JP4611731B2 - Manufacturing method of molded products - Google Patents

Description

  The present invention relates to a method for manufacturing a molded product made of a thermoplastic resin, and more particularly to a manufacturing method for secondary processing of a thermoplastic resin primary molded product having a rough shape such as a film or a plate shape.

  As a method for producing a molded article made of a thermoplastic resin, an injection molding method suitable for mass production is known. However, in the injection molding method, when a resin material that has been heated and melted is injection-filled into a cavity of a mold, a solidified layer is formed on the surface. Therefore, there is a limit to transfer accuracy with respect to the mold surface and thinning of a molded product.

  In order to remedy these drawbacks, a plastic base material molded in advance by injection molding or the like was inserted into the mold cavity, and this base material was heated and melted above the glass transition temperature of the base material to increase the internal pressure of the resin. Thereafter, a molding method for slowly cooling has been proposed (see Patent Document 1). In this method, since it is indispensable to cool slowly below the glass transition temperature of the base material so that the pressure and temperature are not distributed or biased, there is a disadvantage that the molding cycle is prolonged.

  As a method for avoiding such a problem, for example, by providing a bar-like or plate-like heating element or ultrasonic heating means in a mold serving as a transfer member, only the transfer surface of the base material is locally heated and melted. A transfer method has been proposed (see, for example, Patent Document 2). A method of melting only the transfer surface of the base material by high-frequency induction heating has also been proposed (see, for example, Non-Patent Document 1). According to these methods, since the resin is heated directly or indirectly in order to soften the resin surface, the heat of the heat source or the molten resin is transferred to the mold, and the temperature of the mold and the press apparatus gradually increases. To rise. For this reason, it has been difficult to accurately control the temperature uniformity over the entire surface of the molded product and the stability of the heat cycle during continuous production. Further, in the case of a molded product having a large area, the above problem is remarkable because the heat capacity of the mold increases. In other words, there has been a limit to obtaining mass productivity comparable to injection molding.

On the other hand, in recent years, attempts to apply supercritical carbon dioxide and carbon dioxide to molding processes have been extensive. Is known from Non-Patent Document 2 and the like. Further, Patent Document 3 discloses a technique in which this is applied to injection molding. In Patent Document 3, a mold filled with pressurized carbon dioxide (CO ₂ ) is filled with a molten resin in which carbon dioxide is dissolved so that carbon dioxide is impregnated into the flow front of the fluidized resin. Although a technique for suppressing the growth of a solidified layer on the mold contact surface is disclosed, this is applied to a resin in a molten state, and in the case of the present invention, it is applied to a solidified resin. Is different. In the method described in Patent Document 3, since the contact time of carbon dioxide with the resin is limited by the injection time, it is difficult to control the penetration amount of carbon dioxide on the outermost surface. In addition, when carbon dioxide is brought into a high pressure state of a supercritical state (7 MPa) or more, it becomes an obstacle to injection, so that the carbon dioxide introduced into the mold must be at a low pressure. Therefore, it was more difficult to permeate a large amount of carbon dioxide in a short time.

  Another technique for improving the transferability of a molded product using carbon dioxide is disclosed in Patent Document 4. According to Patent Document 4, the mold is once opened after injection molding, a gap is formed between the mold and the skin layer on the resin surface, and the skin layer is softened by introducing high-pressure carbon dioxide into the gap. Further, the mold pressure is transferred by increasing the resin pressure. Patent Document 4 is also applied to a molten resin in the same manner as Patent Document 3, and the entire molded product is not below the glass transition temperature. Therefore, carbon dioxide that has permeated from the skin layer surface can easily penetrate into the molten resin. Therefore, the problem peculiar to the solidified resin that the carbon dioxide staying in the gap between the resin and the mold remains undissolved does not occur.

  According to the earnest study by the present inventors, it was easy to soften the surface by allowing high-pressure carbon dioxide in a supercritical state to penetrate into a base material made of a solidified thermoplastic resin having a glass transition temperature or lower in a short time. It was. However, when the base material is simply pressed against the mold surface by a press or the like in an atmosphere filled with high-pressure carbon dioxide, problems such as swelling, local foaming, and uneven transfer occur on the surface of the molded product. It was difficult to transfer the fine shape of the mold surface. This problem was remarkable when the thickness of the base material was 1 mm or less, particularly 0.5 mm or less. This is considered to be because carbon dioxide remaining in the gap between the base material and the mold during compression was compressed and sandwiched in a high pressure state and could not penetrate into the resin by the press pressure. The thinner the base material, the smaller the absolute amount of carbon dioxide that can penetrate, and it becomes difficult to exhaust the undissolved carbon dioxide from the gap between the base material and the mold.

If the pressure of carbon dioxide is lowered, the density is lowered and a gas body is formed, and thus the above problem can be avoided. However, the permeation time of carbon dioxide becomes long, and continuous mass production is difficult. Furthermore, by increasing the pressing pressure between the base material such as the pressing pressure and the resin, there is a problem that the problem can be avoided to some extent or the energy efficiency is poor.
JP-A-4-163119 JP 2002-36355 A JP 2001-62862 A JP 2002-52583 A Technical Lecture Sponsored by Plastic Industry Technology Research Group "Trends in Latest Recording Media and Materials / Molding Technology" Preliminary Book P3-30-31,2004 J. et al. APPl. PolyM. Sci. "Vol. 30, 2633 (1985)

  The present invention has been made in view of the above circumstances, and a first object is to provide a method for producing a molded product with high mass productivity. The second object is to provide a method for producing a molded product capable of obtaining good transferability.

  In order to achieve the above object, a molding method according to an exemplary aspect of the present invention includes inserting a base material made of a thermoplastic resin into a cavity formed from a mold having a transfer surface, and transferring the mold. In a method for molding a thermoplastic resin in which the shape of a mold transfer surface is transferred to a base material by pressing the surface against the surface of the base material, the base material contains at least carbon dioxide in the vicinity of the surface, and the glass transition of the base material It is characterized by pressing a mold transfer surface having a temperature lower than the temperature. Since carbon dioxide softens the transfer surface, temperature control can be performed at a constant level without increasing the temperature of the entire base material, so that mass productivity is improved.

  In the present invention, the timing at which carbon dioxide permeates the surface of the base material is arbitrary, and it may be performed within the molding cycle or may be permeated in advance by pretreatment.

  It is desirable that the mold surface temperature of the transfer surface be in the range of 5 ° C. to 100 ° C. lower than the glass transition temperature of the base thermoplastic resin. If the temperature of the resin is higher than this range, it becomes difficult to suppress mechanical deformation of the base material, and if it is low, carbon dioxide hardly penetrates and mass productivity decreases. More desirably, the mold surface temperature is controlled within a range of 10 ° C. to 50 ° C. lower than the glass transition temperature of the base material. In the present invention, the glass transition temperature of the thermoplastic resin is defined as a physical property of a bulk material that does not include a softening material, a plasticizer, a gas body, and the like.

  In the present invention, the base material may be a thermoplastic resin film having a thickness of 1 mm or less. Furthermore, it is desirable that the thickness is 0.5 mm or less, which is difficult to mold by injection molding or the like. More desirably, the film has a thickness of 0.2 mm or less. Further, for example, the light guide plate or the like may have a large area of 15 inches or more. The thin-walled and large-area precision molding characteristics that are difficult to achieve by injection molding can be utilized.

  According to another aspect of the present invention, there is provided a molding method in which carbon dioxide preliminarily adjusted in a temperature range of 50 ° C. to 250 ° C. and a pressure of 1 to 25 MPa in a mold cavity in which a base material made of the thermoplastic resin is inserted. By introducing the carbon dioxide, carbon dioxide is infiltrated into at least the transfer side surface of the base material. The temperature and pressure are of course considered from the viewpoint of a plasticizer for the base material, but are preferably optimized from the following viewpoints. That is, a change in mold temperature when introduced into the mold. It is desirable that the temperature difference of carbon dioxide from the mold is small so that the surface temperature of the mold is not greatly affected, and it is desirable that the temperature difference is in the range of 100 ° C. or less.

  V1 / V2, which is a ratio between the internal volume V1 of the container for preliminarily pressurizing and controlling the carbon dioxide and the internal volume V2 of the mold cavity filled with carbon dioxide in which the base material made of the thermoplastic resin is inserted, is 0. It is desirable that it is in the range of 5 or more and 20.0 or less. If it is smaller than this range, the temperature of carbon dioxide may be drastically lowered due to adiabatic expansion when the mold is introduced, and further, it may be liquefied. As a result, there arises a problem of depriving the mold and base material of heat. In addition, if it is larger than this range, a problem occurs particularly under the following conditions. In other words, when the temperature of carbon dioxide that has been pressurized and adjusted in advance is lower than the surface temperature in the cavity, the pressure of the carbon dioxide introduced into the cavity suddenly becomes high and the pressure rises. Pressure control including the inside becomes difficult.

  Further, the inner diameter and / or the outer diameter may be cut while the base material is vacuum-adsorbed. In particular, this method is suitable for manufacturing a disc-shaped information recording medium such as an optical disk.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of a molded product with high mass-productivity and the manufacturing method of the molded product which can obtain favorable transcription | transfer property can be provided.

Example 1.
The method for producing a molded product relating to Example 1 of the present invention is used particularly for the production of optical lenses, plastic mirrors, optical parts such as light guide plates and microlens arrays, and information media such as optical disks.

  Hereinafter, the shaping | molding apparatus and shaping | molding method concerning the present Example 1 are demonstrated using FIGS. In addition, there is a space where excess carbon dioxide stays in addition to the space inside the mold where the base material made of thermoplastic resin is inserted, and these are collectively referred to as a cavity.

  1 to 4 are block diagrams illustrating a schematic configuration of the molding apparatus according to the first embodiment. The molding apparatus includes a toggle press mechanism 101 that can be driven by an electric servo motor (not shown) and can be controlled in position, a high-pressure carbon dioxide supply unit 102, and a press unit 103 for molding. 1 is a schematic cross-sectional view of the entire apparatus, FIG. 2 is a cross-sectional view of the main part of the press unit 103, and FIGS. 3 and 4 are schematic views from above the press unit 103.

  In the present invention, a method for allowing carbon dioxide to permeate the surface of the base material or the whole is arbitrary. For example, a method of controlling the temperature in a container separate from the mold to a temperature lower than the glass transition temperature of the base material in advance and filling high pressure carbon dioxide, and retaining the base material in the container for a long time Can be applied.

  Further, a method of allowing carbon dioxide to permeate the base material in a continuous manner in a short time in the mold cavity can also be applied. In this example, the latter method was adopted, and carbon dioxide held in the high-pressure tank 6 controlled in temperature and pressure was infiltrated into the mold cavity 2 in the press unit 103 in a sealed state.

  During the molding period in which the mold surface shape is transferred to the base material sheet 1, the inside of the mold cavity 2 is preferably sealed (sealed) with carbon dioxide. The method of sealing the high-pressure carbon dioxide filled in the mold cavity 2 is arbitrary, but mechanically, rather than applying a reaction force higher than the pressure of the carbon dioxide by a driving source such as a press mechanism and sealing. Fixing and sealing is preferable because energy consumption can be reduced.

  In the first embodiment, the press unit 103 employs a structure capable of sealing high-pressure carbon dioxide up to 25 MPa by the following known method employed in a supercritical dyeing high-pressure vessel or the like, and performs sealing as follows. It was.

  First, as shown in FIG. 3, the upper lid 20 holding the stamper 3 having a finely structured transfer surface is inserted into the lower press unit 21 so that the gear 19 is fitted, and then, as shown in FIG. The upper lid was rotated 45 degrees. The upper lid 20 is provided with four gears 19 radially projecting outward at 90 ° intervals. The lower press unit 21 has a recess corresponding to the outer shape of the upper lid 20 at the center, and a recess into which the gear 19 of the upper lid 20 is fitted is provided on the inner surface of the recess. The lower press unit 21 is formed with a hollow portion hollowed in a columnar shape having a diameter equal to or larger than the outermost diameter of the gear 19 of the upper lid 20, and the gear 19 of the upper lid 20 rotates in this hollow portion. It is positioned at the position.

  As shown in FIG. 2, an O-ring 4 is inserted into a recess provided on the outer periphery of the upper lid 20. By bringing the O-ring 4 and the inner wall seal surface 5 in the lower press unit 21 into close contact with each other, the sealing performance is maintained. The upper lid 20 is moved up and down by driving a piston connected to an air cylinder (not shown). The upper lid 20 can be rotated by the operator holding and rotating the handle 28.

  As shown in FIG. 1, the high-pressure carbon dioxide supply unit 102 includes a carbon dioxide cylinder 18, a pump 9, a pressure reducing valve 10, a pressure gauge 11, a pressure reducing valve 12, a pressure gauge 13, a stop valve 14, and air operated valves 15 and 16. The check valve 17 and the high-pressure tank 6 are provided. Of these, the air operated valves 15 and 16 can be automatically controlled by turning on and off the solenoid valves. The air operated valve 15 is for introduction into the press unit 103, and the air operated valve 16 is for discharge. The air operated valves 15 and 16 can be automatically operated in conjunction with the toggle press mechanism 101.

  The carbon dioxide supplied from the carbon dioxide cylinder 18 is pressurized by the pump 9, and the pressure is adjusted by the pressure reducing valve 10 so that the display of the pressure gauge 11 becomes P. The carbon dioxide whose pressure has been adjusted is maintained at an arbitrary temperature and pressure P in the high-pressure tank 6. In the present invention, the temperature and pressure P of carbon dioxide introduced into the mold cavity are preferably adjusted to the ranges of 50 ° C. to 250 ° C. and 1 to 25 MPa, respectively. The pressure P was 15 MPa.

  In the present invention, V2 / V1, which is the volume ratio of the volume V2 of the high-pressure tank that preliminarily adjusts the pressure and temperature of carbon dioxide and the internal volume V1 in the mold cavity into which carbon dioxide is introduced, is 0.5 to 20. It is desirable that it is 0 or less. In this embodiment, the internal volume V2 in the high-pressure tank 6 is 2.0 liters, the internal volume V1 of the mold cavity 2 when introducing carbon dioxide is 1.5 liters, and V2 / V1 = 1.3. did.

  The lower press die 7 is held in a state of being movable in the vertical direction in a hollow portion provided in the central portion of the lower press unit 21. A sealed cylinder 8 is formed between the lower surface of the lower press die 7 and the lower press unit 21. The closed cylinder 8 in the lower press unit 21 is always filled with carbon dioxide whose pressure gauge 13 is adjusted to 6 MPa by the pressure reducing valve 12 by opening the stop valve 14. For this reason, the lower press die 7 is pushed upward by the sealed cylinder 8 and is always in a raised position when the mold cavity 2 is not filled with carbon dioxide.

  When 8 MPa of carbon dioxide is filled in the mold cavity 2, the rising pressure of the lower press mold 7 by the sealed cylinder 8 and the descending pressure of carbon dioxide on the entire upper surface of the lower press mold 7 are balanced. Set. With such a mechanism, the pressing force by the toggle press mechanism 101 does not require an excessive driving force even when the carbon dioxide filled in the cavity becomes a high pressure. The lower press die 7 is guided by a guide post 31 with respect to the lower press unit 21.

  In the present invention, the form of the molded product as the base material is arbitrary. Further, as the molding method of the base material, known injection molding, injection compression molding, compression molding, transfer molding, extrusion molding, casting, or the like can be selected. In this example, a film obtained by extrusion molding with a thickness of 0.4 mm and 500 × 800 mm □ was used.

  In the present invention, the type of thermoplastic resin used as a base material is arbitrary, and polycarbonate, polymethyl methacrylate, alicyclic olefin resin, polyetherimide, polymethylpentene, amorphous polyolefin, polytetrafluoroethylene, liquid crystal Polymer, styrene resin, polyethylene, polymethylpentene, polyacetal, polyamide resin, polyimide, polyamideimide, polyphenyl sulfone, polyether sulfone, aromatic polyester, biodegradable plastic, and the like can be selected. Further, various copolymers and blend materials of these materials may be used, and various additives such as fillers may be contained. In this example, polycarbonate having a glass transition temperature of 145 ° C. was used.

  The holding method of the base material in the mold cavity in the present invention is arbitrary, but in the present example, it was performed as follows. First, as shown in FIG. 2, the base material sheet 1 was placed on the lower mirror plate 25 on the lower press die 7. Here, the vacuum suction groove 23 is provided in a rectangular shape on the surface of the lower mirror plate 25. The vacuum suction groove 23 is connected to one end of the suction hole 22. A vacuum pump (not shown) installed outside the press unit 103 is provided on the other end side of the suction hole 22. The base material sheet 1 is installed on the vacuum suction groove 23. Therefore, when sucked by the vacuum pump, the base material sheet 1 is sucked to the flat upper surface of the lower mirror plate 25 through the suction holes 22 and the vacuum suction grooves 23. In this way, the base material sheet 1 is firmly fixed to the upper surface of the lower mirror surface plate 25.

  In the present invention, the form of the mold surface to be transferred to the base material sheet 1 is arbitrary, but in this embodiment, the transfer pattern has a φ100 μm and a height of 50 μm provided on a 0.3 mm thick Ni stamper 3. A microlens pattern with dense lenses was formed. The Ni stamper 3 was fixed to the upper mirror plate 26 by the stamper holding member 54. In order to release the gas staying on the stamper and the mirror back surface from the outer periphery of the stamper, the mold of this embodiment has an exhaust path (not shown) connected to the exhaust hole 541 (see FIG. 7) in the stamper holding member 54.

  In the present invention, the temperature control method and set temperature of the base material and the transfer mold are arbitrary, but in this embodiment, the temperature is adjusted to 125 ° C. in the upper and lower temperature control circuits 24 and 27 as shown in FIG. The adjusted aqueous medium was circulated in a pressurized state by a temperature controller to control the surface temperature of the lower mirror plate 25 and the stamper 3 to be 120 ° C. This temperature of 120 ° C. is a temperature obtained by subtracting 25 ° C. from the glass transition temperature of the base material. The entire upper lid 20 and the outside of the lower press mold 7 constituting the press piston inside the lower press unit 21 are temperature-controlled at 120 ° C. by a heater (not shown).

  In the present invention, when high-pressure carbon dioxide is introduced into and discharged from the cavity, the temperature in the cavity may change due to compression and release of the gas in the cavity. Therefore, it is desirable to control the temperature of the entire mold to suppress the temperature change of the mold due to the flow of carbon dioxide.

  Next, the molding process in the present embodiment will be described. First, the base material sheet 1 was tightly fixed to the lower mirror surface plate 25 by the method described above. Thereafter, as shown in FIG. 5, the upper lid 20 was inserted so that the gear 19 was fitted in the cavity of the lower press unit 21. When the gear 19 was completely inserted into the cavity of the lower press unit 21 as shown in FIG. 6, the upper lid 20 was rotated 45 degrees. When the upper lid 20 starts to rotate, the seal works, and at the same time, the air operated valve 15 shown in FIG. 1 is opened. As a result, the carbon dioxide in the high-pressure tank 6 was introduced into the mold cavity 2.

  FIG. 7 is an enlarged view of part A of FIG. 6, and FIG. 8 is an enlarged view of the interface of the stamper 3. When the pressure in the mold cavity 2 reaches 8 MPa or more due to the introduction of carbon dioxide, the lower press mold 7 is pushed back by the pressure of carbon dioxide on the upper surface, that is, descends. In this example, the distance between the cavities was controlled by bringing the upper surface of the toggle press mechanism 101 shown in FIG. 1 into contact with the pressing surface 29 of the lower press die 7. In this embodiment, the distance between the cavities in the state where the base material sheet 1 and the stamper 3 are in close contact with each other is set to zero.

  In the present invention, it is desirable to introduce carbon dioxide into the mold cavity in a state where the gap between the base material made of the plastic resin and the mold transfer surface is kept within 5 mm. When high-pressure and high-density carbon dioxide stays between the base material and the stamper, if the gap is wide, it becomes difficult to quickly discharge excess carbon dioxide from the transfer surface of the base material and the stamper. In particular, when the base material has a large area and is thin, it is difficult to quickly discharge excess carbon dioxide from the transfer surface of the base material and the stamper. Here, it is possible to avoid this problem to some extent by slowing down the press speed at which the base material and the stamper are brought into contact, but this leads to cycle up.

  In this embodiment, the position of the toggle press mechanism 101 is controlled at the moment when the lower press die 7 is retracted so that the distance between the cavities (that is, the distance between the stamper 3 and the base material sheet 1) becomes 0.2 mm. The press force was increased in accordance with the gas pressure in the mold cavity 2. The gas pressure inside the cavity 2 was monitored by a gas pressure sensor in the mold (not shown).

  FIG. 10 shows a process time chart of gas pressure, pressing force, and distance between cavities in this example. In FIG. 10, the horizontal axis represents time, and the vertical axis represents the pressure in the cavity, the pressing force, or the distance between the cavities. As shown in FIG. 10, the press force is increased 3 seconds after the pressure in the cavity starts to increase. As the press force increases, the lower press die 7 is momentarily retracted by the gas pressure, but the press force increases accordingly, and the distance between the cavities is kept constant. In this example, the distance between the cavities was maintained at 0.2 mm for about 6 seconds to about 16 seconds.

  Next, after holding the distance between cavities of 0.2 mm for about 10 seconds, the pressing force was increased, and transfer was performed as shown in FIG. During the pressing for 20 seconds, the air operated valve 16 was opened, and carbon dioxide was released from the cavity 2. Thereafter, the pressing force was released, and the base material sheet 1 and the stamper 3 were peeled off. Further, after removing the upper lid 20, the molded product was taken out.

  The molded film produced by the molding method according to this example had a thickness change of 1 μm or less, and the microlens pattern of the stamper 3 was well transferred over the entire surface.

  As described above, it is desirable to introduce carbon dioxide into the mold cavity with the gap between the base material made of thermoplastic resin and the mold transfer surface maintained within 5 mm. More desirably, it is 1 mm or less. More desirably, it is 100 μm or less. If the gap between the base material and the mold transfer surface is wider than this, the amount of excess carbon dioxide that does not dissolve in the base material will increase, and when pressing the transfer surface with a press or the like, it is difficult to exhaust with a low-pressure press force. Become. In addition, the narrower the gap, the less the absolute amount of carbon dioxide introduced is economical.

  Further, when the mold transfer surface is pressed against a base material made of a thermoplastic resin, there is a surface where the mold does not partially contact the base material at least until the transfer is completed, and carbon dioxide contacts the surface. It is desirable to have. At the time of pressing by a press or the like, excess carbon dioxide can be efficiently exhausted from the non-contact portion.

  Further, the transfer surface of the mold has fine irregularities, and the base material and the mold transfer surface are brought into contact with each other in a carbon dioxide atmosphere at a low pressure P1 of 10 MPa or less, more preferably 7 MPa or less. preferable. When carbon dioxide is in a low pressure state, the fine irregularities of the base metal and the mold are brought into close contact with each other, so that the excess carbon dioxide is close to a low-density gas. It becomes easy. Further, it is considered that plasticity of the base material surface is promoted because carbon dioxide is compressed and stays in contact with the resin in a high pressure state on the unevenness of the mold surface. The pressure P1 of carbon dioxide when the mold transfer surface and the base material are in contact with each other is preferably 1 to 10 MPa, more preferably 1 to 7 MPa.

  Further, it is desirable that the pressure P2 of carbon dioxide in contact with the base material is set to a high pressure equal to or higher than P1 after contacting carbon dioxide and the unevenness of the mold. P2 is desirably in a supercritical state of 7 MPa or more, and more desirably 10 MPa or more. It can be expected that carbon dioxide in a supercritical state having a high penetrability and a large plasticizer effect penetrates from the entire surface of the base material through fine unevenness existing on the surface of the base material and the mold and improves transferability. Moreover, after making the carbon dioxide which touches a base material into a high voltage | pressure, the transcription | transfer property can be improved more by raising the pressing force of the base material and metal mold | die in press etc. further. Thereafter, the base material can be cooled and solidified by exhausting carbon dioxide from the mold.

  Carbon dioxide may contain alcohol. By containing an alcohol such as ethanol, the plasticizer effect on the resin as the base material is dramatically improved. The mixed concentration of ethanol is preferably about 1 to 10%.

Example 2
A molding apparatus and a molding method according to Example 2 will be described with reference to FIGS. FIG. 11 is a block diagram showing a schematic configuration of the molding apparatus according to the present embodiment, and FIG. As in the first embodiment, the apparatus configuration in this embodiment includes a toggle press mechanism 101, a high-pressure carbon dioxide supply unit 102, and a molding press unit 103.

  In addition to the molding apparatus according to the first embodiment, a carbon dioxide exhaust air operated valve 34, an air operated valve 35, and a vacuum pump 36 communicating with the exhaust holes 38 and 39 of the lower press die 7 are added.

  In addition, a discharge hole 56 connected to the check valve 57, the air operated valve 58, and the exhaust air operated valve 16 is provided to supply carbon dioxide for raising the press to the sealed cylinder 8.

  In this embodiment, the internal volume V2 in the high-pressure tank 6 is 30 ml, the cavity internal volume V1 when introducing carbon dioxide is 15 ml, and V2 / V1 = 2.0. The internal volume V2 in the high-pressure tank 6 was reduced by inserting a metal member therein.

  In the present embodiment, a film made of polycarbonate having an outer diameter of φ130 mm and a plate thickness of 0.1 mm is used as the base material sheet 1, and a pattern having land grooves of an optical disk as a disk-shaped information storage medium on a transfer surface of a mold. The formed Ni stamper 3 was used. The stamper 3 used was formed with a pattern having a groove width (WG) of 0.17 μm, a land width (WL) of 0.12 μm, and a track pitch (W) of 0.32 μm. Disc recognition information, address information, and the like can be recorded in advance by meandering grooves or prepits.

  As shown in FIG. 12, the stamper 3 was held on the upper mirror plate 26 by the inner diameter holding member 40 and the outer diameter holding member 44. Both holding members 40 and 44 are provided with exhaust holes 401 and 441 for exhausting carbon dioxide retained in the gap between the stamper 3 and the base material sheet 1.

  The base material sheet 1 is fixed by a clamp member 45 on a film plate 37 that is removable from the mold. In advance, the film plate 37 was heated and adjusted to 120 ° C. by external setup with the base material sheet 1 fixed. A projection 41 is formed in the center of the lower surface of the film plate 37 so as to fit into a tapered recess 40 provided on the lower receiving plate 55.

  Next, as shown in FIG. 13, the film plate 37 whose temperature has been adjusted is set on the lower plate 55. In the set state, the protrusion 41 is fitted in the tapered recess 40. As will be described later, since the inner and outer diameters of the base material sheet 1 are cut during transfer molding, an inner peripheral suction groove 49 and an outer peripheral suction groove 46 for fixing the base material sheet 1 to the film plate 37 at that time are circular. It is dug around. Both suction grooves 46 and 49 are connected by a through hole 47 and further connected to an exhaust hole 39. A spring 42 and a check ball 43 are built in the central portion of the lower surface of the film plate 37 where the protrusion 41 is provided.

  Thus, after the mold is opened to the atmosphere, the base sheet 1 is vacuum-held between the inner peripheral suction groove 49 and the outer peripheral suction groove 46 with a suction force stronger than the spring force of the spring 42. Even when the plate 37 is removed from the lower receiving plate 55, the check ball 43 is pressed against the film plate 37 by the spring force of the spring 42.

  Therefore, the inside of the suction grooves 46 and 49 is maintained at a negative pressure, and the base material sheet 1 does not peel from the film plate 37. As a result, the thin film-like base material sheet 1 can be easily handled integrally with the high-strength film plate 37. For example, an organic dye material or the like can be spin-coated on the base material sheet 1 while being held on the film plate 37.

  In Example 2, the temperature control of the mold and the pressurization temperature control of carbon dioxide were performed in the same manner as in Example 1. Moreover, shaping | molding was performed as follows.

  First, the upper lid 20 shown in FIG. 11 was inserted into the lower press unit 21 and rotated to be in a sealed state. Then, the toggle press mechanism 101 shown in FIG. 11 was brought into contact with the pressing surface 29 on the lower surface of the lower press die 7 to set the distance between the cavities to 0.2 mm.

  Next, the air operated valves 15 and 58 were opened, and carbon dioxide having the same pressure as in Example 1 was introduced into the mold cavity 2 and the sealed cylinder 8. During the introduction of carbon dioxide, the toggle press mechanism 101 was brought into contact with the pressing surface 29 on the lower surface of the lower press die 7 to maintain the distance between the cavities at 0.2 mm.

  FIG. 14 is a schematic diagram showing the structure in the mold cavity 2 during the introduction of carbon dioxide. And the enlarged view of each outer peripheral part A part and inner peripheral part B part in FIG. 14 is shown in FIG. 15, FIG.

  In this example, carbon dioxide was permeated from both surfaces of the base material sheet 1. Of course, it is possible to transfer on both sides by permeating from both sides, and it is possible to reduce warpage due to post-shrinkage. As shown in FIGS. 14 and 15, carbon dioxide is introduced into and discharged from the base material sheet 1 on the stamper surface side. First, the slit 51 provided on the outer periphery of the upper mirror plate 26 and the inside of the outer diameter holding member 44 leading to the slit 51 are provided. From the exhaust hole 441. Further, carbon dioxide can be similarly introduced and discharged from the gap between the outer diameter cutting teeth 52 and the base material sheet 1 provided on the outer diameter holding member 44 shown in FIG.

  Carbon dioxide is introduced into the base material sheet 1 on the side opposite to the stamper surface from the introduction hole 48 in FIGS. The introduction hole 48 is a through hole that penetrates the upper surface and the side surface of the film plate 37. On the upper surface of the film plate 37 on which the base material sheet 1 is placed, a hollow portion wider than the hole diameter of the introduction hole 48 is formed, and the hollow portion and the introduction hole 48 are connected. The discharge of carbon dioxide from the vicinity of the base material sheet 1 is also performed from the inner peripheral suction groove 49 and the outer peripheral suction groove 46.

  In the present invention, it is desirable to bring the base material sheet and the mold transfer surface into contact with each other in a carbon dioxide atmosphere at a low pressure P1 of 10 MPa or less. However, in this embodiment, the carbon dioxide pressure P1 in the mold cavity 2 is used. When the pressure reached 5 MPa, the pressing force was increased so that the distance between the cavities became zero, and the base material sheet 1 was pressed against the stamper 3.

  In the present invention, it is desirable to set the pressure P2 of carbon dioxide to a high pressure equal to or higher than P1 after the base material sheet and the uneven surface of the mold are in contact with each other. , After the contact between the base material sheet 1 and the stamper 3, the pressure of carbon dioxide was increased to a predetermined pressure of 16 MPa over about 6 seconds.

  In the present invention, it is desirable to further increase the pressing force between the base material sheet and the mold after increasing the pressure of carbon dioxide in contact with the base material sheet to improve transferability. FIG. 20 shows a time chart of the process in this example. In FIG. 20, the horizontal axis represents time, and the vertical axis represents the pressure in the cavity, the pressing force, or the distance between the cavities. As shown in FIG. 20, while the base material sheet 1 and the stamper 3 were brought into close contact with each other, the pressure of carbon dioxide was increased as described above, and the pressing force was increased at an arbitrary timing.

  In this example, the inner and outer diameters of the base material sheet 1 were cut by the inner diameter cutting teeth 53 and the outer diameter cutting teeth 52 as shown in FIG. 17 while bringing the base material sheet 1 and the stamper 3 into close contact. As shown in FIG. 16, the inner diameter cutting teeth 53 are formed by projecting at an acute angle from the surface of the inner diameter holding member 40 opposite to the surface holding the stamper 3 toward the base material sheet 1 side. As shown in FIG. 15, the outer diameter cutting teeth 52 are formed by projecting at an acute angle from the surface opposite to the surface that holds the stamper 3 in the outer diameter holding member 44 to the base material sheet 1 side. . These inner diameter cutting teeth 53 and outer diameter cutting teeth 54 are continuously formed in a circular arc shape at positions corresponding to the inner periphery and outer periphery of the optical disk.

  The maximum pressing force was maintained for about 9 seconds. After maintaining the carbon dioxide at a high pressure for a certain time, the air operated valves 16 and 34 shown in FIG. 11 were opened to discharge the carbon dioxide.

  After the inside of the mold cavity 2 is opened to the atmosphere, the air operated valve 34 is closed, the air operated valve 35 is opened, and the vacuum pump 36 sucks the base material sheet 1 from the inner peripheral suction groove 49 and the outer peripheral suction groove 46. The film plate 37 was tightly fixed. Further, after releasing the press pressure and opening the cavity, the upper lid 20 was removed in the same manner as in Example 1. When the pattern of the molded film in this example was observed using an atomic force microscope (AFM), it was found to be well transferred.

  There are two possible transfer mechanisms for the molding method in the present invention. This point will be described with reference to FIGS. 18 and 19, which are enlarged views of part A of FIG.

  First, as shown in FIG. 18, it is conceivable that high-pressure carbon dioxide permeates the surface of the film and softens through the fine spiral land groove shape on the surface of the stamper 3 as shown in FIG. Then, the transfer is completed as shown in FIG. 19 in a state where the glass transition temperature is lowered only on the outermost surface.

  On the other hand, when the low-pressure carbon dioxide is retained, the stamper and the base material sheet are brought into contact with each other, so that the compressed high-pressure carbon dioxide is retained on the fine stamper pattern to promote plasticization. Conceivable.

[Comparative Example 1]

  Using the same apparatus as in Example 2, molding was performed under the same conditions as in Example 1 except that the distance between the base material sheet 1 and the stamper 3 in the initial cavity was set to 10 mm. In the molded product in this comparative example, a part of the foamed part and a place where the pattern was not transferred occurred. It is considered that this is because the amount of carbon dioxide retained between the base material sheet 1 and the stamper 3 increased, and the surplus portion could not be discharged during pressing. This problem could not be solved unless the distance was within 5 mm.

1 is a block diagram illustrating a schematic configuration of a molding apparatus according to a first embodiment. 1 is a cross-sectional view illustrating a schematic configuration of a molding apparatus according to a first embodiment. FIG. 3 is a top view illustrating a part of the molding apparatus according to the first embodiment. FIG. 3 is a top view illustrating a part of the molding apparatus according to the first embodiment. It is the block diagram which expanded a part of shaping | molding apparatus concerning the present Example 1. FIG. It is the block diagram which expanded a part of shaping | molding apparatus concerning the present Example 1. FIG. It is the block diagram which expanded a part of shaping | molding apparatus concerning the present Example 1. FIG. It is the block diagram which expanded a part of shaping | molding apparatus concerning the present Example 1. FIG. It is the block diagram which expanded a part of shaping | molding apparatus concerning the present Example 1. FIG. 3 is a process time chart of gas pressure, pressing force, and distance between cavities in Example 1. It is a block diagram which shows schematic structure of the shaping | molding apparatus which concerns on the present Example 2. FIG. It is the block diagram which expanded a part of shaping | molding apparatus which concerns on the present Example 2. FIG. It is the block diagram which expanded a part of shaping | molding apparatus which concerns on the present Example 2. FIG. It is the block diagram which expanded a part of shaping | molding apparatus which concerns on the present Example 2. FIG. It is the block diagram which expanded a part of shaping | molding apparatus which concerns on the present Example 2. FIG. It is the block diagram which expanded a part of shaping | molding apparatus which concerns on the present Example 2. FIG. It is the block diagram which expanded a part of shaping | molding apparatus which concerns on the present Example 2. FIG. It is a figure for demonstrating the mechanism of the shaping | molding method which concerns on the present Example 2. FIG. It is a figure for demonstrating the mechanism of the shaping | molding method which concerns on the present Example 2. FIG. It is a process time chart of the gas pressure, the press force, and the distance between cavities in the present Example 2.

Explanation of symbols

1 Base material sheet 2 Mold cavity 3 Stamper 4 Ring
5 inner wall sealing surface, 6 high pressure tank, 7 lower press mold, 8 sealed cylinder,
9 Pump, 10 Pressure reducing valve, 11 Pressure gauge, 12 Pressure reducing valve, 13 Pressure gauge,
14 Stop valve, 15, 16 Air operated valve,
17 check valve, 18 carbon dioxide cylinder, 19 gear,
20 Upper lid, 21 Lower press unit, 22 Suction hole,
23 Vacuum suction groove, 24, 27 Temperature control circuit, 25 Lower mirror plate,
26 upper mirror plate, 28 handle, 31 guide post,
33 Upper lid, 34 Air operated valve, 35 Air operated valve,
36 vacuum pump, 37 film plate, 38 exhaust hole,
39 exhaust hole, 40 inner diameter holding member, 41 protrusion, 42 spring,
43 Check ball, 44 Outer diameter holding member, 45 Clamp member,
46 outer periphery suction groove, 47 through hole, 48 introduction hole, 49 inner periphery suction groove,
51 slits, 52 outer diameter cutting teeth, 53 inner diameter cutting teeth,
54 stamper holding member, 55 base plate, 56 discharge hole,
57 check valve, 58 air operated valve, 101 toggle press mechanism,
102 high-pressure carbon dioxide supply unit, 103 press unit.

Claims (12)

A base material made of a thermoplastic resin is inserted into a cavity formed from a mold having a transfer surface, and the shape of the mold transfer surface is changed by pressing the transfer surface of the mold against the surface of the base material. A method of manufacturing a molded product to be transferred to
Contacting the base material with low-pressure carbon dioxide of 7 Mpa or less at least near the surface;
Pressing a mold transfer surface having a temperature lower than the glass transition temperature of the base material against the base material;
After the mold transfer surface is brought into close contact with the base material, the carbon dioxide that has been boosted to a high pressure of 7 Mpa or more in the state where the mold transfer surface is in close contact with the base material. And a step of containing the molded article.   2. The method for manufacturing a molded product according to claim 1, wherein the metal transfer surface is brought into contact with the base material when the low-pressure carbon dioxide of 7 MPa or less is in contact with the base material.   The method for producing a molded product according to claim 2, further comprising a step of increasing a pressing force of the mold transfer surface against the base material in the process of containing the carbon dioxide in the base material. .   The molded article according to claim 3, wherein the pressing force of the mold transfer surface against the base material is increased in the process of containing the high-pressure carbon dioxide of 7 Mpa or more to the base material. Method.   The method for producing a molded article according to any one of claims 1 to 4, wherein the step of bringing the carbon dioxide into contact makes carbon dioxide contact with a base material disposed in the cavity. The step of contacting the carbon dioxide includes:
Adjusting the carbon dioxide to a temperature of 50 ° C. to 250 ° C. and a pressure of 1 to 7 MPa;
The method for producing a molded article according to claim 5, further comprising a step of introducing the adjusted carbon dioxide into a cavity into which the base material is inserted.   V1 / V2, which is the ratio of the internal volume V1 of the container that performs temperature adjustment and pressurization to the carbon dioxide and the internal volume V2 of the mold cavity into which the base material is inserted, is 0.5 or more and 20.0. It is the following ranges, The manufacturing method of the molded article of Claim 5 or 6 characterized by the above-mentioned.   The surface temperature of the mold on the transfer surface is in the range of 5 ° C to 100 ° C lower than the glass transition temperature of the thermoplastic resin of the base material. The manufacturing method of the molded article as described in 2.   The method for producing a molded product according to any one of claims 1 to 8, wherein the base material is made of a thermoplastic resin film having a thickness of 1 mm or less.   The said carbon dioxide contains alcohol, The manufacturing method of the molded article as described in any one of Claims 1-9 characterized by the above-mentioned. 11. The method according to claim 1, further comprising a step of cutting the base material in association with an inner diameter and / or an outer diameter of an optical disc in a state where the sheet-shaped base material is vacuum-adsorbed. The manufacturing method of the molded article of description.   12. The method of manufacturing a molded product according to claim 11, wherein the molded product is a disk-shaped information recording medium.

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