JP2002510564A - Method and apparatus for producing plastic film - Google Patents

Abstract

(57) [Summary] A method and apparatus for producing a plastic film, wherein an annular film preform is extruded by an extruder 1. The extruder 1 comprises a nozzle 6 for spreading and flattening the annular film preform into a flat film 5.

Description

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to a method for producing a plastic film, comprising extruding an annular plastic film preform with an extruder.

[0002] The present invention also relates to an apparatus for producing a plastic film, comprising an extruder for extruding an annular plastic film preform. U.S. Pat. No. 3,244,781, U.S. Pat. No. 3,891,374 and EP-A-0,182,764 describe apparatuses for producing plastic films. These solutions involve extruding an annular plastic film preform, then orienting the preform by a mandrel or air blast, and then, for example, rolling the preform by a roll. Flattening into a flat plastic film. However, this method of producing flat plastic films is complicated and difficult, and the equipment required is expensive.

[0003] It is an object of the present invention to provide a simple and effective method and apparatus for producing flat plastic films. The method according to the invention is characterized in that the extruder comprises a nozzle for expanding the annular film preform and flattening the preform into a flat film.

[0004] The device of the invention is characterized in that the extruder is provided with a nozzle for expanding the annular film preform and flattening the preform into a flat film. The basic idea of the present invention is that an annular film preform is extruded by an extruder, which extrudes the annular film preform and flattens the annular film preform. It is to provide a nozzle for forming a film. The idea in one preferred embodiment is that the nozzles of the extruder are arranged to widen to the end of the extruder.

[0005] One advantage of the present invention is that flat films can be produced very simply and effectively. When the extruder nozzle is arranged to extend to the end of the extruder, the plastic to be extruded is always transversely oriented, in addition to being oriented longitudinally, which means that Greatly facilitates the transverse orientation of the plastic film in a later processing stage.

[0006] The invention will be described in more detail with reference to the following drawings. FIG. 1 is a side view of an apparatus according to the present invention. The device comprises an extruder 1. The extruder is conical, ie the extruder has a conical rotor 2
Outside the rotor, there is an outer rotor whose outer surface 3 at least on the side of the rotor 2 is conical, inside the rotor at least its surface on the side of the rotor 2 is conical Preferably, there is some inner stator 4. In that case, there is an annular feed gap in the form of a tapered cone inside and outside the rotor. When the rotor 2 rotates, it consists of a rotor 2 and a stator 3,
4 is extruded from the extruder 1 in a manner known per se.
The basic structure of such an extruder is disclosed, for example, in EP 0,422,042. For the sake of clarity, these figures do not show, for example, the rotor for feeding the material to be extruded into the extruder 1 or the rotating means of the feeding device. The extruder 1 can include one or more rotors 2 and two or more stators 3 and 4. In this case, the extruder 1 can be used for extruding a multilayer product. An arrangement with one rotor 2 and two stators 3, 4 can be used to produce a two-layer product. The end portion of the inner stator 4 is wide and vertically tapered, so that the inner stator together with the nozzle 6 forms a relatively flat and wide air gap through which the plastic 5a Is extruded. The inner stator 4 can be formed, for example, in two parts, in which case the end part of the inner stator is attached to the front part. After the nozzle 6, there is a calibration piece 7, the nut of which is used to adjust the height of the gap, the calibration piece 7 defining the thickness of the plastic film 5 obtained from the extruder 1. To make it possible.

After the extruder 1, the plastic film 5 is cooled by a cooling device 8. The cooling device 8 can include, for example, a cooling roll 9 disposed in a cooling tank 10 that holds a cooling medium such as water. The plastic film 5 is arranged so that it can be pressed against the cooling roll 9. The device according to FIG. 1 uses an auxiliary roll 11 for guiding the plastic film 5 at several points.

After cooling, the plastic film 5 is guided to a machine direction orienting device 12. The machine direction orienting device 12 comprises an orienting roll 13 whose speed can be adjusted to stretch the plastic film 5 and thus be used to orient in the machine direction. it can. If desired
The speed of such orienting rolls 13 can be adjusted separately. The machine direction determining device 12 can also comprise a heating means 14 such as a radiant heater for heating the plastic film 5 in a manner known per se. A heating medium, such as heated oil, is supplied to the orienting rolls 13
Orienting roll 1 to heat plastic film by warming
3 can also be used. If desired, the temperature of each orientation roll 13 can be adjusted separately.

The orienting roll is located in the discharge chamber 15. Pressurized gas, preferably air, is supplied into the exhaust chamber 15 along a gas supply pipe 16. Instead of air, for example, nitrogen or another gas or gas mixture can be used as the gas to be supplied. The gas to be supplied can also be selected according to the desired electrical properties. For example, it is desirable to use sulfur hexafluoride SF ₆ with respect to the electrical strength of the preform of the product and to use, for example, argon from the viewpoint of chargeability. The pressure of the gas to be supplied is relatively low compared to a typical foaming process and is preferably about 1000 kpa (about 10 bar), for example 300 kpa (3 bar) to 2000 kpa (20 bar). Can be changed within the range. A suitable material, such as particles of calcium carbonate, is mixed into the plastic 5a of the plastic film 5 and, due to the effect of the plastic, the interface between the plastic molecule and the mixed material is torn during orientation, so that Cavitation bubbles are formed. When oriented by placing a pressurized gas to act on the plastic film 5, the gas diffuses in the cavitation bubbles and creates overpressure in the bubbles. Discharge chamber 1
In 5, the pressurized gas acts on both sides of the plastic film 5, so that gas bubbles are formed uniformly in the plastic film 5. The discharge chamber 15 is sealed at the entrance and exit of the plastic film 5 in a manner known per se.

Behind the machine direction orienting device 12, the plastic film 5 is fed to a transverse direction orienting device 17. In the transverse orientation device 17, the plastic film 5 is stretched in the transverse direction, ie, oriented in a direction substantially perpendicular to the orientation direction performed in the machine direction orientation device 12. . Due to the overpressure and transverse stretching of the gas in the foam, the foam grows laterally and to some extent vertically in the transverse orientation device 17. In this case, the degree of foaming of the film is, for example, about 70 to 90%. The degree of foaming can be adjusted only by adjusting the pressure of the gas supplied into the discharge chamber 15. The transverse orienting device 17 comprises two orienting wheels 18, on each of which a steering band 19 is arranged. The orientation band 19 is an endless band guided by a band guide roll 20. The edge of the plastic film 5 is arranged between a directional wheel 18 and a directional band 19. The orienting band 19 applies the edge of the plastic film 5 firmly and uniformly between the orienting wheel 18 and the orienting band 19 along substantially the entire direction of travel of the transverse orienting device 17. Pressing, in which case the film is not subjected to changing pressure stress or tensile strain, so that the plastic film stretches in the transverse direction without tearing. In FIG. 1, for clarity, the plastic film 5, the orienting wheel 18 and the orienting band 19 are shown at a distance from each other, but in practice these parts are pressed firmly against each other. . The orientation wheel 18 and the orientation band 19 are oriented in the direction of the plastic film as shown in FIG.
It is more separated from one another at the end than at the start, so that the transverse orientation device 17 stretches the plastic film 5 and at the same time orients it in the transverse direction. The angle of displacement from the machine direction between the steering wheel 18 and the steering band 19 can be adjusted according to the desired degree of elongation in the cross-sectional direction. One or more band guide rolls 20 can be arranged to be rotatable by the rotating means. Since the band 19 is firmly pressed against the directional wheel 18, the directional wheel 18 does not necessarily need a rotating means, but can be rotatable. For clarity, the accompanying drawings include:
The rotating means or other actuators of the device are not shown. A curved support plate 21 having substantially the same shape as the outer circumference of the orientation wheel 18 is disposed between the orientation wheels 18 and supports the plastic film 5.

The cross-sectional direction determining device 17 can itself be arranged in the casing 26. If desired, the casing 26 can be provided with a heater known per se, such as a radiant heater, for heating the plastic film 5.

The plastic film 5 is introduced into the relaxation device 22 behind the device 17 for determining the cross-sectional direction. In the relaxation device 22, the plastic film 5 relaxes, so that it shrinks slightly in a manner known per se. Finally, the plastic film 5 is wound around the reel 23.

FIG. 2 is a sectional view of the apparatus of the present invention in the extruder 1. For clarity, FIG. 2 does not show the plastic film 5 and the support structure of the device to which, for example, the rolls, reels and plates of the device are mounted.

FIG. 3 is a detailed sectional view of the extruder 1 along the line AA in FIG. In this case, both the outer stator and the inner stator 4 are circular in cross section. Thus, the plastic material 5a is also in the annular supply passage, ie at this stage,
The extruder forms an annular plastic film preform directly from the material without requiring any intermediate steps.

FIG. 4 is a cross-sectional view of a detail of the extruder 1 along the line BB of FIG. In this case, the wide end of the inner stator 4 and the plastic 5a are extruded into a wide and flat gap so that the flat plastic film 5 is formed from the annular plastic film preform. The shape of the nozzle 6 is illustrated. If the first plastic material 5a supplied on the outside of the rotor 2 is different from the second plastic material 5a 'supplied on the inside of the rotor 2, a two-layer annular plastic film preform is initially After that, a multilayer plastic film 5 is obtained.

FIG. 5 is a cross-sectional view of a detail of the transverse directing device 17 along line CC of FIG. In FIG. 5, it can be seen how the orientation wheel and the orientation band are pressed against each other and the plastic film 5 is pressed between each other.
The surface of the support plate 21 with respect to the plastic film 5 can be heated, for example, by providing a heating resistor on the surface.
Slides very easily along the sliding surface. Further, a gap 21a is formed from the support plate 21.
A propellant such as air is blown out through the gap, in which case the propellant flowing through the gap 21 a provides a sliding bearing between the support plate 21 and the plastic film 5. If desired, the gas can be heated, thus supporting plate 21
Is heated by the propellant flowing through the gap 21a.

FIG. 6 shows an extruder 1 used in an apparatus according to the invention. The nozzle 6 of the extruder 1 widens to the end of the extruder, ie to the point where the plastic film 5 exits the extruder 1. At the nozzle 6 of the extruder 1, the plastic 5a is always oriented in the cross-section in addition to its longitudinal orientation, which means that during the subsequent processing stage the plastic film is oriented transversely. Makes decisions much easier.

The plastic film 5 can be used for several purposes in a manner known per se. At least one surface of the plastic film 5 can be provided, for example, with a conductive coating, for example as a microphone or a loudspeaker in some acoustic applications with sound attenuation. Can be used. Further, the plastic film 5 can be permanently charged.

The drawings and the related description are only intended to illustrate the idea of the invention. The details of the invention can be varied within the scope of the claims.

[Brief description of the drawings]

FIG. 1 is a schematic side sectional view of the apparatus of the present invention.

FIG. 2 is a partial sectional view of the apparatus shown in FIG.

3 is a sectional view of a detail of the device shown in FIG. 1 along line AA.

FIG. 4 is a sectional view of a detail of the device shown in FIG. 1 along line BB.

5 is a cross-sectional view of a detail of the device shown in FIG. 1 along line CC.

FIG. 6 is a schematic sectional view of an extruder used in the apparatus of the present invention.

[Procedural Amendment] Submission of translation of Article 34 Amendment of the Patent Cooperation Treaty

[Submission date] October 19, 1999 (1999.10.19)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claims

[Correction method] Change

[Correction contents]

[Claims]

──────────────────────────────────────────────────続 き Continuation of front page (81) Designated country EP (AT, BE, CH, CY, DE, DK, ES, FI, FR, GB, GR, IE, IT, LU, MC, NL, PT, SE ), OA (BF, BJ, CF, CG, CI, CM, GA, GN, GW, ML, MR, NE, SN, TD, TG), AP (GH, GM, KE, LS, MW, SD, SL, SZ, UG, ZW), EA (AM, AZ, BY, KG, KZ, MD, RU, TJ, TM), AE, AL, AM, AT, AU, AZ, BA, BB, BG, BR , BY, CA, CH, CN, CU, CZ, DE, DK, EE, ES, FI, GB, GD, GE, GH, GM, HR, HU, ID, IL, IN, IS , JP, KE, KG, KP, KR, KZ, LC, LK, LR, LS, LT, LU, LV, MD, MG, MK, MN, MW, MX, NO, NZ, PL, PT, RO, RU, SD, SE, SG, SI, SK, SL, TJ, TM, TR, TT, UA, UG, US, UZ, VN, YU, ZA, ZW (71) Applicant Route du Bois 37 CH-1024 Ecublens / Lausanne, Switcherland F-term (reference) 4F100 AA08A AA08C AA08H AK01A AK01B AK01C BA03 BA06 BA10A BA10C DJ06A DJ06C EH202 EJ38 EJ382 GB90 4F201 AB16 BC01 AG03 BC01 AG03 BC02 KA01 KA11 KA17 KB22 KL58 KL80 KL84 KL88

Claims (10)

[Claims] 1. A method for producing a plastic film, comprising forming an annular plastic film preform with an extruder (1), wherein the extruder (1) spreads and flattens the annular film preform. And a flat film (
5) A method characterized by comprising a nozzle (6). 2. The method according to claim 1, wherein the film (5) comprises a nozzle (6).
) To the end of the extruder (1). 3. The method according to claim 1, wherein the thickness of the plastic film (5) is adjusted by adjusting the height of a gap in the calibration piece (7) of the extruder (1). The method. 4. The method according to claim 1, wherein at least one two-layer annular plastic film preform is extruded by an extruder (1), and the preform is flattened. A multilayer film (5). 5. The method according to claim 1, wherein the extruder (1) comprises at least one rotor (2) and at least one stator (3, 3).
4), characterized in that there is an annular feed gap in the form of a tapered cone between the rotor (2) and the stator (3, 4). 6. An apparatus for producing a plastic film, comprising an extruder (1) for extruding an annular film preform, wherein the extruder (1) expands and flattens the annular film preform. Device comprising a nozzle (6) for flattening the film (5). 7. The apparatus according to claim 6, wherein the nozzle (6) is provided with an extruder (6).
Device, characterized in that it is arranged to extend to the end portion of 1). 8. The device according to claim 7, comprising a calibration strip (7), the thickness of the film (5) being adjusted by adjusting the height of a gap in the calibration strip (7). Device, characterized in that it can be adjusted in the extruder (1). 9. The apparatus according to claim 6, wherein the extruder (1) comprises at least one two-layer annular film preform for producing a multilayer film (5). An apparatus characterized in that it is arranged to be extrudable. 10. An apparatus according to claim 6, wherein the extruder (1) comprises at least one rotor (2) and at least one stator (2).
3, 4), at least the surfaces of which contact each other are in the shape of a cone,
Apparatus characterized in that an annular supply gap in the form of a tapered cone is formed therebetween.