JP3957530B2 - Solution casting method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a solution casting method, and more particularly to a solution casting method including a solvent recovery line.
[0002]
[Prior art]
A film formed from cellulose acylate, particularly cellulose triacetate having an average degree of acetylation of 57.5 to 62.5% (hereinafter referred to as TAC film) is characterized by its toughness and flame retardancy. It is used as a support. In addition, since the TAC film is excellent in optical isotropy, the TAC film is suitable for use as a protective film for a polarizing plate of a liquid crystal display device and a color filter whose market is expanding in recent years.
[0003]
The TAC film is generally produced by a solution casting method. The solution casting method can produce a film having excellent optical properties and physical properties as compared with other production methods such as a melt casting method. In the solution casting method, a polymer is dissolved in a solvent (mainly an organic solvent) to prepare a dope, and then the dope is cast on a support such as a band or a drum to form a dope. When the film is formed, a solvent gas volatilized from the dope is generated. This solvent gas is sucked out from the film drying chamber by the solvent recovery line, and the discharged solvent gas is It was liquefied, collected and reused from the viewpoint of environmental protection or economy. Further, the gas from which volatile components such as a solvent have been removed is returned to the film drying chamber and used as drying air.
[0004]
[Problems to be solved by the invention]
However, the solvent gas generated in the film drying chamber may leak outside before being discharged outside in the solvent recovery line, leading to deterioration of the working environment. In addition, the solvent recovery line is equipped with an adsorption facility and an absorption facility having a large number of adsorption layers, and by these, volatilized solvents and additives contained in the solvent gas are adsorbed. These adsorption facilities and the like switch the gas flow path with a switching device, and adsorb additives on the one hand, and desorb the additives adsorbed on the other, thereby enabling continuous operation. The gas air volume fluctuates when switching the gas flow paths of these adsorption facilities and the like. For this reason, an open chamber for absorbing the fluctuation has been installed. However, simply providing an open chamber may cause pressure fluctuations in the solvent recovery line to reach the film drying chamber. In some cases, the film drying chamber becomes pressurized, and a gas containing an organic solvent leaks, In addition, the organic solvent gas may leak from the open chamber.
[0005]
An object of the present invention is to prevent fluctuations in the amount of gas air generated when the gas flow path of an adsorption facility or the like is switched so that a gas containing an organic solvent does not leak from the drying chamber and the open chamber of the film production line. And providing a solution casting method.
[0006]
Another object of the present invention is to provide a solution casting method capable of efficiently recovering and reusing a gas containing an organic solvent generated from a film drying chamber of a film casting line.
[0007]
[Means for Solving the Problems]
The solution casting method of the present invention is a solution casting in which a dope in which a polymer and an additive are dissolved in a solvent is cast on a support, and then peeled off and dried in a film drying chamber to form a film. In the method, a solvent recovery line is connected to the film drying chamber, gas in the film drying chamber is circulated between the film drying chamber and the solvent recovery line, and at least a plurality of adsorbing portions provided in the solvent recovery line are circulated. By switching to use one, at least one of the solvent and the additive contained in the gas is adsorbed and recovered, and a first open chamber is provided upstream of the adsorption unit, and the adsorption unit A second open chamber is provided on the downstream side, and the negative pressure in each open chamber is maintained. The plurality of adsorbing portions are preferable because at least one of them can be adsorbed continuously by desorbing the solvent or the additive and sequentially performing the desorption.
[0008]
It is preferable to maintain the negative pressure in the first open chamber in the range of 0 to 1500 Pa. Moreover, it is preferable to maintain the negative pressure in the second open chamber in a range of 0 to 1500 Pa. Furthermore, it is preferable to maintain a negative pressure in the film drying chamber. In this case, the negative pressure in the film drying chamber is more preferably maintained in the range of 0 to 10 Pa. In the present invention, a pressure lower than the atmospheric pressure is defined as “negative pressure” without considering the effective digit of the measured value. In addition, any known method can be used as a method for measuring the pressure.
[0009]
The solution casting method of the present invention is a solution casting in which a dope in which a polymer and an additive are dissolved in a solvent is cast on a support, and then peeled off and dried in a film drying chamber to form a film. In the method, a solvent recovery line is connected to the film drying chamber, gas in the film drying chamber is circulated between the film drying chamber and the solvent recovery line, and at least a plurality of adsorbing portions provided in the solvent recovery line are circulated. By switching to use one, at least one of the solvent and the additive contained in the gas is adsorbed and recovered, and the film drying chamber is maintained at a negative pressure. Even in this case, it is more preferable to maintain the negative pressure of the film drying chamber in the range of 0 to 10 Pa. The negative pressure in the film drying chamber is preferably maintained in the solvent recovery line by reducing the amount of gas air sent to the film drying chamber from the amount of gas air sucked from the film drying chamber.
[0010]
It is preferable that a part of the gas adsorbed by the adsorption unit is discharged out of the solvent recovery line. Further, it is preferable that a part of the gas adsorbed by the adsorbing unit is further sent to the upstream side of the adsorbing unit and again adsorbed.
[0011]
An additional collection line is provided for sucking and collecting at least one of the solvent and the additive in the gas by sucking the gas in the building including the film drying chamber, and adding the building and the additional It is preferable to provide a third open chamber between the adsorbing part and maintain the negative pressure in the third open chamber. In this case, it is more preferable to maintain the negative pressure of the third open chamber in the range of 0 to 1500 Pa. In this case, one of the plurality of adsorption units may be selected and used as the additional adsorption unit. Further, the atmosphere is sucked by the second open chamber, the gas in the second open chamber is sucked by the first open chamber, and the gas in the first open chamber is sucked by the third open chamber. More preferably, the pressure in the open chamber is maintained at a negative pressure.
[0012]
The polymer is preferably cellulose acylate, more preferably cellulose triacetate.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
[polymer]
The polymer used in the present invention is not particularly limited. However, it is preferable to use cellulose acylate, and it is particularly preferable to use cellulose acetate. Further, among the cellulose acetates, it is most preferable to use cellulose triacetate having an average degree of acetylation of 57.5 to 62.5%. The degree of acetylation means the amount of bound acetic acid per unit weight of cellulose. The degree of acetylation follows the measurement and calculation of the degree of acetylation in ASTM: D-817-91 (test method for cellulose acetate and the like). In the present invention, cellulose acylate particles are used, and 90% by weight or more of the particles used have a particle diameter of 0.1 to 4 mm, preferably 1 to 4 mm. Also, preferably 95% by weight or more, more preferably 97% by weight or more, further preferably 98% by weight or more, and most preferably 99% by weight or more of particles have a particle size of 0.1 to 4 mm. Furthermore, it is preferable that 50% by weight or more of the particles used have a particle diameter of 2 to 3 mm. More preferably 70% by weight or more, still more preferably 80% by weight or more, and most preferably 90% by weight or more of the particles have a particle size of 2 to 3 mm. Moreover, it is preferable that the particle shape of cellulose acylate is as close to a sphere as possible.
[0014]
[solvent]
Examples of the solvent used in the present invention include halogenated hydrocarbons, esters, ketones, ethers and alcohols, but are not particularly limited. The solvent is not particularly limited as long as it is commercially available. The solvent may be used alone (100% by weight) or a mixture of halogenated hydrocarbons having 1 to 6 carbon atoms, esters, ketones, ethers, and alcohols. Examples of solvents that can be used include halogenated hydrocarbons (eg, methylene chloride), esters (eg, methyl acetate, methyl formate, ethyl acetate, amyl acetate, butyl acetate), ketones (eg, acetone). , Methyl ethyl ketone, cyclohexanone, etc.), ethers (eg, dioxane, dioxolane, tetrahydrofuran, diethyl ether, methyl-t-butyl ether), alcohols (eg, methanol, ethanol, etc.), and the like.
[0015]
[Additive]
Examples of the additive used in the present invention include a plasticizer and an ultraviolet absorber. Examples of the plasticizer include phosphate esters (for example, triphenyl phosphate, tricresyl phosphate, cresyl diphenyl phosphate, octyl diphenyl phosphate, diphenyl biphenyl phosphate, trioctyl phosphate, tributyl phosphate, etc.), phthalate esters (for example, Diethyl phthalate, dimethoxyethyl phthalate, dimethyl phthalate, dioctyl phthalate, etc.), glycolic acid esters (eg, triacetin, tributyrin, butyl phthalyl butyl glycolate, ethyl phthalyl ethyl glycolate, methyl phthalyl ethyl glycolate, butyl phthalyl) Butyl glycolate) and any other known plasticizer can be used.
[0016]
Examples of usable UV absorbers include oxybenzophenone compounds, benzotriazole compounds, salicylic acid ester compounds, benzophenone compounds, cyanoacrylate compounds, nickel complex compounds, and any other known UV absorbers. be able to. Particularly preferred ultraviolet absorbers are benzotriazole compounds and benzophenone compounds. Furthermore, various additives such as a mold release agent, a release accelerator, and a fluorosurfactant can be used as necessary.
[0017]
[Preparation of dope]
After the polymer and additive are charged into the solvent, the dope is prepared by dissolving the polymer and additives by any known dissolution method. This dope generally removes foreign matters by filtration. Various known filter media such as filter paper, filter cloth, non-woven fabric, metal mesh, sintered metal, and perforated plate can be used for filtration. By filtering, foreign substances and undissolved substances in the dope can be removed, and defects due to foreign substances in the film formed can be reduced.
[0018]
In addition, the dope once dissolved can be heated to further improve the solubility. For heating, there are a method of heating while stirring in a stationary tank, a method of heating while transferring the dope using various heat exchangers such as a multi-tube type, a jacket pipe with a static mixer, and the like. Moreover, it is also possible to heat to the temperature more than the boiling point of dope by providing a cooling process after a heating process, and pressurizing the inside of an apparatus. By performing these heat treatments, the fine undissolved material can be completely dissolved, the dope filtration load can be reduced, and foreign matters in the formed film can be reduced.
[0019]
[Solution casting method]
Although the solution casting method will be described with reference to an example in which TAC is used as a polymer, the polymer used in the solution casting method according to the present invention is not limited to TAC. FIG. 1 shows a film deposition line 10 used in the solution casting method according to the present invention. The film deposition line 10 is installed in the building 9. The film production line 10 is divided into a preparation zone 11, a band zone 12 and a drying zone 13. The preparation zone 11 includes a preparation tank 14, a pump 15, and a filter 16. Further, the dope 18 is uniformly prepared in the charging tank 14 by the stirring blade 17. The prepared dope 18 is sent to the casting die 20 in the band zone 12 through the pump 15 and the filter 16. The dope 13 is preferably manufactured by the above-described dope preparation method. For example, TAC particles and a solvent are mixed, and after the TAC particles are swollen with the solvent, additives such as a plasticizer and an ultraviolet absorber are mixed to prepare a dope. In the present invention, as a solvent for preparing a dope, a solvent recovered from the film production line 10 can be mixed with a commercially available solvent and used. The recovery of the solvent will be described later.
[0020]
The band zone 12 is provided with a casting band 23 stretched around the rollers 21 and 22, and the casting band 23 is rotated by a driving device (not shown). A casting die 20 is provided on the casting band 23. The dope 18 is sent from the preparation tank 14 by the pump 15, and after impurities are removed by the filter 16, the dope 18 is sent to the casting die 20. The dope 18 is cast on the casting band 23 from the casting die 20. The dope 18 is self-supporting by being gradually dried while being conveyed by the casting band 23, and is peeled off from the casting band 23 by the peeling roller 24 to form a film 25. Further, the film 25 is stretched to a predetermined width by the tenter 26 and dried while being conveyed.
[0021]
In the band zone 12, the solvent in the dope 18 volatilizes and becomes a solvent gas and is sent to the heat exchanger 40. In the band zone 12, since a large amount of solvent volatilizes because it is in the initial stage of drying, the generated solvent gas contains a large amount of volatilized organic solvent. The solvent gas is condensed and liquefied by the condenser 41, and the liquid is condensed and recovered as a recovery solvent 42. Further, the gas that has not been liquefied is sent to the heat exchanger 40 by the blower 43, heated by the heater 44, sent to the band zone 12 again, and reused as dry air. As is well known, the inside of the band zone 12 is divided into a plurality of chambers by partition walls as required, and the gas is discharged and the drying gas is sent to these chambers.
[0022]
The film 25 sent from the tenter 26 to the drying zone 13 is dried while being wound around a plurality of rollers 27 and conveyed in the drying zone 13. The dried film 25 is taken up by a winder 28. The temperature in the drying zone 13 is preferably controlled in the range of 50 to 150 ° C. for uniform drying of the film 25. A solvent recovery line 30, which will be described later, is attached to the drying zone 13, and the solvent gas containing the volatilized solvent and additive generated from the drying zone 13 is sucked. After removing the solvent and additives from the solvent gas, the gas is recycled to the drying zone 13 as dry air and reused. The recovered solvent is reused as a solvent for preparing the dope. The solvent recovery line 30 will be described later in detail.
[0023]
The film 25 can be used as an optical film such as a polarizing plate protective film. A polarizing plate can be formed by pasting this polarizing plate protective film on both surfaces of a polarizing film made of polyvinyl alcohol or the like. Furthermore, it can also be used as an optical functional film such as an optical compensation film having an optical compensation sheet affixed on the film or an antireflection film having an antiglare layer formed on the film. From these products, a liquid crystal display plate which is a part of the liquid crystal display device can be constituted.
[0024]
Although FIG. 1 shows a form in which one kind of dope is cast in a single layer, the solution casting method of the present invention is not limited to the form shown in the figure. For example, it is possible to apply a co-casting method in which a feed block is attached upstream of the casting die, a large number of dopes are fed into the feed block, and the dopes are joined together in the feed block. is there. In FIG. 1, a casting belt is used as a casting support. However, the present invention is not limited to the illustrated embodiment, and the present invention is also applicable to, for example, a solution casting method in which a dope is cast on a rotating drum. It is possible.
[0025]
[Solvent recovery process]
A method for recovering the solvent gas by the solvent recovery line 30 will be described in detail with reference to FIG. The solvent gas containing the solvent volatilized in the drying zone 13 is sent to the heat exchanger 50 and then blown to the open chamber (hereinafter also referred to as the first open chamber) 52 by the blower 51. As shown in FIG. 2, the open chamber 52 is provided with an opening 52a for sucking the air 53, and the air 53 can always be sucked from the opening 52a. In addition, the opening 52 a is provided with a filter 54 to prevent the dust contained in the air 53 from being sucked into the open chamber 52. Further, a baffle plate 52b is provided in the open chamber 52, and the amount of the air 53 sucked by the baffle plate 52b is adjusted. The open chamber is the same in an open chamber (hereinafter referred to as a second open chamber) 70 and an open chamber (hereinafter referred to as a third open chamber) which will be described later. And the air | atmosphere 53 and the solvent gas 56 are attracted | sucked from the 1st open chamber 52 with the air blower 55 (refer FIG. 1), and the inside of the 1st open chamber 52 is made into a pressure (negative pressure) lower than atmospheric pressure. In addition, it is preferable to make this negative pressure into the range of 0-1500Pa. When the negative pressure is smaller than 0 Pa, that is, when the pressure is increased, the solvent gas 56 is discharged outside the system. In addition, if the negative pressure is higher than 1500 Pa, the amount of processing air necessary for the solvent recovery facility increases, and the size of the facility increases accordingly, resulting in an increase in cost. Further, the form of the open chamber used in the present invention is not limited to the illustrated one, and any known open chamber can be used.
[0026]
In order to make the inside of the first open chamber 52 have a negative pressure, it is necessary to select the upstream blower 51 and the downstream blower 55 that have different blowing capabilities. That is, it is necessary that the blower capacity of the downstream blower 55 that sucks the solvent gas 56 and the air 53 is larger than the blower 51 that blows the solvent gas 56 to the first open chamber 52. The gas discharge air volume of the blower 55 attached on the downstream side is 100 to 200 Nm. ^Three / Min (“N” means normal state of gas, 0 ° C., 1 atm), when the gas discharge air volume of the blower 51 attached on the upstream side is 80˜ 170 Nm ^Three / Min is preferably used. However, in the present invention, the blowing capacity of the blowers is not limited to the above-described range as long as the blowing ability of the downstream blower is larger than the blowing ability of the upstream blower.
[0027]
Thus, by always maintaining the inside of the first open chamber 52 at a negative pressure, leakage of the solvent gas 56 from the first open chamber 52 can be prevented. Further, between the first open chamber 52 and the blower 55, a cooler 57 for cooling the solvent gas 56, a pretreated activated carbon 58 for the gas drying process, and a dehumidifier 59 are attached. These may be omitted as appropriate.
[0028]
Further, the solvent gas 56 is selectively sent by the switching device 63 to any of the adsorbers 60, 61, 62 by the blower 55, and the volatilized solvent and additive contained in the solvent gas 56 are absorbed by the adsorber 60. Adsorbed by ~ 62. Further, the gas after the adsorption treatment is sent to the open chamber 70. A part of the gas after the adsorption treatment is discharged from the air opening 64 provided on the downstream side of the adsorbers 60 to 62. However, returning this gas to the upstream side of the switching device 63 of the solvent recovery line 30 and performing the adsorption treatment again by the adsorbers 60 to 62 makes it possible to suppress the release of gas to the outside of the system. preferable. The second open chamber 70 is configured similarly to the first open chamber 52 shown in FIG. The second open chamber 70 sucks the gas (hereinafter referred to as treated gas) discharged from the adsorber by the blower 71 and the atmosphere 72. It is possible to prevent fluctuations in the air volume of the gas that occurs when the adsorbers 60 to 62 used for the adsorption process are selected by the switch 63. This is because fluctuations in the total gas air volume including the atmosphere are eliminated by increasing / decreasing the air flow rates in the first open chamber 52 and the second open chamber 70 which are maintained at a negative pressure as the gas air volume changes. It is. As a result, the environment in the drying zone 13 can be maintained without transmitting the gas flow rate fluctuation in the solvent recovery line 30 to the drying zone 13. Further, by making the inside of the second open chamber 70 have a negative pressure by the blower 71, it is possible to prevent gas leakage from the second open chamber 70. The inside of the second open chamber 70 is preferably set to a negative pressure of 0 to 1500 Pa, but is not limited to this range.
[0029]
The treated gas sucked by the blower 71 is adjusted to a predetermined temperature by the temperature controller 73 and then sent to the heat exchanger 50 by the blower 74. Then, after heat exchange is performed with the solvent gas described above, the heater 75 is further heated to a predetermined temperature by the heater 75, sent again into the drying zone 13, and reused as drying air.
[0030]
The volatile solvent component adsorbed by the adsorbers 60 to 62 is selectively sent by the desorption gas 80 by the switch 81, desorbed by the desorption gas 80, and sent to the condenser 82. The desorption gas 80 is condensed and liquefied by the condenser 82, and the liquid is sent to the solvent processing device 84 as a recovery solvent 83. Moreover, the gas component which is not liquefied is sent out again to the blower 55, sent into the adsorbers 60 to 62, and is collected by adsorption. In the present embodiment, the three adsorbers 60 to 62 are used to perform adsorption treatment with two of these, and perform desorption treatment with the remaining one. Hereinafter, when the desorption process of the adsorbate is completed, the adsorbent is made to function as an adsorber, and the adsorber whose adsorbability is lowered is then desorbed. By repeating this operation, the adsorbate can be continuously adsorbed and desorbed. However, the form of the adsorption and desorption processing is not limited to the above-described method, and the adsorbers 60 to 62 selected by the switchers 63 and 81 may be appropriately changed.
[0031]
The recovered solvent 83 is separated into a purified solvent 85 and a waste liquid 86 by the solvent processing device 84. The purified solvent 85 is fed into the preparation device 87 together with the recovery solvent 42 described above. In the preparation device 87, the components of the recovered solvent 42 and the purification solvent 85 are adjusted and sent to the preparation tank 14 as the dope preparation solvent described above. The waste liquid 86 is discarded.
[0032]
In the embodiment, the first open chamber 52 and the second open chamber 70 are attached to the solvent recovery line 30 to make the inside of the drying zone 13 have a negative pressure. However, the present invention is not limited to the embodiment. For example, by reducing the amount of gas air sent to the drying zone 13 with respect to the amount of gas air sucked from the drying zone 13 by the solvent recovery line 30, the inside of the drying zone 13 is always maintained in a negative pressure state, and the leakage of solvent gas Can be prevented. In addition, it is preferable that the negative pressure of the drying zone 13 at this time is the range of 0-10 Pa. If the negative pressure is higher than 10 Pa, the gas flow from the outside of the building 9 becomes too large, and it is easy to bring impurities such as dust outside the system into the drying zone 13 and may cause failure due to dust or the like. Because there is. An example of such a solvent recovery line is an apparatus that utilizes changes in gas pressure due to heating and cooling of solvent gas, but is not limited to this apparatus.
[0033]
In the solvent recovery line 30 of FIG. 1, a part of the processed gas was discharged from the atmosphere opening port 64. Furthermore, the method for returning the gas to the solvent recovery line 30 and performing the recovery process has also been described. However, in the present invention, the processing method of the processed gas is not limited to the form shown in FIG. FIG. 3 is a schematic diagram illustrating a solvent recovery line according to another embodiment.
[0034]
As shown in FIG. 3, in addition to the solvent recovery line 30 attached to the drying zone 13, the atmosphere containing the component in which the organic solvent in the building 9 is volatilized (hereinafter referred to as “volatile component gas”) is treated. A solvent recovery line 90 is attached. The solvent recovery line 90 includes a blower 91, a third open chamber 92, a cooler 93, a blower 94, an adsorber 95, and the like. Note that the numerical values in the squares in FIG. 3 will be described later.
[0035]
A part of the treated gas is branched downstream of the adsorber (the adsorber 62 is shown in FIG. 3 but may be other adsorbers 60 and 61) 62 in the solvent recovery line 30. Since the inside of the third open chamber 92 is maintained at a negative pressure while sucking the air 96, the treated gas in the solvent recovery line 30 can be easily sucked, and the treated gas is discharged out of the system. It is prevented from being discharged. The negative pressure in the third open chamber 90 is preferably in the range of 0 to 1500 Pa, but is not limited to this range. Then, the branched treated gas and the volatile component gas in the building 9 are combined and sent to the adsorber 95 for adsorption treatment. Thus, by attaching a solvent recovery line 90 different from the solvent recovery line 30 in the drying zone 13, it is possible to further prevent environmental fluctuations in the drying zone 13. Furthermore, since the volatile component gas inside the building 9 can also be adsorbed, the environment in the film production line 10 can be improved. Note that the adsorber 95 in FIG. 3 may use one of the three adsorbers 60 to 62 shown in FIG.
[0036]
Next, numerical values in the squares in FIG. 3 will be described. The numerical value in the square means the gas flow rate through each flow path, and its unit is Nm. ^Three / Min. In the following description, the amount of gas per minute (unit: Nm ^Three ). These numerical values are for explaining the embodiment of the present invention, and are not limited to those numerical values. That is, these values are only one mode for explaining the amount of gas sucked and discharged by the open chamber in the solvent recovery line, and the amount of suction of the atmosphere, and are not limited to the relationship between these values.
[0037]
First, the gas delivery and suction amount in the drying zone 13 will be described. As described above, in the drying zone 13, the solvent contained in the film 27 was gradually evaporated to form a solvent gas. Therefore, if the operation of the film forming line 10 is continued in this state, the inside of the drying zone 13 is in a pressurized state. Therefore, using the solvent recovery line 30, the drying zone 13 to 101 Nm ^Three Of solvent gas, 100Nm ^Three Aspirate the treated gas. Therefore, the environment is kept good and always 1Nm ^Three Since this gas is discharged to the solvent recovery line 30, it is possible to maintain a negative pressure in the drying zone 13 even if a solvent gas is generated. In addition, it is preferable that the negative pressure in the drying zone 13 is maintained in the range of 0-10 Pa.
[0038]
101 Nm discharged from the drying zone 13 ^Three The solvent gas is 9Nm ^Three After being sucked into the first open chamber 52 together with the atmospheric air 53 (total 110 Nm ^Three ) Is adsorbed by the adsorber 62. Part of treated gas (19Nm ^Three ) Is sucked into the third open chamber 92 of the solvent recovery line 90. The remaining 91 Nm ^Three Of the treated gas is 9 Nm in the second open chamber 70. ^Three A total of 100 Nm ^Three To the drying zone 13 as a gas.
[0039]
In addition, building 9 has 101 Nm ^Three 101 Nm of exhausted gas ^Three By sucking the gas, the pressure in the building 9 is made to be almost atmospheric pressure. 101 Nm discharged from building 9 ^Three Volatile component gas of 9Nm ^Three Of the treated gas in the atmosphere 96 and the solvent recovery line 30 described above (19 Nm ^Three ) In the third open chamber 92 (total 129 Nm) ^Three ) After that, the adsorption process is performed by the adsorber 95. In addition, a part of the treated gas (101 Nm ^Three ) Is preferably sent into the building 9 because the environment in the building 9 can be maintained well.
[0040]
In the present invention, the form of the solvent recovery line attached to the building 9 is not limited to that shown in FIG. FIG. 4 shows a schematic view in which the solvent recovery line 100 having the functions of the solvent recovery line 30 and the solvent recovery line 90 shown in FIG. 3 is attached to the building 9 and the drying zone 13. An open chamber 101 having the functions of the three first open chambers 52, the second open chamber 70, and the third open chamber 92 shown in FIG. 3 is attached to the solvent recovery line 100. The open chamber 101 includes three sections, a first section 101a, a second section 101b, and a third section 101c. The first open chamber 52, the second open chamber 70, and the third open chamber 92 (see FIG. 3). Each has a function corresponding to each. By this open chamber 101, the inside of the drying zone 13 is kept at a negative pressure, and the environment in the building 9 can be made in a good state. Furthermore, the inside of the open chamber 101 can be maintained at a negative pressure (0 to 1500 Pa). Since the gas treatment is performed in the same manner as in FIG. 3, the description thereof is omitted.
[0041]
An advantage of the open chamber 101 shown in FIG. 4 is that the amount of gas processed can be reduced. This point will be described in detail. In addition, the numerical value in the square in a figure is the gas | air volume (a unit is Nm) like FIG. ^Three / Min) but the amount of gas per minute (Nm ^Three ) Is the same as the description of FIG. Each of these numerical values is an aspect for explanation, and is not limited to those numerical values, as in the embodiment of FIG.
[0042]
101 Nm from drying zone 13 ^Three Of solvent gas is exhausted and 100 Nm ^Three The treated gas is kept at a negative pressure (preferably in the range of 0 to 10 Pa). 101Nm discharged ^Three The solvent gas is sucked into the first section 101a. The first section 101a is 19 Nm from the second section 101b. ^Three Gas is also sucked (total 120Nm ^Three ). Part of this gas (10Nm ^Three ) Is sucked into the third section 101c. 110Nm remaining ^Three Is sent to an adsorber (in the figure, the adsorber 62 is shown, but any of the adsorbers 60 to 62 shown in FIG. 1 may be used) 62 and subjected to an adsorption process. 110 Nm ^Three Processed gas of 9 Nm in the second compartment 101b ^Three (At a total of 119 Nm) ^Three ). Part of the gas (19 Nm ^Three ) Is sucked into the first section 101a as described above, and the remaining 100 Nm ^Three The treated gas is sent to the drying zone 13 as described above.
[0043]
The building 9 is 101 Nm as in FIG. ^Three Volatile component gas was discharged, 101 Nm ^Three Gas is fed in and maintained at approximately atmospheric pressure. 101Nm discharged ^Three The volatile component gas is sucked into the third section 101c. Further, as described above, the third section 101c has 10 Nm from the first section 101a. ^Three Gas is also sucked (total 111 Nm ^Three ). These gases are combined and sent to the adsorber 103 for adsorption treatment. And a part of the treated gas (101 Nm ^Three ) In the building 9 is preferable because the environment is kept good. The adsorber 103 in FIG. 4 may use one of the three adsorbers 60 to 62 shown in FIG. In FIG. 4, the atmosphere 102 is sucked from the second section 101b. However, in the present invention, an open chamber (not shown) for sucking the atmosphere from the first section 101a can be used.
[0044]
As described above, by using the open chamber 101 having the functions of the first to third open chambers 52, 70, 92, the gas of the adsorber provided in the solvent recovery line attached to the building 9 can be obtained. The amount of processing can be reduced. As shown, the adsorber 95 (see FIG. 3) is 129 Nm per minute. ^Three However, the adsorber 103 (see FIG. 4) had 111 Nm. ^Three It was possible to reduce about 15%. Further, in the embodiment of FIG. 3, it is necessary to provide three air intake ports, but in the embodiment of FIG. 4, only one location is possible, and the fluctuation of the gas flow rate in the solvent recovery line is further suppressed. It becomes possible to do. In addition, since the number of open chambers to be used is reduced from three to one, the negative pressure can be easily managed and the open chamber can be easily maintained.
[0045]
【The invention's effect】
According to the solution casting method of the present invention, after casting a dope in which a polymer and an additive are dissolved in a solvent, the solution is peeled off and dried in a film drying chamber to form a film. In the film forming method, a solvent recovery line is connected to the film drying chamber, and a gas in the film drying chamber is circulated between the film drying chamber and the solvent recovery line, and a plurality of adsorption portions provided in the solvent recovery line And at least one of the solvent and the additive contained in the gas is adsorbed and recovered, and a first open chamber is provided upstream of the adsorption unit, and the adsorption Since the second open chamber is provided downstream of the unit and the negative pressure in each open chamber is maintained, fluctuations in the amount of gas air generated when the gas flow paths of the plurality of adsorbers are switched can be prevented. so It is possible to prevent leakage to the outside of the system gas containing solvent from said film drying chamber and an open chamber.
[0046]
According to the solution casting method of the present invention, after casting a dope in which a polymer and an additive are dissolved in a solvent, the solution is peeled off and dried in a film drying chamber to form a film. In the film forming method, a solvent recovery line is connected to the film drying chamber, and a gas in the film drying chamber is circulated between the film drying chamber and the solvent recovery line, and a plurality of adsorption portions provided in the solvent recovery line And at least one of the solvent and the adsorbent contained in the gas is adsorbed and recovered, and the film drying chamber is maintained at a negative pressure. Leakage from the film drying chamber can be prevented.
[0047]
According to the solution casting method of the present invention, after casting a dope in which a polymer and an additive are dissolved in a solvent, the solution is peeled off and dried in a film drying chamber to form a film. In the film forming method, a solvent recovery line is connected to the film drying chamber, and a gas in the film drying chamber is circulated between the film drying chamber and the solvent recovery line, and a plurality of adsorption portions provided in the solvent recovery line And at least one of the solvent and the additive contained in the gas is adsorbed and recovered, and a first open chamber is provided upstream of the adsorption unit, and the adsorption A second open chamber is provided on the downstream side of the unit, and the gas in the building including the film drying chamber is sucked and at least one of the solvent and the additive in the gas is adsorbed by the additional adsorbing unit. Times An additional recovery line is provided, a third open chamber is provided between the building and the additional suction portion, the atmosphere is sucked by the second open chamber, and the first open chamber Since the gas in the two open chambers is sucked and the gas in the first open chamber is sucked in by the third open chamber, each open chamber is maintained at a negative pressure and the negative pressure of the film drying chamber is set. The pressure can also be maintained, and the processing amount of the gas containing the solvent can be reduced.
[Brief description of the drawings]
FIG. 1 is a schematic view of a film deposition line used in the solution casting method according to the present invention.
FIG. 2 is a schematic view of an open chamber used in the solution casting method according to the present invention.
FIG. 3 is a schematic view of a film deposition line of another embodiment used in the solution casting method according to the present invention.
FIG. 4 is a schematic view of a film deposition line of another embodiment used in the solution casting method according to the present invention.
[Explanation of symbols]
10 Film film production line
13 Drying zone
18 dope
25 film
30, 90, 100 Solvent recovery line
51, 55, 71 Blower
52, 70, 92, 101 Open chamber
56 Solvent gas
60, 61, 62, 95, 103 Adsorber

Claims (11)

In a solution casting method in which a dope prepared by dissolving a polymer and an additive in a solvent is cast on a support, and then peeled off and dried in a film drying chamber to form a film.
A solvent recovery line is connected to the film drying chamber, and the gas in the film drying chamber is circulated between the film drying chamber and the solvent recovery line.
Switch to use at least one of a plurality of adsorption parts provided in this solvent recovery line,
Adsorb and recover at least one of the solvent and the additive contained in the gas;
A first open chamber on the upstream side of the adsorption unit, and a second open chamber on the downstream side of the adsorption unit,
A solution casting method characterized by maintaining a negative pressure in each open chamber. The plurality of adsorbing portions desorb the solvent or the additive using at least one,
By sequentially performing this desorption,
The solution casting method according to claim 1, wherein the solution is continuously adsorbed. Maintaining the negative pressure in the first open chamber in the range of 0 to 1500 Pa,
3. The solution casting method according to claim 1, wherein the negative pressure in the second open chamber is maintained in a range of 0 to 1500 Pa. 4. The solution casting method according to claim 1, wherein the film drying chamber is maintained at a negative pressure. In a solution casting method in which a dope prepared by dissolving a polymer and an additive in a solvent is cast on a support, and then peeled off and dried in a film drying chamber to form a film.
A solvent recovery line is connected to the film drying chamber, and the gas in the film drying chamber is circulated between the film drying chamber and the solvent recovery line.
Switch to use at least one of a plurality of adsorption parts provided in this solvent recovery line,
While adsorbing and recovering at least one of the solvent and the additive contained in the gas,
A solution casting method characterized by maintaining a negative pressure in the film drying chamber. Maintaining a negative pressure in the film drying chamber;
6. The solution casting method according to claim 4 or 5, wherein, in the solvent recovery line, the amount of gas air sent to the film drying chamber is smaller than the amount of gas air sucked from the film drying chamber. The solution casting method according to any one of claims 1 to 6, wherein a part of the gas adsorbed by the adsorption unit is discharged out of the solvent recovery line. 7. The solution casting method according to claim 1, wherein a part of the gas adsorbed by the adsorbing unit is further sent to the upstream side of the adsorbing unit and adsorbed again. An additional recovery line is provided for sucking the gas in the building including the film drying chamber and absorbing and recovering at least one of the solvent and the additive in the gas by an additional adsorption unit;
Providing a third open chamber between the building and the additional suction section;
9. The solution casting method according to claim 1, wherein the inside of the third open chamber is maintained at a negative pressure. Aspirating the atmosphere through the second open chamber;
Aspirating gas in the second open chamber by the first open chamber;
Aspirating the gas in the first open chamber by the third open chamber;
The solution casting method according to claim 9, wherein the inside of each open chamber is maintained at a negative pressure. The solution casting method according to any one of claims 1 to 10, wherein the polymer is cellulose acylate.

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