JP2007118478A - Method of manufacturing thermoplastic resin sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing a thermoplastic resin sheet which prevents an amount of operation to a thickness adjusting means from diverging so as to stably manufacture a sheet having a minimal thickness fluctuation. <P>SOLUTION: The method of manufacturing the thermoplastic resin sheet comprises the steps of: measuring a thickness distribution in the sheet width direction while the sheet is formed by extruding a material using a die 1 provided with a plurality of thickness adjusting means 2; determining a manipulated variable for outputting to the thickness adjusting means 2 on the basis of the measured value using a process model descriptive of a behavior of a control system; and controlling so that the thickness distribution in the width direction becomes a required thickness distribution by transmitting the manipulated variable to each thickness adjusting means 2, wherein the adjustment of the corresponding relation between a plurality of the thickness adjusting means 2 and measuring points of the thickness distribution in the width direction is performed on the condition that satisfies a predetermined equation after manufacturing at least one roll of the product sheet, and the manipulated variable for inputting to the thickness adjusting means 2 is obtained on the basis of a result of the adjustment. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for producing a thermoplastic resin sheet.

  Conventionally, the manufacturing method of a thermoplastic resin sheet is performed by the following process.

  FIG. 2 is a schematic view of a general thermoplastic resin sheet production facility.

This manufacturing equipment includes a die 1 that forms extruded molten resin into a sheet shape by a lip gap, a cooling roll 3 that is formed into a sheet shape, a stretching machine 4 that stretches the sheet vertically and horizontally, and a stretched sheet that is continuously formed. And a turret winder 6 that can be rolled up to a desired length and continuously switched.
The sheet is required to have the same predetermined thickness in the width direction, but in practice, it is difficult to pass the molten resin through the narrow gap of the base at the same speed in the width direction, and the stretching also differs in the width direction. Therefore, the thickness of the sheet is not necessarily the same in the width direction.

  For this purpose, the base 1 is provided with thickness adjusting means 2 arranged in the width direction with respect to the sheet. As the thickness adjusting means 2, a heat bolt system is used in which heat bolts are used and the temperature of these bolts is changed to thermally expand and contract the bolts to adjust the lip gap of the base 1.

  The sheet was continuously passed through the stretching machine 4, and the sheet thickness after passing through the stretching machine 4 was measured as a distribution in the width direction of the sheet with the thickness measuring device 5. Various sheet manufacturing methods are known in which the thickness adjusting means 2 is controlled based on the thickness measurement value at the measurement position corresponding to the thickness adjusting means 2.

  At this time, it is important that the correspondence between each thickness adjusting unit and the measurement position of the sheet thickness is determined with high accuracy. If it is not determined with high accuracy, the sheet thickness at a position different from the position that should be adjusted is adjusted, and the sheet thickness cannot be controlled with high accuracy, resulting in a reduction in sheet quality. As long as it extends uniformly in the sheet width direction at various points in the sheet width direction, the measurement position corresponding to each thickness adjusting means is determined from the similar relationship between the sheet width at the casting position and the sheet width at the measurement position. Although it can be determined, the necking-in phenomenon, in order to converge the thickness unevenness that occurs due to the stretching state varies depending on the location in the sheet width direction and the stretching state varies in the width direction, the control of the base Due to the effect that the lip gap cannot be made uniform in the width direction, it is not possible to determine the corresponding relationship simply by using the similarity as described above, and it is necessary to actually measure the measurement position corresponding to each thickness adjusting means. is there.

As a method for determining the correspondence between the thickness adjusting means and the measurement position, for example, in Patent Document 1, the sheet thickness fluctuation caused by operating the thickness adjusting means by operating the thickness adjusting means by a predetermined amount is in a steady state. By the way, it is disclosed that the peak position of the sheet thickness variation is detected and the measurement position closest to the peak position is set as the position corresponding to the thickness adjusting means.
As the control means, the thickness adjusting means is operated by a predetermined amount before the start of control, and when the sheet thickness fluctuation caused by operating the thickness adjusting means becomes a steady state, the sheet thickness fluctuation peak is detected and the peak position is the highest. The measurement position of each thickness adjusting means and the sheet thickness is determined by a method of setting the measurement position as the corresponding position of the thickness adjusting means (hereinafter referred to as adjusting means), and the known proportional (P), proportional integral (PI) or proportional integral derivative ( PID control type thickness control means that outputs the control output obtained by calculating (PID) as the operation amount to the thickness adjustment means can provide a stable effect for simple construction, and is easy to tune. Widely used for reasons.
However, in the case of PID control, the thickness distribution control in the width direction of the sheet can be practically performed without any problem in a steady operation state. There was a problem that it took a lot of time to make the spots converge.

  Therefore, in recent years, a computer-based control system has been developed, and an operation amount to be added to the thickness adjustment means is determined using a process model representing a mathematical relationship between the operation amount to be applied to the thickness adjustment means and the sheet thickness described in Patent Documents 2 and 3. By the method, the convergence of the thickness is improved. In the case of control using a process model, compared to PID control, the thickness unevenness convergence speed at the time of start-up and a large change in conditions is high, and the final convergence thickness unevenness is also small, and a sheet with smaller thickness unevenness can be manufactured. .

  However, when a thermoplastic resin sheet is manufactured by performing thickness control using a process model, a situation occurs in which the difference between the operation amount of the thickness adjustment unit and the operation amount of the adjacent thickness adjustment unit becomes excessively large. There was a thing. When the difference in the operation amount at the adjacent position becomes excessively large, even if the difference between adjacent thickness adjustment means is made larger, the operation amount will affect the adjacent thickness adjustment means, and the shape of the gap It becomes impossible to follow the amount difference, the gap adjustment ability is lowered, the sheet thickness control accuracy is lowered, and the operation amount is eventually diverged, resulting in an uncontrollable state.

  In order to converge the thickness unevenness, the operation amount is changed to the thickness adjusting means at any time, and the flow path of the molten thermoplastic resin is changed by the change in the shape of the base lip accompanying the change in the operation amount. For this reason, a slight deviation occurs in correspondence to the adjusting means before the thickness adjustment. This slight misalignment was not a major problem in the case of PID control, but in the case of control using a process model capable of improving even a large change in operation amount or even minute thickness unevenness, the operation amount is increased by using for a long time. The tendency to diverge is revealed.

In addition, the process gain and interference rate, which are important characteristics related to the process model, change due to the change in the shape of the gap between the base lips, causing a slight change, and it appears that the actual process characteristics do not necessarily match the process model. It is difficult to perfectly match the process model with the actual process because there are differences in the thickness adjusting means. Due to this process model error, the control stability may decrease.If the control stability decreases, even if the system can be controlled without any problems in a short time, such as when starting up or when a large condition is changed, it will be long in the steady operation state. As it was used over time, the final thickness convergence worsened, and the amount of operation diverged, leading to a loss of control.
JP 2002-301752 A JP 2000-094497 A JP 2002-096371 A

  An object of the present invention is to solve the above-mentioned problems, to provide a method for producing a sheet having a small thickness unevenness while preventing the manipulated variable from diverging.

  In order to achieve the above object, the present invention has the following configuration.

  That is, the raw material is extruded using a die provided with a plurality of thickness adjusting means, molded into a sheet, the thickness distribution in the width direction of the sheet is measured, and the behavior of the control system is determined based on the measured value. Using the described process model, an operation amount to be applied to the thickness adjusting unit is obtained, and the operation amount is output to each thickness adjusting unit so that the thickness distribution in the width direction of the sheet becomes a desired thickness distribution. A method of manufacturing a sheet, wherein the adjustment of the correspondence between the plurality of thickness adjusting means and the position in measuring the thickness distribution in the width direction is performed after manufacturing a roll of one or more product sheets. There is provided a method for producing a thermoplastic resin sheet, which is carried out under the condition that the formula (1) is established, and an operation amount to be applied to the thickness adjusting means is obtained based on the adjustment result.

Ｆ：品種替えもしくは口金交換または前回調整手段対応を実施してからの経過時間[時間]
ｄ：熱可塑性樹脂シートの基準厚み[μm]
Ｎ：品種替えもしくは口金交換から調整手段対応を実施した回数（Ｎ＝０，１，２，３，・・・）
また、本発明の好ましい形態によれば、前記各厚み調整手段と幅方向における厚み分布の測定に際する位置との対応関係の調整は、互いに離間した前記複数個の厚み調整手段について同時期に実施し、前記対応関係を調整した前記各厚み調整手段ごとに、プロセスゲインおよび/または隣接する厚み調整手段との干渉率を求め、求めた前記プロセスゲインおよび/または前記干渉率に基づいてプロセスモデルを再構成することを特徴とする請求項１に記載の熱可塑性樹脂シートの製造方法が提供される。

F: Elapsed time [hours] since the product change or base change or the last adjustment procedure
d: Reference thickness [μm] of thermoplastic resin sheet
N: Number of times adjustment means support was implemented from product change or base change (N = 0, 1, 2, 3,...)
Further, according to a preferred embodiment of the present invention, the adjustment of the correspondence relationship between the thickness adjusting means and the position for measuring the thickness distribution in the width direction is performed at the same time for the plurality of thickness adjusting means spaced from each other. The process gain and / or the interference rate with the adjacent thickness adjustment unit is obtained for each of the thickness adjustment units that have been implemented and the correspondence relationship has been adjusted, and a process model is obtained based on the obtained process gain and / or the interference rate The method for producing a thermoplastic resin sheet according to claim 1 is provided.

  In the present invention, the process model is the time delay of the operation of the thickness adjusting means after outputting the operation amount, the time when the sheet is conveyed from the die to the position of the thickness measuring device, and the width direction in the thickness measuring device. In consideration of the dead time consisting of the time required to measure the thickness data and the interference of the change in the sheet thickness at the position corresponding to the adjacent thickness adjusting means when one thickness adjusting means is operated, the control system This is a mathematical expression of behavior. However, modeling each thickness adjusting unit individually not only requires a great amount of time and labor, but also the time series derivation formula becomes too complicated. Therefore, the process model represents the interference between the transfer function representing the relationship between the operation amount of the thickness adjusting means and the sheet thickness at the corresponding position and the individual thickness adjusting means. It is preferable to express using at least a product with a constant matrix whose diagonal component is not zero. Thereby, the calculation at the time of operation amount time series calculation of the thickness adjusting means is simplified.

  In the present invention, the thermoplastic resin is a resin that exhibits plasticity when heated, and typical resins (polymers) include polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, polyethylene α, β-dicarboxylate, P -Polymers from hexahydro xylylene terephthalate, polymers from 1,4 cyclohexanedimethanol, poly-P-ethyleneoxybenzoate, polyarylate, polycarbonate etc. and their ester linkages to the main chain as represented by their copolymers Polyamides having amide bonds in the main chain as represented by nylon 6, nylon 66, nylon 610, nylon 12, nylon 11, etc., polyethylene, polypropylene, ethylene vinyl acetate copolymer, polymethyl Polyolefins mainly composed of hydrocarbons such as pentene, polybutene, polyisobutylene, polystyrene, etc., polyethersulfone (PES), polyphenylene oxide (PPO), polyetheretherketone (PEEK), polyethylene oxide, polypropylene Polyethers represented by oxides, polyoxymethylene, etc., halogenated polymers represented by polyvinyl chloride, polyvinylidene chloride, polyvinylidene fluoride, polychlorotrifluoroethylene, and polyphenylene sulfide (PPS), polysulfone And their copolymers and modified products.

  In the case of the present invention, as the thermoplastic resin, polyesters, polyamides, polyethers, polyphenylene sulfides and the like are particularly preferable. Polyesters such as polyethylene terephthalate and polyethylene naphthalate and polyphenylene sulfides are particularly preferable in the present invention. This effect is remarkable and is more preferable. Of course, additives such as stabilizers, viscosity modifiers, antioxidants, antistatic agents, antiblocking agents, ultraviolet absorbers, infrared absorbers and the like may be appropriately added to the above-described resins as necessary.

  In the present invention, the reference thickness of the thermoplastic resin sheet is a target thickness that is uniquely determined by the type of product to be manufactured.

  In the present invention, the process gain is a value representing the sensitivity of the control amount change with respect to the operation amount change. That is, the value represents how much the thickness of the sheet changes when the operation amount input to the sheet thickness adjusting means is changed by a unit amount. In the present invention, the interference rate is the thickness adjusting means adjacent to the sheet thickness change at the sheet thickness measuring position corresponding to the sheet thickness adjusting means corresponding to the thickness adjusting means when a certain thickness adjusting means is operated. Is a value representing how much the thickness of the sheet at the measurement position corresponding to. That is, when the thickness adjusting means is operated, the sheet thickness changes not only at the operation position but also at the peripheral portion due to the influence of the base rigidity and the stretching process. At this time, the sheet thickness change rate at the measurement position corresponding to the thickness adjusting means adjacent to the operated thickness adjusting means is shown.

  According to the method for producing a thermoplastic resin sheet of the present invention, the amount of operation to the thickness adjusting means diverges, an uncontrollable state can be prevented, and a thermoplastic resin sheet having a small thickness variation can be stably produced.

  Examples of the best embodiment of the present invention will be described below.

  After changing the base, that is, from the state where production of the film is suspended, before starting to control the thickness of the sheet, a predetermined interval among the plurality of thickness adjusting means, preferably a thickness fluctuation distribution by operation of the thickness adjusting means A predetermined operation amount is added to two or more thickness adjusting means which are separated by an interval at which the interference can be ignored. When the thickness variation of the sheet caused by operating the thickness adjusting means reaches a steady state, the thickness deviation distribution in the width direction is obtained by taking the deviation from the thickness before changing the thickness adjusting means. The peak position of this thickness distribution is detected, and the measurement position closest to the peak position is set as the corresponding position of the thickness adjusting means. Further, by interpolating between corresponding positions of the peak position thickness adjusting means, the relationship between all thickness adjusting positions and thickness measuring positions is calculated, and the corresponding positions of the adjusting means are acquired.

  FIG. 3 shows the thickness uniformity deterioration time in which the thickness uniformity deteriorates as it is used for a long time when the process model is controlled at the corresponding position. As an evaluation of thickness uniformity, the thickness distribution in the width direction was calculated by averaging the thickness distribution in the width direction of the sheet measured 20 times with the thickness measuring instrument in the width direction of the sheet after passing through the stretching machine. The time until the R value of the thickness distribution (the difference between the maximum value and the minimum value of the thickness distribution in the width direction) deteriorated by 50% was used. When the thickness uniformity deteriorates, the adjustment means is dealt with, and among the 82 thickness adjustment means, the thirteenth, 27th, 41st, 55th, and 69th thickness adjustment means respectively have 240 thickness measurement positions. Table 1 shows which thickness measurement position corresponds to. The thickness uniformity was evaluated for sheets having a reference thickness of 30 μm, 50 μm, 100 μm, 250 μm, and 500 μm, respectively.

口金を交換してからは、最初の調整手段対応以降では大きな厚み斑を修正するために、口金リップ形状変化が大きくなり、調整手段対応のズレが大きくかつ厚み均一性の悪化が早く現れる（図３において、６０〜７５時間程度までの間に厚み均一性が悪化している。）。２回目以降は厚み斑は小さい状態で制御を再開することができるために、調整手段対応のズレが発生するまでの時間が長くなり、厚み均一性の悪化までの時間が延長される（図３において、７５〜１２０時間程度までの間に厚み均一性が悪化している。）。３回目以降においては、２回目の調整手段対応後に、まず調整手段対応にズレが生じた状態での厚み調整手段の操作量から、厚み均一性を確保するための操作量に戻すように操作量が変化し、口金のリップ形状変化が小さいながらも発生する（図３において、１１０〜１４０時間程度までの間に厚み均一性が悪化している。）。この形状変化は、回数ごとに小さくなるために、調整手段対応を実施するたびに減少していき、結果として調整手段対応実施までの時間を伸ばすことが可能になるが、最終的には、厚み均一性確保のための操作量変化があり、形状変化も少ないものの存在するので、調整手段対応のズレが無くなることはない。この厚み均一性悪化までの時間は式（１）で近似することができ、この近似式で演算された間隔以内で、再び調整手段対応を実施することによって、厚み均一性の悪化を防ぐことが出来る。

After replacing the base, in order to correct large thickness spots after the first adjustment means, the change in the lip shape of the base becomes large, the deviation corresponding to the adjustment means is large, and the uniformity of thickness appears quickly (Fig. 3, the thickness uniformity has deteriorated for about 60 to 75 hours. Since the control can be resumed with the thickness unevenness being small after the second time, the time until the deviation corresponding to the adjusting means occurs is lengthened and the time until the thickness uniformity is deteriorated (FIG. 3). In this case, the thickness uniformity has deteriorated for about 75 to 120 hours). In the third and subsequent times, after the second adjustment means, the operation amount is returned from the operation amount of the thickness adjustment means in a state where the adjustment means is deviated to the operation amount for ensuring thickness uniformity. This occurs even though the lip shape change of the die is small (in FIG. 3, the thickness uniformity is deteriorated between about 110 to 140 hours). Since this shape change becomes smaller every time, it will decrease each time the adjustment means correspondence is implemented, and as a result, it will be possible to increase the time until the adjustment means correspondence implementation, but ultimately the thickness Since there is a change in the operation amount for ensuring uniformity and there is little change in shape, there is no loss of deviation corresponding to the adjusting means. The time until the thickness uniformity is deteriorated can be approximated by the equation (1). By implementing the adjustment means again within the interval calculated by this approximate equation, the deterioration of the thickness uniformity can be prevented. I can do it.

  Further, a ratio between the deviation amount of the peak position and a certain operation amount added to the thickness adjusting means is calculated as a process gain. When the corresponding position is calculated, the position of the thickness adjusting unit adjacent to the position where the certain amount of operation is added to the thickness adjusting unit is also calculated, and the ratio between the deviation amount of the position and the peak value of the deviation is calculated as the interference rate. Is done. A process model is created from the calculated process gain and interference rate.

  By applying the newly created process model to the control, it is possible to control the process model with a small error due to the change in the shape of the lip gap, and as a result, the final thickness convergence is good. Turn into.

  FIG. 1 shows a flowchart in the embodiment of the present invention.

  Using the process model, before the sheet is manufactured by controlling the thickness, the adjustment means is handled, the corresponding position is acquired, and the process gain and interference rate are calculated from the thickness deviation that appears in response to the adjustment means. Then, create a process model and apply it to the control. Control is performed using a process model to produce a sheet. Stop the control once by the time of the formula (1), and implement the adjustment means so that the adjustment means corresponding to the long-term use will be displaced and the manipulated variable tends to diverge and the thickness unevenness does not increase. . Substituting the corresponding position and process model obtained by this adjustment time correspondence, control is started again, and a sheet with good thickness uniformity is manufactured.

  In this case, when the product sheet is being manufactured, the control is temporarily stopped and the adjustment means is supported. As a result, a thickness unevenness is provided on the product sheet, and the roll being manufactured at that time does not become a product. When the product roll is switched and the elapsed time from the adjustment means correspondence is compared and the adjustment means correspondence is implemented, the loss of the product roll is eliminated and it is preferably used.

  In the equation (1), when the equal sign holds, it is needless to say that the response time of the adjusting means can be extended most and the yield is improved. Moreover, it is also preferable to take a measure of the adjusting means at about 50% to 80% where the equal sign is established.

  Using the above method for producing a thermoplastic resin sheet, a thermoplastic resin sheet (biaxially stretched polyester film) was produced, and each evaluation was performed.

The polyester was melted by an extruder, extruded from a die at a temperature of 290 ° C., and rapidly cooled and solidified on a casting drum having a surface temperature of 30 ° C. by using an electrostatic application casting method to produce an unstretched sheet. Moreover, the discharge amount of the extruder was adjusted, and it adjusted so that the thickness of the last polyester film after completion | finish of extending | stretching might be set to 50 micrometers. The unstretched film is stretched 3.5 times in the longitudinal direction at 112 ° C., stretched 4.8 times in the width direction at 110 ° C., and then heat treated at 246 ° C., and at a speed of 50 m / min with a winder. Each sheet roll was wound up by 8500 m (winding time was 170 minutes), and a thermoplastic resin sheet (biaxially stretched polyester film) having a thickness of 50 μm was obtained. In order to confirm the uniformity of the thickness distribution in the width direction of the film, R in the width direction of the sheet thickness (difference between the maximum value and the minimum value in the width direction of the film thickness) was measured.
Furthermore, it was monitored over 320 hours that the thickness uniformity did not deteriorate, it was confirmed whether there was a tendency for the thickness to deteriorate, and it was determined as NG when the thickness collapse was observed on a regular basis.
In this case, F in Expression (1) when the number of times N = 0 is 68 or less. Further, F in Expression (1) when N = 1 is 109 or less.
[Example 1]
When manufacturing the sheet, the thickness distribution in the width direction of the sheet after passing through the stretching machine was measured at 240 locations at equal intervals in the width direction of the sheet using a β-ray thickness meter that traverses at a constant speed. Thickness data in the width direction of the sheet measured by the thickness meter is input to a controller composed of a computer. Thickness adjusting means consisting of heat bolts are arranged at 82 positions on the base at equal intervals, and five thickness adjusting means support ( 13th, 27th, 41st, 55th, 69th), the output to the thickness adjusting means is calculated, and control is performed so that the thickness distribution in the width direction becomes uniform by outputting each operation amount to the thickness adjusting means. Then, before the interval after the adjustment means correspondence is reached, the adjustment means correspondence is executed at the stage of 70 hours, 180 hours, and 320 hours, and further the thickness deviation corresponding to the adjustment means is reached. Therefore, the process model created by the obtained process gain and interference rate is used from the next control.

As a result, as shown in FIG. 4, a sheet with a small thickness variation having an average thickness of about 1.2 μm (average of 300 hours) is stably produced without deteriorating the film thickness uniformity over the entire 320 hours monitored. I was able to.
[Example 2]
The adjustment means correspondence is implemented at the stage of 70 hours, 180 hours, and 320 hours before reaching the formula (1), that is, again in the same manner as in the first embodiment. A sheet was manufactured in the same manner as in Example 1 except that the process model created from the average of the process gain and the interference rate measured over the time was continuously used to calculate the output of the thickness adjusting means.

As a result, as shown in FIG. 5, the final thickness variation does not become smaller compared to Example 1 due to process model errors, but it does not degrade the film thickness uniformity over the entire 320 hours monitored. A sheet having a small thickness variation of 5 μm (average of 300 hours) could be stably produced.
[Comparative Example 1]
A sheet was produced in the same manner as in Example 1 except that the production of the adjusting means was not performed even after the time of the formula (1) had elapsed, and the production was continued.

As a result, as shown in FIG. 6, although the thickness unevenness was once reduced, the manipulated variable diverged in about 100 hours due to the deviation corresponding to the adjusting means, and the thickness unevenness also diverged thereafter.
[Comparative Example 2]
As Comparative Example 2, a sheet was produced in the same manner as in Example 1 except that the time of the formula (1) was passed, the adjustment means was handled only once, and the production was continued without carrying out the second and subsequent times. .

  As a result, as shown in FIG. 7, by performing the process up to the calculation of the process model by dealing with the first adjustment means, the initial thickness convergence up to about 160 hours is good, but the adjustment means after the first large thickness spot correction Since the correspondence deviation was corrected, the adjustment means correspondence deviation due to the production of the sheet by executing the control again occurred, the sheet thickness gradually collapsed, and stable film formation could not be performed.

  The above results are summarized in Table 2.

  The present invention can be applied not only to a method for producing a thermoplastic resin sheet but also to sheets of other materials, but the application range is not limited thereto.

It is a flowchart of the sheet thickness adjustment method in the manufacturing method of the thermoplastic resin sheet of this embodiment. It is a perspective view which shows the whole schematic structure of the manufacturing apparatus of a sheet | seat. It is a figure showing the thickness deterioration time in the thickness control using a process model. FIG. 3 is a diagram showing R of sheet thickness produced in Example 1 in time series. FIG. 3 is a diagram showing R of sheet thickness produced in Example 1 in time series. It is the figure which represented R of the sheet thickness manufactured by the comparative example 1 in time series. It is the figure which represented R of the sheet thickness manufactured by the comparative example 2 in time series.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Base 2 Thickness adjustment means 3 Cooling roll 4 Stretching machine 5 Thickness measuring device 6 Winder

Claims (2)

The raw material was extruded using a die equipped with a plurality of thickness adjusting means, molded into a sheet, the thickness distribution in the width direction of the sheet was measured, and the behavior of the control system was described based on this measured value. A sheet for obtaining an operation amount to be applied to the thickness adjusting unit using a process model, outputting the operation amount to the thickness adjusting unit, and controlling the thickness distribution in the width direction of the sheet to be a desired thickness distribution. And adjusting the correspondence between the plurality of thickness adjusting means and the position for measuring the thickness distribution in the width direction, after manufacturing one or more rolls of product sheets, A method for producing a thermoplastic resin sheet, which is performed under a condition that (1) is satisfied, and an operation amount to be applied to the thickness adjusting means is obtained based on the result of the adjustment.

F: Elapsed time [hours] since the product change or base change or the last adjustment procedure
d: Reference thickness [μm] of thermoplastic resin sheet
N: Number of times adjustment means support was implemented from product change or base change (N = 0, 1, 2, 3,...) The adjustment of the correspondence relationship between the thickness adjusting means and the position when measuring the thickness distribution in the width direction is performed at the same time for the plurality of thickness adjusting means spaced from each other, and the correspondence relationship is adjusted. The process gain and / or the interference rate with the adjacent thickness adjustment unit is obtained for each thickness adjustment unit, and a process model is reconfigured based on the obtained process gain and / or the interference rate. 2. A method for producing a thermoplastic resin sheet according to 1.

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