JP2012144033A - Method of manufacturing resin sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing a resin sheet by which a transfer rate is increased.SOLUTION: The method of manufacturing the resin sheet includes a sheet manufacturing step of manufacturing a continuous resin sheet and a transfer step of transferring a transfer mold using a shaping roll. In the sheet manufacturing step, a resin sheet having a multi-layered structure having a shape transfer layer (A) constituting the sheet surface and a main layer (B) adjacent to the inside of the shape transfer layer (A) is manufactured. An MFR (a measured value measured based on JIS K7210 at 200°C and 49 N load) of the shape transfer layer (A) to the MTF of the main layer (B) is controlled to ≥1.5.

Description

  The present invention relates to a method for producing a resin sheet having a shape on the surface.

  As a method for producing a resin sheet having a shape on the surface (surface shape transfer resin sheet), an extruder is used to extrude the resin from a die in a heated and melted state, and a continuous resin sheet (continuous resin sheet) is produced and transferred. A method of transferring the shape of a transfer mold onto the surface of a continuous resin sheet using a mold is known (for example, see Patent Document 1). In this method, the continuous resin sheet is sandwiched and pressed between the first pressing roll and the second pressing roll that are separated in the thickness direction of the sheet, and the shape of the transfer mold formed on the surface of the second pressing roll is It is transferred to a continuous resin sheet.

JP 2009-220555 A

  In recent years, a resin sheet having a shape on its surface has been required to have a shape with a large aspect ratio, which is a ratio of the height to the pitch (arrangement interval) of unit shapes. However, in the conventional method for producing a resin sheet, the resin does not sufficiently enter the transfer mold depth, and the height of the shape transferred to the resin sheet is not always sufficient. Therefore, an improvement in transfer rate (H ′ / H), which is a ratio of the maximum height H ′ of the surface shape transferred to the resin sheet to the groove depth H of the transfer mold, is demanded.

  The present invention has been made to solve such a problem, and an object of the present invention is to provide a method for producing a resin sheet capable of improving the transfer rate.

  As a result of intensive studies to solve the above-mentioned problems, the present inventor aims to improve the transfer rate by laminating resins having different predetermined conditions in the thickness direction of the sheet and molding them under appropriate conditions. The present invention has been found to be possible.

  That is, the method for producing a resin sheet according to the present invention uses a sheet production process for producing a continuous resin sheet by continuously extruding a heated and melted resin from a die, and a shape roll having a transfer mold formed on the peripheral surface. A transfer step of transferring a transfer mold onto the sheet surface of the continuous resin sheet, wherein the transfer step includes pressing the continuous resin sheet manufactured by the sheet manufacturing step between a pressing roll and a shape roll. The transfer start process starts to transfer the shape of the transfer mold of the shape roll to the continuous resin sheet, and the continuous resin sheet having the transfer mold shape transferred to the sheet surface in the transfer start process is Including a transporting process for transporting the sheet while closely contacting the sheet, and a peeling process for peeling the continuous resin sheet transported in the transporting process from the peripheral surface of the shape roll. The continuous resin sheet produced by the manufacturing process has a multilayer structure having a plurality of layers in the thickness direction of the sheet, and the shape transfer layer (A) and shape constituting the sheet surface arranged on the shape roll side in the transfer start process At least two main layers (B) adjacent to the back side of the transfer layer, and a shape transfer layer for the MFR of the main layer (B) (measured value measured at a temperature of 200 ° C. and a load of 49 N in accordance with JISK7210) The ratio of the MFR in A) is 1.5 or more.

  According to such a method for producing a resin sheet of the present invention, the resin sheet has a multilayer structure, and the fluidity of the resin (a) constituting the shape transfer layer (A) is determined by the resin constituting the main layer (B) ( The fluidity of b) can be improved. Thereby, the resin (a) can be suitably entered into the transfer mold, and the transfer rate can be improved. By using a high fluidity resin for the resin (a) constituting the surface layer (A), the shape transfer rate can be improved.

  Here, the transfer process includes a preload process for pressing the continuous resin sheet manufactured by the sheet manufacturing process between the preload roll and the press roll, and the continuous resin sheet pressed in the preload process on the peripheral surface of the press roll. Including a preliminary transporting step of transporting the sheet while being in close contact, and in the transfer start step, it is preferable that the continuous resin sheet transported in the preliminary transporting step is sandwiched and pressed between the pressing roll and the shape roll. Thus, the thickness of the continuous resin sheet can be adjusted and the sheet temperature can be adjusted by the preloading process sandwiched between the preloading roll and the pressing roll, and the shape transfer rate can be improved.

  Further, when the glass transition temperature of the resin (a) constituting the shape transfer layer (A) is Tg (a), the surface temperature of the shape transfer layer (A) immediately before contacting the peripheral surface of the shape roll is (Tg (A) +50) ° C. to (Tg (a) +150) ° C., and the surface temperature of the shape transfer layer (A) immediately after peeling from the peripheral surface of the shape roll is (Tg (a) -10). It is preferable that it is the range of degree-C-(Tg (a) +40) degreeC.

  The ratio of the thickness of the shape transfer layer (A) to the thickness of the main layer (B) is preferably in the range of 1/200 to 1/10. If the thickness ratio of the resin sheet (shape transfer layer (A) / main layer (B)) is in the range of 1/200 to 1/10 before the shape is transferred, the transfer rate is further improved. Can do.

  Moreover, it is preferable to provide the heating process which heats the sheet | seat surface of the shape transfer layer (A) of the continuous resin sheet conveyed in close contact with the surrounding surface of a press roll immediately before a transfer start process.

  In addition, it is preferable that a plurality of groove portions continuous in the circumferential direction of the shape roll are provided side by side in the rotation axis direction of the shape roll, and the arrangement interval P of the plurality of groove portions is 200 μm to 500 μm.

  Moreover, it is preferable that a plurality of groove portions that are continuous in the circumferential direction of the shape roll are arranged in parallel in the rotation axis direction of the shape roll, and the plurality of groove portions are arranged at equal intervals.

  Moreover, it is preferable that a plurality of groove portions that are continuous in the circumferential direction of the shape roll are arranged in parallel in the rotation axis direction of the shape roll, and the depth H of the plurality of groove portions is 100 μm to 500 μm.

  In addition, the transfer mold has a plurality of groove portions that are continuous in the circumferential direction of the shape roll in parallel with the rotation axis direction of the shape roll, and an aspect ratio H that is a ratio of the groove portion depth H to the arrangement interval P of the plurality of groove portions. / P is preferably 0.3 or more.

  In addition, the transfer mold has a plurality of grooves continuous in the circumferential direction of the shape roll in parallel with the rotational axis direction of the shape roll, and the cross-sectional shape in the direction perpendicular to the circumferential direction of the shape roll of the groove is substantially semicircular. It is preferable that the shape is substantially semi-elliptical or prismatic.

  The transfer mold has a plurality of grooves continuous in the circumferential direction of the shape roll in the rotational axis direction of the shape roll, and the cross-sectional shape in the direction perpendicular to the circumferential direction of the shape roll of the groove forms an optical lens. It is preferable that the shape be a corresponding shape.

  In the transfer mold, a plurality of groove portions continuous in the circumferential direction of the shape roll are arranged in parallel in the direction of the rotation axis of the shape roll, the arrangement interval P of the plurality of groove portions is equal to 200 μm to 500 μm, and the depth H of the groove portion is 100 μm. ˜500 μm, aspect ratio (H / P) is 0.3 or more, and the cross-sectional shape in a direction perpendicular to the circumferential direction of the shape roll of the groove portion is a substantially semicircular shape, a substantially semielliptical shape, or a prism shape. In the case of a corresponding shape for forming an optical lens, it has been difficult to produce a surface shape transfer resin sheet having a high transfer rate by the conventional manufacturing method. When the method for producing a resin sheet according to the present invention is used, a surface shape transfer resin sheet having a high transfer rate can be produced even in a transfer mold having a high transfer difficulty as described above.

  The resin (a) constituting the shape transfer layer (A) is a styrene resin or an acrylic resin, and the resin (b) constituting the main layer (B) is a styrene resin or an acrylic resin. It is preferable.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the resin sheet which can aim at the improvement of the transfer rate of the shape transcribe | transferred to the resin sheet can be provided.

It is a schematic block diagram which shows the resin sheet manufacturing apparatus which concerns on embodiment of this invention. It is a schematic block diagram which shows the resin sheet manufacturing apparatus which concerns on 2nd Embodiment of this invention. It is a schematic block diagram which shows the resin sheet manufacturing apparatus which concerns on 3rd Embodiment of this invention. It is a schematic block diagram which shows the resin sheet manufacturing apparatus which concerns on 4th Embodiment of this invention. It is a schematic block diagram which shows the resin sheet manufacturing apparatus which concerns on 5th Embodiment of this invention. It is sectional drawing which shows typically the layer structure of the resin sheet which concerns on embodiment of this invention. It is a perspective view which shows typically the structure of the resin sheet which concerns on embodiment of this invention. It is sectional drawing which shows typically the recessed part formed in the transcription | transfer mold, and the convex-shaped part formed in the resin sheet. It is a flowchart which shows the procedure of the manufacturing method of the resin sheet which concerns on embodiment of this invention. It is sectional drawing which shows typically the layer structure of the resin sheet which concerns on other embodiment of this invention. It is sectional drawing which shows typically the structure of one Embodiment of the transmissive image display apparatus provided with the light-guide plate which concerns on this invention. It is a rear view which shows typically the structure of one Embodiment of the surface light source device provided with the light-guide plate which concerns on this invention. It is a rear view which shows typically the structure of other embodiment of the surface light source device provided with the light-guide plate which concerns on this invention. It is a front view which shows typically the structure of one Embodiment of the surface light source device provided with the light-guide plate which concerns on this invention. It is a perspective view which shows typically the structure of other embodiment of the light-guide plate which concerns on this invention. It is a side view which shows typically the structure of one Embodiment of the transmissive | pervious image display apparatus provided with the light diffusing plate which concerns on this invention. FIG. 17 is a schematic perspective view of the transmissive image display device shown in FIG. 16. It is a typical perspective view of the light diffusing plate which consists of a resin sheet which concerns on one Embodiment of this invention. It is a principal part expanded sectional view of the lamp box which shows the attachment state of a light diffusing plate. It is a schematic block diagram which shows the resin sheet manufacturing apparatus which concerns on 6th Embodiment of this invention. It is a principal part expanded sectional view of the intaglio transfer type | mold attached to the 2nd press roll (shape roll). It is a figure which shows the 1st modification (substantially semicircle shape) of an intaglio transfer type | mold. It is a figure which shows the 2nd modification (substantially prism shape) of an intaglio transfer type | mold.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, the same code | symbol is attached | subjected to the same or an equivalent element, and the overlapping description is abbreviate | omitted. The dimensional ratios in the drawings do not necessarily match those described.

(Resin sheet manufacturing equipment)
FIG. 1 is a schematic configuration diagram illustrating a resin sheet manufacturing apparatus according to an embodiment of the present invention. The resin sheet manufacturing apparatus 50 is an apparatus that can be used in the resin sheet manufacturing method of the present invention. The resin sheet manufacturing apparatus 50 includes a die 51 that continuously extrudes a heated and melted resin to obtain a continuous resin sheet 60, and a first pressing roll that presses the continuous resin sheet 60 extruded from the die 51 from both sides in the thickness direction. (Pressing roll in the present invention) 52A and a second pressing roll (shape roll in the present invention) 52B.

  The resin sheet manufacturing apparatus 50 includes a resin charging port 57 for charging a resin as a raw material and an extruder 58 for pressing the resin charged from the resin charging port 57. The resin sheet manufacturing apparatus 50 according to the present embodiment is configured to be able to manufacture a multi-layered resin sheet 60 laminated in the thickness direction, and in this embodiment, a continuous resin having a two-layer structure as shown in FIG. A case where the sheet 60 is manufactured will be described.

  52 A of 1st press rolls and the 2nd press roll 52B are set as the structure which can rotate around the mutually parallel rotation axis. 52 A of 1st press rolls and the 2nd press roll 52B are spaced apart and arrange | positioned in the thickness direction of the resin sheet 60, and the space | interval of mutual peripheral surfaces is set according to the thickness of the resin sheet 60. FIG. As shown in FIGS. 8, 21, 22, and 23, a transfer mold 53 corresponding to the concavo-convex shape transferred to the resin sheet 60 is formed on the peripheral surface of the second pressing roll 52B. Details will be described later.

(Modification of resin sheet manufacturing equipment)
FIG. 2 is a schematic configuration diagram showing a resin sheet manufacturing apparatus according to the second embodiment of the present invention. The resin sheet manufacturing apparatus 50B shown in FIG. 2 is different from the resin sheet manufacturing apparatus 50 shown in FIG. 1 in that a third pressing roll 52C is provided downstream of the second pressing roll (shape roll in the present invention) 52B. Is a point. The third pressing roll 52C has the same configuration as the first pressing roll (pressing roll in the present invention) 52A. The third pressing roll 52C sandwiches and presses the continuous resin sheet 60 between the second pressing roll 52B.

  FIG. 3 is a schematic configuration diagram showing a resin sheet manufacturing apparatus according to the third embodiment of the present invention. The difference between the resin sheet manufacturing apparatus 50C shown in FIG. 3 and the resin sheet manufacturing apparatus 50 shown in FIG. 1 is that a preloading roll 52D is provided upstream of the first pressing roll (pressing roll in the present invention) 52A. is there. The preload roll 52D has the same configuration as the first pressing roll 52A. The preload roll 52D sandwiches and presses the continuous resin sheet 60 between the first press roll 52A.

  FIG. 4 is a schematic configuration diagram showing a resin sheet manufacturing apparatus according to the fourth embodiment of the present invention. The resin sheet manufacturing apparatus 50D shown in FIG. 4 is different from the resin sheet manufacturing apparatus 50B shown in FIG. 2 in that a fourth pressing roll (rear pressing roll) 52E is provided after the third pressing roll 52C. The other structure is the same as that of the resin sheet manufacturing apparatus 50B shown in FIG. The fourth pressing roll 52E sandwiches and presses the continuous resin sheet 60 between the third pressing roll 52C. The continuous resin sheet 60 is conveyed while the shape transfer layer 61 is in close contact with the fourth pressing roll 52E.

  FIG. 5 is a schematic configuration diagram showing a resin sheet manufacturing apparatus according to the fifth embodiment of the present invention. The resin sheet manufacturing apparatus 50E shown in FIG. 5 is different from the resin sheet manufacturing apparatus 50C shown in FIG. 3 in that a third pressing roll (rear pressing roll) 52C is provided after the second pressing roll (shape roll in the present invention) 52B. It is a point that has. Other configurations are the same as those of the resin sheet manufacturing apparatus 50C shown in FIG. The third pressing roll 52C sandwiches and presses the continuous resin sheet 60 between the second pressing roll 52B. The continuous resin sheet 60 is conveyed while the non-shape transfer layer is in close contact with the third pressing roll 52C.

  The plurality of rolls may be arranged adjacent to each other in the vertical direction as shown in FIGS. 1 to 3, or arranged adjacent to each other in the horizontal direction as shown in FIGS. 4 and 5. But you can. Moreover, the structure arrange | positioned adjacent to the direction which inclines with respect to a horizontal direction may be sufficient as a some roll. In the resin sheet manufacturing apparatus 50E shown in FIG. 5, since the third pressing roll 52C is disposed after the second pressing roll (the shape roll in the present invention) arranged third, the second pressing roll 52B The resin can be in close contact with the upper half (for 180 degrees). Moreover, the temperature of a continuous resin sheet can be adjusted by sticking a continuous resin sheet to the 3rd press roll 52C.

  FIG. 20 is a schematic configuration diagram showing a resin sheet manufacturing apparatus according to the sixth embodiment of the present invention. The resin sheet manufacturing apparatus 50F shown in FIG. 20 is different from the resin sheet manufacturing apparatus 50C shown in FIG. 3 in that the continuous resin sheet 60 immediately before being sandwiched between the first pressing roll 52A and the second pressing roll 52B. The heater 59 for heating the sheet surface on the shape transfer layer 61 side of the sheet 60 is provided.

  The resin sheet manufacturing apparatus 50D includes a sheet molding machine 54 that extrudes the raw material resin into a sheet shape and a set of pressing roll groups (52D, 52A, 52B) for molding the extruded continuous resin sheet 60 by pressing. And a pair of take-up roll groups (52G, 52H) for taking up the continuous resin sheet 60.

  The sheet molding machine 54 includes a first extruder (sub-extruder) 58A for heating and melting the raw resin (a) of the shape transfer layer (A) 61, and a raw resin (b) of the main layer (B) 62. A second extruder (main extruder) 58B for heating and melting, a feed block 55 to which the resin melted by the first and second extruders 58A and 58B is supplied, and the resin in the feed block 55 in a sheet state And a die 51 for extruding.

  As 1st and 2nd extruder 58A, 58B, well-known extrusion molding machines, such as a single screw extruder and a twin screw extruder, can be used, for example. The first and second extruders 58A and 58B are provided with a hopper (resin charging port) 57 for charging the resin into the cylinder of the extruder.

  The feed block 55 is not particularly limited as long as it is a type that can supply two or more kinds of resins to the die 51 and can be co-extruded in a laminated state. For example, a two-type three-layer distribution type, a two-type two-layer distribution type, etc. A known feed block can be used.

  The die 60 is not particularly limited as long as it is a co-extrusion die, and a metal T-die used in a normal extrusion molding method or the like is used. The width of the lip (die lip 60a) of the die 60 is selected according to the width of the intended continuous resin sheet 60, and is, for example, 300 mm to 3000 mm.

  The preloading roll 52D, the first pressing roll 52A, and the second pressing roll 52B are each made of a cylindrical metal (for example, stainless steel, steel, etc.) roll, and adjust the temperature (surface temperature) of the peripheral surface thereof. This is a cooling roll having a function of An intaglio transfer mold 53 for forming a semi-elliptical convex portion 35 and a concave groove 35b (see FIGS. 18 and 19) on the continuous resin sheet 60 is provided on the peripheral surface of the second pressing roll 52B.

  In the intaglio transfer mold 53, as shown in FIG. 21, a plurality of semi-elliptical concave grooves 70 as grooves opposite to the semi-elliptical convex parts 35 are formed in a plurality of streaks along the circumferential direction of the second pressing roll 52B. Is formed. That is, in the intaglio transfer mold 53, the semi-elliptical concave grooves 70 and the ridges 71 between the adjacent semi-elliptical concave grooves 70 are alternately arranged along the axial direction of the second pressing roll 52B. .

  The semi-elliptical concave groove 70 has a substantially semi-elliptical outline in a cut surface perpendicular to the longitudinal direction (circumferential direction). The depth H of the semi-elliptical concave groove 70 is slightly larger than the height H ′ of the semi-elliptical convex portion 35, and is, for example, 100 μm to 500 μm, preferably 100 μm to 300 μm or less. If the depth H is excessively large, it becomes difficult to allow the high-fluidity polystyrene resin (resin (b) constituting the shape transfer layer 61) to enter the tip of the semi-elliptical concave groove 70.

  Moreover, although the distance (pitch P) between the centers of the adjacent semi-elliptical concave grooves 70 is appropriately determined according to the shape of the semi-elliptical convex part 35, for example, 200 μm to 500 μm, preferably 250 μm to 450 μm, Preferably, it is 300 micrometers-400 micrometers. When the pitch P is less than 200 μm, the resin may solidify immediately upon contact with the second pressing roll 53, and as a result, the resin (a) constituting the shape transfer layer (A) 61 is a semi-elliptical concave groove 70. There is a possibility that the target transfer shape cannot be obtained without entering the tip of the sheet. On the other hand, when the pitch P exceeds 500 μm, the pitch streak may be observed with the naked eye even on the liquid crystal panel, or a moire pattern with the liquid crystal panel 10 or the optical film 41 may appear.

  Moreover, the aspect ratio represented by the ratio (H / P) of the height H with respect to the pitch P of the semi-elliptical concave groove 70 is 0.3 or more, for example, Preferably, it is 0.5-0.7. The difference between the height H ′ of the semi-elliptical convex portion 35 and the depth H of the semi-elliptical concave groove 70 is that the intaglio transfer mold 53 is transferred to the continuous resin sheet 60 to form the semi-elliptical convex portion 35. This is due to the transfer rate (H ′ / H) (%).

  Further, motors (not shown) are connected to the rotation shafts of the pressing rolls (52D, 52A, 52B), respectively. The preload roll 52D and the second pressing roll 52B can rotate counterclockwise, and the first pressing roll 52A can rotate clockwise. That is, the pressing rolls (52D, 52A, 52B) are “rotatable counterclockwise”, “rotatable clockwise”, and “rotatable counterclockwise” in order from the top. Thereby, all the rolls (52D, 52A, 52B) can rotate synchronously with the continuous resin sheet 60 sandwiched therebetween. Moreover, the conveyance speed of the resin sheet 60 can be adjusted by appropriately adjusting the rotation speed of the pressing rolls (52D, 52A, 52B).

  The diameter of each pressing roll (52D, 52A, 52B) is, for example, 100 mm to 500 mm. Further, when a metal roll is used as the pressing roll (52D, 52A, 52B), the surface thereof may be subjected to plating treatment such as chromium plating, copper plating, nickel plating, Ni-P plating, for example. .

  Further, a heater 72 for heating the surface of the shape transfer layer 61 (the surface on the transfer side) of the resin sheet 60 conveyed on the first pressing roll 52A is installed near the first pressing roll 52A. ing. The heater 72 is disposed so as to be separated from the peripheral surface of the first pressing roll 52 </ b> A, and heats the conveyed continuous resin sheet 60 from the sheet surface side of the shape transfer layer 61. As the heater 72, for example, a known heater such as an infrared heater can be used. In addition, the heater 72 may be an in-line type installed in a line where the continuous resin sheet 60 is conveyed, or may be a handy type that an operator can hold and measure.

  The pair of take-up roll groups (52E, 52E) includes a pair of take-up rolls 52E, 52E that sandwich the continuous resin sheet 60 from both sides in the thickness direction. The take-up rolls 52E and 52E are each made of a cylindrical metal roll (for example, made of stainless steel or steel), and the upper end of the lower take-up roll 52E is the same as the lower end of the second pressing roll (shape roll) 52B. Opposite installation is done so that it may become a height position. Thereby, since the continuous resin sheet 60 sent out from the 2nd press roll 52B can be horizontally conveyed, supporting at the height immediately after sending out, conveyance resistance can be made small.

(Continuous resin sheet)
Next, the continuous resin sheet manufactured by the manufacturing method which concerns on embodiment of this invention is demonstrated. FIG. 10 is a cross-sectional view showing the layer structure of the continuous resin sheet according to the embodiment of the present invention. In FIG. 10, it is the cross section cut in the direction (y direction, z direction) orthogonal to the continuous direction (x direction) of a continuous resin sheet, and has shown the state before a surface shape is transcribe | transferred.

  The continuous resin sheet 60 has a multilayer structure in which a plurality of layers are laminated in the thickness direction (z direction) of the sheet, and includes a shape transfer layer (A) 61, a main layer (B) 62, and a sheet surface 60a. It has. For example, the surface shape is transferred to the shape transfer layer (A) 61 having the sheet surface 60a. The main layer (B) 62 is disposed adjacent to the back side of the shape transfer layer (A) 61 to which the shape is transferred in the thickness direction of the sheet.

  As shown in FIG. 10, the continuous resin sheet 60 may have a configuration of two types and two layers (shape transfer layer (A) / main layer (B)), or two types and three layers as shown in FIG. 6. (Shape transfer layer (A) / main layer (B) / back surface layer). In the continuous resin sheet 60 shown in FIG. 6, the shape transfer layer (A) 61 constituting the sheet surface 60a, the back layer 63 constituting the sheet surface 60b, and the shape transfer layer (A) 61 and the back layer 63 are provided. And a sandwiched main layer (B) 62. In the case of two types and three layers, the resin constituting the shape transfer layer 61 and the back layer 63 is the same resin.

  FIG. 7 is a perspective view schematically showing the configuration of the resin sheet according to the embodiment of the present invention. In FIG. 7, the resin sheet 30 formed by cutting the continuous resin sheet 60 into a predetermined size is shown. The resin sheet 30 can be used as the light guide plate 30 or the light diffusion plate 30C of the surface light source devices (backlights) 20 and 20B mounted on the transmission type image devices 1 and 1B (see FIGS. 11 and 16) described later. It is. As the surface light source devices (backlights) 20 and 20B, a light source such as an LED is disposed on the side surface 33 of the light guide plate 30 and used as an edge light type that emits light incident from the side surface 33 of the light guide plate 30 to the front side. Is possible. A light source may be disposed on the side surface 33 of the resin sheet and used as a light guide plate, or a light source may be disposed on the back surface 32 of the resin sheet and used as a light diffusion plate (details will be described later). To do).

  When the resin sheet is used as the light guide plate 30, the back surface 32 of the resin sheet is usually subjected to a reflection process for irregularly reflecting light incident from the side surface. As a printing method performed as reflection processing, ink jet printing may be performed in addition to silk printing. Or as a method of reflection processing, you may give a dot-shaped unevenness | corrugation by laser irradiation instead of printing.

  The surface 31 of the resin sheet 30 extends in the first direction (x-axis direction) and has a plurality of convex shapes arranged in parallel in a second direction (y-axis direction) orthogonal to the first direction. A portion 35 is formed. The concavo-convex shape having the convex portion 35 formed on the surface 31 is formed by a transfer process described later.

(Usage example of light guide plate)
Next, a specific usage example of the light guide plate will be described with reference to FIG. FIG. 11 is a cross-sectional view schematically showing a configuration of an embodiment of a transmissive image display device including the light guide plate according to the present invention. FIG. 11 shows the transmissive image display device 1 in an exploded manner.

(Transparent image display device)
The transmissive image display device 1 includes a transmissive image display unit 10 and a surface light source device 20 disposed on the back side of the transmissive image display unit 10 in FIG. As shown in FIG. 11, the arrangement direction of the surface light source device 20 and the transmissive image display unit 10 is referred to as the z direction (plate thickness direction), and the two directions orthogonal to the z direction and perpendicular to each other are the x direction. And the y direction.

  Examples of the transmissive image display unit 10 include a liquid crystal display panel in which linearly polarizing plates 12 and 12 are disposed on both surfaces of a liquid crystal cell 11. In this case, the transmissive image display device 1 is a liquid crystal display device (or a liquid crystal television). As the liquid crystal cell 11 and the polarizing plates 12 and 12, those used in the transmissive image display device 1 such as a conventional liquid crystal display device can be used. Examples of the liquid crystal cell 11 include known liquid crystal cells such as TFT type and STN type.

(Surface light source device)
FIG. 12 is a rear view schematically showing a configuration of an embodiment of a surface light source device including the light guide plate according to the present invention, and FIG. 13 is another embodiment of the surface light source device including the light guide plate according to the present invention. The rear view which shows typically the structure of a form, FIG. 14 is a front view which shows typically the structure of one Embodiment of the surface light source device provided with the light-guide plate based on this invention. As shown in FIGS. 11 to 14, the surface light source device 20 includes a light guide plate (optical sheet) 30 and an LED light source (point light source) 22 arranged to face the side surface 33 of the light guide plate 30. Yes. In addition, the structure by which the various films 41 are arrange | positioned between the light guide plate 30 and the transmissive image display part 10 in the front side of the light guide plate 30 may be sufficient. Examples of the various films 41 include a diffusion film, a prism film, and a brightness enhancement film.

(light source)
The LED light source 22 functions as a point light source of the surface light source device 20, and is disposed to face the side surfaces 33, 33 extending in the y-axis direction of the light guide plate 30, as shown in FIG. . The plurality of LED light sources 22 are discretely arranged along the longitudinal direction (y-axis direction) of the side surface 33. The arrangement interval of the LED light sources 22 is usually 5 mm to 20 mm. The point light sources may be arranged so as to face the four sides of the light guide plate 30, and are arranged on two sides facing the x-axis direction (see FIG. 12) and two sides facing the y-axis direction. Alternatively, it may be configured to be arranged on only one side (see FIGS. 13 and 14). Further, the point light source is not limited to the LED light source, but may be other point light sources. Furthermore, the light source is not limited to a point light source, and a configuration in which a linear light source (cold cathode tube) is arranged may be used.

  The LED light source 22 may be a white LED, and a plurality of LEDs may be arranged in one place to constitute one light source unit. For example, as one light source unit, LEDs of three colors different in red, green, and blue may be arranged close to each other. And the light source unit which has several LED is discretely arrange | positioned according to the arrangement | positioning direction mentioned above. In such a case, it is preferable that different LEDs are arranged as close as possible.

  As the LED light source, those having various light emission distributions can be used, but the luminous intensity in the normal direction (z-axis direction) of the LED light source is maximum, and the half-value width of the luminous intensity distribution is 40 degrees or more and 80 or less. What has a light emission distribution is suitable. Specific examples of the LED light source type include a Lambertian type, a shell type, and a side emission type.

(Light guide plate)
As shown in FIGS. 12 to 14, the light guide plate 30 has a rectangular shape, and the size of the plan view shape is selected so as to match the screen size of the target transmissive image display device 10, but is orthogonal. The length of the two sides (L1 × L2) is usually a large size of 250 mm × 440 mm or more, preferably 500 mm × 800 mm or more. The planar view shape of the light guide plate 30 is not limited to a rectangle, but may be a square, but in the following, it will be described as a rectangle unless otherwise specified.

  The light guide plate 30 is formed of a translucent resin that transmits light and has a plate shape. The light guide plate 30 may be a sheet or a film. The thickness T of the light guide plate 30 is preferably 1.0 mm or greater and 4.5 mm or less.

  The light guide plate 30 includes a pair of main surfaces (31, 32) facing in the z-axis direction (thickness direction), a pair of side surfaces 33, 33 facing in the X-axis direction, and a pair of side surfaces 34 facing in the Y-axis direction. 34 is provided. The main surfaces (31, 32) are formed in a direction intersecting with the side surfaces (33, 34).

  One main surface (31) of the pair of main surfaces facing each other in the z-axis direction functions as an emission surface 31 capable of emitting planar light. The emission surface 31 is disposed on the transmissive image display unit 10 side, and the other main surface (back surface 32) is disposed on the opposite side to the transmissive image display unit 10. In addition, a reflection sheet 42 that reflects light in the light guide plate 30 toward the emission surface 31 is provided at a position facing the back surface 32.

(Reflection processing)
As shown in FIGS. 12 and 13, the back surface 32 of the light guide plate 30 is subjected to reflection processing (for example, silk printing) for irregularly reflecting light. As a printing method performed as reflection processing, ink jet printing may be performed in addition to silk printing. Or as a method of reflection processing, you may give a dot-shaped unevenness | corrugation by laser irradiation instead of printing. In the light guide plate 30 of the present embodiment, a dot pattern is printed as reflection processing. In printing dot patterns, ink having diffusing particles that diffuse light is used. Further, the gradation of each dot 38 (printing dot) constituting the dot pattern is changed so as to increase as the distance from the light source side increases. For example, the dot diameter of the region near the side that is the region near the light source is about 516 μm, and the dot diameter of the region near the center of the panel that is the farthest from the light source is about 904 μm. The dot diameter is about 729 μm.

(Uneven shape)
FIG. 7 is a perspective view schematically showing the configuration of one embodiment of the light guide plate according to the present invention, and FIG. 15 is a perspective view schematically showing the configuration of another embodiment of the light guide plate according to the present invention. . A plurality of convex portions 35 that are convex outward in the z-axis direction are formed on the emission surface 31. The convex portions 35 extend in the x-axis direction (one direction) and are arranged in parallel in the y-axis direction.

  In addition, examples of the shape of the convex portion 35 include a prism shape, a substantially semicircular shape, and a substantially semielliptical shape, and a shape that continuously changes in one convex portion 35 (shape unit) is preferable. For example, a semicircular shape or a semi-elliptical shape is preferable to a prism shape. In addition, it is preferable that the direction where the convex-shaped part 35 is extended is parallel to the emission direction of the light from a light source. Further, in the direction in which the convex portions 35 are adjacent (y-axis direction), a plane portion may be formed between the adjacent convex portions 35 and 35. In addition, the shape of the convex portion may be an optical lens shape.

  FIG. 8 is an enlarged view showing the convex portion in FIG. 7 from the x-axis direction. Here, the convex portion 35 may satisfy H × T / P ≧ 0.23 (1). However, P is the space | interval (micrometer) of the adjacent convex-shaped parts 35 and 35, H is the height (micrometer) of the convex-shaped part 35, and T is sheet | seat thickness (mm). As shown in FIG. 8, the interval P is a distance between the vertices 35 a and 35 a of the adjacent convex portions 35. The height H of the convex portion 35 is the distance between the lower end 35b of the convex portion 35 and the vertex 35a. The sheet thickness T is the distance between the apex 35 a of the convex portion 35 and the back surface 32.

(Construction material of light guide plate)
The light guide plate 30 is made of a translucent resin. The refractive index of the translucent resin is usually 1.49 to 1.59. As the translucent resin used for the light guide plate 30, methacrylic resin is mainly used. As the translucent resin used for the light guide plate 30, other resins may be used, or a styrene resin may be used. As the translucent resin, acrylic resin, styrene resin, carbonate resin, cyclic olefin resin, MS resin (acrylic and styrene copolymer), and the like can be used.

  In applying the light guide plate to the liquid crystal display device (transmission type image display device 1), the light guide plate 30 is added with additives such as a light diffusing agent, an ultraviolet absorber, a heat stabilizer, and a photopolymerization stabilizer. Also good.

(Usage example of light diffuser)
Next, a usage example of the light diffusing plate will be described with reference to FIG. FIG. 16 is a side view schematically showing a configuration of an embodiment of a transmissive image display device including the light diffusing plate according to the present invention. FIG. 17 is a schematic perspective view of the transmissive image display apparatus shown in FIG.

(Transparent image display device)
The transmissive image display device 1B includes the transmissive image display unit 10 and a surface light source device 20B disposed on the back side of the transmissive image display unit 10 in FIG. As shown in FIG. 16, the arrangement direction of the surface light source device 20 </ b> B and the transmissive image display unit 10 is referred to as the z direction (plate thickness direction), and the two directions orthogonal to the z direction and perpendicular to each other are the x direction. And the y direction.

  Examples of the transmissive image display unit 10 include a liquid crystal display panel in which linearly polarizing plates 12 and 12 are disposed on both surfaces of a liquid crystal cell 11. In this case, the transmissive image display device 1 is a liquid crystal display device (or a liquid crystal television). As the liquid crystal cell 11 and the polarizing plates 12 and 12, those used in the transmissive image display device 1 such as a conventional liquid crystal display device can be used. Examples of the liquid crystal cell 11 include known liquid crystal cells such as TFT type and STN type.

(Surface light source device)
The surface light source device 20 </ b> B includes a light guide plate (optical sheet) 30 and an LED light source (point light source) 22 disposed to face the side surface 33 of the light guide plate 30. Note that, on the front side of the light guide plate 30, various films (optical films) 41 may be arranged between the light guide plate 30 and the transmissive image display unit 10. The various films 41 are not particularly limited, and examples thereof include a microlens film, a substantially semicircular lenticular lens film, a diffusion film, a prism film, a brightness enhancement film, and a reflective polarization separation film.

  The surface light source device (backlight system) 20B includes a square plate-like rear wall 23 and a square frame-like side wall 24 integrally standing from the periphery of the rear wall 23 to the front (front side). An open thin box-shaped resin lamp box 25, a plurality of linear light sources 22B provided in the lamp box 25, and a light diffusing plate 30C that closes an open surface 26 (front surface) of the lamp box 25 are provided. Yes.

  That is, the box-shaped lamp box 25 has an open surface 26 whose outline is defined by a rectangular frame-shaped side wall 24, and a linear light source 22B is provided in a space surrounded by the side wall 24 and the rear wall 23. On the inner surface of the rear wall 23 of the lamp box 25, for example, a reflection plate 42 (see FIG. 11) for reflecting light incident on the rear wall 23 side from the linear light source 22B to the open surface 26 side of the box is entirely present. It is attached.

(light source)
The linear light source 22B is, for example, a cylindrical lamp having a diameter of 2 mm to 4 mm. The plurality of linear light sources 22B are arranged at equal intervals in parallel with each other in a state of being spaced apart from the back surface 32 of the light diffusion plate 22B.

  The interval Q between the centers of the adjacent linear light sources 22B is preferably 30 mm to 60 mm from the viewpoint of power saving. Moreover, it is preferable that the distance R between the back surface 32 (for example, the center part in the back surface 32) of the light diffusing plate 30C and the center of the linear light source 22B is 10 mm to 20 mm from the viewpoint of thinning. Further, the ratio of the distance Q to the distance R (Q / R) is preferably 2.5 to 4.0. In particular, the interval Q is preferably 40 mm to 55 mm, and the distance R is preferably 13 mm to 17 mm. The number of linear light sources 22B is inevitably determined by the size of the lamp box 25 (screen size of the transmissive image display device 1B) and the interval Q. For example, in the case of the 32 type liquid crystal display device 1, 6-10. A book is preferred. In FIG. 17 and FIG. 18, only five linear light sources 22B are shown for easy illustration.

  Further, as the linear light source 22B, for example, a known cylindrical lamp such as a fluorescent tube (cold cathode tube), a halogen lamp, or a tungsten lamp can be used. Further, as the light source of the surface light source device 20B, a point light source such as a light emitting diode (LED) can be used instead of the linear light source 22B.

(Light diffusion plate)
FIG. 18 is a schematic perspective view of a light diffusing plate made of a resin sheet according to an embodiment of the present invention. FIG. 19 is an enlarged cross-sectional view of a main part of the lamp box showing a mounted state of the light diffusing plate. As shown in FIG. 18, the light diffusion plate 30 </ b> C is formed in a square plate shape that is substantially the same as the frame shape of the side wall 24 of the lamp box 25.

  The light diffusing plate 30C is a light-transmitting multilayer light diffusing plate in which at least two resin layers are laminated in the thickness direction Z, and includes a shape transfer layer (A) (front layer) 61 made of a highly fluid resin. And a main layer (B) (back layer) 62 made of a low fluidity resin.

  The light diffusion plate 30C can contain a light diffusing agent (light diffusing particles) as necessary. The light diffusing agent is not particularly limited as long as it has a refractive index different from that of the translucent resin constituting the light diffusing plate 30C and can diffuse transmitted light. For example, as an inorganic light diffusing agent, calcium carbonate, Examples thereof include barium sulfate, titanium oxide, aluminum hydroxide, silica, glass, talc, mica, white carbon, magnesium oxide, and zinc oxide. These may be subjected to a surface treatment with a fatty acid or the like.

  Examples of the organic light diffusing agent include styrene polymer particles, acrylic polymer particles, and siloxane polymer particles. Preferably, the weight average molecular weight is 500,000 to 5,000,000. Examples include coalescent particles and crosslinked polymer particles having a gel fraction of 10% by mass or more when dissolved in acetone. The light diffusing agents can be used alone or in combination of two or more.

  When the light diffusing plate 30C contains a light diffusing agent, the blending ratio of the light diffusing agent is 0.001 to 1 part by weight, preferably 0.001 to 0.01 with respect to 100 parts by weight of the translucent resin. Parts by weight. Moreover, a light-diffusion agent can be used as a masterbatch with the said translucent resin. Further, the absolute value of the difference between the refractive index of the translucent resin and the refractive index of the light diffusing agent is usually 0.01 to 0.20, preferably 0.02 to 0.02 from the viewpoint of light diffusibility. 0.15.

  In addition, various additives such as ultraviolet absorbers, heat stabilizers, antioxidants, weathering agents, light stabilizers, optical brighteners, and processing stabilizers may be added to the light diffusion plate 10 as necessary. You can also.

  The ultraviolet absorber is not particularly limited, and examples thereof include salicylic acid phenyl ester ultraviolet absorbers, benzophenone ultraviolet absorbers, triazine ultraviolet absorbers, and benzotriazole ultraviolet absorbers. When adding an ultraviolet absorber, it is preferable to add 0.1-3 weight part of ultraviolet absorbers with respect to 100 weight part of translucent resin. If it is the above-mentioned range, the bleeding to the surface of an ultraviolet absorber can be suppressed and the external appearance of a light diffusing plate can be maintained favorable.

  The heat stabilizer is not particularly limited, and examples thereof include manganese compounds and copper compounds. When adding the heat stabilizer, it is preferably added together with the ultraviolet absorber, and the heat stabilizer is preferably added at a ratio of 2 parts by weight or less with respect to 1 part by weight of the ultraviolet absorber in the translucent resin. More preferably, 0.01 to 1 part by weight of a heat stabilizer is added to 1 part by weight of the ultraviolet absorber in the translucent resin.

  Moreover, it does not restrict | limit especially as antioxidant, For example, a hindered phenol compound, a hindered amine compound, etc. are mentioned. When adding antioxidant, it is preferable to add 0.1-3 weight part of antioxidant with respect to 100 weight part of translucent resin.

  Then, as shown in FIG. 19, the light diffusing plate 30C transmits light to the side wall 24 of the lamp box 25 at a position where the semi-elliptical convex portion 35 is parallel to the linear light source 22B in the lamp box 25. The back surface 32 of the diffusing plate 30 </ b> C is brought into contact with and fixed to the lamp box 25. Thereby, the open surface 26 of the lamp box 25 is blocked by the light diffusion plate 30C.

(Constituent material of resin sheet)
The light guide plate or light diffusing plate made of a resin sheet is made of a translucent resin. The refractive index of the translucent resin is usually 1.49 to 1.59. As the translucent resin used for the light guide plate 30, methacrylic resin is mainly used. As the translucent resin used for the light guide plate 30, other resins may be used, or a styrene resin may be used. As the translucent resin, an acrylic resin, a styrene resin, a carbonate resin, a cyclic olefin resin, an MS resin (a copolymer of acrylic and styrene), or the like can be used.

  A resin sheet 60 shown in FIG. 10 includes a shape transfer layer (A) 61 and a main layer (B) 62, and a shape transfer layer for the MFR (b) of the resin (b) constituting the main layer (B). The ratio (MFR (a) / MFR (b)) of MFR (a) of the resin (a) constituting (A) is 1.5 or more. MFR (a) and MFR (b) are measurement values measured at a temperature of 200 ° C. and a load of 49 N in accordance with JISK7210 (MFR: Melt flow rate).

  As the resin (a) constituting the shape transfer layer (A), there is usually a thermoplastic resin that becomes a molten state when heated. The resin (a) is preferably a styrene resin or an acrylic resin. The resin (a) may be other resins, and may be a carbonate resin, a cyclic olefin resin, an MS resin (a copolymer of acrylic and styrene), or the like. In addition, the thermosetting resin which hardens | cures by heating in the range applicable to the manufacturing method of this invention may be sufficient. Additives such as a light diffusing agent, an ultraviolet absorber, a heat stabilizer, and an antistatic agent may be added to the resin.

  As the resin (b) constituting the main layer (B), there is usually a thermoplastic resin that becomes a molten state when heated. The resin (b) is preferably a styrene resin or an acrylic resin. The resin (b) may be other resins, such as carbonate resin, cyclic olefin resin, MS resin (a copolymer of acrylic and styrene). In addition, the thermosetting resin which hardens | cures by heating in the range applicable to the manufacturing method of this invention may be sufficient. Additives such as a light diffusing agent, an ultraviolet absorber, a heat stabilizer, and an antistatic agent may be added to the resin.

(Example of MFR value)
When the resin (a) constituting the shape transfer layer (A) and the resin (b) constituting the main layer (B) are both styrene resins, the MFR (a) is 5 g / 10 min to 15 g / 10 min, MFR (b) can be set to 0.5 g / 10 min to 2.0 g / min.

  When the resin (a) constituting the shape transfer layer (A) and the resin (b) constituting the main layer (B) are both acrylic resins, the MFR (a) is 0.4 g / 10 min to 3.0 g / 10 min and MFR (b) can be 0.1 g / 10 min to 2.0 g / min.

(Production method of resin sheet)
The manufacturing method of the resin sheet which concerns on embodiment of this invention is demonstrated. FIG. 9 is a flowchart showing a procedure of a method for producing a resin sheet according to the embodiment of the present invention. The resin sheet manufacturing method of the present embodiment can be implemented using, for example, a resin sheet manufacturing apparatus 50 shown in FIGS. 1 to 5 and FIG. As shown in FIG. 9, the resin sheet manufacturing method of this embodiment includes sheet manufacturing (S1) in which a resin in a heated and melted state is continuously extruded from a die to form a continuous resin sheet, and a transfer mold is provided on the peripheral surface. A transfer step (S2) of transferring the transfer mold to the continuous resin sheet using the formed (shape roll).

(Sheet manufacturing process)
In the sheet manufacturing process, the resin is continuously extruded from the die 51 in a heated and melted state to manufacture the continuous resin sheet 60. Examples of the resin used in the production method of the present invention include thermoplastic resins that are in a molten state when heated.

  As the die 51 for continuously extruding the resin in a heated and melted state, a metal T-die that is the same as that used in a normal extrusion method is used. In order to extrude the resin from the die 51 in a heated and melted state, an extruder 58 is used as in a normal extrusion molding method. The extruder 58 may be a single screw extruder or a twin screw extruder. The resin is heated in the extruder 58, sent to the die 51 in a molten state, and extruded. The resin extruded from the die 51 is continuously extruded into a sheet shape to form a continuous resin sheet 60.

  Since the continuous resin sheet 60 has a multilayer structure, two or more kinds of resins are supplied to the die 51 and coextruded in a laminated state. In order to perform co-extrusion in a state where two or more kinds of resins are laminated, for example, a known two-type three-layer distribution type feed block is used, and the resin is supplied to the die 51 through this.

  In addition, what is necessary is just to adjust the thickness of the continuous resin sheet 60 suitably according to the use of the obtained sheet | seat. For example, when the continuous resin sheet 60 is used as the light guide plate 30 or the light diffusion plate 30C, a preferable range of the sheet thickness is 1.0 mm or more and 4.5 mm or less.

(Transfer process)
In the transfer step (S2), the transfer starts when the continuous resin sheet 60 manufactured in the sheet manufacturing step (S1) is pressed between the first pressing roll (pressing roll) 52A and the second pressing roll (shape roll) 52B. The continuous resin sheet 60 pressed in the step (S3) and the transfer start step (S3) is transported while being in close contact with the peripheral surface of the shape roll 52B, and is transported in the transport step (S4). And a peeling step (S5) for peeling the continuous resin sheet 60 from the peripheral surface (transfer mold 53) of the shape roll 52B.

(Transfer start process)
As shown in FIG. 1, the continuous resin sheet 60 obtained in the sheet manufacturing step (S1) is transferred in the thickness direction of the sheet by the first pressing roll 52A and the second pressing roll 52B as shown in FIG. Are simultaneously sandwiched and pressed from both sides.

  At this time, the surface temperature of the continuous resin sheet 60 immediately before coming into contact with the second pressing roll 52B is (Tg (a) when the glass transition temperature of the resin (a) constituting the shape transfer layer (A) is Tg (a). a) + 50 ° C.) to (Tg (a) + 150 ° C.). The surface temperature can be adjusted by changing the set temperature of the extruder 58 and changing the set temperature of the die 51. In addition, the surface temperature of the continuous resin sheet 60 can be measured using an infrared thermometer.

  Moreover, you may perform the heating process which heats the sheet | seat surface of the shape transfer layer 61 of the continuous resin sheet 60 currently closely_contact | adhered and conveyed to the surrounding surface of the 1st press roll 52A just before a transfer start process.

  In this transfer start step (S3), the shape of the transfer mold 53 formed on the surface of the second pressing roll (shape roll) 52B is transferred to the continuous resin sheet 60. In the present invention, the second pressing roll 52B provided with a transfer mold is also referred to as a transfer roll. The transfer mold provided on the surface of the transfer roll is pressed against the surface of the continuous resin sheet 60 and transferred to the continuous resin sheet 60 with the surface shape as the reverse mold.

  As the first and second pressing rolls 52A and 52B, metal rolls made of a metal such as stainless steel or steel are usually used, and the diameter is usually 100 mm to 500 mm. When metal rolls are used as the first and second pressing rolls 52A and 52B, the surface thereof may be subjected to plating treatment such as chromium plating, copper plating, nickel plating, nickel-phosphorous plating, or the like. Further, the surface (circumferential surface) of the first pressing roll 52A may be a mirror surface or may be a transfer surface provided with unevenness such as embossing.

(Conveying process)
The transporting step (S4) is a step of transporting the continuous resin sheet 60 according to the rotation of the second pressing roll 52B in a state where the continuous resin sheet 60 is in close contact with the peripheral surface of the second pressing roll 52B.

(Peeling process)
A peeling process (S5) is a process of peeling the continuous resin sheet 60 from the surrounding surface of the 2nd press roll 52B.

  At this time, the surface temperature of the resin (a) of the continuous resin sheet 60 immediately after being peeled from the second pressing roll 52B is equal to the glass transition temperature Tg (a) of the resin (a) constituting the shape transfer layer (A). On the other hand, it is suitable that it is in the range of (Tg (a) -10) ° C. to (Tg (a) +40) ° C. When the surface temperature of the resin (a) is lower than this range, the production efficiency cannot be increased. When the surface temperature of the resin (a) is higher than the above temperature range, the shape transferred to the continuous resin sheet 60 is restored to the original by heat, and the transfer rate is deteriorated. A more preferable range of the surface temperature of the resin (a) immediately after being peeled from the second pressing roll 52B is a range of (Tg (a) -5) ° C. to (Tg (a) +10) ° C.

  The glass transition temperature Tg (a) of the resin (a) constituting the surface layer (A) is (g) when the glass transition temperature of the resin (b) constituting the main layer (B) is Tg (b). The range may be Tg (b) +2) ° C. <Tg (a) ° C. <(Tg (b) +20) ° C.

  Moreover, after peeling from the 2nd press roll 52B, the ratio of the thickness of the shape transfer layer (A) with respect to the thickness of a main layer (B) is the range of 1/200 to 1/10. When the thickness ratio is smaller than 1/200, the transfer rate is not sufficiently improved when the thickness ratio is larger than 1/10.

(Transfer type)
FIG. 8 is a cross-sectional view schematically showing the concave portion formed in the transfer mold and the convex portion formed in the resin sheet. The transfer mold 53 includes a plurality of recesses provided on the surface of the shape roll 52B. For example, the recess is formed continuously in the circumferential direction of the shape roll 52B. The pitch of the recesses is usually 30 μm or more, preferably 50 μm or more. However, in the manufacturing method and manufacturing apparatus of the present invention, it is suitable when the pitch interval between the recesses is 200 μm to 500 μm, and the groove depth H of the recesses is Is 100 μm to 500 μm. The pitch interval (P) of the recesses refers to the distance between the groove portions (bottom portions) of the adjacent recesses, and the groove depth (D) of the recesses refers to the groove portion (bottom portion) of the recesses from the surface circumference of the shape roll 52B. ).

  The aspect ratio (H / P), which is the ratio of the groove depth (H) of the recesses to the pitch interval (P) of the recesses, is, for example, 0.3 or more, preferably 0.4 to 0.7.

  Further, examples of the cross-sectional shape of the concave portion of the transfer mold 53 include a semicircular shape and a semielliptical shape. Further, it may be a V shape having an acute angle portion corresponding to the prism shape.

  As a method for producing the transfer mold, the surface of the transfer roll made of stainless steel, steel, or the like is subjected to plating treatment such as chrome plating, copper plating, nickel plating, nickel-phosphorous plating, and then applied to the plated surface. The shape may be processed by performing removal processing using a diamond tool or a metal grindstone, laser processing, or chemical etching, but is not particularly limited to these methods.

  Further, the surface of the transfer roll may be subjected to plating treatment such as chromium plating, copper plating, nickel plating, nickel-phosphorous plating, etc. at a level that does not impair the accuracy of the surface shape after the transfer mold is formed.

  In order to more accurately and reproducibly form the groove shape of the transfer mold, a combination of a lathe and a diamond tool is preferable, and the thickness of the chromium plating applied on the copper is preferably 5 μm or less, more preferably 2 μm or less. .

(Modified example of resin sheet manufacturing method)
As a modification of the manufacturing method, for example, the second pressing step may be performed after the transporting step (S4). The second pressing step can be performed using a resin sheet manufacturing apparatus 50B shown in FIG. In the second pressing step, the continuous resin sheet 60 conveyed in the conveying step (S4) is pressed by being sandwiched between the second pressing roll (shape roll) 52B and the third pressing roll 52C. The continuous resin sheet 60 pressed in the second pressing step is peeled off from the second pressing roll (peeling step) and conveyed while being in close contact with the peripheral surface of the third pressing roll 52C, and then the circumference of the third pressing roll 52C. Peel from the surface.

  As another modification of the manufacturing method, for example, a pre-pressing step of pressing in advance may be performed before the transfer start step (S3). The preloading step can be performed using a resin sheet manufacturing apparatus 50C shown in FIG. In the preloading process, the continuous resin sheet 60 manufactured in the sheet manufacturing process (S1) is pressed in advance by being sandwiched between the preloading roll 52D and the first pressing roll 52A. The pressed continuous resin sheet 60 is conveyed in close contact with the peripheral surface of the first pressing roll 52A (preliminary conveying process), and the transfer start process (S3) is executed by the first and second pressing rolls 52A and 52B. It is effective to improve the transfer rate, and it is preferable to use this manufacturing method.

  Moreover, you may install the heater for heating the surface of the continuous resin sheet 60 conveyed on the 1st press roll 52A near the 1st press roll 52A. The heater is disposed opposite to the circumferential surface of the first pressing roll 52A and heats the continuous resin sheet conveyed from the front side. As the heater, for example, a known heater such as an infrared heater can be used.

(Function)
In the method for producing a resin sheet of the present invention, only the shape transfer layer has a relatively good flow, and the main layer has a relatively low fluidity, so that the surface layer portion of the resin (a) flows into the recess shape of the transfer mold. The shape of the resin that has flowed into the concave shape of the transfer mold 53 is easily held even after the transfer mold 53 is peeled off. Thereby, the shape transfer rate can be improved. Therefore, it becomes possible to form a surface shape with a high aspect ratio on the resin sheet.

(Example)
Examples Hereinafter, the present invention will be described in more detail with reference to Examples 1 to 4, but the present invention is not limited thereto.

(Example 1, Comparative Example 1)
The sheet | seat which concerns on Example 1 and Comparative Example 1 was created using the resin sheet manufacturing apparatus 50C shown in FIG. The conditions of the manufacturing apparatus 50 used are shown below. The screw diameter of the extruder 58 was 40 mm, and the amount of extrusion by the extruder 58 was 20 kg / hr. The line speed was 0.32 m / min, and the sheet width (length in the Y direction) was 25 cm. As the shape of the transfer mold of the second pressing roll 52B, the pitch P was 600 μm and the depth H was 300 μm. The roll temperature (preload roll 52D / first pressing roll 52A / second pressing roll 52B) was 80 ° C./80° C./80° C.

  In Example 1, a PMMA plate having a sheet thickness of 4 mm was formed by extrusion molding (sheet manufacturing process). In Example 1, a resin sheet having a three-layer structure (see FIG. 6) was prepared using two types of resins.

For the resin (a) constituting the surface layer (A), a copolymer of methyl methacrylate and methyl acrylate was used. The specification of resin (a) is shown below.
Weight ratio: methyl methacrylate / methyl acrylate = 98/2
MFR (a): 1.5 g / 10 min (200 ° C., 49 N load condition)
Glass transition temperature Tg (a): 107 ° C
Thickness (one side): 0.1mm
In addition, it was 9.4 g / 10min when MFR of resin (a) was measured on 230 degreeC and 37 N (3.8 kgf) load conditions.

A copolymer of methyl methacrylate and methyl acrylate was used for the resin (b) constituting the main layer (B). The specification of resin (b) is shown below.
Weight ratio: methyl methacrylate / methyl acrylate = 94/6
MFR (b): 0.24 g / 10 min (200 ° C., 49 N load condition)
Glass transition temperature Tg (b): 102 ° C.
Thickness: 3.8mm
In addition, it was 1.5 g / 10min when MFR of resin (b) was measured on 230 degreeC and 37 N (3.8 kgf) load conditions.

  The ratio of the thickness of the surface layer (A) and the main layer (B) is 1/38.

  In Comparative Example 1, a resin sheet having a single layer structure was prepared using the resin (b). Except that the three-layer structure is changed to a single-layer structure, it is the same as the above embodiment.

  In Example 1, the surface temperature of the resin sheet immediately after being peeled from the second pressing roll 52B is 105 ° C., and the shape height H ′ at this time is 183 μm, and the shape transfer rate (= H ′ / H) was 61%. In Comparative Example 1, the surface temperature of the resin sheet immediately after being peeled from the second pressing roll 52B is 105 ° C., and the shape height H ′ at this time is 168 μm, and the shape transfer rate (= H ′ / H) was 56%.

Table 1 below shows the test conditions and test results of Example 1 and Comparative Example 1. The case where the shape transfer rate was 60% or more was determined as acceptable.

(Examples 2 and 3, Comparative Example 2)
Sheets according to Examples 2 and 3 and Comparative Example 2 were prepared using a resin sheet manufacturing apparatus 50C illustrated in FIG. The conditions of the manufacturing apparatus 50C used are shown below. The screw diameter of the extruder 58 was 120 mm, and the amount of extrusion by the extruder 58 was 700 kg / hr. In Examples 2 and 3, the line speed was 2.85 m / min, and in Comparative Example 2, the line speed was 2.83 m / min. The sheet width (length in the Y direction) was 135 cm in both Examples 2 and 3 and Comparative Example 2. As the shape of the transfer mold of the second pressing roll 52B, the pitch P was 400 μm and the depth H was 222 μm. In Example 2, the roll temperature (preloading roll 52D / first pressing roll 52A / second pressing roll 52B) is 80 ° C./85° C./97° C., and in Example 3, it is 80 ° C./85° C./87° C. In Comparative Example 2, the temperature was set to 80 ° C./85° C./95° C.

  In Examples 2 and 3, a PMMA plate having a sheet thickness of 3 mm was formed by extrusion molding (sheet manufacturing process). In Examples 2 and 3, a resin sheet having a three-layer structure (see FIG. 6) was prepared using two types of resins.

A copolymer of methyl methacrylate and methyl acrylate was used for the resin (a-2) constituting the surface layer (A). The specification of resin (a-2) is shown below.
Weight ratio: methyl methacrylate / methyl acrylate = 95/5
MFR (a): 1.4 g / 10 min (200 ° C., 49 N load condition)
Glass transition temperature Tg (a): 102 ° C.
Thickness (one side): (Example 2) 0.2 mm: (Example 3) 0.2 mm
In addition, it was 10.0 g / 10min when MFR of resin (a-2) was measured on 230 degreeC and 37 N (3.8 kgf) load conditions.

A copolymer of methyl methacrylate and methyl acrylate was used for the resin (b) constituting the main layer (B). The specification of resin (b) is shown below.
Weight ratio: methyl methacrylate / methyl acrylate = 94/6
MFR (b): 0.24 g / 10 min (200 ° C., 49 N load condition)
Glass transition temperature Tg (b): 102 ° C.
Thickness: (Example 2) 2.6 mm: (Example 3) 2.6 mm
In addition, it was 1.5 g / 10min when MFR of resin (b) was measured on 230 degreeC and 37 N (3.8 kgf) load conditions.

  In Comparative Example 2, a resin sheet having a single layer structure was prepared using the resin (b).

  In Example 2, the surface temperature of the resin sheet immediately after being peeled from the second pressing roll 52B is 124 ° C., and the shape height H at this time is 155 μm, and the shape transfer rate (= H ′ / H ) Was 61%. In Example 3, the surface temperature of the resin sheet immediately after being peeled from the second pressing roll 52B is 119 ° C., and the shape height H at this time is 167 μm, and the shape transfer rate (= H ′ / H ) Was 75%. In Comparative Example 2, the surface temperature of the resin sheet immediately after being peeled from the second pressing roll 52B is 123 ° C., and the shape height H at this time is 127 μm, and the shape transfer rate (= H ′ / H ) Was 57%.

Table 2 below shows test conditions and test results of Examples 2 and 3 and Comparative Example 2. The case where the shape transfer rate was 60% or more was determined as acceptable.

(Example 4, Comparative Example 3)
The sheet | seat which concerns on Example 4 and Comparative Example 3 was created using the resin sheet manufacturing apparatus 50C shown in FIG. The conditions of the manufacturing apparatus 50C used are shown below. The screw diameter of the extruder 58 was 120 mm, and the amount of extrusion by the extruder 58 was 1000 kg / hr. In Example 4, the line speed was 4.08 m / min, and in Comparative Example 3, the line speed was 3.52 m / min. The sheet width (length in the Y direction) was 120 cm in Example 4 and 135 cm in Comparative Example 3. As the shape of the transfer mold of the second pressing roll 52B, the pitch P was 400 μm and the depth H was 222 μm. In Example 4, the roll temperature (preloading roll 52D / first pressing roll 52A / second pressing roll 52B) is 80 ° C./85° C./87° C., and in Comparative Example 3, 80 ° C./85° C./98° C. did.

  In Example 4, a PMMA plate having a sheet thickness of 3 mm was formed by extrusion molding (sheet manufacturing process). In Example 4, a resin sheet having a three-layer structure (see FIG. 6) was prepared using two types of resins.

A copolymer of methyl methacrylate and methyl acrylate was used for the resin (a-2) constituting the surface layer (A). The specification of resin (a-2) is shown below.
Weight ratio: methyl methacrylate / methyl acrylate = 95/5
MFR (a-2): 1.4 g / 10 min (200 ° C., 49 N load condition)
Glass transition temperature Tg (a): 102 ° C.
Thickness (one side): 0.15mm
In addition, it was 10.0 g / 10min when MFR of resin (a-2) was measured on 230 degreeC and 37 N (3.8 kgf) load conditions.

A copolymer of methyl methacrylate and methyl acrylate was used for the resin (b) constituting the main layer (B). The specification of resin (b) is shown below.
Weight ratio: methyl methacrylate / methyl acrylate = 94/6
MFR (b): 0.24 g / 10 min (200 ° C., 49 N load condition)
Glass transition temperature Tg (b): 102 ° C.
Thickness: 2.7mm
In addition, it was 1.5 g / 10min when MFR of resin (b) was measured on 230 degreeC and 37 N (3.8 kgf) load conditions.

  In Comparative Example 3, a resin sheet having a single layer structure was prepared using the resin (b).

  In Example 4, the surface temperature of the resin sheet immediately after peeling from the second pressing roll 52B is 135 ° C., and the shape height H at this time is 155 μm, and the shape transfer rate (= H ′ / H ) Was 70%. In Comparative Example 3, the surface temperature of the resin sheet immediately after being peeled from the second pressing roll 52B is 131 ° C., and the shape height H at this time is 127 μm, and the shape transfer rate (= H ′ / H ) Was 57%.

ライン速度（４．０８ｍ／ｍｉｎ）が速く、ロール温度（８７℃）が低い実施例４の方が、比較例３よりも高い形状転写率（７０％）となった。 Table 3 below shows test conditions and test results of Example 4 and Comparative Example 3. The case where the shape transfer rate was 60% or more was determined as acceptable.

In Example 4 where the line speed (4.08 m / min) was high and the roll temperature (87 ° C.) was low, the shape transfer rate (70%) was higher than in Comparative Example 3.

  Next, the present invention will be described based on Examples 5 and 6 and Comparative Example 4, but the present invention is not limited to the following examples.

(Raw material for resin sheet)
As raw materials for the resin sheet, the following materials (1) to (2) were prepared.
(1) Amorphous resin (main layer (B)): Low-flowing polystyrene resin (“HRM40” manufactured by Toyo Styrene Co., Ltd.)
MFR (b): 1.3 g / 10 min (200 ° C., 49 N load condition)
(2) Amorphous resin (shape transfer layer (A)): High fluidity polystyrene resin (“G490N” manufactured by Nippon Polystyrene Co., Ltd.)
MFR (a): 7.0 g / 10 min (200 ° C., 49 N load condition)

(Configuration of resin sheet manufacturing equipment)
The apparatus which has the structure similar to the resin sheet manufacturing apparatus shown in FIG. 20 was used.
In addition, the mirror surface cooling roll by which chromium plating was given to the surface was prepared as a press roll.
Further, a transfer mold A shown in Table 4 was prepared as a transfer mold to be attached to the pressing roll. In the transfer mold A, semi-elliptical groove portions are formed in parallel at equal intervals along the circumferential direction of the pressing roll. In Table 4, “Pitch P” and “Depth H” are values defined in the above-described embodiment.

(Examples 5 and 6 and Comparative Example 4)
First, the amorphous resin shown in Table 2 is supplied to each of the main extruder and the sub-extruder of the multilayer extruder having the main extruder (screw diameter 40 mm) / sub-extruder (screw diameter 20 mm), and the cylinder temperature After melt-kneading at 210 ° C. to 250 ° C., the mixture was supplied to a two-layer distribution type feed block.

  Next, the resin supplied from the sub-extruder to the feed block becomes the shape transfer layer layer (high fluidity resin layer) 61, and the resin supplied from the main extruder to the feed block becomes the main layer (low fluidity resin layer) 62. The resin in the feed block was extruded in a sheet form at a T die temperature of 240 ° C. to 250 ° C. via a T die having a width of 300 mm.

  Thereafter, the extruded continuous resin sheet 60 is sandwiched between a preload roll (mirror cooling roll) 52D and a first pressing roll (mirror cooling roll) 52A, and conveyed while being wound around the surface of the first pressing roll 52A. The continuous resin sheet 60 sandwiched between the first pressing roll 52A and the second pressing roll (shape roll) 52B, conveyed in a state wound around the surface of the second pressing roll 52B, and taken off from the second pressing roll 52B is taken up. , 52E. Thereby, the surface shape transfer resin sheet in which the concave shape was transferred to the high fluidity resin layer was obtained. And shape transfer rate T (= H '/ H) of the obtained resin sheet was calculated | required by said formula. The results are shown in Table 5.

  Thus, according to the manufacturing method of the resin sheet which concerns on embodiment of this invention, the shape transfer rate of a resin sheet can be improved.

  As mentioned above, although this invention was concretely demonstrated based on the embodiment, this invention is not limited to the said embodiment. In the above embodiment, as a continuous resin sheet having a multilayer structure, the shape transfer layer (A) and the main layer (B) sandwiched between the shape transfer layer (A) are provided on both sides in the thickness direction. One sheet surface to which the shape of the transfer mold is transferred may be composed of the resin (a) as the surface layer (A), and the other sheet surface may be composed of another resin different from the resin (a). For example, the other sheet surface may be made of resin (b) to produce a continuous resin sheet having a two-layer structure.

  Moreover, although the said embodiment demonstrated the light-guide plate or the light diffusing plate as a resin sheet, you may create another resin sheet. The resin sheet manufacturing method of the present invention is effective for manufacturing a shape light guide plate and a shape diffusion plate mounted on a backlight of a liquid crystal TV. The present invention is particularly effective for manufacturing a shape light guide plate and a shape diffusion plate having a high aspect ratio.

  Moreover, in the said embodiment, although the continuous resin sheet is manufactured using the resin sheet manufacturing apparatuses 50, 50B, 50C, 50D, 50E, and 50F shown in FIGS. 1-5 and FIG. You may use the resin sheet manufacturing apparatus which can perform a manufacturing process.

  Moreover, the surface temperature of the continuous resin sheet immediately after peeling from the shape roll is (Tg (a) -10) with respect to the glass transition temperature Tg (a) of the resin (a) constituting the shape transfer layer (A). ) It is preferable that the temperature is in the range of not less than ° C and not more than (Tg (a) +30) ° C.

  Moreover, the surface temperature of the continuous resin sheet immediately after peeling from the shape roll is Tg (b) ° C. to Tg () with respect to the glass transition temperature Tg (b) of the resin (b) constituting the main layer (B). a) It may be in the range of ° C.

  50, 50B, 50C, 50D, 50E, 50F ... resin sheet manufacturing apparatus, 51 ... die, 52A ... first pressing roll, 52B ... second pressing roll (shape roll), 52C ... third pressing roll, 52D ... preloading roll , 53 ... transfer mold, 57 ... resin inlet, 58 ... extruder, 60 ... continuous resin sheet, 61, 63 ... surface layer (A), 62 ... main layer (B).

Claims (12)

A sheet manufacturing process for continuously extruding a heat-melted resin from a die to manufacture a continuous resin sheet;
In a resin sheet manufacturing method comprising a transfer step of transferring the transfer mold to the sheet surface of the continuous resin sheet using a shape roll having a transfer mold formed on the peripheral surface,
The transfer step includes transferring the shape of the transfer mold of the shape roll to the continuous resin sheet by sandwiching and pressing the continuous resin sheet manufactured by the sheet manufacturing step between the press roll and the shape roll. A transfer start process to start;
A transporting step of transporting the continuous resin sheet having the shape of the transfer mold transferred to the surface of the sheet in the transfer start step while being in close contact with the peripheral surface of the shape roll;
A peeling step of peeling the continuous resin sheet conveyed in the conveying step from the peripheral surface of the shape roll,
The continuous resin sheet manufactured by the sheet manufacturing process has a multilayer structure having a plurality of layers in the thickness direction of the sheet, and shape transfer that constitutes the surface of the sheet disposed on the shape roll side in the transfer start process Comprising at least two layers of a layer (A) and a main layer (B) adjacent to the back side of the shape transfer layer,
The ratio of the MFR of the shape transfer layer (A) to the MFR of the main layer (B) (measured value measured according to JISK7210 at a temperature of 200 ° C. and a load of 49 N) is 1.5 or more. A method for producing a resin sheet. The transfer step includes
A preloading step of pressing the continuous resin sheet manufactured by the sheet manufacturing step by sandwiching between the preloading roll and the pressing roll;
Including a preliminary conveying step of conveying the continuous resin sheet pressed in the preloading step while being in close contact with the peripheral surface of the pressing roll,
The method for producing a resin sheet according to claim 1, wherein in the transfer start step, the continuous resin sheet conveyed in the preliminary conveyance step is sandwiched and pressed between the pressing roll and the shape roll. When the glass transition temperature of the resin (a) constituting the shape transfer layer (A) is Tg (a),
The surface temperature of the shape transfer layer (A) immediately before contacting the peripheral surface of the shape roll is:
(Tg (a) +50) ° C. to (Tg (a) +150) ° C.
The surface temperature of the shape transfer layer (A) immediately after being peeled from the peripheral surface of the shape roll is:
It is the range of (Tg (a) -10) degreeC-(Tg (a) +40) degreeC. The manufacturing method of the resin sheet of Claim 1 or 2. The ratio of the thickness of the said shape transfer layer (A) with respect to the thickness of the said main layer (B) is the range of 1 / 200-1 / 10. Manufacture of the resin sheet as described in any one of Claims 1-3. Method. The heating process of heating the sheet | seat surface of the said shape transfer layer (A) of the said continuous resin sheet conveyed in close contact with the surrounding surface of the said press roll immediately before the said transfer start process is provided. The manufacturing method of the resin sheet as described in any one. In the transfer mold, a plurality of grooves continuous in the circumferential direction of the shape roll are provided in parallel in the rotation axis direction of the shape roll,
The method for producing a resin sheet according to any one of claims 1 to 5, wherein an arrangement interval P of the plurality of groove portions is 200 µm to 500 µm. In the transfer mold, a plurality of grooves continuous in the circumferential direction of the shape roll are provided in parallel in the rotation axis direction of the shape roll,
The method for producing a resin sheet according to any one of claims 1 to 6, wherein the plurality of groove portions are arranged at equal intervals. In the transfer mold, a plurality of grooves continuous in the circumferential direction of the shape roll are provided in parallel in the rotation axis direction of the shape roll,
The depth H of the said some groove part is 100 micrometers-500 micrometers. The manufacturing method of the resin sheet as described in any one of Claims 1-7. In the transfer mold, a plurality of grooves continuous in the circumferential direction of the shape roll are provided in parallel in the rotation axis direction of the shape roll,
The method for producing a resin sheet according to any one of claims 1 to 8, wherein an aspect ratio H / P, which is a ratio of a depth H of the groove portions to an arrangement interval P of the plurality of groove portions, is 0.3 or more. . In the transfer mold, a plurality of grooves continuous in the circumferential direction of the shape roll are provided in parallel in the rotation axis direction of the shape roll,
The resin sheet according to any one of claims 1 to 9, wherein a cross-sectional shape of the groove portion in a direction orthogonal to the circumferential direction of the shape roll is a substantially semicircular shape, a substantially semielliptical shape, or a prism shape. Method. In the transfer mold, a plurality of grooves continuous in the circumferential direction of the shape roll are provided in parallel in the rotation axis direction of the shape roll,
The method for producing a resin sheet according to any one of claims 1 to 10, wherein a cross-sectional shape of the groove portion in a direction orthogonal to a circumferential direction of the shape roll is a corresponding shape for forming an optical lens. The resin (a) constituting the shape transfer layer (A) is a styrene resin or an acrylic resin,
The method for producing a resin sheet according to any one of claims 1 to 11, wherein the resin (b) constituting the main layer (B) is a styrene resin or an acrylic resin.

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