JP2009236419A - Dryer assembly and method for moist film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To remove deposits deposited in a sprocket cover interior by a simple configuration. <P>SOLUTION: One part of a sprocket 46 is covered by a sprocket cover 90. The sprocket cover 90 is composed of an upper cover 91, a lower cover 92, and a cradle 93. An outlet 93a discharging the deposits from a side of the sprocket 46 is formed in the cradle 93. Inclined planes 93b, 93c for guiding the deposits to the outlet 93a by gravity are formed in a bottom of the cradle 93. An excitation part 96 and a heating part 97 are connected to the cradle 93. The excitation part 96 applies vibration to the cradle 93 to facilitate slipping of the deposits. The heating part 97 heats the inclined planes 93b, 93c to facilitate slipping of the deposits. A suction tube 99 of an air cleaner 98 is connected to the outlet 93a, and the deposits are recovered by suction. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a wet film drying apparatus and method.

  Polymer films have excellent light transmittance and flexibility, and can be made light and thin, and thus are widely used as optical functional films. Among these, the cellulose ester film using cellulose acylate or the like has toughness and low birefringence in addition to the above-described properties. This cellulose ester film is used as a protective film and an optical compensation film for a polarizing plate, which is a constituent member of a liquid crystal display (LCD) whose market is expanding in recent years, including a photographic photosensitive film.

  One method for producing a polymer film is a solution casting method. According to this solution casting method, first, a dope containing a polymer and a solvent is cast from a casting die onto a support to form a casting film. Then, after the casting film has a self-supporting property, the casting film is peeled off from the support as a wet film. And the wet film is conveyed in the state which hold | maintained the both ends of the wet film with the tenter. In the tenter, the wet film being transported is dried. Thereby, a film is obtained.

Drying of the wet film in the tenter is performed by carrying both ends of the film by carrying means such as clips and pins, and blowing dry air on the running film. On the other hand, since the gripping means is fixed to an endless moving body such as a chain and circulates, if the film is held again by the gripping means exposed to high temperature dry air near the tenter outlet and heated to a high temperature, the solvent in the film will boil. May cause foaming, leading to film cutting. Moreover, in the solution casting method in which self-supporting property is imparted by cooling gelation, the film is supported by the pin plate. However, if the pin temperature is high, the resin that covers the tip of the pin when the pin enters the film is solidified. It peels off to form a cap-like powder, which causes foreign matter failure and scratches. In order to prevent this, the supporting means is cooled by passing through a cooling duct before supporting both side ends of the film (see, for example, Patent Document 1).
JP-A-9-85846

  However, the provision of cooling ducts creates new problems. In the tenter, the solvent gas volatilized from the wet film is filled, and a part of the solvent gas enters the cooling duct. The solvent gas that has entered the cooling duct is liquefied or solidified by cooling the cooling duct, and adheres to the pins and the pin plate as precipitates. This precipitate contains a large amount of additives such as plasticizers and UV agents added to the dope. When this deposit adheres to the pin plate or the endless moving part and the amount of deposition increases, a large burden is applied. In particular, when deposits are deposited on a conveying guide roller used for conveying a pin plate or a bearing used therefor, there is a possibility that the film cannot be conveyed stably. In addition, when the deposit attached to the endless moving part is peeled off in the drying chamber, the film may be scattered, and in this case, there is also a problem that a foreign matter failure is caused.

  For the above problems, measures such as the introduction of plasticizers and UV agents that are difficult to volatilize, lowering the drying temperature of the tenter, and longer drying time of the tenter can be considered. This is not preferable because there is a problem that the quality of the film is changed or the cost is excessive.

  In the tenter, the solvent is recovered from the solvent gas in the tenter by condensation recovery or adsorption recovery, and the gas from which the solvent has been removed is sent back into the tenter. UV agents are collected. However, even if this method is used, the amount of foreign matter adhering to the pin plate or the like cannot be completely eliminated.

  Although it is conceivable to clean the pin plate using a cleaning solvent, there is a problem that the cleaning effect is weak and the cleaning guide solvent and the oil component of the bearing are dissolved. . Furthermore, when the cleaning solvent volatilizes in the tenter, there is a problem that the cleaning solvent must be recovered. Therefore, it may be possible to blow dry ice or nitrogen gas. However, in the case of a chain bearing with a complicated structure, it is difficult to inject gas into the chain, so the film production line is periodically stopped. It is necessary to clean the pin plate etc. offline. For this reason, there existed a problem that an operation rate fell by washing | cleaning operation | work and the cost of the film became high.

  An object of the present invention is to provide a wet film drying apparatus and method capable of removing deposits deposited inside a sprocket cover with a simple configuration.

  The wet film drying apparatus of the present invention is a carrier that carries both edges of the wet film after casting a dope containing a polymer and a solvent onto an endless support to make it self-supporting, and then peeling it off as a wet film. Drying of a wet film in which a pair of endless moving parts to which a plurality of members are attached are moved by the rotation of a plurality of sprockets, and the wet film carried on the carrying member is sent to a drying chamber to dry the solvent in the wet film In the apparatus, a cooling duct that covers and cools the endless moving part that is looped around the last sprocket of the return path of the endless moving part that has left the drying chamber, a sprocket cover that covers the last sprocket, and the sprocket A cradle provided on the cover for receiving and depositing the precipitate solidified by cooling by the cooling duct, and the cradle Provided, a discharge port for discharging the deposited precipitate, is provided in the cradle, characterized in that it comprises an inclined surface that induced by its own weight the deposited precipitates the outlet

  Further, it is preferable that the inclined surface is formed to be inclined by 10 ° to 80 ° with respect to a horizontal plane, and the deposited precipitate is guided to the discharge port by this inclination.

  Furthermore, it is preferable to provide a heating part for heating the inclined surface to 45 ° C. or higher.

  In addition, a vibration portion that vibrates the inclined surface, the inclined surface is made of a material having a smaller surface frictional resistance than other portions, and the inclined surface is vibrated by the vibration portion, and is deposited. It is preferable to guide the precipitate to the outlet.

  Furthermore, it is preferable to provide an air cleaner that sucks and removes the precipitate induced in the discharge port.

  Furthermore, in the method for drying a wet film according to the present invention, a dope containing a polymer and a solvent is cast on an endless support to make it self-supporting, and then peeled off as a wet film to support both side edges of the wet film. A wet film that moves a pair of endless moving parts to which a plurality of support members to be mounted are attached by rotation of a plurality of sprockets, and sends the wet film supported by the support member to a drying chamber to dry the solvent in the wet film In the drying method, the endless moving part cooling step of covering and cooling the endless moving part wrapped around the last sprocket of the return path of the endless moving part leaving the drying chamber with a cooling duct, and the last sprocket Is covered with a sprocket cover, and the precipitate solidified by cooling by the cooling duct is received by the cradle of the sprocket cover. It is a product, wherein the precipitate obtained by this deposit has a deposit discharge step to discharge from the discharge port before reaching the moving path of the sprocket.

  According to the present invention, the deposit deposited inside the sprocket cover that covers the sprocket is guided by the inclined surface and discharged from the discharge port to the outside of the sprocket cover. Damage can be reliably prevented.

  Moreover, since the inclined surface is formed so as to be inclined by 10 ° to 80 ° with respect to the horizontal plane, the deposits accumulated inside the sprocket cover can be reliably guided to the discharge port.

  As shown in FIG. 1, the film manufacturing facility 10 includes a casting chamber 11, a crossing part 12, a pin tenter 13, a clip tenter 14, an ear clip device 15, a drying device 16, a cooling device 17, and a winding device 18. .

  In the casting chamber 11, a feed block 21 into which the dope from the dope production facility 20 is fed, a casting drum 22 as an endless support, a casting die 23 for casting the dope onto the casting drum 22, and a flow A stripping roller 26 for stripping the casting film 24 on the rolling drum 22 as a wet film 25, a condenser 27 (condenser) for condensing and liquefying solvent gas evaporated from the casting film 24 and the wet film 25, and a liquefied solvent And a recovery device 28 for recovering. Further, a heat transfer medium supply device (not shown) is connected to the casting drum 22, and the surface temperature of the casting drum 22 is set to a desired value by supplying the heat transfer medium into the heat transfer medium supply device. The temperature is adjusted. Further, a temperature adjusting device 30 for adjusting the internal temperature is attached to the casting chamber 11.

  A dope channel is formed inside the feed block 21. A decompression chamber 32 is attached to the casting die 23, and the decompression chamber 32 is used for a dope flow (hereinafter referred to as “bead”) from the discharge port of the casting die 23 to the casting drum 22. The back is decompressed to stabilize the bead contact with the casting drum 22. A jacket (not shown) is attached to the decompression chamber 32, and the decompression chamber 32 is adjusted to a desired temperature.

  The casting drum 22 is composed of a stainless steel drum capable of continuous rotation. The surface of the casting drum 22 is polished. As a result, a casting film 24 having excellent planarity is formed on the casting drum 22. A casting drum is used as the 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 shape, material, size and the like of the casting die 23 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 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 SUS316 in the forced corrosion test by 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.

A cured film is preferably formed at the tip of the discharge port of the casting die 23 for the purpose of improving wear resistance. 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, the cured film should be capable of grinding, have a high porosity, be superior in brittleness and corrosion resistance, and have a high degree of adhesion to the casting die. However, 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.

  A plurality of rollers 35 are installed in the crossover part 12. These rollers 35 convey the wet film 25 peeled off from the casting drum 22 to the pin tenter 13. Hereinafter, the conveyance direction of the wet film 25 is defined as the X direction. A blower 36 is provided above the conveyance path of the wet film 25, and the blower 36 blows dry air on the wet film 25 to promote drying of the wet film 25.

  As will be described in detail later, the pin tenter 13 inserts and holds pins on both side end portions (hereinafter referred to as “ear portions”) 25a of the wet film 25, and conveys the wet film 25 while holding the ear portions 25a. Drying air is sent from the drying ducts 52 and 53 (see FIG. 3) to the wet film 25 and heated to a desired temperature to promote drying. The drying air is sent to the drying air circulation device 60 (see FIG. 3) through an exhaust port 60a (see FIG. 3) provided in the drying chamber 62. The drying air circulation device 60 adsorbs and recovers the solvent and the plasticizer from the drying air and returns the drying air after the adsorption recovery to the drying ducts 52 and 53.

  The clip tenter 14 is provided downstream of the pin tenter 13, grips and conveys the ear portion 25 a of the wet film 25 coming out of the pin tenter 13 and performs drying. Also in the clip tenter 14, a plurality of drying ducts (not shown) are arranged vertically so as to sandwich the wet film 25, and the wet film 25 is dried by the drying duct (not shown). Thereby, the film 37 is obtained. Note that the clip tenter is provided as necessary and may be omitted. In this case, the film 37 exiting the pin tenter 13 is sent to the drying device 16.

  The ear clip device 15 cuts the ear portion of the film 37 that has come out of the clip tenter 14. Further, a crusher 66 is connected to the ear clip device 15, and the crusher 66 crushes the ear portion of the film 37 into chips. Then, the film 37 from which the ears have been cut is sent to the drying device 16. A large number of rollers 67 are provided inside the drying device 16, and the film 37 is dried while being conveyed by the rollers 67. The solvent gas generated from the film 37 in the drying device 16 is adsorbed and recovered by an adsorption recovery device 69 provided outside the drying device 16. The gas from which the solvent has been removed by the adsorption recovery is returned to the drying device 16 again. The film 37 exiting the drying device 16 is sent to the cooling device 17 where it is cooled to approximately room temperature. The ear clip device may also be provided at the outlet of the pin tenter 13 so that the ear portion is cut and then sent to the clip tenter.

  The winding device 18 includes a winding core 70, and the film 37 exiting the cooling device 17 is wound up in a roll shape by the winding core 70. The winding device 18 includes a press roller 71. The press roller 71 winds the film 37 while adjusting the winding pressure.

  As shown in FIGS. 2 and 3, the pin tenter 13 conveys the wet film 25 in the X direction while holding the ear portion 25 a of the wet film 25, and the width direction (hereinafter referred to as “Y direction”). ) At a predetermined stretching ratio.

  The pin tenter 13 includes a pin insertion brush roller 40, a dust removing device 42, a rail 44, sprockets 46 to 48, drying ducts 52 and 53, a rail cover 54, and a pin carrier (endless moving part) 58. Is provided.

  The brush roller 40 is provided on the inlet 13a side of the pin tenter 13, and the pin 72 (see FIG. 4) is inserted into the ear portion 25a of the wet film 25 that has entered the pin tenter 13 to its root portion. The dust removing device 42 is provided on the outlet 13b side of the pin tenter 13 and removes dust and the like on the ear portion 25a by suction.

  The rails 44 are installed on both sides of the transport path of the wet film 25. The rail 44 has its width and widening pattern determined in accordance with the stretch rate of the wet film 25, and the stretched state of the rail 44 is shown exaggerated. Moreover, the widening pattern is also an example, and various widening patterns may be employed in consideration of the optical characteristics of the film. The rail 44 is composed of two sets of rails 44a and 44b arranged in the vertical direction.

  The sprockets 46 and 47 are provided on the inlet 13 a side of the pin tenter 13, and the sprocket 48 is provided on the outlet 13 b side of the pin tenter 13. The teeth 59 (see FIG. 5) of the sprocket 46 mesh with the meshing grooves 74b (see FIG. 5) of the pin carrier 58. Similarly, the teeth (not shown) of the sprockets 47 and 48 are engaged with the engagement groove 74 b of the pin carrier 58. The pin carrier 58 is connected to each other on the rail 44, and the pin carrier 58 travels along the rail 44 when the sprocket 48 is rotated by a rotational drive of a motor or the like. As the pin carrier 58 travels, the sprockets 46 and 47 rotate.

  The dry duct 52 is installed above the transport path of the wet film 25, and the dry duct 53 is installed below the transport path of the wet film 25. The drying duct 52 blows dry air on the upper surface of the wet film 25. Further, the drying duct 53 blows dry air on the lower surface of the wet film 25. The temperature of the drying air in the drying ducts 52 and 53 is set to a predetermined temperature in the range of 40 ° C. or more and 200 ° C. or less. Thereby, drying of the wet film 25 is promoted, and the solvent gas is volatilized from the wet film 25.

  As shown in FIG. 4, the rail cover 54 covers a part of the rails 44 a and 44 b and the pin carrier 58. A rail 44a is attached to the upper surface inside the rail cover 54, and a rail 44b is attached to the lower surface thereof. The pin carrier 58 is disposed between the rail 44a and the rail 44b. In addition, a slit 54 a is formed in the rail cover 54 along the traveling direction of the pin carrier 58. Further, as shown in FIG. 5, the rail cover 54 in the vicinity of the installation position of the sprocket 46 is formed with a slit 54b for the sprocket 46 to enter. The same applies to the rail cover 54 in the vicinity of the position where the sprocket 47 is installed, and a description thereof will be omitted.

  As shown in FIG. 4, the pin carrier 58 includes a pin 72, a pin plate 73, a carrier body 74, and guide rollers 76 to 79.

  A large number of pins 72 are planted on the pin plate 73 at predetermined intervals. The pin plate 73 is fixed to the protrusion 74 a of the carrier body 74. A meshing groove 74 b that meshes with the teeth of the sprockets 46 to 48 is formed at the center of the lower surface of the carrier body 74. A pin cover 80 that covers the pins 72 and the pin plate 73 is attached to the rail cover 54.

  The guide roller 76 and the guide roller 77 are provided on the upper surface of the carrier body 74 so as to be separated from each other by the width of the rail 44a. Similarly, the guide roller 78 and the guide roller 79 are provided on the lower surface of the carrier body 74 so as to be separated by the width of the rail 44b. The guide rollers 76 to 79 sandwich the rails 44a and 44b, and guide the carrier body 74 when the carrier body 74 moves along the rails 44a and 44b.

  A connection bracket for connecting the carrier bodies 74 to each other is provided at the front end portion and the rear end portion in the traveling direction of each carrier body 74, and a connection pin is attached to the connection bracket in the horizontal direction. Therefore, since each carrier main body 74 is connected via the connecting pin, it can run and move in the vertical plane as shown in FIG. Instead of connecting the block-shaped carrier bodies to each other with connecting pins to form the pin carrier, the pin carrier may be formed using a chain.

  As shown in FIGS. 3 and 4, the pin tenter 13 is provided with a cooling area 81. An air supply nozzle 82 is attached to a rail cover (cooling duct) 54 located in the cooling area 81. The blowout hole of the nozzle 82 is directed to the inside of the rail cover 54. A cooling air supply unit 83 is installed in the cooling area 81.

  In the cooling area 81, cooling air is supplied from the cooling air supply unit 83 so that the temperature inside the rail cover 54 is substantially uniform. The temperature of the cooling air is set to, for example, −30 ° C. or higher and + 30 ° C. or lower.

  By cooling in the cooling area 81, the surface temperatures of the pins 72 and the pin plate 73 become 35 ° C. or more and 50 ° C. or less. By setting the temperature of the pin 72 within the above range, the pin 72 can easily pass through the ear portion 25a.

  Further, the cooling air from the cooling air supply unit 83 causes the temperature inside the rail cover 54 to be equal to or lower than the melting point of TPP, that is, 50 ° C. or lower. Therefore, components contained in the solvent gas volatilized from the wet film 25, in particular, plasticizers such as TPP (triphenyl phosphate), dope additives such as UV agents such as benzotriazole-based materials, When the pin plate 73 moves into the cooling area 81, the plasticizer and additive solidify (hereinafter, the solidified plasticizer and additive are referred to as precipitates). Then, the deposit adheres to the pin carrier 58, the pin 72, the pin plate 73, and the like.

  As shown in FIGS. 3 and 6, a part of the sprocket 46 as the last sprocket is covered with a sprocket cover 90. The sprocket cover 90 includes an upper cover 91, a lower cover 92, and a pedestal 93, and covers a portion where each tooth 59 of the sprocket 46 is exposed (a portion where the pin carrier 58 is not hung). It is configured.

  The upper cover 91 covers the upper half of the exposed portion of the teeth 59 of the sprocket 46, and the lower cover 92 covers the lower half. The lower cover 92 has a sufficient volume so that the deposits do not come into contact with the passage portions of the teeth 59 even if the deposits accumulate to some extent. The cradle 93 is disposed below the lower cover 92.

  The cradle 93 is formed with a discharge port 93 a for discharging precipitates from the side of the sprocket 46. In addition, inclined surfaces 93b and 93c are formed at the bottom of the cradle 93 for guiding precipitates by their own weight to the discharge port 93a. Precipitates are brought to the lower right of the lower cover 92 by the two inclined surfaces 93b and 93c.

  The surfaces of the inclined surfaces 93b and 93c are lined with Teflon (registered trademark) so that the precipitates slide smoothly. The angle θ of each of the inclined surfaces 93b and 93c with respect to the horizontal plane HF is appropriately selected in the range of 10 ° to 80 °, but an inclination angle of 25 ° to 50 ° is more preferable in consideration of the induction effect due to sliding and space efficiency. . The upper cover 91, the lower cover 92, and the cradle 93 are made of stainless steel.

  In order to surely guide the precipitate to the discharge port 93a, a vibration unit 96 and a heating unit 97 are connected to the cradle 93. The vibration unit 96 applies vibration to the cradle 93 to facilitate the sliding of the precipitate. The heating unit 97 heats the inclined surfaces 93b, 93c to, for example, a melting point of 50 ° C. or higher of TPP, which is a main component of the precipitate, and dissolves the inclined surface contact portion of the precipitate, thereby facilitating the sliding of the precipitate. To do.

  A suction tube 99 of an air cleaner 98 is connected to the discharge port 93a, and precipitates are collected by suction. These vibration, heating, and suction are performed constantly or intermittently. From the viewpoint of equipment efficiency, intermittent driving is preferable. In the case of intermittent driving, since both of the precipitates can be grasped according to the operating time of the film forming equipment, a certain amount is accumulated so that the precipitates do not come into contact with the teeth 59 of the sprocket 46. Forced discharge at the stage.

  In addition, you may change suitably the shape of the discharge port 93a and inclined surface 93b, 93c. Further, instead of the forced discharge by suction, the precipitate may be discharged by other forced discharge means such as scraping or extrusion.

  In the present embodiment, the wet film is transported without being inverted from the start of holding the ear of the wet film until it is released. However, the present invention is not limited to this, and the wet film is transported while being inverted several times. It is good also as a multistage conveyance system.

  In the present embodiment, the pin tenter of the present invention is implemented in a film manufacturing facility, but it is not necessary to be limited to this. For example, you may implement the pin tenter of this invention also in the web manufacturing equipment which manufactures webs other than a film. In the present embodiment, the present invention is applied to a pin tenter. However, the present invention is not limited to this, and the present invention can also be applied to a clip tenter. In this case, an endless moving part is comprised from the carrier main body which has a clip, for example.

  The width of the film 37 manufactured in the present embodiment is preferably 1400 mm or more and 2500 mm or less. In addition, even if it is a case where the width | variety of the film 37 exceeds 2500 mm, the effect of this invention can be acquired. In addition, the thickness of the film 37 manufactured in the above embodiment is preferably 20 μm or more and 100 μm or less, more preferably 20 μm or more and 80 μm or less, and most preferably 30 μm or more and 70 μm or less.

  In the above 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, 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 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. 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.

  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 the inventions related to these descriptions can also be applied to the present invention. it can. Regarding 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 For use in liquid crystal display devices.

  Next, the raw material of dope manufactured with the dope manufacturing equipment 20 is shown below.

  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 acylate butyrate. Especially, it is preferable to use a cellulose acylate from the height of transparency, and it is preferable to use a triacetyl cellulose (TAC). The dope used in the above embodiment includes triacetyl cellulose (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 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 (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. 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.

  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 raw 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 the 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, 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 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 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 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.

  The film 37 was manufactured in the film manufacturing facility 10 shown in FIG. An appropriate amount of the dope was sent from the dope production facility 20 to the casting die 23 via the feed block 21, and the dope was cast from the casting die 23 onto the continuously rotating drum 22 to form a casting film 24. . The discharge port of the casting die 23 was a slit having 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 21 was 36 ° C. The pressure behind the bead was reduced to 600 Pa and the pressure behind the bead was reduced.

  As the casting drum 22, a stainless steel drum capable of controlling the number of rotations 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 30.

  When the casting film 24 was cooled and gelled and became self-supporting, the casting film 24 was peeled off as a wet film 25 by the peeling roller 26. The wet film 25 thus peeled off was sent to the crossover part 12 and conveyed while being supported by a plurality of rollers 35 provided in the crossover part 12. During the conveyance, the drying air adjusted to 40 ° C. was supplied from the blower 36 to dry the film 37.

  As shown in FIG. 2, the pin 72 (refer FIG. 4) was inserted in the ear | edge part 25a of the wet film 25, and the ear | edge part 25a was hold | maintained. The wet film 25 was conveyed while holding the ear portion 25a. Further, as shown in FIG. 3, a drying duct 52 is provided above the conveyance path of the wet film 25, and a drying duct 53 is provided therebelow, and dry air is blown from the drying ducts 52 and 53 onto the wet film 25. In the cooling area 81, the pin carrier 58, the pin 72, and the pin plate 73 were cooled by cooling air.

As shown in FIG. 1, the wet film 25 that passed through the pin tenter 13 was sent to the clip tenter 14. In the clip tenter 14, the wet film 25 was transported while gripping the ears 25 a, and the wet film 25 was dried during the transport. Thereby, the film 37 was obtained. The position of 50 mm was cut | disconnected inward from the ear | edge part of the film 37 using the ear cutting device 15 provided with the NT type cutter distribute | arranged within 30 second from the exit of the clip tenter 14. The ears of the cut film 37 were sent to a crusher 66 through a cutter blower (not shown) and crushed into chips of about 80 mm ^{2 on} average.

  A pre-drying chamber (not shown) was provided between the ear opener 15 and the drying device 16, and the film 37 was preheated by supplying a drying air at 100 ° C. and then sent to the drying device 16. In the drying device 16, the film 37 was conveyed while being wound around a plurality of rollers 67, and drying was performed during the conveyance. The internal temperature of the drying device 16 was adjusted so that the film surface temperature of the film 37 was 140 ° C. The drying time of the film 37 in the drying device 16 was 10 minutes. The film surface temperature of the film 37 was measured using a thermometer (not shown) provided immediately above the conveyance path of the film 37 and in the vicinity of the surface. In the drying device 16, after recovering the solvent gas volatilized from the film 37 using an adsorption recovery device 69 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 device 16 and the cooling device 17, and air having a temperature of 50 ° C. and a dew point of 20 ° C. is supplied to the film 37. % Air was blown to adjust the humidity, and the curl generated on the film 37 was corrected. Next, the film 37 was sent to the cooling device 17, and the film 37 was gradually cooled until it became 30 degrees C or less.

  The film 37 was sent to the winding device 18, and was wound around the core Φ 169 mm while applying a pressing force of 50 N / m to the film 37 by the press roller 71. At the time of winding, the tension at the beginning of winding of the film 37 was 300 N / m, and the tension at the end of winding was 200 N / m. The roll-shaped film 37 was obtained by the above.

  The completed film 37 had a width of 1700 mm and a film thickness of 80 μm. In addition, the average drying rate of the cast film and the film was set to 20% by weight / min throughout the film forming process.

Four prescriptions of dope raw materials used in this example are shown below.
[Prescription 1]
Methylene chloride 83.5 parts by mass Methanol 16 parts by mass Butanol 0.5 parts by mass Water (outside split) 0.2-1.0 parts by mass [Prescription 2]
Methylene chloride 84.5 parts by mass Methanol 13.5 parts by mass Butanol 2 parts by mass Water (external split) 0.2-1.0 parts by mass [Prescription 3]
Methylene chloride 85 parts by weight Methanol 12 parts by weight Butanol 3 parts by weight Water (external split) 0.2-1.0 part by weight [Prescription 4]
Methylene chloride 92 parts by weight Methanol 8 parts by weight Butanol 0 parts by weight Water (outer split) 0.2-1.0 parts by weight In addition, in the above [Prescription 1] to [Prescription 4], in addition to the raw materials of each prescription, the following The ingredients were also prescribed.
TAC 100 parts by weight Plasticizer A 7.6 parts by weight Plasticizer B 3.8 parts by weight UV agent a 0.7 parts by weight UV agent b 0.3 parts by weight Citric acid ester mixture 0.006 parts by weight Fine particles 0.05 weights Part

  The TAC 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 0.5 mm. The plasticizer A is triphenyl phosphate, the plasticizer B is diphenyl phosphate, and the 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 compound is citric acid , Monoethyl ester, diethyl ester and triethyl ester, and the fine particles are silicon dioxide having an average particle diameter of 15 nm and a Mohs hardness of about 7. In addition, when the dope is prepared, a retardation control agent (N—N-di-m-toluyl-N—P-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.

  Next, in the pin tenter 13, the deposits accumulated inside the sprocket cover 90 were removed based on Examples 1 to 3 and Comparative Example 1.

  In Example 1, as shown in FIG. 6, the outlet 93a is formed in the cradle 93, the inclined surface 93b is inclined by 30 ° with respect to the horizontal surface HF, and the inclined surfaces 93b and 93c are 50 ° C. or higher ( For example, it was heated to 55 ° C. And the deposit induced | guided | derived to the discharge port 93a was attracted | sucked with the suction tube 99 of the air cleaner 98. FIG. Hereinafter, Examples 2 and 3 and Comparative Example 1 were obtained by changing the presence or absence of the discharge port 93a, the presence or absence of the inclined surface 93b, and the presence or absence of heating of the inclined surfaces 93b and 93c with respect to Example 1. Other conditions were the same as in Example 1. The results of this experiment are shown in Table 1.

  The “precipitate removal state” in Table 1 indicates how much the deposit deposited inside the sprocket cover 90 has been removed. Here, “◎” indicates that the precipitate has been completely removed, “○” indicates that the precipitate has been removed for maintenance-free for more than one year, and “×” indicates that maintenance within half a year is required. It is shown that the precipitate could be removed only to the extent of

  As a result of this experiment, in Example 1, the deposits inside the sprocket cover 90 were completely removed, and in Examples 2 and 3, the deposits were removed to a degree that is maintenance-free for one year or more. Thereby, in Examples 1-3, even if it operated the film manufacturing equipment 10 continuously for one year or more, for example, there was no damage of the pin carrier 58 resulting from adhesion of a deposit. Further, in Comparative Example 1, when the film manufacturing facility 10 was continuously operated for more than half a year, the pin carrier 58 was damaged due to adhesion of precipitates.

It is the schematic which shows a film manufacturing equipment. It is a top view which shows a pin tenter. It is a front view which shows a pin tenter. It is sectional drawing of a rail, a rail cover, and a pin carrier. It is sectional drawing of a rail, a rail cover, and a pin carrier which shows the state which the tooth | gear of the sprocket and the biting groove | channel of the pin carrier meshed | engaged. (A) is a front view showing a sprocket and a sprocket cover, (B) is a side view, and (C) is an exploded perspective view.

Explanation of symbols

10 Film production equipment 13 Pin tenter 25 Wet film 46 Sprocket 54 Rail cover (cooling duct)
58 pin carrier (endless moving part)
72 pin 73 pin plate 81 cooling area 90 sprocket cover 91 upper cover 92 lower cover 93 cradle 93a discharge port 93b, 93c inclined surface 96 excitation unit 97 heating unit 98 air cleaner

Claims (6)

A dope containing a polymer and a solvent is cast on an endless support to make it self-supporting, then peeled off as a wet film, and a pair of support members attached to both edges of the wet film are attached. In the wet film drying apparatus for moving the endless moving part by rotation of a plurality of sprockets, sending the wet film supported by the support member to the drying chamber and drying the solvent in the wet film,
A cooling duct that covers and cools the endless moving part that is wound around the last sprocket of the return path of the endless moving part that has left the drying chamber;
A sprocket cover covering the last sprocket;
A cradle that is provided on the sprocket cover and receives and deposits the precipitate solidified by cooling by the cooling duct;
An outlet provided in the cradle for discharging the deposited deposit;
An apparatus for drying a wet film, comprising: an inclined surface provided on the pedestal for guiding the deposited deposit to the discharge port by its own weight.   2. The wet film drying according to claim 1, wherein the inclined surface is formed at an angle of 10 ° to 80 ° with respect to a horizontal plane, and the deposited precipitate is guided to the discharge port by the inclination. apparatus.   The wet film drying apparatus according to claim 1, further comprising a heating unit configured to heat the inclined surface to 45 ° C. or more. Comprising a vibrating part for vibrating the inclined surface;
The inclined surface is made of a material having a smaller surface frictional resistance than other parts,
4. The wet film drying apparatus according to claim 1, wherein the inclined surface is vibrated by the vibration unit to guide the deposited precipitate to the discharge port. 5.   The apparatus for drying a wet film according to any one of claims 1 to 4, further comprising an air cleaner that sucks and removes the precipitate guided to the discharge port. A dope containing a polymer and a solvent is cast on an endless support to make it self-supporting, then peeled off as a wet film, and a pair of support members attached to both edges of the wet film are attached. In the method for drying a wet film, the endless moving part is moved by rotation of a plurality of sprockets, the wet film supported on the support member is sent to a drying chamber, and the solvent in the wet film is dried.
An endless moving part cooling step of covering and cooling the endless moving part wound around the last sprocket of the return path of the endless moving part leaving the drying chamber;
The last sprocket is covered with a sprocket cover, and the precipitate solidified by cooling by the cooling duct is received by the cradle of the sprocket cover and deposited, and the deposited precipitate is discharged before reaching the movement path of the sprocket. A method of drying a wet film, comprising: a precipitate discharging step of discharging from an outlet.

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