JP2009154518A - Apparatus for manufacturing thermoplastic resin film and method for manufacturing thermoplastic resin film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thermoplastic resin film suitable for optical use, by restraining nonuniformity of the thickness, when manufacturing the thermoplastic resin film by a melting film forming method. <P>SOLUTION: This apparatus has a die 16 which discharges a molten thermoplastic resin in a film shape, a cooling roll 18 which is arranged so as to oppose to a discharge port of the die 16 and cools and solidifies the discharged film 12A, and a shielding means which shields at least an end part in the width direction of the film 12A up to landing on a surface of the cooling roll 18 from the discharge port of the die 16 between an end part in the width direction of the cooling roll 18 and the end part in the width direction of the film 12A. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a thermoplastic resin film manufacturing apparatus and a thermoplastic resin film manufacturing method, and more particularly to a film manufacturing technique in which the manufactured thermoplastic resin film is used for optical applications such as a liquid crystal display device.

  Thermoplastic resins such as cellulose resins and cyclic olefin resins are widely used as films for optical applications. In particular, a cellulose resin or a cyclic olefin resin film is used as an optical film for liquid crystal display devices because of its transparency, toughness, and optical isotropy.

  As a method for producing a thermoplastic resin film, there is a method in which a molten thermoplastic resin is discharged from a die into a film shape, and the discharged film is cooled and solidified by a plurality of cooling rolls (for example, a melt film forming method). The unstretched thermoplastic resin film produced in this way is used for a protective film of a liquid crystal display device, for example. A film obtained by stretching an unstretched thermoplastic resin film to develop retardation is used as a retardation film of a liquid crystal display device.

  By the way, in the melt film forming method, there is a problem that the film discharged from the die is easily affected by the disturbance until the landing from the die to the cooling roll (air gap), resulting in uneven thickness. .

As a countermeasure, for example, Patent Document 1 proposes that the entire periphery of the die and the cooling roll is surrounded by a shielding member so that the film is not affected by the external air flow in the air gap portion. .
JP 2006-150806 A

  However, Patent Document 1 shows a certain effect in reducing the thickness unevenness, but does not analyze the air flow that causes the thickness unevenness, and cannot effectively and effectively suppress the disturbance. .

  The present invention has been made in view of such circumstances, and suppresses uneven thickness when a thermoplastic resin film is produced by a melt film-forming method, so that a thermoplastic resin film suitable for optical applications can be obtained. It aims at providing the manufacturing method of a plastic resin film.

  In order to achieve the above object, claim 1 of the present invention includes a die that discharges a molten thermoplastic resin into a film, a cooling roll that is disposed opposite to the discharge port of the die and that cools and solidifies the discharged film. And shielding between at least the widthwise end of the film from the discharge port of the die to the surface of the cooling roll between the widthwise end of the cooling roll and the widthwise end of the film. And a thermoplastic resin film manufacturing apparatus.

  The inventors of the present invention have a large temperature difference with the cooling roll because the die is hot. For example, the width between the cooling roll 2 and the touch roll 3 will be described with reference to FIG. 23 of the conventional touch roll method. It was found that ascending airflow (arrows) rising from both sides of the direction toward the die 4 was generated on both surfaces of the film 6. This updraft causes wind speed fluctuation in the vicinity of the film surface between the die and the surface of the cooling roll, and causes temperature distribution on the film surface. Moreover, when temperature distribution arises on the film surface, when it solidifies by cooling on a cooling roll, it also becomes a cause which causes thickness nonuniformity.

  According to claim 1, the shielding that shields at least the widthwise end of the film from the die outlet to the surface of the cooling roll between the widthwise end of the cooling roll and the widthwise end of the film. Means are provided. Thereby, it can suppress that an updraft hits the film surface vicinity until it is discharged from die | dye and it lands on the surface of a cooling roll. Therefore, it is possible to reduce the wind speed fluctuation in the vicinity of the film surface that causes uneven thickness.

  A second aspect of the present invention is the first aspect of the present invention, wherein the shielding means is a shielding plate provided in a direction substantially orthogonal to the film surface between the width direction end of the cooling roll and the width direction end of the film. It is characterized by being.

  According to claim 2, the shielding plate which shields the width direction end of the discharged film is provided between the width direction end of the cooling roll and the width direction end of the film. Thereby, it can suppress that an updraft hits the surface vicinity of the film discharged from die | dye.

  A third aspect of the present invention is characterized in that, in the second aspect, the distance between the shielding plate and the width direction end of the film is 50 mm or less.

  According to claim 3, since the interval between the shielding member and the side surface in the width direction of the film is narrowed, the shielding property can be improved, and at the same time, the rising airflow from the cooling roll surface to the die is hardly generated in the vicinity of the film surface. Can do.

  A fourth aspect of the present invention is characterized in that, in the second or third aspect, the shielding means is provided so as to surround a periphery including the surface of the film. Thereby, it can suppress reliably that an updraft hits the surface side of a film, and it can prevent that thickness nonuniformity arises.

  According to a fifth aspect of the present invention, in the first aspect, the shielding unit includes a casing that surrounds a longitudinal direction of the die and the surface of the cooling roll and in which a labyrinth mechanism is formed. Air flow forming means for forming an air flow in a direction substantially orthogonal to the film surface is provided at both ends in the width direction.

  According to the fifth aspect of the present invention, the casing is provided with a case in which a labyrinth mechanism is formed inside the longitudinal direction of the die and the surface of the cooling roll. Can be suppressed. Moreover, since an air flow is formed in the direction substantially orthogonal to the film surface, it is possible to eliminate the rising air flowing from both ends in the width direction. At this time, the air flow passes through the labyrinth mechanism inside the housing, but is buffered by this, so there is no possibility of disturbing the air flow near the surface of the film. In the present invention, the type of air flow is not limited to air, and may be, for example, an inert gas such as nitrogen gas.

  A sixth aspect of the present invention according to the fifth aspect is characterized in that the air flow forming means is a blower nozzle or a suction nozzle.

  Thus, since an air flow is formed in the direction substantially orthogonal to the film surface by the suction nozzle or the air blowing nozzle, the rising air flowing from the width direction end of the film can be shielded.

  According to a seventh aspect of the present invention, in order to achieve the above object, a die for discharging a molten thermoplastic resin into a film shape, a cooling roll disposed opposite to the discharge port of the die and cooling and solidifying the discharged film, And a rectifying means provided near the discharge port of the die and rectifying the vicinity of the surface of the film between the discharge port and landing on the surface of the cooling roll. A film manufacturing apparatus is provided.

  According to the seventh aspect, the rectifying means for rectifying the vicinity of the discharged film surface is provided in the vicinity of the discharge port of the die. Thereby, even if an updraft reaches near the surface of the film, fluctuations in wind speed can be reduced by rectifying the airflow near the film surface. As such a rectifying means, for example, a blowing nozzle for blowing air in parallel with the film discharge direction, a reduced pressure suction nozzle for sucking under reduced pressure, or the like can be used.

  An eighth aspect of the present invention is characterized in that, in the seventh aspect, the rectifying means is a blower nozzle or a suction nozzle that is provided near the discharge port of the die and blows air in parallel with the discharge direction of the film.

  Claim 9 is any one of claims 1 to 8, a measuring means for measuring the temperature in the vicinity of the film surface, and a heating means for setting the vicinity of the film surface to a predetermined temperature based on the measurement result, It is provided with.

  According to the ninth aspect, since the ambient temperature around the die is increased, the temperature difference between the die and the ambient temperature can be reduced. Thereby, it is possible to make it difficult to generate an upward air flow. Specifically, the vicinity of the film surface indicates a range in which the distance from the film surface is 20 mm or less.

  In addition, as a heating means, what is necessary is just to install in shielding member itself or it inside, for example, the method of embedding a heater in shielding member itself, etc. are mentioned.

  A tenth aspect of the present invention is characterized in that, in any one of the first to ninth aspects, an air gap from the discharge port of the die to the contact point of the film on the surface of the cooling roll is 200 mm or less.

  According to the tenth aspect, since the air gap is set to 200 mm or less, it is possible to reduce the area of the film that receives a disturbance such as an external air flow. Thereby, it can suppress that thickness nonuniformity arises.

  An eleventh aspect of the present invention is the method according to any one of the first to tenth aspects, wherein the touch roll is provided adjacent to the cooling roll, and the discharge port of the die is more than the apex of the cooling roll and the apex of the touch roll. It is provided at a low position.

  According to the eleventh aspect, the discharge port of the die is provided at a position lower than both the vertex of the cooling roll and the vertex of the touch roll. Thereby, both surfaces of the film discharged from the die are shielded by the cooling roll and the touch roll, and the rising air current can be made difficult to hit the film.

  In order to achieve the above object, a twelfth aspect of the present invention uses the thermoplastic resin film manufacturing apparatus according to any one of the first to eleventh aspects to reduce wind speed fluctuation in the vicinity of the film surface. A method for producing a thermoplastic resin film is provided.

  According to the twelfth aspect, since the thermoplastic resin film manufacturing apparatus according to any one of the first to eleventh aspects is used, the rising air current to the vicinity of the film surface is blocked, or the vicinity of the film surface is rectified, and the vicinity of the film surface. It is possible to suppress the occurrence of the wind speed distribution in the air or to reduce the wind speed distribution.

  According to a thirteenth aspect of the present invention, in order to achieve the above object, a thermoplastic resin film comprising a step of discharging a molten thermoplastic resin from a die into a film and cooling and solidifying the discharged film on a cooling roll. In the production method, a method for producing a thermoplastic resin film is provided, wherein the wind speed fluctuation in the vicinity of the surface of the discharged film is set to 0.5 m / second or less.

  The updraft described in FIG. 22 causes a wind speed fluctuation in the vicinity of the film surface between the die and the surface of the cooling roll, causing a temperature distribution on the film surface. When such a temperature distribution is generated on the film surface, it may cause unevenness in thickness when cooled and solidified on the cooling roll. According to the thirteenth aspect, by setting the wind speed fluctuation to 0.5 m / second or less, it is possible to suppress the occurrence of the temperature distribution causing the thickness unevenness.

  A fourteenth aspect is characterized in that, in the thirteenth aspect, rectification is performed in the vicinity of the surface of the film from the discharge port of the die to the surface of the cooling roll.

  A fifteenth aspect of the present invention is characterized in that, in the fourteenth aspect, the rectification is performed by blowing or sucking in parallel with a discharge direction of the film.

  A sixteenth aspect is characterized in that, in any one of the thirteenth to fifteenth aspects, the wind speed in the vicinity of the film surface is 1 m / sec or less.

  According to the sixteenth aspect, since the wind speed in the vicinity of the film surface is small, the thickness unevenness caused by this influence can be suppressed.

  A seventeenth aspect is characterized in that, in any one of the thirteenth to sixteenth aspects, a temperature difference between the vicinity of the film surface and the die is within a range of 160 ° C or less.

  According to the seventeenth aspect, since the difference between the ambient temperature in the vicinity of the film surface and the temperature of the die is in a range of 160 ° C. or less, it is possible to make it difficult to generate an upward air flow due to the temperature difference between the die and the ambient temperature. .

  An eighteenth aspect is characterized in that, in any one of the thirteenth to seventeenth aspects, the cooling roll is a touch roll type.

  In such a touch roll method, since the surface pressure is uniformly applied to the molten film discharged from the die, in-plane Re and Rth unevenness and unevenness unevenness can be reduced.

  A nineteenth aspect of the present invention is the thermoplastic resin according to any one of the thirteenth to eighteenth aspects, wherein the thermoplastic resin has a melting temperature T (° C) immediately after being discharged from the die, and is (T-10) ° C or higher and T ° C. In the following, the absolute value of the melt viscosity gradient is 1.7 Pa · s / ° C. or more.

  According to the nineteenth aspect, when the melting temperature immediately after being discharged from the die is T (° C.), the absolute value of the melt viscosity gradient at (T−10) ° C. to T ° C. is 1.7 Pa · s / ° C. The present invention is applied to the thermoplastic resin as described above. Thus, a resin having a high temperature dependence of melt viscosity is easily affected by temperature fluctuations due to fluctuations in wind speed, and the viscosity is greatly changed, so that thickness unevenness is likely to occur. In such a case, thickness unevenness can be remarkably suppressed by making it difficult to generate an upward air flow.

  A twentieth aspect according to any one of the thirteenth to nineteenth aspects is characterized in that the thermoplastic resin is a cellulose resin or a cyclic olefin resin.

  This is because, among thermoplastic resin films, in particular, a cellulose resin or a cyclic olefin resin film is suitable as a film for optical use because of its transparency, toughness, and optical isotropy.

  A twenty-first aspect is characterized in that, in any one of the thirteenth to twentieth aspects, the thickness unevenness of the film is 1 μm or less.

  This is because if a thermoplastic resin film for optical use is produced by the production method of the present invention, an optical film having a favorable surface shape with a thickness unevenness of 1 μm or less can be produced.

  ADVANTAGE OF THE INVENTION According to this invention, the thickness nonuniformity at the time of manufacturing a thermoplastic resin film by a melt film-forming method can be suppressed, and the thermoplastic resin film suitable for an optical use can be obtained.

  Hereinafter, preferred embodiments of a method for producing a thermoplastic resin film according to the present invention will be described with reference to the accompanying drawings. In the present specification, a numerical range represented by using “to” means a range including numerical values described before and after “to” as a lower limit value and an upper limit value.

  First, a first embodiment of the present invention will be described. The present embodiment is an example in which a shielding plate is installed at least at an end portion in the width direction of the film or shielded by forming an air flow, and an upward air flow is prevented from hitting the vicinity of the film surface.

  FIG. 1 is a block diagram showing an example of a production apparatus for carrying out the method for producing a thermoplastic resin film of the present invention. In this embodiment, an example of producing a cellulose acylate film is shown, but the present invention is not limited to this, and can be applied to other cyclic olefin-based thermoplastic resin films.

As shown in FIG. 1, the manufacturing apparatus 10 is mainly discharged from an extruder 14 that melts the cellulose acylate resin 12, a die 16 that discharges the melted cellulose acylate resin 12 into a film, and a die 16. A plurality of cooling rolls 18, 20, and 22 that cool the cellulose acylate film 12 </ b> A (hereinafter referred to as a film 12 </ b> A) in a high-temperature melt state, a peeling roll 24 that peels the film 12 </ b> A from the last cooling roll 22, and the cooled A winder 26 that winds up the film 12A and the like are configured.

  FIG. 2 is a cross-sectional view showing the configuration of the extruder 14. As shown in the figure, in the cylinder 32 of the extruder 14, a single screw 38 having a flight 36 attached to a screw shaft 34 is provided. The single screw 38 is rotated by a motor (not shown). A hopper (not shown) is attached to the supply port 40 of the cylinder 32. Then, the cellulose acylate resin 12 is supplied from the hopper into the cylinder 32 through the supply port 40.

  Inside the cylinder 32, in order from the supply port 40 side, a supply unit (region indicated by A) for quantitatively transporting the cellulose acylate resin supplied from the supply port 40, and a compression unit (B) for kneading and compressing the cellulose acylate resin And an area for measuring the kneaded and compressed cellulose acylate resin (area indicated by C). The cellulose acylate resin melted by the extruder 14 is continuously sent from the discharge port 42 to the die 16.

  The screw compression ratio of the extruder 14 is preferably set to 1.5 to 4.5, and the ratio L / D of the cylinder length to the cylinder inner diameter is preferably set to 20 to 70. Here, the screw compression ratio is represented by the volume ratio of the supply unit A and the metering unit C, that is, the volume per unit length of the supply unit A ÷ the volume per unit length of the metering unit C. Is calculated using the outer diameter d1 of the screw shaft 34, the outer diameter d2 of the screw shaft 34 of the measuring section C, the groove diameter a1 of the supply section A, and the groove diameter a2 of the measuring section C. The extrusion temperature is preferably 190 to 300 ° C. Furthermore, in order to prevent the molten resin from being oxidized by residual oxygen, it is also preferable to carry out the inside of the extruder in an inert (nitrogen or the like) air flow or while evacuating using a vented extruder.

Then, the cellulose acylate resin 12 melted by the extruder 14 is sent to the die 16 via the pipe 44 (see FIG. 1), and discharged from the die discharge port into a film shape. Die 16
The fluctuation of the discharge pressure discharged from the nozzle is preferably within a range of 10%.

  As shown in FIG. 1, three cooling rolls 18, 20, and 22 are arranged in multiple stages on the downstream side of the die 16. The cooling roll 18 is configured to be cooled and solidified by being sandwiched between adjacent touch rolls 28.

  FIG. 3 is a perspective view showing a configuration between the die 16 and the cooling roll 18. 4 is a side view seen from the X direction in FIG. 3, and FIG. 5 is a cross-sectional view taken along the Y direction from the thickness direction center line of the die 16 in FIG.

  As shown in FIG. 3, a pair of shielding plates 46, 46 are provided between the discharge port of the die 16 and the surface of the cooling roll 18 so as to surround both ends of the film 12 </ b> A in the width direction.

  The shielding plate 46 is provided on the inner side of the both ends of the cooling roll 18 and through the gap between the side surface in the width direction of the die 16. The shielding plate 46 may be directly fixed to the side surface of the die 16 or may be supported and fixed by a support member (not shown).

  The width W of the shielding plate 46 is provided so as to efficiently block the rising airflow due to the heat radiation of the die 16, and for example, as shown in FIG. 4, the width Wd should be equal to or greater than the width Wd of the side surface of the die 16. Is preferred.

  The discharge port of the die 16 is preferably provided at a position lower than both the vertex P of the touch roll 28 and the vertex Q of the cooling roll 18. Thereby, since the discharge port of the die 16 is shielded from the outside between the cooling roll 18 and the touch roll 28, the film 12 </ b> A discharged from the die 16 can be hardly affected by the rising airflow or the like.

  The air gap L between the discharge port of the die 16 and the surface of the cooling roll 18 is preferably 200 mm or less in order to make it less susceptible to the influence of external air flow (including ascending airflow).

  The gap C1 between the shielding plate 46 and the end in the width direction of the film 12A, as shown in FIG. 5, is preferably narrowly formed to efficiently shield the rising airflow flowing along the surface of the cooling roll 18, More preferably, it is about 50 mm from the end in the width direction of the film 12A. Note that the gap C2 between the side surface of the die 16 and the shielding plate 46 is not necessarily provided, but is preferably formed to an extent that allows airflow in the space surrounded by the shielding plate 46 to be discharged, for example, 10 mm or less.

  FIG. 6 is a cross-sectional view between the lower end portion of the shielding plate 46 and the cooling roll 18. As shown in FIG. 6, the lower end portion of the shielding plate 46 has a labyrinth structure in order to effectively prevent air from flowing into the die 16 side from both ends in the width direction of the cooling roll 18. In the figure, the labyrinth structure is formed to be thicker than the thickness of the shielding plate 46 itself, thereby increasing the air flow resistance and improving the shielding performance. However, the present invention is not limited to this, and the same thickness is used. You may form in. Note that the lower end portion of the shielding plate 46 (the convex portion of the labyrinth structure in FIG. 6) is set such that the gap C3 with the surface of the cooling roll 18 is 10 mm or less in a range that does not contact the surface of the cooling roll 18. It is preferable.

  By comprising in this way, the fluctuation | variation of the wind speed in the space enclosed by the shielding board 46 is adjusted to 0.5 m / sec or less, Preferably it is 0.3 m / sec or less, More preferably, it is 0.1 m / sec or less. . Furthermore, the absolute value of the wind speed is preferably adjusted to 1 m / second or less.

  As the wind speed in the vicinity of the surface of the film 12A, a known anemometer, for example, Anemo Master anemometer (main body: MODEL 6162, probe: MODEL 204) manufactured by Nippon Kanomax Co., Ltd. can be used. The wind speed near the surface of the film 12A is a value at a position within 20 mm from the surface (film surface) of the film 12A.

  As the shielding board 46, what was excellent in the wind-shielding property and heat retention property is preferable, for example, metal plates, such as stainless steel, can be used preferably.

  The upward flow that affects the thickness unevenness of the film 12A is mainly caused by the fact that the die 16 is heated and the temperature difference between the surrounding atmosphere and the surface temperature of the cooling roll 18 is increased. Therefore, by increasing the ambient temperature in the vicinity of the surface of the film 12A, the temperature difference from the die 16 can be reduced, and an upward flow can be made difficult to occur.

  FIG. 7 is a perspective view showing an example of a configuration when a temperature control mechanism is provided in the vicinity of the surface of the film 12A.

  As shown in FIG. 7, a heater 46 </ b> A (heating means) for heating a space surrounded by the shielding plate 46 is embedded in the shielding plate 46, and the heater 46 </ b> A is connected to the control means 50. Further, a temperature sensor 48 is provided in the vicinity of the surface of the film 12 </ b> A so that the measurement result can be output to the control means 50. Then, when the temperature near the surface of the film 12A is measured by the temperature sensor 48, the control means 50 controls the heating temperature of the heater 46A embedded in the shielding plate 46 based on the measurement result. Thus, the temperature difference between the atmosphere near the surface of the film 12A and the die 16 can be adjusted to be within a predetermined range.

  The temperature sensor 48 is preferably installed in a range where the distance from the surface of the film 12A is 20 mm or less, for example.

  As a heating means, not only the said heater but various heating means can be used. In the present embodiment, the heater 46A is embedded in the shielding plate 46, but the present invention is not limited to this, and a heater may be provided at a position different from the shielding plate 46.

  Further, a discharge means (not shown) for discharging the rising air current from the space surrounded by the shielding plate 46 may be provided. There is no limitation in particular as such a discharge means, For example, a suction pump, an ejector, etc. can be used.

  The touch roll method is a method of shaping a film surface by placing a touch roll on a cast drum. The touch roll 28 is not usually high in rigidity but preferably has elasticity. Thereby, it can suppress that a surface unevenness | corrugation is made into the range of this invention or less by an excess surface pressure. For this purpose, it is necessary to make the outer cylinder thickness of the roll thinner than that of a normal roll, and the outer wall thickness Z is preferably 0.05 mm to 7.0 mm, more preferably 0.2 mm to 5 mm. 0.0 mm, more preferably 0.3 mm to 3.5 mm. The touch roll may be installed on a metal shaft and a heat medium (fluid) may be passed between them. An elastic layer is provided between the outer cylinder and the metal shaft, and the heat medium (fluid) is filled between the outer cylinders. Can be mentioned.

  The temperature of the touch roll is preferably set to 60 ° C to 160 ° C, more preferably 70 ° C to 150 ° C, and still more preferably 80 ° C to 140 ° C. Such temperature control can be achieved by passing a temperature-controlled liquid or gas through these rolls. Thus, what has a temperature control mechanism inside is more preferable.

  The material of the touch roll is preferably a metal, more preferably stainless steel, and the surface is preferably plated. On the other hand, a rubber roll or a metal roll lined with rubber is not preferable because the rubber surface has irregularities and the thermoplastic film having the surface irregularities cannot be formed.

  The surface of the touch roll and casting roll has an arithmetic average height Ra of 100 nm or less, preferably 50 nm or less, and more preferably 25 nm or less.

  As the multistage cooling temperature condition with a plurality of cooling rolls, it is preferable to set the roll surface temperature in order from the upstream side in the film conveyance direction.

  Next, the effect | action of this invention is demonstrated with reference to FIG.3 and FIG.5.

  As shown in FIG. 3, the film 12 </ b> A discharged from the die 16 is landed on the surface of the cooling roll 18 and then cooled and solidified while being sandwiched between the touch roll 28.

  At this time, as shown in FIG. 5, the rising airflow (dotted arrow) flowing from the both ends in the width direction of the cooling roll 18 toward the discharge port of the die 16 is shielded by the pair of shielding plates 46 and 46. Thereby, it can suppress that the upward airflow which goes to the die | dye 16 side from the surface of the cooling roll 18 flows into film 12A periphery. Thereby, since the fluctuation | variation of a wind speed is adjusted to 0.3 m / sec or less in the film 12A surface vicinity, the thickness nonuniformity of film 12A can be suppressed.

  Further, by providing a temperature control mechanism as shown in FIG. 7, the temperature difference ΔT between the vicinity of the surface of the film 12A and the die 16 is adjusted to 160 ° C. or less. Specifically, if the die 16 is about 240 ° C, the ambient temperature near the surface of the film 12A is set to 80 ° C or higher. As a result, the temperature difference between the die 16 and its periphery can be reduced, and ascending air current can be made difficult to occur.

  As described above, in the present embodiment, in the melt film-forming process for forming the film 12A, the upward airflow is prevented from flowing into the surface of the cooling roll 18 into the air gap between the die 16 and the surface of the cooling roll 18. it can. Thereby, the wind speed fluctuation | variation by an updraft does not arise in the film 12A surface vicinity, and it can suppress that thickness nonuniformity arises in the film 12A. Accordingly, it is possible to produce a cellulose acylate film that is excellent in surface shape and suitable for optical applications.

  In the present embodiment, an example in which the shielding plates 46 are provided only on both side surfaces in the width direction of the die 16 when the air gap between the die 16 and the cooling roll 18 is short has been described. It is preferable to provide a shielding plate 46 at a position facing the surface of the film 12A so as to surround the entire periphery of the film 12A. Thereby, not only the rising airflow flowing in from both ends in the width direction of the cooling roll 18 but also the rising airflow from the surface of the cooling roll 18 toward the die 16 through the vicinity of the surface of the film 12A and the surface of the touch roll 28 from the film 12A. Ascending airflow toward the die 16 through the vicinity of the surface can be blocked.

  In this case, the shielding plate 46 facing the surface of the film 12A is preferably provided within a range of 200 mm or less from the surface of the film 12A.

  In the present embodiment, an example in which the touch roll type cooling roll 18 is used has been described. However, the present invention is not limited to this, and for example, a casting roll type as shown in FIG. 8 can be adopted.

  FIG. 8 is an enlarged perspective view showing the configuration between the die and the cooling roll in the casting roll system, and FIG. 9 is a side view seen from the X direction in FIG. FIG. 10 is a perspective view when the temperature control mechanism is provided in FIG. In addition, the same code | symbol is attached | subjected about the member same as FIG. 4, and the detailed description is abbreviate | omitted.

  As shown in FIG. 8, a shielding plate 46 is provided between the die 16 and the cooling roll 18 so as to surround not only the width direction both ends of the film 12A but also the surface of the film 12A.

  In this case, it is preferable that the shielding plate 46 (the left shielding plate in FIG. 9) disposed to face the surface of the film 12 </ b> A is provided so as to protrude slightly from the surface of the cooling roll 18.

  Further, as shown in FIG. 10, by providing the shielding plate 46 with a temperature control mechanism, the ambient temperature in the space surrounded by the shielding plate 46 can be set to a predetermined temperature. Thereby, since the temperature difference between the atmospheric temperature in the shielding plate 46 and the die 16 can be reduced, it is possible to suppress the generation of ascending air current. The configuration of the temperature control mechanism is the same as that shown in FIG.

  Further, in the embodiment of FIG. 8 described above, the configuration surrounding both surfaces (the entire periphery) of the film 12A has been described. However, the configuration is not limited to this, and for example, only one side surface of the film 12A may be surrounded. In particular, it is preferable to shield the surface of the film 12A that does not come into contact with the cooling roll 18. Thereby, since an above-mentioned ascending air current can be interrupted | blocked efficiently, it can suppress that thickness nonuniformity arises in the film 12A.

  As mentioned above, although preferable embodiment of the manufacturing method of the thermoplastic resin film which concerns on this invention was described, this invention is not limited to the said embodiment, Various aspects can be taken.

  For example, in the present embodiment, it is particularly effective to apply the present invention to a molten resin having a high melt viscosity temperature dependency. Specifically, as the molten resin having high temperature dependence, when the melting temperature of the film 12A immediately after being discharged from the die 16 is T (° C.), the film at (T-10) to T (° C.) A thermoplastic resin having an absolute value of a melt viscosity gradient of 1.7 Pa · s / ° C. or higher is included. In the case of using such a resin, by suppressing the wind speed fluctuation, the temperature fluctuation of the melted film 12A, that is, the melt viscosity fluctuation can be significantly reduced, and the thickness unevenness can be remarkably improved.

  The melt viscosity can be measured using, for example, a viscoelasticity measuring device using a cone plate (for example, a modular compact rheometer manufactured by Anton Paar: Physica MCR301). As a measurement condition, after the thermoplastic resin is sufficiently dried until the water content becomes 0.1% or less, the shear rate can be measured at 1 (/ second) at a predetermined temperature (a temperature close to the melting temperature).

  In the present embodiment, the example in which the ascending airflow is shielded by using the shielding plate 46 has been described. However, the present invention is not limited to this. For example, an airflow can be formed to shield the rising airflow.

  FIG. 11 is a diagram for explaining another aspect of the shielding mechanism according to the present invention. FIG. 12 is a side view of FIG. 11 viewed from the X direction.

  As shown in FIG. 11, the shielding mechanism 51 includes a casing 52 that surrounds between the longitudinal direction of the die 16 and the surface of the cooling roll 18, and the film 12 </ b> A is provided at both ends in the width direction of the casing 52. An air blowing nozzle 54 that forms an air flow in the Y direction is connected so as to shield the widthwise end of the air.

  The blower nozzle 54 is connected to a blower (not shown) and is configured to blow out clean air. Further, the blower nozzle 54 is provided with a temperature adjusting mechanism (not shown) so that the blower temperature can be adjusted.

  A labyrinth mechanism 56 including a plurality of baffle plates 52A is formed at both ends in the width direction of the casing 52 to which the blower nozzles 54 are connected. As a result, the air supplied from the blow nozzle 54 into the housing 52 is buffered by passing through the labyrinth mechanism 56 and rectified, and then air in the Y direction so as to shield the width direction end of the film 12A. Form a flow. Thus, since the air supplied from the blowing nozzle 54 is buffered by passing through the labyrinth mechanism 56, there is no possibility of disturbing the airflow near the surface of the film 12A.

  It is preferable that the flow rate of the air blocking the width direction end of the film 12A is set to 0.6 to 1.0 m / sec. If the air blowing temperature is too high, the film 12A is likely to be necked in, so it is preferable to set the air temperature to about Tg ± 20 ° C. (eg, about 140 ° C.).

  Moreover, it is preferable to make the space | interval of the width direction edge part of the film 12A and the air flow formed into the range of 50 mm or more.

  In the embodiment of FIG. 11, the example in which the air blowing nozzle 54 is used as the air flow forming unit has been described. However, the embodiment is not limited thereto, and as illustrated in FIG. An air flow may be formed to shield.

  FIG. 13 is a perspective view illustrating still another aspect of the shielding mechanism according to the present invention. FIG. 14 is a side view of FIG. 13 viewed from the X direction.

  As shown in FIG. 13, the configuration is substantially the same as that of FIG. 11 except that a suction nozzle 58 is provided instead of the blower nozzle 54. In addition, the member which has the same function as FIG.11 and FIG.12 attaches | subjects the same code | symbol, and abbreviate | omits the detailed description.

  In this way, by sucking the end portion in the width direction of the film 12A with the suction nozzle 58, a gentle air flow can be formed so as to shield the end portion in the width direction of the film 12A. For this reason, it can suppress that an updraft flows in from the width direction both ends of the film 12A, without disturbing the airflow near the surface of the film 12A by an air flow.

  Next, a second embodiment of the present invention will be described. This embodiment is an example of reducing fluctuations in wind speed in the vicinity of the film surface by providing a rectifying means for rectifying the airflow in the vicinity of the film surface.

  FIG. 15 is a perspective view illustrating another aspect of the thermoplastic resin film manufacturing apparatus provided with the blowing nozzle 60 (air flow forming means) according to the present invention. FIG. 16 is a side view of FIG. 15 viewed from the X direction. Members having the same functions as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  As shown in FIG. 15, a pair of blowing nozzles 60 are provided at the discharge port of the die 16 along the longitudinal direction of the die 16.

  The blower nozzle 60 is connected to a pump or the like (not shown) and blows clean air uniformly in the discharge direction (vertical direction) along the surface of the film 20A. As a result, even if an ascending airflow is generated near the surface of the film 20A, as shown in FIG. 16, it is canceled out by the clean air flowing in the opposite direction, so that fluctuations in the wind speed near the surface of the film 12A can be reduced.

  It is preferable that the flow rate of the air blown out from the blower nozzle 60 is set so as to be a size necessary for canceling the ascending air current, specifically, 0.6 to 1.0 m / sec. The air flow rate is a value at a position within 20 mm from the film surface of the film 12A. If the air blowing temperature is too high, the film 12A is likely to be necked in, so it is preferable to set the air temperature to about Tg ± 20 ° C. (eg, about 140 ° C.).

  The rectifying means is not limited to the blowing nozzle 60, and may be a suction nozzle 62 as shown in FIG.

  FIG. 17 is a perspective view for explaining another aspect of the thermoplastic resin film manufacturing apparatus provided with the suction nozzle 62 (rectifying means) according to the present invention. FIG. 18 is a side view of FIG. 17 viewed from the X direction.

  As shown in FIG. 17, a pair of suction nozzles 62 are provided along the longitudinal direction of the die 16 at the discharge port of the die 16. Thereby, a flow in the direction opposite to the vertical direction is formed in the vicinity of the surface of the film 12A. Therefore, fluctuations in wind speed can be reduced by rectifying the vicinity of the surface of the film 12A.

  The flow rate of air formed by vacuum suction near the surface of the film 12A is preferably set to a value necessary for correcting the turbulence caused by the rising airflow, for example, 0.6 to 1.0 m / sec. be able to.

  In addition, in said FIG. 15-18, although the example which provided the ventilation nozzle 60 or the suction nozzle 62 in the discharge outlet vicinity of the die | dye 16 was shown, it is not limited to this, It is below the film 12A (cooling roll side). It may be provided.

  As shown in FIG. 19, the thermoplastic film 12A melt-formed as described above is preferably subjected to longitudinal stretching and lateral stretching, and may further be combined with shrinkage treatment. Of these, preferred are those in which transverse stretching is carried out after longitudinal stretching, or a combination of transverse stretching and longitudinal shrinkage treatment. The former is suitable for developing high Rth, and the latter is suitable for developing low Rth.

  When the transverse stretching and the longitudinal shrinkage treatment are performed in combination, the longitudinal shrinkage may be performed during the transverse stretching, may be performed after the transverse stretching, or may be performed both. Further, longitudinal stretching may be combined before or after the transverse stretching or both. In addition, after the film 12A is manufactured by the melt film-forming process, the film may be wound after the longitudinal stretching process and the lateral stretching process are continuously performed without being wound around the winder 26 once.

  In the present invention, longitudinal stretching may be performed alone or in combination with lateral stretching. The longitudinal stretching may be performed either before or after the lateral stretching, but is more preferably performed before the lateral stretching. In addition, the longitudinal stretching may be performed in one stage or may be performed in multiple stages.

  Longitudinal stretching can be achieved by installing two pairs of nip rolls and heating the gap between them so that the peripheral speed of the nip roll on the outlet side is higher than the peripheral speed of the nip roll on the inlet side. Under the present circumstances, the expression of the retardation of the thickness direction can be changed by changing the space | interval (L) between nip rolls, and the film width (W) before extending | stretching. When L / W exceeds 2 and is 50 or less (long span stretching), Rth can be reduced, and when L / W is 0.01 or more and 0.3 or less (short span stretching), Rth can be increased. In the present invention, any of a long span stretching, a short span stretching, and a region between them (intermediate stretching = L / W is more than 0.3 and 2 or less) may be used. Short span stretching is preferred. Further, when aiming at high Rth, it is more preferable to use short span stretching, and when aiming at low Rth, it is distinguished from long span stretching.

  The preferred stretching temperature for these longitudinal stretching is (Tg-10 ° C) to (Tg + 50) ° C, more preferably (Tg-5 ° C) to (Tg + 40) ° C, and more preferably (Tg) to (Tg + 30) ° C. is there. A preferable draw ratio is 2% to 200%, more preferably 4% to 150%, and still more preferably 6% to 100%.

  The transverse stretching can be performed using a tenter. That is, the film is stretched by gripping both ends in the width direction with clips and widening in the lateral direction. At this time, the stretching temperature can be controlled by sending wind at a desired temperature into the tenter. The stretching temperature is preferably Tg-10 ° C or higher and Tg + 60 ° C or lower, more preferably Tg-5 ° C or higher and Tg + 45 ° C or lower, and further preferably Tg or higher and Tg + 30 ° C or lower. A preferable draw ratio is 10% or more and 250% or less, more preferably 20% or more and 200% or less, and further preferably 30% or more and 150% or less. The draw ratio here is defined by the following formula.

Stretch ratio (%) = 100 × {(Length after stretching) − (Length before stretching)} / (Length before stretching)
Hereinafter, various materials used in the present invention will be described.

[Material of thermoplastic film]
The thermoplastic film used in the present invention is not particularly limited, but preferred examples include cellulose acylate resins, lactone ring-containing polymers, cyclic olefin resins, and polycarbonates. Among them, cellulose acylate resins and cyclic olefin resins are preferable, cellulose acylates containing acetate groups and propionate groups, and cyclic olefin resins obtained by addition polymerization are more preferable, and addition polymerization is more preferable. It is a cyclic olefin resin obtained by the above.

(1) Cellulose acylate resin Cellulose acylate resins include, for example, JP-A-2006-45500, JP-A-2006-241433, JP-A-2007-138141, JP-A-2001-188128, JP-A-2006-142800, JP-A-2007-. The total acyl substitution degree is preferably 2.1 or more and 3.0 or less, and the substitution degree of the acetyl group is preferably 0.05 or more and 2.5 or less, more preferably 0.05 or more and 0.00. 5 or less, or 1.5 or more and 2.5 or less. The propionyl substitution degree is preferably 0.1 or more and 2.8 or less, more preferably 0.1 or more and 1.2 or less, or 2.3 or more and 2.8 or less.

(2) Cyclic olefin resin The cyclic olefin resin is preferably polymerized from a norbornene compound. This polymerization can be carried out by either ring-opening polymerization or addition polymerization. Examples of the addition polymerization include those described in Japanese Patent No. 3517471, Japanese Patent No. 3559360, Japanese Patent No. 3867178, Japanese Patent No. 3871721, Japanese Patent No. 3907908, Japanese Patent No. 3945598, Japanese Translation of PCT International Publication No. 2005-527696, Japanese Patent Application Laid-Open No. 2006-28993, and WO 2006-004376. Particularly preferred is that described in Japanese Patent No. 3517471.

  Examples of the ring-opening polymerization include those described in WO98-14499, Japanese Patent 30605532, Japanese Patent 3220478, Japanese Patent 3273046, Japanese Patent 3404027, Japanese Patent 3428176, Japanese Patent 3687231, Japanese Patent 3873934, and Japanese Patent 3912159. Of these, those described in WO98-14499 and Japanese Patent No. 30605532 are preferable. Of these cyclic olefins, addition polymerization is more preferable.

(3) Lactone ring-containing polymer A polymer having a lactone ring structure represented by the following general formula (1) is shown.

(In the formula, R ¹ , R ² and R ³ each independently represent a hydrogen atom or an organic residue having 1 to 20 carbon atoms. The organic residue may contain an oxygen atom.) The content of the lactone ring structure of the formula (1) is preferably 5 to 90% by weight, more preferably 10 to 70% by weight, and still more preferably 10 to 50% by weight.

  In addition to the lactone ring structure represented by the general formula (1), at least selected from a (meth) acrylic acid ester, a hydroxyl group-containing monomer, an unsaturated carboxylic acid, and a monomer represented by the following general formula (2a) A polymer structural unit (repeating structural unit) constructed by polymerizing one kind is preferred.

(Wherein R ⁴ represents a hydrogen atom or a methyl group, X represents a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, an aryl group, an —OAc group, a —CN group, a —CO—R ⁵ group, or —C -O-R ⁶ group, Ac group represents an acetyl group, R ⁵ and R ⁶ represent a hydrogen atom or an organic residue having 1 to 20 carbon atoms.)
For example, those described in WO2006 / 025445, JP2007-70607, JP2007-63541, JP2006-171464, and JP2005-162835 can be used.

(4) Polycarbonate resin A resin obtained by reacting a dihydroxy component and a carbonate precursor by an interfacial polymerization method or a melt polymerization method. For example, those described in JP-A-2006-277914, JP-A-2006-106386, Those described in JP 2006-284703 can be preferably used.

(5) Additives In these thermoplastic films, 0 to 20% by mass of alkylphthalylalkyl glycolates, phosphate esters, carboxylic acid esters, and polyhydric alcohols can be added as plasticizers. Phosphite stabilizers (for example, tris (4-methoxy-3,5-diphenyl) phosphite, tris (nonylphenyl) phosphite, tris (2,4-di-t-butylphenyl) phosphite) as a stabilizer, Phenolic stabilizers (eg, 2,6-di-t-butyl-4-methylphenol, 2,2-methylenebis (4-ethyl-6-t-butylphenol), 2,5-di-t-butylhydroquinone, Pentaerythrityltetrakis [.3- (3,5-di-tert-butyl-4-hydroxyphenyl) propiolate, 4,4-thiobis- (6-tert-butyl-3-methylphenol), 1,1 ^, -Bis (4-hydroxyphenyl) cyclohexane, octadecyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) propiolate], An epoxy compound and a thioether compound can be added in an amount of 0 to 3% by mass, and an inorganic fine particle such as silica, titania, zirconia, alumina, calcium carbonate, or clay, and an organic fine particle such as crosslinked acrylic or crosslinked styrene can be added in an amount of 0 to 1000 ppm. Moreover, ultraviolet absorbers (for example, 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2,2, -methylenebis [4- (1,1,3,3-tetramethylbutyl) -6-[(2H -Benzotriazol-2-yl) phenol]]), an infrared absorber and a retardation modifier are also preferably added.

  Hereinafter, the features of the present invention will be described more specifically with reference to examples. However, the scope of the present invention should not be construed as being limited by the specific examples shown below.

Example 1
In this embodiment, the film 12A manufactured by shielding the air gap (molten resin film) between the die 16 and the touch roll type cooling roll 18 with the shielding plate 46 in the melt film forming step of FIG. It was tested how the surface condition of the was improved.

  As the final shape of the film 12A, the film thickness was 80 μm, the width after slitting the end was 1500 mm, and a cycloolefin copolymer (hereinafter also referred to as “COC”) was used as a raw material. The glass transition temperature Tg of the cycloolefin copolymer is 140 ° C.

  The air gap from the discharge port of the die 16 to the surface of the cooling roll 18 was set to 100 mm. The temperature of the die 16 was 260 ° C., and the line speed was 20 m / sec.

  As the shielding plate 46, a metal plate of material SUS304 and thickness 5 mm was used. The shielding board 46 was provided only in the width direction both ends (side surface) of the film 12A. The shielding plate 46 was installed so that the gap C2 with the side surface of the die 16 was 5 mm (the gap C1 with the end in the width direction of the film 12A was 50 mm) and the gap C3 with the surface of the cooling roll 18 was 12 mm. Further, the temperature control mechanism of FIG. 7 was used to adjust the atmospheric temperature at a point 20 mm away from the surface of the film 12A to 80 ° C., and the wind speed and temperature at this point were measured.

(Method of measuring wind speed and temperature)
Anemomaster anemometer (main body: MODEL 6162, probe: MODEL0204) manufactured by Nippon Kanomax Co., Ltd. was used.

  At a point 20 mm away from the surface of the film 12A, measurement was performed with time at 5 points in the width direction of the film 12A, and the wind speed fluctuation, the absolute value of the wind speed, and the wind temperature were obtained.

  Moreover, the surface temperature of the cooling rolls 18, 20, and 22 was set to 130 ° C., and the thickness unevenness of the manufactured film was measured.

(Measurement method of thickness)
Using an offline contact-type continuous thickness gauge (Anritsu Co., Ltd., Film Sickness Tester KG601B), the measurement pitch was measured at 1 mm intervals. The thickness was measured for the entire width of the film 12A after trimming in the film width direction, and was measured for the 3m length of the film 12A in the film transport direction. The thickness unevenness was evaluated according to the following criteria.

A: Uneven thickness range: 1 μm or less O: Uneven thickness range: 2 μm or less Δ: Uneven thickness range: 5 μm or less X: Uneven thickness range: More than 5 μm This result is shown in FIG.

(Example 2)
The shielding plate 46 was made the same as in Example 1 except that the gap C3 with the surface of the cooling roll 18 was set to 5 mm. The result is shown in FIG.

(Example 3)
Example 2 was the same as Example 2 except that the shielding plate 46 was configured to surround not only both ends in the width direction of the film 12A but also the entire periphery including the surface of the film 12A. The result is shown in FIG.

Example 4
The same operation as in Example 3 was performed except that the air gap (molten resin film length) between the die 16 and the cooling roll 18 was set to 200 mm. The result is shown in FIG.

(Example 5)
The same procedure as in Example 3 was performed except that the air gap (molten resin film length) between the die 16 and the cooling roll 18 was set to 50 mm. The result is shown in FIG.

(Example 6)
Instead of the touch roll type cooling roll 18, a casting roll type cooling roll 18 as shown in FIG. In addition, the shielding board 46 was provided in the side surface 46A, the side surface 46B, the front surface 46C (surface side which does not contact the cooling roll 18), and the bottom face 46E in FIG. The result is shown in FIG.

(Example 7)
The shielding plate 46 is configured to surround the entire periphery (side surface 46A, side surface 46B, front surface 46C, front surface 46D, bottom surface 46E) including the surface of the film 12A, and the same as in Example 6 except that the gap C3 is changed to 5 mm. I made it. The result is shown in FIG.

(Example 8)
The same procedure as in Example 1 was conducted except that the type of resin was changed from a cycloolefin copolymer to cellulose acylate propionate (hereinafter also referred to as “CAP”). Cellulose acylate propionate has a glass transition temperature Tg of 135 ° C. The result is shown in FIG.

Example 9
The shielding plate 46 was configured to surround not only both ends in the width direction of the film 12A but also the entire periphery including the surface of the film 12A, and the same as in Example 8 except that the gap C3 was changed to 5 mm. The result is shown in FIG.

(Example 10)
The same as in Example 1 except that the type of resin was changed from cycloolefin copolymer to polyethylene terephthalate (hereinafter also referred to as “PET”), and the ambient temperature at a point 20 mm away from the surface of the film 12A was set to 90 ° C. I made it. The glass transition temperature Tg of polyethylene terephthalate is 70 ° C. The result is shown in FIG.

(Example 11)
The shielding plate 46 was configured to surround not only both ends in the width direction of the film 12A but also the entire periphery including the surface of the film 12A, and the same as in Example 10 except that the gap C3 was changed to 5 mm. The result is shown in FIG.

(Comparative Example 1)
Example 1 was performed except that the shielding plate 46 was not provided. The result is shown in FIG.

(Comparative Example 2)
Example 6 was performed except that the shielding plate 46 was not provided. The result is shown in FIG.

(Comparative Example 3)
Example 8 was performed except that the shielding plate 46 was not provided. The result is shown in FIG.

(Comparative Example 4)
Example 10 was performed except that the shielding plate 46 was not provided. The result is shown in FIG.

  As can be seen from the table in FIG. 20, in Examples 1 to 11 in which the shielding plate 46 is provided between the die 16 and the surface of the cooling roll 18, the wind speed fluctuation in the vicinity of the surface of the film 12 </ b> A is 0.5 m / sec. Good results with less thickness unevenness were obtained. Moreover, in any of the said Examples 1-11, the absolute value of the wind speed was as small as 1 m / sec, and the bad influence on thickness nonuniformity was not seen.

  On the other hand, in Comparative Examples 1 to 4 in which the shielding plate 46 was not provided between the die 16 and the surface of the cooling roll 18, the wind speed fluctuation in the vicinity of the surface of the film 12A exceeded 0.5 m / second, and the thickness It was found that a lot of unevenness occurred. Moreover, the absolute value of the wind speed was as large as 1.2 m / second or more.

  Moreover, it turned out that shielding property improves by making the clearance gap C3 of the surface of the cooling roll 18 and the shielding board 46 small, and the wind speed fluctuation | variation in the film 12A surface vicinity reduces (Example 1, 2). Further, it is understood that the shielding performance is improved by providing the shielding plate 46 on the entire surface of the film 12A, the wind speed fluctuation near the surface of the film 12A is reduced to 0.1 m / second or less, and the thickness unevenness is remarkably reduced. (Example 3). It was also found that shortening the air gap and improving the shielding performance of the film 12A is effective in reducing wind speed fluctuation (Examples 3, 4, and 5).

  In the casting roll method, similarly to the touch roll method, the shielding plate 46 is provided on at least one front surface (front surface 46C), side surface, and bottom surface of the film 12A, preferably on the entire surface, so that the wind speed fluctuation in the vicinity of the film 12A surface is provided. It was found that thickness unevenness can be suppressed. (Examples 6 and 7).

  Moreover, when cellulose acylate propionate and polyethylene terephthalate were used as resin, it turned out that the same tendency as the case of a cycloolefin copolymer is acquired (Examples 8-11).

  From the above results, it was confirmed that application of the present invention can suppress uneven thickness of the film.

  Next, the case where the wind speed fluctuation | variation near the surface of film 12A was suppressed by the airflow control system was examined.

Example 12
The air velocity fluctuation and thickness unevenness in the vicinity of the surface of the film 12A were measured in substantially the same manner as in Example 1 except that air was allowed to flow along the surface of the film 12A with the blowing nozzle 60 shown in FIG. The results are shown in the table of FIG.

(Example 13)
The air velocity fluctuation in the vicinity of the surface of the film 12A was measured in substantially the same manner as in Example 1 except that air was passed along the surface of the film 12A by the suction nozzle 62 shown in FIG. The results are shown in the table of FIG.

(Example 14)
In the case 52 shown in FIG. 11, the labyrinth is eliminated, and the air nozzle is used to form the air flow on the outside of both ends in the width direction of the film 12 </ b> A. The wind speed fluctuation of was measured. The results are shown in the table of FIG.

(Example 15)
In the casing 52 shown in FIG. 13, the labyrinth is eliminated, and the vicinity of the surface of the film 12 </ b> A is substantially the same as in Example 1 except that an air flow is formed outside the both ends in the width direction of the film 12 </ b> A by the suction nozzle 58. The wind speed fluctuation of was measured. The results are shown in the table of FIG.

(Example 16)
The air velocity fluctuations in the vicinity of the surface of the film 12A were measured in substantially the same manner as in Example 1 except that the air flow was formed outside the both ends in the width direction of the film 12A by the blowing nozzle 54 of the casing 52 shown in FIG. . The results are shown in the table of FIG.

(Example 17)
The air velocity in the vicinity of the surface of the film 12A is substantially the same as in Example 1 except that an air flow is formed outside the both ends in the width direction of the film 12A by the suction nozzle 58 of the housing 52 (with labyrinth) shown in FIG. Variation was measured. The results are shown in the table of FIG.

(Example 18)
The wind speed fluctuation near the surface of the film 12A was measured in substantially the same manner as in Example 17 except that the air gap (molten resin film length) between the die 16 and the cooling roll 18 was set to 200 mm. The results are shown in the table of FIG.

Example 19
Wind velocity fluctuations near the surface of the film 12A were measured in substantially the same manner as in Example 17 except that the type of resin was changed from cycloolefin copolymer to cellulose acylate propionate (hereinafter also referred to as “CAP”). The results are shown in the table of FIG.

  As can be seen from the table of FIG. 21, Examples 12 and 13 are cases where air is flown along the surface of the film 12A and rectified. Examples 14 to 19 are cases in which the upward airflow is prevented from hitting the vicinity of the surface of the film 12A by forming an airflow on both outer sides of the film 12A in the width direction. Comparative Examples 1 and 3 are cases where the airflow control as described above was not performed.

  In each of Examples 12 to 19, the wind speed fluctuation in the vicinity of the surface of the film 12A was 0.5 m / second or less, and the thickness unevenness could be 5 μm or less.

  On the other hand, in Comparative Examples 1 and 3, as described above, it was found that the variation in the wind speed near the surface of the film 12A exceeded 0.5 m / second, and a large amount of unevenness in thickness occurred.

  Further, in Examples 14 to 19 in which the casing 52 and the blowing nozzle 54 or the suction nozzle 58 were used in combination, the variation in the wind speed in the vicinity of the surface of the film 12A was set to 0.3 m / second or less, and the thickness unevenness could be reduced. Furthermore, after passing the air flow through the labyrinth mechanism 56 in the housing 52, if the air flow is formed outside the both ends in the width direction of the film 12A, the rising air flow is not disturbed and the air speed near the surface of the film 12A is not disturbed. It was able to block effectively (Examples 16 to 19).

  From the above results, it was confirmed that application of the present invention can suppress uneven thickness of the film.

It is a whole block diagram which shows an example of the manufacturing apparatus of the thermoplastic resin film in 1st Embodiment. It is sectional drawing which shows the structure of the extruder in 1st Embodiment. It is an expansion perspective view which shows the structure between the die | dye in 1st Embodiment, and a cooling roll. It is the side view seen from the X direction in FIG. It is sectional drawing seen from the Y direction in FIG. It is an expanded sectional view of the shielding board of the surface vicinity of the cooling roll of FIG. It is a perspective view which shows the temperature control mechanism of the film surface vicinity in 1st Embodiment. It is an expansion perspective view which shows the other structure between the die | dye in 1st Embodiment, and a cooling roll. It is the side view seen from the X direction in FIG. It is a perspective view which shows the temperature control mechanism of the film surface vicinity in FIG. It is a perspective view explaining another aspect of the shielding mechanism in 1st Embodiment. It is the side view which looked at FIG. 11 from the X direction. It is a side view explaining another aspect of the shielding mechanism in a 1st embodiment. It is the side view which looked at FIG. 12 from the X direction. It is a perspective view explaining the shielding mechanism in a 2nd embodiment. It is the side view which looked at FIG. 15 from the X direction. It is a perspective view explaining the other aspect of the shielding mechanism in 2nd Embodiment. It is the side view which looked at FIG. 17 from the X direction. It is a block diagram in the case of carrying out the longitudinal stretch and the lateral stretch of the film manufactured in this embodiment. It is a table | surface figure which shows the result of a present Example. It is a table | surface figure which shows the result of a present Example. It is an expanded sectional view which shows the structure between the die | dye and the cooling roll in the casting roll system of a present Example. It is an expansion perspective view which shows the structure between the conventional die | dye and a cooling roll.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Manufacturing apparatus of a thermoplastic resin film, 12 ... Cellulose acylate resin, 12A ...
Film, 14 ... Extruder, 16 ... Die, 18, 20, 22 ... Cooling roll, 24 ... Release roll, 26 ... Winder, 28 ... Touch roll, 46 ... Shield plate, 46A ... Heater, 48 ... Temperature sensor, DESCRIPTION OF SYMBOLS 50 ... Control means, 51 ... Shielding mechanism, 52 ... Housing | casing, 54, 60 ... Air blow nozzle, 56 ... Labyrinth mechanism, 58, 62 ... Suction nozzle

Claims (21)

A die for discharging a molten thermoplastic resin into a film;
A cooling roll disposed opposite the discharge port of the die and cooling and solidifying the discharged film;
Shielding means for shielding at least the widthwise end of the film from the die outlet to the surface of the cooling roll between the widthwise end of the cooling roll and the widthwise end of the film; ,
An apparatus for producing a thermoplastic resin film, comprising:   The said shielding means is a shielding board provided in the substantially orthogonal direction with respect to the said film surface between the width direction edge part of the said cooling roll, and the width direction edge part of the said film. The manufacturing apparatus of the thermoplastic resin film of description.   The apparatus for producing a thermoplastic resin film according to claim 2, wherein an interval between the shielding plate and an end in the width direction of the film is 50 mm or less.   The thermoplastic resin film manufacturing apparatus according to claim 2, wherein the shielding means is further provided so as to surround a periphery including a surface of the film.   The shielding means includes a casing that encloses between the longitudinal direction of the die and the surface of the cooling roll and in which a labyrinth mechanism is formed, and the film is provided at both ends in the width direction of the casing. The apparatus for producing a thermoplastic resin film according to claim 1, further comprising air flow forming means for forming an air flow in a direction substantially orthogonal to the surface.   The said air flow formation means is a ventilation nozzle or a suction nozzle, The manufacturing apparatus of the thermoplastic resin film of Claim 5 characterized by the above-mentioned. A die for discharging a molten thermoplastic resin into a film;
A cooling roll disposed opposite the discharge port of the die and cooling and solidifying the discharged film;
Rectifying means provided near the discharge port of the die and rectifying the vicinity of the surface of the film from the discharge port until landing on the surface of the cooling roll;
An apparatus for producing a thermoplastic resin film, comprising:   The thermoplastic resin film according to claim 7, wherein the rectifying means is a blow nozzle or a suction nozzle that is provided near the discharge port of the die and blows in parallel with the discharge direction of the film. Manufacturing equipment. Measuring means for measuring the temperature in the vicinity of the film surface;
Based on the measured results, heating means for bringing the vicinity of the film surface to a predetermined temperature;
The apparatus for producing a thermoplastic resin film according to any one of claims 1 to 8, wherein the apparatus is provided. The apparatus for producing a thermoplastic resin film according to any one of claims 1 to 9, wherein an air gap from a discharge port of the die to a grounding point of the film on the surface of the cooling roll is 200 mm or less. . A touch roll is provided adjacent to the cooling roll,
11. The thermoplastic resin film according to claim 1, wherein a discharge port of the die is provided at a position lower than any of a vertex of the cooling roll and a vertex of the touch roll. Manufacturing equipment.   The manufacturing method of the thermoplastic resin film characterized by reducing the fluctuation | variation of the wind speed in the said film surface vicinity by using the manufacturing apparatus of the thermoplastic resin film of any one of Claims 1-11. In a method for producing a thermoplastic resin film comprising a step of discharging a molten thermoplastic resin from a die into a film and cooling and solidifying the discharged film on a cooling roll,
A method for producing a thermoplastic resin film, wherein a fluctuation in wind speed in the vicinity of the surface of the discharged film is set to 0.5 m / second or less.   14. The method for producing a thermoplastic resin film according to claim 13, wherein the vicinity of the surface of the film from the discharge port of the die to landing on the surface of the cooling roll is rectified.   The method for producing a thermoplastic resin film according to claim 14, wherein the rectification is performed by blowing or sucking in parallel with a discharge direction of the film.   The method for producing a thermoplastic resin film according to any one of claims 13 to 15, wherein a wind speed in the vicinity of the film surface is 1 m / sec or less.   The method for producing a thermoplastic resin film according to any one of claims 13 to 16, wherein a temperature difference between the vicinity of the film surface and the die is within a range of 160 ° C or less.   The said cooling roll is a touch roll system, The manufacturing method of the thermoplastic resin film of any one of Claims 13-17 characterized by the above-mentioned.   The thermoplastic resin has an absolute value of a melt viscosity gradient of 1.7 Pa · s / ° C. at (T−10) ° C. to T ° C. when the melting temperature immediately after being discharged from the die is T (° C.). It is the above, The manufacturing method of the thermoplastic resin film of any one of Claims 13-18 characterized by the above-mentioned.   The method for producing a thermoplastic resin film according to any one of claims 13 to 19, wherein the thermoplastic resin is a cellulose resin or a cyclic olefin resin.   The method for producing a thermoplastic resin film according to any one of claims 13 to 20, wherein the thickness unevenness of the film is 1 µm or less.