JP4049065B2 - Film manufacturing method and apparatus - Google Patents

Description

  The present invention relates to a film manufacturing method and apparatus, and more particularly, to a film manufacturing method and apparatus that enables acquisition of a product roll having excellent smoothness without winding or wrinkling.

  In general, a film forming process is configured such that a molten resin is discharged from a die in a sheet shape, and is stretched to be a stretched film and wound around a roll-shaped raw roll. The stretched film is measured for thickness distribution in the width direction with a thickness meter immediately before being wound into a roll, and the discharge amount distribution in the width direction of the molten resin discharged from the die is adjusted based on the measured value of the thickness distribution. Thus, the thickness distribution of the film is made uniform.

  However, in recent years, users have not only smoothed each film (that is, no thickness unevenness), but also the product roll on which the film has been wound has no wraps or wrinkles on the surface, It is strongly desired that the diameter shape is uniform and smooth. In order to meet such demands, it has become necessary to further enhance the smoothness of each film.

  However, film thickness measurement values are specific to thickness gauges, such as errors due to distortion of the thickness gauge traveling frame in radiographic thickness gauges and errors due to film orientation angles in optical interference thickness gauges. Therefore, even if the thickness measurement value looks smooth, the actual thickness of the film is not smooth and uneven thickness may remain. Therefore, there is a problem that when the thickness unevenness of the film is wound up and laminated in a roll shape, a large shape defect appears when it becomes a product roll.

  As a measure for preventing such defective shape of the product roll, Patent Document 1 measures the outer diameter shape (outer diameter distribution in the width direction) of the product roll together with the measurement of the film thickness distribution just before winding. A method for adjusting the discharge amount distribution in the width direction of the die is proposed by feeding back and correcting the deviation between the measured value of the outer diameter shape and the target outer diameter shape to the measured value of the thickness distribution. ing.

However, in this proposed method, the thickness measurement error of the thickness gauge causes a thickness unevenness on the film, which is why the outer diameter shape of the product roll is defective, there is no thickness measurement error of the thickness gauge, It is impossible to distinguish whether the outer diameter of the product roll is defective due to unevenness in the thickness of the film due to fluctuations in the state of film formation. If there is a thickness measurement error in the thickness meter, it is necessary to feed back the outer diameter shape defect of the product roll, but if there is no thickness measurement error in the thickness meter, the film thickness is smoothed by normal thickness control. This eliminates the defective outer shape of the product roll, so there is no need for feedback. On the contrary, there is a concern that the outer diameter shape of the product roll will be deteriorated because the discharge amount distribution of the die is excessively adjusted by the feedback.
JP 2001-30339 A

  The object of the present invention is to improve the above-mentioned problems, and the product roll outer diameter shape defect that occurs when there is a thickness measurement error of the thickness gauge, and the product roll outside that occurs when there is no thickness measurement error of the thickness gauge. Disclosed is a method and apparatus for producing a film that distinguishes from a defective shape and always obtains a product roll having a good outer diameter.

  The method for producing a film of the present invention that achieves the above object is to measure the thickness distribution in the width direction of the film when winding the film from which the molten resin is discharged from the die onto the original roll, and based on the measured value of the thickness distribution. In the film manufacturing method for adjusting the discharge amount distribution in the width direction of the base and controlling the thickness of the film, the outer diameter shape data of the raw roll in the previous winding cycle, and the winding cycle in the winding cycle Comparing with the predicted shape data of the outer diameter of the roll roll predicted from the measured thickness distribution value, the correction data obtained from the difference data is added to the measured thickness distribution value and the discharge of the die based on the corrected thickness distribution data The quantity distribution is adjusted.

  Further, in the above manufacturing method, the outer diameter shape data of the original fabric roll is preferably obtained by joining the outer diameter shape values of product rolls obtained by slitting the original fabric roll into a plurality of arbitrary widths. Good.

  Further, the film production apparatus of the present invention is provided with a thickness meter for measuring the thickness distribution in the width direction of the film in a winding process in which the film in which the molten resin is discharged from the die is wound up on a raw roll, In a film manufacturing apparatus provided with a die control device for controlling the thickness of the film by adjusting the discharge amount distribution in the width direction of the die based on the measured value, the outer diameter shape measurement for measuring the outer diameter of the original fabric roll The outer diameter shape data of the original roll in the previous winding cycle measured by the outer diameter shape measuring device by the base control device, and the thickness distribution measured by the thickness meter in the winding cycle. Based on the corrected thickness distribution data obtained by comparing the predicted shape data of the outer diameter of the roll roll predicted from the measured value and adding the correction data obtained from the difference data to the measured thickness distribution value. It is characterized in that the discharge amount distribution was configured to condition.

  According to the film manufacturing method and apparatus of the present invention, the outer diameter shape of the raw roll is measured together with the measurement of the thickness distribution of the film, and the deviation obtained by comparing this with the expected outer diameter shape is the thickness distribution measurement value. The thickness of the film is controlled by feeding back to the film. However, as the basis for obtaining the expected shape data, the measured value of the film thickness distribution is used instead of the fixed target shape as in the prior art. It is possible to distinguish the outer diameter shape defect of the product roll that occurs when there is a thickness measurement error of the thickness and the outer diameter shape defect of the product roll that occurs when there is no thickness measurement error of the thickness meter, and therefore it is always good. A product roll having an outer diameter shape can be obtained.

  The present invention will be specifically described with reference to embodiments shown in the drawings.

  FIG. 1 shows an example of a film forming process used in the present invention.

  The thermoplastic resin is melted by the extruder 1 and supplied to the base 4 through the filter 3 while being quantified by the gear pump 2 at the tip, and is extruded from the base 4 into a sheet shape. The extruded molten resin sheet is cooled and solidified by the cooling roll 5 and then longitudinally stretched in the longitudinal direction by the longitudinal stretching machine 6 in the stretching process, and further laterally stretched in the lateral direction by the lateral stretching machine 7 to form a stretched film 8. After being formed and then wound up in a winding process, a raw roll 10 is obtained.

  Next, the raw roll 10 is sent to a slitting process, where it is slit in the width direction while swinging in the width direction by an operation called oscillation, and the wide original roll 10 is made into a plurality of narrow product rolls 11. To separate. The slit operation by this oscillation does not necessarily have to be performed after winding the raw roll 10, and may be performed in the winding process of the film forming process to directly obtain a plurality of product rolls 11.

  In the winding process of the raw fabric roll 10, a thickness meter 9 is provided immediately before winding the stretched film. The thickness meter 9 measures the thickness distribution of the film by scanning in the width direction of the stretched film 8, and transmits data of the thickness distribution to the die control device 13. The base control device 13 controls the discharge amount distribution in the width direction of the base 4. The thickness gauge is not particularly limited, but a ray transmission type thickness gauge or an optical interference thickness gauge is preferably used.

  The product roll 11 after being divided into a plurality of slits is configured such that the outer diameter distribution in the width direction is measured by the outer diameter shape measuring instrument 12. The outer diameter shape measuring device 12 measures the outer diameter distribution in the width direction of the plurality of product rolls 11 separated from the raw roll 10, and the outer diameter shape data (width direction) obtained from the plurality of product rolls. The outer diameter distribution data) to create outer diameter shape data in the width direction of the original roll (hereinafter referred to as original shape data), and the original shape data is transmitted to the die control device 13. ing.

  As the raw fabric shape data, there is also a method of directly measuring the widthwise outer diameter distribution of the raw fabric roll 10 before being separated into a plurality of product rolls. However, since the raw fabric roll contains a large amount of air between the laminated films as compared with the product roll, there is a peculiarity that the outer diameter shape defect seen in the product roll does not appear in the raw fabric roll. . Therefore, for the purpose of correcting the outer diameter shape defect of the product roll which is the final product, it is desirable to use the product roll outer diameter shape data connected as the raw fabric shape data.

  The die control device 13 includes the film thickness distribution data transmitted from the thickness gauge 9 provided in the winding process of the original roll 10 in the film forming process, and the original fabric shape data obtained from the outer diameter shape measuring instrument 12. Based on the above, the discharge amount distribution adjustment amount in the width direction of the base 3 is calculated, and the adjustment mechanism of the base 3 is operated based on the calculation result to make both the stretched film 8 and the product roll 11 smooth. To do.

  Next, the flow of the film thickness control method of the present invention performed in the die control device 13 will be described with reference to the block diagram of FIG.

  The base control device 13 creates corrected thickness data 20 by adding correction data 19 to be described later to thickness data 18 (thickness distribution data in the film width direction) sent from the thickness gauge 9. Then, the corrected thickness data 20 and the target profile data 24 are input to the thickness control unit 14, the operation amount is calculated so that the corrected thickness data 20 approaches the target profile data 24, and the base 4 is based on the operation amount. The discharge amount distribution in the width direction of the molten resin discharged from is controlled.

  Further, the correction data 19 is obtained as follows. The corrected thickness data 20 is input to the original expected web shape creation unit 15, and the original expected web shape creation unit 15 virtually accumulates the values of the corrected thickness data assuming that the thickness is wound up by the corrected thickness data 20. Thus, the original fabric expected shape data 22 is created. Next, the original fabric expected shape data 22 and the original fabric shape data 21 sent from the outer diameter shape measuring instrument 12 are input to the difference data creation unit 16, and the difference data creation unit 16 feeds the original fabric shape data 21. The difference value 23 is generated by subtracting the value of the original fabric predicted shape data 22 from the value of the value and further converting the difference value into the difference value per film. The created difference data 23 is input to the correction data creation unit 17, and the correction data creation unit 17 adds the value of the difference data to the previous correction data value to create new correction data 19. Then, as described above, the value of the new correction data 19 is added to the value of the thickness data 18 to create the next new corrected thickness data 20.

  The control of the base control device 13 carried out in this way will be specifically described with reference to the profile diagram shown in time series of FIG.

  FIG. 3 shows thickness data 18 (18a to 18d) and correction data 19 (19a to 19a) when the raw roll is wound one by one for each time of times T1 to T2, T3 to T4, T5 to T6, and T7 to T8. 19d), profiles of corrected thickness data 20 (20a to 20d), original fabric shape data 21 (21a to 21d), original fabric expected shape data 21 (21a to 21d), and difference data 23 (23a to 23d) are shown. Yes.

  Since the thickness data 18 (18a to 18d) and the corrected thickness data 20 (20a to 20d) are updated every time the thickness gauge 9 crosses the film, the profiles are arranged from the top to the oldest. For the sake of simplicity, it is assumed that the target profile data is flat. The times T1 to T2, T3 to T4, T5 to T6, and T7 to T8 are times when one roll of raw material is wound, respectively, and times T1, T2, T3, T4, T5, T6 , T7, T8 in this order.

  First, the profile of each data in the time of time T1-T2 is demonstrated.

  The values of the correction data 19a in the initial state are all 0, and the thickness data 18a between the times T1 and T2 are all flat. If the corrected thickness data 20a is created by adding the thickness data 18a and the correction data 19a, the corrected thickness data 20a also has a flat profile. Therefore, the corrected thickness data 20a between times T1 and T2 is integrated / moving averaged. The predicted original fabric shape data 22a has a flat profile. Further, it is assumed that the original fabric shape data 21a wound by film formation between times T1 and T2 has a convex profile at the center. The difference data 23a obtained by subtracting the value of the original fabric expected shape data 22a from the value of the original fabric shape data 21a and converting the value per film is a profile having a convex center. That is, this is the measurement error of the thickness gauge.

  Next, the profile of each data in time from time T3 to T4 will be described.

  The difference data 23a is added to the previous correction data 19a, and the new correction data 19b has a convex profile at the center. Since the thickness data 18b is a flat profile at the beginning of winding, the corrected thickness data 20b obtained by adding the correction data 19b has a convex profile at the center. Since the central portion of the corrected thickness data 20b is convex, an operation amount that flattens the convex portion of the central portion is given to the base 4 in the thickness control unit 14, and the thickness of the central portion of the film becomes thinner as time passes. Go. At the end of winding, the thickness data 18b has a concave profile at the center, and the corrected thickness data 20b obtained by adding the correction data 19b has a flat profile. When the corrected thickness data 20b becomes flat, the operation amount from the thickness control unit 14 is maintained as it is, and the thickness of the film is maintained. The original fabric shape data 21b wound by film formation between times T3 and T4 and the expected original shape data 22b obtained by integrating and moving average the corrected thickness data 20b also have a convex profile at the center. Difference data 23b obtained by subtracting the value of the original fabric expected shape data 22b from the value of the original fabric shape data 21b has a flat profile. That is, the measurement error of the thickness meter is corrected.

  Further, the profile of each data at time T5 to T6 will be described.

  Since the difference data 23b is flat, the new correction data 19c is the same as the previous correction data 19b and has a convex profile at the center. At the beginning of winding, since the thickness data 18c is a concave profile at the center, the corrected thickness data 20c obtained by adding the correction data 19c becomes a flat profile, and the operation amount from the thickness control unit 14 is maintained as it is. Keep the film thickness. Accordingly, since this state continues until the end of winding, each thickness data 18c between times T5 and T6 is a profile having a concave central portion, and each corrected thickness data 20c is a flat profile. The original fabric shape data 21c of the original fabric wound by the film formation between times T5 and T6 and the expected original shape data 22c obtained by integrating / moving the corrected thickness data 20c have a flat profile, and the difference data 23c is A flat profile is obtained. Thereafter, if the film formation is stable, the state at time T5 to T6 is maintained, and a smooth raw roll having an outer diameter shape can be obtained.

  A profile of each data when the film forming state is changed for some reason after time T6 (time T7 to T8) and the thickness of the right end of the fillim is increased will be described.

  The correction data 19d remains a profile with a convex center. At the beginning of winding, since the thickness data 18d is a concave profile at the center, the corrected thickness data 20d obtained by adding the correction data 19d is a profile that rises to the right. Since the corrected thickness data 20d rises to the right, an operation amount for flattening the right end is given to the base 4 in the thickness control unit 14, and the thickness of the right end of the film becomes thinner as time passes. At the end of winding, the thickness data 18d has a concave profile at the center and a flat profile at the right end, and the corrected thickness data 20d obtained by adding the correction data 19d has a flat profile.

  When the corrected thickness data 20d becomes flat, the operation amount from the thickness control unit 14 is maintained as it is, and the thickness of the film is maintained. The original fabric shape data 21d wound by film formation between times T7 and T8, and the expected original shape data 22d obtained by integrating and moving average the corrected thickness data 20d, also have a rising profile. As a result, the difference data 23d has a flat profile, and the subsequent correction data remains the same as the correction data 19d.

  That is, there is a difference between the original fabric shape data 21a and the expected original fabric shape data 22a as between the times T1 and T2. That is, when the corrected thickness data 20a does not reflect the actual film thickness, the correction data 19a needs to be changed, but the original fabric shape 21d and the original fabric expected shape 22d are between time T7 and T8. If there is no difference, that is, if the corrected thickness data 20d reflects the actual film thickness, the outer diameter shape of the product roll will be smooth if the corrected thickness data becomes flat as a result of the operation of the thickness control unit 14. Therefore, there is no need to change the correction data 19d.

  Here, if only the original fabric shape 21d is used to create difference data that rises to the right, and the correction data 19d is updated, the correction is too effective, and the original shape data decreases as time passes. And the outer diameter shape of the product roll is deteriorated. In the present invention, since the difference data is created by the difference between the original fabric shape data and the original fabric expected shape data predicted based on the thickness data, the outer diameter shape of the product roll is thus deteriorated. Absent.

  In the embodiment of the present invention described above, the case of a film forming process of a stretched film has been described. However, the present invention can also be applied to a film forming process of an unstretched film, and the unstretched film is measured with a thickness meter. The same control can be performed with. In addition, the outer diameter shape measuring instrument 12 connects the outer diameter shape data of each product roll 11 to create the original fabric shape data, and transmits the original fabric shape data to the die control device 13. The outer diameter shape data of each product roll 11 may be transmitted from the measuring device 12 to the die control device 13, and the outer shape data may be created by connecting the outer diameter shape data in the die control device 13.

  The film forming apparatus shown in FIG. 1 is used, a radiation transmission type thickness meter using β rays as a radiation source is used as the thickness meter 9, and a contact displacement meter is used as the outer diameter shape measuring device 12. A stretched polyester film having a thickness of about 14 μm was formed by a film thickness control method. FIG. 4 shows the original fabric shape data which is the outer diameter distribution in the width direction of the original fabric before and after the correction data update obtained in this film forming process (film formation at times T1 to T2 and film formation at times T3 to T4). The original fabric expected shape data is shown.

  Comparing the original fabric shape data 24a and the expected original fabric shape data 25a in the film forming process (before correction data update) at times T1 to T2, the original fabric shape data 24a is thicker by about 100 μm at the center and at the right end. The thickness was about 100 μm, and the R value (the difference between the maximum outer diameter and the minimum outer diameter) of the raw fabric shape data 24a was 290 μm.

  Using the difference between the original fabric shape data 24a and the expected original fabric shape data 25a as difference data, the original fabric shape data 24b and the original fabric prediction in the film forming process (before correction data update) at times T3 to T4 when the correction data is updated. When compared with the shape data 25b, the outer diameter shapes of the two are almost the same, and the R value of the original fabric shape data 24b is improved to 170 μm.

It is the schematic which shows an example of the film manufacturing process used for this invention. It is a block diagram which shows the control loop of the nozzle | cap | die control apparatus provided in the film manufacturing process of FIG. It is a profile figure which shows the film thickness control state in this invention. It is a profile figure which shows the result of the Example of this invention.

Explanation of symbols

1 Extruder
2 Gear pump
3 Filter device 4 Cap
5 Cooling drum
6 Longitudinal drawing machine 7 Horizontal drawing machine
8 Stretched film
9 Thickness gauge 10
11 Product roll
12 Outer Diameter Measuring Device 13 Base Control Device
14 Thickness control unit
15 Original fabric expected shape creation unit 16 Difference data creation unit
17 Correction data creation part 18, 18a-18d Thickness data
19, 19a-19d Correction data
20, 20a to 20d Corrected thickness data 21, 21a to 21d Original fabric shape data
22, 22a-22d Original fabric expected shape data 23, 23a-23d Difference data 24a Original fabric shape data 24b before correction data update Original fabric shape data 25a after correction data update Original fabric expected shape data 25b before correction data update Original fabric expected shape data after data update

Claims (4)

When winding a film in which a molten resin is discharged from a die onto a raw roll, the thickness distribution in the width direction of the film is measured, and the discharge amount distribution in the width direction of the die is adjusted based on the measured value of the thickness distribution. In the film manufacturing method for controlling the thickness of the film,
Compare the outer diameter shape data of the original roll in the previous winding cycle with the expected shape data of the outer diameter of the original roll predicted from the measured thickness distribution in the winding cycle, and from the difference data A method for producing a film, comprising adjusting the discharge amount distribution of the die based on corrected thickness distribution data obtained by adding the obtained correction data to the thickness distribution measurement value.   The film production according to claim 1, wherein the outer diameter shape data of the original roll is obtained by connecting the outer diameter shape values of product rolls obtained by slitting the original roll into a plurality of arbitrary widths. Method. A thickness meter for measuring the thickness distribution in the width direction of the film is provided in the winding process of winding the film in which the molten resin is discharged from the die onto the raw roll, and the discharge in the width direction of the die is based on the measured value of the thickness distribution. In the film manufacturing apparatus provided with a die control device that controls the thickness of the film by adjusting the amount distribution,
An outer diameter shape measuring device for measuring the outer diameter of the original fabric roll is provided, and the outer diameter shape data of the original fabric roll in the previous winding cycle measured by the outer diameter shape measuring device by the base control device, and Compared with the expected shape data of the outer diameter of the roll roll, which was predicted from the measured value of the thickness distribution measured with the thickness meter at the winding cycle, and added correction data obtained from the difference data to the measured thickness distribution value. A film manufacturing apparatus configured to adjust a discharge amount distribution of the die based on corrected thickness distribution data. The film production according to claim 3, wherein the outer diameter shape data of the original fabric roll is obtained by connecting the outer diameter shape values of product rolls obtained by slitting the original fabric roll into a plurality of arbitrary widths. apparatus.

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