WO2012117662A1 - Optical film manufacturing device and manufacturing method, optical film, polarizing plate, and liquid crystal display device - Google Patents

Optical film manufacturing device and manufacturing method, optical film, polarizing plate, and liquid crystal display device Download PDF

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Publication number
WO2012117662A1
WO2012117662A1 PCT/JP2012/000553 JP2012000553W WO2012117662A1 WO 2012117662 A1 WO2012117662 A1 WO 2012117662A1 JP 2012000553 W JP2012000553 W JP 2012000553W WO 2012117662 A1 WO2012117662 A1 WO 2012117662A1
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Prior art keywords
film
casting
optical film
intake
air
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PCT/JP2012/000553
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French (fr)
Japanese (ja)
Inventor
直也 太田
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コニカミノルタアドバンストレイヤー株式会社
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Publication of WO2012117662A1 publication Critical patent/WO2012117662A1/en

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C41/00—Shaping by coating a mould, core or other substrate, i.e. by depositing material and stripping-off the shaped article; Apparatus therefor
    • B29C41/24—Shaping by coating a mould, core or other substrate, i.e. by depositing material and stripping-off the shaped article; Apparatus therefor for making articles of indefinite length
    • B29C41/28—Shaping by coating a mould, core or other substrate, i.e. by depositing material and stripping-off the shaped article; Apparatus therefor for making articles of indefinite length by depositing flowable material on an endless belt
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
    • B29K2001/00—Use of cellulose, modified cellulose or cellulose derivatives, e.g. viscose, as moulding material
    • B29K2001/08—Cellulose derivatives
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
    • B29K2995/00—Properties of moulding materials, reinforcements, fillers, preformed parts or moulds
    • B29K2995/0018—Properties of moulding materials, reinforcements, fillers, preformed parts or moulds having particular optical properties, e.g. fluorescent or phosphorescent

Definitions

  • the present invention relates to an optical film manufacturing apparatus and method, an optical film manufactured by the manufacturing apparatus or manufacturing method, a polarizing plate using the optical film as a transparent protective film, and these optical films or polarizing plates.
  • the present invention relates to a liquid crystal display device.
  • a solution casting film forming method in which a resin solution (dope) is cast on a moving support to form a casting film (web).
  • a resin solution dip
  • a casting film web
  • drying air may not be applied to the casting film immediately after casting on the support. Since the cast film immediately after casting has a high residual solvent amount, when dry air is applied, the cast film is locally dried and contracted only at the location where the dry air is applied, resulting in uneven drying of the cast film. This is because the flatness of the cast film may be lowered.
  • the casting film immediately after casting has a high residual solvent amount and high fluidity, when the drying air is applied, the casting film locally flows and deforms only at the location where the drying air is applied. This is because unevenness in drying may occur and the flatness of the cast film may be deteriorated.
  • Patent Document 1 a relatively weak dry wind having a wind speed of about 0.1 to 2.0 m / s is applied to the casting film until the temperature of the casting film after casting reaches the gelling temperature. After drying and the temperature of the casting film reaches the gelation temperature, drying with high drying efficiency can be performed by applying relatively strong drying air with a wind speed of 2.0 m / s or more to the casting film. It is disclosed.
  • Patent Document 2 discloses a blowing nozzle for applying a drying air to a casting film, and a suction port for sucking a part of the drying air applied to the casting film from the blowing nozzle and exhausting it to the outside. Is provided in the air duct.
  • JP-A-11-58425 (paragraphs 0006 and 0010) JP 2007-290370 A (paragraph 0043, FIG. 3)
  • the purpose of the present invention is to produce a non-uniformity in drying of the cast film caused by the dry air hitting the cast film and the flow of the wind in the space above the cast film when the optical film is produced by the solution casting film forming method. It is to suppress remelting unevenness of the cast film due to weakening.
  • One aspect of the present invention is an optical film manufacturing apparatus that performs a step of casting a resin solution on a moving support to form a cast film, and an upper space of the cast film immediately after casting on the support. And an air blower for executing an air blowing process for blowing dry air to the casting film following the air intake process by the air intake device.
  • This is an optical film manufacturing apparatus.
  • Another aspect of the present invention is an optical film manufacturing method including a step of casting a resin solution on a moving support to form a cast film, and above the cast film immediately after casting on the support.
  • An optical film manufacturing method comprising: an air intake step of performing air intake in a space; and an air blowing step of blowing dry air to a cast film following the air intake step.
  • Still another aspect of the present invention is an optical film manufactured by the manufacturing apparatus or the manufacturing method.
  • Still another aspect of the present invention is a polarizing plate using the optical film as a transparent protective film on at least one surface.
  • Still another aspect of the present invention is a liquid crystal display device using the optical film or the polarizing plate.
  • FIG. 1 is a schematic configuration diagram of an optical film manufacturing apparatus according to an embodiment of the present invention.
  • FIG. 2 is an enlarged view of the support of the optical film manufacturing apparatus of FIG. 1 and its surroundings.
  • FIG. 1 is a schematic configuration diagram of an optical film manufacturing apparatus 1 according to an embodiment of the present invention.
  • the optical film manufacturing apparatus 1 manufactures an optical film by a solution casting film forming method, and includes a casting apparatus 10, a stretching apparatus 20, a heat treatment apparatus 30, and a winding apparatus 40.
  • the casting apparatus 10 includes a die 11, an endless belt 12 that is a support, and a peeling roll 13.
  • the die 11 discharges a resin solution (dope) 51 in which a resin is dissolved in a solvent and casts it on the moving endless belt 12 to form a casting film (web) 52. This is called a casting process.
  • the endless belt 12 moves to move the formed cast film 52 in the direction of the arrow in the figure.
  • the peeling roll 13 peels the casting film 52 from the endless belt 12 and sends the peeled casting film 52, that is, the resin film 53 to the stretching device 20.
  • the stretching device 20 uses a clip tenter, a pin tenter, or the like while transporting the resin film 53 to move the resin film 53 in the longitudinal direction (transport direction (machine direction: MD direction)) and / or the width direction (direction orthogonal to the transport direction). (Transverse Direction: TD direction)).
  • the heat treatment apparatus 30 heats and heats the stretched resin film 53 to a predetermined temperature while being conveyed, that is, dries.
  • the winding device 40 winds the heat-treated resin film 53 as an optical film in a roll shape.
  • an optical film that is, a cellulose triacetate film or a cellulose ester film
  • a cellulose ester resin such as cellulose triacetate (hereinafter sometimes simply referred to as cellulose ester) is produced as the optical film.
  • the optical film containing an acrylic resin and a cellulose-ester resin may be manufactured, for example.
  • the resin solution 51 discharged from the die 11 is prepared by, for example, dissolving a cellulose ester resin such as cellulose triacetate in a solvent containing a good solvent for the cellulose ester resin using a dissolution vessel.
  • the content of the cellulose ester resin in the resin solution 51 is preferably 15 to 30% by mass, for example.
  • a method carried out at normal pressure a method carried out below the boiling point of the solvent, a method carried out under pressure above the boiling point of the solvent, JP-A-9-95544, JP-A-9-95557, or Various dissolution methods such as a method using a cooling dissolution method as described in Kaihei 9-95538 and a method using a high pressure as described in Japanese Patent Application Laid-Open No. 11-21379 can be used.
  • the method of pressurizing at a temperature equal to or higher than the boiling point of the solvent is preferable.
  • the resin solution 51 is filtered through a filter medium and defoamed.
  • a filter medium having a collected particle diameter of 0.5 to 5 ⁇ m and a drainage time of 10 to 25 sec / 100 ml.
  • the resin solution 51 is sent to the die 11 by a liquid feed pump such as a pressurized metering gear pump.
  • the die 11 is preferably capable of adjusting the shape of the discharge port.
  • a pressure die that can easily make the film thickness of the casting film 52 uniform is preferable. Examples of the pressure die include a coat hanger die and a T die, and any of them is preferably used. In order to increase the film forming speed, two or more pressure dies may be arranged side by side, and the resin solution 51 may be divided and discharged.
  • the discharge speed at which the resin solution 51 is discharged from the die 11 is preferably, for example, about 30 to 150 m / min in consideration of the balance with the transport speed of the casting film 52 by the endless belt 12 and productivity.
  • the endless belt 12 is a metal belt having a mirror-finished surface.
  • the endless belt 12 is preferably made of stainless steel, for example, from the viewpoint of peelability of the cast film 52.
  • the width of the casting film 52 cast by the die 11 is preferably 80 to 99% with respect to the width of the endless belt 12 from the viewpoint of effectively utilizing the width of the endless belt 12.
  • the endless belt 12 travels to dry the casting film 52 while transporting the casting film 52 formed on the surface thereof.
  • this drying will be described in detail later, in general, for example, a method in which the back surface of the endless belt 12 is heated by blowing a heater or hot air, and the casting film 52 on the endless belt 12 is heated by blowing a heater or hot air. It is possible to select as appropriate according to need.
  • the temperature of the casting film 52 at the time of drying is preferably ⁇ 5 to 70 ° C., more preferably 0 to 60 ° C. in consideration of the time required for evaporation of the solvent, the conveyance speed, productivity, and the like. If the temperature of the casting film 52 is too high, the casting film 52 tends to foam or the flatness of the casting film 52 tends to deteriorate. In the present embodiment, as will be described later, about 30 to 45 ° C. is preferable.
  • the wind pressure of the dry air is preferably 50 to 5000 Pa in consideration of the uniformity of solvent evaporation and the like.
  • the temperature of the drying air may be dried at a constant temperature, or may be sprayed in several steps in the traveling direction of the endless belt 12.
  • the temperature of the drying air is preferably about 30 to 45 ° C., for example.
  • the time until the casting film 52 is peeled from the endless belt 12 varies depending on the film thickness of the optical film to be produced and the solvent used, but the endless belt 12. In view of peelability from the film, it is preferably in the range of 0.5 to 5 minutes.
  • the transport speed of the casting film 52 by the endless belt 12 (that is, the moving speed of the endless belt 12) is, for example, from 60 m / min to 150 m / min (1 m / s to 2.. 5 m / s).
  • the ratio (V2 / V1) (draft ratio) of the transport speed V2 of the cast film 52 by the endless belt 12 to the discharge speed V1 of the resin solution 51 from the die 11 is about 0.8 to 2.0. preferable.
  • the draft ratio is within this range, the casting film 52 can be stably formed.
  • the draft ratio is too large, there is a tendency to cause a phenomenon called neck-in in which the casting film 52 is reduced in the width direction, which makes it difficult to form a wide film.
  • the peeling roll 13 is in contact with the surface of the endless belt 12 in a pressurized state, and peels the dried casting film 52 from the endless belt 12.
  • the peeling tension at the time of peeling is preferably in the range of 50 to 400 N / m.
  • the residual solvent ratio of the cast film 52 at the time of peeling is 30 to 200% by mass in consideration of the peelability from the endless belt 12, the transportability after peeling, the physical properties of the optical film to be manufactured, and the like. It is preferable.
  • Residual solvent ratio (%) ⁇ (mass before heat treatment of cast film ⁇ mass after heat treatment of cast film) / mass after heat treatment of cast film ⁇ ⁇ 100 Note that the heat treatment for measuring the residual solvent ratio is a heat treatment at 115 ° C. for 1 hour.
  • the stretching device 20 grips both lateral edges of the resin film 53, which is the casting film 52 peeled from the endless belt 12, with a clip tenter, a pin tenter, etc., to hold the resin film 53 in the longitudinal direction (MD direction) and / Or extends in the width direction (TD direction).
  • the stretching ratio in the TD direction of the resin film 53 is preferably about 5 to 30%.
  • the stretching ratio of the resin film 53 in the TD direction is 5 to 30%, it is possible to prevent the optical value of the optical film from becoming non-uniform. Therefore, an optical film having a uniform optical value and a wide width can be obtained.
  • variety of an optical film is wide, it is preferable also from the point of use to a large sized liquid crystal display device, the use efficiency of the film at the time of polarizing plate processing, and production efficiency.
  • the stretching ratio in the TD direction is defined by the following equation.
  • Stretch ratio (%) in TD direction ⁇ (length in the width direction after stretching at a predetermined position of the film ⁇ length in the width direction before stretching at a predetermined position of the film) / before stretching at a predetermined position of the film Length in the width direction ⁇ ⁇ 100
  • the length in the width direction of the film is a value measured with a C-type JIS grade 1 steel scale.
  • Stretching rate in MD direction (%) ⁇ (Conveying speed of film after stretching ⁇ Conveying speed of film before stretching) / Conveying speed of film before stretching ⁇ ⁇ 100
  • the heat treatment apparatus 30 includes a plurality of transport rolls, and dries the resin film 53 while transporting the resin film 53 between the rolls. In that case, you may dry using heating air, infrared rays, etc. independently, and you may dry using heating air and infrared rays together. It is preferable to use heated air from the viewpoint of simplicity.
  • the drying temperature varies depending on the residual solvent ratio of the resin film 53, but is appropriately selected depending on the residual solvent ratio in the range of 30 to 180 ° C. in consideration of drying time, shrinkage unevenness, stability of expansion and contraction, etc. You can decide. Further, it may be dried at a constant temperature, or may be divided into two to four stages of temperature and may be divided into several stages of temperature.
  • the winding device 40 winds the resin film 53 that has been stretched by the stretching device 20 and dried by the heat treatment device 30 to a required length to be wound around 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 can be used without any particular limitation, and may be a commonly used one, 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. Can be wound up.
  • the width of the optical film to be wound is preferably 1000 to 4000 mm.
  • the film thickness of the optical film is preferably 15 ⁇ m to 60 ⁇ m from the viewpoint of contributing to thinning (thinning) the polarizing plate and the liquid crystal display device and stabilizing production of the film.
  • the film thickness is an average film thickness.
  • a film thickness measuring instrument DH-150 manufactured by Tokyo Seimitsu Co., Ltd., a contact-type film thickness meter manufactured by Mitutoyo Co., Ltd., or the like is used. The film thickness is measured at 20 to 200 locations in the longitudinal direction and the width direction, and the average value of the measured values is shown as the film thickness.
  • the film thickness deviation in the width direction and the longitudinal direction of the optical film is 0.2 ⁇ m to 1.m from the viewpoint that the good flatness of the optical film is reliably maintained and the optical properties of the optical film are further improved. It is preferably 5 ⁇ m.
  • FIG. 2 is an enlarged view of the endless belt 12 of the manufacturing apparatus 1 and its surroundings.
  • reference numeral 14 denotes an intake device
  • reference numeral 15 denotes a blower
  • reference numeral 16 denotes a shielding plate.
  • the intake device 14 is for executing an intake process of performing intake on the endless belt 12 in the space above the casting film 52 immediately after casting.
  • the air blower 15 is for performing the air blow process which blows dry air to the casting film 52 on the endless belt 12 following the air intake process by the air intake apparatus 14.
  • the intake device 14 is disposed adjacent to the die 11 and downstream of the die 11 in the moving direction of the casting film 52.
  • the air blower 15 is arranged downstream of the air intake device 14 in the moving direction of the casting film 52, following the air intake device 14.
  • the intake device 14 and the blower device 15 are arranged around the endless belt 12 so as to surround the endless belt 12 at a certain distance from the circumferential surface of the endless belt 12.
  • a large number of slit-shaped air inlets and air outlets extending in the width direction over the entire width of the endless belt 12 are provided on the surfaces of the air intake device 14 and the air blower 15 facing the endless belt 12, that is, the bottom surface. Then, by changing the direction of a large number of nozzles (not shown) incorporated in the intake device 14 and the blower device 15, the direction of intake air by the intake device 14 (symbol a) and the direction of air blow by the blower device 15 (symbol b). ) Is freely changeable.
  • the term “above the casting film 52” literally means a direction above the casting film 52, and the casting film 52 is cast from the surface of the casting film 52 toward the bottom surfaces of the intake device 14 and the blower device 15. A direction away from the surface of the film 52.
  • an optical film manufacturing method having a casting process in which the resin solution 51 is cast on the moving endless belt 12 to form the casting film 52 is realized.
  • the intake device 14 executes an intake process in which air is sucked in the space above the casting film 52 immediately after casting on the endless belt 12, and the casting film 52 on the endless belt 12 is dried after the suction process.
  • a blowing process for blowing wind is performed by the blower 15.
  • drying air is not applied to the casting film 52 immediately after casting, so that drying unevenness of the casting film 52 is suppressed. .
  • the air is sucked in the space above the casting film 52 with respect to the casting film 52 immediately after casting, the flow of wind in the space above the casting film 52 does not weaken, and the casting film 52 Movement of the evaporated solvent is ensured, and uneven remelting of the casting film 52 is suppressed.
  • the drying air is blown to the casting film 52, so that drying of the casting film 52 is promoted while suppressing drying unevenness and remelting unevenness.
  • the air blowing process is performed subsequent to the air intake process, the wind always flows through the space above the casting film 52, and the solvent evaporated from the casting film 52 is moved even when switching from the air intake process to the air blowing process. It is ensured and re-dissolution unevenness is suppressed.
  • the shielding plate 16 is for partitioning the upper space of the casting film 52 where the air suction device 14 sucks air from the upper space of the casting film 52 where the air blowing device 15 blows air.
  • a predetermined amount of gap is left between the shielding plate 16 and the casting film 52.
  • a preferable value of the gap varies depending on the situation, but is, for example, 1 mm to 300 mm.
  • the shielding plate 16 is movably provided at the boundary between the intake device 14 and the blower device 15 as indicated by arrows c and d. That is, the optical film manufacturing apparatus 1 is provided with a suction passage and a blower passage (not shown), and the intake port and the blower port of the intake device 14 and the blower device 15 are respectively a passage switching means such as a valve. Thus, it is possible to selectively communicate with either the suction passage or the air passage. Then, the shielding plate 16 is moved at the boundary between the portion that operates as the intake device 14 and the portion that operates as the blower device 15.
  • the intake air in the intake process and the blown air in the blowing process do not interfere with each other, and the wind moves through the gap between the shielding plate 16 and the casting film 52. Remelting unevenness is further suppressed when switching to the blowing process.
  • the intake speed of the intake process is smaller than the blow speed of the blow process. This is because unevenness of drying of the cast film 52 is further suppressed.
  • the intake speed of the intake process is 0.1 m / s to 3 m / s in terms of effective wind speed
  • the blow speed of the blow process is preferably 2 m / s to 30 m / s in terms of effective wind speed. This is because in addition to the suppression of drying unevenness and remelting unevenness, insufficient drying of the cast film 52 is also suppressed.
  • the intake speed of the intake process is gradually or stepwise increased from 0.1 m / s to 2 m / s as an effective wind speed, and following this intake process, the blow speed of the blow process is set to 2 m / s as an effective wind speed. From 30 m / s to 30 m / s.
  • the amount of solvent in the casting film 52 with respect to the amount of solvent in the resin solution 51 before being cast on the endless belt 12 is reduced to 85% by mass to 95% by mass, air is blown from the intake process. It is preferable to switch to a process. This is because drying unevenness and insufficient drying are further suppressed.
  • the amount of the solvent in the casting film 52 decreases to 85 mass% to 95 mass%.
  • the direction from the surface of the casting film 52 toward the upper side of the casting film 52 along the normal line of the surface of the casting film 52 is used as a reference, and is separated from the surface of the casting film 52 from this direction. It is preferable that the intake side inhales in a direction inclined at 0 ° to 45 ° downstream of the casting film 52 in the moving direction. For example, FIG. 2 shows that the air is sucked in a direction inclined 45 ° downstream.
  • the direction from the upper side of the casting film 52 toward the surface of the casting film 52 along the normal line of the surface of the casting film 52 is used as a reference, and the proximity to the surface of the casting film 52 from this direction.
  • the air flowing side is blown in a direction inclined at 0 ° to 80 ° downstream of the casting film 52 in the moving direction.
  • FIG. 2 shows that the air is blown in a direction inclined by 63 ° on the downstream side.
  • the temperature of the drying air blown in the blowing step is preferably about 30 to 45 ° C. as described above.
  • the optical film manufacturing apparatus 1 shown in FIGS. 1 and 2 uses an endless belt 12 as a support. Instead, the optical film manufacturing apparatus 1 uses a drum as a support. There may be. By rotating, the drum is dried while transporting the cast film 52 formed on the peripheral surface thereof.
  • the drum is preferably a metal drum having a mirror-finished surface.
  • the drum is preferably made of, for example, stainless steel from the viewpoint of peelability of the cast film 52.
  • the air intake device 14 and the air blower 15 have an annular shape surrounding the drum with a certain distance.
  • an optical film manufacturing method including a casting process in which a resin solution 51 is cast on a moving endless belt 12 to form a casting film 52. Then, an intake process by the intake device 14 that performs intake in the space above the casting film 52 immediately after casting on the endless belt 12, and subsequent to this suction process, a dry wind is applied to the casting film 52 on the endless belt 12.
  • the manufacturing method of the optical film which has the ventilation process by the air blower 15 which ventilates can be implemented.
  • optical film manufactured by such a manufacturing apparatus 1 or a manufacturing method maintains a favorable flatness, and is excellent in an optical characteristic.
  • optical film including a cellulose ester resin such as cellulose triacetate is manufactured.
  • thermoplastic resin composed of a cellulose ester resin or the like is dissolved in a mixed solvent of a good solvent and a poor solvent, and additives such as a plasticizer and an ultraviolet absorber are added thereto.
  • a resin solution (dope) 51 is prepared.
  • the dope 51 adjusted by the melting pot is fed to the casting die 11 by a conduit through, for example, a pressurized metering gear pump, and is transferred infinitely, for example, on a support made of a rotationally driven stainless steel endless belt 12.
  • the dope 51 is cast from the casting die 11 at the extending position.
  • the solid content concentration of the cellulose ester solution is preferably 15 to 30% by mass. If the solid content concentration of the cellulose ester solution (dope) is less than 15% by mass, sufficient drying cannot be performed on the support, and part of the dope film remains on the support during peeling, leading to belt contamination. It is not preferable. On the other hand, if the solid content concentration exceeds 30% by mass, the dope viscosity is increased, filter clogging is accelerated in the dope adjusting step, and pressure is increased during casting onto the support, which is not preferable.
  • various resins can be used as the film material, and among them, cellulose ester is preferable.
  • Cellulose ester is a cellulose ester in which a hydroxyl group derived from cellulose is substituted with an acyl group or the like.
  • examples thereof include cellulose acylates such as cellulose acetate, cellulose triacetate, cellulose acetate propionate, cellulose acetate butyrate and cellulose acetate propionate butyrate, and cellulose acetate having an aliphatic polyester graft side chain.
  • cellulose acetate, cellulose triacetate, cellulose acetate propionate, and cellulose acetate having an aliphatic polyester graft side chain are preferable.
  • Other substituents may be included as long as the effects of the present invention are not impaired.
  • the substitution degree of acetyl group is preferably 2.0 or more and 3.0 or less.
  • the acyl group total substitution degree is preferably 2.4 to 2.8
  • the acetyl group substitution degree is 0.1 to 0.2
  • the propionyl group substitution degree is preferably 2.4 to 2.6.
  • the substitution degree of the acetyl group is lower than this range, the heat resistance as a retardation film, particularly the dimensional stability under wet heat may be inferior, and if the substitution degree is too large, the necessary retardation characteristics will not be exhibited. There is a case.
  • the cellulose used as the raw material for the cellulose ester used in the present embodiment is not particularly limited, and examples thereof include cotton linter, wood pulp, and kenaf. Moreover, the cellulose ester obtained from them can be mixed and used in arbitrary ratios, respectively.
  • the number average molecular weight (Mn) of the cellulose ester is preferably in the range of 60,000 to 300,000, since the mechanical strength of the obtained film is strong. Furthermore, 70,000 to 200,000 are preferable. For the same reason, the weight average molecular weight (Mw) is preferably in the range of 100,000 to 400,000, more preferably in the range of 150,000 to 300,000.
  • various additives can be added to the cellulose ester.
  • a dope composition containing a cellulose ester and an additive for reducing the thickness direction retardation (Rt) can be used.
  • an organic solvent having good solubility for the cellulose derivative is referred to as a good solvent.
  • Examples of good solvents include ketones such as acetone, methyl ethyl ketone, cyclopentanone, cyclohexanone, ethers such as tetrahydrofuran (THF), 1,4-dioxane, 1,3-dioxolane, 1,2-dimethoxyethane, formic acid Esters such as methyl, ethyl formate, methyl acetate, ethyl acetate, amyl acetate, ⁇ -butyrolactone, methyl cellosolve, dimethylimidazolinone, dimethylformamide, dimethylacetamide, acetonitrile, dimethylsulfoxide, sulfolane, nitroethane, methylene chloride (Dichloromethane, methylene chloride), methyl acetoacetate and the like, and 1,3-dioxolane, THF, methyl ethyl ketone, acetone, methyl acetate
  • the dope preferably contains 1 to 40% by mass of an alcohol having 1 to 4 carbon atoms in addition to the organic solvent.
  • These are gels that, after casting the dope onto the support, the solvent begins to evaporate and the proportion of alcohol increases, making the web gel, making the web strong and easy to peel off from the support When used as a solvating solvent, or when the proportion of these is small, it also has a role of promoting the dissolution of a cellulose derivative of a non-chlorine organic solvent.
  • Examples of the alcohol having 1 to 4 carbon atoms include methanol, ethanol, n-propanol, iso-propanol, n-butanol, sec-butanol, tert-butanol, and propylene glycol monomethyl ether.
  • ethanol is preferred because it has excellent dope stability, has a relatively low boiling point, good drying properties, and no toxicity.
  • These organic solvents alone are not soluble in cellulose derivatives and are called poor solvents.
  • the most preferable solvent for dissolving a cellulose derivative, which is a preferable polymer compound satisfying such conditions, at a high concentration is a mixed solvent having a ratio of methylene chloride: ethyl alcohol of 95: 5 to 80:20.
  • a mixed solvent of methyl acetate: ethyl alcohol 60:40 to 95: 5 is also preferably used.
  • the film in the present embodiment includes a plasticizer that imparts processability, flexibility, and moisture resistance to the film, fine particles (matting agent) that impart slipperiness to the film, an ultraviolet absorber that imparts an ultraviolet absorbing function, and deterioration of the film. You may contain the antioxidant etc. which prevent this.
  • the plasticizer used in the present embodiment is not particularly limited, but is a cellulose derivative or a reactive metal compound capable of hydrolysis polycondensation so as not to generate haze, bleed out or volatilize from the film. It preferably has a functional group capable of interacting with the polycondensate by hydrogen bonding or the like.
  • Examples of such functional groups include hydroxyl groups, ether groups, carbonyl groups, ester groups, carboxylic acid residues, amino groups, imino groups, amide groups, imide groups, cyano groups, nitro groups, sulfonyl groups, sulfonic acid residues, Examples thereof include a phosphonyl group and a phosphonic acid residue, and a carbonyl group, an ester group and a phosphonyl group are preferred.
  • plasticizers examples include phosphate ester plasticizers, phthalate ester plasticizers, trimellitic acid ester plasticizers, pyromellitic acid plasticizers, polyhydric alcohol ester plasticizers, glycolate plasticizers. Agents, citric acid ester plasticizers, fatty acid ester plasticizers, carboxylic acid ester plasticizers, polyester plasticizers, etc. can be preferably used, but polyhydric alcohol ester plasticizers, glycolate plasticizers are particularly preferred. And non-phosphate ester plasticizers such as polycarboxylic acid ester plasticizers.
  • the polyhydric alcohol ester is composed of an ester of a dihydric or higher aliphatic polyhydric alcohol and a monocarboxylic acid, and preferably has an aromatic ring or a cycloalkyl ring in the molecule.
  • the polyhydric alcohol used in this embodiment is represented by the following general formula (1).
  • Formula (1) R1- (OH) n
  • R1 represents an n-valent organic group
  • n represents a positive integer of 2 or more.
  • Examples of preferred polyhydric alcohols include the following, but the present invention is not limited to these.
  • Examples of preferred polyhydric alcohols include adonitol, arabitol, ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, 1,2-propanediol, 1,3-propanediol, dipropylene glycol, tripropylene glycol, 1, 2-butanediol, 1,3-butanediol, 1,4-butanediol, dibutylene glycol, 1,2,4-butanetriol, 1,5-pentanediol, 1,6-hexanediol, hexanetriol, gallium
  • Examples include lactitol, mannitol, 3-methylpentane-1,3,5-triol, pinacol, sorbitol, trimethylolpropane, trimethylolethane, and xylitol.
  • the monocarboxylic acid used in the polyhydric alcohol ester of the present embodiment is not particularly limited, and known aliphatic monocarboxylic acid, alicyclic monocarboxylic acid, aromatic monocarboxylic acid and the like can be used. Use of an alicyclic monocarboxylic acid or aromatic monocarboxylic acid is preferred in terms of improving moisture permeability and retention.
  • Examples of preferred monocarboxylic acids include the following, but the present invention is not limited thereto.
  • aliphatic monocarboxylic acid a fatty acid having a straight chain or a side chain having 1 to 32 carbon atoms can be preferably used.
  • the number of carbon atoms is more preferably 1-20, and particularly preferably 1-10.
  • acetic acid is contained, the compatibility with the cellulose derivative is increased, and it is also preferable to use a mixture of acetic acid and another monocarboxylic acid.
  • Examples of preferred aliphatic monocarboxylic acids include acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, 2-ethyl-hexanecarboxylic acid, undecylic acid, lauric acid, Tridecylic acid, myristic acid, pentadecylic acid, palmitic acid, heptadecylic acid, stearic acid, nonadecanoic acid, arachidic acid, behenic acid, lignoceric acid, serotic acid, heptacosanoic acid, montanic acid, mellicic acid, laccellic acid, etc., undecylen Examples thereof include unsaturated fatty acids such as acid, oleic acid, sorbic acid, linoleic acid, linolenic acid, and arachidonic acid.
  • Examples of preferable alicyclic monocarboxylic acids include cyclopentane carboxylic acid, cyclohexane carboxylic acid, cyclooctane carboxylic acid, and derivatives thereof.
  • aromatic monocarboxylic acids examples include those in which an alkyl group is introduced into the benzene ring of benzoic acid such as benzoic acid and toluic acid, and two or more benzene rings such as biphenylcarboxylic acid, naphthalenecarboxylic acid, and tetralincarboxylic acid. Examples thereof include aromatic monocarboxylic acids and derivatives thereof, and benzoic acid is particularly preferable.
  • the molecular weight of the polyhydric alcohol ester is not particularly limited, but is preferably 300 to 1500, and more preferably 350 to 750. A higher molecular weight is preferred because it is less likely to volatilize, and a smaller one is preferred in terms of moisture permeability and compatibility with cellulose derivatives.
  • the carboxylic acid used in the polyhydric alcohol ester may be one kind or a mixture of two or more kinds. Moreover, all the OH groups in the polyhydric alcohol may be esterified, or a part of the OH groups may be left as they are.
  • the glycolate plasticizer is not particularly limited, but a glycolate plasticizer having an aromatic ring or a cycloalkyl ring in the molecule can be preferably used.
  • a glycolate plasticizer having an aromatic ring or a cycloalkyl ring in the molecule can be preferably used.
  • preferred glycolate plasticizers for example, butyl phthalyl butyl glycolate, ethyl phthalyl ethyl glycolate, methyl phthalyl ethyl glycolate and the like can be used.
  • phosphate plasticizers triphenyl phosphate, tricresyl phosphate, cresyl diphenyl phosphate, octyl diphenyl phosphate, diphenylbiphenyl phosphate, trioctyl phosphate, tributyl phosphate, etc.
  • phthalate ester plasticizers diethyl phthalate, dimethoxy Ethyl phthalate, dimethyl phthalate, dioctyl phthalate, dibutyl phthalate, di-2-ethylhexyl phthalate, dicyclohexyl phthalate, and the like can be used. In this embodiment, it is preferable that a phosphate ester plasticizer is not substantially contained.
  • substantially does not contain means that the content of the phosphoric ester plasticizer is less than 1% by mass, preferably 0.1% by mass, and particularly preferably not added.
  • plasticizers can be used alone or in combination of two or more.
  • the amount of plasticizer used is preferably 1 to 20% by mass. It is more preferably 6 to 16% by mass, particularly preferably 8 to 13% by mass. If the amount of the plasticizer used is less than 1% by mass relative to the cellulose derivative, the effect of reducing the moisture permeability of the film is small, so this is not preferred. If it exceeds 20% by mass, the plasticizer bleeds out from the film, and the film Since the physical properties of the material deteriorate, it is not preferable.
  • fine particles such as a matting agent
  • the fine particles include fine particles of an inorganic compound or fine particles of an organic compound.
  • inorganic compound fine particles include fine particles of silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide, tin oxide, and the like. Of these, fine particles of a compound containing a silicon atom are preferred, and fine silicon dioxide particles are particularly preferred.
  • silicon dioxide fine particles include Aerosil 200, 200V, 300, R972, R972V, R974, R202, R812, R805, OX50, and TT600 manufactured by Aerosil Co., Ltd.
  • organic compound fine particles include fine particles of acrylic resin, silicone resin, fluorine compound resin, urethane resin, and the like.
  • the primary particle size of the fine particles is not particularly limited, but the average particle size in the film is preferably about 0.05 to 5.0 ⁇ m. More preferably, it is 0.1 to 1.0 ⁇ m.
  • the average particle diameter of the fine particles refers to the average value of the lengths of the particles in the major axis direction when the cellulose ester film is observed with an electron microscope or an optical microscope. As long as the particles are observed in the film, they may be primary particles or secondary particles in which the primary particles are aggregated, but most of the particles that are usually observed are secondary particles.
  • the primary particle size, the particle size after being dispersed in a solvent, and the particle size added to the film often change, and what is important is that the fine particles are finally combined with the cellulose ester in the film to aggregate. And controlling the particle size formed.
  • the average particle size of the fine particles exceeds 5 ⁇ m, haze deterioration or the like may be observed, or it may cause a failure in a wound state as a foreign matter. Moreover, when the average particle diameter of fine particles is less than 0.05 ⁇ m, it becomes difficult to impart slipperiness to the film.
  • the above fine particles are used by adding 0.04 to 1.0 mass% with respect to the cellulose ester. Preferably, 0.05 to 0.6% by mass, more preferably 0.05 to 0.4% by mass is added.
  • the addition amount of the fine particles is less than 0.04% by mass, the film surface roughness becomes too smooth, and blocking occurs due to an increase in the friction coefficient. If the amount of fine particles added exceeds 1.0% by mass, the coefficient of friction on the film surface will be too low, causing winding misalignment during winding, and the transparency of the film will be low and haze will be high.
  • the above range is essential because it has no value as a film.
  • a 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.
  • the maximum pressure condition inside the apparatus is 980 N / cm 2 or more in a thin tube having a tube diameter of 1 to 2000 ⁇ m, for example, by processing with a high-pressure dispersion apparatus. More preferably, the maximum pressure condition inside the apparatus is 1960 N / cm 2 or more. Further, at that time, those having a maximum reaching speed of 100 m / sec or more and those having a heat transfer speed of 100 kcal / hr or more are preferable.
  • Examples of the high-pressure dispersing device as described above include an ultra-high pressure homogenizer (trade name, Microfluidizer) manufactured by Microfluidics Corporation, or a nanomizer manufactured by Nanomizer. Examples thereof include a homogenizer.
  • the fine particles are dispersed in a solvent containing 25 to 100% by mass of a lower alcohol, and then mixed with a dope in which a cellulose ester (cellulose derivative) is dissolved in a solvent, and the mixed solution is placed on a support.
  • a cellulose ester film is obtained which is cast and dried to form a film.
  • the content ratio of the lower alcohol is preferably 50 to 100% by mass, and more preferably 75 to 100% by mass.
  • examples of lower alcohols preferably include methyl alcohol, ethyl alcohol, propyl alcohol, isopropyl alcohol, butyl alcohol and the like.
  • the solvent other than the lower alcohol is not particularly limited, but it is preferable to use a solvent used at the time of forming a cellulose ester film.
  • Fine particles are dispersed in a solvent at a concentration of 1 to 30% by mass. Dispersing at a concentration higher than this is not preferable because the viscosity increases rapidly.
  • the concentration of the fine particles in the dispersion is preferably 5 to 25% by mass, more preferably 10 to 20% by mass.
  • the ultraviolet absorbing function of the film is preferably imparted to various optical films such as a polarizing plate protective film, a retardation film, and an optical compensation film from the viewpoint of preventing deterioration of the liquid crystal.
  • a material that absorbs ultraviolet rays may be included in the cellulose derivative, and a layer having an ultraviolet absorbing function may be provided on a film made of the cellulose derivative.
  • examples of the ultraviolet absorber that can be used include oxybenzophenone compounds, benzotriazole compounds, salicylic acid ester compounds, benzophenone compounds, cyanoacrylate compounds, nickel complex compounds, and the like. However, a benzotriazole-based compound with little coloring is preferable. Further, ultraviolet absorbers described in JP-A-10-182621 and JP-A-8-337574 and polymer ultraviolet absorbers described in JP-A-6-148430 are preferably used.
  • ultraviolet absorber those having excellent absorption ability of ultraviolet rays having a wavelength of 370 nm or less from the viewpoint of preventing deterioration of a polarizer or liquid crystal and those having little absorption of visible light having a wavelength of 400 nm or more from the viewpoint of liquid crystal display properties. preferable.
  • UV absorbers include 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-butyl) Phenyl) -5-chlorobenzotriazole, 2- (2′-hydroxy-3 ′-(3 ′′, 4 ′′, 5 ′′, 6 ′′ -tetrahydrophthalimidomethyl) -5′-methylphenyl) benzotriazole, 2,2 -Methylenebis (4- (1,1,3,3-tetramethylbutyl) -6- (2H-benzotriazol-2-yl) phenol, 2- (2'-hydride) Xy-3'-tert-butyl-5'-methylphenyl)
  • TINUVIN 109 TINUVIN 171
  • TINUVIN 326 all manufactured by Ciba Specialty Chemicals
  • -Sulfobenzophenone, bis (2-methoxy-4-hydroxy-5-benzoylphenylmethane) and the like can be mentioned, but are not limited thereto.
  • the blending amount of these ultraviolet absorbers is preferably in the range of 0.01 to 10% by mass, more preferably 0.1 to 5% by mass with respect to the cellulose ester (cellulose derivative). If the amount of the ultraviolet absorber used is too small, the ultraviolet absorbing effect may be insufficient. If the amount of the ultraviolet absorber is too large, the transparency of the film may be deteriorated.
  • the ultraviolet absorber is preferably one having high heat stability.
  • the ultraviolet absorber that can be used in the optical film of the present embodiment, the polymer ultraviolet absorber (or ultraviolet absorbing polymer) described in JP-A-6-148430 and JP-A-2002-47357 is preferably used.
  • it is represented by the general formula (1) described in JP-A-6-148430, the general formula (2), or the general formulas (3), (6), and (7) described in JP-A-2002-47357.
  • a polymer ultraviolet absorber is preferably used.
  • the cellulose ester film as an optical film finally produced has a moisture content of preferably 0.1 to 5%, more preferably 0.3 to 4%, and more preferably 0.5 to 2%. More preferably it is.
  • the optical film targeted by the present invention is a functional film used for various displays such as a liquid crystal display, a plasma display, and an organic EL display, particularly a liquid crystal display.
  • the optical film according to the present embodiment can be particularly preferably used as a protective film for a polarizing plate for a large liquid crystal display device or a liquid crystal display device for outdoor use as long as the above physical properties are satisfied.
  • a polarizing plate When using the optical film which concerns on this embodiment as a transparent protective film for polarizing plates, a polarizing plate can be produced by a general method. It is preferable that an adhesive layer is provided on the back surface side of the optical film according to the present embodiment, and is bonded to at least one surface of a polarizer produced by immersion and stretching in an iodine solution.
  • the optical film according to this embodiment may be used, or another transparent protective film for polarizing plate may be used.
  • a commercially available cellulose ester film for example, Konica Minoltack KC8UX, KC8UX2M, KC4UX, KC5UX, KC8UY, KC4UY, KC12UR, KC8UCR-3, KC8UCR-4, KC8UCR-5, KC8UE, KF4UE, KF4UE, KF4UE, C4R) KC4HR-1, KC8UY-HA, KC8UX-RHA, manufactured by Konica Minolta Opto Co., Ltd.) and the like are preferably used.
  • a polarizer which is a main component of a polarizing plate, is an element that transmits only light having a plane of polarization in a certain direction.
  • a typical polarizing film known at present is a polyvinyl alcohol polarizing film, which is a polyvinyl alcohol. There are one in which iodine is dyed on a system film and one in which dichroic dye is dyed.
  • a pressure-sensitive adhesive having a storage elastic modulus at 25 ° C. in the range of 1.0 ⁇ 10 4 Pa to 1.0 ⁇ 10 9 Pa in at least a part of the pressure-sensitive adhesive layer is used. It is preferable to use a curable pressure-sensitive adhesive that forms a high molecular weight body or a crosslinked structure by various chemical reactions after the pressure-sensitive adhesive is applied and bonded.
  • urethane adhesives examples include, for example, urethane adhesives, epoxy adhesives, aqueous polymer-isocyanate adhesives, curable adhesives such as thermosetting acrylic adhesives, moisture-curing urethane adhesives, polyether methacrylate types
  • curable adhesives such as thermosetting acrylic adhesives, moisture-curing urethane adhesives, polyether methacrylate types
  • anaerobic pressure-sensitive adhesives such as ester-based methacrylate type and oxidized polyether methacrylate, cyanoacrylate-based instantaneous pressure-sensitive adhesives, and acrylate-peroxide-based two-component instantaneous pressure-sensitive adhesives.
  • the above-mentioned pressure-sensitive adhesive may be a one-component type or a type in which two or more components are mixed before use.
  • the pressure-sensitive adhesive may be a solvent system using an organic solvent as a medium, or an aqueous system such as an emulsion type, a colloidal dispersion type, or an aqueous solution type that is a medium containing water as a main component. It may be a solvent type.
  • concentration of the pressure-sensitive adhesive liquid may be appropriately determined depending on the film thickness after adhesion, the coating method, the coating conditions, and the like, and is usually 0.1 to 50% by mass.
  • the polarizing plate according to the present embodiment includes a polarizer and a transparent protective film disposed on the surface of the polarizer, and the transparent protective film is the optical film.
  • the polarizer is an optical element that emits incident light by converting it into polarized light.
  • the polarizing plate for example, a completely saponified polyvinyl alcohol aqueous solution is used on at least one surface of a polarizer produced by immersing and stretching a polyvinyl alcohol film in an iodine solution.
  • a polarizer produced by immersing and stretching a polyvinyl alcohol film in an iodine solution.
  • the said optical film may be laminated
  • resin films such as cyclic olefin resin other than a cellulose-ester film, an acrylic resin, polyester, a polycarbonate. In this case, since the saponification suitability is low, it is preferable to perform an adhesive process on the polarizing plate through an appropriate adhesive layer.
  • the polarizing plate uses the optical film as a protective film laminated on at least one surface side of the polarizer.
  • the said optical film functions as a phase difference film, it is preferable to arrange
  • polarizer examples include, for example, a polyvinyl alcohol polarizing film.
  • Polyvinyl alcohol polarizing films include those obtained by dyeing iodine on polyvinyl alcohol films and those obtained by dyeing dichroic dyes.
  • a modified polyvinyl alcohol film modified with ethylene is preferably used as the polyvinyl alcohol film.
  • the polarizer is obtained as follows, for example. First, a film is formed using a polyvinyl alcohol aqueous solution. The obtained polyvinyl alcohol film is uniaxially stretched and then dyed or dyed and then uniaxially stretched. And preferably, a durability treatment is performed with a boron compound.
  • the film thickness of the polarizer is preferably 5 to 40 ⁇ m, more preferably 5 to 30 ⁇ m, and more preferably 5 to 20 ⁇ m.
  • a cellulose ester resin film When laminating a cellulose ester resin film on the surface of the polarizer, it is preferable to bond the cellulose ester resin film with an aqueous adhesive mainly composed of completely saponified polyvinyl alcohol or the like. Moreover, in the case of resin films other than a cellulose ester-type resin film, it is preferable to carry out the adhesive process to a polarizing plate through a suitable adhesion layer.
  • the polarizing plate as described above uses the optical film according to the present embodiment as a transparent protective film, so that the deformation of the optical film is sufficiently suppressed.
  • the optical film applied as a transparent protective film of a polarizing plate also suppresses dimensional changes due to changes in humidity, for example, when applied to a liquid crystal display device, so-called corner unevenness can also be suppressed.
  • the polarizing plate according to the present embodiment is a polarizing plate including a polarizer and two transparent protective films disposed on both sides of the polarizer so as to sandwich the polarizer, and the two sheets At least one of the transparent protective films is a polarizing plate characterized in that it is the optical film described above. This polarizing plate is excellent in optical characteristics while maintaining good flatness of the transparent protective film.
  • a polarizing plate in which the optical film according to this embodiment is bonded as a protective film for a liquid crystal polarizing plate into a liquid crystal display device, it is possible to produce various liquid crystal display devices with excellent visibility. It is preferably used for a liquid crystal display device for outdoor use such as a liquid crystal display device and digital signage.
  • the polarizing plate according to the present embodiment is bonded to the liquid crystal cell via the adhesive layer or the like.
  • the liquid crystal display device includes a liquid crystal cell and two polarizing plates arranged so as to sandwich the liquid crystal cell, and at least one of the two polarizing plates is the polarizing plate.
  • the liquid crystal cell is a cell in which a liquid crystal substance is filled between a pair of electrodes, and by applying a voltage to the electrodes, the alignment state of the liquid crystal is changed and the amount of transmitted light is controlled.
  • the use of the polarizing plate according to the present embodiment makes it possible to use an optical film whose deformation is sufficiently suppressed as a transparent protective film for the polarizing plate.
  • a high-quality liquid crystal display device is obtained.
  • the optical film in which the dimensional change by the humidity change was suppressed was used for the polarizing plate as a transparent protective film, what is called a corner nonuniformity can also be suppressed.
  • the liquid crystal display device is a liquid crystal display device including a liquid crystal cell and two polarizing plates arranged on both sides of the liquid crystal cell so as to sandwich the liquid crystal cell. At least one of the polarizing plates is a liquid crystal display device characterized in that it is the polarizing plate described above. This liquid crystal display device is excellent in optical characteristics while maintaining good flatness of the optical film or the transparent protective film of the polarizing plate.
  • An optical film manufacturing apparatus 1 is an optical film manufacturing apparatus 1 that performs a process of casting a resin solution 51 on a moving endless belt 12 to form a cast film 52, and is an endless belt. 12, the intake device 14 for performing the intake process of performing intake in the space above the casting film 52 immediately after casting, and the air blowing process to the casting film 52 following the intake process by the intake device 14. And an air blowing device 15 for executing the air blowing process.
  • the method for producing an optical film according to the present embodiment is a method for producing an optical film, which includes a step of casting a resin solution 51 on a moving endless belt 12 to form a cast film 52.
  • 12 has an intake process for performing intake in the space above the casting film 52 immediately after casting, and a blowing process for blowing dry air to the casting film 52 following the intake process.
  • the air blowing process is performed subsequent to the air intake process, the wind always flows through the space above the casting film 52, and the solvent evaporated from the casting film 52 is moved even when switching from the air intake process to the air blowing process. It is ensured and re-dissolution unevenness is suppressed.
  • the intake speed of the intake process is smaller than the blow speed of the blowing process. This is because unevenness of drying of the cast film 52 is further suppressed.
  • the intake speed in the intake process is 0.1 m / s to 3 m / s in terms of effective wind speed, and that the air speed in the blow process is in the range of 2 m / s to 30 m / s in terms of effective wind speed. . This is because in addition to the suppression of drying unevenness and remelting unevenness, insufficient drying of the cast film 52 is also suppressed.
  • the intake speed of the intake process is changed during the intake process and / or the blow speed of the blow process is changed during the blow process. This is because the casting film 52 can be dried according to the situation.
  • the amount of solvent in the casting film 52 with respect to the amount of solvent in the resin solution 51 before being cast on the endless belt 12 is reduced to 85% by mass to 95% by mass, It is preferable to switch from the intake process to the blow process. This is because drying unevenness and insufficient drying are further suppressed.
  • the shielding plate 16 that partitions the upper space of the casting film 52 that performs intake in the intake process and the upper space of the casting film 52 that performs blowing in the blowing process is provided with the shielding plate 16. It is preferable to provide a predetermined amount of gap between the casting film 52 and the casting film 52.
  • the intake air in the intake air process and the air in the air supply process do not interfere with each other, and the wind moves through the gap between the shielding plate 16 and the casting film 52. This is because uneven dissolution is further suppressed.
  • a preferable value of the gap between the shielding plate 16 and the casting film 52 varies depending on the situation, but is, for example, 1 mm to 300 mm.
  • the casting film is formed from this direction on the basis of the direction from the casting film 52 surface to the upper side of the casting film 52 along the normal line of the casting film 52 surface. It is preferable that air is sucked in a direction in which the side away from the surface 52 is inclined by 0 ° to 45 ° downstream of the casting film 52 in the moving direction.
  • the intake air causes the wind to flow downstream in the movement direction of the casting film 52, and the opposite wind (accompaniment wind) received by the casting film 52 is canceled by the movement of the casting film 52, so that the casting film 52 receives the wind. This is because unevenness in drying due to local flow is reliably suppressed.
  • the casting film is formed from this direction on the basis of the direction from the upper side of the casting film 52 to the surface of the casting film 52 along the normal line of the surface of the casting film 52. It is preferable that air is blown in a direction in which the side close to the surface 52 is inclined 0 ° to 80 ° downstream of the casting film 52 in the moving direction.
  • the wind causes the wind to flow downstream in the direction of movement of the casting film 52, and the opposite wind (accompaniment wind) received by the casting film 52 is canceled by the movement of the casting film 52, so that the casting film 52 receives the wind. This is because unevenness in drying due to local flow is reliably suppressed.
  • the moving speed of the endless belt 12 is preferably 60 m / min to 150 m / min (1 m / s to 2.5 m / s). This is because it can contribute to high-speed production of optical films.
  • an optical film having a film thickness of 15 ⁇ m to 60 ⁇ m. This is because it can contribute to thinning (thinning) of polarizing plates and liquid crystal display devices.
  • an optical film having a film thickness deviation of 0.2 ⁇ m to 1.5 ⁇ m in the width direction and the longitudinal direction of the film is preferable to manufacture an optical film having a film thickness deviation of 0.2 ⁇ m to 1.5 ⁇ m in the width direction and the longitudinal direction of the film. This is because good flatness is surely maintained, and an optical film having better optical properties can be obtained.
  • the optical film according to the present embodiment is an optical film manufactured by the manufacturing apparatus 1 or the manufacturing method. This optical film is excellent in optical properties while maintaining good flatness.
  • the polarizing plate according to the present embodiment is a polarizing plate using the optical film as a transparent protective film on at least one surface. This polarizing plate is excellent in optical characteristics while maintaining the good flatness of the transparent protective film.
  • the liquid crystal display device is a liquid crystal display device using the optical film or the polarizing plate. This liquid crystal display device is excellent in optical properties while maintaining good flatness of the optical film or transparent protective film.
  • Test 1 Using the apparatus similar to the optical film manufacturing apparatus 1 shown in FIG. 1, the prepared dope was subjected to a dope temperature of 34 ° C., a support (endless belt) temperature of 20 to 25 ° C., a cast film thickness of 280 ⁇ m, and a support moving The film was uniformly cast on an endless belt made of stainless steel at a speed of 80 m / min and a width of 2 m.
  • the intake device was used to perform intake under the conditions shown in Table 1 (intake speed 1 m / s at effective wind speed) (first operation).
  • a blower was used to blow dry air to the cast film under the conditions shown in Table 1 (blowing speed 3 m / s at the effective wind speed) using a blower (second operation).
  • Switching from the suction process (first operation) to the blowing process (second operation) is performed by changing the amount of solvent in the casting film to 90% of the amount of solvent (methylene chloride and ethanol) in the dope before casting on the endless belt. This was done when the mass was reduced.
  • the gap between the shielding plate provided at the boundary between the intake device and the blower and the casting film was 1 mm.
  • the direction of intake in the intake process was set to a direction inclined 45 ° downstream.
  • the direction of the air blowing in the air blowing process was a direction inclined by 80 ° on the downstream side.
  • the temperature of the drying air blown in the blowing step was 30 to 45 ° C.
  • the solvent was evaporated until the residual solvent ratio of the cast film reached 60% by mass, and the cast film was peeled from the endless belt with a peel tension of 100 N / m.
  • the peeled resin film is stretched 1.1 times (stretching rate: 10%) in the longitudinal direction (MD direction) and 1.2 times (stretching rate: 20%) in the width direction (TD direction) using a clip tenter. However, it was dried at 70 ° C. for 10 seconds.
  • An optical film (cellulose acetate film) that can be used as a transparent protective film for polarizing plates, for example, by winding it on a core with an initial tension of 220 N / m and a final tension of 110 N / m and an inner diameter of 15.24 cm after a knurling process of 5 ⁇ m.
  • a roll of Pionate film was obtained.
  • the residual solvent ratio of the manufactured optical film was 0.01%, the film thickness was 40 ⁇ m, the film thickness deviation in the width direction and the longitudinal direction of the film was 0.2 ⁇ m, and the winding length was 4000 m.
  • Test 2 As shown in Table 1, an optical film was produced in the same manner as in Test 1 except that the first operation was the air blowing step (the air blowing speed at the effective wind speed was 1 m / s).
  • Test 3 As shown in Table 1, an optical film was produced in the same manner as in Test 1 except that the first operation was not performed (intake and ventilation were not performed).
  • test number 2 was inferior to the result of drying unevenness
  • the air blowing process not the air intake process, was performed as the first operation, so that the casting film immediately hit the casting film.
  • test number 3 was inferior to the result of the remelting unevenness is considered to be that the air flow in the space above the casting film was weakened because neither the intake process nor the air blowing process was performed as the first operation.
  • test number 11 was slightly inferior to the result of the remelting unevenness is considered to be that the flow of wind in the space above the casting film was slightly weakened because the intake speed was excessively small.
  • test number 14 was slightly inferior to the result of the unevenness in drying was considered to be that the wind acted slightly on the casting film immediately after casting because the intake speed was excessively high.
  • test number 21 was insufficient drying of the cast film is thought to be because the blowing speed was excessively low.
  • test number 24 was slightly inferior to the result of drying unevenness is considered that the air blowing speed was excessively large.
  • test number 31 was slightly inferior to the result of drying unevenness is considered to be that the blowing was started at a stage where the amount of solvent in the cast film was relatively large.
  • the test number 34 was insufficient drying of the casting membrane because the blowing was started at a stage where the amount of solvent in the casting membrane was relatively small. This is probably because the time has been shortened.
  • test number 42 was slightly inferior to the result of the re-dissolution unevenness was that there was no shielding plate for separating the upper space of the casting film where the air intake device sucks air from the upper space of the casting film where the air blowing device blows air. This is probably because the intake air in the intake process interferes with the blow in the blowing process, and the flow of wind in the space above the casting film is slightly weakened, especially when switching from the intake process to the blowing process.
  • test number 52 was slightly inferior to the result of the re-dissolution unevenness was that the intake direction in the intake process was on the upstream side, so the intake in the intake process and the blow in the blow process interfered with each other (cancelled each other). It is considered that the flow of the wind in the upper space of the casting film was slightly weakened when switching from the process to the blow process.
  • test number 62 was slightly inferior to the result of the re-dissolution unevenness was that the air blowing direction in the air blowing process was on the upstream side, so that the air intake in the air intake process and the air in the air blowing process interfered (cancelled each other), It is considered that the flow of the wind in the upper space of the casting film was slightly weakened when switching from the process to the blow process.
  • test 4 the first operation (intake) was performed, but the second operation was not performed (intake and ventilation were not performed). As a result of the production, it was inferior to the result of uneven dissolution, and the cast film was insufficiently dried. Further, as test 5, an optical film was manufactured in the same manner as in test 1 except that a period in which neither intake nor ventilation was performed for several seconds was provided between the first operation (intake) and the second operation (air blow). However, it was still inferior to the result of uneven remelting, and the cast film was insufficiently dried.
  • the present invention can suppress unevenness in drying and re-dissolution of cast films when manufacturing an optical film by the solution casting film forming method. Therefore, the present invention is widely used in the technical field of manufacturing optical films by the solution casting film forming method. Have great industrial applicability.

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  • Moulding By Coating Moulds (AREA)

Abstract

In order to suppress uneven drying of a cast film due to the blowing of dry wind against the cast film, and uneven remelting of the cast film due to the weakened flow of wind in a space above the cast film when an optical film is manufactured by a solution casting film forming method, an optical film manufacturing method comprising a step for forming a cast film by casting a resin solution onto a moving support comprises: a suction step for sucking in air in a space above the cast film immediately after the casting onto the support, and a blowing step for, following the suction step, blowing a dry wind to the cast film. The suction speed in the suction step is lower than the blowing speed in the blowing step. The suction speed in the suction step is an effective wind speed of 0.1-3 m/s, and the blowing speed in the blowing step is an effective wind speed of 2-30 m/s. Switching from the suction step to the blowing step is performed when the amount of a solvent in the cast film with respect to the amount of a solvent in the resin solution before the casting onto the support decreases to 85-95% by mass.

Description

光学フィルムの製造装置及び製造方法、光学フィルム、偏光板並びに液晶表示装置Optical film manufacturing apparatus and manufacturing method, optical film, polarizing plate, and liquid crystal display device
　本発明は、光学フィルムの製造装置及び製造方法、この製造装置又は製造方法によって製造された光学フィルム、この光学フィルムを透明保護フィルムとして用いた偏光板、並びに、これらの光学フィルム又は偏光板を用いた液晶表示装置に関する。 The present invention relates to an optical film manufacturing apparatus and method, an optical film manufactured by the manufacturing apparatus or manufacturing method, a polarizing plate using the optical film as a transparent protective film, and these optical films or polarizing plates. The present invention relates to a liquid crystal display device.
　従来、光学フィルムの製造方法の１つとして、移動する支持体上に樹脂溶液（ドープ）を流延させて流延膜（ウェブ）を形成させる溶液流延製膜法が知られている。この溶液流延製膜法では、乾燥ムラを回避するため、支持体上に流延直後の流延膜に乾燥風を当てないようにすることがある。流延直後の流延膜は残留溶媒量が高いため、乾燥風を当てると、乾燥風を当てた箇所だけ流延膜が局所的に乾燥し、収縮し、流延膜に乾燥ムラが生じて、流延膜の平面性が低下する可能性があるからである。あるいは、流延直後の流延膜は残留溶媒量が高く流動性が高いため、乾燥風を当てると、乾燥風を当てた箇所だけ流延膜が局所的に流動し、変形し、流延膜に乾燥ムラが生じて、流延膜の平面性が低下する可能性があるからである。 Conventionally, as one method for producing an optical film, a solution casting film forming method is known in which a resin solution (dope) is cast on a moving support to form a casting film (web). In this solution casting film forming method, in order to avoid drying unevenness, drying air may not be applied to the casting film immediately after casting on the support. Since the cast film immediately after casting has a high residual solvent amount, when dry air is applied, the cast film is locally dried and contracted only at the location where the dry air is applied, resulting in uneven drying of the cast film. This is because the flatness of the cast film may be lowered. Alternatively, since the casting film immediately after casting has a high residual solvent amount and high fluidity, when the drying air is applied, the casting film locally flows and deforms only at the location where the drying air is applied. This is because unevenness in drying may occur and the flatness of the cast film may be deteriorated.
　このような乾燥ムラを回避するため、例えばヒータ等の輻射熱源を用いて流延膜を乾燥することが知られている。しかし、この場合、乾燥風を流さないから、流延膜の上方空間の風の流れが弱くなり、そのため、流延膜から蒸発した溶媒が流延膜の上方空間から移動せずに滞留する傾向となる。その結果、流延膜の上方空間の溶媒濃度が高くなり、溶媒が蒸発していったんゲル化しつつある流延膜の表面が局所的に再溶解し、流延膜に再溶解ムラが生じて、流延膜の平面性が低下する可能性がある。つまり、乾燥ムラが回避できても再溶解ムラが生じるのである。 In order to avoid such drying unevenness, for example, it is known to dry the cast film using a radiant heat source such as a heater. However, in this case, since the drying air is not flowed, the wind flow in the upper space of the casting film is weakened, and therefore, the solvent evaporated from the casting film tends to stay without moving from the upper space of the casting film. It becomes. As a result, the solvent concentration in the upper space of the casting film is increased, and the surface of the casting film that is once gelled as the solvent evaporates is locally re-dissolved, causing re-dissolution unevenness in the casting film, There is a possibility that the flatness of the cast film is lowered. That is, even if drying unevenness can be avoided, remelting unevenness occurs.
　特許文献１には、流延後の流延膜の温度がゲル化温度に達するまでは、風速が０．１～２．０ｍ／ｓ程度の相対的に弱い乾燥風を流延膜に当てて乾燥を行い、流延膜の温度がゲル化温度に達した後は、風速が２．０ｍ／ｓ以上の相対的に強い乾燥風を流延膜に当てて乾燥効率の高い乾燥を行なうことが開示されている。 In Patent Document 1, a relatively weak dry wind having a wind speed of about 0.1 to 2.0 m / s is applied to the casting film until the temperature of the casting film after casting reaches the gelling temperature. After drying and the temperature of the casting film reaches the gelation temperature, drying with high drying efficiency can be performed by applying relatively strong drying air with a wind speed of 2.0 m / s or more to the casting film. It is disclosed.
　特許文献２には、流延膜に乾燥風を当てるための送風用ノズルと、この送風用ノズルから流延膜に当てられた乾燥風の一部を吸引して外部に排気するための吸引口とを送風ダクトに備えることが開示されている。 Patent Document 2 discloses a blowing nozzle for applying a drying air to a casting film, and a suction port for sucking a part of the drying air applied to the casting film from the blowing nozzle and exhausting it to the outside. Is provided in the air duct.
特開平１１－５８４２５号公報（段落０００６、００１０）JP-A-11-58425 (paragraphs 0006 and 0010) 特開２００７－２９０３７０号公報（段落００４３、図３）JP 2007-290370 A (paragraph 0043, FIG. 3)
　特許文献１に開示されている技術では、いくら相対的に弱い乾燥風といっても、流延直後の流延膜に対して乾燥風を当てるため、乾燥ムラが発生する可能性が残る。 In the technique disclosed in Patent Document 1, no matter how weak the drying air is, the drying air is applied to the cast film immediately after casting, so that there is a possibility that uneven drying occurs.
　特許文献２に開示されている技術では、送風用ノズルを出た直後の乾燥風が吸引口に吸引される可能性があるから、流延膜の上方空間の風の流れが弱くなり、再溶解ムラが生じるおそれがある。 In the technique disclosed in Patent Document 2, since the dry air immediately after exiting the blowing nozzle may be sucked into the suction port, the flow of air in the upper space of the casting film becomes weak, and re-melting occurs. There may be unevenness.
　本発明の目的は、溶液流延製膜法により光学フィルムを製造するに際し、乾燥風が流延膜に当たることに起因する流延膜の乾燥ムラと、流延膜の上方空間の風の流れが弱くなることに起因する流延膜の再溶解ムラとを抑制することである。 The purpose of the present invention is to produce a non-uniformity in drying of the cast film caused by the dry air hitting the cast film and the flow of the wind in the space above the cast film when the optical film is produced by the solution casting film forming method. It is to suppress remelting unevenness of the cast film due to weakening.
　本発明の一局面は、移動する支持体上に樹脂溶液を流延させて流延膜を形成させる工程を行う光学フィルムの製造装置において、支持体上に流延直後の流延膜の上方空間において吸気を行なう吸気工程を実行するための吸気装置と、この吸気装置による吸気工程に続いて、流延膜に乾燥風を送風する送風工程を実行するための送風装置とを有することを特徴とする光学フィルムの製造装置である。 One aspect of the present invention is an optical film manufacturing apparatus that performs a step of casting a resin solution on a moving support to form a cast film, and an upper space of the cast film immediately after casting on the support. And an air blower for executing an air blowing process for blowing dry air to the casting film following the air intake process by the air intake device. This is an optical film manufacturing apparatus.
　本発明の他の局面は、移動する支持体上に樹脂溶液を流延させて流延膜を形成させる工程を有する光学フィルムの製造方法において、支持体上に流延直後の流延膜の上方空間において吸気を行なう吸気工程と、この吸気工程に続いて、流延膜に乾燥風を送風する送風工程とを有することを特徴とする光学フィルムの製造方法である。 Another aspect of the present invention is an optical film manufacturing method including a step of casting a resin solution on a moving support to form a cast film, and above the cast film immediately after casting on the support. An optical film manufacturing method comprising: an air intake step of performing air intake in a space; and an air blowing step of blowing dry air to a cast film following the air intake step.
　本発明のさらに他の局面は、前記製造装置又は製造方法によって製造されたことを特徴とする光学フィルムである。 Still another aspect of the present invention is an optical film manufactured by the manufacturing apparatus or the manufacturing method.
　本発明のさらに他の局面は、前記光学フィルムを透明保護フィルムとして少なくとも一方の面に用いたことを特徴とする偏光板である。 Still another aspect of the present invention is a polarizing plate using the optical film as a transparent protective film on at least one surface.
　本発明のさらに他の局面は、前記光学フィルム又は前記偏光板を用いたことを特徴とする液晶表示装置である。 Still another aspect of the present invention is a liquid crystal display device using the optical film or the polarizing plate.
　前記並びにその他の本発明の目的、特徴及び利点は、以下の詳細な記載と添付図面とから明らかになるであろう。 The above and other objects, features and advantages of the present invention will become apparent from the following detailed description and the accompanying drawings.
図１は、本発明の実施形態に係る光学フィルムの製造装置の概略構成図である。FIG. 1 is a schematic configuration diagram of an optical film manufacturing apparatus according to an embodiment of the present invention. 図２は、図１の光学フィルムの製造装置の支持体及びその周辺の拡大図である。FIG. 2 is an enlarged view of the support of the optical film manufacturing apparatus of FIG. 1 and its surroundings.
　以下、本発明の実施形態を説明するが、本発明はこれらの実施形態に限定されるものではない。 Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to these embodiments.
　＜光学フィルムの製造装置＞
　［全体構成］
　図１は、本発明の実施形態に係る光学フィルムの製造装置１の概略構成図である。この光学フィルムの製造装置１は、溶液流延製膜法により光学フィルムを製造するものであって、流延装置１０、延伸装置２０、熱処理装置３０、及び巻取装置４０を有する。 <Optical film manufacturing equipment>
[overall structure]
FIG. 1 is a schematic configuration diagram of an optical film manufacturing apparatus 1 according to an embodiment of the present invention. The optical film manufacturing apparatus 1 manufactures an optical film by a solution casting film forming method, and includes a casting apparatus 10, a stretching apparatus 20, a heat treatment apparatus 30, and a winding apparatus 40.
　流延装置１０は、ダイ１１、支持体である無端ベルト１２、及び剥離ロール１３を備える。ダイ１１は、樹脂を溶媒に溶解した樹脂溶液（ドープ）５１を吐出し、移動する無端ベルト１２上に流延させて流延膜（ウェブ）５２を形成させる。これを流延工程という。無端ベルト１２は、走行することにより、形成された流延膜５２を図中の矢印方向に移動させる。剥離ロール１３は、流延膜５２を無端ベルト１２から剥離し、剥離した流延膜５２、すなわち樹脂フィルム５３を延伸装置２０に送る。 The casting apparatus 10 includes a die 11, an endless belt 12 that is a support, and a peeling roll 13. The die 11 discharges a resin solution (dope) 51 in which a resin is dissolved in a solvent and casts it on the moving endless belt 12 to form a casting film (web) 52. This is called a casting process. The endless belt 12 moves to move the formed cast film 52 in the direction of the arrow in the figure. The peeling roll 13 peels the casting film 52 from the endless belt 12 and sends the peeled casting film 52, that is, the resin film 53 to the stretching device 20.
　延伸装置２０は、樹脂フィルム５３を搬送しながらクリップテンターやピンテンター等を用いて樹脂フィルム５３を長手方向（搬送方向（Machine Direction：ＭＤ方向））及び／又は幅手方向（搬送方向と直交する方向（Transverse Direction：ＴＤ方向））に延伸する。 The stretching device 20 uses a clip tenter, a pin tenter, or the like while transporting the resin film 53 to move the resin film 53 in the longitudinal direction (transport direction (machine direction: MD direction)) and / or the width direction (direction orthogonal to the transport direction). (Transverse Direction: TD direction)).
　熱処理装置３０は、延伸された樹脂フィルム５３を搬送しながら所定温度に加熱して熱処理する、すなわち乾燥させる。 The heat treatment apparatus 30 heats and heats the stretched resin film 53 to a predetermined temperature while being conveyed, that is, dries.
　巻取装置４０は、熱処理された樹脂フィルム５３を光学フィルムとしてロール状に巻き取る。 The winding device 40 winds the heat-treated resin film 53 as an optical film in a roll shape.
　なお、本実施形態では、光学フィルムとして、セルローストリアセテート等のセルロースエステル樹脂（以下、単に、セルロースエステルという場合がある）を含む光学フィルム（すなわちセルローストリアセテートフィルム又はセルロースエステルフィルム）が製造される。もっとも、これに限らず、例えば、アクリル樹脂とセルロースエステル樹脂とを含む光学フィルムが製造されてもよい。 In this embodiment, an optical film (that is, a cellulose triacetate film or a cellulose ester film) containing a cellulose ester resin such as cellulose triacetate (hereinafter sometimes simply referred to as cellulose ester) is produced as the optical film. But not only this but the optical film containing an acrylic resin and a cellulose-ester resin may be manufactured, for example.
　［ダイ］
　ダイ１１から吐出される樹脂溶液５１は、例えば、セルローストリアセテート等のセルロースエステル樹脂を、該セルロースエステル樹脂の良溶媒を含む溶媒に、溶解釜を用いて溶解することにより調製される。樹脂溶液５１中のセルロースエステル樹脂の含有量は、例えば１５～３０質量％であることが好ましい。 [Die]
The resin solution 51 discharged from the die 11 is prepared by, for example, dissolving a cellulose ester resin such as cellulose triacetate in a solvent containing a good solvent for the cellulose ester resin using a dissolution vessel. The content of the cellulose ester resin in the resin solution 51 is preferably 15 to 30% by mass, for example.
　セルロースエステル樹脂の溶解には、常圧で行う方法、溶媒の沸点以下で行う方法、溶媒の沸点以上で加圧して行う方法、特開平９－９５５４４号公報、特開平９－９５５５７号公報又は特開平９－９５５３８号公報に記載されるように、冷却溶解法で行う方法、特開平１１－２１３７９号公報に記載されるように高圧で行う方法等、種々の溶解方法を用いることができる。これらのうちでは、溶媒の沸点以上で加圧して行う方法が好ましい。 For dissolving the cellulose ester resin, a method carried out at normal pressure, a method carried out below the boiling point of the solvent, a method carried out under pressure above the boiling point of the solvent, JP-A-9-95544, JP-A-9-95557, or Various dissolution methods such as a method using a cooling dissolution method as described in Kaihei 9-95538 and a method using a high pressure as described in Japanese Patent Application Laid-Open No. 11-21379 can be used. Among these, the method of pressurizing at a temperature equal to or higher than the boiling point of the solvent is preferable.
　樹脂が溶媒に溶解された後、樹脂溶液５１は、濾材で濾過され、かつ脱泡される。濾過は、捕集粒子径が０．５～５μｍで、濾水時間が１０～２５ｓｅｃ／１００ｍｌの濾材を用いることが好ましい。 After the resin is dissolved in the solvent, the resin solution 51 is filtered through a filter medium and defoamed. For the filtration, it is preferable to use a filter medium having a collected particle diameter of 0.5 to 5 μm and a drainage time of 10 to 25 sec / 100 ml.
　樹脂溶液５１は、例えば加圧型定量ギヤポンプ等の送液ポンプによりダイ１１に送られる。ダイ１１は、吐出口の形状が調整可能なものが好ましい。また、流延膜５２の膜厚を均一にし易い加圧ダイが好ましい。加圧ダイとしては、コートハンガーダイやＴダイ等があり、いずれも好ましく用いられる。製膜速度を上げるために、加圧ダイを２基以上並べて配設し、樹脂溶液５１を分割して吐出してもよい。 The resin solution 51 is sent to the die 11 by a liquid feed pump such as a pressurized metering gear pump. The die 11 is preferably capable of adjusting the shape of the discharge port. Further, a pressure die that can easily make the film thickness of the casting film 52 uniform is preferable. Examples of the pressure die include a coat hanger die and a T die, and any of them is preferably used. In order to increase the film forming speed, two or more pressure dies may be arranged side by side, and the resin solution 51 may be divided and discharged.
　ダイ１１から樹脂溶液５１を吐出する吐出速度は、無端ベルト１２による流延膜５２の搬送速度との兼ね合いや生産性等を考慮して、例えば、３０～１５０ｍ／分程度であることが好ましい。 The discharge speed at which the resin solution 51 is discharged from the die 11 is preferably, for example, about 30 to 150 m / min in consideration of the balance with the transport speed of the casting film 52 by the endless belt 12 and productivity.
　［無端ベルト］
　無端ベルト１２は、表面が鏡面仕上げされた金属製のベルトである。無端ベルト１２は、流延膜５２の剥離性の観点から、例えばステンレス鋼製が好ましい。ダイ１１によって流延される流延膜５２の幅は、無端ベルト１２の幅を有効活用する観点から、無端ベルト１２の幅に対して、８０～９９％が好ましい。 [Endless belt]
The endless belt 12 is a metal belt having a mirror-finished surface. The endless belt 12 is preferably made of stainless steel, for example, from the viewpoint of peelability of the cast film 52. The width of the casting film 52 cast by the die 11 is preferably 80 to 99% with respect to the width of the endless belt 12 from the viewpoint of effectively utilizing the width of the endless belt 12.
　無端ベルト１２は、走行することにより、その表面上に形成された流延膜５２を搬送しながら流延膜５２を乾燥させる。この乾燥については、後に詳しく述べるが、一般には、例えば、無端ベルト１２の裏面をヒータや温風の吹き付けで加熱する方法、無端ベルト１２上の流延膜５２をヒータや温風の吹き付けで加熱する方法等によって行われ、必要に応じて適宜選択することが可能である。乾燥の際の流延膜５２の温度は、溶媒の蒸発に要する時間や搬送速度や生産性等を考慮して、－５～７０℃が好ましく、０～６０℃がより好ましい。流延膜５２の温度が高すぎると、流延膜５２が発泡したり、流延膜５２の平面性が劣化する傾向がある。本実施形態においては、後述するように、３０～４５℃程度が好ましい。 The endless belt 12 travels to dry the casting film 52 while transporting the casting film 52 formed on the surface thereof. Although this drying will be described in detail later, in general, for example, a method in which the back surface of the endless belt 12 is heated by blowing a heater or hot air, and the casting film 52 on the endless belt 12 is heated by blowing a heater or hot air. It is possible to select as appropriate according to need. The temperature of the casting film 52 at the time of drying is preferably −5 to 70 ° C., more preferably 0 to 60 ° C. in consideration of the time required for evaporation of the solvent, the conveyance speed, productivity, and the like. If the temperature of the casting film 52 is too high, the casting film 52 tends to foam or the flatness of the casting film 52 tends to deteriorate. In the present embodiment, as will be described later, about 30 to 45 ° C. is preferable.
　乾燥風を吹き付ける場合、その乾燥風の風圧は、溶媒蒸発の均一性等を考慮して、５０～５０００Ｐａであることが好ましい。乾燥風の温度は、一定の温度で乾燥してもよいし、無端ベルト１２の走行方向に数段階の温度に分けて吹き付けてもよい。乾燥風の温度は、例えば３０～４５℃程度が好ましい。 When blowing dry air, the wind pressure of the dry air is preferably 50 to 5000 Pa in consideration of the uniformity of solvent evaporation and the like. The temperature of the drying air may be dried at a constant temperature, or may be sprayed in several steps in the traveling direction of the endless belt 12. The temperature of the drying air is preferably about 30 to 45 ° C., for example.
　無端ベルト１２の上に流延膜５２を形成した後、無端ベルト１２から流延膜５２を剥離するまでの時間は、作製する光学フィルムの膜厚、使用する溶媒によっても異なるが、無端ベルト１２からの剥離性を考慮して、０．５～５分間の範囲であることが好ましい。 After the casting film 52 is formed on the endless belt 12, the time until the casting film 52 is peeled from the endless belt 12 varies depending on the film thickness of the optical film to be produced and the solvent used, but the endless belt 12. In view of peelability from the film, it is preferably in the range of 0.5 to 5 minutes.
　無端ベルト１２による流延膜５２の搬送速度（つまり無端ベルト１２の移動速度）は、光学フィルムの高速生産に寄与し得る観点から、例えば、６０ｍ／分～１５０ｍ／分（１ｍ／ｓ～２．５ｍ／ｓ）であることが好ましい。ダイ１１からの樹脂溶液５１の吐出速度Ｖ１に対する、無端ベルト１２による流延膜５２の搬送速度Ｖ２の比（Ｖ２／Ｖ１）（ドラフト比）は、０．８～２．０程度であることが好ましい。ドラフト比がこの範囲内であると、安定して流延膜５２を形成させることができる。一方、ドラフト比が大きすぎると、流延膜５２が幅手方向に縮小されるネックインという現象を発生させる傾向があり、そうなると、広幅のフィルムの形成が困難となる。 The transport speed of the casting film 52 by the endless belt 12 (that is, the moving speed of the endless belt 12) is, for example, from 60 m / min to 150 m / min (1 m / s to 2.. 5 m / s). The ratio (V2 / V1) (draft ratio) of the transport speed V2 of the cast film 52 by the endless belt 12 to the discharge speed V1 of the resin solution 51 from the die 11 is about 0.8 to 2.0. preferable. When the draft ratio is within this range, the casting film 52 can be stably formed. On the other hand, when the draft ratio is too large, there is a tendency to cause a phenomenon called neck-in in which the casting film 52 is reduced in the width direction, which makes it difficult to form a wide film.
　［剥離ロール］
　剥離ロール１３は、無端ベルト１２の表面に加圧された状態で接しており、乾燥された流延膜５２を無端ベルト１２から剥離する。この剥離時の剥離張力は、５０～４００Ｎ／ｍの範囲が好ましい。また、剥離時における流延膜５２の残留溶媒率は、無端ベルト１２からの剥離性、剥離後の搬送性、製造される光学フィルムの物理特性等を考慮して、３０～２００質量％であることが好ましい。 [Peeling roll]
The peeling roll 13 is in contact with the surface of the endless belt 12 in a pressurized state, and peels the dried casting film 52 from the endless belt 12. The peeling tension at the time of peeling is preferably in the range of 50 to 400 N / m. The residual solvent ratio of the cast film 52 at the time of peeling is 30 to 200% by mass in consideration of the peelability from the endless belt 12, the transportability after peeling, the physical properties of the optical film to be manufactured, and the like. It is preferable.
　ここで、残留溶媒率は、次式で定義される。
残留溶媒率（％）＝｛（流延膜の加熱処理前の質量－流延膜の加熱処理後の質量）／流延膜の加熱処理後の質量｝×１００
なお、残留溶媒率を測定する際の加熱処理とは、１１５℃で１時間の加熱処理である。 Here, the residual solvent ratio is defined by the following equation.
Residual solvent ratio (%) = {(mass before heat treatment of cast film−mass after heat treatment of cast film) / mass after heat treatment of cast film} × 100
Note that the heat treatment for measuring the residual solvent ratio is a heat treatment at 115 ° C. for 1 hour.
　［延伸装置］
　延伸装置２０は、無端ベルト１２から剥離された流延膜５２である樹脂フィルム５３の幅手方向の両側縁部をクリップテンターやピンテンター等で把持して樹脂フィルム５３を長手方向（ＭＤ方向）及び／又は幅手方向（ＴＤ方向）に延伸する。 [Stretching device]
The stretching device 20 grips both lateral edges of the resin film 53, which is the casting film 52 peeled from the endless belt 12, with a clip tenter, a pin tenter, etc., to hold the resin film 53 in the longitudinal direction (MD direction) and / Or extends in the width direction (TD direction).
　ここでの樹脂フィルム５３のＴＤ方向の延伸率は、５～３０％程度であることが好ましい。一般に、延伸率を高くすると、光学フィルムの光学値が不均一になり易い。しかし、ここでの樹脂フィルム５３のＴＤ方向の延伸率を５～３０％とすると、光学フィルムの光学値が不均一になることを抑制できる。したがって、光学値が均一で、かつ広幅の光学フィルムを得ることができる。また、光学フィルムの幅が広いと、大型の液晶表示装置への使用、偏光板加工時のフィルムの使用効率、生産効率の点からも好ましい。 Here, the stretching ratio in the TD direction of the resin film 53 is preferably about 5 to 30%. In general, when the stretching ratio is increased, the optical value of the optical film tends to be nonuniform. However, if the stretching ratio of the resin film 53 in the TD direction is 5 to 30%, it is possible to prevent the optical value of the optical film from becoming non-uniform. Therefore, an optical film having a uniform optical value and a wide width can be obtained. Moreover, when the width | variety of an optical film is wide, it is preferable also from the point of use to a large sized liquid crystal display device, the use efficiency of the film at the time of polarizing plate processing, and production efficiency.
　ここで、ＴＤ方向の延伸率は、次式で定義される。
ＴＤ方向の延伸率（％）＝｛（フィルムの所定位置における延伸後の幅手方向の長さ－フィルムの所定位置における延伸前の幅手方向の長さ）／フィルムの所定位置における延伸前の幅手方向の長さ｝×１００
なお、フィルムの幅手方向の長さは、Ｃ型ＪＩＳ１級の鋼製スケールで測定した値である。 Here, the stretching ratio in the TD direction is defined by the following equation.
Stretch ratio (%) in TD direction = {(length in the width direction after stretching at a predetermined position of the film−length in the width direction before stretching at a predetermined position of the film) / before stretching at a predetermined position of the film Length in the width direction} × 100
The length in the width direction of the film is a value measured with a C-type JIS grade 1 steel scale.
　また、ＭＤ方向の延伸率は、次式で定義される。
ＭＤ方向の延伸率（％）＝｛（延伸後のフィルムの搬送速度－延伸前のフィルムの搬送速度）／延伸前のフィルムの搬送速度｝×１００ Moreover, the draw ratio in the MD direction is defined by the following equation.
Stretching rate in MD direction (%) = {(Conveying speed of film after stretching−Conveying speed of film before stretching) / Conveying speed of film before stretching} × 100
　［熱処理装置］
　熱処理装置３０は、複数の搬送ロールを備え、そのロール間を樹脂フィルム５３を搬送させる間に樹脂フィルム５３を乾燥させる。その際、加熱空気、赤外線等を単独で用いて乾燥してもよいし、加熱空気と赤外線とを併用して乾燥してもよい。簡便さの点から加熱空気を用いることが好ましい。乾燥温度としては、樹脂フィルム５３の残留溶媒率により、好適温度が異なるが、乾燥時間、収縮ムラ、伸縮量の安定性等を考慮し、３０～１８０℃の範囲で残留溶媒率により適宜選択して決めればよい。また、一定の温度で乾燥してもよいし、２～４段階の温度に分けて、数段階の温度に分けて乾燥してもよい。 [Heat treatment equipment]
The heat treatment apparatus 30 includes a plurality of transport rolls, and dries the resin film 53 while transporting the resin film 53 between the rolls. In that case, you may dry using heating air, infrared rays, etc. independently, and you may dry using heating air and infrared rays together. It is preferable to use heated air from the viewpoint of simplicity. The drying temperature varies depending on the residual solvent ratio of the resin film 53, but is appropriately selected depending on the residual solvent ratio in the range of 30 to 180 ° C. in consideration of drying time, shrinkage unevenness, stability of expansion and contraction, etc. You can decide. Further, it may be dried at a constant temperature, or may be divided into two to four stages of temperature and may be divided into several stages of temperature.
　［巻取装置］
　巻取装置４０は、延伸装置２０で延伸させ、熱処理装置３０で乾燥させた樹脂フィルム５３を必要量の長さに巻き芯に巻き取る。なお、巻き取る際の温度は、巻き取り後の収縮によるスリキズ、巻き緩み等を防止するために室温まで冷却することが好ましい。使用する巻き取り機は、特に限定なく使用でき、一般的に使用されているものでよく、定テンション法、定トルク法、テーパーテンション法、内部応力一定のプログラムテンションコントロール法等の巻き取り方法で巻き取ることができる。 [Winding device]
The winding device 40 winds the resin film 53 that has been stretched by the stretching device 20 and dried by the heat treatment device 30 to a required length to be wound around 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 can be used without any particular limitation, and may be a commonly used one, 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. Can be wound up.
　ここで巻き取る光学フィルムの幅は、１０００～４０００ｍｍであることが好ましい。このような広幅の光学フィルムは、大型の液晶表示装置への使用、偏光板加工時のフィルムの使用効率、生産効率の点から好ましい。また、光学フィルムの膜厚は、偏光板や液晶表示装置の薄膜化（薄型化）や、フィルムの生産安定化等に寄与し得る観点から、１５μｍ～６０μｍであることが好ましい。ここで膜厚とは、平均膜厚のことであり、例えば、東京精密株式会社製の膜厚測定器ＤＨ－１５０や、株式会社ミツトヨ製の接触式膜厚計等を用いて、光学フィルムの長手方向及び幅手方向に２０～２００箇所、膜厚を測定し、その測定値の平均値を膜厚として示した値である。 Here, the width of the optical film to be wound is preferably 1000 to 4000 mm. Such a wide optical film is preferable from the viewpoints of use in a large liquid crystal display device, use efficiency of the film during polarizing plate processing, and production efficiency. Further, the film thickness of the optical film is preferably 15 μm to 60 μm from the viewpoint of contributing to thinning (thinning) the polarizing plate and the liquid crystal display device and stabilizing production of the film. Here, the film thickness is an average film thickness. For example, a film thickness measuring instrument DH-150 manufactured by Tokyo Seimitsu Co., Ltd., a contact-type film thickness meter manufactured by Mitutoyo Co., Ltd., or the like is used. The film thickness is measured at 20 to 200 locations in the longitudinal direction and the width direction, and the average value of the measured values is shown as the film thickness.
　また、光学フィルムの幅手方向及び長手方向の膜厚偏差は、光学フィルムの良好な平面性が確実に維持されて、光学フィルムの光学特性がより一層優れるという観点から、０．２μｍ～１．５μｍであることが好ましい。 The film thickness deviation in the width direction and the longitudinal direction of the optical film is 0.2 μm to 1.m from the viewpoint that the good flatness of the optical film is reliably maintained and the optical properties of the optical film are further improved. It is preferably 5 μm.
　＜本実施形態の特徴＞
　図２は、前記製造装置１の無端ベルト１２及びその周辺の拡大図である。図中、符号１４は吸気装置、符号１５は送風装置、符号１６は遮蔽板を示す。 <Features of this embodiment>
FIG. 2 is an enlarged view of the endless belt 12 of the manufacturing apparatus 1 and its surroundings. In the figure, reference numeral 14 denotes an intake device, reference numeral 15 denotes a blower, and reference numeral 16 denotes a shielding plate.
　吸気装置１４は、無端ベルト１２上に流延直後の流延膜５２の上方空間において吸気を行なう吸気工程を実行するためのものである。送風装置１５は、この吸気装置１４による吸気工程に続いて、無端ベルト１２上の流延膜５２に乾燥風を送風する送風工程を実行するためのものである。吸気装置１４は、ダイ１１に隣接して、ダイ１１よりも、流延膜５２の移動方向下流側に配置されている。送風装置１５は、吸気装置１４に連続して、吸気装置１４よりも、流延膜５２の移動方向下流側に配置されている。 The intake device 14 is for executing an intake process of performing intake on the endless belt 12 in the space above the casting film 52 immediately after casting. The air blower 15 is for performing the air blow process which blows dry air to the casting film 52 on the endless belt 12 following the air intake process by the air intake apparatus 14. The intake device 14 is disposed adjacent to the die 11 and downstream of the die 11 in the moving direction of the casting film 52. The air blower 15 is arranged downstream of the air intake device 14 in the moving direction of the casting film 52, following the air intake device 14.
　吸気装置１４及び送風装置１５は、無端ベルト１２の周面から一定距離をおいて、無端ベルト１２を取り巻くように無端ベルト１２の周囲に配置されている。吸気装置１４及び送風装置１５の無端ベルト１２との対向面、すなわち底面には、無端ベルト１２の全幅に亘って幅手方向に延びるスリット形状の吸気口及び送風口が多数設けられている。そして、吸気装置１４及び送風装置１５に内装された多数のノズル（図示せず）の向きを変えることによって、吸気装置１４による吸気の方向（符号ａ）及び送風装置１５による送風の方向（符号ｂ）が自由に変更可能とされている。 The intake device 14 and the blower device 15 are arranged around the endless belt 12 so as to surround the endless belt 12 at a certain distance from the circumferential surface of the endless belt 12. A large number of slit-shaped air inlets and air outlets extending in the width direction over the entire width of the endless belt 12 are provided on the surfaces of the air intake device 14 and the air blower 15 facing the endless belt 12, that is, the bottom surface. Then, by changing the direction of a large number of nozzles (not shown) incorporated in the intake device 14 and the blower device 15, the direction of intake air by the intake device 14 (symbol a) and the direction of air blow by the blower device 15 (symbol b). ) Is freely changeable.
　なお、本実施形態において、流延膜５２の上方とは、文字通り流延膜５２より上の方向という意味の他、流延膜５２表面から吸気装置１４及び送風装置１５の底面に向かって流延膜５２表面から離間する方向をいう。 In the present embodiment, the term “above the casting film 52” literally means a direction above the casting film 52, and the casting film 52 is cast from the surface of the casting film 52 toward the bottom surfaces of the intake device 14 and the blower device 15. A direction away from the surface of the film 52.
　このような構成により、移動する無端ベルト１２上に樹脂溶液５１を流延させて流延膜５２を形成させる流延工程を有する光学フィルムの製造方法が実現される。そして、無端ベルト１２上に流延直後の流延膜５２の上方空間において吸気を行なう吸気工程が吸気装置１４により実行され、この吸気工程に続いて、無端ベルト１２上の流延膜５２に乾燥風を送風する送風工程が送風装置１５により実行される。 With such a configuration, an optical film manufacturing method having a casting process in which the resin solution 51 is cast on the moving endless belt 12 to form the casting film 52 is realized. Then, the intake device 14 executes an intake process in which air is sucked in the space above the casting film 52 immediately after casting on the endless belt 12, and the casting film 52 on the endless belt 12 is dried after the suction process. A blowing process for blowing wind is performed by the blower 15.
　このような光学フィルムの製造装置１又は光学フィルムの製造方法によれば、流延直後の流延膜５２に対しては、乾燥風を当てないので、流延膜５２の乾燥ムラが抑制される。代わりに、流延直後の流延膜５２に対しては、流延膜５２の上方空間において吸気を行なうので、流延膜５２の上方空間の風の流れが弱くならず、流延膜５２から蒸発した溶媒の移動が確保されて、流延膜５２の再溶解ムラが抑制される。そして、この吸気工程の後に、流延膜５２に乾燥風を送風するので、乾燥ムラ及び再溶解ムラを抑制しつつ、流延膜５２の乾燥が促進される。しかも、吸気工程に続いて送風工程が行われるので、常に流延膜５２の上方空間を風が流れ、吸気工程から送風工程への切替時においても、流延膜５２から蒸発した溶媒の移動が確保されて、再溶解ムラが抑制される。 According to such an optical film manufacturing apparatus 1 or an optical film manufacturing method, drying air is not applied to the casting film 52 immediately after casting, so that drying unevenness of the casting film 52 is suppressed. . Instead, since the air is sucked in the space above the casting film 52 with respect to the casting film 52 immediately after casting, the flow of wind in the space above the casting film 52 does not weaken, and the casting film 52 Movement of the evaporated solvent is ensured, and uneven remelting of the casting film 52 is suppressed. Then, after this intake step, the drying air is blown to the casting film 52, so that drying of the casting film 52 is promoted while suppressing drying unevenness and remelting unevenness. In addition, since the air blowing process is performed subsequent to the air intake process, the wind always flows through the space above the casting film 52, and the solvent evaporated from the casting film 52 is moved even when switching from the air intake process to the air blowing process. It is ensured and re-dissolution unevenness is suppressed.
　遮蔽板１６は、吸気装置１４が吸気を行なう流延膜５２の上方空間と、送風装置１５が送風を行なう流延膜５２の上方空間とを仕切るためのものである。遮蔽板１６と流延膜５２との間に所定量の間隙が残されている。その間隙の好ましい値は、状況により変化するが、例えば１ｍｍ～３００ｍｍである。 The shielding plate 16 is for partitioning the upper space of the casting film 52 where the air suction device 14 sucks air from the upper space of the casting film 52 where the air blowing device 15 blows air. A predetermined amount of gap is left between the shielding plate 16 and the casting film 52. A preferable value of the gap varies depending on the situation, but is, for example, 1 mm to 300 mm.
　遮蔽板１６は、吸気装置１４と送風装置１５との境界部分に、矢印ｃ，ｄで示すように、移動可能に設けられている。つまり、この光学フィルムの製造装置１には、図外に吸引通路と送風通路とが備えられており、吸気装置１４及び送風装置１５の吸気口及び送風口は、それぞれ、バルブ等の通路切替手段により、吸引通路又は送風通路のいずれか一方と選択的に連通可能とされている。そして、吸気装置１４として動作する部分と、送風装置１５として動作する部分との境目に、遮蔽板１６が移動される。 The shielding plate 16 is movably provided at the boundary between the intake device 14 and the blower device 15 as indicated by arrows c and d. That is, the optical film manufacturing apparatus 1 is provided with a suction passage and a blower passage (not shown), and the intake port and the blower port of the intake device 14 and the blower device 15 are respectively a passage switching means such as a valve. Thus, it is possible to selectively communicate with either the suction passage or the air passage. Then, the shielding plate 16 is moved at the boundary between the portion that operates as the intake device 14 and the portion that operates as the blower device 15.
　このような遮蔽板１６により、吸気工程の吸気と送風工程の送風とが干渉し合わないと共に、遮蔽板１６と流延膜５２との間の間隙を介して風が移動するので、吸気工程から送風工程への切替時において再溶解ムラがより一層抑制される。 With such a shielding plate 16, the intake air in the intake process and the blown air in the blowing process do not interfere with each other, and the wind moves through the gap between the shielding plate 16 and the casting film 52. Remelting unevenness is further suppressed when switching to the blowing process.
　本実施形態においては、吸気工程の吸気速度は、送風工程の送風速度よりも小さいことが好ましい。流延膜５２の乾燥ムラがより一層抑制されるからである。 In this embodiment, it is preferable that the intake speed of the intake process is smaller than the blow speed of the blow process. This is because unevenness of drying of the cast film 52 is further suppressed.
　本実施形態においては、吸気工程の吸気速度は実効風速で０．１ｍ／ｓ～３ｍ／ｓ、送風工程の送風速度は実効風速で２ｍ／ｓ～３０ｍ／ｓであることが好ましい。乾燥ムラ及び再溶解ムラの抑制に加えて、流延膜５２の乾燥不足も抑制されるからである。 In the present embodiment, it is preferable that the intake speed of the intake process is 0.1 m / s to 3 m / s in terms of effective wind speed, and the blow speed of the blow process is preferably 2 m / s to 30 m / s in terms of effective wind speed. This is because in addition to the suppression of drying unevenness and remelting unevenness, insufficient drying of the cast film 52 is also suppressed.
　本実施形態においては、吸気工程の吸気速度を吸気工程中変化させること、及び／又は、送風工程の送風速度を送風工程中変化させることが好ましい。状況に応じた流延膜５２の乾燥が実現するからである。例えば、吸気工程の吸気速度を実効風速で０．１ｍ／ｓから２ｍ／ｓまで徐々に又は段階的に上げていき、この吸気工程に続いて、送風工程の送風速度を実効風速で２ｍ／ｓから３０ｍ／ｓまで徐々に又は段階的に上げていくことができる。 In this embodiment, it is preferable to change the intake speed of the intake process during the intake process and / or change the blow speed of the blow process during the blow process. This is because the casting film 52 can be dried according to the situation. For example, the intake speed of the intake process is gradually or stepwise increased from 0.1 m / s to 2 m / s as an effective wind speed, and following this intake process, the blow speed of the blow process is set to 2 m / s as an effective wind speed. From 30 m / s to 30 m / s.
　本実施形態においては、無端ベルト１２上に流延させる前の樹脂溶液５１中の溶媒量に対する流延膜５２中の溶媒量が８５質量％～９５質量％に低下したときに、吸気工程から送風工程への切替えを行なうことが好ましい。乾燥ムラ及び乾燥不足がより一層抑制されるからである。 In the present embodiment, when the amount of solvent in the casting film 52 with respect to the amount of solvent in the resin solution 51 before being cast on the endless belt 12 is reduced to 85% by mass to 95% by mass, air is blown from the intake process. It is preferable to switch to a process. This is because drying unevenness and insufficient drying are further suppressed.
　なお、無端ベルト１２上に流延された流延膜５２が流延装置１０のどの地点まで移動したときに、流延膜５２中の溶媒量が８５質量％～９５質量％まで低下するかについては、例えば、樹脂溶液５１の組成、無端ベルト１２の移動速度、吸気工程の吸気速度等の種々のパラメータに基いて予め実験的に求めておくことができる。 Note that when the casting film 52 cast on the endless belt 12 moves to which point of the casting apparatus 10, the amount of the solvent in the casting film 52 decreases to 85 mass% to 95 mass%. Can be experimentally obtained in advance based on various parameters such as the composition of the resin solution 51, the moving speed of the endless belt 12, and the intake speed of the intake process.
　本実施形態においては、吸気工程において、流延膜５２表面の法線に沿って流延膜５２表面から流延膜５２上方へ向かう方向を基準として、この方向から、流延膜５２表面から離間する側が流延膜５２の移動方向下流側に０°～４５°傾斜する方向に吸気することが好ましい。例えば、図２では、下流側に４５°傾斜する方向に吸気することが示されている。これにより、吸気によって風が流延膜５２の移動方向下流側に流れることとなり、流延膜５２の移動により流延膜５２が受ける向かい風（伴走風）が打ち消されるので、流延膜５２が風を受けて局所的に流動することによる乾燥ムラが確実に抑制される。また、下流側に４５°を超えて傾斜する方向に吸気したときは、結果的に溶媒が流延膜５２の上方空間に長く滞留する状態となり、再溶解ムラが懸念されるので好ましくない。 In the present embodiment, in the intake step, the direction from the surface of the casting film 52 toward the upper side of the casting film 52 along the normal line of the surface of the casting film 52 is used as a reference, and is separated from the surface of the casting film 52 from this direction. It is preferable that the intake side inhales in a direction inclined at 0 ° to 45 ° downstream of the casting film 52 in the moving direction. For example, FIG. 2 shows that the air is sucked in a direction inclined 45 ° downstream. As a result, the wind flows to the downstream side in the movement direction of the casting film 52 due to the intake air, and the head wind (accompaniment wind) received by the casting film 52 is canceled by the movement of the casting film 52, so that the casting film 52 And drying unevenness due to local flow is reliably suppressed. In addition, when the air is sucked in the direction inclined at an angle exceeding 45 ° on the downstream side, the solvent will stay in the upper space of the casting film 52 as a result, and there is a concern about re-dissolution unevenness, which is not preferable.
　本実施形態においては、送風工程において、流延膜５２表面の法線に沿って流延膜５２上方から流延膜５２表面へ向かう方向を基準として、この方向から、流延膜５２表面に近接する側が流延膜５２の移動方向下流側に０°～８０°傾斜する方向に送風することが好ましい。例えば、図２では、下流側に６３°傾斜する方向に送風することが示されている。これにより、送風によって風が流延膜５２の移動方向下流側に流れることとなり、流延膜５２の移動により流延膜５２が受ける向かい風（伴走風）が打ち消されるので、流延膜５２が風を受けて局所的に流動することによる乾燥ムラが確実に抑制される。また、下流側に８０°を超えて傾斜する方向に送風したときは、結果的に溶媒が流延膜５２の上方空間に長く滞留する状態となり、再溶解ムラが懸念されるので好ましくない。 In the present embodiment, in the air blowing step, the direction from the upper side of the casting film 52 toward the surface of the casting film 52 along the normal line of the surface of the casting film 52 is used as a reference, and the proximity to the surface of the casting film 52 from this direction. It is preferable that the air flowing side is blown in a direction inclined at 0 ° to 80 ° downstream of the casting film 52 in the moving direction. For example, FIG. 2 shows that the air is blown in a direction inclined by 63 ° on the downstream side. As a result, the wind causes the wind to flow to the downstream side in the moving direction of the casting film 52, and the head wind (accompaniment wind) received by the casting film 52 is canceled by the movement of the casting film 52. And drying unevenness due to local flow is reliably suppressed. Moreover, when it blows in the direction which inclines over 80 degrees downstream, as a result, it will be in the state which a solvent will remain in the upper space of the casting film 52, and a remelting nonuniformity may be anxious, and is unpreferable.
　本実施形態においては、送風工程で送風する乾燥風の温度は、前述したように、例えば３０～４５℃程度が好ましい。 In the present embodiment, the temperature of the drying air blown in the blowing step is preferably about 30 to 45 ° C. as described above.
　＜他の実施形態＞
　図１、図２に示した光学フィルムの製造装置１は、支持体として無端ベルト１２を用いたものであったが、これに代えて、支持体としてドラムを用いた光学フィルムの製造装置１であってもよい。ドラムは、回動することにより、その周面上に形成された流延膜５２を搬送しながら乾燥させる。ドラムは、表面が鏡面仕上げされた金属製のドラムが好ましい。ドラムは、流延膜５２の剥離性の観点から、例えばステンレス鋼製が好ましい。支持体がドラムの場合は、吸気装置１４及び送風装置１５は、ドラムの周囲を一定距離をおいて取り巻く環形状を呈することになる。 <Other embodiments>
The optical film manufacturing apparatus 1 shown in FIGS. 1 and 2 uses an endless belt 12 as a support. Instead, the optical film manufacturing apparatus 1 uses a drum as a support. There may be. By rotating, the drum is dried while transporting the cast film 52 formed on the peripheral surface thereof. The drum is preferably a metal drum having a mirror-finished surface. The drum is preferably made of, for example, stainless steel from the viewpoint of peelability of the cast film 52. When the support is a drum, the air intake device 14 and the air blower 15 have an annular shape surrounding the drum with a certain distance.
　＜光学フィルムの製造方法＞
　以上のような構成の光学フィルムの製造装置１を用いることにより、移動する無端ベルト１２上に樹脂溶液５１を流延させて流延膜５２を形成させる流延工程を有する光学フィルムの製造方法であって、無端ベルト１２上に流延直後の流延膜５２の上方空間において吸気を行なう吸気装置１４による吸気工程と、この吸気工程に続いて、無端ベルト１２上の流延膜５２に乾燥風を送風する送風装置１５による送風工程とを有する光学フィルムの製造方法が実施され得る。 <Method for producing optical film>
By using the optical film manufacturing apparatus 1 configured as described above, an optical film manufacturing method including a casting process in which a resin solution 51 is cast on a moving endless belt 12 to form a casting film 52. Then, an intake process by the intake device 14 that performs intake in the space above the casting film 52 immediately after casting on the endless belt 12, and subsequent to this suction process, a dry wind is applied to the casting film 52 on the endless belt 12. The manufacturing method of the optical film which has the ventilation process by the air blower 15 which ventilates can be implemented.
　そして、そのような製造装置１又は製造方法によって製造された光学フィルムは、良好な平面性が維持されて、光学特性に優れるものである。 And the optical film manufactured by such a manufacturing apparatus 1 or a manufacturing method maintains a favorable flatness, and is excellent in an optical characteristic.
　＜光学フィルム＞
　前述したように、本実施形態では、代表例として、セルローストリアセテート等のセルロースエステル樹脂を含む光学フィルムが製造される。 <Optical film>
As described above, in the present embodiment, as a representative example, an optical film including a cellulose ester resin such as cellulose triacetate is manufactured.
　前述したように、例えば溶解釜を用いて、セルロースエステル樹脂等からなる熱可塑性樹脂を、良溶媒及び貧溶媒の混合溶媒に溶解し、これに可塑剤や紫外線吸収剤等の添加剤を添加して樹脂溶液（ドープ）５１を調製する。 As described above, for example, using a dissolution vessel, a thermoplastic resin composed of a cellulose ester resin or the like is dissolved in a mixed solvent of a good solvent and a poor solvent, and additives such as a plasticizer and an ultraviolet absorber are added thereto. A resin solution (dope) 51 is prepared.
　ついで、溶解釜で調整されたドープ５１を、例えば加圧型定量ギヤポンプを通して、導管によって流延ダイ１１に送液し、無限に移送する例えば回転駆動ステンレス鋼製エンドレスベルト１２よりなる支持体上の流延位置に、流延ダイ１１からドープ５１を流延する。 Next, the dope 51 adjusted by the melting pot is fed to the casting die 11 by a conduit through, for example, a pressurized metering gear pump, and is transferred infinitely, for example, on a support made of a rotationally driven stainless steel endless belt 12. The dope 51 is cast from the casting die 11 at the extending position.
　熱可塑性樹脂溶液（ドープ）として、例えばセルロースエステルを用いる場合、セルロースエステル溶液の固形分濃度は、１５～３０質量％であるのが、好ましい。セルロースエステル溶液（ドープ）の固形分濃度が、１５質量％未満であれば、支持体上で充分な乾燥ができず、剥離時にドープ膜の一部が支持体上に残り、ベルト汚染につながるため、好ましくない。また固形分濃度が３０質量％を超えると、ドープ粘度が高くなり、ドープ調整工程でフィルター詰まりが早くなったり、支持体上への流延時に圧力が高くなり、押し出せなくなるため、好ましくない。 For example, when cellulose ester is used as the thermoplastic resin solution (dope), the solid content concentration of the cellulose ester solution is preferably 15 to 30% by mass. If the solid content concentration of the cellulose ester solution (dope) is less than 15% by mass, sufficient drying cannot be performed on the support, and part of the dope film remains on the support during peeling, leading to belt contamination. It is not preferable. On the other hand, if the solid content concentration exceeds 30% by mass, the dope viscosity is increased, filter clogging is accelerated in the dope adjusting step, and pressure is increased during casting onto the support, which is not preferable.
　本実施形態の溶液流延製膜法による光学フィルムの製造方法においては、フィルム材料として、種々の樹脂を用いることができるが、中でもセルロースエステルが好ましい。 In the method for producing an optical film by the solution casting film forming method of the present embodiment, various resins can be used as the film material, and among them, cellulose ester is preferable.
　セルロースエステルは、セルロース由来の水酸基がアシル基などで置換されたセルロースエステルである。例えば、セルロースアセテート、セルローストリアセテート、セルロースアセテートプロピオネート、セルロースアセテートブチレート、セルロースアセテートプロピオネートブチレートなどのセルロースアシレートや、脂肪族ポリエステルグラフト側鎖を有するセルロースアセテートなどが挙げられる。中でも、セルロースアセテート、セルローストリアセテート、セルロースアセテートプロピオネート、脂肪族ポリエステルグラフト側鎖を有するセルロースアセテートが好ましい。本発明の効果を阻害しない範囲であれば、その他の置換基が含まれていてもよい。 Cellulose ester is a cellulose ester in which a hydroxyl group derived from cellulose is substituted with an acyl group or the like. Examples thereof include cellulose acylates such as cellulose acetate, cellulose triacetate, cellulose acetate propionate, cellulose acetate butyrate and cellulose acetate propionate butyrate, and cellulose acetate having an aliphatic polyester graft side chain. Among these, cellulose acetate, cellulose triacetate, cellulose acetate propionate, and cellulose acetate having an aliphatic polyester graft side chain are preferable. Other substituents may be included as long as the effects of the present invention are not impaired.
　セルローストリアセテートの例としては、アセチル基の置換度が２．０以上、３．０以下であることが好ましい。また、例えば、アシル基総置換度が２．４～２．８、アセチル基置換度が０．１～０．２、プロピオニル基置換度が２．４～２．６であることも好ましい。置換度をこのような範囲にすることで、良好な成形性が得られ、かつ所望の面内方向リタデーション（Ｒｏ）、及び厚み方向リタデーション（Ｒｔ）を得ることができるのである。アセチル基の置換度が、この範囲より低いと、位相差フィルムとしての耐湿熱性、特に湿熱下での寸法安定性に劣る場合があり、置換度が大きすぎると、必要なリタデーション特性が発現しなくなる場合がある。 As an example of cellulose triacetate, the substitution degree of acetyl group is preferably 2.0 or more and 3.0 or less. In addition, for example, the acyl group total substitution degree is preferably 2.4 to 2.8, the acetyl group substitution degree is 0.1 to 0.2, and the propionyl group substitution degree is preferably 2.4 to 2.6. By setting the degree of substitution in such a range, good moldability can be obtained, and desired in-plane direction retardation (Ro) and thickness direction retardation (Rt) can be obtained. If the substitution degree of the acetyl group is lower than this range, the heat resistance as a retardation film, particularly the dimensional stability under wet heat may be inferior, and if the substitution degree is too large, the necessary retardation characteristics will not be exhibited. There is a case.
　本実施形態に用いられるセルロースエステルの原料のセルロースとしては、特に限定はないが、綿花リンター、木材パルプ、ケナフなどを挙げることができる。また、それらから得られたセルロースエステルは、それぞれ任意の割合で混合使用することができる。 The cellulose used as the raw material for the cellulose ester used in the present embodiment is not particularly limited, and examples thereof include cotton linter, wood pulp, and kenaf. Moreover, the cellulose ester obtained from them can be mixed and used in arbitrary ratios, respectively.
　本実施形態において、セルロースエステルの数平均分子量（Ｍｎ）は、６００００～３０００００の範囲が、得られるフィルムの機械的強度が強く好ましい。さらに７００００～２０００００が好ましい。同様の理由により、重量平均分子量（Ｍｗ）は、１０００００～４０００００の範囲が好ましく、１５００００～３０００００の範囲がより好ましい。 In this embodiment, the number average molecular weight (Mn) of the cellulose ester is preferably in the range of 60,000 to 300,000, since the mechanical strength of the obtained film is strong. Furthermore, 70,000 to 200,000 are preferable. For the same reason, the weight average molecular weight (Mw) is preferably in the range of 100,000 to 400,000, more preferably in the range of 150,000 to 300,000.
　本実施形態において、セルロースエステルには、種々の添加剤を配合することができる。 In this embodiment, various additives can be added to the cellulose ester.
　本実施形態による光学フィルムの製造方法では、セルロースエステルと厚み方向リタデーション（Ｒｔ）を低減する添加剤とを含有するドープ組成物を用いることができる。 In the method for producing an optical film according to the present embodiment, a dope composition containing a cellulose ester and an additive for reducing the thickness direction retardation (Rt) can be used.
　本実施形態による光学フィルムの製造方法において、上記セルロース誘導体に対して良好な溶解性を有する有機溶媒を良溶媒という。 In the method for producing an optical film according to the present embodiment, an organic solvent having good solubility for the cellulose derivative is referred to as a good solvent.
　良溶媒の例としては、アセトン、メチルエチルケトン、シクロペンタノン、シクロヘキサノンなどのケトン類、テトラヒドロフラン（ＴＨＦ）、１，４－ジオキサン、１，３－ジオキソラン、１，２－ジメトキシエタンなどのエーテル類、蟻酸メチル、蟻酸エチル、酢酸メチル、酢酸エチル、酢酸アミル、γ－ブチロラクトン等のエステル類の他、メチルセロソルブ、ジメチルイミダゾリノン、ジメチルホルムアミド、ジメチルアセトアミド、アセトニトリル、ジメチルスルフォキシド、スルホラン、ニトロエタン、塩化メチレン（ジクロロメタン、メチレンクロライド）、アセト酢酸メチルなどが挙げられるが、１，３－ジオキソラン、ＴＨＦ、メチルエチルケトン、アセトン、酢酸メチル及び塩化メチレンが好ましい。 Examples of good solvents include ketones such as acetone, methyl ethyl ketone, cyclopentanone, cyclohexanone, ethers such as tetrahydrofuran (THF), 1,4-dioxane, 1,3-dioxolane, 1,2-dimethoxyethane, formic acid Esters such as methyl, ethyl formate, methyl acetate, ethyl acetate, amyl acetate, γ-butyrolactone, methyl cellosolve, dimethylimidazolinone, dimethylformamide, dimethylacetamide, acetonitrile, dimethylsulfoxide, sulfolane, nitroethane, methylene chloride (Dichloromethane, methylene chloride), methyl acetoacetate and the like, and 1,3-dioxolane, THF, methyl ethyl ketone, acetone, methyl acetate and methylene chloride are preferred.
　ドープには、上記有機溶媒の他に、１～４０質量％の炭素原子数１～４のアルコールを含有させることが好ましい。これらは、ドープを支持体に流延した後、溶媒が蒸発し始めてアルコールの比率が多くなることで、ウェブをゲル化させ、ウェブを丈夫にして、支持体から剥離することを容易にするゲル化溶媒として用いられたり、これらの割合が少ない時は非塩素系有機溶媒のセルロース誘導体の溶解を促進したりする役割もある。 The dope preferably contains 1 to 40% by mass of an alcohol having 1 to 4 carbon atoms in addition to the organic solvent. These are gels that, after casting the dope onto the support, the solvent begins to evaporate and the proportion of alcohol increases, making the web gel, making the web strong and easy to peel off from the support When used as a solvating solvent, or when the proportion of these is small, it also has a role of promoting the dissolution of a cellulose derivative of a non-chlorine organic solvent.
　炭素原子数１～４のアルコールとしては、メタノール、エタノール、ｎ－プロパノール、ｉｓｏ－プロパノール、ｎ－ブタノール、ｓｅｃ－ブタノール、ｔｅｒｔ－ブタノール、プロピレングリコールモノメチルエーテルを挙げることができる。これらのうち、ドープの安定性に優れ、沸点も比較的低く、乾燥性も良く、かつ毒性がないことなどからエタノールが好ましい。これらの有機溶媒は、単独ではセルロース誘導体に対して溶解性を有しておらず、貧溶媒という。 Examples of the alcohol having 1 to 4 carbon atoms include methanol, ethanol, n-propanol, iso-propanol, n-butanol, sec-butanol, tert-butanol, and propylene glycol monomethyl ether. Of these, ethanol is preferred because it has excellent dope stability, has a relatively low boiling point, good drying properties, and no toxicity. These organic solvents alone are not soluble in cellulose derivatives and are called poor solvents.
　このような条件を満たす好ましい高分子化合物であるセルロース誘導体を高濃度に溶解する溶媒として最も好ましい溶媒は塩化メチレン：エチルアルコールの比が９５：５～８０：２０の混合溶媒である。あるいは、酢酸メチル：エチルアルコール６０：４０～９５：５の混合溶媒も好ましく用いられる。 The most preferable solvent for dissolving a cellulose derivative, which is a preferable polymer compound satisfying such conditions, at a high concentration is a mixed solvent having a ratio of methylene chloride: ethyl alcohol of 95: 5 to 80:20. Alternatively, a mixed solvent of methyl acetate: ethyl alcohol 60:40 to 95: 5 is also preferably used.
　本実施形態におけるフィルムには、フィルムに加工性・柔軟性・防湿性を付与する可塑剤、フィルムに滑り性を付与する微粒子（マット剤）、紫外線吸収機能を付与する紫外線吸収剤、フィルムの劣化を防止する酸化防止剤等を含有させてもよい。 The film in the present embodiment includes a plasticizer that imparts processability, flexibility, and moisture resistance to the film, fine particles (matting agent) that impart slipperiness to the film, an ultraviolet absorber that imparts an ultraviolet absorbing function, and deterioration of the film. You may contain the antioxidant etc. which prevent this.
　本実施形態において使用する可塑剤としては、特に限定はないが、フィルムにヘイズを発生させたり、フィルムからブリードアウトあるいは揮発しないように、セルロース誘導体や加水分解重縮合が可能な反応性金属化合物の重縮合物と、水素結合などによって相互作用可能である官能基を有していることが好ましい。 The plasticizer used in the present embodiment is not particularly limited, but is a cellulose derivative or a reactive metal compound capable of hydrolysis polycondensation so as not to generate haze, bleed out or volatilize from the film. It preferably has a functional group capable of interacting with the polycondensate by hydrogen bonding or the like.
　このような官能基としては、水酸基、エーテル基、カルボニル基、エステル基、カルボン酸残基、アミノ基、イミノ基、アミド基、イミド基、シアノ基、ニトロ基、スルホニル基、スルホン酸残基、ホスホニル基、ホスホン酸残基等が挙げられるが、好ましくはカルボニル基、エステル基、ホスホニル基である。 Examples of such functional groups include hydroxyl groups, ether groups, carbonyl groups, ester groups, carboxylic acid residues, amino groups, imino groups, amide groups, imide groups, cyano groups, nitro groups, sulfonyl groups, sulfonic acid residues, Examples thereof include a phosphonyl group and a phosphonic acid residue, and a carbonyl group, an ester group and a phosphonyl group are preferred.
　このような可塑剤の例として、リン酸エステル系可塑剤、フタル酸エステル系可塑剤、トリメリット酸エステル系可塑剤、ピロメリット酸系可塑剤、多価アルコールエステル系可塑剤、グリコレート系可塑剤、クエン酸エステル系可塑剤、脂肪酸エステル系可塑剤、カルボン酸エステル系可塑剤、ポリエステル系可塑剤などを好ましく用いることができるが、特に好ましくは多価アルコールエステル系可塑剤、グリコレート系可塑剤、多価カルボン酸エステル系可塑剤等の非リン酸エステル系可塑剤である。 Examples of such plasticizers include phosphate ester plasticizers, phthalate ester plasticizers, trimellitic acid ester plasticizers, pyromellitic acid plasticizers, polyhydric alcohol ester plasticizers, glycolate plasticizers. Agents, citric acid ester plasticizers, fatty acid ester plasticizers, carboxylic acid ester plasticizers, polyester plasticizers, etc. can be preferably used, but polyhydric alcohol ester plasticizers, glycolate plasticizers are particularly preferred. And non-phosphate ester plasticizers such as polycarboxylic acid ester plasticizers.
　多価アルコールエステルは、２価以上の脂肪族多価アルコールとモノカルボン酸のエステルよりなり、分子内に芳香環またはシクロアルキル環を有することが好ましい。 The polyhydric alcohol ester is composed of an ester of a dihydric or higher aliphatic polyhydric alcohol and a monocarboxylic acid, and preferably has an aromatic ring or a cycloalkyl ring in the molecule.
　本実施形態に用いられる多価アルコールは、つぎの一般式（１）で表される。
一般式（１）：Ｒ１－（ＯＨ）ｎ
式中、Ｒ１はｎ価の有機基、ｎは２以上の正の整数を表わす。 The polyhydric alcohol used in this embodiment is represented by the following general formula (1).
Formula (1): R1- (OH) n
In the formula, R1 represents an n-valent organic group, and n represents a positive integer of 2 or more.
　好ましい多価アルコールの例としては、例えば以下のようなものを挙げることができるが、本発明はこれらに限定されるものではない。 Examples of preferred polyhydric alcohols include the following, but the present invention is not limited to these.
　好ましい多価アルコールの例としては、アドニトール、アラビトール、エチレングリコール、ジエチレングリコール、トリエチレングリコール、テトラエチレングリコール、１，２－プロパンジオール、１，３－プロパンジオール、ジプロピレングリコール、トリプロピレングリコール、１，２－ブタンジオール、１，３－ブタンジオール、１，４－ブタンジオール、ジブチレングリコール、１，２，４－ブタントリオール、１，５－ペンタンジオール、１，６－ヘキサンジオール、ヘキサントリオール、ガラクチトール、マンニトール、３－メチルペンタン－１，３，５－トリオール、ピナコール、ソルビトール、トリメチロールプロパン、トリメチロールエタン、キシリトール等を挙げることができる。特に、トリエチレングリコール、テトラエチレングリコール、ジプロピレングリコール、トリプロピレングリコール、ソルビトール、トリメチロールプロパン、キシリトールが好ましい。 Examples of preferred polyhydric alcohols include adonitol, arabitol, ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, 1,2-propanediol, 1,3-propanediol, dipropylene glycol, tripropylene glycol, 1, 2-butanediol, 1,3-butanediol, 1,4-butanediol, dibutylene glycol, 1,2,4-butanetriol, 1,5-pentanediol, 1,6-hexanediol, hexanetriol, gallium Examples include lactitol, mannitol, 3-methylpentane-1,3,5-triol, pinacol, sorbitol, trimethylolpropane, trimethylolethane, and xylitol. In particular, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol, sorbitol, trimethylolpropane, and xylitol are preferable.
　本実施形態の多価アルコールエステルに用いられるモノカルボン酸としては、特に制限はなく、公知の脂肪族モノカルボン酸、脂環族モノカルボン酸、芳香族モノカルボン酸等を用いることができる。脂環族モノカルボン酸、芳香族モノカルボン酸を用いると透湿性、保留性を向上させる点で好ましい。 The monocarboxylic acid used in the polyhydric alcohol ester of the present embodiment is not particularly limited, and known aliphatic monocarboxylic acid, alicyclic monocarboxylic acid, aromatic monocarboxylic acid and the like can be used. Use of an alicyclic monocarboxylic acid or aromatic monocarboxylic acid is preferred in terms of improving moisture permeability and retention.
　好ましいモノカルボン酸の例としては、以下のようなものを挙げることができるが、本発明はこれに限定されるものではない。 Examples of preferred monocarboxylic acids include the following, but the present invention is not limited thereto.
　脂肪族モノカルボン酸としては、炭素数１～３２の直鎖または側鎖を有する脂肪酸を好ましく用いることができる。炭素数は１～２０であることがさらに好ましく、１～１０であることが特に好ましい。酢酸を含有させると、セルロース誘導体との相溶性が増すため好ましく、酢酸と他のモノカルボン酸を混合して用いることも好ましい。 As the aliphatic monocarboxylic acid, a fatty acid having a straight chain or a side chain having 1 to 32 carbon atoms can be preferably used. The number of carbon atoms is more preferably 1-20, and particularly preferably 1-10. When acetic acid is contained, the compatibility with the cellulose derivative is increased, and it is also preferable to use a mixture of acetic acid and another monocarboxylic acid.
　好ましい脂肪族モノカルボン酸の例としては、酢酸、プロピオン酸、酪酸、吉草酸、カプロン酸、エナント酸、カプリル酸、ペラルゴン酸、カプリン酸、２－エチル－ヘキサンカルボン酸、ウンデシル酸、ラウリン酸、トリデシル酸、ミリスチン酸、ペンタデシル酸、パルミチン酸、ヘプタデシル酸、ステアリン酸、ノナデカン酸、アラキン酸、ベヘン酸、リグノセリン酸、セロチン酸、ヘプタコサン酸、モンタン酸、メリシン酸、ラクセル酸等の飽和脂肪酸、ウンデシレン酸、オレイン酸、ソルビン酸、リノール酸、リノレン酸、アラキドン酸等の不飽和脂肪酸等を挙げることができる。 Examples of preferred aliphatic monocarboxylic acids include acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, 2-ethyl-hexanecarboxylic acid, undecylic acid, lauric acid, Tridecylic acid, myristic acid, pentadecylic acid, palmitic acid, heptadecylic acid, stearic acid, nonadecanoic acid, arachidic acid, behenic acid, lignoceric acid, serotic acid, heptacosanoic acid, montanic acid, mellicic acid, laccellic acid, etc., undecylen Examples thereof include unsaturated fatty acids such as acid, oleic acid, sorbic acid, linoleic acid, linolenic acid, and arachidonic acid.
　好ましい脂環族モノカルボン酸の例としては、シクロペンタンカルボン酸、シクロヘキサンカルボン酸、シクロオクタンカルボン酸、またはそれらの誘導体を挙げることができる。 Examples of preferable alicyclic monocarboxylic acids include cyclopentane carboxylic acid, cyclohexane carboxylic acid, cyclooctane carboxylic acid, and derivatives thereof.
　好ましい芳香族モノカルボン酸の例としては、安息香酸、トルイル酸等の安息香酸のベンゼン環にアルキル基を導入したもの、ビフェニルカルボン酸、ナフタリンカルボン酸、テトラリンカルボン酸等のベンゼン環を２個以上有する芳香族モノカルボン酸、またはそれらの誘導体を挙げることができるが、特に安息香酸が好ましい。 Examples of preferred aromatic monocarboxylic acids include those in which an alkyl group is introduced into the benzene ring of benzoic acid such as benzoic acid and toluic acid, and two or more benzene rings such as biphenylcarboxylic acid, naphthalenecarboxylic acid, and tetralincarboxylic acid. Examples thereof include aromatic monocarboxylic acids and derivatives thereof, and benzoic acid is particularly preferable.
　多価アルコールエステルの分子量は、特に制限はないが、３００～１５００であることが好ましく、３５０～７５０であることが、さらに好ましい。分子量が大きい方が揮発し難くなるため好ましく、透湿性、セルロース誘導体との相溶性の点では、小さい方が好ましい。 The molecular weight of the polyhydric alcohol ester is not particularly limited, but is preferably 300 to 1500, and more preferably 350 to 750. A higher molecular weight is preferred because it is less likely to volatilize, and a smaller one is preferred in terms of moisture permeability and compatibility with cellulose derivatives.
　多価アルコールエステルに用いられるカルボン酸は１種類でもよいし、２種以上の混合であってもよい。また、多価アルコール中のＯＨ基は、全てエステル化してもよいし、一部をＯＨ基のままで残してもよい。 The carboxylic acid used in the polyhydric alcohol ester may be one kind or a mixture of two or more kinds. Moreover, all the OH groups in the polyhydric alcohol may be esterified, or a part of the OH groups may be left as they are.
　グリコレート系可塑剤は、特に限定されないが、分子内に芳香環またはシクロアルキル環を有するグリコレート系可塑剤を、好ましく用いることができる。好ましいグリコレート系可塑剤としては、例えばブチルフタリルブチルグリコレート、エチルフタリルエチルグリコレート、メチルフタリルエチルグリコレート等を用いることができる。 The glycolate plasticizer is not particularly limited, but a glycolate plasticizer having an aromatic ring or a cycloalkyl ring in the molecule can be preferably used. As preferred glycolate plasticizers, for example, butyl phthalyl butyl glycolate, ethyl phthalyl ethyl glycolate, methyl phthalyl ethyl glycolate and the like can be used.
　リン酸エステル系可塑剤では、トリフェニルホスフェート、トリクレジルホスフェート、クレジルジフェニルホスフェート、オクチルジフェニルホスフェート、ジフェニルビフェニルホスフェート、トリオクチルホスフェート、トリブチルホスフェート等、フタル酸エステル系可塑剤では、ジエチルフタレート、ジメトキシエチルフタレート、ジメチルフタレート、ジオクチルフタレート、ジブチルフタレート、ジ－２－エチルヘキシルフタレート、ジシクロヘキシルフタレート等を用いることができるが、本実施形態では、リン酸エステル系可塑剤を実質的に含有しないことが好ましい。 For phosphate plasticizers, triphenyl phosphate, tricresyl phosphate, cresyl diphenyl phosphate, octyl diphenyl phosphate, diphenylbiphenyl phosphate, trioctyl phosphate, tributyl phosphate, etc. For phthalate ester plasticizers, diethyl phthalate, dimethoxy Ethyl phthalate, dimethyl phthalate, dioctyl phthalate, dibutyl phthalate, di-2-ethylhexyl phthalate, dicyclohexyl phthalate, and the like can be used. In this embodiment, it is preferable that a phosphate ester plasticizer is not substantially contained.
　ここで、「実質的に含有しない」とは、リン酸エステル系可塑剤の含有量が１質量％未満、好ましくは０．１質量％であり、特に好ましいのは添加していないことである。 Here, “substantially does not contain” means that the content of the phosphoric ester plasticizer is less than 1% by mass, preferably 0.1% by mass, and particularly preferably not added.
　これらの可塑剤は、単独あるいは２種以上混合して用いることができる。 These plasticizers can be used alone or in combination of two or more.
　可塑剤の使用量は、１～２０質量％が好ましい。６～１６質量％がさらに好ましく、特に好ましくは８～１３質量％である。可塑剤の使用量が、セルロース誘導体に対して１質量％未満では、フィルムの透湿度を低減させる効果が少ないため、好ましくなく、２０質量％を越えると、フィルムから可塑剤がブリードアウトし、フィルムの物性が劣化するため、好ましくない。 The amount of plasticizer used is preferably 1 to 20% by mass. It is more preferably 6 to 16% by mass, particularly preferably 8 to 13% by mass. If the amount of the plasticizer used is less than 1% by mass relative to the cellulose derivative, the effect of reducing the moisture permeability of the film is small, so this is not preferred. If it exceeds 20% by mass, the plasticizer bleeds out from the film, and the film Since the physical properties of the material deteriorate, it is not preferable.
　本実施形態におけるセルロース誘導体には、滑り性を付与するために、マット剤等の微粒子を添加するのが好ましい。微粒子としては、無機化合物の微粒子または有機化合物の微粒子が挙げられる。 In the present embodiment, it is preferable to add fine particles such as a matting agent to the cellulose derivative in order to impart slipperiness. Examples of the fine particles include fine particles of an inorganic compound or fine particles of an organic compound.
　無機化合物の微粒子の例としては、二酸化ケイ素、二酸化チタン、酸化アルミニウム、酸化ジルコニウム、酸化錫等の微粒子が挙げられる。この中では、ケイ素原子を含有する化合物の微粒子であることが好ましく、特に二酸化ケイ素微粒子が好ましい。二酸化ケイ素微粒子としては、例えばアエロジル株式会社製のＡＥＲＯＳＩＬ　２００、２００Ｖ、３００、Ｒ９７２、Ｒ９７２Ｖ、Ｒ９７４、Ｒ２０２、Ｒ８１２，Ｒ８０５、ＯＸ５０、ＴＴ６００などが挙げられる。 Examples of inorganic compound fine particles include fine particles of silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide, tin oxide, and the like. Of these, fine particles of a compound containing a silicon atom are preferred, and fine silicon dioxide particles are particularly preferred. Examples of the silicon dioxide fine particles include Aerosil 200, 200V, 300, R972, R972V, R974, R202, R812, R805, OX50, and TT600 manufactured by Aerosil Co., Ltd.
　有機化合物の微粒子の例としては、アクリル樹脂、シリコーン樹脂、フッ素化合物樹脂、ウレタン樹脂等の微粒子が挙げられる。 Examples of organic compound fine particles include fine particles of acrylic resin, silicone resin, fluorine compound resin, urethane resin, and the like.
　微粒子の１次粒径は、特に限定されないが、最終的にフィルム中での平均粒径は、０．０５～５．０μｍ程度が好ましい。さらに好ましくは、０．１～１．０μｍである。 The primary particle size of the fine particles is not particularly limited, but the average particle size in the film is preferably about 0.05 to 5.0 μm. More preferably, it is 0.1 to 1.0 μm.
　微粒子の平均粒径は、セルロースエステルフィルムを電子顕微鏡や光学顕微鏡で観察した際に、フィルムの観察場所における、粒子の長軸方向の長さの平均値を指す。フィルム中で観察される粒子であれば、１次粒子であっても、１次粒子が凝集した２次粒子であってもよいが、通常観察される多くは２次粒子である。 The average particle diameter of the fine particles refers to the average value of the lengths of the particles in the major axis direction when the cellulose ester film is observed with an electron microscope or an optical microscope. As long as the particles are observed in the film, they may be primary particles or secondary particles in which the primary particles are aggregated, but most of the particles that are usually observed are secondary particles.
　測定方法の一例としては、１つのフィルムにつき、ランダムに１０箇所の垂直断面写真を撮影し、各断面写真について、長軸長さが、０．０５～５μｍの範囲にある１００μｍ２中の粒子個数をカウントする。このときカウントした粒子の長軸長さの平均値を求め、１０箇所の平均値を平均した値を平均粒径とする。 As an example of the measurement method, 10 vertical cross-sectional photographs are taken at random for each film, and the number of particles in 100 μm 2 whose major axis length is in the range of 0.05 to 5 μm for each cross-sectional photograph. Count. The average value of the major axis lengths of the particles counted at this time is obtained, and a value obtained by averaging the average values of 10 locations is defined as the average particle size.
　微粒子の場合は、１次粒径、溶媒に分散した後の粒径、フィルムに添加された粒径が変化する場合が多く、重要なのは、最終的にフィルム中で微粒子がセルロースエステルと複合し凝集して形成される粒径をコントロールすることである。 In the case of fine particles, the primary particle size, the particle size after being dispersed in a solvent, and the particle size added to the film often change, and what is important is that the fine particles are finally combined with the cellulose ester in the film to aggregate. And controlling the particle size formed.
　ここで、微粒子の平均粒径が、５μｍを超えた場合は、ヘイズの劣化等が見られたり、異物として巻状態での故障を発生する原因にもなる。また、微粒子の平均粒径が、０．０５μｍ未満の場合は、フィルムに滑り性を付与するのが難しくなる。 Here, if the average particle size of the fine particles exceeds 5 μm, haze deterioration or the like may be observed, or it may cause a failure in a wound state as a foreign matter. Moreover, when the average particle diameter of fine particles is less than 0.05 μm, it becomes difficult to impart slipperiness to the film.
　上記の微粒子は、セルロースエステルに対して、０．０４～１．０質量％添加して使用される。好ましくは、０．０５～０．６質量％、さらに好ましくは０．０５～０．４質量％添加して使用される。微粒子の添加量が０．０４質量％未満では、フィルム表面粗さが平滑になりすぎて、摩擦係数の上昇によりブロッキングを発生する。微粒子の添加量が１．０質量％を超えると、フィルム表面の摩擦係数が下がりすぎて、巻き取り時に巻きズレが発生したり、フィルムの透明度が低く、ヘイズが高くなるため、液晶表示装置用フィルムとしての価値を持たなくなるので、上記の範囲が必須である。 The above fine particles are used by adding 0.04 to 1.0 mass% with respect to the cellulose ester. Preferably, 0.05 to 0.6% by mass, more preferably 0.05 to 0.4% by mass is added. When the addition amount of the fine particles is less than 0.04% by mass, the film surface roughness becomes too smooth, and blocking occurs due to an increase in the friction coefficient. If the amount of fine particles added exceeds 1.0% by mass, the coefficient of friction on the film surface will be too low, causing winding misalignment during winding, and the transparency of the film will be low and haze will be high. The above range is essential because it has no value as a film.
　微粒子の分散は、微粒子と溶媒を混合した組成物を高圧分散装置で処理することが好ましい。高圧分散装置とは、微粒子と溶媒を混合した組成物を、細管中に高速通過させることで、高剪断や高圧状態など特殊な条件を作りだす装置である。 For dispersion of fine particles, it is preferable to treat a composition in which fine particles and a solvent are mixed with a high-pressure dispersion apparatus. A 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.
　高圧分散装置で処理することにより、例えば、管径１～２０００μｍの細管中で装置内部の最大圧力条件が９８０Ｎ／ｃｍ２以上であることが好ましい。さらに好ましくは、装置内部の最大圧力条件が１９６０Ｎ／ｃｍ２以上である。またその際、最高到達速度が１００ｍ／ｓｅｃ以上に達するもの、伝熱速度が１００ｋｃａｌ／ｈｒ以上に達するものが、好ましい。 It is preferable that the maximum pressure condition inside the apparatus is 980 N / cm 2 or more in a thin tube having a tube diameter of 1 to 2000 μm, for example, by processing with a high-pressure dispersion apparatus. More preferably, the maximum pressure condition inside the apparatus is 1960 N / cm 2 or more. Further, at that time, those having a maximum reaching speed of 100 m / sec or more and those having a heat transfer speed of 100 kcal / hr or more are preferable.
　上記のような高圧分散装置としては、例えばMicrofluidics Corporation社製の超高圧ホモジナイザー（商品名、マイクロフルイダイザー）あるいはナノマイザー社製ナノマイザーが挙げられ、他にもマントンゴーリン型高圧分散装置、例えばイズミフードマシナリ製ホモゲナイザーなどが挙げられる。 Examples of the high-pressure dispersing device as described above include an ultra-high pressure homogenizer (trade name, Microfluidizer) manufactured by Microfluidics Corporation, or a nanomizer manufactured by Nanomizer. Examples thereof include a homogenizer.
　本実施形態において、微粒子は、低級アルコール類を２５～１００質量％含有する溶媒中で分散した後、セルロースエステル（セルロース誘導体）を溶媒に溶解したドープと混合し、該混合液を支持体上に流延し、乾燥して製膜することを特徴とするセルロースエステルフィルムを得る。 In this embodiment, the fine particles are dispersed in a solvent containing 25 to 100% by mass of a lower alcohol, and then mixed with a dope in which a cellulose ester (cellulose derivative) is dissolved in a solvent, and the mixed solution is placed on a support. A cellulose ester film is obtained which is cast and dried to form a film.
　ここで、低級アルコールの含有比率としては、好ましくは５０～１００質量％、さらに好ましくは７５～１００質量％である。 Here, the content ratio of the lower alcohol is preferably 50 to 100% by mass, and more preferably 75 to 100% by mass.
　また、低級アルコール類の例としては、好ましくはメチルアルコール、エチルアルコール、プロピルアルコール、イソプロピルアルコール、ブチルアルコール等が挙げられる。 Also, examples of lower alcohols preferably include methyl alcohol, ethyl alcohol, propyl alcohol, isopropyl alcohol, butyl alcohol and the like.
　低級アルコール以外の溶媒としては、特に限定されないが、セルロースエステルの製膜時に用いられる溶媒を用いることが好ましい。 The solvent other than the lower alcohol is not particularly limited, but it is preferable to use a solvent used at the time of forming a cellulose ester film.
　微粒子は、溶媒中で１～３０質量％の濃度で分散される。これ以上の濃度で分散すると、粘度が急激に上昇し、好ましくない。分散液中の微粒子の濃度としては、好ましく、５～２５質量％、さらに好ましくは、１０～２０質量％である。 Fine particles are dispersed in a solvent at a concentration of 1 to 30% by mass. Dispersing at a concentration higher than this is not preferable because the viscosity increases rapidly. The concentration of the fine particles in the dispersion is preferably 5 to 25% by mass, more preferably 10 to 20% by mass.
　フィルムの紫外線吸収機能は、液晶の劣化防止の観点から、偏光板保護フィルム、位相差フィルム、光学補償フィルムなどの各種光学フィルムに付与されていることが好ましい。このような紫外線吸収機能は、紫外線を吸収する材料をセルロース誘導体中に含ませても良く、セルロース誘導体からなるフィルム上に紫外線吸収機能のある層を設けてもよい。 The ultraviolet absorbing function of the film is preferably imparted to various optical films such as a polarizing plate protective film, a retardation film, and an optical compensation film from the viewpoint of preventing deterioration of the liquid crystal. For such an ultraviolet absorbing function, a material that absorbs ultraviolet rays may be included in the cellulose derivative, and a layer having an ultraviolet absorbing function may be provided on a film made of the cellulose derivative.
　本実施形態において、使用し得る紫外線吸収剤としては、例えば、オキシベンゾフェノン系化合物、ベンゾトリアゾール系化合物、サリチル酸エステル系化合物、ベンゾフェノン系化合物、シアノアクリレート系化合物、ニッケル錯塩系化合物等を挙げることができるが、着色の少ないベンゾトリアゾール系化合物が好ましい。また、特開平１０－１８２６２１号公報、特開平８－３３７５７４号公報に記載の紫外線吸収剤、特開平６－１４８４３０号公報に記載の高分子紫外線吸収剤も好ましく用いられる。 In this embodiment, examples of the ultraviolet absorber that can be used include oxybenzophenone compounds, benzotriazole compounds, salicylic acid ester compounds, benzophenone compounds, cyanoacrylate compounds, nickel complex compounds, and the like. However, a benzotriazole-based compound with little coloring is preferable. Further, ultraviolet absorbers described in JP-A-10-182621 and JP-A-8-337574 and polymer ultraviolet absorbers described in JP-A-6-148430 are preferably used.
　紫外線吸収剤としては、偏光子や液晶の劣化防止の観点から、波長３７０ｎｍ以下の紫外線の吸収能に優れており、かつ液晶表示性の観点から、波長４００ｎｍ以上の可視光の吸収が少ないものが好ましい。 As the ultraviolet absorber, those having excellent absorption ability of ultraviolet rays having a wavelength of 370 nm or less from the viewpoint of preventing deterioration of a polarizer or liquid crystal and those having little absorption of visible light having a wavelength of 400 nm or more from the viewpoint of liquid crystal display properties. preferable.
　本実施形態において、有用な紫外線吸収剤の具体例としては、２－（２’－ヒドロキシ－５’－メチルフェニル）ベンゾトリアゾール、２－（２’－ヒドロキシ－３’，５’－ジ－ｔｅｒｔ－ブチルフェニル）ベンゾトリアゾール、２－（２’－ヒドロキシ－３’－ｔｅｒｔ－ブチル－５’－メチルフェニル）ベンゾトリアゾール、２－（２’－ヒドロキシ－３’，５’－ジ－ｔｅｒｔ－ブチルフェニル）－５－クロロベンゾトリアゾール、２－（２’－ヒドロキシ－３’－（３”，４”，５”，６”－テトラヒドロフタルイミドメチル）－５’－メチルフェニル）ベンゾトリアゾール、２，２－メチレンビス（４－（１，１，３，３－テトラメチルブチル）－６－（２Ｈ－ベンゾトリアゾール－２－イル）フェノール、２－（２’－ヒドロキシ－３’－ｔｅｒｔ－ブチル－５’－メチルフェニル）－５－クロロベンゾトリアゾール、２－（２Ｈ－ベンゾトリアゾール－２－イル）－６－（直鎖及び側鎖ドデシル）－４－メチルフェノール、オクチル－３－〔３－ｔｅｒｔ－ブチル－４－ヒドロキシ－５－（クロロ－２Ｈ－ベンゾトリアゾール－２－イル）フェニル〕プロピオネートと２－エチルヘキシル－３－〔３－ｔｅｒｔ－ブチル－４－ヒドロキシ－５－（５－クロロ－２Ｈ－ベンゾトリアゾール－２－イル）フェニル〕プロピオネートの混合物等を挙げることができるが、これらに限定されない。 In the present embodiment, specific examples of useful ultraviolet absorbers include 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-butyl) Phenyl) -5-chlorobenzotriazole, 2- (2′-hydroxy-3 ′-(3 ″, 4 ″, 5 ″, 6 ″ -tetrahydrophthalimidomethyl) -5′-methylphenyl) benzotriazole, 2,2 -Methylenebis (4- (1,1,3,3-tetramethylbutyl) -6- (2H-benzotriazol-2-yl) phenol, 2- (2'-hydride) Xy-3'-tert-butyl-5'-methylphenyl) -5-chlorobenzotriazole, 2- (2H-benzotriazol-2-yl) -6- (straight and side chain dodecyl) -4-methylphenol Octyl-3- [3-tert-butyl-4-hydroxy-5- (chloro-2H-benzotriazol-2-yl) phenyl] propionate and 2-ethylhexyl-3- [3-tert-butyl-4-hydroxy Examples include, but are not limited to, a mixture of -5- (5-chloro-2H-benzotriazol-2-yl) phenyl] propionate.
　また、紫外線吸収剤の市販品として、チヌビン（ＴＩＮＵＶＩＮ）１０９、チヌビン（ＴＩＮＵＶＩＮ）１７１、チヌビン（ＴＩＮＵＶＩＮ）３２６（いずれもチバ・スペシャリティ・ケミカルズ社製）を、好ましく使用できる。 Further, as commercially available ultraviolet absorbers, TINUVIN 109, TINUVIN 171, and TINUVIN 326 (all manufactured by Ciba Specialty Chemicals) can be preferably used.
　また、本実施形態において使用し得る紫外線吸収剤であるベンゾフェノン系化合物の具体例として、２，４－ジヒドロキシベンゾフェノン、２，２′－ジヒドロキシ－４－メトキシベンゾフェノン、２－ヒドロキシ－４－メトキシ－５－スルホベンゾフェノン、ビス（２－メトキシ－４－ヒドロキシ－５－ベンゾイルフェニルメタン）等を挙げることができるが、これらに限定されない。 In addition, specific examples of the benzophenone compounds that are UV absorbers that can be used in the present embodiment include 2,4-dihydroxybenzophenone, 2,2′-dihydroxy-4-methoxybenzophenone, and 2-hydroxy-4-methoxy-5. -Sulfobenzophenone, bis (2-methoxy-4-hydroxy-5-benzoylphenylmethane) and the like can be mentioned, but are not limited thereto.
　本実施形態において、これらの紫外線吸収剤の配合量は、セルロースエステル（セルロース誘導体）に対して、０．０１～１０質量％の範囲が好ましく、さらに０．１～５質量％が好ましい。紫外線吸収剤の使用量が少なすぎると、紫外線吸収効果が不充分の場合があり、紫外線吸収剤の多すぎると、フィルムの透明性が劣化する場合があるので、好ましくない。紫外線吸収剤は熱安定性の高いものが好ましい。 In the present embodiment, the blending amount of these ultraviolet absorbers is preferably in the range of 0.01 to 10% by mass, more preferably 0.1 to 5% by mass with respect to the cellulose ester (cellulose derivative). If the amount of the ultraviolet absorber used is too small, the ultraviolet absorbing effect may be insufficient. If the amount of the ultraviolet absorber is too large, the transparency of the film may be deteriorated. The ultraviolet absorber is preferably one having high heat stability.
　また、本実施形態の光学フィルムに用いることのできる紫外線吸収剤は、特開平６－１４８４３０号公報及び特開２００２－４７３５７号公報に記載の高分子紫外線吸収剤（または紫外線吸収性ポリマー）を好ましく用いることができる。とりわけ特開平６－１４８４３０号公報に記載の一般式（１）、あるいは一般式（２）、あるいは特開２００２－４７３５７号公報に記載の一般式（３）（６）（７）で表される高分子紫外線吸収剤が、好ましく用いられる。 Further, as the ultraviolet absorber that can be used in the optical film of the present embodiment, the polymer ultraviolet absorber (or ultraviolet absorbing polymer) described in JP-A-6-148430 and JP-A-2002-47357 is preferably used. Can be used. In particular, it is represented by the general formula (1) described in JP-A-6-148430, the general formula (2), or the general formulas (3), (6), and (7) described in JP-A-2002-47357. A polymer ultraviolet absorber is preferably used.
　本実施形態において、最終的に製造された光学フィルムとしてのセルロースエステルフィルムは、含水率としては０．１～５％が好ましく、０．３～４％がより好ましく、０．５～２％であることがさらに好ましい。 In this embodiment, the cellulose ester film as an optical film finally produced has a moisture content of preferably 0.1 to 5%, more preferably 0.3 to 4%, and more preferably 0.5 to 2%. More preferably it is.
　本発明が対象とする光学フィルムは、液晶ディスプレイ、プラズマディスプレイ、有機ＥＬディスプレイ等の各種ディスプレイ、特に液晶ディスプレイに用いられる機能フィルムのことであり、偏光板保護フィルム、位相差フィルム、反射防止フィルム、輝度向上フィルム、視野角拡大等の光学補償フィルムを含むものである。 The optical film targeted by the present invention is a functional film used for various displays such as a liquid crystal display, a plasma display, and an organic EL display, particularly a liquid crystal display. A polarizing plate protective film, a retardation film, an antireflection film, It includes an optical compensation film such as a brightness enhancement film and a viewing angle expansion.
　本実施形態に係る光学フィルムは、上記のような物性を満たしていれば、大型の液晶表示装置や屋外用途の液晶表示装置用の偏光板用保護フィルムとして特に好ましく用いることができる。 The optical film according to the present embodiment can be particularly preferably used as a protective film for a polarizing plate for a large liquid crystal display device or a liquid crystal display device for outdoor use as long as the above physical properties are satisfied.
　＜偏光板＞
　本実施形態に係る光学フィルムを偏光板用の透明保護フィルムとして用いる場合、偏光板は一般的な方法で作製することが出来る。本実施形態に係る光学フィルムの裏面側に粘着層を設け、ヨウ素溶液中に浸漬延伸して作製した偏光子の少なくとも一方の面に貼り合わせることが好ましい。 <Polarizing plate>
When using the optical film which concerns on this embodiment as a transparent protective film for polarizing plates, a polarizing plate can be produced by a general method. It is preferable that an adhesive layer is provided on the back surface side of the optical film according to the present embodiment, and is bonded to at least one surface of a polarizer produced by immersion and stretching in an iodine solution.
　もう一方の面には本実施形態に係る光学フィルムを用いても、別の偏光板用透明保護フィルムを用いてもよい。例えば、市販のセルロースエステルフィルム（例えば、コニカミノルタタック　ＫＣ８ＵＸ、ＫＣ８ＵＸ２Ｍ、ＫＣ４ＵＸ、ＫＣ５ＵＸ、ＫＣ８ＵＹ、ＫＣ４ＵＹ、ＫＣ１２ＵＲ、ＫＣ８ＵＣＲ－３、ＫＣ８ＵＣＲ－４、ＫＣ８ＵＣＲ－５、ＫＣ８ＵＥ、ＫＣ４ＵＥ、ＫＣ４ＦＲ－３、ＫＣ４ＦＲ－４、ＫＣ４ＨＲ－１、ＫＣ８ＵＹ－ＨＡ、ＫＣ８ＵＸ－ＲＨＡ、以上コニカミノルタオプト（株）製）等が好ましく用いられる。 On the other side, the optical film according to this embodiment may be used, or another transparent protective film for polarizing plate may be used. For example, a commercially available cellulose ester film (for example, Konica Minoltack KC8UX, KC8UX2M, KC4UX, KC5UX, KC8UY, KC4UY, KC12UR, KC8UCR-3, KC8UCR-4, KC8UCR-5, KC8UE, KF4UE, KF4UE, KF4UE, C4R) KC4HR-1, KC8UY-HA, KC8UX-RHA, manufactured by Konica Minolta Opto Co., Ltd.) and the like are preferably used.
　偏光板の主たる構成要素である偏光子とは、一定方向の偏波面の光だけを通す素子であり、現在知られている代表的な偏光膜は、ポリビニルアルコール系偏光フィルムで、これはポリビニルアルコール系フィルムにヨウ素を染色させたものと二色性染料を染色させたものがある。 A polarizer, which is a main component of a polarizing plate, is an element that transmits only light having a plane of polarization in a certain direction. A typical polarizing film known at present is a polyvinyl alcohol polarizing film, which is a polyvinyl alcohol. There are one in which iodine is dyed on a system film and one in which dichroic dye is dyed.
　上記粘着層に用いられる粘着剤としては、粘着層の少なくとも一部分において２５℃での貯蔵弾性率が１．０×１０４Ｐａ～１．０×１０９Ｐａの範囲である粘着剤が用いられていることが好ましく、粘着剤を塗布し、貼り合わせた後に種々の化学反応により高分子量体または架橋構造を形成する硬化型粘着剤が好適に用いられる。 As the pressure-sensitive adhesive used in the pressure-sensitive adhesive layer, a pressure-sensitive adhesive having a storage elastic modulus at 25 ° C. in the range of 1.0 × 10 4 Pa to 1.0 × 10 9 Pa in at least a part of the pressure-sensitive adhesive layer is used. It is preferable to use a curable pressure-sensitive adhesive that forms a high molecular weight body or a crosslinked structure by various chemical reactions after the pressure-sensitive adhesive is applied and bonded.
　具体例としては、例えば、ウレタン系粘着剤、エポキシ系粘着剤、水性高分子－イソシアネート系粘着剤、熱硬化型アクリル粘着剤等の硬化型粘着剤、湿気硬化ウレタン粘着剤、ポリエーテルメタクリレート型、エステル系メタクリレート型、酸化型ポリエーテルメタクリレート等の嫌気性粘着剤、シアノアクリレート系の瞬間粘着剤、アクリレートとペルオキシド系の２液型瞬間粘着剤等が挙げられる。 Specific examples include, for example, urethane adhesives, epoxy adhesives, aqueous polymer-isocyanate adhesives, curable adhesives such as thermosetting acrylic adhesives, moisture-curing urethane adhesives, polyether methacrylate types, Examples include anaerobic pressure-sensitive adhesives such as ester-based methacrylate type and oxidized polyether methacrylate, cyanoacrylate-based instantaneous pressure-sensitive adhesives, and acrylate-peroxide-based two-component instantaneous pressure-sensitive adhesives.
　上記粘着剤としては１液型であっても良いし、使用前に２液以上を混合して使用する型であっても良い。 The above-mentioned pressure-sensitive adhesive may be a one-component type or a type in which two or more components are mixed before use.
　また上記粘着剤は有機溶媒を媒体とする溶媒系であってもよいし、水を主成分とする媒体であるエマルジョン型、コロイド分散液型、水溶液型等の水系であってもよいし、無溶媒型であってもよい。上記粘着剤液の濃度は、粘着後の膜厚、塗布方法、塗布条件等により適宜決定されれば良く、通常は０．１～５０質量％である。 The pressure-sensitive adhesive may be a solvent system using an organic solvent as a medium, or an aqueous system such as an emulsion type, a colloidal dispersion type, or an aqueous solution type that is a medium containing water as a main component. It may be a solvent type. The concentration of the pressure-sensitive adhesive liquid may be appropriately determined depending on the film thickness after adhesion, the coating method, the coating conditions, and the like, and is usually 0.1 to 50% by mass.
　本実施形態に係る偏光板は、偏光子と、前記偏光子の表面上に配置された透明保護フィルムとを備え、前記透明保護フィルムが、前記光学フィルムである。前記偏光子とは、入射光を偏光に変えて射出する光学素子である。 The polarizing plate according to the present embodiment includes a polarizer and a transparent protective film disposed on the surface of the polarizer, and the transparent protective film is the optical film. The polarizer is an optical element that emits incident light by converting it into polarized light.
　前記偏光板としては、例えば、ポリビニルアルコール系フィルムをヨウ素溶液中に浸漬して延伸することによって作製される偏光子の少なくとも一方の表面に、完全ケン化型ポリビニルアルコール水溶液を用いて、前記光学フィルムを貼り合わせたものが好ましい。また、前記偏光子のもう一方の表面にも、前記光学フィルムを積層させてもよいし、別の偏光板用透明保護フィルムを積層させてもよい。あるいは、セルロースエステルフィルム以外の環状オレフィン樹脂、アクリル樹脂、ポリエステル、ポリカーボネート等の樹脂フィルムを用いてもよい。この場合は、ケン化適性が低いため、適当な接着層を介して偏光板に接着加工することが好ましい。 As the polarizing plate, for example, a completely saponified polyvinyl alcohol aqueous solution is used on at least one surface of a polarizer produced by immersing and stretching a polyvinyl alcohol film in an iodine solution. The thing which bonded together is preferable. Moreover, the said optical film may be laminated | stacked also on the other surface of the said polarizer, and another transparent protective film for polarizing plates may be laminated | stacked. Or you may use resin films, such as cyclic olefin resin other than a cellulose-ester film, an acrylic resin, polyester, a polycarbonate. In this case, since the saponification suitability is low, it is preferable to perform an adhesive process on the polarizing plate through an appropriate adhesive layer.
　前記偏光板は、上述のように、偏光子の少なくとも一方の表面側に積層する保護フィルムとして、前記光学フィルムを使用したものである。その際、前記光学フィルムが位相差フィルムとして働く場合、光学フィルムの遅相軸が偏光子の吸収軸に実質的に平行または直交するように配置されていることが好ましい。 As described above, the polarizing plate uses the optical film as a protective film laminated on at least one surface side of the polarizer. In that case, when the said optical film functions as a phase difference film, it is preferable to arrange | position so that the slow axis of an optical film may be substantially parallel or orthogonal to the absorption axis of a polarizer.
　また、前記偏光子の具体例としては、例えば、ポリビニルアルコール系偏光フィルムが挙げられる。ポリビニルアルコール系偏光フィルムは、ポリビニルアルコール系フィルムにヨウ素を染色させたものと二色性染料を染色させたものとがある。前記ポリビニルアルコール系フィルムとしては、エチレンで変性された変性ポリビニルアルコール系フィルムが好ましく用いられる。 In addition, specific examples of the polarizer include, for example, a polyvinyl alcohol polarizing film. Polyvinyl alcohol polarizing films include those obtained by dyeing iodine on polyvinyl alcohol films and those obtained by dyeing dichroic dyes. As the polyvinyl alcohol film, a modified polyvinyl alcohol film modified with ethylene is preferably used.
　前記偏光子は、例えば、以下のようにして得られる。まず、ポリビニルアルコール水溶液を用いて製膜する。得られたポリビニルアルコール系フィルムを一軸延伸させた後染色するか、染色した後一軸延伸する。そして、好ましくはホウ素化合物で耐久性処理を施す。 The polarizer is obtained as follows, for example. First, a film is formed using a polyvinyl alcohol aqueous solution. The obtained polyvinyl alcohol film is uniaxially stretched and then dyed or dyed and then uniaxially stretched. And preferably, a durability treatment is performed with a boron compound.
　前記偏光子の膜厚は、５～４０μｍであることが好ましく、５～３０μｍであることがより好ましく、５～２０μｍであることがより好ましい。 The film thickness of the polarizer is preferably 5 to 40 μm, more preferably 5 to 30 μm, and more preferably 5 to 20 μm.
　該偏光子の表面上に、セルロースエステル系樹脂フィルムを張り合わせる場合、完全ケン化ポリビニルアルコール等を主成分とする水系の接着剤によって貼り合わせることが好ましい。また、セルロースエステル系樹脂フィルム以外の樹脂フィルムの場合は、適当な粘着層を介して偏光板に接着加工することが好ましい。 When laminating a cellulose ester resin film on the surface of the polarizer, it is preferable to bond the cellulose ester resin film with an aqueous adhesive mainly composed of completely saponified polyvinyl alcohol or the like. Moreover, in the case of resin films other than a cellulose ester-type resin film, it is preferable to carry out the adhesive process to a polarizing plate through a suitable adhesion layer.
　上述のような偏光板は、透明保護フィルムとして、本実施形態に係る光学フィルムを用いることによって、この光学フィルムは、変形が充分に抑制されているので、例えば、液晶表示装置に適用した際に、コントラストの向上等の、液晶表示装置の高画質化を実現できる。また、偏光板の透明保護フィルムとして適用された光学フィルムは、湿度変化による寸法変化も抑制されているので、例えば、液晶表示装置に適用した際に、いわゆる、コーナーむらの発生も抑制できる。 The polarizing plate as described above uses the optical film according to the present embodiment as a transparent protective film, so that the deformation of the optical film is sufficiently suppressed. For example, when applied to a liquid crystal display device It is possible to realize high image quality of the liquid crystal display device, such as improvement of contrast. Moreover, since the optical film applied as a transparent protective film of a polarizing plate also suppresses dimensional changes due to changes in humidity, for example, when applied to a liquid crystal display device, so-called corner unevenness can also be suppressed.
　このように、本実施形態に係る偏光板は、偏光子と、前記偏光子を挟むように偏光子の両側に配置された２枚の透明保護フィルムとを備える偏光板であって、前記２枚の透明保護フィルムのうちの少なくとも一方が、前述の光学フィルムであることを特徴とする偏光板である。この偏光板は、透明保護フィルムの良好な平面性が維持されて、光学特性に優れるものである。 Thus, the polarizing plate according to the present embodiment is a polarizing plate including a polarizer and two transparent protective films disposed on both sides of the polarizer so as to sandwich the polarizer, and the two sheets At least one of the transparent protective films is a polarizing plate characterized in that it is the optical film described above. This polarizing plate is excellent in optical characteristics while maintaining good flatness of the transparent protective film.
　＜液晶表示装置＞
　本実施形態に係る光学フィルムを液晶偏光板用保護フィルムとして貼合した偏光板を液晶表示装置に組み込むことによって、種々の視認性に優れた液晶表示装置を作製することが出来るが、特に大型の液晶表示装置やデジタルサイネージ等の屋外用途の液晶表示装置に好ましく用いられる。本実施形態に係る偏光板は、前記粘着層等を介して液晶セルに貼合する。 <Liquid crystal display device>
By incorporating a polarizing plate in which the optical film according to this embodiment is bonded as a protective film for a liquid crystal polarizing plate into a liquid crystal display device, it is possible to produce various liquid crystal display devices with excellent visibility. It is preferably used for a liquid crystal display device for outdoor use such as a liquid crystal display device and digital signage. The polarizing plate according to the present embodiment is bonded to the liquid crystal cell via the adhesive layer or the like.
　また、色ムラ、ギラツキや波打ちムラが少なく、長時間の鑑賞でも目が疲れないという効果があった。 In addition, there was little color unevenness, glare and wavy unevenness, and the eyes were not tired even after long hours of viewing.
　本実施形態に係る液晶表示装置は、液晶セルと、前記液晶セルを挟むように配置された２枚の偏光板とを備え、前記２枚の偏光板のうち少なくとも一方が、前記偏光板である。なお、液晶セルとは、一対の電極間に液晶物質が充填されたものであり、この電極に電圧を印加することで、液晶の配向状態が変化され、透過光量が制御される。このような液晶表示装置は、本実施形態に係る偏光板を用いることによって、偏光板用の透明保護フィルムとして、変形が充分に抑制されている光学フィルムが用いられているので、コントラスト等が向上された、高画質な液晶表示装置となる。また、偏光板に、湿度変化による寸法変化が抑制された光学フィルムを透明保護フィルムとして備えたものを用いているので、いわゆる、コーナーむらの発生も抑制できる。 The liquid crystal display device according to this embodiment includes a liquid crystal cell and two polarizing plates arranged so as to sandwich the liquid crystal cell, and at least one of the two polarizing plates is the polarizing plate. . Note that the liquid crystal cell is a cell in which a liquid crystal substance is filled between a pair of electrodes, and by applying a voltage to the electrodes, the alignment state of the liquid crystal is changed and the amount of transmitted light is controlled. In such a liquid crystal display device, the use of the polarizing plate according to the present embodiment makes it possible to use an optical film whose deformation is sufficiently suppressed as a transparent protective film for the polarizing plate. Thus, a high-quality liquid crystal display device is obtained. Moreover, since what used the optical film in which the dimensional change by the humidity change was suppressed was used for the polarizing plate as a transparent protective film, what is called a corner nonuniformity can also be suppressed.
　このように、本実施形態に係る液晶表示装置は、液晶セルと、前記液晶セルを挟むように液晶セルの両側に配置された２枚の偏光板とを備える液晶表示装置であって、前記２枚の偏光板のうちの少なくとも一方が、前述の偏光板であることを特徴とする液晶表示装置である。この液晶表示装置は、光学フィルム又は偏光板の透明保護フィルムの良好な平面性が維持されて、光学特性に優れるものである。 Thus, the liquid crystal display device according to the present embodiment is a liquid crystal display device including a liquid crystal cell and two polarizing plates arranged on both sides of the liquid crystal cell so as to sandwich the liquid crystal cell. At least one of the polarizing plates is a liquid crystal display device characterized in that it is the polarizing plate described above. This liquid crystal display device is excellent in optical characteristics while maintaining good flatness of the optical film or the transparent protective film of the polarizing plate.
　本実施形態の技術的特徴をまとめると下記のようになる。 The technical features of this embodiment are summarized as follows.
　本実施形態に係る光学フィルムの製造装置１は、移動する無端ベルト１２上に樹脂溶液５１を流延させて流延膜５２を形成させる工程を行う光学フィルムの製造装置１であって、無端ベルト１２上に流延直後の流延膜５２の上方空間において吸気を行なう吸気工程を実行するための吸気装置１４と、この吸気装置１４による吸気工程に続いて、流延膜５２に乾燥風を送風する送風工程を実行するための送風装置１５とを有している。 An optical film manufacturing apparatus 1 according to this embodiment is an optical film manufacturing apparatus 1 that performs a process of casting a resin solution 51 on a moving endless belt 12 to form a cast film 52, and is an endless belt. 12, the intake device 14 for performing the intake process of performing intake in the space above the casting film 52 immediately after casting, and the air blowing process to the casting film 52 following the intake process by the intake device 14. And an air blowing device 15 for executing the air blowing process.
　また、本実施形態に係る光学フィルムの製造方法は、移動する無端ベルト１２上に樹脂溶液５１を流延させて流延膜５２を形成させる工程を有する光学フィルムの製造方法であって、無端ベルト１２上に流延直後の流延膜５２の上方空間において吸気を行なう吸気工程と、この吸気工程に続いて、流延膜５２に乾燥風を送風する送風工程とを有している。 The method for producing an optical film according to the present embodiment is a method for producing an optical film, which includes a step of casting a resin solution 51 on a moving endless belt 12 to form a cast film 52. 12 has an intake process for performing intake in the space above the casting film 52 immediately after casting, and a blowing process for blowing dry air to the casting film 52 following the intake process.
　このような構成によれば、流延直後の流延膜５２に対しては、乾燥風を当てないので、流延膜５２の乾燥ムラが抑制される。代わりに、流延直後の流延膜５２に対しては、流延膜５２の上方空間において吸気を行なうので、流延膜５２の上方空間の風の流れが弱くならず、流延膜５２から蒸発した溶媒の移動が確保されて、流延膜５２の再溶解ムラが抑制される。そして、この吸気工程の後に、流延膜５２に乾燥風を送風するので、乾燥ムラ及び再溶解ムラを抑制しつつ、流延膜５２の乾燥が促進される。しかも、吸気工程に続いて送風工程が行われるので、常に流延膜５２の上方空間を風が流れ、吸気工程から送風工程への切替時においても、流延膜５２から蒸発した溶媒の移動が確保されて、再溶解ムラが抑制される。 According to such a configuration, since the drying air is not applied to the casting film 52 immediately after casting, drying unevenness of the casting film 52 is suppressed. Instead, since the air is sucked in the space above the casting film 52 with respect to the casting film 52 immediately after casting, the flow of wind in the space above the casting film 52 does not weaken, and the casting film 52 Movement of the evaporated solvent is ensured, and uneven remelting of the casting film 52 is suppressed. Then, after this intake step, the drying air is blown to the casting film 52, so that drying of the casting film 52 is promoted while suppressing drying unevenness and remelting unevenness. In addition, since the air blowing process is performed subsequent to the air intake process, the wind always flows through the space above the casting film 52, and the solvent evaporated from the casting film 52 is moved even when switching from the air intake process to the air blowing process. It is ensured and re-dissolution unevenness is suppressed.
　前記製造装置１又は製造方法においては、吸気工程の吸気速度は、送風工程の送風速度よりも小さいことが好ましい。流延膜５２の乾燥ムラがより一層抑制されるからである。 In the manufacturing apparatus 1 or the manufacturing method, it is preferable that the intake speed of the intake process is smaller than the blow speed of the blowing process. This is because unevenness of drying of the cast film 52 is further suppressed.
　前記製造装置１又は製造方法においては、吸気工程の吸気速度は実効風速で０．１ｍ／ｓ～３ｍ／ｓ、送風工程の送風速度は実効風速で２ｍ／ｓ～３０ｍ／ｓであることが好ましい。乾燥ムラ及び再溶解ムラの抑制に加えて、流延膜５２の乾燥不足も抑制されるからである。 In the manufacturing apparatus 1 or the manufacturing method, it is preferable that the intake speed in the intake process is 0.1 m / s to 3 m / s in terms of effective wind speed, and that the air speed in the blow process is in the range of 2 m / s to 30 m / s in terms of effective wind speed. . This is because in addition to the suppression of drying unevenness and remelting unevenness, insufficient drying of the cast film 52 is also suppressed.
　前記製造装置１又は製造方法においては、吸気工程の吸気速度を吸気工程中変化させること、及び／又は、送風工程の送風速度を送風工程中変化させることが好ましい。状況に応じた流延膜５２の乾燥が実現するからである。 In the manufacturing apparatus 1 or the manufacturing method, it is preferable that the intake speed of the intake process is changed during the intake process and / or the blow speed of the blow process is changed during the blow process. This is because the casting film 52 can be dried according to the situation.
　前記製造装置１又は製造方法においては、無端ベルト１２上に流延させる前の樹脂溶液５１中の溶媒量に対する流延膜５２中の溶媒量が８５質量％～９５質量％に低下したときに、吸気工程から送風工程への切替えを行なうことが好ましい。乾燥ムラ及び乾燥不足がより一層抑制されるからである。 In the manufacturing apparatus 1 or the manufacturing method, when the amount of solvent in the casting film 52 with respect to the amount of solvent in the resin solution 51 before being cast on the endless belt 12 is reduced to 85% by mass to 95% by mass, It is preferable to switch from the intake process to the blow process. This is because drying unevenness and insufficient drying are further suppressed.
　前記製造装置１又は製造方法においては、吸気工程の吸気を行なう流延膜５２の上方空間と、送風工程の送風を行なう流延膜５２の上方空間とを仕切る遮蔽板１６を、遮蔽板１６と流延膜５２との間に所定量の間隙を残して設けることが好ましい。吸気工程の吸気と送風工程の送風とが干渉し合わないと共に、遮蔽板１６と流延膜５２との間の間隙を介して風が移動するので、吸気工程から送風工程への切替時において再溶解ムラがより一層抑制されるからである。なお、遮蔽板１６と流延膜５２との間の間隙は、状況により好ましい値が変化するが、例えば１ｍｍ～３００ｍｍである。 In the manufacturing apparatus 1 or the manufacturing method, the shielding plate 16 that partitions the upper space of the casting film 52 that performs intake in the intake process and the upper space of the casting film 52 that performs blowing in the blowing process is provided with the shielding plate 16. It is preferable to provide a predetermined amount of gap between the casting film 52 and the casting film 52. The intake air in the intake air process and the air in the air supply process do not interfere with each other, and the wind moves through the gap between the shielding plate 16 and the casting film 52. This is because uneven dissolution is further suppressed. Note that a preferable value of the gap between the shielding plate 16 and the casting film 52 varies depending on the situation, but is, for example, 1 mm to 300 mm.
　前記製造装置１又は製造方法においては、吸気工程において、流延膜５２表面の法線に沿って流延膜５２表面から流延膜５２上方へ向かう方向を基準として、この方向から、流延膜５２表面から離間する側が流延膜５２の移動方向下流側に０°～４５°傾斜する方向に吸気することが好ましい。吸気によって風が流延膜５２の移動方向下流側に流れることとなり、流延膜５２の移動により流延膜５２が受ける向かい風（伴走風）が打ち消されるので、流延膜５２が風を受けて局所的に流動することによる乾燥ムラが確実に抑制されるからである。また、下流側に４５°を超えて傾斜する方向に吸気したときは、結果的に溶媒が流延膜５２の上方空間に長く滞留する状態となり、再溶解ムラが懸念されるので好ましくない。 In the manufacturing apparatus 1 or the manufacturing method, in the intake step, the casting film is formed from this direction on the basis of the direction from the casting film 52 surface to the upper side of the casting film 52 along the normal line of the casting film 52 surface. It is preferable that air is sucked in a direction in which the side away from the surface 52 is inclined by 0 ° to 45 ° downstream of the casting film 52 in the moving direction. The intake air causes the wind to flow downstream in the movement direction of the casting film 52, and the opposite wind (accompaniment wind) received by the casting film 52 is canceled by the movement of the casting film 52, so that the casting film 52 receives the wind. This is because unevenness in drying due to local flow is reliably suppressed. In addition, when the air is sucked in the direction inclined at an angle exceeding 45 ° on the downstream side, the solvent will stay in the upper space of the casting film 52 as a result, and there is a concern about re-dissolution unevenness, which is not preferable.
　前記製造装置１又は製造方法においては、送風工程において、流延膜５２表面の法線に沿って流延膜５２上方から流延膜５２表面へ向かう方向を基準として、この方向から、流延膜５２表面に近接する側が流延膜５２の移動方向下流側に０°～８０°傾斜する方向に送風することが好ましい。送風によって風が流延膜５２の移動方向下流側に流れることとなり、流延膜５２の移動により流延膜５２が受ける向かい風（伴走風）が打ち消されるので、流延膜５２が風を受けて局所的に流動することによる乾燥ムラが確実に抑制されるからである。また、下流側に８０°を超えて傾斜する方向に送風したときは、結果的に溶媒が流延膜５２の上方空間に長く滞留する状態となり、再溶解ムラが懸念されるので好ましくない。 In the manufacturing apparatus 1 or the manufacturing method, in the air blowing process, the casting film is formed from this direction on the basis of the direction from the upper side of the casting film 52 to the surface of the casting film 52 along the normal line of the surface of the casting film 52. It is preferable that air is blown in a direction in which the side close to the surface 52 is inclined 0 ° to 80 ° downstream of the casting film 52 in the moving direction. The wind causes the wind to flow downstream in the direction of movement of the casting film 52, and the opposite wind (accompaniment wind) received by the casting film 52 is canceled by the movement of the casting film 52, so that the casting film 52 receives the wind. This is because unevenness in drying due to local flow is reliably suppressed. Moreover, when it blows in the direction which inclines over 80 degrees downstream, as a result, it will be in the state which a solvent will remain in the upper space of the casting film 52, and a remelting nonuniformity may be anxious, and is unpreferable.
　前記製造装置１又は製造方法においては、無端ベルト１２の移動速度は６０ｍ／分～１５０ｍ／分（１ｍ／ｓ～２．５ｍ／ｓ）であることが好ましい。光学フィルムの高速生産に寄与し得るからである。 In the manufacturing apparatus 1 or the manufacturing method, the moving speed of the endless belt 12 is preferably 60 m / min to 150 m / min (1 m / s to 2.5 m / s). This is because it can contribute to high-speed production of optical films.
　前記製造装置１又は製造方法においては、膜厚が１５μｍ～６０μｍの光学フィルムを製造することが好ましい。偏光板や液晶表示装置の薄膜化（薄型化）に寄与し得るからである。 In the manufacturing apparatus 1 or the manufacturing method, it is preferable to manufacture an optical film having a film thickness of 15 μm to 60 μm. This is because it can contribute to thinning (thinning) of polarizing plates and liquid crystal display devices.
　前記製造装置１又は製造方法においては、フィルムの幅手方向及び長手方向の膜厚偏差が０．２μｍ～１．５μｍの光学フィルムを製造することが好ましい。良好な平面性が確実に維持されて、光学特性により一層優れた光学フィルムが得られるからである。 In the manufacturing apparatus 1 or the manufacturing method, it is preferable to manufacture an optical film having a film thickness deviation of 0.2 μm to 1.5 μm in the width direction and the longitudinal direction of the film. This is because good flatness is surely maintained, and an optical film having better optical properties can be obtained.
　本実施形態に係る光学フィルムは、前記製造装置１又は製造方法によって製造された光学フィルムである。この光学フィルムは、良好な平面性が維持されて、光学特性に優れている。 The optical film according to the present embodiment is an optical film manufactured by the manufacturing apparatus 1 or the manufacturing method. This optical film is excellent in optical properties while maintaining good flatness.
　本実施形態に係る偏光板は、前記光学フィルムを透明保護フィルムとして少なくとも一方の面に用いた偏光板である。この偏光板は、透明保護フィルムの良好な平面性が維持されて、光学特性に優れている。 The polarizing plate according to the present embodiment is a polarizing plate using the optical film as a transparent protective film on at least one surface. This polarizing plate is excellent in optical characteristics while maintaining the good flatness of the transparent protective film.
　本実施形態に係る液晶表示装置は、前記光学フィルム又は前記偏光板を用いた液晶表示装置である。この液晶表示装置は、光学フィルム又は透明保護フィルムの良好な平面性が維持されて、光学特性に優れている。 The liquid crystal display device according to this embodiment is a liquid crystal display device using the optical film or the polarizing plate. This liquid crystal display device is excellent in optical properties while maintaining good flatness of the optical film or transparent protective film.
　以上のように、本実施形態によれば、溶液流延製膜法により光学フィルムを製造するに際し、乾燥風が流延膜５２に当たることに起因する流延膜５２の乾燥ムラと、流延膜５２の上方空間の風の流れが弱くなることに起因する流延膜５２の再溶解ムラとが抑制される。また、良好な平面性が維持されて、光学特性に優れる光学フィルム、偏光板、液晶表示装置が得られる。 As described above, according to the present embodiment, when an optical film is manufactured by the solution casting film forming method, drying unevenness of the casting film 52 caused by the drying air hitting the casting film 52, and the casting film The remelting unevenness of the casting film 52 due to the weak wind flow in the upper space of 52 is suppressed. In addition, it is possible to obtain an optical film, a polarizing plate, and a liquid crystal display device that maintain good flatness and have excellent optical characteristics.
　以下、実施例を通して、本発明をさらに詳しく説明するが、本発明はこの実施例により限定されるものではない。 Hereinafter, the present invention will be described in more detail through examples, but the present invention is not limited to these examples.
　＜光学フィルムの製造試験＞
　［ドープの調製］
　下記の素材を密閉容器に投入し、加熱し、撹拌しながら、完全に溶解、濾過し、ドープを調製した。なお、二酸化珪素微粒子（アエロジルＲ９７２Ｖ）は、エタノールに分散した後、添加した。 <Optical film production test>
[Preparation of dope]
The following materials were put into a closed container, heated, stirred and completely dissolved and filtered to prepare a dope. Silicon dioxide fine particles (Aerosil R972V) were added after being dispersed in ethanol.
　［ドープ組成］
・セルロースアセテートプロピオネート（アシル基総置換度２．７５、アセチル基置換度０．１９、プロピオニル基置換度２．５６、Ｍｗ＝２０００００）を１００質量部
・トリフェニルホスフェート（可塑剤）を８質量部
・メチレンクロライド（溶媒）を４１８質量部
・エタノール（溶媒）を２３質量部
・二酸化珪素微粒子（アエロジルＲ９７２Ｖ）（マット剤）を０．１質量部
　そして、上記のドープを用いて、以下のようにして、光学フィルム（セルロースアセテートプロピオネートフィルム）を作製した。 [Dope composition]
Cellulose acetate propionate (acyl group total substitution degree 2.75, acetyl group substitution degree 0.19, propionyl group substitution degree 2.56, Mw = 200000) 100 parts by mass Triphenyl phosphate (plasticizer) 8 Part by mass, 418 parts by mass of methylene chloride (solvent), 23 parts by mass of ethanol (solvent), 0.1 part by mass of silicon dioxide fine particles (Aerosil R972V) (matting agent), and using the above dope, Thus, an optical film (cellulose acetate propionate film) was produced.
　［試験１］
　調製したドープを、図１に示した光学フィルムの製造装置１に類似の装置を用いて、ドープ温度３４℃、支持体（無端ベルト）温度２０～２５℃、流延膜厚２８０μｍ、支持体移動速度８０ｍ／分、２ｍ幅でステンレス鋼製の無端ベルト上に均一に流延させた。 [Test 1]
Using the apparatus similar to the optical film manufacturing apparatus 1 shown in FIG. 1, the prepared dope was subjected to a dope temperature of 34 ° C., a support (endless belt) temperature of 20 to 25 ° C., a cast film thickness of 280 μm, and a support moving The film was uniformly cast on an endless belt made of stainless steel at a speed of 80 m / min and a width of 2 m.
　無端ベルト上に流延直後の流延膜の上方空間において、吸気装置を用いて、表１に示す条件（実効風速での吸気速度１ｍ／ｓ）で、吸気を行った（第１動作）。この吸気工程に続いて、送風装置を用いて、表１に示す条件（実効風速での送風速度３ｍ／ｓ）で、流延膜に乾燥風を送風する送風工程を行った（第２動作）。吸気工程（第１動作）から送風工程（第２動作）への切替えは、無端ベルト上に流延させる前のドープ中の溶媒（メチレンクロライド及びエタノール）量に対する流延膜中の溶媒量が９０質量％に低下したときに行った。吸気装置と送風装置との境界部分に設けた遮蔽板と流延膜との間の間隙は１ｍｍとした。吸気工程における吸気の方向は、下流側に４５°傾斜する方向とした。送風工程における送風の方向は、下流側に８０°傾斜する方向とした。送風工程で送風する乾燥風の温度は３０～４５℃とした。 In the space above the casting film immediately after casting on the endless belt, the intake device was used to perform intake under the conditions shown in Table 1 (intake speed 1 m / s at effective wind speed) (first operation). Subsequent to this intake step, a blower was used to blow dry air to the cast film under the conditions shown in Table 1 (blowing speed 3 m / s at the effective wind speed) using a blower (second operation). . Switching from the suction process (first operation) to the blowing process (second operation) is performed by changing the amount of solvent in the casting film to 90% of the amount of solvent (methylene chloride and ethanol) in the dope before casting on the endless belt. This was done when the mass was reduced. The gap between the shielding plate provided at the boundary between the intake device and the blower and the casting film was 1 mm. The direction of intake in the intake process was set to a direction inclined 45 ° downstream. The direction of the air blowing in the air blowing process was a direction inclined by 80 ° on the downstream side. The temperature of the drying air blown in the blowing step was 30 to 45 ° C.
　無端ベルト上で、流延膜の残留溶媒率が６０質量％になるまで溶媒を蒸発させ、剥離張力１００Ｎ／ｍで流延膜を無端ベルトから剥離した。 On the endless belt, the solvent was evaporated until the residual solvent ratio of the cast film reached 60% by mass, and the cast film was peeled from the endless belt with a peel tension of 100 N / m.
　剥離した樹脂フィルムをクリップテンターを用いて長手方向（ＭＤ方向）に１．１倍（延伸率：１０％）、幅手方向（ＴＤ方向）に１．２倍（延伸率：２０％）に延伸しながら、７０℃で、１０秒間、乾燥させた。 The peeled resin film is stretched 1.1 times (stretching rate: 10%) in the longitudinal direction (MD direction) and 1.2 times (stretching rate: 20%) in the width direction (TD direction) using a clip tenter. However, it was dried at 70 ° C. for 10 seconds.
　延伸後、１３０℃で５分間緩和を行った後、１２０℃、１４０℃の熱処理装置を複数のロールで搬送させながら乾燥を終了させ、１．５ｍ幅にスリットし、フィルム両端に幅１０ｍｍ高さ５μｍのナーリング加工を施し、初期張力２２０Ｎ／ｍ、終張力１１０Ｎ／ｍで内径１５．２４ｃｍのコアに巻取ることで、例えば、偏光板用透明保護フィルム等として用いられ得る光学フィルム（セルロースアセテートプロピオネートフィルム）のロールを得た。 After stretching, relaxation was performed at 130 ° C. for 5 minutes, and then drying was completed while conveying a heat treatment apparatus at 120 ° C. and 140 ° C. with a plurality of rolls, slitting to a width of 1.5 m, and a width of 10 mm at both ends of the film. An optical film (cellulose acetate film) that can be used as a transparent protective film for polarizing plates, for example, by winding it on a core with an initial tension of 220 N / m and a final tension of 110 N / m and an inner diameter of 15.24 cm after a knurling process of 5 μm. A roll of Pionate film) was obtained.
　製造された光学フィルムの残留溶媒率は０．０１％であり、膜厚は４０μｍ、フィルムの幅手方向及び長手方向の膜厚偏差は０．２μｍ、巻長は４０００ｍであった。 The residual solvent ratio of the manufactured optical film was 0.01%, the film thickness was 40 μm, the film thickness deviation in the width direction and the longitudinal direction of the film was 0.2 μm, and the winding length was 4000 m.
　［試験２］
　表１に示すように、第１動作を送風工程（実効風速での送風速度１ｍ／ｓ）とした他は、試験１と同様にして光学フィルムを製造した。 [Test 2]
As shown in Table 1, an optical film was produced in the same manner as in Test 1 except that the first operation was the air blowing step (the air blowing speed at the effective wind speed was 1 m / s).
　［試験３］
　表１に示すように、第１動作を行わなかった（吸気も送風も行わなかった）他は、試験１と同様にして光学フィルムを製造した。 [Test 3]
As shown in Table 1, an optical film was produced in the same manner as in Test 1 except that the first operation was not performed (intake and ventilation were not performed).
　［試験１１～１４］
　表２に示すように、吸気速度を変化させた他は、試験１と同様にして光学フィルムを製造した。 [Tests 11 to 14]
As shown in Table 2, an optical film was produced in the same manner as in Test 1 except that the intake speed was changed.
　［試験２１～２４］
　表３に示すように、送風速度を変化させた他は、試験１と同様にして光学フィルムを製造した。 [Tests 21 to 24]
As shown in Table 3, an optical film was produced in the same manner as in Test 1 except that the blowing speed was changed.
　［試験３１～３４］
　表４に示すように、吸気工程から送風工程への切替時の流延膜中の溶媒量を変化させた他は、試験１と同様にして光学フィルムを製造した。 [Tests 31 to 34]
As shown in Table 4, an optical film was produced in the same manner as in Test 1 except that the amount of solvent in the casting film was changed when switching from the intake process to the blow process.
　［試験４１、４２］
　表５に示すように、遮蔽板について条件を変化させた他は、試験１と同様にして光学フィルムを製造した。 [Tests 41 and 42]
As shown in Table 5, an optical film was produced in the same manner as in Test 1 except that the conditions for the shielding plate were changed.
　［試験５１、５２］
　表６に示すように、吸気工程における吸気方向を変化させた他は、試験１と同様にして光学フィルムを製造した。 [Tests 51 and 52]
As shown in Table 6, an optical film was manufactured in the same manner as in Test 1 except that the intake direction in the intake process was changed.
　［試験６１、６２］
　表７に示すように、送風工程における送風方向を変化させた他は、試験１と同様にして光学フィルムを製造した。 [Tests 61 and 62]
As shown in Table 7, an optical film was produced in the same manner as in Test 1 except that the blowing direction in the blowing process was changed.
　＜評価方法＞
　［再溶解ムラ］
　各試験で製造された光学フィルムを目視で観察し、無端ベルト上で局所的な再溶解が生じたことによる再溶解ムラの有無について、下記基準で評価した。結果を表１～７に示す。
○：再溶解ムラがまったく確認できない。
△：再溶解ムラが確認できる部分がある。
×：再溶解ムラが多く確認できる。 <Evaluation method>
[Remelting unevenness]
The optical film produced in each test was visually observed, and the presence or absence of remelting unevenness due to local remelting on the endless belt was evaluated according to the following criteria. The results are shown in Tables 1-7.
○: Remelting unevenness cannot be confirmed at all.
(Triangle | delta): There exists a part which can confirm remelting nonuniformity.
X: Many re-dissolution unevenness can be confirmed.
　［乾燥ムラ］
　各試験で製造された光学フィルムを目視で観察し、無端ベルト上で局所的な乾燥、収縮が生じたことによる乾燥ムラ、あるいは、無端ベルト上で局所的な流動、変形が生じたことによる乾燥ムラの有無について、下記基準で評価した。結果を表１～７に示す。
○：乾燥ムラがまったく確認できない。
△：乾燥ムラが確認できる部分がある。
×：乾燥ムラが多く確認できる。 [Drying unevenness]
Visual observation of the optical film produced in each test, drying unevenness due to local drying and shrinkage on the endless belt, or drying due to local flow and deformation on the endless belt The presence or absence of unevenness was evaluated according to the following criteria. The results are shown in Tables 1-7.
○: Drying unevenness cannot be confirmed at all.
Δ: There is a portion where drying unevenness can be confirmed.
X: Many drying irregularities can be confirmed.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000003
Figure JPOXMLDOC01-appb-T000003
Figure JPOXMLDOC01-appb-T000005
Figure JPOXMLDOC01-appb-T000005
Figure JPOXMLDOC01-appb-T000006
Figure JPOXMLDOC01-appb-T000006
Figure JPOXMLDOC01-appb-T000007
Figure JPOXMLDOC01-appb-T000007
　＜結果考察＞
　試験番号２が乾燥ムラの結果に劣ったのは、第１動作として吸気工程ではなく送風工程を行い、そのため流延直後の流延膜に乾燥風が当たったためと考えられる。試験番号３が再溶解ムラの結果に劣ったのは、第１動作として吸気工程も送風工程も行わず、そのため流延膜の上方空間の風の流れが弱くなったためと考えられる。 <Consideration of results>
The reason why the test number 2 was inferior to the result of drying unevenness is considered to be that the air blowing process, not the air intake process, was performed as the first operation, so that the casting film immediately hit the casting film. The reason why the test number 3 was inferior to the result of the remelting unevenness is considered to be that the air flow in the space above the casting film was weakened because neither the intake process nor the air blowing process was performed as the first operation.
　試験番号１１が再溶解ムラの結果に若干劣ったのは、吸気速度が過度に小さかったため、流延膜の上方空間の風の流れが若干弱くなったためと考えられる。試験番号１４が乾燥ムラの結果に若干劣ったのは、吸気速度が過度に大きかったため、流延直後の流延膜に風が若干作用したためと考えられる。 The reason why the test number 11 was slightly inferior to the result of the remelting unevenness is considered to be that the flow of wind in the space above the casting film was slightly weakened because the intake speed was excessively small. The reason why the test number 14 was slightly inferior to the result of the unevenness in drying was considered to be that the wind acted slightly on the casting film immediately after casting because the intake speed was excessively high.
　試験番号２１が流延膜の乾燥不足であったのは、送風速度が過度に小さかったためと考えられる。試験番号２４が乾燥ムラの結果に若干劣ったのは、送風速度が過度に大きかったためと考えられる。 The reason why the test number 21 was insufficient drying of the cast film is thought to be because the blowing speed was excessively low. The reason why the test number 24 was slightly inferior to the result of drying unevenness is considered that the air blowing speed was excessively large.
　試験番号３１が乾燥ムラの結果に若干劣ったのは、流延膜中の溶媒量が相対的に多い段階で送風を開始したためと考えられる。試験番号３４が流延膜の乾燥不足であったのは、流延膜中の溶媒量が相対的に少ない段階で送風を開始し、そのため吸気工程の時間が長くなり、剥離までの送風工程の時間が短くなったためと考えられる。 The reason why the test number 31 was slightly inferior to the result of drying unevenness is considered to be that the blowing was started at a stage where the amount of solvent in the cast film was relatively large. The test number 34 was insufficient drying of the casting membrane because the blowing was started at a stage where the amount of solvent in the casting membrane was relatively small. This is probably because the time has been shortened.
　試験番号４２が再溶解ムラの結果に若干劣ったのは、吸気装置が吸気を行なう流延膜の上方空間と、送風装置が送風を行なう流延膜の上方空間とを仕切る遮蔽板がなかったため、吸気工程の吸気と送風工程の送風とが干渉し合って、特に吸気工程から送風工程への切替時において、流延膜の上方空間の風の流れが若干弱くなったためと考えられる。 The reason why the test number 42 was slightly inferior to the result of the re-dissolution unevenness was that there was no shielding plate for separating the upper space of the casting film where the air intake device sucks air from the upper space of the casting film where the air blowing device blows air. This is probably because the intake air in the intake process interferes with the blow in the blowing process, and the flow of wind in the space above the casting film is slightly weakened, especially when switching from the intake process to the blowing process.
　試験番号５２が再溶解ムラの結果に若干劣ったのは、吸気工程における吸気方向を上流側としたため、吸気工程の吸気と送風工程の送風とが干渉し合って（打ち消し合って）、特に吸気工程から送風工程への切替時において、流延膜の上方空間の風の流れが若干弱くなったためと考えられる。 The reason why the test number 52 was slightly inferior to the result of the re-dissolution unevenness was that the intake direction in the intake process was on the upstream side, so the intake in the intake process and the blow in the blow process interfered with each other (cancelled each other). It is considered that the flow of the wind in the upper space of the casting film was slightly weakened when switching from the process to the blow process.
　試験番号６２が再溶解ムラの結果に若干劣ったのは、送風工程における送風方向を上流側としたため、吸気工程の吸気と送風工程の送風とが干渉し合って（打ち消し合って）、特に吸気工程から送風工程への切替時において、流延膜の上方空間の風の流れが若干弱くなったためと考えられる。 The reason why the test number 62 was slightly inferior to the result of the re-dissolution unevenness was that the air blowing direction in the air blowing process was on the upstream side, so that the air intake in the air intake process and the air in the air blowing process interfered (cancelled each other), It is considered that the flow of the wind in the upper space of the casting film was slightly weakened when switching from the process to the blow process.
　以上の試験に加えて、試験４として、第１動作（吸気）は行ったが、第２動作を行わなかった（吸気も送風も行わなかった）他は、試験１と同様にして光学フィルムを製造したところ、再溶解ムラの結果に劣ると共に、流延膜の乾燥不足であった。また、試験５として、第１動作（吸気）と第２動作（送風）との間に数秒間吸気も送風も行わなかった期間を設けた他は、試験１と同様にして光学フィルムを製造したところ、やはり、再溶解ムラの結果に劣ると共に、流延膜の乾燥不足であった。 In addition to the above test, as test 4, the first operation (intake) was performed, but the second operation was not performed (intake and ventilation were not performed). As a result of the production, it was inferior to the result of uneven dissolution, and the cast film was insufficiently dried. Further, as test 5, an optical film was manufactured in the same manner as in test 1 except that a period in which neither intake nor ventilation was performed for several seconds was provided between the first operation (intake) and the second operation (air blow). However, it was still inferior to the result of uneven remelting, and the cast film was insufficiently dried.
　この出願は、２０１１年３月３日に出願された日本国特許出願特願２０１１－０４６６４０を基礎とするものであり、その内容は、本願に含まれるものである。 This application is based on Japanese Patent Application No. 2011-046640 filed on Mar. 3, 2011, the contents of which are included in this application.
　本発明を表現するために、前述において図面を参照しながら実施形態を通して本発明を適切かつ十分に説明したが、当業者であれば前述の実施形態を変更及び／又は改良することは容易になし得ることであると認識すべきである。したがって、当業者が実施する変更形態又は改良形態が、請求の範囲に記載された請求項の権利範囲を離脱するレベルのものでない限り、当該変更形態又は当該改良形態は、当該請求項の権利範囲に包括されると解釈される。 In order to express the present invention, the present invention has been properly and fully described through the embodiments with reference to the drawings. However, those skilled in the art can easily change and / or improve the above-described embodiments. It should be recognized as gaining. Therefore, unless the modifications or improvements implemented by those skilled in the art are at a level that departs from the scope of the claims recited in the claims, the modifications or improvements are not limited to the scope of the claims. To be construed as inclusive.
　本発明は、溶液流延製膜法により光学フィルムを製造するに際し、流延膜の乾燥ムラ及び再溶解ムラを抑制できるので、溶液流延製膜法により光学フィルムを製造する技術分野において、広範な産業上の利用可能性を有する。 The present invention can suppress unevenness in drying and re-dissolution of cast films when manufacturing an optical film by the solution casting film forming method. Therefore, the present invention is widely used in the technical field of manufacturing optical films by the solution casting film forming method. Have great industrial applicability.

Claims (15)

  1. 　移動する支持体上に樹脂溶液を流延させて流延膜を形成させる工程を行う光学フィルムの製造装置において、
    　支持体上に流延直後の流延膜の上方空間において吸気を行なう吸気工程を実行するための吸気装置と、
    　この吸気装置による吸気工程に続いて、流延膜に乾燥風を送風する送風工程を実行するための送風装置とを有することを特徴とする光学フィルムの製造装置。     In an optical film manufacturing apparatus that performs a process of casting a resin solution on a moving support to form a cast film,
    An intake device for performing an intake process of performing intake on a space above the casting film immediately after casting on a support;
    An apparatus for producing an optical film, comprising: a blower for executing a blower step of blowing dry air to the cast film following the suction step by the suction device.
  2. 　移動する支持体上に樹脂溶液を流延させて流延膜を形成させる工程を有する光学フィルムの製造方法において、
    　支持体上に流延直後の流延膜の上方空間において吸気を行なう吸気工程と、
    　この吸気工程に続いて、流延膜に乾燥風を送風する送風工程とを有することを特徴とする光学フィルムの製造方法。     In the method for producing an optical film having a step of casting a resin solution on a moving support to form a cast film,
    An intake step for performing intake in the upper space of the casting film immediately after casting on the support;
    A method for producing an optical film, comprising: a blowing step for blowing dry air to the casting film following the suction step.
  3. 　吸気工程の吸気速度は、送風工程の送風速度よりも小さいことを特徴とする請求項２に記載の光学フィルムの製造方法。 The method for producing an optical film according to claim 2, wherein the intake speed of the intake process is smaller than the blow speed of the blow process.
  4. 　吸気工程の吸気速度は実効風速で０．１ｍ／ｓ～３ｍ／ｓ、送風工程の送風速度は実効風速で２ｍ／ｓ～３０ｍ／ｓであることを特徴とする請求項２又は３に記載の光学フィルムの製造方法。 The air intake speed in the air intake process is 0.1 m / s to 3 m / s in effective wind speed, and the air supply speed in the air blowing process is 2 m / s to 30 m / s in effective air speed. Manufacturing method of optical film.
  5. 　吸気工程の吸気速度を吸気工程中変化させること、及び／又は、送風工程の送風速度を送風工程中変化させることを特徴とする請求項２～４のいずれか１項に記載の光学フィルムの製造方法。 The optical film manufacturing method according to any one of claims 2 to 4, wherein the intake speed of the intake process is changed during the intake process and / or the blow speed of the blow process is changed during the blow process. Method.
  6. 　支持体上に流延させる前の樹脂溶液中の溶媒量に対する流延膜中の溶媒量が８５質量％～９５質量％に低下したときに、吸気工程から送風工程への切替えを行なうことを特徴とする請求項２～５のいずれか１項に記載の光学フィルムの製造方法。 When the amount of solvent in the cast film with respect to the amount of solvent in the resin solution before casting on the support is lowered to 85% to 95% by mass, switching from the intake process to the blowing process is performed. The method for producing an optical film according to any one of claims 2 to 5.
  7. 　吸気工程の吸気を行なう流延膜の上方空間と、送風工程の送風を行なう流延膜の上方空間とを仕切る遮蔽板を、遮蔽板と流延膜との間に所定量の間隙を残して設けることを特徴とする請求項２～６のいずれか１項に記載の光学フィルムの製造方法。 A shielding plate that partitions the upper space of the casting film that performs intake air in the intake process and the upper space of the casting film that performs air blowing in the air blowing process, leaving a predetermined amount of gap between the shielding plate and the casting film. The method for producing an optical film according to any one of claims 2 to 6, wherein the method is provided.
  8. 　吸気工程において、流延膜表面の法線に沿って流延膜表面から流延膜上方へ向かう方向を基準として、この方向から、流延膜表面から離間する側が流延膜の移動方向下流側に０°～４５°傾斜する方向に吸気することを特徴とする請求項２～７のいずれか１項に記載の光学フィルムの製造方法。 In the intake process, the direction away from the casting film surface from the casting film surface along the normal of the casting film surface as a reference is the downstream side of the casting film moving direction from this direction. The method for producing an optical film according to any one of claims 2 to 7, wherein the air is sucked in a direction inclined at 0 ° to 45 °.
  9. 　送風工程において、流延膜表面の法線に沿って流延膜上方から流延膜表面へ向かう方向を基準として、この方向から、流延膜表面に近接する側が流延膜の移動方向下流側に０°～８０°傾斜する方向に送風することを特徴とする請求項２～８のいずれか１項に記載の光学フィルムの製造方法。 In the air blowing process, with reference to the direction from the upper part of the casting film toward the casting film surface along the normal line of the casting film surface, the side closer to the casting film surface is the downstream side of the casting film movement direction from this direction. The method for producing an optical film according to any one of claims 2 to 8, wherein the air is blown in a direction inclined at 0 ° to 80 °.
  10. 　支持体の移動速度は６０ｍ／分～１５０ｍ／分であることを特徴とする請求項２～９のいずれか１項に記載の光学フィルムの製造方法。 10. The method for producing an optical film according to claim 2, wherein the moving speed of the support is from 60 m / min to 150 m / min.
  11. 　膜厚が１５μｍ～６０μｍの光学フィルムを製造することを特徴とする請求項２～１０のいずれか１項に記載の光学フィルムの製造方法。 The method for producing an optical film according to any one of claims 2 to 10, wherein an optical film having a film thickness of 15 to 60 µm is produced.
  12. 　フィルムの幅手方向及び長手方向の膜厚偏差が０．２μｍ～１．５μｍの光学フィルムを製造することを特徴とする請求項２～１１のいずれか１項に記載の光学フィルムの製造方法。 The method for producing an optical film according to any one of claims 2 to 11, wherein an optical film having a film thickness deviation of 0.2 μm to 1.5 μm in the width direction and the longitudinal direction of the film is produced.
  13. 　請求項１に記載の光学フィルムの製造装置又は請求項２～１２のいずれか１項に記載の光学フィルムの製造方法によって製造されたことを特徴とする光学フィルム。 An optical film manufactured by the optical film manufacturing apparatus according to claim 1 or the optical film manufacturing method according to any one of claims 2 to 12.
  14. 　請求項１３に記載の光学フィルムを透明保護フィルムとして少なくとも一方の面に用いたことを特徴とする偏光板。 A polarizing plate using the optical film according to claim 13 as a transparent protective film on at least one surface.
  15. 　請求項１３に記載の光学フィルム又は請求項１４に記載の偏光板を用いたことを特徴とする液晶表示装置。 A liquid crystal display device using the optical film according to claim 13 or the polarizing plate according to claim 14.
PCT/JP2012/000553 2011-03-03 2012-01-27 Optical film manufacturing device and manufacturing method, optical film, polarizing plate, and liquid crystal display device WO2012117662A1 (en)

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2003103544A (en) * 2001-09-28 2003-04-09 Konica Corp Method for manufacturing cellulose ester film
JP2006306055A (en) * 2005-03-30 2006-11-09 Fuji Photo Film Co Ltd Solution film forming method
JP2007290370A (en) * 2006-03-28 2007-11-08 Fujifilm Corp Polymer film manufacturing apparatus and polymer film manufacturing method
JP2010082993A (en) * 2008-09-30 2010-04-15 Fujifilm Corp Method of solution film-forming

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2003103544A (en) * 2001-09-28 2003-04-09 Konica Corp Method for manufacturing cellulose ester film
JP2006306055A (en) * 2005-03-30 2006-11-09 Fuji Photo Film Co Ltd Solution film forming method
JP2007290370A (en) * 2006-03-28 2007-11-08 Fujifilm Corp Polymer film manufacturing apparatus and polymer film manufacturing method
JP2010082993A (en) * 2008-09-30 2010-04-15 Fujifilm Corp Method of solution film-forming

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