JP2008221508A - Optical film, its manufacturing method, polarization plate and liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a wide and thin optical film prevented from feed failure by preventing the curl of the end part of the film to enhance the strength of the end part without installing a special device when the wide and thin optical film is manufactured by a solution casting method using an endless belt support and not causing the occurrence of a cramp or wrinkles, the optical film manufactured by this method, a polarization plate and a liquid crystal display device. <P>SOLUTION: In the manufacturing method for manufacturing the thin optical film by a solution casting manufacturing apparatus having a casting process for casting a dope, which is prepared by dissolving a raw material resin in a solvent, on the endless belt support to form a web and having at least a stretching process, a drying process and a taking-up process after the web is peeled from the endless belt support, the residual amount of the solvent in the lateral direction of the web in the central part of the web from the peeling time of the web from the endless belt support to the stretching start time in the stretching process is made lower than that in the end parts of the web. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for producing an optical film, an optical film, a polarizing plate, and a liquid crystal display device.

  As one method for forming a thin resin film having a thickness of 70 μm or less, a solution casting method is known. The solution casting method is a dope prepared by dissolving a raw material resin in a solvent and adding various additives such as a plasticizer, an ultraviolet absorber, a deterioration preventing agent, a slipping agent, and a peeling accelerator as necessary. Is discharged from a die on a horizontal endless metal belt or an endless support such as a rotating drum, casted, and after removing the solvent to some extent on the endless support, the endless support is supported. It is a method of peeling off from the body and then passing through the drying section by various transport means to remove the solvent.

  One of the uses of the thin resin film produced by these methods is an optical film. In the present invention, various functions such as a protective film for a polarizing plate used for a liquid crystal display (LCD), a retardation film used for a liquid crystal display (LCD), a viewing angle widening film, an antireflection film used for a plasma display, etc. Various functional films used in films and organic EL displays, plastic substrates, photographic supports, moving picture cells and optical filters, and optical films including OHP films.

  The optical film has different functions depending on the application. For example, a polarizing plate protective film is required to be transparent and have excellent physical and mechanical properties, and to have a small dimensional change with respect to temperature and humidity.

  A liquid crystal display device, which is one of the applications of optical films, can be directly connected to an IC circuit with low voltage and low power consumption. In particular, it can be thinned, so a liquid crystal TV, personal computer, word processor, etc. It is widely used as a display device for portable terminals, televisions, and digital still cameras and movie cameras. The liquid crystal display device has a basic configuration in which, for example, polarizing plates are provided on both sides of a liquid crystal cell.

  And the quality improvement of a polarizing plate is requested | required according to the improvement of the quality of a liquid crystal display device, and the protective film of a polarizing plate is also requested | required that it is higher quality with it. Further, in recent years, as the liquid crystal TV becomes larger and thinner, the optical film is required to have higher quality in combination with wider and thinner films.

When producing a thin and wide optical film required as an optical film by the solution casting method using an endless belt support, the following problems are raised.
1. When the web formed and cast on the endless belt support is peeled off from the endless belt support by carrying at high speed to increase production efficiency, the time from casting to peeling is shortened. Residual solvent amount increases.
2. In the drying process, the curling of the end portion becomes large, and breakage of the end portion during drying, failure such as slippage and scratches due to poor conveyance stability occurs.
3. As the amount of residual solvent increases, the amount of shrinkage in the TD (Transverse Direction) direction increases, so that the strength of the end is insufficient, especially when stretching with a tenter stretching device, the gripping part is torn and poor conveyance and wrinkles and wrinkles occur. appear.
4). The strength decreases, the conveyance stability is inferior, and the high-speed conveyance suitability for increasing production efficiency is lacking.

  These problems have been examined so far. For example, when producing a cellulose ester film having a thickness of 20 to 60 μm by casting a dope containing cellulose ester on a support, tenter stretching is performed to prevent curling from occurring at the edge of the web peeled from the support. A method is known in which a guide plate for preventing curling is installed before entering the apparatus to improve the gripping ability of the tenter (see, for example, Patent Document 1).

  However, the technique described in Patent Document 1 is effective as a curl countermeasure at the end, but when it becomes wide, it does not serve as a countermeasure against tearing of the end in the tenter stretching device due to insufficient strength of the end. In the tenter stretching apparatus, the end of the gripping part is torn off, and there is a high risk of occurrence of poor conveyance, slipping and wrinkling.

  When manufacturing a polymer film by the solution casting method, before entering the tenter device, blow out dry air so that the side edge is at a lower drying speed than the center, thereby causing surface defects such as creases, wrinkles, curls, etc. There is known a method for producing a thin film having no film (for example, see Patent Document 2).

  However, the technique described in Patent Document 2 has insufficient strength at the side end portion due to an increase in residual solvent at the side end portion, and when the tenter device is stretched, the side end portion is torn, causing poor conveyance, creases, and wrinkles. There is a high risk of Especially in the case of wide, the danger is high.

  When a cellulose acylate dope is cast to produce a film, the end when the cellulose acylate dope is peeled from the support by casting the cellulose acylate dope on the support so that the thickness of the end is thicker than the center. There is a known method for preventing the curling of the portion and preventing the occurrence of poor conveyance, crease and wrinkle when the side end portion is torn when the tenter clip is gripped by the tenter clip and the tenter device is extended. (For example, refer to Patent Document 3).

  However, in the technique described in Patent Document 3, the end portion is eventually deleted, so that the width of the end portion is increased, and there is a concern that the manufacturing cost increases due to a decrease in yield and extra use of raw materials. The

From these situations, when manufacturing wide and thin optical films by the solution casting method using an endless belt support, curling of the end is prevented without installing a special device, and the strength of the end It is desired to develop a wide, thin optical film manufacturing method that does not cause creases and wrinkles, and an optical film manufactured by this method, a polarizing plate, and a liquid crystal display device. ing.
JP 2003-33933 A JP 2005-271233 A JP 2006-272958 A

  The present invention has been made in view of the above circumstances, and its purpose is to install a wide-thin and thin-film optical film by a solution casting method using an endless belt support without installing a special apparatus. , Preventing curling of the end portion, preventing conveyance failure by increasing the strength of the end portion, a method for producing a wide, thin optical film free from creases and wrinkles, an optical film produced by this method, It is to provide a polarizing plate and a liquid crystal display device.

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

  1. A dope prepared by dissolving a raw material resin in a solvent is cast on an endless belt support from a die to form a web, and after peeling the web from the endless belt support, at least a stretching step, and drying In the method for producing an optical film for producing a thin film optical film by a solution casting production apparatus having a process and a winding process, from the time of peeling from the endless belt support until the start of stretching in the stretching process A method for producing an optical film, wherein the amount of residual solvent in the width direction of the web is made lower at the center than at the ends.

  2. The amount of residual solvent when the web is peeled from the endless belt support has a wide distribution, and the center portion of the web is 5% by mass to 50% by mass lower than the end portion. The manufacturing method of the optical film of description.

  3. The total residual solvent amount when the web is peeled from the endless belt support is 70% by mass to 170% by mass, and the ratio of the good solvent amount to the total residual solvent amount is 10% to 70%. The manufacturing method of the optical film of any one of said 1 or 2.

  4). Any one of the above 1 to 3 characterized in that the residual solvent amount of the web at the start of stretching has a wide distribution, and the central portion of the web is 2 mass% to 20 mass% lower than the end portion. The manufacturing method of the film for optics as described in a term.

  5. The total residual solvent amount at the start of the stretching is 10% by mass to 30% by mass, and the ratio of the good solvent amount to the total residual solvent amount is 5% to 50%. The manufacturing method of the optical film of any one.

  6). The surface of the endless belt support is set such that the temperature at the center in the width direction is set higher than the temperature at the end in the width direction. A method for producing an optical film.

  7. The temperature of the central part in the width direction of the endless belt support on the surface of the endless belt support is 1 ° C. to 30 ° C. higher than the temperature of the end in the width direction. The manufacturing method of the optical film of any one.

  8). The surface temperature of the web from when the web is peeled off from the endless belt support to the start of stretching is 1 to 20 ° C. higher at the center in the width direction than at the end by 1 to 20 ° C. The manufacturing method of the optical film of any one of these.

  9. 9. An optical film produced by the method for producing an optical film described in any one of 1 to 8 above.

  10. A polarizing plate, wherein the optical film described in 9 above is disposed on at least one surface of a polarizer.

  11. 11. A liquid crystal display device using the polarizing plate described in 10 above.

  When manufacturing wide and thin optical films by the solution casting method using an endless belt support, it is transported by preventing end curling and increasing end strength without installing a special device. A method for producing a wide-width, thin-film optical film that prevents defects and does not cause creases and wrinkles, an optical film produced by this method, a polarizing plate, and a liquid crystal display device can be provided. It has become possible to improve the production performance of the film and the quality performance of the polarizing plate and the liquid crystal display device corresponding to the enlargement.

  The present invention prevents curling of the web that occurs between the casting process and the start of stretching in the stretching process, prevents the conveyance failure by increasing the strength of the edge, and has a wide width that does not cause creases and wrinkles. The present invention relates to a method for producing a thin optical film. Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 to 7, but the present invention is not limited thereto.

  FIG. 1 is a schematic view of an apparatus for producing an optical film by a solution casting method in which an endless belt support is used and a first drying step by a roll conveyance system is arranged. FIG. 1A shows a solution casting method using an endless belt support that is preliminarily dried in a first drying process using a roll conveyance method after casting, and then subjected to main drying in a second drying process. It is a schematic perspective view of the manufacturing apparatus of an optical film. FIG. 1B is a schematic cross section taken along the line AA ′ of FIG.

  In the figure, reference numeral 1a represents an apparatus for producing a solution casting method for an optical film. The manufacturing apparatus 1 a includes a casting process 101, a first drying process 102, a stretching process 103, a second drying process 104, and a winding process 105.

  The casting step 101 includes a mirror endless belt support 101a, a die 101b for casting a dope 2 in which a resin is dissolved in a solvent, and a heating device 101c. The endless belt support 101a is held by a roll 101a1 and a roll 101a2, and can be rotated (in the direction of the arrow in the figure).

  Reference numeral 3 denotes a peeling roll for peeling the web in a state where the dope casted on the endless belt support 101a is solidified, and 4 denotes the peeled web. The thickness of the web 4 can be set as necessary so that the thickness of the optical film collected in the winding process 105 becomes the set film thickness.

  The dope 2 is produced using a resin material for an optical film as a mixed solvent composed of a good solvent and a poor solvent. In the present invention, what dissolves the resin used alone is called a good solvent, and what swells or does not dissolve alone is called a poor solvent.

  The heating device 101c is disposed to remove the solvent so that the dope 2 cast on the endless belt support 101a can be peeled from the endless belt support 101a.

  The heating device 101c includes a drying box 101c1, heating air supply pipes 101d1 to 101d6 disposed in the drying box 101c1, and an exhaust pipe 101d7. The heated air supply pipes 101d1 to 101d6 are disposed so that the temperatures at both ends and the center of the endless belt support 01a can be controlled separately. Although the heating apparatus 101c shown in this figure shows the case where heating air is used, the heating means is not particularly limited. In addition to this, for example, a method of heating the dope surface on the endless belt support 101a with an infrared heater A method of blowing warm air to the back surface of the endless belt support 101a and heating from the back surface side can be mentioned, and it can be appropriately selected as necessary.

  The endless belt support 101a is provided with measuring means (not shown) and display means (not shown) so that the temperatures at both ends and the center of the surface of the endless belt support 101a can be measured. The measuring means is not particularly limited, and examples thereof include a non-contact type thermometer and a contact type thermometer, and can be appropriately selected as necessary. The display means is not particularly limited, and examples thereof include a liquid crystal display device, and can be appropriately selected as necessary.

  The time between casting and peeling varies depending on the film thickness of the optical film to be produced and the solvent used, but in the range of 0.5 to 5 minutes in consideration of peelability from the endless belt support 101a. preferable.

  As the endless belt support 101a to be used, one having a mirror-finished surface is preferable. For example, a metal belt having a surface plated with a casting is preferably used. The width of the endless belt support 101a is preferably 1700 mm to 2700 mm. The casting width is preferably 80% to 99% with respect to the width of the endless belt support 101a.

  The surface temperature of the endless belt support 101a in the casting process is preferably set to 20 ° C. to a temperature at which the solvent does not boil and foam. A higher temperature is preferable because the web can be dried faster, but if the temperature is too high, the web may foam or the flatness may deteriorate.

  The surface of the endless belt support 101a is preferably set so that the temperature at the center in the width direction is higher than the temperature at the end in the width direction. More preferably, the surface of the endless belt support 101a has a releasability from the endless belt support, a residual solvent amount at the time of peeling, It is preferable that the temperature is set to be higher by 1 ° C. to 30 ° C. in consideration of the transport properties and the physical characteristics of the film obtained after transport and drying.

  In addition, the edge part of the surface of the endless belt support body 101a means the range of 50 mm-500 mm in the width direction on the basis of the edge of the surface of the endless belt support body 101a. The central portion of the surface of the endless belt support 101a refers to a portion excluding the range of both ends from the entire width of the endless belt support 101a.

The residual solvent amount of the web 4 from when it peels from the endless belt support 101a to the start of stretching in the stretching process has a wide distribution and is lower in the center than the end of the web 4 (end The residual solvent amount in the part is higher than the residual solvent amount in the central part). The residual solvent is a solvent used for dissolving the resin used when preparing the dope, and is composed of a mixed solvent composed of a good solvent and a poor solvent. In the present invention, what dissolves the resin used alone is called a good solvent, and what swells or does not dissolve alone is called a poor solvent, and has an effect of promoting gelation of the dope. When the amount of residual solvent at the center of the web 4 is higher than the amount of residual solvent at the end (the amount of residual solvent at the end is lower than the amount of residual solvent at the center), the thickness is 20 μm to 70 μm and the width is 1200 mm to 1900 mm. Since the following adverse effects are exerted on the web 4 for optical films, it is not preferable.
1) Curling occurs at the edge of the web from the time when it is peeled off from the endless belt support until the start of stretching in the stretching process, and failure such as creases and scratches due to inferior edge bending and poor conveyance stability occurs. To do.
2) When the center portion becomes heavy and is gripped by the tenter device in the stretching process and stretched in the TD direction, the strength of the end portion is insufficient and the gripping portion is broken.
3) When the gripping part is torn off, the conveyance is poor, and creases, wrinkles, and scratches are generated.

  The present invention utilizes the effect of promoting the gelation of the poor solvent dope, and the amount of residual solvent at the end is greater than the amount of residual solvent at the center, so that even when a thin film / wide web is conveyed, Prevents loosening due to the weight of the center part, prevents curling of the end part, increases the amount of poor solvent at the end part and promotes the gelation of the end part to give the end part strength and stretch with a tenter device Thus, the gripping of the end portion is stabilized, and the scratches due to tearing of the gripping portion, wrinkles, and conveyance failure are prevented.

  The residual solvent amount of the web 4 when the web 4 is peeled from the endless belt support 101a is 70% by mass or more in consideration of curl stability at the end, conveyance stability, gripping ability with a tenter device, stretch rate, and the like. 170 mass% is preferable. Moreover, the ratio of the good solvent amount to the total residual solvent amount is such that the peelability of the web from the endless belt support, the curl stability of the end portion, the strength strength of the end portion by stabilizing the residual of the poor solvent, Considering gripping suitability and the like, 10% to 70% is preferable. Preferably it is 5%-60%, More preferably, it is 5%-30%. The solvent to be used will be described later.

  The preferred residual solvent amount in the central portion of the web 4 from the time when it is peeled off from the endless belt support 101a until the start of stretching in the stretching step 103 includes curl stability at the end, gripping ability with a tenter device, and transport stability. In consideration of the expansion and contraction rate, it is preferably 5% by mass to 50% by mass lower than the residual solvent amount at the end.

  In the present invention, the end portion of the web refers to a range of 100 mm to 500 mm from the end side of the web toward the center portion. Preferably it is the range of 100 mm-400 mm, More preferably, it is the range of 100 mm-300 mm. The center portion refers to a portion excluding the range of the end portions at both ends from the entire width of the web.

  The concentration of the resin for forming the optical film of the dope 2 is preferably higher because the drying load after casting on the endless belt support can be reduced, but the concentration of the resin for forming the optical film is too high. And the load at the time of filtration increases, and the filtration accuracy deteriorates. The concentration for achieving both of these is preferably 10% by mass to 35% by mass, and more preferably 15% by mass to 25% by mass.

  When the web 4 is peeled from the endless belt support 101a, the web 4 is stretched in the MD (Machine Direction) direction due to the peeling tension and the subsequent conveying tension. Therefore, in the present invention, the web is peeled from the endless belt support 101a. In this case, it is preferable that the peeling and conveying tension be 100 N / m to 400 N / m.

  The first drying step 102 includes a drying device 102a. The drying apparatus 102a has an outer box 102a1, heated air supply pipes 102b1 to 102b6 disposed in the outer box 102a1, a discharge port 102b7, an upper conveying roll 102c for conveying the web 4, and a lower conveying roll 102d. is doing. The internal configuration of the drying apparatus 102a is the same as the heating apparatus 101c (see FIG. 2) in the casting process 101. The heated air supply pipes 102b1 to 102b6 are arranged so that the temperatures at both ends and the center of the surface of the web 4 sent from the casting process 101 can be controlled separately. The upper transport roll 102c and the lower transport roll 102d 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 web 4 before entering the stretching step 103 in the first drying step 102.

  The drying temperature varies depending on the amount of residual solvent of the web when entering the stretching process, but it takes into account condensation on the surface of the web accompanying evaporation of the solvent, adjustment of the residual solvent amount, stretching ratio, foaming of the solvent, etc. In the range from ℃ to 80 ℃, select and decide appropriately according to the amount of residual solvent, and the end portion so that the central portion in the width direction of the web when entering the stretching step is 1 ℃ to 20 ℃ higher than the end portion. It is preferable to dry by adjusting the drying temperature in the center. In the 1st drying process 102, you may use heating air, infrared rays alone, or heating air and infrared drying together. It is preferable to use heated air in terms of simplicity. This figure shows the case where heated air is used.

  The width distribution of the residual solvent amount of the web when the processing in the first drying step 102 is completed and the stretching in the stretching step 103 is started, considering the physical characteristics of the film that is formed after transporting and drying, and the like. It is preferable that the residual solvent amount in the central part is 2% by mass to 20% by mass lower than the residual solvent amount at the end part.

  The stretching step 103 includes an outer box 103a having a dry air intake port 103b and a discharge port 103c, and a tenter stretching device 103d placed in the outer box 103a. The tenter used in the tenter stretching apparatus 103d is not particularly limited, and examples thereof include a clip tenter and a pin tenter, which can be selected and used as necessary. In the tenter stretching apparatus 103d, it is possible to stretch the web 4 in the transport direction (MD direction) or in the direction perpendicular to the transport direction (TD direction) as necessary.

  The dry air intake port 103b and the discharge port 103c may be reversed. Although the case where heated air is used as the solvent removing means in the stretching step 103 is shown, the solvent removing means is not particularly limited, and other examples include infrared rays.

  The total residual solvent amount of the web at the start of stretching in the stretching step 103 is 10% by mass to 30% by mass in consideration of the curl stability at the end, the gripping ability with the tenter device, the conveyance stability, the stretch rate, and the like. It is preferable to do. In addition, the ratio of the good solvent amount to the total residual solvent amount is preferably 5% to 50% in consideration of gripping suitability with a tenter device, conveyance stability, and the like. Preferably, it is 5% to 40%. More preferably, it is 5% to 30%.

  The surface temperature of the web when the treatment in the first drying step 102 is finished and the drawing in the drawing step 103 is started takes into account the amount of residual solvent at the edge and center in the width direction, the strength of the edge, and the like. And it is preferable that the center part of the width direction is 1 to 20 degreeC higher than an edge part. The means for measuring the surface temperature of the web at the start of stretching in the stretching step is not particularly limited, and examples thereof include a non-contact thermometer, a contact thermometer, and the like, which can be appropriately selected as necessary. . The display means is not particularly limited, and examples thereof include a liquid crystal display device, and can be appropriately selected as necessary.

  In the case of the manufacturing apparatus shown in this figure, the stretch rate in the MD direction of the web 4 is peeled off from the endless belt support 101a until the start of stretching in the stretching step 103, and the elastic modulus of the finished film and the optical properties of the finished film In consideration of the above, 1% to 15% is preferable. The stretch rate in the TD direction of the web 4 is preferably -1% to -15% in consideration of the elastic modulus of the finished film, the optical properties of the finished film, and the like.

  The second drying step 104 includes a drying box 104a having a drying air intake port 104b and a discharge port 104c, an upper conveyance roll 104d that conveys the web 4, and a lower conveyance roll 104e. The upper conveyance roll 104d and the lower conveyance roll 104e are a set of upper and lower, and are configured by a plurality of sets. The number of transport rolls disposed in the second drying step 104 varies depending on the drying conditions, the method, the length of the optical film to be manufactured, and the like, and is appropriately set. The upper conveyance roll 104d and the lower conveyance roll 104e are free rotation rolls that are not rotationally driven by a drive source. In addition, between the drying process and the winding process, a transport roll that freely rotates is not used. Usually, one to several transport drive rolls (roll driven to rotate by a drive source) are installed. Need. Basically, the purpose of the transport drive roll is to transport the resin film by its drive, so the transport of the resin film and the rotation of the drive roll are synchronized by nip or suction (air suction). With the mechanism.

  In the 2nd drying process 104, you may use heating air, infrared rays alone, or heating air and infrared drying together. It is preferable to use heated air in terms of simplicity. This figure shows the case where heated air is used. The drying temperature varies depending on the amount of residual solvent in the web when entering the drying process, but is appropriately selected depending on the amount of residual solvent in the range of 30 ° C to 180 ° C in consideration of drying time, shrinkage unevenness, stability of the amount of expansion and contraction, etc. The temperature may be determined, 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 residual solvent amount of the optical film after the drying treatment in the second drying step 104 is preferably 0.01% 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 present invention, the web formed in the casting step is gradually removed in the second drying step 104, and the web in which the total residual solvent amount is 15% by mass or less is referred to as an optical film.

  The winding recovery step 105 has a winding device (not shown), and winds the optical film 5 having the residual solvent amount set in the second drying step 104 to a necessary length to be wound around the winding core. 105a shows the roll-shaped optical film wound up by the 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 winding and collecting steps shown in FIGS. 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 stretch rate of the optical film 5 collected in the winding and collecting step 105 is 0% to 20% in the MD direction and the stretch rate in the TD direction in consideration of the physical characteristics of the film that is obtained after transporting and drying. Is preferably −3% to 20%.

  FIG. 2 is a schematic enlarged sectional view taken along the line BB ′ of FIG.

  The heating device 101c includes a drying box 101c1, a first heated air blowing header 101e1, a second heated air blowing header 101e2, a third heated air blowing header 101e3, and a fourth heated air blowing header 101e4. It has a fifth heated air blowing header 101e5, a sixth heated air blowing header 101e6, an exhaust pipe 101d7 (see FIG. 1), and heated air supply pipes 101d1 to 101d6. 101e11 shows the heating air blowing port of the first heating air blowing header 101e1. 101e21 indicates a heating air blowing port of the second heating air blowing header 101e2. Reference numeral 101e31 denotes a heating air blowing port of the third heating air blowing header 101e3. Reference numeral 101e41 denotes a heating air blowing port of the fourth heating air blowing header 101e4. 101e51 indicates a heating air blowing port of the fifth heating air blowing header 101e5. Reference numeral 101e61 denotes a heating air blowing port of the sixth heating air blowing header 101e6.

  The first heated air blowing header 101e1 and the third heated air blowing header 101e3 are disposed to dry both ends of the dope cast on the front half of the endless belt support 101a. The heated air blowing header 101e2 is disposed to dry the central portion of the dope cast on the front half of the endless belt support 101a.

  The fourth heated air blowing header 101e4 and the sixth heated air blowing header 101e6 are arranged to dry both ends of the dope cast on the second half of the endless belt support 101a. The heated air blowing header 101e5 is disposed to dry the central portion of the dope cast on the rear half of the endless belt support 101a. The structure of the drying apparatus 102a shown in FIG. 1 is the same as the structure of the drying box 101c1 shown in this figure.

  FIG. 3 is an enlarged schematic cross-sectional view of the casting process shown in FIG.

  The dope 2 cast on the endless belt support 101a is in the dope by being heated by blowing air from each heating air blowing port sequentially with the rotational movement of the endless belt support 101a (in the direction of the arrow in the figure). The solvent is removed to form a web, which becomes a solidified web 4 that can be peeled from the endless belt support 101a, and is conveyed to the next step.

  In the present invention, the front half of the endless belt support 101a refers to the upper part of the endless belt support 101a held between the holding roll 101a1 and the holding roll 101a2, and the latter half of the endless belt support 101a is The lower part of the endless belt support 101a held between the holding roll 101a1 and the holding roll 101a2.

  The second heated air blowing header 101e2 is disposed so as to blow heated air over substantially the entire length of the front half of the belt 101a. The first heated air blowing header 101e1 (see FIG. 2) and the third heated air blowing header 101e3 (see FIG. 2) are also arranged in the same manner as the second heated air blowing header 101e2.

  The fifth heated air blowing header 101e5 is disposed so as to blow heated air over substantially the entire length of the rear half of the endless belt support 101a. The fourth heated air blowing header 101e4 (see FIG. 2) and the sixth heated air blowing header 101e6 (see FIG. 2) are also arranged in the same manner as the fifth heated air blowing header 101e5.

  As shown in FIGS. 2 and 3, the heating air blowing headers are arranged so as to heat the dope side, but the belt held by the holding roll to heat the back side of the belt. A similar heating air blowing header may be disposed between the two.

  FIG. 4 is a schematic view of an apparatus for producing an optical film by a solution casting method in which an endless belt support is used and a first drying step by a tenter conveyance method is arranged. FIG. 4 (a) shows a solution casting method using an endless belt support of an optical film that is preliminarily dried in a first drying process by a tenter conveyance method after casting, and then dried in a drying process. It is a schematic perspective view of this manufacturing apparatus. FIG. 4B is a schematic cross section taken along the line CC ′ of FIG.

  The difference from the manufacturing apparatus 1a shown in FIG. 1 is that the first drying step 102 in FIG. 1 (a) has a first drying step by a tenter conveyance method in the case of FIG. That is. Everything else is the same as in FIG.

  In the figure, 1b shows a manufacturing apparatus for a solution casting method of an optical film. The manufacturing apparatus 1 b includes a casting process 101, a first drying process 102 ′, a stretching process 103, a second drying process 104, and a winding process 105. The casting process 101, the stretching process 103, the second drying process 104, and the winding process 105 are the same as those in the manufacturing apparatus shown in FIG.

  The first drying step 102 'includes an outer box 102'a having a dry air intake port 102'b and a discharge port 102'c, and a tenter transport device 102'd placed in the outer box 102'a. Have. As the tenter used for the tenter conveying apparatus 102 ′ d, the same tenter as that used in the stretching process 103 can be used. In the tenter conveying apparatus 102'd, the web 4 is conveyed while being held at both ends by the tenter, so that contraction in the MD direction can be controlled. It is possible to adjust the amount of solvent contained in the web 4 before entering the stretching step 103 in the first drying step 102 ′.

  The drying temperature varies depending on the amount of residual solvent of the web when entering the stretching process, but it takes into account condensation on the surface of the web accompanying evaporation of the solvent, adjustment of the residual solvent amount, stretching ratio, foaming of the solvent, etc. What is necessary is just to select and determine suitably with the amount of residual solvents in the range of -80 degreeC, and it may dry at fixed temperature and may be divided and divided into several steps of temperature. Other symbols are the same as those in FIG.

  In the case of the manufacturing apparatus shown in this figure, as in the case of the manufacturing apparatus 1 a shown in FIG. 1, the residual solvent of the web 4 from the time when the web 4 is peeled from the endless belt support 101 a until the start of stretching in the stretching step 103. The amount has a wide distribution, and the central portion of the web 4 is lower than the end portion (the residual solvent amount at the end portion is higher than the residual solvent amount at the central portion).

  When the web 4 is peeled from the endless belt support 101a, the total residual solvent amount of the web 4, the width distribution of the residual solvent amount, and the ratio of the good solvent amount to the total residual solvent amount are the case of the manufacturing apparatus 1a shown in FIG. Is the same.

  When the treatment in the first drying step 102 ′ is completed and the stretching in the stretching step 103 is started, the width distribution of the residual solvent amount of the web, the residual solvent amount, and the ratio of the good solvent amount to the total residual solvent amount are This is the same as the manufacturing apparatus 1a shown in FIG. The surface temperature of the web when the treatment in the first drying step 102 ′ is finished and the drawing in the drawing step 103 is started is determined by the amount of residual solvent at the edge and center in the width direction, the strength of the edge, etc. In consideration, it is preferable that the central portion in the width direction is higher by 1 ° C. to 20 ° C. than the end portion. The measurement of the surface temperature of the web is the same method as in FIG.

  The stretch rate in the MD direction and the stretch rate in the TD direction of the web 4 until peeling from the endless belt support and at the start of stretching in the stretching step 103 are the same as in the manufacturing apparatus 1a shown in FIG. The expansion / contraction rate of the optical film 5 recovered in the winding recovery step 105 is the same as that in the manufacturing apparatus 1a shown in FIG.

  FIG. 5 is a schematic view of an apparatus for producing an optical film by a solution casting method using an endless belt support and arranging an MD stretching step. FIG. 5 (a) shows a solution flow using an endless belt support that is preliminarily dried in a first drying process by a tenter conveying system after casting, then passed through a MD stretching process, and then dried in a drying process. It is a schematic perspective view of the manufacturing apparatus of the optical film by a rolling method. FIG. 5B is a schematic cross section taken along line DD ′ of FIG.

  1 differs from the manufacturing apparatus 1a shown in FIG. 1 in that the first drying step 102 in FIG. 1 has a first drying step 102 ′ by the tenter conveyance method in the case of FIG. 103 has an MD stretching step 103 ′. Everything else is the same as in FIG.

  In the figure, 1c represents a manufacturing apparatus for the solution casting method of an optical film. The manufacturing apparatus 1 c includes a casting process 101, a first drying process 102 ′, an MD stretching process 103 ′, a stretching process 103, a second drying process 104, and a winding process 105. The casting process 101, the stretching process 103, the second drying process 104, and the winding process 105 are the same as those in the manufacturing apparatus 1a shown in FIG. 1, and the first drying process 102 ′ is shown in FIG. Since this is the same as the manufacturing apparatus 1b to be described, the description thereof is omitted.

  The MD stretching step 103 ′ includes a heating device 103 ′ a, a feed roll 103 ′ b on the first drying step 102 ′ side and a feed roll 103 ′ c on the stretching step 103 side across the heating device 103 ′ a. ing. The MD stretching ratio can be adjusted by the balance between the peripheral speeds of the feed roll 103'b and the feed roll 103'c.

  The heating device 103'a has an outer box 103'a1, heated air supply pipes 103'b1 to 103'b6 disposed in the outer box 103'a1, and an exhaust pipe 103'b7. The heated air supply pipes 103'b1 to 103'b6 are heated by a heating device 101c shown in FIG. 1 so that the temperatures at both ends and the center of the surface of the web 4 fed from the first drying step 102 'can be controlled separately. It is arranged in the same way.

  The heating device 103'a adjusts the distribution of the residual solvent amount in the width direction of the web 4 when stretching is started in the stretching step 103, so that the heating air from the heated air supply pipes 103'b1 to 103'b6 is adjusted. It is preferable to change the temperature between the end portion and the center portion so that the temperature at the center portion is 1 ° C. to 20 ° C. higher than the temperature at the end portion. It is also possible to adjust the amount of residual solvent contained in the web 4 when stretching is started in the stretching step 103, together with the first drying step 102 '. The heating device 103′a shown in this figure may be heating air, infrared rays alone or a combination of heating air and infrared drying. It is preferable to use heated air in terms of simplicity. This figure shows the case where heated air is used.

  The outer box 103′a1 has a transport unit having an upper transport roll 103′d1 and a lower transport roll 103′d2 for transporting the web 4 sent from the first drying step 102 ′. Yes. The upper transport roll 103'd1 and the lower transport roll 103'd2 are a set of upper and lower, and are composed of a plurality of sets. The number of conveyance rolls arranged in the conveyance unit can be appropriately set depending on the MD stretching rate.

  The heating temperature varies depending on the residual solvent amount of the web conveyed from the first drying step 102 ′ or the residual solvent amount of the web when entering the stretching step, but condensation on the surface of the web as the solvent evaporates, In consideration of the amount of residual solvent, adjustment of expansion and contraction, foaming of the solvent, etc., it is selected and determined appropriately depending on the amount of residual solvent in the range of 20 ° C. to 80 ° C. It is preferable to adjust the heating temperature of the end portion and the central portion so that the portion is 1 ° C. to 20 ° C. higher than the end portion.

  In the case of the manufacturing apparatus shown in this figure, as in the case of the manufacturing apparatus shown in FIG. 1, the residual solvent amount of the web 4 from the time of peeling from the endless belt support 101 a to the start of stretching in the stretching step 103 is It has a wide distribution, and the central part of the web 4 is lower than the end part (the residual solvent amount at the end part is higher than the residual solvent quantity at the central part).

  The residual solvent amount of the web 4 when peeled from the endless belt support 101a, the width distribution of the residual solvent amount, and the ratio of the good solvent amount to the total residual solvent amount are the same as in the production apparatus shown in FIG. . The stretch rate in the MD direction of the web 4 after peeling from the endless belt support and until the start of stretching in the stretching step 103 is the same as in the manufacturing apparatus shown in FIG. The width distribution of the residual solvent amount of the web when the treatment in the first drying step 102 ′ is finished and the drawing in the drawing step 103 is started, the total residual solvent amount, and the ratio of the good solvent amount to the total residual solvent amount Is the same as that of the manufacturing apparatus shown in FIG. The stretch rate in the MD direction and the stretch rate in the TD direction of the web 4 from the endless belt support until the start of stretching in the stretching step 103 are the same as in the manufacturing apparatus shown in FIG. The expansion / contraction rate of the optical film 5 collected in the winding process 105 is the same as that in the manufacturing apparatus shown in FIG.

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

  The ratio of the good solvent amount to the total residual solvent amount in the present invention is that a sample of a certain area is collected and extracted with a cosolvent of a good solvent and a poor solvent, and the measurement is performed by a gas manufactured by Hewlett-Packard Company connected with a headspace sampler. The values measured using the chromatography 5890 type SERISII and the headspace sampler HP7694 type under the following measurement conditions are shown.

Headspace sampler heating conditions: 120 ° C, 20 minutes GC introduction temperature: 150 ° C
Temperature rise: 40 ° C, hold for 5 minutes → 100 ° C (8 ° C / min)
Column: J-W DB-WAX (inner diameter 0.32 mm, length 30 m).

  The expansion / contraction ratio in the MD direction in the present invention is a value obtained from the conveyance speed at the start of stretching relative to the conveyance speed during casting or the conveyance speed during winding relative to the conveyance speed during casting.

  The expansion / contraction ratio in the TD direction is a value obtained from the film width at the start of stretching relative to the film width during casting or the film width during winding relative to the film width during casting.

  The width of the optical film produced by the method for producing an optical film by the solution casting method of the present invention is compatible with a liquid crystal screen like a large TV, the use efficiency of the film at the time of polarizing plate processing, workability, production efficiency, etc. In consideration of the above, 1200 mm to 2400 mm is preferable. The film thickness is preferably 20 μm to 70 μm in view of thinning the liquid crystal panel, thinning the polarizing plate, stabilizing production of the film, and the like. The film thickness indicates an average film thickness, and 20 to 200 positions in the width direction are measured with a contact-type film thickness meter manufactured by Mitutoyo Corporation, and an average value is shown. In the present invention, the range of 20 μm to 70 μm in thickness is defined as a thin film.

The following effects can be obtained by the method for producing an optical film by the solution casting method using the endless belt support of the present invention.
1. It is possible to prevent curling that occurs at both ends of the web when the web for forming a thin film / wide optical film is peeled off from the endless belt support, and there is no danger of bending of the end. Improved gripping ability.
2. Improved strength at both ends of the web eliminates tearing of gripped parts in the tenter device, eliminates poor transport due to poor gripping, and enables stable production of thin films and wide optical films free from creases, wrinkles, and scratches. became.
3. With the manufacture of stable quality thin films and wide optical films, polarizing films using these thin films and wide optical films and larger and lighter liquid crystal display devices can be supported and quality stabilized. It has become possible.

  FIG. 6 is a schematic view of a polarizing plate produced using the optical film produced by the production method of the present invention as a protective film.

  In the figure, 6 indicates a polarizing plate. The polarizing plate 6 has a configuration in which protective films 602 are disposed on both sides of the polarizer 601. The polarizing plate shown in this figure can be manufactured by a general method.

  It is preferable that the back side of the protective film 602 be subjected to alkali saponification treatment and bonded to both sides of the polarizer using a completely saponified polyvinyl alcohol aqueous solution. A polarizer is an element that allows only light of a polarization plane in a certain direction to pass through. A typical polarizer currently known is a polyvinyl alcohol polarizing film, which is obtained by staining a polyvinyl alcohol film with iodine. Some of them are dyed with dichroic dyes. As the polarizing film, a polyvinyl alcohol aqueous solution is formed and dyed by uniaxially stretching or dyed, or uniaxially stretched after dyeing, and then preferably subjected to a durability treatment with a boron compound. The polarizing plate of the present invention can optimize the viewing angle characteristics of a liquid crystal display device employing various driving methods such as TN, VA, OCB, HAN, and IPS.

  FIG. 7 is a schematic exploded view of a liquid crystal display device using a polarizing plate produced using the optical film produced in the present invention.

  In the figure, reference numeral 7 denotes a liquid crystal display device. The liquid crystal display device 7 is configured to have polarizing plates 702 on both sides of the liquid crystal cell 701. The polarizing plate 702 includes a protective film 702b on both sides of the polarizer 702a. The liquid crystal display device incorporating the polarizing plate of the present invention has a high contrast even in a large-screen liquid crystal display device having a screen of 30 or more types, particularly 30 to 54 types, and suppresses color change due to viewing angle, for a long time. There is an effect that the eyes are not tired even when watching.

  Next, the materials used in the method for producing an optical film of the present invention will be described.

(Resin material)
The resin used in the method for producing an optical film of the present invention is not particularly limited, and generally a resin used in a solution casting method can be used. As a resin material for producing an optical film, for example, good adhesiveness with a polarizer and optical transparency are preferable requirements. The visible light transmittance is 60% or more, preferably 80% or more, and particularly preferably 90% or more.

  The resin is not particularly limited as long as it is a resin that forms an optical film having the above properties. For example, cellulose esters such as cellulose diacetate resin, cellulose triacetate resin, cellulose acetate butyrate resin, and cellulose acetate propionate resin. Resin, polyester resin, polycarbonate resin, polyarylate resin, polysulfone (including polyethersulfone) resin, polyethylene terephthalate resin, polyester resin such as polyethylene naphthalate resin, polyethylene resin, polypropylene resin, cellophane, polychlorinated resin Vinylidene resin, polyvinyl alcohol resin, ethylene vinyl alcohol resin, syndiotactic polystyrene resin, polycarbonate resin, cycloolefin resin, polymethyl Pentene resins, polyether ketone resins, polyether ketone imide resin, polyamide resin, fluorine resin, nylon resin, polymethylmethacrylate resin, and acrylic resin. Among these, cellulose ester resins, cycloolefin resins, polycarbonate resins, and polysulfone (including polyethersulfone) resins are preferable. In the present invention, cellulose ester resins, cycloolefin resins, and polycarbonate resins are particularly preferable in production. From the viewpoints of cost, transparency, adhesion and the like, it is preferably used.

  The cellulose ester resin according to the present invention will be described. The cellulose ester resin is preferably cellulose acetate resin, cellulose propionate resin, cellulose butyrate resin, cellulose acetate butyrate resin, or cellulose acetate propionate resin. Among them, cellulose acetate butyrate resin, cellulose acetate phthalate resin, cellulose acetate Propionate resin is preferably used.

  In particular, when the substitution degree of the acetyl group is X and the substitution degree of the propionyl group or butyryl group is Y, a cellulose ester resin having a mixed fatty acid ester of cellulose in which X and Y are in the following ranges is preferably used.

Formula (I) 2.0 ≦ X + Y ≦ 2.6
Formula (II) 0.1 ≦ Y ≦ 1.2
Furthermore, a cellulose acetate propionate (total acyl group substitution degree = X + Y) resin of 2.4 ≦ X + Y ≦ 2.6 and 1.4 ≦ X ≦ 2.3 is preferable. Among them, 2.4 ≦ X + Y ≦ 2.6, 1.7 ≦ X ≦ 2.3, 0.1 ≦ Y ≦ 0.9, cellulose acetate propionate resin, cellulose acetate butyrate (total acyl group substitution degree = X + Y ) Resins are preferred. The portion not substituted with an acyl group usually exists as a hydroxyl group. These cellulose ester resins can be synthesized by a known method. The measuring method of the substitution degree of an acyl group can be measured according to the provisions of ASTM-D817-96.

  When the cellulose ester resin is used as the optical film according to the present invention, the cellulose used as the raw material for the cellulose ester resin is not particularly limited, but includes cotton linter, wood pulp (derived from coniferous tree, derived from broadleaf tree), kenaf and the like. I can list them. Moreover, the cellulose ester-type resin obtained from them can be mixed and used in arbitrary ratios, respectively. When the acylating agent is an acid anhydride (acetic anhydride, propionic anhydride, butyric anhydride), these cellulose ester resins use an organic acid such as acetic acid or an organic solvent such as methylene chloride, It can obtain by making it react with a cellulose raw material using such a protic catalyst.

When the acylating agent is acid chloride (CH ₃ COCl, C ₂ H ₅ COCl, C ₃ H ₇ COCl), the reaction is carried out using a basic compound such as an amine as a catalyst. Specifically, it can be synthesized with reference to the method described in JP-A-10-45804. The cellulose ester resin used in the present invention is obtained by mixing and reacting the above acylating agent amounts in accordance with the degree of substitution. In the cellulose ester resin, these acylating agents react with hydroxyl groups of cellulose molecules. To do. Cellulose molecules are composed of many glucose units linked together, and the glucose unit has three hydroxyl groups. The number of acyl groups derived from these three hydroxyl groups is called the degree of substitution (mol%). For example, cellulose triacetate has acetyl groups bonded to all three hydroxyl groups of the glucose unit (actually 2.6 to 3.0).

  As described above, the cellulose ester resin according to the present invention includes a propionate group or a butyrate group in addition to an acetyl group such as a cellulose acetate propionate resin, a cellulose acetate butyrate resin, or a cellulose acetate propionate butyrate resin. A mixed fatty acid ester of cellulose to which is bound is particularly preferably used. In addition, the cellulose acetate propionate resin containing a propionate group as a substituent is excellent in water resistance and is useful as a film for a liquid crystal image display device.

  The number average molecular weight of the cellulose ester-based resin is preferably 40000 to 200000, and has a high mechanical strength when molded, and an appropriate dope viscosity in the case of a solution casting method, and more preferably 50000 to 150,000. . The weight average molecular weight (Mw) / number average molecular weight (Mn) is preferably in the range of 1.4 to 4.5.

  The cycloolefin resin according to the present invention will be described. The cycloolefin resin used in the present invention is composed of a polymer resin containing an alicyclic structure. A preferred cycloolefin resin is a resin obtained by polymerizing or copolymerizing a cyclic olefin. Examples of the cyclic olefin include norbornene, dicyclopentadiene, tetracyclododecene, ethyltetracyclododecene, ethylidenetetracyclododecene, tetracyclo [7.4.0.110, 13.02,7] trideca-2,4. Unsaturated hydrocarbons of polycyclic structures such as 6,11-tetraene and derivatives thereof; cyclobutene, cyclopentene, cyclohexene, 3,4-dimethylcyclopentene, 3-methylcyclohexene, 2- (2-methylbutyl) -1-cyclohexene, cyclo Examples thereof include monocyclic unsaturated hydrocarbons such as octene, 3a, 5,6,7a-tetrahydro-4,7-methano-1H-indene, cycloheptene, cyclopentadiene, cyclohexadiene, and derivatives thereof. These cyclic olefins may have a polar group as a substituent. Examples of the polar group include a hydroxyl group, a carboxyl group, an alkoxyl group, an epoxy group, a glycidyl group, an oxycarbonyl group, a carbonyl group, an amino group, an ester group, and a carboxylic acid anhydride group. Or a carboxylic anhydride group is preferred.

  Preferred cycloolefin resins may be those obtained by addition copolymerization of monomers other than cyclic olefins. Addition copolymerizable monomers include ethylene, propylene, 1-butene, 1-pentene, and other ethylene or α-olefins; 1,4-hexadiene, 4-methyl-1,4-hexadiene, 5-methyl- Examples include dienes such as 1,4-hexadiene and 1,7-octadiene.

The cyclic olefin is obtained by an addition polymerization reaction or a metathesis ring-opening polymerization reaction. The polymerization is carried out in the presence of a catalyst. Examples of the addition polymerization catalyst include a polymerization catalyst composed of a vanadium compound and an organoaluminum compound. As a catalyst for ring-opening polymerization, a polymerization catalyst comprising a metal halide such as ruthenium, rhodium, palladium, osmium, iridium, platinum, nitrate or acetylacetone compound, and a reducing agent; or titanium, vanadium, zirconium, tungsten, molybdenum And a polymerization catalyst composed of a metal halide such as acetylacetone compound and an organoaluminum compound. The polymerization temperature, pressure and the like are not particularly limited, but the polymerization is usually carried out at a polymerization temperature of -50 ° C to 100 ° C and a polymerization pressure of 0 to 490 N / cm ² .

  The cycloolefin resin according to the present invention is preferably a resin obtained by polymerizing or copolymerizing a cyclic olefin, followed by a hydrogenation reaction to change the unsaturated bond in the molecule to a saturated bond. The hydrogenation reaction is performed by blowing hydrogen in the presence of a known hydrogenation catalyst. Examples of hydrogenation catalysts include cobalt acetate / triethylaluminum, nickel acetylacetonate / triisobutylaluminum, transition metal compounds such as titanocene dichloride / n-butyllithium, zirconocene dichloride / sec-butyllithium, tetrabutoxytitanate / dimethylmagnesium / alkyl. Homogeneous catalyst consisting of a combination of metal compounds; heterogeneous metal catalyst such as nickel, palladium, platinum; nickel / silica, nickel / diatomaceous earth, nickel / alumina, palladium / carbon, palladium / silica, palladium / diatomaceous earth And a heterogeneous solid-supported catalyst in which a metal catalyst such as palladium / alumina is supported on a carrier.

  Or the following norbornene-type resin is also mentioned as a cycloolefin resin. The norbornene-based resin preferably has a norbornene skeleton as a repeating unit. Specific examples thereof include, for example, JP-A-62-252406, JP-A-62-2252407, and JP-A-2-133413. JP, JP 63-145324, JP 63-264626, JP 1-224017, JP 57-8815, JP 5-2108, JP 5-39403. JP-A-5-43663, JP-A-5-43834, JP-A-5-70655, JP-A-5-279554, JP-A-6-206985, JP-A-7-62028, JP-A-8-176411, JP-A-9-241484, JP-A-2001-277430, JP-A-2003-139 No. 50, JP-A No. 2003-14901, JP-A No. 2003-161832, JP-A No. 2003-195268, JP-A No. 2003-111588, JP-A No. 2003-211589, JP-A No. 2003-268187 Gazette, JP-A-2004-133209, JP-A-2004-309799, JP-A-2005-121183, JP-A-2005-164632, JP-A-2006-72309, JP-A-2006-178191, Although what was described in Unexamined-Japanese-Patent No. 2006-215333, Unexamined-Japanese-Patent No. 2006-268065, Unexamined-Japanese-Patent No. 2006-299199 etc. is mentioned, It is not limited to these. Moreover, these may be used individually by 1 type and may use 2 or more types together. Specifically, ZEONEX, ZEONOR manufactured by Nippon Zeon Co., Ltd., Arton manufactured by JSR Corporation, APPEL manufactured by Mitsui Chemicals, Inc. (APL8008T, APL6509T, APL6013T, APL5014DP, APL6015T) and the like are preferably used.

  The molecular weight of the cycloolefin polymer according to the present invention is appropriately selected depending on the purpose of use, but it is determined by a gel permeation chromatographic method using a cyclohexane solution (a toluene solution when the polymer resin is not dissolved). Isoprene or polystyrene-equivalent weight average molecular weight, usually in the range of 5000 to 500000, preferably 8000 to 200000, more preferably 10000 to 100000, the mechanical strength and molding processability of the molded body are highly balanced. Being preferred.

  Moreover, when a low-volatile antioxidant is blended at a ratio of 0.01 to 5 parts by mass with respect to 100 parts by mass of the cycloolefin polymer, it can effectively prevent the polymer from being decomposed or colored during the molding process. I can do it.

  The polycarbonate resin according to the present invention will be described. There are various types of polycarbonate resins, and aromatic polycarbonates are preferable from the viewpoint of chemical properties and physical properties, and bisphenol A polycarbonates are particularly preferable. Among them, more preferred is a bisphenol A derivative in which a benzene ring, a cyclohexane ring, or an aliphatic hydrocarbon group is introduced into bisphenol A, and these groups are introduced asymmetrically with respect to the central carbon. A polycarbonate having a structure in which the anisotropy in the unit molecule is reduced, obtained by using the obtained derivative is preferable. For example, one in which two methyl groups on the central carbon of bisphenol A are replaced with phenyl groups, and one hydrogen on each benzene ring of bisphenol A is substituted asymmetrically with respect to the central carbon with methyl groups or phenyl groups The polycarbonate resin obtained is preferable. Specifically, 4,4′-dihydroxydiphenylalkane or a halogen-substituted product thereof can be obtained by a phosgene method or a transesterification method. For example, 4,4′-dihydroxydiphenylmethane, 4,4′-dihydroxydiphenylethane 4,4'-dihydroxydiphenylbutane and the like. In addition, for example, polycarbonate resins described in JP-A-2006-215465, JP-A-2006-91836, JP-A-2005-121813, JP-A-2003-167121 and the like can be mentioned. It is done.

  The resin film made of the polycarbonate resin used in the present invention may be used by mixing with a transparent resin such as a polystyrene resin, a methyl methacrylate resin, or a cellulose acetate resin, or at least one of the cellulose acetate films. A polycarbonate resin may be laminated on the surface.

  The resin film made of a polycarbonate-based resin used in the present invention has a glass transition point (Tg) of 110 ° C. or higher and a water absorption rate (measured under conditions of 23 ° C. water and 24 hours) of 0.3% or less. It is better to use one. More preferably, Tg is 120 ° C. or higher and water absorption is 0.2% or less.

(Dope)
The solvent used in preparing the dope used in the solution casting method may be any solvent that can dissolve the resin, and may be mixed with other solvents even if it cannot be dissolved alone. As long as it can be dissolved, it can be used. In general, a mixed solvent composed of a good solvent and a poor solvent is used. For example, in the case of a cellulose ester resin, the good solvent and the poor solvent change depending on the acyl group substitution degree of the cellulose ester. For example, when acetone is used as the solvent, the cellulose ester acetate ester (acetyl group substitution degree 2.4), cellulose Acetate propionate is a good solvent, and cellulose acetate (acetyl group substitution degree 2.8) is a poor solvent. In the case of a cellulose ester resin, the preferable range of the mixing ratio of the good solvent and the poor solvent is 70 to 98% by mass for the good solvent and 2 to 30% by mass for the poor solvent.

  Since the good solvent and the poor solvent differ depending on the resin to be used, the case of cellulose ester resin will be described. Examples of the good solvent 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-propanol, 1,1 , 1,3,3,3-hexafluoro-2-propanol, 2,2,3,3,3-pentafluoro-1-propanol, nitroethane and the like, but organic halogen compounds such as methylene chloride, Dioxolane derivatives, methyl acetate, ethyl acetate, acetone and the like are mentioned as preferred organic solvents (that is, good solvents). That.

  Examples of the poor solvent 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, propyl acetate, and monochloro. Examples thereof include benzene, benzene, cyclohexane, tetrahydrofuran, methyl cellosolve, ethylene glycol monomethyl ether, and the like. These poor solvents can be used alone or in combination of two or more.

  Next, a method for preparing a dope using a cellulose ester resin will be described. As a method for dissolving the cellulose ester resin when preparing the dope, a general method can be used. When heating and pressurization are combined, it is possible to heat above the boiling point at normal pressure. It is preferable to stir and dissolve while heating at a temperature that is equal to or higher than the boiling point of the solvent at normal pressure and that the solvent does not boil under pressure, in order to prevent the generation of massive undissolved materials called gels and mamacos. In addition, a method in which a cellulose ester resin is mixed with a poor solvent and wetted or swollen, and then a good solvent is added and dissolved is also preferably used.

  The pressurization may be performed by a method of injecting an inert gas such as nitrogen gas or a method of increasing the vapor pressure of the solvent by heating. Heating is preferably performed from the outside. For example, a jacket type is preferable because temperature control is easy.

  The heating temperature with the addition of the solvent is preferably higher from the viewpoint of the solubility of the cellulose ester, but if the heating temperature is too high, the required pressure increases and the productivity deteriorates. A preferable heating temperature is 45 to 120 ° C, more preferably 60 to 110 ° C, and still more preferably 70 ° C to 105 ° C. The pressure is adjusted so that the solvent does not boil at the set temperature.

  Alternatively, a cooling dissolution method is also preferably used, whereby the cellulose ester resin can be dissolved in a solvent such as methyl acetate.

  Next, this cellulose ester resin solution is filtered using a suitable filter medium such as filter paper. As the filter medium, it is preferable that the absolute filtration accuracy is small in order to remove insoluble matters and the like. However, if the absolute filtration accuracy is too small, there is a problem that the filter medium is likely to be clogged. For this reason, a filter medium with an absolute filtration accuracy of 0.008 mm or less is preferable, a filter medium with 0.001 to 0.008 mm is more preferable, and a filter medium with 0.003 to 0.006 mm is still more preferable.

  There are no particular restrictions on the material of the filter medium, and ordinary filter media can be used. However, plastic filter media such as polypropylene and Teflon (registered trademark), and metal filter media such as stainless steel do not drop off fibers. preferable. It is preferable to remove and reduce impurities, particularly bright spot foreign matter, contained in the raw material cellulose ester by filtration.

Bright spot foreign matter is when two polarizing plates are placed in a crossed Nicol state, a cellulose ester film is placed between them, light is applied from the side of one polarizing plate, and observed from the side of the other polarizing plate. It is a point (foreign matter) where light from the opposite side appears to leak, and the number of bright spots having a diameter of 0.01 mm or more is preferably 200 / cm ² or less. More preferably, it is 100 pieces / cm < ² > or less, More preferably, it is 50 pieces / m < ² > or less, More preferably, it is 0-10 pieces / cm < ² > or less. Further, it is preferable that the number of bright spots of 0.01 mm or less is small.

  The dope can be filtered by a normal method, but the method of filtering while heating at a temperature not lower than the boiling point of the solvent at normal pressure and in a range where the solvent does not boil under pressure is the filtration pressure before and after filtration. The increase in the difference (called differential pressure) is small and preferable. A preferred temperature is 45 to 120 ° C, more preferably 45 to 70 ° C, and still more preferably 45 to 55 ° C.

  A smaller filtration pressure is preferred. The filtration pressure is preferably 1.6 MPa or less, more preferably 1.2 MPa or less, and further preferably 1.0 MPa or less.

(Plasticizer)
Although it does not specifically limit as a plasticizer, Phosphate ester plasticizer, phthalate ester plasticizer, trimellitic acid ester plasticizer, pyromellitic acid plasticizer, glycolate plasticizer, citrate plasticizer Polyester plasticizers can be preferably used. Examples of the phosphate ester include triphenyl phosphate, tricresyl phosphate, cresyl diphenyl phosphate, octyl diphenyl phosphate, diphenyl biphenyl phosphate, trioctyl phosphate, tributyl phosphate, and the like. Examples of the phthalic acid ester include diethyl phthalate, dimethoxyethyl phthalate, dimethyl phthalate, dioctyl phthalate, dibutyl phthalate, di-2-ethylhexyl phthalate, and butyl benzyl phthalate. Examples of trimellitic acid plasticizers include tributyl trimellitate, triphenyl trimellitate, triethyl trimellitate, and the like. Examples of the pyromellitic acid ester plasticizer include tetrabutyl pyromellitate, tetraphenyl pyromellitate, and tetraethyl pyromellitate. Examples of glycolic acid esters include triacetin, tributyrin, ethyl phthalyl ethyl glycolate, methyl phthalyl ethyl glycolate, and butyl phthalyl butyl glycolate. Examples of the citrate plasticizer include triethyl citrate, tri-n-butyl citrate, acetyl triethyl citrate, acetyl tri-n-butyl citrate, and acetyl tri-n- (2-ethylhexyl) citrate. 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 plasticizer can be added in an amount of 1 to 40% by mass, preferably 3 to 20% by mass, based on the cellulose ester resin. More preferably, it is 4 to 15% by 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 optical film according to 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 inorganic fine particles such as kaolin, talc, diatomaceous earth, quartz, calcium carbonate, barium sulfate, titanium oxide, and alumina, and alkaline earth metal salts such as calcium and magnesium may be added. Good.

  The optical film produced by the production method of the present invention can be used for a polarizing plate or a liquid crystal display member because of its high dimensional stability. In this case, the polarizing plate or the liquid crystal is prevented from being deteriorated. Therefore, 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 preferably used ultraviolet absorbers 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)
Although the specific example of a benzophenone series ultraviolet absorber is shown below, this invention is not limited to these. 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 it before adding it 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 an organic compound, polymers, such as a silicone resin, a fluororesin, and an acrylic resin, are preferable, for example, Among these, a 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 dispersing apparatus as described above includes an ultra-high pressure homogenizer (trade name: Microfluidizer) manufactured by Microfluidics Corporation or a nanomizer manufactured by Nanomizer, and other manton gorin type high-pressure dispersing apparatuses such as homogenizer manufactured by Izumi Food Machinery, Examples include UHN-01 manufactured by Wako 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 Japanese Patent No. 54672, Japanese Patent Publication Nos. 59-14735, 57-18175, 57-18176, 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- No. 56858, JP-A 61-27853, and 62-9346, a cationic pender having a cationic dissociation group in the side chain 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 as a clear or slightly turbid solution by visual observation but appears as a granular dispersion under an electron microscope.

  When the resin film is used as an optical film, the addition of the antistatic agent or the matting agent is preferably included in the surface layer portion (portion of 10 μm from the surface) of the optical film. It is preferable to contain an antistatic agent and / or a matting agent on the surface of the film. 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.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

Example 1
A cellulose ester film was produced by the method described below.

(Preparation of dope)
<Fine particle dispersion>
Fine particles (Aerosil R972V (manufactured by Nippon Aerosil Co., Ltd.)) 11 parts by mass (average primary particle diameter 16 nm, apparent specific gravity 90 g / liter)
89 parts by mass of ethanol or more was stirred and mixed with a dissolver for 50 minutes, and then dispersed with Manton Gorin.

<Fine particle additive solution>
The following cellulose ester resin was added to a dissolution tank containing methylene chloride and heated to completely dissolve, and this was then added to Azumi Filter Paper No. Azumi Filter Paper No. Filtered using 244. While finely stirring the filtered cellulose ester solution, the fine particle dispersion was slowly added thereto. Further, the particles were dispersed by an attritor so that the secondary particles had a predetermined particle size. This was filtered through Finemet NF manufactured by Nippon Seisen Co., Ltd. to prepare a fine particle additive solution.

Methylene chloride 99 parts by weight Cellulose acetate propionate (acetyl group substitution degree 1.5, propionyl group substitution degree 1.0, total acyl group substitution degree 2.5) 4 parts by weight Fine particle dispersion 11 parts by weight Main dope having the following composition Was prepared. First, methylene chloride and ethanol were added to the pressure dissolution tank. The cellulose ester resin was added to a pressurized dissolution tank containing a solvent while stirring. This was heated and stirred to completely dissolve, and a plasticizer and an ultraviolet absorber were further added and dissolved. This was designated as Azumi Filter Paper No. The main dope was prepared by filtration using 244.

  The main dope was added so as to be 100 parts by mass and 5 parts by mass of the fine particle additive solution, and sufficiently mixed with an in-line mixer (Toray static in-tube mixer Hi-Mixer, SWJ) to obtain a dope.

<Composition of main dope>
Methylene chloride 390 parts by mass Ethanol 80 parts by mass Cellulose acetate propionate (acetyl group substitution degree 1.5, propionyl group substitution degree 1.0, total acyl group substitution degree 2.5) 100 parts by mass Plasticizer: Triphenyl phosphate 8 Part by mass Plasticizer: 3 parts by weight of ethyl phthalyl ethylene glycolate UV absorber: Tinuvin 109 (manufactured by Ciba Specialty Chemicals Co., Ltd.)
1 part by mass UV absorber: Tinuvin 171 (manufactured by Ciba Specialty Chemicals)
1 part by mass In the composition of the main dope, methylene chloride is a good solvent and ethanol is a poor solvent.

(Manufacture of cellulose acetate propionate film)
When preparing the cellulose acetate propionate film through the casting process, the first drying process, the stretching process, the second drying process, and the winding process using the manufacturing apparatus shown in FIG. As shown, the amount of residual solvent in the width direction of the web from the time when it is peeled off from the endless belt support until the start of stretching in the stretching process is changed to 1800 mm in width, 40 μm in thickness, 5000 m in length, in the MD direction. A cellulose acetate propionate film having a stretch rate of 3% and a stretch rate in the TD direction of 8% was prepared under the conditions shown below. 101-103. Manufacturing conditions are shown below.

Conditions for starting casting The prepared dope was uniformly heated at a temperature of 35 ° C., a 2200 mm wide, wet dope film thickness of 100 μm on a stainless steel endless belt support with a width of 2300 mm and a length of 100 m, and a take-up speed of 40 m / min. It was cast into. A heating air was used as a heat source for the endless belt support. The temperature of the surface of the endless belt support indicates a temperature displayed by using a non-contact type thermometer as a measurement means and using a liquid crystal display device as a display means.

Separation conditions of the web from the endless belt support The web was peeled from the endless belt support at a set value of 200 N / m, and the total residual solvent amount of the web peeled from the endless belt support was 140% by mass.

  The value of the total residual solvent amount (% by mass) of the web peeled from the endless belt support is defined as B when the web having a total width of 100 mm × 100 mm is dried for 1 hour at 115 ° C. When the mass of the web is A, ((A−B) / B) × 100 = a value obtained by the amount of residual solvent (% by mass).

  The residual solvent amount at the edge of the web peeled from the endless belt support is the mass of the web when a 50 mm × 50 mm web cut from a 100 mm area from the edge of the web is dried at 115 ° C. for 1 hour. When C is C and the mass of the web before drying is D, ((D−C) / C) × 100 = a value obtained by the amount of residual solvent (% by mass).

  The amount of residual solvent in the central part of the web peeled from the endless belt support is the mass of the web when dried at 115 ° C. for 1 hour at a size of 50 mm × 50 mm cut from a location 100 mm from the edge of the web. When E is the weight of the web before drying, F is the value determined by ((FE) / E) × 100 = residual solvent amount (mass%).

  The ratio of the good solvent amount to the total residual solvent amount is a value measured under the following measurement conditions using a gas chromatography 5890 type SERISII and headspace sampler HP7694 manufactured by Hewlett-Packard Co., to which a headspace sampler is connected.

Headspace sampler heating conditions: 120 ° C, 20 minutes GC introduction temperature: 150 ° C
Temperature rise: 40 ° C, hold for 5 minutes → 100 ° C (8 ° C / min)
Column: J-W DB-WAX (inner diameter 0.32 mm, length 30 m)
Drying conditions of the first drying step The drying temperature of the first drying step was 60 ° C., the time was 1 minute, and the conveyance speed was 40 m / min. The stretch rate in the MD direction of the web from the time of peeling from the endless belt support to the start of stretching was 3%, and the stretch rate in the TD direction was −3%.

  The expansion / contraction rate in the MD direction is a value obtained from the conveyance speed at the start of stretching relative to the conveyance speed during casting. The expansion / contraction ratio in the TD direction is a value obtained from the film width at the start of stretching relative to the film width during casting.

Stretching conditions in the stretching process The surface temperature of the web at the start of stretching in the stretching process was 15 ° C. higher in the center in the width direction than in the edges. The tenter stretching apparatus used a clip tenter, and stretched in the TD direction so that the stretch rate in the TD direction of the cellulose acetate propionate film collected at the temperature of 150 ° C. and the winding process was 30%. The temperature in the stretching process was 150 ° C., the time was 0.5 minutes, and the conveyance speed was 40 m / min. The surface temperature of the web at the start of stretching was measured with a commercially available non-contact thermometer. The total residual solvent amount at the start of stretching, the residual solvent amount at the end, the residual solvent amount at the center, and the ratio of the good solvent amount to the total residual solvent amount are the total residual solvent amount of the web peeled from the endless belt support, the end portion The method was the same as the method for measuring the residual solvent amount, the central residual solvent amount, and the ratio of the good solvent amount to the total residual solvent amount.

Drying conditions of the second drying step The drying temperature of the second drying step was 120 ° C., the time was 20 minutes, and the conveyance speed was 40 m / min.

Winding process The winder was wound at a tension of 200 N / m using a constant tension method.

Evaluation Each sample No. Table 2 shows the results of evaluations according to the evaluation ranks shown below, which are determined by the methods shown below for transportability, crease, wrinkles, and scratches.

Evaluation method of transportability The state of the end of all m of the prepared sample was visually observed.

Evaluation rank of transportability ○: No breaks, tears, or elongation at the end △: No breaks, tears, or stretches at the ends. ×: The occurrence of breaks or tears in the ends can be seen everywhere. Measurement Method A 5 m portion was taken out of the prepared sample from 5000 m from the end of winding, and the presence or absence of a slip was visually measured under the following measurement conditions.

Evaluation rank of crease ○: No occurrence of crease Δ: Generation of crease is slightly conspicuous ×: Generation of crease is conspicuous When measuring each wrinkle, the presence or absence of wrinkle was visually confirmed.

Evaluation rank of wrinkle ○: No wrinkle generation Δ: Wrinkle generation is slightly noticeable ×: Wrinkle generation is conspicuous Scratch measurement method Out of 5000 m of the prepared sample, a 5 m portion is taken out from the end of winding, and the scratch is taken. The presence or absence of was confirmed visually.

Evaluation rank of scratches ○: No generation of scratches Δ: Slight generation of scratches is conspicuous ×: Generation of scratches is conspicuous

  The effectiveness of the present invention was confirmed.

Example 2
A cellulose acetate propionate film was produced by the method shown below.

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

(Manufacture of cellulose acetate propionate film)
When preparing the cellulose acetate propionate film using the manufacturing apparatus shown in FIG. 1 through the casting process, the first drying process, the stretching process, the second drying process, and the winding process, using the prepared dope, Table 3 The amount of residual solvent when the web is peeled from the endless belt support made of stainless steel is changed in the width direction, the width is 1800 mm, the thickness is 30 μm, the length is 5000 m, and the expansion / contraction ratio in the MD direction is 3%. A cellulose acetate propionate film having an expansion / contraction ratio in the TD direction of 8% was prepared under the conditions shown below. 201-207. Manufacturing conditions are shown below.

Conditions for starting casting The prepared dope was uniformly heated at a temperature of 35 ° C., a 2200 mm wide, wet wet dope film thickness of 75 μm on a stainless steel endless belt support having a width of 2400 mm and a length of 100 m, and a take-up speed of 40 m / min. It was cast into. A heating air was used as a heat source for the endless belt support. The temperature of the surface of the endless belt support indicates a temperature displayed by using a non-contact type thermometer as a measurement means and using a liquid crystal display device as a display means.

Separation condition of web from endless belt support The web was peeled from the endless belt support at a set value of 200 N / m. The total residual solvent amount of the web peeled from the endless belt support was 140% by mass. The total residual solvent amount of the peeled web, the ratio of the good solvent amount to the residual solvent amount, and the residual solvent amounts at the ends and the central portion are values measured by the same method as in Example 1.

Drying conditions of the first drying step The drying temperature of the first drying step was 60 ° C., the time was 1 minute, and the conveyance speed was 40 m / min. The stretch rate in the MD direction of the web from when the web was peeled off from the endless belt support to the start of stretching was 3%, and the stretch rate in the TD direction was −3%. The expansion / contraction rate in the MD direction and the expansion / contraction rate in the TD direction are values obtained by the same method as in Example 1.

Stretching conditions in the stretching process The surface temperature of the web at the start of stretching in the stretching process was 15 ° C. higher in the center in the width direction than in the edges. The tenter stretching apparatus used a clip tenter, and stretched in the TD direction so that the stretch rate in the TD direction of the cellulose acetate propionate film collected at the temperature of 150 ° C. and the winding process was 30%. The temperature in the stretching process was 150 ° C., the time was 0.5 minutes, and the conveyance speed was 40 m / min.

  The total residual solvent amount at the start of stretching is the method of measuring the total residual solvent amount of the web peeled from the wide endless belt support and the residual solvent amount of the end portion and the central portion. Done in the same way. The ratio of the good solvent amount to the total residual solvent amount is a value obtained by the same method as in Example 1. The surface temperature of the web at the start of stretching is a value measured by the same method as in Example 1.

Drying conditions of the second drying step The drying temperature of the second drying step was 120 ° C., the time was 20 minutes, and the conveyance speed was 40 m / min.

Winding process The winder was wound at a tension of 200 N / m using a constant tension method.

Evaluation Each sample No. Table 4 shows the results obtained by determining transportability, creases, wrinkles, and scratches 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 3
A cellulose acetate propionate film was produced by the method shown below.

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

(Manufacture of cellulose acetate propionate film)
When preparing the cellulose acetate propionate film through the casting process, the first drying process, the stretching process, the second drying process, and the winding process using the manufacturing apparatus shown in FIG. As shown in FIG. 1, the total residual solvent amount when the web is peeled from the endless belt support and the ratio of the good solvent amount to the total residual solvent amount are changed, and the width is 1800 mm, the thickness is 50 μm, the length is 5000 m, and the MD direction. A cellulose acetate propionate film having a stretch rate of 3% and a stretch rate in the TD direction of 8% was prepared under the conditions shown below. 301 to 314. Manufacturing conditions are shown below.

Casting start conditions The prepared dope was uniform at a temperature of 35 ° C., a 2200 mm wide, wet dope film thickness of 125 μm on a stainless steel endless belt support having a width of 2300 mm and a length of 100 m, and a take-up speed of 40 m / min. It was cast into. A heating air was used as a heat source for the endless belt support. The temperature of the surface of the endless belt support indicates a temperature displayed by using a non-contact type thermometer as a measurement means and using a liquid crystal display device as a display means.

Separation condition of web from endless belt support The peeling tension from the endless belt support was set at a set value of 200 N / m. The total residual solvent amount of the peeled web, the ratio of the good solvent amount to the residual solvent amount, and the residual solvent amounts at the ends and the central portion are values measured by the same method as in Example 1.

Drying conditions of the first drying step The drying temperature of the first drying step was 60 ° C., the time was 1 minute, and the conveyance speed was 40 m / min. The stretch rate in the MD direction of the web from when the web was peeled off from the endless belt support to the start of stretching was 3%, and the stretch rate in the TD direction was −3%. The expansion / contraction rate in the MD direction and the expansion / contraction rate in the TD direction are values obtained by the same method as in Example 1.

Stretching conditions in the stretching process The surface temperature of the web at the start of stretching in the stretching process was 15 ° C. higher in the center in the width direction than in the edges. The tenter stretching apparatus used a clip tenter, and stretched in the TD direction so that the stretch rate in the TD direction of the cellulose acetate propionate film collected at the temperature of 150 ° C. and the winding process was 30%. The temperature in the stretching process was 150 ° C., the time was 0.5 minutes, and the conveyance speed was 40 m / min.

  The same method as the method for measuring the total residual solvent amount at the start of stretching, the residual solvent amount at the end and the center, the total residual solvent amount of the web peeled from the wide endless belt support, and the residual solvent amount at the end and the center. I went there. The ratio of the good solvent amount to the total residual solvent amount is a value obtained by the same method as in Example 1. The surface temperature of the web at the start of stretching is a value measured by the same method as in Example 1.

Drying conditions of the second drying step The drying temperature of the second drying step was 120 ° C., the time was 20 minutes, and the conveyance speed was 40 m / min.

Winding process The winder was wound at a tension of 200 N / m using a constant tension method.

Evaluation Each sample No. Table 6 shows the results of evaluations according to the same evaluation rank as in Example 1 with respect to 301 to 314, the transportability, crease, wrinkles, and scratches were determined by the same method as in Example 1.

  The effectiveness of the present invention was confirmed.

Example 4
A cellulose acetate propionate film was produced by the method shown below.

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

(Manufacture of cellulose acetate propionate film)
When preparing the cellulose acetate propionate film using the manufacturing apparatus shown in FIG. 1 through the casting process, the first drying process, the stretching process, the second drying process, and the winding process using the manufacturing apparatus shown in FIG. As shown in Fig. 2, the amount of residual solvent in the web at the start of stretching is changed in the width direction, the width is 1800 mm, the thickness is 40 μm, the length is 5000 m, the MD stretch rate is 3%, and the TD stretch rate is 8%. A cellulose acetate propionate film was prepared under the conditions shown below and sample no. 401 to 407. Manufacturing conditions are shown below.

Casting start conditions The prepared dope was uniform at a temperature of 35 ° C., a 2200 mm wide, wet dope film thickness of 100 μm on a stainless steel endless belt support with a width of 2200 mm and a length of 100 m, and a take-up speed of 40 m / min. It was cast into. A heating air was used as a heat source for the endless belt support. The temperature of the surface of the endless belt support indicates a temperature displayed by using a non-contact type thermometer as a measurement means and using a liquid crystal display device as a display means.

Separation condition of web from endless belt support The peeling tension from the endless belt support was set at a set value of 200 N / m. The total residual solvent amount of the web peeled from the endless belt support, the ratio of the good solvent amount to the total residual solvent amount, and the residual solvent amounts at the end portion and the central portion are values measured by the same method as in Example 1.

Drying conditions of the first drying step The drying temperature of the first drying step was 60 ° C., the time was 1 minute, and the conveyance speed was 40 m / min. The stretch rate in the MD direction of the web from when the web was peeled off from the endless belt support to the start of stretching was 3%, and the stretch rate in the TD direction was −3%. The expansion / contraction rate in the MD direction and the expansion / contraction rate in the TD direction are values obtained by the same method as in Example 1.

Stretching conditions in the stretching process The surface temperature of the web at the start of stretching in the stretching process was 15 ° C. higher in the center in the width direction than in the edges. The tenter stretching apparatus used a clip tenter, and stretched in the TD direction so that the stretch rate in the TD direction of the cellulose acetate propionate film collected at the temperature of 150 ° C. and the winding process was 30%. The temperature in the stretching process was 150 ° C., the time was 0.5 minutes, and the conveyance speed was 40 m / min.

  The total residual solvent amount at the start of stretching, the ratio of the good solvent amount to the total residual solvent amount, and the residual solvent amount at the end and the center are the total residual solvent amount of the web peeled from the endless belt support, and the total residual solvent amount. The measurement was performed in the same manner as the method for measuring the ratio of the good solvent amount and the residual solvent amount at the end and the center. The surface temperature of the web at the start of stretching is a value measured by the same method as in Example 1.

Drying conditions of the second drying step The drying temperature of the second drying step was 120 ° C., the time was 20 minutes, and the conveyance speed was 40 m / min.

Winding process The winder was wound at a tension of 200 N / m using a constant tension method.

Evaluation Each sample No. Table 8 shows the results of obtaining the transportability, crease, wrinkle, and scratches 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 5
A cellulose acetate propionate film was produced by the method shown below.

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

(Manufacture of cellulose acetate propionate film)
When preparing the cellulose acetate propionate film through the casting process, the first drying process, the stretching process, the second drying process, and the winding process using the manufacturing apparatus shown in FIG. As shown in FIG. 1, the total residual solvent amount of the web at the start of stretching and the ratio of the good solvent amount to the total residual solvent amount are changed, and the width is 1800 mm, the thickness is 60 μm, the length is 5000 m, and the expansion / contraction ratio in the MD direction is 3. %, A cellulose acetate propionate film having a stretching ratio in the TD direction of 8% was prepared under the conditions shown below. 501-514. Manufacturing conditions are shown below.

Conditions for starting casting The prepared dope was uniformly cast at a temperature of 35 ° C. on a 2200 mm wide, 100 m long endless belt support with a 2200 mm wide wet film thickness of 100 μm and a take-up speed of 40 m / min. did. A heating air was used as a heat source for the endless belt support. The temperature of the surface of the endless belt support indicates a temperature displayed by using a non-contact type thermometer as a measurement means and using a liquid crystal display device as a display means.

Separation condition of web from endless belt support The peeling tension from the endless belt support was set at a set value of 200 N / m. The total residual solvent amount of the web peeled from the endless belt support, the ratio of the good solvent amount to the total residual solvent amount, and the residual solvent amounts at the end portion and the central portion are values measured by the same method as in Example 1.

Drying conditions of the first drying step The drying temperature of the first drying step was 60 ° C., the time was 1 minute, and the conveyance speed was 40 m / min. The stretch rate in the MD direction of the web from when the web was peeled off from the endless belt support to the start of stretching was 3%, and the stretch rate in the TD direction was −3%. The expansion / contraction rate in the MD direction and the expansion / contraction rate in the TD direction are values obtained by the same method as in Example 1.

Stretching conditions in the stretching process The surface temperature of the web at the start of stretching in the stretching process was 15 ° C. higher in the center in the width direction than in the edges. The tenter stretching apparatus used a clip tenter, and stretched in the TD direction so that the stretch rate in the TD direction of the cellulose acetate propionate film collected at the temperature of 150 ° C. and the winding process was 30%. The temperature in the stretching process was 150 ° C., the time was 0.5 minutes, and the conveyance speed was 40 m / min.

  The total residual solvent amount at the start of stretching and the ratio of the good solvent amount to the total residual solvent amount are values obtained by the same method as in Example 1. The surface temperature of the web at the start of stretching is a value measured by the same method as in Example 1.

Drying conditions of the second drying step The drying temperature of the second drying step was 120 ° C., the time was 20 minutes, and the conveyance speed was 40 m / min.

Winding process The winder was wound at a tension of 200 N / m using a constant tension method.

Evaluation Each sample No. Table 10 shows the results of evaluations according to the same evaluation rank as in Example 1 with respect to 501 to 514, in which the transportability, crease, wrinkles, and scratches were determined by the same method as in Example 1.

  The effectiveness of the present invention was confirmed.

Example 6
A cellulose acetate propionate film was produced by the method shown below.

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

(Manufacture of cellulose acetate propionate film)
When preparing the cellulose acetate propionate film through the casting process, the first drying process, the stretching process, the second drying process, and the winding process using the manufacturing apparatus shown in FIG. As shown, the surface temperature of the endless belt support is changed, the width is 1800 mm, the thickness is 70 μm, the length is 5000 m, the MD stretch rate is 3%, and the TD stretch rate is An 8% cellulose acetate propionate film was prepared under the conditions shown below and sample No. 601-607. Manufacturing conditions are shown below.

Conditions for starting casting The prepared dope was uniformly cast at a temperature of 35 ° C. on a 2200 mm wide, 100 m long endless belt support with a 2200 mm wide wet film thickness of 100 μm and a take-up speed of 40 m / min. did. A heating air was used as a heat source for the endless belt support. The temperature of the surface of the endless belt support indicates a temperature displayed by using a non-contact type thermometer as a measurement means and using a liquid crystal display device as a display means.

Separation condition of web from endless belt support The peeling tension from the endless belt support was set at a set value of 200 N / m. The total residual solvent amount of the web peeled from the endless belt support, the ratio of the good solvent amount to the total residual solvent amount, and the residual solvent amounts at the end portion and the central portion are values measured by the same method as in Example 1.

Drying conditions of the first drying step The drying temperature of the first drying step was 60 ° C., the time was 1 minute, and the conveyance speed was 40 m / min. The stretch rate in the MD direction of the web from when the web was peeled off from the endless belt support to the start of stretching was 3%, and the stretch rate in the TD direction was −3%. The expansion / contraction rate in the MD direction and the expansion / contraction rate in the TD direction are values obtained by the same method as in Example 1.

Stretching conditions in the stretching process The surface temperature of the web at the start of stretching in the stretching process was 15 ° C. higher in the center in the width direction than in the edges. The tenter stretching apparatus used a clip tenter, and stretched in the TD direction so that the stretch rate in the TD direction of the cellulose acetate propionate film collected at the temperature of 150 ° C. and the winding process was 30%. The temperature in the stretching process was 150 ° C., the time was 0.5 minutes, and the conveyance speed was 40 m / min.

  The total residual solvent amount at the start of stretching, the ratio of the good solvent amount to the total residual solvent amount, and the residual solvent amount at the end and the center are the total residual solvent amount of the web peeled from the endless belt support, and the total residual solvent amount. The measurement was performed in the same manner as the method for measuring the ratio of the good solvent amount and the residual solvent amount at the end and the center.

Drying conditions of the second drying step The drying temperature of the second drying step was 120 ° C., the time was 20 minutes, and the conveyance speed was 40 m / min.

Winding process The winder was wound at a tension of 200 N / m using a constant tension method.

Evaluation Each sample No. Table 12 shows the results of evaluations according to the same evaluation rank as in Example 1, with the transportability, crease, wrinkles, and scratches determined in accordance with the same evaluation rank as in Example 1.

  The effectiveness of the present invention was confirmed.

Example 7
A cellulose acetate propionate film was produced by the method shown below.

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

(Manufacture of cellulose acetate propionate film)
When preparing the cellulose acetate propionate film through the casting process, the first drying process, the stretching process, the second drying process, and the winding process using the manufacturing apparatus shown in FIG. As shown in Fig. 2, the web surface temperature from the endless belt support to the start of stretching is changed, the width is 1800 mm, the thickness is 40 μm, the length is 5000 m, the MD stretch rate is 3%, and the TD stretch rate is A cellulose acetate propionate film having a rate of 8% was prepared under the conditions shown below and sample No. 701-716. Manufacturing conditions are shown below.

Conditions for starting casting The prepared dope was uniformly cast at a temperature of 35 ° C. on a 2200 mm wide, 100 m long endless belt support with a 2200 mm wide wet film thickness of 100 μm and a take-up speed of 40 m / min. did. A heating air was used as a heat source for the endless belt support. The temperature of the surface of the endless belt support indicates a temperature displayed by using a non-contact type thermometer as a measurement means and using a liquid crystal display device as a display means.

Separation condition of web from endless belt support The peeling tension from the endless belt support was set at a set value of 200 N / m. The total residual solvent amount of the web peeled from the endless belt support, the ratio of the good solvent amount to the total residual solvent amount, and the residual solvent amounts at the end portion and the central portion are values measured by the same method as in Example 1.

Drying conditions of the first drying step The drying temperature of the first drying step is such that the temperature at the edge and center of the width direction shown in Table 13 when the web enters the stretching step is the edge and center of the drying box. The temperature was adjusted to 1 hour, and the conveyance speed was 40 m / min. The stretch rate in the MD direction of the web from when the web was peeled off from the endless belt support to the start of stretching was 3%, and the stretch rate in the TD direction was −3%. The expansion / contraction rate in the MD direction and the expansion / contraction rate in the TD direction are values obtained by the same method as in Example 1. The expansion / contraction rate in the MD direction and the expansion / contraction rate in the TD direction are values obtained by the same method as in Example 1.

Stretching conditions in the stretching process The tenter stretching apparatus used a clip tenter, and stretched in the TD direction so that the cellulose acetate propionate film collected in the winding process had a stretching ratio of 30% in the TD direction. The temperature in the stretching process was 150 ° C., the time was 0.5 minutes, and the conveyance speed was 40 m / min. The surface temperature of the web at the start of stretching in the stretching process is a value measured by the same method as in Example 1. The total residual solvent amount at the start of stretching and the ratio of the good solvent amount to the total residual solvent amount are values obtained by the same method as in Example 1.

Drying conditions of the second drying step The drying temperature of the second drying step was 120 ° C., the time was 20 minutes, and the conveyance speed was 40 m / min.

Winding process The winder was wound at a tension of 200 N / m using a constant tension method.

Evaluation Each sample No. Table 14 shows the results of evaluations according to the same evaluation rank as in Example 1 with respect to 701 to 706, the transportability, crease, wrinkles, and scratches obtained by the same method as in Example 1.

  The effectiveness of the present invention was confirmed.

Example 8
Production of liquid crystal display device (Production of polarizing plate)
A polyvinyl alcohol film having a thickness of 120 μm was uniaxially stretched (temperature: 110 ° C., stretch ratio: 5 times). This was immersed in an aqueous solution composed of 0.075 g of iodine, 5 g of potassium iodide and 100 g of water for 60 seconds, and then immersed in an aqueous solution of 68 ° C. composed of 6 g of potassium iodide, 7.5 g of boric acid and 100 g of water. This was washed with water and dried to obtain a polarizer.

  Next, the cellulose acetate propionate film No. 1 prepared in Example 1 and the polarizer according to the following steps 1 to 5 was used. 101 to 103 are bonded together to produce a polarizing plate having the structure shown in FIG. 8-1, 8-2, and 8-3.

  Step 1: Soaked in a 1 mol / L sodium hydroxide solution at 50 ° C. for 60 seconds, then washed with water and dried to obtain a cellulose acetate propionate film saponified on the side to be bonded to the polarizer.

  Process 2: The said polarizer was immersed in the polyvinyl alcohol adhesive tank of 2 mass% of solid content for 1-2 seconds.

  Step 3: Excess adhesive adhered to the polarizer in Step 2 was gently wiped off, and the cellulose acetate propionate film treated in Step 1 was laminated and arranged on the upper and lower sides.

Step 4: The cellulose acetate propionate film and the polarizing film laminated in Step 3 were bonded at a pressure of 20 to 30 N / cm ² and a conveying speed of about 2 m / min, and then dried for 2 minutes to produce a polarizing plate. .

  After that, the polarizing plate of a commercially available liquid crystal TV (Sharp Aquos 32AD5) was peeled off, and each polarizing plate No. 8-1, 8-2, and 8-3 were each bonded to the glass surface of the liquid crystal cell to prepare a liquid crystal display device. 801, 802, and 803. At that time, the polarizing plate protective film prepared as described above was placed on the liquid crystal cell surface side, and the direction of bonding of the polarizing plate was such that the absorption axis was in the same direction as the previously bonded polarizing plate.

Evaluation The liquid crystal display device No. 801, 802, 803 in the environment of 23 ° C 55% RH, turn on the backlight of the liquid crystal TV display device of the manufactured liquid crystal display device and leave it for 30 minutes, then visually evaluate the visibility by the following method The results are shown in Table 15.

Screen Visibility Evaluation Method The backlight of the manufactured liquid crystal display device was continuously lit for 100 hours in a bright room, and the visibility at the initial stage of lighting and the visibility after 100 hours were visually evaluated.

Evaluation rank of screen visibility ○: Black appears to be crisp and clear △: No blackness, slightly sharpness ×: No blackness, low clarity

  The effectiveness of the present invention was confirmed.

It is the schematic of the manufacturing apparatus of the film for optics by the solution casting method which used the endless belt support body and has arrange | positioned the 1st drying process by a roll conveyance system. It is a general | schematic expanded sectional view along BB 'of Fig.1 (a). It is an expansion schematic sectional drawing of the casting process shown in FIG.1 (b). It is the schematic of the manufacturing apparatus of the film for optics by the solution casting method which used the endless belt support body and arrange | positioned the 1st drying process by a tenter conveyance system. It is the schematic of the manufacturing apparatus of the film for optics by the solution casting method which used the endless belt support body and arrange | positioned MD extending process. It is a schematic diagram of the polarizing plate produced using the optical film manufactured with the manufacturing method of this invention as a protective film. It is a model exploded block diagram of the liquid crystal display device using the polarizing plate produced using the optical film manufactured by this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1a, 1b, 1c Manufacturing apparatus 101 Casting process 101a Endless belt support 101b Die 102, 102 '1st drying process 102a, 104a Drying box 102'd Tenter conveyance apparatus 103 Stretching process 103' MD stretching process 103'a Conveying part 103'b, 103'c Feed roll 103'd Heating device 103c, 102'c, 103'd1 Outer box 103d Tenter stretching device 104 Second drying step 105 Winding step 2 Dope 3 Peeling roll 4 Web 5 Optical film 6 , 702 Polarizing plate 601, 702a Polarizer 602, 702b Protective film 7 Liquid crystal display device 701 Liquid crystal cell

Claims (11)

A dope prepared by dissolving a raw material resin in a solvent is cast on an endless belt support from a die to form a web, and after peeling the web from the endless belt support, at least a stretching step, and drying In the method for producing an optical film for producing a thin optical film by a solution casting production apparatus having a step and a winding step,
Production of an optical film, characterized in that the amount of residual solvent in the width direction of the web from the time of peeling from the endless belt support to the start of stretching in the stretching process is made lower at the center than at the ends. Method. The amount of residual solvent when the web is peeled from the endless belt support has a wide distribution, and the central portion of the web is 5 mass% to 50 mass% lower than the end portion. The manufacturing method of the optical film as described in any one of Claims 1-3. The total residual solvent amount when the web is peeled from the endless belt support is 70% by mass to 170% by mass, and the ratio of the good solvent amount to the total residual solvent amount is 10% to 70%. The manufacturing method of the optical film of any one of Claim 1 or 2. The residual solvent amount of the web at the start of stretching has a wide distribution, and the central part of the web is 2% by mass to 20% by mass lower than the end part. 2. A method for producing an optical film according to item 1. The total residual solvent amount at the start of stretching is 10% by mass to 30% by mass, and the ratio of the good solvent amount to the total residual solvent amount is 5% to 50%. The manufacturing method of the optical film of any one of these. The surface of the endless belt support is set such that the temperature at the center in the width direction is higher than the temperature at the end in the width direction. Manufacturing method for optical film. The temperature of the center portion in the width direction of the endless belt support on the surface of the endless belt support is 1 ° C to 30 ° C higher than the temperature of the end in the width direction. The manufacturing method of the optical film of any one of these. The surface temperature of the web from the time when the web is peeled off from the endless belt support to the start of stretching is 1 to 20 ° C higher at the center in the width direction than at the end. 8. The method for producing an optical film as described in any one of 7 above. An optical film produced by the method for producing an optical film according to claim 1. A polarizing plate comprising the optical film according to claim 9 disposed on at least one surface of a polarizer. A liquid crystal display device using the polarizing plate according to claim 10.

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