JP6538600B2 - Solution film forming apparatus and method - Google Patents

Description

  The present invention relates to a solution casting apparatus and method.

  In the market of small-to-medium-sized displays mounted in smartphones and tablet terminals, further high definition is required. Therefore, for the films used for these displays, it is required that the smoothness on the film surface be further enhanced than before. In addition, for films used for these displays, it is also required to make the thickness thinner, specifically 40 μm or less.

  Usually, the film is manufactured in a long size, cut into a desired size and used. The production method of the long film is roughly classified into a solution film forming method and a melt film forming method. Among them, the solution film forming method has been superior to the melt film forming method in that a film having a smoother film surface can be produced. In the solution film forming method, a dope in which a polymer is dissolved in a solvent flows out from a casting die onto a running support to form a cast film, and the cast film is peeled off from the cast support to produce a film. How to The cast film cast on the support is such that the solvent is volatilized by the blowing of the drying air while being transferred to the peeling position where the solvent is peeled off from the support, and the solvent can be transported after peeling. Until dried.

  On the other hand, the casting film, in particular, the casting film immediately after casting, has an unstable surface, and if the solvent is volatilized rapidly, there is a problem that unevenness in thickness occurs. For this reason, in the following patent document 1, thickness unevenness is prevented by spraying the solvent gas containing a solvent with respect to a casting membrane. Further, in Patent Document 2 below, suction of the solvent gas and supply of the solvent gas are simultaneously performed to suppress abrupt evaporation of the solvent, thereby preventing thickness unevenness.

JP, 2013-156488, A JP, 2005-096182, A

  However, if the solvent gas is sprayed to the casting membrane as in Patent Document 1 described above, the drying of the casting membrane does not proceed, and the time until peeling is long, and there is a problem that the production efficiency is poor. On the other hand, in Patent Document 2 described above, since not only the supply of the solvent gas but also the suction is performed in a predetermined area, the concentration of the solvent in this area is controlled to an extent that the drying of the casting film proceeds appropriately. It is also possible to suppress the decrease in production efficiency.

  However, in Patent Document 2 described above, since the suction position and the supply position of the solvent gas are not taken into consideration, the concentration of the solvent gas at each position in the area is different, which causes the cast film to have each position. There is a problem that the degree of drying differs and thickness unevenness occurs.

  This invention is made in view of the said subject, and it aims at providing the solution film-forming apparatus and method which can also prevent thickness nonuniformity, suppressing the fall of production efficiency.

  In order to solve the above problems, a solution casting apparatus according to the present invention is a solution casting apparatus in which a polymer solution in which a polymer is dissolved in a solvent is cast on a running support to form a cast film. A pair of wind shields provided along the side edges of the spread film and dividing the space above the support into an inner area where the cast film is cast and an outer area outside the cast film, and an inner area A solvent gas suction mechanism for suctioning a solvent gas containing a solvent volatilized from a casting film by suction from a suction port disposed inside, a solvent gas containing a solvent for dissolving a polymer, a support and a windproof plate And a solvent gas supply mechanism for supplying a gap between the two.

  When the mass of the solvent in the casting membrane is MS and the mass of the casting membrane is MF, the solvent content in the area represented by {MS / (MF-MS)} × 100 is 200% or more It is preferable to perform suction by the gas suction mechanism and supply by the solvent gas supply mechanism.

  It is preferable to provide a lid member connecting the upper end portion of one of the wind shield plates and the upper end portion of the other wind shield plate, and to cover the inner region from above with the lid member.

  The inner region may be provided with an infrared irradiator for irradiating the cast film with infrared light to promote volatilization of the solvent contained in the cast film.

  The solvent gas supply mechanism may supply from a supply port provided on the side of the lower end of the windproof plate.

  The solvent gas supply mechanism may vertically supply a solvent gas containing a solvent for dissolving the polymer from the supply port toward the lower support.

  A / 5 ≦ B when the concentration of the suction gas as the solvent gas suctioned by the solvent gas suction mechanism is A, and the concentration of the supply gas as the solvent gas supplied by the solvent gas supply mechanism is B. preferable.

  It is preferable to satisfy B ≦ A, where A is a concentration of suction gas which is a solvent gas to be sucked by the solvent gas suction mechanism, and B is a concentration of a supply gas which is a solvent gas supplied by the solvent gas supply mechanism.

  A sensor for measuring the concentration of the solvent gas sucked by the solvent gas suction mechanism, and a supply gas concentration control mechanism for controlling the concentration of the solvent gas supplied from the solvent gas supply mechanism based on the measurement result of the sensor preferable.

  The solvent gas containing the solvent gas sucked by the solvent gas suction mechanism may be supplied from the solvent gas supply mechanism.

  The thickness of the film produced by peeling the cast film from the support may be 40 μm or less.

  Further, in order to achieve the above object, according to the solution casting method of the present invention, there is provided a casting film forming step of casting a polymer solution in which a polymer is dissolved in a solvent onto a running support to form a casting film. A transfer step of transferring the cast film to the peeling position to peel away from the support, and a peeling step of peeling the cast film from the support at the peeling position; In the step, a space above the support is formed by a pair of wind shields provided along the side edge of the casting membrane, an inner area where the casting membrane is cast and an outer area outside the casting membrane. The support gas and the air shield plate are provided with a solvent gas containing a solvent that dissolves the polymer, suctions a solvent gas containing the solvent volatilized from the cast film, and sucks in the solvent gas containing the solvent volatilized from the cast film. Supply through the gap between

  According to the present invention, it is possible to suppress a decrease in production efficiency by drawing solvent gas from the region above the cast film (inner region) to advance the drying of the cast film. Further, according to the present invention, each portion in the vicinity of the surface of the casting film is supplied with the solvent gas from the site where new air flows in with the suction of the solvent gas, that is, the gap between the windproof plate and the support. The solvent concentration at the position can be made uniform (the solvent concentration near the side edge of the cast film can be prevented from decreasing relative to the solvent concentration near the center of the cast film), and thickness unevenness can also be prevented.

It is the schematic of a solution film-forming apparatus. It is an explanatory view showing the composition of a solvent gas suction mechanism. It is explanatory drawing which shows the structure of a solvent gas supply mechanism.

  As shown in FIG. 1, the solution film forming apparatus 10 of the present invention casts the dope 12 on a support to form a cast film 14, and after the cast film 14 is dried, it is peeled off from the support Thus, the film 16 is manufactured, and a casting device 20, a tenter 22, a roller drying device 24, a slitter 26, and a winding device 28 are provided in this order from the upstream side. In the present embodiment, the film 16 having a thickness of 10 μm to 40 μm is manufactured by the solution film forming apparatus 10.

  The dope 12 is a polymer solution in which a polymer is dissolved in a solvent, and in this embodiment, cellulose triacetate (TAC) is used as the polymer. The polymer solution may contain other than the polymer as a solid content to be the film 16. As solid content other than a polymer, there exist a plasticizer, a ultraviolet absorber, the retardation control agent, microparticles | fine-particles etc., for example, and the plasticizer is included in this embodiment. The fine particles are so-called matting agents used for the purpose of imparting slipperiness and scratch resistance to the film 16 and suppressing sticking when the film 16 is stacked. The solid content in the dope 12 is in the range of 10% or more and 23% or less in percentage indicated by MP / (MP + MS) × 100, where MP is mass of solid content and MS is mass of solvent. In this embodiment, it is 19%.

  In the present embodiment, a mixture of dichloromethane and methanol is used as the solvent. The solvent used in the solution film formation is usually heavier than the gas in the gas state, and the solvent of the present embodiment is also heavier than the gas in the gas state. The solvent is not limited to the example of the present embodiment, and butanol, ethanol, propanol and the like may be used, for example, and two or more of them may be used in combination as a mixture.

  In the present specification, the solvent content (unit;%) of the film 16 (or the casting film 14) is a value on a dry basis. Specifically, the solvent content (unit;%) of the film 16 (or the cast film 14) in an arbitrary area A corresponds to the mass of the solvent in the area A as MS, and the film 16 (or the cast film 14) in the area A It is a percentage shown by {MS / (MF-MS)} × 100, where MF is the mass of

  The casting apparatus 20 includes a belt 30 which is an endless casting support formed in an annular shape, and a first roller 32 and a second roller 34 which rotate in the circumferential direction. The belt 30 is wound around the circumferential surfaces of the first roller 32 and the second roller 34. At least one of the first and second rollers 32 and 34 is a drive roller which receives supply of drive force from the drive means and rotates. In the present embodiment, both the first roller 32 and the second roller 34 are driven. It is considered to be a roller. When the drive roller rotates in the circumferential direction, the belt 30 in contact with the circumferential surface travels and circulates in the longitudinal direction.

  Above the belt 30, a casting die 36 for discharging the dope 12 is provided. The dope 12 is continuously flowed out of the casting die 36 onto the belt 30 running, whereby the dope 12 is cast on the belt 30 to form the casting film 14. The position where the dope 12 starts contact with the belt 30 is hereinafter referred to as a casting position PC.

  In the present embodiment, the casting die 36 is provided above the belt 30 on the first roller 32, and the casting position PC is on the first roller 32. However, the position of the casting die 36 is not limited to this. For example, the casting die 36 may be provided above the belt 30 between the first roller 32 and the second roller 34. In this case, it is preferable to dispose the casting die 36 above the belt 30 supported by the roller 38 disposed below the belt 30 between the first roller 32 and the second roller 34.

  Each of the first roller 32 and the second roller 34 includes a temperature controller (not shown) that controls the peripheral surface temperature. For example, the first roller 32 is cooled by the temperature controller so that the circumferential surface temperature falls within a predetermined range. By cooling the first roller 32, the belt 30 is cooled each time it makes one revolution. As a result, even if the belt 30 travels continuously and continues to be heated by the intake air drying unit 40 and the air blowing and drying unit 42 described later, the temperature rise of the belt 30, particularly, both side portions is suppressed. Further, the second roller 34 is heated by the temperature controller so that the circumferential surface temperature falls within a predetermined range. By heating the second roller 34, the casting film 14 is more effectively dried.

  The circumferential surface temperature of the first roller 32 is preferably in the range of 3 ° C. to 30 ° C., more preferably in the range of 5 ° C. to 25 ° C., and in the range of 8 ° C. to 20 ° C. It is further preferable to do. The circumferential surface temperature of the second roller 34 is preferably in the range of 20 ° C. to 50 ° C., more preferably in the range of 25 ° C. to 45 ° C., and in the range of 30 ° C. to 40 ° C. It is further preferable to do.

  With respect to the dope 12 from the casting die 36 to the belt 30, so-called beads, a pressure reducing chamber is provided on the upstream side in the traveling direction of the belt 30 (not shown). The decompression chamber sucks the atmosphere in the area upstream of the bead (the area to the right of the bead in FIG. 1) to decompress this area. As a result, the bead is pulled to the upstream side, and even if the casting film 14 moves to the downstream side, the casting position PC does not change and becomes constant (the casting position PC becomes stable).

  The casting film 14 on the belt 30 passes through an air intake drying unit 40 and an air blowing drying unit 42 described later, and is hardened (gelled) to a degree that enables transport to the tenter 22, and then contains a solvent. The film is peeled off from the belt 30. Peeling is preferably performed after the solvent content rate reaches 70% or less, more preferably in the range of 10% to 70%, and still more preferably in the range of 20% to 50%. preferable.

  At the time of peeling, the film 16 is supported by the peeling roller 44, and the peeling position PP where the casting film 14 is peeled from the belt 30 is held constant. The stripping roller 44 may be a driving roller that is provided with driving means and rotates in the circumferential direction. The peeling is performed by the belt 30 on the first roller 32. When the belt 30 circulates and returns from the peeling position PP to the casting position PC, the new dope 12 is cast again at the casting position PC.

  Between the casting position PC and the peeling position PP, a suction drying unit 40 and a blowing drying unit 42 are provided. The suction drying unit 40 is disposed above the belt 30 from the casting position PC toward the second roller 34, and promotes the drying of the casting film 14 by sucking the solvent gas containing the solvent volatilized from the casting film 14 . The intake drying unit 40 is preferably provided above the area where the solvent content of the casting film 14 is 200% or more, and in the present embodiment, the intake drying unit 40 flows until the solvent content reaches 300%. The film 14 is dried. That is, in the present embodiment, the intake drying unit 40 is disposed above the area where the solvent content rate is 300% or more. The details of the intake air drying unit 40 will be described later using another drawing.

  The blower drying unit 42 is provided on the downstream side of the intake drying unit 40, and is arranged along the traveling direction of the belt 30 in the order of the first blower 46, the exhaust unit 48, and the second blower 50 from the upstream side There is. The first blower 46 is disposed near the traveling path of the belt 30 from the first roller 32 to the second roller 34, and the exhaust 48 and the second blower 50 move from the second roller 34 to the first roller 32. It is disposed in the vicinity of the traveling path of the traveling belt 30.

  The first blowing unit 46 and the second blowing unit 50 flow out the dried gas, and the exhaust unit 48 sucks and discharges the gas. The blower drying unit 42 includes a controller 52. The controller 52 sends a dried gas (hereinafter, referred to as a dry gas), for example, air, to the first blower 46 and the second blower 50, and the temperature of the gas, The humidity, the flow rate from the first air blower 46 and the second air blower 50, and the suction power of the gas at the exhaust air 48 are adjusted independently. In the present embodiment, the dry gas from the first air blower 46 and the second air blower 50 is heated to approximately 100 ° C. by the controller 52. The cast film 14 is heated by heating the cast gas as warm air on the cast film 14 to promote drying. The temperature of the drying gas is preferably in the range of 50 ° C. or more and 140 ° C. or less.

  The first air blowing unit 46 is disposed such that the outlet 46 a for discharging the dry gas is directed in the traveling direction of the belt 30, thereby supplying the dry gas to the cast film 14 being conveyed by using a back wind. . The dry gas flows parallel to the surface of the casting film 14. The second air blowing unit 50 is disposed such that the outlet 50 a for discharging the dry gas is directed to the side opposite to the traveling direction of the belt 30, whereby the dry gas is delivered to the cast film 14 being conveyed. Supply by headwind. The dry gas also flows parallel to the film surface of the casting film 14. The exhaust unit 48 is disposed to face the casting membrane 14 through which the suction port 48 a for sucking the gas passes, and sucks the gas between the first blowing unit 46 and the second blowing unit 50. The outlet 46a, the outlet 50a, and the inlet 48a are slit-like openings extending in the width direction of the belt 30 (in the depth direction in FIG. 1).

  In the present embodiment, the first air blower 46, the exhaust air 48 and the second air blower 50 are independently controlled by the controller 52, but the present invention is not limited to this aspect. For example, a controller (not shown) is provided for each of the first blower 46, the exhaust 48, and the second blower 50, and each controller controls the first blower 46, the exhaust 48, and the second blower 50. May be

  As described above, the casting film 14 dried by the intake air drying unit 40 and the air blowing drying unit 42 is peeled off from the belt 30 by the peeling roller 44 and is guided to the film 16 as a film 16. A blower (not shown) may be disposed in the conveyance path between the casting apparatus 20 and the tenter 22. Drying of the film 16 is promoted by air blowing from the air blower.

  The tenter 22 is a first film drying device which advances drying while conveying the film 16. The tenter 22 of the present embodiment stretches the film 16 in the width direction by applying tension in the width direction while holding each side portion of the film 16 with the clip 22a as a holding member and conveying the film in the longitudinal direction. The stretching process is also performed. In the tenter 22, a preheating area, an extension area, and a relaxation area are formed in order from the upstream side. The relief area may not be present.

  The tenter 22 comprises a pair of rails (not shown) and a chain (not shown). The rails are disposed on both sides of the transport path of the film 16, and the pair of rails are spaced apart at a predetermined distance. The rail spacing is constant in the preheating area, gradually wides toward the downstream in the extension area, and constant in the relaxation area. In addition, the rail interval of the relaxation area may be gradually narrowed toward the downstream.

  The chain is looped around a driving sprocket and a driven sprocket (not shown), and is mounted movably along the rail. The plurality of clips 22a are attached to the chain at predetermined intervals. The rotation of the driving sprocket causes the clip 22a to circulate along the rail. The clip 22a starts holding the guided film 16 near the inlet of the tenter 22, moves toward the outlet, and releases the holding near the outlet. The clip 22a which has been released from the holding position moves again to the vicinity of the entrance to hold the film 16 which has been newly guided.

  Moreover, the tenter 22 is provided with the air blower 22b. The blower 22 b is provided above the transport path of the film 16. The blower 22b has a slit for delivering a dry gas (for example, dry air), and the dry gas is supplied from a blower (not shown). The blower sends drying air adjusted to a predetermined temperature and humidity to the blower 22b. The blower 22 b is disposed such that the slit faces the transport path of the film 16. The slits extend in the width direction of the film 16 and are formed at predetermined intervals in the transport direction. A blower having a similar structure may be provided below the transport path of the film 16, or may be provided both above and below the transport path of the film 16.

  The roller drying device 24 is a second drying device for further drying the film 16. Temperature, humidity, etc. are adjusted by an air conditioner (not shown) in the atmosphere inside the roller drying device 24. In the roller drying device 24, the film 16 is wound around and transported by a number of rollers 24a.

  The slitter 26 is for cutting off both sides of the film 16 to have a target width. In this cutting, both sides of the film 16 are cut so as to include a retention mark by the clip 22a. The winding device 28 winds the film 16 around a winding core to form a roll.

  Hereinafter, the intake air drying unit 40 will be described in more detail with reference to FIGS. 2 and 3. As shown in FIG. 2, the intake-air drying unit 40 is disposed between the labyrinth seals 60 and 62 and a pair of labyrinth seals 60 and 62 disposed on the upstream side and the downstream side of the casting film 14 in the longitudinal direction (transport direction). And a drying case 64 covering the casting film 14 from above, which are disposed downstream of the casting position PC.

  The labyrinth seals 60 and 62 are provided with a plurality of seal plates 66 which are long in the width direction of the casting film 14 and arranged in a standing posture perpendicular to the belt 30, and the plurality of sealing plates 66 Are arranged along the longitudinal direction (conveyance direction). The labyrinth seals 60 and 62 prevent the outside air from flowing into the drying case 64 from the upstream side and the downstream side in the longitudinal direction (conveying direction) of the casting film 14.

  As shown in FIG. 3, the drying case 64 is a top plate provided to connect the pair of wind shielding plates 68 and 70 facing each other in the width direction of the casting film 14 and the upper end portions of the wind shielding plates 68 and 70. (Lid member) 72 is comprised. The wind shields 68 and 70 are formed long along the side edge of the casting film 14 in the longitudinal direction (conveying direction) of the casting film 14, and are arranged in a standing posture perpendicular to the belt 30. The air shielding plates 68 and 70 divide the space above the belt 30 into an inner region 74 where the casting film 14 is cast and an outer region 76 (see FIG. 3) outside the casting film 14. . Further, the top end of the inner region 74 is closed by the top plate 72. Thus, the space above the casting membrane 14 (inner region 74) is covered by the drying case 64.

  Further, the intake air drying unit 40 is provided with a solvent gas suction mechanism 80 (see FIG. 2). The solvent gas suction mechanism 80 includes an infrared heater (infrared irradiator) 82, an intake duct 84, an intake fan 86, an intake controller 88, and a condenser 90. The infrared heater 82 is arranged, for example, in a matrix on the inner portion of the top plate 72 of the drying case 64, and is irradiated with infrared rays toward the casting film 14 to heat the casting film 14, thereby the casting film 14 We recommend the drying of

  The air intake duct 84 is formed to penetrate the top plate 72, the air intake port 84 a provided at one end is disposed in the inner region 74, and the other end is connected to the capacitor 90. In the present embodiment, the intake port 84 a is formed in a slit shape long in the width direction of the casting film 14, and is disposed at the central portion of the top plate 72 of the drying case 64 in the longitudinal direction (conveying direction) of the casting film 14. ing. In addition, since the arrangement position and shape of the air inlet 84a can be freely set, for example, a slit-like opening long in the transport direction of the casting film 14 is provided at the center of the top plate 72 in the width direction of the casting film 14 You may provide.

  The intake fan 86 is disposed inside the intake duct 84 and rotates under the control of the intake controller 88. By this rotation, the atmosphere of the inner region 74 (that is, the solvent gas containing the solvent volatilized from the casting film 14) is sucked from the air inlet 84 a and is sent to the condenser 90 through the air intake duct 84. The intake controller 88 controls the suction force (the amount of suction per unit time) of the solvent gas by controlling the driving force (electric power or the like) supplied to the suction fan 86. The condenser 90 liquefies the solvent in the solvent gas, for example, by cooling the solvent gas. The liquefied solvent is recovered and reused as the dope 12, or is sent to a solvent gas generator 102 described later and used for generation of a solvent gas.

  Thus, by sucking the solvent gas from the inner region 74, the drying of the casting film 14 can be promoted efficiently. On the other hand, outside air (fresh air) having a lower solvent content (e.g., approximately 0% solvent content) in the inner region 74 reduced in pressure by suction only by suctioning the solvent gas (e.g., solvent content approximately 0%) Flow from In the case of the present embodiment, fresh air flows into the inner region 74 from the gap between the wind shields 68 and 70 and the belt 30, that is, from both sides of the casting film 14 only by suctioning the solvent gas.

  Then, the concentration of solvent gas in the inner region 74 varies due to the influence of the fresh air flowing into the inner region 74 in this manner, and the progress of drying at each position of the casting film 14 becomes different. There is a problem that uneven thickness occurs in the spread film 14 and the film 16. In the case of the present embodiment, only by suctioning the solvent gas, the casting film is different because the concentration of the solvent gas is different between the both sides of the casting film 14 where the fresh air flows in and the central part where the fresh air does not flow. Uneven thickness occurs on the film 14 (film 16).

  In order to prevent such uneven thickness due to the influence of fresh air, the intake air drying unit 40 is provided with a solvent gas supply mechanism 100. The solvent gas supply mechanism 100 includes a solvent gas generation device 102, a solvent gas supply duct 104, an air supply fan 106, and a supply gas controller (supply gas concentration control mechanism) 108.

  The solvent gas generator 102 generates a solvent gas containing a solvent, for example, by spraying or heating the solvent for volatilization. The solvent used in the solvent gas generator 102 may have the same composition as the solvent of the dope 12 or may have a composition different from that of the solvent of the dope 12. In addition, the solvent recovered by the condenser 90 described above may be used in the solvent gas generator 102.

  One end of the solvent gas supply duct 104 is connected to the solvent gas generator 102, and the other end is connected to the pair of supply boxes 110 and 112. The supply boxes 110 and 112 are formed long in the longitudinal direction (conveying direction) of the casting film 14 and disposed outside the wind shields 68 and 70. A slit-shaped supply port 110 a which is long in the longitudinal direction (conveying direction) of the casting film 14 is formed on the lower surface of the supply box 110 on the side of the wind shield plate 68. Similarly, a slit-like supply port 112 a which is long in the longitudinal direction (conveying direction) of the casting film 14 is formed on the lower surface of the supply box 112 on the side of the wind shield plate 70. An air supply fan 106 is provided inside the solvent gas supply duct 104, and the solvent gas generated by the solvent gas generator 102 is sent to the supply boxes 110 and 112 by the air supply fan 106, and the supply port 110a. , 112a vertically toward the lower belt 30.

  The supply ports 110a and 112a may be porous openings made of a collection of a plurality of fine holes. Although the solvent gas is supplied vertically downward from the supply ports 110a and 112a, the solvent gas is supplied from the supply ports 110a and 112a toward the inner side (inner region 74) and the outer side (outer region 76). It may be configured to

  By thus supplying the solvent gas, the supplied solvent gas functions as an air curtain covering the gap between the wind shields 68 and 70 and the belt 30, and fresh air flows into the inner region 74. It can prevent. Also, even if the solvent gas in the inner region 74 is sucked by the solvent gas suction mechanism 80 and the pressure in the inner region 74 is reduced, it flows into the inner region 74 from the gap between the wind shields 68, 70 and the belt 30. The solvent gas supplied from the supply ports 110a and 112a is not fresh air. Thereby, the thickness unevenness mentioned above can be prevented.

  The supply gas controller 108 is provided to control the amount and concentration of the solvent gas supplied from the supply ports 110 a and 112 a and to prevent uneven thickness more reliably. The supply gas controller 108 is connected to the air supply fan 106 described above, and the supply gas controller 108 controls the driving power (such as electric power) supplied to the air supply fan 106 to supply the solvent gas supply amount Control the supply amount per unit time). In addition, it is preferable that the supply amount of solvent gas is more than the suction amount of the solvent gas which the solvent gas suction mechanism 80 sucks.

  Further, in addition to the solvent gas generator 102 described above, a sensor 114 is connected to the supply gas controller 108. A sensor 114 is disposed in the inner region 74 to detect the concentration of solvent in the inner region 74, ie, the concentration of solvent gas drawn by the solvent gas suction mechanism 80. In the present embodiment, the sensor 114 is disposed about 2 cm away from the belt 30 (about 2 cm above the belt 30) at the upstream end of the drying case 64 and at the center in the width direction of the casting film 14. In addition, although the arrangement position of the sensor 114 is not limited to this, although it can set freely if it is in the inside area | region 74, arrange | positioning as upstream as possible is preferable. In addition, it is preferable to arrange at the center in the width direction of the casting film 14.

  The supply gas controller 108 controls the solvent gas generator 102 based on the concentration of the solvent gas detected by the sensor 114 and the amount of the solvent gas supplied by the air supply fan 106 (the amount of sprayed solvent and the heating temperature). (The amount of volatilization) is controlled, and the concentration of the solvent gas supplied from the supply ports 110a and 112a is controlled.

  The thinner the concentration of the solvent gas supplied from the supply ports 110a and 112a, the lower the effect of preventing thickness unevenness. Therefore, the concentration of the solvent gas (hereinafter sometimes referred to as a suction gas) suctioned by the solvent gas suction mechanism 80 is “A”, and the solvent gas supplied from the supply ports 110a and 112a (hereinafter referred to as a supply gas) It is preferable to satisfy “A / 5 ≦ B” when the concentration of “A” is “B”, that is, the concentration B of the supplied gas is 1⁄5 or more of the concentration A of the suction gas.

  In addition, as the concentration of the solvent gas supplied from the supply ports 110a and 112a becomes higher, the drying of the casting film 14 becomes less likely to occur. Therefore, it is preferable to satisfy “B ≦ A”, that is, to set the concentration B of the supplied gas to the concentration A or less of the suction gas.

  As described above, in the solution film forming apparatus 10, the step of forming the casting film 14 by casting the dope 12 from the casting die 36 onto the belt 30 (casting film forming step), A step (transfer step) of conveying to the peeling position PP while being dried via the suction drying unit 40, the air flow drying unit 42 (transfer step), a step of peeling the casting film 14 from the belt 30 at the peeling position PP (peeling The film 16 is manufactured through the above steps.

  Then, in the transfer step, the solvent gas is sucked from the inner region 74 covered by the drying case 64 to dry the casting film 14, and the gap between the drying case 64 (the wind shields 68 and 70) and the belt 30. The supply of the solvent gas prevents fresh air from flowing into the inner region 74, thereby preventing the occurrence of uneven thickness.

  In the above embodiment, the solvent gas suction mechanism 80 and the solvent gas supply mechanism 100 are provided independently, and suction and supply of the solvent gas are performed independently. At least a part of the gas 80 and the solvent gas supply mechanism 100 may be connected, and suction and supply of the solvent gas may be performed in conjunction with each other.

  Specifically, the intake duct 84 (see FIG. 2) and the solvent gas supply duct 104 (see FIG. 3) are connected, and at least one of the branched ducts obtained by branching the intake duct 84 is a solvent gas supply duct Alternatively, the solvent gas drawn by the air intake duct 84 may be supplied from the solvent gas supply duct 104. In this case, it is preferable to provide concentration adjusting means for adjusting the concentration of the solvent gas drawn by the intake duct 84. When the concentration adjusting means reduces the concentration of the solvent gas, for example, the solvent gas is cooled to liquefy a part of the solvent, or a gas having a lower solvent concentration than the solvent gas sucked by the intake duct 84 (for example, fresh Wind) is combined with the solvent gas drawn by the air intake duct 84. Further, when the concentration of the solvent gas is increased, the concentration adjusting means generates solvent gas having a concentration higher than that of the solvent gas sucked by the air intake duct 84 by spraying or heating the solvent, for example. Combine with the solvent gas

  Thus, by connecting at least a part of the solvent gas suction mechanism 80 and the solvent gas supply mechanism 100, for example, the intake fan 86 (see FIG. 2) and the air feed fan 106 (see FIG. 3) are integrated (see FIG. Since one can be eliminated or the capacitor 90 and the solvent gas generator 102 can be integrated as the above-mentioned concentration adjusting means, the solution casting apparatus can be miniaturized and the cost can be reduced.

  Moreover, in the said embodiment, although the cellulose triacetate (TAC) was used as a polymer of the dope 12, it may replace with TAC and may use another cellulose acylate. The cellulose acylate may have only one type of acyl group, or may have two or more types of acyl groups. When two or more types of acyl groups are used, one of them is preferably an acetyl group. It is preferable that the proportion of the hydroxyl group of cellulose esterified with a carboxylic acid, that is, the one in which the degree of substitution of the acyl group satisfies all of the following formulas (I) to (III). In the following formulas (I) to (III), A and B represent the degree of substitution of acyl group, A is the degree of substitution of acetyl group, and B is the degree of substitution of acyl group having 3 to 22 carbon atoms It is.

(I) 2.0 ≦ A + B ≦ 3.0
(II) 1.0 ≦ A ≦ 3.0
(III) 0 ≦ B ≦ 2.0

  The total substitution degree A + B of the acyl group is more preferably 2.20 or more and 2.90 or less, and particularly preferably 2.40 or more and 2.88 or less. The substitution degree B of the acyl group having 3 to 22 carbon atoms is more preferably 0.30 or more, and particularly preferably 0.5 or more.

  Also, the polymer of the dope 12 is not limited to cellulose acylate. For example, acrylic resin, cyclic olefin resin (for example, Arton (registered trademark) manufactured by JSR Corporation) may be used.

  Hereinafter, examples of the present invention and comparative examples for comparison with the examples will be described.

In all the examples and comparative examples, the solid content to be the film 16 is dissolved in a mixture of 92 parts by mass of dichloromethane as the first component of the solvent and 8 parts by mass of methanol as the second component of the solvent, Made a 19.0 wt% dope 12. The solid content is the following TAC, a first plasticizer and a second plasticizer. The first plasticizer is triphenyl phosphate and the second plasticizer is biphenyl diphenyl phosphate. The formed dope 12 was subjected to stationary degassing, and then the foreign matter was removed through a filter by a liquid feed pump, and the dope 12 after foreign matter removal was subjected to casting.
TAC 100 parts by mass First plasticizer 7 parts by mass Second plasticizer 5 parts by mass

  Using this dope 12, a film 16 having a thickness of 40 μm was produced. The film forming apparatus 10 (see FIG. 1) was used to manufacture the film 16, and the traveling speed of the belt 30 was 50 m / min.

  Then, in the example, the film 16 was manufactured by operating the solvent gas supply mechanism 100 (see FIG. 3). That is, in the embodiment, even if the inside of the drying case 64 is depressurized by suction by the solvent gas suction mechanism 80 (see FIG. 2), fresh air flows in the drying case 64 from the gap between the wind shields 68 and 70 and the belt 30. The film 16 was manufactured so as not to flow.

  On the other hand, in the comparative example, the film 16 was manufactured by stopping the solvent gas supply mechanism 100. That is, in the comparative example, when the inside of the drying case 64 is depressurized by suction by the solvent gas suction mechanism 80, fresh air flows into the drying case 64 from the gap between the wind shields 68 and 70 and the belt 30. The film 16 was manufactured.

  In each example and each comparative example, the suction gas concentration A (the solvent concentration in the suction gas, the concentration measured by the sensor 114), the supply gas concentration B (the solvent concentration in the supply gas), the wind speed on the film (film The film 16 is manufactured while changing the upper air velocity of the upper gas, which changes based on the suction amount of the suction gas. The suction gas concentration A, the supply gas concentration B, the gas concentration ratio (A / B), and the air velocity on the film of each Example and each Comparative Example are as shown in Tables 1 and 2.

  The uneven thickness of the film 16 of each example and each comparative example manufactured under each condition shown in Table 1 and Table 2 was evaluated. The evaluation results are also shown in Tables 1 and 2. Evaluation was made into three steps of "A", "B", and "C". Evaluation A is the highest evaluation, and evaluation C is the lowest evaluation. The evaluation is based on the conventional constitution, that is, evaluation C based on Comparative Example 1-4 in which the solvent gas supply mechanism 100 is stopped to manufacture the film 16, and evaluation B is obtained when thickness unevenness is improved compared to the conventional one. When the smooth film 16 having almost no thickness unevenness was obtained, the evaluation was A.

  Specifically, it was evaluated by irradiating light from the back side of the film and visually observing the difference in density of the transmitted light. In addition, the density difference is confirmed (observed) as a minute thing, and as above-mentioned, it was set as the evaluation C on the basis of the density difference recognized by Comparative Example 1-4. Moreover, it was set as evaluation B, when the light / dark difference is small compared with Comparative Example 1-4. Furthermore, in the case where no difference in density was visually observed, it was evaluated as A without unevenness in thickness.

  As shown in Tables 1 and 2, it has been confirmed that in each of the examples in which the solvent gas supply mechanism 100 is operated, thickness unevenness can be prevented as compared with the comparative example in which the solvent gas supply mechanism 100 is not operated. In addition, comparison with Examples 1a to 1d, 2a to 2e, 3a to 3e, 4a, 4b and the other embodiments shows that “A / 5 ≦ B” is satisfied, that is, the concentration B of the supplied gas is It was confirmed that the thickness unevenness can be further prevented by setting the density A of the suction gas to 1⁄5 or more.

  In addition, the thickness of the film 16 to manufacture was changed from 40 micrometers to 25 micrometers mentioned above, and the same verification was performed. Also in this case, the results were the same as in the case of 40 μm described above (see Tables 1 and 2). Thus, it was confirmed that the present invention is effective even when the thickness of the film 16 is 25 μm.

Reference Signs List 10 solution film forming apparatus 12 dope 14 casting film 16 film 20 casting apparatus 30 belt (support)
36 casting die 40 intake air drying unit 42 air blowing drying unit 60, 62 labyrinth seal 64 drying case 66 sealing plate 68, 70 air shielding plate 72 top plate (lid member)
74 inner area 76 outer area 80 solvent gas suction mechanism 82 infrared heater (infrared irradiator)
84 intake duct 84a intake 86 intake fan 88 intake controller 90 condenser 100 solvent gas supply mechanism 102 solvent gas generator 104 solvent gas supply duct 106 air supply fan 108 supply gas controller (supply gas concentration control mechanism)
110, 112 supply box 110a, 112a supply port 114 sensor

Claims (12)

In a solution casting apparatus in which a polymer solution in which a polymer is dissolved in a solvent is cast on a running support to form a cast film,
A pair of wind shields provided along the side edges of the cast film and dividing the space above the support into an inner area of the cast film to be cast and an outer area of the cast film outside. Board,
A solvent gas suction mechanism which sucks in a solvent gas including a solvent volatilized from the casting film by suction from a suction port disposed in the inner region;
A solvent gas supply mechanism for supplying a solvent gas containing a solvent for dissolving the polymer into a gap between the support and the windproof plate;
Solution film forming apparatus equipped with When the mass of the solvent in the casting membrane is MS and the mass of the casting membrane is MF,
{MS / (MF-MS)} x 100
The solution film-forming apparatus of Claim 1 which performs attraction | suction by the said solvent gas suction mechanism, and the supply by the said solvent gas supply mechanism in the area whose solvent content shown by these is 200% or more. Providing a lid member for connecting the upper end of one of the wind shield plates to the upper end of the other wind shield plate;
The solution casting apparatus according to claim 1 or 2, wherein the inner region is covered from above by the lid member.   The said inner side area | region is provided with the infrared rays irradiation machine which accelerates | stimulates the volatilization of the solvent contained in the said casting film by irradiating an infrared rays with respect to the said casting film, The any one of Claims 1-3. Solution film forming equipment.   The solution forming apparatus according to any one of claims 1 to 4, wherein the solvent gas supply mechanism performs the supply from a supply port provided on a side of a lower end portion of the windproof plate.   The solution film forming apparatus according to claim 5, wherein the solvent gas supply mechanism vertically supplies a solvent gas containing a solvent for dissolving the polymer, from the supply port toward the lower support. The concentration of the suction gas which is the solvent gas suctioned by the solvent gas suction mechanism is A,
When the concentration of the supplied gas which is the solvent gas supplied by the solvent gas supply mechanism is B,
A / 5 ≦ B
The solution film-forming apparatus of any one of Claims 1-6 satisfy | filled. The concentration of the suction gas which is the solvent gas suctioned by the solvent gas suction mechanism is A,
When the concentration of the supplied gas which is the solvent gas supplied by the solvent gas supply mechanism is B,
B ≦ A
The solution film-forming apparatus of any one of Claims 1-7 which satisfy | fills. A sensor for measuring the concentration of the solvent gas sucked by the solvent gas suction mechanism;
A supply gas concentration control mechanism for controlling the concentration of the solvent gas supplied from the solvent gas supply mechanism based on the measurement result of the sensor;
The solution film-forming apparatus of any one of Claims 1-8 provided with these.   The solution film-forming apparatus of any one of Claims 1-9 which supplies the solvent gas containing the solvent gas which the said solvent gas suction mechanism attracted | sucked from the said solvent gas supply mechanism.   The solution film-forming apparatus according to any one of claims 1 to 10, wherein the thickness of the film produced by peeling the cast film from the support is 40 μm or less. A cast film forming step of casting a polymer solution in which a polymer is dissolved in a solvent onto a traveling support to form a cast film, and transferring the cast film to a peeling position for peeling the cast film from the support A solution casting method comprising a transfer step, and a peeling step of peeling the cast film from the support at the peeling position,
In the transfer step,
A space above the support is defined by a pair of wind shields provided along the side edge of the casting membrane, the inner area of the casting membrane to be cast and the outer area of the casting membrane outside And partitions,
Intake is performed from an air inlet disposed in the inner region, and a solvent gas containing a solvent volatilized from the cast film is sucked.
The solution film forming method which supplies the solvent gas containing the solvent which dissolves the said polymer from the clearance gap between the said support body and the said windproof plate.

Images