JP5145281B2 - Solution casting method - Google Patents

Description

The present invention relates to a solution casting method for producing a film by using a dope to which additives for imparting various functions to the film are added.

  The polymer film has excellent light transmittance and flexibility, and can be reduced in weight and thickness. Therefore, the polymer film is used in various fields as an optical functional film. Among these, TAC films formed from cellulose esters, particularly cellulose triacetate (hereinafter referred to as “TAC”) having an average degree of acetylation of 57.5% to 62.5%, have recently been marketed including photographic photosensitive films. Is used as a protective film and an optical compensation film for polarizing plates, which are constituent members of liquid crystal display devices (LCD).

  As a method for producing a TAC film, for example, as shown in Patent Document 1, a solution casting method is known. The solution casting method can produce a film having excellent physical properties such as optical properties as compared with other production methods such as a melt casting method. In the solution casting method, first, various additives such as an ultraviolet absorber (UV agent), a matting agent, a retardation control agent, and a plasticizer are mixed with a dope in which a polymer is dissolved in a solvent such as dichloromethane or methyl acetate. Thus, a casting dope is prepared. Next, the casting dope is cast on a support by a casting die to form a casting film. Then, after the cast film becomes self-supporting on the support, the cast film is peeled off from the support as a wet film. Then, the peeled wet film is dried to obtain a product film, and the product film is wound into a roll form.

  As a method of mixing the additive with the dope, in-line addition is known in which an addition nozzle is provided in a dope flow path through which the dope flows, and the additive solution is fed to the dope through the addition nozzle. After the additive liquid is added, the dope and the additive are stirred and mixed by a static mixer as shown in Patent Documents 1 to 3. Note that Patent Document 1 describes efficient stirring and mixing by combining a slewer mixer and a kenix mixer. Patent Document 2 describes a method of stopping dope casting so that no foreign matter is generated in the dope. Further, Patent Document 3 describes that aggregates generated in the additive supply line are suppressed by making the check valve a predetermined structure.

JP 2006-076280 A JP 2006-88583 A JP 2007-215574 A

In recent years, various types of films have been demanded due to diversification of uses of polymer films. Film types are determined by the type and amount of additive liquids. Therefore, in order to produce a wide variety of films on a single film production line, depending on the type of film, the type and addition of additive liquids. It is necessary to switch the amount appropriately.

While the amount of additive liquid added is changed by changing the type of film, the amount of additive added has not reached the standard value of the film to be changed, so the film manufactured during that time is discarded. The Therefore, in order to reduce the number of films to be disposed of and suppress the manufacturing cost, it is necessary to minimize the time until the amount of additive liquid added reaches the standard value of the film to be changed. In order to minimize such time, it is necessary to reliably and quickly mix the additive liquid with the dope so that the additive is uniformly mixed in the dope.

  An object of this invention is to provide the solution casting method which can perform mixing of the additive liquid with respect to dope reliably and rapidly.

  The solution casting method of the present invention includes a dope preparation step for preparing a dope containing a polymer and a solvent, an additive solution addition step for sending an additive solution into a pipe for feeding the dope, and a solution feed for the dope. Using a dynamic mixer provided with a plurality of stages of stators and rotors in the direction, mixing the dope and the additive liquid to obtain a casting dope, and using the casting dope, a film And a film forming process for manufacturing the film.

  The dope viscosity in the additive liquid addition step is preferably 30 Pa · s or more. The viscosity ratio (%) between the additive solution and the dope (100 × (viscosity of additive solution) / (viscosity of dope)) is preferably 10% or less. The outer peripheral speed of the dynamic mixer is preferably 0.1 m / second or more and 1.0 m / second or less. It is preferable to control the driving of the rotor so that the static pressure in the dynamic mixer is 0.1 MPa or more. The stator preferably stores the rotor rotatably such that a clearance of 0.3 mm or more and 1.5 mm or less is formed between the stator and the rotor. The dope stays in each stator and rotor is preferably 0.1 seconds or longer.

  In the additive liquid mixing step, in addition to the dynamic mixer, the dope and the additive liquid are mixed by a static mixer provided on the upstream side or the downstream side of the dynamic mixer. Is preferred.

  According to the present invention, the additive liquid can be reliably and rapidly mixed with the dope.

It is the schematic of solution casting apparatus. It is the schematic of an in-line mixer. It is sectional drawing of a dynamic mixer. It is a perspective view of a rotor and a stator. It is the schematic of a film forming unit.

  As shown in FIG. 1, the solution casting apparatus 10 includes a dope preparation unit 11, an additive liquid addition mixing unit 12, and a film forming unit 13.

  The dope preparation unit 11 includes a mixing unit 15 that mixes the polymer 26 and a solvent to create a crude solution, a dissolution unit 16 that dissolves the crude solution to prepare the dope 31, a concentration unit 17 that concentrates the dope 31, It is comprised from the storage part 18 which stores dope 31. FIG. The mixing unit 15 includes first and second tanks 21 and 22, a dissolution tank 23, a storage tank 24, and a pump 25. A polymer 26 is placed in the first tank 21, and the polymer 26 is charged into the dissolution tank 23 by a predetermined amount measured by an attached meter (not shown). A solvent 27 is placed in the second tank 22, and the solvent 27 is charged into the dissolution tank 23 by a predetermined amount measured by an attached pump (not shown).

  The polymer 26 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 TAC is used. When using granular TAC, 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. .

  The details of cellulose acylate are described in paragraphs [0140] to [0195] of JP-A-2005-104148. The same applies to additives such as solvents and plasticizers, deterioration inhibitors, UV absorbers (UV agents), optical anisotropy control agents, retardation control agents, dyes, matting agents, release agents, release accelerators, etc. JP-A-2005-104148 describes in detail in paragraphs [0196] to [0516]. A film production method by a solution casting method using cellulose acylate is also described in detail in paragraphs [0517] to [0913] of JP-A-2005-104148. These descriptions can also be applied to the present invention.

  The solvent 27 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 27 may be one kind of compound or a mixed solvent in which a plurality of compounds are mixed. 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 dissolution tank 23 includes a stirring blade (not shown), and the polymer and the solvent in the dissolution tank 23 are stirred by the rotation of the stirring blade. By this stirring, a crude solution in which the polymer is not completely dissolved in the solvent is obtained.

  The crude solution in the dissolution tank 23 is temporarily stored in the storage tank 24. As a result, the dissolution tank 23 is emptied, and the preparation of the crude dissolution solution can be started in the dissolution tank 23. Therefore, by providing the two tanks of the dissolution tank 23 and the storage tank 24, it is possible to produce a crude dissolution liquid by a batch method. The storage tank 24 is also provided with a stirring blade. By rotating the stirring blade, the crude solution is stirred and made uniform.

  The crude solution in the storage tank 24 is sent to the first heater 30 of the dissolution unit 16 by the pump 25. The first heater 30 includes a multi-tube heat exchanger, a static mixer, and the like, and heats the crude solution while stirring. The heating temperature is preferably 50 to 120 ° C., and the heating time is preferably 5 to 30 minutes. By this heating, a solute such as a polymer necessary for solution film formation is completely dissolved without deformation and becomes a dope 31.

  The dope 31 heated by the first heater 30 is sent to the cooler 32. The cooler 32 cools the dope 31 to a temperature equal to or lower than the boiling point of the main solvent constituting the dope 31. The cooled dope 31 is sent to the first filter 34 by the pump 33. The first filter 34 filters the dope 31 to remove impurities in the dope 31. The first filter 34 is provided with a filter exchanger (not shown) for exchanging the filter main body, which has become difficult to filter due to many impurities, with a new filter main body. The dope 31 after filtration is sent to the concentration unit 17 by the pump 35.

  In the concentration unit 17, the dope 31 after filtration is heated by the second heater 40, and the heated dope 31 is sent to the flash tank 41. In the flash tank 41, the dope 31 is concentrated by a flash concentration method. The concentrated dope 31 is sent to the storage unit 18 by the pump 42. The storage tank 43 of the storage unit 18 stores the dope 31 from the flash tank 41 and sends the dope 31 in the storage tank 43 to the additive liquid addition mixing unit 12 by a pump 45 as necessary. The concentrating part is provided as necessary and may be omitted.

  The additive liquid addition mixing unit 12 includes first to fourth additive liquid supply units 47 to 50 for supplying an additive to the dope 31, an in-line mixer 51 for stirring and mixing the dope 31 to which the additive is supplied, A second filter 53 for removing foreign substances from the dope 31 and a controller 58 are provided.

  The first additive liquid supply unit 47 includes a plasticizer supply unit 74, a solvent supply unit 75, a mixing tank 76, and an additive liquid tank 77. The plasticizer supply unit 74 includes a plasticizer tank that stores the plasticizer, and the solvent supply unit 75 includes a solvent tank that stores the solvent 27 (both not shown). Each tank is equipped with a measuring instrument. A predetermined amount measured by an attached measuring instrument (not shown) is put into the mixing tank 76. The plasticizer concentration is preferably in the range of 10% by weight to 60% by weight.

The mixing tank 76 mixes the plasticizer and the solvent supplied from the supply units 74 and 75 with stirring to prepare the additive liquid 78a. The prepared additive liquid 78a is temporarily stored in an additive liquid tank 77 that can be stirred and mixed. Thereby, since the additive liquid 78a in the mixing tank 76 can be emptied, the additive liquid 78a can be newly prepared in the mixing tank 76. The additive liquid 78 a in the additive liquid tank 77 is supplied to the addition nozzle 62 a by the pump 64. The rotational speed of the pump 64 is controlled by the controller 58, and the amount of additive liquid 78a added is adjusted according to the rotational speed of the pump 64.

A check valve 61 is provided in the pipe 65 connecting the additive liquid tank 77 and the addition nozzle 62a (see FIG. 2) in the first static mixer 80. The check valve 61 prevents the additive liquid 78a sent to the addition nozzle 62a from flowing backward. The supply of the additive liquid to the addition nozzle is preferably performed after the rotation of the rotors 91 to 94 (see FIG. 3) in the dynamic mixer described later is started.

  Other 2nd-4th additive liquid supply parts 48-50 are also comprised similarly to the 1st additive liquid supply part 47, and abbreviate | omit detailed description. The second additive liquid supply unit 48 supplies an additive liquid 78b obtained by mixing the matting agent and the solvent 27 from the addition nozzle 62b. The third additive liquid supply unit 49 supplies an additive liquid 78c obtained by mixing the UV agent and the solvent 27 from the addition nozzle 62c. The fourth additive liquid supply unit 50 supplies an additive liquid 78d obtained by mixing the retardation control agent and the solvent 27 from the addition nozzle 62d. In the present embodiment, four additive liquid supply units are provided, but these may be increased or decreased as necessary.

  The controller 58 controls the rotational speed of the pump 64 installed in the first to fourth additive liquid supply units 47 to 50. The controller 58 associates the film type with the addition amounts of the additive liquids 78a to 78d including the plasticizer, matting agent, UV agent, and retardation used in the first to fourth additive liquid supply units 47 to 50. A stored LUT 58a is provided. The controller 58 determines the amount of additive liquid 78a-78d added according to the type of film produced from the LUT 58a. And the rotation speed of the said pump 64 is controlled so that the additive liquids 78a-78d of the calculated | required addition amount are supplied to the addition nozzles 62a-62d. The addition amount of the additive liquid is a discharge amount of the additive liquid discharged from the addition nozzle per unit time.

  As shown in FIG. 2, the in-line mixer 51 is a first static mixer that mixes the dope 31 and the additive liquids 78 a to 78 d from the storage unit 18 in order from the upstream side with respect to the liquid feeding direction of the dope 31. 80, a dynamic mixer 81 to which the dope 31 mixed in the first static mixer 80 is fed by rotors 91 to 94 (see FIG. 3) rotated by driving force, and the dope 31 that has passed through the dynamic mixer 81 is fed A second static mixer 82 is provided. The mixers 80 to 82 are connected by a pipe 84. In each of the mixers 80 to 82, dope channels 80a to 82a through which the dope 31 flows are formed. In the dope flow path 80a of the first static mixer 80, addition nozzles 62a to 62d for discharging additive liquids 78a to 78d are provided.

  The first static mixer 80 includes a number of elements (not shown) formed by twisting a rectangular plate 180 degrees. These many elements are arranged in series in the dope channel 80a, and the additive liquids 78a to 78d and the dope 31 are dispersed and mixed. At the time of the first static mixer 80, the additive liquids 78 a to 78 d are not completely dissolved in the dope 31. The dope 31 that has passed through the first static mixer 80 is sent to the dynamic mixer 81.

  Although the details will be described later, the dynamic mixer 81 stirs and mixes the dope 31 by the rotors 91 to 94 (see FIGS. 3 and 4) that are rotated by the driving force of the motor 102. In the dynamic mixer 81, the additive liquids 78 a to 78 d are almost completely dissolved in the dope 31. The dope 31 that has passed through the dynamic mixer 81 is sent to the second static mixer 82. In the second static mixer 82, the additive liquids 78 a to 78 d are completely dissolved in the dope 31 by a large number of elements (not shown) similar to the first static mixer 80. Foreign material is removed from the dope 31 that has passed through the second static mixer 81 by the second filter 53 (see FIG. 1) to become a casting dope 54. The casting dope 54 is sent to a casting die 147 (see FIG. 5) of the film forming unit 13.

  As shown in FIG. 3, the dynamic mixer 81 includes a casing 90, rotors 91 to 94, a rotation shaft 95, stators 96 to 99, a motor 102, and an electromagnet unit 103. In addition to the dope channel 81a, the casing 90 includes a supply pipe 106 into which the dope 31 from the first static mixer 80 enters the dope channel 81a, a discharge pipe 107 from which the dope 31 exits from the dope channel 81a, and a rotation. A shaft support chamber 108 for supporting the shaft 95 is provided. The partition wall 110 that divides the dope channel 81a and the shaft support chamber 108 is formed with a shaft insertion hole 110a through which the rotation shaft 95 is inserted. Further, a mechanical seal 112 seals between the rotating shaft 95 and the partition wall 110. This prevents the dope 31 from leaking to the shaft support chamber 108 side. In this embodiment, the dynamic mixer is installed in the horizontal direction. However, the present invention is not limited to this, and the dynamic mixer may be installed in the vertical direction so that the dope liquid feeding direction is from bottom to top.

  As shown in FIGS. 3 and 4, the four rotors 91 to 94 are attached to the rotating shaft 95 at a constant pitch with respect to the axial direction X of the rotating shaft. The rotor 91 has a large diameter on the inlet side of the dope 31 and a small diameter on the outlet side. The rotors 91 to 94 are attached to the rotation shaft 95 in series at a constant pitch in the longitudinal direction. Four stirring blades 116 are attached to the circumferential surfaces of the rotors 91 to 94 at intervals of 90 ° in the circumferential direction. Each stirring blade 116 is twisted so as to rotate 90 ° about the rotation shaft 95 from one end to the other end, and is attached in a spiral manner to the peripheral surfaces of the rotors 91 to 94. Note that the number of rotors is not limited to four, and may be two to three or five or more. Further, the number of stirring blades need not be limited to four.

The four stators 96 to 99 are installed in the dope channel 81 a along the liquid feeding direction of the dope 31. A supply port 120 into which the dope from the supply pipe enters is formed on one side surface of the stator 96, and a discharge port 121 through which the dope enters and a shaft hole 122 through which the rotary shaft 95 is inserted are formed on the other side surface. Is formed. In addition, a hollow portion 124 in which the rotor 91 is accommodated is formed in the stator 96 between the supply port 120 and the discharge port 121. The inner peripheral surface 127 of the stator 96 is a tapered surface inclined along the axial direction X.

The motor 102 rotates the rotors 91 to 94 by applying a driving force to the rotating shaft 95. The dope 31 that has entered the dope channel 81 a is first stirred by the rotation of the stirring blade 116. Thereby, the additive liquids 78a to 78d are mixed in the dope 31. After the dope 31 exits the discharge port 121 of the stator 96, the dope 31 is similarly stirred by the rotation of the stirring blades of the rotors 92 to 94, and the additive liquids 78a to 78d are mixed with the dope 31. . In this manner, the dope 31 is stirred by the four stirring blades until the dope 31 enters the supply pipe 106 and exits from the discharge pipe 107, so that the additive liquids 78a to 78d are almost completely dissolved in the dope 31. To do.

  As described above, by using the dynamic mixer 81, the additive liquids 78 a to 78 d are sufficiently mixed even in the dope 31 having a viscosity of 30 Pa · s or more, and completely dissolved or uniform in the dope 31. To disperse.

  Further, the viscosity ratio (%) (100 × (additive viscosity) / (dope viscosity)) between the viscosity of the additive liquids 78a to 78d and the viscosity of the dope 31 is preferably 10% by the dynamic mixer 81. By making it below, the mixing property of the additive liquids 78a to 78d with respect to the dope 31 can be further enhanced. On the other hand, when the viscosity ratio is less than 10%, the additive liquids 78 a to 78 d cannot be sufficiently mixed with the dope 31. “Mixability” in the present embodiment refers to how much the additive liquids 78 a to 78 d are mixed in the dope 31. The viscosity ratio may be 0% or a value close to 0%.

In addition, by setting the outer peripheral speed of the dynamic mixer 81 to preferably 0.1 m / second or more and 1.0 m / second or less, the dynamic mixer 81 only has a sufficient mixing property for the high viscosity dope 31 as described above. In addition, the additive liquids 78a to 78d can be stably mixed without degrading the performance of the dynamic mixer 81. On the other hand, when the outer peripheral speed is less than 0.1 m / sec, the additive liquids 78 a to 78 d cannot be sufficiently mixed with the dope 31.

On the other hand, when the outer peripheral speed exceeds 1.0 m / sec, frictional heat is generated between the stirring blade 116 and the dope 31, so that the dope 31 generates heat and foaming may occur. When foaming occurs in the dope 31, the performance of the dynamic mixer 81 is lowered, so that the additive liquids 78 a to 78 d cannot be stably mixed. In addition, since frictional heat is also generated between the stirring blade 116 and the mechanical seal 112, the durability of the mechanical seal 112 is reduced, and the dope 31 may leak into the shaft support chamber 108.

Further, by controlling the driving of the rotors 91 to 94 so that the static pressure in the dope channel 81a is preferably 0.1 MPa or more, the additive liquid can be stably added without degrading the performance of the dynamic mixer 81. Mixing of 78a-78d can be performed. On the other hand, if the static pressure is less than 0.1 MPa, the dope 31 may foam due to the generation of frictional heat due to contact with the stirring blade 116, so that the performance of the dynamic mixer 81 is lowered and stable. In some cases, the additive liquids 78a to 78d cannot be mixed.

The dope 31 flows from the supply port 120 to the discharge port 121 without resistance by setting the clearance CL between the inner peripheral surface 127 of the stator and the stirring blade 116 of the rotor to preferably 0.3 mm or more and 1.5 mm or less. At the same time, it has sufficient miscibility with the high viscosity dope 31 as described above. On the other hand, when the clearance CL is less than 0.3 mm, the resistance is increased and the flow of the dope 31 is deteriorated, so that the mixing property is deteriorated. On the other hand, when the clearance CL exceeds 1.5 mm, the shearing stress due to the stirring blade 116 is insufficient, and the mixing property is lowered. The clearance CL shown in FIG. 3 indicates the distance between the stirring blade 116 located near the center with respect to the axial direction X and the inner peripheral surface 127, but this is an example and is located at the tip. The distance between the stirring blade 116 and the inner peripheral surface 127 may be used.

  In addition, by setting the time for the dope 31 to stay in each stator and rotor to be preferably 0.1 seconds or longer, the dope 31 has sufficient mixing properties with respect to the high viscosity dope 31 as described above. When the residence time is less than 0.1 seconds, the additive liquids 78 a to 78 d cannot be sufficiently mixed with the dope 31. The residence time refers to the time from when the dope enters each stator until it exits, that is, the time from when the dope 31 enters the supply port 120 to the exit from the discharge port 121 in the case of the stator 96.

  The electromagnet portion 103 is provided in the shaft support chamber 108 so as to face the magnet portion 130 attached to the rotating shaft 95. The rotating shaft 95 is supported so as to be rotatable without contact with the electromagnet portion 103 by a force attracting or pushing between the electromagnet portion 103 and the magnet portion 130.

  As shown in FIG. 5, the film forming unit 13 includes a casting chamber 140, a transfer portion 141, a tenter 142, a drying chamber 143, and a winder 144, and a film 146 using the casting dope 54. Manufacturing. In the casting chamber 140, a casting die 147 in which a discharge port for the casting dope 54 is formed, a casting drum 148 that acts as a support, and a peeling roller 149 are disposed.

  The casting dope 54 is cast on a casting drum 148 that is rotating endlessly via a casting die 147. Thereby, a casting film 151 is formed on the casting drum 148. The surface temperature of the casting drum 148 is preferably substantially constant within a range of −10 ° C. to 10 ° C. If the casting dope 54 is cast on such a casting drum 148, the casting dope 54 is quickly cooled, so that a gel-like casting film 151 is formed within a short time. When the casting film 151 has self-supporting properties, the casting film 151 is peeled off as the wet film 153 while being supported by the peeling roller 149.

  In the crossover part 141, it conveys while supporting the wet film 153 with many rollers, and it dries in the meantime. In the tenter 142, both end portions of the wet film 153 are conveyed while being held by holding means such as a pin, and are dried during that time. In the tenter 142, the wet film 153 is stretched or relaxed in the width direction by moving the holding means in a direction in which the width of the wet film 153 is expanded or contracted. The wet film 153 that has exited the tenter 142 is dried by the drying air in the drying chamber 143. Thereby, the film 146 as a product is obtained. The film 146 is wound up in a roll shape around the core 155 by the winder 144.

  Casting chamber, casting die, casting drum structure, co-casting, peeling method, stretching, drying conditions for each process, handling method, curl, 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. In the above embodiment, the cooling gelation method is adopted in which the casting film is cooled and gelled on the casting drum so as to have self-supporting property. However, the casting film is dried on the band or the drum to be self-supporting. The present invention can be carried out in the same manner even in a drying system having a water content.

  The film obtained by the present invention has high transparency, expresses a desired retardation value, and has low temperature 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 use 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, TN type, STN type, VA type, OCB type as a liquid crystal display device. The reflection type and other examples are described in detail, and these descriptions can also be applied to the present invention.

  In the above embodiment, various additive liquids are added to the dope using four additive nozzles provided corresponding to the four additive liquid supply units. Instead, for example, one additive nozzle is added to the dope. Four additive liquid supply units may be connected, and the various additive liquids may be added together using one nozzle.

  In the above embodiment, the additive liquid is added to the dope immediately before the casting die. However, before the dope is concentrated in the flash tank or before the dope is stored in the storage tank, the additive liquid is doped. You may add to.

  In the said embodiment, after adding an additive liquid to dope, an additive liquid is used using the 1st static mixer, dynamic mixer, and 2nd static mixer which were provided in order in the dope liquid feeding direction. The additive solution was completely dissolved in the dope by mixing with the dope, but it is not necessary to be limited thereto. For example, when the viscosity ratio between the dope and the additive solution is low, the additive solution may be mixed using only a dynamic mixer.

  In the above embodiment, the single layer casting has been described as an example. In addition to this, in addition to the base layer, the outer layer may be simultaneously or sequentially cast on both surfaces of the base layer. Also in this case, it is preferable to prepare a dope by dissolving a polymer in a solvent, and then add an additive to each dope corresponding to each layer, as in the above embodiment.

  Hereinafter, the present invention will be described specifically by way of examples.

  As shown in FIG. 2, the 1st static mixer 80, the dynamic mixer 81, and the 2nd static mixer 82 were installed in order from the upstream with respect to the liquid feeding direction of the dope 31. Dope channels 80a to 82a were provided in the mixers 80 to 82, respectively. The dope channel 80a of the first static mixer 80 includes an additive liquid 78a containing a plasticizer, an additive liquid 78b containing a matting agent, an additive liquid 78c containing a UV agent, and an additive containing a retardation control agent. Addition nozzles 62 a to 62 d for adding the liquid 78 d to the dope 31 were provided. In the first static mixer 80, the dope 31 and the additive liquids 78a to 78d were mixed by using 24 elements formed by twisting a rectangular plate by 180 degrees.

Here, the plasticizer concentration in the additive liquid 78a was 60% by weight. The viscosity of the dope 31 was 30 Pa · s. The viscosity of the additive liquid 78a was 3 Pa · s. Therefore, the viscosity ratio between the additive liquid 78a and the viscosity of the dope 31 is set to 10%. The addition ratio of the additive liquid 78a and the dope 31 was 5%.

As shown in FIG. 3, the dope channel 81 a of the dynamic mixer 81 is configured to rotatably store the four rotors 91 to 94 and the rotors 91 to 94 along the liquid feeding direction of the dope 31. Stators 96 to 99 were provided. Four stirring blades 116 were attached to the rotor body 115 of each rotor at a pitch of about 90 ° in the circumferential direction. A driving force was applied to the rotating shaft 95 from the motor 102 to rotate the stirring blade 116. The dope 31 and the additive liquids 78 a to 78 d were mixed by the rotation of the stirring blade 116.

Here, the outer peripheral speed of the dynamic mixer 81 was set to 1.0 m / sec. The static pressure in the dope channel 81a was 0.4 MPa. The clearance CL between the inner peripheral surface 127 of the stators 96 to 99 and the stirring blades 116 of the rotors 91 to 94 was set to 0.3 mm. The time during which the dope 31 stays in each rotor and stator (hereinafter referred to as “residence time”) was set to 0.1 seconds.

  The same procedure as in Example 1 was performed except that the number of rotors and the number of stators was three, and the additive liquids 78a to 78d were mixed only by the dynamic mixer 81.

  The same procedure as in Example 1 was performed except that the number of rotors and stators was two, the clearance CL was 1.5 mm, and the additive liquids 78a to 78d were mixed only by the dynamic mixer 81.

  The same as in Example 1 except that the number of rotors and stators is two, the outer peripheral speed of the dynamic mixer is 0.1 m / second, and the additive liquids 78a to 78d are mixed only by the dynamic mixer 81. It was.

  The same as in Example 1 except that the number of rotors and stators is two, the static pressure in the dope channel 81a is 0.1 MPa, and the additive liquids 78a to 78d are mixed only by the dynamic mixer 81. did.

The same as in Example 1 except that the number of rotors and stators is two, the static pressure in the dope channel 81a is 0.09 MPa, and the additive liquids 78a to 78d are mixed only by the dynamic mixer 81. did.

The same procedure as in Example 1 was performed except that the number of rotors and stators was two, the clearance CL was 0.29 mm, and the additive liquids 78a to 78d were mixed only by the dynamic mixer 81.

The same procedure as in Example 1 was performed except that the number of rotors and stators was two, the clearance CL was 1.51 mm, and the additive liquids 78a to 78d were mixed only by the dynamic mixer 81.

The same as in Example 1 except that the number of rotors and stators is two, the rotation speed of the stirring blade 116 is 1.1 m / sec, and the additive liquids 78a to 78d are mixed only by the dynamic mixer 81. did.

The same as in Example 1 except that the number of rotors and stators is two, the rotation speed of the stirring blade 116 is 0.09 m / sec, and the additive liquids 78a to 78d are mixed only by the dynamic mixer 81. did.

The same procedure as in Example 1 was performed except that the number of rotors and stators was two, the residence time was 0.09 seconds, and the additive liquids 78a to 78d were mixed only by the dynamic mixer 81.

The same procedure as in Example 1 was performed except that the number of rotors and the number of stators was one each, and the additive liquids 78a to 78d were mixed only by the dynamic mixer 81.

The same as in Example 1 except that the number of rotors and stators is two each, and the additive liquids 78a to 78d are mixed only by a static mixer (6-N16-22 (6) -1 manufactured by Noritake Co., Ltd.). did.

[result]
The results of Examples 1 to 13 are shown in Table 1.

  In “Mixer Pattern” in Table 1, “Static / Dynamic / Static” means that a static mixer, a dynamic mixer, and a static mixer were installed in order from the upstream side. “Static” indicates that a static mixer was used. In addition, the evaluation “◎” indicates that the dope and the additive are uniformly mixed. “◯” indicates that the dope and the additive are mixed, but only a part is non-uniform. “Δ” indicates that the dope and the additive are not partially mixed. “X” indicates that the dope and the additive are hardly mixed. “Performance failure” indicates that the performance of the mixer has deteriorated and the dope cannot be mixed with the additive. “Production stop” indicates that production failed due to repeated mixer failures.

  In Examples 1 to 5, the additive liquid was highly miscible with the dope, and the additive could be stably mixed without any failure of the mixer. Moreover, in Examples 1 and 2, the mixing property could be further improved by increasing the number of rotors.

  On the other hand, in Example 6, since static pressure was low compared with each Example, foaming generate | occur | produced and the performance of the mixer fell because of this foaming. Moreover, in Example 7, since the clearance CL was too small compared with each Example, mixing property fell, and in Example 8, the clearance CL was too large compared with each Example, and mixing property reduced extremely. . Moreover, in Example 9, since the outer peripheral speed was too high compared with each Example, the mixers were continuously broken and production was impossible. Moreover, in Example 10, since the outer peripheral speed was too slow compared with each Example, the mixability fell. Moreover, in Example 11, since the residence time of dope was too short compared with each Example, the mixability fell extremely. Moreover, in Example 12, since the additive was mixed with only one rotor, the mixing property was lowered. Moreover, in Example 13, since mixing was performed only with the static mixer, the mixing property was extremely lowered.

DESCRIPTION OF SYMBOLS 10 Solution casting apparatus 31 Dope 78a-78d Additive liquid 81 Dynamic mixer 81a Dope flow path 91-94 Rotor 95 Rotating shaft 96-99 Stator 116 Stirring blade 124 Hollow part 127 Inner peripheral surface

Claims (8)

A dope preparation step of preparing a dope comprising a polymer and a solvent;
In the pipe for feeding the dope, an additive liquid addition step for sending the additive liquid,
Additive liquid mixing step of obtaining a casting dope by mixing the dope and the additive liquid by a dynamic mixer provided with a plurality of stages of stators and rotors in the liquid feeding direction of the dope,
And a film forming process for manufacturing a film using the casting dope.   The solution casting method according to claim 1, wherein the dope has a viscosity of 30 Pa · s or more in the additive solution adding step.   3. The solution according to claim 1, wherein a viscosity ratio (%) of the additive solution and the dope (100 × (viscosity of additive solution) / (dope viscosity)) is 10% or less. Film forming method.   The solution casting method according to any one of claims 1 to 3, wherein an outer peripheral speed of the dynamic mixer is 0.1 m / second or more and 1.0 m / second or less.   5. The solution casting method according to claim 1, wherein the driving of the rotor is controlled so that the static pressure in the dynamic mixer is 0.1 MPa or more.   The said stator accommodates the said rotor rotatably so that a clearance of 0.3 mm or more and 1.5 mm or less may be formed between the said rotor. Solution casting method.   The solution casting method according to any one of claims 1 to 6, wherein the dope stays in each stator and rotor for 0.1 seconds or more.   In the additive liquid mixing step, in addition to the dynamic mixer, the dope and the additive liquid are mixed by a static mixer provided on the upstream side or the downstream side of the dynamic mixer. The solution casting method according to claim 1, wherein:

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