JP2006069184A - Manufacturing method and manufacturing device of polymer film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent a film from a dispersion of a thickness of the film by suppressing a pressure fluctuation inside of a pressure reducing chamber. <P>SOLUTION: The vicinity part of an effluent part 51a of a dope formed from a casting die 36 to a band 38 is depressurized by a first and second pressure reducing chambers 61 and 62. Regarding to the inside pressure of the second pressure reducing chamber 62, ¾Pv¾≤1.5¾K¾ (a proviso K=(t×¾P<SB>0</SB>¾)<SP>1/2</SP>/100, P<SB>0</SB>(Pa) is a set pressure value, Pv(Pa) is a difference between a pressure observed value and P<SB>0</SB>) is set. A tube 67 has an inside diameter of 70-700 mm, a length of ≤30 mm and a number of bends of ≤15. The tube 67 provides with a first and second expanding type noise eliminators 71, 72 and a resonance type noise eliminator 73 as a vibration damping means, a ratio of a cross section of a cavity part of the first expanding type noise eliminator 71 and a hollow part cross section of the tube 67 is made to be 5-500. Thus a fluctuation of the inside air pressure of the second pressure reducing chamber 62 and the tube 67 is suppressed and a shape of the effluent part 51a described above can be stabilized, therefore a film 52 without thickness fluctuation can be provided. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method and equipment for producing a polymer film, and more particularly to a method and equipment for producing a polymer film for optical use.

  Many polymer films used in the field of optoelectronics are manufactured by a solution casting method. The polymer film produced by the solution casting method is superior in optical isotropy and thickness uniformity compared to the film obtained by the melt extrusion method, and has a low content of foreign matter, for example, a polarizing plate protective film, It is used as a retardation film, a transparent conductive film and the like. Among them, the cellulose acylate film is one of the widely used because it has transparency, moderate moisture permeability, high mechanical strength, and low dimensional stability with respect to humidity and temperature. It is. In the solution casting method, a polymer such as cellulose acylate and various additives are doped with a solvent, and then the dope is cast from a die to a casting support, and the casting film is peeled off when it has self-supporting properties. Then, this is dried in a drying step to form a film. The casting support is a metal drum or band that continuously rotates.

  Further, in recent years, the development of the optoelectronics field as described above is remarkable, and there is a strong demand for high functionality and multi-functionality for a polymer film as one of the materials. In order to respond to this, it is essential to make the polymer film thinner. In the solution casting method, a decompression chamber is provided in the vicinity of the dope from the die to the casting support, and the back surface of the dope, that is, the upstream side in the running direction of the casting support, is decompressed to reduce the thickness of the polymer film. In many cases. Also in the melt film forming method, in order to reduce the film thickness, the melt polymer extruded from the die may be similarly decompressed to produce a film.

  However, the thinner the film is, the more difficult it is to manufacture. In particular, it is very difficult to manufacture the film so that the thickness is uniform. For example, when the dope coming out of the casting die is decompressed from the back side by the decompression chamber, there is a problem that the thickness of the film varies with the pressure variation inside the decompression chamber. The thickness unevenness that occurs in this way often appears periodically in the longitudinal direction of the film. In particular, when the film thickness is very thin such as 100 μm or less, it becomes a fatal defect for the product. And in order to reduce this thickness nonuniformity, measures, such as diluting a casting dope or reducing the drying speed of the film peeled from the casting support body, aiming at uniform thickness, may be taken. However, although the thickness unevenness can be reduced by such a method, it cannot be completely eliminated, and since each method is a method in which the drying time is prolonged, it leads to a decrease in manufacturing efficiency and an increase in manufacturing cost. There's a problem.

  Therefore, in the solution film forming method using the decompression chamber, a proposal for eliminating this uneven thickness has been made. For example, each of 0 to 0.3 from the both ends in the width direction of the decompression chamber with respect to the entire width. A method has been proposed in which an opening of a suction pipe for decompression is arranged at a position in the double range, and the dope is pushed out from the die while the pressure in the vicinity of the back of the extrusion part of the extrusion die is sucked and decompressed ( For example, see Patent Document 1). The method of Patent Document 1 is to suppress wavy unevenness of the film by optimizing the structure of the decompression chamber.

Further, in the film manufacturing method in which the resin film discharged from the slit-shaped base is brought into close contact with the moving cast surface (support surface) and sent to the downstream side along with the movement of the cast surface, the resin film is obtained by two or more suction means. There has been proposed a method of improving the adhesion degree by suppressing the variation of the landing point on the cast surface (see, for example, Patent Document 2).
JP-A-6-155494 (page 2-3, FIG. 1) Japanese Patent Laid-Open No. 10-272637 (page 3-4, FIG. 1)

  However, according to the method of Patent Document 1, the occurrence of a part of the planar failure of the film can be suppressed, but there is no effect on the uneven thickness that periodically occurs in the longitudinal direction of the film. Also, as in Patent Document 2, it is not possible to suppress landing point fluctuations simply by placing a decompression chamber upstream of the landing point. Conversely, due to internal pressure fluctuations such as piping connected to the decompression chamber and the decompression chamber, There is a problem that the landing point fluctuation becomes large.

  This invention is made | formed in view of the said subject, In the manufacturing method of a polymer film, the manufacturing method and equipment of a polymer film which can suppress the thickness nonuniformity which generate | occur | produces periodically in the elongate direction of a polymer film are provided. The purpose is to provide.

In order to achieve the above object, in the present invention, a dope in which a polymer is dissolved in a solvent, or the molten polymer is allowed to flow out of a die onto a traveling support and peeled off from the support, and then dried or cooled. In the method for producing a polymer film having a predetermined thickness t (unit: μm), the upstream side in the running direction of the support with respect to the dope or the molten polymer taken out from the die is decompressed by a decompressor, and the pressure at this decompression When the set value is P ₀ (unit: Pa) and the difference between the actually measured pressure value when the pressure is reduced and the pressure set value P ₀ is the pressure fluctuation value Pv (unit: Pa), this pressure fluctuation value Pv (unit Pa) satisfies | Pv | ≦ 1.5 | K | (where K = (t × | P ₀ |) ^1/2 / 100).

  The decompressor includes a decompression chamber having a predetermined internal pressure and a pressure controller for controlling the internal pressure of the decompression chamber, and a pipe for connecting the decompression chamber and the pressure controller. The number of bent portions of the tube from the pressure control unit to the decompression chamber is preferably 15 or less, and the length of the tube from the pressure control unit to the decompression chamber is preferably 30 m or less. Moreover, it is preferable that the internal diameter of this pipe | tube is 70 mm or more and 700 mm or less.

  Moreover, it is preferable that the pipe is provided with a vibration attenuating means for attenuating vibration that fluctuates the internal pressure of the decompression chamber. It is preferable to use at least one of an expansion silencer and a resonator type silencer as the vibration damping means, and it is more preferable to use a resonator type silencer and an expansion silencer in combination. When the cross-sectional area of the hollow portion of the tube is S1, and the area of the hollow portion in the cross section perpendicular to the longitudinal direction of the expansion silencer is S2, the value of S2 / S1 is 5 or more and 500 or less. Is preferred.

  Further, the present invention provides a method for producing a polymer film in which a polymer is caused to flow out from a die onto a traveling support, and is peeled off from the support, and then dried or cooled. Flowing out of the die, the pressure of the vicinity of the flowed-out polymer is reduced by a pressure reducer, and the vibration generated in the pressure reducer in operation is damped so that the fluctuation range of the pressure in the vicinity of the polymer during the pressure reduction falls within a predetermined range. The vibration damping means is a silencer provided in the decompressor.

  At this time, it is preferable that the silencer is an expansion silencer. Further, the pressure periodically changing due to the vibration is measured, and the measurement data is frequency-resolved by fast Fourier transform, and a frequency at which the pressure is larger than a predetermined value in the frequency-resolved data is expressed as f. (Unit: Hz), the length L (unit: m) in the longitudinal direction of the expandable silencer is V / 7f ≦ L ≦ V / 2f (where V is the speed of sound in the atmosphere, and its unit Is preferably m / second).

  The present invention further includes a casting apparatus for casting the polymer, and a drying apparatus or cooling apparatus for drying or cooling the cast polymer to form a polymer film. In a polymer film manufacturing facility comprising a support on which the polymer travels and a die for discharging the polymer onto the support, the polymer is discharged from the die in a molten state or dissolved in a solvent, and the polymer outlet of the die A decompressor for decompressing the vicinity is provided, and the decompressor includes a decompression chamber having a predetermined internal pressure and a pressure control unit for controlling the internal pressure of the decompression chamber. The decompression chamber and the pressure control unit And the number of bent parts of the pipe from the pressure control unit to the decompression chamber is 15 or less. It has been.

  The length of the tube from the pressure control unit to the decompression chamber is preferably 30 m or less, and the inner diameter of the tube is preferably 70 mm or more and 700 mm or less. Moreover, it is preferable that the pipe is provided with a vibration attenuating means for attenuating vibration that fluctuates the internal pressure of the decompression chamber.

  Further, the present invention provides a casting apparatus for casting a polymer by allowing the polymer to flow out from a die onto a traveling support, and a drying apparatus for cooling after the cast polymer is peeled off from the support or cooling. In a polymer film manufacturing facility comprising a cooling device, the polymer is discharged from the die in a molten state or dissolved in a solvent, and includes a decompressor for decompressing the vicinity of the polymer that has flowed out of the die. The machine has a decompression chamber disposed near the polymer outlet of the die and a pressure control unit for controlling the internal pressure of the decompression chamber, and connects the decompression chamber and the pressure control unit to form an air flow path. The pipe includes a vibration damping means for attenuating vibration that fluctuates the internal pressure of the decompression chamber. It is.

  In the polymer film manufacturing facility of the present invention, the vibration damping means is an expansion type silencer or a resonator type silencer, or a plurality of silencers as vibration decompression means are provided, and at least one of the silencers Is an expansion-type silencer, and the other silencer is preferably a resonator-type silencer. When the cross-sectional area of the hollow portion of the tube is S1, and the area of the cavity in the cross section perpendicular to the longitudinal direction of the expansion silencer is S2, the value of S2 / S1 is 5 or more and 500 or less. preferable.

  Further, in the polymer film manufacturing facility, the length L (unit: m) in the longitudinal direction of the expandable silencer is V / 7f ≦ L ≦ V / 2f (in accordance with the frequency value f determined in advance). Where V is the speed of sound in the atmosphere, the unit of which is m / second), and the frequency value f is a frequency obtained by fast Fourier transform of the measurement data of the internal pressure, which shows periodic fluctuations due to the vibration. It is preferable that it is any one of the values when the internal pressure shows a value equal to or higher than a predetermined value in the decomposed and frequency-resolved data.

  Furthermore, the said 1st expansion-type silencer whose longitudinal direction length is L1 (unit; m), and the said 2nd expansion-type silencer whose longitudinal direction length is L2 (unit; m). It is preferable that L1 and L2 satisfy L1 = 2n × L2 (where n is a natural number).

  The expansion silencer is preferably provided with a partition member that partitions the interior in a direction intersecting the propagation direction of the vibration, and has a length L (unit: m) in the longitudinal direction of the expansion silencer. The division length LD (unit: m) in the propagation direction of at least one of the divisions formed by the partition member is LD = (1 / m) × L (where m is a natural number of 2 or more). It is more preferable to satisfy. Further, when the section lengths of the first and second sections are respectively LD1 and LD2 (unit: m), it is preferable that LD1 = 2n × LD2 (where n is a natural number). It is preferable that an extension line obtained by extending the center line of one of the two openings of the vibration inlet and outlet of the silencer is the outside of the other opening.

  According to the method for producing a polymer film of the present invention, the pressure fluctuation in the decompression chamber can be suppressed by suppressing the pneumatic vibration in each of the piping and the decompression chamber leading to the decompression chamber. For this reason, the vibration of the outflow part (it may be called a bead) formed by flowing out from the casting die to the casting support can be suppressed. As a result, a good film with no thickness unevenness can be obtained. Moreover, when the obtained film, especially polymer is cellulose acylate, a polarizing plate and a liquid crystal display device excellent in optical properties can be obtained using this.

  FIG. 1 is a schematic view of a solution casting apparatus as an embodiment of the present invention. However, the present invention is not limited to the solution casting apparatus shown in FIG. The solution casting apparatus 10 includes a dope preparation device 11, a casting device 12, a drying device 15 and a winding device 16.

  The dope preparation device 11 includes a stirring tank 21, a stock tank 22, a filter 25, a static mixer 26, first to third pumps P1 to P3, and a flow rate adjustment valve V1. The first and second supply sources 31 and 32 are connected to the first stirring tank 21 of the dope preparation device 11, and the third supply source 33 is connected to a liquid feed line between the filter 25 and the static mixer 26. ing.

  The casting apparatus 12 includes a casting die 36, a backup roller 37, and a band 38. Although a decompression chamber is provided in the vicinity of the casting die 36, it is not shown in FIG. 1 and will be described in detail later using another drawing. The drying device 15 includes a tenter 41 and a roller dryer 42, and the winding device 16 includes a cutter 45 and a winding unit 46. In the solution casting apparatus 10, supporting or transporting rollers 47 are appropriately arranged as necessary, and these rollers 47 support or transport the polymer film 52. In FIG. 1, only a part of the used rollers is illustrated in order to avoid complexity.

  The polymer as the main component of the film 52 is supplied from the first supply source 31 and the liquid serving as the solvent for the dope is supplied from the second supply source 32 to the agitation tank 21 via separate liquid supply paths. However, the supply of raw materials such as a polymer and a solvent may be sent to the stirring tank 21 after being mixed in another container. Moreover, solid content other than a polymer may be added to this liquid mixture. And various additives, such as a ultraviolet absorber and microparticles | fine-particles, are supplied from the 3rd supply source 33 as needed. However, the timing of addition of these various additives is not limited, and may be added in, for example, the stirring tank 21. The polymer and solvent sent from the first and second supply sources 31 and 32 to the agitation tank 21 are mixed in the agitation tank 21 and stirred for a predetermined time, and sent to the stock tank 22 as a mixture by the first pump P1. It is done. In the stock tank 22, the mixture is statically degassed. Thereby, the amount of bubbles in the casting dope 51 can be reduced, and bubbles can be prevented from being mixed into the film 52.

  The mixture is sent to the filtration device 25 by the second pump P2, and foreign matters such as undissolved matter and dust are removed. The amount of the mixture fed from the stock tank 22 to the filtration device 25 is controlled by the valve V1 in consideration of the filtration pressure in the filtration device 25 and the film forming speed. However, the second pump P2 and the valve V1 may be replaced with a metering pump, and the liquid may be fed while controlling the flow rate of the mixture. Subsequently, the mixture, the additive and the like from the third supply source 33 are mixed in-line by the static mixer 26 to become the casting dope 51 and reach the casting die 36.

  The casting dope 51 is cast from the casting die 36 on a band 38 that is supported by the backup roller 37 and continuously runs. The backup roller 37 is provided with drive control means (not shown), and the rotation speed of the backup roller 37 is controlled by the drive control means, and the band is conveyed at a predetermined speed. The cast dope 51 thus cast becomes a cast film on the band, and the cast film becomes self-supporting while running on the band 38. Note that a drum may be used as the casting support instead of the band 38, but the illustration is omitted in this embodiment.

  The cast film having self-supporting properties is peeled off by a roller as a film 52 and further conveyed to a downstream process. The film 52 that has been peeled off is sent to the tenter 41 where it is dried while its width is regulated or stretched. In the tenter 41, a plurality of tenter clips (not shown) travel along a tenter track (not shown) while holding both side ends of the film 52, and the film 52 is conveyed by the travel of the tenter clip. . A pin clip or the like may be used instead of the tenter clip. The tenter clip is automatically controlled to be opened and closed by a controller (not shown), and the holding and releasing of the film 52 are controlled by the opening and closing. The tenter clip holding the film 52 travels inside the tenter 41 and is automatically controlled to release the clip and release the holding of the film 52 when reaching a predetermined holding release point near the exit.

  The film 52 of the tenter 41 is sent to a roller dryer 42 which is a next process by a supporting or conveying roller 47, and is sufficiently dried while being supported or conveyed by a plurality of rollers 42a. The film 52 after being sufficiently dried is cut and removed at both ends by the cutter 45 and wound up by the winding section 46 as a product.

  Next, the casting process in the casting apparatus will be described with reference to FIGS. FIG. 2 is a schematic view showing a main part of the casting apparatus 12, and FIG. 3 is a side view including a partial cross section around the casting die 36 and the band 38. In the following description, the position where the casting dope 51 coming out of the casting die 36 contacts the band 38 is referred to as a casting start position PS. The casting dope 51 from the tip lip portion of the casting die 36 to the casting start position PS is referred to as an outflow portion 51a, and the casting dope 51 in a state of being cast on the band 38 is cast. This is denoted by reference numeral 51b. As shown in FIG. 2, first and second decompression chambers 61 and 62 are installed on the upstream side of the casting die 36 in the traveling direction of the band 38. The first decompression chamber 61 is installed upstream of the second decompression chamber 62 and is larger than the second decompression chamber 62. The second decompression chamber 62 is disposed in the vicinity of the back side of the outflow part 51 a formed from the casting die 36 to the band 38. The first decompression chamber 61 is provided such that a part of the tip of the air suction portion enters between the second decompression chamber 62 and the band 38, and is located at the back of the second decompression chamber 62.

  The second decompression chamber 62 is connected to a decompression control unit 66 including a decompression fan 63 and a controller 64 for controlling the rotational speed of the decompression fan 63. Then, the rotational speed of the decompression fan 63 is controlled so that the pressure in the vicinity of the back surface of the outflow portion 51a can be controlled by the second decompression chamber 62. In FIG. 2, a pipe for connecting the second decompression chamber 62 and the decompression fan 63 to allow air to flow is denoted by reference numeral 67. In this tube 67, first and second expansion silencers 71 and 72 and a resonator type (side branch type) silencer 73 are arranged in series from the decompression fan 63 side. Note that a decompression fan and a controller are connected to the first decompression chamber 61 in the same manner as the second decompression chamber, but are not shown in FIG.

  The first decompression chamber 61 is in a decompressed state by sucking the internal air by a decompression fan (not shown). Further, the second decompression chamber 62 is also decompressed by sucking the air inside by the decompression fan 63. Then, the decompression control unit 66 controls the degree of decompression inside the second decompression chamber 62. In this way, the back side of the outflow portion 51 a is effectively decompressed, and the casting film 51 b is formed on the band 38. However, the present invention is not limited to the form and number of the decompression chambers 61 and 62 as described above.

  In casting, the degree of decompression inside the second decompression chamber 62 is normally set according to at least the type and properties of the casting dope 51, the casting speed, and the target film thickness t (unit: μm). The However, the pressure in the second decompression chamber 62 fluctuates during casting, and this pressure fluctuation is caused by various vibrations generated in the casting apparatus 12. And the thickness accuracy required to express the excellent optical properties as an optical film can be set according to the thickness of the film to be manufactured, and the allowable value of the magnitude of the pressure fluctuation is It has been found by the present inventors that it can be set according to the thickness. Examples of the vibration that causes the pressure fluctuation include a liquid feeding vibration when the casting dope 51 is fed to the casting die 36 by a pump, a rotational vibration of the backup roller 37, an operating vibration of the decompression fan 63, and the like. . If there is such a vibration, the outflow part 51a itself is shaken, and the casting start position PS is changed by this shake. In addition, a member or device close to the second reduced pressure chamber 62 and the second reduced pressure chamber 62 are provided. , And the internal air pressure fluctuates. Such air pressure fluctuations include periodic fluctuations, and in the following description, such periodic fluctuations may be referred to as pneumatic vibration. In addition, as a clearance gap formed between the 2nd decompression chamber 62, there exist between the band 38, between the casting die 36, and the outflow part 51a, for example. In the present embodiment, the vicinity of the outflow part 51a and the casting film 51b is an inert gas atmosphere such as nitrogen. Therefore, for example, the pressure fluctuation and the pneumatic vibration in the second decompression chamber 62 are as follows. Inert gas pressure fluctuations and pressure oscillations.

Here, the pressure setting value inside the second decompression chamber 62 is P ₀ (unit; Pa), and the fluctuation value of the internal pressure during casting (hereinafter referred to as pressure fluctuation value) is Pv (unit; Pa). To do. This pressure fluctuation value Pv is the difference between the actually measured pressure value Pm during casting and the set pressure value P ₀ . A small absolute value | Pv | of the pressure fluctuation value means a value close to the pressure set value P ₀ , and a constant | Pv | means that there is no pressure fluctuation. In the present invention, it is assumed that the pressure fluctuation value Pv satisfies the following expression (1). In the following formula (1), t represents the thickness of the dried film 52, that is, the product film, and is a value when the unit is μm.
| Pv | ≦ 1.5 | K | (where K = (t × | P ₀ |) ^1/2 / 100) (1)

  By using the equation (1), it can be set by the thickness t (μm) of the film to be manufactured, how much the pressure fluctuation value Pv can be suppressed so that it can be suitably used for optical applications. Therefore, conventionally, it is necessary to actually measure the thickness of the film after passing through the roller dryer 42, and to perform condition control in the casting process based on this measurement data, until the conditions are stabilized. The raw material loss was large, but according to the present invention, the allowable range of the pressure fluctuation value in the casting process was set according to the thickness of the film 52 (see FIG. 1) to be manufactured. Therefore, it is preferable to take measures to suppress the pressure fluctuation, so that it is possible to efficiently produce a film having excellent optical characteristics without thickness unevenness, and to suppress the above-mentioned raw material loss until the conditions are stabilized.

  In addition, since the pipe 67 is connected to the second decompression chamber 62, the internal pressure of the pipe 67 is equivalent to the internal pressure of the second decompression chamber 62 in the present invention. Therefore, it is preferable to control the fluctuation of the internal pressure of the pipe 67 so as to satisfy the same condition as the pressure fluctuation value Pv of the second decompression chamber 62. A method for measuring the pressure fluctuation value Pv will be described later.

  If the absolute value | Pv | of the pressure fluctuation value Pv is larger than 1.5 | K |, the outflow portion 51a is too swayed to cause thickness unevenness, which is not suitable. The absolute value | Pv | of the pressure fluctuation value Pv is more preferably 0.5 × | K | or less, and particularly preferably 0.2 × | K | or less. That is, the absolute value | Pv | of the pressure fluctuation value Pv is most preferably set to zero, but in practice it is impossible. Therefore, the smaller the positive value of 1.5 | K | It is preferable that it is close to.

  Next, a method for controlling the absolute value | Pv | of the pressure fluctuation value will be described. In order to set the absolute value | Pv | of the pressure fluctuation value to 1.5 | K | or less, it is effective to set the inner diameter of the tube 67 to 70 mm or more and 700 mm or less, or to set the length of the tube 67 to 30 m or less. It is. Here, the length of the pipe 67 is a length between the second decompression chamber 62 and the decompression fan 63. In the case where another decompression control unit is used in place of the decompression control unit 66 including the decompression fan 63 and the controller 64, the pipe between the used decompression control unit and the second decompression chamber 62 is connected to the above-mentioned. The inner diameter and the length are good. And this pipe | tube 67 has the some bending location (henceforth a bend part) as shown by the code | symbol A of FIG. More preferably, it is 15 or less.

Although the preferable range of the inner diameter of the tube 67 varies depending on the size of the second decompression chamber 62, the pressure set value P _0, etc., the degree of decompression when producing a film with a width of about 1000 to 2000 mm (vs. The above range is effective when the atmospheric pressure value is -10 to -1500 Pa. If the inner diameter of the tube 67 is smaller than 70 mm, the inner diameter becomes too small with respect to the air volume, and the wind speed inside the tube 67 becomes too large, so that vibration may occur inside the tube 67. Further, it is not practical that the inner diameter of the pipe 67 is larger than 700 mm because the scale is too large as an actual process, and even if it is larger than 700 mm, the absolute value | Pv | of the pressure fluctuation value is 1.5. In many cases, it becomes larger than | K |, and depending on the operation control capability of the decompression fan 63 to be used, minute control to respond to a small pressure fluctuation cannot be performed accurately. The inner diameter of the pipe 67 is more preferably 100 mm or more and 500 mm or less.

  Further, by setting the length of the pipe 67 to 30 m or less, the effect of suppressing the occurrence of vibration itself is great, and the pressure control inside the second decompression chamber 62 and the pipe 67 can be performed quickly and precisely. . If the length of the pipe 67 is larger than 30 m, the contact area of the pipe 67 with the external environment increases, so that the probability that various disturbances act on the pipe 67 increases, and this flows out through the second decompression chamber 62. It may be transmitted to the part 51a and uneven thickness may occur. Examples of the disturbance include vibration including generated sound due to the operation of the casting device 12 and various driving means (not shown) provided in the vicinity thereof. Furthermore, if the length of the pipe 67 is larger than 30 m, even if the operation condition of the decompression fan 63 is controlled by the controller 64, the time required until the internal pressure of the second decompression chamber 62 is adjusted by the control becomes longer. There is also a problem that it ends up. The length of the pipe 67 is more preferably 15 m or less.

  In the present invention, by setting the number of bend portions A to 15 or less, the pneumatic vibration in the second decompression chamber 62 and the pipe 67 can be more effectively suppressed. This is a method paying attention to the phenomenon that the air flow is disturbed in the bend portion A as compared with the straight portion, and the probability of occurrence of pneumatic vibration increases as the number of the bend portions A increases. Accordingly, the smaller the number of bend parts A, the more effective the reduction of vibration generation is, and it is more preferably 10 or less, further preferably 5 or less, and particularly preferably 3 or less.

  In this embodiment, the first and second expansion silencers 71 and 72 and the resonator silencer 73 are provided in the tube 67 as vibration damping means for enhancing the effect of suppressing pressure fluctuations including pneumatic vibration. Is provided. Thereby, the vibration which has arisen in the pipe | tube 67 can be damped, and the pneumatic vibration transmitted to the outflow part 51a can be suppressed. Therefore, if the pressure fluctuation value Pv is any value and the internal pressure of the second decompression chamber 62 fluctuates and the position of the flow start point changes, the vibration decompression means is provided in the pipe 67. This has the effect of effectively suppressing pressure fluctuations. As the vibration attenuating means, a silencer is preferable among known ones in terms of ease of mounting operation, availability, and cost performance. In the present invention, the vibration attenuating means means not only those that attenuate the generated vibrations in a strict sense, but also those that absorb vibrations and those that cancel vibrations by reflection or the like. In the following description of the present invention, these functions, that is, the action by the vibration damping means will be referred to as attenuation or suppression.

  As for vibration damping means, even if only one is used, it is effective, but if it is plural as in this embodiment, it is more effective, and all the vibration damping means may be extended type silencers or resonator type silencers. Also good. In addition, it is preferable to use one or more expansion-type silencers in the range where the length of the tube 67 is within 30 m, and it is more preferable to use three or more units. However, the expansion silencer and the resonator-type silencer have the following differences, and the effects are also different.Therefore, either one of them or both are used together. It is advisable to select appropriately based on measurement data. In the present embodiment, as a result of studying measurement data of pressure fluctuations, an expansion silencer and a resonator type silencer are used in combination to comprehensively suppress pressure fluctuations including pneumatic vibration. When the expansion type and the resonator type are used together as in the present embodiment, the mutual positional relationship between them is not limited. For example, the resonance with the first and second expansion type silencers 71 and 72 is resonant. The same effect can be obtained by reversing the position of the silencer 73 or arranging the resonator silencer 73 between the first and second expansion silencers 71 and 72.

  Many expansion-type silencers and resonator-type silencers are commercially available. The expansion-type silencer is a silencer represented by an automobile muffler, characterized by a structure having a change in the cross-sectional area of the tube, and exhibits an effect in a wide frequency range. The resonator-type silencer is characterized by having a vibration resonance structure inside, and exhibits a great effect at a specific frequency.

  Each of the two silencers described above is a kind of silencer called a reactive silencer. A reactive silencer is a type of silencer that reflects sound to the source side using the change in acoustic impedance of the tube. A device having both the expanded structure and the resonator structure is commercially available and can be preferably used in the present invention. In addition to the reactive silencer, there is a silencer called an absorption silencer. This is a silencer that utilizes the effect of absorbing sound energy by a sound absorbing material such as rock wool or glass wool. In the present invention, a certain effect can be obtained even if these are used. However, the absorption silencer has a property that the effect on the low frequency region is generally inferior to that of the reactive silencer. In the present invention, the silencer is not particularly limited, but from the viewpoints of availability and effects such as the frequency region of vibration to be absorbed, among the various silencers, the expansion silencer and the resonator type silencer And are most preferred.

  Here, a cross section taken along line IV-IV of the tube 67 in FIG. 2 is shown in FIG. 4, and a cross section taken along line VV of the first expansion silencer 71 is shown in FIG. 5. In addition, since the same cross section of the 2nd expansion type silencer 73 is the same as that of the 1st expansion type silencer 71, description and illustration of the cross section of the 2nd expansion type silencer 73 are abbreviate | omitted. Then, the cross-sectional area of the hollow portion of the tube 67 in FIG. 4, that is, the area of the area A1 indicated by cross-hatching is S1, and the cross-sectional area of the hollow portion of the first expansion silencer 71 in FIG. Let S2 be the area of the area A2 indicated by. The area S2 is an area in a cross section perpendicular to the longitudinal direction of the first expansion silencer 71. When the cross-sectional area S2 changes in the longitudinal direction in the first expansion silencer 71, the cross-sectional area S2 may be a value at an arbitrary location in the longitudinal direction. In addition, as shown in FIG. 5, the 1st partition member 71c is provided in the inside of the 1st expansion type silencer 71, but this is demonstrated in detail later using another drawing. In the present embodiment, the area ratio S2 / S1, which is a value obtained by dividing the area S2 of the first expansion silencer 71 by the area S1 of the pipe 67, is set to 5 or more and 500 or less. The area ratio S2 / S1 is particularly preferably 20 or more and 300 or less. By setting the area ratio S2 / S1 to 5 or more and 500 or less, it is possible to further improve the effects of damping of pneumatic vibration such as collision vibration attenuation, sound absorption attenuation, phase difference attenuation, and distance attenuation. When the area ratio S2 / S1 is larger than 500, there is a problem that the apparatus becomes too large. On the other hand, when S / S1 is less than 5, the effect of the above-described pneumatic vibration damping becomes small.

  On the other hand, when using a resonator-type silencer as the vibration damping means as in this embodiment, it is preferable to select one that can adjust the length of the silencer in the longitudinal direction, and adjusting the length. As a result, it is possible to suppress the vibration of the problematic frequency according to the type of the pneumatic vibration. Depending on how many pneumatic vibrations have different frequencies, one or more resonator-type silencers are preferably used within a length of 30 m of the pipe 67, and more preferably three or more.

  By the above method, it is possible to suppress a large amount of vibration and control the absolute value | Pv | of the pressure fluctuation inside the first decompression chamber 61 (see FIGS. 2 and 3) to 1.5 | K | or less. However, when the pressure is measured as described above, periodic fluctuations, that is, pneumatic vibrations may still be observed. Therefore, in this embodiment, this periodic pressure fluctuation was analyzed. Specifically, the measurement data of the internal pressure that fluctuates periodically was subjected to frequency decomposition by fast Fourier transform (FFT). This frequency-resolved data is data expressed by a power spectrum by FFT. In this method, in the measured internal pressure measurement data, the vertical axis is the internal pressure and the horizontal axis is time, but in the power spectrum data by FFT, the vertical axis is also the internal pressure and the horizontal axis is the frequency (Hz). . At this time, the data of the internal pressure itself may be directly subjected to the fast Fourier transform, but the data of the pressure fluctuation value Pv or its absolute value | Pv | can also be subjected to the fast Fourier transform. An embodiment using | Pv | data will be described. Then, data indicating that the absolute value | Pv | of the pressure fluctuation value subjected to frequency decomposition shows a peak at a specific frequency is obtained.

  (A), (b), and (c) of FIG. 6 are measurement diagrams showing an outline of the relationship between the absolute value | Pv | of the pressure fluctuation value and the frequency, and the vertical axis indicates the absolute value of the pressure fluctuation value | Pv |, and the horizontal axis indicates the frequency f (unit: Hz). 6A shows data in the case of a conventional manufacturing apparatus and method, and FIG. 6B shows data in the case of applying the method already described of the present invention. FIG. Is data when a method described later is further applied. Both are data when t ≦ 80 μm.

  As can be seen from FIG. 6 (a), in the conventional method, | Pv | is large in the entire frequency region, whereas in FIG. 6 (b), the number of peaks decreases in the entire frequency region, and | Pv overall. It can be seen that | is reduced and that | Pv | is controlled to be approximately 1.5 | K | or less. Therefore, the already described method of the present invention achieves good thickness accuracy, so that the film exhibits good optical properties. However, as shown in FIG. 6B, even with the method of the present invention described above, the frequency at which | Pv | appears as a peak may be confirmed although the intensity is not large. For example, in FIG. 6B, the value of the frequency f is 80 Hz, 60 Hz, 40 Hz, 30 Hz, or the like. Therefore, it can be seen that the pressure fluctuation is generated periodically and that there is a pneumatic vibration.

  Therefore, in order to reduce the peaks of the specific frequencies 80 Hz, 60 Hz, 40 Hz, and 30 Hz, the method described below was used, and data as shown in FIG. 6C could be obtained by this method. In FIG. 6C, the peaks of 80 Hz, 60 Hz, 40 Hz, and 30 Hz seen in FIG. 6B are small and hardly confirmed, and | Pv | is suppressed in all frequency regions. Recognize. Hereinafter, the present invention for suppressing the pneumatic vibration as confirmed in FIG. 6B and obtaining the effect as shown in FIG. 6C will be described in detail.

  In the present invention, as described above, in order to selectively and effectively attenuate the peak of | Pv | appearing at a specific frequency although the number detected is small, the expansion silencer is subjected to the following conditions. It is supposed to be. 7 is a cross-sectional view taken along line VII-VII in FIG. 2, and FIG. 8 is a cross-sectional view of the first expansion silencer 71. The first expansion silencer 71 and the second expansion silencer 72 may be adjusted so that the lengths L1 and L2 are different from each other, but their basic structures are generally the same. As shown in FIG. 7, the first and second expansion silencers 71 and 72 have suction ports 71a and 72a for sucking air from the second decompression chamber 62 side, and for sucking out the sucked air to the outside. Discharge ports 71b and 72b are provided, and first partition members 71c and 72c for partitioning the inside are provided. With respect to the first expansion silencer 71, the suction port 71a and the discharge port 71b are diagonal in the longitudinal section so that when one center line C1, C2 is extended, the extension line does not enter the other. Provided in position. That is, the suction port 71a and the discharge port 71b are provided so that the extension line of the center line C1 does not enter the discharge port 71b and the extension line of the center line C2 does not enter the suction port 71a. This configuration is the same for the second expansion silencer 72.

  By determining the positions of the suction ports 71a and 72ab and the discharge ports 71b and 72b as described above, the probability that the pneumatic vibration can be attenuated by the first and second expansion silencers 71 and 72 is increased. Can do. That is, if the suction ports 71a and 72ab and the discharge ports 71bc and 72b are provided on the same straight line, the vibrations that have entered from the suction ports 71a and 72a pass through as they are and exit from the discharge ports 71bc and 72b. By arranging the suction ports 71a, 72a and the discharge ports 71b, 72b in this manner, as much vibration as possible having different wavelengths can be attenuated by the first and second expansion silencers 71, 72.

  The first partition members 71c and 72c partition the interiors of the first and second expansion silencers 71 and 72 so that a gap is formed, and the gap serves as an air flow path. The first partition members 71c and 72c are provided so as to intersect the longitudinal direction, that is, the propagation path of the air vibration that has entered from the suction ports 71a and 72a. In the present embodiment, the first partition members 71c and 72c are perpendicular to the propagation path. A surface is formed. As a result, the pneumatic vibration that has entered from the suction ports 71a and 72a is reflected by the first partition members 71c and 72c, and the reflected wave and the incoming air vibration wave cancel each other. There is an effect of suppressing the pneumatic vibration transmitted to the part 51a (see FIGS. 2 and 3) and the like.

  Furthermore, as shown in FIG. 8, the first expansion silencer 71 has a structure in which a first member 75 and a second member 76 are fitted together. The first member 75 and the second member 76 slide in the (A) direction, are positioned so that the length L1 in the longitudinal direction becomes a predetermined length, and are fixed by the fixing member 77. In this embodiment, the length L1 of the first expansion silencer 71 is positioned and fixed so as to satisfy V / 7f ≦ L1 ≦ V / 2f. Here, V represents the speed of sound (unit: m / second) in the atmosphere under the casting environment, and f is the frequency at which a peak appears in the data indicating the relationship between | Pv | and its frequency as shown in FIG. Unit: Hz). For example, the peaks in FIG. 6 are 80 Hz, 60 Hz, 40 Hz, 30 Hz and the like as described above. Thereby, collision vibration attenuation and phase difference attenuation can be performed, so that the pneumatic vibration of a predetermined frequency can be suppressed and the absolute value | Pv | of the pressure fluctuation value can be reduced. Here, since the frequency f is any one of the confirmed peaks, the above range is used to attenuate the vibration having a frequency higher than that generated by resonance of the vibration having the selected frequency. An effect can be obtained. Therefore, by setting L1 as described above, the same effect as that of the resonator type silencer can be obtained.

  If L1 is less than V / 7f, the distance inside the first expansion silencer 71 is too short and there is almost no effect of distance attenuation. On the other hand, if L1 is set to a value larger than V / 2f, the vibration resonates at a low frequency, which may cause a problem that the vibration becomes large due to this resonance. The length L1 is more preferably V / 5f ≦ L1 ≦ V / 3f. In the present embodiment, the length in the longitudinal direction of the expansion silencer is defined as L as described above, but this takes into account the positions of the suction port and the discharge port in the first silencer. This is substantially the length in the direction when vibration enters from the suction port. The concept of the length L will be described in detail later with another expansion silencer used in the present invention shown in another drawing.

  In the present embodiment, the length L2 of the second expansion silencer 72 as well as the first expansion silencer 71 is set to satisfy V / 7f ≦ L2 ≦ V / 2f. This is more preferable when V / 5f ≦ L2 ≦ V / 3f. In the present invention, when a plurality of expansion silencers are used, if any one of the lengths L is set to V / 7f ≦ L ≦ V / 2f, the above effects are obtained. It is particularly preferable to satisfy this condition for all of the expansion silencers as in the embodiment, whereby the pneumatic vibration of a predetermined frequency can be more effectively suppressed.

  Moreover, the effect of suppressing | Pv | at a plurality of frequencies f can be obtained by using a plurality of expansion silencers having different lengths in the longitudinal direction. For example, by setting the length L1 of the first expansion silencer 71 to approximately 2.1 m, the | Pv | peak seen at f = 80 Hz in FIG. 6B is reduced, and the second expansion silencer By setting the length L2 of 72 to 1.5 m, the | Pv | peak seen at f = 60 Hz in FIG. 6B can be reduced.

  When the length L1 of the first expansion silencer 71 and the length L2 of the second expansion silencer 72 are adjusted so that L1 = 2n × L2 (where n is a natural number), the second The first expansion silencer 71 can suppress vibration having a frequency 2n times the vibration suppressed by the expansion silencer 72. Accordingly, vibration generated by resonance in the second expansion silencer 72 can also be attenuated by the first expansion silencer 71. As described above, when | Pv | peaks appear at a plurality of frequencies, the lengths L are determined by using a plurality of expansion silencers so as to correspond to different frequencies f, thereby suppressing each peak. can do. Furthermore, according to this method, it is possible to deal with vibrations of various frequencies by using only the expansion silencer without using the large resonator silencer silencer.

  Further, in the present embodiment, the first partition member 71c is movably mounted on the slide base 71d as shown in FIG. 8, and moves in the direction indicated by (B) to a predetermined position. Positioned. The lengths in the longitudinal direction of the first and second sections D1, D2 formed by being partitioned by the first partition member 71c are defined as a first section length LD1 and a second section length LD2, respectively. The position of the first partition member 71c is positioned and fixed so as to satisfy at least one of LD1 ≦ (1 / m) × L1 and LD2 ≦ (1 / m) × L2. Here, m represents a natural number of 2 or more, V represents the speed of sound (unit: m / sec) in the atmosphere under the casting environment, and f represents the pressure fluctuation data as shown in FIG. Is the frequency (unit: Hz) of an arbitrary peak among the peaks confirmed when expressed as power spectrum data. Thereby, vibration energy of a predetermined frequency can be suppressed by changing to thermal energy, and | Pv | can be reduced. Here, since the frequency f is any one of the confirmed peaks, the above range is used to attenuate the vibration having a frequency higher than that generated by resonance of the vibration having the selected frequency. An effect can be obtained.

  By setting the position of the first partition member 71c as described above, the vibration is also reduced at a frequency (1 / m) times the vibration suppression frequency f by the setting of the length L1 of the first expansion silencer 71. Can be suppressed. For example, when the vibration of f = 80 Hz is suppressed by setting L1 to a predetermined value as described above, and at least one of LD1 and LD2 is (1/2) × L1 , The peak of | Pv | at f = 40 Hz can be suppressed. In this example, the relationship between the suppression effect of the 80 Hz peak and the suppression effect of the 40 Hz peak can be adjusted by changing the area of the first partition member 71c. Specifically, the area of the first partition member 71c is made smaller when it is desired to suppress the peak at 80 Hz more than 40 Hz, and the peak of the first partition member 71c is suppressed when the peak at 40 Hz is more preferably suppressed than 80 Hz. The area should be large.

  If an extended silencer that cannot change the length L is used, instead of changing the length L, a partition formed by the partition member provided with the partition member as described above is provided in the silencer. The length LS is preferably set to V / 7f ≦ LD ≦ V / 2f. When this method is to be applied in the present embodiment, the section lengths LD1 and LD2 are V / 5f ≦ LD1 ≦ V / 3f. More preferably, V / 5f ≦ LD2 ≦ V / 3f.

  In the present embodiment, the section length of the second expansion silencer 72 is set similarly to the first expansion silencer 71. For example, by setting L2 to a predetermined length, f When | Pv | peak at 60 Hz is attenuated and one partition member is provided and at least one of the partition lengths LD is (1/2) × L2, | Pv at f = 30 Hz The peak of | can be attenuated.

  In the present embodiment, the first and second section lengths LD1 and LD2 of the first expansion silencer 71 are adjusted so that LD1 = 2n × LD2 (where n is a natural number). In some cases. By this method, vibrations having a frequency 2n times the vibration attenuated in the second section D2 can be attenuated in the first section D1. Thereby, the vibration generated by resonating in the second section D2 can also be attenuated in the first section D1.

  FIG. 9 is a cross-sectional view of a third expansion silencer 81 used in place of the first expansion silencer in the above embodiment. Similar to the first and second expansion silencers 71 and 72, the third expansion silencer 81 has a first member 85 and a second member 86 that slide in the (A) direction. Thus, the length L3 in the longitudinal direction is set. In addition, first and second partition members 81c and 81e are movably mounted on slide bases 81d and 81f, respectively. By these partition members 81c and 81e, three sections D1 to D3 are formed inside. In the third extended silencer 81, the first to third division lengths LD1 to LD3 are adjusted to be LD1 = 2n × LD2 and LD1 = 2n × LD3 (where n is a natural number). .

  When peaks of the pressure fluctuation value Pv appear at a plurality of frequencies, as shown in FIG. 9, a plurality of partition plates are provided to form three or more sections, each corresponding to a different frequency f. Each peak can be suppressed by determining the partition length LS.

  FIGS. 10 and 11 show still another embodiment of the present invention, and are sectional views of other expansion silencers that can be used in place of the first to third expansion expansion silencers. . However, in these FIG. 10 and FIG. 11, detailed illustration is omitted in order to avoid the complexity of the drawings. A fourth expansion silencer 91 shown in FIG. 10 includes a suction port 91a and a discharge port 91b in a direction perpendicular to the longitudinal direction. In this case, the length L4 is not the length in the longitudinal direction, but the length in the propagation direction of the vibration from the suction port 91a as described above. Further, the fifth expansion silencer 95 shown in FIG. 11 is provided at the same position as the first to third expansion silencers with respect to the suction port 95a and the discharge port 95b. The positional relationship with the second partition member 95e is different from the first to third expansion silencers. That is, the first partition member 95c and the second partition member 95e are both partitioned so as to form a plurality of sections in the longitudinal direction, but their attachment positions are surfaces facing each other. Even when the fourth and fifth expansion silencers are used, the same effects as those of the first to third expansion silencers can be obtained.

  Further, in the film production by the solution casting method as in the present embodiment, the degree of decompression in the second decompression chamber 62 or the pipe 67 is -10 Pa to -2000 Pa when the atmospheric pressure is set to the reference value zero. It is preferable to do. In particular, as the thickness of the film to be manufactured is thinner, it is preferable to increase the degree of vacuum as much as possible within the above range.

  As described above, according to the present invention, it is possible to suppress pneumatic vibration and pressure fluctuations in the second decompression chamber 62 and the pipe 67. Here, measurement of pressure fluctuation will be described. As already described, in the present embodiment, first, the air pressure inside the second decompression chamber 62 is measured with a commercially available pressure gauge. Next, pressure fluctuations are analyzed by subjecting this measurement result to fast Fourier transform (FFT) and frequency decomposition. In this embodiment, Special Transducer manufactured by ST Laboratories was used as a pressure gauge, and MULTI CHANNEL DATASTATION DS-9110 manufactured by ONO SOKKI was used for analysis of pressure fluctuation data, that is, FFT processing. However, in the present invention, the method for measuring pressure fluctuation is not limited to the above method, and may be obtained by a known pressure fluctuation analyzing means. According to the present invention, the absolute value | Pv | of the pressure fluctuation value is small in the entire frequency region, and in particular, in the frequency region of approximately 30 to 50 Hz, | Pv |

  In this embodiment, since it has been confirmed in advance that most of the pressure reducing effect on the outflow portion 51a (see FIGS. 2 and 3) is due to the second pressure reducing chamber, the control object of the internal pneumatic vibration is selected. Although only the second decompression chamber is used, the effect is further improved when the first decompression chamber is controlled. For example, in order to set the absolute value | Pv | of the fluctuation value Pv (unit; Pa) of the internal pressure of the first decompression chamber 61 to 1.5 | K | or less, the first decompression chamber and its decompression fan are connected. It is preferable that the inner diameter of the pipe is 70 mm or more and 700 mm or less, the bend portion of the pipe is 15 or less, the length of the pipe is 30 m or less, and the pipe is equipped with a silencer. Furthermore, when only one decompression chamber is installed, it is preferable to control the pneumatic vibration for each unit, as in the case of the second decompression chamber of the present embodiment. Thus, although the present invention does not depend on the number of decompression chambers to be installed, it is preferable to control pneumatic vibration at least for the decompression chambers installed at positions closest to the outflow membrane.

  In the production method of the present invention, as the polymer component, cellulose acylate is preferable, and cellulose acetate is particularly preferable. Even if it is a polymer other than cellulose acylate, it can be applied to solution film formation in the present invention as long as the polymer and its precursor can be doped with a solvent and solution film formation is possible. Polymers capable of forming films by melt extrusion of are also applied. For example, polyvinyl alcohol, modified polyvinyl alcohol, polyacrylate, polymethacrylate, polyethylene terephthalate (PET), polybutylene terephthalate (PBT), chlorinated polyether, polyacetal, polyetheretherketone (PEEK), polyethersulfone (PES), polyimide (PI), polyamide (PA), polyamideimide (PAI), polyphenylene oxide (PPO), polyphenylenesulfone, polysulfone, polyarylate, polycarbonate (PC), polyethylene (PE), polypropylene (PP), polystyrene (PS), polyvinyl chloride (PVC), etc. can be illustrated. Furthermore, the above-mentioned various polymers can be used in the present invention, either individually or in combination. Further, the present invention is not limited to the form such as the shape of the polymer to be doped or melted, and may be, for example, a powder or a pellet.

  In this invention, when manufacturing a film by solution casting, the solvent used for dope is not limited, Well-known various solvents can be used. For example, in addition to halogen-containing organic compounds such as dichloromethane and dichloromethylene, alcohols such as methyl alcohol, ethyl alcohol, and n-butyl alcohol, various ester compounds such as methyl acetate and ethyl acetate, non-chlorine organic compounds such as acetone, Water can be used.

  As described above, the present invention can be applied not only to solution casting but also to melt casting. In other words, when extruding the molten polymer as an outflow part (extruding part) from a known melt extrusion die, in order to reduce the vibration of the outflow part, etc. It is effective to make the conditions similar to the above. In the case of melt film formation, the drying device 15 in the solution film formation facility shown in FIG. 1 is replaced with a cooling device, and the polymer extruded into a film is cooled under predetermined cooling conditions. This cooling may be natural cooling. And after cooling or after cooling, the film may be stretched in a predetermined direction by a stretching machine or the like.

  Furthermore, the polymer film obtained by the present invention can be favorably used as a polarizing plate protective film. A polarizing plate is obtained by bonding together the polymer film obtained by said manufacturing method as a protective film on both surfaces of the polarizing film produced with the polyvinyl alcohol (PVA) type film. The polarizing film is obtained by dyeing a polyvinyl alcohol-based film. As the dyeing method, a gas phase adsorption method and a liquid phase adsorption method are generally used, and both can be applied. Dyeing was performed by phase adsorption.

  For dyeing by liquid phase adsorption, iodine is used here, but the present invention is not limited to this. The polyvinyl alcohol film was immersed in an iodine / potassium iodide (KI) aqueous solution with an immersion time of 30 seconds to 5000 seconds. The aqueous solution at this time preferably has an iodine concentration of 0.1 g / liter to 20 g / liter and a potassium iodide concentration of 1 g / liter to 100 g / liter. Moreover, it is preferable that the temperature of the aqueous solution at the time of immersion is set to the range of 5 degreeC or more and 50 degrees C or less.

  The liquid phase adsorption method is not limited to the above immersion method, and a known method such as a method of applying iodine or other dye solution to a polyvinyl alcohol film or a method of spraying may be applied. Dyeing may be performed before or after the polyvinyl alcohol film is stretched, but the polyvinyl alcohol film is appropriately swelled and easily stretched by being dyed, so that the stretching step It is particularly preferable to provide a dyeing step before the step.

  It is also preferable to dye with a dichroic dye instead of iodine. Examples of dichroic dyes include dye compounds such as azo dyes, stilbene dyes, pyrazolone dyes, triphenylmethane dyes, quinoline dyes, oxazine dyes, thiazine dyes, anthraquinone dyes. it can. Water-soluble dye compounds are most preferable. Further, it is preferable that a hydrophilic functional group such as a sulfonic acid group, an amino group, or a hydroxyl group is introduced into the molecule of these dichroic dyes.

  In the production process of a polarizing film by stretching a dyed polyvinyl alcohol film, a compound that crosslinks polyvinyl alcohol is used. Specifically, a polyvinyl alcohol film is immersed in a crosslinking agent solution in the pre-stretching step or the stretching step to contain a crosslinking agent. It may be applied instead of dipping. The polyvinyl alcohol film is sufficiently hardened by the inclusion of the crosslinking agent, and as a result, appropriate orientation is imparted. In addition, as a crosslinking agent of polyvinyl alcohol, boric acids are most preferable, but are not limited thereto.

  As the adhesive between the obtained polarizing film and the polymer film according to the present invention, various known adhesives that can be used for bonding the polarizing film and the protective film are used. Among these, an aqueous solution of a polyvinyl alcohol polymer or a boron compound containing a modified polyvinyl alcohol having an acetoacetyl group, a sulfonic acid group, a carboxyl group, an oxyalkylene group or the like is preferable. This adhesive is preferably applied so that the thickness after drying is 0.01 μm or more and 10 μm or less, and more preferably 0.05 μm or more and 5 μm or less. Furthermore, an antireflection layer, an antiglare layer, a slippage imparting layer, an easy adhesion layer, and the like can be imparted to the surface of the polymer film layer imparted to the polyvinyl alcohol layer as a protective film.

  Furthermore, an optical compensation sheet can be pasted on the polymer film obtained by the present invention, particularly a cellulose triacetate film, and used as an optical compensation film. An antireflection film provided with an antireflection layer on the polarizing plate is obtained, and this is used as one side of the surface protective film, and twisted nematic (TN), super twisted nematic (STN), vertical alignment (VA), impression A transmissive, reflective, or transflective liquid crystal display device in a mode such as in-switching (IPS) or optically compensated bend cell (OCB) is obtained. Further, an optical compensation film such as a viewing angle widening film for improving the viewing angle of the liquid crystal display device, a retardation plate, and the like can be used in combination. When used in a transmissive or transflective liquid crystal display device, it is used in combination with a commercially available brightness enhancement film (a polarized light separating film having a polarization selective layer, such as D-BEF manufactured by Sumitomo 3M Co., Ltd.). In addition, a display device with higher visibility can be obtained.

  EXAMPLES Hereinafter, although an Example is shown and this invention is demonstrated concretely, this invention is not limited to this.

The solid content of the following blending ratio was mixed with a solvent having a weight ratio of dichloromethane: methanol of 92: 8 and left to stand for deaeration. Then, the solid content was sent to the filter 25 by the pump P2, filtered, and cast dope 51. It was. The solid content concentration of the casting dope 51 was 19.0% by weight.
(Solid content)
・ 100 parts by weight of cellulose triacetate ・ 7 parts by weight of triphenyl phosphate ・ 5 parts by weight of biphenyl diphenyl phosphate

  The casting dope 51 was cast from the casting die 36. The conveyance speed of the band 38 is 55 m / min. The casting was performed while controlling the degree of decompression in the second decompression chamber 62. The tube 67 has an inner diameter of 100 mm, a length of 12 m, and the number of bend portions A is eight. Further, as the first expansion silencer 71, one having S2 / S1 of 30 was used, and as the second expansion silencer 72, one having S2 / S1 of 50 was used. Further, neither the first expansion silencer 71 nor the second expansion silencer 72 is provided with a partition member, the former length L1 is 3.5 m, and the latter length L2 is 2.5 m. . Furthermore, a resonator type silencer 73 was also used as the vibration damping means. After the cast film was peeled off, the film was dried and wound up to obtain a film 52 having a thickness of 80 μm.

  The conditions are adjusted so that | Pv | becomes each value as in Examples 1-1 to 1-3 shown in Table 1, and in each case, the thickness unevenness generated with a periodicity of 3 Hz or more is 0.3%. Evaluation was made with ◎ when less than%, ○ when less than 0.8%, and x when 1.5% or more. The results are shown in Table 1. The set pressure reduction degree of Table 1 has shown the value with respect to atmospheric pressure. In addition, the thickness of the film 52 was measured using FILM THICKNESS TESTER KG601 manufactured by ANRITSU.

  It implemented similarly to Example 1 except having set the thickness of the film 52 obtained by film forming to 60 micrometers, and was set as Examples 2-1 to 1-3. The results are shown in Table 1 together with Example 1.

  It implemented similarly to Example 1 except having set the thickness of the film 52 obtained by film forming to 40 micrometers, and was set as Examples 3-1 to 1-3. The results are shown in Table 1 together with Examples 1 and 2.

According to the results in Table 1, when | Pv | is 1.5 | K | or less (however, | K | = (t × | P ₀ |) ^1/2 / 100), there is almost no thickness unevenness and a good film When | Pv | is 0.5 | K | or less, it can be seen that a very good film without thickness unevenness can be obtained.

An average of absolute values | Pv | of pressure fluctuation values Pv by changing the set pressure reduction degree of the second pressure reduction chamber 62 to −100 Pa with respect to atmospheric pressure and changing the inner diameter of the pipe 67 as in Examples 4-1 to 3 in Table 2. The value was determined in the same manner as in Example 1. When the air pressure fluctuation in the second decompression chamber 62 is | Pv | is 0.5 | K | or less (where | K | = (t × | P ₀ |) ^1/2 / 100), Table 2 shows the results when │ is less than or equal to 1.5 | K | and ◯, and when | Pv | is greater than 1.5 | K |

  According to the results in Table 2, it can be seen that when the inner diameter of the tube 67 is 50 mm, the air pressure fluctuation is too large, and when the inner diameter of the tube 67 is 80 mm, the air pressure fluctuation is suppressed, which is good. Further, it can be seen that when the inner diameter of the tube 67 is 100 mm, the air pressure fluctuation is greatly suppressed.

The set decompression degree of the second decompression chamber 62 is −100 Pa with respect to the atmospheric pressure, the inner diameter of the pipe 67 is 80 mm, the length of the pipe 67 is 15 m, and the number of the bend portions A is as shown in Example 5-1 in Table 3. The average value of the absolute values | Pv | of the pressure fluctuation values Pv was determined in the same manner as in Example 1. In the second decompression chamber 62, | Pv | is 0.5 | K | or less (provided that | K | = (t × | P ₀ |) ^1/2 / 100). Table 3 shows the results when .smallcircle..vertline..vertline.K.vertline. Is equal to or lower than .vertline.K.vertline.

  According to the results in Table 3, it can be seen that when the bend number A is 20 or more, the air pressure fluctuation is excessively large, which is not preferable, and when the bend number A is 15, the air pressure fluctuation is suppressed and good. Further, it can be seen that when the bend number A is 8, the air pressure fluctuation is extremely suppressed, which is very good.

The set decompression degree of the second decompression chamber 62 is −100 Pa in relation to atmospheric pressure, the inner diameter of the pipe 67 is 80 mm, the number of the bend portions A is 10, and the length of the pipe 67 is the embodiment 5-1 in Table 4. The average value of the absolute value | Pv | of the pressure fluctuation value Pv was determined in the same manner as in Example 1. When the air pressure fluctuation in the second decompression chamber 62 is | Pv | is 0.5 | K | or less (where | K | = (t × | P ₀ |) ^1/2 / 100), Table 4 shows the results when │ is less than or equal to 1.5 | K | and ◯ when │Pv│ is greater than 1.5│K│.

  According to the results in Table 4, it can be seen that if the length of the pipe 67 is 50 m, the air pressure fluctuation becomes too large, which is not preferable, and if it is 25 m, the air pressure fluctuation is suppressed and good. Further, it can be seen that when the length of the pipe 67 is 10 m, the air pressure fluctuation is extremely suppressed, which is very good.

The set pressure reduction degree of the second decompression chamber 62 is −100 Pa in relation to atmospheric pressure, the inner diameter of the pipe 67 is 80 mm, the length of the pipe 67 is 15 m, the number of bend portions A is 15, and the number of expansion silencers installed. The number of resonance-type silencers installed was changed as in Examples 7-1 to 5 in Table 5, and the average value of the absolute values | Pv | of the pressure fluctuation values Pv was obtained in the same manner as in Example 1. When the expansion-type silencer and the resonance-type silencer were used in combination, the former was the upstream side and the latter was the downstream side, regardless of the number of each. Regarding the air pressure fluctuation in the second decompression chamber 62, the case where | Pv | is 0.5 | K | or less (however, | K | = (t × | P ₀ |) ^1/2 / 100) is Table 5 shows the results when Pv | is 1.5 | K | or less and ◯, and when | Pv | is larger than 1.5 | K |

  According to the results in Table 5, it can be seen that when the expansion silencer is not used, the air pressure fluctuation becomes too large, which is not preferable, and when one unit is used, the air pressure fluctuation is suppressed and good. Further, it can be seen that when three units are used, the fluctuation in air pressure is extremely suppressed, which is very good.

The set decompression degree of the second decompression chamber 62 was −100 Pa with respect to atmospheric pressure, the inner diameter of the tube 67 was 80 mm, the length of the tube 67 was 15 m, and the number of the bend portions A was 15. The area ratio S2 / S1 of the expansion silencer that is the first silencer 71 and the pipe 67 is changed as shown in Examples 8-1 to 3-3 in Table 6, and the absolute value | Pv | Was obtained in the same manner as in Example 1. When the air pressure fluctuation in the second decompression chamber 62 is | Pv | is 0.5 | K | or less (where | K | = (t × | P ₀ |) ^1/2 / 100), Table 6 shows the results when │ is less than 1.5 | K | and ◯, and when | Pv | is larger than 1.5 | K |.

  According to the results of Table 6, when the ratio S2 / S1 of the area between the expandable silencer and the pipe 67 is 2, it is not preferable because the air pressure fluctuation is too large, and when it is 6, the air pressure fluctuation is suppressed. It turns out that it is favorable. Further, in the case of 22, it is understood that the air pressure fluctuation is extremely suppressed and is very good.

  In Example 1-2, when the degree of decompression was −200 Pa, the pressure fluctuation inside the second decompression chamber 62 was measured, and the pneumatic vibration data that appeared periodically by the FFT process was obtained. In the analysis data, the maximum value of | Pv | peak was 1.9, and this value appeared at f = 80 Hz. Therefore, instead of the length L1 of the first expansion silencer 71, which was 3.5 m, as shown in Examples 9-1 to 9-5 in Table 7, for each length L1, The value of | Pv | peak at 80 Hz was determined. In the evaluation result column of Table 7, when the value of | Pv | peak at 80 Hz is 0 to 0.25, ◎, when it is larger than 0.25 and 1.0 or less, ○, 1. When it is larger than 0, it is shown as x.

  As a result of Example 9, it can be seen that the effect of suppressing the | Pv | peak that appeared at 80 Hz changes by changing the length L1 of the first expansion silencer 71. In order to suppress the | Pv | peak, it is effective to adjust the length of L1 to a predetermined value in the range of V / 7f to V / 2f according to the frequency at which the peak appears. Recognize.

  In addition, analysis data was obtained for pneumatic vibrations in the second decompression chamber 62 in the same manner as in Example 9 with the set decompression degree changed to −100 Pa (vs. atmospheric pressure). In the analysis data, the maximum value of | Pv | peak was 2.1, and this value appeared at f = 60 Hz. Therefore, the length L1 of the first expansion silencer 71, which was 3.5 m in the ninth embodiment, is changed to each length as shown in the embodiments 10-1 to 10-5 in Table 8, and each length is changed. The value of | Pv | peak at 60 Hz was determined for each L1.

  As a result of Example 10, it can be seen that the effect of suppressing the | Pv | peak appearing at 60 Hz is changed by changing the length L1 of the first expansion silencer 71. In order to suppress the | Pv | peak, it is effective to adjust the length of L1 to a predetermined value in the range of V / 7f to V / 2f according to the frequency at which the peak appears. Recognize.

  For the first expansion silencer 71, a partition member was provided and the number thereof was changed as shown in Table 9. Other conditions were the same as in Example 9-1. These conditions were set to Examples 11-1 to 11-4, and the number of | Pv | peaks that appeared at 80 Hz was measured. The results are shown in Table 9. In Table 9, the description method regarding the evaluation results is the same as in Table 7 and Table 8.

  As a result of Example 11, the peak of 80 Hz can be reduced by setting the predetermined L1, and the | Pv | peak such as 40 Hz can also be reduced by the partition member. As described above, in addition to the | Pv | peak at 80 Hz depending on the presence and the number of partition members in the first expansion silencer 71, the suppression against the | Pv | It turns out that the effect changes.

  When the first expansion silencer 71 is used, Example 12-1 is used, and instead of the first expansion silencer 71, an extension line extending the center line of the suction port 71a enters the discharge port 71b. Example 12-2 was taken when the expansion silencer was used. Other conditions were the same as in Example 9-1. Then, the value of | Pv | peak at 80 Hz in each case was obtained, and the result is shown in Table 10. In Table 10, the description method regarding the evaluation results is the same as in Tables 7 to 9.

  As a result of Example 12, the suppression effect of vibration differs depending on the positional relationship between the suction port and the discharge port, and the suppression effect of vibration is achieved by making the line that extends the center line of the suction port be outside the discharge port. You can see that it increases.

  The cellulose triacetate surface on one side of the antiglare antireflection film was saponified by immersing the antiglare antireflection film in a 2.0 normal 55 ° C. NaOH aqueous solution for 2 minutes. Moreover, the cellulose triacetate film obtained in Example 1-3 was saponified under the same conditions. Using these two films as protective films, iodine was adsorbed onto polyvinyl alcohol and adhered to both surfaces of the polarizer prepared by doing this to prepare a polarizing plate. The obtained polarizing plate was excellent in flatness and good.

  The polarizing plate obtained in Example 13 is a liquid crystal display device of a notebook computer equipped with a transmission type TN liquid crystal display device (D-BEF manufactured by Sumitomo 3M Co., Ltd., which is a polarization separation film having a polarization selection layer), The polarizing plate on the viewing side of the liquid crystal cell was attached. At this time, the antireflection layer side was the outermost surface. The obtained display device had very little display of the background and very high display quality.

It is the schematic of the solution casting apparatus which is embodiment of this invention. It is the schematic which shows the casting apparatus which is embodiment. It is a side view containing the partial cross section of the principal part of a casting apparatus. It is sectional drawing of the pipe | tube connected to a pressure reduction chamber. It is sectional drawing of a 1st expansion type silencer. It is a figure which shows the relationship between | Pv | and frequency in a pneumatic vibration. (A) is a case of a conventional method, (b) is a case where only a part of the present invention is applied, and (c) is a case where the present invention is suitably applied. It is the schematic which shows an expansion type silencer. It is sectional drawing of an expansion type silencer. It is sectional drawing of another expansion-type silencer. It is a section schematic diagram of another expansion type silencer. It is a section schematic diagram of another expansion type silencer.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Solution film-forming equipment 12 Casting device 36 Casting die 38 Band 51 Casting dope 61 1st pressure reduction chamber 66 Pressure reduction control part 67 Pipe | tube 71 1st expansion-type silencer 71a suction port 71b discharge port 71c partitioning member 72 2nd expansion Type silencer 73 Resonator type silencer 81, 91, 95 Extended silencer

Claims (25)

The polymer having a predetermined thickness t (unit: μm) is obtained by allowing the polymer in which the polymer is dissolved in the solvent or the molten polymer to flow out from the die on the traveling support, peel off the support, and dry or cool. In a method for producing a film,
The upstream side in the running direction of the support with respect to the dope or the molten polymer discharged from the die is depressurized by a decompressor,
When the pressure setting value in the pressure reduction is P ₀ (unit; Pa), and the difference between the pressure measurement value when the pressure is reduced and the pressure setting value P ₀ is the pressure fluctuation value Pv (unit: Pa),
The pressure fluctuation value Pv (unit: Pa) is
| Pv | ≦ 1.5 | K | (where K = (t × | P ₀ |) ^1/2 / 100)
The manufacturing method of the polymer film characterized by satisfy | filling. The decompressor includes a decompression chamber having a predetermined internal pressure and a pressure control unit for controlling the internal pressure of the decompression chamber, and a tube for connecting the decompression chamber and the pressure control unit With
The method for producing a polymer film according to claim 1, wherein the number of bent portions of the pipe from the pressure control unit to the decompression chamber is 15 or less.   The length of the said pipe | tube from the said pressure control part to the said pressure reduction chamber shall be 30 m or less, The manufacturing method of the polymer film of Claim 2 characterized by the above-mentioned.   The method for producing a polymer film according to claim 2 or 3, wherein the inner diameter of the tube is 70 mm or more and 700 mm or less.   The method for producing a polymer film according to any one of claims 2 to 4, wherein a vibration attenuating means for attenuating vibration that fluctuates the internal pressure of the decompression chamber is provided in the pipe.   6. The method for producing a polymer film according to claim 5, wherein at least one of an expansion type silencer and a resonator type silencer is used as the vibration damping means.   The method for producing a polymer film according to claim 6, wherein the resonator-type silencer and the expansion-type silencer are used in combination.   The value of S2 / S1 is 5 or more and 500 or less, where S1 is the cross-sectional area of the hollow portion of the tube and S2 is the area of the cavity in the cross section perpendicular to the longitudinal direction of the expansion silencer. A method for producing a polymer film according to claim 6 or 7. In the method for producing a polymer film, the polymer is allowed to flow out from a die on a traveling support, and is peeled off from the support, and then dried or cooled.
The polymer is allowed to flow out of the die in a molten state or dissolved in a solvent, and the pressure of the vicinity of the discharged polymer is reduced by a decompressor,
Attenuating vibration generated in the decompressor in operation by a vibration damping means so that a fluctuation range of pressure in the vicinity of the polymer during the decompression falls within a predetermined range,
The method for producing a polymer film, wherein the vibration damping means is a silencer provided in the decompressor.   The method for producing a polymer film according to claim 9, wherein the silencer is an expansion silencer. The pressure that fluctuates periodically due to the vibration is measured, and the measurement data is frequency-resolved by fast Fourier transform, and the frequency at which the pressure is larger than a predetermined value in the frequency-resolved data is expressed as f ( Unit: Hz)
The length L (unit; m) in the longitudinal direction of the expansion silencer is V / 7f ≦ L ≦ V / 2f (where V is the speed of sound in the atmosphere, and the unit is m / second). The method for producing a polymer film according to claim 10. A casting apparatus for casting the polymer, and a drying apparatus or cooling apparatus for drying or cooling the cast polymer to produce a polymer film;
In a polymer film production facility comprising a support body on which the casting apparatus travels and a die that flows the polymer onto the support body,
The polymer flows out of the die in a molten state or dissolved in a solvent;
A decompressor for decompressing the vicinity of the polymer outlet of the die;
The decompressor includes a decompression chamber having a predetermined internal pressure, a pressure control unit for controlling the internal pressure of the decompression chamber, and a pipe for connecting the decompression chamber and the pressure control unit With
The polymer film manufacturing facility, wherein the number of bent portions of the pipe from the pressure control unit to the decompression chamber is 15 or less.   The length of the said pipe | tube from the said pressure control part to the said pressure reduction chamber shall be 30 m or less, The polymer film manufacturing equipment of Claim 12 characterized by the above-mentioned.   The polymer film manufacturing equipment according to claim 12 or 13, wherein an inner diameter of the tube is 70 mm or more and 700 mm or less.   15. The polymer film manufacturing equipment according to claim 12, wherein the pipe is provided with vibration damping means for damping vibration that fluctuates the internal pressure of the decompression chamber. A casting apparatus for flowing the polymer from a die onto a traveling support and casting the polymer; a drying apparatus for drying the cast polymer after peeling the cast polymer from the support; or a cooling apparatus for cooling. In polymer film production equipment,
The polymer flows out of the die in a molten state or dissolved in a solvent;
A decompressor for decompressing the vicinity of the polymer flowing out of the die;
The decompressor includes a decompression chamber disposed in the vicinity of the polymer outlet of the die and a pressure control unit that controls an internal pressure of the decompression chamber, and connects the decompression chamber and the pressure control unit. With a tube that serves as an air flow path,
A polymer film manufacturing facility, wherein the pipe is provided with a vibration attenuating means for attenuating vibration that fluctuates the internal pressure of the decompression chamber.   The polymer film manufacturing facility according to claim 15 or 16, wherein the vibration damping means is an expansion silencer or a resonator silencer.   A plurality of silencers as the vibration decompression means are provided, at least one of the silencers is an expansion silencer, and the other silencer is a resonator type silencer. The polymer film manufacturing facility as described.   The value of S2 / S1 is 5 or more and 500 or less, where S1 is the cross-sectional area of the hollow portion of the tube and S2 is the area of the cavity in the cross section perpendicular to the longitudinal direction of the expansion silencer. The polymer film manufacturing facility according to claim 17 or 18. The length L (unit: m) in the longitudinal direction of the expansion silencer is V / 7f ≦ L ≦ V / 2f (where V is the speed of sound in the atmosphere) according to the frequency value f obtained in advance. The unit is m / second),
The frequency value f is obtained by frequency-decomposing the measurement data of the internal pressure that shows periodic fluctuations due to the vibration by fast Fourier transform, and the internal pressure shows a value equal to or higher than a predetermined value in the frequency-decomposed data. 20. The polymer film manufacturing facility according to claim 17, wherein the facility is any one of values. The first expansion silencer having the longitudinal length L1 and the second expansion silencer having the longitudinal length L2 (unit; m) are connected in series to form the tube. Provided in
21. The polymer film manufacturing equipment according to claim 17, wherein the L1 and the L2 satisfy L1 = 2n × L2 (where n is a natural number).   The polymer film manufacturing facility according to any one of claims 17 to 21, wherein the expansion silencer includes a partition member that partitions the interior in a direction that intersects a propagation direction of the vibration.   A length L (unit; m) in the longitudinal direction of the expandable silencer, and a section length LD (unit: m) in the propagation direction of at least one section among sections formed by the partition member, The polymer film manufacturing equipment according to claim 22, wherein LD = (1 / m) × L (where m is a natural number of 2 or more). When the section lengths of the first and second sections are respectively LD1 and LD2,
24. The polymer film manufacturing facility according to claim 23, wherein LD1 = 2n × LD2 (where n is a natural number).   An extension line extending from the center line of one of the two openings of the vibration entrance and exit of the expansion silencer is the outside of the other opening. The polymer film manufacturing facility according to any one of claims 22 to 24.

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