JP2008191217A - Manufacturing method of retardation film, retardation film, polarizing plate and liquid crystal display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a retardation film with which a manufacturing apparatus, requiring no large size and no complicated administration of a stretching apparatus, is used and a retardation value in a width direction is stable, and further to provide a retardation film manufactured using this manufacturing method, a polarizing plate that uses the retardation film and a liquid crystal display that uses the polarizing plate. <P>SOLUTION: In the manufacturing method of the retardation film by a solution casting method where stretching treatment by an uniaxially stretching apparatus is performed, there is a transport step of a web, after being peeled from an endless support to the uniaxially stretching apparatus by a transportation roll of 0.8 to 2.0 μm surface roughness (Ra), while the solvent remaining amount in the web is in between 40 mass% and 110 mass%. The uniaxially stretching apparatus performs stretching of the web by 10 to 35% in the transport direction of the web (MD direction) or in a direction normal to the transportat direction (a TD direction). <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

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

  Liquid crystal display devices are widely used as display devices for liquid crystal TVs, personal computers, and the like because they can be directly connected to an IC circuit with low voltage and low power consumption, and can be particularly thin. 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.

  In such a liquid crystal display device, from the viewpoint of contrast or the like, a conventional liquid crystal display device using a twisted nematic (TN) with a twist angle of 90 degrees and a super twisted nematic (STN) with a twist angle of 160 degrees or more are used. Liquid crystal display devices have been developed. Recently, however, a vertical alignment (vertical alignment, VA for short) type liquid crystal display device disclosed in, for example, Japanese Patent Laid-Open No. 2-176625 has been developed. The VA type liquid crystal display device uses a so-called vertical alignment mode liquid crystal cell to display black firmly as black, has high contrast, and has a relatively wide viewing angle compared to TN and STN type. have.

  However, as the liquid crystal screen becomes larger as in a large TV, there is a growing demand for further widening the viewing angle, and a retardation film has been used for widening the viewing angle. Therefore, with the expansion of the liquid crystal screen, it is increasingly important to widen the retardation film. However, when a retardation film having a wide width of 1200 mm to 2700 mm and a thickness of 20 μm to 80 μm is produced by a solution casting method, after peeling from the endless support, shrinkage occurs due to the influence of the residual solvent. As the shift of the slow axis is not uniform, there is a problem that it is difficult to obtain uniform retardation values.

  When producing a retardation film by the solution casting method, studies have been made on the uniformity of the retardation value. For example, when a cellulose ester film is produced by a solution casting method, an apparatus having a first tenter and a second tenter is used, and after peeling the web from the endless support, the stretch ratio in the width direction is included in the web. A technique for stabilizing the retardation value by changing the first tenter and the second tenter in accordance with the amount of the residual solvent is disclosed (for example, see Patent Document 1). When a cellulose ester film is produced by the solution casting method, a device having a first tenter and a second tenter is used, and after peeling the web from the endless support, the amount of residual solvent at the edge and center of the web A technique is disclosed in which the retardation value is stabilized by stretching in the transverse direction by changing the temperature, and further stretching at a temperature 1 to 50 ° C. higher than the temperature of the first tenter (for example, Patent Document 2). reference.).

  However, although the techniques described in Patent Documents 1 and 2 are improved to some extent, they are still insufficient when used for a liquid crystal screen like a large TV. In addition, since there are two tenters in the process, the management of each tenter becomes complicated, and the entire apparatus becomes large.

From such a situation, a manufacturing method for a retardation film having a stable retardation value in the width direction using a manufacturing apparatus that does not require a complicated management of a stretching apparatus without increasing the manufacturing apparatus, and this manufacturing Development of a retardation film produced by the method, a polarizing plate using the retardation film, and a liquid crystal display device using the polarizing plate is desired.
JP 2002-31245 A JP 2002-296422 A

  The present invention has been made in view of the above situation, and its purpose is to use a manufacturing apparatus that does not require a complicated management of the stretching apparatus without increasing the manufacturing apparatus, and has a retardation value in the width direction. It is providing the manufacturing method of the stable retardation film, the retardation film manufactured by this manufacturing method, the polarizing plate using this retardation film, and the liquid crystal display device using this polarizing plate.

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

  1. A solution in which a liquid obtained by dissolving a raw material resin in a solvent is cast on an endless support to form a web, the web is peeled off from the endless support, and then stretched by a uniaxial stretching apparatus, and then the solvent is removed. In the method for producing a retardation film by a casting method, after peeling the web from the endless support, until the uniaxial stretching apparatus, the residual solvent amount of the web is between 40% by mass and 110% by mass, It has a conveyance process by a conveyance roll having a surface roughness (Ra) of 0.8 μm to 2.0 μm, and in the uniaxial stretching apparatus, the web conveyance direction (MD direction) or a direction perpendicular to the conveyance direction (TD direction) And a method for producing a retardation film, wherein the film is stretched by 10% to 35%.

  2. 2. The method for producing a retardation film as described in 1 above, wherein a width of the retardation film is from 1200 mm to 2700 mm.

  3. 2. The method for producing a retardation film as described in 1 above, wherein the thickness of the retardation film is from 20 μm to 80 μm.

  4). 4. The method for producing a retardation film according to any one of 1 to 3, wherein the raw resin is a cellulose ester resin.

  5. 4. The method for producing a retardation film according to any one of 1 to 3, wherein the raw resin is a cycloolefin resin.

  6). 4. The method for producing a retardation film according to any one of 1 to 3, wherein the raw resin is a polycarbonate-based resin.

  7. A retardation film produced by the method for producing a retardation film according to any one of 1 to 6 above.

  8). A polarizing plate, wherein the polarizing plate is disposed on at least one surface of a polarizer so that a slow axis of the retardation film described in 7 is perpendicular or parallel to a transmission axis of the polarizer.

  9. 9. A liquid crystal display device using the polarizing plate described in 8 above.

  A manufacturing method for a retardation film in which the retardation value in the width direction is stable without using a manufacturing device that does not require a complicated management of the stretching device without increasing the manufacturing device, and the manufacturing method of this retardation method. A phase difference film, a polarizing plate using the retardation film, and a liquid crystal display device using the polarizing plate can be provided, and a high quality retardation film that can be used for a liquid crystal screen such as a large TV is manufactured. It became possible to do.

  Embodiments of the present invention will be described with reference to FIGS. 1 to 5, but the present invention is not limited thereto.

  FIG. 1 is a schematic view of an apparatus for producing a retardation film by a solution casting film forming method. FIG. 1A is a schematic perspective view of an apparatus for producing a retardation film by a solution casting film forming method in a case where a tenter is conveyed after casting and then dried in a drying process. FIG.1 (b) is a schematic sectional drawing in alignment with AA 'of Fig.1 (a).

  In the figure, reference numeral 1a denotes an apparatus for producing a retardation film by a solution casting film forming method. The manufacturing apparatus 1a includes a solution casting film forming process 101, a stretching process 102, a drying process 103, and a winding recovery process 104. The solution casting film forming step 101 includes a mirror-like metal casting belt (hereinafter referred to as a belt) 101a, a die 101b, and a heating device 101c as an endless support. The belt 101a is composed of an endless support that travels endlessly. The dice 101b is disposed to cast the dope 2 in which a resin for forming a retardation film is dissolved in a solvent onto the belt 101a. The heating device 101c is disposed to remove the solvent so that the dope 2 cast on the belt 101a can be peeled from the belt 101a.

  The concentration of the resin for forming the retardation film of the dope 2 is preferably higher because the drying load after casting on the metal support can be reduced, but when the concentration of the resin for forming the retardation film is too high. The load at the time of filtration increases, resulting in poor filtration accuracy. As a density | concentration which makes these compatible, 10-35 mass% is preferable, More preferably, it is 15-25 mass%.

  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. Although the heating device 101c shown in this figure shows the case where heating air is used, the heating means is not particularly limited. In addition, for example, a method of heating the dope contact surface of the belt with an infrared heater, the back surface of the belt There are a method in which warm air is blown onto the belt and heated from the back side, a method in which warm water or heating oil is brought into contact with the back side of the belt and heated. The time from casting to peeling varies depending on the film thickness of the cellulose ester film to be produced and the solvent used, but it takes 0.5 minutes in consideration of peelability from the belt, film-forming efficiency, process length, etc. A range of ˜5 minutes is preferred.

  As the endless support to be used, a mirror-finished surface is preferable, and a stainless steel belt or a drum whose surface is plated with a casting is preferably used. The casting width can be 1 to 4 m. The surface temperature of the endless support in the solution casting film forming step is set to −50 ° C. to a temperature at which the solvent boils and does not 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. A preferable endless support temperature is appropriately determined at 0 to 100 ° C, and more preferably 5 to 30 ° C. Alternatively, it is also a preferable method that the web is gelled by cooling and peeled from the drum in a state containing a large amount of residual solvent. The method for controlling the temperature of the endless support is not particularly limited, and there are a method of blowing hot air or cold air, and a method of contacting hot water with the back side of the metal support. It is preferable to use warm water because heat transfer is performed efficiently, so that the time until the temperature of the endless support becomes constant is short. When using warm air, considering the temperature drop of the web due to the latent heat of vaporization of the solvent, while using warm air above the boiling point of the solvent, there may be cases where wind at a temperature higher than the target temperature is used while preventing foaming. . In particular, it is preferable to perform drying efficiently by changing the temperature of the support and the temperature of the drying air during the period from casting to peeling.

  The belt 101a is held by the holding roll 101a1 and the holding roll 101a2, and rotates and moves between the holding roll 101a1 and the holding roll 101a2 (in the direction of the arrow in the drawing) as the holding roll rotates. Reference numeral 3 denotes a peeling point at which the solvent is removed from the dope cast on the belt 101a to a state where it can be peeled and the solidified web is peeled off. The temperature at the peeling point is preferably −50 to 40 ° C., more preferably 10 to 40 ° C., and most preferably 15 to 30 ° C. 4 shows the conveyance roll provided in the peeling point. 5 shows the peeled web. When the web 5 is peeled from the belt, the web is stretched in the longitudinal direction by the peeling tension and the subsequent conveying tension. Therefore, in the present invention, when peeling the web from the belt, the peeling and conveying tensions are lowered as much as possible. Preferably it is done. Specifically, for example, it is effective to set it to 50 to 170 N / m or less. At that time, it is preferable to apply a cold air of 20 ° C. or less to fix the web rapidly in order to enhance the effect of the present invention.

  In the case of the manufacturing apparatus shown in this figure, the web 5 peeled off at the peeling point is sent to the next stretching step 102. The amount of residual solvent contained in the web 5 when it is sent to the stretching step 102 is 15 mass% to 40 mass%. If the amount of residual solvent is less than 15% by mass, it is not preferable because the target stretching ratio cannot be obtained in the stretching step, and the required retardation value cannot be obtained. If the amount of residual solvent exceeds 40% by mass, the web will shrink immediately after peeling from the belt, and the desired stretching ratio cannot be obtained in the stretching process, so the necessary retardation value is obtained. It is not preferable because it cannot be done.

  The stretching step 102 includes an outer box 102a having a dry air intake port 102b and a discharge port 102c, and a uniaxial stretching device 102d placed in the outer box 102a. Although the case where heated air is used is shown as the solvent removal means in the stretching step 102, the solvent removal means is not particularly limited, and other examples include infrared rays.

  The dry air intake port 102b and the discharge port 102c may be reversed. It is preferable that the solvent is stretched to the width required in the stretching step 102 and the amount of the solvent contained in the optical film is 5% by mass to 30% by mass in consideration of scratches, shrinkage, deformation, and the like.

  The drying temperature varies depending on the residual solvent amount 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. The temperature may be appropriately selected and determined depending on the amount of residual solvent in the range of from ° C to 180 ° C, and may be dried at a constant temperature or may be divided into several stages of temperature.

  The tenter used in the uniaxial stretching apparatus 102d is not particularly limited, and examples thereof include a clip tenter and a pin tenter, and can be selected and used as necessary. In the uniaxial stretching apparatus 102d, the web 5 is stretched by 10% to 35% in the transport direction (MD direction) of the web 5 or in the direction perpendicular to the transport direction (TD direction). When the stretching applied to the web 5 is less than 10%, the transfer of the unevenness of the mat roll is hardly reduced by the stretching, and glare caused by the unevenness is generated, which is not preferable. When the stretching exceeds 35%, the haze value increases and the transparency of the film decreases, which is not preferable.

  The drying process 103 includes a drying box 103a having a dry air intake port 103b and a discharge port 103c, an upper transport roll 103d for transporting the web 5, and a lower transport roll 103e. The upper conveyance roll 103d and the lower conveyance roll 103e are one set in the vertical direction, and are configured by a plurality of sets. Reference numeral 103 f denotes a transport roll that transports the web 5 drying process 103 coming out of the stretching process 102. The number of transport rolls disposed in the drying step 103 varies depending on the drying conditions, the method, the length of the retardation film to be manufactured, and the like, and is set as appropriate. The upper conveyance roll 103d and the lower conveyance roll 103e 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 retardation film by its drive, so the transport of the retardation film and the rotation of the drive roll are performed by nip or suction (air suction). With a synchronization mechanism.

  In the drying step 103, heating air, infrared rays, etc. alone or heating air and infrared drying may be used in combination. 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 residual solvent amount of the cellulose ester film when entering the drying process, but considering the drying time, shrinkage unevenness, stability of the expansion / contraction amount, etc., depending on the residual solvent amount in the range of 30 ° C to 180 ° C It may be selected and determined, and may be dried at a constant temperature, or may be divided into three to four stages of temperature and may be divided into several stages of temperature.

  The residual solvent amount of the retardation film after the drying treatment in the drying step 103 is preferably 0.1% by mass to 15% by mass in consideration of the load of the drying step, the dimensional stability expansion / contraction ratio during storage, and the like. In the present invention, the web subjected to the heat treatment in the drying step 103 and having a residual solvent amount of 1.5 mass% or less is referred to as a retardation film.

  The winding and collecting step 104 includes a winding device (not shown), and winds the optical film 4 that has been dried to a necessary length to a winding core. 104a 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 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.

  FIG. 2 is a schematic view of another apparatus for producing a retardation film by a solution casting method. FIG. 2A is a schematic perspective view of an apparatus for producing a retardation film by a solution casting film forming method in the case of performing preliminary drying in a drying process after casting and then performing drying in the drying process after transporting the tenter. FIG. 2B is a schematic cross-sectional view along CC ′ of FIG.

  In the figure, reference numeral 1b denotes an apparatus for producing a retardation film by a solution casting film forming method. The manufacturing apparatus 1b includes a solution casting film forming process 101, a first drying process 105, a stretching process 102, a second drying process 106, and a winding recovery process 104. The difference from the retardation film manufacturing apparatus shown in FIG. 2A is that the web 5 peeled from the belt is once dried in the first drying step 105 before being stretched in the stretching step. Other steps are the same as those of the manufacturing apparatus shown in FIG. The first drying step 105 includes a drying box 105a having a drying air intake port 105b and a discharge port 105c, an upper conveyance roll 105d that conveys the web 5, and a lower conveyance roll 105e. The upper conveyance roll 105d and the lower conveyance roll 105e are a set of upper and lower, and are configured by a plurality of sets. It is possible to adjust the amount of solvent contained in the web 5 before entering the stretching step 102 (same as the stretching step 102 shown in FIG. 1) in the first drying step 105. After the solvent amount is adjusted in the first drying step 105, the residual solvent amount contained in the web 5 when sent to the stretching step 102 is the same as that shown in FIG.

  In the 1st drying process 105, you may use heating air, infrared rays alone, or heating air and infrared drying together as a drying means. It is preferable to use heated air in terms of simplicity. The drying conditions vary depending on the residual solvent amount of the web when entering the first drying step 105 and the solvent used, so it is difficult to determine uniquely, but the residual solvent amount when entering the stretching step 102 is, It is necessary to select and determine the temperature, time, etc. as appropriate.

  In the stretching step 102 shown in this figure, the stretch ratio (%) applied in the web 5 conveyance direction (MD direction) or in the direction perpendicular to the conveyance direction (TD direction) is the same as in the stretching step shown in FIG. It is. The dry air intake port 102b and the discharge port 102c may be reversed. It is preferable that the solvent is stretched to the width required in the stretching step 102 and the amount of the solvent contained in the optical film is 5% by mass to 30% by mass in consideration of scratches, shrinkage, deformation, and the like.

  The second drying step 106 includes a drying box 106a having a drying air intake port 106b and a discharge port 106c, an upper conveyance roll 106d that conveys the web 5, and a lower conveyance roll 106e. The upper conveyance roll 306d and the lower conveyance roll 306e are one set up and down and are composed of a plurality of sets (the same configuration as the drying step 103 shown in FIG. 1). Other reference numerals are the same as those in FIG.

  The amount of residual solvent in the retardation film after the drying treatment in the second drying step 106 is the same as that in the drying step 103b in FIG.

  The width of the retardation film produced by the production apparatus shown in FIGS. 1 and 2 is preferably 1200 mm to 2700 mm in consideration of liquid crystal screen compatibility, production efficiency / utilization efficiency improvement, etc. as in a large TV. The film thickness is preferably 20 μm to 80 μm in consideration of humidity stability, reduction of display unevenness due to film shrinkage at high temperature, and the like.

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

  The in-plane retardation value Ro of the retardation film manufactured by the manufacturing apparatus shown in FIGS. 1 and 2 is preferably 10 nm to 100 nm in consideration of the optical axis shift and transparency. The thickness direction retardation value Rt is preferably 80 nm to 300 nm in consideration of humidity stability.

  The present invention uses a manufacturing apparatus that uses a solution casting film forming method as shown in FIGS. 1 and 2, without using a large manufacturing apparatus, and that does not require complicated management of the stretching apparatus. The present invention relates to a method for producing a retardation film having a stable retardation value, a retardation film produced by this production method, a polarizing plate using this retardation film, and a liquid crystal display device using this polarizing plate. .

  FIG. 3 is an enlarged schematic view of a portion indicated by P in FIG. FIG. 3A is an enlarged schematic perspective view of a portion indicated by P in FIG. FIG. 3B is an enlarged partial schematic cross-sectional view along the line DD ′ in FIG. In addition, the web 5 is abbreviate | omitted in FIG.3 (b).

  The web peeled from the belt 101a is transported to the stretching step 102 (see FIG. 1) while being supported by the transport roll 4. Reference numeral 401 denotes a peripheral surface of the transport roll 4. The peripheral surface of the transport roll 4 is a mat roll having a surface roughness of 0.8 μm to 2.0 μm. When the surface roughness is less than 0.8 μm (corresponding to a conventional transport roll), the regulating force that regulates the shrinkage that occurs in the width direction of the web when peeled from the belt cannot be obtained, and the shrinkage rate in the width direction Is different from each other, it causes creases and wrinkles, the slow axis is not constant, and the retardation value is not stable in the width direction. When the surface roughness exceeds 2.0 μm, the web pattern is soft because it contains a solvent when it is peeled off from the belt, so the surface pattern is transferred and does not disappear even in the next stretching process. It is not preferable because it does not have a function as. The surface roughness is a value measured according to JIS B 0601-2001.

  As shown in the figure, the place where the transport roll having a surface roughness of 0.8 μm to 2.0 μm is disposed is the place where the residual solvent amount of the web is 40% by mass to 110% by mass. In the case of FIG. 1, the conveyance process from the peeling point 3 to the entrance of the extending process 102 corresponds. In the case of FIG. 2, the conveyance process from the peeling point 3 through the exit of the first drying process 105 to the entrance of the stretching process 102 corresponds. In the case of FIG. 1, when the distance from the peeling point 3 to the stretching step 102 exceeds 2 m, it is preferable that a mat roll having the surface roughness shown in FIG. . In the case of FIG. 2, mat rolls having the surface roughness shown in this figure are arranged on all the conveying rolls arranged from the peeling point 3 through the exit of the first drying process 105 to the entrance of the stretching process 102. ing.

As shown in FIGS. 1 to 3, the method for producing a retardation film by the solution casting method can be widely applied to film formation using the solution casting method. As shown in FIGS. 1 to 3, the following effects can be obtained by producing a retardation film by a method for producing a retardation film by a solution casting method.
1. The shrinkage in the width direction of the web peeled from the belt can be controlled, and a retardation film having a retardation value stable in the width direction can be produced even for wide and thin films.
2. Support for large liquid crystal display devices is now possible.
3. A retardation film having a stable retardation value in the width direction can be produced without increasing the stretching process and without increasing the production apparatus, and the production cost can be suppressed.

  FIG. 4 is a schematic view of a polarizing plate produced using the retardation film produced in the present invention.

  In the figure, 6 indicates a polarizing plate. The polarizing plate 6 has a configuration in which a protective film 602 is disposed on one side of a polarizer 601 and a retardation film 603 that also functions as a protective film is disposed on the other side. The retardation film 603 is disposed so that the slow axis of the retardation film is orthogonal or parallel to the transmission axis of the polarizer.

  The polarizing plate shown in this figure can be manufactured by a general method. The back side of the retardation film 603 of the present invention is preferably bonded to at least one surface of a polarizer 601 produced by alkali saponification treatment and immersed in an iodine solution using a completely saponified polyvinyl alcohol aqueous solution. . The retardation film 603 or the protective film 602 may be used on the other surface.

  With respect to the retardation film 603 of the present invention, the protective film 602 used on the other surface is an optically isotropic protective film having an in-plane retardation Ro of 0 to 20 nm and an Rt of -50 to 50 nm. Preferably there is. The protective film preferably has a hard coat layer or an antiglare layer having a thickness of 8 to 20 μm. For example, JP 2003-114333 A, JP 2004-203309 A, 2004-354699 A A polarizing plate protective film having a hard coat layer or an antiglare layer described in JP-A No. 2004-354828 is preferably used. Further, an antireflection layer, an antifouling layer or the like is preferably laminated on the hard coat layer or antiglare layer.

  Alternatively, it is also preferable to use a polarizing plate protective film that also serves as an optical compensation film having an optical anisotropic layer formed by aligning liquid crystal compounds such as discotic liquid crystal, rod-shaped liquid crystal, and cholesteric liquid crystal. For example, the optically anisotropic layer can be formed by the method described in JP-A-2003-98348. By using in combination with the polarizing plate of the present invention, a liquid crystal display device having excellent flatness and a stable viewing angle expansion effect can be obtained.

  A polarizer, which is a main component of a polarizing plate, is an element that allows only light of a plane of polarization in a certain direction to pass. A typical polarizer currently known is a polyvinyl alcohol-based polarizing film, which is polyvinyl alcohol. There are one in which iodine is dyed on a system film and one in which dichroic dye is dyed. 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. On the surface of the polarizing film, one side of the optical film of the present invention is bonded to form a polarizing plate. It is preferably bonded with an aqueous adhesive mainly composed of completely saponified polyvinyl alcohol or the like. Ethylene-modified polyvinyl alcohol is also preferably used as a polarizer. The film thickness of the polarizer is preferably 5 to 30 μm, particularly 10 to 25 μm.

  FIG. 5 is a schematic exploded configuration diagram of a liquid crystal display device using a polarizing plate produced using the retardation 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 a polarizing plate 7b on one side of the liquid crystal cell 7a and a polarizing plate 7b on one side. The polarizing plate 7b includes a retardation film 7b2 on the liquid crystal cell 7a side of the polarizer 7b1 and a protective film 7b3 on the other side. E represents the transmission axis of the polarizer 7b1, and F represents the slow axis of the retardation film 7b2. The polarizing plate 7c includes a retardation film 7c2 on the liquid crystal cell 7a side of the polarizer 7c1 and a protective film 7c3 on the other side. G represents the transmission axis of the polarizer 7b1, and H represents the slow axis of the retardation film 7b2. The polarizing plate 7b and the polarizing plate 7c are disposed so that their slow axes are orthogonal to each other.

  The liquid crystal display device shown in the figure, which is composed of a polarizing plate using the retardation film of the present invention, is used for developing a higher display quality than a normal polarizing plate. In particular, it is preferably used for a multi-domain liquid crystal display device, more preferably a multi-domain liquid crystal display device with a birefringence mode.

  Multi-domaining is also suitable for improving the symmetry of image display, and various methods have been reported "Okita, Yamauchi: Liquid Crystal, 6 (3), 303 (2002)". The liquid crystal display cell is also shown in “Yamada, Yamahara: Liquid Crystal, 7 (2), 184 (2003)”, but is not limited thereto.

  The polarizing plate of the present invention includes an MVA (Multi-domain Vertical Alignment) mode represented by a vertical alignment mode, in particular, a MVA mode divided into four, a known PVA (Patterned Vertical Alignment) mode and an electrode multi-domained by an electrode arrangement. It can be effectively used in a CPA (Continuous Pinwheel Alignment) mode in which arrangement and chiral ability are fused. Above all, the retardation film of the present invention is preferably used for a vertical alignment mode liquid crystal display device, and particularly preferably for a MVA (Multi-domain Vertical Alignment) mode liquid crystal display device.

  The display quality of the display cell is preferably symmetrical with respect to human observation. Therefore, when the display cell is a liquid crystal display cell, the domains can be multiplied substantially giving priority to the symmetry on the observation side. A known method can be used to divide the domain, and can be determined by taking into account the properties of the known liquid crystal mode by a two-division method, more preferably a four-division method.

  Liquid crystal display devices are being applied to color display and moving image display devices, and the display quality in the present invention is less fatigued and more faithful to display moving images due to improved contrast and resistance to polarizing plates. It becomes.

  In the liquid crystal display device of the present invention, the polarizing plate using the retardation film of the present invention is disposed only on one surface of the liquid crystal cell or on both surfaces. At this time, by using the retardation film of the present invention contained in the polarizing plate so as to be on the liquid crystal cell side, it is possible to contribute to improvement in display quality. Next, the material used for manufacturing the retardation film of the present invention will be described.

(Resin material)
The retardation film of the present invention is preferably manufactured easily, has good adhesion to a polarizer, and is optically transparent. Among them, a resin film is preferable. Transparent means that the visible light transmittance is 60% or more, preferably 80% or more, and particularly preferably 90% or more.

  There is no particular limitation as long as it is a resin that forms a resin film having the above-mentioned properties. For example, cellulose ester-based resins such as cellulose diacetate resin, cellulose triacetate resin, cellulose acetate butyrate resin, and cellulose acetate propionate resin Resins, polyester resins, polycarbonate resins, polyarylate resins, polysulfone (including polyethersulfone) resins, polyester resins such as polyethylene terephthalate resins and polyethylene naphthalate resins, polyethylene resins, polypropylene resins, cellophane, polyvinylidene chloride 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 a cellulose ester resin is used as the retardation film of the present invention, the cellulose used as the raw material for the cellulose ester resin is not particularly limited, and examples include cotton linters, wood pulp (derived from coniferous trees and hardwoods), kenaf and the like. I can do it. 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-based resin used in the present invention may be propionate group or butyrate in addition to acetyl group such as cellulose acetate propionate resin, cellulose acetate butyrate resin, or cellulose acetate propionate butyrate resin. A mixed fatty acid ester of cellulose to which a group is bonded 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 polyisoprene measured by gel permeation chromatography method of cyclohexane solution (toluene solution when the polymer resin does not dissolve). Alternatively, when the weight average molecular weight in terms of polystyrene is usually in the range of 5,000 to 500,000, preferably 8,000 to 200,000, more preferably 10,000 to 100,000, the mechanical strength and molding processability of the molded body are highly balanced. It is preferable.

  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 a benzene ring, and one hydrogen on each benzene ring in bisphenol A is replaced asymmetrically with respect to the central carbon by a methyl group or a phenyl group 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 retardation 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 retardation film made of polycarbonate 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%. The following should be used: More preferably, Tg is 120 ° C. or higher and water absorption is 0.2% or less.

(Dope)
The solvent used for preparing the dope may be any solvent that can dissolve the resin, and even a solvent that cannot be dissolved alone can be dissolved by mixing with another solvent. Can be used. In general, a mixed solvent composed of a good solvent and a poor solvent is used. In addition, what melt | dissolves resin to be used independently is defined as a good solvent, and what swells or does not melt | dissolve independently is defined as a poor solvent. 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, it will be described in the case of a cellulose ester resin. 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 formation 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 a 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 (referred to as 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, an ultraviolet absorber or the like to the retardation film of the present invention. As the antioxidant, a hindered phenol compound is preferably used, and 2,6-di-t-butyl-p-cresol, pentaerythrityl-tetrakis [3- (3,5-di-t-butyl). -4-hydroxyphenyl) propionate], triethylene glycol-bis [3- (3-tert-butyl-5-methyl-4-hydroxyphenyl) propionate], 1,6-hexanediol-bis [3- (3 5-di-t-butyl-4-hydroxyphenyl) propionate], 2,4-bis- (n-octylthio) -6- (4-hydroxy-3,5-di-t-butylanilino) -1,3 5-triazine, 2,2-thio-diethylenebis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], octadecyl-3- ( , 5-di-t-butyl-4-hydroxyphenyl) propionate, N, N′-hexamethylenebis (3,5-di-t-butyl-4-hydroxy-hydrocinnamamide), 1,3,5 -Trimethyl-2,4,6-tris (3,5-di-t-butyl-4-hydroxybenzyl) benzene, tris- (3,5-di-t-butyl-4-hydroxybenzyl) -isocyanurate Etc. In particular, 2,6-di-t-butyl-p-cresol, pentaerythrityl-tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], triethylene glycol-bis [3- (3-t-butyl-5-methyl-4-hydroxyphenyl) propionate] is preferred. Further, for example, hydrazine-based metal deactivators such as N, N′-bis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyl] hydrazine and tris (2,4-di-t A phosphorus-based processing stabilizer such as -butylphenyl) phosphite may be used in combination. The amount of these compounds added is preferably 1 ppm to 1.0%, more preferably 10 to 1000 ppm in terms of mass ratio with respect to the cellulose ester.

  In addition, heat stabilizers such as 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 retardation 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 liquid crystal can be 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 and then add to the dope. The amount of the ultraviolet absorber used is preferably 0.1% by mass to 2.5% by mass in consideration of the effect as an ultraviolet absorber, transparency, and the like. Furthermore, Preferably, it is 0.8 mass%-2.0 mass%.

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

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

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

  As 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 to be a clear or slightly turbid solution by visual observation but appears as a particulate dispersion under an electron microscope.

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

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

  The retardation film manufactured by the manufacturing method of this invention can be used for the polarizing plate used for a liquid crystal display, and a liquid crystal display device.

  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
Using the production apparatus shown in FIG. 1, a dope shown below is cast on a belt having a length of 100 m at a temperature of 35 ° C., and the web is peeled at the peeling point of the belt (time from casting to peeling 1. 5 minutes), the residual solvent amount of the web between the uniaxial stretching apparatus, the surface roughness (Ra) of the conveying roll disposed from the peeling point to the entrance of the uniaxial stretching apparatus, and the conveying direction in the uniaxial stretching apparatus. Stretching was performed while changing the stretching ratio in the perpendicular direction (TD direction) as shown in Table 1. Thereafter, a 3000 μm-thick retardation film having a thickness of 43 μm, which was dried in the drying process and made into a roll in the recovery process, was prepared. 101-140. The belt used was a 1800 mm wide stainless steel with a mirror finished surface. The residual solvent amount of the web was the residual solvent amount of the web immediately after peeling. The casting width was 1650 mm. The peeling tension when peeling the web from the belt was 150 N / m, and the conveying tension to the uniaxial stretching apparatus was 200 N / m. When peeling, cold air of 10 ° C. was blown. In the uniaxial stretching apparatus, heated air was used as a solvent removing means, the temperature of the heated air was adjusted, and the amount of residual solvent in the web was 7% by mass when the stretching process was completed. The uniaxial stretching apparatus used a clip tenter. In the drying process, the temperature of the heated air was adjusted so that the amount of residual solvent in the retardation film of the product was 1.5% by mass.

  The value of the residual solvent amount (% by mass) is 10 cm × 5 cm in web (retardation film) when the web (retardation film) is dried for 1 hour at 115 ° C. When the mass of the retardation film is A, it is a value obtained by ((A−B) / B) × 100 = residual solvent amount (mass%). The change in the residual solvent amount of the web immediately after peeling was adjusted by changing the heating temperature in the solution casting film forming step.

<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: Aromatic terminal ester Sample No. 4 5 parts by mass Plasticizer: Trimethylolpropane tribenzoate 5.5 parts by mass UV absorber: Tinuvin 109 (manufactured by Ciba Specialty Chemicals)
1 part by mass UV absorber: Tinuvin 171 (manufactured by Ciba Specialty Chemicals)
1 part by mass

Evaluation The produced sample No. The in-plane retardation value Ro and the thickness direction retardation value Rt are measured by the methods shown below, and the results are shown in Table 2.

Measurement of in-plane retardation value Ro and thickness direction retardation value Rt Using an automatic birefringence meter KOBRA-21ADH (manufactured by Oji Scientific Instruments), the film was allowed to stand for 24 hours in an environment of 23 ° C. and 55% RH. In this environment, the retardation of the film was measured at a wavelength of 589 nm. The above-mentioned average refractive index and film thickness are input to the following equation, and the lateral deviation of the in-plane retardation value Ro, the thickness direction retardation value Rt, and the thickness direction retardation value Rt is obtained. The width deviation is a 13-point thickness direction retardation value Rt, and the Rt width deviation indicating the maximum value and the minimum value causes display unevenness when the polarizing plate is processed. It is preferable that it is 6 nm or less.

  The present invention has an Rt width deviation of 6 nm or less, confirming the effectiveness of the present invention.

Example 2
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.

  Subsequently, each retardation film sample No. 1 produced in the polarizer and Example 1 according to the following steps 1 to 5 was used. 101 to 140 and Konica Minolta Tack KC8UX-RHA (manufactured by Konica Minolta Opto Co., Ltd.) were bonded together as a protective film on the back side to produce a polarizing plate. 2-1 to 2-40.

  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 saponified cellulose ester film 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: Lightly wipe off excess adhesive adhering to the polarizer in Step 2 and place it on the cellulose ester film treated in Step 1 so that the anti-reflection layer of KC8UX-RHA is on the outside Laminated and placed.

Step 4: The retardation film, the polarizing film, and the cellulose ester film sample laminated in Step 3 were bonded at a pressure of 20 to 30 N / cm ² and a conveyance speed of about 2 m / min.

  Step 5: The polarizer, cellulose ester film, and each sample No. prepared in Step 4 in a dryer at 80 ° C. The sample bonded with 101 to 140 was dried for 2 minutes to prepare a polarizing plate.

  Thereafter, the polarizing plate of a commercially available liquid crystal TV (Sharp Aquos 32AD5) was peeled off, and the produced sample No. Each of 201 to 240 was bonded to the glass surface of the liquid crystal cell. At that time, the polarizing plate is bonded so that the surface of the retardation film is on the liquid crystal cell side and the absorption axis is oriented in the same direction as the previously bonded polarizing plate. A display device was manufactured and 201-240.

Evaluation The liquid crystal display device No. As a result of evaluating the front contrast by the following method after turning on the backlight of the liquid crystal TV display device of the manufactured liquid crystal display device in the environment of 201 to 240 at 23 ° C. and 55% RH and leaving it as it is for 30 minutes. Is shown in Table 3.

Evaluation Method of Front Contrast For measurement, EZ-Contrast 160D manufactured by ELDIM was used to measure front luminance from the normal direction of white display and black display on a liquid crystal TV, and the ratio was defined as front contrast. The higher the value, the better the contrast.

  Front contrast = brightness of white display measured from normal direction of display device / brightness of black display measured from normal direction of display device

Example 3
Sample No. 1 prepared in Example 1 was used. When producing No. 118, a retardation film having different widths as shown in Table 4 was prepared under the same conditions except that the width of the web was changed. 301 to 306.

Evaluation The produced sample No. Table 4 shows the results of measuring the lateral deviation of the in-plane retardation value Ro, the thickness direction retardation value Rt, and the thickness direction retardation value Rt in the same manner as in Example 1.

  The present invention has an Rt width deviation of 6 nm or less, confirming the effectiveness of the present invention.

Example 4
Sample No. 1 prepared in Example 1 was used. When producing No. 118, a retardation film having a thickness changed as shown in Table 5 under the same conditions except that the thickness of the web was changed was prepared. 401 to 406.

Evaluation The produced sample No. 401 to 406, the result of measuring the width deviation of the in-plane retardation value Ro, the thickness direction retardation value Rt, and the thickness direction retardation value Rt in the same manner as in Example 1 in the same manner as in Example 1. Is shown in Table 5.

  The present invention has an Rt width deviation of 6 nm or less, confirming the effectiveness of the present invention.

Example 5
Using the production apparatus shown in FIG. 1, the dope shown below is cast on a belt having a length of 100 m at a temperature of 35 ° C., and the web is peeled off at the peeling point of the belt (the time from casting to peeling is 2 minutes) ), The residual solvent amount of the web between the uniaxial stretching apparatus, the surface roughness (Ra) of the conveying roll disposed from the peeling point to the entrance of the uniaxial stretching apparatus, and the direction perpendicular to the conveying direction in the uniaxial stretching apparatus. The stretching ratio (TD direction) was changed as shown in Table 6 for stretching. Thereafter, 2500 m of a retardation film having a thickness of 50 μm, which was dried in the drying process and made into a roll in the recovery process, was prepared. 501-540.

  The belt used was a 1800 mm wide stainless steel with a mirror finished surface. The residual solvent amount of the web was the residual solvent amount of the web immediately after peeling. The casting width was 1650 mm. The peeling tension when peeling the web from the belt was 150 N / m, and the conveying tension to the uniaxial stretching apparatus was 150 N / m. When peeling, cold air of 10 ° C. was blown.

  In the uniaxial stretching apparatus, heated air was used as a solvent removing means, the temperature of the heated air was adjusted, and the amount of residual solvent of the web at the time when the stretching process was completed was set to 8.0% by mass. The uniaxial stretching apparatus used a clip tenter. In the drying process, the temperature of the heated air was adjusted so that the amount of residual solvent in the retardation film of the product was 1.5% by mass.

  The value of the residual solvent amount (% by mass) is 10 cm × 5 cm in web (retardation film) when the web (retardation film) is dried for 1 hour at 115 ° C. When the mass of the retardation film is A, it is a value obtained by ((A−B) / B) × 100 = residual solvent amount (mass%). The change in the residual solvent amount of the web immediately after peeling was adjusted by changing the heating temperature in the solution casting film forming step.

  A main dope solution 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. A dope solution was prepared by filtration using 244.

<Dope composition>
Polycarbonate resin (viscosity average molecular weight 40,000, bisphenol A type) 100 parts by mass 2- (2'-hydroxy-3 ', 5'-di-)
t-Butylphenyl) benzotriazole 1.0 part by weight Methylene chloride 430 parts by weight Methanol 90 parts by weight The above composition is put into a sealed container, kept at 80 ° C. under pressure, and completely dissolved with stirring to obtain a dope composition I got a thing.

Evaluation The produced sample No. 501 to 540, the results of measuring the width deviation of the in-plane retardation value Ro, the thickness direction retardation value Rt, and the thickness direction retardation value Rt in the same manner as in Example 1 in the same manner as in Example 1. Is shown in Table 7.

  The present invention has an Rt width deviation of 6 nm or less, confirming the effectiveness of the present invention.

Example 6
Using the production apparatus shown in FIG. 1, the dope shown below is cast on a belt having a length of 100 m at a temperature of 35 ° C., and the web is peeled off at the peeling point of the belt (the time from casting to peeling is 2 minutes) ), The residual solvent amount of the web between the uniaxial stretching apparatus, the surface roughness (Ra) of the conveying roll disposed from the peeling point to the entrance of the uniaxial stretching apparatus, and the direction perpendicular to the conveying direction in the uniaxial stretching apparatus. The stretching ratio (TD direction) was changed as shown in Table 8 for stretching. Thereafter, a 3000 μm thick retardation film having a thickness of 30 μm, which was dried in the drying process and rolled in the recovery process, was prepared. 601-640.

  The belt used was a 1800 mm wide stainless steel with a mirror finished surface. The residual solvent amount of the web was the residual solvent amount of the web immediately after peeling. The casting width was 1650 mm. The peeling tension when peeling the web from the belt was 100 N / m, and the conveying tension to the uniaxial stretching apparatus was 130 N / m. When peeling, cold air of 10 ° C. was blown.

  In the uniaxial stretching apparatus, heated air was used as a solvent removing means, the temperature of the heated air was adjusted, and the amount of residual solvent in the web was 6.5% by mass when the stretching process was completed. The uniaxial stretching apparatus used a clip tenter. In the drying process, the temperature of the heated air was adjusted so that the residual solvent amount of the retardation film of the product was 1.0% by mass.

  The value of the residual solvent amount (% by mass) is 10 cm × 5 cm in web (retardation film) when the web (retardation film) is dried for 1 hour at 115 ° C. When the mass of the retardation film is A, it is a value obtained by ((A−B) / B) × 100 = residual solvent amount (mass%). The change in the residual solvent amount of the web immediately after peeling was adjusted by changing the heating temperature in the solution casting film forming step.

<Preparation of fine particle dispersion>
Ethanol 27 parts by mass Silicon dioxide fine particles 3 parts by mass (trade name: AEROSIL-R972V, primary particle size: 16 nm)
The above materials are mixed in a predetermined container, stirred for 30 minutes at a rotation speed of 500 rpm, dispersed in a Manton Gorin type high-pressure disperser at a pressure of 2500 × 10 ⁴ Pa, and then the dispersion is methylene chloride. The fine particle dispersion was prepared by diluting with 27 parts by mass.

(Preparation of norbornene resin solution)
Norbornene resin (Arton G, JSR) 80 parts by weight Ethylphthalyl ethyl glycolate (plasticizer) 2 parts by weight Triphenyl phosphate (plasticizer) 8 parts by weight Methylene chloride (boiling point: 39.8 ° C.) 250 parts by weight Ethanol 10 Part of the mass The above material was put into a melting pot, heated to 70 ° C., and while stirring, the norbornene resin was completely dissolved to obtain a norbornene resin solution. The time required for dissolution was 4 hours.

(Preparation of additive solution)
The norbornene resin solution 75 parts by mass Tinuvin 326 (manufactured by Ciba Specialty Chemicals) 5 parts by weight The fine particle dispersion 60 parts by weight Methylene chloride 290 parts by weight In the dissolution vessel, the norbornene resin after filtration while stirring the methylene chloride After a part of the solution was added, an ultraviolet absorber and the fine particle dispersion were further added in this order. After the addition, the additive solution was prepared by heating to 40 ° C. and dissolving for 30 minutes.

(Preparation of dope for norbornene resin film)
The dope for norbornene-based resin film was prepared by adding inline the additive solution from the flow tube to the main part of the norbornene-based resin solution (the remaining 25 parts by weight) and mixing with a static mixer.

Evaluation The produced sample No. Table 9 shows the results obtained by measuring width deviations of the in-plane retardation value Ro, the thickness direction retardation value Rt, and the thickness direction retardation value Rt in the same manner as in Example 1, with reference to 601 to 640.

  The present invention has an Rt width deviation of 6 nm or less, confirming the effectiveness of the present invention.

It is the schematic of the manufacturing apparatus of the phase difference film by a solution casting film forming method. It is the schematic of the other manufacturing apparatus of retardation film by a solution casting film forming method. FIG. 2 is an enlarged schematic view of a portion indicated by P in FIG. It is a schematic diagram of the polarizing plate produced using the phase difference film manufactured by this invention. It is a model exploded block diagram of the liquid crystal display device using the polarizing plate produced using the retardation film manufactured by this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1a, 1b Manufacturing apparatus 101 Solution casting film forming process 101a Mirror surface metal casting belt 101b Die 101c Heating apparatus 102 Stretching process 102a Outer box 102b Dry air intake 102c Discharge port 102d Uniaxial stretching apparatus 103 Drying process 103a, 105a, 106a Drying box 104 Winding and collecting step 105 First drying step 106 Second drying step 2 Dope 3 Peeling point 4 Conveying roll 401 Circumferential surface 5 Web 6, 7b, 7c Polarizing plate 601, 7b1, 7c1 Polarizer 602, 7b3, 7c3 Protection Film 603, 7b2, 7c2 Retardation film 7 Liquid crystal display device 7a Liquid crystal cell G Transmission axis H Slow axis

Claims (9)

A solution in which a liquid obtained by dissolving a raw material resin in a solvent is cast on an endless support to form a web, the web is peeled off from the endless support, and then stretched by a uniaxial stretching apparatus, and then the solvent is removed. In the method for producing a retardation film by a casting method,
After peeling the web from the endless support, until the uniaxial stretching apparatus, the residual solvent amount of the web is between 40% by mass and 110% by mass, and the surface roughness (Ra) is 0.8 μm to 2 μm. A transport process with a transport roll of .mu.m;
In the uniaxial stretching apparatus, the film is stretched by 10% to 35% in a transport direction (MD direction) of the web or in a direction perpendicular to the transport direction (TD direction). The width of the said retardation film is 1200 mm-2700 mm, The manufacturing method of the retardation film of Claim 1 characterized by the above-mentioned. The thickness of the said retardation film is 20 micrometers-80 micrometers, The manufacturing method of the retardation film of Claim 1 characterized by the above-mentioned. The method for producing a retardation film according to claim 1, wherein the raw resin is a cellulose ester resin. The method for producing a retardation film according to claim 1, wherein the raw resin is a cycloolefin resin. The method for producing a retardation film according to claim 1, wherein the raw resin is a polycarbonate resin. A retardation film produced by the method for producing a retardation film according to claim 1. A polarizing plate, wherein the retardation film according to claim 7 is disposed on at least one surface of the polarizer so that the slow axis of the retardation film is perpendicular or parallel to the transmission axis of the polarizer. A liquid crystal display device using the polarizing plate according to claim 8.

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