JP2009028899A - Film casting method and equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a film casting method and equipment capable of suppressing the occurrence of skinning, edge blocking and surface defect failure. <P>SOLUTION: A dope is cast onto a casting drum from a discharge port 36a of a casting die 36. A casting bead 40 is formed between the discharge port 36a and the casting drum. The upstream side in the drum running direction of the casting bead 40 is evacuated by a pressure reducing chamber 37. A solidification preventive liquid 41 is supplied to both end parts of the casting bead 40. A wind shielding plate 39 is disposed on the upstream side in the drum running direction near both end parts of the casting bead. Suction wind that flows into the pressure reducing chamber 37 from both end parts of the casting bead is shielded by the wind shielding plate 39. Thereby, the scattering of the solidification preventive liquid 41 can be prevented. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a solution casting method and equipment.

  A polymer film (hereinafter referred to as “TAC film”) formed from cellulose ester, particularly cellulose triacetate (hereinafter referred to as “TAC”) having an average degree of acetylation of 58.0 to 62.0%, has its toughness and flame retardancy. Due to its properties, it is used as a film support for photographic light-sensitive materials. Further, since the TAC film is excellent in optical isotropy, it is used as a protective film for a polarizing plate of a liquid crystal display device whose market is expanding in recent years.

  The TAC film is produced by a solution casting method. This solution casting method can produce a film having excellent physical properties such as optical characteristics as compared with other production methods such as a melt casting method. In the solution casting method, first, a polymer solution (hereinafter referred to as “dope”) in which a polymer is dissolved in a mixed solvent containing dichloromethane or methyl acetate as a main solvent is prepared. Then, the dope is cast from the casting die onto the support to form a casting film. The dope flow formed between the discharge port of the casting die and the support is called a casting bead. After the cast film on the support becomes self-supporting, it is peeled off from the support as a wet film. The wet film that has been peeled off is sent to the tenter device via a transfer section provided with a plurality of rollers. In the tenter apparatus, the wet film is dried while being stretched in the width direction. Thereby, a film is obtained. The film is then dried again and taken up by a take-up device.

  When casting the dope, drying at both ends in the width direction of the casting bead is easier to proceed than at the center, and therefore, burrs and ears are likely to be generated at both ends of the casting bead. Therefore, in order to prevent the casting bead from drying, a coagulation preventing liquid composed of a dope solvent or the like has been supplied by a liquid method nozzle (see Patent Document 1 or 2). Moreover, drying of both ends of the casting bead was prevented by making both ends of the discharge port of the casting die into a predetermined shape (see Patent Document 3).

On the other hand, when casting at a high speed, it is necessary to move the support body (for example, a casting drum or a casting band) that travels endlessly at a high speed. The problem can not be ignored. Accompanied wind is one of the major factors that cause vibration to the casting bead. In order to eliminate this effect, a decompression chamber is placed upstream of the casting bead in the running direction of the support in order to eliminate this effect. However, the inflow of accompanying wind is reduced.
Japanese Patent No. 2687260 JP 2002-337173 A JP 2002-103361 A

  In order to further improve the production efficiency of the polymer film, it is effective to increase the casting speed and widen it. In addition, due to demands for thinning and weight reduction of liquid crystal displays, there is also a demand for thinning polymer films used as protective films. However, if the casting width is widened and the casting bead is made thin in response to this requirement, simply supplying the anticoagulation liquid to both ends of the casting bead from the liquid method nozzle increases the height of the decompression chamber. Under the reduced pressure, the anticoagulation liquid was scattered by the suction air in the vacuum chamber.

  Due to this scattering, the anticoagulation liquid could not be efficiently supplied to both ends of the casting bead, and burrs and ears were likely to be generated at both ends of the casting bead. In addition, when the anticoagulation liquid scatters in the decompression chamber and drops that grow on the inner wall of the decompression chamber fall on the support, the anticoagulation liquid droplets are mixed into the casting film via the support. End up. The surface of the casting film is deformed by the mixing of the anticoagulation liquid into the casting film, and as a result, a surface defect such as deformation of the film surface occurs.

  It is an object of the present invention to provide a solution film-forming method and equipment for preventing the occurrence of burrs, ear lobes, and surface defect failures by preventing scattering of anticoagulation liquid supplied to both ends of a casting bead. Objective.

  In order to solve the above problems, the present invention discharges a dope containing a polymer and a solvent from a discharge part of a casting die onto a support that runs endlessly, and the discharge part of the casting die and the support A casting bead is formed between the casting bead and a casting film formed on the support, and the upstream side of the casting bead in the running direction of the support is depressurized by a decompression chamber, and the casting film is In the solution film-forming method for peeling off the wet film from the support and obtaining the film by drying the peeled wet film, the anticoagulation liquid supply means for the both ends of the casting bead in the width direction of the support The anti-coagulation liquid is supplied by the windshield member provided upstream of the casting bead in the support running direction in the vicinity of the support width direction both ends of the casting bead. Part of the vacuum Block the suction air flowing into the Nba, characterized in that to prevent the scattering of the anti-clotting solution.

  It is preferable that the wind-shielding member is attached inside the decompression chamber. The supply of the anticoagulation liquid to both ends of the casting bead in the width direction of the support is performed by a downstream liquid method nozzle provided on the downstream side in the running direction of the support with respect to the discharge portion of the casting die. Are preferred. A guide path for guiding the anticoagulation liquid from the liquid discharge port of the downstream liquid method nozzle toward both ends of the casting bead in the width direction of the support body, and the support body of the casting bead by the guide path; A pool of the anticoagulation liquid is formed downstream of the both ends in the width direction in the running direction of the support, and the anticoagulation liquid is supplied to both ends of the casting bead in the width direction of the casting bead through the liquid pool. It is preferable to do.

  The polymer is cellulose acylate, and the supply rate of the anticoagulation liquid is preferably 0.08 cc / min to 0.8 cc / min. It is preferable that the anticoagulation liquid is a mixed solvent of methylene chloride and methanol, and the ratio of methylene chloride / methanol is (2/3) or more and (3/2) or less. It is preferable that the running speed of the support is 50 m / min or more, the thickness of the film is 20 to 70 μm, and the width is 1.5 to 3.0 m.

  The solution casting apparatus according to the present invention includes an anticoagulation liquid supply means for supplying an anticoagulation liquid to both ends of the casting bead in the support width direction, and both ends of the casting bead in the support width direction. A wind-shielding member that is provided in the vicinity of the support body running direction in the vicinity and blocks the suction air flowing into the decompression chamber from both ends of the casting bead in the support width direction to prevent the anticoagulation liquid from scattering. It is characterized by providing.

  According to the present invention, it is possible to prevent scattering of the anticoagulation liquid supplied to both ends of the casting bead, and to suppress the occurrence of burrs, ear clumps, and surface defects.

  As shown in FIG. 1, the film manufacturing facility 10 according to the first embodiment of the present invention includes a casting chamber 11, a transition portion 12, a pin tenter 13, a clip tenter 14, ear cutting devices 15 and 16, and a drying device. A device 17, a cooling device 18, and a winding device 19 are provided.

  In the casting chamber 11, a casting drum 22 as a support, a casting unit 25 for casting the dope from the dope production facility 23 to the casting drum 22, and a casting film on the casting drum 22. A stripping roller 28 for stripping 26 as a wet film 27, a condenser 30 (condenser) for condensing and liquefying the solvent gas evaporated from the casting film 26, and a recovery device 31 for recovering the liquefied solvent are provided. . Further, a heat transfer medium supply device (not shown) is connected to the casting drum 22, and the surface of the casting drum 22 is made to have a desired surface by supplying the heat transfer medium into the casting drum 22. The temperature is adjusted. Further, a temperature adjusting device 33 for adjusting the internal temperature is attached to the casting chamber 11.

  The casting drum 22 is composed of a stainless steel drum, and is rotated in the drum running direction by a driving device such as a motor (not shown). The traveling speed (casting speed) of the casting drum 22 is not particularly limited, but is particularly effective for preventing the anticoagulation liquid from being scattered at high speed casting at a traveling speed of 50 m / min or more. The surface of the casting drum 22 is polished. As a result, a casting film 26 having excellent flatness is formed on the casting drum 22.

  The casting drum 22 is used as a support, but the form of the support is not particularly limited. For example, a casting band wound around a pair of rollers and running endlessly may be used as the support. The support preferably has a width of about 1.1 to 2.0 times the casting width of the dope. The material of the support is preferably a material having corrosion resistance and high strength, such as stainless steel.

  The casting unit 25 includes a feed block 35, a casting die 36, a decompression chamber 37, a liquid method unit 38, and a wind shielding plate 39 (see FIG. 2). A dope channel is formed inside the feed block 35, and the casting film 26 having a desired structure can be formed by appropriately adjusting the arrangement of the channel. The feed block 35 is attached to the casting die 36.

  As shown in FIG. 2, the casting die 36 has a discharge port 36a, and is formed in a tapered shape in which the thickness of the casting drum 22 in the drum running direction decreases toward the discharge port 36a. The casting die 36 includes a land surface 36b (see FIG. 3) in which a discharge port 36a is formed in the width direction of the casting drum 22, and a front surface 36c and a land surface 36b when viewed from the downstream side in the drum traveling direction. And a tapered surface 36d provided therebetween. The dope from the feed block 35 is cast to the casting drum 22 through the discharge port 36a. Thereby, a casting bead 40 is formed between the discharge port 36 a and the casting drum 22.

  The decompression chamber 37 is attached upstream of the casting die 36 in the drum traveling direction. The decompression chamber 37 decompresses the upstream side of the casting bead 40 in the drum running direction, and stabilizes the contact of the casting bead 40 with the casting drum 22.

  The liquid method section 38 supplies the anticoagulation liquid 41 to both ends in the width direction of the casting bead 40 to prevent the dope from solidifying and the casting bead 40 from fluttering. The liquid method unit 38 includes a tank 42, a nozzle 43, and a guide path 44. An anticoagulation liquid 41 is stored in the tank 42, and the anticoagulation liquid 41 is composed of methylene chloride and methanol. Here, the ratio of (mass of methylene chloride) / (mass of methanol) is preferably (2/3) or more and (3/2) or less. The tank 42 and the nozzle 43 are connected by a pipe 45. The pipe 45 is provided with a valve, a pump, a flow meter (all not shown) and the like, and a predetermined amount of the anticoagulation liquid 41 can be sent to the nozzle 43 by these operations. 2 and FIG. 3 and FIG. 4 shown below show a liquid method part provided on one end side of the casting bead 40. The same liquid method part is provided on the other end side of the casting bead 40. Is also provided.

  As shown in FIGS. 3 and 4, the nozzle 43 is provided on the tapered surface 36 d of the casting die 36. The tip portion 46 of the nozzle 43 is provided on the inner side of the end portion E in the width direction of the discharge port 39 a and is provided so as to be in contact with the upper end portion 44 a of the guide path 44. A supply port 46 a is formed in the distal end portion 46, and the anticoagulation liquid 41 is supplied to the guide path 44 from the supply port 46 a. By providing the nozzle 43 as described above, the anticoagulation liquid 41 from the nozzle 43 can be reliably supplied to the guide path 44 without being scattered in the air.

  In addition, although the nozzle 43 was provided inside the edge part E, if the front-end | tip part 46 of the nozzle 43 is contacting the upper end part 44a of the guide path 44, it does not need to restrict to this. The shape of the supply port 46a may be other shapes such as an ellipse in addition to the circular shape shown in FIG. Here, when the shape of the supply port 46a is circular, the diameter is preferably 0.25 mm.

  The guide path 44 is configured by a groove having a predetermined cross section. The guide path 44 is formed along an oblique line L that connects the supply port 46a of the nozzle 43 and the end E on the tapered surface 36d. In addition, the width of the guide path 44 is a tapered shape that gradually decreases from the upper end 44a toward the lower end 44b.

  The anticoagulation liquid 41 supplied from the nozzle 43 is guided from the upper end 44 a to the lower end 44 b by the guide path 44. The anticoagulation liquid 41 reaching the lower end 44b forms a liquid reservoir 41a in the vicinity of the end E due to its own weight and surface tension. When the liquid reservoir 41 a becomes large, the anticoagulation liquid 41 flows out to the end of the casting bead 40. Thereby, the anticoagulation liquid 41 is supplied to the end of the casting bead 40. Since the anticoagulation liquid 41 is sent from the nozzle 43 at a constant supply rate, the size of the liquid reservoir 41a is also substantially constant, and is continuously supplied to the end of the casting bead 40 at a constant amount according to the supply speed. The supply amount of the anticoagulation liquid 41 is preferably 0.08 cc / min or more and 0.8 cc / min or less.

  As described above, by continuously supplying the anticoagulation liquid 41 to both ends of the casting bead 40 through the liquid reservoir 41a, no burrs are generated at both ends of the casting bead 40. Further, the supply of the anticoagulation liquid 41 to both ends of the casting bead 40 suppresses the gelation of the dope at both ends, thereby improving the flexibility, so that the flutter caused by the suction air in the decompression chamber 37 is reduced. . Thereby, a uniform film with little thickness unevenness can be obtained. Note that if the liquid reservoir 41a is too large, the air flow in the vicinity of both end portions of the casting bead 40 may be obstructed. Therefore, the diameter of the liquid reservoir is preferably about 1 mm.

  In addition, although the formation of the liquid reservoir 41a is facilitated by making the width of the guide path 44 gradually tapered toward the lower end, it is not necessary to be limited to this, and it is evenly distributed from the upper end 44a to the lower end 44b. Good. Further, the shape of the cross section of the guide path 44 is not particularly limited as long as the anticoagulation liquid 41 can be reliably guided to the vicinity of the end E. For example, a groove having a V-shaped cross section or a substantially semicircular shape may be used. Further, in order to facilitate formation of the liquid reservoir 41a, a recess may be formed in the lower end portion 44b of the guide path 44. Further, the guide path 44 may be constituted by a protrusion instead of the groove.

  As shown in FIGS. 3 to 5, the wind shield plate 39 is formed of a substantially rectangular metal plate having a predetermined thickness. The wind shield plate 39 is attached to the inside of the decompression chamber 37 and is provided on the downstream side in the drum running direction in the vicinity of both ends of the casting bead 40. Further, the gap G1 between the vertical end portion 39a of the wind shield plate 39 and the casting drum 22 is substantially equal to or slightly shorter than the gap Ga between the discharge portion 36a and the casting drum 22. Further, the lateral end 39 b outside the wind shielding plate 39 is provided outside by a predetermined distance from both ends of the casting bead 40.

  By providing the wind shielding plate 39 as described above, the volume of the suction air passing through the vicinity of both ends of the casting bead 40 among the suction air flowing into the decompression chamber 36 is suppressed. Thereby, scattering of the anticoagulation liquid 41 can be prevented, and the anticoagulation liquid 41 can be supplied to both ends of the casting bead 40 without waste. Further, since the anticoagulation liquid 41 is prevented from being scattered, the anticoagulation liquid 41 does not fall onto the casting drum 22, so that the anticoagulation liquid 41 is prevented from being mixed into the casting film 26. . Thereby, generation | occurrence | production of the planar defect by mixing of anticoagulation liquid is suppressed, and the film excellent in planarity can be manufactured.

  As shown in FIG. 6, in the second embodiment of the present invention, the anticoagulation liquid 41 is supplied to both ends of the casting bead 40 without using the guide path 44 of the first embodiment. In addition, about 2nd Embodiment, it is the same as that of 1st Embodiment except not providing a guide path.

  The wind shield 48 is made of a metal plate having a predetermined thickness, like the wind shield 39 of the first embodiment, and its surface area is slightly larger than that of the wind shield of the first embodiment. The wind shield 48 is attached to the inside of the decompression chamber 37 and is provided in the vicinity of both ends of the casting bead 40 on the downstream side in the drum running direction. Further, the gap G2 between the vertical end 48a of the wind shield plate 48 and the casting drum 22 is substantially equal to or slightly shorter than the gap Ga between the discharge part 36a and the casting drum 22. The lateral end portion 48b outside the wind shielding plate 48 is provided slightly outside the lateral end portion 39b of the wind shielding plate 39 of the first embodiment.

  By providing the wind shielding plate as described above, it is possible to form a wider wind shielding area for shielding the suction air of the decompression chamber 37 than in the case of the first embodiment. Thereby, since the wind shielding effect of suction | inhalation wind increases, even if it does not use a guidance path, scattering of the coagulation prevention liquid 41 can fully be prevented.

  In the first and second embodiments, the liquid method nozzle is provided on the downstream side in the drum running direction with respect to the casting die, but instead of or in addition to this, the liquid method nozzle is provided on the side of the casting die. The anticoagulation liquid may be supplied from the side of the casting bead.

The casting die 36 is preferably the following. The shape, material, size and the like of the casting die 36 are not particularly limited, but it is preferable to use a coat hanger type because the casting width of the dope can be kept substantially uniform. Moreover, what has the discharge port 36a about 1.1 to 2.0 times with respect to the casting width of dope is preferable. From the viewpoint of durability, heat resistance, etc., it is preferable to use precipitation hardening type stainless steel, and even if it is immersed in a mixed solution of dichloromethane, methanol and water for 3 months, it does not cause pores at the gas-liquid interface. Those having such corrosion resistance are preferred. Moreover, what has the corrosion resistance equivalent to the product made from SUS316 by the forced corrosion test in electrolyte aqueous solution can be used suitably. From the viewpoint of heat resistance, it is preferable to use one having a thermal expansion coefficient of 2 × 10 ⁻⁵ (° C. ⁻¹ ) or less.

Further, it is preferable that a cured film is formed on the discharge port 36a for the purpose of improving wear resistance or the like. The method for forming the cured film is not particularly limited, and examples thereof include ceramic coating, hard chrome plating, and nitriding treatment. In the case of using ceramics as the cured film, the cured film can be ground, has a high porosity, is excellent in brittleness and corrosion resistance, and has an adhesion to the casting die 36. Although it is high, it is preferable to satisfy conditions such as low adhesion to the dope. Specific examples include tungsten carbide (WC), Al ₂ O ₃ , TiN, Cr ₂ O _{3 and the} like. Among these, WC is preferably used. The WC coating can be performed by a known thermal spraying method.

  Further, in order to form a casting film having excellent flatness, the contact surface of the dope in the casting die 36 is preferably smoothed by polishing or the like. Moreover, it is preferable to attach a suction device (not shown) to the edge portion of the casting die 36 and perform suction while setting the edge suction air volume to 1 to 100 L / min. Thereby, the flow of the wind which becomes a cause which forms an unevenness | corrugation in the surface of the casting bead 40 can be reduced.

  As shown in FIG. 1, a large number of rollers 60 are installed in the crossover portion 12, and these rollers 60 guide the wet film 27 to the pin tenter 13. A blower 61 is provided above the transport path of the wet film 27, and the blower 61 blows dry air on the wet film 27 to promote drying of the wet film 27.

  The pin tenter 13 carries and conveys both end portions (hereinafter referred to as “ear portions”) of the wet film 27 by inserting pins. During the conveyance, the wet film 27 is stretched in the width direction at a predetermined widening rate, and is dried using drying air.

  The clip tenter 14 is provided downstream of the pin tenter 13, grips and transports the ear portion of the wet film 27 with the clip, and performs drying. Thereby, the film 63 is obtained. The ear clip device 15 is provided between the pin tenter 13 and the clip tenter 14 and cuts the ear portion of the wet film 27 that has come out of the pin tenter 13. Further, the ear clip device 16 is provided between the clip tenter 14 and the drying device 17 and cuts the ear portion of the film 63 coming out of the clip tenter 14. Further, a crusher 64 is connected to the ear-cutting devices 15 and 16, and the crusher 64 crushes the ear portion into chips. The film 63 from which the ears have been cut is sent to the drying device 17. The drying device 17 includes a number of rollers 65, and the film 63 is dried while being conveyed by the rollers 65. The film 63 exiting the drying device 17 is sent to the cooling device 18 where it is cooled to approximately room temperature.

:
The above-mentioned transition part 12, pin tenter 13, clip tenter 14, and drying device 17 are connected to an adsorption recovery device 67 provided outside them. The adsorption / recovery device 67 adsorbs and recovers the solvent gas generated in the crossover part 12, the pin tenter 13, the clip tenter 14, and the drying device 17. The solvent recovered by adsorption is reused as a dope raw material.

  The winding device 19 includes a winding core 70, and the film 63 is taken up by the winding core 70. The winding device 19 includes a press roller 71, and the press roller 71 presses the film 63 that is wound around the winding core 70.

  Through the above steps, a film having excellent flatness is produced stably at high speed. The width of the film after production is preferably 1500 mm or more and 3000 mm or less. In addition, even if it is a case where the width | variety of a film exceeds 3000 mm, the effect of this invention can be acquired. Further, the thickness of the film after production is preferably 20 μm or more and 70 μm or less, more preferably 25 μm or more and 70 μm or less, and most preferably 30 μm or more and 70 μm or less.

  In the above-described embodiment, the case where a single-layer film is manufactured using one kind of dope has been described. However, the present invention is also effective when a cast film having a multilayer structure is formed. In this case, a known method such as casting a desired number of dopes simultaneously or sequentially may be used, and there is no particular limitation. Also, the structure of casting die, decompression chamber, support, co-casting, peeling method, stretching, drying method of each process, handling method, curling, winding method after flatness correction, solvent recovery method, film The collection method is described in detail in paragraphs [0617] to [0889] of JP-A-2005-104148, and the inventions according to these descriptions can also be applied to the present invention. In addition, the performance of the completed film, the degree of curling, the thickness, and the measurement methods thereof are described in paragraphs [1073] to [1087] of JP-A-2005-104148. The invention can also be applied to the present invention.

  When the completed film is used as a base and a desired functional layer is provided on both or one of the surfaces, it can be used as various functional films. Examples of the functional layer include an antistatic layer, a cured resin layer, an antireflection layer, an easy adhesion layer, an antiglare layer, and an optical compensation layer. For example, when an antireflection layer is provided, an antireflection film capable of providing high image quality by preventing reflection of light can be obtained. The functional layer and the formation method thereof are described in detail in paragraphs [0890] to [1072] of JP-A-2005-104148, and the inventions related to these descriptions also apply to the present invention. Can do. As for specific uses of the polymer film, for example, TN type, STN type, VA type, OCB type, reflective type and the like described in paragraphs [1088] to [1265] of JP-A-2005-104148, etc. For use in liquid crystal display devices.

  The dope solute and solvent produced by the dope production facility of the above embodiment are shown below.

[Solute]
It is preferable to use cellulose ester as the solute of the dope because a highly transparent film can be obtained. Examples of the cellulose ester include lower fatty acid esters of cellulose such as cellulose triacetate, cellulose acetate propionate, and cellulose acylate butyrate. Especially, it is preferable to use a cellulose acylate from the height of transparency, and it is especially preferable to use a triacetyl cellulose (TAC). Note that the dope used in this embodiment includes TAC as a polymer. Thus, when using TAC, it is preferable that 90 mass% or more of TAC is a particle | grain of 0.1-4 mm.

As the above-mentioned cellulose acylate, in order to obtain a film with higher transparency, it is preferable that the degree of substitution of the acyl group with the hydroxyl group of cellulose satisfies all of the following formulas (a) to (c). A and B in the following formula represent the substitution degree of the acyl group with respect to the hydrogen atom in the hydroxyl group of cellulose. Specifically, A is the substitution degree of the acetyl group, and B has 3 to 22 carbon atoms. The degree of substitution of the acyl group.
(A) 2.5 ≦ A + B ≦ 3.0
(B) 0 ≦ A ≦ 3.0
(C) 0 ≦ B ≦ 2.9

  The β-1,4 bonded glucose units constituting cellulose have free hydroxyl groups at the 2nd, 3rd and 6th positions. Cellulose acylate is a polymer (polymer) obtained by esterifying some or all of these hydroxyl groups with an acyl group having 2 or more carbon atoms. The degree of acyl substitution means the ratio of the esterification of the hydroxyl group of cellulose for each of the 2-position, 3-position and 6-position. The degree of substitution is 1 in the case of 100% esterification.

  The total degree of acylation substitution, that is, the value of DS2 + DS3 + DS6 is preferably 2.00 to 3.00, more preferably 2.22 to 2.90, and particularly preferably 2.40 to 2.88. The DS6 / (DS2 + DS3 + DS6) value is preferably 0.28 or more, more preferably 0.30 or more, and particularly preferably 0.31 to 0.34. Here, DS2 is a ratio in which the hydrogen of the hydroxyl group at the 2-position in the glucose unit is substituted with an acyl group, and DS3 is a ratio in which the hydrogen of the hydroxyl group at the 3-position in the glucose unit is substituted with an acyl group. DS6 is a ratio in which the hydrogen of the hydroxyl group at the 6-position in the glucose unit is substituted with an acyl group.

  Only one type of acyl group may be used for cellulose acylate, or two or more types of acyl groups may be used. When two or more kinds of acyl groups are used, it is preferable that one of them is an acetyl group. The sum of the degree of substitution of hydroxyl groups at the 2nd, 3rd, and 6th positions by acetyl groups, and the degree at which the hydroxyl groups at the 2nd, 3rd, and 6th positions are substituted by acyl groups other than acetyl groups Assuming that the total sum of DSB is DSB, the value of DSA + DSB is preferably 2.22 to 2.90, and particularly preferably 2.40 to 2.88.

  The DSB is preferably 0.30 or more, particularly preferably 0.70 or more. Further, 20% or more of the DSB is preferably the substitution degree of the 6-position hydroxyl group, more preferably 25% or more, still more preferably 30% or more, and particularly preferably 33% or more. Furthermore, the value of DSA + DSB at the 6-position of cellulose acylate is 0.75 or more, more preferably 0.80 or more, and particularly preferably cellulose acylate of 0.85 or more. When such cellulose acylate is used, a dope having excellent solubility can be prepared.

  Cellulose, which is a raw material of cellulose acylate, may be obtained from either linter cotton or pulp cotton.

  The acyl group having 2 or more carbon atoms in cellulose acylate may be an aliphatic group or an aryl group, and is not particularly limited. For example, cellulose alkylcarbonyl ester, alkenylcarbonyl ester, aromatic carbonyl ester, aromatic alkylcarbonyl ester and the like can be mentioned. Furthermore, each may have a substituted group. Preferred examples of these include propionyl group, butanoyl group, pentanoyl group, hexanoyl group, octanoyl group, decanoyl group, dodecanoyl group, tridecanoyl group, tetradecanoyl group, hexadecanoyl group, octadecanoyl group, iso-butanoyl group. , T-butanoyl group, cyclohexanecarbonyl group, olenoyl group, benzoyl group, naphthylcarbonyl group, cinnamoyl group and the like. Among these, a propionyl group, a butanoyl group, a dodecanoyl group, an octadecanoyl group, a t-butanoyl group, an oleoyl group, a benzoyl group, a naphthylcarbonyl group, a cinnamoyl group, and the like are more preferable, and a propionyl group and a butanoyl group are particularly preferable. .

  The details of the cellulose acylate that can be used in the present invention are described in paragraphs [0140] to [0195] of JP-A-2005-104148, and the inventions related to these descriptions are also included in the present invention. Can be applied.

[solvent]
As the dope solvent, an organic compound capable of dissolving the polymer is preferably used. However, in the present invention, the dope means a mixture obtained by dissolving or dispersing a polymer in a solvent, and thus can be used for a solvent having low solubility with the polymer. Solvents that can be suitably used include, for example, aromatic hydrocarbons such as benzene and toluene, halogenated hydrocarbons such as dichloromethane, chloroform, and chlorobenzene, alcohols such as methanol, ethanol, n-propanol, n-butanol, and diethylene glycol. , Ketones such as acetone and methyl ethyl ketone, esters such as methyl acetate, ethyl acetate and propyl acetate, ethers such as tetrahydrofuran and methyl cellosolve, and the like. Two or more kinds of solvents may be selected from these solvents and mixed solvents may be used. Among these, use of dichloromethane is preferable because a dope having excellent solubility can be obtained, and the solvent in the cast film can be volatilized in a short time to form a film.

  As said halogenated hydrocarbon, a C1-C7 thing is used preferably. Furthermore, from the viewpoints of compatibility with the polymer, stripping property indicating ease of stripping of the cast film stripped from the support, mechanical strength of the film, optical properties, etc., alcohol having 1 to 5 carbon atoms in dichloromethane. It is preferable to use one or a mixture of several kinds. The content of alcohol is preferably 2 to 25% by weight, more preferably 5 to 20% by weight, based on the solvent. Specific examples of the alcohol include methanol, ethanol, n-propanol, isopropanol, n-butanol, etc. Among them, it is preferable to use methanol, ethanol, n-butanol, or a mixture thereof.

  Recently, a solvent composition not using dichloromethane has been proposed in order to minimize the influence on the environment. For this purpose, ethers having 4 to 12 carbon atoms, ketones having 3 to 12 carbon atoms, and esters having 3 to 12 carbon atoms are preferable, and these are preferably used by being mixed appropriately. These compounds may have a cyclic structure, and compounds having two or more functional groups of ether, ketone, and ester, that is, -O-, -CO-, and -COO- are also used as a solvent. be able to. In addition, the solvent may have another functional group such as an alcoholic hydroxyl group. In addition, when it has two or more types of functional groups, the carbon number should just be in the prescription | regulation range of the compound which has either functional group, and it does not specifically limit.

  Depending on the purpose, the dope may be added with various known additives such as a plasticizer, an ultraviolet absorber (UV agent), a deterioration preventing agent, a slipping agent, and a peeling accelerator. For example, as the plasticizer, phosphate plasticizers such as triphenyl phosphate and biphenyldiphenyl phosphate, phthalate plasticizers such as diethyl phthalate, and various known plasticizers such as polyester polyurethane elastomers are used. be able to.

  Moreover, it is preferable to add fine particles to the dope for the purpose of preventing adhesion between films or adjusting the refractive index. As the fine particles, a silicon dioxide derivative is preferably used. The silicon dioxide derivative in the present invention includes silicon dioxide and a silicone resin having a three-dimensional network structure. As such a silicon dioxide derivative, it is preferable to use an alkylated surface. Fine particles that have been subjected to a hydrophobization treatment such as an alkylation treatment are excellent in dispersibility in a solvent, so that a dope can be prepared without agglomeration between the fine particles, and a film can be produced. It is possible to produce a film having a small number of defects and a high transparency.

  As described above, as the fine particles whose surface is alkylated, for example, Aerosil R805 (manufactured by Nippon Aerosil Co., Ltd.) which is commercially available as a silicon dioxide derivative having an octyl group introduced on its surface can be used. . In order to obtain a highly transparent film while ensuring the effect of adding fine particles, the content of fine particles with respect to the solid content of the dope is preferably 0.2% or less. Further, the average particle diameter is preferably 1.0 μm or less, more preferably 0.3 to 1.0 μm, and particularly preferably 0.4 to 0.00, so that the fine particles do not hinder the passage of light. 8 μm.

  As described above, in the present invention, it is preferable to prepare a dope using TAC as a polymer in order to obtain a highly transparent polymer film. In this case, it is preferable that the ratio containing TAC is 5 to 40% by weight with respect to the total amount of the dope after mixing the solvent, additives, and the like, more preferably, the ratio containing TAC is 15 to 15%. 30% by weight, particularly preferably 17 to 25% by weight. Moreover, it is preferable to make the ratio which contains an additive (mainly a plasticizer) into 1 to 20 weight% with respect to the whole solid content including the polymer, other additives, etc. which are contained in dope.

  Note that various additives such as solvents, plasticizers, ultraviolet absorbers, deterioration inhibitors, slipping agents, release accelerators, optical anisotropy control agents, retardation control agents, dyes, release agents, and the like, and fine particles are disclosed in JP-A-2005. No. 104148, paragraphs [0196] to [0516] describe in detail, and the invention according to these descriptions can also be applied to the present invention. Similarly, materials, raw materials, additive dissolution methods and addition methods, filtration methods, defoaming, and the like are described in detail in paragraphs [0517] to [0616] of JP-A-2005-104148. The inventions according to these descriptions can also be applied to the present invention.

  Hereinafter, the present invention will be specifically described with reference to examples. However, the present invention is not limited to these examples.

  The film 63 was manufactured in the film manufacturing facility 10 shown in FIG. An appropriate amount of the dope was sent from the dope production facility 23 to the casting die 36 through the feed block 35. The dope was cast from the casting die 36 onto the continuously rotating casting drum 22 to form the casting film 26. At this time, the discharge amount of the dope was adjusted so that the thickness of the dried film 63 was 60 μm.

  As shown in FIG. 2, the discharge port 36a of the casting die 36 has a predetermined shape and a width of 1.8 m. The temperature of the dope at the time of casting was set to 36 ° C. The internal temperature of the feed block 35 was set to 36 ° C. The pressure on the upstream side of the casting bead 40 in the drum running direction was reduced to −600 Pa by the decompression chamber 37.

  As shown in FIGS. 3 and 4, a pool 41 a of the anticoagulation liquid 41 is formed in the vicinity of both ends of the discharge port 36 a of the casting die 36 using the guide path 44. By this liquid reservoir 41a, the anticoagulation liquid 41 was continuously supplied to both ends of the casting bead 40. At this time, the supply speed of the anticoagulation liquid supplied from the nozzle 43 was set to 0.2 cc / min.

  As shown in FIGS. 3 to 5, the wind shield plate 39 is attached to the inside of the decompression chamber 37 so that a part of the casting bead 40 is on the near side when viewed from the downstream side in the drum traveling direction. The wind shield plate 39 prevented the anticoagulation liquid 41 from scattering.

  As the casting drum 22 shown in FIG. 1, a stainless steel drum capable of controlling the rotation speed was used. The surface temperature of the casting drum 22 was set to −10 ° C. by supplying the refrigerant from the heat transfer medium supply device into the casting drum 22. The temperature inside the casting chamber 11 was always 35 ° C. using the temperature control device 33.

  When the casting film 26 was cooled and gelled and became self-supporting, the casting film 26 was peeled off as a wet film 27 by the peeling roller 28. While the wet film 27 is fed to the crossover part 12 and conveyed while being supported by a plurality of rollers 60 provided in the crossover part 12, dry air whose temperature is adjusted to 40 ° C. is supplied from the blower 61 to supply the wet film 27. Was dried.

  A pin was inserted into the ear portion of the wet film 27 sent to the pin tenter 13, and the wet film 27 was conveyed while holding the ear portion. In addition, during transportation, the wet film 27 was stretched in the width direction and dried using dry air.

The wet film 27 that passed through the pin tenter 13 was sent to the clip tenter 14. In the clip tenter 14, the ear portion of the wet film 27 was conveyed while being gripped by the clip, and drying was performed during the conveyance. As a result, a film 63 was obtained. The ears of the wet film 27 and the film 63 were cut using the ear-cutting devices 13 and 14. The cut ears were sent to a crusher 64 through a cut tab lower (not shown) and crushed into chips having an average of about 80 mm ² .

  A preliminary drying chamber (not shown) was provided between the ear opener 14 and the drying device 17, and the film 63 was preheated by supplying a drying air at 100 ° C. and then sent to the drying device 17. In the drying device 17, the film 63 is conveyed while being wound around a plurality of rollers 65, and drying is performed during the conveyance. The internal temperature of the drying device 17 was adjusted so that the film surface temperature of the film 63 was 140 ° C. The drying time of the film 63 in the drying device 17 was 10 minutes. The film surface temperature of the film 63 was measured using a thermometer (not shown) provided immediately above the conveyance path of the film 63 and in the vicinity of the surface.

  The adsorption / recovery device 67 was connected to the crossover part 12, the pin tenter 13, the clip tenter 14, and the drying device 17. This adsorption / recovery device 67 has an adsorbent made of activated carbon and a desorbent made of dry nitrogen (all not shown), and the solvent generated in the crossover portion 12, the pin tenter 13, the clip tenter 14, and the drying device 17. After recovering the gas, the water in the solvent gas was removed until the water content reached 0.3% by weight.

  A humidity control chamber (not shown) is provided between the drying device 17 and the cooling device 18, and air having a temperature of 50 ° C. and a dew point of 20 ° C. is supplied to the film 63. % Air was blown to adjust the humidity, and the curl generated in the film 63 was corrected. Next, the film 63 was sent to the cooling device 18, and the film 63 was gradually cooled until it became 30 degreeC.

  The film 63 was sent to the winding device 19 and wound with a roll of 169 mm while applying a pressing force of 50 N / m to the film 63 by the press roller 71. At the time of winding, the tension at the start of winding of the film 63 was 300 N / m, and the tension at the end of winding was 200 N / m. Thus, a roll-shaped film 63 was obtained.

  The completed film had a film thickness of 60 μm and a width of 1.8 m. Note that the average drying time of the cast film, the wet film, and the film was 20 wt% / min throughout the entire film forming process.

The mass parts of the raw materials used in this example are as follows. In addition, as a solvent for dope preparation, after preparing a mixed solvent in which methylene chloride (first solvent), methanol (second solvent), and n-butanol (third solvent) are mixed, a solvent tank (illustrated) is prepared. Omission) was used.
TAC (substitution degree 2.86, viscosity average polymerization degree 306, water content 0.2 mass%, viscosity 315 mPa · s 6 mass% in dichloromethane solution, average particle diameter 1.5 mm, standard deviation 0.5 mm) Powdered powder) 100 parts by mass Methylene chloride (first solvent) 400 parts by mass Methanol (second solvent) 77 parts by mass n-butanol (third solvent) 5 parts by mass Plasticizer A: (Triphenyl phosphate) 7.6 parts by mass Plasticizer B: (Diphenyl phosphate) 3.5 parts by mass

  The TAC used here has a residual acetic acid content of 0.1% by mass or less, a Ca content of 80 ppm, a Mg content of 42 ppm, a Fe content of 0.5 ppm, free acetic acid 40 ppm, and sulfate ions. Was 15 ppm. The acetone extract was 8% by mass, and the weight average molecular weight / number average molecular weight ratio was 2.7. The yellow index was 6.0, the haze was 0.08, the transparency was 93.5%, the Tg (glass transition temperature; measured by DSC) was 160 ° C., and the crystallization exotherm was 6.4 J / g. It was. This TAC synthesized cellulose triacetate from cellulose collected from pulp.

[Comparative example]
In contrast to the above example, a film was formed under the same conditions as in the example except that the wind shielding plate was omitted.

  Hereinafter, an example and a comparative example will be described in comparison. In the example having the wind shield, the wind sucked to the side of the casting bead was suppressed by the wind shield, and as a result, the anticoagulation liquid was not scattered, and the occurrence of river burr and ear lump was suppressed. Further, since the anticoagulation liquid is not scattered on the support, the anticoagulation liquid is not mixed with the cast film. As a result, the occurrence of planar failure was suppressed. On the other hand, in the comparative example in which the wind shielding plate was omitted, in addition to the occurrence of burrs and ears, a sheet failure occurred due to the anticoagulation liquid falling on the support being mixed into the casting film.

It is the schematic which shows a film manufacturing equipment. It is a front view which shows the casting die in 1st Embodiment, and its vicinity. It is sectional drawing which shows the front-end | tip part of the casting die in the 1st Embodiment, and its vicinity. It is a side view which shows the front-end | tip part of the width direction of the casting die in 1st Embodiment, and its vicinity. It is a bottom view which shows the front-end | tip part of the width direction of the casting die in 1st Embodiment, and its vicinity. It is a side view which shows the front-end | tip part of the width direction of the casting die in 2nd Embodiment, and its vicinity.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Film production equipment 22 Casting drum 25 Casting unit 36 Casting die 36a Discharge port 36b Land surface 36c Front 36d (casting die when viewed from the downstream side in the running direction of the casting drum) Tapered surface 37 Decompression chamber 39 , 48 Wind shield plate 40 Casting bead 41 Anticoagulation liquid 41a Liquid reservoir 43 Nozzle 44 Guide path

Claims (8)

On the support that runs endlessly, a dope containing a polymer and a solvent is discharged from the discharge part of the casting die, and a casting bead is formed between the discharge part of the casting die and the support. The casting film is formed on the support, the upstream side of the casting bead in the running direction of the support is depressurized by a decompression chamber, and the casting film is peeled off as a wet film from the support. In the solution casting method for obtaining a film by drying the wet film after removal,
Supply anticoagulation liquid to the support width direction both ends of the casting bead by the anticoagulation liquid supply means,
The windshield bead flows into the decompression chamber from both ends of the casting bead in the width direction of the support by a wind shielding member provided in the vicinity of both ends of the casting bead in the width direction of the support. A solution casting method characterized in that the suction air to be blocked is blocked to prevent the anticoagulation liquid from scattering.   The solution casting method according to claim 1, wherein the wind shielding member is attached to the inside of the decompression chamber.   The supply of the anticoagulation liquid to both ends of the casting bead in the width direction of the support is performed by a downstream liquid method nozzle provided on the downstream side in the running direction of the support with respect to the discharge portion of the casting die. 3. The solution casting method according to claim 1 or 2, wherein A guide path for guiding the anticoagulation liquid from the liquid discharge port of the downstream liquid method nozzle toward both ends of the casting bead in the width direction of the support body, and the support body of the casting bead by the guide path; Forming a pool of the anticoagulation liquid on the downstream side in the support running direction with respect to both ends in the width direction;
4. The solution casting method according to claim 1, wherein the anticoagulation liquid is supplied to both ends of the casting bead in the width direction of the support through the liquid pool.   5. The solution casting according to claim 1, wherein the polymer is cellulose acylate, and the supply rate of the anticoagulation liquid is 0.08 cc / min to 0.8 cc / min. Method.   6. The coagulation preventing liquid is a mixed solvent of methylene chloride and methanol, and the ratio of methylene chloride / methanol is (2/3) or more and (3/2) or less. The solution casting method according to claim 1.   The travel speed of the support is set to 50 m / min or more, the thickness of the film is set to 20 μm or more and 70 μm or less, and the width thereof is set to 1.5 m or more and 3.0 m or less. The solution casting method according to the item. On the support that runs endlessly, a dope containing a polymer and a solvent is discharged from the discharge part of the casting die, and a casting bead is formed between the discharge part of the casting die and the support. The casting film is formed on the support, the upstream side of the casting bead in the running direction of the support is depressurized by a decompression chamber, and the casting film is peeled off as a wet film from the support. In the solution film-forming equipment to obtain a film by drying the wet film after removal,
Anticoagulation liquid supply means for supplying an anticoagulation liquid to both ends of the casting bead in the support width direction;
Provided in the vicinity of both ends of the casting bead in the width direction of the support and upstream in the running direction of the support, and blocks suction air flowing into the decompression chamber from both ends of the casting bead in the width direction of the support. And a wind shielding member for preventing scattering of the anticoagulation liquid.

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