JP2010158787A - Method and apparatus for adjusting property and state of polymer film and method for producing optical film - Google Patents

Abstract

A retardation film having uniform optical characteristics and small retardation fluctuation before and after a wet heat durability test is produced.
A TAC film stored in a supply chamber is sent to a tenter unit. The tenter unit 5 extends the TAC film 3 in the Y direction. The TAC film 3 sent out from the tenter unit 5 passes through the transport paths 51 and 52 in the water vapor contact chamber 6. The conveyance paths 51 and 52 are divided into three areas in the Y direction. In each of the areas 51a to 51c, the wet gases 400a to 400c come into contact with the TAC film 3. The film measuring device 75 measures the retardation of the TAC film 3 in each of the areas 52a to 52c. The wet gas supply device 78 adjusts the temperature and humidity of each of the wet gases 400a to 400c based on the retardation measured by the film measuring device 75.
[Selection] Figure 1

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 properties 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 durability test under high temperature and high humidity conditions (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 process, it is considered that the in-plane retardation Re and the thickness direction retardation Rth, which are important optical characteristics in the retardation film, vary, but in Patent Document 1, a letter resulting from the humidification process is used. No mention is made of variations in the foundation Re, Rth. Therefore, the method described in Patent Document 1 does not take into consideration fluctuations in retardation Re and Rth of the retardation film.

  The methods described in Patent Document 2 and Patent Document 3 relate to a method for producing a film that obtains a different Nz factor with a retardation Re in the vicinity of λ / 4, and suppresses fluctuations in optical properties before and after the wet heat durability test. This is not a consideration.

  The present invention solves the above problems, and provides a method and apparatus for adjusting the properties of a polymer film and a method for producing an optical film, which can produce a retardation film having a low retardation Rth variation before and after a wet heat durability test. It is to provide.

  The apparatus for adjusting an optical property of a polymer film of the present invention is orthogonal to the transport direction among a film transport unit that transports a polymer film subjected to stretching treatment and the polymer film that is transported by the film transport unit. Supplying second steam to both ends in a direction orthogonal to the transport direction among the first steam contact section for supplying first steam to the center of the direction and the polymer film transported by the film transport section Based on a property distribution in a direction perpendicular to the transport direction of the polymer film supplied with the second water vapor contact portion and the first water vapor or the second water vapor, at least of the first water vapor and the second water vapor And a water vapor supply condition changing unit for changing one of the supply conditions.

  The method for adjusting the optical properties of the polymer film of the present invention is a method of transporting a stretched polymer film, supplying water vapor to the polymer film, and a temperature and humidity distribution near the polymer film in a direction perpendicular to the transport direction. The water vapor supply condition is changed in a direction orthogonal to the transport direction so that the pressure is constant.

  It is preferable that the water vapor is individually supplied to a central portion and both end portions in a direction orthogonal to the transport direction in the polymer film. In addition, the property distribution of the polymer film in a direction orthogonal to the transport direction is measured, the supply condition of the water vapor is changed based on the property distribution, and the temperature and humidity distribution in the direction orthogonal to the transport direction is made constant. It is preferable to do.

  It is preferable that the temperature distribution in the vicinity of the polymer film in the direction orthogonal to the transport direction is within 5 ° C., and the humidity distribution in the vicinity of the polymer film in the direction orthogonal to the transport direction is within 10%. 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 using the property adjusting method for the polymer film.

  According to the present invention, since the polymer film that has been subjected to the stretching treatment is conveyed and the polymer film and the wet gas are brought into contact with each other, it is possible to produce an optical film having a small variation in retardation Rth before and after the wet heat durability test. Become. And based on the property distribution of the polymer film in the direction orthogonal to the conveyance direction of the polymer film, among the polymer film, the first water vapor contact portion that applies water vapor to the central portion in the direction orthogonal to the conveyance direction, and the polymer film Since the supply condition of water vapor is changed in at least one of the second water vapor contact portions that apply water vapor to both ends in the direction orthogonal to the transport direction, the property distribution of the polymer film becomes uniform in the direction orthogonal to the transport direction. 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 water vapor contact chamber 6, a cooling chamber 7, and a winding chamber 8. Prepare. In the supply chamber 4, a long TAC film 3 manufactured by a film manufacturing facility described later and wound around a winding core is stored. 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 4 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 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 of the film transport path in the Y direction, and are arranged to face each other via the film transport 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 move along the rails 11 and 12. As the first and second chains 13 and 14 travel, the clip 15 moves along the rails 11 and 12.

  The rails 11 and 12 near the tenter inlet 26 are provided with a grip start position Pa, and the rails 11 and 12 near the tenter outlet 27 are provided with a grip release position Pb. When the clip 15 passes the grip start position Pa due to the movement of the first and second chains 13 and 14, the clip 15 grips the ear portion of the TAC film 3. When the clip 15 passes the grip release position Pb, 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 Y-direction width Wb of the TAC film 3 at the grip release position Pb is larger than the Y-direction width Wa of the TAC film 3 at the grip start position Pa. From the grip start position Pa to the grip release position Pb, the TAC film 3 is stretched in the Y direction by the clips 15 moving along the rails 11 and 12. A position Pc may be provided between the position Pa and the position Pb in the X direction, and the rails 11 and 12 may be arranged so that the width Wc in the Y direction of the TAC film 3 at the position Pc is larger than the width Wa. . The width Wc may be larger than the width Wb or may be equal to the width Wb.

  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 divide a plurality of zones in the X direction and change the film heating conditions for each zone. For example, in the X direction, a preheating zone for preheating the TAC film 3, a heating zone for heating the TAC film 3 to a stretchable degree, and a stretching zone for stretching the TAC film 3 may be provided. In addition to these, a heat relaxation zone for stopping the stretching of the TAC film 3 and heating the TAC film 3 so as to relax the strain remaining in the TAC film 3 may be provided on the downstream side in the X direction from the stretching zone. .

  As shown in FIG. 1, an ear clip device 30 is provided between the tenter unit 5 and the water vapor 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 water vapor 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 water vapor 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.

(Water vapor contact chamber)
As shown in FIGS. 1 and 3, the water vapor contact chamber 6 is partitioned into a contact area 41 and a measurement area 42 from the upstream side in the X direction by a partition member (not shown). In each of the areas 41 to 42, a plurality of rollers are sequentially provided from the upstream side in the X direction toward the downstream side. The plurality of rollers form conveyance paths 51 to 52 for conveying the TAC film 3 in the respective areas 41 to 42.

  A plurality of partition plates (not shown) are preferably provided in the Y direction in the water vapor contact chamber 6 and arranged so as to stand up with respect to the transport paths 51 to 52. One end portion of each partition plate is in contact with the inner wall of the water vapor contact chamber 6, and one end portion extends to the vicinity of the transport paths 51 to 52. By this partition plate, the conveyance path 51 is partitioned into three parts: a first area 51a located at the center in the Y direction, and a second area 51b and a third area 51c located at both ends in the Y direction. Similarly, the conveyance path 52 is partitioned by a partition plate (not shown) into a first area 52a located at the center in the Y direction, and a second area 52b and a third area 52c located at both ends in the Y direction.

  In the vicinity of the conveyance path 51, a plurality of rollers 61 to 65 are provided. The plurality of rollers 61 to 65 are sequentially arranged from the upstream side in the X direction toward the downstream side, and are arranged in a staggered manner. Further, in the vicinity of the conveyance path 51, a plurality of air supply heads 66 are sequentially arranged from the upstream side in the X direction toward the downstream side. In addition, it is preferable to provide a plurality of sensors in the water vapor contact chamber 6 for detecting temperatures or humidity at a plurality of positions arranged in the Y direction in the vicinity of the conveyance path 51.

(Air supply head)
As shown in FIGS. 4 and 5, the air supply head 66 includes an air supply head main body 70, a plurality of ejection holes 71 a to 71 c, and flow paths 72 a to 72 c. The air supply head main body 70 formed in a columnar shape is arranged so that the axis is in the Y direction. The plurality of ejection holes 71 a to 71 c are provided on the peripheral surface of the air supply head main body 70 and are arranged so as to be aligned in the circumferential direction and the Y direction of the air supply head main body 70. The plurality of ejection holes 71a are formed to face the first area 51a. Similarly, the plurality of ejection holes 71b are formed so as to face the second area 51b, and the plurality of ejection holes 71c are formed so as to face the third area 51c. The flow paths 72 a to 72 c are provided inside the air supply head main body 70. The flow path 72a communicates with the plurality of ejection holes 71a and a wet gas supply device described later. Similarly, the flow path 72b communicates with the plurality of ejection holes 71b and a wet gas supply machine described later, and the flow path 72c communicates with the plurality of ejection holes 71c and a wet gas supply machine described later.

(Film measuring machine)
As shown in FIGS. 1 and 3, a film measuring device 75 is preferably provided in the vicinity of the conveyance path 52. The film measuring machine 75 has a retardation measuring unit (not shown) and a dimension measuring unit (not shown). The retardation measuring unit detects in-plane retardation Re and thickness direction retardation Rth of the TAC film 3 in the transport path 52. The dimension measuring unit measures at least one of the thickness of the TAC film 3 in the transport path 52, the dimension in the X direction, and the dimension in the Y direction. It is preferable to set a plurality of measurement points for the retardation measurement unit and the dimension measurement unit so as to be aligned in the Y direction.

  The measuring method of the in-plane retardation Re and the thickness direction retardation Rth may be a known measuring method such as a parallel Nicol rotation method. Moreover, the measuring method of thickness, the dimension of a X direction, and the dimension of a Y direction should just be a well-known measuring method, such as a method using an optical characteristic measuring device, for example.

(Wet gas supply machine)
The wet gas supply unit 78 includes a first wet gas supply unit 78a to a third wet gas supply unit 78c. The first wet gas supply unit 78a includes a mixing unit, a heating unit, a control unit, and an air blowing 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 humidity and temperature of the 1st moist gas 400a can be adjusted substantially constant within a desired range. Then, the blower supplies the first wet gas 400a adjusted so that the humidity and temperature are within the predetermined ranges to the flow path 72a (see FIG. 4) of the air supply head 66. Thus, the first wet gas supply unit 78a supplies the first wet gas 400a adjusted so that the humidity and temperature are within the predetermined ranges to the flow path 72a (see FIG. 4).

  Similarly, the second wet gas supply unit 78b and the third wet gas supply unit 78c have the same configuration as the first wet gas supply unit 78a. Then, the second wet gas supply unit 78b supplies the second wet gas 400b adjusted so that the humidity and temperature are within the predetermined ranges to the flow path 72b (see FIG. 4). Further, the third wet gas supply unit 78c supplies the third wet gas 400c adjusted so that the humidity and temperature are within the predetermined ranges to the flow path 72c (see FIG. 4).

  Each area 41 to 42 is provided with an exhaust duct (not shown). The exhaust duct is connected to the wet gas supply machine 78 via a pipe (not shown). The wet gas supply machine 78 collects air in each area 41 to 42 through the exhaust duct. The recovered air is reused for the preparation of each wet gas.

  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 Pa, and cancels gripping of both side edges at the grip release position Pb. 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 Pa and the grip release position Pb. The stretching ratio Lx {= (Wb / Wa) × 100} of the TAC film 3 in the tenter portion 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 TAC film 3 sent from the tenter unit 5 is sent to the water vapor contact chamber 6 by cutting off both side edges by the edge-cutting device 30. A predetermined process is performed in the water vapor contact chamber 6. Details of the predetermined processing will be described later. The TAC film 3 sent out from the water vapor contact chamber 6 is sent to the cooling chamber 7. The TAC film 3 is cooled to approximately room temperature in the cooling chamber 7. The cooled TAC film 3 becomes an 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.

  As shown in FIGS. 3 and 4, the TAC film 3 sent to the water vapor contact chamber 6 sequentially passes through the transport path 51 and the transport path 52. The wet gas supply device 78 has a first wet gas 400a adjusted to a predetermined temperature Ta1 and humidity Ha1, a second wet gas 400b adjusted to a predetermined temperature Tb1 and humidity Hb1, and a predetermined temperature Tc1 and humidity Hc1. The adjusted third wet gas 400c is supplied to the supply head 66, respectively. The first wet gas 400a supplied to the air supply head 66 contacts the TAC film 3 in the first area 51a, that is, the portion of the TAC film 3 at the center in the Y direction. In addition, the second wet gas 400b and the third wet gas 400c supplied to the air supply head 66 are the TAC film 3 in the second area 51b and the third area 51c, that is, portions of the TAC film 3 at both ends in the Y direction. Contact with. In this way, the water vapor contact process is performed on the TAC film 3 in the transport path 51.

  By the water vapor contact 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.

  Moreover, the sensor provided in the wet gas contact chamber 6 detects the temperature and humidity in the vicinity of each area 51a-51c. The wet gas supply machine 78 reads the temperature and humidity detected by each sensor. Next, the wet gas supply unit 78 calculates the temperature distribution and humidity distribution in the Y direction around the conveyance path 51 based on the detection values read from the sensors. Then, the wet gas supply device 78 adjusts the temperature and humidity of each of the wet gases 400a to 400c based on these temperature distribution and humidity distribution so that the temperature distribution and humidity distribution in the vicinity of the transport path 51 are constant in the Y direction. Adjust. Thereby, water vapor contact processing can be performed uniformly in the Y direction.

  Further, the TAC film 3 that has undergone the water vapor contact treatment travels on the conveyance path 52. Of the TAC film 3, the portion that has passed through the first area 51a travels through the first area 52a, the portion that has passed through the second area 51b passes through the second area 52b, and the portion that passes through the third area 51c is third. Travel in area 52c. The film measuring device 75 measures the optical characteristics and dimensions of the TAC film 3 in each of the areas 52a to 52c. The wet gas supply device 78 reads the optical properties and dimensions measured by the film measuring device 75, and obtains the optical properties and size distribution in the Y direction for the TAC film 3 in the transport path 52. Further, the wet gas supply device 78 adjusts the temperature and humidity of each of the wet gases 400a to 400c based on the distribution in the Y direction with respect to the optical characteristics and dimensions. And each wet gas 400a-400c by which temperature and humidity were adjusted is supplied to the TAC film 3 in the conveyance path 51, respectively, and a water vapor contact process is performed. The method for adjusting the temperature and humidity of each of the wet gases 400a to 400c may be performed so that the optical characteristics and the dimensional distribution are uniform in the TAC film 3 that has undergone a newly performed water vapor contact treatment. Thereby, the optical film 35 whose optical characteristics and dimensions are uniform in the Y direction can be manufactured.

  In addition, adjustment of the temperature and humidity of each wet gas 400a-400c is performed based on both the temperature distribution and humidity distribution in the conveyance path 51 vicinity, and the distribution of the Y direction about each retardation, a dimension, and a film thickness. Alternatively, it may be performed based on either one of them.

  Details of each process will be described below.

(Water vapor contact treatment)
The lower limit of the temperature Tf1 of the TAC film 3 in the steam contact treatment is preferably 100 ° C. or higher, more preferably 102 ° C. or higher, and particularly preferably 104 ° C. or higher. The upper limit of the temperature Tf1 is preferably 150 ° C. or less, more preferably 140 ° C. or less, and particularly preferably 130 ° C. or less. If the temperature Tf1 is less than 100 ° C., it is not preferable because the time required for the water vapor contact treatment to reduce the amount of change in the optical properties before and after the wet heat durability test is increased. When the temperature Tf1 exceeds 150 ° C., curling of the TAC film 3 becomes remarkable, which is not preferable. Therefore, the temperatures Ta1 to Tc1 of the wet gases 400a to 400c may be adjusted as appropriate so that the temperature Tf1 falls within the above range. For example, the temperatures Ta1 to Tc1 of the wet gases 400a to 400c are preferably 70 ° C. or higher and 200 ° C. or lower, more preferably 90 ° C. or higher and 160 ° C. or lower, and 95 ° C. or higher and 140 ° C. or lower. Most preferred.

The relative humidity Ha1 to Hc1 of each wet gas 400a to 400c 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 that When the relative humidity Ha1 to Hc1 is less than 20% RH, the effect of suppressing ΔRth _WET is small, which is not preferable. Further, when it is desired to reduce the in-plane retardation Re of the optical film 35, it is preferable to increase the relative humidity Ha1 to Hc1, and when it is desired to increase the in-plane retardation Re of the optical film 35, the relative humidity. It is preferable to increase Ha1 to Hc1.

  Further, the temperatures Ta1 to Tc1 and relative humidity Ha1 to Hc1 are such that the humidity distribution in the vicinity of the conveyance path 51 in the Y direction is within 10% so that the temperature distribution in the vicinity of the conveyance path 51 in the Y direction is within 5 ° C. It is preferable to adjust to. The temperature distribution near the conveyance path 51 is more preferably within 3 ° C., and the humidity distribution near the conveyance path 51 is more preferably within 7%. Here, of the temperatures near the transport path 51 in the Y direction, when Tmax is the maximum temperature and Tmin is the minimum temperature, the temperature distribution near the transport path 51 is represented by | Tmax−Tmin |. Further, when the maximum humidity in the vicinity of the transport path 51 in the Y direction is Hmax, and the minimum humidity is Hmin, the humidity distribution near the transport path 51 is represented by | Hmax−Hmin |.

  The wet gas supply device 78 reads the values detected by these sensors, and obtains the temperature distribution or humidity distribution near the conveyance path 51 in the Y direction from each value and the above-described formula. Next, the wet gas supplier 78 adjusts the temperatures Ta1 to Tc1 and the relative humidity Ha1 to Hc1 according to the temperature distribution or humidity distribution. In this way, reading of the values detected by each sensor, calculation of temperature distribution or humidity distribution, and adjustment of the temperature or humidity of the humid gas are desired for the temperature distribution or humidity distribution calculated from the values detected by the sensors. Repeat until it becomes.

  Moreover, the range of the treatment time P1 of the water vapor contact treatment 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 P1 is preferably 60 minutes or less, and more preferably 10 minutes or less. On the other hand, the lower limit of the processing time P1 is, for example, preferably 5 seconds or more, more preferably 10 seconds or more, and particularly preferably 30 seconds or more.

  In the above embodiment, the conveyance paths 51 and 52 are each divided into three areas in the Y direction. However, the present invention is not limited to this, and the conveyance paths 51 and 52 are divided into two, or four or more areas in the Y direction. You may partition. In this case, a measuring instrument for measuring the optical characteristics or dimensions of the TAC film 3 in each area of the conveyance path 52 is provided with ejection holes formed in the air supply head so as to face each area of the conveyance path 51. Each wet gas adjusted based on the value measured by the measuring machine may be applied to the TAC film 3.

  Moreover, when the water vapor | steam contact process which makes each wet gas 400a-400c contact is performed about the TAC film 3 by which the extending | stretching process was performed, as a result of TAC film 3 expanding rapidly due to absorption of a water molecule, a TAC film 3. As a result, the optical film 35 is wrinkled. Therefore, it is preferable to perform the pretreatment on the TAC film 3 before the steam contact treatment. The pretreatment refers to a treatment in which a pretreatment gas having a lower humidity than the wet gases 400 a to 400 c is brought into contact with the TAC film 3. Thereby, the rapid expansion | swelling of the TAC film 3 resulting from absorption of a water molecule can be suppressed. Furthermore, you may perform the process (henceforth a post-process) similar to a pre-processing to the TAC film 3 which passed the water vapor | steam contact process.

The absolute humidity of the atmosphere at the position where pre-processing starts (hereinafter referred to as pre-processing start position) is Hps (g / m ³ ), and the position when pre-processing is completed (hereinafter referred to as pre-processing completion position). When the absolute humidity of the atmosphere is Hpe (g / m ³ ), and the time required for the TAC film 3 at the pretreatment start position to reach the pretreatment completion position is T1 (seconds), (| Hps The value of −Hpe | / T1) is preferably 500 (g / m ³ seconds) or less, and more preferably 300 (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 of the atmosphere at the position where post-processing starts (hereinafter referred to as post-processing start position) is defined as Has (g / m ³ ), and the position when post-processing is completed (hereinafter referred to as post-processing completion position). When the absolute humidity of the atmosphere in the atmosphere is Hae (g / m ³ ) and the time required for the TAC film 3 at the post-processing start position to reach the post-processing completion position is T3 (seconds), (| Has The value of −Hae | / T3) is preferably 1000 (g / m ³ seconds) or less, and more preferably 500 (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 an absolute humidity measured at the center in the Y direction in the area where each process is performed, or may be an average value of absolute humidity measured at a plurality of locations. . Absolute humidity can be measured with a known hygrometer.

  In the above-described embodiment, the water vapor contact treatment is performed using a wet gas composed of water vapor and a predetermined gas. However, the present invention is not limited to this, and water vapor may be used instead of the wet gas. In this case, in order to adjust the conditions of the water vapor contact treatment, the temperature and humidity of the wet gas are adjusted, but instead, the temperature of the water vapor and the ejection amount from the air supply head 66 may be adjusted.

  In the said embodiment, although the water vapor contact process was performed in the contact area 41, this invention is not restricted to this, You may perform a water vapor contact process to the TAC film 3 between the tenter part 5 and the winding chamber 8. FIG. When performing the water vapor contact process in the tenter unit 5, the water vapor contact process may be performed simultaneously with the stretching process or as a thermal relaxation process after the stretching process.

  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. The stretching means may be any means that can apply a predetermined tension to the TAC film 3 like the tenter unit 5.

  As the TAC film 3 to be subjected to the steam contact treatment, it is preferable to use a TAC film that has been sufficiently dried, that is, a solvent in which almost no solvent remains and the fluidity of polymer molecules has almost disappeared. The amount 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. 6, 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 facility 2 (see FIG. 1), the TAC film 3 produced by the solution casting method is subjected to stretching treatment and then subjected to water vapor contact treatment, but the present invention is limited to this. Absent. When the TAC film 3 wound up on the winding core has been subjected to a stretching process in the solution casting method, the TAC film 3 taken out from the winding core is directly subjected to the steam contact process without being subjected to the stretching process. Also 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 to apply a dry gas to the TAC film 3 that has been subjected to the water vapor contact treatment, and perform a heat treatment to bring the temperature of the TAC film 3 within a predetermined range. It is preferable to sequentially perform the steam contact treatment and the heat treatment sequentially. By this heat treatment, it is possible to produce a TAC film 3 having a small amount of variation in each retardation, dimensional change in the X direction, or Y direction not only before and after the wet heat durability test but also before and after the dry 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 gas is within a range equivalent to the temperature Tf2. When the temperature Tf2 is less than 110 ° C. or the temperature Tf2 exceeds 160 ° C., the amount of variation in retardation before and after the wet heat durability test and the dry heat durability test, the dimensional change in the X direction, and the dimension in the Y direction This is not preferable because the amount of change cannot be suppressed. Further, the temperature Tf2 is preferably higher than the temperature Tf1.

  The relative humidity H2 of the dry gas in the heat treatment is preferably 20% RH or less, and more preferably 10% RH or less. When the relative humidity H2 of the dry gas 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 amount of variation in each retardation before and after the wet heat endurance test and the dry heat endurance test, and the dimensional change amount in the X or Y direction can be suppressed. It is not preferable because it cannot be done.

  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. 6). It is preferable to provide the heat treatment chamber on the downstream side of the facility where the steam contact 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 subjected to the water vapor contact treatment, the dry gas is applied to the TAC film 3 before the water vapor contact treatment is performed, so that the temperature of the TAC film 3 of the above embodiment is within a predetermined range. It is preferable to carry out the treatment. It is preferable to sequentially perform the dew condensation prevention treatment and the water vapor contact treatment sequentially.

  The range of the temperature Tf0 of the TAC film 3 at the completion of the condensation prevention treatment is preferably set to a temperature higher by ΔT0 than the lowest dew point of each 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. 6). The dew condensation prevention treatment chamber is preferably provided on the upstream side of the facility where the water vapor contact 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 at least one of pre-treatment, post-treatment, heat treatment, and anti-condensation treatment, a predetermined gas having a different temperature or humidity is divided into a plurality of areas in the TAC film 3 in each area. Each may be assigned. And the adjustment method of the temperature or humidity of a predetermined gas may be the same as that of each wet gas 400a-400c.

  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, referred to as “acyl group”). 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)
This refers to those having a lactone ring structure represented by the following (General Formula 1).

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. 6, 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 of the winder 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 at a temperature of 25 ° C. and a humidity of 60% RH for 2 hours, and the value measured from the vertical direction at 589.3 nm with an automatic birefringence meter (KOBRA21DH Oji Scientific Co., Ltd.) and the film surface were 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 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 sequentially subjected to a condensation prevention process, a water vapor contact process, and a heat treatment. 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 the steam contact treatment, one kind of wet gas was applied to the TAC film 3. The absolute humidity VH1 and relative humidity H1 of the wet gas are adjusted to the values shown in Table 2, and the dew point of the wet gas is adjusted to be higher by 10 ° C. than the temperature Tf0 of the TAC film 3, and the TAC The TAC film 3 was transported while maintaining the state in which the temperature Tf1 of the film 3 was a value shown in Table 2 only for the processing time P1. The transport tension F in the water vapor 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 steam contact 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 blank hump's haze from the measured value of the haze of the sample film was made into the internal haze.

  The following test was done about the TAC film after performing the dew condensation prevention process, the water vapor contact process, and the heat processing on 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 .

Table 4 shows _{ΔX WET, ΔY WET, ΔRe WET} , and [Delta] Rth _WET is in the sample film between before and after the wet heat durability test, the amount of variation in the X-direction dimension _{{(X1 WET -X0) / X0} }, the Y-direction dimension 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 one day, five days, ten 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 were obtained.

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

(Experiment 41)
The optical film 35 was manufactured from the TAC film 3 in the same manner as in Experiment 1 except that the TAC film 3 was introduced into the water vapor contact chamber 6 shown in FIG. In the water vapor contact chamber 6, the transport paths 51 and 52 are each divided into three areas in the Y direction, the first wet gas 400a is applied to the TAC film 3 in the first area 51a, and the TAC film 3 in the second area 51b. The second wet gas 400b was applied to the TAC film 3 in the third area 51c, and the third wet gas 400c was applied to the TAC film 3. Thereafter, the retardation Re and Rth of the TAC film 3 in each of the areas 52a to 52c were measured. Then, based on the measured values of retardation Re and Rth of the TAC film 3 in each of the areas 52a to 52c, the temperature distribution of the atmosphere near the transport path 51 is 2 ° C., and the humidity distribution of the atmosphere near the transport path 51 is 5 Water vapor contact treatment was performed by adjusting the temperature Ta1 to Tc1 or the relative humidity Ha1 to Hc1 of each of the wet gases 400a to 400c to be%.

(Experiment 42)
In the water vapor contact chamber 6, the conveyance paths 51 and 52 are each divided into two areas in the Y direction, the first wet gas is applied to the TAC film in the first area of the conveyance path 51, and the second in the conveyance path 51. The second wet gas was applied to the TAC film in the area, the retardation Re, Rth of the TAC film 3 in each area of the conveyance path 52 was measured, and based on these measured values, the vicinity of the conveyance path 51 was measured. The TAC film is the same as in Experiment 41 except that the temperature or humidity of each wet gas is adjusted so that the temperature distribution of the atmosphere is 5 ° C. and the humidity distribution of the atmosphere near the transport path 51 is 7%. 3 produced an optical film 35.

(Experiment 43)
Similar to Experiment 42, except that the temperature or humidity of each wet gas was adjusted so that the temperature distribution in the atmosphere near the transport path 51 was 4 ° C. and the humidity distribution in the atmosphere near the transport path 51 was 10%. Thus, an optical film 35 was produced from the TAC film 3.

  In the steam contact treatment in Experiments 1 and 2, the temperature distribution and humidity distribution in the atmosphere near the conveyance path were measured. In Experiment 1, the temperature distribution was 5 ° C. and the humidity distribution was 15%. In Experiment 2, the temperature distribution was 6 ° C. and the humidity distribution was 9%.

(Evaluation of variation in optical characteristics)
Ten sample films were equally cut out in the Y direction from each optical film obtained in Experiments 1-2, 41-43, and the in-plane retardation Re of each sample film was measured. Then, the difference ReX (= | Re _M −Re _AV |) of the measured value Re _{M of} the in-plane retardation Re and the average value Re _AV of these measured values was calculated. Using this ReX as an index, the presence / absence of in-plane retardation Re was evaluated based on the following criteria.
A: ReX is within 1.0 nm.
○: ReX is larger than 1.0 nm and within 2.0 nm.
X: ReX is larger than 2.0 nm.

  The evaluation of variation in optical characteristics was “、” in Experiment 41, “◯” in Experiments 42 to 43, and “X” in Experiments 1 and 2.

  From the above, it was found that according to the present invention, an optical film having uniform optical properties can be produced.

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 top view which shows the outline | summary of a water vapor contact chamber. It is a top view which shows the outline | summary of an air supply head. It is sectional drawing 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 water vapor contact chamber 41 contact area 42 measurement area 51, 52 transport path 66 air supply head 75 film measuring machine 78 wet gas supply machine 80 film manufacturing equipment 400a to 400c first wet gas 3rd wet gas

Claims (7)

A film transport section for transporting a polymer film subjected to stretching treatment;
Of the polymer film being transported by the film transport unit, a first steam contact portion that supplies first steam to a central portion in a direction orthogonal to the transport direction;
Of the polymer film being transported by the film transport unit, a second steam contact portion for supplying the second steam to both ends in a direction orthogonal to the transport direction;
Based on the property distribution in the direction orthogonal to the transport direction of the polymer film supplied with the first water vapor or the second water vapor, the supply condition of at least one of the first water vapor and the second water vapor is changed. A device for adjusting a property of a polymer film, comprising: a water vapor supply condition changing unit. Conveying the polymer film that has been stretched,
Supplying water vapor to the polymer film;
The property adjustment of the polymer film, wherein the water vapor supply condition is changed in the direction orthogonal to the transport direction so that the temperature and humidity distribution in the vicinity of the polymer film in the direction orthogonal to the transport direction is constant Method.   The property adjustment method for a polymer film according to claim 2, wherein the water vapor is individually supplied to a central portion and both end portions in a direction orthogonal to the transport direction of the polymer film.   Measure the property distribution of the polymer film in a direction orthogonal to the transport direction, change the water vapor supply condition based on the property distribution, and make the temperature and humidity distribution in the direction orthogonal to the transport direction constant. The method for adjusting the properties of a polymer film according to claim 2 or 3.   The temperature distribution in the vicinity of the polymer film in the direction orthogonal to the transport direction is within 5 ° C., and the humidity distribution in the vicinity of the polymer film in the direction orthogonal to the transport direction is within 10%. The method for adjusting the properties of a polymer film according to any one of claims 2 to 4.   6. The property adjusting method for a polymer film according to claim 2, 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 using the method for adjusting properties of a polymer film according to any one of claims 2 to 6.

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