JP2009274387A - Resin sheet with protective film, and method for manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a resin sheet with protective films free from deformation of the resin sheet even when anneal-treated in a state where the protective films are laminated on both front and rear surfaces of the resin sheet, and a method for manufacturing the same. <P>SOLUTION: This resin sheet with protective films comprises a resin sheet and protective films pasted on both front and rear surfaces thereof, where the resin sheet and the protective film satisfy following relations of (1) an absolute value [thermal expansion coefficient of resin sheet-thermal expansion coefficient of protective film] ≤2×10<SP>-5</SP>/°C, and (2) tensile modulus of protective film/tensile modulus of resin sheet ≤1/7. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a resin sheet with a protective film and a method for producing the same, and more particularly to a resin sheet with a protective film and a method for producing the same, which can prevent deformation of the resin sheet and peeling of the protective film even after annealing.

  As a resin sheet used for various optical elements, a flat resin sheet having no thickness deviation or an uneven thickness resin sheet having a thickness deviation is used. These resin sheets are manufactured by discharging a resin melted by an extruder from a die and forming the discharged resin into a sheet shape with a pair of nip rollers. When molding an uneven resin sheet, it can be formed by replacing one of the pair of nip rollers with a mold roller. In the molded resin sheet, particularly a resin sheet for an optical element, a protective film is laminated on the front and back surfaces in order to protect the front and back surfaces from scratches and the like.

  Then, by performing the annealing process in a state where the protective film is laminated, residual strain at the time of molding can be removed so that the resin sheet is not damaged. The resin sheet from which residual strain has been removed is subjected to machine processing such as end face processing of the resin sheet in the subsequent process. In this case as well, the front and back surfaces of the resin sheet are protected from scratches, etc. It is necessary to laminate a protective film on the front and back surfaces in order not to adhere to the surface.

  As inventions that define the relationship between a protective film and a resin sheet in heat treatment such as annealing treatment, there are Patent Literature 1 and Patent Literature 2.

  In Patent Document 1, the protective film is not lifted from the polarizing plate even by heat treatment by defining the flow rate (conveying direction) and the dimensional change rate in the width direction of the protective film laminated on the polarizing plate within a predetermined range. The invention to be described is described.

In Patent Document 2, a protective film made of a laminate of films having different properties such as density is used as a protective film for a plastic optical material or the like, so that the protective film is lifted from the plastic optical material even when heat-treated. An invention to prevent it is described.
JP 2002-265893 A JP 2006-299162 A

  However, if annealing is performed with the protective film laminated on the front and back surfaces of the resin sheet, the protective film expands and contracts and deforms, so that the deformation force is transmitted to the resin sheet and the resin sheet is also deformed. The problem of this deformation is the same when the protective films of Patent Documents 1 and 2 are used.

  The present invention has been made in view of such circumstances, and a resin sheet with a protective film in which the resin sheet does not deform even when annealed in a state where a protective film is laminated on the front and back surfaces of the resin sheet, and its An object is to provide a manufacturing method.

  In order to achieve the object, the resin sheet with a protective film of the present invention includes a resin sheet and protective films attached to the front and back surfaces of the resin sheet, and the resin sheet and the protective film are represented by the following formula ( It is characterized by satisfying 1) and (2).

| Thermal expansion coefficient of the resin sheet−The thermal expansion coefficient of the protective film | ≦ 2 × 10 ⁻⁵ / ° C. (1)
Tensile elastic modulus of protective film / tensile elastic modulus of resin sheet ≦ 1/7 (2)
The inventors of the present invention, as a result of earnest research on the relationship between the deformation of the protective film and the resin sheet in the annealing treatment of the resin sheet, the difference between the thermal expansion coefficient of the resin sheet and the thermal expansion coefficient of the protective film is within a predetermined range, Furthermore, by making the ratio of the tensile elastic modulus of the protective film and the tensile elastic modulus of the resin sheet within a predetermined range, the resin sheet may be deformed even if the protective film is laminated on the front and back surfaces of the resin sheet and annealed. I got no knowledge.

The present invention has been made on the basis of such knowledge. When removing the residual strain during molding in a state where the protective film is laminated on the front and back surfaces of the resin sheet, the protective film and the resin sheet are (1) | resin sheet. The thermal expansion coefficient of the protective film−the thermal expansion coefficient of the protective film | ≦ 2 × 10 ⁻⁵ / ° C., (2) the tensile elastic modulus of the protective film / the tensile elastic modulus of the resin sheet ≦ 1/7, Found no deformation.

  By reducing the difference between the thermal expansion coefficient of the resin sheet and the thermal expansion coefficient of the protective film, the deformation of the resin sheet during the annealing process can be reduced. Further, by making the tensile elastic modulus of the protective film smaller than the tensile elastic modulus of the resin sheet and making it softer than the resin sheet, the resin sheet will not be deformed even if expansion or contraction occurs in the protective film.

  In the above invention, the resin sheet with a protective film of the present invention preferably has an uneven shape in which the resin sheet has a thickness distribution.

  Resin sheets with uneven thickness are used, for example, as light guide plates for backlights in liquid crystal display devices, and are more likely to cause residual distortion during molding than flat resin sheets, and are protected on the front and back surfaces of uneven thickness resin sheets. This is because it is particularly important to remove residual strain by annealing so that the resin sheet is not deformed in a state where the film is laminated.

  In order to achieve the above object, a method for producing a resin sheet with a protective film of the present invention includes a step of extruding a molten resin from a die into a sheet, a step of niping the extruded resin sheet with a pair of nip rollers, A step of laminating a protective film on the front and back surfaces of the resin sheet, a step of cutting and cutting the resin sheet, and a step of annealing the cut and cut resin sheet, the resin sheet and the protective film comprising: The following formulas (1) and (2) are satisfied.

| Thermal expansion coefficient of the resin sheet−The thermal expansion coefficient of the protective film | ≦ 2 × 10 ⁻⁵ / ° C. (1)
Tensile elastic modulus of protective film / tensile elastic modulus of resin sheet ≦ 1/7 (2)
The difference between the thermal expansion coefficients of the resin sheet and the protective film is 2 × 10 ⁻⁵ / ° C. or less, and the ratio of the tensile elastic modulus between the protective film and the resin sheet is 1/7 or less. The resin sheet does not deform even when annealing is performed in the state of laminating.

  In addition, whichever of the order of the step of laminating the protective film on the front and back surfaces of the resin sheet and the step of cutting and cutting the resin sheet may be performed first. In other words, when a strip-shaped resin sheet is formed by continuous molding and then cut into sheet-shaped resin sheets, and sheet-shaped resin sheets are molded from the beginning by batch-type molding such as injection molding or injection compression molding. Including both cases. In addition, the timing of laminating the protective film on the resin sheet may be obtained by laminating the protective film on the belt-shaped resin sheet and then cutting it into sheets. Alternatively, the protective film may be cut after cutting the belt-shaped resin sheet into sheets. You may laminate.

  The manufacturing method of the resin sheet with a protective film of the present invention includes the step of forming the resin sheet in an uneven shape, wherein one of the pair of nip rollers is a mold roller.

  The manufacturing method of the resin sheet with a protective film is suitably applied to the resin sheet having an uneven shape. Residual strain is likely to occur during molding compared to a flat resin sheet, and with the protective film laminated on the front and back surfaces of the uneven thickness resin sheet, the residual strain can be removed by annealing so that the resin sheet does not deform. This is especially important.

  According to the present invention, since the resin sheet is not deformed even if the annealing treatment is performed in a state where the protective film is laminated on the front and back surfaces of the resin sheet, a high-quality resin sheet for an optical element is manufactured. Can do.

  Hereinafter, preferred embodiments of a method and an apparatus for producing a resin sheet according to the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is an overall process diagram of a method for producing a resin sheet according to the present invention, and FIG. 2 is an overall configuration diagram of a production line for carrying out the production method. In the present embodiment, an example in which an uneven thickness resin sheet is manufactured as a resin sheet by continuous molding will be described. In the present embodiment, the strip-shaped resin sheet before cutting / cutting is referred to as a resin sheet A, and the sheet-shaped resin sheet after cutting is referred to as a resin sheet a.

  As shown in FIG. 1, the manufacturing method 10 of the uneven thickness resin sheet of this invention mainly has the raw material process 12 which measures and mixes a raw material, the melting process 14 which fuse | melts a raw material with an extruder, and a molten resin is die-molded. A molding cooling step 16 for continuously extruding the extruded sheet-like resin sheet A and cooling and solidifying the extruded sheet-shaped resin sheet A while performing uneven thickness molding, a slow cooling step 18 for gradually cooling the solidified resin sheet A, and a resin Laminating step 20 for laminating protective films on the front and back surfaces of sheet A, cutting / cutting step 22 for cutting resin sheet A into a predetermined size (length / width), and integration for collecting cut and cut resin sheet a Step 24, annealing treatment step 26 for annealing the accumulated resin sheet a, and replacing the protective film laminated on the annealed resin sheet a with another protective film It includes replacement and step 28, the machining process 30 for mechanically processing the end surface of the resin sheet a that replacement of the protective film, the. Thereby, for example, a product resin sheet for optical use is manufactured.

  A thermoplastic resin can be used as a resin raw material of the resin sheet applied to the present invention. For example, polymethyl methacrylate resin (PMMA), polycarbonate resin, polystyrene resin, MS resin, AS resin, polypropylene resin, polyethylene resin, polyethylene terephthalate resin, polyvinyl chloride resin (PVC), thermoplastic elastomer, or a copolymer thereof And cycloolefin polymers.

  Next, the apparatus configuration provided for the above-described process of the present invention will be described with reference to FIG.

  As shown in FIG. 2, in the raw material process 12, the raw material resin and additive sent from the raw material silo 31 (or raw material tank) and the additive silo 32 (or additive tank) to the metering mixer 34 are automatically weighed, The raw material resin and the additive are mixed at a predetermined ratio by the metering mixer 34. When adding diffusing particles as an additive to the raw material resin, a master pellet in which the diffusing particles are added to the raw material resin at a concentration higher than a predetermined concentration is manufactured using a granulator (not shown). A master batch method in which the base pellets not added are mixed in a predetermined ratio by the metering mixer 34 can be suitably employed. The same applies when additives other than the diffusion particles are added.

The diffusion particles preferably have a particle size of 10 μm or less. As the kind of the diffusion particles, metal particles, inorganic particles, organic particles, semiconductor particles, polymer particles, and the like can be used. More specifically, silicon dioxide (SiO ₂ ), aluminum oxide (Al ₂ O ₃ ), oxidation Titanium (IV) (TiO ₂ ), yttrium oxide (Y ₂ O ₃ ), magnesium oxide (MgO), zinc oxide (ZnO), carbon (C), silicon (Si), magnesium (Mg), calcium (Ca), Silver (Ag), platinum (Pt), titanium (Ti), nickel (Ni), ruthenium (Ru), rhodium (Rh), gallium arsenide (GaAs), aluminum gallium arsenide (AlGaAs), zirconia (ZrO ₂ ), carbonized silicon (SiC), silicon nitride _{(Si 3 N} 4), zeolite, nano-diamond, nanocrystal, Sukumetaito, mica, Dendori Chromatography, may be mentioned a star polymer, hyperbranched polymers, microporous methyl phosphonic acid aluminum, and the like. Moreover, as a density | concentration of the spreading | diffusion particle contained in the particle | grain containing resin sheet manufactured, it is preferable that it is the range of 0.005-0.5 mass%, and is the range of 0.03-0.08 mass%. It is more preferable.

  The raw material resin appropriately weighed and mixed in the raw material process 12 is sent to the melting process 14.

  In the melting step 14, the raw material resin mixed by the metering mixer 34 is introduced into the extruder 38 through the hopper tank 36 and melted while being kneaded by the extruder 38. The extruder 38 may be either a single-screw extruder or a multi-screw extruder, and preferably includes a vent function that evacuates the inside of the extruder 38. The raw material resin melted by the extruder 38 is filtered by the filter 40 and then sent to the die 45 (for example, T die) of the molding and cooling step 16 through the supply pipe 43 by the metering pump 42 such as a pump or a gear pump. . It is preferable to pass a filter in front of the pump or gear pump in order to filter unmelted material and foreign matter. The form of the filter is not particularly limited, and examples thereof include a screen type and a leaf type filter.

  In the molding cooling step 16, the resin sheet A discharged from the die 45 is nipped between the mold roller 44 and the nip roller 46, cooled and solidified while being formed with uneven thickness molding, and the solidified resin sheet A is peeled off by the peeling roller 48. To do. Thereby, the strip-shaped uneven thickness resin sheet A in which the thickness is uneven in the width direction of the resin sheet A is formed.

  The extrusion speed of the resin sheet A from the die 45 can be 0.1 to 50 m / min, preferably 0.3 to 30 m / min. Therefore, the peripheral speed of the mold roller 44 is also made to substantially coincide with this. In addition, it is preferable to control the speed unevenness of each roller within 1% of the set value.

  The pressing pressure of the nip roller 46 against the mold roller 44 is set to 0 to 200 kN / m (kgf / cm) in terms of linear pressure (value converted assuming that the surface contact due to elastic deformation of each nip roller is linear contact). Is more preferable, and 0 to 100 kN / m (kgf / cm) is more preferable. The temperature control of the mold roller 44 and the peeling roller 48 is preferably performed for each individual roller. The surface temperature of the resin sheet A at the location of the peeling roller 48 is preferably equal to or higher than the glass transition temperature Tg. At this time, when a polymethyl methacrylate resin is employed for the resin sheet A, the set temperature of the peeling roller 48 can be set to 50 to 110 ° C.

  Examples of the shape of the uneven-thickness resin sheet A molded in the molding cooling step 16 include those shown in FIGS. 3A, 3 </ b> B, and 3 </ b> C in which the resin sheet A is shown in cross section in the width direction. is there. The resin sheet A in FIG. 3 (a) is thick at the center in the resin sheet width direction and becomes thinner toward both ends. FIG. 3B shows a shape in which FIG. 3A is connected in series in the resin sheet width direction. In FIG. 3C, the central part in the resin sheet width direction is thin and becomes thicker toward both ends.

  Therefore, a reverse shape of the concave and convex shape of the resin sheet is formed on the surface of the mold roller 44 in accordance with the manufacture of FIGS. 3A to 3C described above, and the reverse shape is transferred to the resin sheet A. In the uneven-shaped resin sheet A, the thickness of the thinnest portion is preferably 5 mm or less, and more preferably 2 mm or less. Further, the difference in thickness between the thickest part and the thinnest part of the uneven thickness resin sheet is preferably 0.5 mm or more, and more preferably 1.0 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.

  In the molding cooling step 16, the resin sheet A is heated by the heating means 25 until it is extruded from the die 45 and nipped by the mold roller 44 and the nip roller 46, and the temperature of the resin sheet A until the nipping is rapidly reduced. It is preferable not to do so. In addition, the uneven-shaped resin sheet A formed by being nipped by the mold roller 44 and the nip roller 46 is cooled by the mold roller 44, but the cooling speed of the thick part is slow and the cooling speed of the thin part is fast. It is difficult to achieve a uniform cooling rate. Therefore, a plurality of heating means 25 (or cooling means) capable of adjusting the temperature in the width direction of the mold roller 44 are provided along the rotation direction of the mold roller 44, and the cooling rate of the thick portion and the thin portion of the resin sheet A is provided. Is preferably made uniform. Furthermore, a plurality of heating means 27 (or cooling means) capable of adjusting the temperature in the width direction of the peeling roller 48 are provided along the rotation direction of the peeling roller 48 to cool the thick and thin portions of the uneven thickness resin sheet. It is more preferable to make the speed uniform.

  FIG. 4 shows an example in which a heater 25A is provided as an example of the heating means 25 capable of adjusting the temperature in the width direction of the mold roller 44. A plurality of heaters 25A are arranged in the width direction of the mold roller 44, and each heater 25A. A temperature sensor 25B is arranged in a pair. Thereby, the cooling rate of the resin sheet width direction is equalized.

  The resin sheet A that has undergone the molding cooling step 16 is then sent to the slow cooling step 18.

  The slow cooling step 18 is a step for gradually cooling the resin sheet A to room temperature while preventing a rapid temperature change of the resin sheet A downstream of the peeling roller 48. For this reason, the slow cooling process 18 is provided with a plurality of heating means 19 for preventing a rapid temperature drop by heating the front and back surfaces of the conveyed resin sheet A. When a sudden temperature change (particularly a temperature drop) occurs in the resin sheet A, for example, the inside of the resin sheet A is in an elastic state while the vicinity of the surface of the resin sheet A is in a plastic state. The surface shape of the resin sheet A deteriorates due to the shrinkage due to. Further, a temperature difference is generated between the front and back surfaces of the resin sheet A, and the resin sheet A is likely to warp. In particular, warping is likely to occur when there is a thickness distribution in the resin sheet width direction, such as an uneven thickness resin sheet.

  Further, a tension cut roller 21 (also referred to as a draw roller) that sandwiches and conveys the resin sheet A with a pair of rollers is provided between the molding cooling step 16 and the slow cooling step 18, so that the resin sheet A in the molding cooling step 16 is provided. It is preferable that the conveyance tension of the resin sheet A in the slow cooling step 18 is larger than the conveyance tension. For example, the resin sheet A is nipped by the mold roller 44 and the nip roller 46 that rotate at the peripheral speed V1, and the uneven shape on the surface of the mold roller 44 is transferred to the resin sheet A, and the resin sheet A after transfer is transferred at the peripheral speed V1. It is nipped and conveyed by a tension cut roller 21 having a peripheral speed V2 of 102 to 107%. Thus, by increasing the conveyance speed of the resin sheet A on the downstream side of the molding cooling step 16 so that a predetermined tension is applied in the conveyance direction of the resin sheet A, the transfer accuracy in the molding cooling step 16 and The effect of preventing deformation (for example, warpage) of the resin sheet A in the slow cooling step 18 can be increased. The tension cut roller used here may be driven.

  The resin sheet A cooled in the slow cooling step 18 is sent to the laminating step 20 and the cutting / cutting step 22.

The laminating step 20 is a step of attaching a protective film (having an adhesive layer to a film of polyethylene or the like) on the front and back surfaces of the resin sheet A, and the protective film 52 rewound from the pair of reels 50 is attached to the resin sheet A. They are joined together so as to be sandwiched, and laminated by passing through the nip roller 54. As physical properties of the film itself excluding the adhesive layer of the protective film 52, those having a small difference in thermal expansion coefficient from the resin sheet a and a small ratio of tensile elastic modulus (for example, Young's modulus) to the resin sheet a are used. The difference in thermal expansion coefficient between the resin sheet a and the protective film 52 is 2 × 10 ⁻⁵ / ° C. or less, and the ratio of the tensile elastic modulus between the protective film 52 and the resin sheet a is 1/7 or less. Moreover, the protective film 52 used here has a pressure-sensitive adhesive layer having an adhesive strength of 0.05 to 0.3 N / 25 mm, and preferably has a pressure-sensitive adhesive layer of 0.1 to 0.2 N / 25 mm. Is preferred.

  As a material of the protective film 52 applied to the present invention, a thermoplastic resin can be used, and examples thereof include polypropylene resin (PP), polyethylene resin (PE), and polyethylene terephthalate resin (PET). The thickness of the protective film 52 is preferably 0.2 mm or less, and more preferably 0.1 mm or less.

  In the cutting / cutting step 22, both end portions (ear portions) in the width direction of the resin sheet A laminated with the protective film 52 are cut and cut out, and the resin sheet A is cut into a predetermined length and trimmed. As the cutting machine 56, a guillotine type cutting machine composed of a receiving blade and a pressing blade can be preferably used, but the cutting machine 56 is not limited to this. Although not shown, a laser cutter or electron beam cutting can be suitably used as the cutting machine, but is not limited to this.

  The resin sheet a with the protective film 52 cut to a predetermined size is accumulated so as to be stacked by a stocker (not shown) in the next accumulation step 24 and then sent to the annealing step 26.

In the annealing treatment step 26, the accumulated resin sheet a is kept at a temperature 10 to 30 ° C. lower than the glass transition temperature of the resin sheet for 2 hours or more with the protective film 52 being laminated, and then cooled to room temperature. Thereby, the residual distortion at the time of shaping | molding is removed. At this time, when a polymethylmethacrylate resin is employed for the resin sheet, the ambient temperature is 80 to 100 ° C. In the annealing treatment step 26, in the present invention, the protective film 52 and the resin sheet a are (1) | the thermal expansion coefficient of the resin sheet−the thermal expansion coefficient of the protective film | ≦ 2 × 10 ⁻⁵ / ° C. Since the relationship of the tensile elastic modulus of the protective film / the tensile elastic modulus of the resin sheet ≦ 1/7 is satisfied, the resin sheet a is not deformed.

  In the present embodiment, when the protective film 52 is laminated on the front and back surfaces of the resin sheet a, the belt-shaped resin sheet A is laminated before being cut into a predetermined size. It carried out by the method of laminating in the forming method (conveying direction). However, as shown in FIG. 5, with respect to the sheet-like resin sheet a after cutting, the diameter changes in the width direction from one end side to the other end side in the width direction of the resin sheet having a biased thickness. It is preferable to laminate using a flat roller having no surface. The laminating apparatus is the same as in the case of FIG. 2, and the protective film 52 unwound from the pair of reels 50 is joined so as to sandwich the resin sheet A, and the resin sheet a moves in the direction of the arrow and passes through the nip roller 54. Is laminated. Further, the roller of the nip roller 54 disposed on the uneven surface side of the resin sheet a is connected to the cylinder 29 so as to expand and contract following the unevenness. Thus, the protective film 52 can be laminated from one end to the other side in the width direction following the thickness deviation, so that the protective film 52 is free from creases and wrinkles as compared with the case of laminating in the molding direction. Can be laminated. Accordingly, since the expansion and contraction of the protective film 52 occurs evenly during the annealing process, a large deformation force is not generated in a part of the protective film 52. Therefore, since the deformation force can be evenly absorbed by the weak adhesive layer of the protective film 52, it is possible to further prevent the deformation force from being transmitted to the resin sheet a. Moreover, a commercially available laminating apparatus can be used by laminating the protective film 52 with respect to the sheet-like resin sheet a.

  The annealed resin sheet a is sent to the machining step 30 after passing through the protective film re-stripping step 28.

  In the protective film replacement step 28, the protective film 52 during the annealing treatment is peeled off. A protective film (not shown) having an adhesive layer having an adhesive strength of 0.4 to 4.5 N / 25 mm, which is larger than the adhesive strength of the protective film 52 laminated before the annealing treatment, is newly provided on the front and back surfaces of the resin sheet a. It is stretched. More preferable adhesive force is in the range of 0.5 to 3.5 N / 25 mm.

  The protective film can be replaced manually by an operator or by an automatic replacement device. However, when the protective film is laminated on the front and back surfaces of the resin sheet a, the thickness of the protective film can be increased. It is preferable to laminate in the width direction of the resin sheet having a bias.

  In the machining step 30, the four end surfaces of the resin sheet a are polished with the protective film being laminated. By polishing the resin sheet a, the end surface is made into a desired shape and the surface roughness of the end surface is reduced. As a polishing apparatus, a method of polishing the end surface of the resin sheet a by rotating a cylindrical object having a blade attached thereto, a method of rotating and polishing a blade attached to a disk, etc. are suitably employed. it can.

  In the present embodiment, when the resin sheet a is machined, a protective film having a strong adhesive layer having an adhesive strength of 0.4 to 4.5 N / 25 mm is laminated, so that the protective film is a resin sheet. It does not lift or peel off from a. Thereby, since the grinding | polishing waste generated by grinding | polishing does not adhere to the front and back of the resin sheet a, generation | occurrence | production of the damage | wound and foreign material to the resin sheet a can be prevented.

  The machined resin sheet a becomes a product resin sheet and is shipped to a user or the like. In addition, it is preferable to provide an inspection process for inspecting the quality of the manufactured resin sheet a (no scratches, no warpage, etc.) after the machining process 30.

  In the warpage inspection of the manufactured resin sheet a, the pass / fail of the warpage of the resin sheet a with respect to a predetermined standard is measured by a warpage measuring device. Here, the warp will be described with an example of the resin sheet a having a bowl shape (FIG. 3A). As shown in FIG. 6, the back surface (flat surface side) of the resin sheet a cut out to a length of 600 mm and a width of 1100 mm is used. The maximum distance H between the resin sheet a and the measurement board 53 when it is placed on the flat upper surface of the measurement board 53 is referred to as a warp amount. Since the predetermined reference (standard value) of the amount of warpage is set according to the application of the resin sheet a and the standard on the user side, the warpage measuring device measures pass / fail with respect to the predetermined reference. A warpage measuring device is disposed after the slow cooling step 18, and the surface (uneven surface) of the resin sheet a is scanned with an electrostatic sensor or the like, and the distance (shape) between the resin sheet a and the electrostatic sensor is measured. A method of converting the warpage amount may be preferably used.

  In this inspection process, it is necessary to peel off the protective film for inspection, and therefore it is preferable to laminate the protective film again before shipment to the user. In this case, the protective film to be laminated again may be either weak adhesive or strong adhesive.

  As described above, according to the present embodiment, the deformation of the resin sheet can be prevented by setting the ratio between the thermal expansion coefficient difference between the protective film and the resin sheet and the ratio of the tensile elastic modulus within a predetermined range. .

  As a preferable material of the mold roller 44 in the present embodiment, various steel members, stainless steel, copper, zinc, brass, those metal materials made of a metal core, a rubber lining on the surface, and these metal materials are plated with HCr. , Cu plated, Ni plated, ceramics, and various composite materials can be used.

  In addition, although the shape of the surface of the mold roller 44 depends on the material of the roller surface, generally, a combination of cutting with an NC lathe and finishing buffing can be preferably employed. In addition, other known processing methods (grinding processing, ultrasonic processing, electric discharge processing, etc.) can also be employed. The surface roughness of the mold roller surface is preferably 0.5 μm or less, and more preferably 0.2 μm or less, in terms of the center line average roughness Ra. The mold roller 44 is rotationally driven at a predetermined peripheral speed by driving means (not shown).

  The nip roller 46 in the present embodiment is a roller that is disposed to face the mold roller 44 and clamps the resin sheet A with the mold roller 44. As the material of the nip roller 46, various steel members, stainless steel, copper, zinc, brass, these metal materials having a metal core and a rubber lining on the surface, these metal materials are HCr plated, Cu plated, Ni plated, etc. These materials, ceramics, and various composite materials can be used.

  The surface of the nip roller 46 is preferably processed into a mirror surface, and the center line average roughness Ra is preferably 0.5 μm or less, and more preferably 0.2 μm or less. By setting it as the smooth surface in this way, the back surface of the resin sheet A after a shaping | molding can be made into a favorable state. The nip roller 46 is rotationally driven at a predetermined peripheral speed by a driving means (not shown). In addition, although the structure which does not provide a drive means in the nip roller 46 is also possible, it is preferable to provide a drive means from the point which can make the back surface of the resin sheet A a favorable state.

  The nip roller 46 is provided with a pressing means (not shown) so that the resin sheet A between the nip roller 46 and the mold roller 44 can be pressed with a predetermined pressure. Each of the pressurizing means is configured to apply pressure in the normal direction at the contact point between the nip roller 46 and the mold roller 44, and various known means such as a motor driving means, an air cylinder, and a hydraulic cylinder can be employed. .

  The nip roller 46 can 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 back-up roller (not shown) is provided on the back side of the nip roller 46 (opposite side of the mold roller 44), a configuration in which a crown shape (middle and high shape) is adopted, and rigidity of the central portion in the axial direction of the roller It is possible to adopt a configuration of a roller having a strength distribution that increases the size of the roller, a configuration combining these, and the like.

  The peeling roller 48 in the present embodiment is disposed opposite to the mold roller 44 and is a roller for peeling the resin sheet A from the mold roller 44 by winding the resin sheet A, and is 180 degrees downstream of the mold roller 44. Be placed. The surface of the peeling roller 48 is preferably processed into a mirror surface. By setting it as such a surface, the back surface of the resin sheet A after shaping | molding can be made into a favorable state. The surface roughness of the surface of the peeling roller 48 is preferably 0.5 μm or less, and more preferably 0.2 μm or less in terms of the centerline average roughness Ra. As the material of the peeling roller 48, various steel members, stainless steel, copper, zinc, brass, these metal materials having a metal core and a rubber lining on the surface, these metal materials are HCr plated, Cu plated, Ni plated For example, ceramics and various composite materials can be used. The peeling roller 48 is rotationally driven in the direction of the arrow at a predetermined peripheral speed by a driving means (not shown). In addition, although the structure which does not provide a drive means in the peeling roller 48 is also possible, it is preferable to provide a drive means from the point which can make the back surface of the resin sheet A a favorable state.

  As an apparatus configuration relating to temperature control relating to temperature control in the molding cooling step to the slow cooling step, the configuration shown in FIG. 7 can be preferably employed. That is, the heater 25A (or cooler) and the temperature sensor 25B are provided in pairs in the width direction of the mold roller 44, and the heater 25A is provided on the upstream side and the downstream side of the peeling position of the peeling roller 48, respectively. . The temperature of the front and back surfaces of the resin sheet A peeled off by the peeling roller 48 is detected by a pair of temperature sensors 25B.

  Further, in the slow cooling step 18, a slow cooling zone 58 having a horizontal tunnel shape is provided, and a heater 25A (or a cooler) and a temperature sensor 25B are provided in a pair inside the tunnel, so that the resin sheet A is slowly cooled. The temperature profile can be controlled. As the heater 25A (or cooler), a resin sheet is formed by a structure in which air (hot air or cold air) whose temperature is controlled from a plurality of nozzles is jetted toward the resin sheet A, a nichrome wire heater, an infrared heater, dielectric heating means, or the like. Various known means such as a structure for heating the front and back surfaces of A can be employed.

  Thus, by detecting the temperature distribution in the resin sheet width direction by the plurality of temperature sensors 25B and obtaining an appropriate PID value for feedback control to the heater 25A (or cooler) paired with the temperature sensor 25B, The cooling rate at the time of shaping | molding of the resin sheet A and the cooling rate at the time of slow cooling can be controlled appropriately. Thereby, temperature can be controlled so that the temperature distribution of the width direction of the resin sheet A may become uniform, and the resin sheet A of a desired shape can be manufactured. In addition, depending on the shape, in order to form a sheet in which distortion and warpage are suppressed, it may be preferable to have a specific temperature distribution in the width direction of the resin sheet A. In this case, control is performed so that the temperature distribution is obtained.

  In the present embodiment, the example in which the uneven thickness resin sheet is manufactured by continuous molding has been described. However, the present invention is not limited to this, and can be applied to the manufacture of a flat resin sheet. It may be manufactured by batch molding.

  The present invention will be described more specifically with reference to the following examples. The materials, production conditions, and the like shown in the following examples can be changed as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention is not limited to the following specific examples.

Using the production line of FIG. 1, a protective film was laminated on a resin sheet, and annealed at 90 ° C. for 4 hours. The relationship between the protective film and the resin sheet is (1) | the thermal expansion coefficient of the resin sheet−the thermal expansion coefficient of the protective film | ≦ 2 × 10 ⁻⁵ / ° C. and (2) the tensile elastic modulus of the protective film. A comparison test between the case where the tensile elastic modulus of the resin sheet ≦ 1/7 is satisfied (Example) and the case where an unsatisfactory protective film is used (Comparative Example) will be described. As the resin sheet, a polymethyl methacrylate resin having a thermal expansion coefficient of 2 × 10 ⁻⁵ / ° C. and a tensile elastic modulus of 2900 MPa was used in both Examples and Comparative Examples. The protective film was laminated using a flat roller having no diameter change in the width direction.

[Example 1]
A protective film having a thermal expansion coefficient of 8 × 10 ⁻⁵ / ° C. and a tensile elastic modulus of 400 MPa was laminated on the front and back surfaces of the resin sheet, and annealed at 90 ° C. for 4 hours.

[Comparative Example 1]
The front and back surfaces of the resin sheet were laminated on a protective film having a thermal expansion coefficient of 10 × 10 ⁻⁵ / ° C. and a tensile elastic modulus of 400 MPa, and annealed at 90 ° C. for 4 hours.

[Comparative Example 2]
On the front and back surfaces of the resin sheet, a protective film having a thermal expansion coefficient of 8 × 10 ⁻⁵ / ° C. and a tensile elastic modulus of 800 MPa was laminated and annealed at 90 ° C. for 4 hours.

(Test results)
About Example 1 and Comparative Examples 1-2, it was measured by the curvature measuring method demonstrated in FIG. 6 whether the resin sheet after an annealing process had a deformation | transformation. Further, it was visually examined whether the protective film was lifted or peeled off during the annealing treatment.

  As a result, in Example 1, generation | occurrence | production of the deformation | transformation of the resin sheet by a protective film was not seen. In addition, the protective film did not lift or peel off during the annealing treatment.

  On the other hand, in Comparative Examples 1 and 2, although the peeling of the protective film was not confirmed, the resin sheet was deformed by 10 mm or more in the warp measurement.

Overall process diagram of the resin sheet manufacturing method of the present invention The whole block diagram of the manufacturing line which enforces the manufacturing method of the resin sheet of the present invention Explanatory drawing explaining the kind of shape of an uneven thickness resin sheet It is the figure which looked at the type | mold roller part of a shaping | molding cooling process from the bottom, and is a figure which shows the example of arrangement | positioning of a heating means and a temperature sensor Explanatory drawing explaining the direction which laminates a protective film on a resin sheet Explanatory drawing explaining the curvature of a resin sheet Explanatory drawing which shows an example of temperature control in a shaping | molding cooling process and a slow cooling process

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Manufacturing process of resin sheet, 12 ... Raw material process, 14 ... Melting process, 16 ... Molding cooling process, 18 ... Slow cooling process, 19, 25, 27 ... Heating means (or cooling means), 20 ... Lamination process, 21 ... tension cut roller, 22 ... cutting / cutting process, 23 ... heating means, 24 ... accumulating process, 26 ... annealing process, 28 ... re-covering process of protective film, 29 ... cylinder, 30 ... machining process, 31 ... raw material Silo, 32 ... Additive silo, 34 ... Metering mixer, 36 ... Hopper tank, 38 ... Extruder, 40 ... Filter, 42 ... Metering pump, 43 ... Feed pipe, 44 ... Mold roller, 45 ... Die, 46 ... Nip roller 48 ... Peeling roller 50 ... Reel 52 ... Protective film 53 ... Measurement base 54 ... Nip roller 56 ... Cutting machine 58 ... Slow cooling zone

Claims (4)

A resin sheet with a protective film, comprising: a resin sheet; and protective films attached to the front and back surfaces of the resin sheet, wherein the resin sheet and the protective film satisfy the following formulas (1) and (2): .
| Thermal expansion coefficient of the resin sheet−The thermal expansion coefficient of the protective film | ≦ 2 × 10 ⁻⁵ / ° C. (1)
Tensile elastic modulus of protective film / tensile elastic modulus of resin sheet ≦ 1/7 (2)   The resin sheet with a protective film according to claim 1, wherein the resin sheet has an uneven shape having a thickness distribution. Extruding the molten resin from the die into a sheet,
Nip the extruded resin sheet with a pair of nip rollers;
Laminating a protective film on the front and back surfaces of the resin sheet;
Cutting and cutting the resin sheet;
Annealing the cut and cut resin sheet;
And the resin sheet and the protective film satisfy the following formulas (1) and (2):
| Thermal expansion coefficient of the resin sheet−The thermal expansion coefficient of the protective film | ≦ 2 × 10 ⁻⁵ / ° C. (1)
Tensile modulus of protective film / tensile modulus of resin sheet ≦ 1/7 (2)   4. The method for producing a resin sheet with a protective film according to claim 3, wherein one of the pair of nip rollers is a mold roller, and includes a step of forming the resin sheet in an uneven shape.

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