FI107321B - Method and apparatus for making a plastic film - Google Patents

Description

107321

METHOD AND APPARATUS FOR MANUFACTURE OF A PLASTIC FILM

The present invention relates to a process for making a plastic film, which method comprises extruding a plastic material with an extruder comprising at least one rotor and at least one stator, to form a plastic film blank on the rotor and stator and apply and flatten the film blank to obtain a flat film.

The invention further relates to a device for making a plastic film, which device comprises an extruder having at least one rotor 10 and at least one stator adapted to form a film blank and a nozzle adapted to apply and flatten the film blank to provide a flat film. 891 374 and EP 0 182 764 disclose apparatus for making a plastic film. In such solutions, the annular plastic film blank is extruded and then oriented by means of a mandrel or air blast and then flattened, for example, by rolls to provide a flat plastic film. However, such a method of manufacturing a flat plastic film is complicated and cumbersome and expensive in terms of hardware.

U.S. Patent No. 3,079,634 discloses a solution wherein the pulp from the extruder die is compressed into a rod-like shape after the screw. Following the extruder, a nozzle is provided for first shaping the pulp into an annular shape and then applying and flattening the pulp over the film.

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'·;' to obtain.

It is an object of the present invention to provide a simple and efficient process and apparatus for making a flat plastic film.

v .: The process of the invention is characterized in that: T: the rotor and stator form an annular plastic film blank and that the nozzle is in contact with an extruder so that the plastic film blank is retained until the nozzle is spread and lithium · ♦ ·. rotating the rotor and stator annular film blank * · * to produce a flat film.

Further, the device according to the invention is characterized in that the rotor and stator are arranged to form an annular diaphragm blank and the nozzle is arranged in connection with an extruder so that the diaphragm blank is arranged to remain annular up to the nozzle, -------------------------------------------------- ---- i -} ---------

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i t 107321! 2 adapted to spread and flatten the perforated membrane blank formed by the rotor and stator to provide a flat film.

An essential idea of the invention is to extrude an annular film blank, and the extruder further includes an extruder for applying and flattening the annular film blank to form a flat film. The idea of a preferred embodiment is that the nozzle in the extruder is adapted to expand to the remainder of your extruder.

An advantage of the invention is that the flat films can be obtained in time; 10 very simply and efficiently. By adjusting the nozzles n j of the extruder to expand to the end of the extruder, the n is extruded | in addition to the longitudinal orientation of the plastic at all times, $ I sold the transverse orientation, resulting in later orientation of the plastic film> -! the transverse direction is also greatly facilitated during this processing step. The invention will be explained in more detail in the accompanying drawings, in which Fig. 1 schematically shows an embodiment of the invention in the devices! viewed from the side and in cross-section; Fig. 2 shows a top view of the apparatus of Fig. 1 and partly in section, Fig. 3 shows a detail line / r of the apparatus of Fig. 1;

A along the section, I

. . Fig. 4 shows a detail of the apparatus of Fig. 1, taken along line ψ \ B, and

Figure 5 shows a detail line d: - I of the apparatus of Figure 1

: 25 C along the section and! Fig. 6 schematically shows a top view and a cross-section of an extruder for use in a device according to the invention.

Figure 1 is a side elevational view of the apparatus according to the invention. The apparatus includes an extruder 1. The extruder 1 is preferably * i. ·· ♦, i.e. conical, with a conical rotor 2, jor k a j •; a cone at least on the face of the rotor 2 is disposed on the outside; in the form of an outer stator 3 having a cone-shaped inner stator 4 having at least a rotatable side 2 on the inside thereof. The inside and outside of the 35 rotors have an annular tapered cone shape *! * * * <'I <<; nipple. As rotor 2 rotates, it compresses rotor 2 and stator 3 | and | 4 3 107321 4 out of the extruder 1 in a manner known per se. The basic construction of such an extruder is disclosed, for example, in EP 0 422 042. For the sake of clarity, for example, rotor rotating devices and feeding devices for supplying extrudable material to the extruder 5 are not shown in the accompanying figures. The extruder 1 may have more than one rotor 2 and more than two stators 3 and 4. In this case, the extruder 1 can be used to extrude multilayer products. With the solution of one rotor 2 and two stators 3 and 4, double layer products can be made. The remainder of the inner stator 4 is formed wide and tapered in the height 10 so as to form, together with the nozzle 6, a reasonably shallow and wide opening through which the plastic 5a is pressed. The inner stator 4 can be made, for example, of two parts, whereby the remainder of the inner stator is attached to the initial part. After the nozzle 6, a calibration piece 7 is further fitted, the nuts 15 being further adjusted by means of the nuts, whereby the thickness of the plastic film 5 protruding from the extruder 1 can be determined.

After the extruder 1, the plastic film 5 is cooled by a cooling device 8. The cooling device 8 may include, for example, a cooling roll 9 fitted to a cooling tank 10 containing a cooling medium, e.g. water,. In controlling the plastic film 5 in the apparatus of Figure 1, . the use of auxiliary rollers at several points 11.

After cooling, the plastic film 5 is guided to a machine-oriented '··· ’orientation device 12. The machine-oriented orientation device 12 comprises: 25 orientation rolls 13, whose speeds are adjusted to: • stretch the plastic film 5 and thus orientate in the machine direction. If desired: V: the speed of each orientation roll 13 can be individually adjusted. The machine oriented orientation device 12 may also include heating means 14, such as radiant heaters, for heating the plastic film 5 in a manner known per se. The plastic film 5 can also be heated by means of orientation rolls 13 such that: ···. heating medium, such as heated oil * '*, is supplied to the orientation rollers 13 so that the orientation rollers 13 are heated. If desired, the temperature of each stall roller 13 can be individually adjusted.

Orientation rollers 13 are mounted in pressure chamber 15. In pressure chamber: ·! The pressurized gas, most preferably air, is supplied via a gas supply line ["S, 16. Instead, the supply gas may be, for example, nitrogen or another gas or gas mixture. The gas to be supplied may also be selected For example, a good gas for the breakthrough strength of the product would be sulfur hexafluoride SF6 and a good gas for storage would be, for example, argon 5. The pressure of the feed gas is quite low compared to typical foaming methods, preferably about 10. bar, but may vary between, for example, 3 and 20. Barrier material 5, such as calcium carbonate particles, is mixed with plastic 5a of the plastic film 5, which causes the plastic molecules and the mixed material to tear during orientation to form cavitation bubbles. I Fr. orienting is performed so that the plastic film 5 is exposed to a pressurized gas, which gas diffuses into the cavitation bubbles and creates a pressure therein. In the pressure chamber 15, the pressurized gas is exposed to πύο- | on both sides of the defective film 5, whereby a uniform amount of gas is formed in the plastic film 5. The pressure chamber 15 is sealed with seals inside the plastic film 5 · a | at exit points in a manner known per se.

After the machine orientation device 12, the plastic film 5 is conductor In the transverse orientation device 17, the plastic film 5 is stretched in the transverse direction, i.e. the orientation j 20 takes place in a direction substantially perpendicular to the orientation in the machine orientation device 12. In the transverse orientation, j. . because of the gas overpressure and the transverse stretches in the bubbles of the device 17, the bubbles are able to grow laterally and also slightly in the height of j * ·; Thus, for example, the film is about 70 to 90 percent i

: 25 foamed. The degree of foaming can simply be adjusted by pressure chamber

• e * is 15 by adjusting the pressure of the gas supplied. Transverse stallion; v !: the actuator 17 has two orienting wheels 18 and each of them responds nj: T: the orienting belt 19 is fitted. The orienting belt 19 is an endless pattern and is guided by the roll guide rollers 20. The edges of the plastic film 5 are fitted between the orientation tape 19. Then the plastic fish! . ···. The edges of von 5 are substantially the entire transverse orientation device 17 j β | * · * Travel smoothly with the orienting band 19 heavily pressed between the orienting band j 19 and the orienting wheel 18, whereby the film is not subjected to silicon-like compression or tensile stress and thus the plastic film stretches in the side-35 direction without tearing. In Fig. 1, the plastic film 5 and the orientation wheel 13 and the orientation tape 19 are drawn for clarity to one another at a distance 5,107,321, but in reality the parts are pressed tightly against each other. Orientation wheels 18 and orienting straps 19, respectively, are arranged so that they are further spaced apart in the direction of travel of the plastic film 5 as initially shown in Figure 2, whereby the transverse orientation device 17 stretches and at the same time orientates the plastic film 5 in transverse direction. The angle deviation of the orientation wheels 18 and the orientation ribs 19 from the machine direction can be adjusted to adjust the desired amount of transverse stretching. One or more belt guide rollers 20 may be adapted to be rotated by means of rotation means. Since the strips 19 are tia-10 obliquely pressed against the orientation wheels 18, the rotation devices 18 are not necessarily required for the orientation wheels 18, but they can rotate freely. For clarity, the accompanying figures do not show the rotation and other controls of the device. A plastic film 5 is disposed between the guide wheels 18 to support a substantially curved support plate 21 corresponding to the circumference of the guide wheels 18.

The transverse orientation device 17 may be mounted in its own housing 24. If desired, heaters known per se, such as radiant heaters, for heating the plastic film 5 may be arranged in connection with the housing 24.

After the transverse orientation device 17, the plastic film 5 is led to the relaxation unit 22. In the relaxation unit 22, the plastic film 5 relaxes. . whereby the plastic film shrinks slightly in a manner known per se. Finally «« '; the plastic film 5 is wound onto a roll 23.

In Fig. 2, the apparatus according to the invention is shown in a top view, · 25 in cross-section at the extruder 1. For the sake of clarity, Figure 2 does not show the plastic film 5 or the supporting structures of the apparatus to which, for example, the rolls and rollers of the apparatus and the plates are fixed.

Fig. 3 shows a detail of the extruder 1 in cross-section along line A-A in Fig. 1. At this point, both the outer stator 30 and the inner stator 4 are circular in cross-section. Herein, the plastic material 5a is also in the annular feed channel, i.e. the extruder has an annular plastic film blank formed at this stage.

Figure 4 shows a detail of the extruder 1 in cross-section along line B-B of Figure 1. At this point is shown the wide tip of the inner stator 4 and the shape of the nozzle 6 which acts on the plastic 5a '. squeezed into a wide and shallow slot, making the annular plastic film ani! ί [107321! A flat plastic film 5 is formed 5. If the first plastic material 5a fed outside the rotor 2 is different from the second plastic material 5a 'fed inside the rotor 2, it is first provided with two layers

an annular plastic film blank followed by a multilayer plastic film 6. I

Fig. 5 is a cross-sectional view of the transverse orientation device 17 taken along line C-C in Fig. 1. Figure 5 shows the orientation wheel of the dimension j and the orientation tape wedging against each other, squeezing the φ j junction of the plastic film 5. The support plate 21 may be formed such that its surface facing the plastic film 5 is heated, for example by fitting the heating resistor 10 along the sliding surface very easily. Further, propellant gas can be blown from inside the support plate 21, for example air through the openings 21a, whereby the gas of pony * - j leaking through the openings 21a creates a sliding bearing between the support plate 21 and the plastic film 5. If desired, the gas may be heated so that the sliding surfaces · of the support plate 21; 15 and the plastic film 5 are heated by propellant gas flowing through the openings 21a

Fig. 6 shows an extruder 1 for use in the device according to the invention. The nozzle 6 of said extruder 1 extends to the end of the extruder, that is, where the plastic film 5i comes out of the extruder 1. In this case, in addition to the longitudinal orientation of time, m) the transverse orientation of j3, whereby the orientation of the plastic film 5 is delayed. . in this processing step, the transverse direction is also greatly facilitated.

The plastic film 5 can be used for a variety of applications s- '··; his nose in known ways. For example, an electrically conductive coating may be applied to the surface of the plastic film 5, at least on one side, whereby such solutions may be used, for example, as a microphone or speaker in a variety of acoustic applications, e.g. Plastic material) : T: 5 can also be permanently electronically charged. !

The drawings and the description related thereto are for illustrative purposes only 30 countries inventing ideas. The details of the invention may vary within the scope of the claims.

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Claims (10)

A method of making a plastic film, in which the plastic material is pressed with an extruder (1) comprising at least one rotor 5 (2) and at least one stator (3, 4), such that a plastic foil preform is formed by means of the rotor ( 2) and the stator (3, 4) and the foil preform are propagated and flattened with a nozzle (6) so that a flat foil (5) is formed, characterized in that an annular plastic foil preform is formed by means of the rotor (2) and the stator (3, 4). ) and that the nozzle (6) is arranged in conjunction with the extruder (1) so that the plastic foil preform is held annular to the nozzle (6), the annular foil preform formed by the rotor (2) and the stator (3, 4). is spread and flattened with the nozzle (6) so that a flat film (5) is produced. Method according to claim 1, characterized in that the nozzle (6) is part of the extruder (1) and that the foil (5) is spread with the nozzle (6) all the way to the end part of the extruder (1). Method according to claim 1 or 2, characterized in that the thickness of the plastic film (5) is controlled by controlling the height of the gap in a calibration piece (7) adjacent to the extruder (1). Method according to any of the preceding claims, characterized in that at least one bilayer annular foil preform is pressed with the extruder (1), which preform is flattened into a multilayer foil (5). ^. Method according to any of the preceding claims, characterized in that the extruder (1) comprises at least one rotor (2) and at least one stator (3, 4) so that between the rotor (2) and the stator (3, 4). ) there is an annular feed gap in the form of a tapered cone. • · 6. Apparatus for producing a plastic film, said device comprising an extruder (1) comprising at least one rotor (2) and at least one stator (3, 4), which are arranged to form a foil preform and a nozzle (6). , which is arranged to propagate and flatten the foil preform to provide a flat foil (5), characterized in that the rotor (2) and the stator (3, 4) are adjacent. arranged to form an annular plastic foil preform and the nozzle (6) is arranged in connection with the extruder (1) so that the plastic foil preform is arranged to be poured annularly to the nozzle (6), the nozzle (6) being arranged to extend and flatten the annular formed by the rotor (2) and the stator (3, 4): ·. The foil preform to provide a flat foil (5). • · ------------------------------------------------------- I ^ j ------------- 10732¾ i 7. Device according to claim 6, characterized by the nozzle 1! (6) is a part of the extruder (1) and the nozzle (6) is arranged to be wider to the end portion of the extruder (1). Device according to claim 7, characterized in that the arrangement comprises a calibration device arranged in conjunction with the extruder (1) | piece (7) for controlling the thickness of the foil (5) by controlling the height of the gap in the calibration piece (7). Device according to any of claims 6-8, characterized in that the extruder (1) is arranged to press an at least two-layer in annular foil preform to produce a multilayer foil (5). ] Device according to any one of claims 6-9, characterized in; in that the extruder (1) comprises at least one rotor (2) and at least e in the stator (3, 4), whose at least abutting surfaces are cone shaped. that an annular gap with a tapered cone is formed between them. • «*« · j • · I * · I | : j • »! 2 • · · • · · · •, • «! • · · • · · • β • · «* • · ·! «· ·; ! • i * · ** · | | . ···. ! ... · i •! * 1 »<«, * ·! «<