JP5249057B2 - Method and apparatus for adjusting properties of polymer film, and method for producing optical film - Google Patents

Description

  The present invention relates to a property adjusting method and apparatus for a polymer film, and a method for producing an optical film.

  Polymer films (hereinafter referred to as “films”) are widely used as optical films because of their features such as excellent light transmission, flexibility, and reduction in weight. Among them, a TAC film formed from cellulose acylate, particularly cellulose triacetate (hereinafter referred to as TAC) having an average degree of acetylation of 57.5% to 62.5% is a photograph because of its toughness and flame retardancy. It is used as a support for a film of photosensitive material. Further, since the TAC film is excellent in optical isotropy, it is used for optical films such as a protective film for a polarizing plate, a retardation film, and a viewing angle widening film of a liquid crystal display device whose market is rapidly expanding.

  As a main method for producing a film, a solution casting method and a melt casting method are known. In the solution casting method, a polymer solution containing a polymer and a solvent (hereinafter referred to as a dope) is cast on a support to form a cast film, and the cast film has self-supporting properties. Thereafter, this is peeled off from the support to form a wet film, and the wet film is dried and wound up as a film. The solution casting method is superior to the melt extrusion method in which a melted polymer is extruded with an extruder to produce a film, and is excellent in optical property isotropy and film thickness uniformity, and obtains a film containing less foreign matter. Therefore, a solution casting method is adopted as a method for producing a film, particularly an optical functional film.

  Further, as a method for expressing the self-supporting property in the casting film in the solution casting method, a method of drying the casting film on the support and reducing the residual solvent amount of the casting film until it falls within a predetermined range (hereinafter referred to as the following) And a method of cooling the cast film to gel the cast film (hereinafter referred to as a cooling gelation system) (for example, Patent Document 1).

Furthermore, as a method for adjusting the optical characteristics of the film, a method of immersing the film in water or exposing the film to water vapor and stretching the film having a moisture content within a predetermined range is known (for example, patents). References 2, 3).
JP 2002-179819 A JP 2003-90915 A JP 2003-62899 A

  By the way, a wet heat durability test is performed on the liquid crystal display device to check whether or not certain characteristics and quality can be ensured under predetermined environmental conditions. Similarly, a wet heat durability test is performed on a film used in a liquid crystal display device or the like. However, it was found that when the wet heat endurance test was performed on this film, the optical characteristics of the film varied. In particular, the retardation Rth in the thickness direction largely fluctuates before and after the wet heat endurance test in a high-temperature and high-humidity environment (for example, a temperature of 60 ° C. or higher and a humidity of 90% RH). There were many phenomena that deviated greatly from the range suitable for the device.

  Patent Document 1 discloses a method in which a film obtained by a solution casting method is subjected to a humidification treatment to suppress a dimensional change of the film in a high temperature and high humidity environment. This is to remove the strain in the film by utilizing the phenomenon that the glass transition temperature Tg is lowered due to the increase in the moisture content of the film. By performing such a humidification treatment, it is considered that in-plane retardation Re and thickness direction retardation Rth, which are important optical characteristics in the retardation film, vary. However, in Patent Document 1, retardation due to the humidification treatment is considered. No mention is made of fluctuations in Re and Rth. Therefore, the method described in Patent Document 1 does not take into consideration fluctuations in retardation Re and Rth of the retardation film.

  In addition, the methods described in Patent Document 2 and Patent Document 3 relate to a method for producing a film having different Nz factors in the in-plane retardation Re in the vicinity of λ / 4, and the variation in optical characteristics before and after the wet heat durability test. It is not considered to suppress.

  SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems, and a method and an apparatus for adjusting the properties of a polymer film and an optical film capable of efficiently producing a retardation film having a low retardation Rth before and after a wet heat durability test. A method is provided.

  The property adjusting device for a polymer film of the present invention includes a casing having a film transport unit for a polymer film that has been subjected to a stretching process, a pretreatment area provided in the film transport unit, and a transport direction that is greater than the pretreatment area. More than the main processing area provided in the downstream film transport section, the main processing section for contacting the polymer film and wet gas in the main processing area, and the polymer film and wet gas in the pre-processing area And a pretreatment unit that makes contact with a pretreatment gas having low humidity.

  The film transport unit has a post-processing area downstream of the main processing area in the transport direction, and contacts the polymer film in the post-processing area and a post-processing gas having a lower humidity than the wet gas. It is preferable to provide a post-processing unit.

  The property adjustment method for a polymer film of the present invention includes a main treatment in which a stretched polymer film and a wet gas are brought into contact with each other, and a pretreatment having a humidity lower than that of the polymer film and the wet gas before the main treatment. And a pretreatment for contacting the gas.

The absolute humidity of the pretreatment gas in contact with the polymer film at the start of the pretreatment is VHas (g / m ³ ), and the absolute amount of the pretreatment gas in contact with the polymer film upon completion of the pretreatment When the humidity is VHae (g / m ³ ) and the required time from the start of the pretreatment to the completion of the pretreatment is Pa (seconds), the value of (| VHas−VHae | / Pa) is 500 ( g / m ³ seconds) or less.

After the main treatment, it is preferable to perform a post-treatment in which a post-treatment gas having a humidity lower than that of the wet gas is brought into contact with the polymer film. Further, the absolute humidity of the post-treatment gas that comes into contact with the polymer film at the start of the post-treatment is VHcs (g / m ³ ), and the post-treatment gas that comes into contact with the polymer film at the completion of the post-treatment When the absolute humidity is VHce (g / m ³ ) and the required time from the start of the post-processing to the completion of the post-processing is Pc (seconds), the value of (| VHcs−VHce | / Pc) is 1000 (G / m ³ seconds) or less is preferable.

  The polymer film is preferably produced by a solution casting method.

  The method for producing an optical film of the present invention is characterized in that an optical film is produced from the polymer film by the method for adjusting properties of the polymer film.

  According to the present invention, since the main treatment in which the stretched polymer film is brought into contact with the wet gas is performed, it is possible to produce a film having a small variation in retardation Rth before and after the wet heat durability test. And since the pretreatment gas whose humidity is lower than the wet gas and the polymer film are brought into contact before the main treatment, the generation of wrinkles on the film due to the contact with the wet gas can be suppressed. Therefore, according to the present invention, it is possible to provide an optical film capable of exhibiting stable optical characteristics without being influenced by large changes in temperature and humidity of the use environment.

(Offline stretching equipment)
As shown in FIG. 1, the offline stretching equipment 2 stretches the TAC film 3, and includes a supply chamber 4, a tenter unit 5, a wet gas contact chamber 6, a cooling chamber 7, and a winding chamber 8. Is provided. In the supply chamber 4, a long TAC film 3 is stored in a state of being wound around a winding core. The TAC film 3 is manufactured by a film manufacturing facility described later. The supply roller 9 takes out the TAC film 3 from the winding core and supplies it to the tenter unit 5.

(Tenter part)
As shown in FIG. 2, the tenter unit 5 has a film transport path for transporting the TAC film 3 in the X direction, and the TAC film 3 in the film transport path is in a direction orthogonal to the X direction (hereinafter referred to as the Y direction). The first rail 11, the second rail 12, and a pair of endless chains (hereinafter referred to as the first and second chains) guided by the rails 11 and 12. 13) and 14). A number of clips 15 are attached to the first and second chains 13 and 14 at regular intervals.

  The rails 11 and 12 are provided along both ends in the Y direction of the film conveyance path, and are arranged to face each other via the film conveyance path. A tenter inlet 26 is provided on the upstream side of the rails 11 and 12 in the X direction, and a tenter outlet 27 is provided on the downstream side of the rails 11 and 12 in the X direction. Driving sprockets 21 and 22 are provided on both sides of the tenter outlet 27 in the Y direction of the film conveyance path, and driven sprockets 23 and 24 are provided on both sides of the tenter inlet 26 in the Y direction of the film conveyance path. The first and second chains 13 and 14 are spanned between the driving sprockets 21 and 22 and the driven sprockets 23 and 24, and the first chain 13 is connected by the first rail 11 between these sprockets 21 to 24. The second chain 14 is guided by the second rail 12. When the sprockets 21 to 22 rotate, the first and second chains 13 and 14 travel along the rails 11 and 12.

  The rails 11 and 12 near the tenter inlet 26 are provided with a grip start position Pi, and the rails 11 and 12 near the tenter outlet 27 are provided with a grip release position Po. When the clip 15 passes the grip start position Pi by traveling of the first and second chains 13 and 14, the clip 15 is in a state of gripping the ear portion of the TAC film 3. When the clip 15 passes the grip release position Po, the clip 15 is in a state of releasing the grip of the ear portion of the TAC film 3. The rails 11 and 12 are arranged such that the width Wo in the Y direction of the TAC film 3 at the grip release position Po is larger than the width Wi in the Y direction of the TAC film 3 at the grip start position Pi. As the chains 13 and 14 run, the clip 15 extends the TAC film 3 in the Y direction while transporting the TAC film 3 at the grip start position Pi to the grip release position Po. The position Pk may be provided between the position Pi and the position Po in the X direction, and the rails 11 and 12 may be arranged so that the width Wk in the Y direction of the TAC film 3 at the position Pk is larger than the width Wi. . The width Wk may be greater than the width Wo or may be equal to the width Wo.

  An air conditioner (not shown) holds the condition of the atmosphere inside the tenter unit 5 so as to be constant within a predetermined range. Further, if necessary, the tenter unit 5 may be divided into a plurality of zones in the X direction, and the film heating conditions may be changed for each zone. For example, a preheating zone for preheating the TAC film 3, a heating zone for heating the TAC film 3 to the extent that it can be stretched, and a stretching zone for stretching the TAC film 3 are provided in order from the upstream side in the X direction. In addition to these, a thermal relaxation zone for stopping the stretching of the TAC film 3 and heating the TAC film 3 so as to alleviate the strain remaining in the TAC film 3 is provided downstream of the stretching zone in the X direction. May be.

  As shown in FIG. 1, an ear clip device 30 is provided between the tenter unit 5 and the wet gas contact chamber 6. The ear clip device 30 cuts off the side edge portion of the TAC film 3 in the Y direction (see FIG. 2) as slit-shaped ear dust. The cut blower 31 connected to the ear clip device 30 cuts the ear dust finely. The air sending device (not shown) sends the ear dust that has passed through the cut blower 31 to the crusher 32, and the crusher 32 cuts the ear dust further finely into chips. Since this chip is reused for dope preparation, this method is effective in terms of cost.

  The TAC film 3 sent to the wet gas contact chamber 6 is subjected to a predetermined treatment, and the TAC film 3 becomes an optical film 35. Details of the predetermined process performed in the wet gas contact chamber 6 will be described later. The optical film 35 is sent to the cooling chamber 7, cooled to a predetermined temperature, and then sent to the winding chamber 8.

  In the winding chamber 8, a winding machine 36 having a winding shaft and a press roller 37 are provided. A winding core 36a is attached to the winding shaft. The optical film 35 sent to the winding chamber 8 is wound around the winding core 36 a while being pressed by the press roller 37.

(Wet gas contact chamber)
As shown in FIGS. 1 and 3, the wet gas contact chamber 6 is provided with a pretreatment area 6a, a main treatment area 6b, and a posttreatment area 6c in order from the upstream side in the X direction. Each area 6a-6c is provided with a plurality of rollers. The plurality of rollers form a film conveyance path for conveying the TAC film 3 in the X direction. The rollers 41 provided in the processing area 6b are arranged in a staggered manner. In addition, you may partition the wet gas contact chamber 6 into three of each area 6a-6c with the partition member which is not shown in figure. Further, the post-processing area 6c may be omitted.

  Each air supply head 42a-42c is provided in the vicinity of the film conveyance path in each area 6a-6c. The main processing area 6b is provided with a plurality of air supply heads 43b.

  The air supply heads 42a to 42c are formed in a rod shape, are arranged to lie in the Y direction, and are arranged apart from each other in the X direction. In the drawing, the number of the air supply heads 42a provided in the pretreatment area 6a and the number of the air supply heads 42c provided in the posttreatment area 6c are one, but may be two or more. Similarly, the number of air supply heads 42b provided in the processing area 6b may be one, two, or four or more.

  As shown in FIG. 4, the air supply head 42 a includes a columnar air supply head main body 51, a plurality of ejection holes 52, and a flow path 56. The plurality of ejection holes 52 are provided on the peripheral surface of the air supply head main body 51. The plurality of ejection holes 52 are arranged so as to be aligned in the circumferential direction and the Y direction of the air supply head body 51. A flow path 56 is formed inside the air supply head body 51. The channel 56 communicates the wet gas supply facility with the plurality of ejection holes 52. The first wet gas 400 a sent from the wet gas supply facility to the flow path 56 is blown out from the plurality of jet holes 52. Further, the air supply heads 42b and 42c shown in FIG. 1 have the same structure as the air supply head 42a, and each wet gas 400b and 400c sent from the wet gas supply equipment is blown out from a plurality of ejection holes.

  As shown in FIG. 3, the plurality of air supply heads 43b formed in a rod shape are arranged so as to lie in the X direction and are spaced apart in the Y direction. The air supply head 43 b includes a columnar air supply head main body 60 and a plurality of ejection holes 61. The plurality of ejection holes 61 are provided on the peripheral surface of the air supply head body 60. A flow path is formed inside the air supply head body 60. The channel communicates the wet gas supply facility with the plurality of ejection holes 61. The first wet gas 400 a sent from the wet gas supply facility to the flow path is blown out from the plurality of jet holes 61.

  Returning to FIG. 1, a return duct (not shown) is provided in each of the areas 6a to 6c. The return duct is connected to the wet gas supply facility 70 via a pipe (not shown).

(Wet gas supply equipment)
The wet gas supply facility 70 includes a mixing unit, a heating unit, a control unit, and a blower unit. The mixing unit mixes a predetermined gas (for example, air) and water vapor at a predetermined mixing ratio under the control of the control unit to obtain the first wet gas 400a. The heating unit heats the first wet gas 400a under the control of the control unit. The control unit adjusts the supply amount of water vapor and air to the mixing unit and the heating amount to the first wet gas 400a. Thereby, the temperature Ta and the relative humidity Ha of the first wet gas 400a can be adjusted to be substantially constant within a predetermined range. Similarly, the wet gas supply equipment 70 creates the wet gases 400b and 400c, and the temperature Tb and relative humidity Hb of the second wet gas 400b and the temperature Tc and relative humidity Hc of the third wet gas 400c are within a predetermined range. Can be adjusted to be substantially constant. The blower supplies the humid gases 400a to 400c, the humidity and temperature of which are adjusted, to the areas 6a to 6c via the air supply heads 42a to 42c and 43b, and to the areas 6a to 6c via the return duct. A certain air is recovered as the recovery gas 300. The recovered gas 300 is preferably reused for the preparation of the wet gases 400a to 400c.

  Next, the effect | action of this invention in the offline extending | stretching equipment 2 is demonstrated. As shown in FIG. 1, the supply roller 9 supplies the TAC film 3 from the supply chamber 4 to the tenter unit 5.

  As shown in FIG. 2, an air conditioner (not shown) adjusts the temperature, humidity, gas dew point, and the like of the atmosphere in the tenter unit 5. Thereby, the temperature of the TAC film 3 which passes the tenter part 5 can be adjusted in a desired range. A drive mechanism (not shown) rotationally drives the sprockets 21 to 24, and the first and second chains 13 and 14 travel endlessly along the first and second rails 11 and 12. The clip 15 attached to the first and second chains 13 and 14 grips both side edges in the direction Y of the TAC film 3 at the grip start position Pi, and cancels gripping of both edges at the grip release position Po. To do. Thus, in the tenter unit 5, the stretching process in the direction Y is performed on the TAC film 3 between the grip start position Pi and the grip release position Po. The stretching ratio Lx {= (Wo / Wi) × 100} of the TAC film 3 in the tenter part 5 is preferably 100.5% or more and 300% or less, and more preferably 110% or more and 180% or less.

  As shown in FIG. 1, the side edges of the TAC film 3 sent from the tenter unit 5 are cut off by the edge-cutting device 30 and sent to the wet gas contact chamber 6. A predetermined process is performed in the wet gas contact chamber 6. Details of the predetermined processing will be described later. The TAC film 3 sent out from the wet gas contact chamber 6 becomes an optical film 35 and is sent to the cooling chamber 7. The optical film 35 is cooled to approximately room temperature in the cooling chamber 7. The cooled optical film 35 is sent to the winding chamber 8 and is wound around the core 36 a of the winder 36 while being pressed by the press roller 37.

  The wet gas supply equipment 70 adjusts the temperatures Ta to Tc, the relative humidity Ha to Hc, and the like of the first wet gas 400a to the third wet gas 400c. The relative humidity Ha, Hc of the first wet gas 400a and the third wet gas 400c is adjusted to be lower than the relative humidity Hb of the second wet gas 400b. The wet gas supply equipment 70 supplies the first wet gas 400a to the pretreatment area 6a via the air supply head 42a, and supplies the second wet gas 400b to the main process area 6b via the air supply head 42b. The third wet gas 400c is supplied to the post-processing area 6c through the air supply head 42c. Thereby, in each area 6a-6c, each wet gas 400a-400c adjusted to the predetermined condition is filled.

  The TAC film 3 sent to the wet gas contact chamber 6 passes through the areas 6a to 6c by a plurality of rollers 41 and the like. Thus, in the pretreatment area 6a, the pretreatment in which the TAC film 3 and the first wet gas 400a are in contact is performed, and in the main treatment area 6b, the main process in which the TAC film 3 and the second wet gas 400b are in contact with each other. In the post-processing area 6c, post-processing in which the TAC film 3 and the third wet gas 400c come into contact with each other is performed.

  By this treatment, the TAC film 3 absorbs water molecules, the glass transition temperature Tg is lowered, and thermal energy of a certain level or more is obtained, so that the diffusion of water molecules in the TAC film 3 is promoted. As a result of promoting the diffusion of water molecules in the TAC film 3, the higher order structure of the polymer molecules is likely to transition to a more stable structure. As a result, the structure of the polymer molecules is stabilized as compared to the process of simply heating the dried TAC film 3. Can be performed in a short time.

Therefore, according to the present invention, it is possible to manufacture the TAC film 3 having a small variation amount ΔRth _WET of the thickness direction retardation Rth before and after the wet heat durability test.

  In addition, when the main treatment is performed in which the second wet gas 400b is brought into contact with the stretched TAC film 3, the TAC film 3 rapidly expands due to the absorption of water molecules. As a result, the optical film 35 is wrinkled. Therefore, a pretreatment is performed in which the first wet gas 400a having a lower humidity than the second wet gas 400b is brought into contact with the TAC film 3 before this treatment is performed. Thereby, the rapid expansion | swelling of the TAC film 3 resulting from absorption of a water molecule can be suppressed. Therefore, according to the present invention, the generation of wrinkles in the film due to the absorption of water molecules can be suppressed.

  Details of each process will be described below.

(Preprocessing)
The temperature Tfa of the TAC film 3 in the pretreatment is preferably 100 ° C. or higher and 150 ° C. or lower, and more preferably 104 ° C. or higher and 140 ° C. or lower. If the temperature Tfa is less than 100 ° C., condensation may occur on the surface of the TAC film 3 or the wall surface of the pretreatment area 6a, which is not preferable. On the other hand, when Tfa exceeds 150 ° C., curling of the TAC film 3 becomes remarkable, which is not preferable. Therefore, the temperature Ta of the first wet gas 400a may be appropriately adjusted so that the temperature Tfa is in the above range. For example, the temperature Ta of the first wet gas 400a is preferably 70 ° C. or higher and 200 ° C. or lower, and more preferably 90 ° C. or higher and 160 ° C. or lower.

  The range of the relative humidity Ha of the first moist gas 400a is not particularly limited, but is preferably as high as possible from the viewpoint of production efficiency as long as the effect of the present invention is exhibited. For example, the relative humidity Ha is preferably 2% RH or more and 100% RH or less, and more preferably 5% RH or more and 100% RH or less.

  The range of the pretreatment time Pa is not particularly limited, but is preferably as short as possible from the viewpoint of production efficiency as long as the effect of the present invention is exhibited. For example, the upper limit of the processing time Pa is preferably 10 minutes or less, and more preferably 5 minutes or less. On the other hand, the lower limit of the processing time Pa is preferably, for example, 1 second or longer.

(This processing)
The lower limit of the temperature Tfb of the TAC film 3 in this treatment is preferably 100 ° C. or higher, more preferably 102 ° C. or higher, and particularly preferably 104 ° C. or higher. Further, the upper limit of the temperature Tfb is preferably 150 ° C. or less, more preferably 140 ° C. or less, and particularly preferably 120 ° C. or less. If the temperature Tfb is less than 100 ° C., it is not preferable because the time required for the main treatment required to reduce the amount of change in optical characteristics before and after the wet heat durability test is increased. When the temperature Tfb exceeds 150 ° C., curling of the TAC film 3 becomes remarkable, which is not preferable. Therefore, the temperature Tb of the second wet gas 400b may be appropriately adjusted so that the temperature Tfb is in the above range. For example, the temperature Tb of the second wet gas 400b is preferably 70 ° C. or higher and 200 ° C. or lower, more preferably 90 ° C. or higher and 160 ° C. or lower, and most preferably 95 ° C. or higher and 140 ° C. or lower.

The relative humidity Hb of the second wet gas 400b is preferably 20% RH or more and 100% RH or less, more preferably 40% RH or more and 100% RH or less, and 70% RH or more and 100% RH or less. It is particularly preferred. When the relative humidity Hb is less than 20% RH, the effect of suppressing ΔRth _WET is small, which is not preferable.

  Moreover, the range of the processing time Pb of this processing is not particularly limited, but is preferably as short as possible from the viewpoint of production efficiency as long as the effect of the present invention is exhibited. The upper limit of the processing time Pb is, for example, preferably 60 minutes or less, and more preferably 10 minutes or less. On the other hand, the lower limit of the processing time Pb is, for example, preferably 5 seconds or more, more preferably 10 seconds or more, and particularly preferably 30 seconds or more.

(Post-processing)
The temperature Tfc of the TAC film 3 in the post-treatment is preferably 100 ° C. or higher and 150 ° C. or lower, and more preferably 104 ° C. or higher and 140 ° C. or lower. If the temperature Tfc is less than 100 ° C., dew condensation may occur on the surface of the TAC film 3 or the wall surface of the post-processing area 6c. On the other hand, when Tfc exceeds 150 ° C., curling of the TAC film 3 becomes remarkable, which is not preferable. Therefore, the temperature Tc of the third wet gas 400c may be adjusted as appropriate so that the temperature Tfc falls within the above range. For example, the temperature Tc of the third wet gas 400c is preferably 70 ° C. or higher and 200 ° C. or lower, and more preferably 90 ° C. or higher and 160 ° C. or lower.

  The range of the relative humidity Hc of the third moist gas 400c is not particularly limited, but is preferably as high as possible from the viewpoint of production efficiency as long as it is within the range in which the effect of the present invention is exhibited. For example, the relative humidity Hc is preferably 2% RH or more and 100% RH or less, and more preferably 5% RH or more and 100% RH or less.

  The range of the post-treatment processing time Pc is not particularly limited, but is preferably as short as possible from the viewpoint of production efficiency as long as the effect of the present invention is exhibited. For example, the upper limit of the treatment time Pc is preferably 10 minutes or less, and more preferably 5 minutes or less. On the other hand, the lower limit of the processing time Pc is preferably 1 second or longer, for example.

As shown in FIG. 3, the absolute humidity of the atmosphere at the position Pas where the preprocessing starts, that is, the position Pas at the upstream end in the X direction of the preprocessing area 6a is VHas (g / m ³ ). The absolute humidity of the atmosphere at the position, that is, the position Pae at the downstream end in the X direction of the pretreatment area 6a is VHae (g / m ³ ), and the time required for the TAC film 3 at the position Pas to reach the position Pae is Pa (Seconds), the value of (| VHas−VHae | / Pa) is preferably 500 (g / m ³ seconds) or less, and more preferably 300 (g / m ³ seconds) or less. preferable. Thereby, generation | occurrence | production of wrinkles in the TAC film 3 etc. can be suppressed reliably.

Further, the absolute humidity of the atmosphere at the position where the post-processing starts, that is, the position Pcs at the upstream end of the post-processing area 6c in the X direction is VHcs (g / m ³ ), The absolute humidity of the atmosphere at the position Pce at the downstream end of the area 6c in the X direction is VHce (g / m ³ ), and the time required for the TAC film 3 at the position Pcs to reach the position Pce is Pc (seconds). Sometimes, the value of (| VHcs−VHce | / Pc) is preferably 1000 (g / m ³ seconds) or less, and more preferably 700 (g / m ³ seconds) or less. Thereby, generation | occurrence | production of wrinkles in the TAC film 3 etc. can be suppressed reliably.

  The absolute humidity at each position may be the absolute humidity measured at the center in the Y direction in the section where each process is performed, or may be the average value of the absolute humidity measured at a plurality of locations. . Absolute humidity can be measured with a known hygrometer.

  The values of (| VHas−VHae | / Pa) and (| VHcs−VHce | / Pc) are the number of the air supply heads 42a and 42c provided in the respective areas 6a and 6c, the distance from the film conveyance path, and the ejection holes 52˜ It can be adjusted by the size of 54, the number of formations, and the like.

  In the said embodiment, although the TAC film 3 was allowed to pass through each area 6a-6c where each wet gas 400a-400c is filled, this invention is not limited to this, and each wet gas 400a-400c in each area 6a-6c. May be applied to the TAC film 3.

  In the above embodiment, one preprocessing area 6a is provided on the upstream side in the X direction of the main processing area 6b. However, the present invention is not limited to this, and a plurality of preprocessing areas 6a are provided on the upstream side in the X direction of the main processing area 6b. May be arranged. Similarly, a plurality of post-processing areas 6c may be arranged on the downstream side in the X direction of the main processing area 6b. This makes it easy to reduce the values of (| VHas−VHae | / Pa) and (| VHcs−VHce | / Pc), and thus it is possible to reliably suppress the occurrence of wrinkles in the TAC film 3. .

  In the above embodiment, the main processing is performed in the main processing area 6b. However, the present invention is not limited to this, and the main processing may be performed on the TAC film 3 between the tenter unit 5 and the winding chamber 8. Further, the preprocessing, the main processing, and the postprocessing may be performed continuously, or another processing may be performed between the preprocessing and the main processing, or between the main processing and the postprocessing. For example, when this processing is performed in the tenter unit 5, this processing may be performed simultaneously with the stretching process or as a thermal relaxation process after the stretching process. The pretreatment may be performed before the main treatment, and may be performed simultaneously with the stretching treatment or the thermal relaxation treatment, before the stretching treatment or the thermal relaxation treatment, or after the stretching treatment or the thermal relaxation treatment. Similarly, the post-treatment may be performed after the main treatment, at the same time as the stretching treatment or the thermal relaxation treatment, before the stretching treatment or the thermal relaxation treatment, or after the stretching treatment or the thermal relaxation treatment.

  In the said embodiment, each process was performed using the wet gas which consists of water vapor | steam and predetermined gas, However, This invention is not restricted to this, You may use water vapor | steam instead of a wet gas. In this case, in order to adjust the conditions of each process, the temperature and the amount of water vapor ejected from the air supply head 66 may be adjusted.

  In the stretching process of the above embodiment, the TAC film 3 is stretched in the Y direction. However, the present invention is not limited to this, and the TAC film 3 may be stretched in the X direction, and the TAC film 3 may be stretched in the X direction and the Y direction. It may be stretched. In addition, the stretching means in the present invention is not limited to the tenter unit 5, and a known stretching means that can apply a predetermined tension to the TAC film 3 may be used.

  The TAC film 3 subjected to this treatment is preferably sufficiently dried, that is, a solvent in which almost no solvent remains and the fluidity of polymer molecules has almost disappeared. Is preferably 5% by weight or less, more preferably 2% by weight or less, and particularly preferably 0.3% by weight or less. Here, the dry solvent-based residual solvent amount indicates the amount of solvent remaining in the wet film or the TAC film 3. The amount of residual solvent is {(xy) / y} × where x is the weight of the sample film at the time of collection, and y is the weight after drying the sample film. 100.

  The width of the TAC film 3 is preferably 600 mm or more, more preferably 1400 mm or more and 2500 mm or less, and the effect of the present invention is exhibited even when the width is larger than 2500 mm. Further, the thickness of the TAC film 3 is preferably 20 μm or more and 200 μm or less, and more preferably 40 μm or more and 100 μm or less.

  As the TAC film 3, it is preferable to use a film manufactured by a solution casting method, and it is particularly preferable to use a film manufactured by a cooling gelation method. Hereinafter, an outline of the cooling gelation method will be described. In addition, the same code | symbol is attached | subjected to the same member as the said embodiment, and the detailed description is abbreviate | omitted.

  As shown in FIG. 5, the film manufacturing facility 80 performs a cooling gelation type solution film forming method. The temperature of the casting dope 81 containing the polymer and the solvent is maintained to be substantially constant within a range of 30 ° C. or more and 40 ° C. or less. Under the control of a control unit (not shown), the casting drum 82 rotates around the shaft 82a. By this rotation, the peripheral surface 82b travels in the traveling direction Z1 at a predetermined speed (50 m / min or more and 200 m / min or less). Moreover, the temperature of the peripheral surface 82b is kept substantially constant within a range of −10 ° C. or more and 10 ° C. or less by the heat transfer medium circulation device 83.

  The casting die 84 discharges the casting dope 81 to the peripheral surface 82b. The decompression chamber 85 decompresses the downstream side in the direction Z1 of the bead formed by the discharged casting dope 81 to stabilize the bead. A cast film 86 is formed on the peripheral surface 82b by the cast dope 81 thus discharged. The casting dope 81 forming the casting film 86 is gelled by cooling on the peripheral surface 82b. As a result of the gelation of the casting dope 81, the casting film 86 exhibits self-supporting properties. In the present specification, gelation means that the fluidity of the casting dope 81 is lost while the solvent contained in the casting dope 81 is retained in the molecular chain of the polymer. As a result, the fluidity of the casting dope 81 is lost. It means being in a state. After the casting film 86 has a self-supporting property, it is peeled off from the peripheral surface 82 b while being supported by the peeling roller 89 as a wet film 88. The residual solvent amount of the cast film 86 at the time of peeling is preferably 250% by weight or more and 280% by weight or less.

  The wet film 88 in which the gelled state is maintained is sequentially sent to the crossover unit 90, the pin tenter 91, and the tenter unit 5. In the transfer part 90, the pin tenter 91, and the tenter part 5, predetermined dry air is applied to the wet film 88 to evaporate the solvent contained in the wet film 88. The draw tension (= V2 / V1) in the transition part 90 is preferably set to 1.00 or more and 1.05 or less. Here, V1 is the peripheral speed of the first transport roller, and V2 is the peripheral speed of the second transport roller provided on the downstream side of the first transport roller.

  The pin tenter 91 and the tenter unit 5 perform a stretching process for stretching the wet film 88 in a predetermined direction while evaporating the solvent. The residual solvent amount of the wet film 88 introduced into the pin tenter 91 is preferably 200% by weight or more and 250% by weight or less. The residual solvent amount of the wet film 88 introduced into the tenter unit 5 is preferably 30% by weight or more and 200% by weight or less.

  In the drying chamber 97, predetermined dry air is applied to the wet film 88 to evaporate the solvent contained in the wet film 88. The temperature of the wet film 88 in the drying chamber 97 is preferably 140 ° C. or higher and 180 ° C. or lower.

  The wet film 88 sufficiently dried in the drying chamber 97 becomes the TAC film 3 and is cooled in the cooling chamber 7 until a predetermined temperature is reached. In addition, the forced neutralization device 98 neutralizes the voltage so that the charged voltage of the TAC film 3 falls within a predetermined range (for example, −3 kV to +3 kV). The knurling roller 99 imparts knurling to both edges of the TAC film 3 by embossing. Thereafter, the TAC film 3 is sent to the winding chamber 8 and is wound around the winding core 36 a of the winding machine 36 while being pressed by the press roller 37.

  In the film manufacturing facility 80, the tenter unit 5 is provided between the pin tenter 91 and the drying chamber 97, but the present invention is not limited to this, and may be provided between the drying chamber 97 and the cooling chamber 7.

  In the above embodiment, in the off-line stretching equipment 2 (see FIG. 1), the TAC film 3 manufactured by the solution casting method is stretched and then the main processing is performed. However, the present invention is not limited to this. . When the TAC film 3 wound around the winding core has been subjected to stretching treatment in the solution casting method, the TAC film 3 taken out from the winding core may be subjected to this treatment as it is without being subjected to stretching treatment. Good. In this case, the tenter unit 5 in the off-line stretching facility 2 may be omitted.

  In the said embodiment, although the casting drum 82 was used as a support body in the film manufacturing equipment 80, this invention is not limited to this, You may use the endless band which drive | works. Alternatively, the casting film 86 may be allowed to exhibit self-supporting properties by bringing dry air into contact with the casting film 86 and evaporating the solvent from the casting film 86.

  The present invention provides simultaneous lamination co-casting in which two or more types of dopes are simultaneously co-cast and laminated when casting dopes, or sequential lamination co-production in which a plurality of dopes are sequentially co-cast and laminated. Casting can be performed. In addition, you may combine both casting. When simultaneous lamination and co-casting is performed, a casting die to which a feed block is attached may be used, or a multi-pocket casting die may be used. However, it is preferable that at least one of the thickness of the layer on the air surface side and the thickness of the layer on the support side is 0.5 to 30% of the thickness of the entire film of the film composed of multiple layers by co-casting. . In addition, when performing simultaneous lamination and co-casting, it is preferable that the high-viscosity dope is enveloped by the low-viscosity dope when the dope is cast from the die slit to the support, and is formed from the die slit to the support. Of the casting beads, the dope in contact with the outside world preferably has a higher alcohol composition ratio than the inner dope.

(Heat treatment)
It is preferable that the TAC film 3 that has undergone this treatment is subjected to heat treatment that applies dry air to bring the temperature of the TAC film 3 within a predetermined range. The heat treatment may be performed between the main process and the post-process, or may be performed after the post-process. By this heat treatment, it is possible to produce a TAC film 3 having a small amount of variation of each retardation and a dimensional change amount in the X and Y directions before and after the wet heat durability test. Here, the dry heat durability test refers to a durability test performed under conditions of high temperature and low humidity (for example, a temperature of 80 ° C. or higher and a humidity of 5% RH or lower).

  The lower limit of the temperature Tf2 of the TAC film 3 in the heat treatment is preferably 110 ° C. or higher, and more preferably 120 ° C. or higher. Moreover, it is preferable that the upper limit of temperature Tf2 is 160 degrees C or less, and it is more preferable that it is 150 degrees C or less. Therefore, it is preferable that the temperature of the dry air be in a range equivalent to the temperature Tf2. When the temperature Tf2 is less than 110 ° C. or the temperature Tf2 exceeds 160 ° C., the fluctuation amount of each retardation before and after the wet heat durability test and the dry heat durability test, and the dimensional change amount in the X direction and the Y direction are suppressed. It is not preferable because it cannot be done. Further, the temperature Tf2 is preferably higher than the temperature Tfa.

  The relative humidity H2 of the dry air is preferably 20% RH or less, and more preferably 10% RH or less. When the relative humidity H2 of the dry air exceeds 20% RH, the moisture content of the film is increased, and the roll shape of the roll is deformed with time.

  The upper limit of the heat treatment time P2 is preferably 5 minutes or less, and more preferably 4 minutes or less. On the other hand, the lower limit of the processing time P2 is preferably 1 minute or longer. When the treatment time P2 exceeds 5 minutes or less than 1 minute, the variation amount of each retardation before and after the wet heat durability test and the dry heat durability test, and the dimensional change amount in the X direction and the Y direction cannot be suppressed. Therefore, it is not preferable.

  The heat treatment can be performed in a heat treatment chamber having the same structure as that of the crossover 90 or the drying chamber 97 (see FIG. 5). It is preferable to provide a heat treatment chamber on the downstream side of the facility where the main treatment is performed. The heat treatment chamber may be provided on either the upstream side or the downstream side of the cooling chamber, but is preferably provided on the upstream side.

(Condensation prevention treatment)
In order to suppress dew condensation in the TAC film 3 of the present treatment, a dew condensation prevention treatment is performed by applying dry air to the TAC film 3 before the present treatment to bring the temperature of the TAC film 3 of the above embodiment within a predetermined range. Preferably it is done. The dew condensation prevention treatment may be performed before the pretreatment or may be performed between the main treatment and the pretreatment.

  The range of the temperature Tf0 of the TAC film 3 at the completion of the dew condensation prevention treatment is preferably set to a temperature higher by ΔT0 than the dew points of the wet gases 400a to 400c. ΔT0 is preferably 5 ° C. or higher and 150 ° C. or lower, and more preferably 10 ° C. or higher and 150 ° C. or lower. When ΔT0 is less than 5 ° C., the effect of preventing condensation is reduced, which is not preferable. If ΔT0 exceeds 150 ° C., the film tends to soften, which is not preferable. More specifically, Tf0 is preferably 80 ° C. or higher and 160 ° C. or lower, and more preferably 100 ° C. or higher and 140 ° C. or lower.

  The dew condensation prevention process can be performed in a dew condensation prevention process chamber having the same configuration as that of the crossover section 90 or the drying chamber 97 (see FIG. 5). It is preferable to provide a dew condensation prevention treatment chamber on the upstream side of the facility where this treatment is performed. The condensation prevention treatment may be provided on either the upstream side or the downstream side of the cooling chamber, but is preferably provided on the upstream side.

  In the above embodiment, the TAC film is used. However, the present invention is not limited to the TAC film, and is composed of other polymers such as cellulose acylate and cyclic olefin, and can be obtained by a solution casting method or a melt casting method. It can also be used for polymer films produced by

  The polymer that can be used in the melt film-forming method is not particularly limited as long as it is a thermoplastic resin, and examples thereof include cellulose acylate, lactone ring-containing polymer, cyclic olefin, and polycarbonate. Of these, cellulose acylate and cyclic olefin are preferred, cellulose acylate containing an acetate group and propionate group, and cyclic olefin obtained by addition polymerization, more preferably cyclic olefin obtained by addition polymerization. It is.

(Cellulose acylate)
As the cellulose acylate, triacetyl cellulose (TAC) is particularly preferable. Of the cellulose acylates, those in which the hydroxyl group of cellulose is esterified with a carboxylic acid, that is, the substitution degree of the acyl group satisfies all of the following formulas (I) to (III) are more preferable. In the following formulas (I) to (III), A and B represent the substitution degree of the acyl group, A is the substitution degree of the acetyl group, and B is the substitution degree of the acyl group having 3 to 22 carbon atoms. It is. In addition, it is preferable that 90 weight% or more of TAC is a particle | grain of 0.1 mm-4 mm.
(I) 2.5 ≦ A + B ≦ 3.0
(II) 0 ≦ A ≦ 3.0
(III) 0 ≦ B ≦ 2.9

  Glucose units having β-1,4 bonds constituting cellulose have free hydroxyl groups at the 2nd, 3rd and 6th positions. Cellulose acylate is a polymer obtained by esterifying some or all of these hydroxyl groups with an acyl group having 2 or more carbon atoms. The degree of acyl substitution means the ratio of the hydroxyl group of cellulose esterified at each of the 2-position, 3-position and 6-position (100% esterification has a substitution degree of 1).

  The total acylation substitution degree, that is, DS2 + DS3 + DS6 is preferably 2.00 to 3.00, more preferably 2.22 to 2.90, and particularly preferably 2.40 to 2.88. Further, DS6 / (DS2 + DS3 + DS6) is preferably 0.28 or more, more preferably 0.30 or more, and particularly preferably 0.31 to 0.34. Here, DS2 is the degree of substitution of the hydroxyl group at the 2-position of the glucose unit with an acyl group (hereinafter also referred to as “degree of acyl substitution at the 2-position”), and DS3 is the degree of substitution of the hydroxyl group at the 3-position with an acyl group (hereinafter, DS6 is the substitution degree of the hydroxyl group at the 6-position with an acyl group (hereinafter also referred to as “acyl substitution degree at the 6-position”).

  Only one type of acyl group may be used in the cellulose acylate of the present invention, or two or more types of acyl groups may be used. When two or more kinds of acyl groups are used, it is preferable that one of them is an acetyl group. When the sum of the substitution degrees by the hydroxyl groups at the 2nd, 3rd and 6th positions is DSA, and the sum of the substitution degree by an acyl group other than the acetyl group at the 2nd, 3rd and 6th hydroxyl groups is DSB, the value of DSA + DSB is More preferably, it is 2.22 to 2.90, and particularly preferably 2.40 to 2.88. The DSB is 0.30 or more, particularly preferably 0.7 or more. Further, 20% or more of DSB is a substituent at the 6-position hydroxyl group, more preferably 25% or more is a substituent at the 6-position hydroxyl group, more preferably 30% or more, and particularly 33% or more is a 6-position hydroxyl group. It is preferable that it is a substituent. Furthermore, the cellulose acylate having a substitution degree of 6-position of cellulose acylate of 0.75 or more, further 0.80 or more, and particularly 0.85 or more can be mentioned. With these cellulose acylates, a solution having a preferable solubility (dope) can be produced. In particular, a good solution can be prepared in a non-chlorine organic solvent. Furthermore, it is possible to produce a solution having a low viscosity and good filterability.

  Cellulose, which is a raw material for cellulose acylate, may be obtained from either linter or pulp.

  The acyl group having 2 or more carbon atoms of the cellulose acylate of the present invention may be an aliphatic group or an aryl group and is not particularly limited. These are, for example, cellulose alkylcarbonyl esters, alkenylcarbonyl esters, aromatic carbonyl esters, aromatic alkylcarbonyl esters, and the like, each of which may further have a substituted group. Preferred examples of these include propionyl, butanoyl, pentanoyl, hexanoyl, octanoyl, decanoyl, dodecanoyl, tridecanoyl, tetradecanoyl, hexadecanoyl, octadecanoyl, iso-butanoyl, t-butanoyl, cyclohexanecarbonyl, oleoyl, benzoyl , Naphthylcarbonyl, cinnamoyl group and the like. Among these, propionyl, butanoyl, dodecanoyl, octadecanoyl, t-butanoyl, oleoyl, benzoyl, naphthylcarbonyl, cinnamoyl and the like are more preferable, and propionyl and butanoyl are particularly preferable.

(solvent)
Solvents for preparing the dope include aromatic hydrocarbons (eg, benzene, toluene, etc.), halogenated hydrocarbons (eg, dichloromethane, chlorobenzene, etc.), alcohols (eg, methanol, ethanol, n-propanol, n-butanol, Diethylene glycol, etc.), ketones (eg, acetone, methyl ethyl ketone, etc.), esters (eg, methyl acetate, ethyl acetate, propyl acetate, etc.) and ethers (eg, tetrahydrofuran, methyl cellosolve, etc.). In the present invention, the dope means a polymer solution or dispersion obtained by dissolving or dispersing a polymer in a solvent.

  Among these, halogenated hydrocarbons having 1 to 7 carbon atoms are preferably used, and dichloromethane is most preferably used. One kind of alcohol having 1 to 5 carbon atoms in addition to dichloromethane from the viewpoint of physical properties such as solubility of TAC, peelability of cast film from the support, mechanical strength of the film, and optical properties of the film It is preferable to mix several kinds. The content of the alcohol is preferably 2% by weight to 25% by weight and more preferably 5% by weight to 20% by weight with respect to the whole solvent. Specific examples of the alcohol include methanol, ethanol, n-propanol, isopropanol, n-butanol and the like, but methanol, ethanol, n-butanol or a mixture thereof is preferably used.

  By the way, recently, for the purpose of minimizing the influence on the environment, studies have been conducted on the solvent composition when dichloromethane is not used. For this purpose, ethers having 4 to 12 carbon atoms, carbon atoms A ketone having 3 to 12 carbon atoms, an ester having 3 to 12 carbon atoms, and an alcohol having 1 to 12 carbon atoms are preferably used. These may be used in combination as appropriate. For example, a mixed solvent of methyl acetate, acetone, ethanol, and n-butanol can be mentioned. These ethers, ketones, esters and alcohols may have a cyclic structure. A compound having two or more functional groups of ether, ketone, ester, and alcohol (that is, —O—, —CO—, —COO—, and —OH) can also be used as the solvent.

  The details of cellulose acylate are described in paragraphs [0140] to [0195] of JP-A-2005-104148. These descriptions are also applicable to the present invention. The same applies to additives such as solvents and plasticizers, deterioration inhibitors, ultraviolet absorbers (UV agents), optical anisotropy control agents, retardation control agents, dyes, matting agents, release agents, and release accelerators. JP-A-2005-104148 describes in detail in paragraphs [0196] to [0516].

(Cyclic olefin)
The cyclic olefin is preferably polymerized from a norbornene compound. This polymerization can be carried out by either ring-opening polymerization or addition polymerization. Examples of the addition polymerization include those described in Japanese Patent No. 3517471, Japanese Patent No. 3559360, Japanese Patent No. 3867178, Japanese Patent No. 3817721, Japanese Patent No. 3907908, Japanese Patent No. 3945598, Japanese Patent Publication No. 2005-527696, Japanese Patent Laid-Open No. 2006-2006. No. 28993 and International Publication No. 2006/004376 pamphlet. Particularly preferred is the one described in Japanese Patent No. 3517471.

  As the ring-opening polymerization, WO 98/14499 pamphlet, Japanese Patent No. 30605532, Japanese Patent No. 3320478, Japanese Patent No. 3273046, Japanese Patent No. 3404027, Japanese Patent No. 3428176, Japanese Patent No. 3687231, Japanese Patent No. 3873934, Patent No. 3912159 is mentioned. Among them, those described in WO98 / 14499 pamphlet and Japanese Patent No. 30605532 are preferable.

  Of these cyclic olefins, those of addition polymerization are more preferred.

(Lactone ring-containing polymer)
The thing which has the lactone ring structure represented by the following (general formula 1) is pointed out.

In (General Formula 1), R ¹ , R ² , and R ³ each independently represent a hydrogen atom or an organic residue having 1 to 20 carbon atoms. The organic residue may contain an oxygen atom.

  The content ratio of the lactone ring structure of (General Formula 1) is preferably 5 to 90% by weight, more preferably 10 to 70% by weight, and still more preferably 10 to 50% by weight.

  In addition to the lactone ring structure represented by (General Formula 1), at least selected from (meth) acrylic acid esters, hydroxyl group-containing monomers, unsaturated carboxylic acids, and monomers represented by the following (General Formula 2). A polymer structural unit (repeating structural unit) constructed by polymerizing one kind is preferred.

In General Formula 2, R ⁴ represents a hydrogen atom or a methyl group, X is a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, an aryl group, an —OAc group, a —CN group, a —CO—R ⁵ group, or an -C-O-R ⁶ group, Ac group represents an acetyl group, R ⁵ and R ⁶ represents a hydrogen atom or an organic residue having 1 to 20 carbon atoms.

  For example, those described in International Publication No. 2006/025445, JP 2007-70607 A, JP 2007-63541 A, JP 2006-171464 A, and JP 2005-162835 A can be used. .

(Use)
The optical film of the present invention is useful as a polarizing plate protective film or a retardation film. An optically anisotropic layer, an antireflection layer, an antiglare function layer, and the like may be added to the optical film to form a high function film such as a viewing angle widening film and an antiglare film.

  When used as a retardation film, the in-plane retardation Re is preferably 30 nm to 100 nm, and the thickness direction retardation Rth is preferably 70 nm to 300 nm.

(Film production)
The manufacturing method of each polymer film (sample No. A1-A4, BD) used for the Example is demonstrated.

(Sample No. A1)
The formulation for preparing the polymer solution (dope) used for film production is shown below.
The prescription of the compound used for preparation of the raw material dope is shown below.
Cellulose triacetate (degree of substitution 2.86) 89.3% by weight
Plasticizer A (triphenyl phosphate) 7.1% by weight
Plasticizer B (biphenyldiphenyl phosphate) 3.6% by weight
80% by weight of solid content (solute) with a composition ratio of dichloromethane
Methanol 13.5 wt%
n-butanol 6.5% by weight
A raw material dope was prepared by appropriately adding to a mixed solvent consisting of The TAC concentration of the raw material dope was adjusted to be about 23% by weight. The raw material dope is filtered through a filter paper (Toyo Filter Paper Co., Ltd., # 63LB), further filtered through a sintered metal filter (Nihon Seisen Co., Ltd. 06N, nominal pore size 10 μm), and further filtered through a mesh filter. I put it in the tank.

[Cellulose triacetate]
The cellulose triacetate used here has a residual acetic acid content of 0.1% by weight or less, a Ca content of 57 ppm, a Mg content of 41 ppm, a Fe content of 0.4 ppm, free acetic acid of 38 ppm, It contained 13 ppm of sulfate ion. The degree of substitution of the acetyl group with respect to the hydrogen at the 6-position hydroxyl group was 0.91. Further, 32.5% of all acetyl groups were acetyl groups in which the hydrogen of the hydroxyl group at the 6-position was substituted. Moreover, the acetone extraction part which extracted this TAC with acetone was 8 weight%, and the weight average molecular weight / number average molecular weight ratio was 2.5. The obtained TAC had a yellow index of 1.7, a haze of 0.08, and a transparency of 93.5%. This TAC is synthesized using cellulose collected from cotton as a raw material. In the following description, this is called cotton raw material TAC.

[Preparation of matting agent solution]
A matting agent solution was prepared from the following formulation.
Silica (Aerosil R972 manufactured by Nippon Aerosil Co., Ltd.) 0.67% by weight
Cellulose triacetate 2.93% by weight
Triphenyl phosphate 0.23% by weight
Biphenyl diphenyl phosphate 0.12% by weight
Dichloromethane 88.37 wt%
Methanol 7.68% by weight
A matting agent solution was prepared from the above formulation, dispersed with an attritor so that the volume average particle size was 0.7 μm, and then filtered with an astropore filter manufactured by Fuji Film Co., Ltd. And it put into the tank for mat agent liquids.

[Preparation of UV absorber solution]
An ultraviolet absorber solution was prepared from the following formulation.
2 (2′-hydroxy-3 ′, 5′-di-tert-butylphenyl) -5-chlorobenzotriazole 5.83% by weight
2 (2′-hydroxy 3 ′, 5′-di-tert-amylphenyl) benzotriazole 11.66% by weight
Cellulose triacetate 1.48% by weight
Triphenyl phosphate 0.12% by weight
Biphenyl diphenyl phosphate 0.06% by weight
Dichloromethane 74.38 wt%
Methanol 6.47% by weight
An ultraviolet absorber solution was prepared from the above formulation, filtered through an astropore filter manufactured by Fuji Film Co., Ltd., and then put into a tank for an ultraviolet absorber liquid method.

  As shown in FIG. 5, the TAC film 3 was manufactured using a film manufacturing facility 80. A liquid containing a matting agent liquid and a retardation control agent described later was added to the ultraviolet absorbent solution, and mixed and stirred with an in-line mixer to obtain a mixed additive. The additive supply line sent the mixed additive into the pipe. The in-line mixer obtained the casting dope 81 by mixing and stirring the raw material dope and the mixed additive. The casting drum 82 rotates around the shaft 82a under the control of the control unit, and holds the speed of the peripheral surface 82b in the traveling direction Z1 so as to be substantially constant within a range of 50 m / min to 200 m / min. did. The temperature of the peripheral surface 82b of the casting drum 82 was maintained so as to be substantially constant within a range of −10 ° C. to 10 ° C. In the casting die 84, the casting dope 81 was cast on the peripheral surface 82b, and a casting film 86 was formed on the peripheral surface 82b. After the casting film 86 became self-supporting by cooling, the casting film 86 was peeled off from the casting drum 82 as a wet film 88 using a peeling roller 89. In order to suppress peeling failure, the peeling speed (peeling roller draw) with respect to the speed of the casting drum 82 was appropriately adjusted in the range of 100.1% to 110%. The wet film 88 was sequentially guided to the transfer section 90, the pin tenter 91, and the drying chamber 97. The crossover part 90, the pin tenter 91, and the drying chamber 97 applied dry air to the wet film 88 to perform a predetermined drying process. The TAC film 3 obtained by this drying treatment was sent to the cooling chamber 7. In the cooling chamber 7, the TAC film 3 was cooled to 30 ° C. or lower. Thereafter, the TAC film 3 was subjected to a charge removal process, a knurling application process, and the like, and then transferred to the winding chamber 8. In the winding chamber 8, the TAC film 3 was wound around the winding core 36 a of the winding machine 36 while applying a desired tension with the press roller 37. The TAC film 3 manufactured by the film manufacturing facility 80 had a width of 1600 m to 2500 m and a film thickness of 110 μm.

(Sample Nos. A2 to A4)
Except what is shown in Table 1, sample No. In the same manner as the TAC film of A1, Sample No. A2-A4 TAC film 3 was obtained.

(Sample No. B)
Using the solution casting method, the film No. described in Example 1 of JP-A-2001-188128 was used. 1 (cellulose acetate propionate: thickness 80 μm, width 1900 mm) was obtained. This is designated as Sample No. It is called the B film.

(Sample No. C)
A melt film-forming method was performed according to Example 1 described in the pamphlet of International Publication No. 2006/025445 to obtain a polymer film (thickness 90 μm, width 1500 mm) made of a lactone ring-containing polymer resin. This is designated as Sample No. Called C film.

(Sample No. D)
A melt film-forming method was performed to obtain a polymer film (thickness 90 μm, width 1500 mm) made of cycloolefin resin A. This is designated as Sample No. It is called a D film.
Cycloolefin resin A (addition polymerization system): TOPAS 6013 (Tg = 130 ° C.) manufactured by Polyplastics Co., Ltd.

  Sample No. The details of the melt film-forming method for producing the film D are as follows. Cycloolefin resin A was dried with a vacuum dryer at 110 ° C. to a water content of 0.1% or less, melted at 260 ° C. using a single-screw kneading extruder, fed from a gear pump, and then a leaf disk with a filtration accuracy of 5 μm. Three cast rolls set at (Tg-5) ° C, Tg ° C, and (Tg-10) ° C from a hanger coat die with a slit interval of 0.8mm and 270 ° C via a static mixer. A melt (molten resin) was extruded on top. At this time, the touch roll was brought into contact with the most upstream cast roll at a surface pressure of 0.1 MPa to form an unstretched film having a thickness of 100 μm. The touch roll was the one described in Example 1 of JP-A-11-235747 (the one described as a double holding roll), and the temperature was adjusted to Tg-5 ° C. (however, the thickness of the thin metal outer cylinder was 2 mm) did).

  Then, after trimming both ends (each 3% of the total width) just before winding, the both ends were subjected to thicknessing (knurling) with a width of 10 mm and a height of 20 μm. In each level, the width was 1.5 m, and 3000 m was wound at 30 m / min.

  In addition, CAP shown in Table 1 represents cellulose acetate propionate, lactone represents a lactone ring-containing polymer resin, and cycloolefin represents cycloolefin resin A. The degree of substitution A is the degree of substitution with an acetyl group, and the degree of substitution B is the degree of substitution with a propionyl group. The addition amount shown in Table 1 is the addition amount of the retardation control agent shown in Chemical formula 3. The film thickness, in-plane retardation Re, thickness direction retardation Rth and haze shown in Table 1 are values for the polymer film obtained by the above method.

(Measurement method of in-plane retardation Re)
A sample film was cut from each polymer film to a predetermined size. This sample film was conditioned for 2 hours at a temperature of 25 ° C. and a humidity of 60% RH, and an extrapolated value of the retardation value measured from the vertical direction at 589.3 nm with an automatic birefringence meter (KOBRA21DH Oji Scientific Co., Ltd.). And calculated according to the following formula.
Re = | nX−nY | × d
nX represents the refractive index in the X direction, nY represents the refractive index in the Y direction, and d represents the thickness (film thickness) of the film.

(Measurement method of thickness direction retardation Rth)
A sample film was cut from each polymer film to a predetermined size. The sample film was conditioned for 2 hours at a temperature of 25 ° C. and a humidity of 60% RH, and the value measured from the vertical direction at 589.3 nm with an automatic birefringence meter (KOBRA21DH Oji Scientific Co., Ltd.) was tilted. However, it calculated according to the following formula from the extrapolated value of the retardation value measured similarly.
Rth = {(nX + nY) / 2−nTH} × d
nTH represents the refractive index in the thickness direction.

(Measurement method of haze)
The haze is a sample film obtained by cutting out each polymer film in a size of 40 mm × 80 mm, and this sample film is JIS K- using a haze meter (model: HGM-2DP, Suga Test Instruments) at 25 ° C. and 60% RH. Measured according to 6714.

  As shown in FIG. 1, each polymer film (sample Nos. A1 to A4, BD) obtained by the above method was stored in the supply chamber 4 of the off-line stretching equipment 2. The supply roller 9 supplied the polymer film from the supply chamber 4 to the tenter unit 5. In the tenter unit 5, the polymer film was stretched. Table 1 shows the stretching ratio Lx {= (Wo / Wi) × 100} of the stretching treatment and the temperature Tfe of the polymer film in the stretching treatment.

(Experiment 1 to Experiment 35)
The TAC film 3 (sample No. A1) that had undergone the stretching process in the tenter unit 5 was subjected to a condensation prevention process, a main process, and a heat treatment in order. Then, it cooled to room temperature. In the anti-condensation treatment, dry air was applied to the TAC film 3 to adjust the temperature Tf0 of the TAC film 3. In this process, the absolute humidity VHb and the relative humidity Hb of the second wet gas 400b are the values shown in Table 2, and the dew point of the second wet gas 400b is 10 ° C. or higher than the temperature Tf0 of the TAC film 3. The TAC film 3 was conveyed while maintaining the temperature Tfb of the TAC film 3 at the value shown in Table 2 while maintaining the temperature Tfb for the treatment time Pb. The transport tension F in the wet gas contact chamber 6 is as shown in Table 2. In the heat treatment, the relative humidity H2 of the dry gas in the heat treatment chamber was adjusted to the value shown in Table 2, and the state where the temperature Tf2 of the TAC film 3 became the value shown in Table 2 was maintained for the treatment time P2. Note that “-” shown in Table 2 indicates that the corresponding processing was not performed.

  Further, the film thickness TH0, in-plane retardation Re0, thickness direction retardation Rth0, haze, and internal haze in Table 3 are after performing the anti-condensation treatment, the main treatment and the heat treatment under the conditions shown in Table 2. It is a value about a TAC film before performing a wet heat durability test and a dry heat durability test.

  The internal haze was measured as follows. After conditioning the sample film at 25 ° C and 60% RH for 2 hours or more, the sample film is sandwiched between two slide glass plates via liquid paraffin, and the haze of the sample film is measured with a haze meter (HGM-2DP, Suga Test Machine). did. A blank sample in which only liquid paraffin was sandwiched between two slide glass plates without a sample film was prepared, and the haze of this blank sump was measured. And what subtracted the measured value of the haze of the blank sump from the measured value of the haze of the sample film was made into the internal haze.

  The following test was performed on the TAC film after the condensation prevention treatment, the main treatment and the heat treatment were performed under the conditions shown in Table 2.

(Damp heat durability test)
A sample film having a length X0 in the X direction and a length Y0 in the Y direction was cut out from the TAC film, and a wet heat durability test was performed on the sample film. In the wet heat durability test, the sample film was continuously placed in the test chamber for 21 days. The environmental conditions inside the test chamber were kept almost constant at a temperature of 60 ° C. and a humidity of 90% RH. For the sample film after the wet heat durability test, in-plane retardation Re1 _WET , thickness direction retardation Rth1 _WET , X direction length X1 _WET , and Y direction length Y1 _WET were measured.

(Dry heat durability test)
A sample film having a length X0 in the X direction and a length Y0 in the Y direction was cut out from the TAC film 3, and a dry heat durability test was performed on the sample film. In the dry heat durability test, the sample film was continuously placed in the test chamber for 21 days. The environmental conditions inside the test chamber were kept almost constant at a temperature of 80 ° C. and a humidity of 5% RH. The sample film after the dry heat durability test was measured for in-plane retardation Re1 _DRY , thickness direction retardation Rth1 _DRY , X direction length X1 _DRY , and Y direction length Y1 _DRY .

ΔX _WET , ΔY _WET , ΔRe _WET , and ΔRth _WET shown in Table 4 are the amount of variation in the dimension in the X direction {(X1 _WET −X0) / X0} and the dimension in the Y direction before and after the wet heat durability test. The fluctuation amount {(Y1 _WET- Y0) / Y0}, the fluctuation amount of in-plane retardation (Re1 _WET- Re0), and the fluctuation amount of thickness direction retardation (Rth1 _WET- Rth0) are shown. Further, ΔX _DRY , ΔY _DRY , ΔRe _DRY , and ΔRth _DRY shown in Table 5 are the amount of dimensional variation in the X direction {(X1 _DRY −X0) / X0} and Y direction in the sample film before and after the dry heat durability test. The amount of variation in dimensions {(Y1 _DRY -Y0) / Y0}, the amount of variation in in-plane retardation (Re1 _DRY -Re0), and the amount of variation in retardation in the thickness direction (Rth1 _DRY -Rth0).

ΔRe _WET and ΔRth _WET after 1 day, 5 days, 10 days, and 21 days from the start of the wet heat durability test were measured. In Table 4, @ 1d, @ 5d, @ 10d, and @ 21d indicate the measured values of ΔRe _WET and ΔRth _WET after 1 day, 5 days, 10 days, and 21 days, respectively. Similarly, ΔRe _DRY and ΔRth _DRY after 1 day, 5 days, 10 days, and 21 days from the start of the dry heat durability test were measured. In Table 5, @ 1d, @ 5d, @ 10d, and @ 21d indicate the measured values of ΔRe _DRY and ΔRth _DRY after 1 day, 5 days, 10 days, and 21 days, respectively.

  Sample No. described in Table 1 For the A2 to A4 and C to D films, each treatment was performed in the same manner as in Experiments 1 to 35. As a result, the same tendency results as in Experiments 1 to 35 could be obtained.

  From the results of Experiment 1 to Experiment 35, it was found that the retardation of the retardation film before and after the wet heat durability test can be suppressed by performing this treatment on the polymer film.

(Experiment 41)
An optical film 35 is produced from the TAC film 3 in the same manner as in Experiments 1 to 35 except that a pretreatment is performed between the dew condensation prevention treatment and the main treatment, and a post treatment is performed between the main treatment and the heat treatment. did. In the pretreatment, the first wet gas 400a was brought into contact with the TAC film 3. In the post-treatment, the third wet gas 400c was brought into contact with the TAC film 3. The difference (= Hb−Ha) between the relative humidity Ha of the first wet gas 400a and the relative humidity Hb of the second wet gas 400b was 70% RH. Further, the difference (= Hb−Hc) between the relative humidity Hb of the second wet gas 400b and the relative humidity Hc of the third wet gas 400c was 70% RH. The value of (| VHas−VHae | / Pa) was 500 (g / m ³ seconds).

(Experiment 42)
The optical film 35 was produced from the TAC film 3 in the same manner as in the experiment 21 except that the value of (| VHas−VHae | / Pa) was 600 (g / m ³ seconds).

(Evaluation of wrinkle occurrence)
About each optical film obtained by Experiment 41-42, it was judged visually whether the wrinkle had generate | occur | produced. The optical film obtained in Experiment 41 was not wrinkled, but the optical film obtained in Experiment 42 was wrinkled.

  From Experiments 41 to 42, it was found that according to the present invention, the generation of wrinkles in the optical film can be reliably suppressed.

It is explanatory drawing which shows the outline | summary of an offline extending | stretching installation. It is a top view which shows the outline | summary of a tenter part. It is a perspective view which shows the outline | summary of a wet gas contact chamber. It is a fragmentary sectional view which shows the outline | summary of an air supply head. It is explanatory drawing which shows the outline | summary of a film manufacturing equipment.

2 offline stretching equipment 3 TAC film 5 tenter section 6 wet gas contact chamber 6a pretreatment area 6b main treatment area 6c post treatment areas 42a to 42c, 43b air supply head 70 wet gas supply equipment 80 film production equipment 400a to 400c first wet Gas to third wet gas

Claims (8)

A casing having a film transport section of a polymer film subjected to stretching treatment;
A pretreatment area provided in the film transport section;
A main processing area provided in the film transport section on the downstream side in the transport direction from the pretreatment area;
A main processing unit for contacting the polymer film and wet gas in the main processing area;
A polymer film property adjusting apparatus comprising: the polymer film in the pretreatment area; and a pretreatment unit that contacts a pretreatment gas having a humidity lower than that of the wet gas. The film transport unit has a post-processing area on the downstream side in the transport direction from the main processing area,
2. The polymer film property adjusting apparatus according to claim 1, further comprising a post-processing unit that contacts the polymer film in the post-processing area and a post-processing gas having a humidity lower than that of the wet gas. A main treatment in which a stretched polymer film and a wet gas are brought into contact with each other;
A method for adjusting the properties of a polymer film, comprising: the polymer film before undergoing the main treatment; and a pretreatment in which a pretreatment gas having a lower humidity than the wet gas is brought into contact with the polymer film. The absolute humidity of the pretreatment gas in contact with the polymer film at the start of the pretreatment is VHas (g / m ³ ), and the absolute amount of the pretreatment gas in contact with the polymer film upon completion of the pretreatment When the humidity is VHae (g / m ³ ) and the required time from the start of the pretreatment to the completion of the pretreatment is Pa (seconds),
4. The property adjusting method for a polymer film according to claim 3, wherein the value of (| VHas−VHae | / Pa) is 500 (g / m ³ seconds) or less.   The method for adjusting the property of a polymer film according to claim 3 or 4, wherein after the main treatment, a post-treatment is performed in which a post-treatment gas having a lower humidity than the wet gas is brought into contact with the polymer film. The absolute humidity of the post-treatment gas that comes into contact with the polymer film at the start of the post-treatment is VHcs (g / m ³ ), and the absolute humidity of the post-treatment gas that comes into contact with the polymer film upon completion of the post-treatment Is VHce (g / m ³ ), and the required time from the start of the post-processing to the completion of the post-processing is Pc (seconds),
6. The property adjusting method for a polymer film according to claim 5, wherein the value of (| VHcs−VHce | / Pc) is 1000 (g / m ³ seconds) or less.   The property adjustment method for a polymer film according to any one of claims 3 to 6, wherein the polymer film is produced by a solution casting method.   A method for producing an optical film, comprising producing an optical film from the polymer film by the method for adjusting properties of a polymer film according to any one of claims 3 to 7.

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