Method for producing a blown film

Abstract

The invention relates to a method for producing a blown film (4) from a fluorine-free polymer mixture (PG) using a blown film extrusion system (2) which has a blow head (2.1) having a nozzle (10), wherein the nozzle (10) has a nozzle region (6) which can be temperature-controlled separately and which is separated from a main body (8) of the nozzle (10) via a temperature-control separating portion (12), said method comprising the steps of: transferring (100) the fluorine-free polymer mixture (PG) through a melt channel (14) of the blow head (2.1) into the separately temperature-controllable nozzle region (6); executing a targeted temperature control (200) of the separately temperature-controllable nozzle region (6) for controlling the temperature of the fluorine-free polymer mixture (PG); and discharging (300) the temperature-controlled fluorine-free polymer mixture (PG) through an outlet gap (16) of the nozzle (10) for producing the blown film (4).

Description

[0001] ßols & Vogel

[0002] Windmöller & Hölscher KG Dept. VO-PAT

[0003] Münsterstr. 50 49525 Lengerich

[0004] Method for producing blown film

[0005] Description

[0006] The present invention relates to a method for producing a blown film from a fluorine-free polymer mixture using a blown film extrusion plant, a blown film extrusion plant for producing a blown film from a fluorine-free polymer mixture, and a fluorine-free polymer mixture for producing a blown film.

[0007] During polymer extrusion, surface defects can sometimes form at the exit of the extrusion die of the polymer melt. These surface defects—known as melt fracture—arise from shearing of the polymers against the die wall and their spontaneous loss of wall adhesion upon exiting the die. Such phenomena occur primarily with high-viscosity materials that exhibit high shear at the surface.

[0008] This problem can be counteracted by reducing wall adhesion or wall friction. For decades, the application of PTFE (polytetrafluoroethylene) to the die wall has proven to be the method of choice. The PTFE, known as AMF (Anti-Melt Fracture), is added to the polymer directly in the extruder of an extrusion line. The AMF, including its carrier material, is immiscible with the polymer, forming a second phase in the melt. This promotes the adhesion of the AMF to the die surface, creating a lubricating film. This film reduces wall friction and thus effectively prevents melt fracture. WH49323-PCT ßols & Vogel

[0009] Unfortunately, it has been known for some time that fluoropolymers accumulate in the environment and are only very partially biodegradable. For this reason, a ban on these polymers is being prepared in the EU and the USA.

[0010] Alternatively, effective prevention of melt fracture can be achieved through a targeted combination of cooling and heating of the molten material before it exits the nozzle. However, a disadvantage is that cooling within a cooling zone negatively affects an adjacent heating zone, and heating within a heating zone negatively affects an adjacent cooling zone. Therefore, the temperature can only be varied within a limited temperature range, and the effect of a targeted combination of cooling and heating of the molten material before it exits the nozzle is limited.Although it is possible to increase the variable temperature range by selectively introducing thermal breaks between a cooling area and a heating area, it has been found that even the introduction of local thermal breaks alone cannot effectively prevent melting fractures.

[0011] It is therefore the object of the present invention to at least partially overcome the aforementioned disadvantages of known methods and equipment for the production of blown film. In particular, it is the object of the invention to provide a method and a starting material by means of which high-quality blown films can be produced sustainably, in an environmentally friendly and efficient manner.

[0012] The foregoing problem is solved by a method with the features of the independent method claim, a blown film extrusion plant with the features of the independent apparatus claim, and a polymer mixture with the features of the independent product claim. Further features and details of the invention will become apparent from the respective dependent claims and the description. Features and details described in connection with the method according to the invention naturally also apply in connection with the blown film extrusion plant according to the invention, or the product according to the invention, and vice versa, so that the disclosure of the individual aspects of the invention always includes or allows for reciprocal reference. WH49323-PCT ßols & Vogel

[0013] According to the invention, a method for producing a blown film from a fluorine-free polymer mixture is provided, using a blown film extrusion system comprising a blowing head with a nozzle, wherein the nozzle has a separately temperature-controlled nozzle section that is separated from a base body of the nozzle by a temperature control section. The method according to the invention comprises the steps of transferring the fluorine-free polymer mixture through a melting channel of the blowing head into the separately temperature-controlled nozzle section, selectively temperature-controlling the separately temperature-controlled nozzle section to control the temperature of the fluorine-free polymer mixture, and expelling the temperature-controlled fluorine-free polymer mixture through an exit gap of the nozzle to produce the blown film.

[0014] Within the scope of the present invention, it has been recognized that by combining the process steps according to the invention using a fluorine-free polymer mixture according to the invention and a blown film extrusion system, which has a blowing head with a nozzle having a separately temperature-controlled nozzle area that is separated from a base body of the nozzle via a temperature control section, a high-quality blown film can be produced in a sustainable, environmentally friendly and effective manner.Within the scope of the invention, it has been recognized in particular that the use of PTFE to reduce shear during the exit of a polymer material from a die of a blown film extrusion line can also be substituted by the use of fluorine-free polymers, provided that a blown film extrusion line is used which has a blow head with a die having a separately temperature-controlled die section that is separated from the main body of the die by a temperature control section. It is understood that "fluorine-free" can also include polymer mixtures that contain fluorine only in trace amounts of < 0.1 wt.%. According to the invention, a temperature control section can be understood as an at least partial or section-by-section separation of a direct connection between a first and an adjacent second section of a die.

[0015] To achieve the most effective prevention of melting fractures, the invention advantageously provides that the targeted temperature control of the separately temperature-controlled nozzle area comprises heating within a heating zone and / or cooling within a cooling zone of the separately temperature-controlled nozzle area. WH49323-PCT ßols & Vogel

[0016] To prevent shearing of a polymer mixture as effectively as possible, it can be particularly advantageous if the separately temperature-controlled nozzle area is temperature-controlled, at least section by section, by means of a temperature control device, such that the fluorine-free polymer mixture is cooled and / or heated by more than 10%.

[0017] In the context of the production of high-quality blown films, it can also be advantageous if the fluorine-free polymer mixture within the separately temperature-controlled nozzle area is cooled to a temperature of < 180 °C, preferably < 150 °C and / or heated to a temperature of > 200 °C, preferably > 250 °C.

[0018] For more targeted temperature control of the fluorine-free polymer mixture, it can also be advantageous if the fluorine-free polymer mixture is transferred within the separately temperature-controlled nozzle area in such a way that it flows through the separately temperature-controlled nozzle area at two different flow rates. Preferably, the fluorine-free polymer mixture is transferred within the heating and cooling areas such that the flow rate within the heating area is 1.5 to 15 times higher than the flow rate within the cooling area. A different flow rate can advantageously be influenced or generated by different gap geometries.

[0019] With a view to effectively suppressing shear of a first fluorine-free polymer upon exiting a die, it can advantageously be provided that the fluorine-free polymer mixture comprises a first fluorine-free polymer based on PE and a second fluorine-free polymer to reduce shear upon exit of the first fluorine-free polymer from the die of the blown film extrusion line, wherein the second fluorine-free polymer has an MFI of > 10. The MFI (Melt Flow Index) is an important characteristic of the flow properties of thermoplastic polymers, indicating how easily a polymer can be melted and extruded. The MFI is typically measured by a standardized test in which the polymer in question is extruded through a specific die under standardized conditions.The measurement is preferably performed in grams per 10 minutes (g / 10 min) and indicates how much material flows through the nozzle in that time. A high MFI value therefore means that the polymer flows easily and has a low viscosity, indicating good processability. A low MFI value (WH49323-PCT ßols & Vogel), on the other hand, indicates a polymer with higher viscosity and difficult processability. A test method described above for determining the MFI of polymers is specified or standardized, for example, in ISO 1133, ASTM D1238, or DIN EN ISO 1133 (preferably at the time of application).

[0020] With a view to effectively suppressing shear stress in a first fluorine-free polymer upon exiting a nozzle, it is advantageously provided that the second fluorine-free polymer is present in the fluorine-free polymer mixture in a proportion of > 1 wt.%, preferably > 2 wt.%, and in particular in a proportion of 2-3 wt.%, and / or that the first fluorine-free polymer is present in the fluorine-free polymer mixture in a proportion of > 90 wt.%, preferably in a proportion of 97-99 wt.%. Within the scope of the invention, it has been recognized that melt fracture can be prevented particularly effectively at the aforementioned proportions of the first and second fluorine-free polymers. Thus, the polymer mixture can preferably consist of only two components, the first fluorine-free polymer and the second fluorine-free polymer. However, it is also possible for further polymers and / or further components, e.g., in the form of additives, to be present.

[0021] Advantageously, the first fluorine-free polymer and the second fluorine-free polymer can be present in the fluorine-free polymer mixture in a P1 / P2 ratio of 99 / 1 to 90 / 10.

[0022] With a view to suppressing shear stress as effectively as possible in a first fluorine-free polymer upon exiting a nozzle, it is advantageously provided that the first and second fluorine-free polymers are not in a homogeneous phase and / or are not miscible to form a homogeneous phase. By forming a second phase within the polymer mixture, the properties of the PTFE being replaced as an AFM can be particularly well adapted.

[0023] To achieve the most targeted possible deposition of the second fluorine-free polymer within the polymer mixture, it can also be advantageous to add the second fluorine-free polymer only after the first fluorine-free polymer has been added, preferably within the extruder. The first and second fluorine-free polymers are added, in particular, in granular or powder form, and / or additional additives are added, preferably in a proportion of less than 1 wt.%. Advantageously, the second WH49323-PCT ßols & Vogel fluorine-free polymer can be added in such a way that it preferably depositions on the wall region of a die in an extrusion system.

[0024] With a view to effectively suppressing shear of a first fluorine-free polymer upon exiting a nozzle, it can advantageously be provided that the second fluorine-free polymer has an MFI of > 100, preferably > 500, in particular > 1000 and / or that the ratio between the MFI of the second fluorine-free polymer and the MFI of the first fluorine-free polymer is > 10, preferably > 50, in particular > 100.

[0025] To ensure optimal extrusion conditions and good environmental compatibility, the first and second fluorine-free polymers may also be peroxide-free and / or halogen-free. Peroxides pose the risk of triggering crosslinking reactions during the extrusion process. Other halogens, such as chlorine or bromine, can also have an environmentally hazardous potential when combined with hydrocarbons.

[0026] Within the context of a wide variety of processes, it may also be provided that the first fluorine-free polymer and / or the second fluorine-free polymer comprises LLDPE, MDPE, VLDPE, HDPE and mixtures thereof and / or that the first fluorine-free polymer and / or the second fluorine-free polymer contains a proportion of PA and / or PP.

[0027] Likewise, with a view to a wide variety of processes, it can be provided that at least one third fluorine-free polymer, preferably more than one third fluorine-free polymer, is present in the fluorine-free polymer mixture, wherein in particular the third fluorine-free polymer and / or the majority of further fluorine-free polymers comprise LLDPE, MDPE, VLDPE, HDPE and mixtures thereof and / or have a proportion of PA and / or PP.

[0028] To ensure the production of high-quality blown films, it can advantageously be further provided that the transfer of the fluorine-free polymer mixture through the melt channel of the blow head and / or the targeted temperature control of the separately temperature-controlled die area and / or the discharge of the temperature-controlled fluorine-free polymer mixture through an exit gap of the die takes place at an extruder temperature and / or die lip temperature of > 200 °C, preferably > 250 °C, and in particular at least 280 °C. Such a temperature selection is important here, both for the WH49323-PCT ßols & Vogel

[0029] The processability of a melt in an extruder, as well as the cleanliness of a production process, are both important factors. For example, a specific die lip temperature can be relevant with regard to deposits on the die, which significantly affect the product quality of an extrudate.

[0030] With a view to achieving high production variability on the one hand, but minimizing shear forces to prevent melt fracture on the other, it can advantageously be provided that the fluorine-free polymer mixture is expelled through an exit gap of the nozzle at a shear rate of 100 s⁻¹. -1 up to 1000 s -1 This has been done.

[0031] The invention also relates to a blown film extrusion system for producing a blown film from a fluorine-free polymer mixture, in particular by applying a method described above, comprising a blowing head, a melt channel for transferring the fluorine-free polymer mixture, and a die with a separately temperature-controlled die section and a base body that is separated from the separately temperature-controlled die section by a temperature control section. The blown film extrusion system according to the invention thus has the same advantages as those already described in detail with regard to the method according to the invention.

[0032] To ensure the most effective prevention of melt fracture in a polymer mixture melt, the invention advantageously provides a temperature control device for the separately temperature-controlled area, wherein the temperature control device preferably comprises a cooling device and / or a heating device. The temperature control device is designed and arranged to temper the material melt in the nozzle assembly. The cooling and heating devices allow the material melt to be selectively tempered to achieve a desirable blown film quality.

[0033] To achieve the most effective combination of cooling and heating a molten material before nozzle exit, thereby preventing melting cracks in a polymer mixture melt, the invention advantageously provides that the cooling device and / or the heating device is annular in design and preferably segmented in a circumferential direction, and in particular, individually controllable. Furthermore, such a design enables advantageous control with regard to a precisely adjustable layer thickness profile of the blown film in question. WH49323-PCT ßols & Vogel

[0034] With a view to achieving particularly effective thermal separation of a heating zone from a cooling zone for temperature variation within the widest possible temperature range, it can also be advantageous for the separately temperature-controlled nozzle area to have a heating zone for heating by means of a heating device and a cooling zone for cooling by means of a cooling device, wherein the heating zone and the cooling zone are separated from each other by a further temperature control partition. The resulting thermal separation between the cooling zone (which can be cooled by the cooling device) and the heating zone (which can be heated by the heating device) due to this further temperature control partition makes it possible to cool the cooling zone and / or heat the heating zone significantly more effectively by the cooling device and / or the heating zone by the heating device without causing undesirable heat transfer between the cooling zone and the heating zone.By using such targeted temperature control, i.e., a defined local limitation when cooling and heating the molten material, any melt fracture can be prevented or at least greatly reduced at high output rates.

[0035] To ensure the most effective prevention of melt fracture at high ejection velocities of a polymer mixture melt, it can also be advantageous to position the cooling zone, for cooling by means of a cooling device, upstream of the heating zone, for heating by means of a heating device, in the flow direction of the fluorine-free polymer mixture. Such an arrangement allows the molten material to be cooled significantly beforehand, thereby modifying the material properties of the molten material or blown film exiting the nozzle device in such a way that a particularly high ejection velocity and output can be achieved.By positioning the heating device downstream of the cooling device, the molten material can be heated before it exits the nozzle assembly through the outlet as blown film, thus preventing or at least largely avoiding the undesirable melting cracking effect. This allows for high output rates while maintaining high blown film quality.

[0036] For a simple and cost-effective thermal separation of a heating zone from a cooling zone to allow temperature variation over the widest possible temperature range, it can also be advantageous if the temperature control separation section and / or the subsequent temperature control separation section is designed as an annular gap. WH49323-PCT ßols & Vogel

[0037] Similarly, for particularly effective thermal separation, the temperature control section and / or the subsequent temperature control section may be designed to incorporate a heat-insulating solid. In addition to providing highly effective thermal insulation, the inclusion of a heat-insulating solid also ensures high nozzle stability.

[0038] In the context of a compact and space-saving design of a blow head, it can also be advantageous if the temperature control section and / or the further temperature control section have a height of less than 10 mm, preferably less than 5 mm. Alternatively, with a view to particularly effective thermal separation of a heating area, it can be provided that the temperature control section and / or the further temperature control section have a height of more than 10 mm, preferably at least 15 mm.

[0039] Similarly, in the context of a compact, space-saving and at the same time effective design of a blow head, it can be advantageous if the heating area has a height that is less than 50%, in particular less than 30%, of the height of the cooling area.

[0040] To prevent molten material deposits at the outlet, it can also be advantageous for the melting channel to have a narrowing and / or widening, with the narrowing preferably being located in a region of the heating zone and the widening in a region of the cooling zone. In this context, a narrowing is understood to mean a reduction in the cross-sectional area of ​​the melting channel. A widening, correspondingly, is understood to mean an increase in the cross-sectional area.

[0041] The invention also relates to a fluorine-free polymer mixture for the production of a blown film, preferably using a method described above, and in particular using a blown film extrusion plant described above. The fluorine-free polymer mixture according to the invention comprises a first fluorine-free polymer based on PE and a second fluorine-free polymer for reducing shear stress upon exit of the first fluorine-free polymer from a die of a blown film extrusion plant, wherein the second fluorine-free polymer has an MFI of > 10 WH49323-PCT ßols & Vogel. Thus, the fluorine-free polymer mixture according to the invention offers the same advantages as those already described in detail with regard to the method and the blown film extrusion plant according to the invention.

[0042] With a view to effectively suppressing shear of a first fluorine-free polymer upon exiting a nozzle, it can advantageously be provided that the second fluorine-free polymer is present in the fluorine-free polymer mixture in a proportion of > 1 wt.%, preferably > 2 wt.%, in particular in a proportion of 2-3 wt.%, and / or that the first fluorine-free polymer is present in the fluorine-free polymer mixture in a proportion of

[0043] > 90 wt.%, preferably to a proportion of 97-99 wt.%.

[0044] Thus, the first fluorine-free polymer and the second fluorine-free polymer in the fluorine-free polymer mixture can advantageously be present in a P1 / P2 ratio of 99 / 1 to 90 / 10.

[0045] With a view to suppressing shear stress as effectively as possible in a first fluorine-free polymer upon exiting a nozzle, it is advantageously provided that the first and second fluorine-free polymers are not in a homogeneous phase or are miscible to form a homogeneous phase, and / or that additional additives are present in the fluorine-free polymer mixture, preferably in a proportion of < 1 wt.%. By forming a second phase within the polymer mixture, the properties of the PTFE to be replaced as an AFM can be particularly well adapted.

[0046] With a view to suppressing shear stress as effectively as possible in a first fluorine-free polymer upon exiting a nozzle, it can advantageously be further provided that the second fluorine-free polymer has an MFI of > 100, preferably of

[0047] > 500, in particular > 1000 and / or the ratio between the MFI of the second fluorine-free polymer and the MFI of the first fluorine-free polymer is > 10, preferably

[0048] > 50, especially > 100.

[0049] To ensure optimal extrusion conditions and good environmental compatibility, the product may also be designed so that the first fluorine-free polymer and the second fluorine-free polymer are peroxide-free and / or halogen-free. WH49323-PCT ßols & Vogel

[0050] Within the context of a wide variety of processes, it may also be provided that the first fluorine-free polymer and / or the second fluorine-free polymer comprises LLDPE, MDPE, VLDPE, HDPE and mixtures thereof and / or that the first fluorine-free polymer and / or the second fluorine-free polymer contains a proportion of PA and / or PP.

[0051] Likewise, with a view to a wide variety of processes, it can be provided that at least one third fluorine-free polymer, preferably more than one third fluorine-free polymer, is present in the fluorine-free polymer mixture, wherein in particular the third fluorine-free polymer and / or the majority of further fluorine-free polymers comprise LLDPE, MDPE, VLDPE, HDPE and mixtures thereof and / or have a proportion of PA and / or PP.

[0052] Further advantages, features, and details of the invention will become apparent from the following description, in which exemplary embodiments of the invention are described in detail, partly with reference to the drawings. The features mentioned in the claims and in the description can each be essential to the invention individually or in any combination.

[0053] They show:

[0054] Fig. 1 shows a schematic representation of the individual steps of a process according to the invention for producing a blown film from a fluorine-free polymer mixture,

[0055] Fig. 2 shows a schematic representation of a blown film extrusion plant according to the invention for producing a blown film from a fluorine-free polymer mixture,

[0056] Fig. 3 shows an enlarged schematic representation of a nozzle of the blown film extrusion system according to the invention for producing a blown film from a fluorine-free polymer mixture.

[0057] Fig. 1 shows a schematic representation of the individual steps of a process according to the invention for producing a blown film 4 from a fluorine-free WH49323-PCT ßols & Vogel

[0058] Polymer mixture PG using a blown film extrusion system 2, which has a blowing head 2.1 with a nozzle 10, wherein the nozzle 10 has a melt channel 14 for transferring 100 of the fluorine-free polymer mixture PG and a separately temperature-controlled nozzle area 6, which is separated from a base body 8 of the nozzle 10 by a temperature control separation section 12 (see Fig. 2 and 3).

[0059] The inventive method comprises the steps of transferring 100 of the fluorine-free polymer mixture PG through a melting channel 14 of the blowing head 2.1 into the separately temperature-controlled nozzle area 6, of targeted temperature control 200 of the separately temperature-controlled nozzle area 6 for temperature control of the fluorine-free polymer mixture PG, and of conveying 300 of the temperature-controlled fluorine-free polymer mixture PG through an exit gap 16 of the nozzle 10 for the production of the blown film 4.

[0060] The targeted temperature control 200 of the separately temperature-controlled nozzle area 6 can include heating within a heating area 6a and / or cooling within a cooling area 6b of the separately temperature-controlled nozzle area 6.

[0061] In this case, the separately temperature-controlled nozzle area 6 can be temperature-controlled at least section by section using the temperature control device 20, such that the fluorine-free polymer mixture PG is cooled and / or heated by more than 10%.

[0062] The fluorine-free polymer mixture PG can be cooled to a temperature of < 180 °C, preferably < 150 °C, within the separately temperature-controlled nozzle area 6 and / or heated to a temperature of > 200 °C, preferably > 250 °C.

[0063] In this process, the fluorine-free polymer mixture PG can be transferred within the separately temperature-controlled nozzle area 6 in such a way that the fluorine-free polymer mixture PG flows through the separately temperature-controlled nozzle area 6 at two different flow rates.

[0064] The fluorine-free polymer mixture PG can also preferably comprise a first fluorine-free polymer P1 based on PE and a second fluorine-free polymer P2, to reduce shear during the exit of the first fluorine-free polymer P1 from the nozzle 10 of the WH49323-PCT ßols & Vogel

[0065] comprising blown film extrusion plant 4, wherein the second fluorine-free polymer P2 preferably has an MFI of > 10.

[0066] The second fluorine-free polymer P2 can advantageously be present in the fluorine-free polymer mixture PG at a proportion of > 1 wt.%, preferably > 2 wt.%. The first fluorine-free polymer P1, on the other hand, can be present in the fluorine-free polymer mixture PG at a proportion of > 90 wt.%, preferably 97-99 wt.%.

[0067] For example, the first fluorine-free polymer P1 and the second fluorine-free polymer P2 can be present in the fluorine-free polymer mixture PG in a P1 / P2 ratio of 99 / 1 to 90 / 10.

[0068] The first fluorine-free polymer P1 and the second fluorine-free polymer P2 preferably do not exist in a homogeneous phase and / or are not miscible to form a homogeneous phase.

[0069] The second fluorine-free polymer P2 can, for example, be added only after the addition of the first fluorine-free polymer P1, preferably within the extruder 6, wherein the first fluorine-free polymer P1 and the second fluorine-free polymer P2 can be added in particular in granular form or in powder form.

[0070] The second fluorine-free polymer P2 can have an MFI of > 100, preferably > 500, and particularly > 1000. The ratio between the MFI of the second fluorine-free polymer P2 and the MFI of the first fluorine-free polymer P1 can preferably be > 10, and particularly > 100.

[0071] The first fluorine-free polymer P1 and the second fluorine-free polymer P2 can advantageously be peroxide-free and / or halogen-free.

[0072] Furthermore, the first fluorine-free polymer P1 and / or the second fluorine-free polymer P2 may contain LLDPE, MDPE, VLDPE, HDPE and mixtures thereof and / or contain a proportion of PA and / or PP.

[0073] Similarly, for example, a third fluorine-free polymer P3, or more than one third fluorine-free polymer P3, may be present in the fluorine-free polymer mixture PG. WH49323-PCT ßols & Vogel

[0074] Furthermore, the transfer 100 of the fluorine-free polymer mixture PG through the melt channel 14 of the blow head 2.1 and / or the targeted temperature control 200 of the separately temperature-controlled nozzle area 6 and / or the discharge 300 of the temperature-controlled fluorine-free polymer mixture PG through an exit gap 16 of the nozzle 10 can be carried out at an extruder temperature and / or nozzle lip temperature of > 200 °C, preferably of > 250 °C, in particular of at least 280 °C.

[0075] Fig. 2 shows a schematic representation of a blown film extrusion plant 2 according to the invention for producing a blown film 4 from a fluorine-free polymer mixture PG. Fig. 3 shows an enlarged schematic representation of a die 10 of the blown film extrusion plant 2 according to the invention for producing a blown film 4 from a fluorine-free polymer mixture PG.

[0076] As can be seen in Figs. 2 and 3, the blown film extrusion system 2 according to the invention comprises a nozzle 10, with a melt channel 14 for transferring 100 of the fluorine-free polymer mixture PG, a separately temperature-controlled nozzle area 6 and a base body 8, which is separated from the separately temperature-controlled nozzle area 6 by a temperature control separation section 12.

[0077] The fluorine-free polymer mixture PG is obtained – as shown in Fig. 2 – by feeding a first fluorine-free polymer P1 and a second fluorine-free polymer P2 into an extruder 7 of the blown film extrusion plant 2 via a metering device 9. As shown in Fig.

[0078] As shown in Figure 2, the extruder 7 has a screw 7.1 for conveying the fluorine-free polymer mixture PG into the blow head 2.1 of the blown film extrusion plant 2.

[0079] After the blown film 4 exits the exit gap 16 of the nozzle 10, the material is cooled via the temperature control unit 18 and rolled by the roller 20 into a flat blown film 4, which is transported further via deflection rollers 20 and finally wound up by a winding device 24.

[0080] As can be seen in the enlarged view of the nozzle 10 according to Fig. 3, a cooling device 6.2 and a heating device 6.1, which are annular in design, are arranged within the separately temperature-controlled area 6. The cooling device 6.2 and the heating device 6.1 can, for example, be segmented, with the individual segments preferably being individually controllable. WH49323-PCT ßols & Vogel

[0081] The separately temperature-controlled nozzle area 6 is divided into a heating area 6a for heating by means of the heating device 6.1 and a cooling area 6b for cooling by means of the cooling device 6.2, wherein the heating area 6a and the cooling area 6b are separated from each other by a further temperature control separation section 12'.

[0082] The cooling zone 6b for cooling by means of the cooling device (6.2) is arranged in the direction of flow of the fluorine-free polymer mixture PG upstream of the heating zone 6a.

[0083] The temperature control separation section 12 and the further temperature control separation section 12' are also designed as an annular gap or a groove-shaped incision. For improved thermal insulation and dimensional stability, the temperature control separation section 12 and the further temperature control separation section 12' can also have a thermally insulating solid instead of an air gap.

[0084] The temperature control separation sections 12 12' can, for example, have a height of less than 10 mm, preferably a height of less than 5 mm.

[0085] Furthermore, the heating area 6a may have a height that is less than 50%, in particular less than 30%, of the height of the cooling area 6b.

[0086] Finally, the melt channel 14 can also have a narrowing and / or widening, wherein the narrowing can preferably be arranged in a region of the heating area 6a and the widening in a region of the cooling area 6b.

[0087] WH49323-PCT ßols & Vogel

[0088] Reference sign list

[0089] P1 first fluorine-free polymer

[0090] P2 second fluorine-free polymer

[0091] P3 third fluorine-free polymer

[0092] P4 fourth fluorine-free polymer

[0093] P5 fifth fluorine-free polymer

[0094] PG fluorine-free polymer mixture

[0095] 2 blown film extrusion lines

[0096] 2.1 Blowhead

[0097] 4 blown film

[0098] 6 temperature-controlled nozzle area

[0099] 6.1 Heating device

[0100] 6.2 Cooling device

[0101] 6a Heating area

[0102] 6b Cooling area

[0103] 7 extruders

[0104] 7.1 Snail

[0105] 8 basic shapes

[0106] 9 Dosing device

[0107] 10 nozzles

[0108] 12 Temperature control separation section

[0109] 12' further temperature control separation section

[0110] 14 Melt channel

[0111] 16 Exit gap

[0112] 18 Tempering agents

[0113] 20 rollers

[0114] 22 Pulley

[0115] 24 Changing unit WH49323-PCT ßols & Vogel

[0116] 100 Transferring a fluorine-free polymer mixture through a melting channel into a separately temperature-controlled nozzle area

[0117] 200 Targeted temperature control of the separately temperature-controlled nozzle area for

[0118] Temperature control of the fluorine-free polymer mixture

[0119] 300 Extraction of the tempered fluorine-free polymer mixture through a

[0120] Exit gap of the nozzle for the production of blown film

Claims

WH49323-PCT ßols & Vogel Patent claims 1. A method for producing a blown film (4) from a fluorine-free polymer mixture (PG) using a blown film extrusion plant (2) having a blowing head (2.1) with a nozzle (10), wherein the nozzle (10) has a melt channel (14) for transferring (100) the fluorine-free polymer mixture (PG) and a separately temperature-controlled nozzle area (6) which is separated from a base body (8) of the nozzle (10) by a temperature control section (12), comprising the steps: Transfer (100) of the fluorine-free polymer mixture (PG) through a melting channel (14) of the blow head (2.1) into the separately temperature-controlled nozzle area (6), - Targeted temperature control (200) of the separately temperature-controlled nozzle area (6) for temperature control of the fluorine-free polymer mixture (PG), Extraction (300) of the tempered fluorine-free polymer mixture (PG) through an exit gap (16) of the nozzle (10) for the production of the blown film (4).

2. Method according to claim 1, characterized in that the targeted temperature control (200) of the separately temperature-controlled nozzle area (6) comprises heating within a heating area (6a) and / or cooling within a cooling area (6b) of the separately temperature-controlled nozzle area (6).

3. Method according to claim 1 or 2, characterized in that the separately temperature-controlled nozzle area (6) is temperature-controlled, at least section by section, by means of a temperature control device (20) such that the fluorine-free polymer mixture (PG) is cooled and / or heated by more than 10%.

4. Method according to one of the preceding claims, characterized in that the fluorine-free polymer mixture (PG) is cooled to a temperature of < 180 °C, preferably < 150 °C, within the separately temperature-controlled nozzle area (6) and / or heated to a temperature of > 200 °C, preferably > 250 °C. WH49323-PCT ßols & Vogel 5. Method according to one of the preceding claims, characterized in that the fluorine-free polymer mixture (PG) is transferred within the separately temperature-controlled nozzle area (6) such that the fluorine-free polymer mixture (PG) flows through the separately temperature-controlled nozzle area (6) at two different flow rates, wherein preferably the fluorine-free polymer mixture (PG) is transferred within the heating area (6a) and the cooling area (6b) such that the flow rate of the fluorine-free polymer mixture (PG) within the heating area (6a) is 1.5 to 15 times higher than the flow rate of the fluorine-free polymer mixture (PG) within the cooling area (6b).

6. Method according to one of the preceding claims, characterized in that the fluorine-free polymer mixture (PG) comprises a first fluorine-free polymer (P1) The base of PE and a second fluorine-free polymer (P2) for reducing shear at the exit of the first fluorine-free polymer (P1) from the die (10) of the blown film extrusion system (4), wherein the second fluorine-free polymer (P2) has an MFI of > 10.

7. Method according to one of the preceding claims, characterized in that the second fluorine-free polymer (P2) is present in the fluorine-free polymer mixture (PG) to a proportion of > 1 wt.%, preferably > 2 wt.%, in particular to a proportion of 2 - 3 wt.% and / or the first fluorine-free polymer (P1) is present in the fluorine-free polymer mixture (PG) to a proportion of > 90 wt.%, preferably to a proportion of 97-99 wt.%.

8. Method according to one of the preceding claims, characterized in that the first fluorine-free polymer (P1) and the second fluorine-free polymer (P2) are present in the fluorine-free polymer mixture (PG) in a ratio P1 / P2 of 99 / 1 to 90 / 10. WH49323-PCT ßols & Vogel 9. Method according to one of the preceding claims, characterized in that the first fluorine-free polymer (P1) and the second fluorine-free polymer (P2) are not in a homogeneous phase and / or are not miscible to form a homogeneous phase.

10. A method according to any one of the preceding claims, characterized in that the second fluorine-free polymer (P2) is added only after the first fluorine-free polymer (P1), preferably within the extruder (6), wherein the first fluorine-free polymer (P1) and the second fluorine-free polymer (P2) are added, in particular, in granular or powder form, and / or that additional additives are added, wherein the additional additives are preferably added in a proportion of < 1 wt.%.

11. A method according to any one of the preceding claims, characterized in that the second fluorine-free polymer (P2) has an MFI of > 100, preferably > 500, in particular > 1000, and / or the ratio between the MFI of the second fluorine-free polymer (P2) and the MFI of the first fluorine-free polymer is > 10, preferably > 50, in particular > 100.

12. Method according to one of the preceding claims, characterized in that the first fluorine-free polymer (P1) and the second fluorine-free polymer (P2) are peroxide-free and / or halogen-free.

13. Method according to one of the preceding claims, characterized in that the first fluorine-free polymer (P1) and / or the second fluorine-free polymer (P2) comprises LLDPE, MDPE, VLDPE, HDPE and mixtures thereof and / or the first fluorine-free polymer (P1) and / or the second fluorine-free polymer (P2) comprises a proportion of PA and / or PP. WH49323-PCT ßols & Vogel 14. Method according to one of the preceding claims, characterized in that at least one third fluorine-free polymer (P3), preferably more than one third fluorine-free polymer (P3), is present in the fluorine-free polymer mixture (PG), wherein in particular the third fluorine-free polymer (P3) and / or the plurality of further fluorine-free polymers (P4, P5, ...) comprise LLDPE, MDPE, VLDPE, HDPE and mixtures thereof and / or comprise a proportion of PA and / or PP.

15. Method according to one of the preceding claims, characterized in that the transfer (100) of the fluorine-free polymer mixture (PG) through the melting channel (14) of the blow head (2.1) and / or the targeted temperature control (200) of the separately temperature-controlled nozzle area (6) and / or the discharge (300) of the temperature-controlled fluorine-free polymer mixture (PG) through an exit gap (16) of the nozzle (10) takes place at an extruder temperature and / or nozzle lip temperature of > 200 °C, preferably of > 250 °C, in particular of at least 280 °C.

16. Method according to one of the preceding claims, characterized in that the extraction (300) of the fluorine-free polymer mixture (PG) through an exit gap (12) of the nozzle (10) at a shear rate of 100 s -1 up to 1000 s -1 This has been done.

17. Blown film extrusion plant (2) for producing a blown film (4) from a fluorine-free polymer mixture (PG), in particular by applying a method according to one of the preceding claims, comprising a blowing head (2.1): - a nozzle (10) with a melt channel (14) for transferring (100) the fluorine-free polymer mixture (PG), a separately temperature-controlled nozzle area (6) and a base body (8) which is separated from the separately temperature-controlled nozzle area (6) via a temperature control separation section (12).

18. Blown film extrusion plant (2) according to claim 17, characterized in that a temperature control device is provided for temperature control of the separately temperature controllable area (6), wherein the temperature control device preferably comprises a cooling device (6.2) and / or a heating device (6.1). - 21 - WH49323-PCT ßols & Vogel 19. Blown film extrusion system (2) according to claim 17 or 18, characterized in that the cooling device (6.2) and / or the heating device (6.1) is designed in an annular shape and preferably segmented in a circumferential direction, in particular designed to be individually controllable.

20. Blown film extrusion system (2) according to one of claims 17 to 19, characterized in that the separately temperature-controlled die area (6) has a heating area (6a) for heating by means of a heating device (6.1) and a cooling area (6b) for cooling by means of a cooling device (6.2), wherein the heating area (6a) and the cooling area (6b) are separated from each other by a further temperature control separation section (12').

21. Blown film extrusion system (2) according to one of claims 17 to 20, characterized in that the cooling zone (6b) for cooling by means of a cooling device (6.2) is arranged in a flow direction of the fluorine-free polymer mixture (PG) upstream of the heating zone (6a) for heating by means of a heating device (6.1).

22. Blown film extrusion plant (2) according to one of claims 17 to 21 , characterized in that the temperature control separation section (12) and / or the further temperature control separation section (12') is designed as an annular gap.

23. Blown film extrusion plant (2) according to one of claims 17 to 22, characterized in that the temperature control separation section (12) and / or the further temperature control separation section (12') comprises a heat-insulating solid.

24. Blown film extrusion system (2) according to one of claims 17 to 23, characterized in that the temperature control separation section (12) and / or the further temperature control separation section (12') have a height of less than 10 mm, preferably a height of less than 5 mm. - 22 - WH49323-PCT ßols & Vogel 25. Blown film extrusion plant (2) according to one of claims 17 to 24, characterized in that the heating area (6a) has a height which is less than 50%, in particular less than 30%, of the height of the cooling area (6b).

26. Blown film extrusion system (2) according to one of claims 17 to 25, characterized in that the melt channel (14) has a narrowing and / or widening, wherein the narrowing is preferably arranged in a region of the heating area (6a) and the widening in a region of the cooling area (6b).

27. Fluorine-free polymer mixture (PG) for the production of a blown film (4), preferably using a method according to one of claims 1 to 16, in particular using a blown film extrusion plant (2) according to one of claims 17 to 26, comprising: - a first fluorine-free polymer (P1) based on PE, and - a second fluorine-free polymer (P2) for reducing shear during the exit of the first fluorine-free polymer (P1) from a die (10) of a blown film extrusion plant (4), wherein the second fluorine-free polymer (P2) has an MFI of > 10.

28. Fluorine-free polymer mixture (PG) according to claim 27, characterized in that the second fluorine-free polymer (P2) is present in the fluorine-free polymer mixture (PG) to a proportion of > 1 wt.%, preferably > 2 wt.%, in particular to a proportion of 2 - 3 wt.% and / or the first fluorine-free polymer (P1) is present in the fluorine-free polymer mixture (PG) to a proportion of > 90 wt.%, preferably to a proportion of 97-99 wt.%.

29. Fluorine-free polymer mixture (PG) according to one of claims 27 to 28, characterized in that the first fluorine-free polymer (P1) and the second fluorine-free polymer (P2) are present in the fluorine-free polymer mixture (PG) in a ratio P1 / P2 of 99 / 1 to 90 / 10. - 23 - WH49323-PCT ßols & Vogel 30. Fluorine-free polymer mixture (PG) according to any one of claims 27 to 29, characterized in that the first fluorine-free polymer (P1) and the second fluorine-free polymer (P2) are not present in a homogeneous phase or are miscible to form a homogeneous phase and / or additional additives are present in the fluorine-free polymer mixture (PG), preferably in a proportion of < 1 wt.%.

31. Fluorine-free polymer mixture (PG) according to any one of claims 27 to 30, characterized in that the second fluorine-free polymer (P2) has an MFI of > 100, preferably > 500, in particular > 1000 and / or the ratio between the MFI of the second fluorine-free polymer (P2) and the MFI of the first fluorine-free polymer is > 10, preferably > 50, in particular > 100.

32. Fluorine-free polymer mixture (PG) according to one of claims 27 to 31, characterized in that the first fluorine-free polymer (P1) and the second fluorine-free polymer (P2) are peroxide-free and / or halogen-free.

33. Fluorine-free polymer mixture (PG) according to any one of claims 27 to 32, characterized in that the first fluorine-free polymer (P1) and / or the second fluorine-free polymer (P2) comprises LLDPE, MDPE, VLDPE, HDPE and mixtures thereof and / or the first fluorine-free polymer (P1) and / or the second fluorine-free polymer (P2) comprises a proportion of PA and / or PP.

34. Fluorine-free polymer mixture (PG) according to one of claims 27 to 33, characterized in that at least one third fluorine-free polymer (P3), preferably more than one third fluorine-free polymer (P3), is present in the fluorine-free polymer mixture (PG), wherein in particular the third fluorine-free polymer (P3) and / or the plurality of further fluorine-free polymers (P4, P5, ...) comprise LLDPE, MDPE, VLDPE, HDPE and mixtures thereof and / or comprise a proportion of PA and / or PP. - 24 -

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