WATER REMOVAL DEVICE

Abstract

The present invention relates to a water removal device 200 for removing water from a film, a casting device 14 comprising a water removal device, and a system 10 for producing a film, comprising a corresponding casting device. The water removal device 200 comprises at least one mechanical water removal device, as well as a first blow-off device and a second blow-off device, each comprising blow-off nozzles, wherein the blow-off nozzles 220a, 220c; 222a, 222b are configured to direct an airflow L onto the film in order to blow entrained water off the film F over a film edge.

Description

Field of invention

[0001] The invention relates to a water removal device for removing water from a film, a casting device comprising a water removal device and a system for producing a film, comprising a corresponding casting device. background

[0002] In the production of thin plastic films, a molten plastic is first extruded and applied to a cooling roller, where it cools and at least partially solidifies (cast film). To cool the extruded film or cast film and subsequently feed it into a stretching machine, the extruded film is typically passed through a water bath.

[0003] The water bath results in homogeneous and rapid cooling; however, the water must be removed from the film before the film is fed to the stretching machine, especially a longitudinal stretching machine.

[0004] This water removal is important because water carried on the film could enter the stretching machine and evaporate there. A typical longitudinal stretching machine includes heated rollers. Water still present on the film surface would evaporate on these rollers, creating steam bubbles between the film and the roller. These steam bubbles lift the film from the roller and prevent the film from heating evenly. This impairs the stretching result, leading to poor film quality or even film tearing.

[0005] Furthermore, the evaporation of water on the rollers leads to residues, such as limescale. Although demineralized water is typically used in the water baths, the evaporation of this demineralized water is still not completely residue-free.

[0006] If water evaporates from the roller surface over a longer period of time, the roller can be permanently damaged by the deposits, especially since mechanical cleaning of the rollers is not possible, as this would lead to scratches in the roller surface and consequently to poor film quality.

[0007] Known water removal devices that dry the film before it is fed into the stretching machine often achieve an insufficient degree of drying. Furthermore, these devices are unsuitable for the high production speeds of, for example, at least 140 m / min (measured at the cooling roller), as are now required. This is because high production speeds result in the film carrying more water from the water bath while simultaneously allowing less time for water removal. Consequently, particularly at high production speeds, the water is not sufficiently removed from the film and ultimately enters the stretching machine. Description of the invention

[0008] It is therefore an object of the present invention to provide an improved water removal device for film production.

[0009] The problem is solved by a water removal device according to claim 1, as well as by the casting device and the apparatus for producing a film according to the further claims. Further aspects of the invention are described in the dependent claims and in the following description.

[0010] In particular, the problem is solved by a water removal device for removing water from a film. The water removal device can be used especially in the production of cast films.

[0011] The water removal device comprises a film inlet opening and a film outlet opening and is configured to guide the film along a film web from the film inlet opening to the film outlet opening. The film web is the path the film takes as it passes through the water removal device. It is determined, in particular, by the positioning of rollers such as deflection rollers, nip rollers, pressure rollers, and / or the like. The rollers can be driven or non-driven. Preferably, at least one driven pressure roller is provided, which is configured to convey the film through the water removal device.

[0012] The water removal device comprises at least one mechanical water removal device and at least one first and one second blow-off device. The water can thus be removed from the film surface in two different ways: mechanically and by blowing. This achieves a particularly high water removal rate, even at high film speeds. The blow-off devices are preferably located downstream of the mechanical water removal device, i.e., arranged after the mechanical water removal device in the film take-off direction.

[0013] The mechanical water removal device comprises at least two water removal elements arranged opposite each other on opposite sides of the film web. For example, a first water removal element and a second water removal element are arranged on the top side of the film web, such that the two water removal elements guide the film between them.

[0014] The water removal elements apply a crushing force to the film. This crushing force causes the water on the surface of the film to be squeezed off and thus mechanically removed.

[0015] The mechanical water removal device, for example, forms a first water removal stage of the water removal system. In this case, it can be located downstream of the water removal system's inlet opening.

[0016] Optionally, a second mechanical water removal device can be provided, for example, downstream of the first. This second mechanical water removal device also has two water removal elements, arranged opposite each other on opposite sides of the film web. These two water removal elements are designed to apply a squeezing force to the film. Thus, any remaining water at a second position on the film web, different from the first, can be squeezed off the top of the film and mechanically removed.

[0017] The water removal elements of the first and / or second water removal device can, for example, be designed as squeeze rollers. The opposing squeeze rollers form a pair of squeeze rollers through which the film is guided. Mechanical water removal takes place during this process.

[0018] The squeeze rollers can be coated with an elastic material such as rubber, silicone, TPU (thermoplastic polyurethane), or similar. This increases the water-squeezing effect.

[0019] Furthermore, a pair of squeeze rollers can consist of two rollers of the same size or rollers of different sizes. For example, the rollers may have a diameter in the range of 100 mm to 200 mm, or in the range of 120 mm to 180 mm, or in the range of 140 mm to 160 mm. It has been shown that this achieves a good water squeeze-out effect.

[0020] Furthermore, at least one squeezing roller of the first and / or second water removal unit can be coupled to an actuator. In particular, at least one squeezing roller of a pair of squeezing rollers can be coupled to an actuator. The actuator can comprise a linear drive or a lever that allows the squeezing roller to pivot. The squeezing force and / or the wrap angle of the roller can be adjusted via the actuator. A squeezing roller of a pair of squeezing rollers that is not coupled to an actuator can, for example, be spring-mounted.

[0021] The first blow-off device of the water removal device according to the invention comprises at least one first blow-off nozzle and at least one second blow-off nozzle. The first blow-off nozzle(s) is / are arranged on a first side of the film web and the second blow-off nozzle(s) is / are arranged on a second side of the film web.

[0022] Accordingly, the second blow-off device of the water removal device according to the invention comprises at least a first blow-off nozzle and at least a second blow-off nozzle. The first blow-off nozzle(s) is / are arranged on a first side of the film web and the second blow-off nozzle(s) is / are arranged on a second side of the film web.

[0023] The blow-off nozzles are designed to direct an airflow onto the film in order to blow away any water it carries, at least along one edge. The water is thus blown from the center of the film over the left and / or right edge.

[0024] Since the first blow-off nozzles of the first and second blow-off devices are located on the first side of the film web, this first side of the film can be blown off at two different positions. At the latest after passing the second blow-off device, the first side of the film is (almost completely) free of water. The same applies to the second blow-off nozzles of the first and second blow-off devices, which are located at different positions on the second side of the film web.

[0025] At least one (or several, or all) blow-off nozzle can be associated with a blow-off roller. The associated blow-off roller is positioned opposite the blow-off nozzle (i.e., on the opposite side of the film web) to support the film in the area being blown off by the nozzle. This makes it possible to direct an airflow onto the film with a sufficiently high pressure and / or flow rate to effectively blow off the water without permanently deforming the film.

[0026] At least one of the blow-off nozzles can be a slot nozzle oriented essentially transversely to the direction in which the film web is pulled. In this case, the slot nozzle is aligned parallel to the transverse direction of the film web. Alternatively, the slot nozzle can form an angle β with the transverse direction of the film web, which lies in the range of 1° to 45°, or in the range of 10° to 30°, or in the range of 15° to 20°.

[0027] The width of the slot nozzle can be selected so that it essentially spans the entire film web in the transverse direction. It is also possible to provide several first (or second) blow-off nozzles in a blow-off device. These can be arranged so that together they span the entire film web in the transverse direction, with the edge areas of the blow-off nozzles potentially overlapping. It is also possible to provide several blow-off nozzles in a blow-off device, arranged sequentially in the take-off direction.

[0028] The slot nozzle can include at least one airflow outlet gap designed to generate a uniform, essentially laminar airflow. This airflow can be directed onto the film in such a way as to blow water off one or both edges of the film.

[0029] To achieve this, the slot nozzle can be configured to direct the airflow onto the film in such a way that it has a transverse flow component. In particular, the airflow can be inclined relative to the film web normal, with the angle between the airflow and the film web normal being in the range of 1° to 5° or 2° to 4°. The inclination of the airflow can be achieved by a corresponding inclination of the slot nozzle and / or by a corresponding design of the airflow outlet gap. This inclination results in particularly effective blow-off.

[0030] The water removal device may further comprise at least one left and / or right edge blow-off device, which is / are downstream of the first and second blow-off devices. The left edge blow-off device is assigned to a left edge of the film, and the right edge blow-off device is assigned to a right edge of the film.

[0031] The edge blow-off devices can each comprise a first edge blow-off nozzle and at least one second edge blow-off nozzle. The first edge blow-off nozzle is located on one side of the film web, and the second edge blow-off nozzle is located on the other side of the film web, opposite the first edge blow-off nozzle. The first and second edge blow-off nozzles are thus positioned on opposite sides of the film web in essentially the same locations. The edge blow-off device blows off only the edge of the film. The airflow generated here does not cover the entire film, but only its edges. This allows any water adhering to the film edge to be blown off.

[0032] Furthermore, the water removal device may include at least one air drying and / or air temperature control device. This device may be configured to provide air supplied to the first blow-off device, the second blow-off device, the left-edge blow-off device, and / or the right-edge blow-off device to generate an airflow, with a defined humidity and / or temperature.

[0033] The air drying and / or air temperature control device can provide air with different temperatures and / or humidity levels to the different blow-off devices, or several air drying and / or air temperature control devices can be provided, each assigned to one of the blow-off devices.

[0034] For example, the air drying and / or air temperature control device can provide air at temperature T1 to the first blow-off device, air at temperature T2 to the second blow-off device, and air at temperature T3 to the edge blow-off devices, where, for example, the following relationship applies: T1≤T2≤T3

[0035] This has the advantage that the film is already (pre-)tempered for the typically subsequent longitudinal and / or transverse stretching.

[0036] Furthermore, the air drying and / or air temperature control device may include a filter so that filtered air can be supplied to the blow-off devices.

[0037] Furthermore, the first blow-off device, the second blow-off device, the left edge blow-off device and / or the right edge blow-off device can be configured to provide the airflow at a defined airflow rate and / or a defined pressure.

[0038] For example, the second blow-off device can provide an airflow with a higher airflow rate and / or pressure than the airflow provided by the first blow-off device. The airflow provided by the edge blow-off devices can have a further increased pressure and / or airflow rate.

[0039] It is also possible that the second blow-off device provides an airflow with a lower airflow rate and / or lower pressure than the airflow provided by the first blow-off device. The airflow provided by the edge blow-off devices may have a further reduced pressure and / or a further reduced airflow rate.

[0040] In one aspect, the first blow-off device provides an airflow with an initial pressure and volume. The initial pressure can, for example, be in the range of 0.5 to 1.1 bar, or in the range of 0.6 to 0.8 bar. The initial volume of air can, for example, be in the range of 1000 m³ / h. 3 / h up to 1600 m 3 / h, or within a range of 1200 m 3 up to 1400 m 3The second, subsequent blow-off device could then provide a second airflow with a second pressure and a second airflow rate, where the second pressure is increased and the second airflow rate is reduced. This pressure and / or airflow rate distribution allows the first blow-off device to blow off a large portion of the water from the film surface. The remaining moisture or droplets can then be removed (with high pressure) in the second blow-off device.

[0041] The water removal device can further comprise a main body and at least one flap element. Preferably, the water removal device comprises at least two flap elements.

[0042] The at least one flap element is pivotably mounted on the main body to be moved from a first position to a second position. In the first position, the water removal device is in an operating position, and in the second position, it is in a maintenance position. In the maintenance position, for example, a film can be inserted into the water removal device, or film can be removed from the water removal device after a malfunction, such as a film tear. For this purpose, the main body is separated from the at least one flap element along the film web.

[0043] Furthermore, the water removal device can include an air extraction system designed to draw moist air from the device's housing. This can further increase the efficiency of the water removal device.

[0044] The task is further solved by a casting device for the production of plastic films, wherein the casting device comprises a cooling roller, a take-off roller, at least one water bath and a water removal device of the type described above.

[0045] The cooling roll is designed to cool a polymer melt extruded onto its surface to produce a film. The take-off roll is located downstream of the cooling roll and is designed to peel the film away from the cooling roll. In particular, the cooling roll can be configured to rotate at a speed sufficient to peel the film at a film speed of at least 120 m / min, or at least 130 m / min, or at least 140 m / min, or at least 150 m / min, or at least 160 m / min.

[0046] The water bath is arranged so that the film is guided through it in the casting unit. For example, the cooling roller, and optionally the take-off roller, can be at least partially submerged in the water bath. Alternatively or additionally, a water bath can be located downstream of the take-off roller, through which the film is guided (e.g., via appropriate deflection rollers).

[0047] The water removal device is arranged so that the film passes through the water removal device before leaving the casting device in order to remove water from the surface of the film.

[0048] Furthermore, the casting device can include a water treatment system, in particular a water softening system, wherein the water treatment system is designed to treat the water of at least one water bath. In particular, impurities such as limescale and / or other residues can be removed from the water of the water bath. This can improve the film quality.

[0049] Furthermore, the problem is solved by a system for producing a film, wherein the system comprises at least a device for supplying a polymer melt and the casting device described above. The device for supplying a polymer melt can comprise an extrusion die, an extruder, and / or a reactor. In particular, the device for supplying a polymer melt can be configured to extrude the polymer melt onto the cooling roller.

[0050] The extruder can be set up to provide a plastic melt (e.g. PE, PP, PET, ...).

[0051] A reactor can be set up to produce the polymer melt via polymerization. For this purpose, the monomers (and optional additives, such as catalysts) are mixed and polymerized in the reactor. The resulting polymerized polymer melt can then be fed to an extrusion die and extruded onto the cooling roller, eliminating the need for an additional extruder.

[0052] Furthermore, the system can include a stretching unit downstream of the casting device, which is configured to stretch the film F longitudinally and / or transversely. Stretching in the longitudinal and transverse directions can be performed simultaneously or sequentially. Brief description of the characters

[0053] The invention is explained in more detail below with reference to the accompanying figures. Here, it shows Fig. 1 a schematic representation of a plant for the production of a film; Fig. 2 an exemplary casting device; Fig. 3 an isometric representation of a water removal device; Fig. 4 a sectional view of the water removal device Fig. 3; Fig. 5 schematically the blowing off of the foil in a first variant, and Fig. 6 schematically the blowing off of the foil in a second variant. Description of the characters

[0054] Fig. Figure 1 shows in a highly schematic manner a system 10 for the production of a film F, which includes several different devices and systems.

[0055] In the example shown, the system 10 comprises an extrusion unit 12, a casting unit 14, at least one longitudinal drawing unit 16 (MDO, "Machine Direction Orienter"), a transverse drawing unit 18 (TDO, "Transverse Direction Orienter"), an optional treatment unit 20, and a winding unit 24. The optional treatment unit 20 can be a separate assembly or, for example, integrated into the winding unit 24.

[0056] The extrusion plant 12 has at least one extruder 120 and / or a melt feed line from a reactor and is designed to produce a melt from at least one feedstock. The feedstock can include, for example, plastic granules, plastic powder, recycled plastic, additives and / or the like.

[0057] At least one extruder can be a single-screw extruder, a cascade extruder, a twin-screw extruder, a planetary roller extruder, and / or the like. It is also conceivable that other mixing and processing units, such as a co-kneader, are used.

[0058] The generated melt is applied (via an optional melt supply line 122) to a cooling roller 142 of the casting device 14 using an extrusion die, such as a slot die 126, thereby producing a film F. An optional application device 128 is provided (see...). Fig. 2) which allows the melt exiting the extrusion die to be precisely placed onto the cooling roller and fixed there. This precise placement results in uniform cooling and high-quality film surfaces.

[0059] It is also possible to produce the polymer melt by means of polymerization. For this purpose, the monomers (and optionally additives, such as catalysts) are mixed and polymerized in a reactor and / or an extruder. The resulting polymerized polymer melt can be applied via melt line 122 through the extrusion die (e.g., slot die 126) onto the cooling roller 142 of the casting device 14, thereby producing a film F.

[0060] The extruded film F can have one or more layers. In the case of a multi-layered film, it is conceivable that one extruder produces several or all layers, or that a separate extruder is provided for each layer.

[0061] After passing through the casting device 14, the film F is fed to a longitudinal stretching unit 16 in the example shown here. In this unit, the film is stretched and thus lengthened in a first direction, i.e., in the take-off direction A.

[0062] The subsequent transverse stretching unit 18, as described, for example, in DE 10 2021 128 332 A1, has an oven 30 with different zones for tempering the film F along the usual direction of movement or discharge A of the unit 10. In the oven 30, the film F is stretched in a transverse direction, i.e., perpendicular to the discharge direction A, in a manner known per se. Thus, the production of a mono- or biaxially oriented film is possible.

[0063] Instead of two separate stretching systems 16, 18 for longitudinal and transverse stretching, a simultaneous stretching system can also be used. In this system, the film is stretched in the longitudinal and transverse directions simultaneously.

[0064] The treatment device 20 is, for example, a device for activating the surface of the film F by corona treatment, for example to achieve better metal adhesion.

[0065] The winding device 24 is used to wind up the produced film F and is the last device in the take-off direction A. It has a winding sleeve onto which the film F is wound.

[0066] In Fig. Figure 2 shows the casting device 14 (also called cooling roller unit) in an enlarged schematic view.

[0067] The casting device 14 shown here comprises the wide slot die 126, the cooling roller 142 and a positioning device 128.

[0068] The slot die 126 is arranged above the cooling roller 142 and is designed to continuously apply the polymer melt to the cooling roller 142, which forms the film F. The polymer used is, in particular, polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), and / or the like. It is also possible to combine different polymers. In particular, a film can have different layers of polymer and / or different polymers can be co-extruded within a single layer.

[0069] The film F is then evenly applied to the cooling roller 142 by means of the application device 128. The cooling roller 142 rotates in the view shown. Fig. 2 counterclockwise (rotation direction R). The film F produced in this way is finally, in the illustrated embodiment after about three-quarters of a rotation of the cooling roller 142, detached from the cooling roller 142, cooled and fed to a stretching unit 16, 18.

[0070] To detach the film F from the cooling roller 142, the casting device 14 comprises a take-off roller 144, which is followed by several deflection rollers 146, 147. The deflection roller 147 is arranged on a tensioning element 148. The tensioning element is designed here as a pivotable lever. The tension of the film F can be set or regulated by adjusting the angle of the lever.

[0071] As shown, the cooling roller 142 can be arranged in a first water bath to cool the extruded film F and the cooling roller 142. After the take-off roller 144, which serves to detach the extruded film F from the cooling roller 142, the film F can be guided through a further water bath 152 (or water bath 150) by means of the deflection rollers 146, 147 to achieve further cooling.

[0072] The water adhering to the film F must be removed from the film surface before the film is stretched in a longitudinal, transverse, or simultaneous stretching machine 16, 18. This is necessary to obtain the highest possible film quality and to prevent deposits on the rollers (e.g., of the longitudinal stretching machine 16), which would form due to the evaporation of the water.

[0073] A film drying device 200 is provided for removing water from the film surface. An exemplary film drying device 200 is shown with reference to the Fig. 3 and Fig. 4 described below.

[0074] Furthermore, a water removal device 154 may be provided, which is associated with the cooling roller 142. This water removal device 154 removes any water adhering to the cooling roller 142, so that the melt can be extruded onto a substantially dry cooling roller 142. For this purpose, the water removal device 154 may comprise at least a water scraper, at least a blower, at least one blow-off nozzle (in particular an air knife nozzle), and / or the like.

[0075] Fig. Figure 3 shows an isometric representation of a water removal device 200, and Fig. Figure 4 shows a sectional view of the water removal device 200.

[0076] The water removal device 200 comprises a main body 202, a first flap element 204, and a second flap element 206. The flap elements 204 and 206 are pivotably arranged on the main body 202 and can be pivoted from a first position (shown here) to a second position. In the first position, the water removal device is in an operating position. In the second position, the water removal device is in a maintenance position. By pivoting the flap elements 204 and 206, the water removal device 200 can be opened. This allows, among other things, the insertion of a film F along the film web.

[0077] As seen particularly in the sectional view of the Fig. As shown in Figure 4, the main body 202 is separated from the two flap elements 204, 206 along the foil web.

[0078] The pivoting of the first flap element 204 can be actuated via a drive, in particular a hydraulic drive 204a. The pivoting of the second flap element 206 can likewise be actuated via a drive, in particular the hydraulic drives 206a, 206b.

[0079] In the illustrated embodiment, the film F is passed through a film entry opening (in Fig. 3, below) into the water removal device 200 and guided there along the film web in the pull-off direction A through the water removal device 200. At a film outlet opening (in Fig. 3, pointing to the rear right) the film exits the water removal device 200 again. A driven nip roller 234 is provided adjacent to the film exit opening (see figure). Fig. 4) This can pull the film – even after it has been torn – through the water removal device 200. Furthermore, a transverse cutting device 260 can be provided, which is designed to cut the film transversely after it has passed through the film exit opening.

[0080] Fig. Figure 4 shows a water removal device 200 in a sectional view. The water removal device 200 comprises a first mechanical water removal device 210, a second mechanical water removal device 212, a first blow-off device 220, and a second blow-off device 222, which are passed by the film F in this order. An edge blow-off device 250 is provided after the second blow-off device 222.

[0081] The first mechanical water removal device 210, in the example shown here, comprises two squeezing rollers 210a, 210b, which are arranged opposite each other on opposite sides of the film web. The opposing squeezing rollers 210a, 210b form a squeezing roller pair through which the film F is passed. Mechanical water removal takes place during this process.

[0082] The squeezing roller 210b is mounted on a lever 210c and coupled to an actuator 210d. The squeezing force and / or the wrap angle of the squeezing roller 210b can be adjusted via the actuator 210b. The squeezing roller 210a is spring-mounted.

[0083] The second mechanical water removal device 212, in the example shown here, also comprises two squeezing rollers 212a, 212b, which are arranged opposite each other on opposite sides of the film web. The opposing squeezing rollers 212a, 212b form a squeezing roller pair through which the film F is passed. Further mechanical water removal takes place during this process.

[0084] The squeezing roller 212b is mounted on a lever 212c and coupled to an actuator 212d. The squeezing force and / or the wrap angle of the squeezing roller 212b can be adjusted via the actuator 212b. The squeezing roller 212a is spring-mounted.

[0085] The first blow-off device 220, which is connected downstream of the second mechanical water removal device 212, comprises a first blow-off nozzle 220a and a second blow-off nozzle 220c. The first blow-off nozzle 220a is arranged on a first side of the film web and the second blow-off nozzle 220c on a second side of the film web. The nozzles are positioned opposite each other, and the second blow-off nozzles can be designed as slot nozzles (see also...). Fig. 5), a blow-off roller 220b, 220d is arranged in each case. The blow-off nozzles 220a, 220c are designed to direct an airflow onto the film F in order to blow off any water carried along from the film F over at least one film edge (left and / or right).

[0086] The film F is guided to the second blow-off device 222 via a deflection roller 230. The deflection roller 230 can be driven to convey the film.

[0087] The second blow-off device 222 comprises a first blow-off nozzle 222a and a second blow-off nozzle 222c. The first blow-off nozzle 222a is arranged on a first side of the film web and the second blow-off nozzle 222c on a second side of the film web. They are positioned opposite each other, and the blow-off nozzles can be designed as slot nozzles (see also...). Fig. 5), a blow-off roller 222b, 222d is arranged in each case. The blow-off nozzles 222a, 222c are designed to direct an airflow onto the film F in order to blow off any water still present on the film F over at least one film edge (left and / or right).

[0088] After passing through the second blow-off device 222, the film can optionally be guided past edge blow-off devices 250. One edge blow-off device can be provided for the left edge of the film and one for the right edge.

[0089] The edge blow-off devices each comprise a first edge blow-off nozzle 250a and at least one second edge blow-off nozzle 250b. The first edge blow-off nozzle 250a is located on the first side of the film web, and the second edge blow-off nozzle 250b is located on the second side of the film web, opposite the first edge blow-off nozzle 250a. The edge blow-off device blows off only the corresponding edge of the film. The airflow generated here therefore does not cover the entire film F, but only its edge areas. Thus, any water adhering to the film edge can be blown off.

[0090] Fig. Figure 5 schematically shows the blowing off of the film using a blowing device, which includes a blowing nozzle 220a. The blowing nozzle 220a is shown schematically here and is designed as a slot nozzle. It includes an airflow outlet gap 220s. The airflow outlet gap 220s is designed to generate a uniform, essentially laminar airflow L. This airflow is directed onto the film in such a way that water is blown off over one or both edges of the film.

[0091] To achieve this, the slot nozzle can be configured to direct the airflow L onto the film F in such a way that it creates a flow component L T in the transverse direction T. In particular, the airflow can be directed relative to a film web normal L. ┴ be inclined, whereby the angle α at which the airflow L is inclined to the film web normal L ┴The angle lies within the range of 1° to 5°. The airflow L is represented here only by an arrow with a solid line. However, it is understood that the airflow exits across the entire width of the airflow outlet gap and thus covers the 225 blow-off area.

[0092] In Fig.Figure 6 shows the blowing off of the film F by means of a further blowing device comprising a blowing nozzle 220c. In this embodiment, the film F is conveyed upwards. The discharge direction A is inclined relative to the vertical G by an angle γ. Thus, any water carried along can flow off the film simply by its own weight. The blowing nozzle 220c is configured to generate a uniform, essentially laminar airflow L. This airflow is directed towards the film F in such a way that water is retained and thus blown off. In addition, the blowing nozzle 220c can be positioned transversely to the transverse direction of the film T by an angle β. This inclined orientation of the blowing nozzle, and thus of the blowing area 225, makes it possible to blow the carried-along water over the edge of the film F. R to cancel. Reference symbol list 10 Plant for the production of a film F 12 Extrusion plant 14 Casting device 16 Longitudinal stretching system 18 Crossbar system 20 treatment device 24 winding device 30 oven 120 extruders 122 Melt supply line 126 wide slot nozzle 128 Laying device 142 Cooling roller 144 Take-Off Roller 146 Deflection roller 147 Deflection roller 148 clamping element 150 water bath 152 Water bath 154 Water removal device for the cooling roller 200 Water removal device for the film 202 Main body 204 flap element 204a drive 206 flap element 206a drive 206b Drive 210 mechanical water removal device (squeezing roller pairing) 210a Squeeze roller 210b Squeeze roller 210c lever 210d actuator 212 mechanical water removal device (squeezing roller pair) 212a Squeeze roller 212b Squeeze roller 212c lever 212d actuator 220 first blow-off device 220a Blow-off nozzle (first side) 220b Blow-off roller 220°C blow-off nozzle (second side) 220d blow-off roller 220s airflow outlet gap 222 second blow-off device 222a Blow-off nozzle (first side) 222b Blow-off roller 222c Blow-off nozzle (second side) 222d Blow-off roller 225 Blow-off area 230 deflection roller 234 Nip roller 250 Edge blow-off device 250a blow nozzle 250b blower nozzle 260 Cross-cutting device A Deduction direction F foil G Vertical R direction of rotation T transverse direction L Airflow QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] DE 10 2021 128 332 A1

[0062]

Claims

Water removal device (200) for removing water from a film (F), in particular for cast film production, wherein the water removal device (200) comprises a film inlet opening and a film outlet opening, and is configured to guide the film (F) along a film web from the film inlet opening to the film outlet opening; wherein the water removal device further comprises at least a mechanical water removal device (210) which has at least two water removal elements (210a, 210b) arranged opposite each other on opposite sides of the film web and configured to apply a crushing force to the film (F);and wherein the water removal device (200) further comprises a first blow-off device (220) and a second blow-off device (222), wherein the first blow-off device (220) comprises at least a first blow-off nozzle (220a) and at least a second blow-off nozzle (220c), wherein the first blow-off nozzle (220a) is arranged on a first side of the film web and the second blow-off nozzle (220c) is arranged on a second side of the film web, and wherein the second blow-off device (222) comprises at least a first blow-off nozzle (222a) and at least a second blow-off nozzle (222c), wherein the first blow-off nozzle (222a) is arranged on the first side of the film web and the second blow-off nozzle (222c) is arranged on the second side of the film web, and wherein the blow-off nozzles (220a, 220c; 222a, 222b) are configured to direct an airflow (L) onto the film in order to to blow off any water carried along by the foil (F) over at least one foil edge; Water removal device (200) according to claim 1, wherein the water removal device (200) comprises a second mechanical water removal device (212) which is connected downstream of the first mechanical water removal device (210), and which has at least two water removal elements (212a, 212b) which are arranged opposite each other on opposite sides of the film web and are configured to apply a crushing force to the film (F). Water removal device (200) according to claim 1 or 2, wherein the water removal elements (210a, 210b; 212a, 212b) of the first and / or second water removal device (210; 212) are designed as squeezing rollers (210a, 210b; 212a, 212b), wherein at least one squeezing roller (210b; 212b) of the first and / or second water removal device (210; 212) is optionally coupled with an actuator (210d; 212d). Water removal device (200) according to one of claims 1 to 3, wherein at least one blow-off nozzle (220a, 220c; 222a, 222b) is associated with a blow-off roller (220b, 220d; 222b, 222d), wherein the associated blow-off roller (220b, 220d; 222b, 222d) is arranged opposite the blow-off nozzle (220a, 220c; 222a, 222b) to support the film (F) in the area (225) which is blown off by the blow-off nozzle (220a, 220c; 222a, 222b). Water removal device (200) according to one of claims 1 to 4, wherein at least one blow-off nozzle (220a, 220c; 222a, 222b) is a slot nozzle which is oriented substantially transversely to the film web, or which forms an angle β with the transverse direction (T) of the film web, wherein β is in the range of 1° to 45°, or in the range of 10° to 30°, or in the range of 15° to 20°. Water removal device (200) according to claim 5, wherein the slot nozzle is configured to direct the airflow (L) onto the film (F) such that it has a flow component (LT) in the transverse direction (T). Water removal device (200) according to one of claims 1 to 6, wherein the water removal device (200) further comprises at least one left and / or right edge blow-off device (250) which is downstream of the first and second blow-off devices (220; 222), wherein the left edge blow-off device is assigned to a left film edge and wherein the right edge blow-off device is assigned to a right film edge. Water removal device (200) according to one of claims 1 to 7, wherein the water removal device (200) comprises an air drying and / or air temperature control device, and wherein the air drying and / or air temperature control device is configured to provide air supplied to the first blow-off device (220), the second blow-off device (222), the left edge blow-off device and / or the right edge blow-off device (250) to generate an airflow, with a defined humidity and / or temperature. Water removal device (200) according to any one of claims 1 to 8, wherein the water removal device (200) is configured to provide the first blow-off device (220), the second blow-off device (222), the left edge blow-off device and / or the right edge blow-off device (250) with an airflow at a defined airflow rate and / or pressure, wherein optionally the second blow-off device (222) provides an airflow at a higher airflow rate and / or pressure than the airflow provided by the first blow-off device (220). Water removal device (200) according to one of claims 1 to 9, wherein the water removal device (200) comprises a main body (202) and at least one flap element (204, 206), and wherein the at least one flap element (204, 206) is pivotably arranged on the main body in order to be pivoted from a first position to a second position, wherein in the first position the water removal device (200) is in an operating position and in the second position in a maintenance position, and wherein the main body (202) is separated along the film web from the at least one flap element (204, 206). Water removal device (200) according to one of claims 1 to 10, wherein the water removal device (200) comprises an air extraction system configured to extract moist air from the housing of the water removal device (200). Casting device (14) for producing plastic films, wherein the casting device comprises a cooling roller (142), a take-off roller (144), at least one water bath (150, 152) and a water removal device (200) according to any one of the preceding claims 1 to 11, wherein the cooling roller (142) is configured to cool a plastic melt extruded onto its surface in order to produce a film (F), wherein the take-off roller (144) is connected downstream of the cooling roller (142) and is configured to release the film (F) from the cooling roller (142), wherein the at least one water bath (150, 152) is arranged such that the film (F) is guided through the at least one water bath (150, 152) in the casting device (14), and wherein the water removal device (200) is arranged such that the film (F) is dewatered before leaving the The casting device (14) passes through the water removal device (200) to remove water from the surface of the film (F). Casting device (14) according to claim 14, wherein the casting device (14) further comprises a water treatment plant, in particular a descaling plant, wherein the water treatment plant is configured to treat the water of the at least one water bath (150, 152). Plant (10) for the production of a film (F), wherein the plant (10) comprises at least one device for generating a polymer melt, in particular an extruder (12) and / or a reactor, as well as the casting device (14) according to claim 12 or 13, and wherein the extruder (12) or the reactor is configured to provide a polymer melt and to extrude it onto the cooling roller (142). Plant (10) for producing a film (F) according to the preceding claim, wherein the plant (10) further comprises a stretching plant (16, 18) which is connected downstream of the casting device (14) and which is configured to stretch the film (F) in the longitudinal direction and / or transverse direction.

Images