TW201304874A - Solution casting method and solution casting apparatus - Google Patents

Abstract

A solution casting method and solution casting apparatus are provided. A band (33) is used as a casting support. The band (33) consists of a central member (33c) and side members (33s) which are integrated with each other by welding, and is formed into a ring shape. The central member (33c) is wide, and has a band width Wc which has been conventionally used as that of a casting support. Each of the side members (33s) has a width Ws smaller than the width Wc of the central member (33c). The band (33) is transported in a longitudinal direction thereof in a circulating manner. A dope is cast onto the central member (33c) and welding portions (33w) so as to form a casting film (39). A pair of first rollers (52) is disposed so as to face the band (33) moving from a peeling position to a casting position (PC). The pair of first rollers (52) holds the side members (33s) and the welding portions (33w) from the side of a casting surface to correct rising of the side members (33s), such that a height of the casting surface becomes the same as that of the central member (33c).

Description

Solution film forming method and casting device

The present invention relates to a solution film forming method in which an endless belt having a welded portion extending in a longitudinal direction on both sides is used as a casting support, and a casting device including the belt.

With the large screen of a liquid crystal display (LCD), a large area is required for an optical film for an LCD. After the optical film is formed into a shape, it is cut into a predetermined size in order to correspond to the LCD. Therefore, in order to manufacture a larger-area optical film, it is necessary to manufacture the elongated optical film in such a manner that the width becomes wider.

As a representative production method of the elongated optical film, there is a continuous method of forming a solution film. It is known that in a continuous method of forming a solution, a dope in which a polymer is dissolved in a solvent flows on a traveling casting support and is cast. The solution film forming method is a method of producing a film by peeling a cast film which is cast into a film form from a casting support, that is, a cast film, and drying it.

As a user of the casting support, there is a belt made of metal. The width of the film that can be manufactured is limited by the width of the tape, and a wider tape is required to make a wider film. However, only belts having a width of up to about 2 m have been obtained so far.

Therefore, in the Korean Patent Laid-Open Publication No. 2009-0110082, the center belt which is the center portion in the width direction and the pair of side belts which are the side portions of the belt are welded in the longitudinal direction, thereby obtaining This width is 2200mm, which is wider than ever.

The tape proposed in Korean Patent Laid-Open Publication No. 2009-0110082 is meaningful in terms of manufacturing an elongated optical film having a wider width than conventional ones. However, the belt formed by the welded portion extending in the longitudinal direction as in the Korean Patent Laid-Open Publication No. 2009-0110082 may be lifted by the side portion formed by the side belt and floated from the central portion formed by the center belt. The casting surface (the surface of one of the periods in which the dope is cast) becomes high. As described above, if the dope is cast on the belt having a non-uniform height of the casting surface, there is a problem that a film having a uniform thickness cannot be produced. For example, if the heights of the casting faces in the side region and the central portion are different, it is impossible to produce a film having a uniform thickness in the width direction. The film having a non-uniform thickness causes uneven optical characteristics such as the direction of the optical axis. However, Korean Patent Publication No. 2009-0110082 does not disclose a film forming method according to such a problem.

Therefore, an object of the present invention is to provide a belt having a welded portion extending in the longitudinal direction and a side portion as a casting support, and when a cast film is formed on the welded portion, the thickness is uniform in the width direction. A film forming method and a casting device for a long film having a wider width than before.

The present invention is a solution film forming method in which a dope obtained by dissolving a polymer in a solvent is cast on a metal tape to form a cast film, and the cast film is peeled off from the tape and dried. In order to solve the above problems, the solution film forming method of the present invention includes a tape preparation step, a first extrusion step, a cast film formation step, a peeling step, and a drying step. The tape preparation step prepares the aforementioned belt in an annular shape composed of a wide central portion and a pair of narrow side portions. The pair of side portions are integrated with both side ends of the center portion by welding. The belt is conveyed in the longitudinal direction so as to be wound around the circumferential surface of the pair of rolls and circulated. In the first pressing step, the welded portion extending in the longitudinal direction of the belt and the side portion floating from the pair of rollers are pressed by the first roller, and the floating of the side portion is corrected. The first roller is disposed opposite to the belt from the peeling position toward the casting position. The peeling position is a position at which the casting film is peeled off. The aforementioned casting position is a position at which the dope is cast. The first roller is equipped such that the longitudinal direction thereof is rotatably aligned with the width direction of the belt. The first roller presses the welded portion and the side portion from a belt surface side on which one of the dope is cast. The cast film forming step casts the above dope to form the above cast film. The dope is cast in such a manner that the cast film is formed on the center portion and the welded portions on both sides. The peeling step peels off the aforementioned cast film from the aforementioned tape. The above-described cast film which is peeled off is dried as a film.

It is preferred that the entire width of the belt is pressed by the first roller longer than the full width of the belt.

It is preferable that the first roller which is processed by resin in the circumferential direction and has a driving means by the above-described driving means at the same speed as the conveying speed of the belt is preferable.

The solution film forming method of the present invention further preferably has a second pressing step. In the second pressing step, the non-casting region exposed by the formation of the casting film is not formed by the second roller. The second roller is disposed to face the belt from the casting position toward the peeling position. The second roller is equipped such that the longitudinal direction thereof is rotatably aligned with the width direction of the belt.

The solution film forming method of the present invention preferably transfers the belt by the pair of rolls that are rotated in the circumferential direction and is preferably the following (1) or (2). (1) The casting solution is placed on the one of the rolls by flowing out the dope from a casting die disposed opposite to the belt on one of the pair of rolls. (2) supporting the belt from one of the pair of rollers toward the other by the supporting roller, and flowing the distillate from the casting die disposed opposite to the belt on the supporting roller, thereby causing the casting The position is on the aforementioned support roller.

The casting device of the present invention comprises a pair of rolls, a metal belt, a first roll, and a casting die. The aforementioned belt is composed of a wide central portion and a pair of narrow sides. The pair of side portions are integrated with both side portions of the center portion by welding. The ring-shaped belt is conveyed in the longitudinal direction so as to be wound around the circumferential surface of the pair of rolls and to circulate the casting position and the peeling position. The casting position is a position at which a casting solution in which a polymer is dissolved in a casting solvent to form a casting film. The peeling position is a position at which the casting film is peeled off. The first roller presses the welded portion that extends in the longitudinal direction of the belt and the side portion that floats from the pair of rollers, and corrects the floating of the side portion. The first roller presses the welded portion and the side portion of the belt from the peeling position toward the casting position. The first roller is equipped such that the longitudinal direction thereof is rotatably aligned with the width direction of the belt. The casting die flows out of the aforementioned dope. In the casting die, the casting film is formed on the center portion and the welded portions on both sides.

In the casting device, it is preferable that the first roll is longer than the width of the belt so as to press the entire width of the belt.

The first roller has a driving means, and the peripheral surface is preferably processed by a resin.

It is preferable that the casting device further includes a second roller. The second roller presses the non-casting region where the casting film is not formed in the belt from the casting position toward the peeling position. The second roller is equipped such that the longitudinal direction thereof is rotatably aligned with the width direction of the belt.

According to the invention, the belt having the welded portion extending in the longitudinal direction is used as the casting support, and when the cast film is formed on the welded portion, the width in the width direction can be made wider than in the past. Long film.

As shown in Fig. 1, the solution film forming apparatus 10 includes a casting device 11, a first slitter 12, a first tenter 13, a roll drying device 16, a second tenter 17, and a second from the upstream side. The slitter 18 and the take-up device 19 are connected in series.

The casting device 11 forms a cellulose vapor film (hereinafter, simply referred to as "film") 27 from the dope 24 in which the cellulose halide 22 is dissolved in the solvent 23. The first slitter 12 cuts out the side portions of the film 27. The first tenter 13 holds the side portions of the film 27 by the clips 28 as holding means, and simultaneously dries the film 27. The roll drying device 16 supports the film 27 by a plurality of rolls 29 while drying. The second tenter 17 holds the side portions of the film 27 by the clips 32 as holding means, and applies tension in the width direction to the film 27. The second slitter 18 cuts the holding traces of the respective side portions held by the clips 32 of the second tenter 17. The winding device 19 winds the film 27 around the winding core and forms a roll.

Hereinafter, each device and film forming method constituting the solution film forming apparatus 10 will be described. Further, in the present specification, the solvent content rate (unit: %) is a value based on the dry amount. The solvent content rate (unit: %) in the present specification is specifically a value obtained by using {x/(y-x)}×100 when the mass of the solvent 23 is x and the mass of the film 27 is y.

The casting device 11 is provided with a belt 33 as a casting support and a pair of rollers 34 and 35 which are rotated in the circumferential direction. The belt 33 is an endless casting support formed into a ring shape and wound around the circumferential surface of the roller 34 and the roller 35. If the diameter of the rolls 34 and 35 is too small, the belt 33 may be plastically deformed. Therefore, the diameter of the rolls 34 and 35 is preferably 1.5 m or more. At least one of the rollers 34, 35 serves as a drive roller having a driving means. The belt 33 is brought into contact with the circumferential surface by the rotation of the driving roller in the circumferential direction.

A casting die 38 that flows out of the dope 24 is provided above the belt 33. The dope 24 is continuously discharged from the casting die 38 to the conveyed belt 33, whereby the dope 24 is cast on the belt 33 and the casting film 39 is formed. In the embodiment shown in Fig. 1, the casting die 38 is disposed above the belt 33 on one of the rollers 34.

Regarding the dope 24 of the casting die 38 to the belt 33, that is, the liquid bead, the decompression chamber 40 is provided upstream of the traveling direction of the belt 33. The decompression chamber 40 sucks the atmosphere of the upstream side region of the concentrated liquid 24 that has flowed out and depressurizes the aforementioned region.

The casting film 39 is fixed to the extent that it can be conveyed to the first tenter 13, and then peeled off from the belt 33 in a state containing the solvent 23. At the time of peeling, the film 27 is supported by a peeling roller (hereinafter referred to as a peeling roller) 43, and the peeling position PP at which the casting film 39 is peeled off from the belt 33 is kept constant. The peeling roller 43 may be a driving roller that includes a driving means and rotates in the circumferential direction.

A plurality of conduits 44 for delivering the dried gas are arranged in the casting device 11 along the path of the belt 33. Each of the ducts 44 is opposed to the traveling path of the belt 33, and is formed with a plurality of outlets (not shown) through which the dried gas flows. Thereby, the drying gas is sent toward the casting film 39 and the drying of the casting film is promoted.

The ducts 44 are respectively 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 the gas supplied to the plurality of conduits 44 is connected to the blower. The gas from the conduit 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 the control of the temperature and flow rate of the warm air and the temperature control of the rolls 34 and 35 which will be described later.

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

The first tenter 13 holds the film 27 by the clip 28 and conveys it in the longitudinal direction (hereinafter referred to as the A direction) while imparting tension in the width direction (hereinafter referred to as the B direction) and expanding the width of the film 27. In the first tenter 13, a preheating zone, a stretching zone, and a relaxation zone are formed in this order from the upstream side. In addition, the relaxation zone can also be omitted.

The first tenter 13 includes a pair of guide rails (not shown) and a chain (not shown). The guide rails are disposed on both sides of the conveying path of the film 27, and the pair of guide rails are separately disposed at predetermined intervals. The rail spacing is constant in the preheating zone, gradually widening towards the downstream in the stretch zone, and constant in the slack zone. In addition, the rail spacing of the slack zone may taper as it goes downstream.

The chain is hung around the drive sprocket and the driven sprocket (not shown) and is movably mounted along the guide rail. A plurality of clips 28 are attached to the chain at predetermined intervals. The clip 28 is cyclically moved along the guide rail by the rotation of the drive sprocket.

The clip 28 starts to hold the guided film 27 near the entrance of the first tenter 13, and moves toward the exit, and releases the hold near the exit. The clip 28, which has been released, moves again toward the vicinity of the entrance, holding the film 27 that has been re-guided.

The preheating zone, the stretching zone, and the relaxation zone are the space formers by the delivery of the dry wind from the duct 45, and there is no clear boundary. The duct 45 is disposed above the transport path of the membrane 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 or humidity to the duct 45. The duct 45 is disposed such that the slit faces the transport path of the film 27. Each of the slits has a shape that extends long in the width direction of the film 27, and is formed at a predetermined interval from each other in the conveying direction. Further, the ducts 45 may be provided below the transport path of the film 27, or may be provided above and below the transport path of the film 27, respectively.

In the first tenter 13, the film 27 is conveyed while being dried by the dry air from the duct 45, and the width is changed by the clip 28 at a predetermined timing.

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

The internal atmosphere of the roll drying device 16 is adjusted by temperature, humidity, and the like by a thermostat (not shown). In the roll drying device 16, the film 27 is wound around a plurality of rolls 29 for transport, and the solvent 23 evaporates from the film 27 during the transfer. In the roll drying device 16, the drying process is carried out until the solvent content is 5 mass% or less.

Further, when the film 27 fed from the roll drying device 16 is curled, a curl correcting device (not shown) for correcting the curl and flattening the film 27 may be provided between the roll drying device 16 and the second tenter 17.

The second tenter 17 stretches the film 27. By this stretching, the film 27 having the desired optical characteristics 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 configuration as the first tenter 13. Further, the duct 48 provided in the second tenter 17 flows out of the slit (not shown) to dry air heated to a predetermined temperature, and flows toward the film 27.

The stretching ratio ER2 (={(width after stretching)/(width before stretching)}×100) in the second tenter 17 is more than 105% and 200% or less is preferable, 110 More than 160% of the above 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, more preferably 3% by mass or less. The temperature of the film 27 at the time of stretching is preferably 100 ° C or more and 200 ° C or less.

The second tenter 17 may be omitted depending on the optical characteristics of the film 27 for the purpose of manufacture.

When the film 27 is guided, the second slitter 18 downstream of the second tenter 17 cuts off the holding marks generated by the respective clips 28, 32 of the first tenter 13 or the second tenter 17. Side. The film 27 on which the side portion is cut off is sent to the take-up device 19 and taken 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 cool it.

As shown in FIGS. 2 and 3, the belt 33 is composed of a central portion 33c and a pair of side portions 33s provided on both sides of the central portion 33c. The belt 33 is welded integrally by the central portion 33c and the side portion 33s. In Fig. 2, a symbol 33w is attached to the welded portion. 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 center portion 33c is formed by a conventionally used as a casting support and has a width of approximately 1500 mm or more and 2100 mm or less. The side portion 33s is formed of a belt member having a width of approximately 50 mm or more and 500 mm or less. The width of the belt 33 is in the range of 2000 mm or more and 3000 mm or less. Further, in the second and third figures, when the direction A of the longitudinal direction of the belt 33 is directed upward, the symbol 33e (R) is attached to the right edge of the belt 33, and the symbol 33e (L) is attached to the left edge. .

If the dope 24 comes into contact with the belt 33, a casting film 39 is formed on the belt 33. Thus, the position at which the dope 24 comes into contact with the belt 33 is a position at which the casting film 39 is started 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 opposite to the belt 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 belt 33 wound around the roller 34 is the casting position PC.

The roller 34 is provided with a tension controller 51. The tension controller 51 displaces the roller 34 by displacing the rotating shaft 34a located at the center of the circular cross section of the roller 34. Thereby, the tension controller 51 controls the tension in the longitudinal direction of the belt 33. The tension controller 51 displaces the roller 34 in a direction away from the roller 35, for example, when the tension in the longitudinal direction of the belt 33 is increased. The tension controller 51 displaces the roller 34 closer to the roller 35, for example, when the tension in the longitudinal direction of the belt 33 is lowered.

As shown in Fig. 3, the belt 33 is in contact with the roller 34 in a state where the belt 33 is wound around the rollers 34 and 35 (refer to Fig. 1). However, the side portion 33s is lifted up and floats from the roller 34, and the side portion 33s is higher than the central portion 33c in terms of the height of the casting surface 33A.

The side portion 33s of the belt 33 which is lifted up and floats from the circumferential surface of the roller 34 has an amount of floating which increases toward the side edge. The amount of floating means the distance from the circumferential surface 34b of the roller 34 to the non-casting surface 33B of the belt. When the side portion 33s such as the belt 33 in the present embodiment is lifted up, the larger the floating amount J1 on the side edges 33e (L) and 33e (R), the greater the effect of the present invention, and at least 1 mm, that is, 1 mm or more. The effect of the present invention is particularly large. Further, the amount of floating changes depending on the tension in the longitudinal direction of the belt 33. Therefore, when measuring the amount of floating, it is preferable to carry out measurement based on the tension under the same conditions as in the casting period. In the present embodiment, since the tension of the belt 33 during the casting is 60 N/mm ² , the amount of floating is measured under a tension of 60 N/mm ² . As shown in the unit N/mm ² , the tension is a value of a cross section per 1 mm ² in the width direction of the belt 33, so it is hereinafter referred to as a tension per unit sectional area. Therefore, the tension in the full width domain becomes the product of the tension per unit sectional area, the thickness and the width of the belt 33. The tension per unit sectional area is 60 N/mm ² , for example, the tension value in the full width of the belt 33 having a thickness of 1 mm and a width of 2200 mm is 60 (N/mm ² ) × 1 (mm) × 2200 (mm).

The dope 24 is cast in such a manner that the casting film 39 is formed on the center portion 33c and the welded portion 33w. That is, the casting region Ac forming the casting film 39 passes through one of the side portions 33s to the other side portion 33s so as to include one of the welded portions 33w and the other welded portion 33w. Both sides of the belt 33 are non-casting areas An exposed without forming the casting film 39.

The width of the product predetermined area Ap corresponding to the film 27 which becomes the product by the second slitter 18 in the casting film 39 is respectively according to the stretching ratio ER1 in the first tenter 13 and the second tenter 17 The elongation ratio ER2 and the width cut by the first slitter 12 are changed by the width of the second slitter 18.

The present invention is particularly effective when the product predetermined area Ap is located on the welded portion 33w, and the larger the amount of floating of the product predetermined area Ap, the greater the effect. When the side portion 33s such as the belt 33 in the present embodiment is lifted up, the larger the floating amount K of the product predetermined region Ap on the side edge, the greater the effect of the present invention, when the product predetermined region Ap floats on the side edge. When the amount K is larger than 0.1 mm, the effect of the present invention is particularly large.

As shown in Fig. 4 and Fig. 5, in the first embodiment of the present invention, the first roller 52 is opposed to the belt 33 from the peeling position PP (refer to Fig. 1) toward the casting position PC. Equipped. In this embodiment, a pair of first rolls 52 that face the welded portion 33w and the side portion 33s extending in the longitudinal direction are provided in the vicinity of both side portions of the belt 33. The first roller 52 is rotatable in the circumferential direction, and is provided with a longitudinal direction (consistent with the direction of the rotation axis) to coincide with the width direction of the belt 33, that is, the B direction.

The first roller 52 presses the welded portion 33w and the side portion 33s from the side of the casting surface 33A and is sandwiched between the roller 34 and the roller 34. Thereby, the floating of the side portion 33s of the belt 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 center portion 33c. Thereby, when the thickness of the side portion 33s and the center portion 33c are the same, the floating amount J1 on the side edges 33e (L), 33e (R) becomes 0 (zero), and the side portion 33s comes into contact with the roller 34. By correcting the floating, 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 having a uniform thickness in the width direction can be obtained.

In addition, it is preferable that the floating amount is 0 (zero). However, in the viewpoint of obtaining the film 27 having a uniform thickness in the width direction, the amount of floating is not necessarily zero, and the floating amount K of the product predetermined region Ap on the side edge may be corrected to float.

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

The first roller 52 is rotatably provided, and is preferably a driving roller that is rotated in the circumferential direction by a driving means.

When the first roller 52 is a driving roller, it is preferable to drive the first roller 52 so as to rotate at the same speed as the conveying speed of the belt 33.

The first roller 52 is provided with the displacement mechanism 53 and is displaced in the B direction. The displacement mechanism 53 has a controller 54. The controller 54 controls the displacement mechanism 53 and adjusts the amount of displacement of the first roller 52 in the B direction. Thereby, the region where the belt 33 is pressed by the first roller 52 is adjusted.

The first roller 52 is a roller whose circumferential surface is smooth. The diameter of the first roller 52 is more preferably in the range of 80 mm or more and 200 mm or less.

When the first roller 52 is a driving roller, as shown in Fig. 6, the first roller 52 is preferably a resin surface. That is, it is preferable that the first roller 52 is such that the circumferential surface of the roller body 52a is covered with the resin layer 52b. Thereby, the region of the casting surface 33A of the belt 33 that is in contact with the first roller 52 is not easily scratched. By preventing the occurrence of scratches, the casting film 39 having a smooth surface is continuously formed. Further, the resin means a synthetic resin.

As shown in Fig. 7, in the second embodiment, a full width pressing roller 57 is used instead of the pair of first rollers 52. The length of the full width pressing roller 57 is longer than the width W33 of the belt 33 (refer to Fig. 2), and the entire width of the belt 33 is pressed. The full-width pressing roller 57 is the same as the first roller 52, and the growth direction is aligned with the B direction. The full width pressing roller 57 is rotatably provided, and is preferably a driving roller that rotates in the circumferential direction.

Similarly to the first roller 52, the full-width pressing roller 57 is provided with a displacement mechanism 53 having a controller 54 and is displaced in the B direction.

The full width pressing roller 57 is a roller whose circumferential surface is smooth. The diameter of the full width pressing roller 57 is more preferably in the range of 80 mm or more and 200 mm or less. The full-width pressing roller 57 is also the same as the first roller 52, and the peripheral surface is preferably processed by resin when it is a driving roller. Thereby, the belt 30 is not easily scratched.

As shown in Figs. 8 and 9, in the third embodiment, in addition to the first roller 52, it is further downstream from the casting position PC in the direction A, that is, from the casting position PC. The pair of second rollers 61 are provided in such a manner that the belt 33 facing the peeling position PP (refer to FIG. 1) is opposed to each other.

The second roller 61 is disposed such that the growth direction coincides with the B direction. As shown in Fig. 9, the second roller 61 is disposed to face the non-casting region An of the belt 33, and press the side portion 33s from the side of the casting surface 33A.

As shown in FIGS. 8 and 9, when the casting position PC is located at the downstream end of the winding region Ar (refer to FIG. 2) on the roller 34, it is downstream of the winding region Ar by the second The roller 61 presses the side portion 33s. When the casting position PC is upstream of the downstream end of the winding region Ar and the second roller 61 is disposed in the winding region Ar, the second roller 61 sandwiches the side portion 33s between the roller 34 and the roller 34. The manner of squeezing the side portions 33s is preferred. By using the second roller 61 in addition to the first roller 52, the side portions 33s are pressed both upstream and downstream of the casting position PC, so that the side portions 33s can be more reliably corrected at the casting position PC. The float. Thereby, the thickness of the film 27 in the B direction can be made more uniform.

When the second roller 61 presses the side portion 33s downstream of the winding region Ar, the second roller 61 and the side portion 33s are pressed in contact with each other so that the second roller 61 and the side portion 33s are in surface contact with each other. Preferably. Thereby, the floating can be corrected more reliably. However, when the surface contact is made in this manner, it is preferable that the wrap angle (winding center angle) of the side portion 33s on the second roller 61 is suppressed to a maximum of 7°. Thereby, the plastic deformation of the belt 33 is suppressed.

The second roller 61 is provided with the displacement mechanism 62 and is displaced in the B direction. The displacement mechanism 62 is coupled to a controller 54, which controls the displacement mechanism 62 in addition to the displacement mechanism 53. The amount of displacement of the second roller 61 in the B direction is adjusted by the control of the displacement mechanism 62. Thereby, the area where the belt 33 is pressed by the second roller 61 is adjusted.

The second roller 61 is a roller whose circumferential surface is smooth. The diameter of the second roller 61 is more preferably in the range of 80 mm or more and 200 mm or less. The second roller 61 may be rotatably provided, and is preferably a driving roller that rotates in the circumferential direction. The second roller 61 is also the same as the first roller 52. When it is a driving roller, the circumferential surface is preferably processed by a resin. Thereby, the belt 30 is not easily scratched.

In the above embodiment, the casting die 38 is disposed such that the casting position PC is located on the winding region Ar of the belt 33 with respect to the roller 34. However, the present invention is not limited to this aspect. For example, as in the fourth embodiment shown in FIGS. 10 and 11, a casting die 38 may be disposed between the two rollers 34, 35 so that the casting position PC is located from the roller 34 toward the roller 35. Belt 33. At this time, the support roller 65 is disposed below the belt 33 from the roller 34 toward the roller 35, and the casting die 38 is preferably disposed to face the belt 33 supported by the support roller 65 from below. Thereby, the casting position PC is more reliably held on the belt 33 supported by the support roller 65.

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

In the fourth embodiment, it is preferable that the full width pressing roller 57 and the belt 33 are pressed by the full width pressing roller 57 so as not to be in line contact with each other but in surface contact. This makes it easier to correct the float. However, when it is set to face contact, it is preferable that the wrap angle of the belt 33 on the full width pressing roller 57 is suppressed to a maximum of 7°. Thereby, plastic deformation of the belt 33 can be suppressed.

In the fourth embodiment, it is more preferable to arrange the second roller 61 on the downstream side of the casting position PC. Thereby, the floating is corrected more reliably.

In the present invention, the length of the slit-shaped outflow port 38a (refer to FIG. 5, FIG. 7, FIG. 9, and FIG. 11) of the casting die 38 is longer than the width of the central portion 33c of the belt 33, and the cast film 39 is formed not only on the center portion 33c but also on the welded portion 33w and the side portion 33s. However, in the non-casting surface 33B of the connecting side portion 33s, the angle formed by the line portion P1 away from the welded portion 33w and the non-casting surface 33B of the welded portion 33w and the non-casting surface 33B of the central portion 33c are formed. A belt (hereinafter referred to as "warpage angle θ" at a position of 10 mm) of less than 0.05 is more preferable. In addition, "the position of the non-casting surface 33B of the side portion 33s which is apart from the welded portion 33w by 10 mm" is specifically as follows. As shown in Fig. 12, a position PD having a distance D = 10 mm from the welded portion 33w toward the end portion side of the roller 34 and on the extension line of the non-casting surface 33B of the center portion 33c is obtained. The intersection of the perpendicular line at the position PD and the non-casting surface 33B of the side portion 33s is obtained. This intersection is "the position of the non-casting surface 33B of the side portion 33s which is away from the welded portion 33w by 10 mm".

Further, in order to adjust the temperature of the casting film 39, it is preferable to adjust the temperature of the belt 33 by the rolls 34, 35 (refer to Fig. 1). At this time, a controller (not shown) that controls the temperature of each circumferential surface of the rolls 34 and 35 to a predetermined temperature is provided.

The embodiment shown above is the case where the belt 33 is lifted by the side portion 33s, but the present invention is not limited to this case. For example, even if the side portion 33s is not lifted and the belt 33 is flat at the time of starting the casting, the flow delay side portion 33s may be gradually lifted. Even in this case, the present invention is effective.

Further, the belt 33 welded in the longitudinal direction is not the one in which the side portions 33s are lifted, and the welded portions 33w on both sides and the vicinity thereof may be lifted. Specifically, as shown in Fig. 13, the welded portion 33w and its vicinity may be floated in a mountain shape like the top portion. Since the welded portion 33w floats so as to become a mountain-like top portion, not only the side portion 33s but also the region of the central portion 33c close to the welded portion 33w floats from the roller 34. In addition, in Fig. 13, only the right side portion of the belt 33 is shown, and the left side portion is omitted. The right side edge 33e (R) of the belt may come into contact with the roller 34 as shown in Fig. 13, and may float from the roller 34.

The present invention is effective even when the belt 33 which is floated so as to be in the vicinity of the welded portion 33w and the like is used. In the case where the belt 33 floats up into a mountain shape, the position where the amount of floating is the largest is mostly the welded portion 33w. Therefore, Fig. 13 shows a state in which the welded portion 33w is maximally floated. The larger the floating amount J2 at the position where the maximum float is, the larger the effect of the present invention. When the non-casting area An is closer to the side edge 33e (R) side than the welded portion 33w, the floating amount J2 at the position where the maximum floating position becomes the maximum value in the width direction of the floating amount in the predetermined area Ap of the product . At this time, when J2 is more than 0.1 mm, it is preferable to correct the floating so as to be 0.1 mm or less.

Further, even if the welded portion 33w and the vicinity are not floated and the belt 33 is flat at the time of starting the casting, there is a case where the flow-welding portion 33w is continued and the vicinity is gradually floated. Even in this case, the present invention is effective.

In order to further increase the manufacturing speed, the casting film 39 toward the peeling position PP is preferably heated by the roller 35. On the other hand, it is preferable to wind the circumferential surface so that the belt 33 passes through the belt 34 passing through the belt 33 at the casting position PC so that the belt 33 does not excessively rise. According to the present invention, when the circumferential temperature of the rolls 34, 35 is uniformly controlled in the B direction, the correcting belt 33 floats and comes into contact with the rolls 34, 35, so that the temperature adjustment based on the rolls 34, 35 becomes It is more reliable and becomes more uniform in the B direction. Thereby, it is possible to more reliably prevent the effect of the foaming or peeling of the casting film 39 on the welded portion 33w or the side portion 33s.

The cellulose halide 22 is not particularly limited. The thiol group of the cellulose halide 22 may be only one type, or may have two or more types of fluorenyl groups. When the fluorenyl group is two or more kinds, one of them is preferably an acetamino group. It is preferred that all of the following formulas (I) to (III) are satisfied by the ratio of the hydroxyl group of the carboxylated cellulose to the carboxyl group, that is, the degree of substitution of the mercapto group. Further, in the following formulas (I) to (III), A and B represent the degree of substitution of a mercapto group, A is a degree of substitution of an ethylidene group, and B is a degree of substitution of a mercapto group having 3 to 22 carbon atoms.

(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 fluorenyl group is preferably 2.20 or more and 2.90 or less, and more preferably 2.40 or more and 2.88 or less. Further, the degree of substitution B of the fluorenyl group having 3 to 22 carbon atoms is more preferably 0.30 or more, and more preferably 0.5 or more. Among them, the present invention has a particularly large effect when cellulose diacetate (DAC) is used as the cellulose halide 22.

Embodiments of the invention are described below. However, the present invention is not limited to the following examples, and the following examples are cited as examples of the present invention. The details will be described with reference to Example 1. The respective examples of the second embodiment and the comparative examples of the present invention show only the conditions different from those of the first embodiment.

[Example 1]

The film 27 is produced from the dope 24 by the solution film forming apparatus shown in Fig. 1. The cellulose halide 22 used is cellulose diacetate (DAC). This film 27 is a VA (Vertical Alignment) type retardation film user as a so-called LCD. The rollers 34, 35 have a diameter of 2 m.

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

The tension of the roller 34 is adjusted by the tension controller 51 so that the tension of the belt 33 is 60 N/mm ² , and the tension in the A direction is imparted to the belt 33. In the tension imparting state, the side portion 33s is lifted up, and the side portion 33s floats from the circumferential surface 34b of the roller 34. The central portion 33c is in contact with the circumferential surface 34b of the roller 34. The floating amount J1 on the side edges 33e (L) and 33e (R) was 1.1 mm, and the floating amount K of the product predetermined region Ap on the side edge was 0.11 mm.

As shown in FIG. 1, FIG. 2, FIG. 4, and FIG. 5, the casting die 38 is disposed such that the casting position PC is located at the downstream end of the winding region Ar with respect to the roller 34, and the first pair is first. The roller 52 is disposed upstream of the casting position PC. The welded portion 33w and the side portion 33s are pressed by the first roller 52, and the floating of the side portion 33s is corrected. The diameter of the first roller 52 is 100 mm.

The thickness unevenness in the width direction of the obtained film 27 is an allowable level. Further, it was not confirmed that the cast film 39 remained in the belt 33 at the time of peeling, and the foaming of the cast film 39 was not confirmed even in the entire full width region of the side portion.

[Embodiment 2]

As shown in Fig. 9, the second roller 61 is disposed downstream of the casting position PC, and the side portion 33s of the belt 33 guided from the casting position PC is pressed. Other conditions were carried out in the same manner 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 is more excellent than that of the first embodiment, and is an allowable level. Further, it was not confirmed that the cast film 39 remained on the belt 33 at the time of peeling, and no foaming of the cast film 39 was observed in the entire width domain, and it was not confirmed even at the side portion.

[Example 3]

As shown in Fig. 7, the first roller 52 upstream of the casting position PC is replaced by the full-width pressing roller 57, and the side portion 33s of the belt 33 from the peeling position PP toward the casting position PC is pressed in addition to pressing the center portion 33c. And the welded portion 33w. Other conditions were carried out in the same manner as in Example 1. The full width pressing roller 57 has a diameter of 150 mm.

The thickness unevenness in the width direction of the obtained film 27 is an allowable level, which is superior to that of the first embodiment. Further, it was not confirmed that the casting film 39 remained on the belt 33 at the time of peeling, and the foaming of the casting film 39 was not confirmed in the entire width domain, and was not confirmed even at the side portion.

[Comparative Example 1]

The same conditions as in Example 1 were used except that the first roll 52 was not used.

The thickness of the obtained film in the width direction is extremely uneven, which is an unacceptable level. Further, it was not confirmed that the cast film remained in the belt at the time of peeling. Further, in the cast film, foaming was not confirmed at the side portion.

10. . . Solution film making equipment

11. . . Casting device

twenty four. . . Concentrate

27. . . membrane

33. . . band

33A. . . Casting surface

33c. . . Central department

33s. . . Side

33w. . . Welding department

38. . . Casting die

39. . . Cast film

52, 61. . . First roll, second roll

57. . . Full width press roller

65. . . Support roller

PC. . . Cast position

PP. . . Peeling position

The above objects and advantages will be readily understood by those skilled in the art in the <RTIgt;

Fig. 1 is a schematic view of a solution film forming apparatus.

Fig. 2 is a schematic perspective view of a belt wound around a roller and a first roller.

Fig. 3 is an explanatory view of the floating of the side portion of the belt.

Fig. 4 is a side view showing the first embodiment of the present invention in which the first roller is used.

Fig. 5 is a plan view showing a first embodiment.

Fig. 6 is a perspective view of the first roller.

Fig. 7 is a plan view showing a second embodiment in which a full width pressing roller is used.

Fig. 8 is a side view showing a third embodiment in which the first roller and the second roller are used.

Fig. 9 is a plan view showing a third embodiment.

Fig. 10 is a side view showing a fourth embodiment in which a full width pressing roller is used.

Fig. 11 is a plan view showing a fourth embodiment.

Fig. 12 is an explanatory diagram of the warp angle θ.

Fig. 13 is an explanatory view of the welded portion of the belt and its vicinity.

33. . . band

33s. . . Side

33c. . . Central department

33w. . . Welding department

38a. . . Outflow

38. . . Casting die

39. . . Cast film

34. . . Roll

40. . . Decompression chamber

52. . . First roller

53. . . Displacement mechanism

54. . . Controller

Claims (10)

A solution film forming method, wherein a dope obtained by dissolving a polymer in a solvent is cast on a metal tape to form a cast film, and the cast film is peeled off from the tape and dried, and the solution film forming method The method includes the steps of: preparing the annular belt formed by a wide central portion and a pair of narrow side portions, wherein the pair of side portions are integrated with both side ends of the central portion by welding, and the Wrapped around the circumferential surface of the pair of rolls and circulated in the longitudinal direction; the welded portion extending in the longitudinal direction of the belt by the first roll and the side portion floating from the pair of rolls are Correcting the floating of the side portion, the first roller is disposed opposite to the belt from the peeling position toward the casting position, wherein the peeling position is a position at which the casting film is peeled off, and the casting position is the casting In the position of the dope, the first roller is provided so that the longitudinal direction thereof is rotatably aligned with the width direction of the tape, and the first roller presses the welded portion from the tape surface side of one of the doped liquids. And the aforementioned side portions; before casting the aforementioned concentrated liquid to form a casting film, wherein the dope is cast in such a manner that the casting film is formed on the center portion and the welded portions on both sides; the casting film is peeled off from the tape; and the cast film is dried and peeled off As a film. The solution film forming method according to claim 1, wherein the entire width of the belt is pressed by the first roll longer than the full width of the belt. The method of forming a solution according to the first aspect of the invention, wherein the first step of the rotation of the circumferential surface by the driving means is resin processing and having the first means of driving means at a speed similar to the conveying speed of the belt. Roller. The method of forming a solution according to claim 1, further comprising the step of: extruding the non-casting region exposed by the casting film without forming the casting film by the second roller; The second roller is disposed to face the belt from the casting position toward the peeling position, and the second roller is provided so that the longitudinal direction thereof is rotatably aligned with the width direction of the belt. The solution film forming method according to claim 1, wherein the belt is conveyed by the pair of rollers that are rotated in the circumferential direction by the belt from the one of the pair of rollers The dope is discharged from the opposite casting die so that the casting position is on one of the aforementioned rolls. The solution film forming method according to claim 1, wherein the belt is conveyed by the pair of rollers that rotate in the circumferential direction, and the support roller supports the belt from one of the pair of rollers toward the other. The casting position is placed on the support roller by flowing out the dope from a casting die disposed opposite the aforementioned belt on the support roller. A casting device comprising: a pair of rollers; a metal belt composed of a wide central portion and a pair of narrow sides, wherein the pair of side portions are integrated with both sides of the central portion by welding The ring-shaped belt is conveyed in the longitudinal direction so as to be wound around the circumferential surface of the pair of rolls and to circulate the casting position and the peeling position, and the casting position is a dope in which the polymer is dissolved in the casting solvent. a position at which the casting film is formed, wherein the peeling position is a position at which the casting film is peeled off; and the first roller presses a welded portion extending in a longitudinal direction of the belt and the side portion floating from the pair of rollers and corrects In the floating of the side portion, the first roller presses the welded portion and the side portion of the belt from the peeling position toward the casting position, and the first roller has a longitudinal direction that coincides with a width direction of the belt. And the casting die is provided in a rotatable mold, and the casting die is formed by forming the casting film on the center portion and the welded portions on both sides. The casting device according to claim 7, wherein the first roller is longer than the width of the belt to press the entire width of the belt. The casting device according to claim 7, wherein the first roller has a driving means, and the circumferential surface is processed by a resin. The casting device according to claim 7, further comprising: a second roller, wherein the second roller presses the non-flow exposed without forming the casting film in the belt from the casting position toward the peeling position In the extension region, the second roller is equipped in such a manner that the longitudinal direction thereof coincides with the width direction of the belt and is rotatable.