JP2012148442A - Casting die, method of manufacturing die head, and method of manufacturing film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a widened die head body with a DLC layer while inhibiting a warp.SOLUTION: A casting die provided with a flow passage for flow of a dope includes a die body. The inlet of the flow passage is opened in the upper part of the die body. The outlet of the flow passage is opened in the downward end of the die body. The die body has a pair of side plates and a pair of lip plates. The flow passage is enclosed by the pair of side plates and the pair of lip plates. The lip plate is formed of a lip plate body which is a component member of the inlet of the flow passage and a die head 82 which is a component member of the outlet. The die head 82 can be fastened to the lip plate by bolts. The die head 82 is formed of the wedged die head body 85 and a DLC film 86 provided on the entire surface of the die head body 85. The DLC film 86 is provided on the die head body 85 by an ion deposition method.

Description

  The present invention relates to a casting die, a die head manufacturing method, and a film manufacturing method.

  Polymer films having light permeability (hereinafter referred to as films) are lightweight and easy to mold, and thus are widely used as optical films. Among these, cellulose ester films using cellulose acylate are used as optical films (polarizing plate protective films, retardation films, etc.) for liquid crystal display devices in addition to photographic photosensitive films.

  A solution casting method is known as a main method for producing a film. In the solution casting method, a film forming process, a film drying process, a stripping process, and a film drying process are sequentially performed. In the film forming step, a casting solution is formed on a moving support body by using a casting die to flow out a polymer solution containing a polymer and a solvent (hereinafter referred to as a dope). In the film drying step, the solvent is evaporated from the cast film until the cast film becomes self-supporting and can be conveyed. In the peeling process, the cast film that has undergone the film drying process is peeled off from the support to form a wet film. In the wet film drying step, the solvent is evaporated from the wet film to obtain a film.

  The casting die includes a pair of lip plates arranged in parallel in the moving direction of the support, a pair of side plates extending from one lip plate to another lip plate, a pair of lip plates and a pair. And a channel surrounded by the side plate. On the surface orthogonal to the dope flow direction, the flow path is formed in a rectangular shape having a short side extending in the moving direction and a long side extending in the width direction of the support moving path. The lip plate and the side plate are made of stainless steel (for example, SUS316L) having a low coefficient of thermal expansion and low solubility in a solvent.

  The casting die flows out of the dope from the outlet of the channel toward the moving support. As a result, a bead is formed between the tip of one lip plate and the support. If the bead becomes unstable in the film forming step, unevenness of thickness occurs in the cast film. Therefore, the bead is stabilized by sharpening the tip of the lip plate, which is the starting point of bead formation.

  However, since SUS316L is relatively soft with a Vickers hardness of about Hv180, it is very difficult to sharpen the tip by machining. Therefore, after providing a layer harder than SUS316L (hereinafter referred to as a hard layer) at the tip of the lip plate, the tip of the lip plate can be sharpened by predetermined machining. A tungsten carbide layer is known as this hard layer (for example, Patent Document 1).

  Moreover, the preferable shape of the front-end | tip part of a lip board changes with film manufacturing conditions. Therefore, the lip plate is divided into a lip plate main body that forms the inlet of the flow path and a tip portion (hereinafter referred to as a die head) that forms the outlet of the flow path, and the die head is detachably provided on the lip plate main body. By using such a die head, it becomes easy to switch the production of various types of films in one production line.

JP 2003-200097 A

  By the way, when the film forming process is continuously performed for a long time, the tungsten carbide layer provided on the die head is corroded. Corrosion of the tungsten carbide layer is caused by elution of a binder metal (such as cobalt atoms). If the casting die is used while the tungsten carbide layer is still corroded, a failure that causes streaks on the surface of the film due to peeling of the tungsten carbide layer occurs. For this reason, every time the film forming process is performed for a certain period of time, the film forming process must be stopped and the die head replaced with a new one, and the production efficiency of the film is lowered. From such a background, in order to form a stable DLC (Diamond Like Carbon) film having a longer life than the tungsten carbide layer on the die head, the DLC film is formed on the die head by using thermal CVD (Chemical Vapor Deposition). It is preferable to do. However, when a DLC film is formed on the die head by using thermal CVD, warpage occurs in the die head. It is difficult to attach the warped die head to the lip plate body.

  In recent years, with the enlargement of liquid crystal display devices, the production of wide optical films has become a new issue for optical film providers. In order to produce a wide optical film, the distance between the pair of side plates must be larger than before, and the lip plate body and die head must be lengthened. However, by increasing the length of the die head, the amount of warpage of the die head that occurs when the DLC film is formed increases. For this reason, it becomes very difficult to make a casting die corresponding to the widening of the film.

  This invention solves such a subject, and it aims at providing the casting die corresponding to widening, its manufacturing method, and the manufacturing method of a film.

  The present invention includes a pair of side plates that face each other at a distance, and a pair of lip plates that are provided from one side plate toward the other side plate and face each other, and the pair of side plates and the pair of lips. In a casting die that flows out a dope containing a polymer and a solvent from an outlet of a channel surrounded by a plate, each of the lip plates constitutes a lip plate body constituting an inlet of the channel and an outlet of the channel. The die head is divided into a stainless steel die head attached to the lip plate body, the die head having a wedge-shaped cross section has a DLC film at the tip, and the length of the die head in the arranging direction of the pair of side plates is set in the arranging direction. The value divided by the length of the die head in the orthogonal direction is 50 or more, and the DLC film is formed at a processing temperature of 130 ° C. or more and 200 ° C. or less.

  The length of the die heads in the alignment direction is preferably 1500 mm or more. The die head preferably includes a wedge-shaped die head main body made of stainless steel and a tungsten carbide layer provided at a tip of the die head main body. Furthermore, the thickness of the DLC film is preferably 2 μm or less.

  The method for producing a film of the present invention includes a film forming step of forming a film made of the dope on the support using the casting die, and from the film until the film can be carried independently. A membrane drying step for evaporating the solvent; a peeling step for peeling the membrane from the support to form a wet film; and a wet film drying step for evaporating the solvent from the wet film to form a film. It is characterized by.

  The present invention includes a pair of side plates that face each other at a distance, and a pair of lip plates that are provided from one side plate toward the other side plate and face each other, and the pair of side plates and the pair of lips. A casting die for discharging a dope containing a polymer and a solvent from an outlet of a flow path surrounded by a plate, wherein the lip plate is formed by a lip plate body constituting an inlet of the flow path, A method for manufacturing a stainless steel die head comprising an outlet and having a DLC film on the surface includes a cured film forming step of obtaining the die head by providing the DLC film on the surface of the stainless steel die head body by vapor deposition. The value obtained by dividing the length of the die head in the direction in which the pair of side plates are arranged by the length of the die head in the direction orthogonal to the direction of arrangement is 50 or more, Treatment temperature law is characterized by at 200 ° C. or less 130 ° C. or higher.

  The vapor deposition method is preferably any one of ionization deposition, ion plating, and plasma CVD. Further, in the cured film forming step, it is preferable that the target electrode and the die head main body are fixed by a fixing tool having a fluorine coating, and the die head main body and the fixing tool are fastened using a bolt. Further, in the cured film forming step, the die head main body and the support member are fastened by the bolts at fastening locations arranged in the direction of arrangement of the pair of side plates, and the direction of arrangement of the pair of side plates is increased. It is preferable that the tightening torque of the bolt decreases as it goes from the center to both ends.

  According to the present invention, a long-life DLC film can be formed on a die head while suppressing warpage of the die head. By using a casting die having such a die head, a wide film can be efficiently produced.

It is explanatory drawing which shows the outline | summary of solution casting apparatus. It is explanatory drawing which shows the outline | summary of the casting die etc. which are arrange | positioned in a casting chamber. It is a fragmentary sectional view which shows the outline | summary of the front-end | tip part of a casting die. It is a perspective view which shows the outline | summary of a die main body. It is a disassembled perspective view which shows the outline | summary of a die main body. It is a perspective view which shows the outline | summary of the flow path provided in the casting die. It is sectional drawing which shows the outline | summary of a slit flow path. It is a perspective view which shows the outline | summary of the lip plate which has a lip plate main body and a die head. It is a disassembled perspective view which shows the outline | summary of the lip plate which has a lip plate main body and a die head. It is sectional drawing which shows the outline | summary of a die head. It is sectional drawing which shows the outline | summary of a die head main body. It is sectional drawing which shows the outline | summary of the front-end | tip part of the lip board which comprises an exit. It is sectional drawing which shows the outline | summary of a DLC film forming apparatus. It is a perspective view which shows the outline | summary of the die head attached to the fixing tool. It is a perspective view which shows the outline | summary of a fixing tool and the die head attached to a fixing tool.

(Solution casting equipment)
As shown in FIG. 1, the solution casting apparatus 10 includes a casting chamber 12, a pin tenter 13, a drying chamber 15, a cooling chamber 16, and a winding chamber 17. As shown in FIGS. 1 and 2, the casting chamber 12 is provided with a casting die 21, a casting drum 22, a decompression chamber 23, and a peeling roller 24.

  The casting drum 22 includes a drive shaft 22a disposed horizontally and a drum body 22b pivotally attached to the drive shaft 22a. The drive shaft 22a is connected to a drive device (not shown). The casting drum 22 is preferably made of stainless steel, and more preferably made of SUS316L because it has sufficient corrosion resistance and strength.

  As shown in FIGS. 2 and 3, the casting die 21 having the flow path 29 through which the dope 28 flows has a die body 30 having a sharp tip. The casting die 21 is attached to the casting chamber 12 by a bracket (not shown) so that the die body 30 is in a predetermined direction. An outlet 29o of the flow path 29 opens at the lower end portion of the die body 30. The die body 30 is arranged so that the outlet 29o is close to the peripheral surface 22bx. Details of the casting die 21 will be described later.

  By driving the drive shaft 22a, the peripheral surface 22bx of the casting drum 22 moves in the Z1 direction at a predetermined speed in the vicinity of the outlet 29o. The casting die 21 flows out of the dope 28 (see FIG. 1) from the outlet 29o. The dope 28 that flows out from the outlet 29o and reaches the peripheral surface 22bx forms a bead 33 (see FIG. 3). The dope 28 that has reached the peripheral surface 22bx extends in the Z1 direction on the peripheral surface 22bx, and as a result, forms a belt-like casting film 34. Thus, in the casting chamber 12, the film forming process of forming the casting film 34 made of the dope 28 on the peripheral surface 22 bx is performed by the casting die 21 and the casting drum 22. Further, in the casting drum 22, a film drying process for evaporating the solvent from the casting film 34 is performed.

  The decompression chamber 23 is disposed upstream of the casting die 21 in the Z1 direction. Under the control of the control unit, the decompression chamber 23 sucks the gas upstream of the bead 33 in the Z1 direction. By sucking this gas, it is possible to create a state where the pressure on the upstream side of the bead 33 is lower than the pressure on the downstream side of the bead 33. Since the decompression chamber 23 can suck the accompanying air that is generated along with the movement of the peripheral surface 22bx and flows in the Z1 direction in the vicinity of the peripheral surface 22bx, the vibration of the bead 33 due to the collision with the accompanying air is suppressed. Can do. Furthermore, since the length of the bead 33 can be shortened, the vibration of the bead 33 can be suppressed. The pressure difference ΔP between the upstream side and the downstream side of the bead 33 is preferably 10 Pa or more and 2000 Pa or less.

  A temperature control device (not shown) is connected to the casting drum 22. The temperature control device incorporates a temperature adjusting unit that adjusts the temperature of the heat transfer medium. The temperature control device circulates the heat transfer medium adjusted to a desired temperature between the temperature adjusting unit and the flow path provided in the casting drum 22. Due to the circulation of the heat transfer medium, the temperature of the peripheral surface 22bx of the casting drum 22 can be maintained at a desired temperature. Further, by providing a condensing device that condenses the solvent contained in the atmosphere in the casting chamber 12 and a collecting device that collects the condensed solvent, the concentration of the solvent contained in the atmosphere in the casting chamber 12 is within a certain range. Can be kept in.

  The stripping roller 24 is disposed downstream of the casting die 21 in the Z1 direction. The stripping roller 24 performs a stripping process in which the casting film 34 formed on the peripheral surface 22bx is stripped to form a wet film 35. The wet film 35 is guided downstream of the casting chamber 12.

  A pin tenter 13, a drying chamber 15, a cooling chamber 16, and a winding chamber 17 are sequentially installed downstream of the casting chamber 12. A plurality of support rollers 41 that support the wet film 35 are arranged in the transition portion 40 between the casting chamber 12 and the pin tenter 13. The support roller 41 is rotated around an axis by a motor (not shown). The support roller 41 supports the wet film 35 sent out from the casting chamber 12 and guides it to the pin tenter 13. In the figure, two support rollers 41 are arranged in the transition section 40. However, the present invention is not limited to this, and three or more support rollers 41 may be arranged in the transition section 40. The support roller 41 may be a free roller.

  The pin tenter 13 has an annular holding member having a plurality of pins that pass through and hold both ends of the wet film 35 in the width direction, a pulley that circulates the holding member, and a dry wind on the wet film 35 held by the pins. And a dry air supply machine (not shown) for supplying. At the entrance of the pin tenter 13, a brush for biting both ends of the wet film 35 in the width direction is provided. The pin penetrates both ends of the wet film 35 in the width direction by pressing the brush. Then, the wet film 35 held at both ends by the pins is conveyed by the circulating travel of the holding member. As a result of evaporation of the solvent from the wet film 35 by contact with the dry air, the film 45 can be obtained from the wet film 35. In this way, a wet film drying step is performed from the transition portion 40 to the pin tenter 13 to evaporate the solvent from the wet film to form the film 45.

  An ear clip device 47 is provided between the pin tenter 13 and the drying chamber 15. At both ends in the width direction of the film 45 sent out to the edge cutting device 47, penetrating marks formed by pins are formed. The edge-cutting device 47 cuts off both end portions having this penetration mark. This separated part is sequentially sent to a cut blower (not shown) and a crusher (not shown) by air blowing, cut into small pieces, and reused as a raw material such as a dope.

  A large number of rollers 49 are provided in the drying chamber 15, and the film 45 is wound around and conveyed. The temperature and humidity of the atmosphere in the drying chamber 15 are adjusted by an air conditioner (not shown). In the drying chamber 15, the film 45 is dried. An adsorption recovery device 52 is connected to the drying chamber 15. The adsorption recovery device 52 recovers the solvent evaporated from the film 45 by adsorption.

  The cooling chamber 16 cools the film 45 until the temperature of the film 45 reaches substantially room temperature. Between the cooling chamber 16 and the winding chamber 17, a static elimination bar 54, a knurling roller 55, and an edge cutting device 56 are provided in order from the upstream side. The neutralization bar 54 is sent out from the cooling chamber 16 and performs a neutralization process for removing electricity from the charged film 45. The knurling roller 55 applies a winding knurling to both ends of the film 45 in the width direction. The edge-cutting device 56 cuts both ends in the width direction of the film 45 so that knurling remains at both ends in the width direction of the film 45 after cutting.

  A winding machine 63 having a press roller 61 and a winding core 62 is installed in the winding chamber 17, and the film 45 sent to the winding chamber 17 is pressed against the winding core 62 while being pressed by the press roller 61. It is wound up into a roll shape.

  As shown in FIGS. 4 and 5, the die body 30 includes a pair of side plates 71 made of stainless steel (SUS316, SUS316L, etc.) and a pair of lip plates 72. The pair of lip plates 72 extending from one end to the other end of the peripheral surface 22bx are arranged apart from each other in the Z1 direction in an upright posture with respect to the peripheral surface 22bx. A pair of side plates 71 extending from one lip plate 72 to the other lip plate 72 is in an upright position with respect to the peripheral surface 22bx and separated in the axial direction of the drum body 22b (hereinafter referred to as the Z2 direction). Are lined up. In this way, the flow path forming surfaces 72a provided on the pair of lip plates 72 face each other, and the flow path forming surfaces 71a provided on the pair of side plates 71 face each other. The distance between the pair of flow path forming surfaces 71a is larger than the distance between the pair of flow path forming surfaces 72a.

  As shown in FIGS. 5 and 6, the flow path 29 is surrounded by a pair of flow path forming surfaces 71a and a pair of flow path forming surfaces 72a. In the flow path 29, an inlet flow path 29a, a manifold 29b, and a slit flow path 29c are sequentially provided from an inlet 29i opening at the top of the die body 30 toward an outlet 29o. The inlet channel 29a sends the dope 28 flowing from the inlet 29i to the manifold 29b. The manifold 29b spreads the dope 28 in the Z2 direction, relaxes the distortion of the polymer molecules contained in the dope 28, and then sends the dope 28 to the slit channel 29c. The slit flow path 29c sends the dope 28 toward the outlet 29o.

  As shown in FIG. 7, the slit channel 29 c is formed in a rectangular shape on a surface orthogonal to the flow direction Z <b> 3 of the dope 28 in the channel 29. On the surface orthogonal to the direction Z3, the pair of long sides of the cross-sectional shape of the slit channel 29c is formed by the channel forming surface 72a, and the short side is formed by the channel forming surface 71a.

  As shown in FIGS. 8 and 9, the lip plate 72 includes a lip plate body 81 made of stainless steel (SUS316, SUS316L, etc.) that is a constituent member of the inlet 29 i, and a constituent member of the outlet 29 o. It is divided into a detachable wedge-shaped die head 82. The division position of the lip plate 72 is in the middle of the slit flow path 29c in the flow path forming portion 72a.

(Die head)
As shown in FIGS. 9 and 10, the die head 82 includes a die head main body 85 and a DLC film 86 provided on the die head main body. As shown in FIG. 11, the wedge-shaped die head main body 85 includes a distal end portion 90 constituting the outlet 29 o and an attachment portion 91 for attaching to the lip plate main body 81. The tip 90 is sharply formed in the Z3 direction, and includes a liquid contact surface 90a that is a part of the flow path forming surface 72a (see FIG. 7) and an exposed surface 90b that is exposed to the outside. The die head main body 85 is made of stainless steel (SUS316, SUS316L, etc.) and is formed in a substantially wedge shape.

  A hard layer 92 is provided at the tip 90 of the die head body 85 so as to be exposed. The Vickers hardness Hv of the hard layer 92 is larger than the Vickers hardness Hv of the die head body 82a. Further, the Vickers hardness Hv of the hard layer 92 is smaller than the Vickers hardness Hv of the DLC film 86. The Vickers hardness Hv of the hard layer 92 is preferably 1000 or more and 2000 or less. In addition, the VLC hardness Hv of the DLC film 86 is preferably 1200 or more and 2500 or less. The Vickers hardness Hv is a value converted from the indentation hardness (Oliver & Pharr calculation method) of ISO14577.

Examples of the material for forming the hard layer 92 include tungsten carbide (WC), Al ₂ O ₃ , TiN, Cr ₂ O _{3 and the} like, and WC is particularly preferable. Examples of WC include a WC-Co system in which cobalt is added as a binder metal, a WC-Ni system, a WC-TiC system, and a WC-TaC system, and any of them can be used in the present invention. The hard layer 92 can be formed by thermal spraying, for example. The thickness of the hard layer 92 is, for example, 50 μm or more and 200 μm or less.

  An example of a method for forming the die head body 85 having the hard layer 92 will be described. First, a hard layer forming area is recessed in the sharp part of the wedge-shaped die head main body 82a. Next, the hard layer 92 is provided in the hard layer formation area. After the hard layer 92 is formed, the die head main body 82a is subjected to predetermined machining so that the die head main body 82a has a wedge shape in which the hard layer 92 is exposed at the distal end portion 90.

As shown in FIGS. 9 and 11, when the length of the die head 82 in the Z3 direction is L _Z3 and the length of the die head 82 in the direction orthogonal to the Z3 direction is L _x , the value of (L _x / L _Z3 ). Is preferably 50 or more and 400 or less. L _x is preferably 1500 mm or more, and more preferably 2000 mm or more. Here, the direction orthogonal to the Z3 direction may be the Z2 direction or the Z1 direction. Therefore, when the length of the die head 82 in the Z1 direction is L _Z1 and the length of the die head 82 in the Z2 direction is L _Z2 , (L _x / L _Z3 ) is changed to (L _Z2 / L _Z3 ) or (L _Z1 / L _Z3 ).

  A through hole 95 penetrating the die head main body 85 is arranged in the Z2 direction in the attachment portion 91. As shown in FIG. 12, the lip plate body 81 is provided with a screw hole 96. In this way, the fastening bolt 97 is screwed into the screw hole 96 through the through hole 95, whereby the lip plate body 81 and the die head 82 are fastened. In FIG. 12, the display of the DLC film 86 is omitted in order to avoid complication of the drawing.

(DLC film)
As shown in FIG. 10, the DLC film 86 is provided on the entire surface of the die head main body 85. As a process for forming the DLC film 86, a known vapor deposition method can be used. In order to reduce the warp amount of the die head 82 after processing, the temperature T1 of the die head body 85 during processing is preferably 130 ° C. or higher and 200 ° C. or lower. Specific examples of the vapor deposition method include plasma CVD, ion plating, ionization deposition, and the like. Among these, ionization deposition is preferable. The thickness d of the DLC film 86 is preferably 1 μm or more and 2 μm or less, for example.

  As shown in FIG. 13, the DLC film forming apparatus 99 includes a cylindrical reflector 100 having a bottom, an anode 101 provided in the reflector 100 in a state of being electrically insulated from the reflector 100, and a reflector more than the anode 101. The cathode 102 provided electrically insulated from the reflector 100 on the opening end side of the reflector 100, the target electrode 103 made of stainless steel provided in front of the opening end of the reflector 100, and the opening end in the internal space of the reflector 100 And a gas introduction pipe 104 having the same. A die head main body 85 is attached to the target electrode 103 via a fixture 106. The potentials of the reflector 100, the anode 101, and the target electrode 103 when the potential of the cathode 102 is used as a reference are negative potentials, and decrease in the order of the anode 101, the reflector 100, and the target electrode 103.

  As shown in FIGS. 14 and 15, the stainless steel fixture 106 includes a fixing plate 110 fastened to the die head main body 85, two foot plates 111 projecting from the fixing plate 110, the die head main body 85 and the fixing. And a fixing bolt 112 for fastening the plate 110. Screw holes 115 are arranged in the fixing plate 110 in the Z2 direction. The fixing tool 106 and the die head body 85 are fastened by screwing the fixing bolt 112 into the screw hole 115 through the through hole 95.

A reaction gas (C ₆ H ₆ or the like) 117 is introduced from the gas introduction pipe 104 into the internal space of the reflector 100. Plasma is generated between the anode 101 and the cathode 102 by DC arc discharge. This plasma generates hydrocarbon ions from the reaction gas 117. The generated hydrocarbon ions go to the target electrode 103. In this way, as a result of the hydrocarbon ions colliding with the die head body 85 attached to the target electrode 103, the DLC film 86 is formed on the die head body 85. Thus, in the DLC film forming apparatus 99, a cured film forming step for obtaining the die head 82 from the die head main body 85 is performed by a predetermined vapor deposition method.

  Here, the die head body 85 is heated to a predetermined temperature by a vapor deposition method. Further, after the vapor deposition method, it is cooled to room temperature. In the process of heating and cooling, warpage occurs in the die head main body 85. Therefore, the surface of the fixed plate 110 is coated with fluorine, and a fluorine film having a lower friction than the material for forming the die head body 85 (for example, SUS316L) is provided on the surface of the fixed plate 110. By performing the vapor deposition method with the die head body 85 fixed through a low-friction fluorine film, the DLC film 86 (see FIG. 10) is formed on the die head body 85 while suppressing warping of the die head body 85. be able to. Further, it is preferable that the tightening torque of the fixing bolt 112 (see FIG. 15) decreases from the center portion in the Z2 direction toward both ends in the Z2 direction. For example, the tightening torque of the center fixing bolt (size M6) at the center in the Z2 direction is 10 N · m, and the tightening torque of the end fixing bolt (size M6) at the end in the Z2 direction is 3 N · m. . Further, the tightening torque of the fixing bolt (size M6) between the center fixing bolt and the end fixing bolt is 5 N · m. Accordingly, the DLC film 86 (see FIG. 10) can be formed on the die head body 85 while suppressing warping of the die head body 85.

  In the above embodiment, the range in which the DLC film 86 is formed is the entire surface of the die head main body 85, but it may be at least the tip portion 90 of the die head main body 85.

  In the above embodiment, the casting film 34 is cooled in order to make the casting film 34 stand-alone and can be conveyed. However, the present invention is not limited to this, and the solvent may be evaporated from the casting film 34. Good.

  In the said embodiment, although the casting drum 22 was used as a support body in the said embodiment, this invention is not restricted to this, The casting stretched around the roller arrange | positioned so that an axial direction may become horizontal A band may be used.

  The present invention provides simultaneous lamination co-casting in which two or more types of dopes are simultaneously co-cast and laminated when casting dopes, or sequential lamination co-production in which a plurality of dopes are sequentially co-cast and laminated. Casting can be performed. In addition, you may combine both casting. When simultaneous lamination and co-casting is performed, a casting die to which a feed block is attached may be used, or a multi-pocket casting die may be used.

(polymer)
As the polymer, cellulose acylate, cyclic polyolefin, or the like can be used.

(Cellulose acylate)
Only one type of acyl group may be used in the cellulose acylate of the present invention, or two or more types of acyl groups may be used. When two or more kinds of acyl groups are used, it is preferable that one of them is an acetyl group. The ratio in which the hydroxyl group of cellulose is esterified with carboxylic acid, that is, the substitution degree of the acyl group satisfies all of the following formulas (I) to (III) is preferable. In the following formulas (I) to (III), A and B represent the substitution degree of the acyl group, A is the substitution degree of the acetyl group, and B is the substitution degree of the acyl group having 3 to 22 carbon atoms. It is. In addition, it is preferable that 90 mass% or more of TAC is a particle | grain of 0.1 mm-4 mm.
(I) 2.0 ≦ A + B ≦ 3.0
(II) 1.0 ≦ A ≦ 3.0
(III) 0 ≦ B ≦ 2.0

  The total substitution degree A + B of the acyl group is more preferably 2.20 or more and 2.90 or less, and particularly preferably 2.40 or more and 2.88 or less. Further, the substitution degree B of the acyl group having 3 to 22 carbon atoms is more preferably 0.30 or more, and particularly preferably 0.5 or more.

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

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

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

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

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

(Additive)
A predetermined additive may be added to the dope. Examples of the additive used in the present invention include a plasticizer and an ultraviolet absorber. It is preferable to use a polycondensed ester as the plasticizer.

  The thickness of the film 45 is preferably 20 μm or more and 120 μm or less, and more preferably 40 μm or more and 100 μm or less.

  The width of the film 45 is preferably 700 mm or more and 3000 mm, more preferably 1000 mm or more and 2800 mm or less, and particularly preferably 1500 mm or more and 2500 mm or less. The width of the film 45 may be 2500 mm or more.

(Haze)
The haze of the film 45 is preferably less than 0.20%, more preferably less than 0.15%, and particularly preferably less than 0.10%. By setting the haze to less than 0.2%, the contrast ratio when incorporated in a liquid crystal display device can be improved. In addition, there is an advantage that the transparency of the film becomes higher and it is easier to use as an optical film.

  The in-plane retardation Re of the film 45 is preferably 20 nm or more and 300 nm or less, and the thickness direction retardation Rth of the film 45 is preferably −100 nm or more and 300 nm or less.

The method for measuring the in-plane retardation Re is as follows. In-plane retardation Re is a letter obtained by conditioning a sample film at a temperature of 25 ° C. and a humidity of 60% RH for 2 hours, and measuring it from the vertical direction at 632.8 nm with an automatic birefringence meter (KOBRA21DH Oji Scientific Co., Ltd.). The foundation value was used. Re is expressed by the following equation.
Re = | n1-n2 | × d
n1 represents the refractive index of the slow axis, n2 represents the refractive index of the fast axis 2, and d represents the thickness (film thickness) of the film.

The measuring method of the thickness direction retardation Rth is as follows. The sample film was conditioned at a temperature of 25 ° C. and a humidity of 60% RH for 2 hours, and measured in the same manner while tilting the film surface with an ellipsometer (M150 manufactured by JASCO Corporation) measuring 632.8 nm from the vertical direction. It calculated according to the following formula from the extrapolated value of the retardation value.
Rth = {(n1 + n2) / 2−n3} × d
n3 represents the refractive index in the thickness direction.

(Experiment 1)
A DLC film 86 was formed on the die head main body 85 by ionization vapor deposition using the DLC film forming apparatus 99 shown in FIG. 13 to obtain a die head 82 (see FIG. 10). The die head body 85 is entirely made of SUS316L and has a WC-Co hard layer 92 at the tip 90. The hardness Hv of the hard layer 92 was 1300. Regarding the die head main body 85, the length L _Z1 was 2 mm, the length L _Z2 was 2000 mm, and the length L _Z3 was 20 mm. The die head main body 85 was fixed to the target substrate 103 by using a fixture 106 (see FIGS. 14 and 15) in which a fluorine film was provided on the surface of a fixing plate 110 made of stainless steel (SUS316L). The temperature T1 of the die head body 85 in the cured film forming process was 150 ° C. to 200 ° C. The thickness d of the DLC film 86 was 1.6 μm.

(Experiments 2-7)
In Experiments 2 to 7, a DLC film 86 was formed on the die head main body 85 and the die head 82 was obtained in the same manner as in Experiment 1 except for the conditions shown in Table 1.

Table 1 shows the DLC film formation method, the temperature T1, the base material, the base hardness, the length L _Z2 , the thickness d of the DLC film 86, and the fixing plate surface forming material in Experiments 1 to 7. The base material refers to the material at the tip 90, and the base hardness refers to the Vickers hardness Hv of the tip 90. In Experiment 2, a fixture 106 (see FIGS. 14 and 15) provided with a stainless steel fixing plate 110 was used. In Experiments 3 and 6, a DLC film 86 is formed by replacing the DLC film formation method from ionized vapor deposition to plasma CVD, and in Experiment 7, the DLC film 86 is formed by replacing the ionized vapor deposition method from thermal CVD. Formed. In Experiment 5, the entire die head body 85 was made of SUS316L, and was used as it was without providing the hard layer 92 at the tip 90. The hardness Hv of the die head main body 85 was 300.

(Evaluation)
The following evaluation was performed on the die head 82 obtained in Experiments 1-7.

1. Warpage of die head The warpage amount W of the die head 82 was measured. First, the die head 82 was placed on the pedestal so that the curved portion would face downward. The largest of the gaps between the die head 82 and the pedestal was defined as the warp amount W. The measured warpage amount W was determined based on the following criteria.
A: W is 5 μm or less.
○: W is greater than 5 μm and 15 μm or less.
X: W is larger than 15 μm.

2. DLC film strength A frictional wear test was performed on the DLC film, the DLC film after the frictional wear test was visually observed, and the strength of the DLC film was evaluated based on the following criteria. The procedure of the friction and wear test is as follows. A friction and abrasion test (JIS R 1613-1993) was performed using a Tribometer (ball-on-disk type) manufactured by CSM Instruments. First, the die head 82 was fixed on the turntable, and the turntable was rotated at a predetermined rotation speed. Next, a ball-like (diameter 6.35 mm) Al ₂ O ₃ test piece is placed at a position of the DLC film 86 at the tip of the die head 82 and 3.0 mm away from the center of rotation. It pressed with the load (5.0N). The speed of the DLC film 86 at the pressing position was 0.1 m / second. The die head 82 was rotated 20000 times with the test piece pressed.
A: Cracking or peeling of the DLC film could not be confirmed.
(Triangle | delta): The crack or peeling of the DLC film has been confirmed. Further, the life of the tip of the die head 82 is longer than that of the conventional die head (die head main body 85).
X: Cracking or peeling of the DLC film could be confirmed. Further, the life of the tip of the die head 82 is the same as or shorter than that of the conventional die head (die head main body 85).

  The evaluation results for the above evaluation items are shown in Table 1. In Table 1, the numbers shown in the evaluation items represent the numbers assigned to the above evaluation items.

DESCRIPTION OF SYMBOLS 10 Solution casting equipment 21 Casting die 29 Flow path 29o Outlet 72 Lip plate 82 Die head 85 Die head main body 86 DLC film 90 Tip part 91 Attachment part 92 Hard layer

Claims (9)

A pair of side plates that are spaced apart and face each other; and a pair of lip plates that are provided from one side plate toward the other side plate and face each other, and are surrounded by the pair of side plates and the pair of lip plates. In the casting die that flows out the dope containing the polymer and the solvent from the outlet of the flow path,
Each of the lip plates is divided into a lip plate main body constituting the inlet of the flow path and a stainless steel die head constituting the outlet of the flow path and attached to the lip plate main body,
The die head having a wedge-shaped cross section has a DLC film at the tip,
The value obtained by dividing the length of the die head in the direction of alignment of the pair of side plates by the length of the die head in the direction orthogonal to the direction of alignment is 50 or more,
The casting die, wherein the DLC film is formed at a processing temperature of 130 ° C. or higher and 200 ° C. or lower.   The casting die according to claim 1, wherein the length of the die head in the arrangement direction is 1500 mm or more. The die head is
A wedge-shaped die head body made of stainless steel,
The casting die according to claim 1, further comprising a tungsten carbide layer provided at a tip of the die head body.   The casting die according to any one of claims 1 to 3, wherein a thickness of the DLC film is 2 µm or less. A film forming step of forming a film made of the dope on the support using the casting die according to any one of claims 1 to 4,
A film drying step of evaporating the solvent from the film until the film is self-supporting and transportable;
A stripping step of stripping the membrane from the support to form a wet film;
And a wet film drying step of evaporating the solvent from the wet film to obtain a film. A pair of side plates that are spaced apart and face each other; and a pair of lip plates that are provided from one side plate toward the other side plate and face each other, and are surrounded by the pair of side plates and the pair of lip plates. A casting die that flows out a dope containing a polymer and a solvent from an outlet of the flow path, wherein the lip plate is formed by a lip plate body that forms the inlet of the flow path, and constitutes an outlet of the flow path In a method for manufacturing a stainless steel die head having a DLC film on its surface,
A cured film forming step of obtaining the die head by providing the DLC film on the surface of the stainless steel die head body by vapor deposition;
The value obtained by dividing the length of the die head in the direction of alignment of the pair of side plates by the length of the die head in the direction orthogonal to the direction of alignment is 50 or more,
The method of manufacturing a die head, wherein a processing temperature of the vapor deposition method is 130 ° C. or higher and 200 ° C. or lower.   7. The method of manufacturing a die head according to claim 6, wherein the vapor deposition method is any one of ionization deposition, ion plating, and plasma CVD.   The said cured film formation process fixes a target electrode and the said die head main body with the fixing tool to which the fluorine coating was given, and fastens the said die head main body and the said fixing tool using a volt | bolt. Or the manufacturing method of the die head of 7. In the cured film forming step,
The die head body and the support member are fastened by the bolts at fastening points arranged in the direction in which the pair of side plates are arranged,
9. The method of manufacturing a die head according to claim 8, wherein a tightening torque of the bolt decreases from a center portion in the arrangement direction of the pair of side plates toward both ends.

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