JP2015214024A - Apparatus and method for producing thermoplastic resin sheet and thermoplastic resin sheet obtained therefrom - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an apparatus for producing a thermoplastic resin sheet capable of stably producing a thermoplastic resin sheet having small residual phase difference and small variation in residual phase difference over the whole sheet.SOLUTION: There is provided an apparatus 1 for producing a thermoplastic resin sheet in which a thermoplastic resin sheet 30 is produced by extruding a molten thermoplastic resin from a die 10 to introduce the resin between a metal belt 15 and a third cooling roll 13, then cooling the resin while conveying the resin on the metal belt 15, and releasing the resin from the metal belt 15. And, the apparatus comprises a warpage correction driving roll 18 for correcting warpage of the thermoplastic resin sheet 30, a driving pinch roll 21, a first load detector 171 and a second load detector 201. The sheet tension between the metal belt 15 and the driving pinch roll 21 is controlled within a predetermined range based on the load detected by the first load detector 171 and the second load detector 201.

Description

  The present invention relates to a thermoplastic resin sheet having excellent optical characteristics suitable as an optical sheet used for a liquid crystal display element and the like, and a thermoplastic resin sheet manufacturing apparatus and manufacturing method capable of stably manufacturing the thermoplastic resin sheet.

As a substrate for a transparent electrode or a resin front plate in a liquid crystal display element, a thermoplastic resin sheet having high total light transmittance, high surface smoothness, small sheet warpage, and small residual retardation is required. .
Therefore, in order to produce such a thermoplastic resin sheet, a first cooling roll whose surface is coated with an elastic material, and a metal belt having a mirror-finished surface wound between the second cooling roll and A third cooling roll disposed opposite to the first cooling roll via the metal belt, and controls the surface temperature of the third cooling roll and the temperature of the metal belt, An apparatus for manufacturing a thermoplastic resin sheet that can also control the linear pressure between the belt and the third cooling roll has been proposed (for example, Patent Document 1).

JP 2010-105188 A

  In optical sheets used for liquid crystal display elements and the like, various optical properties are required, and therefore various thermoplastic resins are used. There is also a demand for an optical sheet including a thermoplastic resin layer having a large photoelastic coefficient such as polycarbonate. When manufacturing such an optical sheet, it is necessary to control the peeling tension of the sheet from the metal belt with higher accuracy. In the thermoplastic resin sheet manufacturing apparatus described in Patent Document 1, the peeling tension of the sheet from the metal belt is controlled by controlling the speed of the warp correction driving roll. However, the method for controlling the peeling tension in such a manufacturing apparatus is not always sufficient, and it is difficult to stably manufacture a thermoplastic resin sheet having a small variation in residual retardation across the entire surface of the sheet.

  Accordingly, the present invention provides a thermoplastic resin sheet having a small residual retardation and a small variation in the residual retardation over the entire surface of the sheet, and a thermoplastic resin sheet manufacturing apparatus and a manufacturing method capable of stably manufacturing the thermoplastic resin sheet. The purpose is to do.

  As a result of intensive studies by the present inventors to solve the above-mentioned problems, the following points are important when manufacturing an optical sheet having a thermoplastic resin layer having a large photoelastic coefficient such as polycarbonate, for example. It turns out that. In other words, in the case of a sheet having a thickness of less than 500 μm, it is necessary to control the sheet tension with high accuracy by the small sheet cross-sectional area. On the other hand, in the case of a sheet having a thickness greater than 500 μm, thermal shrinkage occurs in the process of being cooled by being pinched by the metal belt / specular roll, but the direction in which the shrinkage is constrained (direction crossing the machine direction (MD): The shrinkage stress is generated in (TD) and the molecule tends to be oriented (that is, the slow axis is the direction of TD). In order to obtain a sheet having a small residual phase difference, it is necessary to control the sheet tension with high accuracy so that the tension is equal to or greater than a certain tension and equal to or less than a certain tension in a temperature region near Tg. And when manufacturing an optical sheet having a thermoplastic resin layer having a large photoelastic coefficient, it is not sufficient to control the speed of the warp correction driving roll, and the sheet tension between the metal belt and the driving pinch roll is adequate. The present inventors have found that it is necessary to control within a range, and have reached the present invention.

  The thermoplastic resin sheet manufacturing apparatus of the present invention includes a first cooling roll whose surface is coated with an elastic material, a metal belt having a mirror surface and wound between a second cooling roll, and the metal A third cooling roll disposed opposite to the first cooling roll via a belt made of steel, extruding a molten thermoplastic resin from a die attached to an extruder, the metal belt and the An apparatus for producing a thermoplastic resin sheet, which is introduced between third cooling rolls, then cooled while being conveyed by the metal belt and peeled off from the metal belt to form a thermoplastic resin sheet. A warp correction driving roll for correcting the warp of the thermoplastic resin sheet peeled off from the metal belt, and a downstream side of the warp correction driving roll, for taking up the thermoplastic resin sheet A dynamic pinch roll, a first load detector disposed between the metal belt and the warp correction drive roll, and a second load detector disposed between the warp correction drive roll and the drive pinch roll. The warp correction roll speed control means for controlling the speed of the warp correction drive roll and the load detected by the second load detector so that the load detected by the first load detector is within a predetermined range. A pinch roll speed control means for controlling the speed of the drive pinch roll so as to be within a range, and the warp correction roll speed control means is a sheet calculated from the load detected by the first load detector. The tension is controlled to 0.1 MPa or more and 0.5 MPa or less, and the pinch roll speed control means adjusts the sheet tension calculated from the load detected by the second load detector to 0.5. It is characterized in that to control the Pa or less.

  In the present invention, the load applied to the thermoplastic resin sheet between the metal belt and the warp correction driving roll can be detected by the first load detector. And based on this detected value, the sheet tension between the metal belt and the warp correction drive roll is controlled to 0.1 MPa or more and 0.5 MPa or less by controlling the speed of the warp correction drive roll by the warp correction roll speed control means. Can be controlled. Further, the load applied to the thermoplastic resin sheet between the warp correction driving roll and the driving pinch roll can be detected by the second load detector. And based on this detected value, the sheet tension between the warp correction driving roll and the driving pinch roll can be controlled to 0.5 MPa or less by controlling the speed of the driving pinch roll by the pinch roll speed control means. According to the present invention, since the sheet tension between the metal belt and the drive pinch roll is controlled within a predetermined range, the residual phase difference is small, and there is a variation in the residual phase difference over the entire sheet surface. A small thermoplastic resin sheet can be produced stably.

In the thermoplastic resin sheet manufacturing apparatus of the present invention, it is preferable to control the surface temperature of the warp correction drive roll to (Tg−20 ° C.) or more and (Tg + 30 ° C.) or less.
In this invention, the sheet | seat curvature of a thermoplastic resin sheet can fully be corrected because the surface temperature of the curvature correction drive roll is more than predetermined temperature. Moreover, when the temperature of the surface of the warp correction driving roll is equal to or lower than a predetermined temperature, it is possible to more reliably prevent a part of the thermoplastic resin sheet from adhering to the surface of the warp correction driving roll, and the appearance is improved. It is possible to prevent the decrease. Furthermore, it can prevent more reliably that a trace will remain in a thermoplastic resin sheet at the time of peeling from a curvature correction drive roll, and a residual phase difference will become large.

In the thermoplastic resin sheet manufacturing apparatus of the present invention, it is preferable to include means for controlling the sheet temperature on the warp correction drive roll.
In the present invention, the warp of the thermoplastic resin sheet is easily corrected by the means for controlling the sheet temperature on the warp correction drive roll, and a part of the thermoplastic resin sheet adheres to the surface of the warp correction drive roll. It is also possible to prevent such inconveniences.

The method for producing a thermoplastic resin sheet of the present invention comprises a first cooling roll whose surface is coated with an elastic material, a metal belt having a mirror surface and wound between a second cooling roll, and the metal Extruding a molten thermoplastic resin from a die attached to an extruder using a manufacturing apparatus comprising a third cooling roll disposed opposite to the first cooling roll via a belt made from the belt, The thermoplastic resin sheet is introduced between the metal belt and the third cooling roll, and then cooled while being conveyed by the metal belt and peeled off from the metal belt to form a thermoplastic resin sheet. In the manufacturing method, the sheet tension between the metal belt and the warp correction driving roll is set to 0.1M by the warp correction driving roll for warping of the thermoplastic resin sheet peeled from the metal belt. The sheet tension between the warp correction drive roll and the drive pinch roll is adjusted by a correction step of correcting while controlling at a to 0.5 MPa or less and a drive pinch roll disposed on the downstream side of the warp correction drive roll. And a take-up step of taking up the thermoplastic resin sheet while controlling the pressure to 0.5 MPa or less.
Also in this invention, there can exist the same effect as the manufacturing apparatus of the said thermoplastic resin sheet. In addition, also in the manufacturing method of the thermoplastic resin sheet of this invention, you may apply the content described about the manufacturing apparatus of the said thermoplastic resin sheet.

The thermoplastic resin sheet of the present invention is obtained by the method for producing a thermoplastic resin sheet.
According to the method for producing a thermoplastic resin sheet, a thermoplastic resin sheet having a small residual phase difference and a small variation in the residual phase difference over the entire surface of the sheet can be obtained.

It is a schematic block diagram which shows the manufacturing apparatus of the thermoplastic resin sheet concerning embodiment of this invention.

With reference to FIG. 1, the manufacturing apparatus and manufacturing method of a thermoplastic resin sheet (hereinafter abbreviated as “sheet”) according to the present embodiment, and the sheet obtained thereby will be described.
First, the configuration of the sheet manufacturing apparatus according to the present embodiment will be described.

[Embodiment]
As shown in FIG. 1, the manufacturing apparatus 1 is made of a metal wound around a die 10 of an extruder, a first cooling roll 11, a second cooling roll 12, and a fourth cooling roll 14. A belt 15 (hereinafter, abbreviated as “belt 15”), and a third cooling roll 13 disposed to face the first cooling roll 11 with the sheet 30 and the belt 15 interposed therebetween are provided.
A fourth cooling roll 14 is disposed below the first cooling roll 11, and a second cooling roll 12 is disposed at substantially the same height as the fourth cooling roll 14. The third cooling roll 13 is disposed opposite to the first cooling roll 11 at substantially the same height position. The third cooling roll 13 is provided so as to come into contact with the first cooling roll 11 via the sheet 30 and the belt 15 and to hold the sheet 30 pressed to the third cooling roll 13 side by the belt 15. Yes. That is, the belt 15 and the sheet 30 in contact with the belt 15 meander so as to be wound around a part of the peripheral surface 131 of the third cooling roll 13.

The manufacturing apparatus 1 includes a nip pressure control unit that controls a linear pressure applied between the belt 15 and the third cooling roll 13, and a roll temperature control that controls the temperature of the peripheral surface 131 that is the surface of the third cooling roll 13. And belt temperature control means for controlling the back surface temperature of the belt 15.
Here, the peripheral surface 131 is a surface that contacts the sheet 30 conveyed by the belt 15. The belt temperature control means includes a second roll temperature control means for controlling the temperatures of the peripheral surfaces 111, 121, and 141 of the first, second and fourth cooling rolls 11, 12 and 14, a belt temperature adjuster 16, Have The back surface temperature of the belt 15 is controlled by the second roll temperature control means and the belt temperature adjuster 16.
The belt temperature controller 16 has a cooling surface 161 that is disposed between the first and second cooling rolls 11 and 12 and substantially faces the peripheral surface 131 with the belt 15 interposed therebetween. The cooling surface 161 cools the belt 15 from a position where the belt 15 and the first cooling roll 11 are separated from a position where the sheet 30 and the belt 15 are separated.
The roll temperature control means and the belt temperature control means control the temperature of the peripheral surface 131 and the temperature of the belt 15 to (Tg−60 ° C.) or more and (Tg + 30 ° C.) or less, and control the temperature difference within 30 ° C. It is preferable to do. Here, Tg is the glass transition temperature of the thermoplastic resin. If the temperature of the peripheral surface 131 and the temperature of the belt 15 are less than (Tg−60 ° C.), a large residual phase difference tends to occur when the sheet 30 is rapidly cooled and pinched. On the other hand, when the temperature of the peripheral surface 131 and the temperature of the belt 15 exceed (Tg + 30 ° C.), the retardation unevenness and the thickness unevenness tend to occur due to the tension at the time of peeling. If the temperature difference exceeds 30 ° C., a difference in shrinkage may occur due to the temperature difference between the front and back surfaces of the sheet 30, and the residual phase difference may increase.

  The die 10 (T die) has an extrusion port 101 through which the sheet 30 is extruded. The distance from the extrusion port 101 until the resin is introduced between the belt 15 and the third cooling roll 13 (air gap) is preferably 200 mm or less, and more preferably 180 mm or less. If the air gap exceeds 200 mm, the sheet 30 may flutter and uneven thickness may occur, and the molten sheet 30 is cooled before being nipped (nip), and a residual phase difference is likely to occur. There is a tendency.

The first to fourth cooling rolls 11, 12, 13, and 14 are, for example, double pipe spiral metal rolls. Although the surface roughness Rz of the 3rd cooling roll 13 is not specifically limited, For example, it is 0.1 micrometer.
The surface of the first cooling roll 11 is covered with an elastic material 113. Examples of the elastic material 113 include fluorine rubber, nitrile rubber, and silicon rubber. The hardness of the elastic material 113 (based on JIS K6301 A type) is preferably 90 degrees or less. The thickness of the elastic material 113 is preferably 3 mm or more, but is not limited thereto.
Rotating shafts 112, 122, 132, 142 are provided at the centers of the first to fourth cooling rolls 11, 12, 13, 14. The manufacturing apparatus 1 includes a nip pressure control unit, and the nip pressure control unit can move the rotating shaft 132 of the third cooling roll 13 close to or away from the first cooling roll 11. By such movement, the linear pressure (nip pressure) applied between the belt 15 and the third cooling roll 13 is controlled to a predetermined pressure. The nip pressure may be controlled by moving the rotating shaft 112 of the first cooling roll 11 close to or away from the third cooling roll 13.
The nip pressure applied by the nip pressure control means is preferably 300 N / cm or less, and more preferably 250 N / cm or less. When the nip pressure exceeds 300 N / cm, a bank (molten resin pool) is partially generated in the width direction of the sheet 30, and as a result, a stable low phase difference sheet 30 may not be obtained.

  As shown in FIG. 1, the manufacturing apparatus 1 includes a first detector-equipped guide roll 17 including a first load detector 171, a warp correction drive roll 18, a guide roll 19, and a second load detector 201. A guide roll 20 with a second detector and a drive pinch roll 21 are further provided.

  The first detector-equipped guide roll 17 is disposed between the belt 15 and the warp correction drive roll 18. The first load detector 171 provided on the first detector-equipped guide roll 17 can measure the load applied to the sheet 30 between the belt 15 and the warp correction drive roll 18. The sheet tension can be calculated from the detected value of the load. And this 1st load detector 171 and the curvature correction roll speed control means of the curvature correction drive roll 18 are electrically connected via the sequencer, and speed control can be performed based on the information of this detected value. .

The surface of the first detector-equipped guide roll 17 is subjected to hard chrome plating or the like. The surface roughness Rz of the first detector-equipped guide roll 17 is preferably 0.8 μm or less (more preferably 0.4 μm or less).
The first detector-equipped guide roll 17 may be a drive roll or a free roll without drive.
In the case of a free roll, the rotational load is preferably less than 5N (more preferably 1N or less) even if the temperature rises to near Tg during film formation. When the rotational load is 5 N or more, the surface of the sheet tends to be easily damaged due to rotational resistance.
The first detector-equipped guide roll 17 may be temperature-controlled inside. When adjusting the temperature inside, resistance by the rotary joint is increased, so that it is preferable to use a driving roll in order to reduce the rotational load.
The distance between the first detector-equipped guide roll 17 and the belt 15 disposed upstream is 500 mm or less, and the distance between the guide roll 19 or the warp correction driving roll 18 disposed downstream is 500 mm or less. It is preferable to install in. If the distance exceeds the upper limit, it tends to be difficult to keep the sheet tension constant in the sheet width direction, and as a result, it tends to be difficult to make the retardation value low in the sheet width direction uniform.

The warp correction driving roll 18 can peel the sheet 30 adhered to the belt 15 and correct the warp of the sheet 30 peeled from the belt 15. The warp correction drive roll 18 is arranged with a predetermined distance from the third cooling roll 13.
The surface of the warp correction drive roll 18 is subjected to hard chrome plating or the like. The surface roughness Rz of the warp correction driving roll 18 is preferably 0.8 μm or less (more preferably 0.4 μm or less).

  The warp correction drive roll 18 includes a warp correction roll speed control means (not shown) for controlling the speed of the warp correction drive roll 18. Examples of the warp correction roll speed control means include those capable of controlling the speed with high accuracy by a vector inverter motor or the like. And based on the detected value detected with the 1st load detector 171 provided in the guide roll 17 with a 1st detector, the sheet | seat 30 can be sent, controlling the speed | rate of the curvature correction drive roll 18. FIG. Thereby, the sheet tension between the belt 15 and the warp correction driving roll 18 can be controlled to 0.1 MPa or more and 0.5 MPa or less. As a result, the variation in the residual phase difference can be reduced over the entire sheet surface while reducing the sheet warpage of the sheet 30.

The guide roll 19 is disposed between the first detector-equipped guide roll 17 and the warp correction drive roll 18. By adjusting the position of the guide roll 19, the sheet holding angle at the warp correction drive roll 18 can be increased.
The surface of the guide roll 19 is subjected to hard chrome plating or the like. It is preferable that the surface roughness Rz of the guide roll 19 is 0.8 μm or less (more preferably 0.4 μm or less).
The guide roll 19 may be a driving roll or a free roll without driving.
The guide roll 19 may adjust the temperature inside. When adjusting the temperature inside, resistance by the rotary joint is increased, so that it is preferable to use a driving roll in order to reduce the rotational load.

  The second detector-equipped guide roll 20 is disposed between the warp correction drive roll 18 and the drive pinch roll 21. The second load detector 201 provided on the second detector-equipped guide roll 20 can measure the load applied to the sheet 30 between the warp correction drive roll 18 and the drive pinch roll 21. The sheet tension can be calculated from the detected value of the load. The second load detector 201 and the pinch roll speed control means of the drive pinch roll 21 are electrically connected via a sequencer, and the speed can be controlled based on the information of the detected value.

Hard chromium plating etc. are given to the surface of the guide roll 20 with a 2nd detector. The surface roughness Rz of the second detector-equipped guide roll 20 is preferably 0.8 μm or less (more preferably 0.4 μm or less).
The second detector-equipped guide roll 20 may be a drive roll or a free roll without drive.
In the case of a free roll, the rotational load is preferably less than 5N (more preferably 1N or less) even if the temperature rises to near Tg during film formation. When the rotational load is 5 N or more, the surface of the sheet tends to be easily damaged due to rotational resistance.
The second detector-equipped guide roll 20 may be temperature-controlled inside. When adjusting the temperature inside, resistance by the rotary joint is increased, so that it is preferable to use a driving roll in order to reduce the rotational load.
The guide roll 20 with the second detector is installed such that the distance from the warp correction drive roll 18 disposed upstream is 500 mm or less and the distance from the drive pinch roll 21 disposed downstream is 500 mm or less. It is preferable to do. If the distance exceeds the upper limit, it tends to be difficult to keep the sheet tension constant in the sheet width direction, and as a result, it tends to be difficult to make the retardation value low in the sheet width direction uniform.

The drive pinch roll 21 is for pulling the sheet 30 and is disposed on the downstream side of the warp correction drive roll 18.
The drive pinch roll 21 includes pinch roll speed control means (not shown) that controls the speed of the drive pinch roll 21. Examples of the pinch roll speed control means include those capable of controlling the speed with high accuracy by a vector inverter motor or the like. And based on the detection value detected with the 2nd load detector 201 provided in the guide roll 20 with a 2nd detector, the sheet | seat 30 can be taken up, controlling the speed of the drive pinch roll 21. FIG. Thereby, the sheet | seat tension between the curvature correction drive roll 18 and the drive pinch roll 21 can be controlled to 0.5 MPa or less. As a result, the variation in the residual phase difference can be reduced over the entire sheet surface.

As shown in FIG. 1, the manufacturing apparatus 1 further includes sheet temperature control means 22 on the warp correction drive roll 18 disposed so as to face the peripheral surface 181 of the warp correction drive roll 18.
Examples of the sheet temperature control means 22 on the warp correction driving roll 18 include a heater such as an infrared radiation heater. The sheet temperature control means 22 is preferably capable of controlling the temperature up to 500 ° C. Moreover, it is preferable that distance adjustment with the curvature correction drive roll 18 is possible.
The sheet temperature control means 22 can be heated until the sheet surface temperature on the side in contact with the warp correction drive roll 18 is in the range of (Tg−20 ° C.) to (Tg + 30 ° C.).
The sheet temperature control means 22 is preferably capable of temperature control in at least three zones in the sheet width direction. Controlling the temperature of the three zones in this way is effective for correcting the warping of the sheet edge.

Next, a method for manufacturing the sheet 30 will be described.
First, a molten thermoplastic resin is extruded from the extrusion port 101 of the die 10 attached to the extruder and introduced between the belt 15 and the third cooling roll 13. At this time, the linear pressure applied between the third cooling roll 13 and the belt 15 is controlled to 300 N / cm or less by the nip pressure control means. Further, the temperature of the peripheral surface 131 is adjusted by the roll temperature control means, and the temperature of the belt 15 is controlled by the belt temperature control means. Thus, the temperature of the peripheral surface 131 and the temperature of the belt 15 are controlled to (Tg−60 ° C.) or more and (Tg + 30 ° C.) or less, and the temperature difference is controlled within 30 ° C.
Then, the sheet 30 is cooled while being conveyed by the belt 15 and is peeled off from the belt 15 to form the sheet 30.

Next, the sheet 30 peeled from the belt 15 is sent to the warp correction drive roll 18 via the first detector-equipped guide roll 17 and the guide roll 19. At this time, the first load detector 171 provided on the first detector-equipped guide roll 17 measures the load applied to the seat 30. Further, the sheet tension is controlled to 0.1 MPa or more and 0.5 MPa or less by controlling the speed of the warp correction driving roll 18 based on the detected value. Further, the temperature of the peripheral surface 181 of the warp correction drive roll 18 is controlled to (Tg−20 ° C.) or more and (Tg + 30 ° C.) or less by the sheet temperature control means 22 on the warp correction drive roll 18. In this way, the warp of the sheet 30 is corrected by the warp correction drive roll 18.
Thereafter, the corrected sheet 30 is taken up by the drive pinch roll 21 via the second detector-equipped guide roll 20. At this time, the second load detector 201 provided on the second detector-equipped guide roll 20 measures the load applied to the sheet 30. Further, the sheet tension is controlled to 0.5 MPa or less by controlling the speed of the drive pinch roll 21 based on the detected value. The sheet 30 can be manufactured as described above.

Next, the sheet 30 obtained in the present embodiment will be described.
The sheet 30 obtained in the present embodiment is made of a thermoplastic resin, and may have a single layer structure or a multilayer structure. In addition, as a method of making the sheet 30 into a multilayer structure, for example, a method of attaching a plurality of extruders to the die 10 can be adopted.
Examples of the thermoplastic resin include a cyclic olefin resin, polycarbonate, polystyrene, and polymethyl methacrylate. In particular, the cyclic olefin-based resin has thermoplasticity, and has a small optical anisotropy, a small photoelastic coefficient, and birefringence unlike other thermoplastic transparent resins such as polycarbonate and polystyrene. This is useful for various applications in the optical field. On the other hand, since polycarbonate is superior in heat resistance and impact resistance as compared with polystyrene, polymethyl methacrylate, and the like, it is useful for optical applications that require thinning.
The sheet 30 obtained in the present embodiment has a small residual phase difference and a small variation in the residual phase difference over the entire sheet surface.

According to the embodiment as described above, the following effects can be obtained.
(1) The load applied to the sheet 30 between the belt 15 and the warp correction driving roll 18 can be detected by the first load detector 171. And based on this detected value, the sheet tension between the belt 15 and the warp correction drive roll 18 is controlled to 0.1 MPa or more and 0.5 MPa by controlling the speed of the warp correction drive roll 18 by the warp correction roll speed control means. The following can be controlled. Further, the load applied to the sheet 30 between the warp correction drive roll 18 and the drive pinch roll 21 can be detected by the second load detector 201. And based on this detection value, the sheet tension between the warp correction drive roll 18 and the drive pinch roll 21 can be controlled to 0.5 MPa or less by controlling the speed of the drive pinch roll 21 by the pinch roll speed control means. . As described above, since the sheet tension between the belt 15 and the drive pinch roll 21 is controlled within a predetermined range, the residual phase difference is small and the variation of the residual phase difference is small over the entire surface of the sheet. 30 can be manufactured stably.

(2) Since the sheet temperature control means 22 on the warp correction drive roll 18 is provided in the vicinity of the warp correction drive roll 18, the temperature of the sheet 30 can be controlled.

[Modification of Embodiment]
The present invention is not limited to the above-described embodiment, and modifications, improvements, and the like within the scope that can achieve the object of the present invention are included in the present invention.
For example, in the above-described embodiment, the mode in which the guide roll 19 is provided between the first detector-equipped guide roll 17 and the warp correction drive roll 18 has been described. However, the embodiment is not limited thereto, and the guide roll 19 is not provided. It is good also as an aspect.

  EXAMPLES Hereinafter, although an Example and a comparative example are given and this invention is demonstrated more concretely, this invention is not limited to the content, such as an Example, at all.

[Example 1]
An extruder, extrusion process conditions, a belt machine, first to fourth cooling rolls and a warp correction driving roll are shown below.
Vent type single screw extruder: Φ90mm (L / D = 32), with which polycarbonate (PC) is extruded, with gear pump.
Polymer filter: Leaf disk type, 16 sheets of 8 inches, nominal filtration accuracy 20 μm.
Coat hanger die: 1000 mm width, lip opening 2 mm.
Extrusion conditions:
Extruder cylinder part; C1 / C2 / C3 / C4 / C5 / C6 / C7 = 200/230/260/260/215/215/215 ° C.,
Adapter part: 260 ° C,
Gear pump part: 260 ° C,
Polymer filter part: 240 ° C.
Die: 260 ° C.,
Extrusion rate: 130 kg / h
Sheet take-up speed: 2.2 m / min.
Belt machine: stainless steel belt; thickness 0.85 mm, width 1000 mm, belt surface roughness Rz = 0.12 μm.
First cooling roll: roll (Φ650 mm) covered with nitrile rubber (NBR) having a thickness of 10 mm and JIS-A 60 °.
Second cooling roll: double pipe spiral metal roll (Φ650 mm).
Third cooling roll: a double pipe spiral roll (Φ650 mm) having a surface roughness Rz = 0.09 μm.
Fourth cooling roll: double pipe spiral metal roll (Φ650 mm).
Warpage correction driving roll: surface roughness Rz is 0.6 μm.

Next, a sheet manufacturing method will be described.
First, as the thermoplastic resin, a polycarbonate resin ^{(MVR = 27cm 3 /10min;300℃,1.2kgf ISO1133 (} JIS-K7210), Tg = 148 ℃ of Idemitsu Kosan Co., Ltd. "Toughlon (TM) A-1700 )) Was dried in a hot air dryer at 110 ° C. for 2 hours.
This polycarbonate resin was supplied to a hopper of an extruder, and a molten resin film in a molten state at 265 ° C. was extruded from an extrusion port (die lip).
The extruded molten resin film is introduced between a belt 15 at 140 ° C. with an air gap of 125 mm and a third cooling roll 13 (140 ° C.) disposed opposite to the first cooling roll 11 via the belt 15. It was clamped with a linear pressure of 350 N / cm. Thereafter, the belt 15 was cooled while being transported by the belt 15 and peeled off from the belt 15. At this time, temperature control was performed from the back surface of the belt by the belt temperature control means, and the belt temperature was kept at a predetermined temperature. After that, the sheet 30 is driven by the first detector-equipped guide roll 17, the guide roll 19, the warp correction drive roll 18 whose surface temperature is controlled to 140 ° C., the second detector-equipped guide roll 20, and the drive. A film was formed through the pinch roll 21. A sheet 30 having a thickness of 1 mm with substantially no warpage was produced by the warp correction driving roll 18. The sheet tension at the first detector-equipped guide roll 17 was set to 0.21 MPa, and the sheet tension at the second detector-equipped guide roll 20 was set to 0.07 MPa.

[Comparative Example 1]
In the comparative example 1, the sheet | seat was produced using the apparatus similar to the manufacturing apparatus of Example 1 except not having the guide roll 17 with a 1st detector. The speed of the warp correction drive roll 18 was set such that the speed ratio with respect to the belt 15 was 100.5%. At this time, the distance from the belt 15 to the guide roll 19 is 900 mm.
[Comparative Example 2]
In Comparative Example 2, a sheet was produced in the same manner as in Example 1 except that the same manufacturing apparatus as in Example 1 was used and the sheet tension in the first detector-equipped guide roll 17 was set to 0.07 MPa.
[Comparative Example 3]
In Comparative Example 3, a sheet was produced in the same manner as in Example 1 except that the same manufacturing apparatus as in Example 1 was used and the sheet tension in the first detector-equipped guide roll 17 was set to 0.8 MPa.

<Measurement of retardation value>
About the sheet | seat obtained by the Example and the comparative example, the retardation value (phase difference) was measured as follows. That is, as a measuring apparatus, a retardation measuring device (“RETS-100” manufactured by Otsuka Electronics Co., Ltd.) was used, and the retardation value was measured by a rotating analyzer method. Then, 16 retardation values were measured at a pitch of 50 mm in the sheet width direction (direction crossing the machine direction (MD): TD). The obtained results are shown in Table 1.

  As is clear from the results shown in Table 1, it was confirmed that the thermoplastic resin sheet obtained in Example 1 had a small residual phase difference and a small variation in the residual phase difference over the entire sheet surface.

  The thermoplastic resin sheet that can be produced by the thermoplastic resin sheet producing apparatus of the present invention can be used as a transparent electrode substrate sheet such as a touch panel or a resin front plate. For example, what was conventionally used as a glass / ITO electrode can be used in place of a thermoplastic resin sheet / ITO electrode, and the alkali-reinforced glass front plate can be used in place of a thermoplastic resin sheet front plate.

DESCRIPTION OF SYMBOLS 1 ... Thermoplastic resin sheet manufacturing apparatus 10 ... Die 11 ... 1st cooling roll 12 ... 2nd cooling roll 13 ... 3rd cooling roll 14 ... 4th cooling roll 15 ... Metal belt 16 ... Belt temperature control 171 ... First load detector 18 ... Warp correction drive roll 201 ... Second load detector 21 ... Drive pinch roll 22 ... Sheet temperature control means on warp correction drive roll 30 ... Thermoplastic resin sheet

Claims (5)

A first cooling roll having a surface coated with an elastic material, a metal belt having a mirror surface wound around the second cooling roll, and the first cooling roll via the metal belt, A third cooling roll disposed oppositely, and
A molten thermoplastic resin is extruded from a die attached to an extruder, introduced between the metal belt and the third cooling roll, and then cooled while being conveyed by the metal belt and made of the metal A thermoplastic resin sheet manufacturing apparatus for forming a thermoplastic resin sheet by peeling from a belt,
A warp correction drive roll for correcting the warp of the thermoplastic resin sheet peeled from the metal belt;
A drive pinch roll disposed on the downstream side of the warp correction drive roll and for taking up the thermoplastic resin sheet;
A first load detector disposed between the metal belt and the warp correction drive roll;
A second load detector disposed between the warp correction drive roll and the drive pinch roll;
A warp correction roll speed control means for controlling the speed of the warp correction drive roll so that the load detected by the first load detector is within a predetermined range;
A pinch roll speed control means for controlling the speed of the drive pinch roll so that the load detected by the second load detector is within a predetermined range;
The warp correction roll speed control means controls the sheet tension calculated from the load detected by the first load detector to 0.1 MPa or more and 0.5 MPa or less,
The apparatus for producing a thermoplastic resin sheet, wherein the pinch roll speed control means controls a sheet tension calculated from a load detected by the second load detector to 0.5 MPa or less. In the manufacturing apparatus of the thermoplastic resin sheet according to claim 1,
The temperature of the surface of the said curvature correction drive roll is controlled to (Tg-20 degreeC) or more and (Tg + 30 degreeC) or less. The manufacturing apparatus of the thermoplastic resin sheet characterized by the above-mentioned. In the manufacturing apparatus of the thermoplastic resin sheet according to claim 1 or 2,
An apparatus for producing a thermoplastic resin sheet, comprising means for controlling a sheet temperature on the warp correction driving roll. A first cooling roll having a surface coated with an elastic material, a metal belt having a mirror surface wound around the second cooling roll, and the first cooling roll via the metal belt, Using a manufacturing device comprising a third cooling roll disposed oppositely,
A molten thermoplastic resin is extruded from a die attached to an extruder, introduced between the metal belt and the third cooling roll, and then cooled while being conveyed by the metal belt and made of the metal A method for producing a thermoplastic resin sheet, wherein a thermoplastic resin sheet is formed by peeling from a belt,
While controlling the sheet tension between the metal belt and the warp correction drive roll to 0.1 MPa or more and 0.5 MPa or less by the warp correction drive roll, the warp of the thermoplastic resin sheet peeled from the metal belt, Correction process to correct,
The thermoplastic resin sheet is taken up while the sheet tension between the warp correction drive roll and the drive pinch roll is controlled to 0.5 MPa or less by the drive pinch roll disposed on the downstream side of the warp correction drive roll. A method for producing a thermoplastic resin sheet.   A thermoplastic resin sheet obtained by the method for producing a thermoplastic resin sheet according to claim 4.

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