JP4882566B2 - Manufacturing method of optical film - Google Patents

Description

  The present invention is used in various functional films such as a protective film for polarizing plates used for liquid crystal display devices (LCD), retardation films, viewing angle widening films, antireflection films used in plasma displays, and organic EL displays. The present invention relates to a method for producing an optical film that can be used for various functional films.

  In recent years, the demand for liquid crystal display devices has increased due to the widespread use of liquid crystal displays mounted on automobiles, large liquid crystal television displays, mobile phones, notebook computers, and the like. A liquid crystal display device is widely used as a monitor because it saves space and energy compared to a conventional CRT display device. Furthermore, it is also spreading for TV. In such a liquid crystal display device, various optical films such as a polarizing film and a retardation film are used.

  As a basic configuration of this liquid crystal display device, polarizing plates are provided on both sides of a liquid crystal cell. The polarizing plate transmits only light having a polarization plane in a certain direction. Therefore, in the liquid crystal display device, it plays an important role in visualizing the change in the alignment of the liquid crystal due to the electric field. That is, the performance of the liquid crystal display device greatly depends on the performance of the polarizing plate. A general configuration of the polarizing plate will be described with reference to the drawings.

  FIG. 7 is a schematic sectional view of a polarizing plate. In the figure, 1 is a polarizer, and protective films 2 are laminated on both sides of the polarizer 1. In some cases, the protective film may have a phase difference correction function. A liquid crystal display device is configured by laminating a polarizing plate having such a configuration on a liquid crystal cell. The protective film is provided for the purpose of improving the durability of the polarizer. Conventionally, as a polarizing plate protective film, there is an optical film that is transparent, has excellent physical and mechanical properties, and has a small dimensional change with respect to temperature and humidity. in use.

  In the present invention, including the protective film shown in FIG. 7, various functional films such as retardation films used in liquid crystal display devices (LCD), viewing angle widening films, antireflection films used in plasma displays, organic EL displays, etc. Various functional films used in the above are called optical films.

  Conventionally, a solution casting film forming method and a melt casting film forming method are used for manufacturing such an optical film. In the case of using the solution casting film forming method, it is manufactured by casting a solution obtained by dissolving a resin in a solvent on a metal support, removing the solvent in a drying step, and winding the film. In addition, when using the melt casting film forming method, the resin is melted by heat, the molten resin that has reached a high temperature is melt-extruded from a die, formed on a cooling roll, and a conveying step for lowering the temperature of the film It is manufactured by winding the film. Both of these methods may be adjusted by stretching with a tenter after film formation in order to adjust optical properties and flatness. In any case, when a film having a soft surface after film formation is transported by a transport roll, it is necessary to use a roll having a small surface roughness so that the surface shape of the transport roll is not transferred.

  Further, with the recent increase in demand for liquid crystal display devices, the production speed has been increased in order to cope with the increased production of optical films. However, when speeding up, the transport speed of the optical film transported only by the transport roll with a small surface roughness does not match the peripheral speed of the transport roll used for transport, so-called roll slip occurs, There was a problem that scratches occurred on the contact surface of the transport roll of the optical film, making it unusable as a product. This problem is a problem in both the melt casting film forming method and the solution casting film forming method, but in the case of using the solution casting film forming method, a long drying process is required to remove the solvent, and the transport roll Therefore, when the conveying speed is increased, the risk of scratching is higher than in the melt casting film forming method.

  Roll slip can be suppressed by increasing the frictional force between the surface of the transport roll and the optical film, but if the transport tension is increased to increase the frictional force, wrinkles may occur on the optical film during transport. There is a risk that retardation and dimensional stability are deteriorated. As another means, there is a method of increasing the roughness of the surface of the transport roll. In this case, fine irregularities on the surface of the transport roll are transferred to the film surface, and the flatness of the finished film is not suitable for the product. turn into. As a countermeasure against roll slip accompanying the increase in speed as described above, there is known a method for producing a cellulose ester fill that uses a transport roll obtained by roughing only a portion of the surface of the transport roll that does not become a product (for example, a patent) Reference 1).

  Although the use of a transport roll as described in Patent Document 1 is effective against roll slip, the following problems can be cited.

  1. In order to respond to the increase in demand for wide optical films in accordance with the increase in size of liquid crystal displays, it is necessary to manufacture optical films of various widths, including the production of conventional optical films. ing. For this reason, when a narrow-width optical film is produced in a process using a transport roll adapted to the production of a wide-width optical film, the speed cannot be increased because there is a risk of roll slippage.

  2. When a wide-width optical film is produced in a process that uses a transport roll that matches the production of a narrow-width optical film, the shape of the end of the transport roll is transferred to the optical film and enters the product part. I can't.

  3. When producing a narrow-width optical film in a process using a roll suitable for the production of a wide-width optical film, if both ends of the film being transported are in contact with both ends of the roll, before winding This is uneconomical because the amount of end trim that is not a product increases.

  4). In order to produce stably, what is necessary is just to change a conveyance roll according to the width | variety of the optical film to produce, but this requires a lot of man-hours and cost, and production efficiency will also fall.

For this reason, in order to accommodate a wide range of widths, a transport roll is provided in accordance with a wide optical film and produced at high speed, and the production speed of a narrow optical film is such that roll slip does not occur. The production is lowered. For this reason, it is one of the reasons why production efficiency does not increase. Under these circumstances, it is desired to develop a method for producing an optical film that can be conveyed at high speed and has a stable quality without changing the width of the conveyance roll in accordance with the change in the width of the optical film to be produced.
JP 2003-19726 A

  The present invention has been made in view of the above situation, and its purpose is to provide an optical film having a stable quality capable of high-speed conveyance without changing the width of the conveyance roll in accordance with the change in the width of the optical film to be produced. A manufacturing method is provided.

  The above object of the present invention has been achieved by the following constitution.

1. A liquid in which a raw resin is dissolved in a solvent or a liquid melted by heating is cast on an endless support to form a web, and after peeling the web from the endless support, it is brought into contact with a transport roll and transported. In the manufacturing method of the optical film manufactured by winding, the conveyance roll has a conveyance auxiliary portion on a circumferential surface in the width direction in the vicinity of at least one end portion, and one end portion of the web, the conveyance auxiliary portion, In the method of manufacturing an optical film that is conveyed in contact with each other ,
A conveyance angle changing step in which a conveyance angle changing roll for changing the conveyance direction of the web is installed in the conveyance step of the web so that either one end of the web is in contact with the conveyance auxiliary unit. The method for producing an optical film is characterized in that one end of the web and the conveyance auxiliary unit are brought into contact with each other and conveyed .

  2. 2. The method for producing an optical film as described in 1 above, wherein the conveyance auxiliary part is formed with a rough surface having an average roughness Ra of 1 μm to 100 μm.

  3. 2. The method for producing an optical film as described in 1 above, wherein the conveyance auxiliary part is formed of a convex part having a height of 10 μm to 500 μm.

  4). 2. The method for producing an optical film as described in 1 above, wherein the conveyance auxiliary part is formed by a concave part having a depth of 0.05 mm to 1 mm.

  5. 5. The method for producing an optical film according to any one of 1 to 4, wherein the web conveyance speed is 30 m / min to 150 m / min.

6). Any one of claim 1 to 5, characterized in that to convey the contacted and the transport assisting section one end of the web in the region residual solvent content of 2% to 30% by weight of the web The manufacturing method of the optical film of description.

7). In the web transport process, a transport angle change step is provided in which a transport angle change roll for changing the transport direction of the web is installed so that one end of either of the webs is in contact with the transport auxiliary unit. The web is transported to the transport angle changing step when the residual solvent amount of the web is 2% by mass to 30% by mass, and transported by bringing one end of the web into contact with the transport auxiliary unit. The manufacturing method of the optical film of any one of 1-5 .

8). The transport angle changing roll is arranged so that an angle formed between a direction perpendicular to the axis of the transport angle changing roll and a web transport direction is 0.3 ° to 3 °. The manufacturing method of the optical film of any one of 1-7 .

  It is possible to provide a production method of optical film with stable quality that can be conveyed at high speed without changing the width of the conveyance roll in accordance with the change of the width of the optical film to be produced. It became possible to produce films with high-speed conveyance, and it became possible to improve the production efficiency of the process.

  Although an embodiment of the present invention will be described with reference to FIGS. 1 to 6 as a representative example of a cellulose ester film as an optical film, the present invention is not limited to this.

  FIG. 1 is a schematic diagram of a solution casting method for optical films. FIG. 1A is a schematic diagram of a solution casting film forming method for an optical film in a case where a tenter is conveyed after casting and then dried in a drying step. FIG. 1B is a schematic diagram of a solution casting film forming method for an optical film in the case of performing preliminary drying in a drying process after casting, transporting a tenter, and drying in the drying process. FIG. 1C is a schematic view of a solution casting film forming method for an optical film in the case where, after casting, preliminary drying is performed in a drying step and then drying is performed in the drying step. FIG.1 (d) is a schematic diagram of the solution casting film forming method of the optical film in the case of drying in the drying process after casting.

  The schematic diagram of the solution casting film forming method of the optical film shown in FIG. In the figure, reference numeral 3a denotes an optical film solution casting apparatus. The solution casting film forming apparatus 3a includes a casting process 301, a stretching process 302, a drying process 303, and a winding recovery process 304.

  The casting process 301 includes an endless mirror belt-like metal casting belt (hereinafter referred to as a belt) 301a that travels endlessly (in the direction of the arrow in the figure) and a dope 4 in which a cellulose ester resin is dissolved in a solvent. And a die 301b that is cast on the surface. 5 shows the peeling point which peels the cellulose-ester film which the dope cast | flow_casted to the belt 301a solidified, 6 shows the peeled cellulose-ester film.

  The stretching step 302 includes an outer box 302c having a dry air intake port 302a and a discharge port 302b, and a tenter stretching device 302d placed in the outer box 302c. The tenter used in the tenter stretching apparatus 302d is not particularly limited, and examples thereof include a clip tenter and a pin tenter, which can be selected and used as necessary. In addition, the dry air intake port 302a and the discharge port 302b may be reversed. It is preferable that the amount of the solvent stretched to the width required in the stretching step 302 and contained in the cellulose ester film is 5% by mass to 30% by mass in consideration of scratches, shrinkage, deformation, and the like.

  The drying step 303 includes a drying box 303a having a dry air intake port 303b and a discharge port 303c, an upper transport roll 303d that transports the cellulose ester film 6, and a lower transport roll 303e. The upper conveyance roll 303d and the lower conveyance roll 303e are one set in the vertical direction, and are composed of a plurality of sets. Reference numeral 303 f denotes a transport roll for transporting the cellulose ester film 6 coming out from the stretching step 302. The number of transport rolls arranged in the drying step 303 varies depending on the drying conditions, the method, the length of the cellulose ester film to be produced, and the like, but is usually about 200 to 800, for example. The upper conveyance roll 303d and the lower conveyance roll 303e are free rotation rolls that are not rotationally driven by a drive source. In addition, between the film transporting process and the winding process, a transporting roll that freely rotates is not used, but usually one to several transporting drive rolls (rolls that are rotationally driven by a driving source). Requires installation. Basically, the purpose of the transport drive roll is to transport the cellulose ester film by its drive, so the transport of the cellulose ester film and the rotation of the drive roll are performed by nip or suction (air suction). With a synchronization mechanism.

  The winding and collecting step 304 has a winding device (not shown), and winds the cellulose ester film 6 that has been dried to a necessary length to the winding core. Reference numeral 304a denotes a roll-shaped cellulose ester film wound around a winding core. The temperature at the time of winding is preferably cooled to room temperature in order to prevent scratches and loosening due to shrinkage after winding. The same applies to the schematic diagrams of the solution casting film forming method of the optical film shown in FIG. 1 (b) to FIG. 1 (d). The winder to be used may be a commonly used winder, and can be wound by a winding method such as a constant tension method, a constant torque method, a taper tension method, or a program tension control method with a constant internal stress.

  The schematic diagram of the solution casting film forming method of the optical film shown in FIG. In the figure, reference numeral 3b denotes an optical film solution casting apparatus. The solution casting film forming apparatus 3b includes a casting process 301, a first drying process 305, a stretching process 302, a second drying process 306, and a winding recovery process 304. The difference from the schematic diagram of the solution casting film forming method shown in FIG. 1A is that the cellulose ester film 6 peeled from the belt is once dried in the first drying step 305 before being stretched in the stretching step. is there. Other steps are the same as the schematic diagram of the solution casting film forming method shown in FIG. The first drying step 305 includes a drying box 305a having a drying air intake port 305b and a discharge port 305c, an upper conveyance roll 305d that conveys the cellulose ester film 6, and a lower conveyance roll 305e. The upper transport roll 305d and the lower transport roll 305e are a pair of upper and lower, and are composed of a plurality of sets. It is possible to adjust the amount of solvent contained in the cellulose ester film 6 before entering the stretching step 302 (same as the stretching step of FIG. 1A) in the first drying step 305.

  The second drying step 306 includes a drying box 306a having a drying air intake port 306b and a discharge port 306c, an upper conveyance roll 306d that conveys the cellulose ester film 6, and a lower conveyance roll 306e. The upper conveyance roll 306d and the lower conveyance roll 306e are one set up and down, and are composed of a plurality of sets (the same configuration as the drying step 305 shown in FIG. 1A). Other reference numerals are the same as those in FIG.

  The schematic diagram of the solution casting film forming method of the optical film shown in FIG.1 (c) is demonstrated. In the figure, reference numeral 3c denotes an optical film solution casting apparatus. The solution casting film forming apparatus 3c includes a casting process 301, a first drying process 305, a second drying process 307, and a winding recovery process 304. The second drying step 307 includes a drying box 307a having a dry air intake port 307b and a discharge port 307c, and an upper transport roll 307d and a lower transport roll 307e that transport the cellulose ester film 6. The upper transport roll 307d and the lower transport roll 307e are a pair of upper and lower, and are composed of a plurality of sets (the same configuration as the drying step 305 shown in FIG. 1A). In addition, since the 2nd drying process 307 does not have the extending | stretching process shown by FIG.1 (b), since the part dried by an extending process is performed by the 2nd drying process 307, the whole process is shown in FIG.1 (b). It is preferable to make it longer than the second drying step 306. The difference from the schematic diagram of the solution casting film forming method shown in FIG. 1 (b) is that it does not have a stretching process, and the cellulose ester film 6 peeled from the belt has a first drying process 305 and a second drying process. And is wound up and collected in a winding and collecting step 304. Other symbols are the same as those in FIGS. 1 (a) and 1 (b).

  The schematic diagram of the solution casting film forming method of the optical film shown in FIG. In the figure, reference numeral 3d denotes an optical film solution casting apparatus. The solution casting film forming apparatus 3d includes a casting process 301, a drying process 308, and a winding recovery process 304. The difference from the schematic diagram of the solution casting film forming method shown in FIG. 1C is that it does not have a first drying step, and the cellulose ester film 6 peeled from the belt is dried in the drying step 308 and wound up. In the collecting step 304, it is wound up and collected. The drying step 308 includes a drying box 308a having a drying air intake port 308b and a discharge port 308c, an upper conveyance roll 308d that conveys the cellulose ester film 6, and a lower conveyance roll 308e. The upper transport roll 308d and the lower transport roll 308e are one set up and down and are composed of a plurality of sets (the same configuration as the drying step 305 shown in FIG. Since the function of the step 350 (see FIG. 1B) is also provided, the whole is long). Other reference numerals are the same as those in FIG.

  Next, the residual solvent amount of the cellulose ester film in each step shown in FIGS. 1 (a) to 1 (d) will be described.

  In the case of FIG. 1A, the residual solvent amount of the cellulose ester film peeled off from the belt 301a after casting in the casting step 301 is the uniformity of residual stress, extensibility, and dimensional stability when peeling from the belt. In consideration of shrinkage during drying, etc., it is 50% by mass to 250% by mass, and preferably 80% to 140% by mass (the same applies to FIGS. 1B to 1D).

  The residual solvent amount of the cellulose ester film after being processed by the tenter stretching apparatus 302c in the stretching step 302 is preferably 5% by mass to 30% by mass in consideration of the expansion / contraction rate adjustment of the cellulose ester film in the drying unit, scratches, and the like. Preferably they are 6 mass%-25 mass%.

  The amount of residual solvent of the cellulose ester film after the drying treatment in the drying step 303 is preferably 0.1% by mass to 15% by mass in consideration of the load of the drying step, the dimensional stability expansion / contraction ratio during storage, and the like.

  In the case of FIG.1 (b), the residual solvent amount of the cellulose-ester film after the drying process of the 1st drying process 305 is 5 mass%-40 considering the drying load in the extending process 302, the stretchability of a extending process, etc. % By mass is preferable, and more preferably 10 to 35% by mass. The amount of residual solvent after the end of the subsequent stretching step 302 is the same as that in FIG. 1A, and the amount of residual solvent after the end of drying in the second drying step 306 is the drying amount in the drying step 303 of FIG. Same as at end.

  In the case of FIG.1 (c), the residual solvent amount of the cellulose-ester film after the drying process of the 1st drying process 305 is the same as the case of FIG.1 (b). The amount of residual solvent after the end of drying in the second drying step 307 is the same as that at the end of drying in the drying step 303 of FIG.

  In the case of FIG. 1D, the residual solvent amount of the cellulose ester film at the end of drying in the drying step 308 is the same as that at the end of drying in the drying step 303 of FIG.

  In the case of FIG. 1A, it is a time when the stretching step 302 is finished and the drying step 303 is entered. In the case of FIG. 1B, it is a time when the stretching step 302 is finished and the second drying step 306 is entered. In the case of FIG.1 (c), the residual solvent amount of a cellulose-ester film will be 5 mass%-30 mass% by the 2nd drying process 307. In the case of FIG.1 (d), it is a place from which the residual solvent amount of a cellulose-ester film will be 5 mass%-30 mass% by the drying process 308. FIG.

  The value of the residual solvent amount (% by mass) in the present invention is defined as B when the cellulose ester film having a certain size is dried at 115 ° C. for 1 hour, and B is the mass of the cellulose ester film before drying. ((A−B) / B) × 100 = a value obtained by the amount of residual solvent (% by mass).

  The means for evaporating the solvent of the dope on the belt shown in FIGS. 1 (a) and 1 (b) is not particularly limited. For example, a method of blowing warm air on the dope contact surface of the belt, heating with an infrared heater For example, a method of blowing warm air to the back surface of the belt and heating from the back surface side, a method of heating the back surface of the belt with warm water or heating oil, and the like. The time from casting to peeling depends on the film thickness of the cellulose ester film to be produced and the solvent used, but it takes 0.5 minutes in consideration of the peelability from the belt, the film forming efficiency, the length of the process, etc. A range of ˜5 minutes is preferred.

  The means for drying the cellulose ester film after being peeled from the belt is not particularly limited, and the stretching process shown in FIGS. 1 (a) and 1 (b) is generally performed with hot air, infrared rays, or the like. It is preferable to carry out with hot air in terms of simplicity. The drying temperature varies depending on the residual solvent amount of the cellulose ester film when entering the stretching process, but the condensation on the surface of the cellulose ester film accompanying the evaporation of the solvent, adjustment of the residual solvent amount, expansion / contraction rate, foaming of the solvent, etc. In consideration of the amount of residual solvent in the range of 30 ° C. to 180 ° C., drying may be performed at a constant temperature, or may be divided into several stages.

  In the drying step after the stretching step shown in FIGS. 1 (a) and 1 (b), and in the drying step shown in FIGS. 1 (c) and 1 (d), heating air, infrared rays alone, or heating air and infrared drying May be used in combination. It is preferable to use heated air in terms of simplicity. The drying temperature varies depending on the residual solvent amount of the cellulose ester film when entering the drying process, but considering the drying time, shrinkage unevenness, stability of the expansion / contraction amount, etc., depending on the residual solvent amount in the range of 30 ° C. to 180 ° C. It may be selected and determined, and may be dried at a constant temperature, or may be divided into three to four stages of temperature and may be divided into several stages of temperature.

  The film thickness of the cellulose ester film produced by the solution casting film-forming method shown in FIG. 1 (a) to FIG. 1 (d) varies depending on the purpose of use, but when used as the protective film shown in FIG. It is 20 μm to 120 μm, desirably 40 μm to 100 μm.

  In the case of changing the width of the optical film to be manufactured by the solution casting film forming method shown in FIGS. 1A to 1D, the present invention is used for high-speed transport without changing the width of the transport roll. However, the present invention relates to a method for producing an optical film that does not generate scratches due to roll slippage on a transport roll.

  FIG. 2 is a schematic diagram showing an example of a melt casting film forming method of an optical film.

  In the figure, reference numeral 7 denotes a melt casting film forming apparatus. The melt casting film forming apparatus 7 includes a film forming process 701, a stretching process 702, a heat treatment process 703, and a cooling process 704. The film forming step 701 includes a melt extruder 701a, a T die 701b, and a cooling roll 701c. The stretching step 702 includes a stretching device that stretches the obtained unstretched film peeled from the cooling roll 701c. As the stretching device, there are longitudinal stretching that stretches in the transport direction and lateral stretching that stretches in the transverse direction, and the stretching device differs depending on the stretching direction. For example, in the case of longitudinal stretching, heating is performed within a range of Tg + 100 ° C. from the glass transition temperature (Tg) of the amorphous thermoplastic resin by a longitudinal stretching device having a plurality of roll groups and / or heating devices such as an infrared heater. Or it is preferable to carry out multistage longitudinal stretching. In the case of lateral stretching, it is preferable to stretch with a tenter stretching device as a lateral stretching device.

  The stretching step 702 includes an outer box 702c having a heated air intake port 702a and a discharge port 702b, and a tenter stretching device 702d or a longitudinal stretching device (not shown) placed in the outer box 702c. The tenter used in the tenter stretching apparatus is not particularly limited, and examples thereof include a clip tenter and a pin tenter, which can be selected and used as necessary. The heated air intake port 702a and the discharge port 702b may be reversed. After extending | stretching to the width | variety required by the extending | stretching process 702, it is conveyed to the heat setting process (not shown) in a tenter process, and the state extended | stretched is fixed. After the transverse stretching, it is preferable that the film is held at a temperature not higher than the final transverse stretching temperature within a range of Tg-40 ° C. for 0.01 to 5 minutes because the distribution of physical properties in the width direction can be further reduced. After stretching, heat treatment is performed if necessary.

  The heat treatment step 703 includes a heat fixing device 703a having an outer box 703a3 having a heated air intake port 703a1 and a discharge port 703a2 and a plurality of transport rolls 703a4. Thereafter, the film heat-set in the cooling step 704 is usually cooled to Tg or less and collected.

  The cooling step 704 includes a cooling device 704a having an outer box 704a3 having a cooling air intake port 704a1 and a discharge port 704a2 for cooling the heat-fixed film, and a plurality of conveying rolls 704a4, and a winding device 704b. Yes.

  Next, general conditions for manufacturing an optical film using the manufacturing apparatus 7 shown in this figure are shown. The take-up speed with the cooling roll is preferably 5 m / min to 100 m / min in consideration of molecular orientation and birefringence.

  The melting temperature of the amorphous thermoplastic resin in the melt extruder 701a may be appropriately selected depending on the amorphous thermoplastic resin to be used. Among them, in order to avoid deterioration of the film appearance due to thermal decomposition of the molten resin, It is preferable to maintain at 300 ° C. or less until it is discharged from the T die after melting, and particularly preferably 290 ° C. or less.

  The temperature setting of the cooling roll 701c is one of the important production conditions having a great influence on the appearance and optical characteristics of the obtained optical film, and the balance between the adhesion of the molten film to the cooling roll and the release property is taken into consideration. The surface temperature was measured with a differential scanning calorimeter (hereinafter referred to as DSC) at a rate of temperature increase of 10 ° C./min. −40 ° C. to + 20 ° C. with respect to the glass transition temperature of the resin composition. It is preferable to set it as 0 degreeC, and it is preferable to set it as -35 degreeC-+10 degreeC especially.

  The screw rotation speed of the melt extruder 701a and the discharge amount from the T die can be appropriately selected according to the thickness of the optical film to be produced, the take-up speed, and the like. In order to suppress thermal decomposition and yellowing due to oxidation of the molten resin, it is preferable to purge or vacuum the inside of the hopper, the extruder cylinder, etc. with an inert gas such as nitrogen or argon.

  Typical examples of the melt extruder according to the present invention include a single-screw extruder, a co-rotating twin-screw extruder, a counter-rotating twin-screw extruder, a tandem extruder, and the like. From the viewpoint of characteristics and optical characteristics, it is preferable to use a single screw extruder. If the amorphous thermoplastic resin used, additives, etc. contain volatile components such as water, the film appearance deteriorates when the optical film is extruded, so these extruders are used to remove volatile components. What was equipped with the vacuum vent, the hopper dryer, etc. is used suitably. In addition, the cylinder diameter, L / D, compression ratio, and screw design should generally be optimized according to the production speed, film dimensions, etc., especially when manufacturing optical films, to stabilize the discharge speed. At the same time, it may be optimized for the purpose of suppressing heat generation from friction and maintaining the resin temperature below the decomposition temperature.

  The temperature of the melt at the time of melt extrusion is usually in the range of 150 to 300 ° C, preferably in the range of 180 to 270 ° C, more preferably in the range of 200 to 250 ° C. The temperature of the melt is a value measured using a contact thermometer.

  In the heat setting, heat setting is usually performed for 0.5 to 300 seconds at a temperature higher than the final transverse stretching temperature and within a temperature range of Tg-20 ° C or lower. At this time, it is preferable to heat-fix while sequentially raising the temperature difference in the range of 1 to 100 ° C. in the region divided into two or more.

  The heat-set film is usually cooled to Tg or less and wound. At this time, it is preferable to perform a relaxation treatment of 0.1 to 10% in the horizontal direction and / or the vertical direction within the temperature range of the final heat setting temperature or lower and Tg or higher. Further, the cooling is preferably performed by gradually cooling from the final heat setting temperature to Tg at a cooling rate of 100 ° C. or less per second. Means for cooling and relaxation treatment are not particularly limited, and can be performed by a conventionally known means. In particular, it is preferable to carry out these treatments while sequentially cooling in a plurality of temperature ranges from the viewpoint of improving the dimensional stability of the film.

  The cooling rate is a value obtained by (T1-Tg) / t, where T1 is the final heat setting temperature and t is the time until the film reaches Tg from the final heat setting temperature.

  The more optimal conditions of these heat setting conditions, cooling, and relaxation treatment conditions vary depending on the amorphous thermoplastic resin used, so the physical properties of the obtained biaxially stretched film are measured and adjusted appropriately to have desirable characteristics. To do so.

  In the present invention, when the width of the optical film to be manufactured is changed by the melt casting film forming method shown in this figure, the width of the transport roll in the heat fixing device 703a in the heat treatment step 703 and the cooling device 704a in the recovery step 704 is set. The present invention relates to a method for producing an optical film that does not cause scratches associated with roll slippage even when transported at high speed without being changed.

  FIG. 3 is an enlarged schematic perspective view of a portion indicated by P in FIG.

  In the figure, 6a indicates one end of the cellulose ester film 5, and 6b indicates the other end. Reference numeral 303f1 denotes a conveyance auxiliary portion disposed on the circumferential surface in the width direction near the end of the conveyance roll 303f. Reference numeral 303f2 denotes a conveyance auxiliary unit disposed on the circumferential surface in the width direction near the opposite end of the conveyance roll 303f. The conveyance auxiliary part should just be arrange | positioned at the circumferential surface of the width direction of at least one edge part vicinity. In the case where the conveyance auxiliary unit as shown in this figure is FIG. 1A, the conveyance roll 303d (303e) in the drying step 303 is used, and in the case of FIG. 1B, the conveyance roll 305d (305e) in the first drying step 305 is performed. In the case of FIG. 1C, the transport roll 305d (305e) of the first drying step 305 and the transport roll 307d (307e) of the second drying step 307 are used as the transport roll 306d (306e) of the second drying step 306. In addition, in the case of FIG. 1D, it is provided on the transport roll 308d (308e) of the drying step 308, and in the case of FIG. 2, the transport roll 703a4 of the heat fixing device 703a and the transport roll 704a4 of the cooling device 704a.

  This figure has shown the case where the one edge part 6a of the cellulose-ester film 6 is contacting the conveyance auxiliary | assistance part 303f1 of the conveyance roll 303f, and is conveying (arrow direction in a figure). Of course, you may make it the one edge part 6b of the cellulose-ester film 6 contact the conveyance auxiliary | assistant part 303f2 of the conveyance roll 303f, and you may make it convey (arrow direction in a figure). Conveying one end of the web of the present invention (cellulose ester film in this figure) and the conveyance auxiliary part means the state shown in this figure. In addition, the edge part which contacts the conveyance auxiliary | assistant part of a conveyance roll means the part about 1 to 20% of web full width toward the width direction from the edge side of a web (cellulose ester film of this figure).

  The transport speed when transporting the cellulose ester film in the state shown in this figure takes into account the air entrainment during casting, the residual solvent amount of the web when peeling from the endless support, the residual solvent amount of the stretched part, etc. 30 m / min to 150 m / min is preferable. The conveyance speed is calculated by using the pulse generator attached to the motor shaft of the drive motor arranged in the conveyance process and calculating the rotation speed using the roll diameter coupled to the motor / the reduction ratio between the motor and the roll. Indicates the obtained value.

  FIG. 4 is an enlarged schematic plan view of a conveyance auxiliary portion of the conveyance roll shown in FIG.

  In the figure, E indicates the distance from the end 303f3 of the transport roll 303f to the transport auxiliary section 303f2. The distance E is preferably 100 mm or less in consideration of the width of the web being conveyed, the amount of meandering of the web being conveyed, and the like. F indicates the width of the conveyance auxiliary portion 303f2. The width F is preferably 30 mm to 150 mm in consideration of the width of the product film, roll slip, and the like. In addition, the conveyance auxiliary | assistant part 303f1 of the conveyance roll 303f shown in FIG. 3 may be arrange | positioned at the same distance from the edge part of the conveyance roll 303f with the same width | variety as the conveyance auxiliary | assistant part 303f2. In the present invention, the vicinity of the end of the transport roll refers to a range including the distance E and the distance F.

  The arrangement position and width of the conveyance auxiliary unit shown in this figure are the same as the conveyance roll 303d (303e) in the drying step 303 shown in FIG. 1A and the conveyance in the first drying step 305 shown in FIG. The roll 305d (305e), the transport roll 306d (306e) of the second drying step 306, the transport roll 305d (305e) of the first drying step 305 and the transport of the second drying step 307 shown in FIG. Applied to the roll 307d (307e), the transport roll 308d (308e) of the drying step 308 shown in FIG. 1D, the transport roll 703a4 of the heat fixing device 703a shown in FIG. 2, and the transport roll 704a4 of the cooling device 704a. Is done.

  FIG. 5 is a schematic view of a conveyance auxiliary unit having a different form of the conveyance roll. FIG. 5A is a schematic perspective view of a transport roll in which the transport auxiliary portion is formed with a rough surface. FIG. 5 (a ′) is an enlarged schematic cross-sectional view along AA ′ of FIG. 5 (a). FIG. 5B is a schematic perspective view of a transport roll in which the transport auxiliary portion is formed with a convex portion. FIG. 5B 'is an enlarged schematic cross-sectional view along the line BB' in FIG. 5B. FIG. 5C is a schematic perspective view of a conveyance roll in which the conveyance auxiliary portion is formed by a plurality of convex portions. FIG. 5C ′ is an enlarged schematic cross-sectional view along CC ′ of FIG. FIG. 5D is a schematic perspective view of a conveyance roll in which the conveyance auxiliary portion is formed by a plurality of concave portions. FIG. 5 (d ′) is an enlarged schematic cross-sectional view along the line DD ′ in FIG. 4 (d).

  A description will be given with reference to the transport roll shown in FIG. Reference numeral 303f21 denotes a rough-surfaced conveyance auxiliary unit. The surface roughness Ra of the conveyance auxiliary portion 303f21 is preferably 1 μm to 100 μm in consideration of the web conveyance speed, the roll diameter, the wrap angle between the web and the roll, the conveyance tension, and the like. The surface roughness Ra is a value measured according to JIS B 0601-2001.

  A description will be given of the transport roll shown in FIG. Reference numeral 303f22 denotes a conveyance auxiliary portion having a convex shape. G shows the height from the surface of the conveyance roll 303f of the conveyance assistance part of a convex part shape. The height G is preferably 10 mm to 500 mm in consideration of the web conveyance speed, roll diameter, wrap angle between the web and roll, conveyance tension, and the like. The height G is a value measured by a general micrometer or a surface roughness measuring device (for example, a small surface roughness measuring device Surf Test SJ-400 manufactured by Mitutoyo Corporation). In addition, formation of a convex part may be processed simultaneously when producing a conveyance roll, and you may stick a tape.

  A description will be given of the transport roll shown in FIG. Reference numeral 303f23 denotes a conveyance auxiliary portion formed with a plurality of convex portions. The height of the convex shape is the same as the height of 303f22 of the convex conveyance auxiliary portion of the conveyance roll shown in FIG. The number of the convex shape is not particularly limited, and is preferably set as appropriate according to the type of the cellulose ester film to be conveyed.

  A description will be given of the transport roll shown in FIG. Reference numeral 303f23 denotes a conveyance auxiliary portion formed in a plurality of concave shapes (groove shapes). H indicates the depth of the concave shape (groove shape). The depth H is preferably 0.01 to 1 mm in consideration of the web conveyance speed, the roll diameter, the wrap angle between the web and the roll, the conveyance tension, and the like. The number of the concave shape (groove shape) is not particularly limited, and is preferably set as appropriate according to the type of the cellulose ester film to be conveyed. The depth of the concave shape (groove shape) indicates a value measured by a general micrometer or a surface roughness measuring device (for example, a small surface roughness measuring device manufactured by Mitutoyo Corporation Surf Test SJ-400). In addition, although this figure has shown the case where it arrange | positions along a surrounding surface, you may arrange | position along an axial direction. In addition to the shape shown in the figure, the shape of the conveyance auxiliary portion can also be a diamond-shaped knurled / mesh shape (honeycomb shape, round hole punch plate shape), other irregular shapes, or a combination thereof. .

  If the surface roughness and the convex / concave portions are too small, sufficient frictional force between the web and the roll cannot be obtained, and roll slip occurs. On the other hand, if it is too large, the frictional force is too great and the web being conveyed is wrinkled.

The following effects can be obtained by disposing the conveyance auxiliary portion having the shape shown in FIGS. 5A to 5D near the end of the conveyance roll.
1) A sufficient frictional force can be obtained by contacting only one side of the conveyance auxiliary part of the cellulose ester film and the conveyance roll, and conveyance can be performed without causing roll slippage during conveyance (conveyance speed 40 m / min to 150 m / min). It became possible, and width correspondence became easy.
2) Since there was no roll slip, no scratches occurred, the yield rate increased, and production efficiency was improved.

  FIG. 6 is a schematic view showing a method of conveying a cellulose ester film in the state shown in FIG. 3 by the solution casting film forming apparatus shown in FIG. FIG. 6A shows that when casting a dope on a belt in a casting process, a cellulose ester film is formed on the endless belt so that one end of the dope matches the position of the conveyance auxiliary portion of the conveyance roll. It is a schematic diagram which shows a method. FIG. 6B is a schematic diagram showing a method for changing the width conveyance position of the web with respect to the conveyance roll by changing the traveling angle of the web conveyed when the predetermined residual solvent is reached after the end of the casting process. FIG. FIG. 6C is an enlarged schematic view of a portion indicated by Q in FIG.

This will be described with reference to the schematic diagram shown in FIG. This figure has shown the method of conveying a cellulose-ester film in the state shown in FIG. 2 after completion | finish of an extending | stretching process with the solution casting film forming apparatus shown by Fig.1 (a). In this figure, the drying box 303a (see FIG. 1A) is omitted. In the method shown in FIG. 5A, one of the end portions 6a (6b) of the cellulose ester film 6 formed on the belt 301a at the time of casting is formed in the vicinity of the end portions of the transport rollers 303f and 303d. In this method, the dope 4 is cast and conveyed from the die 301b to the belt 301a of the casting process 301 so as to come into contact with either one of the conveyance auxiliary portions. In the case of the melt casting film forming apparatus shown in FIG. 2, the method of conveying the cellulose ester film shown in this figure is when the molten film is extruded from the T die between the cooling rolls, and one of the ends is a heat treatment step. The cellulose ester film can be transported in the state shown in the figure by matching with the position of the transport auxiliary portion of the transport roll. The effects obtained by the method shown in FIG.
1) Even if the width is narrow, one end of the optical film and the conveyance auxiliary part on one side of the conveyance roll are in contact and conveyed, so there is no generation of scratches due to roll sliding, and it can be used for optical films of all widths. Became possible.
2) Manufacture because any width can be handled by changing only the position of the die according to the width of the cellulose ester film to be manufactured using a solution casting film forming apparatus that matches the maximum width. Costs can be reduced.
3) Using a solution casting film forming apparatus matched to the maximum width, it becomes possible to produce a cellulose ester film having a narrow width without lowering the production efficiency without lowering the conveying speed.

  This will be described with reference to the schematic diagram shown in FIG. This figure shows a method of transporting the cellulose ester film in the state shown in FIG. 3 by changing the transport angle in the transport angle changing step after completion of the stretching step in the solution casting film forming apparatus shown in FIG. In this figure, the drying box 303a (see FIG. 1A) is omitted. In the method shown in FIG. 6B, the cellulose ester film 6 formed on the belt 301a at the end of the stretching process is such that the center line of the belt 301a and the center of the cellulose ester film 6 substantially coincide with each other regardless of the width. Formed, and then peeled off from the belt, and formed at the vicinity of the ends of the transport rolls 303f and 303d by the transport direction angle change roll 303g disposed in the transport angle change process when the process in the stretching process is completed. In this method, the traveling angle is changed so as to come into contact with either one of the conveyance auxiliary portions. The number of rolls 303g for changing the conveyance direction angle is usually one set of two, and when it is desired to increase the angle in the conveyance direction, the interval between the two roll angle changing rolls 303g is increased or the angle of the conveyance direction is changed. It is possible to increase the number of sets of rolls 303g as necessary. For example, in the schematic diagram shown in FIG. 6B, when a cellulose ester film having a width of 900 mm is conveyed with respect to a conveyance roll having a maximum width set to 1500 mm, the conveyance auxiliary portion of the conveyance roll 303 f and the cellulose ester It is preferable to arrange a plurality of conveyance direction angle changing rolls 303g before contacting the end portion of the film and convey the film without abruptly changing the angle. For changing the angle of the conveyance direction angle changing roll 303g, for example, the angle may be determined in advance and disposed on the gantry, or installed on the gantry where the angle can be changed, and the gantry is moved by, for example, a servo motor or manually. It is possible to select as needed.

  In the case of this figure, the case where a running angle is changed so that the conveyance auxiliary | assistant part above a conveyance roll may be contacted is shown. θ represents an angle formed between the web conveyance direction and the direction perpendicular to the roll axis of the conveyance direction angle changing roll 303g. The angle θ is preferably 0.3 ° to 3 ° in consideration of the physical property distribution in the width direction (particularly, the distribution of the direction of the optical slow axis), the generation of wrinkles, the size of the equipment, the production efficiency, and the like. The angle θ of the conveyance direction angle changing roll 303g can be measured with a combination of a metal ruler or a dial gauge when the conveyance direction angle changing roll 303g is fixed. Further, when it is installed on a gantry whose angle can be changed, it can be obtained by calculation using, for example, the value of the rotation angle encoder in the servo motor.

In the case of the melt casting film forming apparatus shown in FIG. 2, a conveyance angle changing step is provided between the stretching step and the heat treatment step, and the number of sets of conveyance direction angle changing rolls is arranged as necessary. It becomes possible to convey a cellulose-ester film in a state. The effects obtained by the method shown in FIG.
1) Even if the width is narrow, one end of the optical film and the conveyance auxiliary part on one side of the conveyance roll are in contact and conveyed, so there is no generation of scratches due to roll sliding, and it can be used for optical films of all widths. Became possible.
2) Using a solution casting film forming apparatus matched to the maximum width, it is possible to cope with any width by simply installing a transport direction angle changing roll.
3) Using a solution casting film forming apparatus matched to the maximum width, it becomes possible to produce a cellulose ester film having a narrow width without lowering the production efficiency without lowering the conveying speed.
4) Since it is possible to cope with the width with one solution casting film forming apparatus in accordance with the maximum width, it is possible to reduce the manufacturing cost.

As shown in FIG. 1 to FIG. 6, at least one end portion of the optical film using a solution casting film forming apparatus using a transport roll having a transport auxiliary portion on the circumferential surface in the width direction near at least one end portion. The following effects can be obtained by manufacturing the product by bringing the transport auxiliary unit into contact with the transport.
1. Even if the width is narrow, one end of the optical film and the conveyance auxiliary part on one side of the conveyance roll are in contact with each other, so there is no scratch due to roll slipping and it can be applied to optical films of any width. It became.
2. Using a solution casting film-forming device designed for the maximum width optical film to be manufactured, it is possible to manufacture an optical film with a narrow width without lowering the transport speed, which can improve production efficiency. became.
3. Since only the part that contacts the conveyance auxiliary part on one side of the conveyance roll is excised, the product yield can be improved.
4). The width of the optical film to be produced can be easily dealt with, and on-demand production becomes possible, enabling quick response to demands.

  The resin used for the optical film according to the present invention will be described below. As the resin used for the optical film, a transparent resin having excellent physical and mechanical properties and a small dimensional change with respect to temperature and humidity is used. For example, a cellulose resin, a polycarbonate resin, a polyarylate resin, a polysulfone resin, Examples include polyethersulfone resin, norbornene resin, polystyrene resin, polyacrylate resin, polyester resin and the like. Among these resins, cellulose ester resins are particularly preferably used. Hereinafter, the cellulose ester resin will be described.

  The cellulose ester resin used in the production of the film of the present invention is preferably a lower fatty acid ester resin of cellulose. The lower fatty acid in the lower fatty acid ester of cellulose is preferably a fatty acid having 6 or less carbon atoms. For example, cellulose acetate, cellulose propionate, cellulose butyrate and the like are particularly preferred examples of the lower fatty acid ester of cellulose.

  In addition to the above, cellulose acetate propionate, cellulose acetate butyrate, cellulose acetate propionate buty described in JP-A Nos. 10-45804, 8-231761, U.S. Pat. No. 2,319,052 and the like. Mixed fatty acid esters such as rate can be used. Among the above description, cellulose triacetate (hereinafter referred to as TAC) and cellulose acetate propionate are the most preferably used lower fatty acid esters of cellulose.

  The number average molecular weight of the cellulose ester according to the present invention is preferably 70,000 to 250,000, which has a high mechanical strength when molded and has an appropriate dope viscosity, and more preferably 80,000 to 150,000. is there.

  The cellulose ester used in the present invention has an acetyl group and / or propionyl group as a substituent, and when the substitution degree of the acetyl group is X and the substitution degree of the propionyl group is Y, the following formula (I) and Cellulose esters that simultaneously satisfy (II) are preferred.

(I) 2.3 ≦ X + Y ≦ 3.0
(II) 0 ≦ X ≦ 2.5
In particular, a cellulose ester that simultaneously satisfies the following formulas (III) and (IV) (V) is particularly preferable.

(III) 2.3 ≦ X + Y ≦ 2.85
(IV) 1.5 ≦ X ≦ 2.5
(V) 0.1 ≦ Y ≦ 1.0
The measuring method of the substitution degree of an acyl group can be measured according to the provisions of ASTM-D817-96.

  Until now, when cellulose ester having a degree of substitution of less than 2.85 was used, the dimensional stability was sometimes lowered, but it was excellent even when a cellulose ester having a low degree of substitution was used by applying the production method of the present invention. It became possible to obtain a film having dimensional stability.

  As the cellulose ester, either a cellulose ester synthesized from a cotton linter or a cellulose ester synthesized from wood pulp can be used alone or in combination. If peelability from the support or drum becomes a problem, it is preferable to use a large amount of cellulose ester synthesized from a cotton linter that has good peelability from the support or drum. When cellulose ester synthesized from wood pulp is mixed and used, the ratio of cellulose ester synthesized from cotton linter is preferably 40% by mass or more, and the effect of releasability becomes remarkable, and more preferably 60% by mass or more. Most preferably, it is used alone.

  The solvent used in preparing the dope may be any solvent that can dissolve the cellulose ester, and it can be dissolved by mixing with other solvents even if it cannot be dissolved alone. Can be used. In general, a mixed solvent composed of a poor solvent of methylene chloride and cellulose ester, which is a good solvent, is used, and the mixed solvent preferably contains 4 to 30% by mass of the poor solvent.

  In addition, examples of good solvents that can be used include methylene chloride, methyl acetate, ethyl acetate, amyl acetate, acetone, tetrahydrofuran, 1,3-dioxolane, 1,4-dioxane, cyclohexanone, ethyl formate, 2,2,2- Trifluoroethanol, 2,2,3,3-hexafluoro-1-propanol, 1,3-difluoro-2-propanol, 1,1,1,3,3,3-hexafluoro-2-methyl-2- Examples include propanol, 1,1,1,3,3,3-hexafluoro-2-propanol, 2,2,3,3,3-pentafluoro-1-propanol, nitroethane, and the like, such as methylene chloride. Preferred organic solvents (ie, good organic solvents such as dioxolane derivatives, methyl acetate, ethyl acetate, acetone) And the like as a medium).

  Examples of the poor solvent for cellulose ester include alcohols having 1 to 8 carbon atoms such as methanol, ethanol, n-propanol, iso-propanol, n-butanol, sec-butanol, tert-butanol, methyl ethyl ketone, methyl isobutyl ketone, and acetic acid. Examples thereof include propyl, monochlorobenzene, benzene, cyclohexane, tetrahydrofuran, methyl cellosolve, and ethylene glycol monomethyl ether. These poor solvents can be used alone or in combination of two or more.

  Although it does not specifically limit as a plasticizer which can be used by this invention, A phosphate ester plasticizer, a phthalate ester plasticizer, a trimellitic ester plasticizer, a pyromellitic acid plasticizer, a glycolate plasticizer Citric acid ester plasticizers, polyester plasticizers and the like can be preferably used.

  For phosphate esters, triphenyl phosphate, tricresyl phosphate, cresyl diphenyl phosphate, octyl diphenyl phosphate, diphenyl biphenyl phosphate, trioctyl phosphate, tributyl phosphate, etc. For phthalate esters, diethyl phthalate, dimethoxyethyl phthalate, dimethyl Trimellitic plasticizers such as phthalate, dioctyl phthalate, dibutyl phthalate, di-2-ethylhexyl phthalate, butyl benzyl phthalate, etc. Tributyl trimellitate, triphenyl trimellitate, triethyl trimellitate, pyromellitic ester Examples of plasticizers include tetrabutyl pyromellitate, tetraphenyl pyromellitate, tetraethyl pyromellitate, In acid ester type, triacetin, tributyrin, ethyl phthalyl ethyl glycolate, methyl phthalyl ethyl glycolate, butyl phthalyl butyl glycolate, etc., citrate ester plasticizers such as triethyl citrate, tri-n-butyl citrate Acetyl triethyl citrate, acetyl tri-n-butyl citrate, acetyl tri-n- (2-ethylhexyl) citrate and the like can be preferably used. As the polyester plasticizer, a copolymer of a dibasic acid such as an aliphatic dibasic acid, an alicyclic dibasic acid, or an aromatic dibasic acid and a glycol can be used. The aliphatic dibasic acid is not particularly limited, and adipic acid, sebacic acid, phthalic acid, terephthalic acid, 1,4-cyclohexyl dicarboxylic acid and the like can be used.

  As the glycol, ethylene glycol, diethylene glycol, 1,3-propylene glycol, 1,2-propylene glycol, 1,4-butylene glycol, 1,3-butylene glycol, 1,2-butylene glycol and the like can be used. These dibasic acids and glycols may be used alone or in combination of two or more. The molecular weight of the polyester is preferably in the range of 500 to 2000 in terms of weight average molecular weight from the viewpoint of compatibility with the cellulose ester.

  In the present invention, it is particularly preferable to use a plasticizer having a vapor pressure of less than 1333 Pa at 200 ° C., more preferably a compound having a vapor pressure of 666 Pa or less, and more preferably 1 to 133 Pa. The non-volatile plasticizer is not particularly limited, and examples thereof include arylene bis (diaryl phosphate) ester, tricresyl phosphate, trimellitic acid tri (2-ethylhexyl), and the above polyester plasticizer. These plasticizers can be used alone or in combination of two or more.

  In consideration of dimensional stability and processability, the amount of the plasticizer used can be added in an amount of 1 to 40% by weight, preferably 3 to 20% by weight, based on the cellulose ester. Preferably it is 4-15 mass%. If the amount is less than 3% by mass, a smooth cut surface cannot be obtained when slitting or punching, resulting in increased generation of chips.

  It is preferable to add an antioxidant or an ultraviolet absorber to the film of the present invention. As the antioxidant, a hindered phenol compound is preferably used, and 2,6-di-t-butyl-p-cresol, pentaerythrityl-tetrakis [3- (3,5-di-t-butyl). -4-hydroxyphenyl) propionate], triethylene glycol-bis [3- (3-tert-butyl-5-methyl-4-hydroxyphenyl) propionate], 1,6-hexanediol-bis [3- (3 5-di-t-butyl-4-hydroxyphenyl) propionate], 2,4-bis- (n-octylthio) -6- (4-hydroxy-3,5-di-t-butylanilino) -1,3 5-triazine, 2,2-thio-diethylenebis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], octadecyl-3- ( , 5-di-t-butyl-4-hydroxyphenyl) propionate, N, N′-hexamethylenebis (3,5-di-t-butyl-4-hydroxy-hydrocinnamamide), 1,3,5 -Trimethyl-2,4,6-tris (3,5-di-t-butyl-4-hydroxybenzyl) benzene, tris- (3,5-di-t-butyl-4-hydroxybenzyl) -isocyanurate Etc. In particular, 2,6-di-t-butyl-p-cresol, pentaerythrityl-tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], triethylene glycol-bis [3- (3-t-butyl-5-methyl-4-hydroxyphenyl) propionate] is preferred. Further, for example, hydrazine-based metal deactivators such as N, N′-bis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyl] hydrazine and tris (2,4-di-t A phosphorus-based processing stabilizer such as -butylphenyl) phosphite may be used in combination. The amount of these compounds added is preferably 1 ppm to 1.0%, more preferably 10 to 1000 ppm in terms of mass ratio with respect to the cellulose ester.

  In addition, heat stabilizers such as kaolin, talc, diatomaceous earth, quartz, calcium carbonate, barium sulfate, titanium oxide, alumina, and other inorganic fine particles, and alkaline earth metal salts such as calcium and magnesium may be added. .

  The optical film manufactured by the manufacturing method of the present invention can be used for a polarizing plate or a liquid crystal display member because of its high dimensional stability, and in this case, for preventing deterioration of the polarizing plate or the liquid crystal. An ultraviolet absorber is preferably used.

  As the ultraviolet absorber, those excellent in the ability to absorb ultraviolet rays having a wavelength of 370 nm or less and having little absorption of visible light having a wavelength of 400 nm or more are preferably used from the viewpoint of good liquid crystal display properties. Specifically, the transmittance at 380 nm is preferably less than 10%, more preferably less than 5%.

  Specific examples of ultraviolet absorbers preferably used include oxybenzophenone compounds, benzotriazole compounds, salicylic acid ester compounds, benzophenone compounds, cyanoacrylate compounds, nickel complex compounds, triazine compounds, and the like. For example, the ultraviolet absorbers described in JP-A-10-182621 and JP-A-8-337574 are preferably used. Moreover, the polymeric ultraviolet absorbers described in JP-A-6-148430 and JP-A-12-273437 are also preferably used. Or you may add the ultraviolet absorber described in Unexamined-Japanese-Patent No. 10-152568.

  Among these ultraviolet absorbers, benzotriazole ultraviolet absorbers and benzophenone ultraviolet absorbers are preferable ultraviolet absorbers. Although the specific example of a benzotriazole type ultraviolet absorber is given to the following, this invention is not limited to these.

2- (2'-hydroxy-5'-methylphenyl) benzotriazole, 2- (2'-hydroxy-3 ', 5'-di-tert-butylphenyl) benzotriazole, 2- (2'-hydroxy-3) '-Tert-butyl-5'-methylphenyl) benzotriazole, 2- (2'-hydroxy-3', 5'-di-tert-butylphenyl) -5-chlorobenzotriazole, 2- (2'-hydroxy -3 '-(3 ", 4", 5 ", 6" -tetrahydrophthalimidomethyl) -5'-methylphenyl) benzotriazole, 2,2-methylenebis (4- (1,1,3,3-tetramethyl) Butyl) -6- (2H-benzotriazol-2-yl) phenol), 2- (2'-hydroxy-3'-tert-butyl-5'-methylphenyl)- -Chlorobenzotriazole, 2- (2H-benzotriazol-2-yl) -6- (linear and side chain dodecyl) -4-methylphenol (TINUVIN171, manufactured by Ciba Specialty Chemicals), octyl-3- [ 3-tert-butyl-4-hydroxy-5- (chloro-2H-benzotriazol-2-yl) phenyl] propionate and 2-ethylhexyl-3- [3-tert-butyl-4-hydroxy-5- (5- Chloro-2H-benzotriazol-2-yl) phenyl] propionate (TINUVIN109, manufactured by Ciba Specialty Chemicals)
Specific examples of the benzophenone-based ultraviolet absorber are shown below, but the present invention is not limited thereto. 2,4-dihydroxybenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone, 2-hydroxy-4-methoxy-5-sulfobenzophenone, bis (2-methoxy-4-hydroxy-5-benzoylphenylmethane)
The ultraviolet absorber may be added by dissolving the ultraviolet absorber in an organic solvent such as alcohol, methylene chloride, dioxolane and the like, or adding it directly to the dope composition. For an inorganic powder that does not dissolve in an organic solvent, it is preferable to use a dissolver or a sand mill in the organic solvent and the cellulose ester resin to disperse and then add to the dope. The amount of the ultraviolet absorber used is preferably 0.1% by mass to 2.5% by mass in consideration of the effect as an ultraviolet absorber, transparency, and the like. Furthermore, Preferably, it is 0.8 mass%-2.0 mass%.

  In addition, fine particles as a matting agent may be added to the cellulose ester-based resin film in order to prevent the films from sticking to each other or to impart slipperiness to facilitate handling. The fine particles include inorganic compound fine particles and organic compound fine particles. Inorganic compounds include silicon-containing compounds, silicon dioxide, aluminum oxide, zirconium oxide, calcium carbonate, talc, clay, calcined kaolin, calcined calcium silicate, hydrated calcium silicate, aluminum silicate, magnesium silicate, calcium phosphate, etc. More preferred is an inorganic compound containing silicon or zirconium oxide, but silicon dioxide is particularly preferably used since the turbidity of the cellulose ester laminated film can be reduced.

  As fine particles of silicon dioxide, for example, AEROSIL-200, 200V, 300, R972, R972V, R974, R976, R976S, R202, R812, R805, OX50, TT600, RY50, RX50, NY50, NAX50, NA50H manufactured by Aerosil Co., Ltd. NA50Y, NX90, RY200S, RY200, RX200, R8200, RA200H, RA200HS, NA200Y, R816, R104, RY300, RX300, R106, and the like. Among these, AEROSIL-200V and R972V are preferable in terms of controlling dispersibility and particle size.

  As the fine particles of zirconium oxide, commercially available products such as Aerosil R976 and R811 (manufactured by Nippon Aerosil Co., Ltd.) can be used.

  As the organic compound, for example, polymers such as silicone resin, fluorine resin and acrylic resin are preferable, and among them, silicone resin is preferably used.

  Among the above-described silicone resins, those having a three-dimensional network structure are particularly preferable. For example, Tospearl 103, 105, 108, 120, 145, 3120 and 240 (above Toshiba Silicone Co., Ltd.) ) Etc. can be used.

  The primary average particle size of the fine particles according to the present invention is preferably 20 nm or less, more preferably 5 to 16 nm, and particularly preferably 5 to 12 nm, from the viewpoint of keeping the haze low.

  The apparent specific gravity of the fine particles is preferably 70 g / liter or more, more preferably 90 to 200 g / liter, and particularly preferably 100 to 200 g / liter. Larger apparent specific gravity makes it possible to make a high-concentration dispersion, which improves haze and agglomerates, and is preferable when preparing a dope having a high solid content concentration as in the present invention. Are particularly preferably used.

  Silicon dioxide fine particles having an average primary particle diameter of 20 nm or less and an apparent specific gravity of 70 g / liter or more are, for example, a mixture of vaporized silicon tetrachloride and hydrogen burned in air at 1000 to 1200 ° C. Can be obtained. Further, for example, Aerosil 200V and Aerosil R972V (manufactured by Nippon Aerosil Co., Ltd.) are commercially available, and these can be used.

  The apparent specific gravity was calculated by the following equation by measuring a weight of silicon dioxide fine particles in a graduated cylinder and measuring the weight at that time.

Apparent specific gravity (g / liter) = Mass of silicon dioxide (g) ÷ Volume of silicon dioxide (liter)
Examples of the method for preparing a dispersion of fine particles according to the present invention include the following three types.

<< Preparation Method A >>
After stirring and mixing the solvent and the fine particles, dispersion is performed with a disperser. This is a fine particle dispersion. The fine particle dispersion is added to the dope solution and stirred.

<< Preparation Method B >>
After stirring and mixing the solvent and the fine particles, dispersion is performed with a disperser. This is a fine particle dispersion. Separately, a small amount of cellulose ester is added to the solvent and dissolved by stirring. As the cellulose ester added here, it is particularly preferable to add the solid material of the present invention.

  The fine particle dispersion is added to this and stirred. This is a fine particle addition solution. The fine particle additive solution is sufficiently mixed with the dope solution using an in-line mixer.

<< Preparation Method C >>
Add a small amount of cellulose ester to the solvent and dissolve with stirring. Fine particles are added to this and dispersed by a disperser. This is a fine particle addition solution. The fine particle additive solution is sufficiently mixed with the dope solution using an in-line mixer.

  Preparation method A is excellent in dispersibility of silicon dioxide fine particles, and preparation method C is excellent in that silicon dioxide fine particles are difficult to re-aggregate. Among them, the preparation method B described above is a preferable preparation method that is excellent in both dispersibility of the silicon dioxide fine particles and that the silicon dioxide fine particles are less likely to reaggregate.

《Distribution method》
The concentration of silicon dioxide when the silicon dioxide fine particles are mixed with a solvent and dispersed is preferably 5 to 30% by mass, more preferably 10 to 25% by mass, and most preferably 15 to 20% by mass. A higher dispersion concentration is preferable because liquid turbidity with respect to the added amount tends to be low, and haze and aggregates are improved.

  The solvent used is preferably lower alcohols such as methyl alcohol, ethyl alcohol, propyl alcohol, isopropyl alcohol, butyl alcohol and the like. Although it does not specifically limit as solvents other than a lower alcohol, It is preferable to use the solvent used at the time of film forming of a cellulose ester.

  The amount of silicon dioxide fine particles added to cellulose ester is preferably 0.01 to 0.3 parts by mass, more preferably 0.05 to 0.2 parts by mass, and more preferably 0.0 to 0.2 parts by mass with respect to 100 parts by mass of cellulose ester. Most preferred is 08 to 0.12 parts by mass. The larger the added amount, the better the dynamic friction coefficient, and the smaller the added amount, the lower the haze and the fewer agglomerates.

  As the disperser, a normal disperser can be used. Dispersers can be broadly divided into media dispersers and medialess dispersers. For dispersing silicon dioxide fine particles, a medialess disperser is preferred because of its low haze.

  Examples of the media disperser include a ball mill, a sand mill, and a dyno mill.

  Examples of the medialess disperser include an ultrasonic type, a centrifugal type, and a high pressure type. In the present invention, a high pressure disperser is preferable. The high pressure dispersion device is a device that creates special conditions such as high shear and high pressure by passing a composition in which fine particles and a solvent are mixed at high speed through a narrow tube. When processing with a high-pressure dispersion apparatus, for example, the maximum pressure condition inside the apparatus is preferably 9.807 MPa or more in a thin tube having a tube diameter of 1 to 2000 μm. More preferably, it is 19.613 MPa or more. Further, at that time, those having a maximum reaching speed of 100 m / second or more and those having a heat transfer speed of 420 kJ / hour or more are preferable.

  The high-pressure dispersion apparatus as described above includes an ultra-high pressure homogenizer (trade name: Microfluidizer) manufactured by Microfluidics Corporation or a nanomizer manufactured by Nanomizer. Examples include UHN-01 manufactured by Wako Machine Co., Ltd.

  These fine particles may be uniformly distributed in the thickness direction of the film, but it is more preferable that they are mainly distributed so as to exist mainly in the vicinity of the surface. It is preferable to add fine particles mainly to the dope arranged on the surface layer side using a dope of a seed or more because a film having high slip properties and low haze can be obtained. It is preferable to add fine particles mainly to two dopes on the surface layer side using three kinds of dopes.

  Moreover, the optical film which has preferable impedance can also be obtained by adding the substance which has electroconductivity to the film of this invention. Although it does not specifically limit as an electroconductive substance, The antistatic agent etc. which have compatibility with an ionic electroconductive substance, electroconductive fine particles, or a cellulose ester can be used.

  Here, the ion conductive substance is a substance that shows electric conductivity and contains ions that are carriers for carrying electricity, and examples thereof include ionic polymer compounds.

  Examples of the ionic polymer compound include anionic polymer compounds such as those described in JP-B-49-23828, JP-A-49-23827, and JP-A-47-28937, such as JP-B-55-734, JP-A-50- An ionene type polymer having a dissociating group in the main chain, as shown in No. 54672, JP-B-59-14735, JP-A-57-18175, JP-A-57-18176, JP-A-57-56059, etc. No. 13223, No. 57-15376, No. Sho 53-45231, No. 55-145578, No. 55-65950, No. 55-67746, No. 57-11342, No. 57-19735, No. Sho-58- Cationic penders having a cationic dissociation group in the side chain, as seen in Japanese Patent No. 56858, Japanese Patent Application Laid-Open Nos. Sho 61-27853 and 62-9346 It can be mentioned door type polymers, and the like.

Examples of the conductive fine particles include conductive metal oxides. As an example of the metal oxide, ZnO, TiO ₂ , SnO ₂ , Al ₂ O ₃ , In ₂ O ₃ , SiO ₂ , MgO, BaO, MoO ₂ , V ₂ O ₅ , or a composite oxide thereof is preferable. In particular, ZnO, TiO ₂ and SnO ₂ are preferred. Examples of containing different atoms include, for example, addition of Al, In, etc. to ZnO, addition of Nb, Ta, etc. to TiO ₂ , and addition of Sb, Nb, halogen elements, etc. to SnO ₂ . Addition is effective. The amount of these different atoms added is preferably in the range of 0.01 to 25 mol%, particularly preferably in the range of 0.1 to 15 mol%.

Further, the volume resistivity of these conductive metal oxide powders is 10 ⁷ Ωcm or less, particularly 10 ⁵ Ωcm or less, the primary particle diameter is 10 nm or more and 0.2 μm or less, and the major structure has a long diameter. It is preferable that a powder having a specific structure of 30 nm or more and 6 μm or less contains 0.01% or more and 20% or less in volume fraction in at least a part of the region of the film.

  It is particularly preferable to contain an ionene conductive polymer described in JP-A-9-203810 or a quaternary ammonium cation conductive polymer having intermolecular crosslinking.

  The characteristic of the cross-linked cationic conductive polymer is the dispersible granular polymer obtained, and it can have a high concentration and high density of the cationic component in the particles, so it has not only excellent conductivity. No deterioration of conductivity was observed even under low relative humidity, and although the particles were well dispersed in the dispersed state, the adhesion of the particles was good in the film-forming process after coating, so the film strength was also low. It is strong and has excellent adhesion to other substances such as substrates, and has excellent chemical resistance.

  The dispersible granular polymer, which is a crosslinked cationic conductive polymer, generally has a particle size range of about 0.01 μm to 0.3 μm, preferably a particle size of 0.05 μm to 0.15 μm. As used herein, the term “dispersible particulate polymer” is a polymer that appears to be a clear or slightly turbid solution by visual observation but appears as a particulate dispersion under an electron microscope.

  The addition of the antistatic agent or matting agent is preferably included in the surface layer portion (portion of 10 μm from the surface) of the optical film, and the antistatic agent and / or matting agent is added to the surface of the film by a method such as co-casting. It is preferable to contain. Specifically, a dope A containing a conductive material and / or a matting agent and a dope B substantially not containing these are used, and the dope B is cast so that the dope A is present on at least one side of the dope B. It is preferable.

  If necessary, an antistatic agent, a flame retardant, a lubricant, an oil agent, a matting agent, and other additives may be added.

  The optical film produced by the production method of the present invention can be used as a base plate for a polarizing plate used for a liquid crystal display, an antireflection film used for a liquid crystal display device, or an optical compensation film.

  Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited thereto.

Example 1
(Preparation of dope composition)
Cellulose triacetate propionate 100 parts by mass (acetyl group substitution degree 1.95, propionyl group substitution degree 0.7)
Triphenyl phosphate 10 parts by weight Ethylphthalyl ethyl glycolate 2 parts by weight Tinuvin 326 (manufactured by Ciba Specialty Chemicals) 1 part by weight AEROSIL 200V (manufactured by Nippon Aerosil Co., Ltd.) 0.1 part by weight Methylene chloride 300 parts by weight Part 40 parts by mass of ethanol The above materials are put into a sealed container sequentially, the temperature in the container is raised from 20 ° C. to 80 ° C., and then stirred for 3 hours while maintaining the temperature at 80 ° C. to completely dissolve. did. Then, stirring was stopped and the temperature of the liquid was lowered to 43 ° C., followed by filtration using filter paper (Azumi filter paper No. 244 manufactured by Azumi Filter Paper Co., Ltd.) to obtain a dope.

(Manufacture of cellulose triacetate propionate film)
The cellulose triacetate propionate film was manufactured by the method shown next using the process shown by FIG.1 (c). The prepared dope was cast at a temperature of 33 ° C. from a casting die on a support made of a stainless steel endless belt as shown in Table 1, and then peeled off from the belt. After completion, as shown in FIG. 3, the cellulose triacetate propionate film is conveyed at a conveyance speed of 50 m / min so that one end of the cellulose triacetate propionate film is in contact with the conveyance auxiliary unit formed near the end of the conveyance roll. And dried at 100 ° C. for 20 minutes to produce a cellulose triacetate propionate film having a thickness of 80 μm, each having a thickness of 1000 m. 101-103. In addition, as shown in FIG. 3, as a method of bringing one end of the cellulose triacetate propionate film into contact with the conveyance auxiliary unit formed in the vicinity of the end of the conveyance roll, it is peeled off from the endless belt when casting. The dope is placed on the endless belt by positioning the casting die so that one end of the formed cellulose triacetate propionate film is in contact with the conveyance auxiliary unit formed near the end of the conveyance roll. Casted.

  In addition, the conveyance roll shown by Fig.5 (a) which was 1800 mm in width | variety, and processed the roughness of surface roughness (Ra) 10 micrometers from 100 mm in width to 100 mm from both ends was used. Further, the residual solvent amount of the cellulose triacetate propionate film at the time when the stretching treatment was completed was adjusted to 15% by mass. The surface roughness Ra indicates a value measured according to JIS B 0601-2001. The conveyance speed is calculated by using the pulse generator attached to the motor shaft of the drive motor arranged in the conveyance process and calculating the rotation speed using the roll diameter coupled to the motor / the reduction ratio between the motor and the roll. Indicates the obtained value.

  In addition, each sample No. As comparative samples 101 to 103, all the samples were prepared under the same conditions except that both ends of the cellulose triacetate propionate film were conveyed without contacting the conveyance auxiliary portions of the conveyance roll. 104-106.

Evaluation Each sample No. Table 1 shows the results of observing the presence or absence of scratches due to roll slip by the method shown below, and evaluating according to the evaluation rank shown below.

Method for confirming scratches The presence or absence of scratches was visually confirmed per 1000 m of the produced cellulose triacetate propionate film.

Evaluation rank of scratches ○: No generation of scratches was found Δ: Scratch occurred at about 1 place in 5 m in 1 to 2 widths of the film ×: Scratch occurred on the entire film surface

  The effectiveness of the present invention was confirmed.

Example 2
(Preparation of pellets)
Cycloolefin resin 100 parts by weight Triphenyl phosphate 10 parts by weight Ethylphthalyl ethyl glycolate 2 parts by weight Tinuvin 109 (manufactured by Ciba Specialty Chemicals) 0.5 part by weight Tinuvin 171 (manufactured by Ciba Specialty Chemicals) 0 0.5 part by weight Tinuvin 326 (manufactured by Ciba Specialty Chemicals) 0.3 part by weight AEROSIL 200V (manufactured by Nippon Aerosil Co., Ltd.) 0.1 part by weight Antioxidant 0.01 part by weight 2,6-di-t-butyl -P-cresol pentaerythrityl-tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate]
The mixture of the above materials was melt-mixed at 230 ° C. using a twin-screw extruder and pelletized.

(Manufacture of cellulose acylate film)
A cellulose acylate film was produced by the following method using the melt casting film forming apparatus shown in FIG. Using the prepared pellets, the cellulose acylate film peeled off by the peeling roll was melt-extruded from the T die into a film shape on a cooling roll at a width of 1300 mm, melt extruded at a melting temperature of 250 ° C., cooled and solidified, Continuously transported to the stretching process and stretched 1.5 times at 160 ° C in the width direction with a tenter, then cooled to 30 ° C while relaxing 3% in the width direction, and then released from the tenter, The end of one side of the cellulose acylate film is formed in the vicinity of the end of the transporting roll by changing the angle of the transporting direction angle changing roll in the transporting direction angle changing step provided between the heat treatment step as shown in Table 2. The heat treatment process and the cooling process are conveyed at a conveyance speed of 40 m / min so as to contact the conveyance auxiliary part having the shape shown in FIG. 5D in the state shown in FIG. After winding wound by the winding device at a uniform tension of the tension 150 N / m, the cellulose acylate film for optical thickness 80μm was 1000m prepared Sample No. 201-205.

  In addition, the heat treatment process was performed for 3 minutes at Tg-10 ° C. of the cellulose acylate film, and was cooled to 25 ° C. in the cooling process. The conveyance roll was 1800 mm wide, 100 mm from both ends, and 100 mm wide, and the shape of the conveyance auxiliary portion (see FIG. 5) was 40 mm at a depth of 1.0 mm, a width of 0.5 mm, and an interval of 2 mm. The angle of the conveyance direction angle change roll was changed to contact the conveyance auxiliary portion of the conveyance roll in the heat treatment step by changing the number of conveyance direction angle change rolls according to the angle of the conveyance direction angle change roll. In addition, the depth of the conveyance auxiliary | assistant part, a width | variety, and a space | interval show the value measured using Mitutoyo Co., Ltd. small surface roughness measuring machine Surf Test SJ-400.

Evaluation Each sample No. No. 201 to 205, the presence or absence of scratches due to roll slip and the angle of the optical slow axis were measured by the following method, and the results of evaluation according to the evaluation rank are shown in Table 2.

Observation of presence or absence of scratches The same method as in Example 1 was used.

Evaluation rank of scratches Same as Example 1 Measuring method of angle of optical slow axis Using KOBRA-WPR manufactured by Oji Scientific Instruments Co., Ltd., measuring 30 points at 50 mm intervals in the width direction. The difference was calculated.

Evaluation rank of angle of optical slow axis ○: Maximum and minimum difference of angle of optical slow axis is less than 2 ° △: Maximum and minimum difference of angle of optical slow axis is 2 ° or more, 7 Less than ° x: The difference between the maximum and minimum angles of the optical slow axis exceeds 7 °

  Sample No. 201 has no effect on the optical slow axis and no scratches, but the number of transport direction angle changing rolls increases and the length of the process becomes longer, so that the process needs to be improved in some cases. In addition, the shape of the conveyance auxiliary | assistant part of a conveyance roll is the conveyance roll (surface roughness (Ra) 20 micrometers) shown by Fig.5 (a), the conveyance roll (height of a convex part 50micrometer) shown by FIG.5 (b), The same result was obtained even when the width was 10 mm) and the conveyance roll shown in FIG. 5C (the height of one convex portion was 50 μm, the width was 1 mm, the interval was 2 mm, and the number was 30). The effectiveness of the present invention was confirmed.

Example 3
(Preparation of dope composition)
The same dope as in Example 1 was prepared.

(Manufacture of cellulose triacetate propionate film)
Using the process shown in FIG. 1 (a), a film was prepared by the following method. The prepared dope was cast at a temperature of 33 ° C. on a support made of a stainless steel endless belt from a casting die at a temperature of 1300 mm as shown in Table 2, and then peeled off from the belt. After the completion, the end of one side of the cellulose triacetate propionate film comes into contact with the transport auxiliary unit formed in the vicinity of the end of the transport roll by changing the angle of the transport direction angle changing roll as shown in Table 3. In this way, the film was transported at a transport speed of 50 m / min, dried at 100 ° C. for 20 minutes, and each cellulose triacetate propionate film having a thickness of 80 μm was produced. 301 to 305. In addition, the conveyance direction angle change roll used what was arrange | positioned at the angle change stand with a servomotor. In addition, after extending | stretching process, as shown in FIG. 3, as a method of contacting the edge part of the one side of a cellulose triacetate propionate film with the conveyance assistance part formed in the vicinity of the edge part of a conveyance roll, FIG. As shown in b), the cellulose triacetate pro-ion formed when the dope was cast so that the center line of the cellulose triacetate propionate film and the center line of the belt substantially coincided and the stretching process in the stretching process was completed. The conveyance auxiliary part formed in the vicinity of one end of the cellulose triacetate propionate film in the vicinity of the end of the conveyance roll by changing the number of the conveyance direction angle change rolls by matching the angle of the conveyance direction angle change roll. To come into contact. In addition, the conveyance roll shown in FIG. 5A having a width of 1800 mm, a roughness of 50 mm from both ends, a width of 100 mm, and a surface roughness (Ra) of 20 μm was used. Further, the residual solvent amount of the cellulose triacetate propionate film at the time when the stretching treatment was completed was adjusted to 15% by mass. The angle θ of the transport direction angle changing roll is a value obtained by calculation using the value of the rotation angle encoder in the servo motor.

Evaluation Each sample No. Table 3 shows the results of evaluations according to the evaluation rank, which were measured for the presence or absence of scratches due to roll slip and the angle of the optical slow axis by the following methods.

Observation of presence or absence of scratches The same method as in Example 1 was used.

Scratch evaluation rank The same evaluation rank as Example 1 was adopted.

Measuring method of angle of optical slow axis It carried out by the same method as Example 2.

Evaluation rank of angle of optical slow axis The evaluation rank was the same as in Example 2.

  Sample No. 301 has no effect on the optical slow axis and no scratches, but the number of transport direction angle changing rolls increases and the length of the process becomes longer, so the process needs to be improved in some cases. The effectiveness of the present invention was confirmed.

Example 4
(Preparation of dope composition)
The same dope as in Example 1 was prepared.

(Manufacture of cellulose triacetate propionate film)
Using the prepared dope, sample no. When manufacturing 303, a cellulose triacetate propionate film with a thickness of 80 μm was added to each 1000 m under the same conditions except that the roughness of the conveyance auxiliary part of the conveyance roll shown in FIG. Sample No. 401 to 406. The formation position of the conveyance auxiliary portion was 50 mm from the end of the conveyance roll, and the width was 100 mm. The surface roughness Ra is a value measured by the same method as in Example 1.

Evaluation Each sample No. Table 3 shows the results of observations 401 to 406, which visually observed the conveyance state, and evaluated according to the following evaluation rank. Table 3 shows the results obtained by measuring the presence or absence of scratches due to roll slip by the same method as in Example 1 and evaluating according to the same evaluation rank as in Example 1.

Evaluation rank of conveyance state ○: The product is transported normally without wrinkles. △: Slight wrinkles are generated that do not cause any problems as a product. ×: The occurrence of wrinkles is confirmed.

  The effectiveness of the present invention was confirmed.

Example 5
(Preparation of dope composition)
The same dope as in Example 1 was prepared.

(Manufacture of cellulose triacetate propionate film)
Using the prepared dope, sample no. A cellulose triacetate propionate film having a thickness of 80 μm under the same conditions except that the height of the convex portion of the conveyance auxiliary portion of the conveyance roll shown in FIG. 1000 m each and sample No. 501-506. The formation position of the conveyance auxiliary portion was 50 mm from the end of the conveyance roll, and the width was 100 mm. In addition, the convex part was formed by sticking a heat-resistant tape (# 695 PPS tape) manufactured by Nichiban Co., Ltd. The height was changed by winding a heat-resistant tape.

Evaluation Each sample No. Table 5 shows the results of visually observing the conveyance state and the evaluation according to the same evaluation rank as in Example 3. Table 5 shows the results of measuring the presence or absence of scratches due to roll slip by the same method as in Example 1 and evaluating according to the same evaluation rank as in Example 1.

  The effectiveness of the present invention was confirmed. The same result was obtained even with the conveyance auxiliary part having the shape shown in FIG. 5C (the height of one convex part was 50 μm, the width was 1 mm, the interval was 2 mm, and the number was 30).

Example 6
(Preparation of dope composition)
The same dope as in Example 1 was prepared.

(Manufacture of cellulose triacetate propionate film)
Using the prepared dope, sample no. When manufacturing 302, the cellulose triacetate propio with a thickness of 40 μm was used under the same conditions except that the depth of the concave portion (groove portion) of the conveyance auxiliary portion of the conveyance roll shown in FIG. 5 (d) was changed as shown in Table 5. Nate films were prepared for each 1000 m and Sample No. 601-606. The formation position of the conveyance auxiliary portion was 50 mm from the end of the conveyance roll, and the width was 100 mm. Forty concave portions (groove portions) were provided with a width of 0.5 mm and an interval of 2 mm. The depth, width, and interval of the concave portion (groove portion) of the conveyance auxiliary portion indicate values measured by the same method as in Example 2.

Evaluation Each sample No. Table 6 shows the results obtained by visually observing the conveyance state 601 to 606 and evaluating according to the same evaluation rank as Example 3. Table 6 shows the results of measuring the presence or absence of scratches due to roll slip by the same method as in Example 1 and evaluating according to the same evaluation rank as in Example 1.

  The effectiveness of the present invention was confirmed.

Example 7
(Preparation of dope composition)
The same dope as in Example 1 was prepared.

(Manufacture of cellulose triacetate propionate film)
Using the prepared dope, sample no. When manufacturing 101, the conveyance speed was changed as shown in Table 7 to prepare a cellulose triacetate propionate film having a thickness of 80 μm. 701 to 706. The drying temperature was changed according to the conveyance speed so that the residual solvent amount was the same. Other conditions were the same as in Example 1. In addition, sample No. When manufacturing 303, the conveying speed was changed as shown in Table 7, and a cellulose triacetate propionate film having a thickness of 40 μm was prepared for each 1000 m, and Sample No. 707-712. The drying temperature was changed according to the conveyance speed so that the residual solvent amount was the same. The other conditions were the same as in Example 3. A conveyance speed shows the value measured by the same method as Example 1.

Evaluation Each sample No. Table 7 shows the results of evaluations according to the same evaluation rank as in Example 3 by visually observing the conveyance state 701 to 712. Table 7 shows the results of measuring the presence or absence of scratches due to roll slip by the same method as in Example 1 and evaluating according to the same evaluation rank as in Example 1.

  The effectiveness of the present invention was confirmed.

Example 8
(Preparation of dope composition)
The same dope as in Example 1 was prepared.

(Manufacture of cellulose triacetate propionate film)
Using the prepared dope, sample no. When producing 302, a cellulose triacetate propionate film having a thickness of 80 μm was formed under the same conditions except that the residual solvent amount of the cellulose triacetate propionate film at the time of finishing the stretching process was changed as shown in Table 8. Each 1000 m was prepared and sample No. 801-806. In addition, the value of residual solvent amount (% by mass) is defined as B before the cellulose ester film having a size before drying (200 mm × 200 mm) is dried at 115 ° C. for 1 hour. When the mass of the ester film is A, ((A−B) / B) × 100 = a value obtained by the amount of residual solvent (mass%).

Evaluation Each sample No. Table 8 shows the results obtained by measuring the angle of the optical slow axis in the same manner as in Example 2 and evaluating according to the same evaluation rank as in Example 2. Table 8 shows the results of visual observation of the conveyance state and evaluation according to the same evaluation rank as that of Example 3. Table 8 shows the results of measuring the presence or absence of scratches due to roll slip by the same method as in Example 1 and evaluating according to the same evaluation rank as in Example 1.

  The effectiveness of the present invention was confirmed.

Example 9
(Preparation of dope composition)
The same dope as in Example 1 was prepared.

(Manufacture of cellulose triacetate propionate film)
Using the process shown in FIG. 1 (a), a film was prepared by the following method. The prepared dope was cast with a width of 1300 mm on a support made of a stainless steel endless belt from a casting die at a temperature of 33 ° C. in a state as shown in FIG. After removing the belt from the belt by changing the solvent concentration and completing the stretching process in the stretching process, the end of one side of the cellulose triacetate propionate film is changed by changing the angle of the transport direction angle changing roll as shown in Table 9. Cellulose triacetate pro having a thickness of 80 μm, transported at a transport speed of 50 m / min, dried at 100 ° C. for 20 minutes so as to come into contact with a transport auxiliary section formed in the vicinity of the end of the transport roll (see FIG. 3). Each 1000m of pionate film was prepared. 901-923.

  In addition, when the stretching process in the stretching process is completed, as one method, the end of one side of the cellulose triacetate propionate film comes into contact with the transport auxiliary unit formed in the vicinity of the end of the transport roll. This was done by changing the number of transport direction angle change rolls according to the angle of the angle change roll. In addition, the conveyance roll shown in FIG.5 (d) which provided 1800 mm in width, 50 mm from both ends, width 100 mm, depth 0.5 mm, width 2 mm, and the number of 40 recessed parts (groove part) was used. The value of the residual solvent amount (% by mass) is a value measured by the same method as in Example 8. The angle θ of the transport direction angle changing roll indicates a value measured by the same method as in Example 3.

Evaluation Each sample No. Table 9 shows the results obtained by measuring the angle of the optical slow axis in the same manner as in Example 2 and evaluating according to the same evaluation rank as in Example 2. Table 8 shows the results of visual observation of the conveyance state and evaluation according to the same evaluation rank as that of Example 3. Table 9 shows the results of measuring the presence or absence of scratches due to roll slip by the same method as in Example 1 and evaluating according to the same evaluation rank as in Example 1.

  The effectiveness of the present invention was confirmed.

It is a schematic diagram of the solution casting film forming method of an optical film. It is a schematic diagram which shows an example of the melt casting film forming method of an optical film. It is an expansion schematic perspective view of the part shown by P of Fig.1 (a). It is an expansion schematic plan view of the conveyance auxiliary | assistant part of the conveyance roll shown in FIG. It is the schematic of the conveyance assistance part of a different form of a conveyance roll. It is a schematic diagram which shows the method of conveying a cellulose-ester film in the state shown in FIG. 2 with the solution casting film forming apparatus shown in FIG. It is a schematic sectional drawing of a polarizing plate.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Polarizer 2 Protective film 3a-3d Solution casting film forming apparatus 301 Casting process 301a Mirror surface metal casting belt (belt)
301b Dies 302 Stretching process 302c Tenter stretching device 303, 308 Drying processes 303d to 303f, 305d, 305e, 306d to 306f, 307d, 307e, 308d, 308e, 703a4, 704a4 Conveying rolls 303f1, 303f2, 303f21 to 303f24 Conveying auxiliary section 303g Transport direction angle change roll 304 Winding and collecting step 305 First drying step 306, 307 Second drying step 4 Dope 6 Cellulose ester film 6a, 6b, 303f3 End 7 Melt casting film forming apparatus 701b T die 703a Heat fixing apparatus

Claims (8)

A liquid in which a raw resin is dissolved in a solvent or a liquid melted by heating is cast on an endless support to form a web, and after peeling the web from the endless support, it is brought into contact with a transport roll and transported. In the manufacturing method of the optical film manufactured by winding, the conveyance roll has a conveyance auxiliary portion on a circumferential surface in the width direction in the vicinity of at least one end portion, and one end portion of the web, the conveyance auxiliary portion, In the method of manufacturing an optical film that is conveyed in contact with each other ,
A conveyance angle changing step in which a conveyance angle changing roll for changing the conveyance direction of the web is installed in the conveyance step of the web so that either one end of the web is in contact with the conveyance auxiliary unit. The method for producing an optical film is characterized in that one end of the web and the conveyance auxiliary unit are brought into contact with each other and conveyed . The method for producing an optical film according to claim 1, wherein the conveyance auxiliary portion is formed with a rough surface having an average roughness Ra of 1 μm to 100 μm. The method for producing an optical film according to claim 1, wherein the conveyance auxiliary portion is formed with a convex portion having a height of 10 μm to 500 μm. The method for producing an optical film according to claim 1, wherein the conveyance auxiliary portion is formed of a concave portion having a depth of 0.05 mm to 1 mm. The method for producing an optical film according to any one of claims 1 to 4, wherein a conveyance speed of the web is 30 m / min to 150 m / min. 6. The web according to any one of claims 1 to 5, wherein the web is transported by bringing one end of the web into contact with a transport assisting unit in a region where the residual solvent amount of the web is 2% by mass to 30% by mass. The manufacturing method of the optical film of description. A conveyance angle changing step in which a conveyance angle changing roll for changing the conveyance direction of the web is installed so that only one of the end portions of the web is in contact with the conveyance auxiliary unit is provided in the conveyance step of the web. The residual solvent amount is conveyed to the conveyance angle changing step in an area of 2% by mass to 30% by mass, and conveyed by bringing one end of the web and the conveyance auxiliary unit into contact with each other. The manufacturing method of the optical film of any one of -6. The conveyance angle change roll is arranged so that an angle formed between a direction perpendicular to the axis of the conveyance angle change roll and a conveyance direction of the web is 0.3 ° to 3 °. Item 8. The method for producing an optical film according to any one of Items 1 to 7.

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