JP6941449B2 - Resin sheet manufacturing method - Google Patents

Description

The present invention relates to a method for producing a resin sheet, and more particularly to a method for producing a resin sheet having a grid pattern, which can be used as a substitute for checker glass.

Checker glass is also called waffle glass or mosaic glass, and is used for antique-style interior doors and furniture because it has an excellent design and a retro feel. The checkered glass lattice pattern is formed by shaping grooves extending in one direction on one surface at equal intervals to form a semi-cylindrical convex pattern, and on the other surface in a direction orthogonal to the groove on the one surface. It is formed by shaping the extending grooves at equal intervals to form a semi-cylindrical convex pattern, and when viewed from the surface, the front and back semi-cylindrical convex patterns overlap and appear as a checkerboard pattern as a whole.

The checker glass is usually manufactured by a rollout method. In the rollout method, as shown in FIG. 7, the checkered glass is formed by passing the melted glass 22 directly between the upper and lower engraving rolls 21a and 21b. The lattice pattern forms a large number of concave grooves continuous in the circumferential direction of the roll in one of the upper and lower engraving rolls, and a large number of concave grooves continuous in the width direction of the roll in the other roll. A groove is formed, and the molten glass is formed by rolling it with two upper and lower engraving rolls 21a and 21b.

Although checkered glass is excellent in design, it is made of glass, so there is a problem that it lacks lightness, it is easily broken by impact, and there is a risk of being injured by debris when it is damaged. On the other hand, the thermoplastic resin is a material that can be used as a substitute material for glass because of its features of light weight, excellent impact resistance, and excellent workability. However, the method for manufacturing checker glass cannot be directly applied to the manufacture of resin checker sheets.

That is, in the case of glass, after melting, the glass is rapidly cooled by contacting with a roll at a low temperature, and the viscosity of the glass rapidly increases, so that a flat glass with small warpage and distortion can be obtained. However, if this method is applied to the production of a resin sheet as it is, the viscosity of the thermoplastic resin increases slowly with respect to the temperature decrease, and the resin remains in a flexible state even after passing through the roll, so that the plate warps. And the pattern will be distorted. As a method that can solve this problem and manufacture a resin plate that can be used as a substitute for checker glass, a resin sheet manufacturing technique that combines T-die extrusion and a shaping roll can be considered. Specifically, it is conceivable to apply manufacturing technology related to a microprism sheet used for a light guide plate for a liquid crystal display or a light diffusing plate. Prior arts that belong to this field and can be used in the production of double-sided shaped resin sheets include the techniques disclosed in Patent Document 1 and Patent Document 2.

In Patent Document 1, the molten resin is extruded into a sheet through a T-die, and the outer surface of the sheet-like material immediately after being extruded is reflected by a reflective member provided on the surface of the tip of the die lip of the T-die to reflect the irradiation light of an infrared heater. After irradiating and heating in the air, the shape is transferred by pressurizing the first cooling molding roll and the second cooling molding roll for imparting the embossed shape to transfer the shape of the sheet-like material having the embossed shape. The target is for the total thickness T of the sheet by cooling while taking over along the second embossing shape-imparting cooling molding roll and further cooling while taking over along the third cooling molding roll. A technique for manufacturing a thermoplastic resin sheet is disclosed, which enables continuous shaping of an embossed shape having a relatively low shape height H and a fine pitch with a high shaping rate and good shape transfer accuracy. ing.

In Patent Document 2, molten resin is extruded from a die into a sheet, rolled between a first roll having a mirror surface and a second roll having an embossed shape to form an embossed pattern, and then the surface is surfaced by a third roll. In the method for manufacturing a thermoplastic resin sheet with a concavo-convex pattern that forms a plurality of concavo-convex shapes, the temperatures of the first roll, the second roll, and the third roll are set in a specific range, and the peripheral speed of the third roll is specified. A method for manufacturing a thermoplastic resin sheet is disclosed, in which a thermoplastic resin sheet having a fine uneven shape that sufficiently exhibits the original design performance can be efficiently manufactured by controlling the range.

Japanese Unexamined Patent Publication No. 2008-80496 Japanese Unexamined Patent Publication No. 2011-73429

When the manufacturing technique for the microprism sheet used for the light guide plate for the liquid crystal display and the light diffusing plate disclosed in Patent Documents 1 and 2 is applied to the manufacturing of the checker sheet as it is, the lattice pattern formed by the lateral groove is formed. Either the lateral straightness is too poor, or the height of the shaped handle is too small for the depth of the groove (the shaping rate is too low), and the shape is shaped by the lateral groove. It was difficult to satisfy both the linearity of the grid pattern and the shaping rate.

In view of the above problems, the present invention provides a checkered pattern that can be used as a substitute for checker glass by rolling the extruded sheet-like material, and has both a groove-shaped shape forming rate and a linearity of the checkered pattern. It is an object of the present invention to provide a method for producing a shaped resin sheet.

According to the present invention, the following resin sheets are provided.
[1] In a method for producing a resin sheet, in which a molten thermoplastic resin is extruded into a sheet, and the surface shape of a molding roll is transferred to both surfaces of the extruded sheet while taking over the extruded sheet.
The thickness of the resin sheet is 3 mm or more, and the resin sheet has a thickness of 3 mm or more.
The forming roll is composed of a vertical groove roll having a large number of concave grooves continuous in the circumferential direction of the roll and a horizontal groove roll having a large number of concave grooves continuous in the width direction of the roll.
The groove depth of the concave groove of the molding roll is 1000 μm or less.
The extruded sheet-like material is first contacted with one molding roll, or both molding rolls are brought into contact with each other at almost the same time, and the sheet-like material is first contacted with the molding roll. By sandwiching the sheet-like material between the horizontal groove roll and the vertical groove roll until the contacted molding roll rotates 90 ° (including 0 °) in the roll rotation direction, a horizontal groove is formed on one surface of the sheet-like material. A resin sheet characterized in that the surface shape of the roll is transferred, the surface shape of the vertical groove roll is transferred to the other surface of the sheet-like material, and the sheet-like material is held by the horizontal groove roll at an angle of 90 ° or more and picked up. Manufacturing method.
[2] The method for producing a resin sheet according to 1 above, wherein the thickness of the resin sheet is 3 mm or more and 10 mm or less.
[3] The method for producing a resin sheet according to 1 or 2 above, wherein the groove depth of the concave groove of the molding roll is 300 μm or more.
[4] The method for producing a resin sheet according to any one of 1 to 3 above, wherein the molding roll has a diameter of 100 to 1000 mm.
[5] The resin sheet according to any one of 1 to 4, wherein the width of the mountain portion 0.05 mm below the tip of the mountain portion between the concave grooves of the molding roll is 0.3 to 3 mm. Manufacturing method.
[6] The sheet-like material is sandwiched between a horizontal groove roll and a vertical groove roll so that the linear pressure when transferring the surface shape of the molding roll to the sheet-like material is 5 N / cm or more. The method for producing a resin sheet according to any one of 1 to 5.
[7] The method for producing a resin sheet according to any one of 1 to 6 above, wherein the thermoplastic resin is a styrene resin or an acrylic resin.

According to the method of the present invention, in the roll shaping of an extruded thermoplastic resin sheet-like material, the shape of a vertical groove and the shape of a horizontal groove are formed on the extruded sheet-like material at a specific position by using a molding roll having a specific arrangement. By shaping, it is possible to manufacture a resin checker sheet that can be used as a substitute for checker glass and is excellent in both the shape ratio of the groove shape and the linearity of the lattice pattern.

FIG. 1 is a schematic view showing an example of an apparatus capable of carrying out the method of the present invention. FIG. 2A is a schematic view showing an example of a vertical groove roll, and FIG. 2B is a schematic view showing an example of a horizontal groove roll. FIG. 3 is a schematic view of a concave groove formed on the roll surface. FIG. 4 is a schematic view showing another example of an apparatus capable of carrying out the method of the present invention. FIG. 5 is a schematic view showing still another example of an apparatus capable of carrying out the method of the present invention. FIG. 6 is an enlarged view of a portion of FIG. 1 in which a sheet-like object is sandwiched between a horizontal groove roll and a vertical groove roll. FIG. 7 is a schematic view of a rollout method for manufacturing checkered glass.

Hereinafter, the method for producing the resin sheet of the present invention will be described in detail with reference to the drawings.
The method for forming a lattice pattern in the present invention has a large number of concave grooves in which a thermoplastic resin is supplied to an extruder, melt-kneaded, and then extruded into a sheet, and the extruded sheet is continuous in the circumferential direction of the roll. This is a method of transferring the surface shape of a molding roll to both surfaces of the sheet-like material while taking it with a molding roll composed of a vertical groove roll and a horizontal groove roll having a large number of concave grooves continuous in the width direction of the roll. In the present invention, a large number of semi-cylindrical convex portions (hereinafter, also referred to as vertical handles) along the vertical direction are formed on one surface of the sheet-like object by the vertical groove roll, and the other of the sheet-like objects is formed by the horizontal groove roll. A large number of semi-cylindrical convex parts (hereinafter, also referred to as arrogant patterns) are formed on the surface of the surface.
In the present invention, the large number of recesses means at least 3 or more recesses, preferably 30 to 100 recesses.

In the method of the present invention, a checkerboard pattern is formed by going through the following steps (1) and (2).
(1) The extruded sheet-like material was first contacted with either the vertical groove roll or the horizontal groove roll, or was brought into contact with both molding rolls at almost the same time, and the sheet-like material was first contacted with the molding roll. The sheet-like material is sandwiched between the horizontal groove roll and the vertical groove roll until the forming roll, which is first contacted with the sheet-like material, rotates 90 ° (including 0 °) in the roll rotation direction, starting from the point. .. By sandwiching the pressure, the surface shape of the horizontal groove roll is transferred to one surface of the sheet-like material, and the surface shape of the vertical groove roll is transferred to the other surface of the sheet-like material.
(2) Further, starting from the point where the sheet-like material is sandwiched between the horizontal groove roll and the vertical groove roll, the sheet-like material is held by the horizontal groove roll at a holding angle of 90 ° or more and picked up.

In the step (1), the surface shape of the horizontal groove roll is transferred to the resin sheet by sandwiching the sufficiently heated sheet-like material immediately after being extruded at a specific position to form a horizontal handle, and at the same time, the vertical pattern is formed. Since the surface shape of the groove roll is transferred to the resin sheet to shape the vertical handle, it is possible to shape the horizontal handle and the vertical handle having sufficient height.
In the step (2), since the surface on which the arranging pattern of the sheet-like object is formed is held by the lateral groove roll and cooled, the deformation of the formed arranging pattern can be suppressed.

The method for producing a resin sheet of the present invention can be suitably carried out by using, for example, the apparatus shown in FIG. Hereinafter, a case where the method of the present invention is carried out using the apparatus shown in FIG. 1 will be described in detail.
In the apparatus shown in FIG. 1, the three rolls of the first roll 1, the second roll 2, and the third roll 3 are arranged horizontally in order so that the rotation axes 1b, 2b, and 3b of the rolls have the same height. It is provided. The first roll 1 is a vertical groove roll in which a large number of concave grooves 1a continuous in the circumferential direction are formed, and the second roll 2 is a horizontal groove roll in which a large number of concave grooves 2a continuous in the width direction of the roll are formed. The third roll 3 is a mirror surface roll for cooling, and the diameters of the three rolls are the same. FIG. 2A is a schematic view of a vertical groove roll (first roll), FIG. 2B is a schematic view of a horizontal groove roll (second roll), and FIG. 3 is a schematic view of a groove formed on the roll surface. Is shown.

In FIG. 1, 1 is the first roll, 1a is the vertical groove, 1b is the rotation axis of the first roll, 2 is the second roll, 2a is the horizontal groove, and 2b is the rotation axis of the second roll. 3 is the 3rd roll 3, 3b is the rotation axis of the 3rd roll, 4 is the T die, 5 is the extruder, 6 is the sheet, 7 is the bank, and 9 is the sheet. Indicates a point where the sheet-like material is sandwiched between the horizontal groove roll and the vertical groove roll, respectively (the same applies in the following figure). Further, in FIG. 2A, 8a indicates a mountain portion of a vertical groove, in FIG. 2B, 8b indicates a mountain portion of a horizontal groove, and in FIG. 3, 8 indicates a generic name of the mountain portion.

In the method using the apparatus of the embodiment shown in FIG. 1, the thermoplastic resin is supplied to the extruder, melt-kneaded, and then the thermoplastic resin is extruded downward from the T die 4 in the form of a sheet, and the extruded sheet-like material 6 is used. By passing through the gap between the two rolls of the first roll 1 and the second roll 2 and pressing the plastic, the surface shapes of the respective rolls of the first roll and the second roll are transferred, and further, the surface shape of each roll is transferred to the second roll 2. A resin sheet is manufactured by picking up along the third roll 3 and then picking up along the third roll 3.

The melting temperature (extrusion temperature) of the thermoplastic resin constituting the sheet-like material is preferably Tg + 80 ° C. to Tg + 170 ° C. with respect to the glass transition temperature (Tg) of the thermoplastic resin constituting the sheet-like material, and is Tg + 90. It is more preferably ° C. to Tg + 160 ° C., and even more preferably Tg + 100 ° C. to Tg + 150 ° C. When the melting temperature is in the above range, the thermoplastic resin is sufficiently melt-kneaded, and the viscosity range is suitable for roll molding, which is preferable. For example, when the thermoplastic resin constituting the sheet-like material is a methyl methacrylate / styrene copolymer resin having a glass transition temperature of 103 ° C., the extruded resin temperature is preferably in the range of 183 ° C. or higher and 273 ° C. or lower, preferably 193. It is more preferably in the range of ° C. or higher and 263 ° C. or lower, and further preferably in the range of 203 ° C. or higher and 253 ° C. or lower.

The glass transition temperature is described in JIS K7121 (1987), "When the glass transition temperature is measured after a certain heat treatment" (the heating rate and the cooling rate in adjusting the state of the test piece are both 10 ° C./ The intermediate point glass transition temperature measured based on the DSC curve obtained at a heating rate of 10 ° C./min using a heat flow flux differential scanning calorific value measuring device (hereinafter referred to as a DSC device). Is the glass transition temperature in the present invention.

In the method using a device in which the rotation shafts of the first roll and the rotation shafts of the second roll are located at the same height as shown in FIG. 1, first, the extruded sheet-like material 6 is placed on one of the molding rolls. That is, either the first roll or the second roll is brought into contact first, or both forming rolls, that is, the first roll and the second roll are brought into contact with each other at almost the same time. In this case, the sheet-like material 6 can be brought into contact with the first roll first, the second roll can be brought into contact with the first roll, or the first roll and the second roll can be brought into contact with each other at the same time. As shown in FIGS. 1 and 6, it is preferable to make the resin reservoir 7, the so-called bank 7, after the sheet-like material 6 is brought into contact with the molding roll, because it facilitates the production of a resin sheet having a uniform thickness. However, in FIG. 1, although the bank 7 is formed on the first roll side, it can also be formed on the second roll side. The bank can be formed by adjusting the discharge amount of the resin. Further, the bank is formed on the roll side facing the roll that first contacts the T-die by extruding the sheet-like material after adjusting the discharge amount of the resin. Therefore, when forming a bank on the first roll side, the resin discharge amount is adjusted, the position of the roll is moved if necessary, and the sheet-like material is first brought into contact with the second roll side. good.

The lattice pattern is formed by bringing the sheet-like material 6 into contact with the forming roll, and then sandwiching the sheet-like material 6 between the first roll 1 (vertical groove roll) and the second roll 2 (horizontal groove roll). The horizontal pattern (surface shape of the horizontal groove roll) is transferred to the surface of the sheet-like material 6 on the second roll side, and at the same time, the vertical pattern (surface shape of the vertical groove roll) is transferred to the surface of the sheet-like material 6 on the first roll side. By doing so. The resin sheet obtained by the above operation has a vertical pattern on one surface and a horizontal pattern on the other surface, and when viewed from the surface, the vertical and horizontal patterns on the front and back overlap, and the resin sheet looks like a checkered glass-like lattice pattern. ..

The pressing force of the sheet-like material 6 by the first roll 1 and the second roll 2 needs to be performed as follows. Starting from the point where the sheet-like material first contacts the molding roll, the sheet-like material rotates 90 ° (including 0 °) in the roll rotation direction until the molding roll that the sheet-like material first contacts comes into contact with the molding roll. Is sandwiched between the horizontal groove roll and the vertical groove roll. In the case of the device of the embodiment shown in FIG. 1, since the rotation shaft 1a of the first roll 1 and the rotation shaft 2a of the second roll 2 are located at the same height, the sheet-like object 6 is the first roll 1 or the first roll 1. 0 to 0 starting from the point where the roll first contacted with the sheet-like material 6 first contacts in the roll rotation direction after contacting the second roll 2 or contacting the first roll 1 and the second roll 2 almost at the same time. It is done until it is rotated by 10 °. In this way, if the roll that the sheet-like object 6 first contacts is pressed before rotating 10 ° in the roll rotation circumferential direction starting from the contact point 9, the sheet-like object 6 is cooled too much. Since there is no handle, a handle of a desired height can be easily shaped. When the bank 7 is formed on the first roll as shown in FIG. 6, the point 9 at which the sheet-like material 6 first contacts the first roll is the uppermost point where the sheet-like object 6 first contacts the first roll. do.

On the other hand, as shown in FIG. 4, when the rotating shaft 1b of the first roll 1 is located above the rotating shaft 2b of the second roll 2, the sheet-like object 6 first comes into contact with the first roll 9 It is necessary to sandwich the sheet-like object 6 between the second roll 2 and the first roll 1 until the first roll rotates 90 ° in the roll rotation circumferential direction with the above as a starting point. If the first roll 1 is rotated by more than 90 ° in the circumferential direction of rotation and then pressed, the sheet-like material 6 may be too cooled to form a handle having a desired height. From this point of view, it is preferable to hold the pressure while the first roll rotates by 80 ° in the roll rotation circumferential direction, more preferably 60 °, still more preferably 30 °, and particularly preferably 10 °.

Further, as shown in FIG. 5, when the rotation shaft 1b of the first roll 1 is located below the rotation shaft 2b of the second roll 2, the starting point is the point 9 where the sheet-like object 6 first comes into contact with the second roll. Therefore, it is necessary to hold the sheet-like material between the second roll 2 and the first roll 1 until the second roll rotates 90 ° in the roll rotation circumferential direction. If the second roll 2 is rotated by more than 90 ° in the circumferential direction of rotation and then pressed, the sheet-like material 6 may be too cooled to form a handle having a desired height. From this point of view, the pressure is preferably sandwiched until the second roll rotates 80 ° in the roll rotation circumferential direction, more preferably 60 °, still more preferably 30 °, and particularly preferably 10 °.

In the method of the present invention, as described above, the sheet-like material is sandwiched between the second roll (horizontal groove roll) and the first roll (vertical groove roll) to form a molding roll composed of a vertical groove roll and a horizontal groove roll. The surface shape is transferred to the sheet-like material. In this case, it is preferable that the linear pressure due to the pinching pressure on the resin sheet is 5 N / cm or more. When the linear pressure satisfies the above, it becomes easy to obtain the desired handle height of the checker sheet. From this point of view, the linear pressure is more preferably 20 N / cm or more, still more preferably 50 N / cm or more. The upper limit of the linear pressure is preferably about 400 N / cm, more preferably 300 N / cm.
The linear pressure means a force (N) per 1 cm in the roll length direction when a pair of rolls are pressed against each other, and the sheet-like material is subjected to the first roll (vertical groove roll) and the second roll (horizontal groove). It is determined by the pressure when sandwiching with the roll).

The sheet-like material 6 discharged from the T-die 4 is sandwiched between molding rolls (vertical groove rolls, horizontal groove rolls), picked up in a predetermined direction, and cooled to form a horizontal groove roll on one surface of the sheet-like material. The surface shape is transferred and the surface shape of the flute roll is transferred to the other surface of the sheet-like material.

The sheet-like material 6 is cooled by coming into contact with each roll. Therefore, any or all of the molding rolls may be used as cooling rolls. When further rolls are used in the subsequent step of the molding roll, it is preferable that those rolls are also cooling rolls. The cooling mechanism of each roll is not particularly limited, and examples thereof include a roll having a double structure of an inner cylinder and an outer cylinder, and a cooling solvent is passed between them to cool the roll surface.

The temperature of the molding rolls (first roll, second roll) is preferably Tg −70 ° C. to Tg + 20 ° C., more preferably Tg-60 ° C. to Tg + 10 ° C., relative to the glass transition temperature (Tg) of the thermoplastic resin. More preferably, Tg-50 ° C to Tg + 0 ° C. When the surface temperature of the roll is within the above range, it becomes easy to manufacture a checker sheet having both a good groove shape shaping rate and a grid pattern linearity. For example, when the thermoplastic resin constituting the sheet-like material is a methyl methacrylate / styrene copolymer resin having a glass transition temperature of 103 ° C., the roll surface temperature is preferably 33 to 123 ° C., preferably 43 to 113 ° C. More preferably, it is more preferably 53 to 103 ° C.

In the method of the present invention, after the sheet-like material is sandwiched between the horizontal groove roll and the vertical groove roll, as shown in FIGS. 1, 4, and 5, the sheet-like material 6 starts from the pressed point 10. It is necessary to hold the second roll 2 (horizontal groove roll) with a holding angle of 90 ° or more and pick it up. If the hugging angle is less than 90 °, the surface of the sheet-like object 6 on which the arranging pattern is formed becomes insufficiently cooled, the deformation of the arranging pattern cannot be suppressed to a small extent, and the linearity of the arranging pattern may be lost. From this point of view, it is preferable that the holding angle is 100 ° or more, and more preferably 120 ° or more. The upper limit of the holding angle is preferably 180 °, more preferably 150 °. The holding angle can be adjusted by changing the height of the roll shafts of the second roll and the third roll and changing the distance between the rolls. The pinched point 10 exists on a line connecting the rotation axis of the first roll and the rotation axis of the second roll with a straight line.

After the sheet-like material 6 is held by the second roll 2 and picked up, the surface temperature of the sheet-like material 6 on the surface side in contact with the first roll at the point where the sheet-like material separates from the second roll is the surface temperature of the sheet-like material. The temperature is preferably Tg + 45 ° C. to Tg + 85 ° C., more preferably Tg + 50 ° C. to Tg + 80 ° C., and even more preferably Tg + 60 ° C. to Tg + 70 ° C. with respect to the glass transition temperature (Tg) of the constituent thermoplastic resin. .. If the temperature at the point where the sheet-like material separates from the second roll is within the above range, the sheet-like material is appropriately cooled by the first roll and the second roll, so that the surface of the lateral groove roll is on one surface of the sheet-like material. The shape is transferred and the surface shape of the flute roll is transferred to the other surface of the sheet-like material, so that the handle height of the sheet-like material can be set to a suitable value. For example, when the thermoplastic resin constituting the sheet-like material is a methyl methacrylate / styrene copolymer resin having a glass transition temperature of 103 ° C., the extruded resin temperature is preferably in the range of 148 ° C. or higher and 188 ° C. or lower, preferably 153 ° C. It is more preferably in the range of ° C. or higher and 183 ° C. or lower, and further preferably in the range of 163 ° C. or higher and 173 ° C. or lower. The surface temperature of the sheet-like object 6 can be measured by a non-contact infrared radiation thermometer or the like.

Since the third roll 3 is a mirror surface roll for the purpose of cooling and it is not necessary to press the sheet-like object between the second roll 2 and the third roll 3, the third roll 3 is installed separately from the second roll 2. It is preferable to do so. Specifically, it is preferable that the distance between the roll surface of the second roll and the roll surface of the third roll is 30 to 300 mm.

The pick-up speed is preferably 0.1 to 10 m / min, more preferably 0.2 to 5 m / min. When the take-up speed is within the above range, it becomes easy to suitably shape the vertical groove and the horizontal groove of the roll on the sheet-like material.

As the thermoplastic resin used in the method of the present invention, a resin corresponding to "transparent plastic" described in JIS K7361 (1997) is preferably used. Specific examples of the thermoplastic resin include styrene resin, propylene resin, acrylic resin, carbonate resin, thermoplastic ester resin, and cyclic olefin resin.

Among these, the resin corresponding to the "transparent plastic" used in the present invention is the total light transmittance measured by molding it into a flat plate having a smooth surface with a thickness of 2 mm (JIS K7136 (2000)). ) Is 65% or more, and haze (according to JIS K7136 (2000)), which is an index of cloudiness, is preferably 15% or less. From the viewpoint of further excellent transparency, the total light transmittance of the thermoplastic resin used in the present invention is preferably 75% or more, more preferably 85% or more, further preferably 90% or more, and haze 12 % Or less is preferable, 10% or less is more preferable, 5% or less is further preferable, and 3% or less is most preferable. In general, even with the same type of thermoplastic resin, the thicker the thickness, the smaller the total light transmittance and the larger the haze. When two or more types of thermoplastic resins are used in combination, it is preferable that the total light transmittance and the haze of the mixed resin satisfy the above ranges.

The styrene-based resin is a styrene polymer, a styrene copolymer having a styrene-based unit of more than 50 mol% and other comonomer-based units of less than 50 mol%, and a mixture of two or more of these. Examples of the styrene-based resin include polystyrene, AS resin, ABS resin, methyl methacrylate-styrene copolymer having a unit based on styrene exceeding 50 mol%, and styrene-diene block copolymer.

Examples of the propylene resin include polypropylene, a copolymer of a propylene component and another polymerizable monomer component, a mixture of the propylene (co) polymer and another polymer, and the like. Specific examples thereof include a propylene homopolymer (h-PP), a propylene-ethylene random copolymer and a propylene-ethylene-butene random copolymer (r-PP). The polypropylene resin has a propylene-based unit or propylene component content of more than 50 mol%, preferably 70 mol% or more, and particularly preferably 80 mol% or more.

The acrylic resin is a homopolymer of an acrylic acid alkyl ester and / or a methacrylic acid alkyl ester (collectively referred to as (meth) acrylic acid ester below) or a combination of (meth) acrylic acid esters. Polymers, or (meth) acrylic acid ester-based copolymers in which the unit based on (meth) acrylic acid ester is greater than 50 mol% and the unit based on other comonomer is less than 50 mol%, and two or more of these. It is a mixture or the like. In addition, (meth) acrylic acid is a concept including acrylic acid and methacrylic acid, and means one or both of them.

Examples of the homopolymer or copolymer of the (meth) acrylic acid ester include polymethylmethacrylate, ethylpolymethacrylate, propylpolymethacrylate, butylpolymethacrylate, methylpolyacrylate, ethyl polyacrylate, and the like. Examples thereof include a methyl methacrylate-ethyl methacrylate copolymer, a methyl methacrylate-butyl methacrylate copolymer, and a methyl methacrylate-ethyl acrylate copolymer. Of these, polymethyl methacrylate, methyl polyacrylate, methyl methacrylate-ethyl methacrylate copolymer, or methyl methacrylate-ethyl acrylate copolymer is preferable, and polymethyl methacrylate is more preferable.

Examples of the (meth) acrylate-based copolymer include a methyl methacrylate-styrene-butylene copolymer, a methyl (meth) acrylate-styrene copolymer, and an ethyl (meth) acrylate-styrene copolymer. , Or methyl methacrylate-acrylonitrile-butadiene-styrene copolymer and the like. Of these, a methyl methacrylate-styrene-butylene copolymer or a methyl methacrylate-styrene copolymer is preferable.

Examples of the carbonate resin include bisphenol A (4,4'-dihydroxydiphenyl-2,2-propane) polycarbonate, bisphenol F (4,4'-dihydroxydiphenyl-2,2-methane) polycarbonate, and bisphenol S (4). , 4'-Dihydroxydiphenylsulfone) polycarbonate, 2,2-bis (4-dihydroxyhexyl) propane) polycarbonate and the like. Of these, an optical grade polycarbonate resin is particularly preferable.

Examples of the thermoplastic ester resin include aromatic ring-containing polyesters (for example, polyethylene terephthalate, polybutylene terephthalate, polycyclohexanedimethylene terephthalate and polyethylene naphthalate) and aliphatic polyesters (for example, polybutylene adipate, polyethylene adipate and poly-ε-caprolactone). Can be mentioned. As the polyethylene terephthalate, amorphous polyethylene terephthalate (A-PET) having excellent transparency is preferably used.

Examples of the cyclic olefin resin include homopolymers of cyclic olefins, copolymers of cyclic olefins, copolymers of cyclic olefins with ethylene and α-olefins, and mixtures of two or more of these. Examples of the cyclic olefin polymer include the trade name "Apel" or "Topus" of Mitsui Chemicals, Inc., or the trade name "Zeonex" or "Zeonoa" of Zeon Corporation.

The thermoplastic resin used in the method of the present invention may be used alone or in combination of two or more, but is preferably used alone. In the resin sheet obtained by the production method of the present invention, in order for the lattice pattern to appear, it is necessary that the pattern formed on the back surface can be seen through the front surface. Therefore, from the viewpoint of maintaining the transparency of the resin sheet, when two or more kinds of the above-mentioned thermoplastic resins are mixed and used, or the above-mentioned thermoplastic resins are mixed with other thermoplastic resins within a range that does not impair the object of the present invention. When mixed and used, it is preferable that the refractive electrodes of the thermoplastic resins used are close to or equal to each other.

Among the above thermoplastic resins, any resin selected from styrene resin, acrylic resin, and carbonate resin is preferable from the viewpoint of transparency, processability, and cost, and styrene resin or acrylic. Any of the based resins is more preferable.

In the method of the present invention, various additives can be added to the thermoplastic resin as long as the transparency is not impaired. Examples of such additives include antioxidants, ultraviolet inhibitors, antistatic agents, flame retardants, metal deactivators, pigments, dyes and the like.

As the extruder 5 used in the method of the present invention, any of a single-screw type, a bi-screw type, and a multi-screw type with two or more shafts may be used. It is preferable to provide a vent in order to remove oligomers during polymerization, small molecule compounds generated during molding, oxygen and water dissolved in the molding machine, and the like. The degree of vacuum of the vent is preferably 500 hectopascals or less, and more preferably 200 hectopascals or less. From the viewpoint of thickness accuracy and shaping of fine uneven shape, it is preferable to provide a gear pump in order to quantitatively discharge the melt-kneaded material. A multi-layer extruder can be provided when the surface of the thermoplastic resin sheet is multi-layered for the purpose of imparting functions such as ultraviolet absorption and antistatic. In the case of multi-layering, either the feed block method or the multi-manifold method may be used. The multi-manifold die is a T-die having a plurality of manifolds inside and capable of merging the molten resins extruded from each manifold in a laminated state and discharging them from the die. Instead of using the multi-manifold, the molten resin attached between each extruder and the T-die and extruded from each extruder is laminated and merged as described in the direction of Japanese Patent Application Laid-Open No. 55-117636. It is also possible to use a device called a feed block that is made to have a multi-layer structure. As the T-die, it is preferable to use the choke bar method in order to ensure stability during continuous production.

In the method of the present invention, the thickness of the resin sheet is preferably 2 mm or more and 10 mm or less. When the thickness is within the above range, there is no risk of the impact resistance being lowered or the resin sheet being bent, and it is preferable because it is easy to roll and is excellent in workability. From the viewpoint of impact resistance and prevention of bending, the thickness of the resin sheet is more preferably 3 mm or more, and further preferably 3.5 mm or more. On the other hand, from the viewpoint of processability, the thickness of the resin sheet is more preferably 8 mm or less, and further preferably 6 mm or less. The thickness of the resin sheet is the maximum thickness in the cross section of the resin sheet measured by a caliper or the like.

The groove depth H of the concave groove of the molding roll is preferably 300 μm or more. When the groove depth H satisfies the above, the height of the transferred pattern becomes sufficient to form a resin sheet having a vivid lattice pattern, which is preferable. From the above viewpoint, the groove depth H of the concave groove is more preferably 500 μm or more. On the other hand, from the viewpoint of ease of shaping the groove depth, the upper limit of the groove depth H is preferably 1000 μm, more preferably 800 μm. The groove depth H of the concave groove of the molding roll means the groove depth of both the vertical groove roll and the horizontal groove roll. The groove depth H of the concave groove of the molding roll can be measured by the following method. First, the concave groove of the molding roll is molded with a silicone resin, the cross section of the mold is enlarged with a microscope or the like, and a photograph is taken to obtain an enlarged photograph. Next, with respect to the obtained enlarged photograph, a point corresponding to the tip of the mountain portion 8 of the roll and a point corresponding to the tip of the mountain portion 8 of the adjacent roll are connected by a straight line. Then, in consideration of the magnification, the point where the groove depth of the concave groove between the point corresponding to the tip of the mountain portion 8 of the roll and the point corresponding to the tip of the mountain portion 8 of the adjacent roll becomes the deepest. Let the length of the line segment intersecting the straight line at right angles be the groove depth H of the concave groove of the forming roll.

The diameter of the molding roll is preferably 100 to 1000 mm. When the lower limit of the diameter satisfies the above, the possibility that the cooling capacity of the roll is lowered is suppressed, and the productivity is not lowered, which is preferable. On the other hand, when the upper limit of the diameter satisfies the above, it is preferable because the groove processing of the roll becomes easy and the workability in the production of the resin sheet is also excellent. From this point of view, the diameter is more preferably 140 to 700 mm, still more preferably 160 to 500 mm.

It is preferable that the diameters of the first roll, the second roll, and the third roll are the same because it is easy to manufacture the resin sheet, but different diameters can be used.

In the method of the present invention, it is preferable that the pattern formed on the resin sheet is clearly visible. For that purpose, it is preferable that the width of the mountain portion at the boundary between the concave grooves formed on the molding roll is 0.3 to 3 mm, which is 0.05 mm below the tip of the mountain portion. When the width satisfies the above range, the strength of the mountain portion of the mold is lowered and there is no possibility of cracking or chipping, and there is no possibility that the concave groove becomes unclear, which is preferable. From this point of view, the width of the mountain portion is more preferably 0.4 to 2.5 mm, still more preferably 0.5 to 2 mm. The width of the mountain portion 0.05 mm below the tip of the mountain portion can be measured by the following method. First, the roll is molded with a silicone resin, and the cross section of the mold is enlarged with a microscope or the like to obtain an enlarged photograph. Next, for the concave groove of any molding roll in the obtained enlarged photograph, the point where the groove depth is the deepest and the point where the adjacent groove depth is the deepest are connected by a straight line A, and the concave groove and the groove are connected to each other. A straight line B that intersects the straight line A at a right angle is drawn from the tip of the mountain portion of the boundary with the adjacent concave groove. Then, after considering the magnification, it can be obtained by measuring the width of the mountain portion parallel to the straight line A at a position 0.05 mm below the tip of the mountain portion.

Further, the pitch P (distance between the peaks) of the concave grooves of the horizontal groove roll and the vertical groove roll is preferably 5 to 30 mm. When the above range is satisfied, the concave groove of the molding roll can be easily formed on the resin sheet, and it can be suitably used as a substitute for the checker glass, which is preferable. From the above viewpoint, the pitch P of the concave groove is more preferably 8 to 25 mm, and further preferably 10 to 20 mm. In the case of manufacturing as a substitute for checker glass, it is preferable to increase the pitch of the vertical grooves by 10 to 30% from the pitch of the horizontal grooves in consideration of the elongation of the sheet in the extrusion direction at the time of manufacturing. Further, when manufactured as a substitute for the checker glass, it is preferable that the pitch P in each of the horizontal groove roll and the vertical groove roll is constant. The pitch P is formed by molding the concave groove 8 of the molding roll with a silicone resin, magnifying the cross section of the mold with a microscope or the like, and taking a picture. Can be determined by measuring.

Whether or not the desired handle height is formed on the resin sheet is evaluated by the shaping rate. The shaping rate is preferably 60% or more, more preferably 65% or more. When the shaping rate satisfies the above, the lattice pattern becomes clear and it is easy to obtain a resin sheet having an excellent appearance.

The shaping rate of the resin sheet is obtained by measuring the handle height and roll groove depth of the resin sheet and substituting the measured values into the following equation (1).
The handle height of the resin sheet is obtained by the following method. The cross section of the sheet is photographed with a microscope or the like to obtain an enlarged photograph. Next, with respect to the obtained enlarged photograph, the deepest points of the valleys at both ends of any Kamaboko shape in the sheet cross section are connected by a straight line A, and a straight line B orthogonal to the straight line A downward from the apex of the Kamaboko shape is drawn. Pull. Then, it can be obtained by measuring the length from the apex of the mountain part of the Kamaboko shape on the straight line B to the intersection with the straight line A in consideration of the magnification.
The groove depth of the roll can be measured by the above method.
Shape rate [%] = (resin sheet handle height [μm] ÷ roll groove depth [μm]) x 100
... (1)

The linearity of the lattice pattern of the resin sheet is evaluated by measuring the deviation of the horizontal pattern. In order to use a resin checker sheet as a substitute for the checker glass, it is preferable that the size of the lateral groove deviation is 2 mm or less in the test piece of the resin sheet of 300 mm × 300 mm.

The arrogant deviation is measured as follows. One part of one end of the horizontal handle of the test piece is arbitrarily determined, and three parts are further determined at equal intervals. A straight line is drawn, the maximum difference between the straight line and the actual arrogance is measured, and the maximum value of the measured values at the four points is defined as the deviation of the arrogance.

Next, the present invention will be described in more detail with reference to Examples and Comparative Examples. However, the present invention is not limited to the examples.

Example 1
An extruder in which a T-die having a lip width (w) of 300 mm (lip gap of T-die = 5.0 mm, parallel land length of lip portion = 5.0 mm) was attached to a single-screw extruder having an inner diameter of 65 mm was used.
The first roll (vertical groove roll), the second roll (horizontal groove roll), and the third roll (mirror surface roll) are arranged in this order so that the rotation axes of the rolls are at the same height as shown in FIG. bottom. The diameters of the three rolls were all 195 mm, the widths were all 700 mm, the material was iron, and a flow path for controlling the oil temperature was provided inside the rolls.
The first roll (vertical groove roll) is formed with a vertical groove having a groove depth of 500 μm, a width of the mountain portion 0.05 mm below the tip of the mountain portion of 1.84 mm, and a pitch of P15 mm. In the horizontal groove roll), a horizontal groove having a groove depth H of 500 μm, a width of the mountain portion 0.05 mm below the tip of the mountain portion was 0.66 mm, and a pitch of 15 mm was formed.
The third roll was arranged so that the distance between the roll surface of the second roll and the roll surface of the third roll was 65 mm.
For the groove depth of the concave groove, the width of the mountain portion 0.05 mm below the tip of the mountain portion, and the pitch P, each of the vertical groove rolls and the horizontal groove rolls was measured by the above method at 5 points at random, and the arithmetic was performed. The average value was adopted.

The raw material is Estyrene MS resin (methylmethacrylate / styrene copolymer resin) "MS-600" (glass transition temperature Tg = 103 ° C., total light transmittance 90%, haze = 2.0, refractive index) manufactured by Nippon Steel & Sumikin Chemical Co., Ltd. 1.53) was used.

The extruded resin temperature is set to 250 ° C., the resin is extruded into a sheet from the T die at a discharge rate of 45 kg / h, and the extruded sheet is brought into contact with the second roll to form a bank on the first roll side. By sandwiching between the 1st roll and the 2nd roll, a vertical groove is formed on the 1st roll side of the sheet-like material, a horizontal groove is formed on the 2nd roll side, and then the 2nd roll and then the 3rd roll are pulled. It was taken and a resin sheet was obtained. The take-up speed was 0.6 m / min, and a resin sheet having a sheet width of 300 mm and a sheet thickness of 4 mm was obtained. The roll temperature was adjusted separately using three oil temperature control pumps (first roll 60 ° C., second roll 70 ° C., third roll 75 ° C.). The surface temperature of the surface side of the sheet-like material in contact with the first roll at the point where the sheet-like material was separated from the second roll was 168 ° C.

The pinching pressure between the second roll and the first roll was performed from the point where the sheet-like material was brought into contact with the second roll until the second roll was rotated by 10 ° in the roll rotation direction. Further, the cooling of the sheet-like material was performed by taking the sheet-like material to the second roll at a holding angle of 150 °, starting from the point where the sheet-like material was pressed.

[Comparative Example 1]
In Comparative Example 1, a resin sheet was produced in the same manner as in Example 1 except that the first roll was changed to a horizontal groove roll and the second roll was changed to a vertical groove roll.

[Comparative Example 2]
In Comparative Example 2, the first roll 1 was a mirror surface roll, the second roll 2 was a horizontal groove roll, the third roll 3 was changed to a vertical groove roll, and the pressure was sandwiched between the second roll and the third roll. A resin sheet was produced in the same manner as in Example 1.

[Comparative Example 3]
In Comparative Example 3, the comparison was made except that the first roll 1 was a mirror surface roll, the second roll 2 was a vertical groove roll, the third roll 3 was changed to a horizontal groove roll, and the pressure was sandwiched between the second roll and the third roll. A resin sheet was produced in the same manner as in Example 2.

The shapeability and arrogant linearity of the lattice-patterned resin sheets obtained in Example 1 and Comparative Examples 1 to 3 were measured and evaluated. The results are shown in Table 1.

<Formability>
The handle height of the resin sheet was determined as follows. A test piece having a length (corresponding to the roll circumferential direction) of 300 mm and a width (corresponding to the roll width direction) of 300 mm was cut out from the obtained resin sheet, and the cross section of the test piece was photographed with a microscope to obtain an enlarged photograph. With respect to the obtained enlarged photograph, the deepest points of the valleys at both ends of an arbitrary sword-shaped cross section are connected by a straight line A, which is a straight line parallel to the straight line A and makes point contact with the ridges of the sword-shaped. A point was defined as the apex of the gem shape, and a straight line B intersecting the straight line A was drawn from the apex of the gauze shape in the downward direction in the thickness direction of the resin sheet. Then, the handle height of the resin sheet was obtained by measuring the length from the apex of the Kamaboko shape on the straight line B to the intersection with the straight line A in consideration of the magnification. The above operation was randomly measured at four points for each of the vertical and horizontal patterns, and the arithmetic mean of the measured values was taken as the height of each of the vertical and horizontal patterns. The groove depth H of the roll was measured by the above method at four points at equal intervals for each of the vertical groove roll and the horizontal groove roll, and the arithmetic mean value was taken as the groove height of the roll. By substituting the handle height of the resin sheet obtained as described above and the groove height of the roll into the following equation (1), the shaping ratios of the vertical handle and the horizontal handle of the resin sheet are obtained, and the following evaluation criteria are used. The formability was evaluated in.
Shape rate [%] = (resin sheet handle height [μm] ÷ roll groove depth [μm]) x 100
... (1)

Evaluation criteria for formability ◯: The formability rate is 60% or more.
X: Shape rate is less than 60%

<Linearity of arrogance>
For the deviation of the arranging pattern, one end of the arranging part of the test piece of 300 mm × 300 mm is arbitrarily determined, and three points are further determined at intervals of 60 mm. A straight line orthogonal to the extrusion direction was drawn up to the end, the maximum difference between the straight line and the actual arranging pattern was measured, and the maximum value of the measured values at the four points was defined as the arranging pattern deviation.

The linearity was evaluated according to the following criteria.
◯: The deviation of the arrogant pattern is 2 mm or less.
X: The deviation of the arrogant pattern is more than 2 mm.

1 1st roll 1a Vertical groove 1b 1st roll rotation shaft 2 2nd roll 2a Horizontal groove 2b 2nd roll rotation shaft 3 3rd roll 3b 3rd roll rotation shaft 4 T die 5 extruder 6 sheet-like material 7 bank 8a Vertical groove ridge 8b Horizontal groove ridge 8 General term for groove ridge 9 Point where the sheet-like material first came into contact with the forming roll 10 Point where the sheet-like material was pressed between the horizontal groove roll and the vertical groove roll P pitch H groove depth

Claims (7)

In a method for producing a resin sheet, in which a molten thermoplastic resin is extruded into a sheet, and the extruded sheet is taken up and the surface shape of a molding roll is transferred to both surfaces of the sheet.
The thickness of the resin sheet is 3 mm or more, and the resin sheet has a thickness of 3 mm or more.
The forming roll is composed of a vertical groove roll having a large number of concave grooves continuous in the circumferential direction of the roll and a horizontal groove roll having a large number of concave grooves continuous in the width direction of the roll.
The groove depth of the concave groove of the molding roll is 1000 μm or less.
The extruded sheet-like material is first contacted with one molding roll, or both molding rolls are brought into contact with each other at almost the same time, and the sheet-like material is first contacted with the molding roll. By sandwiching the sheet-like material between the horizontal groove roll and the vertical groove roll until the contacted molding roll rotates 90 ° (including 0 °) in the roll rotation direction, a horizontal groove is formed on one surface of the sheet-like material. A resin sheet characterized in that the surface shape of the roll is transferred, the surface shape of the vertical groove roll is transferred to the other surface of the sheet-like material, and the sheet-like material is held by the horizontal groove roll at an angle of 90 ° or more and picked up. Manufacturing method.
The method for producing a resin sheet according to claim 1, wherein the thickness of the resin sheet is 3 mm or more and 10 mm or less.
The method for producing a resin sheet according to claim 1 or 2, wherein the groove depth of the concave groove of the molding roll is 300 μm or more.
The method for producing a resin sheet according to any one of claims 1 to 3, wherein the molding roll has a diameter of 100 to 1000 mm.
The production of the resin sheet according to any one of claims 1 to 4, wherein the width of the mountain portion 0.05 mm below the tip of the mountain portion between the concave grooves of the molding roll is 0.3 to 3 mm. Method.
Claims 1 to 1, characterized in that the linear pressure at the time of transferring the surface shape of the molding roll to the sheet-like material is 5 N / cm or more by sandwiching the sheet-like material between the horizontal groove roll and the vertical groove roll. 5. The method for producing a resin sheet according to any one of 5.
The method for producing a resin sheet according to any one of claims 1 to 6, wherein the thermoplastic resin is a styrene resin or an acrylic resin.

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