JP2007210161A - Method and apparatus for producing resin sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing 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 surfce of the mold roller is transferred to the resin material. The resin material after the molding is wound onto a peeling roller 24 arranged to face the mold roller to be peeled from the mold roller. On the downstream side of the peeling roller, the temperatures of the upper and lower surfaces are controlled by an upper surface side heating means 26 and a lower surface side heating means 28 which are arranged to hold the resin material between them, respectively. The resin material is cut in a prescribed length in the conveyance direction by a cutting means set on the down stream side. The amount of warpage of the resin material after the cutting is measured. <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.

  Further, in the countermeasure against the warp in the apparatus having the configuration shown in FIG. 6, the molding conditions (conveying speed of the resin material 1, the discharge temperature of the resin material 1 from the die 2, the temperature of each roller, etc.) are optimized. Although it was necessary, there were restrictions on the pattern to be transferred, etc., the range in which the molding conditions could be varied was narrow, and optimization was difficult.

  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 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. And the resin material after transfer is peeled off from the mold roller by being wound around a peeling roller disposed opposite to the mold roller, and is provided on the upper surface side sandwiching the resin material downstream of the peeling roller The surface temperature of the upper and lower surfaces of the resin material is controlled by the heating means and the lower surface side heating means, respectively, and the resin material is cut into a predetermined length in the transport direction by a cutting means provided downstream, and the resin material after being cut A method for producing a resin sheet, characterized by measuring the amount of warpage of the resin, is provided.

  To this end, the present invention includes a mold roller having a concavo-convex shape formed on the peripheral surface, a nip roller disposed to face one side of the mold roller, and a peeling roller disposed to face the other side of the mold roller. An upper surface side heating means and a lower surface side heating means which are arranged downstream of the peeling roller and are provided so as to sandwich the resin material, and further downstream. Provided with a cutting means for cutting the resin material into a predetermined length in the conveying direction, and a warp amount measuring means for measuring the warp amount of the resin material after cutting, wherein the resin material extruded from the die is The mold roller and the nip roller are sandwiched and pressed, 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 resin material after separation is heat-treated by the upper surface side heating means and the lower surface side heating means, the resin material after the heat treatment is cut, the warpage amount of the resin material after cutting is measured, and the warpage amount is reduced. The apparatus for producing a resin sheet is characterized in that set temperatures of the upper surface side heating means and the lower surface side heating means are respectively controlled.

  According to the present invention, the resin material is sandwiched between the mold roller and the nip roller, the uneven shape of the mold roller surface is transferred to the resin material, and the resin material after the transfer is heat-treated by the upper surface side heating means and the lower surface side heating means, This resin material is cut into a predetermined length in the transport direction by a cutting means, and the amount of warpage of the resin material after cutting is measured.

  Therefore, if the heat treatment is appropriately performed by the upper surface side heating means and the lower surface side heating means, 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.

  In the present invention, the measurement result of the warpage amount of the resin material is fed back to the upper surface side heating device and the lower surface side heating device, and the set temperatures of the upper surface side heating device and the lower surface side heating device are set so that the warpage amount is reduced. Each is preferably controlled. Further, in the present invention, as a result of measuring the amount of warping of the resin material, when the resin material has a concave shape on the upper side, the set temperature of the upper surface side heating means is lower than the set temperature of the lower surface side heating means. It is preferable to control so that the set temperature of the upper surface side heating means becomes higher than the set temperature of the lower surface side heating means when the resin material has a convex shape upward.

  Thus, if the measurement result of the amount of warpage is fed back to the upper surface side heating means and the lower surface side heating means, and the control is performed so that the warpage amount is reduced, the warpage after molding of the resin sheet can be further reduced.

  Moreover, in this invention, it is preferable to provide a conveyor means downstream of the said cutting means, and to measure the curvature amount of the said resin material on this conveyor means with a some non-contact-type position sensor. If such a conveyor means and a plurality of non-contact type position sensors are used, the amount of warping of the resin material can be measured online, and feedback can be performed quickly.

  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 peeling roller 24 disposed opposed to the mold roller 16, an upper surface side heating means 26 and a lower surface side heating means 28 provided so as to sandwich the resin material 14, and a first The amount of warping of the drawing means comprising the drawing roller 32 and the second drawing roller 34, the cutting means 36 for cutting the resin material 14 into a predetermined length in the conveying direction, the conveyor means 38, and the resin material 14 after cutting are measured. It comprises a warp amount measuring means 40, a control means 42 for feeding back the measurement results of the warp amount measuring means 40 to the upper surface side heating means 26 and the lower surface side heating means 28, 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 the direction of the arrow in FIG. 1 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 the direction of the arrow in FIG. 1 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 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 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.

  Downstream of the peeling roller 24, guide rollers G and G for supporting the lower surface of the resin material 14 are provided, and then an upper surface side heating unit 26 and a lower surface side heating unit 28 are provided. The upper surface side heating means 26 and the lower surface side heating means 28 are for controlling the surface temperatures of the upper and lower surfaces of the resin material 14, respectively.

  That is, as will be described in detail later, the present inventors have found that the warpage in the transport direction of the resin material 14 depends greatly on the temperature difference between the upper and lower surfaces of the resin material 14. In order to correct the warpage in the transport direction, an upper surface side heating unit 26 and a lower surface side heating unit 28 are provided to cancel the temperature difference between the upper and lower surfaces of the resin material 14.

  As the upper surface side heating means 26 and the lower surface side heating means 28, various known heating means (for example, plate heaters) can be employed. In this configuration, infrared heaters of the same specification are employed as the upper surface side heating means 26 and the lower surface side heating means 28.

  The upper surface side heating means 26 and the lower surface side heating means 28 are respectively connected to the control means 42 so that the measurement result of the downstream warp amount measuring means 40 can be feedback-controlled.

  Downstream of the upper surface side heating unit 26 and the lower surface side heating unit 28, a draw unit 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, provided on the upper side of the first draw roller 32 that is rotationally driven at a peripheral speed of 100 to 107% of the peripheral speed of the mold roller 16, and the resin material 14, The second draw roller 34 is disposed opposite to the first draw roller 32.

  In this configuration, the first draw roller 32 is driven to rotate in the direction of the arrow in FIG. 1 at the above peripheral speed 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 above peripheral speed. 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 at substantially the same peripheral speed via the resin material 14 by the driving force of the first draw roller 32. 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.

  It is preferable to provide surface temperature measuring means (not shown) so that the surface temperatures of the respective rollers and the resin material 14 described above 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. A plurality of points in the width direction at 6 o'clock in the direction), a plurality of points in the width direction of the resin material 14 when peeled from the peeling roller 24 (a position at 12 o'clock in the clockwise direction), and the resin after peeling from the peeling roller 24 A plurality of points in the width direction of the material 14 can be considered.

  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, 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.

  Further, 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 peeling roller 24 or upstream of the draw means, 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.

  Further, in the resin sheet production line 10 of FIG. 1, a slow cooling zone (or annealing zone) is provided downstream of the peeling roller 24 or upstream of the draw means, and a rapid temperature change of the resin material 14 downstream of the peeling roller 24 is caused. It can also be prevented. 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, 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.

  A cutting means 36 is provided downstream of the drawing means. The cutting means 36 (cross cutter) is a device that cuts the resin material 14 into a predetermined length in the transport direction. Although illustration is omitted, a side cutter for cutting off both end portions (discard portions) in the width direction of the resin material 14 may be provided upstream or downstream of the cutting means 36.

  A conveyor means 38 is provided downstream of the cutting means 36. The conveyor means 38 includes rotating shafts 38A and 38B provided at both ends, and a conveyor belt (endless belt) 38C stretched around the rotating shafts 38A and 38B. Either one or both of the rotary shafts 38A and 38B are rotationally driven.

  And it is preferable to set the conveyance speed of the conveyor belt 38C in the arrow direction to be slightly larger than the peripheral speed of the draw means. By conveying the resin material 14 after cutting at such a speed, collision between the resin materials 14 can be effectively avoided.

  Warpage amount measuring means 40 is provided above the left end of the conveyor belt 38C. The warp amount measuring means 40 is a device that measures the warp amount of the resin material 14 after cutting. The resin material 14 after cutting is composed of a plurality of (three in FIG. 1) non-contact position sensors.

  The position sensors 40A, 40B, and 40C have the same specifications, and are supported at equal intervals in the horizontal direction and at an equal distance above the conveyor belt 38C. As the position sensors 40A, 40B, and 40C, for example, a laser beam type sensor device can be adopted. The position sensors 40A, 40B and 40C are each connected to the control means 42.

  The warp amount measuring means 40 can also be constituted by a plurality of contact type position sensors. In this case, it is more preferable not to deform the resin material 14 as a contact type position sensor with a small stylus pressure, and the resin material is supported (driven) so that it can be retracted upward during non-measurement. 14 is preferable.

  The measurement of the warping amount of the resin material 14 after cutting is performed as shown in FIG. FIG. 4A is a perspective view showing the resin sheet in a state where it is trimmed to a predetermined width and a predetermined length (in this case, 274 × 487 mm). FIG. 4B is a front view showing a resin sheet warpage evaluation method. In this way, the amount of lifting at both ends is measured by the position sensors 40A, 40B, and 40C, and calculated by the control means 42 using 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 value of warpage is positive (plus).

  The control unit 42 is a control unit that calculates the measurement result of the warp amount measurement unit 40, converts this into a correction amount, and feeds back to the upper surface side heating unit 26 and the lower surface side heating unit 28. As the control means 42, various computer means such as a personal computer can be employed.

  Although not shown in FIG. 1, a cleaning device (cleaning zone), a defect inspection device (inspection zone), a laminating device, and a stacking unit are sequentially provided downstream of the conveyor unit 38.

  Among these, the laminating apparatus is an apparatus for attaching a protective film (film such as polyethylene) to the front and back surfaces of the resin material 14. 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 so as to face the mold roller 16, and the uneven shape on the surface of the mold roller 16 is transferred to the resin material 14. The paper 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, it is preferable to control the temperature of the resin material 14 immediately before being wound around the mold roller 16 to an appropriate value (for example, (Tg + 80) to (Tg + 140) ° C.). 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 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.

  Moreover, it is preferable to peel from the peeling roller 24 in a state where the resin material 14 is controlled to an appropriate value (for example, a glass transition temperature (Tg-30) to (Tg + 40) ° C. of the resin material 14). Thereby, the curvature of the resin material 14 can be reduced.

  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).

  The resin material 14 peeled off from the mold roller 16 is transported in the horizontal direction by a draw means that rotates at a peripheral speed of 100 to 107% (preferably 103 to 105%) of the peripheral speed at the time of transfer. And the lower surface side heating means 28 are subjected to heat treatment, cut into a predetermined length by the cutting means 36, and the warpage amount of the resin material 14 after being cut on the conveyor means 38 is measured by the warpage amount measurement means 40. Then, it is stored as a resin sheet product downstream of the conveyor means 38.

  At this time, a warpage amount measurement result of the resin material 14 is calculated by the control means 42, converted into a correction amount, and fed back to the upper surface side heating means 26 and the lower surface side heating means 28 so that the warpage amount is reduced.

  Specifically, as a result of the measurement of the amount of warpage, when the resin material 14 has a concave shape on the upper side, the set temperature of the upper surface side heating means 26 is controlled to be lower than the set temperature of the lower surface side heating means 28, Control is performed so that the set temperature of the upper surface side heating means 26 becomes higher than the set temperature of the lower surface side heating means 28 when the material 14 has an upwardly convex shape.

  Thereby, 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.

  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 this embodiment, infrared heaters of the same specification are employed as the upper surface side heating means 26 and the lower surface side heating means 28, but other heating means such as hot air blowing means may be employed instead. it can. By such means, it is possible to control the temperature of the upper and lower surfaces of the resin material 14 by changing the hot air temperature and the air flow rate, and the same effect as in this embodiment can be obtained.

  Further, in the present embodiment, as the drawing means, a configuration including the first draw roller 32 and the second draw roller 34 in 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 the like is arranged 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.

  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.

  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 (Acrypet VH001, manufactured by Mitsubishi Rayon Co., Ltd.)
Temperature of the resin material 14 at the discharge port of the die 12: 247 ° C
While changing the preset temperature of the lower surface side heating means 28 to 200-300 degreeC and manufacturing the resin sheet, the curvature of the resin sheet in each condition was measured.

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

  According to the graph of FIG. 5, the set temperature is 200 ° C. and the warp is 1.0 mm, whereas the set temperature is 250 ° C. and the warp is 1.5 mm, and the set temperature is 300 mm. The warpage was 2.5 mm at ° C. That is, it has been confirmed that the warpage is improved by making the set temperature appropriate.

  Further, it has been found that the relationship between the warp (Y) and the set temperature (X) can be linearly approximated by a linear relationship using the formula in FIG.

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 Diagram explaining the warpage of resin material In an Example, the graph explaining the relationship between the preset temperature of a heating means 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, 24 ... Peeling roller, 26 ... Upper surface side heating means, 28 ... Lower surface side heating means, 32 ... First draw Roller 34 ... second draw roller 36 ... cutting means 38 ... conveyor means 40 ... warping amount measuring means 42 ... control means

Claims (7)

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,
Control the surface temperature of the upper and lower surfaces of the resin material by the upper surface side heating means and the lower surface side heating means provided on both sides of the resin material downstream of the peeling roller,
Further, by cutting means provided downstream, the resin material is cut into a predetermined length in the transport direction,
A method for producing a resin sheet, comprising measuring a warping amount of the resin material after cutting.   The measurement result of the warping amount of the resin material is fed back to the upper surface side heating unit and the lower surface side heating unit, and the set temperatures of the upper surface side heating unit and the lower surface side heating unit are controlled so that the warpage amount is reduced. The manufacturing method of the resin sheet of Claim 1 characterized by these.   As a result of measuring the amount of warping of the resin material, when the resin material has a concave shape on the upper side, the set temperature of the upper surface side heating means is controlled to be lower than the set temperature of the lower surface side heating means, and the resin 3. The resin according to claim 1, wherein when the material has a convex shape upward, the set temperature of the upper surface side heating means is controlled to be higher than the set temperature of the lower surface side heating means. Sheet manufacturing method.   The conveyor means is provided downstream of the cutting means, and the warpage amount of the resin material on the conveyor means is measured by a plurality of non-contact type position sensors. The manufacturing method of the resin sheet of description.   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 row comprising a mold roller having a concavo-convex shape formed on the peripheral surface, 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;
A die for extruding a sheet-shaped resin material from the discharge port;
An upper surface side heating means and a lower surface side heating means which are arranged downstream of the peeling roller and are provided so as to sandwich the resin material;
Cutting means provided further downstream and cutting the resin material into a predetermined length in the transport direction;
A warping amount measuring means for measuring a warping amount of the resin material after cutting,
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 resin material after peeling is heat-treated by the upper surface side heating means and the lower surface side heating means,
The resin material after heat treatment is cut,
An apparatus for producing a resin sheet, wherein the amount of warpage of the resin material after cutting is measured, and the set temperatures of the upper surface side heating means and the lower surface side heating means are controlled so that the warpage amount decreases.

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