardation film for a liquid crystal display. The second tenter 17 has the same structure as the first tenter 13. The duct 48 provided in the second tenter 17 flows from the slit (not shown) out of the drying air heated to a predetermined temperature and flows toward the film 27.

  The stretching ratio ER2 (= {(width after stretching) / (width before stretching)} × 100) in stretching in the second tenter 17 is preferably greater than 105% and not greater than 200%, and is not less than 110% and not greater than 160. % Or less is more preferable. The solvent content of the film 27 at the start of stretching in the second tenter 17 is preferably 5% by mass or less, and more preferably 3% by mass or less. The temperature of the film 27 in stretching is preferably 100 ° C. or higher and 200 ° C. or lower.

  Depending on the optical characteristics of the film 27 to be manufactured, the second tenter 17 may not be used.

  When the film 27 is guided, the second slitter 18 downstream of the second tenter 17 cuts out the side including the retention marks by the clips 28 and 32 of the first tenter 13 and the second tenter 17. The film 27 with the side portions cut off is sent to the winding device 19 and wound up in a roll shape.

  A cooling device (not shown) may be provided between the second tenter 17 and the second slitter 18 to cool the film 27 from the second tenter 17 and lower the temperature.

  As shown in FIGS. 2 and 3, the band 33 includes a central portion 33c and a pair of side portions 33s provided on both sides of the central portion 33c. The central portion 33c and the side portions 33s are integrally welded. It is a thing. In FIG. 2, the welded portion is denoted by reference numeral 33w. The width Wc of the central portion 33c is wider than the width Ws of the side portion 33s. That is, the central portion 33c is wide and each side portion 33s is narrow. The central portion 33c is formed of a material having a width of approximately 1500 mm or more and 2100 mm or less that has been widely used as a casting support. The side portion 33s is formed of a band member having a width of approximately 50 mm to 500 mm. The width of the band 33 ranges from 2000 mm to 3000 mm. 2 and 3, when the direction A, which is the longitudinal direction of the band 33, is directed upward, the right edge of the band 33 is denoted by reference numeral 33e (R), and the left edge is denoted by reference numeral 33e (L). Attached.

  When the dope 24 comes into contact with the band 33, a casting film 39 is formed on the band 33. The position where the dope 24 starts to contact the band 33 is a position where the casting film 39 starts to be formed, and this position is referred to as a casting position PC in the following description. In the present embodiment, the casting die 38 is disposed so as to face the band 33 wound on the roller 34 so that the casting position PC is on the roller 34. FIG. 2 shows a case where the downstream end of the winding region Ar of the band 33 wound around the roller 34 is the casting position PC.

  The roller 34 includes a tension controller 51. The tension controller 51 displaces the roller 34 by displacing the rotation shaft 34a at the center of the circular cross section of the roller 34 so as to control the tension in the longitudinal direction of the band 33. Let For example, when the tension in the longitudinal direction of the band 33 is increased, the tension controller 51 displaces the roller 34 away from the roller 35, and when the tension is decreased, the tension controller 51 displaces the roller 34 so as to approach the roller 35. Let

  As shown in FIG. 3, when the band 33 is wound around the rollers 34 and 35 (see FIG. 1), the central portion 33c is in contact with the roller 34, but the side portion 33s is warped and floats from the roller 34. The height of the casting surface 33A is higher at the side portion 33s than at the central portion 33c.

The amount of floating of the side portion 33s of the band 33 that is warped and floats from the circumferential surface of the roller 34 increases toward the side edge. The floating amount is a distance from the peripheral surface 34b of the roller 34 to the non-casting surface 33B of the band. When the side portion 33s is warped like the band 33 in the present embodiment, the effect of the present invention is larger as the floating amount J1 at the side edges 33e (L) and 33e (R) is larger, at least 1 mm, That is, when the thickness is 1 mm or more, the present invention is particularly effective. Since the floating amount varies depending on the tension in the longitudinal direction of the band 33, when measuring the floating amount, it is preferable to measure under the same tension as that during casting. Therefore, in this embodiment, since the tension of the band 33 during casting is 60 N / mm ² , the floating amount is measured under a tension of 60 N / mm ² . As shown in the unit N / mm ² , this tension is a value per 1 mm ^{2 of} the cross section along the width direction of the band 33, and is hereinafter referred to as a tension per unit cross sectional area. Therefore, the tension in the entire width region is the product of the tension per unit cross-sectional area, the thickness of the band 33, and the width. The tension per unit cross-sectional area is 60 N / mm ^2. For example, the tension value in the entire width region of the band 33 having a thickness of 1 mm and a width of 2200 mm is 60 (N / mm ² ) × 1 (mm) × 2200 (mm). is there.

  The dope 24 is cast so that the cast film 39 is formed on the central portion 33c and the welded portion 33w. That is, the casting region Ac in which the casting film 39 is formed extends from one side 33s to the other side 33s so as to include one welding part 33w and the other welding part 33w. Both sides of the band 33 are non-casting regions An that are exposed without the casting film 39 being formed.

  Of the cast film 39, the width of the planned product area Ap corresponding to the film 27 that becomes the product through the second slitter 18 is the stretch ratio ER1 in the first tenter 13, the stretch ratio ER2 in the second tenter 17, and The width varies with the first slitter 12 and the width with the second slitter 18.

  The present invention is particularly effective when the product planned area Ap is on the welded portion 33w, and the effect is greater as the floating amount of the product planned area Ap is larger. When the side portion 33s is warped like the band 33 in the present embodiment, the effect of the present invention is greater as the floating amount K at the side edge of the product planned area Ap is larger, and the side edge of the product planned area Ap is larger. The present invention is particularly effective when the floating amount K is greater than 0.1 mm.

  As shown in FIGS. 4 and 5, in the first embodiment of the present invention, the first roller 52 is provided so as to face the band 33 from the peeling position PP (see FIG. 1) to the casting position PC. It is done. In this embodiment, a pair of first rollers 52 facing the welded portion 33 w and the side portion 33 s extending in the longitudinal direction are provided near both side portions of the band 33. The first roller 52 is rotatable in the circumferential direction, and is provided so that the longitudinal direction (which coincides with the rotation axis direction) coincides with the B direction which is the width direction of the band 33.

  The first roller 52 presses the welded portion 33 w and the side portion 33 s from the casting surface 33 </ b> A side and nips between the roller 34. Thereby, the rising of the side portion 33s of the band 33 is corrected, and the height of the casting surface 33A of the side portion 33s is made the same as the height of the casting surface 33A of the central portion 33c. Therefore, when the thickness of the side portion 33s and the central portion 33c is the same, the floating amount J1 at the side edges 33e (L) and 33e (R) becomes 0 (zero), and the side portion 33s moves to the roller 34. Get in touch. The dope 24 is cast so as to have a uniform thickness on the welded portion 33w, the central portion 33c, and the side portion 33s. Thereby, the film 27 with a uniform thickness in the width direction is obtained.

  The floating amount is most preferably 0 (zero). However, from the viewpoint of obtaining the film 27 having a uniform thickness in the width direction, the floating amount does not necessarily become zero, and the floating amount K at the side edge of the planned product area Ap is 0.1 mm or less. Correct it.

  When the decompression chamber 40 is used, the first roller 52 may be provided upstream of the decompression chamber 40 in the transport direction of the band 33.

  The first roller 52 only needs to be rotatably provided, and is more preferably a driving roller that is rotated in the circumferential direction by a driving unit.

  When the first roller 52 is a drive roller, it is preferable to drive the first roller 52 so that it rotates at the same speed as the transport speed of the band 33.

  The first roller 52 includes a shift mechanism 53 and is displaced in the B direction. The shift mechanism 53 has a controller 54, and the controller 54 controls the shift mechanism 53 to adjust the amount of displacement of the first roller 52 in the B direction. Thereby, the area | region which presses the band 33 with the 1st roller 52 is adjusted.

  The first roller 52 is a roller having a smooth peripheral surface. The diameter of the first roller 52 is more preferably in the range of 80 mm to 200 mm.

  When the first roller 52 is a drive roller, it is preferable that the first roller 52 has a resin processed peripheral surface as shown in FIG. That is, the first roller 52 is preferably one in which the peripheral surface of the roller body 52a is covered with the resin layer 52b. Thereby, the area | region which contact | connects the 1st roller 52 among the casting surfaces 33A of the band 33 becomes difficult to be damaged. By preventing the generation of scratches, the casting film 39 having a smooth surface is continuously formed. The resin is a synthetic resin.

  In the second embodiment, as shown in FIG. 7, instead of the pair of first rollers 52, the length is longer than the width W33 of the band 33 (see FIG. 2) and the entire width of the band 33 is suppressed. A pressing roller 57 is used. Similar to the first roller 52, the full width pressing roller 57 is arranged so that the longitudinal direction thereof coincides with the B direction. The full width pressing roller 57 only needs to be rotatably provided, and is more preferably a driving roller that rotates in the circumferential direction.

  Similar to the first roller, the full width pressing roller 57 includes a shift mechanism 53 having a controller 54 and is displaced in the B direction.

  The full width pressing roller 57 is a roller having a smooth peripheral surface. The diameter of the full width pressing roller 57 is more preferably in the range of 80 mm to 200 mm. Similarly to the first roller 52, the full width pressing roller 57 is preferably a resin processed peripheral surface when it is a driving roller. Thereby, the band 30 is hardly damaged.

  In the third embodiment, as shown in FIGS. 8 and 9, in addition to the first roller 52, downstream from the casting position PC in the A direction, that is, the peeling position PP from the casting position PC (see FIG. 1). ) Is provided with a pair of second rollers 61 so as to oppose the band 33 toward the head.

  The second roller 61 is arranged so that the longitudinal direction thereof coincides with the B direction. As shown in FIG. 9, the second roller 61 is provided to face the non-casting region An of the band 33, and presses the side portion 33s from the casting surface 33A side.

  When the casting position PC is at the downstream end of the winding area Ar (see FIG. 2) of the roller 34, as shown in FIGS. 8 and 9, the second roller 61 is downstream of the winding area Ar. To press the side portion 33s. When the casting position PC is upstream of the downstream end of the winding area Ar and the second roller 61 is disposed in the winding area Ar, the second portion 61 is nipped between the roller 34 and the side portion 33s. It is preferable to hold the side portion 33 s with two rollers 61. By using the second roller 61 in addition to the first roller 52, the side portion 33s is pressed both upstream and downstream of the casting position PC, so that the rising of the side portion 33s at the casting position PC is more reliably corrected. can do. Thereby, the thickness of the film 27 in the B direction can be made more uniform.

  When the second roller 61 is pressed against the side portion 33s downstream of the winding area Ar, the second roller 61 and the side portion 33s are not in line contact with each other but are in surface contact with each other. It is preferable to press the side portion 33s. Thereby, the lift is more reliably corrected. However, in the case of such surface contact, it is preferable that the wrap angle (winding center angle) of the side portion 33s of the second roller 61 is suppressed to 7 ° at most. Thereby, plastic deformation of the band 33 is suppressed.

  The second roller 61 includes a shift mechanism 62 and is displaced in the B direction. The shift mechanism 62 is connected to the controller 54, and the controller 54 controls the shift mechanism 62 in addition to the shift mechanism 53. By controlling the shift mechanism 62, the displacement amount of the second roller 61 in the B direction is adjusted. Thereby, the area | region which presses the band 33 with the 2nd roller 61 is adjusted.

  The second roller 61 is a roller having a smooth peripheral surface. The diameter of the second roller 61 is more preferably in the range of 80 mm to 200 mm. The second roller 61 only needs to be rotatably provided, and is more preferably a driving roller that rotates in the circumferential direction. Similarly to the first roller 52, the second roller 61 is preferably a resin processed peripheral surface when it is a drive roller. Thereby, the band 30 is hardly damaged.

  In the above embodiment, the casting die 38 is disposed so that the casting position PC is on the winding region Ar of the band 33 with respect to the roller 34, but the present invention is not limited to this embodiment. For example, as in the fourth embodiment shown in FIGS. 10 and 11, the casting die 38 is placed between the rollers 34, 35 so that the casting position PC is on the band 33 from the roller 34 to the roller 35. It may be arranged. In this case, the support roller 65 is disposed under the band 33 from the roller 34 toward the roller 35, and the casting die 38 is disposed so as to face the band 33 supported from below by the support roller 65. preferable. Thereby, the casting position PC is more reliably held on the band 33 supported by the support roller 65.

  In the fourth embodiment, the same full width pressing roller 57 as that in the second embodiment is arranged upstream of the casting position PC. This is because the full width pressing roller 57 can correct the lifting of the side portion 33 s more reliably than the first roller 52.

  In the fourth embodiment, it is preferable to press the band 33 with the full width pressing roller 57 so that the full width pressing roller 57 and the band 33 are not in line contact with each other but in surface contact. Thereby, the lift is more reliably corrected. However, in the case of surface contact, it is preferable that the wrap angle of the band 33 in the full width pressing roller 57 is suppressed to 7 ° at most. Thereby, plastic deformation of the band 33 is suppressed.

  Also in the fourth embodiment, it is more preferable to dispose the second roller 61 on the downstream side of the casting position. Thereby, the lift is more reliably corrected.

  In the present invention, the length of the outlet 38 a (refer to FIGS. 5, 7, 9, and 11) that is the slit shape of the casting die 38 is longer than the width of the central portion 33 c of the band 33, and the casting film 39. May also be formed on the welded portion 33w and the side portion 33s. However, of the non-casting surface 33B of the side portion 33s, a line segment connecting the position P1 10 mm away from the welded portion 33w and the non-casted surface 33B of the welded portion 33w and the non-casted surface 33B of the central portion 33c It is more preferable to use a band having an angle (hereinafter referred to as “a warp angle θ at a 10 mm position”) smaller than 0.05 °. In addition, “the position 10 mm away from the welded portion 33 w in the non-casting surface 33 B of the side portion 33 s” is specifically specified as follows. As shown in FIG. 12, a position PD is obtained at a distance D = 10 mm on the extension line of the non-casting surface 33 </ b> B of the central portion 33 c from the welded portion 33 w toward the end of the roller 34. The intersection of the perpendicular at this position PD and the non-casting surface 33B of the side portion 33s is obtained. This intersection is a “position of the non-casting surface 33B of the side portion 33s that is 10 mm away from the welded portion 33w”.

  In addition, in order to adjust the temperature of the casting film 39, it is preferable to adjust the temperature of the band 33 with the rollers 34 and 35 (refer FIG. 1). In this case, a controller (not shown) for controlling each peripheral surface temperature of the rollers 34 and 35 to a predetermined temperature is provided.

  The embodiment described above is a case where the band 33 with the side portion 33s warped is used, but the present invention is not limited to this case. For example, when the casting is started, the side portion 33s is not warped, and even if the band 33 is flat, the side portion 33s may gradually warp while the casting is continued. . Even in such a case, the present invention is effective.

  In addition, the band 33 welded in the longitudinal direction may not be warped at the side portion 33s but may be raised at the welded portion 33w on both sides and the vicinity thereof. Specifically, as shown in FIG. 13, it is a case where it floats in a mountain shape so that the welding part 33w and this vicinity may become a top part. Since the welded portion 33w floats so as to be a mountain-shaped top, not only the side portion 33s but also a region close to the welded portion 33w of the central portion 33c floats from the roller 34. In FIG. 13, only the right side portion of the band 33 is shown, and the left side portion is not shown. The right edge 33e (R) of the band may be in contact with the roller 34 as shown in FIG.

  The present invention is also effective when using the band 33 that floats so that the welded portion 33w and the vicinity thereof form the top. In the mode in which the band 33 is floated in a mountain shape, the position where the floating amount is the largest is often the welded portion 33w. Therefore, FIG. 13 shows a mode in which the welded portion 33w is floated the most. The effect of the present invention increases as the floating amount J2 at the position where the floating is the largest is larger. When the non-casting region An is closer to the side edge 33e (R) than the welded portion 33w, the floating amount J2 at the most floating position is the largest in the width direction among the floating amounts in the product planned region Ap. Value. In this case, when J2 is larger than 0.1 mm, it is preferable to correct the lift so that it becomes 0.1 mm or less.

  In addition, when the casting is started, the welded portion 33w and the vicinity thereof are not lifted, and even if the band 33 is flat, the welded portion 33w and the vicinity thereof are gradually lifted while the casting is continued. Sometimes it comes. Even in such a case, the present invention is effective.

  In order to further improve the manufacturing speed, it is preferable that the casting film 39 toward the peeling position PP is heated by the roller 35. On the other hand, it is preferable that the roller 34 on which the band 33 toward the casting position PC is wound and passed is cooled on the circumferential surface so that the band 33 does not excessively rise in temperature. According to the present invention, when the peripheral surface temperature of the rollers 34 and 35 is uniformly controlled in the B direction, the lifting of the band 33 is corrected and brought into contact with the rollers 34 and 35. Therefore, the temperature adjustment by the rollers 34 and 35 is performed. Is more reliable, and the temperature is more surely uniform in the B direction. As a result, there is also an effect that the peeling remaining at the time of foaming or peeling of the cast film 39 on the welded portion 33w or the side portion 33s is more reliably prevented.

  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 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, the present invention is particularly effective when cellulose diacetate (DAC) is used as the cellulose acylate 22.

  Examples of the present invention will be described below. However, the present invention is not limited to the following examples, and the following examples are given as examples of the present invention. Details will be described in the first embodiment, and only the conditions different from the first embodiment will be shown for each of the second and following embodiments and the comparative example for the present invention.

  A film 27 was produced from the dope 24 using the solution casting apparatus shown in FIG. The cellulose acylate 22 used is cellulose diacetate (DAC). This film 27 is used as a retardation film for a so-called LCD VA (Vertical Alignment) system. The diameter of the rollers 34 and 35 is 2 m.

  A band 33 made of SUS316 was used. The width of each side portion 33s is 150 mm, and the width of the central portion 33c is 2000 mm. The band 33 has a length of 80 m and a thickness of 1.5 mm.

The roller 34 was displaced by the tension controller 51 so that the tension per unit cross-sectional area of the band 33 was 60 N / mm ^2, and the tension in the A direction was applied to the band 33. Under this tension application state, the side portion 33 s is warped, and the side portion 33 s is floating from the peripheral surface 34 b of the roller 34. The central portion 33 c was in contact with the peripheral surface 34 b of the roller 34. The floating amount J1 at the side edges 33e (L) and 33e (R) was 1.1 mm, and the floating amount K at the side edge of the planned product area Ap was 0.11 mm.

  As shown in FIGS. 1, 2, 4, and 5, a casting die 38 is arranged so that the casting position PC is at the downstream end of the winding area Ar for the roller 34, and a pair of first rollers 52 was arranged upstream of the casting position PC to hold down the welded portion 33w and the side portion 33s to correct the rising of the side portion 33s. The diameter of the first roller 52 is 100 mm.

  The thickness unevenness in the width direction of the obtained film 27 was an acceptable level. In addition, no peeling of the casting film 39 to the band 33 in peeling was confirmed, and foaming of the casting film 39 was not confirmed over the entire width region as well as the side portion.

  As shown in FIG. 9, the second roller 61 is disposed downstream of the casting position PC, and the side portion 33s of the band 33 guided from the casting position PC is pressed. Other conditions were the same as in Example 1. The diameter of the second roller 61 is 100 mm.

  The uniformity of the thickness of the obtained film 27 in the width direction was even better than that of Example 1 and at an acceptable level. In addition, the remaining peeling of the casting film 39 on the band 33 in peeling was not confirmed, and the foaming of the casting film 39 was not confirmed over the entire width region, and was not confirmed in the side portion.

  As shown in FIG. 7, the first roller 52 upstream of the casting position PC is replaced with the full width pressing roller 57, and the side portion 33s of the band 33 and the welding portion 33w from the peeling position PP toward the casting position PC are provided. It was pressed including the central portion 33c. Other conditions were the same as in Example 1. The diameter of the full width pressing roller 57 is 150 mm.

  The uneven thickness in the width direction of the obtained film 27 was an acceptable level, which was superior to Example 1. In addition, the remaining peeling of the casting film 39 on the band 33 in peeling was not confirmed, and the foaming of the casting film 39 was not confirmed over the entire width region, and was not confirmed in the side portion.

[Comparative Example 1]
The conditions are the same as those in the first embodiment except that the first roller 52 is not used.

  The thickness of the obtained film in the width direction was very uneven and was not acceptable. Moreover, the peeling remainder to the band of the casting film in peeling was confirmed. Furthermore, foaming was confirmed on the side of the cast film.

DESCRIPTION OF SYMBOLS 10 Solution casting apparatus 11 Casting apparatus 24 Dope 27 Film 33 Band 33A Casting surface 33c Center part 33s Side part 33w Welding part 38 Casting die 39 Casting film 52,61 1st roller, 2nd roller 57 Whole area press roller 65 Support roller PC Casting position PP Stripping position

In order to solve the above-mentioned problems, the present invention flows a dope in which a polymer is dissolved in a solvent into an annular metal band that is wound around a peripheral surface of a pair of rollers and conveyed in a longitudinal direction so as to circulate. In a solution casting method in which a cast film is formed by stretching, and the cast film is peeled off from the band and dried to form a film, the band is integrated by welding at a wide central portion and both side ends thereof. It is arranged so as to face the band from the peeling position where the casting film is peeled off to the casting position where the dope is cast, and the longitudinal direction coincides with the width direction of the band. The first roller provided so as to be rotatable allows the welded portion extending in the longitudinal direction of the band and the side portion lifted from the pair of rollers to be pressed from one band surface side where the dope is cast. , Side uplifting And, as the casting film is formed on the upper central portion and on the opposite sides of the weld, and casting the dope, the band between one of the rollers of the first roller and the pair of rollers It is configured to nip and to correct the lifting of the side portion on the one roller . The band is conveyed by the pair of rollers rotating in the circumferential direction, and the dope flows out from a casting die provided facing the band on one of the pair of rollers, The casting position is preferably on the one roller.

The present invention also provides a casting method in which a dope in which a polymer is dissolved in a solvent is cast on an annular metal band that is wound around a peripheral surface of a pair of rollers and conveyed in a longitudinal direction so as to circulate. In the solution casting method in which a film is formed and the cast film is peeled off from the band and dried to form a film, the band is formed by a pair of welds integrated with a wide central portion and both side ends thereof. The narrow side portion is arranged so as to face the band from the peeling position where the casting film is peeled off to the casting position where the dope is cast, and the longitudinal direction is made to coincide with the width direction of the band. The first roller provided rotatably and from the side of one band surface on which the dope is cast, the welded portion extending in the longitudinal direction of the band and the side portion lifted from the pair of rollers. Hold down the side The dope is cast so that the floating is corrected and the cast film is formed on the central portion and the welded portions on both sides, and one of the first roller and the pair of rollers. The welded portion and the side portion are pressed by the first roller so that the band heading from one side to the other is in surface contact. The band is conveyed by the pair of rollers rotating in the circumferential direction, the band from one of the pair of rollers toward the other is supported by a support roller, and is provided facing the band on the support roller. It is preferable that the casting position is on the support roller by allowing the dope to flow out from the casting die.

The lift of the side portion at the casting position is corrected by the first roller. It is preferable that the full width region of the band is pressed by the first roller longer than the full width of the band. It is preferable that the first roller having a driving unit and having a resin processed peripheral surface is rotated in the circumferential direction by the driving unit at the same speed as the transport speed of the band.

Of the one band surface, the second roller is disposed so as to face the band from the casting position to the peeling position, and is rotatably provided with a longitudinal direction coinciding with the width direction of the band. It is preferable to suppress a non-casting region that is exposed without forming the casting film.

In the casting apparatus of the present invention, a pair of rollers and a dope that dissolves a polymer in a solvent are cast around a pair of rollers and a circumferential surface of the pair of rollers to form a casting film. A pair of narrow side portions that are conveyed in the longitudinal direction so as to circulate between the casting position and the peeling position where the casting film is peeled off, and are integrated by welding to the wide central portion and both sides thereof. an annular metal band of, rotatably provided in the width direction of the band so the longitudinal direction one Itasa, the welds extending in the longitudinal direction of the band towards the peeling position to the casting position of the pair A first roller that presses against the side lifted from the roller and corrects the lift of the side, and a flow that flows out the dope so as to form a casting film on the central portion and on the welded portions on both sides. and a rolling die, wherein the first roller, the bar between one of said pair of rollers Is arranged at a position nipping the de is configured as characterized Rukoto.

Further, the casting apparatus of the present invention is a casting position where a dope dissolving a polymer in a solvent is cast around a peripheral surface of the pair of rollers to form a casting film, It is made of an annular metal that is conveyed in the longitudinal direction so as to circulate through the peeling position where the cast film is peeled off, and has a wide central portion and a pair of narrow side portions integrated by welding on both sides thereof. A band, which is rotatably provided with its longitudinal direction coinciding with the width direction of the band, is lifted from the welded portion extending in the longitudinal direction of the band from the peeling position to the casting position and the pair of rollers. A first roller that presses against the side and corrects the lifting of the side, and a flow that flows out the dope so as to form the cast film on the central portion and on the welded portions on both sides. The first roller is one of the pair of rollers. Configured as a feature to be arranged to contact the band and the surface toward the other from.

The first roller corrects the lifting of the side portion at the casting position. The first roller is preferably longer than the width of the band so as to press the entire width region of the band. It is preferable that the first roller has a driving means, and a peripheral surface is processed with a resin. A second member that is rotatably provided with its longitudinal direction aligned with the width direction of the band, and that presses a non-casting region that is exposed without forming a casting film, out of the band from the casting position toward the peeling position. It is preferable to provide a roller.

The present invention also provides a casting method in which a dope in which a polymer is dissolved in a solvent is cast on an annular metal band that is wound around a peripheral surface of a pair of rollers and conveyed in a longitudinal direction so as to circulate. In the solution casting method in which a film is formed and the cast film is peeled off from the band and dried to form a film, the band is formed by a pair of welds integrated with a wide central portion and both side ends thereof. The narrow side portion is arranged so as to face the band from the peeling position where the casting film is peeled off to the casting position where the dope is cast, and the longitudinal direction is made to coincide with the width direction of the band. The first roller provided rotatably and from the side of one band surface on which the dope is cast, the welded portion extending in the longitudinal direction of the band and the side portion lifted from the pair of rollers. Hold down the side Correcting the lift, the flow as rolled film is formed on the upper the welded portions of the upper and both side said central part, casting the dope, going from one of the rollers of the pair of rollers to the other the The welded portion and the side portion are pressed by the first roller so that the band is wound around the first roller at a winding central angle of at most 7 ° . The band is conveyed by the pair of rollers rotating in the circumferential direction, the band from one of the pair of rollers toward the other is supported by a support roller, and is provided facing the band on the support roller. It is preferable that the casting position is on the support roller by allowing the dope to flow out from the casting die.

Further, the casting apparatus of the present invention is a casting position where a dope dissolving a polymer in a solvent is cast around a peripheral surface of the pair of rollers to form a casting film, It is made of an annular metal that is conveyed in the longitudinal direction so as to circulate through the peeling position where the cast film is peeled off, and has a wide central portion and a pair of narrow side portions integrated by welding on both sides thereof. A band, which is rotatably provided with its longitudinal direction coinciding with the width direction of the band, is lifted from the welded portion extending in the longitudinal direction of the band from the peeling position to the casting position and the pair of rollers. A first roller that presses against the side and corrects the lifting of the side, and a flow that flows out the dope so as to form the cast film on the central portion and on the welded portions on both sides. The first roller is one of the pair of rollers. Said band toward the other are arranged as hanging up by the winding central angle greater even 7 ° from configured as characterized.

Claims (10)

A casting film is formed by casting a dope in which a polymer is dissolved in a solvent on an annular metal band that is wound around a peripheral surface of a pair of rollers and is conveyed in a longitudinal direction so as to circulate, In the solution casting method in which the cast film is peeled off from the band and dried to form a film,
The band is composed of a wide central portion and a pair of narrow side portions integrated by welding to both side ends thereof.
The first film is disposed so as to face the band from the peeling position where the casting film is peeled off to the casting position where the dope is cast, and is provided so as to be rotatable with its longitudinal direction aligned with the width direction of the band. From the side of one band surface on which the dope is cast by a roller, the welded part extending in the longitudinal direction of the band and the side part lifted from the pair of rollers are pressed to lift the side part. Correct,
The solution casting method, wherein the dope is cast so that the casting film is formed on the central portion and the welded portions on both sides.   The solution casting method according to claim 1, wherein the entire width region of the band is pressed by the first roller that is longer than the entire width of the band.   The said 1st roller which has a drive means and the peripheral surface was resin-processed is rotated to the circumferential direction by the said drive means at the same speed as the conveyance speed of the said band, The claim 1 or 2 Solution casting method.   Of the one band surface, the second roller is disposed so as to face the band from the casting position to the peeling position, and is rotatably provided with a longitudinal direction coinciding with the width direction of the band. The solution casting method according to claim 1, wherein a non-casting region that is exposed without forming the casting film is suppressed. The band is conveyed by the pair of rollers rotating in the circumferential direction,
The casting position is set on the one roller by allowing the dope to flow out from a casting die provided to face the band on one of the pair of rollers. Item 5. A solution casting method according to any one of Items 1 to 4. The band is conveyed by the pair of rollers rotating in the circumferential direction,
A band from one of the pair of rollers toward the other is supported by a support roller,
5. The casting position is set on the support roller by allowing the dope to flow out from a casting die provided to face the band on the support roller. The solution casting method described. A pair of rollers,
A casting position where a dope dissolving the polymer in a solvent is cast around a circumference of the pair of rollers to form a casting film, and a peeling position where the casting film is peeled off. An annular metal band comprising a pair of narrow side portions that are conveyed in the longitudinal direction so as to circulate and are integrated by welding on both sides of the wide center portion;
The welded portion extending in the longitudinal direction of the band from the peeling position to the casting position and the side portion lifted from the pair of rollers, the longitudinal direction being aligned with the width direction of the band and being freely rotatable. A first roller that presses and corrects the lifting of the side portion;
A casting apparatus comprising: a casting die for discharging the dope so as to form the casting film on the central portion and on the welded portions on both sides.   The casting apparatus according to claim 7, wherein the first roller is longer than the width of the band so as to press the entire width region of the band.   The casting apparatus according to claim 7 or 8, wherein the first roller has a driving means, and a peripheral surface is processed with resin.   A non-casting region that is rotatably provided with its longitudinal direction coinciding with the width direction of the band and is exposed without forming the casting film, of the band heading from the casting position to the peeling position. The casting apparatus according to any one of claims 7 to 9, further comprising a second roller that presses.

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