JP5850961B2 - Die head manufacturing method - Google Patents

Description

The present invention relates to a die head 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 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 or the cast film is cooled 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 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 that cover both side ends of the pair of lip plates, a pair of lip plates, and a pair of side plates. And a flow path surrounded by. In the cross section orthogonal to the flow direction of the dope, the flow path is formed in a slit shape. The slit is formed in an elongated rectangle composed of a short side extending in the moving direction of the support and a long side extending in a direction (width direction) orthogonal to the moving direction of the support. The lip plate and the side plate are made of stainless steel having a low coefficient of thermal expansion and low solubility in the solvent used for the dope. The stainless steel is, for example, SUS316L.

  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 the lip plate and the support. If the bead becomes unstable in the film forming step, unevenness of thickness occurs in the cast film. For this reason, the bead is stabilized by sharpening the tip of the lip plate that 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. For this reason, a cemented carbide layer harder than SUS316L is provided at the tip of the lip plate, and the tip of the lip plate is sharpened by a predetermined machining on the cemented carbide layer. As this super hard layer, for example, as disclosed in Patent Document 1, a tungsten carbide (WC) layer is known.

  Moreover, the preferable shape of the front-end | tip part of a lip board changes with film manufacturing conditions. For this reason, 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 selecting and using such a die head, it becomes easy to switch and manufacture various types of films in one production line.

  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 in a state where the tungsten carbide layer is corroded, the tungsten carbide layer is peeled off, and due to this peeling, a failure in which streaks (streaks) are generated on the surface of the film 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, as disclosed in Patent Document 2, a DLC (Diamond Like Carbon) film having a longer life than a tungsten carbide layer and stable is formed on a die head. In addition, with the increase in size of liquid crystal display devices, the demand for wide optical films is rapidly increasing. In order to manufacture a wide optical film, the distance between the pair of side plates must be made larger than before, and the lip plate body and die head must be lengthened. When this die head is lengthened, the amount of warpage of the die head that occurs when the DLC film is formed increases. It is difficult to attach the warped die head to the lip plate body. For this reason, in Patent Document 2, the warpage of the die head is suppressed to a certain range by forming the DLC film at a heating temperature of 130 ° C. or higher and 200 ° C. or lower.

JP 2003-200097 A JP 2012-148442 A

  However, when a die head having a DLC film on the surface and suppressing warpage is attached to the dope outlet of the casting die and solution film formation is performed, a failure that causes streaks on the film surface occurs immediately after the start of film formation. However, it has been found that streak-like failure occurs when film formation is performed continuously for a long time, and a countermeasure has been desired. Such a streak-like failure becomes higher when a long outlet-shaped casting die corresponding to the widening of the film is used.

The present invention solves such problems, and an object of the present invention is to provide a method of manufacturing a die head corresponding to the widening of the film.

  As a result of examining the cause of the occurrence of the streak-like failure, it was found that fine cracks occurred in the DLC film and the underlayer, and that the streak-like failure was caused by the crack and the peeling of the DLC film caused by the crack. Obtained. As a result of intensive studies based on this knowledge, it has been found that fine cracks are generated due to thermal expansion strain generated between the underlayer and the base when the DLC film is formed.

The present invention has been made on the basis of the above knowledge, and a method of manufacturing a die head according to the present invention is a method of manufacturing a die head attached to a dope outlet of a casting die that flows out a dope containing a polymer and a solvent. It includes a formation process, a DLC film formation process, and a crack prevention conformity determination process. In the base layer forming step, a base layer having a super hard material is formed on a stainless base. In the DLC film forming step, a DLC film is formed on the underlayer by a vapor deposition method. In order to make the stress acting on the underlayer determined by the thermal expansion strain between the base and the underlayer in the DLC film forming step less than the breaking stress of the underlayer, The combination of the linear expansion coefficient, the length of the base in the longitudinal direction, and the heating temperature in the vapor phase film forming method is determined. Based on this combination, a base layer forming step and a DLC film forming step are performed. When the compressive force acting on the base is PB, the tensile force acting on the base layer is PL, and the cross-sectional area of the base layer in the cross section perpendicular to the longitudinal direction of the base is AL, the stress σ1 acting on the base layer is σ1 = (PB-PL) / AL

  The base is an elongated column body, where LY ≧ 50 · LW when the length in the longitudinal direction is LY and the maximum length in a cross section perpendicular to the longitudinal direction is LW, and the length LY is 1500 mm or more, The thickness of the underlayer is preferably 70 μm or more and 130 μm or less, and the thickness of the DLC film is preferably 0.7 μm or more and 2 μm or less.

  It is preferable that the base is formed of any one of SUS316L, SUS329J1, and SUS630, and the underlayer is formed of tungsten carbide.

  The difference in hardness between the underlayer and the DLC film is preferably 500 Hv or less. The DLC film is preferably formed by a vapor deposition method and has a hardness of 1300 Hv or more.

  The vapor deposition method is preferably any one of ionized vapor deposition, ion plating, and plasma CVD.

  According to the present invention, when the DLC film is formed on the underlayer, the generation of cracks in the underlayer and the DLC film is suppressed, and a die head composed of the DLC film without cracks can be obtained. By using a casting die having such a die head, the DLC film is not peeled off due to cracks. In addition, since the low friction characteristic due to the DLC film is partially reduced due to peeling, dope solids may be generated and grow at the die head exit of the lowered portion. Generation and growth of solid materials can be suppressed. Therefore, in order to remove the dope solids, the casting can be interrupted to greatly reduce the number of times the die head is washed, and the product loss due to the casting interruption is reduced, and the film is manufactured continuously and stably. be able to. Also, these effects can be obtained for widening the film.

It is a side view which shows the outline | summary of an example of solution casting apparatus. It is a perspective view which shows the outline | summary of examples, such as a casting die in a casting chamber, a casting drum. It is a fragmentary sectional view which shows the outline | summary of an example of the front-end | tip part of a casting die. It is a perspective view which shows the outline | summary of an example of a casting die. It is a disassembled perspective view of a casting die. It is a perspective view which shows the outline | summary of an example of the flow path provided in the casting die. It is sectional drawing which shows an example of the outline | summary of a flow path. It is a perspective view which shows the outline | summary of an example of the lip plate which has a lip plate main body and a die head. It is a disassembled perspective view of a lip board. It is sectional drawing which shows an example of the outline | summary of a die head. 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 an example of the outline | summary of a base and a base layer. It is sectional drawing which shows the outline | summary of an example of a DLC film forming apparatus. It is a perspective view which shows an example of the outline | summary of the die head attached to the fixing tool. It is a disassembled perspective view of a fixing tool and a die head. It is a flowchart which shows the manufacturing method of a die head.

(Solution casting equipment)
In FIG. 1 showing an example of the solution casting equipment, the solution casting equipment 10 includes a casting chamber 12, a pin tenter 13, a drying chamber 15, a cooling chamber 16, and a winding chamber 17. The casting chamber 12 is provided with a casting die 21, a casting drum 22 (support), a decompression chamber 23, and a peeling roller 24.

  As shown in FIG. 2, the casting drum 22 includes a drive shaft 22a disposed horizontally and a drum body 22b fixed 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 FIG. 3, the casting die 21 has a flow path 29 inside. An outlet 29o of the flow path 29 opens at the lower end portion of the casting die 21. The casting die 21 is disposed so that the outlet 29 o is close to the peripheral surface 22 c of the casting drum 22. Details of the casting die 21 will be described later. Due to the rotation of the casting drum 22, in the vicinity of the outlet 29o, the peripheral surface 22c moves in the X direction at a predetermined speed. The X direction indicates the direction of rotation of the casting drum 22, the Y direction indicates a direction orthogonal to the X direction (the width direction of the casting film 34), and the Z direction is orthogonal to the XY plane including the X direction and the Y direction. Direction (height direction of the casting die 21).

  The dope 28 is sent to the flow path 29 of the casting die 21. The dope 28 flows out from the outlet 29o toward the peripheral surface 22c. A bead 33 is formed by the dope 28 from the outlet 29o to the peripheral surface 22c. The dope 28 that has reached the peripheral surface 22 c is extended in the X direction on the peripheral surface 22 c, resulting in a belt-shaped casting film 34. In this way, the film forming step of forming the casting film 34 by the casting die 21 and the casting drum 22 is performed.

  The decompression chamber 23 is disposed upstream of the casting die 21 in the X direction. Under the control of a controller (not shown), the decompression chamber 23 sucks the gas upstream of the beads 33 in the X direction. Due to the suction of the gas, the pressure on the upstream side of the bead 33 becomes lower than the pressure on the downstream side of the bead 33. The decompression chamber 23 can suck accompanying air that is generated along with the movement of the peripheral surface 22c and flows in the X direction in the vicinity of the peripheral surface 22c. Therefore, the vibration of the bead 33 due to the collision with the accompanying wind is suppressed. Further, the length of the bead 33 is shortened by suction, and the vibration of the bead 33 is suppressed corresponding to the shortened length.

  A temperature control device 32 is connected to the casting drum 22. The temperature adjustment device 32 includes a temperature adjustment unit that adjusts the temperature of the heat transfer medium. The temperature control device 32 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. By circulating the heat transfer medium, the temperature of the peripheral surface 22c of the casting drum 22 can be maintained at a desired temperature. The solution casting apparatus 10 is provided with a condensing device for condensing the solvent contained in the atmosphere in the casting chamber 12 and a collecting device for collecting the condensed solvent. The concentration of the solvent contained is kept within a certain range. Thus, in the casting drum 22, a film drying process for evaporating the solvent from the casting film 34 is performed.

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

  As shown in FIG. 1, a pin tenter 13, a drying chamber 15, a cooling chamber 16, and a winding chamber 17 are sequentially arranged downstream of the casting chamber 12. A crossover 40 is provided between the casting chamber 12 and the pin tenter 13. A plurality of support rollers 41 are arranged in the transition part 40. The support roller 41 is rotated by a motor (not shown). The support roller 41 supports the wet film 35 and guides it to the pin tenter 13. Note that the number of the support rollers 41 of the crossover portion 40 is not limited to two, and may be one or more. The support roller 41 may be a free roller.

  The pin tenter 13 has a pair of annular chains, pulleys, and a dry air supply device. The annular chain has a plurality of pins attached at a constant pitch. The plurality of pins pass through and hold both ends of the wet film 35 in the width direction. The annular chain is circulated between pulleys. The dry air supply device supplies dry air to the wet film 35 held by the pins. A brush is provided at the entrance of the pin tenter 13. The brush presses both sides of the wet film 35 and causes the pins to penetrate the wet film 35. The wet film 35 whose both sides are held by the pins is conveyed by circulating travel of the annular chain. During this conveyance, the solvent evaporates from the wet film 35 by the contact with the dry air, and the film 45 is obtained. In this way, a film drying process is performed from the transition part 40 to the pin tenter 13 to evaporate the solvent from the wet film 35 to obtain the film 45.

  A side slitter 47 is provided between the pin tenter 13 and the drying chamber 15. The side slitter 47 cuts off both sides of the film where the through-holes by the pins remain from the center. The separated both sides are sent to a crusher (both not shown) via a cut blower, and are cut into small pieces and reused as raw materials for dopes and the like.

  The drying chamber 15 has a large number of rollers 49. The film 45 is wound around a roller 49 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 a side slitter 56 are provided in order from the upstream side. The neutralization bar 54 performs a neutralization process for removing electricity from the charged film 45. The knurling roller 55 applies a winding knurling to both sides of the film 45. The side slitter 56 cuts off both sides of the film 45 so as to leave a knurling on the product film side.

  The winding chamber 17 has a winder 63. The winder 63 winds the film 45 around the winding core 62 in a roll shape. The press roller 61 presses the film 45 against the winding core 62 side.

  As shown in FIG. 4, the casting die 21 has 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 are in close contact with each other. As shown in FIG. 5, a flow path forming surface 72a is formed on the close contact surface of the lip plate 72, and the flow path 29 is formed by the flow path forming surface 72a as shown in FIG. The pair of side plates 71 are attached so as to cover both end surfaces 72 b of the lip plate 72. The side plate 71 closes both ends of the flow path 29.

  As shown in FIG. 6, the flow path 29 has an inlet flow path 29a, a manifold 29b, and a slit flow path 29c. These flow from the inlet 29i that opens to the upper part of the casting die 21 to the outlet (dope flow). (Exit) are provided sequentially toward 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 Y 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 channel 29c sends the dope 28 toward the outlet 29o.

  As shown in FIG. 7, the slit channel 29 c is formed in an elongated rectangular shape in a cross section on the XY plane orthogonal to the flow direction (Z direction) of the dope 28 in the channel 29. In the cross section of the slit channel 29c, a pair of long sides is composed of a channel forming surface 72a, and a short side is composed of a channel forming surface 71a.

  As shown in FIGS. 8 and 9, the lip plate 72 is divided into a lip plate body 81 and a die head 82 made of stainless steel (SUS316, SUS316L, etc.). The die head 82 is a prismatic body that is substantially wedge-shaped and elongated in the Y direction, and is detachably attached to the lip plate main body 81 with attachment screws 97. Thereby, the die head 82 is detachably provided at the outlet 29o of the casting die 21. The dividing position of the lip plate main body 81 and the die head 82 is in the middle of the slit flow path 29c in the flow path forming surface 72a.

(Die head)
As shown in FIG. 10, the die head 82 includes a base 85, a base layer 92, and a DLC film 86. As shown in FIG. 9, the base 85 is made of stainless steel (SUS316, SUS316L, SUS329J1, SUS630, etc.), and is formed from a long prismatic body having a substantially wedge-shaped cross section along the XZ plane. The base 85 has, for example, four mounting holes 95 at regular intervals in the Y direction. As shown in FIG. 11, screw holes 96 are formed in the lip plate body 81 at positions corresponding to the mounting holes 95. The die head 82 is detachably fastened to the lip plate body 81 by attaching the attachment screw 97 to the screw hole 96 through the attachment hole 95.

  As shown in FIG. 12, the base layer 92 is formed on the surface of the lower end portion 85 a of the base 85. The surface of the foundation layer 92 is sharply formed in the Z direction, and has a flow channel surface 92a for forming the flow channel 29 and an exposed surface 92b exposed to the outside.

  Examples of the material for forming the base layer 92 include super hard materials such as tungsten carbide (WC), Al 2 O 3, TiN, and Cr 2 O 3, 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 underlayer 92 can be formed by thermal spraying, for example. For example, the thickness of the underlayer 92 is preferably in the range of 50 μm to 200 μm, and more preferably 70 μm to 130 μm. In each drawing, the thickness of the underlayer 92 and the DLC film 86 is exaggerated in comparison with other members for the purpose of illustration.

  The underlayer 92 is formed as follows, for example. First, a base layer forming area is recessed at the sharp portion of the wedge-shaped base 85. Next, a base layer 92 is provided in the base layer formation area. After the base layer 92 is formed, the base layer 92 is formed in the same manner as the base 85 by mechanical processing such as polishing. In this way, the underlayer forming process is performed.

  As shown in FIGS. 9 and 12, when the maximum length in the cross section of the die head 82 in the XY plane is LW and the length of the die head 82 in the Y direction is LY, the value of (LY / LW) is 50 It is preferably 400 or less, that is, 50 · LW ≦ LY ≦ 400 · LW. LY is preferably 1500 mm or more, and more preferably 2000 mm or more.

  The attachment hole 95 penetrates the base 85 in the Z direction. A plurality of the mounting holes 95 are provided apart from each other in the Y direction. A screw hole 96 is provided in the lip plate body 81 at a position corresponding to the mounting hole 95. In FIG. 12, the display of the DLC film 86 is omitted in order to avoid complication of the drawing.

  The Vickers hardness Hv of the underlayer 92 is larger than the Vickers hardness Hv of the base 85. Further, the Vickers hardness Hv of the underlayer 92 is smaller than the Vickers hardness Hv of the DLC film 86. The Vickers hardness Hv of the underlayer 92 is preferably 150 Hv or higher. In addition, the VLC hardness Hv of the DLC film 86 is preferably 1300 Hv or more and 2500 Hv or less. Further, as will be described in detail later, the Vickers hardness difference (Hv2-Hv1 described later) between the underlayer 92 and the DLC film 86 is preferably 500 Hv or less. The Vickers hardness Hv is a value converted from the indentation hardness (Oliver & Pharr calculation method) of ISO14577. In the following description, Vickers hardness may be referred to as “hardness”, and Vickers hardness difference may be referred to as “hardness difference”.

(DLC film)
As shown in FIG. 10, the DLC film 86 is provided on the entire surface of the base 85. However, in this embodiment, since the upper end surface 85b of the base 85 shown in FIG. 10 is attached in close contact with the fixture 106 as shown in FIG. 14, the DLC film 86 is not formed on the upper end surface 85b. The DLC film 86 is formed by a known vapor deposition method. In order to reduce the warp amount of the die head 82 after the treatment, the heating temperature ΔT of the base 85 during the treatment is preferably 130 ° C. or more and 300 ° C. or less. This ΔT will be described later. Specific examples of the vapor deposition method include plasma CVD, ion plating, and ionized vapor deposition. Of these, ionized vapor deposition is preferable. The thickness d of the DLC film 86 is, for example, preferably in the range of 0.7 μm to 2 μm, and more preferably in the range of 1 μm to 2 μm.

  As shown in FIG. 13, a DLC film forming apparatus 99 that forms a DLC film by ionization vapor deposition includes a reflector 101, a filament 102, an anode 103, a target electrode 104, and a gas introduction pipe 105 in a processing chamber 100. Have. The reflector 101 is formed in a cylindrical shape having a bottom, for example. The anode 103 is provided in the reflector 101 while being electrically insulated from the reflector 101. A plasma source 107 is configured by the tripolar structure of the filament 102, the anode 103, and the reflector 101. A gas introduction pipe 105 is connected to the reflector 101. A reaction gas 108 such as a hydrocarbon gas is sent from the gas introduction pipe 105 into the reflector 101. A base 85 is attached to the target electrode 104 via a fixture 106. The power supply unit 109 includes a reflector power supply 109a, a filament power supply 109b, an anode power supply 109c, and a target power supply 109d. These power supplies 109 a to 109 d apply a predetermined voltage to the reflector 101, the filament 102, the anode 103, and the target electrode 104 to be connected.

  As shown in FIGS. 14 and 15, the stainless steel fastener 106 includes a fixing plate 110 having foot plates 111 at right angles on both sides, and a fixing bolt 112 having a size of, for example, M6 (JIS (Japanese Industrial Standard)). Prepare. The fixing plate 110 is provided with screw holes 115 arranged side by side in the Y direction. By attaching the fixing bolt 112 to the screw hole 115 through the attachment hole 95, the base 85 is fastened to the fixture 106.

  As shown in FIG. 13, the reaction gas 108 is introduced from the gas introduction pipe 105 into the internal space of the reflector 101. Plasma is generated around the anode 103 by DC arc discharge. Hydrocarbon ions are generated from the reaction gas 108 by this plasma. The generated hydrocarbon ions are directed to the target electrode 104. Since the base 85 is attached to the target electrode 104, hydrocarbon ions collide with the base 85 and a DLC film 86 is formed on the base 85. Thus, in the DLC film forming apparatus 99, the DLC film forming process for forming the DLC film 86 on the base 85 is performed by ionized vapor deposition.

  The base 85 is heated to a predetermined temperature by ionization vapor deposition. In the case where the DLC film 86 is formed in an elongated shape like the die head 82, a plurality of plasma sources 107 are arranged in the longitudinal direction according to the length of the die head 82, and ionized vapor deposition is performed on the entire length of the die head 82. For this reason, as the die head 82 is elongated, the number of the plasma sources 107 increases as the length increases, and the number of electrodes increases accordingly, so that the processing temperature in the DLC film forming process increases.

  When adjusting the hardness of the DLC film 86, for example, in the ionization vapor deposition method, the following is performed. First, using hydrocarbon gas as a raw material, carbon ions C + are generated by vaporizing plasma or the like. By applying a cathode (−) voltage to the base 85, carbon ions are struck against the base 85 and a DLC film 86 is formed. When the carbon ions collide with the base 85, the mixing ratio of the diamond film (Sp3 bond) and the graphite film (Sp2 bond) constituting the DLC film 86 changes according to the collision energy of the carbon ions generated on the base 85. In the DLC film 86, the more the Sp3 bonds are, the harder the film is. When there are many Sp2 bonds, a low friction film tends to be obtained. By utilizing this tendency and adjusting the cathode voltage applied to the base 85, the DLC film 86 having desired characteristics can be formed.

  After ionization deposition, it is cooled to room temperature. In the process of heating and cooling, the base 85 is warped. For this reason, the surface of the fixed plate 110 is coated with fluorine. By providing a fluorine film having a lower friction than the forming material of the base 85 (for example, SUS316L) on the surface of the fixed plate 110 and performing ionization vapor deposition in a state where the base 85 is fixed via the low friction fluorine film. The DLC film 86 (see FIG. 10) can be formed on the base 85 while suppressing the warp of the base 85.

  In addition, it is preferable that the fastening torque of the fixing bolt 112 (see FIG. 15) decreases from the central portion in the Y direction toward both ends in the Y direction. For example, the tightening torque of the center fixing bolt 112 at the center in the Y direction is 10 N · m, and the tightening torque of the end fixing bolt 112 at the end in the Y direction is 3 N · m. The tightening torque of the fixing bolt 112 between the center fixing bolt 112 and the end fixing bolt 112 is 5 N · m. Thus, the tightening torque becomes smaller toward the end portion, so that the end portion of the base 85 becomes easier to move, and the DLC film 86 (see FIG. 10) is applied to the base 85 while suppressing warpage and cracking of the base 85 more reliably. Can be formed.

  Since the base 85 and the base layer 92 are made of different materials, the linear expansion coefficient α1 of the base 85 and the linear expansion coefficient α2 of the base layer 92 are different. When the DLC film 86 is formed, the relationship between the difference (α1−α2) and the heating temperature (processing temperature in the DLC film forming process−room temperature) ΔT when forming the DLC film 86 is As the temperature rises, the elongation of the two differs and thermal expansion distortion occurs. The thermal expansion strain is a strain generated by each thermal expansion of the base 85 and the base layer 92. When the stress σ1 received by the underlayer 92 due to this thermal expansion strain exceeds the WC rupture stress σ2 of 820 MPa, the underlayer 92 breaks and cracks are generated in the underlayer 92 and the DLC film 86 formed on the underlayer 92. To do. Due to the occurrence of cracks, the yield of the die head 82 (the number of non-defective products with no occurrence of cracks / the total number of manufactured parts) is lowered, and the production efficiency is lowered. In addition, the DLC film 86 is peeled off during use over time due to minute cracks that have been missed so far, and a streak-like failure occurs in the film formation during solution film formation.

  For this reason, as shown in FIG. 16, the die head 82 is manufactured through a crack prevention suitable condition determination step 121, an underlayer formation step 122, and a DLC film formation step 123. In the crack prevention conformity condition determination step 121, the combination of the linear expansion coefficient of the base 85 and the base layer 92, the length LY in the longitudinal direction (Y direction) of the die head 82, and the heating temperature in forming the DLC film is changed. For each combination, the stress acting on the underlayer 92 from the external force due to the thermal expansion strain between the base 85 and the underlayer 92 due to the temperature rise during the formation of the DLC film, that is, σ1 acting on the underlayer 92 due to the thermal expansion strain is obtained. . When this stress σ1 is 820 MPa or more, which is the rupture stress σ2 of the underlayer 92, it is determined that cracks are generated in this combination. Further, when the obtained stress σ1 is less than 820 MPa, it is determined that no crack is generated. The aforementioned external force is a force generated by a compressive force PB acting on the base 85 and a pulling force PL acting on the underlayer 92, and acting on each in the longitudinal direction. Specifically, it is calculated by PB-PL. Note that the breaking stress σ2 is not only the stress itself that starts rupture, but also safety, for example, 95%, 90%, 85%, etc. A stress multiplied by a rate may be used.

The stress σ1 acting on the underlayer 92 is PB as the compressive force acting on the base 85, PL as the tensile force acting on the underlayer 92, and the underlayer in a cross section (cross section along the XZ plane) orthogonal to the longitudinal direction of the die head 82. When the cross-sectional area of 92 is AL,
It calculates | requires by (sigma) 1 = (PB-PL) / AL.

  The compression force PB acting on the base 85 is obtained as follows. First, the strain εB is obtained from εB = ΔLYB / LY from the amount of elongation ΔLYB of the base 85 due to the heating temperature and the length LY of the base. Next, the vertical stress σB (σB = εB · EB) is obtained by multiplying the strain εB by the Young's modulus EB of the base 85. The compression force PB (PB = σB · AB) is obtained by multiplying the obtained vertical stress σB by the cross-sectional area AB in the cross section along the XZ plane. Similarly, the tensile force PL of the underlayer 92 is obtained. First, the strain εL is obtained from εL = ΔLYL / LY from the amount of elongation ΔLYL due to the heating temperature of the underlayer 92 and the length LY of the base. Next, the vertical stress σL (σL = εL · EL) is obtained by multiplying the strain εL of the base layer 92 by the Young's modulus EL. The tensile force PL (PL = σL · AL) is obtained by multiplying the obtained normal stress σL by the cross-sectional area AL. Here, ΔLYB is obtained by subtracting the length in the Y direction before heating (non-heated state, that is, at room temperature) from the length in the Y direction under the above heating temperature. ΔLYL is obtained by subtracting the length in the Y direction before heating (non-heated state, that is, at room temperature) from the length in the Y direction under the heating temperature of the base layer 92.

  In addition, it is necessary to increase the quantity of the reflectors 101 as the length LY of the target base 85 becomes longer. For this reason, the number of electrodes increases as the number of reflectors 101 increases. Since vacuum plasma discharge is performed by this electrode, an increase in the electrode leads to an increase in the processing temperature. As described above, the processing temperature in the DLC film forming step 123 rises due to the increase in the amount of the reflector 101 according to the length of the base 85. Therefore, the heating temperature in the DLC film forming step 123 is obtained in advance by experiments or determined based on the past processing results data.

  The determination of the crack prevention conformity condition may be performed by using spreadsheet software (for example, Excel manufactured by Microsoft Corporation) in addition to the method of obtaining by the above formula. In this case, as shown in Table 1 below, in each column, the length LY in the longitudinal direction of the base 85 to be used, the linear expansion coefficient α between the base 85 and the base layer 92, and the heating temperature ΔT when forming the DLC film are listed. When the Young's modulus E, the cross-sectional area A, and the breaking stress σ2 of the underlayer 92 are numerically input, the underlayer 92 is obtained as a calculation result by the elongation ε due to thermal expansion, the stress σ during thermal expansion, the external force F at that time, and the thermal expansion strain. In each column of the tensile stress σ1 generated in FIG. The obtained stress σ1 is compared with the breaking stress σ2 (= 820 MPa) of the underlayer 92, and when σ1 <σ2, it is determined that the combination value is suitable, and the determination column in the rightmost column shows As a result of the determination, “OK” is displayed when it conforms, and “NG” is displayed when it does not conform. By using spreadsheet software in this way, it is possible to automatically determine whether or not the entered numerical value is in the crack prevention conformity condition by inputting numerical data and dimension data depending on the material of the die head to be created. .

  When a combination that satisfies the crack-free condition is obtained by the crack prevention conforming condition determination step 121, first, the underlayer 92 is formed by the underlayer formation step 122 under this condition, and then By forming the DLC film 86 in the DLC film forming step 123, it is possible to reliably obtain the die head 82 free from cracks.

  Although not shown in the figure instead of performing the numerical calculation by the spreadsheet software, it may be incorporated in a personal computer as an application to which a comparison determination and a data input guidance function are added. In this case, the input guidance function for each of the above conditions, the function of calculating the stress σ1 based on the input numerical values of each condition, and comparing the calculated stress σ1 with the rupture stress σ2, the stress σ1 is less than the rupture stress σ2. In this case, a judgment function for determining that the combination of these conditions is suitable, and a re-input function for issuing a crack occurrence alarm and re-entering each condition when the stress σ1 becomes equal to or greater than the rupture stress σ2 by comparison judgment. Configure your application to have it on your computer.

  Moreover, it is good also as an application which combined spreadsheet software. In this case, in addition to the tabular input guide as shown in Table 1, the obtained stress σ1 and the breaking stress σ2 are compared, and when σ1 <σ2, the combination of the conditions does not cause cracks. Displayed as conforming conditions. When σ1 ≧ σ2, the numbers in each column are displayed blinking to prompt the user to change the numerical value. At this time, if the conformity condition is calculated in the direction of increasing the numerical value, ↑ and ▲ symbols are attached to the numerical value, and if the conformance condition is determined in the direction of decreasing the numerical value, ↓ and ▼ are appended to the numerical value, Condition correction can be easily performed. Also, instead of entering numerical values, it automatically calculates how much the numerical value is changed and enters the matching condition, and changes the color to display the numerical value or display it adjacent to the input numerical value. Also good. At this time, one condition numerical value may be fixed, and other numerical values may be changed and automatically calculated.

  The hardness difference between the underlayer 92 and the DLC film 86 is 500 Hv or less, preferably 200 Hv or less, and more preferably 100 Hv or less. Experimental results show that the adhesion of the DLC film 86 to the underlying layer 92 is improved when the hardness difference between the two is within a certain range such as 500 Hv or less. This is considered to be due to the fact that when the difference in hardness between the two interfaces is large, a difference occurs in the amount of strain and the adhesion is reduced. If the hardness difference exceeds a certain value, a soft base such as SUS may be recessed first, and the DLC film 86 may not follow the change of the base and may break.

  The range in which the DLC film 86 is formed may be the entire surface of the base 85 or a part of the tip.

  In the above embodiment, the casting die 21 is configured by a combination of a pair of side plates 71 and a pair of lip plates 72. However, the present invention is not limited to this. For example, the side plate 71 is omitted, and only the lip plate 72 is used. It is good also as a casting die which formed channel 29. Furthermore, in addition to the side plate 71 and the lip plate 72, other members may be included to constitute the casting die.

  In the above-described embodiment, the casting film 34 is cooled in order to make the casting film 34 self-supporting, but the present invention is not limited to this. It is also possible to evaporate the water and make it possible to carry it independently.

  In the above embodiment, the casting drum 22 is used as the support, but a casting band may be used instead. In the case of using a casting band, the casting band is circulated by rotating the casting band between a pair of drums and rotating the drum.

  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.

  In the solution casting apparatus 10 of the present invention, the width of the film as a product is preferably 600 mm or more, and more preferably 1400 mm or more and 2500 mm or less. It is also effective when the film width is greater than 2500 mm. The film thickness is preferably 15 μm or more and 80 μm or less. The polymer used as the raw material for the polymer film is not particularly limited, and examples thereof include cellulose acylate and cyclic polyolefin.

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. Moreover, it is preferable that 90 mass% or more of triacetylcellulose (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 ≦ 2.9

  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.

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

(Experiment 1)
A DLC film 86 was formed on the base 85 shown in FIG. 12 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 base 85 is entirely made of SUS316L and has a WC-Co base layer 92 at the lower tip 85a. The underlayer 92 was formed by WC spraying, the hardness Hv was 1500, and the linear expansion coefficient was 8 × 10 −6 / ° C. The linear expansion coefficient of the base 85 was 16 × 10 −6 / ° C., and the difference between the linear expansion coefficients of the base layer 92 and the base 85 was 8 × 10 −6 / ° C. Regarding the base 85, the length LX was 20 mm, the length LY was 2000 mm, the length LZ was 20 mm, and the maximum length LW in the cross section on the XY plane was 28 mm. The base 85 was fixed to the target electrode 104 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 heating temperature ΔT of the base 85 in the cured film forming process was 180 ° C. The DLC film 86 had a thickness d of 1.6 μm and a hardness Hv of 2000 Hv. The hardness difference between the underlayer 92 and the DLC film 86 was 500 Hv.

(Experiments 2-11)
In Experiments 2 to 11, except for the conditions shown in Table 2, a DLC film 86 was formed on the base 85 in the same manner as in Experiment 1, and a die head 82 was obtained.

  Table 2 shows the length LY (mm) of the base 85 in Experiments 1 to 11, the material of the base 85, the linear expansion coefficient α1, the material of the base layer 92, the linear expansion coefficient α2, the hardness Hv1, the hardness Hv2 of the DLC film 86, The heating temperature ΔT (° C.) is shown. Hardness refers to Vickers hardness Hv.

  In Experiment 2, the length LY of the base 85 was set to 2200 mm, which was 700 mm longer than that in Experiment 1. Accordingly, the same conditions as in Experiment 1 were used except that the heating temperature ΔT in the DLC film forming step was 60 ° C. higher than that in Experiment 1 and became 240 ° C. The difference in hardness between the underlayer 92 and the DLC film 86 was 500 Hv as in Experiment 1.

  In Experiment 3, the length LY of the base 85 was 2700 mm and the material was changed to SUS329J1. Accordingly, the linear expansion coefficient α1 of the base 85 is 12 × 10 −6 / ° C., and the heating temperature ΔT in the DLC film forming process is 90 ° C. higher than the experiment 1 and 270 ° C. 1 and the same conditions. The difference in hardness between the underlayer 92 and the DLC film 86 was 500 Hv as in Experiment 1.

  In Experiment 4, the length LY of the base 85 was 3000 mm, and the material was changed to SUS630. Accordingly, the linear expansion coefficient α1 of the base 85 is 12 × 10 −6 / ° C., and the heating temperature ΔT in the DLC film forming process is 105 ° C. higher than the experiment 1 and is 285 ° C. 1 and the same conditions. The difference in hardness between the underlayer 92 and the DLC film 86 was 500 Hv as in Experiment 1.

  In Experiment 5, the length LY of the base 85 was set to 1800 mm, which was 300 mm longer than that in Experiment 1. Along with this, the heating temperature ΔT in the DLC film formation step was 20 ° C. higher than that in Experiment 1, 200 ° C., and the hardness of the obtained DLC film was 1700 Hv. The difference in hardness between the underlayer 92 and the DLC film 86 was 200 Hv lower than that in Experiment 1.

  In Experiment 6, the length LY of the base 85 was set to 1700 mm, which was 200 mm longer than that in Experiment 1. Along with this, the heating temperature ΔT in the DLC film forming process was 20 ° C. higher than that in Experiment 1, 200 ° C., and the same conditions as in Experiment 1 except that the hardness of the obtained DLC film was 1400 Hv. The hardness difference between the underlayer 92 and the DLC film 86 was −100 Hv, which is lower than that in Experiment 1.

  In Experiment 7, the length LY of the base 85 was set to 3000 mm, which was 1500 mm longer than that in Experiment 1. Accordingly, the same conditions as in Experiment 1 were used except that the heating temperature ΔT in the DLC film forming step was 105 ° C. higher than Experiment 1 and 285 ° C. The difference in hardness between the underlayer 92 and the DLC film 86 was 500 Hv as in Experiment 1.

  In Experiment 8, the length LY of the base 85 was set to 1800 mm, which was 300 mm longer than that in Experiment 1. Along with this, the heating temperature ΔT in the DLC film forming process was 20 ° C. higher than that in Experiment 1 to 200 ° C., and the same conditions as in Experiment 1 were used except that the hardness of the obtained DLC film 86 became 1100 Hv. . The hardness difference between the underlayer 92 and the DLC film 86 was −400 Hv, which was lower than that in Experiment 1.

  In Experiment 9, the same conditions as in Experiment 1 were used except that the heating temperature ΔT in the DLC film forming step was 170 ° C. and the hardness of the obtained DLC film was 2700 Hv. The hardness difference between the underlayer 92 and the DLC film 86 was 1200 Hv, which is higher than that in Experiment 1.

  In Experiment 10, the conditions were the same as in Experiment 5 except that the DLC film 86 was directly formed on the base 85 without forming the base layer 92 on the base 85.

  In Experiment 11, the same conditions as in Experiment 10 were used except that instead of the base of SUS316L in Experiment 10, a base made of a nickel-based superhard material (WC-Ni) was used.

(Evaluation)
The following evaluation was performed about the die head 82 obtained by Experiments 1-11. In Table 2, the numbers shown in the evaluation items represent the numbers given to the following evaluation items.

1. Cracks in DLC film The presence or absence of cracks in the DLC film 86 was inspected. The inspection for the presence or absence of cracks was performed using a microscope VH-900 manufactured by Keyence Co., Ltd., and observed with a magnifying lens magnified 100 times to determine the presence and length of cracks. Evaluation was made based on the following criteria depending on the presence and length of cracks.
A: There is no occurrence of cracks.
B: There is a crack, and its length is 100 μm or less.
C: There is a crack, and its length is larger than 100 μm.

2. 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 warpage amount W. The warpage amount W was evaluated based on the following criteria.
A: W is 5 μm or less.
B: W is larger than 5 μm and not larger than 15 μm.
C: W is larger than 15 μm.

3. Friction and Wear Strength of DLC Film A friction and wear test was performed on the DLC film 86. After this test, the DLC film 86 was visually observed, and the strength of the DLC film 86 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, a test piece (50 mm × 20 mm × 10 mm) obtained by cutting a part of the die head 82 was fixed on the turntable, and the turntable was rotated at a predetermined rotation speed. Next, an Al2O3 disk ball (test piece) having a ball-like tip (diameter 6.35 mm) at the position of the DLC film 86 at the tip of the die head 82, 3.0 mm away from the center of rotation. Was pressed with a predetermined load (5.0 N). The speed of the DLC film 86 at the pressing position was 0.1 m / second. The die head 82 was rotated at 20000 rpm with the disc ball pressed. Thereafter, the amount of wear of the DLC film 86 by the disc ball was measured with a surface roughness measuring instrument (Surfcom 2000DX3) manufactured by Tokyo Seimitsu Co., Ltd. The amount of wear was evaluated based on the following criteria.
A: The amount of wear is “0” and there is no wear.
B: Abrasion amount is 100 nm or less.
C: Wear amount is larger than 100 nm.

4). Evaluation of adhesion of DLC film A scratch test was performed on the DLC film 86 to evaluate the adhesion of the DLC film 86. For the scratch test, Revetest (scratch tester) manufactured by CSM Instruments was used. Evaluation was performed under the following conditions with a diamond indenter (N2-3962) having a curvature radius of 200 μm. First, the DLC film 86 is scratched at a moving speed of 10 mm / min while a diamond indenter is applied to the DLC film 86 with a load of 100 N / min. If the DLC film 86 is destroyed during this scratching, the scratch target changes from the DLC film 86 to the WC film of the underlayer 92. At this time, the friction coefficient of the DLC film 86 is 0.1, whereas the friction coefficient of the WC film is 0.4, and this change in frictional resistance is detected. When the change in the frictional resistance exceeded a certain value, it was detected that the DLC film 86 was broken. The critical load of delamination where the DLC film 86 was broken was defined as the adhesion force.

If a slight time loss occurs in calculating the coefficient of friction from the load with a scratch tester, the correct adhesion force (stress in which the DLC film 86 is broken) cannot be obtained. For this reason, when the DLC film 86 is destroyed, the elastic wave emitted at the time of destruction is detected by an AE (acoustic emission) sensor, and the time when the DLC film 86 is destroyed is recorded more accurately. Accurate adhesion data is obtained. The initial load was 0.9 N, the applied load was 100 N / min, the moving speed was 10.0 mm / min, and the sensitivity of the AE sensor was 9. In practice, it has been found that if the adhesion of the DLC film 86 is 30 N or more in this evaluation method, the DLC film 86 does not peel off and is stable. This adhesion was evaluated based on the following criteria.
A: Adhesion strength exceeds 30N.
B: Adhesion force exceeds 20N and is 30N or less.
C: Adhesive strength is 20 N or less.

  In Experiments 1, 3, and 4, the crack, warpage, strength was “A”, and adhesion was “B”. In Experiment 2, the strength was “A”, and the cracks, warpage, and adhesion were “B”. In Experiment 5, all of cracks, warpage, strength, and adhesion were “A”. In Experiment 6, the crack, warpage, and adhesion were “A” and the strength was “B”. In Experiment 7, the crack and warpage were “C”, the strength was “A”, and the adhesion was “B”. In Experiment 8, the crack, warpage, and adhesion were “A” and the strength was “C”. In Experiments 9 and 10, the crack, warpage, strength was “A”, and adhesion was “C”. In Experiment 11, all of cracks, warpage, strength, and adhesion were “A”.

  When SUS316L is used as the material of the base 85, in the case of Experiment 1 in which the base length LY is 1500 mm, the crack, warpage, and strength are all “A”, and the adhesion force is B. The evaluation tends to decrease as the base length LY increases. For example, when the base length LY is as long as 2200 mm (Experiment 2), it can be seen that the evaluation of warpage and cracks falls to “B”, and cracks of 100 μm or less are formed. Further, when the base length LY is increased to 3000 mm (Experiment 7), only the strength evaluation is “A”, the warpage and crack evaluation is “C”, and the adhesion strength evaluation is “B”.

  In Experiment 3 and Experiment 4, the base material was changed from SUS316L to SUS329J1 or SUS630. In this case, even when the base length LY was as long as 2700 mm or 3000 mm, a die head having a crack, warpage, strength of “A” and an adhesion force of B was obtained.

  Experiment 5 is the same as Experiment 1 except that the base length LY is increased by 300 mm to 1800 mm, the heating temperature of the DLC film 86 is 200 ° C., and the hardness Hv2 is 1700. In this case, the hardness difference Hv2−Hv1 between the DLC layer and the base layer 92 was 200, and a die head having cracks, warpage, strength, and adhesive strength of “A” was obtained.

  Experiment 6 is the same as Experiment 1 except that the base length LY is increased by 200 mm to 1700 mm, the heating temperature of the DLC film 86 is 200 ° C., and the hardness Hv2 is 1400. In this case, the hardness difference Hv2−Hv1 between the DLC layer and the underlayer 92 was −100, and a die head with cracks, warpage, adhesion strength “A”, and strength “B” was obtained.

  Experiment 7 is a die head having the same conditions as Experiment 4 except that the material is changed to SUS316L. In this case, a die head was obtained in which the crack and warpage were C, the strength was A, and the adhesion was B. Since cracks and warpage are C, when used as a film-forming die, there is a problem in durability, and there is a problem that streaks occur on the surface of the film formed due to peeling of the underlayer 92. There is.

  Experiment 8 is a die head having the same conditions as Experiment 5 except that the hardness Hv2 of the DLC film 86 is set to 1100. In this case, a die head having a hardness difference Hv2−Hv1 between the underlayer 92 and the DLC film 86 of −400, cracks, warpage, adhesion strength A, and strength C was obtained. Since the strength is C, there is a problem in durability when used as a film-forming die.

  Experiment 9 is a die head having the same conditions as Experiment 1 except that the hardness Hv2 of the DLC film 86 is 2700 and the heating temperature is 170 ° C. In this case, a hardness difference Hv2−Hv1 between the base layer 92 and the DLC film 86 was 1200, cracks, warpage, strength was A, and a die head with adhesion C was obtained. Since the adhesion is C, there is a problem in durability when used as a film-forming die.

  In Experiment 10, the die head was subjected to the same conditions as in Experiment 5 except that the DLC film 86 was formed directly on the base without forming the base layer 92 on the base 85. In Experiment 10, the hardness difference between the DLC film 86 and the member in contact therewith was 1800, and it was found that the adhesion was C and decreased compared to Experiment 5.

  Experiment 11 is a die head under the same conditions as Experiment 10, except that instead of the base of SUS316L in Experiment 10, a base made of a nickel-based superhard material was used. In Experiment 11, the hardness difference between the DLC film 86 and the member in contact therewith was 600, and it was found that the adhesion was A as compared to Experiment 10.

  As in Experiment 11, since the base itself is made of a super hard material without providing a base layer, stress due to thermal expansion strain between the base and the base layer does not occur when the DLC film is formed. A crack does not occur in the DLC film 86, and the adhesion force of the DLC film 86 due to the crack does not decrease. As a result, the durability of the casting die is increased and the occurrence of streak-like failures can be suppressed.

  Next, Table 3 shows the result of calculation using the numerical calculation table as to whether or not the conditions in the experiments are satisfied.

  From the results in Table 3, it can be seen that the determination result of the matching condition is consistent with the evaluation of the cracks in Experiments 1 to 9. Therefore, when manufacturing a die head, the presence or absence of cracks can be confirmed before manufacturing, depending on the material used and the combination of mechanical properties, length, etc. according to this material, leading to a decrease in yield. There is no. Further, since the generation of cracks is eliminated, the DLC film 86 is not peeled off due to aged use due to minute cracks, and a film free from the occurrence of streak-like failures can be manufactured efficiently.

DESCRIPTION OF SYMBOLS 10 Solution casting equipment 21 Casting die 29 Flow path 29o Outlet 72 Lip plate 82 Die head 85 Base 86 DLC film 92 Underlayer

Claims (6)

In a method of manufacturing a die head attached to a dope outlet of a casting die that flows out a dope containing a polymer and a solvent,
An underlayer forming step of forming an underlayer having a super hard material on a stainless steel base;
A DLC film forming step of forming a DLC film on the underlayer by vapor deposition;
In order to make the stress acting on the underlayer determined by thermal expansion strain between the base and the underlayer in the DLC film forming step less than the breaking stress of the underlayer, each line between the base and the underlayer A combination of an expansion coefficient, a length in the longitudinal direction of the base, and a heating temperature in the vapor phase film forming method is determined, and based on this combination, a crack prevention suitable condition for performing the base layer forming step and the DLC film forming step is determined. A determination step,
When the compressive force acting on the base is PB, the tensile force acting on the base layer is PL, and the cross-sectional area of the base layer in a cross section perpendicular to the longitudinal direction of the base is AL,
Stress σ1 acting on the underlayer is
A die head manufacturing method obtained by σ1 = (PB−PL) / AL. The base is an elongated column body, where LY ≧ 50 · LW when the length in the longitudinal direction is LY and the maximum length in a cross section perpendicular to the longitudinal direction is LW, and the length LY is 1500 mm or more. 2. The method for manufacturing a die head according to claim 1, wherein the thickness of the underlayer is 70 μm or more and 130 μm or less, and the thickness of the DLC film is 0.7 μm or more and 2 μm or less. 3. The method of manufacturing a die head according to claim 1, wherein the base is formed of any one of SUS316L, SUS329J1, and SUS630, and the underlayer is formed of tungsten carbide. The method of manufacturing a die head according to any one of claims 1 to 3, wherein a difference in hardness between the underlayer and the DLC film is 500 Hv or less. The die head manufacturing method according to claim 4, wherein the DLC film is formed by a vapor deposition method and has a hardness of 1300 Hv or more. 6. The method of manufacturing a die head according to claim 5, wherein the vapor deposition method is any one of ionized vapor deposition, ion plating, and plasma CVD.

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