TWI618581B - Casting device, solution film forming device and method - Google Patents

Abstract

The present invention provides a casting device, a solution film-forming equipment, and a solution film-forming method that suppress the occurrence of uneven thickness failure when a thin film of 15 μm or more and 80 μm or less is produced at high speed. The dope 30 is cast from a mold 25 to a belt 23 mounted on a pair of rotating drums 21 and 22, and a liquid bead 31 is formed between the belt 23 and the belt 23. The liquid beads 31 are cast on the belt 23 to form a casting film 32. A wind blocking block 41 is provided on the upstream side of the belt traveling direction with respect to the mold 25. The wind shielding block 41 faces the belt 23 and has an associated wind guide surface 42. The exit of the associated wind guide surface 42 is positioned on the side of the mold 25. By dividing a part of the associated wind 43 caused by the high-speed travel of the belt 23 to the mold 25 side, the associated wind 43 which causes the liquid beads 31 to vibrate or air to be drawn in can be reduced accordingly, and the thickness of the casting film 32 can be eliminated. Uneven.

Description

Casting device, solution film forming equipment and method

The invention relates to a casting device, a solution film-making equipment and a method.

A polymer film (hereinafter referred to as a film) is used as an optically functional film in a variety of ways due to its excellent light transmission properties, flexibility, and the ability to achieve a lightweight thin film. Among them, cellulose ester films, such as cellulose acylate, have strong toughness or low birefringence, so they are used as photographic films, and have been expanding in recent years. A protective film, an optical compensation film, and the like of a polarizing plate of a constituent element of a liquid crystal display device.

The main film manufacturing methods include solution film forming methods and melt extrusion methods. In the solution film forming method, a polymer solution (hereinafter referred to as a dope) containing a polymer and a solvent is flowed onto a support as a bead. The liquid beads become a casting film on the support. After the casting film becomes self-supporting, it is peeled off from the support to make a wet film. Then, the wet film is dried to form a film. Compared with a melt extrusion method in which an extruder is used to extrude a molten polymer into a film, the solution film forming method can obtain better optical isotropy or thickness uniformity, and it can contain more foreign materials. There are few films, so optically functional films are mainly manufactured by solution film forming methods.

Regarding the production speed of the solution film forming method, it is generally considered that the speed limit in the casting step of forming a casting film from a dope. Therefore, in order to improve the productivity of solution film formation, speeding up the casting step has become an issue. In order to perform the casting step at a high speed, for example, the traveling speed of the support is increased. However, in the vicinity of the surface of the traveling support body, wind (hereinafter referred to as an associated wind) which flows along with the support body and progresses along with the support body is generated. If the associated wind touches the liquid beads, the liquid beads vibrate. The vibration of the liquid beads causes a failure in the thickness of the film in the film width direction. Such uneven thickness failure caused by the associated wind becomes obvious as the traveling speed of the support becomes higher. Therefore, as disclosed in Patent Document 1, a windshield is disposed close to the liquid beads on the upstream side of the support in the traveling direction of the liquid beads to prevent the accompanying wind from entering the liquid beads.

In addition, as disclosed in Patent Document 2, a decompression chamber is arranged close to the liquid beads on the upstream side of the support in the traveling direction of the liquid beads, and the associated wind is sucked by the negative pressure to suppress the liquid beads caused by the associated wind. vibration.

[Prior Art Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. 2004-114328

[Patent Document 2] Japanese Patent Laid-Open No. 2010-158834

In addition, in recent years, flat panel displays Larger and lighter films are being made thinner. In order to efficiently manufacture a thin film, in addition to a method of forming a thin film by stretching in a stretching step after film formation, a method of thinning a thickness in a liquid bead stage can also be mentioned. Make improvements.

However, in the case where the liquid beads are thinned and cast in the casting stage, if the thickness of the liquid beads has not been a problem so far, if the liquid beads become thin, they are also easily affected by the associated wind. Regarding the method for thinning the liquid beads, there are cases in which the thickness of the liquid beads at the ejection port of the die is not changed as in the conventional case, but the moving speed of the support is increased so that the liquid beads are about to contact the support. The case where the previous thickness becomes thinner; or the case where the thickness of the liquid beads at the nozzle of the mold is thinner than conventional.

For example, when a windshield is disposed close to a support body as in Patent Document 1, and the windshield is used to block the accompanying wind accompanying the movement of the support body, if the liquid beads are thinned and cast, the width direction is Uneven thickness occurs over long distances. This thickness unevenness changes in the feed direction of the support, and appears as a surface failure that changes in a waveform in the feed direction. Therefore, improvement is required.

In addition, when a decompression chamber is used as in Patent Document 2, as the liquid beads are thinned, the liquid beads are liable to vibrate due to air pressure vibration caused by negative pressure. As a result, a surface property failure that has a waveform change in the feed direction is shown, and improvement is required. In addition, air entanglement is liable to occur due to the vibration of the liquid beads. When air is drawn between the support and the liquid beads, the air enters between the casting film formed by casting the liquid beads on the support and the support. This air entrapment sometimes progresses to cracking of the casting film. To stop casting in this case, it takes a lot of time and labor to start casting. Therefore, there is a demand for suppressing air entrapment.

An object of the present invention is to provide a casting device, a solution film forming apparatus, and a method. When a film is formed into a solution, high-speed casting can be performed to improve productivity, and surface properties can be suppressed from being deteriorated or caused by air entrainment. The casting stops and so on.

In order to achieve the object, the present invention has a mold, a wind shielding element and an associated wind guide surface. The mold ejects the concentrated liquid from the ejection port toward the traveling support, and forms liquid beads between the mold and the support. The liquid beads become a casting film on the surface of the support. The wind shielding element is provided in the width direction of the casting film on the upstream side of the supporting body in the traveling direction upstream of the liquid beads. The wind shielding element is arranged close to the surface of the support, and shields the associated wind caused by the support against liquid beads. The associated wind guide surface is formed at a portion close to the surface of the support, and guides the associated wind to the mold.

In addition, the associated wind guide surface is preferably a downwardly convex curved surface that guides the associated wind from a position near the surface to the mold. The curved surface preferably has a porous layer with a smooth surface, and the associated wind is sucked from the porous layer. In addition, it is preferable that the curved surface has a groove extending in the width direction of the casting film, and the accompanying wind be sucked from the groove.

It is preferable that the support side of the associated wind guide surface in the traveling direction downstream side is connected to a mold more than 2 mm from the ejection outlet, and the associated wind sent along the associated wind guide surface is sucked through the suction channel. . In addition, it is preferable that the distance between the wind shielding element and the surface of the support is 0.1 mm or more and 3 mm or less, and the length of the traveling direction of the associated wind guide surface is 10 mm or more and 40 mm or less.

The solution film forming apparatus of the present invention includes the casting device, a peeling element for peeling the casting film from the support, and a drying device for drying the peeled casting film. The solution film forming method of the present invention includes a step of forming a cast film on a support using the casting device, and a step of peeling the cast film from the support and drying the cast film.

According to the present invention, it is possible to efficiently produce a thin film while suppressing occurrence of uneven thickness failure.

10‧‧‧Solution film forming equipment

11‧‧‧casting device

12‧‧‧The first tenter

13‧‧‧ drying device

14‧‧‧The second tenter

15‧‧‧Slitting machine

16‧‧‧ Take-up device

21, 22‧‧‧ rotating drum

23, 101‧‧‧ belt

24‧‧‧Guide roller

25‧‧‧Mould

25A‧‧‧Spout

25B‧‧‧Side

26A, 26B, 26C‧‧‧pipes (film dryer)

28‧‧‧ stripping roller

30‧‧‧ dope

31, 105‧‧‧ liquid beads

32, 106‧‧‧ cast film

33‧‧‧ film

33A‧‧‧ roll film

34, 35‧‧‧ Fixtures

36, 37‧‧‧ Pipeline

38‧‧‧roller

41, 53, 62, 72, 102‧‧‧ wind block

41A‧‧‧Upside bevel

42, 55, 60, 73‧‧‧ Associated wind guide surface

42A‧‧‧Entrance

42B‧‧‧Export

43, 104‧‧‧ associated wind

43A, 104A‧‧‧ Lower part

43B‧‧‧ Upper part

45‧‧‧ spacer

46, 52‧‧‧ Suction channels

51‧‧‧ porous layer

54‧‧‧Negative pressure source

61‧‧‧Suction trough

61A‧‧‧Suction port

71‧‧‧ entrance guide

74‧‧‧ Upper Associated Wind Guide Surface

75‧‧‧suction channel surface

103, G, G1, G2‧‧‧ clearance

107‧‧‧ Vortex

A, B‧‧‧ arrows

L1‧‧‧ length

L2‧‧‧distance

FIG. 1 is a side view showing an outline of a solution film forming apparatus according to this embodiment.

It is a perspective view which shows the outline of a casting apparatus.

3 is a cross-sectional view showing the flow of the accompanying wind between the mold and the wind shield block and the band according to the first embodiment.

4 is a cross-sectional view showing a porous layer and a suction channel of a windshield block according to a second embodiment.

FIG. 5 is a cross-sectional view showing the flow of the associated wind in the porous layer.

Fig. 6 is a rear view showing a windshield block of the porous layer.

7 is a cross-sectional view showing a suction groove of a wind shield block according to a third embodiment.

Fig. 8 is a rear view showing a suction groove of a wind shield block according to a third embodiment.

Fig. 9 is a cross section showing a windshield block according to a fourth embodiment having an entrance guide; Illustration.

FIG. 10 is a cross-sectional view showing the flow of accompanying wind in a conventional wind shield block.

As shown in FIG. 1, the solution film forming apparatus 10 includes a casting device 11, a first tenter 12, a drying device 13, a second tenter 14, a slitter 15, and a winding device 16. These elements They are connected in series from the upstream side.

The casting device 11 includes a drum 21, a drum 22, an endless belt (support) 23 mounted on these drums 21 and 22, a guide roller 24, a mold 25, and a duct (film dryer) 26A, pipe (film dryer) 26B, pipe (film dryer) 26C, and stripping roller 28. The belt 23 functions as a metal cast support formed in a ring shape, and is stretched over the peripheral surfaces of the first drum 21 and the second drum 22. The first drum 21 is rotationally driven by a motor (not shown), whereby the belt 23 travels in a first direction shown by an arrow A. The guide roller 24 supports the upper belt 23 from the rear surface side.

As shown in FIG. 2, a mold 25 is arranged above the first drum 21. The mold 25 makes the dope 30 into liquid beads 31 and continuously flows from the ejection port 25A (see FIG. 3) onto the surface of the traveling belt 23. Thereby, the casting film 32 is formed on the tape 23. The mold 25 is formed with a side surface 25B which is inclined so as to be further away from the belt 23 toward the upstream side in the traveling direction. The side surface 25B is formed on the upstream side in the traveling direction from the ejection outlet 25A. The dope 30 is obtained by dissolving tritiated cellulose in a solvent, for example, and is manufactured by a dope manufacturing line (not shown) and supplied to the mold 25.

As shown in FIG. 1, in order to increase the manufacturing speed, the casting is directed toward the peeling roller 28. The film 32 is heated by the second drum 22 and the belt 23. At the casting position, the belt 23 is cooled by the first drum 21 so that the belt 23 does not excessively heat up. Therefore, each of the drums 21 and 22 has a temperature adjustment device (not shown).

The duct 26A, the duct 26B, and the duct 26C are arranged in plurality along the traveling route of the belt 23 and blow dry air. The warm air controller independently controls the temperature, humidity and flow of the dry air. The temperature of the casting film 32 is adjusted by controlling the temperature and flow rate of the drying wind and the temperature control device of the rotating drum 21 and the rotating drum 22, and the solvent is evaporated from the casting film 32 to perform the casting film. 32 dry. The cast film 32 is cured to such an extent that the cast film 32 can be transported in the first tenter 12.

A stripping roller 28 is disposed near the peripheral surface of the first drum 21 on the upstream side of the die 25 in the traveling direction. The peeling roller 28 supports the casting film 32 when it peels off the dried casting film 32 containing the solvent from the tape 23. The stripped casting film 32 is guided to the first tenter 12 as the film 33. In the present embodiment, the peeling roller 28 functions as a peeling element that peels the casting film 32 from the belt 23.

In the first tenter 12, the edges of both sides of the film 33 are held by clips 34, and the dry wind is sent out from the duct 36, so that the film 33 is transported on one side and the width of the film 33 on the other side Tension is applied to expand the width of the film 33.

In the drying device 13, the film 33 is wound around a plurality of rollers 38 and conveyed. Regarding the environment inside the drying device 13, the temperature, humidity, and the like are adjusted by a thermostat (not shown), and the solvent is evaporated from the film 33 while the film 33 is being transported.

The second tenter 14 includes a jig 35 and a pipe 37, and has the same configuration as the first tenter 12. The second tenter 14 holds and stretches the film 33 using a jig 35. By this stretching, a film 33 having desired optical characteristics is obtained. The second tenter 14 may be omitted depending on the optical characteristics of the film 33.

The slitter 15 cuts the side of the film 33. Specifically, the slitting machine 15 cuts off the side portions including the marks held by the clamps 35 and 35 of the first tenter 12 or the second tenter 14. The cut-off film 33 is wound into a roll shape by a winding device 16. The thus obtained roll-shaped film 33A can be used in particular as a retardation film or a polarizing plate protective film.

A windshield block (windshield element) 41 is disposed upstream of the liquid beads 31 from the mold 25 in the traveling direction of the belt 23. As shown in FIG. 2, the wind shield block 41 is arranged so as to approach the liquid beads 31 and extend in the width direction of the casting film 32. The "close" means a state in which they approach each other to such an extent that no practical obstacle is caused to the movement, and a gap is formed to the extent that air passes through each other. In this embodiment, the wind shielding block 41 is set on the mold 25 on the upstream side in the traveling direction from the ejection outlet 25A. The wind blocking block 41 is arranged near the mold 25 on the upstream side in the traveling direction from the ejection outlet 25A. The wind block 41 is attached to the mold 25 via a spacer 45. More specifically, the wind blocking block 41 is arranged so that the upper inclined surface 41A of the wind blocking block 41 is parallel to the side surface 25B of the mold 25, and the spacer 45 is arranged between the upper inclined surface 41A and the side surface 25B. Connected to the mold 25. The length of the windshield block 41 in the width direction of the belt 23 shown by the arrow B is the same length as the mold 25 and faces the mold 25 in the width direction. In addition, the wind shield 41 has The belt 23 faces the associated wind guide surface 42. The associated wind guide surface 42 is arranged so as to be close to the surface of the belt 23. Hereinafter, a direction indicated by an arrow B may be referred to as a "B direction".

A spacer 45 is provided between the mold 25 and the wind shield block 41 in a direction away from the B direction, and a suction channel 46 is formed between the side surface 25B of the mold 25 and the upper inclined surface 41A of the wind shield block 41. The belt 23 travels at a high speed, and therefore accompanies the air to generate an associated wind 43. The wind blocking block 41 blocks the associated wind 43 toward the liquid beads 31. Specifically, the wind shielding block 41 shields the associated wind 43 on the upstream side of the liquid beads 31 so that the associated wind 43 does not contact the liquid beads 31.

A gap G is provided between the wind blocking block 41 so as not to contact the traveling belt 23. Therefore, the lower portion 43A of the associated wind 43 which is not completely blocked by the wind blocking block 41 passes through the gap G.

As shown in FIG. 10, when the traveling speed of the conventional belt 101 is about 30 m / min, the associated wind 104 passing through the liquid beads 105 in the gap 103 between the windshield block 102 and the surface of the belt 101 The influence is small, and it does not develop into a failure of uneven surface properties such as uneven thickness of the casting film 106. With the request for thin film, if the traveling speed of the belt 101 is set to a high speed of 50 m / min or more and 100 m / min or less, the liquid beads 105 also become thinner due to the increase in speed, and are easily affected by the associated wind 104. . In addition, it is known that although the wind shielding block 102 is used to shield the associated wind 104, the lower layer portion 104A of the accompanying wind 104 passing through the gap 103 is rolled into a vortex 107 after passing through the wind shielding block 102. The present inventors have confirmed through experiments that the generation of the vortex 107 or the vibration imparted to the liquid beads 105 by the vortex 107 and the like.

Therefore, as shown in FIG. 3, in the first embodiment, the associated wind guide surface 42 is gradually increased away from the belt 23 as it goes toward the liquid beads 31, so that the associated wind guide surface is gradually increased. The gap G between 42 and the surface of the belt 23. In addition, the associated wind guide surface 42 is set as a downwardly-curved curved surface (curved surface convex toward the belt 23 side) so that the associated wind 43 flows smoothly along the associated wind guide surface 42. The associated wind guide surface 42 has a curved surface protruding toward the belt 23 side. Further, the exit end 42B of the associated wind guide surface 42 is positioned on the side surface 25B of the mold 25. Specifically, the associated wind guide surface 42 is configured such that when the surface is extended toward the mold 25 along the curved surface of the associated wind guide surface 42, the surface intersects the side surface 25B of the mold 25. Therefore, the lower portion 43A of the associated wind 43 is moved along the associated wind guide surface 42 and guided to the side surface 25B of the mold 25, thereby reducing the associated wind 43 toward the liquid beads 31, and the liquid beads 31 become stable. No air entrainment is generated. Although the associated wind guide surface 42 is set as a curved surface that is convex downward, it may be a flat surface. In addition, in FIG. 3, in order to avoid complicated drawings, hatching of the mold 25 and the wind shield 41 is omitted.

At the entrance end 42A of the wind blocking block 41, the upper portion 43B of the accompanying wind 43 is blocked by the wind blocking block 41. In addition, a part of the lower layer portion 43A of the associated wind flowing along the associated wind guide surface 42 does not contact the liquid beads 31 but contacts the side surface 25B of the mold 25. The associated wind 43 that contacts the side surface 25B of the mold 25 is sent to the upper portion of the mold 25 through the suction channel 46. In addition, for the associated wind 43 flowing along the belt 23 without flowing along the associated wind guide surface 42, the associated wind 43 flowing on the associated wind guide surface 42 is correspondingly reduced, so that the liquid beads 31 can be suppressed. Vibration or air entanglement.

For the associated wind guide surface 42, the gap G1 (the distance between the inlet end 42A and the belt 23) from the entrance side of the belt 23 (the upstream side of the belt 23 in the direction of travel) is 0.1 mm or more and 3 mm or less, preferably 0.5. Above mm and below 2mm. In the case of 0.1 mm or more, it is preferable that the associated wind guide surface 42 does not easily come into contact with the belt 23 even if there is an influence of a temperature change or a foreign matter on the belt 23. In addition, if it is 3 mm or less, the associated wind 43 is easily blocked, and the effect of shielding the wind is easily obtained. The gap G2 (the distance between the outlet end 42B and the belt 23) on the exit side (the downstream side of the belt 23 in the direction of travel) is 3 mm or more and 20 mm or less, preferably 5 mm or more and 10 mm or less. In the case of 3 mm or more, the guided associated wind 43 is easily separated from the liquid beads 31, and the surface property improvement effect is easily obtained. In addition, in the case of 20 mm or less, it is easy to prevent the guided accompanying wind 43 from being scattered halfway, and it is easy to obtain a surface property improvement effect.

The length L1 of the associated wind guide surface 42 in the A direction is 10 mm or more and 40 mm or less, and preferably 20 mm or more and 30 mm or less. In the case of 10 mm or more, the guided associated wind 43 is easily separated from the liquid beads 31, and the surface property improvement effect is easily obtained. In addition, if it is 40 mm or less, it is easy to prevent the guided accompanying wind 43 from being scattered midway, it is easy to guide the associated wind 43, and it is easy to obtain a surface property improvement effect. The distance L2 of the exit end 42B of the associated wind guide surface 42 from the ejection port 25A of the mold 25 is 2 mm or more, preferably 3 mm or more, and more preferably 5 mm or more. In the case of 2 mm or more, the guided associated wind 43 is difficult to contact the liquid beads 31, and the surface property improvement effect is easily obtained.

As shown in Figs. 4 to 6, in the second embodiment, the first embodiment The wind blocking block 41 is provided with a porous layer 51 and a suction channel 52 on its associated wind guide surface 55 to form a wind blocking block 53. In addition, the same components as those in the first embodiment are denoted by the same reference numerals, and redundant descriptions are omitted. As shown in FIG. 6, the porous layer 51 is formed long in the B direction. The surface of the porous layer 51 is formed smoothly. The term "smooth" means that the arithmetic surface roughness Ra is 30 µm or less. By setting Ra to 30 μm or less, the associated wind can be directed to the mold 25 without disturbing it.

The suction channel 52 is formed on the back surface (inner surface) of the porous layer 51. The suction channel 52 is connected to a negative pressure source 54 provided outside the wind shield block 53. Therefore, the associated wind 43 is sucked when passing through the porous layer 51. As a result, most of the associated wind 43 is guided to the associated wind guide surface 55 side, so that the associated wind 43 that contacts the liquid beads 31 can be reduced accordingly.

As shown in FIGS. 7 and 8, in the third embodiment, a suction groove 61 is formed in the associated wind guide surface 60 along the B direction instead of the porous layer 51 to constitute a wind shield block 62. The suction groove 61 has a circular cross section and has a suction port 61A at a lower end. A plurality of, for example, three suction grooves 61 are arranged in the A direction. Both ends in the B direction of the suction groove 61 are connected to a negative pressure source 54. Therefore, the associated wind 43 passing through the gap G is sucked by the suction groove 61 and discharged from both sides of the wind shield block 62.

As shown in FIG. 9, in the fourth embodiment, an inlet guide 71 is provided on the entrance side of the windshield block 41 of the first embodiment to constitute the windshield block 72, and the basic structure is the same as the windshield block of the first embodiment. 41 are the same. The wind shield 72 has a shape protruding toward the upstream side in the traveling direction, and an entrance guide 71 is formed on the most upstream side with respect to the traveling direction of the belt 23. In order to efficiently separate the associated wind 43 into the lower part 43A and In the upper portion 43B, the entrance guide 71 becomes an acute angle. The entrance guide 71 includes an upper-stage associated wind guide surface 74 that comes into contact with the lower-stage associated wind guide surface 73 at an acute angle from an inclined upper side. Therefore, the windshield block 72 has a substantially triangular shape in the vertical section due to the lower associated wind guide surface 73, the upper associated wind guide surface 74, and the suction channel surface 75. In addition, a porous layer 51 as in the second embodiment or a suction groove 61 as in the third embodiment may be formed on the lower associated wind guide surface 73.

In each of the embodiments described above, the suction pressure BP of the suction passage 46, the suction passage 52, and the suction groove 61 is -0.5 Pa or more and -100 Pa or less, preferably -1 Pa or more and -50 Pa or less. In the case of -0.5Pa or more, it is easy to sufficiently guide the associated wind. In addition, in the case of -100 Pa or less, deformation of the liquid beads itself due to the influence of negative pressure is unlikely to occur, and thus the surface properties are good.

In each of the above-mentioned embodiments, a windshield block 41, a windshield block 53, a windshield block 62, and a windshield block 72 are provided on the upstream side of the mold 25 with respect to the traveling direction. A decompression chamber is further provided on the upstream side of the block 53, the wind blocking block 62, and the wind blocking block 72. The decompression chamber sucks air in the area upstream of the liquid beads 31 and decompresses the area, thereby reducing the vibration of the liquid beads 31.

In the second embodiment, the porous layer 51 is formed on the entrance end side of the associated wind guide surface 42, and the porous layer 51 may be formed over the entire surface of the associated wind guide surface 42.

In the solution film forming apparatus 10, the width of the film 33 as a product is preferably 600 mm or more, and more preferably 1400 mm or more and 2500 mm or less. It is also effective when the width of the film 33 is larger than 2500 mm. In addition, the film thickness of the film 33 is relatively large. It is preferably 15 μm or more and 80 μm or less, particularly preferably 15 μm or more and 60 μm or less, and more preferably 15 μm or more and 40 μm or less. The polymer used as a raw material of the film 33 is not particularly limited, and examples thereof include tritiated cellulose and cyclic polyolefin.

There may be only one fluorenyl group used in the tritiated cellulose of the present invention, or two or more fluorenyl groups may be used. When two or more kinds of fluorenyl groups are used, it is preferable that one of them is an ethenyl group. It is preferable that the ratio of esterifying the hydroxyl group of cellulose with a carboxylic acid, that is, the degree of substitution of a fluorene group satisfies all of the following formulas (I) to (III). In the following formulae (I) to (III), A and B represent the degree of substitution of the fluorenyl group, A represents the degree of substitution of the ethenyl group, and B represents the degree of substitution of the fluorenyl group having 3 to 22 carbon atoms. Moreover, it is preferable that 90 weight% or more of triacetyl cellulose (TAC) is a particle of 0.1 mm-4 mm.

(I) 2.0 ≦ A + B ≦ 3.0

(II) 1.0 ≦ A ≦ 3.0

(III) 0 ≦ B ≦ 2.9

The total degree of substitution A + B of the fluorenyl group is preferably 2.20 or more and 2.90 or less, and particularly preferably 2.40 or more and 2.88 or less. The degree of substitution B of the fluorenyl group having 3 to 22 carbon atoms is more preferably 0.30 or more, particularly preferably 0.5 or more.

The details of the tritiated cellulose are described in paragraphs [0140] to [0195] of Japanese Patent Laid-Open No. 2005-104148. These descriptions can also be applied to the present invention. In addition, the solvents and plasticizers, anti-deterioration agents, ultraviolet absorbers (UV agents), optical anisotropy control agents, retardation control agents, dyes, matting agents, release agents, and release accelerators are also described in detail in the same manner Patented in Japan In paragraphs [0196] to [0516] of JP 2005-104148.

[Example]

In order to confirm the effects of each of the wind blocking blocks 41, 53, 62, and 72, experiments were performed. In Example 1, as shown in FIG. 3, the wind block 41 having an associated wind guide surface 42 is used to stabilize the liquid beads 31, and the solution film forming apparatus 10 shown in FIG. 1 is used to form a cast on the belt 23. After the film 32, the cast film 32 is peeled off to form a film 33. The film 33 passes through the first tenter 12, the drying device 13, and the second tenter 14 to produce the film 33, and the film 33 is wound into a roll shape. In Example 2, as shown in FIG. 4 to FIG. 6, a film 33 was produced under the same conditions as in Example 1 except that a wind shield block 53 having a porous layer 51 on the associated wind guide surface 42 was used. . In Example 3, as shown in FIGS. 7 and 8, a windshield block 62 having a suction groove 61 on the associated wind guide surface 60 was used, and a film 33 was produced under the same conditions as in Example 1. . In Example 4, as shown in FIG. 9, a film 33 was manufactured under the same conditions as in Example 1 except that a wind block 72 having an entrance guide 71 was used.

In Comparative Example 1, a film 33 was produced under the same conditions as in Example 1 except that the conventional wind shield block 102 shown in FIG. 10 was used. In Comparative Example 2, except that the windshield was removed from Example 1, a film 33 was manufactured under the same conditions as in Example 1.

In Examples 1 to 4, the thickness was not all 0.2 μm, and the castable limit speed was 80 m / min. On the other hand, in Comparative Example 1, the thickness was not uniform at all 0.4 μm, and the castable limit speed was 40 m / min. In addition, in Comparative Example 2, the thickness was not all 0.8 μm, and the castable limit speed was 40 m / min. From the above results, it is understood that the thickness unevenness is improved and the castable limit speed is increased.

In addition, the thickness unevenness is the difference between the maximum value and the minimum value of the thickness variation in the casting direction of the film set in the dry state. The thickness variation is measured using a contact or non-contact film thickness meter, and the thickness variation is determined from the thickness variation Both. The castable limit is determined based on whether air entrainment occurs. The occurrence of air entanglement is judged by the following methods: visually confirm whether there is a bubble near the landing point of the liquid bead and whether there is a bubble entering between the liquid bead and the belt.

23‧‧‧ belt

25‧‧‧Mould

25A‧‧‧Spout

25B‧‧‧Side

30‧‧‧ dope

31‧‧‧ liquid beads

32‧‧‧cast film

41‧‧‧wind block

41A‧‧‧Upside bevel

42‧‧‧ Associated Wind Guide Surface

42A‧‧‧Entrance

42B‧‧‧Export

43‧‧‧ associated wind

43A‧‧‧Lower section

45‧‧‧ spacer

46‧‧‧Suction channel

A‧‧‧arrow

G, G1, G2 ‧‧‧ clearance

L1‧‧‧ length

L2‧‧‧distance

Claims (7)

A casting device includes a mold that ejects a concentrated liquid from a discharge port to a traveling support body, while forming liquid beads between the mold and the support body, and forming a casting film on a surface of the support body. A wind shield element, which is arranged in the width direction of the casting film on the upstream side of the support body in the direction of travel of the support body, and is arranged close to the surface of the support body, and shields the The associated wind to the liquid beads caused by the support; and an associated wind guide surface formed at a portion close to the surface of the wind shield element and leading to the associated wind, The mold; wherein the associated wind guide surface is a curved surface that guides the associated wind to the mold from a position close to the surface of the support and is convex toward the support. The casting device according to item 1 of the scope of patent application, wherein the curved surface has a porous layer with a smooth surface, and the associated wind is sucked from the porous layer. The casting device according to item 1 of the patent application range, wherein the curved surface has a groove extending in a width direction of the casting film, and the associated wind is sucked from the groove. The casting device according to any one of claims 1 to 3, wherein the downstream side of the supporting body in the traveling direction of the associated wind guide surface is connected to a place at least 2 mm from the ejection outlet. The mold, and the associated wind sent along the associated wind guide surface is formed by a draft formed between the mold and the wind shielding element Suction by suction channels. The casting device according to any one of claims 1 to 3, wherein the distance between the wind shielding element and the surface of the support is 0.1 mm or more and 3 mm or less, and the associated wind guide The length of the leading surface in the traveling direction is 10 mm or more and 40 mm or less. A solution film forming apparatus, comprising: the casting device according to any one of claims 1 to 3 of the scope of patent application; a stripping element for peeling the casting film from the support; and A drying device for drying the cast film peeled from the support. A solution film forming method includes the steps of: forming a casting film on the support using a casting device according to any one of claims 1 to 3 of the scope of patent application; The step of peeling the cast film from the support; and the step of drying the cast film peeled from the support.