JPH10119124A - Method and apparatus for producing plastic film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To facilitate speedup and the saving of a space and to perform stretching by setting the product part and edge parts of the film to uniform temp. by heating the plastic film to temp. higher than preheating temp. necessary for raising the temp. of the film to objective stretching temp. SOLUTION: A plastic film 1 is fed from the upstream side in the feed direction of the plastic film 1 to the downstream side thereof through preheating rolls 2-6 equipped with heat treatment devices to be raised in its temp. to an objective stretching temp. When the temp. before the preheating of the film 1 is rapidly raised to the objective stretching temp. from 80 deg.C, for example, to a temp. of 110 deg.C, the set temp. of the preheating roll on the upstream side in the feed direction of the plastic film 1 is set to temp. higher than the objective set temp. For example, the temp. of a product part is raised to temp. higher than the objective stretching temp., for example, by 3 deg.C and the edge part of the film is rapidly raised in temp. and, thereafter, the temp. of the preheating roll is set to the objective set temp. to eliminate the temp. difference between the product part and the edge part at a time of stretching.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for producing a plastic film which continuously stretches a plastic film in a transport direction, and more particularly to a method and an apparatus for producing a plastic film having a heating step of heat-treating the plastic film to a stretching temperature. Related to the device.

[0002]

2. Description of the Related Art Generally, in order to continuously stretch a plastic film in a conveying direction, the film is passed through at least one or more preheating rolls having a heating device, and is heated from a temperature before heat treatment to a predetermined temperature (hereinafter, target stretching). Temperature), and stretching the film at a predetermined magnification between the last stretching heating roll and the cooling roll.

Conventionally, the set temperature of the preheating roll is such that all the preheating rolls are uniform so that the film temperature reaches the target stretching temperature when the amount of heat supplied from the preheating roll and the amount of heat radiated to the outside air are in a steady state. (Hereinafter referred to as target set temperature), or the roll temperature on the upstream side in the film transport direction is set lower than the roll temperature on the downstream side, and the roll temperature before stretching is set to the target set temperature. Was.

[0004]

However, one of the important problems in stretching an unstretched plastic film made of a thermoplastic resin, or at least a plastic film that has already been oriented in the transport direction, is that the plastic film is not easily stretched. How quickly the temperature rises to the target stretching temperature,
Another method is to reduce the temperature difference between the product part and the edge part due to the difference in thickness between the two parts.

For example, when a thermoplastic unstretched plastic film is stretched in the transport direction, the target set temperature in the stretched portion is 90 to 130 ° C., depending on the total stretch ratio or the target degree of orientation after stretching. It is known that the degree is the desired temperature. However, the above temperature is a control temperature of the heat medium (for example, steam) passed through the roll, and the actual surface temperature of the preheating roll has an optimal range somewhat lower than that of the heat transfer, and is 85 to 125.
℃, and the film temperature is 8
0-120 ° C is considered the optimal temperature range.

However, conventionally, the set temperature of the preheating roll is:
All rolls are set uniformly to the set temperature for the film to reach the target stretching temperature.In this case, it takes a considerable time for the film to reach the target stretching temperature, so high speed and space saving In addition to the restrictions, the difference in thickness between the product part and the edge part of the film causes a temperature difference in both the film before stretching, and a difference in orientation due to this temperature difference occurs during stretching. In the process, a difference in heat shrinkage due to a difference in orientation of the film occurs, and at worst, "wrinkles" and "breaks" occur.

The present invention pays attention to the above-mentioned problems in the stretching preheating step, and makes it possible to increase the speed and space saving by rapidly raising the temperature of the film to a target stretching temperature. It is an object of the present invention to provide a method and an apparatus for producing a plastic film, which enable the film to be stretched at a uniform temperature at an edge portion.

[0008]

The present invention has the following configuration to achieve the above object. That is, (1) a method of manufacturing a plastic film in which a molten film is extruded from a slit die, cooled and solidified, and then preheated in at least one preheating region, stretched at least in a transport direction, and wound up. A method for producing a plastic film, comprising heating the plastic film at a temperature higher than a preheating temperature required to raise the temperature of the plastic film to a target stretching temperature in a region.

(2) In the method for producing a plastic film, a molten film is extruded from a slit die, cooled and solidified, preheated in at least one preheating region, stretched at least in a conveying direction, and wound up. In the preheating region, the plastic film is heated at a temperature lower than a preheating temperature necessary to raise the temperature to the target stretching temperature, and before heating at the low temperature, the plastic film is heated to the target stretching temperature. A method for producing a plastic film, comprising heating at a temperature higher than a preheating temperature required for a plastic film.

(3) In a plastic film manufacturing apparatus having at least a slit die, a stretching device, and a winding device, at least one preheating region of the plastic film is provided before the stretching device, and in the preheating region, An apparatus for manufacturing a plastic film, wherein at least one temperature region higher than a preheating temperature required to raise the temperature of the plastic film to a target stretching temperature is provided.

(4) In an apparatus for producing a plastic film having at least a slit die, a stretching device, and a winding device, at least one preheating region of the plastic film is provided before the stretching device, and in the preheating region, Providing at least one temperature region lower than a preheating temperature required to raise the temperature of the plastic film to a target stretching temperature, and a preheating temperature required to raise the temperature of the plastic film to the target stretching temperature before the low temperature region. An apparatus for producing a plastic film, wherein at least one higher temperature region is provided.

(5) The apparatus for producing a plastic film according to (3) or (4), wherein the at least one preheating region is constituted by a preheating roll provided with a heat treatment device.

(6) The apparatus for producing a plastic film according to the above (5), wherein the temperature change of the plastic film per one of the preheating rolls is within 50 degrees.

(7) The surface material of the preheating roll is made of silicone rubber.
Or the manufacturing apparatus of a plastic film as described in (6).

(8) In a plastic film manufacturing apparatus having at least a slit die, a stretching device, and a winding device, at least one preheating region of the plastic film is provided before the stretching device, and at least one of the preheating regions is provided. A film temperature measuring device for the plastic film, and a preheating region temperature controller for controlling the temperature of the preheating region based on a value obtained by the film temperature measuring device. apparatus.

(9) The apparatus for manufacturing a plastic film according to the above (8), further comprising a main controller for controlling a preheating area temperature controller for controlling the temperature of the preheating area. .

[0017]

That is, in the present invention, a temperature region higher than a preheating temperature required to raise the temperature of the plastic film to a target stretching temperature is provided in a plurality of preheating regions.

Accordingly, the temperature of the plastic film can be rapidly raised, and the speed and space can be reduced. In addition, the temperature before stretching caused by the difference in thickness between the product portion and the edge portion of the plastic film can be improved. The difference is eliminated.

When the temperature of the plastic film is once raised to a target stretching temperature and then cooled to the target stretching temperature, the temperature of the plastic film is reduced to a preheating temperature required for cooling the plastic film to the target stretching temperature. By providing a low temperature region and providing a high temperature region before the low temperature region, the plastic film can be rapidly cooled, and as in the above-described embodiment, high speed and space saving can be achieved. This is intended to eliminate a temperature difference before stretching caused by a difference in thickness between the edge portion and the edge portion.

At least two or more preheating regions may be provided, and at least one of the above-mentioned high and low temperature regions may be provided.

When a preheating roll having a heat treatment device is used as the preheating means, the temperature change during the transport of the plastic film per preheating roll is made within 50 ° C., whereby rapid thermal expansion or thermal shrinkage occurs. Generation of "flaws" due to the above can be suppressed.

Further, the plastic film is
When the temperature is raised to at least ° C., by using silicon rubber as the surface material of the preheating roll, it is possible to eliminate the adhesion of the plastic film to the roll in a high temperature region.

Further, a temperature measuring device is provided in the preheating area, the temperature of the plastic film is measured, and a preheating area temperature controller for controlling a set temperature of the preheating area is controlled based on the measurement result. A desired plastic film can be obtained stably.

The preheating zone temperature controller may be manually operated, but a main controller for controlling the entire preheating zone temperature controller is further installed, and a control program is input to the main controller in advance so that a more stable operation can be achieved. Plastic film can be obtained, and human power can be reduced.

Hereinafter, the present invention will be further described based on embodiments shown in the drawings.

FIG. 1 is a perspective view showing an example of a manufacturing apparatus in which the method for manufacturing a plastic film according to the present invention is carried out. It is a perspective view.

In FIG. 1, 1 is a plastic film, 2 is a No. 1 preheating roll, 3 is a No. 2 preheating roll, 4
Indicates a No. 3 preheating roll, 5 indicates a No. 4 preheating roll, and 6 indicates a No. 5 preheating roll. Reference numeral 7 denotes a film thickness gauge for measuring the thickness of the film, and reference numeral 8 denotes a temperature measuring device for measuring the temperature of the film.

9 is a No. 1 preheating roll temperature controller, 10 is a No. 2 preheating roll temperature controller, and 11 is a No. 2 preheating roll temperature controller.
No. 3 preheating roll temperature controller, 12 is a No. 4 preheating roll temperature controller, 13 is a No. 5 preheating roll temperature controller, and 14 is a main controller. As shown in FIG. A measuring device 8 is provided to measure the temperature of the plastic film 1 being conveyed, and to control the preheating roll temperature controllers 9 to 13 for controlling the set temperature of the preheating roll based on the result, to stably control the target plastic film 1. Can be obtained. Although the preheating roll temperature controller may be manually operated, as shown in FIG. 1, a main controller 14 that comprehensively controls the preheating roll temperature controller is further installed, and by inputting a control program to the main controller 14 in advance, The desired plastic film can be obtained more stably, and human power can be reduced.

The means for preheating the plastic film is not particularly limited, but a general method is to preheat the plastic film by a preheating roll provided with a heat treatment device (steam is passed when the temperature is raised and cold water is passed when cooling). is there.

The material of the surface of the roll is not particularly limited, but when silicon rubber is used, it is possible to eliminate the sticking of the plastic film to the roll which occurs during the high-temperature heat treatment.

In the present invention, the set temperature of the preheating zone or the preheating roll depends on the thermal properties of the plastic film,
The thickness is set according to the film thickness, the roll material, and the desired heating time.

[0032]

An embodiment of the present invention will be described below with reference to the accompanying drawings.

FIGS. 2 and 4 show the measurement results obtained by the present example, and FIGS. 3 and 5 show the measurement results obtained by the comparative example.

In FIG. 1, a plastic film 1
With preheating rolls 2, 3, 4, 5, 6 equipped with a heat treatment device.
And transports the plastic film 1 from the upstream side to the downstream side in the transport direction, and raises the temperature to the target stretching temperature.

The plastic film used is polyethylene terephthalate, and the thickness and physical properties are as follows.

Thickness [μm] 100 Thermal conductivity [W / (m · K)] 0.3 Specific heat [kJ / (kg · K)] 1.5 Density [kg / m ³ ] 1.4 × 10 ³ It is on the street.

Number of pieces 5 pieces Outer diameter φ100 mm Surface material Silicon rubber roll The physical properties of the silicon rubber are as follows.

Thickness [mm] 5 Thermal conductivity [W / (m · K)] 0.2 Specific heat [kJ / (kg · K)] 1.6 Density [kg / m ³ ] 1000 Surface roughness 1 s Transport speed of plastic film Is as follows.

Transport speed [m / min] 5 The horizontal axis in FIGS. 2 to 5 indicates the transport time of the plastic, and the time when the plastic film starts to contact the No. 1 preheating roll 2 is defined as 0 second. I have. The vertical axis indicates the measured value of the temperature of the plastic film during transportation measured by the contact thermometer 8 in FIG. 1. The product film thickness 100 μm measured by the film thickness meter 7 in FIG. Two types of temperature gradients having a film thickness of 500 μm are shown.

(1) When the temperature is rapidly raised from the pre-heating temperature of 80 ° C. to the target stretching temperature of 110 ° C.

The set temperatures of the preheating rolls that were implemented are shown below.

Example 1 is a case where the set temperature of the preheating roll on the upstream side in the transport direction of the plastic film of the present invention is set higher than the target set temperature. In Comparative Example 1, the set temperatures of all the preheating rolls were set uniformly.

No. 1 roll No. 2 roll No. 3 roll No. 4 roll No. 5 roll Example 1 100 ° C. 130 ° C. 120 ° C. 120 ° C. 120 ° C. Comparative Example 1 120 ° C. 120 ° C. 120 ° C. 120 ° C. 120 ° C. 2 and FIG. 3 show the results of implementation based on Example 1 and Comparative Example 1, respectively.

As can be seen from FIG. 3, in the case of Comparative Example 1, it took 13.2 seconds (on the No. 5 roll) until the temperature of the plastic film reached the target stretching temperature. In the case of 9.5 seconds (N
o.4 Roll only), and as a result, by setting the set temperature of the roll as in Example 1,
Since only four rolls, which required books, are required, preheating space can be reduced, and
If five rolls were used as before, the speed could be increased to 7.9 m / min.

As can be seen from FIG. 3, in the case of Comparative Example 1, the edge portion (500 μm) of the plastic film was used.
m) cannot reach the target stretching temperature because the heat capacity is larger than that of the product part (100 μm), and there is a difference between the two temperatures in the stretching part. In the case of Example 1, the temperature of the product part is 3 ° C. from the target stretching temperature.
By raising the temperature to a high temperature and rapidly raising the temperature of the edge portion, and then setting the preheating roll temperature to the target set temperature, it was possible to eliminate the temperature difference between the product portion and the edge portion during stretching.

Further, the plastic film does not stick to the preheating roll, and the plastic film is rapidly stretched.
No flaws occurred.

(2) A case where the temperature of the plastic film is once raised to a target stretching temperature and then cooled to the target stretching temperature.

The roll set temperatures performed are shown below.

In the second embodiment, the temperature of the No. 2 roll is set to be higher than the preheating temperature required for raising the temperature to the target high temperature,
After that, set the preheating roll temperature required to raise the temperature to the target high temperature with the No. 3 roll, and when cooling to the stretching temperature, once set it below the preheating temperature required for the target stretching temperature. Finally, the target stretching temperature is set.

In Comparative Example 2, the temperature of the No. 2 and No. 3 rolls was set to the preheating roll temperature required to raise the temperature to the target high temperature, and No. 4 and No. 5 were set to the target stretching temperature. The required preheating roll temperature is set.

No. 1 roll No. 2 roll No. 3 roll No. 4 roll No. 5 roll Example 2 120 ° C. 150 ° C. 140 ° C. 110 ° C. 120 ° C. Comparative Example 2 120 ° C. 140 ° C. 140 ° C. 120 ° C. 120 ° C. 4 and FIG. 5 show the results of implementation based on Example 2 and Comparative Example 2, respectively.

As can be seen from FIG. 5, in the case of Comparative Example 2, the product portion of the plastic film cannot not only be heated to the target high temperature but also cannot be cooled to the target stretching temperature. In addition, there is a temperature difference between the product part and the edge part before stretching.

On the other hand, in the case of Example 2, as can be seen from FIG. 4, the temperature of the product portion of the plastic film can be quickly raised to a target high temperature, and further, it can be rapidly cooled to the target stretching temperature. In addition to the above, the temperature difference between the product portion and the edge portion before stretching was able to be eliminated.

Also, the plastic film does not stick to the preheating roll, and the plastic film is rapidly stretched.
No flaws occurred.

[0055]

According to the method and apparatus for producing a plastic film of the present invention, in the method and apparatus for producing a plastic film for continuously stretching a plastic film in the stretching direction, the temperature of the plastic film is raised to a target stretching temperature. In this case, since the temperature can be rapidly raised to the target temperature, the space required for the preheating can be reduced, or the speed can be increased without adding additional equipment.

Further, by eliminating the temperature difference of the film before stretching caused by the difference in thickness between the product portion and the edge portion of the film, the orientation unevenness caused by stretching the film having the temperature difference, or the orientation unevenness due to stretching. "Wrinkles" and "breaks" of the film caused by the above can be eliminated.

Further, when a preheating roll provided with a heat treatment device is used as the preheating means for the plastic film, the temperature change of the plastic film per one preheating roll is set to 50 ° C. or less, so that a rapid change can be achieved. The generation of “flaws” due to thermal elongation or thermal shrinkage can be suppressed.
When the temperature is raised to 0 ° C. or higher, by using silicon rubber as the surface material of the preheating roll, it is possible to eliminate sticking of the plastic film to the roll which occurs during high-temperature heat treatment.

Also, at least one film temperature measuring device for the plastic film is provided in at least one of the preheating regions, and the film temperature detected by the temperature measuring device is fed back to the temperature in the preheating region to reduce human power. And the desired film can be stably obtained.

[Brief description of the drawings]

FIG. 1 is a perspective view of a manufacturing apparatus in which a plastic film manufacturing method of the present invention is performed.

FIG. 2 is a graph showing the results of implementation based on Example 1 of the present invention and showing the relationship between the plastic transport time and the temperature of the plastic film.

FIG. 3 is a graph showing the results of implementation based on Comparative Example 1 of the present invention and showing the relationship between the plastic transport time and the temperature of the plastic film.

FIG. 4 is a graph showing a result of the embodiment 2 of the present invention and showing a relationship between a plastic transport time and a temperature of a plastic film.

FIG. 5 is a graph showing the results of implementation based on Comparative Example 2 of the present invention and showing the relationship between the plastic transport time and the temperature of the plastic film.

[Explanation of symbols]

 1: plastic film 2: No. 1 preheating roll 3: No. 2 preheating roll 4: No. 3 preheating roll 5: No. 4 preheating roll 6: No. 5 preheating roll 7: film thickness gauge 8: temperature measuring device 9 : No.1 preheating roll temperature controller 10: No.2 preheating roll temperature controller 11: No.3 preheating roll temperature controller 12: No.4 preheating roll temperature controller 13: No.5 preheating roll temperature controller 14: Main controller

Claims (9)

[Claims] 1. A method for producing a plastic film in which a molten film is extruded from a slit die, cooled and solidified, then preheated in at least one preheating region, stretched at least in a conveying direction, and wound up. A method for producing a plastic film, comprising heating the plastic film at a temperature higher than a preheating temperature required to raise the temperature of the plastic film to a target stretching temperature in a region. 2. A method for producing a plastic film, wherein a molten film is extruded from a slit die, cooled and solidified, then preheated in at least one preheating region, stretched at least in a conveying direction, and wound up. In the region, while heating the plastic film at a temperature lower than the preheating temperature required to raise the temperature of the plastic film to the target stretching temperature, and before heating the plastic film to the target stretching temperature, heating the plastic film to the target stretching temperature. A method for producing a plastic film, comprising heating at a temperature higher than a required preheating temperature. 3. A plastic film manufacturing apparatus having at least a slit die, a stretching device, and a winding device, wherein at least one preheating region of the plastic film is provided before the stretching device. An apparatus for producing a plastic film, wherein at least one temperature region higher than a preheating temperature required to raise the temperature of the plastic film to a target stretching temperature is provided. 4. A plastic film manufacturing apparatus having at least a slit die, a stretching device, and a winding device, wherein at least one preheating region of the plastic film is provided before the stretching device. At least one temperature region lower than a preheating temperature required to raise the temperature of the plastic film to the target stretching temperature is provided, and the temperature is higher than a preheating temperature required to raise the temperature of the plastic film to the target stretching temperature before the lower temperature region. An apparatus for producing a plastic film, wherein at least one high temperature region is provided. 5. The plastic film manufacturing apparatus according to claim 3, wherein said at least one preheating region is constituted by a preheating roll provided with a heat treatment device. 6. The plastic film manufacturing apparatus according to claim 5, wherein a temperature change of the plastic film per one of the preheating rolls is within 50 degrees. 7. The preheating roll according to claim 5, wherein a surface material of the preheating roll is made of silicone rubber.
2. The apparatus for producing a plastic film according to 1. 8. A plastic film manufacturing apparatus having at least a slit die, a stretching device, and a winding device, wherein at least one preheating region of the plastic film is provided before the stretching device, and at least one of the preheating regions is provided. A film temperature measuring device for the plastic film, and a preheating region temperature controller for controlling the temperature of the preheating region according to a value obtained by the film temperature measuring device. . 9. The plastic film manufacturing apparatus according to claim 8, further comprising a main controller for controlling a preheating area temperature controller for controlling the temperature of the preheating area.