WO2010024292A1

WO2010024292A1 - Method for producing resin sheet

Info

Publication number: WO2010024292A1
Application number: PCT/JP2009/064861
Authority: WO
Inventors: 卓弘林; 芳彦佐野
Original assignee: 富士フイルム株式会社
Priority date: 2008-09-01
Filing date: 2009-08-26
Publication date: 2010-03-04
Also published as: JP2010058285A

Abstract

Disclosed is a method for producing a resin sheet wherein the ends of a resin sheet can be cut without generating chips because the opposite ends of a resin sheet are cut using an ultrasonic cutter. Since the resin at the cut portion can be rendered soft by confining the temperature at the cut portion of the resin sheet within a preset temperature range, the sheet can be cut without generating chips even if the sheet has a thickness of 1 mm or more. Even a resin sheet of PMMA can be cut without generating chips.

Description

Manufacturing method of resin sheet

The present invention relates to a method for producing a resin sheet, and more particularly to a method for producing a resin sheet suitable for use in a light guide plate and various optical elements disposed on the back surface of various display devices.

In general, in resin sheet extrusion molding, the molten resin sheet extruded from the T-die is cooled by a cooling roll, and then cooled and solidified by air cooling in a conveying section while being taken up by a take-up roll, and then in a width direction by a cutting machine. And is formed into a sheet shape. The end in the width direction of the sheet thus obtained is likely to be warped, residual distortion, thickness variation, etc. due to the influence of the end. Therefore, the end of the sheet in the width direction is cut to obtain a sheet having a desired width. A shaped molding is obtained. The cut end is turned into crushed waste by a pulverizer and is put into a hopper of an extruder for reuse.

In particular, in the case of extrusion molding of an uneven thickness resin sheet having a large thickness distribution in the width direction, the temperature distribution in the width direction becomes very large, so that the influence of the edge portion is a major cause of warpage. Further, even when the warp is corrected by a heat treatment in a later step, if there is an end portion of the sheet, it is difficult to correct the warp. Therefore, it is necessary to cut the end portion.

When cutting the end, a rotating blade is usually used, but when cutting with a rotating blade, swarf is generated, and this swarf adheres to the product and causes defects. If a laser cutter is used, the generation of chips can be suppressed, but the introduction cost is high, and the laser cutter has a problem in that gas is generated or a sheet burns during cutting.

As a countermeasure, the following Patent Documents 1 to 3 disclose that the cut portion is heated from the outside and cut with a cutter blade or the like. By heating the cut portion, cutting performance was improved, generation of chips and chips by cutting was suppressed, and a good cut processing portion could be obtained.

A water jet is used for cutting the resin. Since the water jet is not affected by heat, the water jet can be used without being distorted or deformed by heat. Moreover, it can cut | disconnect without generation | occurrence | production of a chip.
Japanese Patent Laid-Open No. 1-281896 JP-A-9-85680 JP 2005-305637 A

However, the methods described in Patent Documents 1 to 3 are effective in suppressing the generation of swarf for thin films of 1 mm or less, but they are scraped when cutting with thick sheets of 1 mm or more. Since the amount increases, chips and burrs are likely to occur. For this reason, the generated swarf adheres to the surface of the sheet and causes a surface failure such as a pressing wound, and it is difficult to obtain a good sheet. Although burrs are unlikely to cause a surface failure such as a scratch, it is desirable that they do not exist in the final product form. In particular, in the case of a thick sheet such as PMMA, when it is cut, a crack is generated from the cut portion, and it is difficult to obtain a good sheet. In addition, the water jet has a high introduction cost and running cost, and is difficult to put into practical use.

The present invention has been made in view of such circumstances, and provides a method for producing a resin sheet that can be continuously cut during conveyance without generating chips or burrs even with a thick sheet of 1 mm or more. The purpose is to do.

In order to achieve the above object, the first aspect of the present invention is an extrusion process in which a molten resin is extruded from a die into a sheet, and the extruded resin sheet is sandwiched between a mold roller and a nip roller, and is cooled and solidified. A sheet forming step for forming, a peeling step for peeling the resin sheet from the mold roller, and a cutting step for cutting both ends of the resin sheet having a thickness of 1 mm or more with an ultrasonic cutter along the conveying direction. The temperature of the cut portion of the resin sheet is (Tg−50) ° C. or more and (Tg + 100) ° C. or less when the glass transition temperature of the resin is Tg. A manufacturing method is provided.

According to the first aspect, since both ends of the resin sheet are cut using the ultrasonic cutter, the ends of the resin sheet can be cut without generating chips. Moreover, since the resin of the cut portion can be softened by setting the temperature range of the cut portion of the resin sheet to the above range, even when the thickness of the sheet is 1 mm or more, the sheet can be cut without generating chips. It can be performed. Even a resin sheet such as PMMA can be cut without causing cracks.

According to a second aspect of the present invention, in the first aspect, the blade of the ultrasonic cutter is a single blade, and the blade surface in contact with the product side of the resin sheet of the blade of the ultrasonic cutter is the traveling direction of the resin sheet. It is characterized by being parallel to.

According to the second aspect, by using a single blade as the blade of the ultrasonic cutter, burrs generated when cutting a thick sheet are intensively generated on one side of the cut surface after cutting, and the other side is cut. Generation of burr can be suppressed. Furthermore, by installing a cutter blade so that the blade surface in contact with the product-side surface of the resin sheet is parallel to the resin sheet traveling direction (conveying direction), burrs are generated on the product-side cutting surface. Can be suppressed, and post-processing of burrs becomes unnecessary.

According to a third aspect of the present invention, in the first or second aspect, the resin sheet has a thickness distribution in the width direction, and a difference in thickness between the thickest part and the thinnest part is 0.5 mm or more and 5 mm or less. It is characterized by that.

A sheet having a thickness in the width direction causes a warp due to a large temperature difference between the thickest part and the thinnest part in the cooling process. Therefore, it is important to cut the edge of the sheet in order to suppress or correct the warp. In the present invention, since the end portion can be cut without generating chips, the sheet has a thickness distribution in the width direction, and the difference in thickness between the thickest portion and the thinnest portion is in the above range. Can be carried out particularly effectively for the production of

According to a fourth aspect of the present invention, in the third aspect, the thickness distribution in the sheet width direction has a periodicity of a pitch of 200 mm or more, and a periodic seam is cut along the conveying direction with the ultrasonic cutter. It is characterized by that.

According to the fourth aspect, when the thickness distribution has periodicity, by cutting this periodic shape seam with an ultrasonic cutter, even with respect to the periodic shape seam, without generating chips, Since a sheet | seat can be cut | disconnected, a favorable sheet | seat can be manufactured.

According to a fifth aspect of the present invention, in any one of the first to fourth aspects, the cutting position is detected during conveyance of the resin sheet, the ultrasonic cutter moves following the change of the cutting position, The cutting position is cut.

According to the fifth aspect, when the sheet is meandering during conveyance by detecting the marked cutting position and moving the ultrasonic cutter following the change in the cutting position to cut the predetermined cutting position. However, the sheet can be processed into a desired shape.

The sixth aspect of the present invention is characterized in that, in any one of the first to fifth aspects, the cut portion of the resin sheet is divided into a plurality of times and cut with the ultrasonic cutter.

According to the sixth aspect, since the cut portion of the resin sheet can be cut into a plurality of times, the sheet can be cut even when the thickness of the sheet is thick.

The seventh aspect of the present invention is characterized in that, in any one of the first to sixth aspects, the resin sheet is cut in the width direction by an ultrasonic cutter.

According to the seventh aspect, since the cutting in the width direction of the resin sheet is also performed by the ultrasonic cutter, generation of chips can be suppressed even when cutting in the width direction, and a good sheet is manufactured. Can do.

According to the method for producing a film of the present invention, since cutting is performed using an ultrasonic cutter, generation of chips and burrs can be suppressed even during cutting of a sheet of 1 mm or more, and the film is being conveyed. Can be cut continuously.

FIG. 1 is a process diagram illustrating a flow of a method for producing a resin sheet to which the present invention is applied; FIG. 2 is a conceptual diagram of a resin sheet manufacturing apparatus to which the present invention is applied; FIG. 3A is a cross-sectional view showing an example of the shape of a resin sheet; FIG. 3B is a cross-sectional view showing another example of the shape of the resin sheet; FIG. 4 is a configuration diagram illustrating a sheet forming process, a peeling process, a slow cooling process, and a cutting process of the resin sheet manufacturing apparatus; FIG. 5 is a side view of the mold roller used in the first embodiment.

Hereinafter, preferred embodiments of a method for producing a resin sheet according to the present invention will be described with reference to the accompanying drawings. Hereinafter, an uneven thickness resin sheet having a thickness distribution in the width direction of the resin sheet will be described as an example.

FIG. 1 is an overall process diagram of a method for producing a resin sheet according to the present invention, and FIG. 2 is a conceptual diagram showing an apparatus configuration in each process.

As shown in FIG. 1, the resin sheet manufacturing method of the present invention mainly includes a raw material process 100 for measuring and mixing raw materials, an extrusion process 112 for continuously extruding molten resin into a sheet (band), and extrusion. A sheet forming step 114 for cooling and solidifying the molded resin sheet 14, a peeling step 115 for peeling the resin sheet 14, a slow cooling step 116 for gradually cooling the solidified resin sheet 14, and a predetermined resin sheet 14. A cutting / cutting process 124 for cutting to a size (length / width) and a stacking process 126 for stacking the cut resin sheets 14 are configured.

Hereinafter, the main configuration of the resin sheet manufacturing apparatus to which the present invention is applied will be described with reference to FIG.

As shown in FIG. 2, in the raw material process 100, the raw material resin and additive sent from the raw material silo 128 (or raw material tank) and the additive silo 130 (or additive tank) to the automatic weighing machine 132 are automatically weighed, The raw material resin and the additive are mixed by the mixer 134 so as to have a predetermined ratio.

As the resin material of the raw material resin applied to the present invention, a thermoplastic resin can be used, for example, polymethyl methacrylate resin (PMMA), polycarbonate resin (PC), polystyrene resin (PS), MS resin, AS resin. , Polypropylene resin (PP), polyethylene resin (PE), polyethylene terephthalate resin (PET), polyvinyl chloride resin (PVC), thermoplastic elastomer, or a copolymer thereof, cycloolefin polymer, and the like.

Further, these thermoplastic resins may contain light diffusing particles. Examples of the light diffusing particles include inorganic materials such as silicone, silica, calcium carbonate, barium sulfate, aluminum hydroxide, titanium oxide, glass beads, and calcium silicate. Examples thereof include particles and polymethyl methacrylate particles. When adding scattering particles, first, a master pellet in which scattering particles are added to a raw material resin at a concentration higher than a predetermined concentration is manufactured by a granulator. Next, by suitably adopting the master batch method, the master pellets to which the scattering particles are added at a concentration higher than the predetermined concentration and the base pellets to which the scattering particles are not added are mixed in the mixer 134 at a predetermined ratio. The The same applies when additives other than the scattering particles are added.

The raw material resin appropriately weighed and mixed in the raw material process 100 is sent to the extrusion process 112.

In the extrusion step 112, the raw material resin mixed in the mixer 134 is charged into the extruder 138 through the hopper 136. The raw material resin is melted while being kneaded by the extruder 138. The extruder 138 may be either a single-screw extruder or a multi-screw extruder, and preferably includes a vent function that evacuates the interior of the extruder 138. The raw material resin melted by the extruder 138 is sent to a die 12 (for example, a T die) through a supply pipe 142 by a metering pump 140 such as a screw pump or a gear pump. The resin sheet 14 extruded from the die 12 into a sheet shape is then sent to a sheet forming step 114.

In the sheet forming step 114, the resin sheet 14 extruded from the die 12 is sandwiched between the mold roller 16 and the nip roller 18. The resin sheet 14 is cooled and solidified while being formed into a shape having a thickness distribution in the width direction. The solidified resin sheet 14 is peeled off by the peeling roller 20 (peeling step). The resin sheet 14 that has undergone the sheet forming step 114 is then sent to a slow cooling step 116.

The slow cooling step (or annealing step) 116 is provided to prevent a rapid temperature change of the resin sheet 14 downstream of the peeling roller 20. When a sudden temperature change occurs in the resin sheet 14, for example, the inside of the resin sheet 14 becomes a plastic state despite the fact that the vicinity of the surface of the resin sheet 14 is in an elastic state. The surface shape of the sheet 14 may be deteriorated. Further, when a temperature difference is generated between the front and back surfaces of the resin sheet 14, the resin sheet 14 is likely to warp. In particular, when the resin sheet 14 has a thickness distribution in the width direction as in the sheet cross-sectional shape of FIG. 3A, the temperature distribution in the width direction becomes large, and the resin sheet 14 is likely to warp.

The slow cooling step 116 is provided with a tunnel-like slow cooling zone 154 (or annealing zone) having an inlet and an outlet.

The heating means provided in the first half of the slow cooling zone 154 includes a structure in which air (hot air) whose temperature is controlled from a plurality of nozzles is jetted toward the resin sheet 14, a nichrome wire heater, an infrared heater, a dielectric heating means, etc. Various known means such as a structure for heating the resin sheet 14 can be employed, and the resin sheet can be prevented from being rapidly cooled.

In addition, when the resin sheet 14 is slowly cooled and conveyed, an external force is applied to the resin sheet 14 in the first half of the slow cooling zone 154 so that the resin sheet 14 is not warped. In order to hold, shape holding means (not shown) can be provided.

The resin sheet 14 that has passed through the slow cooling step 116 is sent to the cutting step 124. In the cutting step 124, both edges of the resin sheet 14 are cut by the ultrasonic cutter 174 during conveyance. The resin sheet 14 is molded into a predetermined shape in the sheet molding step 114, but both edge portions of the resin sheet 14 are cut because residual distortion is likely to occur. The cut portions are preferably cut at 20 to 50 mm at both ends of the resin sheet 14.

In particular, when the resin sheet 14 has a thickness distribution in the width direction as in the sheet cross-sectional shape of FIG. 3A, both ends of the resin sheet 14 are thin, so that the thickness of the sheet center is thick. The temperature difference with the part becomes large and causes warping. Therefore, it is necessary to cut both ends of the resin sheet 14. Moreover, since the ultrasonic cutter is used as the cutting means, generation of chips during cutting can be suppressed, and thus a good sheet with less adhesion of impurities to the resin sheet can be manufactured. The surface roughness of the end face of the resin sheet 14 after cutting is preferably Ry ≦ 5 μm, and more preferably Ry ≦ 3 μm.

Also, by marking the cutting position of the resin sheet 14, detecting the cutting position marked during conveyance, the ultrasonic cutter 174 moves following the change of the cutting position and cuts the predetermined cutting position, Even when the resin sheet 14 meanders during conveyance, the sheet can be processed into a desired shape.

As a means for marking the cutting position, a method of forming a concavo-convex shape on the mold roller 16, the nip roller 18, or the peeling roller 20 and transferring it to the resin sheet 14, contacting the roller during contact with the mold roller 16 or nip roller 18 The method of marking by the inkjet etc. from the surface on the opposite side to the surface which is present is mentioned.

At this time, the temperature of the cut portion of the resin sheet is (Tg−50) ° C. or more and (Tg + 100) ° C. or less, more preferably (Tg−30) ° C. or more and (Tg + 50) when the glass transition temperature of the resin is Tg. ) C or less. Since the cut portion of the resin sheet can be softened by cutting the temperature of the cut portion of the resin sheet within the above range, generation of chips can be suppressed.

At this time, the thickness of the cut portion of the resin sheet 14 is preferably 1 mm or more and 5 mm or less, and more preferably 1 mm or more and 3 mm or less. When the thickness of the resin sheet 14 is thick, the cutting part can be cut into a plurality of times. Even if the cut portion of the resin sheet 14 is thick, it can be cut by dividing into a plurality of times.

A part of the cut resin sheet 14 is collected in a collection box 176, and the collected resin is discarded or reused.

Next, the ultrasonic cutter used in the present invention will be described. The ultrasonic cutter is a cutter that can cut by reducing the friction by applying ultrasonic vibration, and heat is applied to the cross section, so that the resin melts and suppresses generation of chips and cuts.

As the cutting condition, the oscillation frequency is preferably 20 kHz or more, more preferably 40 kHz or more. Moreover, it is preferable that an output is 20 W or more, and it is more preferable that it is 50 W or more. If the transport speed of the resin sheet to be cut is too slow, the cut sheet will be re-welded by the heat at the time of cutting, and if it is too early, a good cut surface cannot be obtained, so that it is 1 m / min or more and 20 m / min or less. Preferably there is.

As the material of the ultrasonic cutter, it is preferable that the cut resin does not adhere to the cutter and has a wear resistance that can withstand long-time cutting, such as high speed steel, stainless steel, carbide, diamond. And titanium. In order to improve the wear resistance, the surface may be coated with DLC, SiN, CrN or the like. It can be physically removed with a brush or compressed air so that the cutting waste does not adhere to the blade and affect the processing performance by continuous use.

Also, examples of the shape of the ultrasonic cutter include an oblique blade, a round blade, and a saw blade. Although the cutting edge can be cut with a single blade or a double blade, a single blade is preferable to suppress the generation of burrs on the cut surface on the product side. Moreover, it is preferable to install and cut | disconnect the blade surface which the blade of an ultrasonic cutter touches the product side during cutting | disconnection so that it may become parallel with the advancing direction of a resin sheet. Generation | occurrence | production of the burr | flash of the cut surface of a product side can be suppressed by making the product side surface of a resin sheet and the blade surface of an ultrasonic cutter into parallel. The thickness of the blade of the ultrasonic cutter is preferably 1 mm or less, and more preferably 0.6 mm or less, in order to reduce the amount of shaving during cutting.

Also, since the blade of the ultrasonic cutter has heat due to use, the resin film melts and the cut surface deteriorates, the blade cooling structure is also important. The blade cooling structure is preferably a structure in which air is cooled with compressed air.

Further, the cutting step 124 may include a step of cutting the resin sheet 14 along a direction orthogonal to the conveying direction and cutting it to a predetermined length. 3A and 3B are cross-sectional views showing an example of the resin sheet 14 having a thickness distribution in the width direction. FIG. 3A shows a resin sheet having a thickness distribution in the width direction in which the central part is thick and both ends are thin, and FIG. 3B is a resin sheet having two thick parts in the width direction. Moreover, a thick part is not specifically limited, It can change suitably with manufacturing conditions, and the manufacture of the resin sheet which has three or more places is also possible. In the resin sheet having a thickness distribution in the width direction, the difference in thickness between the thickest part and the thinnest part is preferably 0.5 mm or more and 5 mm or less, more preferably 1 mm or more and 3 mm or less. Moreover, as shown to FIG. 3B, when there are two or more thick parts, it is preferable that the pitch L is 200 mm or more and has periodicity, and more preferably 400 mm or more. Further, the cutting step 124 may include a step of cutting in the conveying direction by the joint 24 having a periodic pitch shape. The resin sheet 14 is cut into individual light guide plates by passing through the cutting step 124. Moreover, the resin sheet does not need to be an uneven thickness resin sheet having a thickness distribution in the width direction, and can be applied to a flat plate.

In order to trim the resin sheet 14 to a predetermined length (cut in a direction perpendicular to the transport direction), it is preferable to use an ultrasonic cutter 174 as in the case of cutting the end of the resin sheet 14. Moreover, it is preferable to also make the temperature of the cutting part of the resin sheet the same temperature as the case where the edge part of a resin sheet is cut | disconnected. By doing in this way, generation | occurence | production of a chip can be suppressed similarly to the case where the edge part of the resin sheet 14 is cut | disconnected, and it can cut | disconnect.

When cutting the resin sheet 14 along the direction orthogonal to the conveyance direction, the ultrasonic cutter is moved in the conveyance direction in synchronization with the traveling speed of the resin sheet 14, thereby cutting the resin sheet 14 while conveying it. It becomes possible. That is, the resin sheet 14 can be trimmed to a predetermined length online.

The cut sheet resin sheet 14 is conveyed to the next processing by a conveyor belt 196 driven by a roller 194 and is not displaced during traveling by the drum-shaped member 192 from the width direction of the resin sheet 14. Is held down.

Also, as for the cutting means for cutting along the transport direction, the ultrasonic cutter 174 can be used as in the case of cutting the end of the resin sheet 14 and cutting perpendicularly to the transport direction.

In the present invention, the cut surface of the resin sheet 14 cut by the ultrasonic cutter 174 has a smooth cut surface, and therefore, it is possible to omit an end face processing step required when used as a light guide plate. Further, by using an ultrasonic cutter for cutting in the width direction (direction perpendicular to the conveying direction), the sheet can be molded without finishing the side surface of the resin sheet.
[Production method of resin sheet]
Next, a method for producing a resin sheet by the resin sheet production line 10 shown in FIG. 4 will be described using an uneven thickness resin sheet as an example.

The sheet-shaped resin sheet 14 extruded from the die 12 is pressed between the mold roller 16 and the nip roller 18 disposed opposite to the mold roller 16, and the uneven-shaped inverted mold on the surface of the mold roller 16 is transferred to the resin sheet 14. Then, the resin sheet 14 is gradually cooled by being wound around a peeling roller 20 disposed opposite to the mold roller 16, and is transported in a state where distortion is removed.

In the production of this resin sheet, the extrusion speed of the resin sheet 14 of the die 12 can be 0.1 to 50 m / min, preferably 0.3 to 30 m / min. Accordingly, the peripheral speed of the mold roller 16 is also substantially matched with this. In addition, it is preferable to control the speed unevenness of each roller within 1% with respect to the set value.

The pressing pressure of the nip roller 18 against the mold roller 16 should be 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). It is preferably 0 to 100 kN / m (kgf / cm).

The resin sheet 14 peeled from the mold roller 16 by the peeling roller 20 is gradually cooled in the slow cooling zone 154. The cooled resin sheet 14 is heated by the heating device 22 from the lower side of the resin sheet 14 (the side where the uneven resin sheet protrusion is not formed) as necessary, and is a cut portion of the resin sheet 14. The end portion is softened and the generation of chips when cut by the ultrasonic cutter 174 is suppressed. In addition, even after cutting the end portion of the resin sheet 14, when the resin sheet 14 is heated by the heating device 22 to be cut in the conveyance direction of the resin sheet 14, in the case of being cut in a direction orthogonal to the conveyance direction. Can be cut while suppressing the generation of chips.

The features of the present invention will be specifically described below with reference to examples and comparative examples. In the following examples, materials, processing contents, processing procedures, and the like can be appropriately changed without departing from the gist of the present invention. Therefore, the scope of the present invention should not be construed as being limited by the specific examples shown below.
[Example 1]
The resin sheet was manufactured using the apparatus shown in FIG.

PMMA (manufactured by Asahi Kasei Co., Ltd., 80NH, glass transition temperature 110 ° C.) is extruded from a T-die set at a temperature of 255 ° C., formed into a sheet through a nip roll, a mold roll having a shape as shown in FIG. The thin portion of the resin sheet is heated with a far-infrared heater in the conveying section and gradually cooled while uniforming the temperature distribution in the width direction, both ends of the resin sheet are cut, and the cross-sectional shape in the sheet width direction is as shown in FIG. A resin sheet having a width of 594 mm, a thinnest part of 2.0 mm, and a thickest part of 3.8 mm was obtained.

In the extrusion process, the lip width of the die is 660 mm, the lip opening (lip clearance) is 4 mm, and the flow rate distribution in the width direction is substantially proportional to the clearance amount between the nip roll and the mold roll at each position. Adjusted with chalk bar.

In the sheet forming process, the surface temperature of the nip roll, the mold roll, and the release roll are 70 ° C., 75 ° C., and 80 ° C., respectively, the roll diameter of the nip roll is φ350 mm, the roll diameter of the release roll is φ500 mm, and the thick roll forming part of the mold roll The roll diameter was 345.6 mm, the roll diameter of the thin-wall forming part was 349.4 mm, and the roll diameter (outermost diameter) of the resin sheet and the non-contact part was 350 mm. The clearance between the nip roll and the mold roll is 3.90 mm at the maximum part in the center of the roll and 1.70 mm at the minimum part at the end of the roll, and the clearance between the mold roll and the peeling roll is 4.00 mm at the maximum part in the center of the roll. The minimum end portion was 1.80 mm. The peripheral speeds (outermost diameters) of the nip roll, mold roll, peeling roll, and take-up roll were 1.205 m / min, 1.209 m / min, 1.230 m / min, and 1.207 m / min, respectively. The nip roll, the mold roll, and the release roll are subjected to hard chrome plating, and the surface material of the take-up roll is EPT rubber.

As shown in FIG. 4, the resin sheet is produced by installing a far-infrared ceramic heater at a position 50 mm away from the resin sheet surface on the opposite side of the surface in contact with the mold roll and the release roll, A range of 150 mm was heated from both ends of the sheet. At this time, the surface temperature of the far-infrared ceramic heater was 500 ° C., and it was heated for 20 seconds during contact with the mold roll and for 15 seconds during contact with the peeling roll.

Also in the transport section, a far infrared ceramic heater is installed at a position 120 mm away from the release roll and 50 mm away from the resin sheet on the lower surface side, the heater surface temperature is set to 500 ° C., and the range of 150 mm from each end of the sheet is 20 mm. Heated in seconds.

An ultrasonic cutter was installed at a position 200 mm from the peeling roll, and the 2.0 mm thick portions at both ends of the resin sheet were cut. When the resin sheet surface temperature of the cut part was measured with a radiation thermometer (TH9100MV manufactured by NEC Sanei Co., Ltd.), the sheet surface was 115 ° C.

The blade of the ultrasonic cutter is made of high-speed steel, the thickness is 0.6 mm, the shape is an oblique blade, the tip is a single blade, and the blade surface on the side in contact with the product-side surface of the resin sheet is parallel to the traveling direction of the resin sheet. It installed so that it might become. The ultrasonic output was 220 W, the vibration frequency was 22 kHz, and the blade and component joints were air-cooled with compressed air.

Chips were not generated by cutting with an ultrasonic cutter, and burrs generated by cutting were generated intensively on the cut surfaces on both ends, not on the product side, and a good resin sheet could be obtained.
[Comparative Example 1]
Under the conditions of Example 1. Although a normal cutter blade was installed at a position 200 mm from the peeling roll and an attempt was made to cut a portion having a thickness of 2.0 mm at both ends of the resin sheet, the sheet could not be cut.
[Comparative Example 2]
Under the conditions of Example 1, an ultrasonic cutter was installed at a position 900 mm from the peeling roll, and the 2.0 mm thick portions at both ends of the resin sheet were cut. The sheet surface of the cut part was 50 ° C. Although the sheet could be cut without generating chips, cracks occurred on the product side of the resin sheet, and a good resin sheet could not be obtained.

DESCRIPTION OF SYMBOLS 10 ... Production line 12 ... Die 14 ... Resin sheet 16 ... Mold roller 18 ... Nip roller 20 ... Peeling roller 22 ... Heating device 24 ... Periodic shape seam 100 ... Raw material process 112 ... Extrusion process 114 ... Sheet forming process 115 ... Peeling process 116 ... slow cooling process 124 ... cutting process 126 ... loading process 128 ... raw material silo 130 ... additive silo 132 ... automatic meter 134 ... mixer 136 ... hopper 138 ... extruder 140 ... metering pump 142 ... supply pipe 154 ... slow cooling zone 174 ... Ultrasonic cutter 176 ... Collection box 192 ... Drum-shaped member 194 ... Roller 196 ... Conveyor belt

Claims

An extrusion process of extruding the molten resin from the die into a sheet,
A sheet forming step of forming the sheet by sandwiching the extruded resin sheet between a mold roller and a nip roller and solidifying by cooling;
A peeling step of peeling the resin sheet from the mold roller;
A cutting step of cutting the both end portions of the resin sheet having a thickness of 1 mm or more with an ultrasonic cutter along the conveying direction;
A method for producing a resin sheet, characterized in that the temperature of the cut portion of the resin sheet is (Tg−50) ° C. or more and (Tg + 100) ° C. or less when the glass transition temperature of the resin is Tg.
The blade of the ultrasonic cutter is a single blade, and the blade surface of the blade of the ultrasonic cutter that contacts the product side of the resin sheet is parallel to the traveling direction of the resin sheet. The manufacturing method of the resin sheet of description.
The resin sheet according to claim 1 or 2, wherein the resin sheet has a thickness distribution in a width direction, and a difference in thickness between the thickest part and the thinnest part is 0.5 mm or more and 5 mm or less. Method.
4. The resin sheet according to claim 3, wherein a thickness distribution in the sheet width direction has a periodicity of a pitch of 200 mm or more, and a seam having a periodic shape is cut along the conveying direction by the ultrasonic cutter. Production method.
The cutting position is detected during conveyance of the resin sheet, the ultrasonic cutter moves following the change of the cutting position, and the cutting position is cut. Manufacturing method of resin sheet.
The method for producing a resin sheet according to any one of claims 1 to 5, wherein the cut portion of the resin sheet is divided into a plurality of times and cut with the ultrasonic cutter.
The method for producing a resin sheet according to any one of claims 1 to 6, wherein the resin sheet is cut in a width direction by an ultrasonic cutter.