JPS647573B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a film. More specifically, the present invention relates to a method for producing a thermoplastic resin film with little thickness fluctuation by a calendar molding method.

When manufacturing a film using the calendar molding method,
After heating and kneading on the rolls of a calendar device, the mixture is rolled with rolls, stretched, and cooled to form a film of a predetermined thickness, processed into a predetermined width with a slitter, and then wound with a winder to form a film roll.

In the production of the film, making the film uniform in thickness from one end to the other is as follows:
It is extremely difficult. Normally, when the thickness of a film is measured in the width direction, changes in thickness such as thinner, thicker, or thinner films appear. For this reason, even if a film with such uneven thickness is wound into a roll, the result is a defective product with variations in the diameter of the rolled roll.

The change in film thickness due to the calendering method may be due to insufficient spacing adjustment between the penultimate roll and the last roll of the calendering device.
This is thought to be caused by a defect in a mechanical part other than the roll spacing, by a change in the amount of resin discharged from the roll spacing, or by temperature unevenness on the roll surface.

Conventionally known methods for correcting the non-uniform film thickness caused by the above phenomenon into a uniform film include the following methods.

(b) Measure the thickness using various film thickness measuring devices, and adjust the amount of resin supplied to the calender roll, resin temperature, roll temperature, and roll spacing to correct for uneven areas based on the measured values and the experience of the operator. , a method of adjusting the amount of stretching, cooling conditions, etc.

(b) Measure the thickness using various film thickness measuring devices, and feed back the measured values to a roll spacing adjustment device, a roll bending device that bends one roll at the center, etc., to determine the film thickness. How to adjust the brightness.

However, method (a) above requires constant monitoring by skilled workers. There is a shortage of skilled workers these days, and this method is not sustainable.

On the other hand, method (b) is more practical than method (b), but has the following drawbacks. That is, for example,
When measuring the thickness of a film using a Beta wire thickness gauge, the thickness measuring device measures each position on the film while moving in the width direction of the film, but the film does not move in the longitudinal direction. Therefore, the thickness obtained by measurement includes not only the thickness change in the width direction but also the thickness change in the longitudinal direction. Therefore, even if the data based on the measurement results are fed back to the calendar device for adjustment, the thickness of the film cannot be uniformly corrected, and the result is sometimes worse than before the adjustment. Film manufacturing speed (line speed)
When the amount is large, the above-mentioned problems are likely to occur, resulting in extremely low manufacturing reliability.

The present inventors have completed the present invention as a result of intensive studies to eliminate the above-mentioned problems in the calender forming method, which requires a high film production speed (line speed), and to provide a method for producing a film with less thickness fluctuation. It is ivy.

Therefore, the gist of the present invention is to provide a molten resin rolling zone consisting of at least three rolls;
When manufacturing a film using a device equipped with a film take-off zone, a film widening zone, a film cooling zone, a film winding zone, etc., there is a A plurality of heaters are arranged at regular intervals in the direction so that each heater can be independently controlled, and the thermoplastic resin is rolled into a film, expanded, cooled, and then wound in a winding zone. The method of manufacturing a film is characterized in that the diameter distribution of the film roll after the film roll is completed is detected, and the electric power applied to the heater is adjusted in accordance with the detected diameter distribution.

Hereinafter, the present invention will be explained in detail based on the drawings, but the present invention is not limited to the following examples.

FIG. 1 is a schematic diagram of an example of a device used in carrying out the present invention, FIG. 2 is a schematic plan view showing an example of the arrangement of heaters, and FIG. 3 is a schematic diagram of an example of a film roll diameter measuring device. It is.

In the figure, 1 is the final roll, 2 is the second roll, 3 is the third roll, 4 is the front roll, 5 and 6 are take-off rolls, 7 is the film spreading device, 8 is the pin, 9 is the cooling zone, and 10 is the roll,
11 is a binaural cutting device; 12 and 31 are each a winding core; 13, 14 and 32 are each a film roll; 15 is a diameter measuring device; 16 is an arithmetic circuit; 17 is an amplifier; 18 is a terminal for inputting a setting command signal; 19 is an amplifier for setting command signals, 20 is an arithmetic unit, 21 is an operating device, 22 is a power source, 23 is a variable resistor for power adjustment, 24 is a heater, 25 is wiring,
26 and 27 are films, 33 is a pressure roll, and 34 is a differential transformer.

In the present invention, an apparatus with a molten resin rolling zone consisting of at least three rolls is used. This rolling zone is an area where the molten resin is rolled into a film. An example of a combination of rolls is a combination of a normal calender device, such as an inverted L type,
It may be I type, L type, Z type, etc.

A film take-off zone is provided next to the rolling zone. This film take-off zone is an area where the film rolled in the rolling zone is taken off. As for the combination of rolls in the film take-off zone, two rolls may be combined as shown in FIG. 1, or three or more rolls may be combined.

A film widening zone is provided next to the film take-off zone. This film widening zone is an area where the film is widened within a range that does not cause molecular orientation in the film. To widen the film, both edges of the film 26 are held and widened to form a wide film 27. To hold both sides of the film, use a pin tenter, clamp, etc.
A conventionally known widening device may be installed.

A film cooling zone and a film winding zone are provided after the film widening zone.

In the present invention, a plurality of heaters are arranged at regular intervals in a direction perpendicular to the film traveling direction at appropriate locations in the film take-off zone or the film widening zone, and each heater can be independently controlled. do.

The heater may be placed in either the film take-off zone or the film widening zone. When disposed in the film take-off zone, it is disposed in parallel to either one of the take-off rolls 5 or 6 along the central axis of the take-off roll. The heater may be arranged so as to directly heat the film or may be arranged so as to heat the surface of the take-off roll. When the heater is disposed in the film widening zone, it is disposed on the entrance side of the film widening zone at right angles to the film traveling direction.

FIG. 1 shows an example in which the heater 24 is arranged on the entrance side of the film widening zone.

The heaters are thus arranged at regular intervals in a direction perpendicular to the direction of travel of the film at appropriate locations in the film take-off zone or the film widening zone. A plurality of heaters are combined, and each heater can be controlled independently. In this way, partial thickness fluctuations in the width direction of the film can be easily and preferably corrected by adjusting the voltage applied to the heater.

FIG. 2 shows an example in which the heater 24 is arranged in a direction perpendicular to the traveling direction of the film 26 (indicated by an arrow in the figure). The heater 24 is
It is composed of a plurality of blocks, and each block is connected to a power source 22 by a wiring 25. Furthermore, an example is shown in which a plurality of power adjustment variable resistors 23 are installed in the middle of the wiring 25 (between the heater 24 and the power source 22) in correspondence with the heater blocks.

A film cooling zone and a film winding zone are provided after the film widening zone. The film cooling zone is an area where the film widened in the widening zone is cooled to around room temperature. In the cooling zone, a method may be adopted in which the film is passed between a plurality of rolls, or a method in which this is combined with a method in which air cooled to room temperature or below room temperature is blown onto the film.

The film winding zone is an area where the cooled film is wound into a roll. In the film winding zone, a conventionally known film winding device can be employed.

In the present invention, the diameter distribution of the film roll after winding is completed is detected, and the power of the heater is adjusted in accordance with the detected diameter distribution.

In order to detect the diameter distribution of the film roll, it is preferable to use a film roll diameter measuring device, an example of which is schematically shown in FIG. In the example shown in FIG. 3, the presser rolls 33 are placed on the intersection line of the cut surface that appears on the surface of the film roll when the film roll is cut along the length direction through the central axis. 32 are placed facing each other, and while they are facing each other, they are moved back and forth along the dotted line in Figure 3. At this time, the diameter of the film roll 32 can be detected by connecting the shaft of the presser roll 33 to the differential transformer 34.

There may be one set of film roll diameter measuring instruments, but two or more sets may also be arranged. When two or more sets are arranged, it is preferable to change their arrangement positions so that they do not collide with each other when reciprocating on the film roll.

The signal measured by the film roll diameter measuring device 15 is sent to an arithmetic circuit 16 comprising an integrating circuit, a dividing circuit, and the like. The signal from the arithmetic circuit 16 is amplified by the amplifier 17, and the output signal of the amplifier 17 is input to the arithmetic device 20.

The relationship between the number of film windings on the film core and the diameter of the film roll is calculated or actually measured in advance, and this is input from the setting command signal input terminal 18, and this signal is input to the amplifier 19. and amplify it. The signal from the amplifier 19 and the signal from the amplifier 17 based on the actual measurement by the film roll diameter measuring device 15 are compared and calculated by the arithmetic unit 20. The calculation result by the calculation device 20 is inputted to the operation device 21 as a correction signal, and the power adjustment variable resistor 23 is thereby adjusted, and the heater 2
4. Apply electricity to the necessary blocks and heat them.

For example, when the thickness of the film suddenly increases in some areas, this phenomenon is detected by the diameter measuring device 15 of the film lawn, and this detection signal is sent to the arithmetic unit via the arithmetic circuit 16 and amplifier 17. Sent to 20th. On the other hand, in the calculation device 20, the actual measurement value is compared with the target value (the value inputted from the setting command input terminal 18), and the calculation result is inputted to the operation device 21 as a correction signal. The amount of electricity applied to the heater in the part corresponding to the bent part is increased to heat the film, and when the film is widened in the film widening zone, it works so that the film thickness becomes the same as other parts.

For every 60 film rolls (core diameter 72 mm, film roll diameter approx. 440 mm, film width 3000 mm) of soft blended polyvinyl chloride film continuously produced according to the method of the present invention, the diameter in the film width direction is measured for one film roll. Measurements were taken at 20 locations, and the horizontal axis represents the difference between the maximum and minimum values, and the vertical axis represents the frequency of occurrence, as shown in Figure 4. In the example shown in this figure, the average value of the difference between the maximum and minimum values is
It was 0.73mm.

In addition, while manually adjusting the film thickness using the conventional method, a film roll (approximately the same size as above) of soft blended polyvinyl chloride film was prepared.
Continuously manufacture 60 rolls of film, measure the diameter of these film rolls in the same way as above, find the difference between the maximum and minimum values (shown on the horizontal axis), and calculate the frequency of appearance (shown on the vertical axis). It is shown in Figure 5. In the example shown in this figure, the average difference between the maximum and minimum values is 1.03
It was warm in mm.

From FIGS. 4 and 5, it is clear that when the method of the present invention is used, the fluctuation in the diameter difference of the film roll is reduced.

The present invention has the following particularly remarkable effects, and its industrial utility value is extremely large.

(1) In the film manufacturing process, rolling, widening,
Changes in film thickness caused by cooling, winding, and other factors are detected by a diameter measuring device on the wound film roll after the final process, and the diameter distribution is used as a variable resistor setting signal for adjusting the power of the heater. By sending a correction signal to
Film thickness can be adjusted to be uniform.
This allows quick response to changes, and corrects using measured values in the final state that include all factors, allowing for accurate operations.

(2) In addition, since the diameter distribution of the film roll is measured in the width direction of the film, it is possible to measure each position in the width direction, and it does not include unnecessary factors like conventional thickness measurements, which improves accuracy. It is possible to produce a film with a uniform thickness by easily detecting the temperature and automatically applying the necessary amount of power only to the necessary parts of the heater.

(3) When using the method of the present invention, the diameter of the wound film roll can be controlled, and a film roll with a uniform diameter without uneven diameter distribution can be obtained.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of an example of a device used in carrying out the present invention, FIG. 2 is a schematic plan view showing an example of the arrangement of heaters, and FIG. 3 is a schematic diagram of an example of a film roll diameter measuring device. , Figure 4 shows the diameters of 60 film rolls of soft blended polyvinyl chloride film produced continuously by the method of the present invention measured in the width direction of the film, the difference between the maximum value and the minimum value determined, and the diameter FIG. 5 is similar to FIG. 4 for 60 film rolls manufactured by the conventional method. In the figure, 1 is the final roll, 2 is the second roll, 3 is the third roll, 4 is the front roll, 5 and 6 are take-off rolls, 7 is the film spreading device, 8 is the pin, 9 is the cooling zone, and 10 is the roll,
11 is a binaural cutting device; 12 and 31 are each a winding core; 13, 14 and 32 are each a film roll; 15 is a diameter measuring device; 16 is an arithmetic circuit; 17 is an amplifier; 18 is a terminal for inputting a setting command signal; 19 is an amplifier for setting command signals, 20 is an arithmetic unit, 21 is an operating device, 22 is a power source, 23 is a variable resistor for power adjustment, 24 is a heater, 25 is wiring,
26 and 27 are films, 33 is a pressure roll, and 34 is a differential transformer.

Claims (1)

[Claims] 1. When manufacturing a film using a device equipped with a molten resin rolling zone, a film take-off zone, a film widening zone, a film cooling zone, a film winding zone, etc. consisting of at least three rolls, the film take-off zone or the film widening zone is A plurality of heaters are arranged at regular intervals in a direction perpendicular to the direction of film travel, and each heater can be controlled independently, and the thermoplastic resin is rolled into a film and expanded. After cooling, the film roll is wound in a winding zone, and the diameter distribution of the film roll after winding is completed is detected, and the electric power applied to the heater is adjusted in accordance with the detected diameter distribution. Film manufacturing method.