JP2007216481A - Method and apparatus for manufacturing resin sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a resin sheet reduced in warpage after molding even in a case relatively large in wall thickness, capable of being formed into a desired cross-sectional shape and especially suitable for use in the light guide plate arranged to the back of a display device of every kind or an optical element of every kind. <P>SOLUTION: The sheetlike resin material 14 extruded from a die 12 is held under pressure between a mold roller 16 rotated at a peripheral speed V1 and the nip roller 18 arranged in opposed relation to the mold roller to transfer the surface uneven shape of the mold roller to the resin material and the resin material after transfer is wound around the peel roller 24 arranged in opposed relation to the mold roller to be peeled from the mold roller while the peeled resin sheet is fed while held under pressure on the downstream side of the peel roller by a first draw roller 32 rotated at a peripheral speed V2, which is 102-107% of the peripheral speed V1, and the second draw roller 34 arranged in opposed relation to the first draw roller. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a resin sheet manufacturing method and apparatus, and more particularly to a resin sheet manufacturing method and apparatus suitable for use in a light guide plate and various optical elements disposed on the back surface of various display devices.

  As resin sheets used for various optical elements, Fresnel lenses, lenticular lenses, and the like are used in various fields. A regular uneven shape is formed on the surface of such a resin sheet, and this uneven shape exhibits optical performance as a Fresnel lens or a lenticular lens.

  As a method for producing such a resin sheet, various proposals have been made so far (see Patent Document 1, etc.). In these proposals, the roller molding method is adopted from the viewpoint of improving productivity.

  A typical roller forming method of these prior arts is configured as shown in FIG. This apparatus configuration includes a sheet die 2 for shaping a resin material 1 melted by an extruder (not shown) into a sheet shape, a stamper roller 3 having an uneven surface formed thereon, and a stamper roller 3. And a mirror roller 4 for peeling, which is disposed opposite to the mirror roller 4 while facing the stamper roller 3.

  Then, the sheet-like resin material 1 extruded from the die 2 is pressed between the stamper roller 3 and the mirror roller 4, and the uneven shape on the surface of the stamper roller 3 is transferred to the resin material 1, and the resin material 1 is peeled off by the mirror roller for peeling. 5 is peeled off from the stamper roller 3.

One of the serious problems in such a resin material molding method is that a plate after molding in the case of a relatively thick resin sheet, particularly in the case of a resin sheet having a large thickness distribution in the width direction during molding. It means that the warpage becomes large. As countermeasures, Patent Documents 2 and 3 have the following countermeasures. However, a complete solution has not been obtained,
For example, in Patent Document 2, heat fixation (correction) is performed as a countermeasure against plate warpage during annealing after molding, and in Patent Document 3, heat softening is performed during sheet cutting as a countermeasure against sheet warpage.
Japanese Patent Laid-Open No. 9-11328 JP 2005-47126 A Japanese Utility Model Publication No. 5-16234

  However, in the case of a sheet warp countermeasure as in Patent Documents 2 and 3, in the case of a molded sheet, the mold collapses due to heating, and a desired function cannot be exhibited as a resin sheet for various optical element applications.

  The present invention has been made in view of such circumstances, and even in the case of a relatively thick resin sheet, particularly in the case of a resin sheet having a large thickness distribution in the width direction during molding. A method and an apparatus for producing a resin sheet suitable for use in a light guide plate and various optical elements arranged on the back surface of various display devices, in which a plate warp after molding is small and a desired cross-sectional shape can be obtained. The purpose is to provide.

  In order to achieve the above object, the present invention presses a sheet-shaped resin material extruded from a die with a mold roller rotating at a peripheral speed V1 and a nip roller disposed opposite to the mold roller, The concavo-convex shape is transferred to the resin material, and the resin material after transfer is peeled off from the mold roller by being wound around a peeling roller disposed to face the mold roller, and the resin material is placed downstream of the peeling roller. A resin sheet conveyed while being pinched by a first draw roller that rotates at a peripheral speed V2 that is 102 to 107% of the peripheral speed V1 and a second draw roller that is disposed opposite to the first draw roller. A manufacturing method is provided.

  To this end, the present invention provides a mold roller having a concavo-convex shape formed on the peripheral surface and rotating at a peripheral speed V1, a nip roller disposed opposite to one side of the mold roller, and disposed opposite to the other side of the mold roller. A roller row composed of a peeling roller, a die for extruding a sheet-like resin material from a discharge port, and a second roller which is arranged downstream of the peeling roller and rotates at a peripheral speed V2 of 102 to 107% of the peripheral speed V1. A draw means comprising a first draw roller and a second draw roller disposed opposite to the first draw roller, and the resin material extruded from the die is pressed between the mold roller and the nip roller, The uneven shape on the surface of the mold roller is transferred to the resin material, and the resin material after the transfer is wound around the peeling roller and peeled off from the mold roller. Providing an apparatus for manufacturing a resin sheet, characterized in that it is conveyed while being nipped between over La and the second draw roller.

  According to the present invention, the resin material is sandwiched between the mold roller and the nip roller rotating at the peripheral speed V1, the uneven shape on the surface of the mold roller is transferred to the resin material, and the resin material after transfer is 102 to 107% of V1. The sheet is conveyed while being pinched by a first draw roller and a second draw roller that rotate at a peripheral speed V2. Thus, the downstream conveyance speed is increased so that a predetermined tension is applied in the resin material conveyance direction.

  Therefore, the uneven shape on the surface of the mold roller can be accurately transferred to the resin material, and the warpage after molding of the resin sheet can be reduced. In particular, it is suitable for production of a resin sheet having a thickness difference of 1 mm or more (particularly, a thickness difference of 2.5 mm or more) in the width direction of the resin material.

  When the circumferential speed V2 is less than 102% of the circumferential speed V1, the tension applied in the resin material conveyance direction is insufficient, resulting in excessive plate warpage, while the circumferential speed V2 is 107 of the circumferential speed V1. When the value exceeds%, the tension applied in the resin material conveyance direction becomes excessive, resulting in problems such as slipping of the draw roller.

  In the present invention, the peripheral speed V2 is preferably set to 103 to 105% of the peripheral speed V1. By setting the peripheral speed V2 in such a range, the uneven shape on the surface of the mold roller can be accurately transferred to the resin material, and the plate warpage after molding of the resin sheet can be further reduced.

  In the present invention, it is preferable that the surface of the first draw roller and / or the second draw roller is formed of a material having a rubber hardness defined by JIS K6301 of 60 to 70 degrees. If a draw roller having such a rubber hardness is used on the roller surface, the uneven shape of the resin material will not be damaged, and the roller will not easily slip.

  In the present invention, it is preferable to provide a slow cooling zone between the peeling roller and the first draw roller. By providing such a slow cooling zone, the warpage of the resin sheet after molding can be reduced.

  In the present invention, it is preferable that the difference in thickness between the thickest portion and the thinnest portion in the width direction of the resin material is 1 mm or more due to the uneven shape transferred to the resin material. Moreover, in this invention, it is preferable that the thickness of the thinnest part of the said resin material shall be 5 mm or less. Thus, the effect of the present invention can be exhibited in the molding of a resin material having a cross-sectional shape that has been difficult to mold.

  As described above, according to the present invention, the uneven shape on the surface of the mold roller can be accurately transferred to the resin material, and the warpage after molding of the resin sheet can be reduced.

  Hereinafter, preferred embodiments of a method and an apparatus for producing a resin sheet according to the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a configuration diagram showing an example of a resin sheet production line to which a resin sheet production method and apparatus according to the present invention are applied.

  This resin sheet production line 10 includes a sheet die 12 for shaping a resin material 14 melted by an extruder (not shown) into a sheet shape, and a mold roller 16 having an uneven surface formed on the surface. A nip roller 18 disposed opposite the mold roller 16, a separation roller 24 disposed opposite the mold roller 16, a resin temperature control means 20 for controlling the temperature of the resin material 14 before contacting the mold roller 16, and a separation roller. 24 includes a temperature sensor 22 for measuring the temperature of the resin material 14 when being peeled off, a slow cooling zone 30, a draw means including a first draw roller 32 and a second draw roller 34, and the like.

  The slit size of the die 12 is formed so that the width of the molded molten resin material 14 is wider than the width of the mold roller 16, and the molten resin material 14 extruded from the die 12 is formed with the first roller 16 and the first roller 12. It arrange | positions so that it may extrude between the nip rollers 18. FIG.

  A regular uneven shape is formed on the surface of the mold roller 16. This regular uneven | corrugated shape can be made into the reverse shape of the resin material 14 surface (upper surface) after the shaping | molding shown by FIG. 2, for example. FIG. 2 is a cross-sectional view of the resin material 14 after molding.

  That is, the back surface (lower surface) of the molded resin material 14 is a flat surface, and a linear concavo-convex pattern in the direction of the arrow in the figure is formed on the surface of the resin material 14. This arrow direction indicates the traveling direction of the resin material 14. Therefore, an endless groove having an inverted shape on the surface of the resin material 14 may be formed on the surface of the mold roller 16. The details of the uneven pattern shape on the surface of the resin material 14 will be described later.

  The material of the mold roller 16 includes various steel members, stainless steel, copper, zinc, brass, and a metal lining of these metal materials, and a rubber lining on the surface. These metal materials are HCr plated, Cu plated, Ni plated. For example, ceramics and various composite materials can be used.

  The method for forming the concavo-convex pattern on the surface of the mold roller 16 depends on the concavo-convex pattern (pitch, depth, etc.) and the material of the surface of the mold roller 16, but generally a combination of cutting with an NC lathe and finishing buffing. Can be preferably employed. In addition, other known processing methods (grinding processing, ultrasonic processing, electric discharge processing, etc.) can also be employed.

  The surface roughness of the surface of the mold roller 16 is preferably 0.5 μm or less in Ra, and more preferably 0.2 μm or less.

  The mold roller 16 is rotationally driven in a direction indicated by an arrow in FIG. 1 at a predetermined peripheral speed V1 by a driving means (not shown). The mold roller 16 is provided with temperature adjusting means. By providing such a temperature adjusting means, it is possible to control to suppress the temperature rise or sudden temperature drop of the mold roller 16 due to the resin material 14 in a high temperature state.

  As such temperature adjusting means, a configuration in which oil whose temperature is adjusted is circulated inside the roller can be preferably employed. This supply and discharge of oil can be realized by a configuration in which a rotary joint is provided at the end of the roller. In the resin sheet production line 10 of FIG. 1, this temperature adjusting means is employed.

  The nip roller is disposed so as to face the mold roller 16 and presses the resin material 14 with the mold roller 16. The nip roller is disposed at the same height as the mold roller 16 and parallel to the mold roller 16.

  The surface of the nip roller 18 is preferably processed into a mirror surface. By setting it as such a surface, the back surface of the resin material 14 after shaping | molding can be made into a favorable state. The surface roughness of the surface of the nip roller 18 is preferably 0.5 μm or less in Ra, and more preferably 0.2 μm or less.

  The material of the nip roller 18 includes various steel members, stainless steel, copper, zinc, brass, and a metal lining of these metal materials, and a rubber lining on the surface. These metal materials are HCr plated, Cu plated, Ni plated, etc. These materials, ceramics, and various composite materials can be used.

  The nip roller 18 is driven to rotate in a direction indicated by an arrow in FIG. 1 at a predetermined peripheral speed V1 by a driving means (not shown). In addition, although the structure which does not provide a drive means in the nip roller 18 is also possible, it is preferable to provide a drive means from the point which can make the back surface of the resin material 14 a favorable state.

  The nip roller 18 is provided with a pressing means (not shown) so that the resin material 14 between the nip roller 18 and the mold roller 16 can be pressed with a predetermined pressure. The pressurizing means is configured to apply pressure in the normal direction at the contact point between the nip roller 18 and the mold roller 16, and various known means such as a motor driving means, an air cylinder, and a hydraulic cylinder can be employed.

  The nip roller 18 may be configured to be less likely to bend due to the reaction force of the clamping pressure. As such a configuration, a configuration in which a backup roller is provided on the back side of the nip roller 18 (opposite side of the mold roller 16), a configuration in which a crown shape (middle and high shape) is adopted, and a rigidity in the central portion in the axial direction of the roller is large. A configuration of a roller having such an intensity distribution, a configuration combining these, and the like can be employed.

  The nip roller 18 is provided with temperature adjusting means. The roller set temperature of the nip roller 18 includes the material of the resin material 14, the temperature when the resin material 14 is melted (for example, the slit exit of the die 12), the transport speed of the resin material 14, the outer diameter of the mold roller 16, The optimum value should be selected according to the uneven pattern shape.

  As the roller temperature adjusting means of the nip roller 18, a configuration in which oil whose temperature is adjusted is circulated inside the roller can be preferably employed. This supply and discharge of oil can be realized by a configuration in which a rotary joint is provided at the end of the roller. In the resin sheet production line 10 of FIG. 1, this temperature adjusting means is employed.

  As other temperature adjusting means, for example, various known means such as a structure in which a sheath heater is embedded in the roller and a structure in which a dielectric heating means is disposed in the vicinity of the roller can be adopted.

  The resin temperature control means 20 is provided to control the temperature of the resin material 14 before coming into contact with the mold roller 16, and includes an air nozzle 20A and an air pipe for supplying air to the air nozzle 20A from an air supply source (not shown). 20B.

  The temperature and flow rate of the gas ejected from the air nozzle 20 </ b> A are the material of the resin material 14, the temperature when the resin material 14 is melted (for example, the slit exit of the die 12), the transport speed of the resin material 14, and the outside of the mold roller 16. The optimum value should be selected according to the diameter, the shape of the concavo-convex pattern of the mold roller 16, and the like.

  The resin temperature control means 20 is not limited to the above-described one, and various known means can be adopted as long as the temperature of the resin material 14 can be appropriately controlled (for example, dielectric heating means, Cooling water pipes).

  The peeling roller 24 is disposed opposite to the mold roller 16 and is a roller for peeling the resin material 14 from the mold roller 16 by winding the resin material 14, 180 degrees downstream of the nip roller 18 with the mold roller 16 interposed therebetween. Has been placed. That is, the peeling roller 24 has the same height as the mold roller 16 and is disposed in parallel with the mold roller 16.

  The surface of the peeling roller 24 is preferably processed into a mirror surface. By setting it as such a surface, the back surface of the resin material 14 after shaping | molding can be made into a favorable state. The surface roughness of the surface of the peeling roller 24 is preferably 0.5 μm or less in terms of Ra, and more preferably 0.2 μm or less.

  As the material of the peeling roller 24, various steel members, stainless steel, copper, zinc, brass, these metal materials having a metal core and a rubber lining on the surface, these metal materials are HCr plated, Cu plated, Ni plated For example, ceramics and various composite materials can be used.

  The peeling roller 24 is rotationally driven in a direction indicated by an arrow in FIG. 1 at a predetermined peripheral speed V1 by a driving means (not shown). In addition, although the structure which does not provide a drive means in the peeling roller 24 is also possible, it is preferable to provide a drive means from the point which can make the back surface of the resin material 14 a favorable state.

  The peeling roller 24 is provided with temperature adjusting means. And the uneven | corrugated pattern shape of the surface of the resin material 14 can be made favorable by setting it as appropriate setting temperature.

  As described above, the temperature sensor 22 is a temperature measuring means for measuring the temperature of the resin material 14 when being peeled off from the peeling roller 24, and in the width direction of the resin material 14 wound around the peeling roller 24. It is an infrared thermometer which measures the temperature of the surface of a plurality of points (opposite surface side of a roller).

  The temperature sensor 22 is connected to control means (such as a personal computer) not shown. The control means is connected to the above-described temperature control means (resin temperature control means 20 and temperature adjusting means for each roller), and can control these temperature control means. Therefore, the measurement result of the temperature sensor 22 is fed back to each temperature control means, the die 12, etc., and reflected in the temperature control of the resin material 14, each roller, etc. Note that temperature measuring means other than the infrared thermometer (for example, a radiation thermometer) may be used as the temperature sensor 22.

  In addition to the above, it is preferable to provide surface temperature measuring means (not shown) so that the surface temperature of each roller described above and each portion of the resin material 14 can be monitored. As such surface temperature measuring means, various known measuring means such as an infrared thermometer and a radiation thermometer can be employed.

  Examples of measurement points by such surface temperature measuring means include a plurality of points in the width direction of the resin material 14 between the die 12 and the nip roller 18, and a resin material 14 (for example, a watch) wound around the mold roller 16. And a plurality of points in the width direction of the resin material 14 after peeling from the peeling roller 24, and the like.

  Further, the monitoring result of such surface temperature measuring means can be fed back to the temperature adjusting means of each roller, the die 12, the resin temperature control means 20, etc., and reflected in the temperature control of the resin material 14, each roller, etc. . It is also possible to operate by feedforward control without providing the surface temperature measuring means.

  In the resin sheet production line 10 of FIG. 1, tension detecting means for detecting the tension of the resin material 14 is provided downstream of the slow cooling zone 30 or downstream of the peeling roller 24, or the thickness of the resin material 14 is detected. Providing a detecting means (thickness sensor) can also be preferably employed. Further, the detection result by such a detecting means can be compared with a set value and fed back to a driving means such as the mold roller 16.

  The slow cooling zone 30 (or annealing zone) is provided to prevent a rapid temperature change of the resin material 14 downstream of the peeling roller 24. When a sudden temperature change occurs in the resin material 14, for example, the inside of the resin material 14 is in an elastic state while the vicinity of the surface of the resin material 14 is in a plastic state. The surface shape of the material 14 deteriorates. In addition, there is a problem that a temperature difference occurs between the front and back surfaces of the resin material 14 and the resin material 14 is warped.

  As the slow cooling zone 30, it is possible to adopt a configuration in which a horizontal tunnel shape is provided, temperature adjusting means is provided inside the tunnel, and the cooling temperature profile of the resin material 14 can be controlled. As the temperature adjusting means, a structure in which air (hot air or cold air) whose temperature is controlled from a plurality of nozzles is ejected toward the resin material 14, and heating means (nichrome wire heater, infrared heater, dielectric heating means, etc.) Various known means such as a structure for heating the front and back surfaces of the material 14 can be employed.

  Downstream of the slow cooling zone 30 (or the annealing zone), a drawing means including a first draw roller 32 and a second draw roller 34 is provided. This draw means is provided on the lower side of the resin material 14, and is provided on the upper side of the first draw roller 32 that is rotationally driven at a peripheral speed V 2 that is 102 to 107% of the peripheral speed V 1 of the mold roller 16. And a second draw roller 34 disposed opposite to the first draw roller 32.

  In this configuration, the first draw roller 32 is rotationally driven in the direction of the arrow in FIG. 1 by the above-described peripheral speed V2 by a driving means (not shown). The drive means is preferably of a variable speed type so that the first draw roller 32 can be rotationally driven at the peripheral speed V2. The first draw roller 32 is supported on a gantry (device main body) (not shown) via bearing means.

  Further, the second draw roller 34 is rotated (driven) in the direction of the arrow in FIG. 1 by the driving force of the first draw roller 32 through the resin material 14 at a substantially peripheral speed V2. It is also possible to adopt a configuration in which driving means is provided in the second draw roller 34 and synchronized (synchronized) with the first draw roller 32.

  The second draw roller 34 is provided with a pressing means (not shown) so that the resin material 14 between the second draw roller 32 and the first draw roller 32 can be clamped with a predetermined pressure. This pressurizing means is configured to apply pressure in the normal direction at the contact point between the second draw roller 34 and the first draw roller 32, and various known means such as a motor drive means, an air cylinder, and a hydraulic cylinder. Can be adopted.

  The surfaces of the first draw roller 32 and the second draw roller 34 are made of a material having a predetermined thickness (for example, 15 mm) and a rubber hardness specified by JIS K6301 of 60 to 70 degrees. Since the roller surfaces of the first draw roller 32 and the second draw roller 34 are made of such a rubber hardness, the uneven shape of the resin material 14 is not impaired, and the roller slip hardly occurs.

  Although not shown, a cleaning device (cleaning zone), a defect inspection device (inspection zone), a laminating device, a side cutter, a cross cutter, and a stacking unit are sequentially provided downstream of the drawing unit.

  Among these, the laminating apparatus is an apparatus that attaches a protective film (a film such as polyethylene) to the front and back surfaces of the resin material 14, and the side cutter is an apparatus that cuts off both end portions (discarded portions) of the resin material 14 in the width direction. The cross cutter is a device that cuts the resin material 14 to a predetermined length.

  Some of the above devices may be omitted depending on the application.

  Next, a method for producing a resin sheet by the resin sheet production line 10 shown in FIG. 1 will be described.

  As the resin material 14 applied to the present invention, a thermoplastic resin can be used. For example, polymethyl methacrylate resin (PMMA), polycarbonate resin, polystyrene resin, MS resin, AS resin, polypropylene resin, polyethylene resin, polyethylene Examples include terephthalate resins, polyvinyl chloride resins (PVC), thermoplastic elastomers, copolymers thereof, and cycloolefin polymers.

  The sheet-shaped resin material 14 pushed out from the die 12 is pressed between a mold roller 16 rotating at a peripheral speed V1 and a nip roller 18 disposed opposite to the mold roller 16 so that the uneven shape on the surface of the mold roller 16 is applied to the resin material 14. After the transfer, the resin material 14 is peeled off from the mold roller 16 by being wound around a peeling roller 24 disposed opposite to the mold roller 16. Then, the resin material 14 wound around the peeling roller 24 is peeled off from the peeling roller 24 at 12:00 in the clockwise direction.

  At this time, the temperature sensor 22 measures the temperatures of the surfaces at the plurality of points in the width direction of the resin material 14 (on the opposite surface side of the roller) when being peeled off from the peeling roller 24. Then, the control means feeds back the measurement result of the temperature sensor 22 to each temperature control means, the die 12, etc., and reflects it in the temperature control of the resin material 14, each roller, etc.

  Thereby, the resin material 14 can be peeled from the peeling roller 24 in a state where the temperature is controlled to (Tg−30) to (Tg + 40) ° C. with respect to the glass transition temperature Tg of the resin material 14. Warpage can be reduced.

  The glass transition temperature Tg is explained as follows. When a polymer substance is heated, a phenomenon that changes from a glassy hard state to a rubbery state is called a glass transition, and a temperature at which the glass transition occurs is called a glass transition point (temperature). This temperature varies depending on the material and composition of the resin material, and is, for example, in the range of 90 to 110 ° C. for polymethyl methacrylate resin.

  When the resin material 14 is peeled off from the peeling roller 24 in a state of being controlled to a temperature lower than (Tg-30) ° C., the flow state of the resin is poor, and as a result, the transfer accuracy becomes poor. On the other hand, when the resin material 14 is peeled off from the peeling roller 24 in a state of being controlled to a temperature exceeding (Tg + 40) ° C., the in-plane distribution of shrinkage after molding is large, and as a result, the plate warpage becomes excessive.

  It is preferable that the temperature of the resin material 14 immediately before being wound around the mold roller 16 is controlled to an appropriate value (for example, (Tg + 80) to (Tg + 140) ° C.) by the resin temperature control means 20. The temperature of the mold roller 16 is preferably controlled to an appropriate value (for example, (Tg-40) to (Tg + 30) ° C.). As a result, the uneven shape on the surface of the mold roller 16 can be accurately transferred to the resin material 14, and the peeling failure that the resin material does not peel from the mold roller 16 does not occur.

  The resin material 14 peeled off from the mold roller 16 is conveyed in the horizontal direction by a draw means rotating at a peripheral speed V2, and is slowly cooled by passing through the slow cooling zone 30, and the downstream product in a state where distortion is removed. A take-off portion (not shown) is cut to a predetermined length and accommodated as a resin sheet product.

  In the production of this resin sheet, the extrusion speed of the resin material 14 from the die 12 can be 0.1 to 50 m / min, preferably 0.3 to 30 m / min. Accordingly, the peripheral speed of the mold roller 16 is also substantially matched with this. In addition, it is preferable to control the speed unevenness of each roller (the mold roller 16, the nip roller 18, and the peeling roller 24) to be within 1% of the set value.

  The pressing pressure of the nip roller 18 against the mold roller 16 is 0 to 200 kN / m (0 to 200 kgf / cm) in terms of linear pressure (value converted assuming that the surface contact due to elastic deformation of each nip roller is linear contact). It is preferable to set it to 0 to 100 kN / m (0 to 100 kgf / cm).

  In the draw means, the first draw roller 32 that rotates at a peripheral speed V2 of 102 to 107% of V1 (preferably 103 to 105% of V1) and the second draw roller that is disposed opposite to the first draw roller 32 are used. 34, the resin material 14 is conveyed while being pinched.

  According to this drawing means, since the resin material 14 after transfer is transported at a peripheral speed V2 that is 102 to 107% of the peripheral speed V1 at the time of transfer, the downstream transport speed is increased and the transport direction of the resin material 14 is increased. A predetermined tension is applied to the. Therefore, the uneven shape on the surface of the mold roller 16 can be accurately transferred to the resin material 14, and the plate warpage after the molding of the resin material 14 can be reduced. In particular, it is suitable for manufacturing a resin sheet having a thickness difference of 1 mm or more (particularly, a thickness difference of 2.5 mm or more) between the thickest part and the thinnest part in the width direction of the resin material 14.

  When the peripheral speed V2 is less than 102% of the peripheral speed V1, the tension applied in the transport direction of the resin material 14 is insufficient, resulting in excessive warpage of the plate, while the peripheral speed V2 is equal to the peripheral speed V1. When the value exceeds 107%, the tension applied in the transport direction of the resin material 14 becomes excessive, resulting in problems such as slipping of the draw roller.

  Next, details of the uneven pattern shape on the surface of the resin material 14 will be described. As described above, FIG. 2 is a perspective view of a state in which the end surface 14A of the resin material 14 after molding is cut out linearly. The back surface of the resin material 14 is a flat surface.

  The uneven pattern shape on the surface of the resin material 14 is a linear uneven pattern in the longitudinal direction (the arrow direction in the figure). In this pattern, the V-groove 50 formed in the thickest part 14B of the resin material 14 and the plate thickness decreases linearly from both edges of the V-groove 50 toward the thinnest part 14C of the resin material 14. The taper portions 52 and 52 are repeatedly shaped. That is, it is a continuous shape in which the V groove 50 and the taper portions 52 and 52 on both sides, which are line targets with respect to the center line of the V groove 50, are one unit (one pitch).

  In FIG. 2, the thickness of the thinnest portion 14C of the resin material 14 is preferably 5 mm or less, and more preferably 2 mm or less. The difference in thickness between the thickest part 14B and the thinnest part 14C of the resin material 14 is preferably 1 mm or more, and more preferably 2.5 mm or more. By setting it as such a dimension, it can be used conveniently for the light-guide plate and various optical elements which are distribute | arranged to the back surface of various display apparatuses.

  When the molded resin material 14 is used for the light guide plate, a cylindrical cold cathode tube is arranged inside the V groove 50, and light irradiated from the cold cathode tube is resin from the surface of the V groove 50. The light enters the inside of the material 14, is reflected by the tapered portions 52 and 52, and is irradiated in a planar shape from the back surface of the resin material 14.

  Thus, when the resin material 14 after molding is used for the light guide plate, the width P of the V groove 50 is preferably 2 mm or more, and the apex angle θ1 of the V groove 50 is 40 to 80 degrees. preferable. The depth Δt of the V groove 50 is preferably 1 mm or more, and more preferably 2.5 mm or more. The inclination angle θ2 of the tapered portions 52, 52 is preferably 3 to 20 degrees. Further, the width P2 of the tapered portions 52, 52 is preferably 5 mm or more, and more preferably 10 mm or more.

  Next, another uneven pattern shape on the surface of the resin material 14 will be described. FIG. 3 is a perspective view of a state in which the end surface 14A of the resin material 14 after molding is cut out linearly. The back surface of the resin material 14 is a flat surface.

  The uneven pattern shape on the surface of the resin material 14 is a linear uneven pattern in the longitudinal direction (the arrow direction in the figure). The cross-sectionally saw-tooth pattern has a vertical wall 54 that connects the thickest portion 14B and the thinnest portion 14C of the resin material 14 and the upper edge (thickest portion 14B) of the vertical wall 54. The taper portion 56 whose thickness decreases linearly toward the thinnest portion 14C is repeated.

  In FIG. 3, the thickness of the thinnest portion 14C of the resin material 14 is preferably 5 mm or less, and more preferably 2 mm or more. The difference in thickness between the thickest part 14B and the thinnest part 14C of the resin material 14 is preferably 1 mm or more, and more preferably 2.5 mm or more. By setting it as such a dimension, it can be used conveniently for the light-guide plate and various optical elements which are distribute | arranged to the back surface of various display apparatuses.

  When the molded resin material 14 is used for the light guide plate, a cylindrical cold cathode tube is disposed on the side surface of the vertical wall 54, and the light beam irradiated from the cold cathode tube is irradiated on the surface (side surface) of the vertical wall 54. ) Is incident on the inside of the resin material 14, is reflected by the taper portion 56, and is irradiated in a planar shape from the back surface of the resin material 14.

  Thus, when using the resin material 14 after shaping | molding for a light-guide plate, it is preferable that the taper part 56 inclination-angle (theta) 3 shall be 3-20 degree | times.

  In addition, when using the resin material 14 after shaping | molding for a light-guide plate, shapes other than these can also be employ | adopted. For example, the cross-sectional shape of the V-groove 50 of the resin material 14 in FIG. 2 is V-shaped, but other shapes such as a rectangular shape, a trapezoidal shape, an arc shape, a parabolic shape, etc. are also possible. It can be used if it satisfies the required characteristics and formability.

  Further, the uneven shape on the surface of the mold roller 16 does not need to be the inverted shape of the surface of the resin material 14 in FIG. 2 or 3, and the product shape of the resin material 14 is illustrated in consideration of the shrinkage allowance of the resin material 14. It can also be set as the shape offset from this shape so that it may become the shape of 2 or FIG.

  According to the method and apparatus for producing a resin sheet according to the present invention described above, the difference in thickness between the thickest part and the thinnest part in the width direction of the resin material is large, for example, the difference in thickness is 1 mm or more. Even in the case of a resin sheet (particularly, the difference in thickness is 2.5 mm or more), the warpage is very small and a desired cross-sectional shape can be obtained.

  As mentioned above, although embodiment of the manufacturing method and apparatus of the resin sheet which concern on this invention was described, this invention is not limited to the said embodiment, Various aspects can be taken.

  For example, in the present embodiment, as the drawing means, a configuration including the first draw roller 32 and the second draw roller 34 of FIG. 1 is adopted, but other configurations, for example, endless belts above and below the resin material 14 are employed. It is also possible to adopt a mode in which a belt-like body such as a belt is disposed and the resin material 14 is conveyed while being sandwiched between the pair of belt-like bodies. This is because even such a belt-like body acts in the same manner as a cylindrical roller, and the same effect can be obtained.

  In addition, although the air nozzle 20A and the like are employed as the resin temperature control means 20, as described above, the present invention is not limited to this type, and if the temperature of the resin material 14 can be appropriately controlled, Various known means can be employed.

  Furthermore, an on-line warpage measuring means that is not employed in the present embodiment is provided downstream of the draw means, and the amount of warpage in the longitudinal direction of the resin material 14 after being cut by a side cutter or a cross cutter is monitored. It is also possible to adopt a configuration that feeds back to the draw means, the resin temperature control means 20, and the like.

  In this embodiment, the surface of the nip roller 18 is mirror-like, and the back surface of the resin material 14 after transfer is a flat surface. However, the surface of the nip roller 18 is formed in an uneven shape, and the resin material after transfer is formed. The reverse side of 14 can also be made into this inversion shape.

  Examples of the present invention will be described below.

  The resin sheet of the Example was manufactured using the resin sheet manufacturing line 10 shown in FIG. The cross-sectional shape of the resin sheet was the shape shown in FIG. 2. P was 2.6 mm, P2 was 13.7 mm, Δt was 4 mm, θ1 was 55 degrees, and θ2 was 15 degrees. The width | variety of the resin sheet was 274 mm in the state which excised the width direction both ends (discarded part) with the side cutter. The length (longitudinal direction) of the resin sheet was 487 mm in a state where the resin sheet was cut to a predetermined length by a cross cutter. FIG. 4A is a perspective view showing the resin sheet in a state of being trimmed to a predetermined width and a predetermined length.

  The warpage evaluation of the resin sheet in a state of being cut into the predetermined width and the predetermined length was performed as shown in FIG. That is, the resin sheet was placed on a flat plate (surface plate) with a ensured flatness, the amount of lifting at both ends was measured with a position sensor, and calculated according to the formula shown in the figure.

  In addition, in the case as shown in FIG. 4B, since the resin sheet is in a downward projecting state at the time of molding, the value of the warp according to the illustrated formula is negative (minus). On the other hand, when the resin sheet is convex upward at the time of molding, the resin sheet is inverted and measured as shown in FIG. In this case, the warp value is positive (plus).

  Manufacturing conditions common to the examples were as follows.

Peripheral speed of mold roller 16: 120 mm / min Composition of resin material 14: PMMA (Acrypet VH001, manufactured by Mitsubishi Rayon Co., Ltd.)
Temperature of the resin material 14 at the discharge port of the die 12: 260 ° C
The peripheral speed V2 of the first draw roller 32 of the drawing means was changed to 100 to 105% of the peripheral speed V1 of the mold roller 16. The circumferential speed V1 and the circumferential speed V2 were obtained by measuring the number of rotations of the roller with a digital tachometer and multiplying by a known roller outer diameter and circumferential ratio. As a draw value, (V2 / V1-1) × 100 (unit:%) was obtained.

  And the curvature of the resin material 14 of each draw value was measured by said method. The above results were plotted in the graph of FIG. In the graph (XY graph) of FIG. 5, the horizontal axis is the draw value, and the vertical axis is the warpage of the resin material 14.

  According to the graph of FIG. 5, the draw value was 0% and the warp was 4.2 mm, whereas the draw value was 3% and the warp was 2.6 mm, and the draw value was 5%. The warpage was 0.7 mm. That is, it was confirmed that the warp was improved by 1.6 mm by setting the draw value to 3%, and the warp was improved by 3.5 mm by setting the draw value to 5%.

[Comparative example]
A sample was prepared with a draw value of 108% and other manufacturing conditions similar to those in the above example. Since slip occurred occasionally on the draw roller, a uniform sample could not be obtained.

The block diagram which shows the example of the production line of the resin sheet to which this invention is applied The perspective view of the state which cut off the end face of the resin material after molding in a straight line The perspective view of the state which cut off the end face of the resin material after molding in a straight line The figure explaining the curvature of the resin material in an Example In an Example, the graph explaining the relationship between the draw value of resin material, and curvature Configuration diagram showing production line of resin sheet of conventional example

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Resin sheet production line, 12 ... Die, 14 ... Resin material, 16 ... Mold roller, 18 ... Nip roller, 20 ... Resin temperature control means, 22 ... Temperature sensor (temperature measuring means), 24 ... Peeling roller, 30 ... Slow cooling zone, 32 ... first draw roller, 34 ... second draw roller

Claims (7)

The sheet-shaped resin material extruded from the die is clamped by a mold roller that rotates at a peripheral speed V1 and a nip roller that is disposed to face the mold roller.
Transfer the uneven shape of the mold roller surface to the resin material,
The resin material after the transfer is peeled off from the mold roller by being wound around a peeling roller disposed to face the mold roller,
Downstream of the peeling roller, the resin material is sandwiched between a first draw roller that rotates at a peripheral speed V2 that is 102 to 107% of the peripheral speed V1 and a second draw roller that is disposed opposite to the first draw roller. A method for producing a resin sheet, wherein the resin sheet is conveyed while being conveyed.   The method for producing a resin sheet according to claim 1, wherein the peripheral speed V2 is set to 103 to 105% of the peripheral speed V1.   3. The method for producing a resin sheet according to claim 1, wherein the surface of the first draw roller and / or the second draw roller is formed of a material having a rubber hardness specified by JIS K6301 of 60 to 70 degrees. .   The method for producing a resin sheet according to claim 1, wherein a slow cooling zone is provided between the peeling roller and the first draw roller.   5. The difference in thickness between the thickest portion and the thinnest portion in the width direction of the resin material is 1 mm or more due to the uneven shape transferred to the resin material. The manufacturing method of the resin sheet of 1 item | term.   The thickness of the thinnest part of the said resin material shall be 5 mm or less, The manufacturing method of the resin sheet of any one of Claims 1-5 characterized by the above-mentioned. A roller comprising a mold roller having a concavo-convex shape formed on its peripheral surface and rotating at a peripheral speed V1, a nip roller disposed opposite to one side of the mold roller, and a peeling roller disposed opposite to the other side of the mold roller Columns,
A die for extruding a sheet-shaped resin material from the discharge port;
Draw means comprising a first draw roller disposed downstream of the peeling roller and rotating at a peripheral speed V2 of 102 to 107% of the peripheral speed V1, and a second draw roller disposed opposite to the first draw roller; With
The resin material extruded from the die is pressed between the mold roller and the nip roller,
The uneven shape on the surface of the mold roller is transferred to the resin material,
The resin material after transfer is wound around the peeling roller and peeled off from the mold roller,
The apparatus for producing a resin sheet, wherein the resin material after peeling is conveyed while being sandwiched between the first draw roller and the second draw roller.

Images