JP2007210160A - Method for producing resin sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing a resin sheet which can reduce plate warpage after molding, can obtain a desired cross-sectional shape even when the resin sheet is relatively thick, and is particularly suitable to be used in a light guide plate arranged in the backs of various displays or in various optical elements. <P>SOLUTION: A sheet-shaped resin material 14 extruded from a die 12 is pinched/pressed by a mold roller 16 and a nip roller 18 arranged to face the mold roller, and the uneven shape of the surface of the mold roller is transferred to the resin material. The resin material after the transfer is wound onto a peeling roller 24 arranged to face the mold roller to be peeled from the mold roller and peeled from the peeling roller while the temperature of the resin material is controlled in a range of (Tg-30) to (Tg+40)°C (Tg is the glass transition temperature of the rein material). <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for producing a resin sheet, and more particularly to a method for producing a resin sheet 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. Provides a method for producing a resin sheet suitable for use in a light guide plate and various optical elements disposed on the back surface of various display devices, with a small warp after molding and a desired cross-sectional shape. The purpose is to do.

  In order to achieve the object, the present invention presses a sheet-shaped resin material extruded from a die between a mold roller and a nip roller disposed so as to face the mold roller, and forms the uneven shape on the surface of the mold roller. The resin material after transfer is peeled off from the mold roller by winding it on a peeling roller disposed opposite to the mold roller, and the resin material is removed from the glass transition temperature Tg of the resin material (Tg There is provided a method for producing a resin sheet, which is peeled off from the peeling roller in a state controlled at a temperature of −30) to (Tg + 40) ° C.

  According to the present invention, the resin material is clamped between the mold roller and the nip roller, the uneven shape on the surface of the mold roller is transferred to the resin material, peeled off from the mold roller, and the resin material is removed from (Tg-30) to (Tg + 40) °. Peeling from the peeling roller in a state controlled to the temperature of C.

  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 resin material is peeled off from the peeling roller in a state controlled at a temperature lower than (Tg-30) ° C., the flow state of the resin is poor, resulting in poor transfer accuracy. ) When peeling from the peeling roller in a state where the temperature is controlled to exceed ° C, the in-plane distribution of shrinkage after molding is large, and as a result, the plate warpage becomes excessive.

  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.

  In the present invention, it is preferable to provide temperature control means in one or more of the mold roller, nip roller, and peeling roller and / or in the vicinity of one or more of the mold roller, nip roller, and peeling roller. Thus, if the temperature control means is provided and the temperature of the resin material is controlled, the transfer accuracy is improved.

  Moreover, in this invention, it is preferable to provide a temperature measuring means, to measure the temperature of the said resin material at the time of peeling from the said peeling roller, and to feed back to the said temperature control means. Thus, if the temperature measuring means is provided to measure the temperature of the resin material and the measurement result is fed back to the temperature control means, the transfer accuracy is further improved.

  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 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 according to the present invention is 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 (temperature measuring means) 22 for measuring the temperature of the resin material 14 when being peeled off, a slow cooling zone 30, a control means (not shown), 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 driven to rotate in a direction indicated by an arrow in FIG. 1 at a predetermined peripheral speed 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 rotationally driven in a direction indicated by an arrow in FIG. 1 at a predetermined peripheral speed 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 driven to rotate in the direction of the arrow in FIG. 1 by a driving means (not shown) at a predetermined peripheral speed. 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 (temperature measuring means) 22 is a sensor (temperature measuring means) for measuring the temperature of the resin material 14 when being peeled from the peeling roller 24, and is wound around the peeling roller 24. It is an infrared thermometer which measures the temperature of the surface of the several point of the width direction of the resin material 14 (the 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 the 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.

  Although not shown, downstream of the slow cooling zone 30 (or annealing zone), a cleaning device (cleaning zone), a defect inspection device (inspection zone), a laminating device, a side cutter, a cross cutter, and an accumulating unit are sequentially provided. .

  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 extruded from the die 12 is pressed between the mold roller 16 and the nip roller 18 disposed opposite to the mold roller 16, and the uneven shape on the surface of the mold roller 16 is transferred to 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 of being controlled to a temperature of (Tg-30) to (Tg + 40) ° C. of the resin material 14, and the warpage of the resin material 14 is greatly reduced. Can do.

  As described above, 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 is poor. Become. On the other hand, when the resin material 14 is peeled off from the peeling roller 24 in a state in which the resin material 14 is controlled to a temperature exceeding the glass transition temperature (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 transported in the horizontal direction, gradually cooled by passing through the slow cooling zone 30, and in a state where distortion is removed, a predetermined length is obtained in a downstream product removing portion (not shown). Cut into pieces and housed 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).

  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 resin sheet manufacturing method 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 (particularly Even if the resin sheet has a thickness difference of 2.5 mm or more, warpage is very small and a desired cross-sectional shape can be obtained.

  As mentioned above, although embodiment of the manufacturing method of the resin sheet which concerns 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, the air nozzle 20A or the like is employed as the resin temperature control means 20, but as described above, the present invention is not limited to this type, and the temperature of the resin material 14 can be appropriately controlled. If it is a thing, well-known various means are employable.

  Furthermore, in the present 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. 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. 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: 118.8 mm / min Composition of resin material 14: PMMA (Mitsubishi Rayon Co., Ltd., trade name: Acrypet VH001)
Temperature of the resin material 14 at the discharge port of the die 12: 247 ° C
An infrared temperature sensor was used as the temperature sensor 22. And the temperature of the 320 point | piece surface (opposite surface side of a roller) of the width direction of the resin material 14 at the time of peeling from the peeling roller 24 was measured, and the average value was computed.

  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.

  The average value of the temperature of the resin material 14 when being peeled from the peeling roller 24 was 115 to 135 ° C. And the curvature of the resin material 14 of each temperature condition 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 average value of the temperature of the resin material 14 when being peeled from the peeling roller 24, and the vertical axis is the warpage of the resin material 14.

  According to the graph of FIG. 5, if the temperature of the resin material 14 when being peeled from the peeling roller 24 is less than 120 ° C., the warpage is less than 1.5 mm, and if the temperature is less than 125 ° C. It was confirmed that the warpage was less than 3.0 mm.

  In addition, since the glass transition temperature Tg of the polymethylmethacrylate resin which is the resin material 14 is 110 degreeC, the temperature 120 degreeC corresponds to (Tg + 10) degreeC, and the temperature 125 degreeC is (Tg + 15). ) Corresponds to ° C.

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 temperature of a 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

Claims (5)

The sheet-shaped resin material extruded from the die is pinched by a mold roller and a nip roller disposed opposite to 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,
A method for producing a resin sheet, comprising: peeling the resin material from the peeling roller in a state of being controlled at a temperature of (Tg-30) to (Tg + 40) ° C. with respect to a glass transition temperature Tg of the resin material.   The temperature control means is provided in at least one of the mold roller, nip roller, and peeling roller and / or in the vicinity of one or more of the mold roller, nip roller, and peeling roller. Manufacturing method of resin sheet.   The method for producing a resin sheet according to claim 2, wherein a temperature measuring unit is provided to measure a temperature of the resin material when being peeled off from the peeling roller and feed back to the temperature control unit.   4. The thickness difference between the thickest part and the thinnest part in the width direction of the resin material is 1 mm or more due to the uneven shape transferred to the resin material. 2. A method for producing a resin sheet according to item 1.   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 1-4 characterized by the above-mentioned.

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