JP2008247507A - Web transport device and solution film manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent a film from being swelled when transporting the film by blowing dry air to uplift the film. <P>SOLUTION: A dry duct 48 is provided under a wet film 25a. The dry duct 48 comprises a duct main body 50, a dry air supply section 52, a discharge pipe 53 and a discharge quantity air volume control section 54. The dry air supply section 52 supplies dray air 56 to the duct main body 50. Dry air 56 is blown to the wet film 25a through a blow-out hole 57a. A discharge hole 53a is provided in a position opposite to a nearly central position in the cross direction of the wet film 25a. The discharge hole 53a discharges dry air 56, which flows in a part corresponding to the nearly central part in the cross direction of the wet film 25a, among the dry air 56 flowing under the wet film 25a to the inside of the discharge pipe 53. The dry air 56a is discharged outside through a discharge hole 53b. Discharge quantity of the dry air 56a is controlled by the discharge quantity control section 54. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a web transport apparatus and a solution casting method for transporting a web while carrying both ends of the web and blowing dry air onto the web.

  Polymer films have excellent light transmittance and flexibility, and can be reduced in thickness and are widely used as optical functional films. Among these, the cellulose ester film using cellulose acylate has toughness and low birefringence in addition to the above-described properties. This cellulose ester film is used as a protective film and an optical compensation film for polarizing plates, which are constituent members of liquid crystal display devices (LCDs) whose market has been expanding in recent years, including photographic photosensitive films.

  One method for producing this polymer film is a solution casting method. According to this solution casting method, first, a dope containing a polymer and a solvent is cast from a casting die onto a support to form a casting film. Then, after the cast film becomes self-supporting, the cast film is peeled off from the support as a wet film. Then, the both ends of the wet film are carried and conveyed by the tenter, and the film is dried during the conveyance. And after the both ends of a film are cut | disconnected by the ear-cutting apparatus, a film passes the drying apparatus and is wound up by the winding apparatus.

In a tenter, especially a pin tenter for drying a wet film with a high solvent content, dry air is blown out from a drying duct installed above or below the film, and the film is transported while floating to dry the film. (See Patent Document 1).
No. 2003-260741

  However, when a film is lifted and transported using a dry air duct, the floating force at the center in the width direction increases, and the wet film being transported swells in a convex or concave shape in the width direction. It will be. Further, in recent years, a large-screen liquid crystal display or the like has been desired, and in response to this, there is a demand for widening the film forming equipment. For this reason, with the widening of production equipment, the resulting wet film also becomes wider. Due to this widening, the floating force distribution in the width direction of the wet film in the tenter drying, that is, the static pressure distribution below the wet film becomes larger than the previous one, and the transport of the wet film becomes unstable, or the wet film The quality of the product may be impaired, and a solution has been desired.

  It is an object of the present invention to provide a web transport apparatus and a solution casting method for transporting a web so as not to swell when transported while blowing dry air onto a web such as a continuously manufactured film. To do.

  In order to solve the above-mentioned problems, the present invention provides a web for carrying the web while carrying both sides of the web by a carrying portion and blowing the drying air to the web by a drying air supply unit. The conveying apparatus includes a static pressure distribution uniformizing unit that lowers a static pressure due to the drying air at a central portion in the width direction of the web and uniforms a static pressure distribution in the web width direction.

  The drying air supply unit is a drying duct having a blow-off opening that blows the drying air toward the web, and the static pressure distribution uniformizing unit is located at a position corresponding to a substantially central portion in the width direction of the web. Preferably, the drying duct is provided so as to penetrate the web-facing surface of the drying duct and includes a drying air exhaust unit that exhausts the drying air. It is preferable that the dry air exhaust unit has an exhaust amount control unit that controls an exhaust amount of the dry air.

  The drying air supply unit is a drying duct having a blow-off opening that blows the drying air toward the web, and the static pressure distribution uniformizing unit is located at a position corresponding to a substantially central portion in the width direction of the web. It is preferable that it is comprised from the recessed part or convex part provided in the web opposing surface of a drying duct.

  The drying air supply unit is a drying duct having a blowing opening that blows the drying air toward the web, and the static pressure distribution uniformizing unit controls the amount of drying air blowing in the web width direction by the blowing opening. It is preferable to have an air volume control mechanism.

  The drying air supply unit is a drying duct having a blowing opening that blows the drying air against the web, and the static pressure distribution uniformizing unit has the blowing opening on a surface of the web of the drying duct. , Each extending in the width direction of the web, and provided at a predetermined interval in the web conveyance direction, and between the protrusions and in a direction facing the web It is preferable to have a movable part that can be moved and a shift part that moves the movable part. The movable part is preferably provided with an exhaust hole for exhausting the dry air.

  Preferably, the static pressure distribution uniformizing means suppresses the static pressure distribution in the web width direction within ± 200% of the weight per unit area of the web. The web is peeled off after casting a dope comprising a polymer and a solvent on a support that runs endlessly to give self-supporting property, and the content of the solvent is 130% by mass or more. A cellulose acylate film is preferred. It is preferable that the carrying portion has a plurality of pins that pierce the web and travel endlessly.

  The solution casting method of the present invention comprises a step of casting a dope containing a polymer and a solvent on a support that runs endlessly to form a casting film, and the casting film is peeled off from the support. The process of making the wet film, and the both ends of the wet film are supported by the traveling support part, and the dry air is blown to the wet film by the dry air supply part, and the static pressure distribution is made uniform. The method comprises a step of lowering the static pressure by the drying air at the center in the width direction of the wet film by means, and drying by uniformizing the static pressure distribution in the web width direction.

  ADVANTAGE OF THE INVENTION According to this invention, when conveying a web, blowing dry air and making it float, it can convey, without expanding the center part of a web to convex shape or a concave shape.

  A first embodiment of the present invention will be described. As shown in FIG. 1, the film production facility 10 includes a casting chamber 11, a crossing part 12, a pin tenter 13, a clip tenter 14, ear clip devices 15 a and 15 b, a drying device 16, and a cooling device 17. The winding device 18 is provided.

  In the casting chamber 11, a feed block 22 into which the dope from the dope production facility 20 is fed, a casting drum 23 as a support, a casting die 24 for casting the dope onto the casting drum 23, and casting. A stripping roller 26 for stripping the casting film 25 on the drum 23 as a wet film 25a, a condenser 27 (condenser) for condensing and liquefying the solvent gas evaporated from the casting film 25, and a collecting device for collecting the liquefied solvent 28. Further, a heat transfer medium supply device (not shown) is connected to the casting drum 23, and the surface temperature of the casting drum 23 is set to a desired value by supplying the heat transfer medium into the heat transfer medium supply device. The temperature is adjusted. Further, a temperature adjusting device 30 for adjusting the internal temperature is attached to the casting chamber 11.

  A dope channel is formed inside the feed block 22. By adjusting the arrangement of the flow paths, the casting film 25 having a desired structure can be formed. A decompression chamber 32 is attached to the casting die 24, and the decompression chamber 32 is used for the flow of dope (hereinafter referred to as “bead”) from the discharge port of the casting die 24 to the casting drum 23. The pressure behind is reduced, and the contact of the dope with the casting drum 23 is stabilized. A jacket (not shown) is attached to the decompression chamber 32.

  The casting drum 23 is composed of a stainless steel drum capable of continuous rotation. Further, the surface of the casting drum 23 is polished. As a result, a casting film 25 having excellent flatness is formed on the casting drum 23. A casting drum is used as the support, but the form of the support is not particularly limited. For example, a casting band wound around a pair of rollers and running endlessly may be used as the support. The support preferably has a width of about 1.1 to 2.0 times the casting width of the dope. The material of the support is preferably a material having corrosion resistance and high strength, such as stainless steel.

The shape, material, size and the like of the casting die 24 are not particularly limited, but it is preferable to use a coat hanger type because the casting width of the dope can be kept substantially uniform. Moreover, what has the discharge port about 1.1 to 2.0 times with respect to the casting width of dope is preferable. From the viewpoint of durability, heat resistance, etc., it is preferable to use precipitation hardening type stainless steel, and even if it is immersed in a mixed solution of dichloromethane, methanol and water for 3 months, it does not cause pores at the gas-liquid interface. Those having such corrosion resistance are preferred. Moreover, what has the corrosion resistance equivalent to the product made from SUS316 by the forced corrosion test in electrolyte aqueous solution can be used suitably. From the viewpoint of heat resistance, it is preferable to use one having a thermal expansion coefficient of 2 × 10 ⁻⁵ (° C. ⁻¹ ) or less.

Moreover, it is preferable that a cured film is formed at the tip of the discharge port of the casting die 24 for the purpose of improving wear resistance. The method for forming the cured film is not particularly limited, and examples thereof include ceramic coating, hard chrome plating, and nitriding treatment. When ceramics are used as the cured film, the cured film should be capable of grinding, have a high porosity, be superior in brittleness and corrosion resistance, and have a high degree of adhesion to the casting die. However, it is preferable to satisfy conditions such as low adhesion to the dope. Specific examples include tungsten carbide (WC), Al ₂ O ₃ , TiN, Cr ₂ O _{3 and the} like. Among these, WC is preferably used. The WC coating can be performed by a known thermal spraying method.

  In order to form the casting film 25 having excellent flatness, the dope contact surface of the casting die 24 is preferably smoothed by polishing or the like. Further, it is preferable to attach a suction device (not shown) to the edge portion of the casting die 24 and perform suction while setting the edge suction air volume to 1 to 100 L / min. Thereby, the flow of the wind which becomes a cause which forms an unevenness | corrugation on the surface of a bead can be reduced.

  A large number of rollers 35 are installed in the transfer section 12, and these rollers 35 guide the wet film 25 a peeled off by the casting drum 23 to the pin tenter 13. A blower 40 is provided above the transport path of the wet film 25a. The blower 40 blows dry air on the wet film 25a to promote drying of the wet film 25a.

  As shown in FIG. 2, the pin tenter 13 includes an endless chain 40 that is supported by a rail 39 and circulates endlessly, a pin plate 42 attached to the endless chain 40, and a plurality of pins 43 attached on the pin plate 42. And. When the wet film 25a having passed through the crossing portion 12 enters the pin tenter 13, the pins 43 are inserted into both end portions of the wet film 25a, and the wet film 25a is moved in the longitudinal direction ( 1 and 3 ("X direction"). Further, a shift mechanism 44 is connected to the rail 39, and the shift mechanism 44 moves the rail 39 in the width direction of the wet film 25a ("Y direction" in FIGS. 2 and 3). Thus, the width of the wet film 25a is adjusted according to the drying of the wet film 25a.

  As shown in FIGS. 2 and 3, the pin tenter 13 is provided with a drying duct 48 below the transport path of the wet film 25a. The drying duct 48 includes a duct body 50, a drying air supply unit 52, an exhaust pipe 53, and an exhaust amount control unit 54. On the lower surface 55 of the duct body 50, an intake hole 55 a for taking in the dry air 56 supplied from the dry air supply unit 52 is formed. In addition, a plurality of blowing holes 57a for blowing the drying air 56 are formed on the upper surface 57 of the duct body 50 at a predetermined interval. The volatile content of the wet film 25a in the pin tenter 13, that is, the residual solvent content, is preferably 130% by mass or more.

  The exhaust pipe 53 is provided from the upper surface 57 to the lower surface 55 at the center of the duct body 50 in the width direction, and a plurality of the exhaust pipes 53 are provided at predetermined intervals along the X direction. The exhaust pipe 53 includes exhaust holes 53a and 53b. The exhaust hole 53a is provided on the upper surface 57 of the duct body 50 at a position facing the substantially central portion in the width direction of the wet film 25a. The exhaust hole 53a exhausts the dry air 56a flowing in a portion corresponding to the substantially central portion in the width direction of the wet film 25a out of the dry air 56 flowing below the wet film 25a into the exhaust pipe 53. To do. The exhaust hole 53b is formed in the lower surface 55 of the duct body 50, and the exhaust hole 53b exhausts the dry air 56a to the outside. The exhaust amount control unit 54 controls the exhaust amount of the dry air 56a exhausted from the exhaust hole 53b. Here, in FIG. 3, only a part of the exhaust pipe 53, the exhaust hole 53 a, the drying air 56, 56 a, and the blowout hole 57 a is attached to avoid the complexity of the drawing.

  As described above, by exhausting the drying air 56a through the exhaust hole 53a provided at a position facing the substantially central portion in the width direction of the wet film 25a, the static pressure below the wet film 25a is The static pressure (hereinafter referred to as “central static pressure”) at the portion corresponding to the substantially central portion in the width direction of the wet film 25a where the pressure is high can be reduced. The static pressure distribution below the wet film 25a is −200 of the weight per unit area of the wet film 25a by lowering the static pressure at the center and making the static pressure at the center substantially equal to the static pressure of the other parts. % To + 200%. The reason why the weight per unit area of the wet film 25a is used as a value indicating the static pressure distribution is that it is ideal that the static static pressure required during the floating transportation is the film weight.

  By suppressing the static pressure distribution below the wet film 25a within the above range, the static pressure distribution below the wet film 25a can be made substantially uniform, so that the wet film 25a in the pin tenter 12 swells in a convex shape. There is nothing. Therefore, the quality of the film after manufacture can be ensured.

  The shape of the exhaust hole 53a is not necessarily limited to the rectangular shape shown in FIG. For example, the shape of the exhaust hole 53a may be an ellipse. Further, similarly to the blowout hole 57a, the exhaust hole may be constituted by a round hole or the like, and the round hole or the like may be provided at a predetermined interval at a position facing the substantially central portion in the width direction of the wet film 25a. Moreover, although the shape of the upper surface 57 and the lower surface 55 of the duct main body 50 was made the same, it is not necessary to restrict to this. For example, the area of the upper surface 57 may be larger than the area of the lower surface 55. In this case, the shape of the exhaust pipe 53 is set so that the area of the exhaust hole 53a is larger than the area of the exhaust hole 53b. Further, by providing an area adjusting mechanism for adjusting the opening area of the exhaust hole 53a and appropriately controlling the area adjusting mechanism, the static pressure distribution at the center is lowered and the static pressure distribution below the wet film 25a is substantially uniformized. Also good.

  As shown in FIG. 1, the clip tenter 14 is provided downstream of the pin tenter 13, grips and conveys both end portions (hereinafter referred to as “ear portions”) of the wet film 25a, and performs drying. Thereby, the film 37 is obtained. The ear clip device 15 a is provided between the pin tenter 13 and the clip tenter 14, and cuts the ear portion of the wet film 25 a that has come out of the pin tenter 13. Further, the ear clip device 15 b is provided between the clip tenter 14 and the drying device 16, and cuts the ear portion of the film 37 that has come out of the clip tenter 14. Further, a crusher 65 is connected to the ear-cutting devices 15a and 15b, and the crusher 65 crushes the ear portion into chips. The film 37 whose ears have been cut is sent to the drying device 16. A large number of rollers 67 are provided inside the drying device 16, and the film 37 is dried while being conveyed by the rollers 67. The film 37 exiting the drying device 16 is sent to the cooling device 17 where it is cooled to approximately room temperature.

  The crossing part 12, the pin tenter 13, the clip tenter 14, and the drying device 16 described above are connected to an adsorption / recovery device 69 provided on the outside thereof. The adsorption / recovery device 69 adsorbs and recovers the solvent gas generated in the crossing part 12, the pin tenter 13, the clip tenter 14, and the drying device 16. The solvent recovered by adsorption is reused as a dope raw material.

  The winding device 18 includes a winding roller 70, and the film 37 that has exited the cooling device 17 is wound into a roll by the winding roller 70. Further, the winding device 18 includes a press roller 71, and the press roller 71 controls the tension of the film 37 wound around the winding roller 70.

  Through the above steps, the film 37 having excellent flatness is manufactured stably at high speed. The width of the film 37 after manufacture is preferably 1400 mm or more and 2500 mm or less. In addition, even if it is a case where the width | variety of a film exceeds 2500 mm, the effect of this invention can be acquired. In addition, the thickness of the film 37 after manufacture is preferably 20 μm or more and 100 μm or less, more preferably 20 μm or more and 80 μm or less, and most preferably 30 μm or more and 80 μm or less.

  A second embodiment of the present invention will be described. In the following description, since devices other than the drying duct in the pin tenter are the same as those in the first embodiment, the symbols of these devices are the same as those shown in FIGS. Omitted. As shown in FIGS. 4 and 5, the pin tenter 13 is provided with a drying duct 75 below the conveyance path of the wet film 25a. The drying duct 75 includes a duct body 76 and a drying air supply unit 78 that supplies a drying air 77 to the duct body 76. Further, a concave portion 82 is formed in the upper surface 80 of the duct body 76 along the X direction at a position facing the substantially central portion in the width direction of the wet film 25a. A plurality of blowing holes 82 a for blowing the drying air 77 are formed in the recess 82 at a predetermined interval. Further, a plurality of blowout holes 80a for blowing out the drying air 77 are formed at predetermined intervals on the upper surface 80 of the duct main body 76 other than the recesses 82. In addition, an intake hole 83 a that takes in the dry air 77 from the dry air supply unit 78 is formed in the lower surface 83 of the duct body 76.

  A recess 82 is formed in the upper surface 80 of the duct main body 76 along the X direction, and the blow hole 82a is provided in the recess, so that the distance between the wet film 25a and the blow hole 82a is the same as the wet film 25a and the blow hole 80a. Will be greater than the distance between. Therefore, the space of the part corresponding to the substantially center part of the width direction of the wet film 25a becomes large, and the center part static pressure becomes low among the static pressures below the wet film 25a. Lowering the static pressure at the central portion makes the static pressure at the central portion substantially equal to the static pressure at other portions, and the static pressure distribution below the wet film 25a is -200% of the weight per unit area of the wet film 25a. It is suppressed to + 200% or less. Thereby, since the static pressure distribution below the wet film 25a can be made substantially uniform, the wet film 25a in the pin tenter 13 does not bulge in a convex shape. Therefore, the quality of the film after manufacture can be ensured. In FIG. 5, only a part of the drying air 77 and the blowing holes 80 a and 82 a are denoted by reference numerals in order to avoid complication of the drawing.

  The cross-sectional shape of the recess 82 is not limited to the V shape shown in FIGS. 4 and 5, and may be other shapes such as a substantially semicircular shape and a substantially rectangular shape. In addition, without forming a concave portion at a position facing the substantially central portion in the width direction of the wet film 25a, the static pressure at the central portion can be reduced by appropriately changing the arrangement and shape of the blowing holes at that position instead. It may be lowered. For example, the number of blowout holes provided at a position facing the substantially central portion in the width direction of the wet film 25a may be smaller than the number of blowout holes provided in other portions. Moreover, you may make the opening area of the blowing hole provided in the position facing the substantially center part of the width direction of the wet film 25a smaller than the opening area of the blowing hole provided in the other part. Further, a depth adjusting mechanism for adjusting the depth of the concave portion is provided, and by appropriately controlling this depth adjusting mechanism, the volume of the space corresponding to the substantially central portion in the width direction of the wet film 25a is changed. Also good. The static pressure distribution at the center may be lowered to make the static pressure distribution below the wet film 25a substantially uniform.

  Further, in the second embodiment, the concave portion is provided on the upper surface 80 of the duct body 76, but a convex portion may be provided instead.

  A third embodiment of the present invention will be described. In the following description, since the devices other than the drying duct in the pin tenter are the same as those in the first embodiment, the reference numerals of these devices and the like are the same as those shown in FIGS. To do. As shown in FIGS. 6 and 7, the pin tenter 13 is provided with a drying duct 90 below the conveyance path of the wet film 25a. The drying duct 90 includes a duct body 91 and first and second drying air supply units 92 and 93. The duct body 91 includes a first air blowing unit 94 and a second air blowing unit 95.

  The first air blower 94 includes an intake hole 97 that takes in the dry air 96 from the first dry air supply unit 92, and a blowout hole 98 that blows out the dry air 96. A plurality of blow-out holes 98 are provided at predetermined intervals at positions facing the substantially central portion in the width direction of the wet film 25a. Further, the second air blowing unit 95 includes an intake hole 101 that takes in the dry air 100 from the second dry air supply unit 93 and a blowout hole 102 that blows out the dry air 100. A plurality of blowing holes 102 are provided at predetermined intervals at positions facing portions other than the substantially central portion in the width direction of the wet film 25a. The first dry air supply unit 92 includes an air volume control unit 92a. The air volume control unit 92a controls the first dry air supply unit 92 so that the air volume of the dry air 96 is smaller than the air volume of the dry air 100. Control.

  The air volume control unit may be provided in the second dry air supply unit so that the air volume of the dry air 100 is controlled to be larger than the air volume of the dry air 96. Further, an air volume control unit may be provided in both the first and second dry air supply units, and the air volume of the dry air 96 may be controlled to be smaller than the air volume of the dry air 100. Further, the shape of the blowout hole 102 and the blowout hole 98 may be different and controlled by one drying air supply unit.

  By making the air volume of the dry air 96 blown to the substantially central portion in the width direction of the wet film 25a smaller than the air volume of the dry air 100, the static pressure at the center of the static pressure below the wet film 25a is lowered. By lowering the static pressure at the central portion, the static pressure at the central portion and the static pressure at the other portions are substantially equal, and the static pressure distribution below the wet film 25a is -200 of the weight per unit area of the wet film 25a. % To + 200%. Thereby, since the static pressure distribution below the wet film 25a can be made substantially uniform, the wet film 25a in the pin tenter 13 does not bulge in a convex shape. Therefore, the quality of the wet film 25a after manufacture can be ensured. In FIG. 7, only part of the drying air 96 and 100 and the blowout holes 98 and 102 are denoted by reference numerals in order to prevent the drawing from being complicated.

  A fourth embodiment of the present invention will be described with reference to FIGS. In the following description, since devices other than the drying duct in the pin tenter are the same as those in the first embodiment, the symbols of these devices are the same as those shown in FIGS. Omitted. The pin tenter 13 is provided with a drying duct 110 below the wet film. The drying duct 110 includes a duct body 111 and a drying air supply unit 113 that supplies the drying air 112 to the duct body. A plurality of protrusions 115 are formed on the upper surface of the duct body 111 along the Y direction, and the protrusions 115 are provided at predetermined intervals in the X direction. In addition, a movable plate 116 that is movable in a direction (Z direction) opposite to the wet film 25a is provided between the protrusions 115. The movable plate 116 is moved by the shift unit 118. Further, blow holes 115a through which the drying air 112 is blown out are formed in the protrusion 115 at predetermined intervals. Exhaust holes 116a through which the drying air 112 is exhausted are formed in the movable plate 116 at a predetermined interval. In this embodiment, the movable plate 116 is provided with the exhaust hole 116a. However, the exhaust hole may not be provided.

  By making the upper surface of the drying duct 110 uneven by the projection 115 and the movable plate 116 and moving the movable plate 116 in the Z direction by the shift unit 118, the floating static pressure of the wet film 25a can be adjusted. By adjusting the floating static pressure, the central static pressure can be lowered, and the central static pressure can be made substantially equal to the static pressure in other portions. Thereby, the static pressure distribution below the wet film 25a is suppressed to −200% to + 200% of the weight per unit area of the wet film 25a. Thus, the wet film 25a in the pin tenter 13 does not swell by making the static pressure distribution below the wet film 25a substantially uniform. Therefore, the quality of the film after manufacture can be ensured. In FIG. 8, only a part of the drying air 112, the projecting portion 115, the movable plate 116, the blowout hole 115 a, and the exhaust hole 116 a is attached to avoid the complexity of the drawing.

  In the first to fourth embodiments, the drying duct is installed below the transport path of the wet film 25a. However, instead of or in addition to this, the drying duct is installed upward, and the wet film 25a is viewed from above. Dry air may be blown.

  In the above embodiment, the present invention is applied to the pin tenter. However, the present invention is not limited to this, and the present invention may be applied to the clip tenter. Furthermore, the present invention can be applied not only to a device that transports a film, but also to a web transport device that transports a continuously manufactured web or the like.

  In the above embodiment, the case where a single-layer film is manufactured using one kind of dope has been described. However, the present invention is also effective when a cast film having a multilayer structure is formed. In this case, a known method such as casting a desired number of dopes simultaneously or sequentially may be used, and there is no particular limitation. Also, from the structure of casting die, decompression chamber, support, etc., co-casting, peeling method, stretching, drying conditions of each step, handling method, curling, winding method after flatness correction, solvent recovery method, film The collection method is described in detail in paragraphs [0617] to [0889] of JP-A-2005-104148, and the inventions according to these descriptions can also be applied to the present invention. Further, the performance of the completed film, the degree of curling, the thickness, and the measurement methods thereof are described in paragraphs [1073] to [1087] of JP-A-2005-104148. The invention can also be applied to the present invention.

  It is preferable to perform a surface treatment on at least one surface of the completed film because the degree of adhesion with an optical member such as a polarizing plate can be increased. Examples of the surface treatment include vacuum glow discharge treatment, atmospheric pressure plasma discharge treatment, ultraviolet irradiation treatment, corona discharge treatment, flame treatment, acid treatment, alkali treatment, etc., and at least one of these treatments is performed. Is preferred.

  When a completed film is used as a base and a desired functional layer is provided on both sides or one side thereof, it can be used as various functional films. Examples of the functional layer include an antistatic layer, a cured resin layer, an antireflection layer, an easy adhesion layer, an antiglare layer, and an optical compensation layer. For example, when an antireflection layer is provided, an antireflection film capable of providing high image quality by preventing reflection of light can be obtained. The functional layer and the forming method are described in detail in paragraphs [0890] to [1072] of JP-A-2005-104148, and the inventions related to these descriptions can also be applied to the present invention. it can. As for specific uses of the polymer film, for example, TN type, STN type, VA type, OCB type, reflective type and the like described in paragraphs [1088] to [1265] of JP-A-2005-104148, etc. For use in liquid crystal display devices.

  Next, the raw material of dope manufactured with the dope manufacturing equipment 20 is shown below.

  It is preferable to use cellulose ester as a dope raw material because a highly transparent film can be obtained. Examples of the cellulose ester include lower fatty acid esters of cellulose such as cellulose triacetate, cellulose acetate propionate, and cellulose acylate butyrate. Especially, it is preferable to use a cellulose acylate from the height of transparency, and it is preferable to use a triacetyl cellulose (TAC). The dope used in the above embodiment includes triacetyl cellulose (TAC) as a polymer. Thus, when using TAC, it is preferable that 90 mass% or more of TAC is a particle | grain of 0.1-4 mm.

As said cellulose acylate, in order to obtain a film with higher transparency, it is preferable that the substitution degree of the acyl group to the hydroxyl group of cellulose satisfies all of the following formulas (a) to (c). A and B in the following formula represent the substitution degree of the acyl group with respect to the hydrogen atom in the hydroxyl group of cellulose, specifically, A is the substitution degree of the acetyl group, and B has 3 to 22 carbon atoms. The degree of substitution of the acyl group.
(A) 2.5 ≦ A + B ≦ 3.0
(B) 0 ≦ A ≦ 3.0
(C) 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 esterification of the hydroxyl group of cellulose for each of the 2-position, 3-position and 6-position. The degree of substitution is 1 in the case of 100% esterification.

  The total degree of acylation substitution, that is, the value of 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, the value of 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 a ratio in which the hydrogen of the hydroxyl group at the 2-position in the glucose unit is substituted with an acyl group, and DS3 is a ratio in which the hydrogen of the hydroxyl group at the 3-position in the glucose unit is substituted with an acyl group. DS6 is the ratio in which the hydrogen of the 6-position hydroxyl group is replaced by an acyl group in the glucose unit.

  Only one kind of acyl group may be used for cellulose acylate, or two or more kinds 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. The sum of the degree of substitution of hydroxyl groups at the 2nd, 3rd and 6th positions by acetyl groups is DSA, and the sum of the degree of substitution of the hydroxyl groups at the 2nd, 3rd and 6th positions by acyl groups other than acetyl groups When DSB is DSB, the value of DSA + DSB is preferably 2.22 to 2.90, and particularly preferably 2.40 to 2.88.

  The DSB is preferably 0.30 or more, particularly preferably 0.7 or more. Further, 20% or more of DSB is preferably a substituent at the 6-position hydroxyl group, more preferably 25% or more, further preferably 30% or more, and particularly preferably 33% or more. Furthermore, the value of DSA + DSB at the 6-position of cellulose acylate is 0.75 or more, more preferably 0.80 or more, and particularly preferably cellulose acylate of 0.85 or more. When such cellulose acylate is used, a dope having excellent solubility can be prepared. In the case of using the cellulose acylate as described above, when a non-chlorinated solvent is used, a dope having very excellent solubility, low viscosity, and excellent filterability can be prepared. .

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

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

  The details of cellulose acylate that can be used in the present invention are described in paragraphs [0140] to [0195] of JP-A-2005-104148, and these descriptions also apply to the present invention. Can do.

  The solvent used as the dope material is preferably an organic compound that can dissolve the polymer used. However, in the present invention, the dope means a mixture obtained by dissolving or dispersing the polymer in a solvent, and therefore a solvent having low solubility with the polymer can also be used. Examples of the solvent that can be suitably used include aromatic hydrocarbons such as benzene and toluene, halogenated hydrocarbons such as dichloromethane, chloroform, and chlorobenzene, and alcohols such as methanol, ethanol, n-propanol, n-butanol, and diethylene glycol. , Ketones such as acetone and methyl ethyl ketone, esters such as methyl acetate, ethyl acetate and propyl acetate, ethers such as tetrahydrofuran and methyl cellosolve, and the like. Two or more kinds of solvents may be selected from these solvents and mixed solvents may be used. Among these, use of dichloromethane is preferable because a dope having excellent solubility can be obtained and the solvent in the cast film can be volatilized in a short time to form a film.

  As said halogenated hydrocarbon, a C1-C7 thing is used preferably. Furthermore, from the viewpoints of compatibility with the polymer, peelability which is an index of ease of peeling of the cast film peeled off from the support, mechanical strength of the film, optical properties, etc., dichloromethane has 1 to 5 carbon atoms. It is preferable to use one of these alcohols or a mixture of several alcohols. The content of alcohol is preferably 2 to 25% by weight, more preferably 5 to 20% by weight, based on the entire solvent. Specific examples of the alcohol include methanol, ethanol, n-propanol, isopropanol, n-butanol, etc. Among them, it is preferable to use methanol, ethanol, n-butanol, or a mixture thereof.

  Recently, a solvent composition not using dichloromethane has been proposed in order to minimize the influence on the environment. For this purpose, ethers having 4 to 12 carbon atoms, ketones having 3 to 12 carbon atoms, and esters having 3 to 12 carbon atoms are preferable, and these are preferably used by being mixed appropriately. These compounds may have a cyclic structure, and compounds having two or more functional groups of ether, ketone and ester, that is, any of -O-, -CO-, and -COO- are also used as a solvent. Can be used. In addition, the solvent may have another functional group such as an alcoholic hydroxyl group. In addition, when it has two or more types of functional groups, the carbon number should just be in the prescription | regulation range of the compound which has either functional group, and it does not specifically limit.

  Depending on the purpose, the dope may be added with various known additives such as a plasticizer, an ultraviolet absorber (UV agent), a deterioration preventing agent, a slipping agent, and a peeling accelerator. For example, as the plasticizer, phosphate plasticizers such as triphenyl phosphate and biphenyldiphenyl phosphate, phthalate plasticizers such as diethyl phthalate, and various known plasticizers such as polyester polyurethane elastomers are used. be able to.

  Moreover, it is preferable to add fine particles to the dope for the purpose of preventing adhesion between films or adjusting the refractive index. As the fine particles, a silicon dioxide derivative is preferably used. The silicon dioxide derivative in the present invention includes silicon dioxide and a silicone resin having a three-dimensional network structure. As such a silicon dioxide derivative, it is preferable to use an alkylated surface. Fine particles that have been subjected to a hydrophobic treatment such as an alkylation treatment have excellent dispersibility in a solvent, so that a dope can be prepared without agglomeration of the fine particles, and a film can be produced. It is possible to produce a film with few state defects and high transparency.

  As described above, as the fine particles whose surface is alkylated, for example, Aerosil R805 (manufactured by Nippon Aerosil Co., Ltd.) which is commercially available as a silicon dioxide derivative having an octyl group introduced on its surface can be used. . In order to obtain a highly transparent film while ensuring the effect of adding fine particles, the fine particle content relative to the solid content of the dope is preferably 0.2% or less. Further, the average particle diameter is preferably 1.0 μm or less, more preferably 0.3 to 1.0 μm, and particularly preferably 0.4 to 0 so that the fine particles do not hinder the passage of light. .8 μm.

  As described above, in the present invention, it is preferable to prepare a dope using TAC as a polymer in order to obtain a highly transparent polymer film. In this case, it is preferable that the ratio of containing TAC is 5 to 40% by weight with respect to the total amount of the dope after mixing the solvent, additives and the like. More preferably, the ratio containing TAC is 15 to 30% by weight, and particularly preferably 17 to 25% by weight. Moreover, it is preferable that the ratio in which an additive (mainly a plasticizer) is contained shall be 1 to 20 weight% with respect to the whole solid content including the polymer, other additives, etc. which are contained in dope.

  Note that various additives such as solvents, plasticizers, ultraviolet absorbers, deterioration inhibitors, slipping agents, release accelerators, optical anisotropy control agents, retardation control agents, dyes, release agents, and the like, and fine particles are disclosed in JP-A-2005. No. 104148, paragraphs [0196] to [0516] describe in detail, and these descriptions can also be applied to the present invention. Further, it is a method for producing a dope using TAC. For example, materials, raw materials, additive dissolution methods and addition methods, filtration methods, defoaming, and the like are also disclosed in JP-A-2005-104148 [0517]. It is described in detail from paragraph to [0616] paragraph, and these descriptions can also be applied to the present invention.

  A film 37 was manufactured in the film manufacturing facility 10 shown in FIG. An appropriate amount of the dope was sent from the dope production facility 20 to the casting die 24 via the feed block 22, and the dope was cast from the casting die 24 onto the continuously rotating casting drum 23 to form the casting film 25. . The discharge amount of the dope was adjusted so that the thickness of the dried film 37 was 80 μm. The discharge port of the casting die 24 was a slit having a width of 1.8 m. The temperature of the dope at the time of casting was set to 36 ° C. The internal temperature of the feed block 22 was 36 ° C. The pressure behind the bead was reduced to 600 Pa and the pressure behind the bead was reduced.

  As the casting drum 23, a stainless steel drum capable of controlling the rotation speed was used. The surface temperature of the casting drum 23 was set to −10 ° C. by supplying the refrigerant into the casting drum 23 from the heat transfer medium supply device. The temperature inside the casting chamber 11 was always 35 ° C. using the temperature control device 30.

  When the casting film 25 was cooled and gelled and became self-supporting, the casting film 25 was peeled off as a wet film 25a by the peeling roller 26. While the stripped wet film 25a is fed to the crossover section 12 and conveyed while being supported by a plurality of rollers 35 provided in the crossover section 12, the blower 40 is supplied with dry air adjusted to 40 ° C. and wetted. The film 25a was dried.

  As shown in FIG. 2, the pin 43 was inserted into the both ends of the wet film 25a sent to the pin tenter 13, and the wet film 25a was conveyed in the X direction. During the conveyance, the wet film 25a was stretched in the Y direction using the shift mechanism 44. Also, as shown in FIGS. 2 and 3, a drying duct 48 is provided below the conveyance path of the film 37. Dry air 56 was supplied to the duct body 50 from the dry air supply unit 52. Dry air 56 was blown from the blow holes 57a of the duct body 50 onto the wet film 25a. The exhaust hole 53a of the exhaust pipe 53 allows the dry air 56a flowing in a portion corresponding to the substantially central portion in the width direction of the wet film 25a out of the dry air 56 flowing below the wet film 25a. Exhausted inside. The shape of the exhaust hole 53a is a substantially rectangular shape. The dry air 56a was exhausted to the outside through the exhaust hole 53b. The exhaust amount of the dry air 56 a was controlled by the exhaust amount control unit 54.

As shown in FIG. 1, the wet film 25 a that has passed through the pin tenter 13 is sent to the clip tenter 14. In the clip tenter 14, the film 37 was conveyed while gripping both end portions thereof, and the film 37 was dried during the conveyance. As a result, a film 37 was obtained. Both end portions of the wet film 25a or the film 37 were cut using the ear-cutting devices 15a and 15b. Both ends of the cut wet film 25a or film 37 were sent to a crusher 65 through a cutter blower (not shown) and crushed into chips having an average of about 80 mm ² .

  A pre-drying chamber (not shown) was provided between the ear opener 15b and the drying device 16, and the film 37 was preheated by supplying drying air at 100 ° C. and then sent to the drying device 16. In the drying device 16, the film 37 is conveyed while being wound around a plurality of rollers 67, and drying is performed during the conveyance. The internal temperature of the drying device 16 was adjusted so that the film surface temperature of the film 37 was 140 ° C. The drying time of the film 37 in the drying device 16 was 10 minutes. The film surface temperature of the film 37 was measured using a thermometer (not shown) provided immediately above the conveyance path of the film 37 and in the vicinity of the surface. After recovering the solvent gas generated in the crossover part 12, the pin tenter 13, the clip tenter 14, and the drying device 16 using an adsorption recovery device 69 having an adsorbent composed of activated carbon and a desorbent composed of dry nitrogen, the moisture content The water content of the solvent gas was removed until the water content became 0.3% by weight or less.

  A humidity control chamber (not shown) is provided between the drying device 16 and the cooling device 17, and air having a temperature of 50 ° C. and a dew point of 20 ° C. is supplied to the film 37. % Air was blown to adjust the humidity, and the curl generated in the film 37 was corrected. Next, the film 37 was sent to the cooling device 17, and the film 37 was gradually cooled until it became 30 degrees C or less.

  The film 37 was sent to the winding device 18, and was wound by a winding roller 70 having a diameter of 169 mm while applying a pressing force of 50 N / m to the film 37 by the press roller 71. At the time of winding, the tension at the start of winding of the film 37 was 300 N / m, and the tension at the end of winding was 200 N / m. Thus, a roll-shaped film 37 was obtained.

  The completed film 37 had a film thickness of 80 μm. In addition, the average drying rate of the cast film and the film was set to 20% by weight / min throughout the film forming process.

The dope raw materials used in this example are shown below.
Cellulose triacetate 100 parts by weight Dichloromethane 320 parts by weight Methanol 83 parts by weight 1-butanol 3 parts by weight Plasticizer A 7.6 parts by weight Plasticizer B 3.8 parts by weight UV agent a 0.7 part by weight UV agent b 0.3 part by weight Part citrate ester mixture 0.006 parts by weight fine particles 0.05 parts by weight

  The cellulose triacetate has a substitution degree of 2.84, a viscosity average polymerization degree of 306, a water content of 0.2% by weight, a viscosity of 6% by weight in a dichloromethane solution of 315 mPa · s, an average particle diameter of 1.5 mm, and a standard deviation of 0.8. 5 mm powder, plasticizer A is triphenyl phosphate, plasticizer B is diphenyl phosphate, and UV agent a is 2 (2′-hydroxy-3 ′, 5′-di- tert-butylphenyl) benzotriazole, UV agent b is 2 (2′-hydroxy-3 ′, 5′-di-tert-amylphenyl) -5-chlorobenzotriazole, and the citrate ester compound is It is a mixture of acid, monoethyl ester, diethyl ester and triethyl ester, and the fine particles have a mean particle size of 15 nm and a Mohs hardness of about 7 It is silicon. In addition, when the dope is prepared, a retardation control agent (N—N-di-m-toluyl-N—P-methoxyphenyl-1,3,5-triazine-2,4,6-triamine) is used as a film. It added so that it might become 4.0 weight% with respect to the total weight.

  The devices other than the drying duct in the pin tenter were the same as in Example 1, and the manufacturing conditions relating to these devices were also the same as in Example 1. As shown in FIGS. 4 and 5, a drying duct 75 is provided below the conveyance path of the wet film 25a. Dry air 77 was supplied to the duct body 76 from the dry air supply unit 78. On the upper surface 80 of the duct body 76, a recess 82 is formed at a position facing the substantially central portion in the width direction of the wet film 25a. Dry air 77 was blown against the wet film 25a from the blow hole 82a provided in the recess 82 and the blow hole 80a provided in a portion other than the recess 82.

  The devices other than the drying duct in the pin tenter were the same as in Example 1, and the manufacturing conditions relating to these devices were also the same as in Example 1. As shown in FIGS. 6 and 7, a drying duct 90 is provided below the conveyance path of the wet film 25a. The duct main body 91 of the drying duct 90 is composed of a first air blowing unit 94 and a second air blowing unit 95. Dry air 96 was supplied from the first dry air supply unit 92 to the first air blowing unit 94. The drying air 100 was supplied from the second drying air supply unit 93 to the second air blowing unit 95. The first air blower 94 is provided with a blowout hole 98 at a position facing the substantially central portion in the width direction of the wet film 25a. The second air blower 95 is provided with a blowout hole 102 at a position facing a portion other than the substantially central portion in the width direction of the wet film 25a. Dry air 96 was blown from the blowout holes 98 and dry air 100 was blown from the blowout holes 102 to the wet film 25a. At that time, the air volume control unit 92 a of the first dry air supply unit 92 made the air volume of the dry air 96 smaller than the air volume of the dry air 100.

  The devices other than the drying duct in the pin tenter were the same as in Example 1, and the manufacturing conditions relating to these devices were also the same as in Example 1. As shown in FIGS. 8 and 9, a drying duct 110 is provided below the conveyance path of the wet film 25a. Dry air 112 was supplied to the duct body 111 from the dry air supply unit 113. Protrusions 115 formed along the Y direction on the upper surface 80 of the duct body 111 and spaced apart from each other at a predetermined interval in the X direction are provided between the protrusions 115 and are movable in the Z direction. A movable plate 116 was provided. Blow holes 115a are formed in the protrusions 115, and exhaust holes 116a are formed in the movable plate 116. The drying air 112 was blown from the blowing hole 115a to the wet film 25a, and the drying air 112 was exhausted to the exhaust hole 116a. At that time, the movable plate 116 was moved in the Z direction by the shift unit 118 so that the static pressure at the center portion was lowered.

  In any case of [Example 1] to [Example 4], the static pressure distribution below the wet film 25a was suppressed to −200% to + 200% of the weight per unit area of the wet film 25a. As a result, the static pressure distribution below the wet film 25a was made uniform, and the wet film 25a in the pin tenter 13 was transported without its central portion bulging in a convex shape. Therefore, the quality of the film after production could be ensured.

It is the schematic of a film manufacturing equipment. It is sectional drawing showing the pin tenter in 1st Embodiment of this invention, and the dry duct in the pin tenter. It is a perspective view showing the dry duct in the pin tenter in 1st Embodiment of this invention. It is sectional drawing showing the pin tenter in 2nd Embodiment of this invention, and the dry duct in the pin tenter. It is a perspective view showing the drying duct in the pin tenter in 2nd Embodiment of this invention. It is sectional drawing showing the pin tenter in 3rd Embodiment of this invention, and the dry duct in the pin tenter. It is a perspective view showing the drying duct in the pin tenter in 3rd Embodiment of this invention. It is a perspective view showing the drying duct in the pin tenter in 4th Embodiment of this invention. It is a partial cross section figure showing the dry duct in the pin tenter in a 4th embodiment of the present invention.

Explanation of symbols

13 Pin tenter 25a Wet film 48 Dry duct 53 Exhaust pipe 53a Exhaust hole 54 Exhaust volume control part 56, 56a Dry air 75 Dry duct 77 Dry air 80 (of the air duct) Upper surface 80a, 82a Blow hole 82 Recess 90 Dry duct 92 1st Dry air supply unit 92a Air volume control unit 94 First air blowing unit 95 Second air blowing unit 96, 100 Dry air 110 Drying duct 112 Dry air 115 Protruding part 116 Movable plate 118 Shift unit

Claims (11)

In the web conveying device that conveys the web while carrying the both side ends of the web by the carrying unit and blowing the drying air to the web by the drying air supply unit.
A web conveyance device comprising static pressure distribution uniformizing means for lowering a static pressure caused by the drying air at a central portion in the width direction of the web and uniforming a static pressure distribution in the web width direction. The drying air supply unit is a drying duct having a blow-off opening that blows the drying air toward the web.
The static pressure distribution uniformizing means is provided at a position corresponding to a substantially central portion in the width direction of the web so as to penetrate the web-facing surface of the drying duct, and includes a dry air exhaust unit that exhausts the dry air. The web conveyance device according to claim 1, wherein the web conveyance device is provided.   The web conveyance device according to claim 2, wherein the dry air exhaust unit includes an exhaust amount control unit that controls an exhaust amount of the dry air. The drying air supply unit is a drying duct having a blow-off opening that blows the drying air toward the web.
The static pressure distribution uniformizing means is configured by a concave portion or a convex portion provided on a web facing surface of the drying duct at a position corresponding to a substantially central portion in the width direction of the web. The web conveying apparatus as described. The drying air supply unit is a drying duct having a blow-off opening that blows the drying air toward the web.
2. The web conveying apparatus according to claim 1, wherein the static pressure distribution equalizing means has an air volume control mechanism for controlling a dry air blowing amount in the web width direction by the blowing opening. The drying air supply unit is a drying duct having a blowing opening for blowing the drying air against the web,
The static pressure distribution uniformizing means includes:
Protrusions that have the blow-off openings on the facing surface of the web of the drying duct, each extending in the width direction of the web and spaced apart at a predetermined interval in the web conveyance direction;
A movable part provided between the protrusions and movable in a direction facing the web;
The web conveyance device according to claim 1, further comprising a shift unit that moves the movable unit.   The web transfer device according to claim 6, wherein the movable portion is provided with an exhaust hole for exhausting the dry air.   The web conveyance according to any one of claims 1 to 7, wherein the static pressure distribution uniformizing means suppresses the static pressure distribution in the web width direction to within ± 200% of the weight per unit area of the web. apparatus.   The web is peeled off after casting a dope comprising a polymer and a solvent on a support that runs endlessly to give self-supporting property, and the content of the solvent is 130% by mass or more. The web conveyance device according to any one of claims 1 to 8, wherein the web conveyance device is a cellulose acylate film.   The web conveying device according to any one of claims 1 to 9, wherein the carrier has a plurality of pins that pierce the web and travels endlessly. A step of casting a dope containing a polymer and a solvent on a support that runs endlessly to form a cast film;
Peeling the cast film from the support to form a wet film;
Both sides of the wet film are carried by the traveling carrying part, and the dry air is blown to the wet film by the dry air supply unit, and the wet film is caused to float by the static pressure distribution uniformizing means. A solution casting method characterized by comprising a step of lowering the static pressure due to the drying air at the center and uniforming the static pressure distribution in the web width direction for drying.

Images