JP2009083881A - Solution storage/transfer tank and film manufacture line - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To transfer dope from a dope preparation facility to a solution film forming facility using a transfer tank. <P>SOLUTION: This transfer tank 12a comprises a tank main body 41, a saturation solvent gas generator part 42, a temperature controller part 43, a solution transferring pipe 44, a solution receiving pipe 45 and a transfer carriage 46. Dope 40 is received in the main body 41 from a dope preparation facility 11 by the pipe 45 of the tank 12a set at a solution receiving position P1. Saturation solvent gas is sent to the main body 41 from the generator part 42 for inhibiting a skin layer from being formed due to drying of the dope in the main body 41. The controller part 43 controls the temperature of the gaseous part above the solution level and the solution part below the level separately according to the level of the dope 40 in the main body 41 for controlling the generation of the barricade on the level. The tank 12a is set at a solution transfer position P2 for transferring the dope 40 to a solution film forming facility 13 through the pipe 44. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a mobile tank for storing a polymer solution and a film production line using the solution storage / transfer tank.

  A cellulose triacetate film produced by a solution film-forming method using a polymer such as cellulose triacetate as a raw material is a protective film or 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. Used for. These optical use films differ in required optical properties depending on the liquid crystal system and the manufacturer's specifications. Therefore, it is necessary to produce a wide variety of optical films according to various required performances.

  Changing the type of optical film involves changing polymer materials, additives, and solvents. On the other hand, in the solution casting method, preparation of polymer raw materials, filtration, storage, and liquid feeding facilities are large-scale. In addition, when changing the polymer solution that is the raw material of the film for the purpose of producing a wide variety of optical films, it is necessary to replace the old and new solutions in these film manufacturing facilities. When replacing the solution, the old polymer solution is washed and then the new polymer solution is sent. However, since the polymer solution in the solution casting apparatus has a high viscosity and tends to adhere and remain on the wall surface of the apparatus, it is difficult to wash the old polymer solution for each facility.

  Therefore, replacement of the old and new solutions is performed by extrusion replacement in which the old polymer solution is extruded with a new polymer solution. Moreover, in order to reliably perform this extrusion replacement, a liquid amount 3 to 5 times the amount of solution retained in the equipment is required due to complete mixing in the tank and laminar flow in the piping. These extrusion-substituted parts are in a state where old and new polymer solutions are mixed, and the resulting film cannot be shipped as a product, and the amount of its components is not known accurately, so it was made into chips. It is also difficult to reuse later. For this reason, a non-reusable film is generated, resulting in a cost problem.

On the other hand, it is possible to install a storage tank and a liquid supply piping system for each product type, but there is a problem in that the equipment cost becomes large. Moreover, when making small changes in the physical properties of the polymer, the type and amount of additives, the solvent composition, etc., the polymer solution must be extruded and replaced. Therefore, there is no big merit. In order to solve these problems, there is also a method of changing old and new polymer solutions using a movable solution storage and transfer tank (see Patent Document 1).
Japanese Patent Laid-Open No. 62-144745

  However, the polymer solution (dope) in the solution casting apparatus has a high viscosity, and the dope is easily dried. For this reason, even if a general mobile production container technique as described in Patent Document 1 is simply applied, there is a problem that a burrs are generated on the liquid surface and a foreign matter failure occurs.

  The present invention has been made to solve the above-described problems, and provides a solution storage and transfer tank that prevents the occurrence of burrs on the liquid surface of a polymer solution and a solution casting apparatus using the same. For the purpose.

  The solution storage and transfer tank of the present invention generates a saturated solvent gas containing the solvent main component of a tank body, and a solution containing a polymer and a solvent stored in the tank body, and the saturated solvent gas is supplied to the tank body. A saturated solvent gas generation section to be supplied to the gas phase section, and a gas phase section above the liquid level and a liquid phase below the liquid level in accordance with the liquid level of the solution stored in the tank body A temperature control unit that individually controls the temperature of the unit, a first connection unit and a first valve that are connected to the solution delivery destination, and that sends the solution in the tank body to the solution delivery destination. A liquid pipe and a movable carriage on which the tank body is mounted are provided.

  In addition, the present invention is characterized by having a cleaning nozzle that sprays and cleans the cleaning liquid toward the inner surface of the tank body. Furthermore, an inert gas inlet for sending an inert gas into the tank body is provided.

  Further, the present invention provides a film production line having a solution preparation facility for preparing a solution and a solution casting facility for forming a film using the solution, and storing the solution storage and transfer tank described above and the solution storage and transfer tank. A second connection part provided in the solution casting apparatus for receiving the solution, and a third connection part provided in the solution preparation equipment for sending the solution to the solution storage and transfer tank; The solution storage and transfer tank between the solution receiving position where the first connecting portion is connected to the third connecting portion and the solution feeding position where the first connecting portion is connected to the second connecting portion. And the solution storage and transfer tank is in the solution receiving position, and the first connection portion is connected to the third connection portion, and the solution is removed from the solution preparation facility. In storage transfer tank The solution storage and transfer tank is in the solution delivery position, and the solution is transferred from the solution storage and transfer tank to the solution casting equipment in a state where the first connection portion is connected to the second connection portion. And a control unit.

  ADVANTAGE OF THE INVENTION According to this invention, it can prevent that foreign materials, such as a river burr, generate | occur | produce on the wall surface in a solution storage movement tank, or the liquid level of a solution.

  FIG. 1 is a schematic view of a film production line for carrying out the present invention. The film production line 10 includes a dope preparation facility 11, a plurality of mobile storage tanks (hereinafter simply referred to as mobile tanks) 12a, 12b, 12c to 12e, and a solution film-forming facility 13.

  The dope preparation equipment 11 includes a hopper 20, a solvent tank 21, an additive tank 22, a dissolution tank 23, a pump 24, a heater 25, a temperature controller 26, and a filter 27. The dissolution tank 23 includes a jacket 23a and a stirrer 23b. The dissolution tank 23 is supplied with the polymer 31 from the hopper 20 via the meter 20a, the solvent 32 from the solvent tank 21 via the valve 21a, and the additive 33 from the additive tank 22 via the valve 22a. These are mixed and stirred by a stirrer. Thereby, the swelling liquid 35 in which the polymer 31 is swollen in the solvent 32 is obtained.

  The swelling liquid 35 is sequentially sent to the heater 25, the temperature controller 26, and the filter 27 by the pump 24, and then sent to the moving tank 12a via the valve 36 and the flange 37 to be stored. The heater 25 dissolves the solid content in the swelling liquid 35 under heating conditions or pressure heating conditions to obtain the dope 40. In this case, the temperature of the swelling liquid 35 is preferably 0 ° C. to 120 ° C., for example. In addition, you may perform the cooling dissolution method which cools the swelling liquid 35 to the temperature of -100 degreeC--10 degreeC. The polymer 31 can be sufficiently dissolved in the solvent 32 by appropriately selecting the heating dissolution method and the cooling dissolution method. The temperature controller 26 sets the dope 40 to approximately room temperature. Thereafter, impurities contained in the dope 40 are removed by the filter 27.

  The first moving tank 12 a includes a tank body 41, a saturated solvent gas generation unit 42, a temperature control unit 43, a liquid feeding pipe 44, a liquid receiving pipe 45, and a moving carriage 46. The movable carriage 46 includes wheels 46a guided by rails (not shown) and a drive unit 46b. The other moving tanks 12b to 12e are configured similarly to the first moving tank 12a. Further, a moving method using radio waves without using rails may be used.

  The movable carriage 46 is comprehensively controlled by a system controller (not shown) and travels between the liquid receiving position P1, the liquid feeding position P2, and the stock yard 48. At the liquid receiving position P <b> 1, the liquid receiving pipe 45 of the moving tank 12 a is connected to the dope preparation equipment 11 to receive the dope 40 and store the dope 40 in the tank body 41. At the liquid feeding position P <b> 2, the liquid feeding pipe 44 of the moving tank 12 b is connected to the solution casting equipment 13 and supplies the dope 40 to the solution casting equipment 13. The stock yard 48 is provided in a carriage moving path 49 between the liquid receiving position P1 and the liquid feeding position P2, and when the moving tanks 12a and 12b are connected to the liquid receiving position P1 and the liquid feeding position P2, respectively. In addition, the remaining moving tanks 12c to 12e are temporarily stored.

  The dope 40 is stored in the tank body 41. The dope 40 is sent from the dope preparation facility 3 through the liquid receiving pipe 45. The liquid receiving pipe 45 includes a flange 45 a and a valve 45 b, and the flange 45 a is connected to the flange 37 of the dope preparation facility 11. Similarly, a liquid supply pipe 44 is connected to the bottom of the tank body 41. The liquid feeding pipe 44 also includes a flange 44 a and a valve 44 b, and the flange 44 a is connected to the flange 47 of the solution casting equipment 13. The liquid receiving pipe 45 may be omitted, and the liquid receiving pipe 44 may be used for liquid reception. Each flange is preferably one that automatically attaches and detaches, but may be a manual one-touch system or other coupling system.

  As shown in FIG. 2, the saturated solvent gas generating unit 42 generates a saturated solvent gas containing the solvent main component of the dope 40 stored in the tank main body 41, and this saturated solvent gas is generated in the gas phase in the tank main body 41. Supply to the department. For this reason, the saturated solvent gas generator 42 has a gas cylinder 54 attached to the container 51 via a pipe 52 and a valve 53. In the container 51, a solvent 55 (including a mixed solvent) having the same composition ratio as the solvent 32 constituting the dope 40 is stored in advance. One end of the pipe 52 is disposed in the solvent 55. By opening and closing the valve 53, the gas 54 a in the gas cylinder 54 is bubbled in the solvent 55 from the pipe 52. A part of the solvent 55 is volatilized by bubbling to become a gas (volatile gas) 55a, which is replaced with a part of the atmosphere in the space 51a of the container 51. By continuing the bubbling, most of the atmosphere in the space 51a is replaced with the volatile gas 55a. The replacement rate is most preferably 100%, but there is no practical problem if the atmosphere in the range of 50% to 100% is replaced by a volume ratio from the viewpoint of costs such as replacement time. This substituted gas is sent as a saturated solvent gas 55b to the gas phase section in the tank body 41 via a pipe 57 having a pump 57a and a valve 57b. The gas 54a is not particularly limited, but nitrogen gas, helium gas, or the like is preferably used, and nitrogen gas is particularly preferably used from the viewpoint of cost. Note that the saturated solvent gas generation unit 42 is not limited to the above-described method, and may be any as long as it can generate a saturated solvent gas.

  The saturated solvent gas 55b in the tank main body 41 may be discharged out of the tank main body 41 through a vent pipe 56 having a valve 56a. In this case, it is preferable to provide a solvent recovery device in the building of the film production line 10 to recover and recycle the released solvent. Thus, since the saturated solvent gas 55b is filled in the gas phase portion in the tank main body 41, the vapor-liquid equilibrium with the solvent of the dope 40 is maintained, and the occurrence of burrs on the gas-liquid surface is eliminated. Further, although the saturated solvent gas generation unit 42 is provided outside the tank main body 41, it may be incorporated in the gas phase part of the tank main body 41.

  The temperature control unit 43 includes a liquid level sensor 60, a plurality of horizontal jackets 61a to 61g, a heat transfer medium supply unit 63, a pump 64, and a temperature sensor (not shown) provided for each of the horizontal jackets 61a to 61g. In addition, by changing the temperature or flow rate of the heat transfer medium 65 supplied to the horizontal jackets 61a to 61g with the liquid surface position in the tank body 41 as a boundary, drying of the dope adhering to the wall surface of the tank body 41 is suppressed, Reduce the generation of foreign matter. In the present embodiment, seven horizontal jackets 61a to 61g are provided, but the number of horizontal jackets 61a to 61g attached is not limited to this, and may be increased or decreased as appropriate. By increasing the number of attachments, it is possible to accurately follow the liquid level displacement in the vertical direction and accurately control the temperature according to the liquid level.

  The temperature control in the tank body 41 is such that T1> T2, T2 <T3, and T1 ≦ T3, where T1 is the liquid phase temperature, T2 is the liquid surface temperature, and T3 is the gas phase temperature. By setting the liquid surface part temperature T2 lower than the liquid phase part temperature T1, the solvent volatilization from the liquid surface is suppressed and the occurrence of burrs is eliminated. At the same time, the saturated solvent gas in the gas phase near the liquid level is liquefied on the inner surface of the tank and flows down the inner surface, so that even if a small amount of burrs are generated on the liquid level by the flowing-down solvent, it is dissolved. be able to. In addition, when the gas phase temperature T3 is lower than the liquid surface temperature T1, the amount of saturated solvent gas in the gas phase that liquefies on the inner surface of the tank increases, and the polymer concentration in the dope is uneven when it flows down to the liquid phase. This causes quality defects such as uneven film thickness. Accordingly, the gas phase temperature T3 is set higher than the liquid surface temperature T2 and not lower than the liquid phase temperature T1.

  The temperature distribution in the vertical direction according to the liquid level in the tank body 41 is detected by detecting the current liquid level position by the liquid level sensor 60, and using the horizontal jackets 61a to 61g where the liquid level is located as a reference. Based on the output of the temperature sensor, the temperature or circulation amount of the heat transfer medium to be circulated to each horizontal jacket 61a to 61g is controlled so that the upper and lower horizontal jackets 61a to 61g satisfy the above temperature condition.

  In addition, the tank main body 41 is provided with a cleaning nozzle 66 for cleaning the tank main body 41 and an inert gas introduction pipe 67 having a valve 67a when the specifications of the dope 40 are changed. The cleaning nozzle 66 and the inert gas introduction pipe 67 are provided with a cleaning liquid supply pipe or an inert gas supply pipe (not shown) when any of the moving tanks 12a to 12e is set at the cleaning position set in the stockyard. Connected to. Then, the remaining dope 40 is discharged from the liquid feeding pipe 44 by introducing the inert gas into the tank body 41.

  Next, after the cleaning liquid 68 is sent to the tank body 41 by the cleaning nozzle 66 to clean the inside, the inert gas 69 is similarly sent to discharge the cleaning liquid 68. The cleaning nozzle 66 is configured such that the cleaning liquid 68 is sprayed on the entire inner peripheral surface of the tank body 41.

  After the cleaning, the valve 67a is opened, and the inert gas 69 is filled into the tank body 41 through the inert gas introduction pipe 67. The filling of the inert gas 69 makes it possible to receive a new dope.

  As shown in FIG. 1, the solution casting apparatus 13 includes a casting chamber 70, a crossover 71, a tenter 72, a drying chamber 73, and a winder 74, and uses the dope 40 from the moving tank 12b. Thus, a film 75 is made. In the casting chamber 70, a casting die 77 in which a discharge port for the dope 40 is formed, a casting drum 78 acting as a support, and a peeling roller 79 are arranged.

  The dope 40 is cast on a casting drum 78 rotating endlessly by a casting die 77 to form a casting film 81. The surface temperature of the casting drum 78 is substantially constant within a range of −10 ° C. to 10 ° C. By casting the dope 40 onto the casting drum 78 thus cooled, the dope 40 is quickly cooled, and a gel-like casting film 81 is formed within a short time. As the casting drum 78 is rotated, the casting film 81 is gelled, and the casting film 81 having self-supporting properties is peeled off as a wet film 85 from the casting drum 78 while being supported by the peeling roller 79. Taken.

  In the crossover portion 71, the wet film 85 is supported by a large number of rollers, and drying proceeds while being conveyed. In the tenter 72, both end portions of the wet film 85 are held by holding means such as pins, and then dried while being transported to form a film 75. Thereafter, the film 75 is wound up in a roll shape by the winding shaft 86.

  Next, the operation of this embodiment will be described. The dope 40 prepared by the dope preparation equipment 11 is sent to the moving tank 12a set at the liquid receiving position P1. At this time, the valves 36 and 45b are opened after the flanges 37 and 45a are joined to each other. When a certain amount of the dope 40 is fed, the flanges 37 and 45a are separated after the valves 36 and 45b are closed. Thereafter, the dope 40 adhering to the flanges 37 and 45a and the pipe 45 is cleaned with a cleaning liquid. In addition to performing the cleaning manually, a cleaning unit may be provided in the dope preparation facility, and after sending the dope, the cleaning liquid may be flowed to automatically clean the inside of the pipes up to the valves 36 and 45b.

  The moving tank 12 a in which the dope 40 is put is self-propelled to the liquid feeding position P <b> 2 and is joined to the flange 47 of the solution casting apparatus 13. Thereafter, after the valves 44 b and 47 a are opened, the dope 40 in the tank main body 41 is sent to the solution casting apparatus 13. In the solution casting apparatus 13, the film 75 is manufactured using the dope 40 in the tank body 41. When the dope 40 in the tank body 41 becomes empty, it is sequentially replaced with new transfer tanks 12c to 12e, and continuous casting is performed in the solution casting equipment.

  When the dope 40 is switched to a new specification, the moving tank is cleaned at the cleaning position of the stock yard 48. Then, the washed transfer tank is set at the liquid receiving position P1, and a dope with a new specification (new dope) is stored in the transfer tank 12a. When a certain amount of dope 40 is stored in the moving tank, the moving carriage 46 is self-propelled from the liquid receiving position P1 to the liquid feeding position P2, and the flange 44a of the moving tank is connected to the flange 47 of the solution casting equipment 13. . Thereafter, the new dope 40 is sent to the solution casting apparatus 13, and solution casting with the new dope 40 is performed.

  In the solution casting apparatus 13, casting is performed while extruding and replacing the old dope in the casting die 77 from the flange 47 with the new dope, and the film 75 manufactured from the dope by this extrusion substitution is mixed with the old and new dopes. Therefore, it is not a product film and is discarded. However, since the new dope is sent by the moving tank system, the total amount of extrusion substitution is reduced as compared with the conventional dope preparation equipment 11 and solution casting equipment 13 being continuous. Accordingly, since the amount of new and old dopes is reduced, doping loss is reduced and efficient film formation becomes possible.

  In the present embodiment, the self-propelled movable carriage 46 is used, but this may be movement by another traction device or the like, or movement by an operator's operation.

  The polymer 31 according to the present invention is not particularly limited as long as it can be applied to the solution casting method. Among these, if cellulose acylate is used, a film having high transparency and excellent optical properties can be obtained, and therefore, it is suitable for optical applications such as a protective film for polarizing plates and an optical compensation film. Among them, when cellulose acetate is used, and particularly cellulose triacetate having an average degree of acetylation of 57.5% to 62.5% is used, a film having excellent optical properties can be obtained.

  The above-mentioned degree of acetylation means the amount of bound acetic acid per unit weight of cellulose, and can be determined according to the measurement and calculation of the degree of acetylation in ASTM: D-817-91 (test method for cellulose acetate and the like). In this embodiment, granular cellulose triacetate is used. In addition, when using a granular polymer, it is preferable that 90 weight% or more is a particle size of 0.1-4 mm from a compatible viewpoint with a solvent, More preferably, a particle size is 1-4 mm. It is.

  The solvent 32 is preferably a halogenated hydrocarbon, an ester, a ketone, an ether, an alcohol, or the like, but is not particularly limited, and may be appropriately selected in consideration of solubility with a polymer to be used. The solvent 32 may be one type of compound or a mixed solvent obtained by mixing a plurality of compounds. Specifically, halogenated hydrocarbons (eg, dichloromethane, etc.), esters (eg, methyl acetate, methyl formate, ethyl acetate, amyl acetate, butyl acetate, etc.), ketones (eg, acetone, methyl ethyl ketone, cyclohexanone, etc.) ), Ethers (eg, dioxane, dioxolane, tetrahydrofuran, diethyl ether, methyl-t-butyl ether, etc.), alcohols (eg, methanol, ethanol, etc.) and the like.

  The additive 33 may be appropriately selected according to the desired characteristics of the film 75. For example, a plasticizer, an ultraviolet absorber, a peeling accelerator, a fluorine surfactant, and the like can be given. Among these, as the plasticizer, phosphate ester type (for example, triphenyl phosphate (hereinafter referred to as TPP), tricresyl phosphate, cresyl diphenyl phosphate, octyl diphenyl phosphate, diphenyl biphenyl phosphate (hereinafter referred to as BDP). ), Trioctyl phosphate, tributyl phosphate, etc.), phthalate esters (eg, diethyl phthalate, dimethoxyethyl phthalate, dimethyl phthalate, dioctyl phthalate, etc.), glycolate esters (eg, triacetin, tributyrin, butyl phthalyl butyl glycolate) Ethyl phthalyl ethyl glycolate, methyl phthalyl ethyl glycolate, butyl phthalyl butyl glycolate, etc.). Among these, TPP is particularly preferable for making cellulose acylate into a film. In addition, a well-known thing can be used for a plasticizer besides the above, and it does not specifically limit. Further, as the ultraviolet absorber, for example, oxybenzophenone compounds, benzotriazole compounds, salicylic acid ester compounds, benzophenone compounds, cyanoacrylate compounds, nickel complex compounds are preferable, and among them, benzotriazole compounds and benzophenone compounds are preferable. Compounds are particularly preferred.

  In addition, from the structure of casting die, decompression chamber, support, etc., co-casting, peeling method, stretching, drying conditions of each step, 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 film obtained by the present invention has high transparency and retardation value and low humidity dependency. Therefore, although it can use suitably as a retardation film of a polarizing plate especially, it can utilize also as a protective film for protecting the surface of a polarizing plate. Regarding specific uses of the cellulose ester film of the present invention, in Japanese Patent Application Laid-Open No. 2005-104148, for example, from [1088] paragraph to [1265] paragraph, as a liquid crystal display device, TN type, STN type, VA type, The OCB type, the reflection type, and other examples are described in detail, and this description can also be applied to the present invention.

It is the schematic which shows a film manufacturing equipment. It is general | schematic sectional drawing which shows a movement tank.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Film production line 11 Dope preparation equipment 12a-12e Moving tank 13 Solution film-forming equipment 40 Dope 41 Tank main body 42 Saturated solvent gas generation part 43 Temperature control part 44 Liquid supply piping 45 Receiving piping 46 Moving cart 48 Stock yard 61a-61g Horizontal jacket 63 Heat transfer medium supply section 66 Cleaning nozzle 67 Inert gas introduction piping

Claims (4)

The tank body,
A saturated solvent gas generation unit that generates a saturated solvent gas containing the solvent main component of a solution containing a polymer and a solvent stored in the tank body, and supplies the saturated solvent gas to a gas phase part in the tank body When,
In accordance with the liquid level of the solution stored in the tank body, a temperature control unit that individually controls the temperature of the gas phase part above the liquid level and the liquid phase part below the liquid level;
A first connection portion and a first valve that are connected to a solution delivery destination of the solution; and a liquid delivery pipe that sends the solution in the tank body to the solution delivery destination;
A solution storage and transfer tank comprising a moving carriage on which the tank body is mounted.   The solution storage / transfer tank according to claim 1, further comprising a cleaning nozzle that injects a cleaning liquid toward the inner surface of the tank body.   3. The solution storage and transfer tank according to claim 1, further comprising an inert gas inlet for sending an inert gas into the tank body. In a film production line having a solution preparation facility for preparing a solution and a solution casting facility for forming a film using the solution,
The solution storage and transfer tank according to any one of claims 1 to 3,
A second connection provided in the solution casting facility to receive the solution stored in the solution storage and transfer tank;
A third connection provided in the solution preparation facility for sending the solution to the solution storage and transfer tank;
Between the solution receiving position where the first connecting portion is connected to the third connecting portion and the solution feeding position where the first connecting portion is connected to the second connecting portion, A tank moving device to move,
With the solution storage and transfer tank in the solution receiving position and the first connection portion connected to the third connection portion, the solution is sent from the solution preparation equipment to the solution storage and transfer tank, and the solution A control unit for sending the solution from the solution storage and transfer tank to the solution casting apparatus in a state where the storage and transfer tank is at the solution delivery position and the first connection is connected to the second connection; A film production line characterized by comprising.

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