JP2008087474A - Method and equipment for manufacturing polymer film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To stably manufacture a film of good quality reduced in flaw or surface unevenness at a high speed. <P>SOLUTION: A dope is cast on a running casting drum 34 from the discharge port of a casting die 33 and the casting drum 34 is not electrically earthed. A DC high voltage is applied to the casting drum 34 from a voltage applying device 36 to generate an electric field on the surface of the casting drum 34. Since the dope is charged corresponding to a contained polymer or the like, the bead being the dope issued from the discharge port is attracted to the casting drum 34. By this constitution, the adhesiveness of the bead and the casting drum 34 is enhanced to suppress the involution of air. When the cast film 12 peeled from the casting drum 34 is dried, the film of good quality reduced in flaw such as a gap or the like and showing excellent flatness can be stably manufactured at a high speed. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a polymer film production method and production equipment.

  For example, a protective film for protecting the surface of the polarizing plate, a retardation film for correcting light misalignment, an antireflection film, etc. on the surface of the polarizing plate which is a main component of a liquid crystal display (LCD) Although polymer films for applications are being used, the demand for LCD films has been increasing along with a significant increase in demand for LCDs. In the following description, the polymer film is simply referred to as a film, and the polymer film for optical use is referred to as an optical film.

  As a method for producing a polymer film, a solution casting method and a melt casting method are generally used. The melt film-forming method is a method in which polymer pellets are heated and melted and then extruded to produce a film, which is excellent in productivity and can be manufactured with simple equipment. However, it is difficult to reduce the transparency of the film or to produce a film having a uniform film thickness. Therefore, as a method for producing an optical film requiring high transparency, a solution casting method is mainly used.

  In the solution casting method, a cast film formed by casting a dope, which is a mixed liquid in which a polymer, a solvent and an additive are mixed, is formed on a traveling support, and then the cast film peeled off from the support is formed. It is a method of drying into a film. In this method, it is important to produce a film having high transparency and excellent quality such as excellent flatness, but in advance, improvement in productivity by increasing the film forming speed is desired, As part of this, studies have been made to improve the dope casting speed. However, if the casting speed of the dope is increased, air is entrained in the bead that is the flow of the dope from the discharge port to the support, and voids are generated inside the casting film, or irregularities are generated on the surface thereof. There is a problem that the flatness is lowered.

Therefore, as a method for suppressing the entrainment of air, for example, Patent Document 1 proposes a method in which an electrode is provided in the vicinity of the discharge port and a voltage is applied between the bead and the support in an environment in which the oxygen concentration is regulated. Has been. Patent Document 2 discloses a method for reducing the pressure in the vicinity of a bead while rectifying by controlling the pressure in each section using a pressure reducing device having a suction port having a plurality of sections in the width direction of the bead. Has been proposed.
JP 2001-113544 A JP 2002-103359 A

  However, in Patent Document 1, since the electrode is provided in the vicinity of the bead, the solvent gas or additive volatilized from the dope adheres to the electrode or the electrode deteriorates while the film is continuously formed. Thus, it becomes difficult to apply a voltage. Therefore, the method of patent document 1 has the problem that the effect which suppresses entrainment of air falls. Further, just using an apparatus such as a decompression chamber as in Patent Document 2 has a weak effect of suppressing the entrainment of air, and further, as the film forming speed is increased, the vicinity of both ends of the bead undulates and becomes unstable. Therefore, there is a problem that a cast film having poor planarity is formed.

An object of the present invention is to provide a method for producing a polymer film, which can form a cast film while suppressing air entrainment and can produce a film having few defects and excellent flatness at high speed and stably. .

  The method for producing a polymer film of the present invention comprises a bead between a casting die and a support by discharging a dope containing a polymer, a solvent and an additive onto a continuously running support from the casting die. And forming a cast film by casting the bead onto the support, and connecting the support to the support by drying the cast film after peeling off from the support to form a film. Casting is performed while applying a voltage to the support using the applied voltage applying device.

  It is preferable that the support is electrically ungrounded and an electric insulating film is provided on the surface of the support. The surface potential V of the support is preferably 0.1 kV <| V | <3 kV.

  In addition, it is preferable that the bead is brought into close contact with the surface of the support using an adhesion device disposed near the surface of the support. The contact device is preferably a decompression chamber disposed in the vicinity of the discharge port in order to decompress the back of the bead. In order to form an intervening film by supplying a liquid containing at least one solvent contained in the dope between the support and the casting film, the close-contacting device is disposed upstream of the landing point of the bead on the support. It is preferable to use an intervening film forming apparatus. The electrical insulating film preferably has a multilayer structure.

  The polymer film production facility of the present invention is a bead between a casting die and a support by discharging a dope containing a polymer, a solvent and an additive onto a continuously running support from the casting die. A casting film forming apparatus for forming a casting film by casting a bead on a support, and a drying apparatus for drying the casting film after peeling off from the support to form a film. And a voltage applying device that is connected to the support and applies a voltage to the support during casting.

  According to the present invention, it is possible to form a casting film at a high speed while attracting the beads to the surface of the support and suppressing air entrainment. Further, by drying the cast film, a film having few defects and excellent flatness can be produced at high speed and stably.

  The manufacturing method of the polymer film which concerns on this invention is demonstrated concretely, showing embodiment. FIG. 1 is a schematic diagram of a film manufacturing facility 10 used in the present embodiment.

  The film manufacturing equipment 10 is dried while a casting chamber 14 for casting a dope is formed on a traveling support to form a casting film 12 and the casting film 12 peeled off from the support is conveyed. A tenter 19 for promoting drying and forming a film 18 while transporting the casting film 12 holding both side ends by fixing means, and both end parts of the film 18. Ear cutting device 20 for cutting the film 18, a drying chamber 22 for sufficiently drying the film 18, a cooling chamber 23 for cooling the dried film 18, and a forcing to adjust the charged voltage of the film 18 A static eliminating device 25, a knurling roller 26 for applying knurling to the film 18, and a winding chamber 28 for winding the film 18 in a roll shape are provided. The film manufacturing facility 10 is connected to the dope manufacturing facility 30 via a pipe serving as a dope flow path, and has a structure in which an appropriate amount of dope is appropriately fed.

  The casting chamber 14 has a feed block 31 into which the dope is fed from the dope manufacturing facility 30, a slit-like discharge port, a casting die 33 for discharging the dope onto the support from the discharge port, and a support. A casting drum 34 acting as a casting roller, a peeling roller 38 for supporting the casting film 12 peeled off from the casting drum 34, and a condenser (for condensing and liquefying the solvent gas floating in the casting chamber 14). (Condenser) 40 and a recovery device 41 for recovering the liquefied solvent. In addition, a heat transfer medium supply for supplying a heat transfer medium whose temperature is adjusted to a flow path formed in the casting drum 34 in order to adjust the surface temperature of the casting drum 34. A device (not shown) is connected. Further, a temperature control device 43 for adjusting the internal temperature of the casting chamber 14 is attached to the outside of the casting chamber 14.

  A dope channel is formed inside the feed block 31. By adjusting the arrangement of the flow paths, the casting film 12 having a desired structure can be formed. A decompression chamber 45 is attached to the casting die 33. The decompression chamber 45 is used for decompressing the rear of the bead, which is the flow of the dope from the discharge port to the casting drum 34. A jacket (not shown) for adjusting the internal temperature by flowing a heat transfer medium whose temperature is adjusted is provided on the outer surface of the decompression chamber 45, and by adjusting the internal temperature, a dope or a cast film is provided. The solvent gas volatilized from 12 is prevented from adhering to the surface.

The shape, material, size and the like of the casting die 33 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 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 liquid of dichloromethane, methanol, and water for 3 months, it creates pores at the gas-liquid interface. Those having a corrosion resistance such that they do not occur are preferred. A material having corrosion resistance substantially equivalent to that of SUS316 in a forced corrosion test with an aqueous electrolyte solution can also be suitably used. 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.

A cured film is preferably formed at the tip of the discharge port 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. When ceramics are used as the cured film, grinding is possible, porosity is low, furthermore, brittleness and corrosion resistance are excellent, and adhesion to the casting die 33 is high, but adhesion to the dope is high. Those satisfying the conditions such as low degree are preferable. Specific examples include tungsten carbide (WC), Al ₂ O ₃ , TiN, Cr ₂ O _3, etc. Among them, it is preferable to use WC. The WC coating can be performed by a known thermal spraying method.

  In order to form the casting film 12 having excellent planarity, the contact surface of the dope in the casting die 33 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 33 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 on the surface of a bead can be reduced.

  The casting drum 34 preferably has a function capable of continuous running. In this embodiment, the casting drum 34 is used as a support, but the form of the support is not particularly limited. For example, the support drum 34 is wound around a pair of rollers including one drive roller, and is endless. The casting band that travels in the above can be suitably used as a support. In addition, regardless of the form of the support, the dimensions and materials are not particularly limited, but those having a width of about 1.1 to 2.0 times the casting width of the dope are preferable, Stainless steel is preferred from the standpoint of corrosion resistance and high strength. Furthermore, in order to form a cast film having excellent flatness, the surface is preferably polished as much as possible. In this embodiment, a stainless steel drum that can be continuously rotated by a driving device (not shown) is used to continuously rotate the dope while it is cast.

  A voltage applying device 36 for carrying out the present invention is connected to the casting drum 34. An electric field is generated from the casting drum 34 by applying a DC high voltage to the casting drum 34 using the voltage application device 36. Activation / deactivation of application by the voltage application device 36 is controlled by the controller 52. Further, the casting drum 34 is provided as an electrically ungrounded. Thereby, the charged state of the casting drum 34 is maintained.

  A plurality of transport rollers for supporting the casting film 12 and an air blower 54 for blowing dry air to the transported film 12 to be transported are arranged in the crossing portion 16. The tenter 19 includes a pair of chains (not shown) including a pin plate having a plurality of pins as fixing means for fixing both side ends of the casting film 12, and the internal temperature of the tenter 19. A temperature control device (not shown) for adjustment is provided. The chain is wound around a pair of rails arranged so that the width gradually increases from the entrance to the exit of the tenter 19 and travels inside the tenter 19 according to the rails.

  A crusher 56 for pulverizing both side ends of the cut film 18 as a chip is connected to the ear clip device 20. Inside the drying chamber 22 are provided with a plurality of rollers 58 for winding and transporting the film 18 and a temperature controller (not shown) for adjusting the internal temperature. An adsorption recovery device 59 for adsorbing and recovering the solvent gas volatilized from the film 18 is attached. The take-up chamber 28 is provided with a take-up roller 62 having a press roller 61 for applying a pressing force to the film 18.

  The flow of manufacturing the film 18 using the film manufacturing facility 10 will be specifically described. The dope prepared in the dope manufacturing facility 30 is sent to the casting die 33 through the feed block 31.

  FIG. 2 is a schematic view of the vicinity of the casting portion of the dope. As shown in FIG. 2, the inside of the casting chamber 14 is partitioned by a labyrinth seal 65 so as to surround a casting portion including a casting die 33 having a dope discharge port and a decompression chamber 45. It is suppressed that the bead surface shape fluctuates under the influence of the wind generated in the casting chamber 14 as the rolling drum 34 travels.

  A DC high voltage is applied from the voltage application device 36 to the casting drum 34. The surface potential V of the casting drum 34 is adjusted to 0.1 kV <| V | <3 kV by adjusting the application amount of the voltage application device 36. When the dope is discharged from the casting die 33 toward the casting drum 34, the beads are attracted to the casting drum 34. Thereby, since the adhesiveness between both improves, entrainment of air is suppressed. However, when V is less than 0.1 kV, only a weak force can be applied between the bead and the casting drum 34, so it is difficult to suppress air entrainment. On the other hand, if V exceeds 3 kV, the bead is attracted to the casting drum 34 with an excessive force, resulting in unevenness in the surface shape, which is inappropriate.

  The electrical insulating film 70 is a film having electrical insulation formed by melting and vapor-depositing an insulating material. As described above, the electric insulating film 70 is provided on the peripheral surface of the casting drum 34 to be cast, and the above-described discharge treatment is performed, thereby forming a dendritic discharge path along the surface of the electric insulating film 70. In addition, the stainless steel casting drum 34 can be easily charged. The electrical insulating film 70 is formed by melting and vapor-depositing an insulating material. The insulating material is not particularly limited, and examples thereof include ceramics, PTFE, and plastic. The ceramic includes alumina, zirconia, chromium oxide, titania, or a mixture including at least any two of them. The formation method, film thickness, and the like are not particularly limited, but are preferably formed so as to have a uniform film thickness over the entire surface of the casting drum 34. The electrical insulating film 70 of this embodiment is a film formed by melting and bonding ceramics mainly composed of alumina.

  The electrical insulating film 70 preferably has a multilayer structure instead of a single layer structure. For example, it is more preferable to have a multilayer structure including a first layer 70a that is in contact with the casting film 12 and a second layer 70b that overlaps the first layer 70a and is thicker than the first layer 70a. It is preferable that the exposed surface of the first layer 70a is smooth in order to make the surface in contact with the first layer 70a of the casting film 12 as smooth as possible. This is because if the surface of the casting film 12 is rough, the surface of the obtained film 18 (see FIG. 1) often becomes rough. In order to form the first layer 70a made of ceramics so that the exposed surface becomes smooth, it is preferable to use ceramics of particles having a small particle size as a raw material. The same applies when PTFE is used instead of ceramics as the material of the first layer 70a.

  The smaller the particle size of the ceramic or PTFE used for the first layer 70a, the easier it is for the first layer 70a to break or it tends to be cracked. This tendency increases as the first layer 70a is made thicker in order to provide electrical insulation to the peripheral surface of the casting drum 34. Therefore, the second layer 70b is provided inside the first layer 70a, that is, the second layer 70b is provided as a layer that is not exposed in contact with the casting drum 34. The second layer 70b is formed of ceramics or PTFE having a larger particle size than the material of the first layer 70a. As a result, the electrical insulating film 70 is formed smoothly without cracking, and cracks are less likely to occur even after long-term use. Then, the electrical insulating film 70 has a multi-layer structure of the first layer 70a and the second layer 70b made of the material as described above, so that the exposed surface is smooth and the electrical insulation is large. be able to. Note that a plurality of the second layers 70b may be provided.

  While the casting film 12 is formed, the oxygen concentration inside the casting chamber 14 is always measured using the oxygen concentration meter 53, and the oxygen concentration in the casting chamber 14 is always measured to be less than 10% by weight. The inflow of nitrogen gas is adjusted according to the value. This reduces the risk of fire and explosion in the casting chamber 14. The oxygen concentration can be easily adjusted by supplying an inert gas such as nitrogen gas or carbon dioxide gas or a mixed gas obtained by mixing an inert gas and air into the casting chamber 14. When the oxygen concentration becomes 10% by weight or more for some reason, an alarm is issued and the measured value is sent to the controller 52 to stop the application by the voltage application device 36.

  At the time of casting, the decompression chamber 45 is used to adjust the pressure behind the bead to be lower than the atmospheric pressure. As a result, the bead is drawn rearward, that is, toward the casting drum 34, so that the air entrainment is further suppressed and the flow of the wind in the vicinity of the bead is reduced, and the bead flows while suppressing the surface fluctuation. Can be extended. Further, as described above, since the casting part is surrounded by the labyrinth seal 65, the pressure in the vicinity of the bead can be efficiently reduced by the decompression chamber 45. The rear of the bead is preferably set to (atmospheric pressure −2000 Pa) or more (atmospheric pressure −10 Pa) or less.

  Further, an intervening film forming device 71 is provided upstream of the casting die 33 in the traveling direction of the casting drum 34. The intervening film forming apparatus 71 supplies a predetermined liquid onto the casting drum 34 before the casting film 12 is formed, and forms the intervening film 72 on the casting drum 34. As the liquid, a liquid containing at least one solvent contained in the dope is preferably used. Since the bead is cast on the casting drum 34 via the intervening film 72, the casting film 12 can be formed while suppressing the entrainment of air, and the casting drum 34 and the casting film 12 can be formed. The degree of close contact is indirectly controlled, and excessive contact between the two is suppressed. Therefore, the casting film 12 can be easily peeled off from the casting drum 34 only by applying a small peeling stress in the subsequent process. Since the intervening film 72 diffuses toward the casting film 12 with the passage of time, the consistency at the interface between the casting film 12 and the intervening film 72 is high, and there is no fear of dissociation or the like.

  The surface temperature of the casting drum 34 is substantially constant in the range of −40 to 30 ° C. In this embodiment, it adjusts to -10 degreeC by supplying the heat-transfer medium which adjusted temperature from the refrigerant | coolant supply apparatus to the flow path formed in the casting drum 34 inside. Moreover, it is preferable that dope at the time of casting is substantially constant in the range of −10 to 55 ° C. It can be easily adjusted by adjusting the internal temperature of the feed block 31 and the casting die 33, and the temperature of the dope here is -5 ° C. Thereby, the bead is efficiently and effectively cooled on the casting drum 34, and the gel-like casting film 12 is formed in a short time.

  By forming the intervening film 72 in this way, the degree of adhesion between the casting film 12 and the casting drum 34 can be suitably adjusted. In the case of forming the intervening film 72, when the ratio of the good solvent contained in the intervening film forming liquid is w (%) and the thickness of the intervening film 72 is t (μm), w and t are , T <−0.05w + 15 is preferably satisfied. Thereby, it is possible to form the intervening film 72 that acts so that the casting film 12 can be easily peeled off from the casting drum 34. However, if the intervening film 72 is too thick, diffusion between the casting film 12 and the intervening film 72 hardly occurs, and the intervening film 72 may remain on the casting drum 34. If the intervening film 72 remains on the casting drum 34 in this way, the surface shape of the film is lowered because it adversely affects the subsequent casting. Moreover, the installation location of the intervening film forming apparatus 71 is not particularly limited, and for example, it may be provided in the vicinity of the casting die 33 so that the liquid can be supplied along the back surface of the bead.

  The contact device that adjusts the contact degree between the casting drum 34 and the casting film 12 may be provided with an air knife instead of or in addition to the intervening film forming device 71. When using an air knife, it is preferable to blow wind on the casting film 12 formed on the downstream side of the casting drum 34 in the traveling direction of the bead. Here, the degree of adhesion between the casting film 12 and the surface of the casting drum 34 can be appropriately adjusted by adjusting the air blowing speed and the air volume.

  It is preferable to attach a solvent supply device (not shown) to the end of the discharge port to supply a desired solvent to both ends of the bead and to the gas-liquid interface between the discharge port and the outside air. As the solvent, a solvent capable of dissolving the dope is preferably used, and examples thereof include a mixture of 86.5 parts by weight of dichloromethane, 13 parts by weight of methanol, and 0.5 parts by weight of n-butanol. . Thereby, since dope does not dry locally and solidify, a bead can be formed stably. In addition, since the possibility that the solidified dope is mixed as a foreign substance in the bead or the casting film 12 is reduced, the film 18 having no defect and high transparency can be obtained. Moreover, when supplying the above mixture, the supply amount is in the range of 0.1 to 1.0 mL / min for each side of the end of the discharge port using a pump having a pulsation rate of 5% or less. It is preferable to supply so that it becomes.

  The solvent gas floating in the casting chamber 14 is condensed and liquefied using the condenser 40 and then recovered by the recovery device 41. Thereby, the effect of reducing the solvent gas in the casting chamber 14 is acquired. The recovered solvent is regenerated by a regenerator (not shown) and reused as a dope preparation solvent. Thereby, reduction of material cost is implement | achieved. The internal temperature of the casting chamber 14 is preferably made substantially constant in the range of −10 to 57 ° C. by the temperature control device 43.

  The casting film 12 on the casting drum 34 is further cooled and gelled with time. Then, the casting film 12 which has been gelled and has self-supporting property is peeled off from the casting drum 34 while being supported by the peeling roller 38. The cast film 12 immediately after stripping preferably has a residual solvent amount of 10 to 200% by mass. The amount of residual solvent is the amount of main solvent in the target sample such as a cast film or film. If there is a lot of solvent in the sample, the solvent with the highest content is considered the main solvent. The amount of residual solvent is based on the dry weight, and is calculated as {(xy) / y} × 100 where x represents the weight of the sample at the time of collection and y represents the weight after the sample is completely dried. Value.

  The stripped cast film 12 is sent to the crossing section 16, and while being supported and transported by a plurality of transport rollers, drying air is blown from the blower 54 to accelerate drying. By setting the temperature of the drying air to be substantially constant within a range of 20 to 250 ° C., the casting film 12 can be effectively dried without causing thermal damage. In addition, the rotation speed of the conveyance roller disposed near the outlet is made faster than the conveyance roller disposed on the entrance side of the crossing portion 16. Thereby, tension is applied in the transport direction of the casting film 12, so that the film can be transported without causing wrinkles or wrinkles on the surface of the casting film 12.

  The cast film 12 whose drying has been promoted is sent to a tenter 19, and a plurality of pins are pierced and fixed at both ends near the entrance. The temperature in the tenter 19 is adjusted in advance by a temperature control device (not shown). Since the rail is installed so that the width increases as it goes from the inlet of the tenter 19 toward the outlet, the casting film 12 is gradually expanded in the width direction while being conveyed along the rail. As a result, the casting film 12 is controlled in the molecular orientation in the width direction and promotes drying, and becomes a film 18 having a high retardation value. In addition, you may make it extend | stretch the width direction with a shrinkage machine, without performing expansion extending | stretching by a rail. In the vicinity of the exit of the tenter 19, the fixing of the film 18 by the pins is released. Further, in the present embodiment, the pin type tenter having a pin as the fixing means is shown. However, the pin type tenter is not particularly limited. For example, a plurality of clips for gripping both side ends of the casting film 12 are provided as the fixing means. A clip type tenter may be used.

  The film 18 carried out from the tenter 19 is cut at both side ends by using an ear-cutting device 20. Thereby, the stab wound by the pin formed in the both ends of the film 18 is cut off. In addition, although the said cutting process can also be abbreviate | omitted, in order to obtain the film 18 with few defects, it is preferable to carry out in any one from the casting chamber 12 to the winding chamber 28. FIG.

  While the film 18 is sent to the drying chamber 22 and supported and conveyed by a number of rollers 58, the film surface temperature of the film 18 is substantially constant within a range of 60 to 145 ° C. using a temperature controller (not shown). Thus, the drying of the film 18 is promoted without being damaged by heat. The film surface temperature of the film 18 can be easily known by a thermometer (not shown) provided on the conveyance path of the film 18 and in the vicinity of the surface. In the drying chamber 22, the solvent gas volatilized from the film 18 is recovered by the adsorption recovery device 59, the solvent component is removed, and the drying chamber 22 is supplied again as drying air. Thereby, solvent gas does not adhere to the surface of the film 18, and reduction of energy cost can be aimed at.

  The film 18 is sent to the cooling chamber 23 and cooled until it reaches substantially room temperature. The cooling method is not particularly limited, and for example, a method of allowing the film 18 to stand in the cooling chamber 23 at approximately room temperature and naturally cooling it, or a method of attaching a blower to the cooling chamber 23 and supplying cold air may be used. . In addition, when a humidity control chamber (not shown) is provided between the drying chamber 22 and the cooling chamber 23 to cool the film 18 after the humidity is adjusted, the wrinkle is effective even when the surface of the film 18 has already wrinkled. Therefore, it is preferable because the effect of stretching can be obtained.

  The charged voltage of the film 18 brought to substantially room temperature is adjusted by the forced static elimination device 25. The charged voltage of the film 18 is not particularly limited, but is preferably substantially constant in the range of −3 kV to +3 kV. Thereafter, knurling is imparted to both end portions of the film 18 by the knurling roller 26. Finally, the film 18 is sent to the take-up chamber 28 and is taken up by the take-up roller 62 while applying pressure to the surface by the press roller 61 and adjusting the flatness. The tension at the time of winding the film 18 is preferably changed gradually from the start to the end of winding. Thereby, it becomes possible to wind up without generating a wrinkle and a twist.

  As described above, the film 18 having excellent flatness can be manufactured at high speed and stably. According to the present invention, it is possible to produce a film 18 that is at least 100 m in the transport direction and 1400 to 1800 mm in the width direction. However, the present invention is effective even when it is larger than 1800 mm. Although the film thickness of the completed film 18 is not specifically limited, It is preferable that it is 20-500 micrometers. More preferably, it is 30-300 micrometers, Most preferably, it is 35-200 micrometers, but the effect of this invention can be acquired even when the film thickness of the film 18 is as thin as 15-100 micrometers.

  In the above description, a mode in which a single-layer film is manufactured using one kind of dope has been shown, but the present invention is also effective when forming a cast film having a multilayer structure. The casting film having a multilayer structure may be any known method such as casting a desired number of dopes simultaneously or sequentially, and is not particularly limited. Also, from the structure of casting die, decompression chamber, support, etc., co-casting, peeling method, stretching, drying conditions of each process, handling method, curling, winding method after flatness correction, solvent recovery method, film The recovery method is described in detail in paragraphs [0617] to [0889] of JP-A-2005-104148, and these descriptions can also be applied to the present invention. 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. It can be applied to the invention.

  It is preferable to perform surface treatment on at least one surface of the completed film because the degree of adhesion with an optical member such as a polarizing plate can be increased. Examples of the surface treatment include vacuum glow discharge treatment, atmospheric pressure plasma discharge treatment, ultraviolet irradiation treatment, corona discharge treatment, flame treatment, acid treatment, alkali treatment, etc., and at least one of these treatments is performed. Is preferred.

  When the completed film is used as a base and a desired functional layer is provided on both sides or one side, 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 preventing light reflection and providing high image quality can be obtained. The functional layer and the forming method are described in detail in paragraphs [0890] to [1072] of JP-A-2005-104148, and these descriptions can also be applied to the present invention. it can. Regarding specific uses of the polymer film of the present invention, for example, TN type, STN type, VA type, OCB type described in paragraphs [1088] to [1265] of JP-A-2005-104148, Application to a liquid crystal display device such as a reflection type is exemplified.

  Next, various dope raw materials according to the present invention will be specifically described.

  It is preferable to use cellulose ester as a dope raw material 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 acetate butyrate. Especially, it is preferable to use a cellulose acetate from the height of transparency, and it is especially preferable to use a triacetyl cellulose (TAC). The dope used in the present embodiment includes triacetyl cellulose (TAC) as a polymer. Thus, when using TAC, it is preferable that 90 weight% or more of TAC is a particle | grain of 0.1-4 mm. In addition, the polymer component of dope is not limited to a cellulose ester, What is necessary is just a well-known thing which can be dissolved in a solvent and can make dope.

As said cellulose acylate, in order to obtain a film with higher transparency, it is preferable that the substitution degree of the acyl group to 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

  Glucose units having β-1,4 bonds constituting cellulose have free hydroxyl groups at the 2nd, 3rd and 6th positions. Cellulose acylate is a 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 at which the hydroxyl group of cellulose is esterified at 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. Further, the value of DS6 / (DS2 + DS3 + DS6) 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 the ratio in which the hydrogen of the 6-position hydroxyl group is replaced by an acyl group in the glucose unit.

  Only one kind of acyl group may be used for cellulose acylate, or two or more kinds 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 is DSA, and the sum of the degree of substitution of the hydroxyl groups at the 2nd, 3rd and 6th positions by acyl groups other than acetyl groups When 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 0.7 or more. Further, 20% or more of DSB is preferably a substituent at the 6-position hydroxyl group, more preferably 25% or more, further 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. In the case of using the cellulose acylate as described above, when a non-chlorinated solvent is used, a dope having very excellent solubility, low viscosity, and excellent filterability can be prepared. .

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

  The acyl group having 2 or more carbon atoms of 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. Further, 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, oleoyl 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 cellulose acylate that can be used in the present invention are described in paragraphs [0140] to [0195] of JP-A-2005-104148, and these descriptions also apply to the present invention. Can do.

  The solvent used as the dope material is preferably an organic compound that can dissolve the polymer used. However, in the present invention, the dope means a mixture obtained by dissolving or dispersing the polymer in a solvent, and therefore a solvent having low solubility with the polymer can also be used. Examples of the solvent that can be suitably used include aromatic hydrocarbons such as benzene and toluene, halogenated hydrocarbons such as dichloromethane, chloroform, and chlorobenzene, and 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, peelability which is an index of ease of peeling of the cast film peeled off from the support, mechanical strength of the film, optical properties, etc., dichloromethane has 1 to 5 carbon atoms. It is preferable to use one of these alcohols or a mixture of several alcohols. The content of alcohol is preferably 2 to 25% by weight, more preferably 5 to 20% by weight, based on the entire 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, any of -O-, -CO-, and -COO- are also used as a solvent. Can be used. 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, phosphoric ester plasticizers such as triphenyl phosphate and biphenyl diphenyl phosphate, phthalic ester 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 hydrophobic treatment such as an alkylation treatment have excellent dispersibility in a solvent, so that a dope can be prepared without agglomeration of the fine particles, and a film can be produced. It is possible to produce a film with few state defects and 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 fine particle content relative 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 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 of 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 30% by weight, and particularly preferably 17 to 25% by weight. Moreover, it is preferable that the ratio in which an additive (mainly a plasticizer) is contained shall be 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 these descriptions can also be applied to the present invention. Further, it is a method for producing a dope using TAC. For example, materials, raw materials, additive dissolution methods and addition methods, filtration methods, defoaming, and the like are also disclosed in JP-A-2005-104148 [0517]. It is described in detail from paragraph to [0616] paragraph, and these descriptions can also be applied to the present invention.

  Examples of the present invention and comparative examples will be shown below to specifically describe the present invention. However, the present invention is not limited to these examples and comparative examples.

  The film 18 was manufactured using the film manufacturing equipment 10 shown in FIG. After an appropriate amount of dope is sent from the dope production facility 30 to the casting die 33 through the feed block 31, the discharge of the casting die 33 is placed on the casting drum 34 continuously rotated as shown in FIG. The dope was discharged from the outlet. The discharge amount of the dope was adjusted so that the thickness of the dried film 18 was 80 μm. Further, the pressure in the decompression chamber 45 was set to 600 Pa, and the back of the bead was decompressed. Further, dichloromethane was cast on the casting band 34 as an intervening film forming liquid from the intervening film forming apparatus 71. The flow rate of the intervening film forming liquid was adjusted so that the thickness of the intervening film 72 was 3 μm.

  The casting drum 34 has a surface temperature of −10 ° C. by supplying a refrigerant from a heat transfer medium supply device (not shown) using a stainless steel drum whose rotational speed can be controlled by a drive device (not shown). It was. Before casting the dope, it was applied to the casting drum 34 by the voltage application device 36 so that the surface potential V was adjusted to 2 kV. Further, nitrogen gas was supplied to the casting chamber 14 to adjust the oxygen concentration to be always less than 10% by weight. Furthermore, the temperature inside the casting chamber 14 was always set to 35 ° C. using the temperature control device 43. Note that the casting die 33 has a discharge port formed by a slit having a width of 1.8 m and a jacket (not shown) for adjusting the internal temperature, and the temperature of the dope to be cast is 36 ° C. did. The feed block 31 and the pipes serving as the dope flow paths were all kept at 36 ° C. using a form having a temperature adjustment function.

  The casting film 12 that had been cooled and gelled until it had self-supporting property was peeled off from the casting drum 34 together with the intervening film 72 while being supported by the peeling roller 38. Next, while the casting film 12 was sent to the crossing part 16 and conveyed while being supported by a plurality of conveying rollers, the casting film 12 was dried by supplying drying air adjusted to 40 ° C. from the blower 54. Thereafter, the casting film 12 is sent to a pin-type tenter 19, a plurality of pins are pierced and fixed at both end portions, and then the casting film 12 is transported while being stretched in the width direction. No.) was supplied and dried to obtain a film 18.

The position of 50 mm was cut | disconnected inward from the both ends of the film 18 using the edge cutting device 20 provided with the NT type cutter distribute | arranged within 30 second from the exit of the tenter 19. FIG. Both end portions of the cut film 18 were sent to a crusher 56 by a cutter blower (not shown) and crushed into chips of about 80 mm ² on average.

  A preliminary drying chamber (not shown) was provided between the ear opener 20 and the drying chamber 22, and the film 18 was preheated by supplying drying air at 100 ° C. and then carried into the drying chamber 22. In the drying chamber 22, the film 18 is conveyed while being wound around a plurality of rollers 58 in the drying chamber 22 whose internal temperature is adjusted by a temperature adjusting device (not shown) so that the film surface temperature of the film 18 becomes 140 ° C. Dried in between. The drying time of the film 18 by the drying chamber 22 was 10 minutes. The film surface temperature of the film 18 was measured using a thermometer (not shown) provided immediately above the conveyance path of the film 18 and in the vicinity of the surface. In the drying chamber 22, after recovering the solvent gas volatilized from the film 18 using an adsorption recovery device 59 having an adsorbent composed of activated carbon and a desorbent composed of dry nitrogen, the water content is reduced to 0.3 wt% or less. The water in the solvent gas was removed until

  A humidity control chamber (not shown) is provided between the drying chamber 22 and the cooling chamber 23, and air having a temperature of 50 ° C. and a dew point of 20 ° C. is supplied to the film 18. % Air was blown to adjust the humidity, and the curl generated on the film 18 was corrected. Next, after sending the film 18 to the cooling chamber 23 and gradually cooling the film 18 to 30 ° C. or lower, the charged voltage of the film 18 was set to −3 kV or higher and +3 kV or lower using the forced static eliminator 25. Then, knurling was imparted to both end portions of the film 18 using the knurling imparting roller 26 to correct irregularities generated on the surface. The film 18 has a width for imparting knurling to 10 mm, and the pressing force by the knurling roller 26 is adjusted so that the height of the irregularities is 12 μm higher than the average thickness of the film 18. Processing was performed.

  The film 18 was sent to the take-up chamber 28 and taken up by a take-up roller 62 having a diameter of 169 mm while applying a pressing force of 50 N / m to the film 18 by the press roller 61. At the time of winding, the tension at the beginning of winding of the film 18 was 300 N / m, and the tension at the end of winding was 200 N / m. From the above, a roll-shaped film 18 was obtained. The completed film 18 had a film thickness of 80 μm. In addition, the average drying rate of the cast film 12 and the film 18 was set to 20% by weight / min throughout the film forming process.

The dope raw materials used in this example are shown below.
[Dope raw material]
Cellulose triacetate 100 parts by weight Dichloromethane 320 parts by weight Methanol 83 parts by weight 1-butanol 3 parts by weight Plasticizer A 7.6 parts by weight Plasticizer B 3.8 parts by weight UV agent a 0.7 part by weight UV agent b 0.3 part by weight Part citrate ester mixture 0.006 parts by weight fine particles 0.05 parts by weight

  The cellulose triacetate has a substitution degree of 2.84, a viscosity average polymerization degree of 306, a water content of 0.2% by weight, a viscosity of 6% by weight in a dichloromethane solution of 315 mPa · s, an average particle diameter of 1.5 mm, and a standard deviation of 0.8. 5 mm powder, plasticizer A is triphenyl phosphate, plasticizer B is diphenyl phosphate, and UV agent a is 2 (2′-hydroxy-3 ′, 5′-di- tert-butylphenyl) benzotriazole, UV agent b is 2 (2′-hydroxy-3 ′, 5′-di-tert-amylphenyl) -5-chlorobenzotriazole, and the citrate ester compound is It is a mixture of acid, monoethyl ester, diethyl ester and triethyl ester, and the fine particles have a mean particle size of 15 nm and a Mohs hardness of about 7 It is silicon. In addition, when the dope is prepared, a retardation control agent (NN-di-m-toluyl-Np-methoxyphenyl-1,3,5-triazine-2,4,6-triamine) is used as a film. It added so that it might become 4.0 weight% with respect to the total weight.

  In order to evaluate the effect of the present invention, the entrainment state of air generated in the bead was visually observed. As a result, in Example 1, the casting speed was 120 m / min. No air entrainment was observed until. In the following Examples and Comparative Examples, air entrainment was observed by this evaluation method.

  A film 18 was manufactured in the same manner as in Example 1 except that the surface potential of the casting drum 34 was changed to 0.7 kV. In Example 2, the dope casting speed was 110 m / min. For the first time, air entrainment was confirmed.

  Except that the surface potential of the casting drum 34 was set to 0.7 kV and the film was formed without forming the intervening film 72, the same procedure as in Example 1 was performed. Then, in Example 3, the dope casting speed was set to 100 m / min. Air entrainment was confirmed.

  The same procedure as in Example 1 was performed except that the film was formed without using the decompression chamber 45. Then, in Example 4, the dope casting speed was set to 100 m / min. Air entrainment was confirmed.

[Comparative Example 1]
Except that the film was formed without charging the surface of the casting drum 34, everything was the same as in Example 1. Then, in Comparative Example 1, the dope casting speed was 90 m / min. Nevertheless, air entrainment was confirmed.

[Comparative Example 2]
The same procedure as in Example 1 was performed except that the surface of the casting drum 34 was not charged and the film was formed without using the decompression chamber 45. Then, in Comparative Example 2, air entrainment was confirmed regardless of the dope casting speed of 80 m / min.

  From the results of Examples and Comparative Examples, the dope casting speed is conventionally 90 m / min. However, when the present invention was applied, the casting speed was 110 to 120 m / min. Without causing air entrainment. It was confirmed that it can be improved to a certain extent. Therefore, according to the present invention, it is possible to improve the film-forming speed while suppressing air entrainment, and to stably form a cast film having no voids and excellent flatness, so that there are few defects and flatness. It was confirmed that a film showing good quality such as excellent can be manufactured at high speed and stably.

It is the schematic of the film manufacturing equipment concerning this invention. It is the schematic of the casting part vicinity of the dope concerning this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Film manufacturing equipment 12 Casting film 34 Casting drum 36 Voltage application apparatus 45 Depressurization chamber 70 Electrical insulation film 71 Interposition film formation apparatus 72 Interposition film

Claims (9)

A dope containing a polymer, a solvent, and an additive is discharged from a casting die onto a continuously running support to form a bead between the casting die and the support, and the bead is Casting on a support to form a cast film;
A step of drying the cast film after peeling off from the support to form a film,
A method for producing a polymer film, wherein the casting is performed while applying a voltage to the support using a voltage application device connected to the support.   The method for producing a polymer film according to claim 1, wherein the support is electrically ungrounded, and an electric insulating film is provided on a surface of the support.   The method for producing a polymer film according to claim 1, wherein the surface potential V of the support is 0.1 kV <| V | <3 kV.   The method for producing a polymer film according to any one of claims 1 to 3, wherein the casting is performed in an environment having an oxygen concentration of less than 10% by weight.   The method for producing a polymer film according to any one of claims 1 to 4, wherein the bead is brought into close contact with the surface of the support using a contact device disposed near the surface of the support.   The method for producing a polymer film according to claim 5, wherein the contact device is a decompression chamber disposed in the vicinity of the discharge port in order to decompress the back of the bead.   The contact apparatus is configured to attach the bead on the support in order to supply a liquid containing at least one solvent contained in the dope between the support and the casting film to form an intervening film. 6. The method for producing a polymer film according to claim 5, wherein the intervening film forming apparatus is disposed upstream of the point.   The method for producing a polymer film according to claim 2, wherein the electrical insulating film has a multilayer structure. A dope containing a polymer, a solvent, and an additive is discharged from a casting die onto a continuously running support to form a bead between the casting die and the support, and the bead is A casting film forming apparatus for casting on a support to form a casting film;
A drying device that dries the cast film after peeling off from the support to form a film, and
A polymer film manufacturing facility, comprising: a voltage application device connected to the support and applying a voltage to the support during casting.

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