JP2006056215A - Resin sheet manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a resin sheet manufacturing method capable of obtaining a desired cross-sectional shape when a resin sheet large in the thickness distribution in its width direction at molding is manufactured and manufacturing the resin sheet especially suitable for use in the light guide plate or various optical elements arranged on the back of a display device of every kind. <P>SOLUTION: The sheetlike resin material 14 extruded from a die 12 is held under pressure by a first mold roller 16 and the first nip roller 18 arranged in opposed relation to the first mold roller and the uneven shape on the surface of the first mold roller is transferred to a resin material. The resin material is wound around the peeling roller 24 arranged in opposed relation to the first mold roller to be peeled from the first mold roller and held under pressure by a second mold roller 26 and the second nip roller 27 arranged in opposed relation to the second mold roller to transfer the uneven shape on the surface of the second mold roller to the resin material. <P>COPYRIGHT: (C)2006,JPO&NCIPI

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 the optical performance as a Fresnel lens or a lenticular lens is exhibited by the uneven shape.

  As a method for producing such a resin sheet, various proposals have been made so far (see Patent Documents 1 to 4). In these proposals, the roller molding method is adopted from the viewpoint of improving productivity.

  For example, Patent Document 1 attempts to improve transferability by devising the cooling means until the resin sheet is peeled from the roller. Patent Document 2 discloses a method of manufacturing a Fresnel lens by winding a die around a roller.

  In Patent Document 3, a heat buffer member is arranged inside the forming roller to improve productivity and transferability. Patent Document 4 uses a corona discharge treatment to improve transferability and reduce defects.

  A typical roller forming system of these prior arts has a configuration 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 by being wound around.
JP-A-8-31025 JP-A-7-314567 JP 2003-53834 A JP-A-8-287530

  However, any of the above conventional proposals relates to a method for producing a relatively thin resin sheet, and is not suitable for producing a relatively thick resin sheet. In particular, when a resin sheet having a large thickness distribution in the width direction during molding is produced, it is very difficult to obtain a desired cross-sectional shape.

  For example, when PMMA (polymethylmethacrylate resin) is extruded and then subjected to roller molding, when the thickness distribution is given in the width direction and the difference in thickness between the thickest part and the thinnest part is 1 mm or more, the surface or There are various problems such as unevenness on the back surface (retraction due to shrinkage when the resin is cured), overall surface shape transfer rate is reduced, and sharp edge shapes cannot be transferred.

  The present invention has been made in view of such circumstances. When a resin sheet having a large thickness distribution in the width direction at the time of molding is produced, a desired cross-sectional shape can be obtained. It aims at providing the manufacturing method of the resin sheet suitable for using for the light-guide plate and various optical elements which are distribute | arranged to a back surface.

  In order to achieve the above object, the present invention sandwiches a sheet-shaped resin material extruded from a die between a first mold roller and a first nip roller disposed opposite to the first mold roller, and The uneven shape on the surface of the one mold roller is transferred to the resin material, and the resin material after the transfer is peeled off from the first mold roller by winding it on a peeling roller disposed opposite to the first mold roller. Then, the resin material after peeling is sandwiched between a second mold roller and a second nip roller disposed opposite to the second mold roller, and the uneven shape on the surface of the second mold roller is transferred to the resin material. A method for producing a resin sheet is provided.

  According to the present invention, the sheet-shaped resin material is sandwiched between the first mold roller and the first nip roller to transfer the concavo-convex shape to the resin material, peeled off from the first mold roller, and then the second mold roller The concavo-convex shape is transferred to the resin material by pressing between the mold roller and the second nip roller. In this way, by using a plurality of sets of mold rollers and nip rollers, even a resin sheet having a large thickness distribution in the width direction at the time of molding is gradually brought closer to the design shape, thereby obtaining a desired cross-sectional shape. Obtainable.

  In the present invention, it is preferable that the wrap angles of the resin material wound around the second mold roller and the second nip roller are each less than 5 degrees. In this state, by pressing between the second mold roller and the second nip roller, the flat resin material can be conveyed without being bent.

  Further, in the present invention, a mold roller and a nip roller having the same configuration as the second mold roller and the second nip roller are provided downstream of the second mold roller and the second nip roller in the resin material traveling direction. It is preferable that one or more sets are provided, and the uneven shape transferred to the resin material is gradually brought closer to the design shape. A predetermined effect can be obtained even with one set of the second die roller and the second nip roller, but the effect of the present invention can be further obtained by providing a plurality of sets and processing in stages.

  In the present invention, the sheet-shaped resin material extruded from the die is pressed between the first front roller and the first back roller disposed opposite to the first front roller, and the first An uneven shape on the surface of the front mold roller and an uneven shape on the surface of the first back roller are transferred to the resin material, and the resin material after the transfer is transferred to the peeling roller disposed to face the first surface roller. The resin material is peeled off from the first front roller by winding and the peeled resin material is sandwiched between the second front roller and the second back roller disposed opposite to the second front roller. There is provided a method for producing a resin sheet, wherein the uneven shape on the surface of the second front roller and the uneven shape on the surface of the second back roller are transferred to the resin material.

  According to the present invention, when forming the concavo-convex shape on the front and back surfaces of the resin material, since the transfer is performed with the set of the pair of second rollers after the transfer with the set of the pair of first rollers, the width direction at the time of molding Even if the resin sheet has a large thickness distribution, a desired cross-sectional shape can be obtained by gradually approaching the design shape.

  In the present invention, it is preferable that a wrap angle of the resin material wound around the second front roller and the second back roller is less than 5 degrees. In this state, by pressing between the second front roller and the second back roller, the plate-shaped resin material can be conveyed without being bent.

  In the present invention, the second front roller and the second back roller have the same configuration as the second front roller and the second back roller on the downstream side in the resin material traveling direction of the second front roller and the second back roller. It is preferable to provide one or more sets of a front roller and a back roller, and gradually bring the uneven shape transferred to the resin material closer to the design shape. The predetermined effect can be obtained even with one set of the second front roller and the second back roller, but the effect of the present invention can be further obtained by providing a plurality of sets and processing in stages.

  In the present invention, it is preferable that an uneven shape substantially the same as the uneven shape on the surface of the first back roller is formed on the surface of the peeling roller. If the unevenness is formed on the peeling roller, transfer can be performed in cooperation with the first front roller, and the effect of the present invention can be obtained.

  In the present invention, a sheet-like resin material extruded from a die is sandwiched between a first mirror roller and a second mirror roller disposed opposite to the first mirror roller, and the resin material is pressed to a predetermined thickness. The resin material after molding is wound around a peeling roller disposed opposite to the first mirror roller so as to peel from the first mirror roller, and the resin material after peeling is separated from a mold roller. There is provided a method for producing a resin sheet, characterized in that a pressing force is applied by a nip roller disposed opposite to the mold roller, and the uneven shape on the surface of the mold roller is transferred to the resin material.

  According to the present invention, since the resin material that has been flattened after being peeled off from the first mirror roller is transferred by the mold roller and the nip roller, a desired cross-sectional shape can be obtained, and the resin material The flat state can be easily maintained.

  In the present invention, it is preferable that the wrap angles of the resin material wound around the mold roller and the nip roller are each less than 5 degrees. In this state, by pressing between the mold roller and the nip roller, the flat resin material can be conveyed without being bent.

  Further, in the present invention, it is preferable that a plurality of sets of the mold roller and the nip roller are provided, and the uneven shape transferred to the resin material is gradually approximated to the design shape. A predetermined effect can be obtained even with one set of the mold roller and the nip roller, but the effect of the present invention can be further obtained by providing a plurality of sets and processing in stages.

  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 is 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, a desired cross-sectional shape can be obtained even with a resin sheet having a large thickness distribution in the width direction during molding.

  Hereinafter, a preferred embodiment (first embodiment) 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.

  The 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 first die roller having a concavo-convex shape formed on the surface. 16, a first nip roller 18 disposed opposite to the first mold roller 16, a peeling roller 24 disposed opposite to the first mold roller 16, and a second disposed on the upper side of the resin material 14 downstream of the peeling roller 24. A mold roller 26, a second nip roller 27 disposed opposite to the second mold roller 26 with the resin material 14 therebetween (disposed on the lower side of the resin material 14), and further disposed on the upper side of the resin material 14 downstream. A third mold roller 28, a third nip roller 29 disposed opposite to the third mold roller 28 with the resin material 14 interposed therebetween (disposed on the lower side of the resin material 14), and further downstream of the resin material 14 A fourth mold roller 30 disposed on the side, a fourth nip roller 31 disposed opposite to the fourth mold roller 30 with the resin material 14 interposed therebetween (disposed below the resin material 14), and a resin further downstream A fifth die roller 32 disposed on the upper side of the material 14, a fifth nip roller 33 disposed opposite to the fifth die roller 32 with the resin material 14 interposed therebetween (disposed on the lower side of the resin material 14), and more Composed.

  The slit size of the die 12 is formed such that the width of the molded molten resin material 14 is wider than the width of the first mold roller 16, and the molten resin material 14 extruded from the die 12 is the first mold roller. 16 and the first nip roller 18 are arranged so as to be pushed out.

  Regular irregularities are formed on the surface of each mold roller (first mold roller 16 to fifth mold roller 32). This regular uneven | corrugated shape can be made into the inversion shape of the resin material 14 after a shaping | molding shown by FIG. 2, for example. 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 on a straight line.

  That is, the back surface of the resin material 14 is a flat surface, and a linear uneven pattern parallel to the arrow is formed on the surface of the resin material 14. This arrow indicates the traveling direction of the resin material 14. Therefore, an endless groove having an inverted shape of the end face 14A may be formed on the surface of each type roller.

  However, even if such an endless groove is formed in the first die roller 16 which is the most upstream die roller, it is often difficult for the resin material 14 to follow this shape, and the design shape is determined by the latter die roller. Therefore, a plurality of sets of mold rollers may be provided so that the uneven shape transferred to the resin material 14 gradually approaches the design shape.

  FIG. 3 is a cross-sectional view of the resin material 14 at each stage of molding. Among these, (a) is a cross section of the resin material 14 immediately after the die 12, and (e) is a cross section of the design shape of the product. Intermediate (b), (c), and (d) are cross sections of the process in which the resin material 14 gradually approaches the design shape.

  Therefore, it is only necessary to form endless grooves having such a reverse shape on each type roller. In addition, the imaginary line (two-dot chain line) in (a)-(d) shows the cross section of the design shape of a product.

  The details of the uneven pattern shape on the surface of the resin material 14 will be described later.

  The material of each type of roller is various steel members, stainless steel, copper, zinc, brass, these metal materials are cored and rubber-lined 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 each mold roller surface depends on the concavo-convex pattern (pitch, depth, etc.) and the material of the mold roller surface, but generally a combination of cutting with NC lathe and finish buffing is used. Preferably employed. In addition, other known processing methods (grinding processing, ultrasonic processing, electric discharge processing, etc.) can also be employed.

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

  Each type roller is rotationally driven in a direction indicated by an arrow in FIG. 1 at a predetermined peripheral speed by a driving means (not shown). Each die roller is provided with temperature adjusting means. By providing such temperature adjusting means, it is possible to control to suppress the temperature rise or rapid temperature drop of each type roller due to the high temperature resin material 14. The configuration of the temperature adjusting means will be described later.

  Each nip roller (first nip roller 18 to fifth nip roller 33) is disposed opposite to each die roller (first die roller 16 to fifth die roller 32), and is a roller for sandwiching the resin material 14 with each die roller. It is.

  The peeling roller 24 is disposed so as to face the first mold roller 16, sandwiches the resin material 14 with the first mold roller 16, and wraps the resin material 14 to peel the resin material 14 from the first mold roller 16. This roller is disposed 180 degrees downstream of the first nip roller 18 with the first mold roller 16 in between.

  The surface of each nip roller and 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. And the surface roughness of each nip roller and the peeling roller 24 is preferably 0.5 μm or less, more preferably 0.2 μm or less, in terms of Ra.

  The materials of each nip roller and peeling roller 24 are various steel members, stainless steel, copper, zinc, brass, those metal materials made of a metal core and a rubber lining on the surface, these metal materials being HCr plated, Cu plated Ni-plated or other plated materials, ceramics, and various composite materials can be used.

  Each of the nip rollers and the peeling roller 24 is driven to rotate in a direction indicated by an arrow in FIG. 1 at a predetermined peripheral speed by a driving unit (not shown). In addition, although the structure which does not provide a drive means in each nip roller 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.

  In the case where driving means is provided for each mold roller and each nip roller, a configuration in which the respective driving speeds can be preferably adopted. Thus, for example, the second mold roller 26 and the second nip roller 27, the third mold roller 28 and the third nip roller 29, the fourth mold roller 30 and the fourth nip roller 31, the fifth mold roller 32 and the fifth nip roller 33 are sequentially arranged. An operation method in which the speed is gradually increased (within a range of at most several%) from the peripheral speed of the first die roller 16 can be employed.

  Each of the nip rollers and the peeling roller 24 is provided with a pressing means (not shown) so that the resin material 14 between each mold roller and each of the nip rollers and the peeling roller 24 can be pressed with a predetermined pressure. It has become. Each of the pressurizing means is configured to apply pressure in the normal direction at the contact point between each mold roller, each nip roller, and the peeling roller 24, and is a known motor drive means, air cylinder, hydraulic cylinder, or the like. Various means can be adopted.

  Each nip roller and peeling roller 24 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 each nip roller and peeling roller 24 (opposite to each type roller), a configuration in which a crown shape (middle and high shape) is adopted, and an axial center portion of the roller A configuration of a roller having a strength distribution that increases the rigidity of the roller, a configuration combining these, and the like can be employed.

  Each nip roller and peeling roller 24 is provided with temperature adjusting means. The separation roller 24, the second mold roller 26 and the second nip roller 27, the third mold roller 28 and the third nip roller 29, the fourth mold roller 30 and the fourth nip roller 31, the fifth mold roller 32 and the fifth nip roller 33 It can be controlled individually so that the roller temperature can be lowered in order. By setting in this way, the uneven pattern shape on the surface of the resin material 14 can be improved.

  That is, if the set temperature of the first nip roller 18 is too low, the resin material 14 in a molten state is rapidly cooled, and distortion is generated in the resin material 14, which is not preferable, and the set temperature of the fifth nip roller 33 is increased. If it is too much, the resin material 14 is peeled off from the fifth type roller 32 and the surface of the resin material 14 becomes a free surface state.

  Further, even when the set temperature of the peeling roller 24 is too low, the viscosity of the resin material 14 increases, and it is not preferable because the resin material 14 cannot be wound around the peeling roller 24.

  The roller set temperature of each mold roller, peeling roller 24, and each nip roller 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 optimum value should be selected according to the outer diameter of the first-type roller 16 and the uneven pattern shape of the first-type roller 16.

  As each roller temperature adjusting means of each mold roller, peeling roller 24 and each nip roller, a configuration in which oil whose temperature is adjusted is circulated inside the rollers 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.

  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.

  As the measurement points by such surface temperature measuring means, for example, a plurality of points in the width direction of the resin material 14 between the die 12 and the first nip roller 18 and a plurality of points in the width direction of the resin material 14 immediately after the peeling roller 24 are used. The surface of the resin material 14 currently wound around the point | piece roller 16 or the peeling roller 24 in the width direction (the opposite surface side of a roller) etc. can be considered.

  In addition, the monitoring result of the 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 each roller. It is also possible to operate by feedforward control without providing the surface temperature measuring means.

  A tension detecting means for detecting the tension of the resin material 14 or a plate thickness detecting means (thickness sensor) for detecting the thickness of the resin material 14 is provided on the resin sheet production line 10 in FIG. It can also be preferably adopted. Moreover, the detection result by such a detection means can be compared with a set value and fed back to a draw control described later.

  Furthermore, it is also possible to provide a cooling device in the resin sheet production line 10 of FIG. For example, an air nozzle is provided, and air with controlled temperature and ejection amount is blown to each nip roller to assist temperature control of each nip roller, or an air nozzle is provided between the nip rollers and the temperature and ejection amount on the back surface of the resin material 14 Can be used to assist temperature control of the resin material 14.

  When such a cooling device is provided, the air temperature and the air supply amount (spraying flow rate) of the cooling device 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 resin material The optimum value should be selected according to the conveyance speed of 14, the outer diameter of the first mold roller 16, the uneven pattern shape of the first mold roller 16, the set temperature of each nip roller, and the like.

  Further, a slow cooling zone (or an annealing zone (a warp correction zone by one-side heating or the like)) can be provided downstream of the resin sheet production line 10 in FIG. Such a slow cooling zone is provided in order to prevent a rapid temperature change of the resin material 14 downstream of the resin sheet production line 10.

  For example, in a configuration such as the first type roller 16, the first nip roller 18, and the peeling roller 24, the inside of the compression / tensile stress generated in the resin material 14 when the resin is molded around the roller. Residual stress is released (annealed) by partial or whole surface heating to correct warpage.

  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 (or annealing zone), 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 can be adopted. 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 cleaning device (cleaning zone), a defect inspection device (inspection zone), a laminating device, a side cutter, a cross cutter, and an accumulating unit are provided in the downstream of the resin sheet production line 10 in FIG. 1 (downstream of the slow cooling zone). It is done.

  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 sandwiched between the first mold roller 16 and the first nip roller 18 disposed so as to face the first mold roller 16, and the uneven shape on the surface of the first mold roller 16 is changed to the resin material. 14, and the resin material 14 is peeled off from the first mold roller 16 by being wound around a peeling roller 24 disposed opposite to the first mold roller 16. In addition, before the peeling, the resin material 14 is sandwiched between the first mold roller 16 and the peeling roller 24 to transfer the uneven shape on the surface of the first mold roller 16 to the resin material 14.

  The resin material 14 peeled off from the first mold roller 16 is conveyed in the horizontal direction, and then sandwiched between the second mold roller 26 and the second nip roller 27 disposed opposite to the second mold roller 26, and the second mold roller 26 is transferred to the resin material 14, and is pressed between the third die roller 28 and the third nip roller 29 disposed opposite to the third die roller 28, and the uneven shape on the surface of the third die roller 28 is transferred to the resin material. 14, and the fourth mold roller 30 and the fourth nip roller 31 disposed opposite to the fourth mold roller 30 are pressed to transfer the uneven shape on the surface of the fourth mold roller 30 to the resin material 14, thereby The roller 32 and the fifth nip roller 33 disposed opposite to the fifth mold roller 32 are pressed to transfer the uneven shape on the surface of the fifth mold roller 32 to the resin material 14.

  Next, if necessary, the product is gradually cooled by passing through a slow cooling zone (or an annealing zone), and after being distorted, it is cut into a predetermined length at a downstream product take-off portion to obtain a resin sheet product. Accommodate.

  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 first die roller 16 is also substantially matched with this.

  On the other hand, the subsequent mold rollers (second mold roller 26, third mold roller 28, fourth mold roller 30, and fifth mold roller 32) and nip rollers (second nip roller 27, third nip roller 29, fourth nip roller 31, The fifth nip roller 33) is driven by a so-called draw control operation method in which the speed is gradually increased from the peripheral speed of the first type roller 16 in the order of the second, third, fourth, and fifth rollers. The draw value between these mold rollers and nip rollers is preferably 0 to 3%, and more preferably 0 to 1%.

  It should be noted that the speed unevenness of each roller is preferably controlled to be within 1% of the set value.

  The pressing pressure of each nip roller (the first nip roller 18 to the fifth nip roller 33) and the peeling roller 24 to each die roller (the first die roller 16 to the fifth die roller 32) is converted into a linear pressure (due to elastic deformation of each nip roller). It is preferably 0 to 200 kN / m (0 to 200 kgf / cm), more preferably 0 to 100 kN / m (0 to 100 kgf / cm). preferable.

  It should be noted that not only the pressing pressure of each nip roller is appropriately controlled so that the prescribed thickness of the resin material 14 in the product state can be obtained, but also each nip roller (first nip roller 18 to fifth nip roller 33) and peeling roller. It is also preferable to appropriately control the clearance between the roller 24 and each die roller (the first die roller 16 to the fifth die roller 32).

  The temperature control of each nip roller (the first nip roller 18 to the fifth nip roller 33) and the separation roller 24 is performed in the order of the separation roller 24, the second nip roller 27, the third nip roller 29, the fourth nip roller 31, and the fifth nip roller 33. It is preferable to set for each individual roller so as to be reduced.

  And it is preferable that the resin material 14 in the location of the 5th nip roller 33 is the temperature below the softening point Ta of resin. At this time, when a polymethylmethacrylate resin is used as the resin material 14, the set temperature of the fifth nip roller 33 can be 50 to 110 ° C.

  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 showing a state in which the end surface 14A of the molded resin material 14 is cut out on a straight line. 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 using the resin material 14 after shaping | molding for a light-guide plate, it is preferable to make the width | variety p of V-groove 50 into 2 mm or more, and to make apex angle (theta) 1 of V-groove 50 into 40-80 degree | times. 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. 4 is a perspective view of a state in which the end surface 14A of the resin material 14 after molding is cut out on a straight line. 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. 4, 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 first mold roller 16 does not need to be the inverted shape of the surface of the resin material 14 in FIG. 2 or 4, and the product shape of the resin material 14 is taken into account the shrinkage allowance of the resin material 14. 2 or FIG. 4 may be offset from this shape.

  Next, another embodiment (second embodiment) of the method for producing a resin sheet according to the present invention will be described in detail. FIG. 5 is a configuration diagram showing a resin sheet production line 10 ′ to which the resin sheet production method according to the present invention is applied. In addition, the same code | symbol is attached | subjected about the member similar to 1st Embodiment shown by FIG. 1, and the description is abbreviate | omitted.

  In this embodiment, instead of the nip rollers (first nip roller 18 to fifth nip roller 33) and the peeling roller 24 of the first embodiment, back type rollers (first back type roller 35 to fifth back type roller 43) and peeling are used. A roller 24 'is used. In addition, each type | mold surface roller (The 1st surface type | mold roller 16-the 5th surface type roller 32) is the same as 1st Embodiment, These are the 1st type | mold roller 16-5th type | mold roller 32 of 1st Embodiment. Applicable.

  In the resin sheet production line 10 ′, the uneven pattern shape is formed on the surface of the resin sheet 14 by each of the front roller (first front roller 16 to fifth front roller 32), which is the same as in the first embodiment. It is. The difference from the first embodiment is that an uneven pattern shape is also formed on the back surface of the resin sheet 14.

  As described above, the back mold rollers (first back mold roller 35 to fifth back mold roller 43) and the peeling roller 24 ′ function in substantially the same manner as the nip rollers and the peeling roller 24 of the first embodiment. Therefore, various configurations such as a surface finish state, a configuration in which a driving unit is provided, a configuration in which a pressurizing unit is provided, a configuration in which a temperature adjusting unit is provided, and a configuration in which bending due to a reaction force of pressure is less likely to occur. What is necessary is just to carry out similarly to each nip roller of 1 embodiment.

  However, since the concave / convex pattern shape is formed on the surfaces of the back roller (first back roller 35 to fifth back roller 43) and the peeling roller 24 ', the bending due to the reaction force of pressure is less likely to occur. In the configuration, it is difficult to adopt a configuration in which a backup roller is provided on the back side of the roller (opposite side of each type roller) or a configuration in which a crown shape (middle and high shape) is adopted.

  In the resin sheet production line 10 ′ of FIG. 5, as in the first embodiment, a cooling device or a slow cooling zone (or annealing zone) can be provided as necessary. What is necessary is just to carry out similarly to 1st Embodiment.

  Next, a method for producing a resin sheet using the resin sheet production line 10 ′ shown in FIG. 5 will be described.

  The sheet-shaped resin material 14 extruded from the die 12 is pressed between the first mold roller 16 and the first back mold roller 35 disposed so as to face the first mold roller 16, and the first mold roller 16 and the first back mold are pressed. The uneven shape on the surface of the roller 35 is transferred to the resin material 14, and then wound around the peeling roller 24 ′ to peel the resin material 14 from the first type roller 16.

  The resin material 14 peeled off from the first mold roller 16 is transported in the horizontal direction, and in sequence, each mold roller (second mold roller 26 to fifth mold roller 32) and each back mold roller (second back mold roller 37 to second mold). Unevenness of the surfaces of the respective mold rollers (second mold roller 26 to fifth mold roller 32) and the respective back mold rollers (second back mold roller 37 to fifth back mold roller 43). The shape is transferred to the front and back surfaces of the resin material 14. Then, if necessary, it is gradually cooled by passing through a slow cooling zone (or an annealing zone), and after being distorted, it is cut into a predetermined length at a downstream product take-off portion, and as a resin sheet product. Accommodate.

  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. Therefore, the peripheral speeds of the first mold roller 16 and the first back mold roller 35 are substantially matched with this.

  The pressing pressure of each back mold roller (first back mold roller 35 to fifth back mold roller 43) and the peeling roller 24 'against each mold roller (first mold roller 16 to fifth mold roller 32) is converted into linear pressure. It is preferably 0 to 200 kN / m (0 to 200 kgf / cm), and preferably 0 to 100 kN / m (0 to 100 kgf / cm) (value converted on the assumption that surface contact due to elastic deformation of each nip roller is line contact). cm).

  In addition, the pressing pressure of each back mold roller (the first back mold roller 35 to the fifth back mold roller 43) and the peeling roller 24 ′ is appropriately set so that the specified thickness in the product state of the resin material 14 is obtained. In addition to controlling, the clearance between each back mold roller (first back mold roller 35 to fifth back mold roller 43) and the peeling roller 24 'and each mold roller (first mold roller 16 to fifth mold roller 32). It is also possible to preferably employ the proper control.

  The temperature control of each back mold roller (the first back mold roller 35 to the fifth back mold roller 43) and the peeling roller 24 ′ is performed by controlling the peeling roller 24 ′, the second back mold roller 37, the third back mold roller 39, and the fourth. It is preferable to set each roller so that the roller temperature can be lowered in the order of the back die roller 41 and the fifth back die roller 43.

  And it is preferable that the resin material 14 in the location of the 5th back type | mold roller 43 is the temperature below the softening point Ta of resin. At this time, when a polymethylmethacrylate resin is employed as the resin material 14, the set temperature of the fifth back roller 43 can be 50 to 110 ° C.

  According to the second embodiment using the resin sheet production line 10 ′, a desired uneven pattern shape can be formed on the front and back surfaces of the resin material 14. Examples of such a concave-convex pattern shape on the back surface include a fine pattern disclosed in JP-A-7-314567, a prism shape (10 to 200 μm pitch, apex angle 45 to 100 °), a lenticular lens, a Fresnel lens, Examples include embossing (light diffusion pattern).

  Further, the present invention can be preferably applied to the case where the molded resin material 14 as described above with reference to FIGS. 2 and 4 is used for the light guide plate.

  For example, when a roller is formed after extruding PMMA, a thickness distribution is given in the width direction, and the thickness difference between the thickest part and the thinnest part is increased as shown in FIG. 2 and FIG. Depending on the processing conditions, so-called “squeezing” often occurs on the back surface due to shrinkage when the resin is cured.

  That is, in the thick part of the resin material 14, a difference occurs in the cooling rate between the surface and the inside of the resin material 14, and a phenomenon in which the inside is in a plastic state occurs while the vicinity of the surface is in an elastic state. Then, due to the internal shrinkage that hardens late, a concave portion is generated in the surface portion of the corresponding resin material 14.

  For example, when a lenticular lens is molded, a shallow concave groove corresponding to the back surface is often generated with respect to the bowl-shaped surface.

  On the other hand, the reverse concavo-convex shape is formed on the surface of each of the back mold rollers (first back mold roller 35 to fifth back mold roller 43) and the peeling roller 24 ′, and the resin is formed in a state where so-called “shrinkage” occurs. The back surface of the material 14 can be just flat. If this method is adopted, the effect of the present embodiment can be exhibited even for a lenticular lens or a resin material 14 having a design shape such that the back surface is flat as shown in FIGS.

  Next, still another embodiment (third embodiment) of the method for producing a resin sheet according to the present invention will be described in detail. FIG. 6 is a configuration diagram showing a resin sheet production line 10 ″ to which the resin sheet production method according to the present invention is applied. In addition, the same code | symbol is attached | subjected about the member similar to 1st Embodiment shown by FIG. 1, and the description is abbreviate | omitted.

  In the present embodiment, a mirror roller 17 is used instead of the first mold roller 16 of the first embodiment. Other configurations are the same as those of the first embodiment, but only the roller names are different. That is, only the mirror roller 17 (corresponding to the first mirror roller of claim 8), the first mold roller 26, the second mold roller 28, the third mold roller 30, and the fourth mold roller 32 are the first embodiment and the roller name. Is different. The first nip roller 18 corresponds to the second mirror surface roller of claim 8.

  In the resin sheet production line 10 ″, the uneven pattern shape is formed on the surface of the resin sheet 14 by the respective mold rollers (the first mold roller 26 to the fourth mold roller 32), which is the same as in the first embodiment. . The difference from the first embodiment is that the concave-convex pattern shape is not formed on the surface of the resin sheet 14 until it passes through the peeling roller 24, and is in a flat plate state.

  Since the mirror roller 17 is different from the first mold roller 16 of the first embodiment only in that the uneven pattern shape is not formed on the surface, the description of the configuration regarding the mirror roller 17 is omitted. The surface of the mirror roller 17 may be the same as that of the first nip roller 18 of the first embodiment, and the surface roughness of the roller surface is preferably 0.5 μm or less in terms of Ra, and 0.2 μm or less. Is more preferable.

  Next, a resin sheet manufacturing method using the resin sheet manufacturing line 10 ″ shown in FIG. 6 will be described.

  The sheet-like resin material 14 extruded from the die 12 is pressed between the mirror roller 17 and the first nip roller 18 disposed opposite to the mirror roller 17, and the resin material 14 is molded into a flat plate having a predetermined thickness. The material 14 is peeled off from the mirror roller 17 by being wound around a peeling roller 24 disposed opposite to the mirror roller 17. In addition, before peeling, the resin material 14 is pinched by the mirror surface roller 17 and the peeling roller 24, and the resin material 14 is rolled to a predetermined thickness.

  The resin material 14 peeled off from the mirror surface roller 17 is conveyed in the horizontal direction, and then sandwiched between the first mold roller 26 and the second nip roller 27 disposed opposite to the first mold roller 26, and the surface of the first mold roller 26 Is transferred to the resin material 14 and pressed between the second mold roller 28 and the third nip roller 29 disposed opposite to the second mold roller 28, and the uneven shape on the surface of the second mold roller 28 is applied to the resin material 14. The third mold roller 30 and the fourth nip roller 31 disposed opposite to the third mold roller 30 are pressed to transfer the uneven shape on the surface of the third mold roller 30 to the resin material 14, and the fourth mold roller 32. And a fifth nip roller 33 disposed opposite to the fourth mold roller 32 to transfer the uneven shape on the surface of the fourth mold roller 32 to the resin material 14.

  Next, if necessary, the product is gradually cooled by passing through a slow cooling zone (or an annealing zone), and after being distorted, it is cut into a predetermined length at a downstream product take-off portion to obtain a resin sheet product. Accommodate.

  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. Therefore, the peripheral speed of the mirror roller 17 is also made to substantially coincide with this.

  On the other hand, the subsequent mold rollers (first mold roller 26, second mold roller 28, third mold roller 30, and fourth mold roller 32) and nip rollers (second nip roller 27, third nip roller 29, fourth nip roller 31, The fifth nip roller 33) is driven by a so-called draw control operation method in which the speed is gradually increased from the peripheral speed of the mirror roller 17 in the order of the first, second, third and fourth rollers. The draw value between these mold rollers and nip rollers is preferably 0 to 3%, and more preferably 0 to 1%.

  Each nip roller (the first nip roller 18 to the fifth nip roller 33) and the pressing pressure of the peeling roller 24 on the mirror roller 17 and each type roller (the first type roller 26 to the fourth type roller 32) are converted into linear pressures (each nip roller). It is preferable that the surface contact due to the elastic deformation is converted to a line contact), and is preferably 0 to 200 kN / m (0 to 200 kgf / cm), and 0 to 100 kN / m (0 to 100 kgf / cm). More preferably.

  It should be noted that not only the pressing pressure of each nip roller is appropriately controlled so that the prescribed thickness of the resin material 14 in the product state can be obtained, but also each nip roller (first nip roller 18 to fifth nip roller 33) and peeling roller. It is also preferable to appropriately control the clearance between the roller 24 and the mirror surface roller 17 and each type roller (the first type roller 26 to the fourth type roller 32).

  The temperature control of each nip roller (the first nip roller 18 to the fifth nip roller 33) and the peeling roller 24 is performed by controlling the peeling roller 24, the second type roller 26 and the second nip roller 27, the third nip roller 29, the fourth nip roller 31, and the fifth nip roller. It is preferable to set for each roller so that the roller temperature can be lowered in the order of 33.

  And it is preferable that the resin material 14 in the location of the 5th nip roller 33 is the temperature below the softening point Ta of resin. At this time, when a polymethylmethacrylate resin is used as the resin material 14, the set temperature of the fifth nip roller 33 can be 50 to 110 ° C.

  According to each manufacturing method of the resin sheet which concerns on this invention demonstrated above, even if it is a resin sheet with a large thickness distribution of the width direction at the time of shaping | molding, 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, the number and arrangement of nip rollers or mold rollers can take various forms other than the present embodiment as long as the same function can 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 on a straight line Cross-sectional view of resin material at each stage of molding The perspective view of the state which cut off the end face of the resin material after molding on a straight line The block diagram which shows the other example of the production line of the resin sheet to which this invention is applied The block diagram which shows the further another example of the production line of the resin sheet to which this invention is applied 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 ... 1st type | mold roller, 17 ... Mirror surface roller, 18 ... 1st nip roller, 24 ... Peeling roller, 26 ... 2nd type | mold roller, 28 ... 1st 3 type roller, 30 ... 4th type roller, 32 ... 5th type roller

Claims (12)

The sheet-shaped resin material extruded from the die is clamped between the first mold roller and the first nip roller disposed opposite to the first mold roller,
The uneven shape on the surface of the first mold roller is transferred to the resin material,
The resin material after the transfer is peeled off from the first mold roller by winding it on a peeling roller disposed opposite to the first mold roller,
The resin material after peeling is sandwiched between a second mold roller and a second nip roller disposed opposite to the second mold roller,
A method for producing a resin sheet, wherein the uneven shape on the surface of the second mold roller is transferred to the resin material.   2. The method for producing a resin sheet according to claim 1, wherein wrap angles of the resin material wound around the second mold roller and the second nip roller are each less than 5 degrees.   One or more sets of mold rollers and nip rollers having the same configuration as the second mold rollers and the second nip rollers are provided downstream of the second mold rollers and the second nip rollers in the resin material running direction. The method for producing a resin sheet according to claim 1, wherein the concavo-convex shape transferred to the resin material is gradually approximated to a design shape. The sheet-shaped resin material extruded from the die is clamped between the first front roller and the first back roller disposed opposite to the first front roller,
Transferring the uneven shape on the surface of the first front roller and the uneven shape on the surface of the first back roller to the resin material;
The resin material after the transfer is peeled off from the first front roller by wrapping it on a peeling roller disposed opposite to the first front roller.
The resin material after peeling is clamped between a second front roller and a second back roller disposed opposite to the second front roller,
A method for producing a resin sheet, wherein the uneven shape on the surface of the second front roller and the uneven shape on the surface of the second back roller are transferred to the resin material.   The method for producing a resin sheet according to claim 4, wherein the wrap angles of the resin material wound around the second front roller and the second back roller are each less than 5 degrees.   A front roller and a back mold having the same configuration as the second front roller and the second back roller on the downstream side in the resin material traveling direction of the second front roller and the second back roller. The method for producing a resin sheet according to claim 4 or 5, wherein one or more sets with a roller are provided, and the uneven shape transferred to the resin material is gradually approximated to a design shape.   7. The resin sheet production according to claim 4, wherein an uneven shape substantially the same as the uneven shape on the surface of the first back roller is formed on the surface of the peeling roller. 8. Method. The sheet-like resin material extruded from the die is sandwiched between the first mirror roller and the second mirror roller disposed opposite to the first mirror roller,
Molding the resin material to a predetermined thickness,
The resin material after molding is peeled off from the first mirror roller by wrapping it on a peeling roller disposed opposite to the first mirror roller,
The resin material after peeling is clamped between a mold roller and a nip roller disposed opposite to the mold roller,
A method for producing a resin sheet, wherein the uneven shape on the surface of the mold roller is transferred to the resin material.   The method for producing a resin sheet according to claim 8, wherein the wrap angles of the resin material wound around the mold roller and the nip roller are each less than 5 degrees.   The method for producing a resin sheet according to claim 8 or 9, wherein a plurality of sets of the mold roller and the nip roller are provided, and the concavo-convex shape transferred to the resin material is gradually approximated to a design shape.   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. The manufacturing method of the resin sheet of 1 item | term. The thickness of the thinnest part of the said resin material is 5 mm or less, The manufacturing method of the resin sheet of any one of Claims 1-11 characterized by the above-mentioned.

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