Film blowing apparatus for producing film strip using recovery

Abstract

The utility model relates to a film blowing device (10) for producing a film strip from recycled material (4), having the following features: a. An extruder (20) for melting and homogenizing the recycled material (4) into a melt, b. An annular nozzle (30) for extruding a film tube (6), c. A guide (40) for the melt flow between the extruder (20) and the annular nozzle (30) via the annular nozzle melt pump (42) for conveying the melt to the annular nozzle (30), d. A tube formation zone (32) for drawing the film tube (6) in the longitudinal direction and in the transverse direction, e. A cooling device (34) for cooling the film tube (6) moving in the machine direction, f. Outside the tube formation zone (32) there is a folding section (36) for folding the film tube (6) into a double-layer film strip (8), g. Outside the cooling device (34) there is a pair of traction rollers (38) for pulling the film tube (6), h. The extruder (20) is designed as a twin-screw extruder.

Description

Technical Field

[0001] The invention relates to a film blowing device and an application of a twin-screw extruder for supplying an annular nozzle of the film blowing device.

[0002] More precisely, the invention relates to a film blowing plant for producing film strips from recycled material, the use of a twin-screw extruder for supplying an annular nozzle of the film blowing plant. Background Art

[0003] Blown film equipment is already known in the prior art in various embodiments. In particular, the blown film equipment of the prior art has also been able to produce film strips using recycled materials. Typically, the blown film equipment will have an extruder, which is used to melt and homogenize the material to be extruded into a melt. In addition, it is particularly known that an annular nozzle is provided for extruding a film tube, and the blown film equipment has an annular nozzle melt pump for conveying the melt to the annular nozzle in the melt flow between the extruder and the annular nozzle. In addition, the blown film equipment can have a tube forming area for drawing the film tube longitudinally and transversely or stretching the film tube longitudinally and transversely, respectively. In addition, in the case of the blown film equipment in the prior art, a cooling device can also be provided for the film tube moving in the machine direction, and in addition to the tube forming area, the blown film equipment can have a folding section for folding the film tube into a double-layer film strip. In addition, in the prior art, in addition to the cooling device, the blown film equipment can also have a pair of traction rollers for traction of the film tube.

[0004] The disadvantage of the known solutions is that the material to be recycled, in particular the film for production and / or use, must first be comminuted, melted and pelletized before the material is extruded in the next step. This may lead to additional processing steps, reduced material quality and higher energy consumption. Summary of the invention

[0005] Problems and Solutions

[0006] The problem of the present invention is therefore to at least partially remedy the above disadvantages. In particular, the problem of the present invention is to provide fast material changes and conversion times, improved melt quality with a high recovery ratio, improved layer distribution, low-tension and low-shrinkage and / or high-tension and high-shrinkage films, a high degree of automation and / or good operability.

[0007] The above-mentioned problem is solved by a film blowing device for producing film tapes using recycled materials, which has the following characteristics: a. The film blowing device has an extruder for melting and homogenizing the recycled materials into a melt, and b. The film blowing device has an annular nozzle for extruding a film tube, and c. The film blowing device has a guide for the melt flow, and the melt is conveyed to the annular nozzle via an annular nozzle melt pump between the extruder and the annular nozzle, and d. The film blowing device has a tube forming zone for drawing the film tube in the longitudinal direction and in the transverse direction, e. The film blowing device has a cooling device for the film tube moving in the machine direction, and f. The film blowing device has a folding section outside the tube forming zone for folding the film tube into a double-layer film tape, and g. The film blowing device has a pair of traction rollers outside the cooling device for traction of the film tube, and is characterized by the following characteristics: h. The extruder is configured as a twin-screw extruder. Other features and details of the invention are explained by the corresponding description and drawings. Of course, the features and details described with respect to the film blowing apparatus according to the present invention also apply to the method for providing a product according to the present invention, and in each case, the features and details described with respect to the method for providing a product according to the present invention also apply to the film blowing apparatus according to the present invention, so that, for the purposes of this disclosure, reference is always made to various aspects of the present invention or reference can always be made to various aspects of the present invention.

[0008] According to the present invention, a film blowing device for producing film strips using recycled materials is proposed. In keeping with a general film blowing device, the film blowing device may have an extruder for melting and homogenizing the recycled material into a melt and an annular nozzle for extruding a film tube. In addition, the film blowing device has an annular nozzle melt pump in a guide for the melt flow between the extruder and the annular nozzle for conveying the melt to the annular nozzle. In the present application, the melt flow should also be understood as a guide for such a melt flow, so that these features are not necessarily related to a film blowing device having a melt, but also to a film blowing device having a guide for a melt flow.

[0009] Furthermore, it can be provided that the film blowing device has a tube forming zone for drawing the film tube in the longitudinal direction and in the transverse direction, and a cooling device for the film tube moving in the machine direction. Furthermore, the film blowing device can also have a folding section for folding the film tube into a double-layer film strip outside the tube forming zone and a pair of traction rollers for traction of the film tube outside the cooling device.

[0010] In addition, it is proposed that the extruder of the film blowing device is configured as a twin-screw extruder. A twin-screw extruder is a multi-shaft extruder. In plastics technology, it is used to prepare plastic melts and to shape plastic melts. In this case, for this purpose, the recycled material or material mixture is conveyed through a heated drum together with the recycled material by means of two mutually meshing rotating screw shafts and then melted. Twin-screw extruders are usually divided into tangential or closely meshed co-rotating twin-screw extruders or tangential or closely meshed counter-rotating twin-screw extruders based on the center distance between the two screw shafts and the rotation direction of the two screw shafts. Counter-rotating twin-screw extruders introduce less shearing force into the material to be extruded, and therefore hardly generate stress on the material. Therefore, when processing temperature-sensitive materials, it is preferred to use counter-rotating twin-screw extruders. In the present application, co-rotating twin-screw extruders, in particular closely meshed co-rotating twin-screw extruders are particularly preferred.

[0011] In other words, twin screw extruders can be divided into counter-rotating and co-rotating designs. In these designs, a distinction is made between intermeshing screws and non-intermeshing screws. In the case of intermeshing screws, the grooves of one screw usually engage with the grooves of the other screw, while in the case of non-intermeshing screws, the screw profiles do not overlap in the axial direction. Another distinguishing feature is the position of the screws relative to each other.

[0012] A distinction is often made between parallel screws and conically arranged screws.

[0013] Intermeshing counter-rotating twin-screw extruders usually form C-shaped closed conveying chambers that convey the extruded composition through the extruder regardless of its tribological properties. This mode of material transport is called forced conveying. Similar to a gear pump, the screws rotate separately at the top to facilitate the material to be sucked in. Due to the closed conveying chamber, the material conveying volume is basically unaffected by the back pressure. A calendering flow is generated in the engagement area of ​​the screws, so that high shear forces are generated in the gap. These forces can be used to disperse additives. Counter-rotating twin-screw extruders are mainly used for processing PVC. Due to the wall slip tendency and thermal sensitivity of the material, difficulties are encountered during the processing of PVC. Due to the use of counter-rotating twin-screw extruders, the material is forced to be conveyed and a narrower residence time range is achieved. On the one hand, this can offset wall slip, and on the other hand, this prevents excessive degradation of the material due to excessive thermal stress.

[0014] In conical twin-screw extruders, the screw axes are no longer parallel but are arranged at an angle so that the center distance of the screws decreases in the direction of the discharge zone. The advantages offered by the conical design include, in particular: shorter installation lengths for comparable conveying volumes, lower shear forces in the discharge zone due to the reduced peripheral speed of the screws, and easier application of torque due to the greater center distance. There are three essential differences. Constant, decreasing or increasing groove depths allow the required volume to be adapted to the respective task.

[0015] In general, twin-screw extruders with intermeshing, co-rotating screws do not constitute a closed conveying chamber, but rather an axially open system. Therefore, there is no forced conveying, but rather conveying is mainly based on the so-called drag flow. The screws preferably rotate at the same angular velocity and in the same direction of rotation. The extruded composition is conveyed in channels that spirally surround the two screws in the form of a figure eight, wherein, due to the geometry, the cross section in the joining area narrows. A portion of the melt is forced to be conveyed, regardless of the adhesion conditions; this occurs due to the geometry in the joining area. At all points in the joining area, the two screws slide closely past each other at the same relative speed; therefore, when the gap between the screws is small enough, the adhering extruded composition is scraped off. Due to this self-cleaning effect, co-rotating twin-screw extruders also constitute important production machines.

[0016] Today, co-rotating twin-screw extruders are used in many industrial sectors, but by far the main field of application (based on installed machines) is the plastics industry. Here, co-rotating twin-screw extruders are primarily used for the preparation of plastic materials, but are also increasingly used for direct processing during extrusion and injection molding. In particular, the advantages gained in these areas are reflected in the fact that no additional melting has to be carried out (saving energy and at the same time avoiding damage to the polymer due to secondary melting) and the formulation freedom leading to greater flexibility in setting the material properties. Other important fields of application for these machines are the rubber and food industries.

[0017] Twin screw extruders can generally have a modular design to accommodate a variety of processing and product requirements. This applies to both the drum and the screw. The extruder screw is preferably composed of elements that are pushed onto a central shaft and attached together. The advantages of this design are, in particular: easy modification of the screw geometry for test settings at initial installation or in the event of changes in processing conditions; standardization of screw elements; and the formation of different optimized processing zones.

[0018] The typical processing zones of a twin screw extruder are:

[0019] - Feeding area,

[0020] - melting zone,

[0021] - Allocate mixing areas,

[0022] - Dispersive mixing zone,

[0023] - a degassing zone, and

[0024] -Discharging area.

[0025] Solid plastics are usually fed to the extruder in a feed zone. The solids are then conveyed in the direction of the discharge zone and compressed. Another task of the feed zone is preferably to remove the air that is also sucked in. The conveying capacity of the solid conveying zone depends on the free screw volume, the speed and the bulk density of the solids.

[0026] Plastics can be supplied to the twin screw extruder via a hopper and / or a side feeder. In any case, during general metering and when designing a hopper and / or a side feeder, special consideration must be given to the fact that plastic waste (particulate material and / or fluff) is not easy to flow due to its low bulk density. This can be attributed essentially to its unfavorable shape and the associated low bulk density: in the case of fluff, this is due to the nature of the material itself ("fragments"); in the case of recycled particulate material particles, this is due to its unfavorable particle shape and uneven particle shape distribution. Without special measures, the result is often the formation of bridges and tunnels in the hopper. The formation of bridges completely blocks the flow of material, while the formation of tunnels can lead to segregation and the formation of dead zones, such as in the hopper. Therefore, these two effects often lead to production interruptions or large fluctuations in the delivery volume. In simple cases, this problem can be solved by appropriate tilting of the hopper wall. The next step is preferably to install a so-called feed fitting in the hopper. If this is also unsuccessful, another possibility is to use an agitator or a compression screw in the hopper. In addition to the polymer in the form of particulate material or fluff, powdered or liquid additives such as fillers (CaCo3, TiO2) or processing aids can also be provided in the downstream region of the twin-screw extruder.

[0027] One advantage of a twin-screw extruder is that the starting material does not necessarily have to be present as particulate material, as in the case of a single-screw extruder, but it is also possible to supply so-called "fluff" in the form of chips / pieces. For production in the form of "fluff", the starting material must be comminuted starting from an original form, for example in the form of sheet material (e.g. as coil), edge strips, scraps or PCR items after sorting (films or laminates with a size of DIN A6 to DIN A0 or more), frits, film / laminate chips, which have been comminuted after sorting and cleaning in a first step.

[0028] As a basic operation, comminution is a prerequisite for virtually all subsequent preparation and recycling processes, where the selected particle size must be adapted to the subsequent processes. At the same time, the particle size should not be smaller than the required size, as the costs associated with comminution are high. In addition to the appropriate particle size, a uniform particle size distribution and particle shape are also required, otherwise different geometries can have a significant negative impact on the subsequent sorting.

[0029] The material properties of the feedstock, in particular toughness, elasticity and thermal stability, are of decisive importance for the comminution performance and the success of the comminution. Energy can be introduced in various ways. However, in the case of thermoplastics, stresses caused by pressure, shear and impact often only lead to undesirable results. Under normal circumstances, pressure and impact are absorbed by the plastic particles in a resilient-elastic manner, while shearing leads to melting of the plastic particles. Therefore, the types of stress used for large-scale comminution are primarily cutting and impact.

[0030] During cutting, particles are separated along the cutting edge in the shear gap due to shear stress. In other words, the difference between the shear stress form and the cutting stress form is that during cutting, the local effect of shearing on the shear gap is very limited, while the shear stress form affects the entire particle. Therefore, in the case of solids, shearing only leads to insufficient comminution results.

[0031] The crushing of particles by impact is achieved by inertial force, that is, when colliding with one or more particles, or by impacting with a solid body at a high relative speed, the kinetic energy present is converted into deformation work. The difference between pressure, impact and impact stress is the relative speed between particles or between particles and solids. The relative speed under pressure stress is less than 5m / s, while the relative speed under impact stress is greater than 5m / s. On the other hand, during the crushing by impact, the relative speed is between 20m / s and several 100m / s. Especially in the case of ultra-fine grinding, the relative speed is very high.

[0032] In order to produce fluff for feeding a twin-screw extruder from the above waste materials, comminution by cutting is an option.

[0033] Cutter roll mills (also called rotor shears, twin shaft shears or shredders) or more rarely guillotine shears (also called dividers) are used first to comminute by cutting.

[0034] In the case of a cutting roller shredder, the supplied material is gripped by tearing teeth arranged on parallel counter-rotating shafts and is sucked between the shafts. The waste is shredded partly by cutting and partly by tearing until it can leave the intermeshing rollers at the bottom.

[0035] In addition to cutting roller mills, cutting mills are also frequently used. These mills are ideal for comminuting ductile-elastic materials and are therefore suitable for almost all plastics. There are different designs of cutting mills, but they all work according to the same principle. Gravity causes the material to be comminuted to enter the feed area of ​​the rotor through the conveyor trough, which is open at the moment. The material to be comminuted circulates through the rotor and is continuously comminuted between the rotor and the bed knife. If the particle size of the individual particles is smaller than the mesh size of the bottom of the filter used, these particles leave the grinding chamber due to gravity and partly due to centrifugal force.

[0036] Cutter roll shredders can take up various film and laminate waste materials particularly well and shred them into fluff and are therefore particularly preferably suitable for producing fluff in direct processing in film extrusion in plants with intermeshing counter-rotating twin-screw extruders.

[0037] The melting or plasticizing zone is used to convert the solid into a melt. In addition, fillers are pre-dispersed. According to the following processing zones, 100% melting is not always achieved at the end of the plasticizing zone.

[0038] Unmelted solid particles can be melted in subsequent zones such as dispersive mixing zones. The task of the dispersive mixing zone is the distribution of solids and liquids in the melt and the homogenization of the temperature of the composition. The mixing effect is achieved by separating and redirecting the melt flow. Mixing elements are usually designed to minimize shear-intensive dispersion, thereby reducing self-cleaning. In the dispersive mixing zone, solid or polymer agglomerates and droplets will be broken under the action of high shear forces. In addition to the shear stress, the duration of the stress is also decisive for the breaking effect.

[0039] The degassing zone is used to remove water, residual monomers and dissolved gases. In order to prevent the melt from escaping from the degassing opening, the pressure of the melt must first be adapted to the ambient pressure. The channel upstream of the degassing zone must be completely filled to prevent components that have not yet been combined from being drawn out or air from being sucked in through the filling funnel. This is achieved by suitable accumulation elements.

[0040] During processing by extrusion, degassing can remove low molecular components, gases or air from the melt. However, the substances to be degassed vary partly due to the specific composition of the recycled material.

[0041] The most frequent degassing tasks during plastic recycling are:

[0042] - Drying: Residual moisture is extracted, so that in some cases time-consuming and costly predrying of the material can be dispensed with; bubble formation and molecular weight loss due to hydrolysis can be prevented.

[0043] - Shift in equilibrium: If low molecular weight components are extracted, especially from polycondensates, the equilibrium shifts towards the high molecular weight chains and the molecular weight increases.

[0044] - Removal of external contaminants: Highly volatile, mainly organic compounds, such as fats, oils and in some cases printing inks or varnishes, which adhere to the plastic in the form of contaminants are removed from the melt.

[0045] -Removal of internal contaminants: Degassing is used to remove substances that diffuse into the material during the use of the plastic and cannot be removed by the cleaning process, such as gasoline, diesel, antifreeze, etc.

[0046] - Removal of low molecular weight degradation products: Removal of degradation products released during processing or use in the form of chain fragments, monomers or oligomers and which permanently impair the use and processing properties of the plastic.

[0047] - Solvent degassing: removal of solvents that have entered the material as a result of the cleaning and separation stages employed as part of the preparation.

[0048] Of course, degassing also partially removes substances that should remain in the material. These substances can be short-chain polymer components and added additives, especially stabilizers, antioxidants, UV absorbers, plasticizers, etc.

[0049] The following relationship applies to the degassing capacity:

[0050] As the temperature increases, factors such as viscosity, vapor pressure, volatility and diffusion equilibrium are positively influenced and lead to improved degassing performance.

[0051] As the pressure in the degassing zone decreases, the degassing capacity increases.

[0052] A large phase interface combined with a simultaneously low layer thickness promotes degassing. The phase interface and the layer thickness are predetermined by the dimensions of the degassing mechanism. Since the layer thickness cannot be reduced arbitrarily, attempts are made to increase the degassing performance by continuous surface renewal, i.e. high speed.

[0053] Long residence times in the degassing zone may lead to better degassing results. This relationship is contrary to economic goals and therefore short residence times.

[0054] In addition to the so-called atmospheric degassing zone, a twin-screw extruder with intermeshing co-rotating screws, as used in direct processing, also has at least one, but preferably two, degassing zones in which a vacuum is applied. In any case, the pressure in such a processing zone is below 1 bar to 1 mbar. Typical pressures are between 800 mbar and 10 mbar, preferably between 500 mbar and 50 mbar.

[0055] The discharge zone is used to build up the pressure required for the following process.

[0056] During melt filtration of plastics, the material is directed through a filter element while it is melted to remove impurities and other solids from the plastic. The plastic is directed through a filter element under pressure and high temperature to filter out solids from the plastic. Melt filtration is an important step during plastic recycling as it helps to improve the quality of the recycled material and remove as many contaminants as possible. It is often used in conjunction with other techniques such as degassing to make the recycled material as pure as possible.

[0057] Filtration or filtering is generally understood as the separation of solid or liquid particles from a fluid by means of a filter medium. Therefore, in extrusion, the task of filtering is to precipitate various foreign particles according to the selected filter fineness and thus provide a melt that is as pure as possible.

[0058] This problem is exacerbated during the processing of plastic waste, which, despite complex cleaning stages during preparation, still contains much higher amounts of pollutants than new plastic materials.

[0059] For process optimization and for economic reasons, melt filtration should meet the following requirements:

[0060] - Filtration at approximately constant pressure and constant temperature

[0061] - Replace filters without interrupting and / or affecting production

[0062] - Minimum additional residence time of the melt

[0063] - Minimal pressure drop across the filter media

[0064] - The filter life is as long as possible

[0065] However, since the degree of contamination is sometimes very high in the case of plastic waste, conventional filter systems for virgin material quickly reach the limits of these requirements. For filtration, a foreign body amount of 0.3% by volume is already a very large amount of contamination, and even for filter wheel filters as a filter system in continuously operating filter systems, the upper limit of the contamination amount is 0.5% by volume for economic reasons.

[0066] Typical filtration finenesses depend on the field of application and therefore also on the melt filter used. Large-area filters are used when the production process runs continuously, recipe and batch variations are rare, and a higher purity is required for the end product, in other words, for example, when the product must be crystal clear and free of visible particles. This generally requires a filtration fineness of less than 50 μm, in special cases even less than 5 μm. On the other hand, filter changers are designed for processes with frequent changes in recipes and / or colors and / or a high degree of contamination (e.g. recycling). Filter finenesses greater than 50 μm are used. During direct processing in a film extrusion plant using a co-rotating twin-screw extruder, typical filtration finenesses are between 50 μm and 500 μm, preferably between 80 μm and 200 μm. Suitable filtration surface areas per filter screen (opening) are between 10 cm 2 With 1.5m 2 between, preferably between 50cm 2 With 500cm 2 between.

[0067] Generally speaking, the entire processing section of the twin screw (barrel and screw) adopts a modular structure and is therefore very flexibly adaptable to various processing tasks. Generally speaking, the processing section is heated electrically or with saturated steam (in the case of very large units) and can be cooled with water (evaporation) or air.

[0068] For torque transmission, screws often have a modified tooth profile, multi-wedge or polygonal geometry. Due to the required level of safety during the transmission of very high torques, feather key connections are hardly used anymore.

[0069] The length of the screw and the drum is indicated based on the screw outer diameter (L / D). In recent years, due to the requirements in the processing of polymer blends, such as intensified mixing and kneading processes, multi-stage supply of additives, multi-stage degassing, etc., the demand for long screw lengths (L / D) has increased: the screw length (L / D) affects the length of time of the mixing and kneading process (dispersive and distributive mixing), the chemical reactions in the processing of the mixture, etc. In short, a longer L / D leads to a longer residence time. Today, twin-screw extruders generally use screw lengths L / D of 12 or more for laboratory extruders and up to 420 L / D for extruders in the chemical industry. The typical ratio during the use of co-rotating twin-screw extruders in direct processing in film extrusion equipment is between 30 and 60 L / D, preferably between 40 and 50 L / D.

[0070] Commonly used shells are 3D or 4D long, in some cases, for economic reasons, the shell is even 8D long. The shell is designed for various processing tasks. These tasks correspond to typical processing areas and include in particular feeding, melting, supply with back ventilation, blending, degassing and discharge / pressurization.

[0071] In the middle of the last century, after the co-rotating twin-screw extruder was put on the market, its typical speed was initially in the range of 100 rpm to 200 rpm. Today, the maximum speed has reached the range of 600 rpm to 1500 rpm, and there is a trend of increasing year by year. High screw speeds can increase the delivery rate and improve the mixing effect under high shear forces. As a special example, very high screw speeds of up to 2500 rpm are indicated, which are sometimes used to control the morphology of polymer alloys. The typical speed of the co-rotating twin-screw extruder during the use period in the direct processing in the film extrusion equipment is 100 rpm to 600 rpm, preferably 200 rpm to 500 rpm.

[0072] For the process engineering of co-rotating twin screws, several geometric and drive parameters are decisive:

[0073] The so-called screw profile is derived from the ratio Da / Di of the outer diameter Da to the inner diameter Di. The center distance a of the two screws is then (Da+Di) / 2. In practice, the center distance will be slightly larger due to the necessary clearance. The projected cross-sectional area of ​​the screw, or more precisely of the two screw elements, at any point in the extruder is always smaller than the cross-sectional area of ​​the figure eight drum. In addition to the outer diameter and the inner diameter, the resulting free cross-sectional area is another geometric parameter of the co-rotating twin-screw extruder that meshes with each other. The free cross-sectional area Afree increases with the increase of the diameter ratio Da / Di. As a result, the free volume in the processing section for feeding, conveying and degassing is larger. The so-called groove depth h is calculated as (Da-Di) / 2.

[0074] At present, the typical outer diameter of co-rotating twin-screw extruders is between about 12 mm for laboratory extruders and about 260 mm for large-scale production equipment. The typical outer diameter of co-rotating twin-screw extruders during use in direct processing in film extrusion lines is between 30 mm and 180 mm, preferably between 50 mm and 120 mm, particularly preferably between 55 mm and 95 mm.

[0075] In addition, the following are important for the possible delivery volume:

[0076] Specific torque, which is the quotient of the installation torque Md of each screw shaft and the cube of the center distance a Md / a 3 and screw speed n.

[0077] In order to obtain high conveying capacity and better mixing effect of twin-screw extruders, the Da / Di ratio and specific torque have continued to increase since the advent of co-rotating twin-screw extruders in the middle of the last century:

[0078] If the diameter ratio Da / Di was initially only 1.22, over the years the diameter ratio Da / Di has increased from 1.44 to 1.55, then to 1.66 and finally even to 1.8.

[0079] In the middle of the last century, the first generation of co-rotating twin-screw extruders had a specific torque of only 3Nm / cm 3 Up to 5Nm / cm 3 ; Typical values ​​today are around 15Nm / cm 3 Up to 20Nm / cm 3 The greater the specific torque, the better the mixing effect and the higher the conveying capacity. In addition, it also means that the polymer can be processed at lower processing temperatures (i.e., the melt viscosity is higher and there is less thermal degradation).

[0080] The recycled material is preferably a plastic or a plastic mixture, particularly preferably a plastic or a plastic mixture from the group consisting of polymers, polycondensates such as polyethylene (LDPE, LLDPE, mLLDPE, HDPE, MDPE, VLDPE, etc.), polypropylene (generic and copolymers, compounds), thermoplastic materials, ionomers, ethylene copolymers (EVA, EVOH, EPM / EPDM, EMMA, EAA, EEA, CPE, etc.), cycloolefin copolymers, polyamides (PA6, PA66, PA6 / 66, PA 11, etc.), thermoplastic elastomers (TPE-E, TPE-O, TPU), terephthalates (polyethylene terephthalate (PET), polybutylene terephthalate (PBT)), polyisobutylene (PIB), polystyrene (PS), bio-based plastics and biodegradable plastics (PLA, PHA, TPS, PCL, PBAT, PBS).

[0081] In addition, the recycled material may contain additives (antioxidants, antistatic agents, colorants, fillers such as CaCO3, TiO2), lubricants, anti-blocking agents, adhesion promoters, etc.). The recycled material can also be clearly printed or labeled, etc. Twin-screw extruders have a particularly good mixing effect and can therefore prepare the plastics used. In particular, it is particularly advantageous to use a twin-screw extruder for recycling and / or blending additives.

[0082] According to one embodiment, the film blowing device has a filter having at least one filter element for filtering the melt from the unfiltered side to the filtered side. The filter is used as a dirt retention filter. The filter is preferably a filter from the group consisting of a melt filter, an extruder filter, a filter disc and a coarse filter. In this case, the filter element can be single-layer or multi-layer or pleated. The filter element can include a wire mesh, a metal nonwoven and / or a sintered fabric laminate.

[0083] The filter is preferably arranged in the melt flow between the extruder and the annular nozzle. The filter can also be part of the extruder. The filter is preferably arranged between the extruder and the annular nozzle melt pump.

[0084] According to one embodiment, the filter has a cleaning device for continuously and / or discontinuously replacing the filter element. In the present application, the term replacement should be understood to refer to both the cleaning of the filter element and the introduction of a new filter element that has not been used as a filter element before or has been cleaned before being used again. This introduction can be done manually or preferably automatically.

[0085] According to one embodiment, the cleaning device is configured to replace the filter element during operation of the device, ie while producing the membrane tape. In other words, in the case of this embodiment, it is not necessary to stop the film blowing device to replace the filter element.

[0086] According to one embodiment, the cleaning device has a rotatable filter element or a rotatable cleaning element for replacing the filter element. The rotatable filter element can be rotated on the scraper element so that the filtered dirt is stripped from the filter element. Alternatively, the scraper element can be rotated on the filter element so that the filtered dirt is stripped from the filter element. According to one embodiment, the cleaning device has a filter element that can be moved relative to the melt flow it is engaged with, or a cleaning element that can be moved relative to the melt flow it is engaged with for replacing the filter element.

[0087] According to one embodiment, the cleaning device has a deflection device for cleaning the filter element by temporarily directing the melt from the filtered side to the unfiltered side, i.e. by directing the melt in the opposite direction to the usual melt flow. Due to this deflection of the melt flow, the filtered debris is removed from the filter element. The cleaning device preferably has a clean outlet through which the melt directed from the filtered side to the unfiltered side is discharged. In particular, it is preferred that the melt to be discharged is a melt comprising filtered dirt.

[0088] According to one embodiment, the cleaning device has a screen changer configured to divide the melt stream and thus direct the melt stream through a plurality of filter elements. The screen changer is preferably configured to direct the melt stream through only one of the filter elements, rather than through the first filter element and the second filter element, so that the first filter element is replaced when the second filter element is located in the melt stream.

[0089] According to one embodiment, the cleaning device or a corresponding filter changer is designed to guide the melt stream selectively through individual and / or all available filter elements.

[0090] According to one embodiment, the film blowing device has a filter melt pump between the extruder and the annular nozzle melt pump, which pumps the melt to the filter. The extruder is conceived so that pressure is built up in the melt flow to overcome the flow resistance of the extruder. In the case of an embodiment with a filter, the pressure of the extruder is often not enough to overcome the flow resistance at the filter. In this case, a filter melt pump that overcomes the flow resistance of the filter is preferred.

[0091] A filter melt pump is preferred so that a particularly constant supply of material per unit time and thus a constant material processing can be achieved.

[0092] According to one embodiment, the twin-screw extruder has at least one degassing unit, from which impurities and contaminants can be extracted. The degassing unit can be configured as a degassing zone as part of the extruder. Volatile components can be extracted from the melt by means of the degassing unit. In order to improve the degassing, it is preferred that the filling degree of the twin-screw extruder is less than 100%, particularly preferably less than 80%. Such a filling degree is preferred, since otherwise the melt would be pressed into the degassing connector and would escape from the degassing unit.

[0093] According to one embodiment, the twin-screw extruder has at least one degassing unit which is configured as a normal-pressure degassing unit. In the case of this design, volatile components can be discharged from the degassing unit without applying negative pressure.

[0094] According to one embodiment, the twin-screw extruder has at least one degassing unit which is designed as a vacuum degassing unit. In the case of this design, negative pressure is applied to the degassing unit. The negative pressure can be generated by a vacuum pump. This design allows for particularly thorough degassing of volatile components. Preferably, the degassing unit, in particular the vacuum degassing unit, has a device for collecting volatile components, preferably in the form of a condensate.

[0095] According to one embodiment, the extruder has a recycling material supply device with a filler screw. By means of the filler screw, the recycling material can be fed to the extruder in a particularly uniform manner. The recycling material supply device preferably has a hopper, in which the filler screw is arranged. The filler screw is preferably driven by a drive independent of the extruder.

[0096] According to one embodiment, the film blowing device has at least two pressure sensors for detecting the pressure in the guide for the melt stream, preferably in each case at the extruder and upstream of the annular nozzle. The pressure sensors are configured to detect the melt pressure in the melt stream during operation of the film blowing device.

[0097] According to one embodiment, the film blowing device has at least two pressure sensors for obtaining the melt pressure in the melt flow at the extruder and the melt flow upstream of the annular nozzle in each case. The first pressure sensor is preferably arranged close to the extruder or arranged outside the extruder. The second pressure sensor is preferably arranged close to the upstream of the annular nozzle or arranged at the annular nozzle. In an alternative embodiment, the second pressure sensor is arranged upstream of the annular nozzle melt pump. The extruder and / or the annular nozzle melt pump and / or the recycling material supply device can preferably be adjusted according to the melt pressure in the melt flow at the extruder and / or the melt flow upstream of the annular nozzle obtained by the first pressure sensor and / or the second pressure sensor.

[0098] According to one embodiment, the film blowing device has two additional pressure sensors for acquiring the melt pressure in the melt stream upstream and downstream of the filter. In other words, these additional pressure sensors are pressure sensors present in addition to the above-mentioned pressure sensors. These additional pressure sensors can be installed immediately upstream and downstream of the filter. However, it is preferred that the additional pressure sensors are positioned immediately upstream of the filter and immediately upstream of the annular nozzle. In the case of this design, the second pressure sensor is preferably positioned immediately downstream of the filter.

[0099] The extruder and / or the annular nozzle melt pump and / or the recycling material supply and / or the deflection device of the filter and / or the filter element changing device can preferably be adjusted as a function of the melt pressure upstream and / or downstream of the filter.

[0100] The deflection device of the extruder and / or the annular nozzle melt pump and / or the recycling material supply device and / or the filter can particularly preferably be adjusted based on pressure sensors for acquiring the melt pressure in the melt flow at the extruder and in the melt flow upstream of the annular nozzle, and additional pressure sensors for acquiring the melt pressure in the melt flow upstream and downstream of the filter.

[0101] According to one embodiment, the film blowing plant has a storage silo for storing the recycled material.

[0102] According to one embodiment, the film blowing apparatus has a screw conveyor for conveying the recycled material from the storage silo to the recycled material supply device. The screw conveyor is preferably arranged horizontally or approximately horizontally.

[0103] According to one embodiment, the storage silo has a device for mixing the recycling material inside the storage silo. This is preferred because possible blockages of recycling material inside the storage silo can be solved thereby. The device for mixing is preferably a comb system inside the storage silo, but can also be, for example, a vibrator that vibrates the storage silo.

[0104] According to one embodiment, the storage silo has a device for determining the filling degree of the recycling material. The device for determining the filling degree can be a weighing device of the storage silo. Preferably, the device for determining the filling degree is an optical and / or capacitive sensor.

[0105] According to one embodiment, the storage silo has a device for determining its recycling material consumption. The device for determining the recycling material consumption is preferably a weighing device of the storage silo. Thus, the recycling material consumption can be obtained by the decrease in weight over time.

[0106] According to one embodiment, the film blowing plant has a distribution silo for filling the storage silo with recycled material.

[0107] According to one embodiment, the film blowing device has a shredder for crushing the starting material. The starting material can be a plastic or a mixture of plastics from the above group. The starting material can exist in the form of sheet material, crushed sheet material, shredded film, etc. The crushed sheet material can exist in a size from a few millimeters to DIN A0 and a large sheet material part. The shredder is preferably configured to crush the starting material into recycled material. The recycled material is preferably in the form of fluff. The recycled material can exist in the form of flakes. The flake size of the recycled material is preferably between 1mm and 40mm, and the flake size of the recycled material is particularly preferably between 5mm and 12mm.

[0108] According to one embodiment, the film blowing plant has a transport device for transporting the recycled material from the shredder to a storage silo and / or a distribution silo.

[0109] In the case of a design with a distribution silo, it is preferred that the transport device only transports the distribution silo. The transport device is preferably designed as a conveyor belt and / or a screw conveyor or a pressure conveying system. A design with a conveyor belt with a screw conveyor is particularly advantageous because the material can be transported in a particularly continuous manner.

[0110] According to one embodiment, the film blowing plant has a mixing silo for mixing the recycled material with other materials. The film blowing plant may also include a plurality of mixing silos. The mixing silo may also serve as a temporary storage device for various recycled materials. In addition to the recycled material, other extrudable materials may also be stored in the mixing silo. The mixing silo preferably has a mixing device in the mixing silo.

[0111] The mixing silo is preferably connected to the storage silo and / or the distribution silo via a blower and / or a conveyor belt and / or a screw conveyor for introducing the recycled material and / or a mixture thereof.

[0112] According to one embodiment, the recycled material supply device is configured to receive pelletized material and / or particulate material in addition to or alternatively to the recycled material for conveying it to the extruder. The additional material may also be other extrudable materials in addition to the recycled material.

[0113] The film blowing device preferably has a pellet metering device for storing and metering pellet materials. The pellet materials are preferably virgin materials and / or recyclates of higher quality than recycled materials.

[0114] According to one embodiment, the film blowing device is configured to produce a film strip having at least one other layer in addition to the layer made of recycled material. The film blowing device is preferably configured to produce a film strip having 1 to 11 or 13 layers, and the film blowing device is particularly preferably configured to produce a film strip having 1 to 5 layers.

[0115] According to one embodiment, the film blowing device has at least one additional extruder for melting and homogenizing the material of the at least one additional layer into a melt. The additional layer is preferably a plastic or a mixture of plastics from the abovementioned group.

[0116] The additional extruder may be an additional twin-screw extruder.

[0117] According to one embodiment, the blown film apparatus is configured to produce a film tape, wherein the recycled material is arranged between at least two other layers in the film tape.

[0118] According to one embodiment, two or more layers are formed by a single extruder. In the case of this embodiment, it is not absolutely necessary for these layers to be immediately above each other.

[0119] According to one embodiment, the film blowing apparatus has a machine direction oriented substantially perpendicular to the bottom-top direction.

[0120] The invention likewise comprises the use of a twin-screw extruder for supplying an annular nozzle of a film blowing device.The film blowing device is preferably constructed according to one of the above-described embodiments.

[0121] In addition, an exemplary method for providing the product of the present invention includes an exemplary method for producing a film tape using recycled materials, preferably on a blown film device. It is provided that a twin-screw extruder melts and homogenizes the recycled materials into a melt, and then an annular nozzle melt pump is used to transport the melt to an annular nozzle via a melt stream. The melt is extruded into a film tube via an annular nozzle, and then the film tube is drawn longitudinally and transversely at a tube forming zone or stretched longitudinally and transversely, respectively. After the tube forming zone is a folding section for the film tube, which folds the film tube into a double-layer film tape outside the tube forming zone. A pair of traction rollers for traction of the film tube are positioned outside the folding section.

[0122] Furthermore, the melt stream can also be filtered by means of a filter having at least one filter element in the melt stream by directing the melt stream from the unfiltered side to the filtered side. The filter is preferably arranged in the melt stream between the extruder and the annular nozzle, the filter is preferably arranged between the extruder and the annular nozzle melt pump.

[0123] The filter system is preferably constructed according to the above-described filter system of the film blowing device.A filter melt pump can be provided which is arranged between the extruder and the annular nozzle melt pump and pumps the melt to the filter or respectively increases the pressure in the melt flow to the filter system.

[0124] The twin-screw extruder may also have at least one degassing unit as described above, which degases the melt, thus extracting impurities and contaminants.

[0125] According to one embodiment, the extruder is filled with recycled material via a recycled material supply device having the above-mentioned filling screw.

[0126] According to one embodiment, a pressure sensor acquires the melt pressure in the melt flow at the extruder, and another pressure sensor acquires the melt pressure in the melt flow upstream of the annular nozzle. The control and regulation device can regulate the extruder and / or the annular nozzle melt pump and / or the recycling material supply device according to the melt pressure in the melt flow at the extruder and / or the melt flow upstream of the annular nozzle. This enables continuous extrusion of recycling material.

[0127] According to one embodiment, an additional pressure sensor acquires the melt pressure in the melt flow upstream of the filter and an additional pressure sensor acquires the melt pressure in the melt flow downstream of the filter. The first pressure sensor preferably acquires the melt pressure in the immediate vicinity of the extruder or outside the extruder. The second pressure sensor preferably acquires the melt pressure upstream of the annular nozzle or directly at the annular nozzle. In an alternative embodiment, the second pressure sensor is arranged upstream of the annular nozzle melt pump and acquires the melt pressure there.

[0128] The shut-off pressure is preferably monitored by means of a pressure sensor, which directly acquires the melt pressure at the annular nozzle. The shut-off pressure is intended to provide information about whether the maximum pressure has been reached in the melt flow. For example, if the temperature at the annular nozzle is too low and the recycled material can no longer be transported through the annular nozzle in the required amount, the maximum pressure is reached in the melt flow. The pressure sensor directly arranged at the annular nozzle can be used to regulate the speed of the annular nozzle melt pump. Another pressure sensor for monitoring another shut-off pressure can also be arranged close to the upstream of the filter. The pressure sensor arranged close to the upstream of the filter can also enable or disable the regulation of the cleaning device. The pressure sensor arranged close to the downstream of the extruder is preferably used to regulate the extruder speed. The pressure sensor arranged close to the downstream of the filter is preferably used to regulate the speed of the filter melt pump and / or the speed of the annular nozzle melt pump.

[0129] According to one embodiment, the control and regulating device regulates the extruder and / or the annular nozzle melt pump and / or the recycling material supply device and / or the filter deflection device and / or the filter element changing device as a function of the melt pressure in the melt flow upstream and / or downstream of the filter.

[0130] The control and regulating device particularly preferably regulates the deflection device of the extruder and / or the annular nozzle melt pump and / or the recycling material supply device and / or the filter based on pressure sensors for detecting the melt pressure in the melt flow at the extruder and in the melt flow upstream of the annular nozzle and additional pressure sensors for detecting the melt pressure in the melt flow upstream and downstream of the filter.

[0131] In the simplest case, the pressure drop at the filter, ie the resistance of the filter in the filter flow, is acquired by means of a pressure sensor. If a threshold value is exceeded, the above-mentioned cleaning device of the filter can be activated in order to replace the filter element of the filter.

[0132] According to one embodiment, the film blowing plant has a screw conveyor for conveying the recycled material from the above-mentioned storage silo to the recycled material supply device.

[0133] According to one embodiment, the screw conveyor conveys the recycled material from the storage silo to the recycled material supply device of the extruder depending on the filling level of the storage silo and / or the recycled material consumption and / or the melt pressure in the melt flow at at least one of the above-mentioned pressure sensors.

[0134] According to one embodiment, the storage silo is filled with recycled material from the distribution silo depending on the filling level of the storage silo. The storage silo is particularly preferably filled with recycled material from the distribution silo depending on the recycled material consumption of the storage silo. The storage silo is preferably filled in such a way that the amount of recycled material in the storage silo does not fall below a minimum value. This is intended to ensure that the recycled material, more precisely the fluff, is supplied to the twin-screw extruder in a constant and uniform manner.

[0135] According to one embodiment, the recycled material is mixed with other materials in a mixing silo. In order to introduce the recycled material and / or its mixture into the storage silo, the mixing silo is preferably connected to the storage silo and / or the distribution silo via a blower and / or a conveyor belt and / or a screw conveyor. This design allows a particularly constant material supply to the extruder and a constant material processing.

[0136] According to one embodiment, the starting material is shredded into recycled material by a shredder. The shredder is preferably constructed according to one of the above-described embodiments.

[0137] According to one embodiment, the transport device transports the recycled material from the shredder via a conveyor belt or a pressure conveying system to a storage silo and / or a distribution silo. If the blown film plant has a mixing silo, the mixing silo is preferably also filled with shredded material from the shredder.

[0138] According to one embodiment, in addition to the recycled material, pelletized material, preferably pelletized recycled material, is additionally or alternatively added to the extruder.According to one embodiment, the pelletized material is added to the extruder or the recycled material supply via a pellet metering device.

[0139] According to one embodiment, pelletized material is added to the extruder in addition or alternatively to the recycled material depending on the filling level of the storage silo and / or the recycled material consumption and / or the melt pressure in the melt stream at one of the above-mentioned pressure sensors.

[0140] According to one embodiment, the film with recycled material is extruded, in addition to the layer made of recycled material, into at least one further layer also with another plastic.

[0141] According to one embodiment, the recycled material is extruded with at least one further layer of further plastic on each flat side. BRIEF DESCRIPTION OF THE DRAWINGS

[0142] Further advantages and aspects of the invention are set forth in the claims and in the following description of preferred exemplary embodiments of the invention, which are illustrated below using the figures.

[0143] Figure 1 A detail of a schematic exemplary embodiment of a film blowing apparatus according to the invention is shown. DETAILED DESCRIPTION

[0144] Figure 1 A film blowing device 10 according to the invention is shown, which is provided for producing film strips from recycled material 4 .

[0145] The film blowing apparatus 10 has an extruder 20 for melting and homogenizing the recycled material 4 into a melt. In this exemplary embodiment, the extruder 20 is arranged horizontally on the floor.

[0146] The extruder 20 is configured as a twin-screw extruder. In this exemplary embodiment, the extruder 20 is a co-rotating twin-screw extruder that is tightly meshed with each other.

[0147] In the present application, the recycled material 4 is a plastic from the group consisting of polymers, polycondensates, polyethylene, polypropylene, thermoplastics, ionomers, ethylene copolymers, cyclic olefin copolymers, polyamides, thermoplastic elastomers, polyethylene terephthalate, polyisobutylene, bio-based plastics and biodegradable plastics.

[0148] The extruder 20 is driven by an electric motor. In this exemplary embodiment, the extruder 20 has a normal pressure degassing unit and a vacuum degassing unit 24. The vacuum degassing unit 24 is operatively connected to a vacuum pump 26. The vacuum degassing unit 24 has a device for collecting condensate. The extruder 20 has a guide 40 for a melt stream, which flows to an annular nozzle 30 for extruding a film tube 6. An annular nozzle melt pump 42 is arranged between the extruder 20 and the annular nozzle 30, and the annular nozzle melt pump 42 conveys the melt to the annular nozzle 30. Due to this design, the pressure in the melt stream does not have to be established completely by the extruder 20, but can be established and / or increased by the annular nozzle melt pump 42. After the annular nozzle 30 is a tube forming zone 32 for drawing the film tube 6 in the longitudinal direction and in the transverse direction. The blown film device 10 has a cooling device 34 for the film tube 6 moving in the machine direction. In the present application, the cooling device 34 is air blown into or respectively onto the blown film tube 6. In addition to the tube forming area 32, the blown film device 10 has a folding section 36 for folding the film tube 6 into a double-layer film strip 8. In addition to the folding section 36, a pair of pulling rollers 38 are arranged, which are arranged outside the cooling device 34 to pull the film tube 6.

[0149] In this exemplary embodiment, the film blowing device 10 has a filter 50, which is arranged between the annular nozzle melt pump 42 and the extruder 20. In this exemplary embodiment, a filter melt pump 60 is arranged between the filter 50 and the extruder 20. In addition, the extruder 20 has a recycling material supply device 44 with a filler screw 46. The filler screw 46 is driven by an electric motor. In this exemplary embodiment, the film blowing device 10 has a shredder 80, into which the starting material 2 can be fed, and the starting material 2 is crushed into recycling material 4. The starting material 2 can be a plastic from the aforementioned group. The starting material 2 can exist in the form of sheet material, crushed sheet material, shredded film, etc. The shredder 80 shreds the starting material 2 into flakes with a size between 5mm and 12mm. The shredder 80 has a transport device 82, which transports the shredded recycling material 4 to the distribution silo 100. The distribution silo 100 is arranged above the storage silo 90 and has a metering device 102, through which the recycling material 4 can be discharged into the storage silo 90 if necessary. In this exemplary embodiment, the metering device 102 is configured as a slide. The storage silo 90 has a device for mixing the recycling material 92, which is configured as a stirrer in this exemplary embodiment. The recycling material 4 is guided from the storage silo 90 to the recycling material supply device 44 at the extruder 20 via a screw conveyor 94.

[0150] The storage silo 90 has a device for determining the consumption of recycled material. In this exemplary embodiment, the device for determining the consumption of recycled material is configured as a weighing device of the storage silo 96. Thus, the consumption of recycled material 4 can be determined as a unit weight per unit time. In this exemplary embodiment, the device for determining the filling level of the storage silo 90 is realized by the weighing device of the storage silo 96. As soon as the filling level and therefore the weight of the storage silo 90 is below a predetermined value, the storage silo 90 is filled with recycled material 4 from the distribution silo 100.

[0151] In addition to the recycled material 4, the recycled material supply device 44 is configured to receive the pelletized recycled material 4 so as to convey it to the extruder 20. To this end, the blown film apparatus 10 has a pellet metering device 110 for storing and metering the pelletized material. The pelletized material is preferably virgin material and / or a higher quality recyclate than the recycled material.

[0152] A pressure sensor 70 acquires the melt pressure in the melt flow at the extruder 20, and another pressure sensor 76 acquires the melt pressure in the melt flow upstream of the annular nozzle 30. A control and regulation device (not depicted) regulates the extruder 20, the annular nozzle melt pump 42 and the recycling material supply device 44 as a function of the melt flow at the extruder 20 and the melt pressure in the melt flow upstream of the annular nozzle 30. This enables continuous extrusion of the recycling material 4.

[0153] Additional pressure sensor 72 acquires the melt pressure in the melt stream upstream of filter 50, and additional pressure sensor 74 acquires the melt pressure in the melt stream downstream of filter 50. First pressure sensor 70 acquires the melt pressure outside extruder 20. Second pressure sensor 76 acquires the melt pressure directly at annular nozzle 30.

[0154] The cut-off pressure is monitored by means of a pressure sensor 76, which directly acquires the melt pressure at the annular nozzle 30. The cut-off pressure provides information about whether the maximum pressure has been reached in the melt flow. For example, if the temperature at the annular nozzle 30 is too low and the recycled material 4 can no longer be conveyed through the annular nozzle 30 in the required amount, the maximum pressure is reached in the melt flow. The pressure sensor 76 arranged directly on the annular nozzle 30 is used to adjust the speed of the annular nozzle melt pump 42. Another pressure sensor 72 for monitoring another cut-off pressure is also arranged immediately upstream of the filter 50. The pressure sensor 72 arranged immediately upstream of the filter 50 is also used to adjust the cleaning device. The pressure sensor 70 arranged immediately downstream of the extruder 20 is used to adjust the extruder speed. The pressure sensor 74 arranged immediately downstream of the filter 50 is used to adjust the speed of the filter melt pump 60 and the speed of the annular nozzle melt pump 42.

[0155] Reference numerals:

[0156] 2 Starting materials;

[0157] 4. Recycled materials;

[0158] 6 membrane tube;

[0159] 8 double-layer membrane tape;

[0160] 10. Film blowing equipment;

[0161] 20 Extruder;

[0162] 22 atmospheric pressure degassing unit;

[0163] 24 Vacuum degassing unit;

[0164] 26 Vacuum pump;

[0165] 28 condensate collector;

[0166] 30 annular nozzle;

[0167] 32 Tube formation zone;

[0168] 34 Cooling device;

[0169] 36 folding sections;

[0170] 38 a pair of traction rollers;

[0171] 40 guide piece;

[0172] 42 annular nozzle melt pump;

[0173] 44 Recycling material supply device;

[0174] 46 packing screw;

[0175] 50 filters;

[0176] 52 filter element;

[0177] 60 filter melt pump;

[0178] 70 pressure sensor;

[0179] 72 pressure sensor;

[0180] 74 pressure sensor;

[0181] 76 pressure sensor;

[0182] 80 Chopper;

[0183] 82 transport devices;

[0184] 90 storage silos;

[0185] 92 Apparatus for mixing recycled materials;

[0186] 94 Screw conveyor;

[0187] 96 Weighing devices for storage silos;

[0188] 100 distribution silos;

[0189] 102 metering device;

[0190] 110 Aggregate metering device.

Claims

1. A film blowing device for producing film strips using recycled materials, characterized in that: a. The film blowing device (10) has an extruder (20) for melting and homogenizing the recycled material (4) into a melt, and b. The film blowing device (10) has an annular nozzle (30) for extruding a film tube (6), and c. the film blowing device (10) has a guide (40) for the melt flow, between the extruder (20) and the annular nozzle (30), the melt is conveyed to the annular nozzle (30) via an annular nozzle melt pump (42), and d. the film blowing device (10) has a tube forming zone (32) for drawing the film tube (6) in the longitudinal direction and in the transverse direction, e. The film blowing device (10) has a cooling device (34) for the film tube (6) moving in the machine direction, and f. The film blowing device (10) has a folding section (36) outside the tube forming area (32) for folding the film tube (6) into a double-layer film strip (8), and g. The film blowing device (10) has a pair of traction rollers (38) for traction of the film tube (6) outside the cooling device (34), and It is also characterized by: h. The extruder (20) is configured as a twin-screw extruder.

2. The film blowing equipment according to claim 1, characterized in that: a. the blown film device (10) has a filter (50), the filter (50) having at least one filter element (52) for filtering the melt from an unfiltered side to a filtered side, and b. The filter (50) is arranged in the guide (40) for the melt flow between the extruder (20) and the annular nozzle (30).

3. The film blowing equipment according to claim 2, characterized in that: The filter is arranged between the extruder (20) and the annular nozzle melt pump (42).

4. The film blowing equipment according to claim 2 or 3, characterized in that: a. The filter (50) has a cleaning device for continuously and / or discontinuously replacing the filter element (52).

5. The film blowing equipment according to claim 4, characterized in that: The film blowing device also has at least one of the following additional features: b. the cleaning device is configured to replace the filter element (52) during operation of the device, i.e. while the membrane tape is being produced, c. the cleaning device has a rotatable filter element (52) or a rotatable cleaning element for replacing the filter element (52), d. the cleaning device has a filter element (52) that can be moved relative to the melt flow or a cleaning element that can be moved relative to the melt flow for replacing the filter element (52), e. the cleaning device has a deflection device for cleaning the filter element (52) by temporarily directing the melt from the filtered side to the unfiltered side, ie in the opposite direction to the normal melt flow, f. The cleaning device has a cleaning outlet through which the melt guided from the filtered side to the unfiltered side is discharged, g. The cleaning device has a screen changer configured to direct the melt stream through a plurality of filter elements (52), and h. The cleaning device is configured to direct the melt stream selectively through a single and / or all available filter elements (52).

6. The film blowing equipment according to any one of claims 1 to 3, characterized in that: a. The film blowing apparatus (10) has a filter melt pump (60) between the extruder (20) and the annular nozzle melt pump (42), and the filter melt pump (60) pumps the melt to the filter (50).

7. The film blowing equipment according to any one of claims 1 to 3, characterized in that: a. The twin-screw extruder has at least one degassing unit (22) capable of extracting impurities and contaminants.

8. The film blowing equipment according to claim 7, characterized in that: The film blowing device also has at least one of the following additional features: b. at least one degassing unit (22) is configured as an atmospheric degassing unit (22), c. At least one degassing unit (22) is configured as a vacuum degassing unit (24).

9. The film blowing equipment according to claim 7, characterized in that: a. The vacuum degassing unit (24) has a device for collecting condensate generated during vacuum degassing.

10. The film blowing equipment according to any one of claims 1 to 3, characterized in that: a. The extruder (20) has a recycled material supply (44) with a feed screw (46).

11. The film blowing equipment according to any one of claims 1 to 3, characterized in that: a. the blown film device (10) has at least two pressure sensors (70, 72, 74, 76) for acquiring the pressure in the guide (40) for the melt stream, in each case acquiring the pressure in the melt stream at the extruder (20) and in the melt stream upstream of the annular nozzle (30), and b. The extruder (20) and / or the annular nozzle melt pump (42) and / or the recycled material supply device (44) can be adjusted according to the melt flow at the extruder (20) and / or the melt pressure in the melt flow upstream of the annular nozzle (30).

12. The film blowing equipment according to any one of claims 1 to 3, characterized in that: a. the film blowing device (10) has two additional pressure sensors (70, 72, 74, 76) for acquiring the melt pressure in the melt flow upstream and downstream of the filter (50), and b. The extruder (20) and / or the annular nozzle melt pump (42) and / or the recycling material supply device (44) and / or the deflection device of the filter (50) and / or the filter element replacement device can be adjusted according to the melt pressure upstream and / or downstream of the filter (50).

13. The film blowing equipment according to claim 12, characterized in that: c. The deflection device of the extruder (20) and / or the annular nozzle melt pump (42) and / or the recycled material supply device (44) and / or the filter (50) can be adjusted according to the pressure sensors (70, 72, 74, 76) for obtaining the melt pressure in the melt flow at the extruder (20) and upstream of the annular nozzle (30) and the additional pressure sensors (70, 72, 74, 76) for obtaining the melt pressure in the melt flow upstream and downstream of the filter (50).

14. The film blowing equipment according to any one of claims 1 to 3, characterized in that: a. The film blowing device (10) has a storage silo (90) for storing the recycled material (4).

15. The film blowing equipment according to any one of claims 1 to 3, characterized in that: a. The film blowing device (10) has a screw conveyor (94) for conveying the recycled material (4) from the storage silo (90) to the recycled material supply device (44).

16. The film blowing equipment according to any one of claims 1 to 3, characterized in that: a. The storage silo (90) has a device for mixing the recycling material (4) within the storage silo (90).

17. The film blowing equipment according to any one of claims 1 to 3, characterized in that: a. The storage silo (90) has means for determining the filling level of the recycling material (4).

18. The film blowing equipment according to any one of claims 1 to 3, characterized in that: a. The storage silo (90) has a device for determining its consumption of recycled material.

19. The film blowing equipment according to claim 18, characterized in that: b. The device for determining the consumption of recycled material is a weighing device of the storage silo (96).

20. The film blowing equipment according to any one of claims 1 to 3, characterized in that: a. The film blowing device (10) has a distribution silo (100) for filling the recycling material (4) in the storage silo (90).

21. The film blowing equipment according to any one of claims 1 to 3, characterized in that: a. The film blowing device (10) has a shredder (80) for crushing the starting material (2), and b. The shredder (80) is configured to shred the starting material (2) into the recycled material (4).

22. The film blowing equipment according to any one of claims 1 to 3, characterized in that: a. the film blowing device (10) has a transport device (82) for transporting the recycled material (4) from the shredder (80) to the storage silo (90) and / or the distribution silo (100), and b. The transport device (82) is constructed as a conveyor belt and / or a screw conveyor or a pressure conveying system.

23. The film blowing equipment according to any one of claims 1 to 3, characterized in that: a. The film blowing device (10) has at least one mixing silo for mixing the recycled material (4) with other materials.

24. The film blowing equipment according to claim 23, characterized in that: b. The mixing silo is connected to the storage silo (90) and / or the distribution silo (100) via a blower and / or a conveyor belt and / or a screw conveyor for introducing the recycled material (4) and / or its mixture.

25. The film blowing equipment according to any one of claims 1 to 3, characterized in that: a. The recycled material supply device (44) is configured to receive pelletized recycled material (4) in addition to or in lieu of the recycled material (4) for delivery to the extruder (20).

26. The film blowing equipment according to claim 25, characterized in that: The film blowing device also has at least one of the following additional features: b. The film blowing device (10) has a pellet metering device (110) for storing and metering the pellet material, c. The pelletized material is virgin material and / or a higher quality recyclate than the recycled material.

27. The film blowing device according to any one of claims 1 to 3, characterized in that: a. The pellet metering device (110) has a screw conveyor for conveying the recycled material (4) to the extruder (20).

28. The film blowing device according to any one of claims 1 to 3, characterized in that: a. the blown film device (10) is configured to produce a film strip having at least one further layer in addition to the layer made of the recycled material (4), and b. The film blowing device (10) has at least one additional extruder (20) for melting and homogenizing the material of at least one additional layer into a melt.

29. The film blowing device according to claim 28, characterized in that: c. The additional extruder is configured as a twin-screw extruder.

30. The film blowing device according to claim 28, characterized in that: a. The blown film apparatus (10) is configured to produce a film strip, wherein the recycled material (4) is arranged between at least two other layers in the film strip.

31. The film blowing device according to claim 30, characterized in that: a. The film blowing apparatus (10) has a machine direction oriented substantially perpendicular to the bottom-top direction.

32. A film blowing device, characterized in that: The film blowing apparatus comprises a twin-screw extruder which is used to feed an annular nozzle (30).

Images