Method for producing a single- or multi-layer film, single- or multi-layer, extruded, simultaneously biaxially stretched, and heat-set film, and corresponding uses

Abstract

The invention relates to: single- or multi-layer, extruded, simultaneously biaxially stretched, and heat-set films comprising a first polypropylene PP1 having a heat deflection temperature of greater than 75°C, which films can be used, for example, as packaging materials, in particular for food products; a method for producing said films; and the use of said films, preferably for packaging a food product.

Description

[0001] Description

[0002] Process for producing a single- or multi-layer film, single- or multi-layer, extruded, simultaneously biaxially stretched and heat-set film and corresponding uses

[0003] Technical area

[0004] The present application relates to single- or multi-layer, extruded, simultaneously biaxially stretched and heat-set films which can be used, for example, as packaging materials, in particular for foodstuffs, a process for their production and their use, preferably for packaging a foodstuff.

[0005] State of the art and problem

[0006] In the course of improving the reusability and recyclability of plastic-based packaging materials, so-called monomaterials, i.e., pure materials consisting of only one type of plastic, are ideally used. However, the materials currently available often reach their technical limitations in more complex applications with a sophisticated requirement profile, such as food packaging. No single plastic fulfills all the properties required to achieve ideal packaging properties.Typically, each plastic grade only fulfills one or two of the following properties, such as barrier properties against water, water vapor, aroma components, or gases such as oxygen; sufficient rigidity; puncture resistance; delamination resistance; and other mechanical properties; good heat resistance; good sealing properties; attractive optical properties such as low haze; and good printability. This has led to complex multilayer structures with up to 13 layers and a multitude of functional polymers, making recycling of the resulting packaging materials difficult or even impossible.

[0007] Consequently, there is still a lack of solutions for recyclable plastic-based packaging materials, especially for food, which preferably adequately meet all of the following requirements: rigidity, heat resistance, oxygen, gas and aroma barrier, low to no shrinkage.

[0008] Object of the invention

[0009] It is therefore an object of the present invention to provide a process for producing a single- or multi-layer film and a single- or multi-layer, extruded, simultaneously biaxially stretched, and heat-set film producible thereby, which is suitable as a packaging material for food or can be processed into a suitable packaging material and exhibits improved recyclability. Furthermore, it is an object to provide corresponding uses.

[0010] Definitions and measurement methods of the invention

[0011] “Extrusion”: passing at least one type of molten thermoplastic material through a nozzle to form a film (sheet with a small thickness of < 3 mm) when the thermoplastic material re-emerges from the nozzle, wherein the nozzle is preferably a ring or slot die.

[0012] “after extrusion” means in time and / or space immediately after the film exits the nozzle, as far as technically feasible.

[0013] "Before stretching" means the time and / or location before the simultaneous application of machine and transverse direction forces to the film for biaxial stretching. "Time at which stretching begins" means the first time at which the machine direction force and the transverse direction force are applied simultaneously to the film for biaxial stretching.

[0014] “after stretching” means, in time and / or space, immediately after the end of the simultaneous application of forces in the machine and transverse directions to the film for the purpose of biaxial stretching, as far as technically feasible.

[0015] “before heat-setting” means temporally and / or spatially before the film is heated to the temperature at which heat-setting is carried out (third temperature (T3)).

[0016] In the context of the present invention, “relaxing” or “relaxation” means the controlled or regulated shrinkage of the film in MD and / or TD. Controlled shrinkage in MD is achieved by different pull-off speeds, i.e. the film pull-off downstream in the relaxation process runs or pulls at a lower speed than the film pull-off upstream of the process. In TD, controlled shrinkage is achieved by reducing the film width between the two film pull-offs. An example of a relaxation process for extruded and stretched single- or multi-layer films is known to the person skilled in the art from Savic, Z., Savic. I, “Sausage Casings”, VICTUS Lebensmittelindustriebedarf Vertriebsgesellschaft mbH, Vienna, 1st edition, June 2002, Chapter 7, Subchapter 4.2, pages 267 to 270, in particular Figs. 7-13a and 7-13b.

[0017] Density: measured according to DIN EN ISO 1183-1:2019-09

[0018] Film temperature (e.g. during stretching, heat-setting, or relaxation): is the temperature of the film surface, preferably measured non-contact using an IR temperature sensor. Shrinkage (also referred to as heat shrinkage): measured in water at 90°C, preferably within 1 second of immersion, but at least within 10 seconds of immersion. According to the invention, to determine shrinkage (or heat shrinkage), the sample is immersed in water at 90°C for a predetermined period of time, in particular the period specified above, and, after removal, is immediately cooled to room temperature with water. The length of a pre-marked section after this treatment is measured and related to the measured length of the same section of the sample before treatment. The resulting length ratio (“shrunk” to “unshrunk”), expressed as a percentage, defines the shrinkage.Depending on the direction of the length measurement, shrinkage occurs in the longitudinal (MD) and transverse (TD) directions. Total shrinkage is calculated by summing the shrinkage in the longitudinal and transverse directions. Multiple determinations, such as triplicate or quintuple determinations, of the length measurements and the calculation of the corresponding mean values ​​advantageously increase the accuracy of the determination. According to the invention, shrinkage and total shrinkage can be determined, in particular, according to ASTM D2732-14, Edition 2020, April 14, 2020.

[0019] Heat deflection temperature: is the heat deflection temperature (= heat deflection temperature), measured according to ASTM D648-18.

[0020] Strength: Tensile properties (DIN EN ISO 527-1:2019-12, edition 2019-12, and DIN EN ISO 527-2:2012-06, edition 2012-06), flexural properties (3-point method) (ASTM D0790-17, edition 24 July 2017), or flexural properties (4-point method) (ASTM D6272-17el, edition 14 July 2020).

[0021] Stiffness: measured according to DIN EN ISO 527-1:2019-12, edition 2019-12, and DIN EN ISO 527-2:2012-06, edition 2012-06.

[0022] Transparency / Haze / Clarity: Measured according to ASTM D1003-21, Edition 7.

[0023] June 2021. Printability: measured according to DIN 16500-2:2018-09, edition 2018-09, or as polarity in the form of surface tension, expressed in the unit dyn / cm (= 10' 3 N / m).

[0024] Sealability: e.g. SiegeE / welding properties of films / hot-tack test of films: measured according to DIN 55571-2:2021-07

[0025] Seal seam strength: measured according to DIN 55529:2012-09

[0026] Sealing temperature: Sealing temperature = temperature of the material to be sealed during sealing, measured as the temperature of the film, as defined by the manufacturer.

[0027] Sealing / heat sealing: Is the joining of thermoplastic coatings on substrates or of purely thermoplastic materials under the influence of time, (contact) pressure and temperature, whereby the substrates are not melted.

[0028] For the purposes of this determination, the following length definitions apply (each referring to the machine direction or the transverse direction):

[0029] L0 := length of a predetermined section of the film before stretching;

[0030] LI := length of the same section of the film after stretching and before relaxing;

[0031] L2 := Length of the same section of the film after stretching and after relaxation.

[0032] Stretch factor: Stretch factor V = length LI of a predetermined section of the film after stretching and before relaxation divided by the length L0 of the same section of the film before stretching; (V = L1 / L0). The stretch factor V, at which the lengths L0 and LI are determined in the machine direction MD, is also referred to according to the invention as the stretch factor VMD. The stretch factor V, at which the lengths L0 and LI are determined in the transverse direction TD, is also referred to according to the invention as the stretch factor VTD.

[0033] Relaxation factor: Relaxation factor R = 1 - (length L2 of a predetermined portion of the film after stretching and after relaxation divided by the length LI of the same portion of the film after stretching and before relaxation); (R = 1 - (L2 / L1)). The relaxation factor R, which is calculated as above and in which the lengths L2 and L1 are determined in the machine direction MD, is also referred to according to the invention as relaxation factor RMD. The relaxation factor R, which is calculated as above and in which the lengths L2 and LI are determined in the transverse direction TD, is also referred to according to the invention as relaxation factor RTD.

[0034] After completing the two process steps of stretching and heat-setting, here with relaxation, a residual stretch or elongation in the film results. A residual stretch factor (RV) can be determined, which is defined in detail below and is based on the ratio of a length L2 of a section of the film after stretching and after heat-setting including relaxation to a length L0 of the same section before stretching and before relaxation.

[0035] Residual stretch factor: Residual stretch factor RV = length L2 of a predetermined section of the film after stretching and after relaxing divided by the length L0 of the same section of the film before stretching and before relaxing; RV = L2 / L0. The residual stretch factor RV, at which the lengths L2 and L0 are determined in the machine direction MD, is also referred to according to the invention as the residual stretch factor RVMD. The residual stretch factor RV, at which the lengths L2 and L0 are determined in the transverse direction TD, is also referred to according to the invention as the residual stretch factor RVTD.

[0036] "Simultaneously biaxially stretched film": means a film that has been stretched simultaneously in both the machine direction and the transverse direction. "Stable method" or "stable process": a method or process that allows continuous operation (implementation of the method or process) and by means of which a film suitable for the intended application can be produced. "Unstable" does not mean "stable" in the above sense.

[0037] Further definitions that apply within the scope of the present invention, in particular to the subject matter and embodiments of the invention defined in the claims and in the description, are listed below. For the purposes of this invention, the numerical terms "first", "second", "third", etc., such as "second polypropylene" or "second polypropylene PP2", used in the designation of the polymers simply represent a designation of the respective polymer as defined below and do not imply any disclosure of a specific number or sequence of polymers. For example, according to the invention, the statement "the film contains a third polypropylene PP3" does not mean that the film also contains or must contain a first polypropylene PP1 and a second polypropylene PP2.Rather, it simply means that the film contains the third polypropylene PP3 as defined below, regardless of any other components, if any. Therefore, the “third polypropylene” could also have any other designation, such as “polypropylene C.” The same applies to the “first polyethylene,” the “second polyethylene,” the “third polyethylene,” the “first polypropylene” and the “second polypropylene,” the “second polymer,” and the “third polymer” as defined below. The limitations of the polymers mentioned, as defined below, also apply regardless of whether the respective polymer is used with the indefinite or definite article in the description and / or claims.

[0038] Polyethylene (PE): Is a thermoplastic polymer produced by chain polymerization of ethene with the repeating unit [C2H4] (molecular formula) with the structural formula:

[0039] First Polyethylene (PEI) (= High Density Polyethylene (HDPE)): is a polyethylene (PE) with a density greater than 0.940 g / cm 3 , preferably greater than 0.950 g / cm 3 , especially greater than 0.960 g / cm 3 , and less than or equal to 1.010 g / cm 3 , preferably less than 1,000 g / cm 3 , especially less than 0.970 g / cm 3 , measured according to EN ISO 1183-1:2019-09. According to the invention, the first polyethylene (PE1) comprises a polymer type or a mixture of several polymer types (e.g., with different chain lengths) of the polyethylene type. If the first polyethylene (PE1) consists of a mixture of several polymer types of the polyethylene type, the density ranges specified above apply to the mixture after its homogenization.

[0040] Second polyethylene (PE2): is a polyethylene (PE) with a density of less than 0.940 g / cm 3 , preferably less than 0.920 g / cm 3 , and greater than 0.870 g / cm 3, measured according to DIN EN ISO 1183-1:2019-09, preferably a sealable polyethylene or a polyethylene suitable for forming a sealable layer. According to the invention, the second polyethylene (PE2) comprises a polymer type or a mixture of several polymer types (e.g., different chain lengths) of the polyethylene type. If the second polyethylene (PE2) consists of a mixture of several polymer types of the polyethylene type, the density ranges specified above apply to the mixture after its homogenization. The second polyethylene (PE2) is not identical to the first polyethylene (PE1).

[0041] Third polyethylene (PE3): is a polyethylene (PE) with a density that is lower than the density of the first polyethylene (PE1) and higher than the density of the second polyethylene (PE2), each measured according to DIN EN ISO 1183-1:2019-09. According to the invention, the third polyethylene (PE3) comprises a polymer type or a mixture of several polymer types (e.g. different chain lengths) of the polyethylene type. If the third polyethylene (PE3) consists of a mixture of several polymer types of the polyethylene type, the density ranges specified above apply to the mixture after its homogenization. The third polyethylene (PE3) is not identical to the second polyethylene (PE2) and not identical to the first polyethylene (PE1).

[0042] Polypropylene (PP): is a thermoplastic polymer produced by chain polymerization of propene with the repeating unit [CeHs] (molecular formula) with the structural formula:

[0043] First polypropylene (PPI): is a polypropylene (PP) with a heat deflection temperature (= heat distortion temperature) of greater than 75 °C, preferably greater than 85 °C, in particular greater than 95 °C, measured according to ASTM D648-18; and preferably with a density of greater than 0.895 g / cm 3 and less than 0.920 g / cm 3 , preferably greater than 0.899 g / cm 3 , and less than 0.910 g / cm 3 , measured according to DIN EN ISO 1183-1:2019-09. According to the invention, the first polypropylene (PPI) comprises one polymer type or a mixture of several polymer types (e.g., different chain lengths) of the polypropylene type. If the first polypropylene (PPI) consists of a mixture of several polymer types of the polypropylene type, the above-specified ranges for the heat distortion temperature and preferably also for the density apply to the mixture after homogenization.

[0044] Second polypropylene (PP2): Is a polypropylene (PP) with a heat deflection temperature of less than 75°C, preferably less than 65°C, in particular less than 55°C, measured according to ASTM D648-18, preferably a sealable polypropylene or a polypropylene suitable for forming a sealable layer. According to the invention, the second polypropylene (PP2) comprises one polymer type or a mixture of several polymer types (e.g., different chain lengths) of the polypropylene type. If the second polypropylene (PP2) consists of a mixture of several polymer types of the polypropylene type, the above-specified ranges for the heat deflection temperature apply to the mixture after its homogenization.

[0045] Third polypropylene (PP3): is a polypropylene (PP) with a heat deflection temperature that is lower than the heat deflection temperature of the first polypropylene (PP1) and higher than the heat deflection temperature of the second polypropylene (PP2), each measured according to ASTM D648-18. According to the invention, the third polypropylene (PP3) comprises a polymer type or a mixture of several polymer types (e.g., different chain lengths) of the polypropylene type. If the third polypropylene (PP3) consists of a mixture of several polymer types of the polypropylene type, the above-specified heat deflection temperature ranges apply to the mixture after homogenization.

[0046] Second polymer (PM2): Is a polymer (preferably a polyolefin) that is preferably sealable, especially heat-sealable, and preferably a polyethylene (PE), a polypropylene (PP), an ethylene-vinyl acetate copolymer (EVA), an ionomer (IO), an ethylene-methyl methacrylate copolymer (EMMA), or an ethylene-methacrylic acid copolymer (EMA). If the second polymer (PM2) is a polyolefin, which is preferred, it is referred to according to the invention as the second polyolefin (PO2).

[0047] Third polymer (PM3): Is a polymer (preferably a polyolefin) that is preferably not sealable, even more preferably not heat-sealable, in particular has a sealing temperature higher than the sealing temperature of the second polymer (PM2) (preferably the second polyolefin (PO2)), and preferably contains or consists of a polyethylene (PE) and / or a polypropylene (PP) or any mixture thereof. If the third polymer (PM3) is a polyolefin, which is preferred, it is referred to according to the invention as the third polyolefin (PO3). Polyethylene terephthalate (PET): Polyethylene terephthalate, which can be obtained by polycondensation of terephthalic acid (1,4-benzenedicarboxylic acid) and ethylene glycol (1,2-dihydroxyethane).

[0048] Polyvinylidene chloride (PVDC): is a thermoplastic formed from vinylidene dichloride (1,1-Diehl or ethylene), similar to PVC. PVDC decomposes near its melting point of approximately 200 °C.

[0049] Polyamide (PA): is a material selected from a group consisting of PA made from 8-caprolactam or poly(s-caprolactam) (PA6), PA made from hexamethylenediamine and adipic acid or polyhexamethyleneadipinamide (PA6.6), PA made from s-caprolactam and hexamethylenediamine / adipic acid (PA6.66), PA made from hexamethylenediamine and dodecanedioic acid or polyhexamethylenedodecanamide (PA6.12), PA made from 11-aminoundecanoic acid or polyundecanamide (PA11), PA made from 12-laurolactam or poly(co-laurolactam) (PA12), or a mixture of these PAs or a mixture of these PAs with amorphous PA or with other polymers. The general notation PAx.y is synonymous with PAx / y or PAxy.

[0050] Ethylene-vinyl alcohol copolymer (EVOH): is a fully saponified copolymer of ethylene and vinyl acetate with the repeating units [C2H4O] and [C2H4] (molecular formula) and with the structural formula:

[0051] Polyvinyl alcohol (PVOH): is a polymer that can be produced by complete saponification (hydrolysis) of polyvinyl acetate (PVAC), with the repeating unit [C2H4O] (molecular formula) and with the structural formula:

[0052] Adhesion promoters (AD): can be provided as intermediate layers in the film according to the invention and represent adhesive layers that ensure good bonding of the individual layers to one another. ADhesion promoters can be based on a base material selected from a group consisting of PE, PP, ethylene-vinyl acetate copolymer (EVA), ethylene-methacrylic acid copolymer (EMA), ethylene-methyl methacrylate copolymer (EMMA), ethylene-acrylic acid copolymers (EAA), and an ionomer, or a mixture thereof. According to the invention, ethylene-vinyl acetate copolymer (EVA), ethylene-methacrylic acid copolymer (EMA), or ethylene-methyl methacrylate copolymer are particularly suitable as adhesion promoters.

[0053] (EMMA), each with a purity of > 99%, preferably > 99.9%. Unless defined above, the person skilled in the art understands the abbreviations used to be the usual definitions used in the technical field of the invention.

[0054] For the purposes of this invention, the designation of a material as a "layer component" means that a layer of the film according to the invention comprises this material at least partially. In this context, the designation "layer component" for the purposes of this invention can include, in particular, that the layer consists entirely or exclusively of this material.

[0055] For the purposes of this invention, "inner layer" or "inner layer" means a layer of the film which, when the film according to the invention is used as intended as a packaging material or as a part thereof, is a surface of the film facing or coming into contact with a product to be packaged. The inner layer is therefore the interface between the film and the product to be packaged when the film is used as a packaging material, or it represents the interface between the film and another layer or layer stack if another layer or layer stack is to be laminated onto the film according to the invention during further processing.

[0056] For the purposes of this invention, "outer layer" means a layer of the film that forms a surface of the film facing outward and, when the film according to the invention is used as intended as a packaging material or as a part thereof, does not come into direct contact with the goods to be packaged. The outer layer is therefore the interface between the film and the external environment. The outer layer and the inner layer are the two essentially opposing layers that seal off the film from the outside.

[0057] For the purposes of this invention, “middle” or “intermediate” layer means a layer of the film which is arranged between the outer layer and the inner layer of the film.

[0058] Disclosure of the subject matter of the invention

[0059] All mass fractions (in %), temperatures (in °C) and durations (in seconds) stated in the present application are stated and determined to one decimal place (e.g. “50%” means “50.0%”; “120 °C” means “120.0 °C”; “2 seconds means 2.0 seconds”; “1.5 seconds” means “1.5 seconds”), unless stated more precisely (e.g. “0.05 seconds” means “0.05 seconds”).

[0060] The above-mentioned object is achieved by the subject matter defined in the claims and / or disclosed below.

[0061] The process according to the invention can be carried out or produced using a variety of process techniques known to those skilled in the art. These include, in particular, the so-called triple-bubble process, the double-bubble process with downstream heat-setting, and the tenter-frame process with simultaneous, biaxial stretching. During heat-setting, the films are passed through an oven in tubular form and treated with heat, in most cases, as with the tenter-frame process, using hot air. Alternatively, the triple-bubble process also uses heat-setting of the film with infrared or hot steam to reduce the shrinkage induced during stretching. Alternatively, in the double-bubble process, the downstream heat-setting can be carried out using tempering rollers or a horizontal hot-air oven.Accordingly, the film according to the invention can be produced using these process technologies or other suitable process technologies known to the person skilled in the art. Such process technologies are known to the person skilled in the art from the relevant literature, for example, the work Savic, Z., Savic, I.: "Sausage Casings," published by VICTUS Lebensmittelindustriebedarf Vertriebsgesellschaft mbH, Vienna, 1st edition, June 2002, Chapter 7, in particular Subchapter 4.2, pages 244 to 301, or from his or her practical experience.

[0062] Specifically, the process according to the invention and the film according to the invention can preferably be carried out or produced using the double-bubble process and, in particular, the triple-bubble process, for which the applicant provides suitable equipment. The film can be coextruded from the respective resin melts, for example, using a die-blowing head of the applicant designed for the production of single-layer or composite films with three or more layers, preferably with thermal separation of the individual layers, cooled using a water cooling system of the applicant, reheated, stretched simultaneously biaxially (in the machine direction (MD) and in the transverse direction (TD)) using an enclosed compressed air bubble, and finally, in a further step, thermally set and optionally relaxed in a defined temperature regime. The relaxation can take place in both directions, i.e.both in the machine direction (MD) and in the transverse direction (TD). Essential to the process according to the invention is that the relaxation, if used, does not occur equally in both directions (MD and TD), but rather the relaxation factor in the transverse direction (TD) is always greater than the relaxation factor in the machine direction (MD). Furthermore, relaxation in only one direction, i.e., only in TD, is also possible. The choice of the relaxation direction can always be made independently. The quantitative expression of the relaxation is expressed in the context of the present invention by the so-called relaxation factor, as defined in more detail below.

[0063] Another possibility for producing the film according to the invention is to stretch a (co-)extruded flat film according to the tenter frame process known to the person skilled in the art.

[0064] The film of the present invention can be advantageously produced on a device or system of the applicant for producing tubular food films for food packaging, such as shrink films or shrink bags, using the nozzle blow molding process, if the device disclosed in patent DE 199 16 428 B4 of the same applicant is additionally used for rapidly cooling thin thermoplastic tubes after their extrusion. A corresponding further development according to patent DE 100 48 178 B4 can also be considered for this purpose.

[0065] The tubular film produced from the plastic melt in the die head is subjected to intensive cooling, which preserves the amorphous structure of the thermoplastics from the plastic melt. The tubular film, vertically extruded from the plastic melt in the die head, initially migrates into the cooling device for cooling without contact with the wall, as described in detail in the documents DE 199 16 428 B4 and DE 100 48 178 B4. For details of the procedures, design, and operation of this cooling device, also referred to as a calibration device, reference is made in full to the contents of the documents DE 199 16 428 B4 and DE 100 48 178 B4 to avoid repetition.

[0066] The tubular film then passes through supports in the cooling device, against which the film rests due to a differential pressure between the interior of the tubular film and the coolant. A liquid film is maintained between the film and the supports, preventing the tubular film from sticking. The diameter of the supports influences the diameter of the tubular film, which is why this cooling device from the same applicant is also referred to as a calibration device.

[0067] The process according to the invention makes it possible for the first time to produce a single- or multi-layer film based on polypropylene (PP) that meets the high requirements of a food packaging material. According to the invention, it is essential that the film is based on PP. The film according to the invention contains the polypropylene (hereinafter referred to as "first polypropylene PPI" and composed as defined above as "first polypropylene PPI"). In the film according to the invention, the mass fraction of the first polypropylene PPI is greater than 30% to 100%, based on the total mass of the film.

[0068] The film produced exhibits little to no shrinkage (0 to 3%, preferably 0 to 2%, in particular 0 to 1% shrinkage in both the machine direction (MD) and the transverse direction (TD), measured at 90°C according to ASTM D2732-14, as described above). The inventor has surprisingly discovered that the manufacturing process based on experience can only be operated stably and the resulting film has satisfactory properties, particularly with regard to its mechanical properties, if, during simultaneous biaxial stretching, the stretch in the machine direction is greater than the stretch in the transverse direction. This is a unique feature of the process according to the invention, since, during simultaneous biaxial stretching, especially in the double-bubble and triple-bubble processes, the stretch in the machine direction is conventionally always set smaller than the stretch in the transverse direction.

[0069] Furthermore, the inventor has surprisingly discovered that, contrary to any expert's expectations, the following relationship applies to the process according to the invention: the greater the stretching of the film according to the invention at the stretching temperature provided according to the invention, the smaller the shrinkage and the smaller the haze (the greater the clarity) of the film, and the stiffer the film. Therefore, with the process according to the invention, it is possible to achieve low shrinkage of the films or even eliminate it completely by selecting high stretching factors in both directions. However, the stretching factor must not exceed 8.0, preferably 7.5, in the machine direction and 7.0, preferably 6.5, in the transverse direction, since otherwise the stability of the stretching process and thus of the film manufacturing process can no longer be ensured.

[0070] A further finding of the inventor is that the longer the heat-setting (residence time during heat-setting = duration of setting at the setting temperature specified according to the invention) of the film in the process according to the invention, the more transparent the resulting film was. It was also observed that the higher the temperature during heat-setting, the more transparent or less opaque the resulting film was.

[0071] Furthermore, during the development of the process according to the invention, it was surprisingly discovered that the higher the temperature during heat setting, the clearer the resulting film and the higher the stiffness and mechanical stability of the resulting film. And: the smaller the relaxation during heat setting, the clearer the resulting film and the higher the stiffness of the resulting film. This is presumably due to the fact that the greater the stretching, the more crystalline and thus more transparent the resulting film. This is also accompanied by lower film shrinkage. If relaxation is completely omitted in the process according to the invention, the resulting film is even clearer and more transparent.

[0072] Overall, the inventor of the present invention has recognized that an increase in the stretch factors during stretching, combined with a stretch factor that is greater in the machine direction than in the transverse direction, and a higher temperature and lower relaxation factors (or no relaxation) during heat setting leads to high transparency or clarity, high stiffness, and low shrinkage of the resulting film according to the invention. He suspects that the reason for this surprising achievement of the improved properties is a higher crystallinity of the main component of the films according to the invention, namely the first polypropylene PPI, compared to conventional processes or films. In the film according to the invention, the residual stretch factor (RVTD) in the transverse direction (TD) is preferably greater than 2.8 and less than 4.4, more preferably greater than 3.6 and less than 4.4, in particular greater than 4.1 and less than 4.4.Furthermore, the residual stretch factor (RVMD) of the film in the machine direction (MD) is preferably greater than 3.6 and less than 5.4, more preferably greater than 4.1 and less than 5.4, in particular greater than 5.0 and less than 5.4. The above ranges for the RVTD and the RVMD are particularly suitable when the inventive film contains a first polypropylene PPI with a heat distortion temperature of greater than 85 °C. In the inventive film which contains a first polypropylene PPI with a heat distortion temperature of greater than 75 °C and less than or equal to 85 °C, the residual stretch factor (RVTD) of the film in the transverse direction (TD) is preferably greater than 4.0 and less than 6.0, more preferably greater than 4.5 and less than 6.0, in particular greater than 5.0 and less than 6.0.Furthermore, the residual stretch factor (RVMD) of the film comprising a first polypropylene PPI having a heat distortion temperature of greater than 75°C and less than or equal to 85°C in the machine direction (MD) is preferably greater than 5.0 and less than 7.0, more preferably greater than 5.5 and less than 7.0, in particular greater than 6.0 and less than 7.0. In any case, however, in the film according to the invention, the residual stretch factor (RVMD) of the film in the machine direction (MD) is preferably greater than the residual stretch factor (RVTD) in the transverse direction (TD).

[0073] Furthermore, the inventor has surprisingly discovered the following relationships in connection with the process according to the invention and the film according to the invention:

[0074] The higher the respective stretch factor or degree of stretching during simultaneous biaxial stretching, the lower the shrinkage of the resulting film. • The higher the respective stretch factor or degree of stretching during simultaneous biaxial stretching, the lower the haze and the higher the clarity or transparency of the resulting film.

[0075] • The greater the respective stretching factor or degree of stretching in the simultaneous biaxial stretching, the greater the stiffness of the resulting film.

[0076] • The higher the temperature during heat setting of the film, the higher the clarity or transparency and the stability of the resulting film.

[0077] • The longer the heat-setting time of the film, the higher the clarity or transparency and the stability of the resulting film.

[0078] • The smaller the relaxation factor during heat setting, the higher the clarity or transparency of the resulting film.

[0079] • The smaller the relaxation factor during heat setting, the higher the stiffness of the resulting film.

[0080] The process according to the invention can completely dispense with a step of lamination or extrusion coating of the film or of individual layers or layer packages. On the one hand, this saves an additional process step, which simplifies the process according to the invention in terms of its implementation and the equipment required. On the other hand, the resulting film is mechanically more stable, since the lamination interfaces of a laminated film always represent a mechanical weak point and increase the risk of delamination of one or more layers of the film. Since the film according to the invention is extruded or coextruded in a single step, the resulting film can be up to 50% thinner than films produced by separate extrusion of layers and subsequent lamination of the separately extruded layers, which have thicknesses of, for example, 40 to 60 μm.This is also due to the fact that the process according to the invention allows the use of PP (= PPI) as a layer component with a comparatively high density for the production of the inventive film. In any case, the up to 50% thinner inventive film, with a thickness of, for example, 20 to 30 μm, results in corresponding material savings and thus also energy savings compared to a comparable film produced by lamination with a similar layer structure.

[0081] However, it is not excluded that the film according to the invention is laminated in a separate working step with one or more other layers to form a ready-to-use film.

[0082] A further essential aspect of the process according to the invention is that the film is cooled very quickly to a temperature of 20°C or below after extrusion. As a result, thermal energy is withdrawn from the film practically immediately after its formation by extrusion or coextrusion, thus preventing crystallization of the polymer molecules or at least avoiding further crystallization. Accordingly, it is also important to heat the film to the stretching temperature within a few seconds before hiding and to preferably carry out stretching immediately after reaching the stretching temperature, i.e., if possible without any time delay. Furthermore, it is advantageous in this context if the film is cooled as quickly as possible to a temperature below 50°C after hiding.

[0083] By limiting the time the film is exposed to high temperatures, for example before or during stretching, as provided for in the invention, crystallization of the PPI is prevented as much as possible. Technically, this is ensured by the extremely short heating and cooling times and the minimization of phases during which the film is exposed to high temperatures, for example the phase from reaching the stretching temperature to the start of stretching. Thus, before stretching, the film according to the invention must be heated from the temperature to which it was cooled after extrusion to the stretching temperature within a period of 1 to 18 seconds, preferably 1.5 to 12 seconds, in particular 2 to 9 seconds. In other words, at the usual running speeds of the film, the heating must take place over a distance of between approximately 5 and 50 cm.Such heating is technically impossible within a period of less than 1 second given current technology. On the other hand, if the heating takes too long, especially longer than 18 seconds, there is a risk that crystallization of the polyolefin material will begin or progress too far. The goal of exposing the film to a high temperature for as short a time as possible, and thus to thermal stress with the risk of further crystallization, is also served by the measure provided for in the process according to the invention of cooling the film immediately after extrusion.

[0084] In the process according to the invention, it is fundamentally important that the film does not crystallize, or only crystallizes to a limited extent, before stretching. However, if the film crystallizes after stretching, this is generally unproblematic or even desirable, as it is advantageous. At most, there is a risk that the bubble enclosed by the film during stretching could cause the film to burst, thus leading to an unstable process (this applies particularly to the triple-bubble and double-bubble processes).

[0085] To prevent crystallization of the polyolefin material of the film, the process according to the invention can therefore also provide for the film to be cooled very quickly to a temperature below 50°C after stretching and before heat-setting. Depending on the process technology used, this cooling step can be mandatory, as in the triple-bubble or double-bubble process, or optional, as in the tenter-frame process. The inventor has thus determined that, for example, when producing the film according to the invention using the triple-bubble process, cooling the film after stretching to below 50°C, preferably below 40°C, and even better below 30°C, is essential, since otherwise the production process is unstable.

[0086] Furthermore, compliance with the temperature ranges provided for heat-setting according to the invention is essential. The inventor has determined that during heat-setting of the film, at a temperature measured on the surface of the film below 60°C, or even below 100°C depending on the polymer material used, the film becomes too cloudy and thus unusable for most intended applications, especially as a food film. If, however, the temperature of the film during heat-setting exceeds 200°C, the film is thermally damaged and may, for example, burst. In contrast, the temperature windows provided according to the invention, in particular the windows greater than 60°C and less than 200°C, preferably greater than 80°C and less than 180°C, and especially greater than 100°C and less than 160°C, produce very transparent films with good stability.These temperature windows apply in particular when the first polypropylene PPI contained in the film according to the invention has a heat distortion temperature of greater than 95°C. The same temperature windows preferably also apply when the film according to the invention contains the second polyethylene PE2 in the inner layer or the inner layer consists of the second polyethylene PE2.

[0087] If, on the other hand, the first polypropylene PPI contained in the film according to the invention has a heat distortion temperature of greater than 85°C and less than or equal to 95°C, the temperature of the film, measured at the surface of the film, during heat setting is preferably greater than 80°C and less than 180°C. If, on the other hand, the first polypropylene PPI contained in the film according to the invention has a heat distortion temperature of greater than 75°C and less than or equal to 85°C, the temperature of the film, measured at the surface of the film, during heat setting is preferably greater than 60°C and less than 160°C.

[0088] The particular advantage of the film according to the invention is that it is recyclable. The film according to the invention is preferably sheet-like or tubular.

[0089] In the film according to the invention, EVOH can serve as a layer component for a good barrier against oxygen and other gases. In addition, or instead, PVOH can also be provided as a layer component in the film according to the invention within the scope of the present invention. According to the inventor's knowledge, PVOH is more thermally sensitive and can therefore only be processed up to a temperature of approximately 190°C and is also more expensive. However, PVOH offers an even better gas barrier than EVOH. Furthermore, PVOH is easy to process together with polyethylene or polypropylene and can therefore also be combined very well with the PE and PP materials processed in this application. According to the invention, it is preferred that the inner layer of the film according to the invention is a polyolefinic sealing layer, which preferably contains or consists of a polypropylene PP, in particular the second polypropylene PP2 or the third polypropylene PP3.

[0090] According to the invention, it is preferred that one or more intermediate layers of the film according to the invention contain or consist of a polyolefinic polymer, preferably a polypropylene PP, in particular the third polypropylene PP3.

[0091] Alternatively, it can be provided according to the invention that the film according to the invention has an outer layer which consists of the first polypropylene PPI, and an inner layer which consists of the second polyethylene PE2 or of the third polyethylene PE3 instead of polypropylene (e.g. instead of the second polypropylene PP2). This constellation improves the sealability of the film compared to a film consisting only of PP, for example. This is because the second polyethylene PE2 in the inner layer has a lower melting temperature than PP (55 to 75 °C for PE2 vs. e.g. > 75 to 105 °C for PP2) and thus the meltability of the entire film is improved while maintaining the good heat resistance of the film, which is caused or supported by the PPI outer layer.Furthermore, this configuration increases the melting temperature difference between the outer and inner layers compared to a film in which the outer and inner layers are each made of polypropylene. This improves the processability of the entire film at higher temperatures, allowing for higher cycle times in the film production process.

[0092] Preferred embodiments of the film according to the invention

[0093] Below, some exemplary embodiments of the film according to the invention are listed schematically. These embodiments are suitable either for immediate use ("ready to use" or RTU) or for lamination of additional layers. If only one material is specified for a layer, this means that the layer consists of the specified material. The respective layer structure is shown as follows (layer sequence from left to right in the row means from outer layer to inner layer):

[0094] Single-layer film made of: PPI

[0095] Single-layer film made of: > 65 mass% PPI + < 35 mass% PP2 or PP3; e.g.

[0096] 75 mass% PPI + 25 mass% PP2; or 70 mass% PPI + 20 mass%

[0097] PP2 + 10 mass% PP3

[0098] 2-layer film: PPI / / PPI

[0099] 2-layer film: PPI / / PP2

[0100] 2-layer film: PP3 / / PPI

[0101] 3-layer film: PPI / / PPI / / PPI

[0102] 3-layer film: PP2 / / PPI / / PP2

[0103] 3-layer film: PP3 / / PPI / / PPI

[0104] 3-layer film: PP3 / / PPI / / PP3

[0105] 3-layer film: PP3 / / PPI / / PP2

[0106] 3-layer film: PPI / / HV / / PE2

[0107] 4-layer film: PP2 / / PPI / / PPI / / PP2

[0108] 4-layer film: PP3 / / PPI / / PPI / / PP2

[0109] 4-layer film: PP3 / / PPI / / PP3 / / PP2

[0110] 4-layer film: PP3 / / PPI / / PPI / / PP3

[0111] 4-layer film: PPI / / PP3 / / HV / / PE2

[0112] 4-layer film: PP3 / / PPI / / HV / / PE2

[0113] 4-layer film: PP2 / / PPI / / HV / / PE2

[0114] 5-layer film: PP3 / / PPI / / PPI / / PPI / / PP2 5-layer film: PP3 / / PPI / / PPI / / PPI / / PP3

[0115] 5-layer film: PP3 / / PPI / / PPI / / PP3 / / PP2

[0116] 5-layer film: PPI / / HV / / EVOH / / HV / / PE2

[0117] 5-layer film: PPI / / HV / / EVOH / / HV / / PPI

[0118] 5-layer film: PPI / / HV / / EVOH / / HV / / PP2

[0119] 5-layer film: PPI / / HV / / EVOH / / HV / / PP3

[0120] 5-layer film: PPI / / HV / / PVOH / / HV / / PE2

[0121] 5-layer film: PPI / / HV / / PVOH / / HV / / PPI

[0122] 5-layer film: PPI / / HV / / PVOH / / HV / / PP2

[0123] 5-layer film: PPI / / HV / / PVOH / / HV / / PP3

[0124] 6-layer film: PPI / / HV / / EVOH / / HV / / PPI / / PP2

[0125] 6-layer film: PPI / / HV / / EVOH / / HV / / PP3 / / PP2

[0126] 6-layer film: PPI / / HV / / EVOH / / HV / / PP2 / / PE2

[0127] 6-layer film: PPI / / HV / / PVOH / / HV / / PPI / / PP2

[0128] 6-layer film: PPI / / HV / / PVOH / / HV / / PP3 / / PP2

[0129] 6-layer foil: PPI / / HV / / PVOH / / HV / / PP2 / / PE2

[0130] 6-layer film: PPI / / PP3 / / HV / / EVOH / / HV / / PE2

[0131] 6-layer film: PPI / / PP3 / / HV / / PVOH / / HV / / PE2

[0132] 7-layer film: PP2 / / PPI / / HV / / EVOH / / HV / / PPI / / PP2

[0133] 7-layer film: PP3 / / PPI / / HV / / EVOH / / HV / / PPI / / PP2

[0134] 7-layer film: PP3 / / PPI / / HV / / EVOH / / HV / / PPI / / PP3

[0135] 7-layer film: PPI / / HV / / EVOH / / HV / / PPI / / HV / / PE2

[0136] 7-layer film: PP2 / / PPI / / HV / / PVOH / / HV / / PPI / / PP2

[0137] 7-layer film: PP3 / / PPI / / HV / / PVOH / / HV / / PPI / / PP2

[0138] 7-layer film: PP3 / / PPI / / HV / / PVOH / / HV / / PPI / / PP3

[0139] 7-layer film: PPI / / HV / / PVOH / / HV / / PPI / / HV / / PE2

[0140] 8-layer film: PP3 / / PPI / / HV / / EVOH / / HV / / PPI / / PP3 / / PP2

[0141] 8-layer film: PP3 / / PPI / / HV / / PVOH / / HV / / PPI / / PP3 / / PP2 • 8-layer film: PP 1 / / PP3 / / HV / / EVOH / / HV / / PP3 / / HV / / PE2

[0142] • 8-layer film: PP 1 / / PP3 / / HV / / EVOH / / HV / / PP3 / / PP2 / / PE2

[0143] • 8-layer film: PP 1 / / PP3 / / HV / / PVOH / / HV / / PP3 / / HV / / PE2

[0144] • 8-layer film: PP 1 / / PP3 / / HV / / PVOH / / HV / / PP3 / / PP2 / / PE2

[0145] • 9-layer film: PP2 / / PP3 / / PP 1 / / HV / / EVOH / / HV / / PP 1 / / PP3 / / PP2

[0146] • 9-layer film: PP2 / / PP3 / / PP 1 / / HV / / PVOH / / HV / / PP 1 / / PP3 / / PP2

[0147] • 9-layer film: PP 1 / / PP3 / / HV / / EVOH / / HV / / PP3 / / PP 1 / / HV / / PE2

[0148] • 9-layer film: PP 1 / / PP3 / / HV / / EVOH / / HV / / PP3 / / PP 1 / / PP2 / / PE2

[0149] • 9-layer film: PP 1 / / PP3 / / HV / / PVOH / / HV / / PP3 / / PP 1 / / HV / / PE2

[0150] • 9-layer film: PP 1 / / PP3 / / HV / / PVOH / / HV / / PP3 / / PP 1 / / PP2 / / PE2

[0151] Explanations and abbreviations for the preferred embodiments explained above:

[0152] • “ / / ” symbolises the layer boundary; for example “A / / B / / C” means: a multi-layer film with a total of three layers, of which the outer layer consists of component A, the middle layer (= intermediate layer) consists of component B, and the inner layer consists of component C;

[0153] • identical reference numerals correspond to identical polymer components as in the claims;

[0154] • all embodiments shown can be produced by means of the method according to the invention using triple bubble technology;

[0155] • all illustrated embodiments of the film according to the invention have at least the limitations of at least one of the product claims; in particular, all embodiments are extruded, simultaneously biaxially stretched and thermoset films;

[0156] • PE1 = first polyethylene (PEI) (= HDPE) as defined above;

[0157] • PE2 = second polyethylene (PE2) as defined above, sealable;

[0158] • PE3 = third polyethylene (PE3) as defined above;

[0159] • PPI = first polypropylene (PPI) as defined above; • PP2 = second polypropylene (PP2) as defined above, sealable;

[0160] • PP3 = third polypropylene (PP3) as defined above;

[0161] • PM2 = second polymer (PM2) as defined above, preferably second

[0162] Polyolefin (PO2) as defined above, sealable;

[0163] • PM3 = third polymer (PM3) as defined above, preferably third

[0164] Polyolefin (PO3) as defined above;

[0165] • EVOH = ethylene-vinyl alcohol copolymer (EVOH) as defined above;

[0166] • PVOH = polyvinyl alcohol (PVOH) as defined above; and

[0167] • HV = Adhesion promoter (HV) as defined above.

[0168] Preferred embodiments of the method according to the invention are listed below:

[0169] Embodiment 1 (VI)

[0170] (VI) A process for producing a single- or multi-layer film, the process comprising at least the following steps: a step of extruding a layer or co-extruding several layers to obtain an extruded film; a step of simultaneously biaxially stretching the extruded film; and a step of heat-setting the stretched film; wherein the film contains a first polypropylene (PPI) in a mass fraction of greater than 50%, preferably greater than 65%, preferably greater than 80%, particularly preferably greater than 90%, based on the total mass of the film; wherein the first polypropylene (PPI) has a heat deflection temperature of greater than 85°C, particularly preferably greater than 95°C, measured according to ASTM D648-18; wherein the film does not contain any of the following polymers selected from the group consisting of polyethylene terephthalate (PET), polyvinylidene chloride (PVDC), and polyamide (PA):wherein the film is cooled after extrusion within a period of 0.05 to 0.5 seconds, particularly preferably 0.07 to 0.3 seconds, to a first temperature (TI) of below 20°C, particularly preferably below 15°C; wherein a stretch factor (VMD) in the machine direction or longitudinal direction (MD) is greater than 5.0, preferably greater than 6.0, particularly preferably greater than 7.0, and less than 8.0; wherein a stretch factor (VTD) in the transverse direction or transverse direction (TD) is greater than 4.0, preferably greater than 5.0, particularly preferably greater than 6.0, and less than 7.0; wherein the stretch factor (VMD) in the machine direction (MD) is greater than the stretch factor (VTD) in the transverse direction (TD); wherein the film has a second temperature (T2) of greater than 130 °C and less than 170 °C, particularly preferably greater than 140 °C and less than 160 °C, during stretching;wherein the film is heated from the first temperature (T1) to the second temperature (T2) within a period of 1.0 to 12 seconds, particularly preferably 2 to 9 seconds, before stretching; wherein a time period (At) (= t2 - t1) between a first point in time (t1) at which the film reaches the second temperature (T2) and a second point in time (t2) at which stretching of the film begins is 0.1 to 3 seconds, particularly preferably 0.3 to 1.5 seconds; wherein the film has a third temperature (T3) of greater than 80°C and less than 180°C, particularly preferably greater than 100°C and less than 160°C, during heat setting; and wherein a residence time during heat setting (= duration of heat setting of the film), during which the film has the third temperature (T3), is greater than 1 second and less than 45 seconds, particularly preferably greater than 3 seconds and less than 30 seconds. Embodiment 2 (V2);

[0171] (V2) Process according to (VI), wherein the process further provides for relaxing the film during heat-setting of the film; wherein a relaxation factor (RMD) in the machine direction (MD) is greater than 0.00 and less than 0.10, preferably greater than 0.00 and less than 0.05, particularly preferably greater than 0.00 and less than 0.03; wherein a relaxation factor (RTD) in the transverse direction (TD) is greater than 0.00 and less than 0.20, preferably greater than 0.00 and less than 0.10, particularly preferably greater than 0.00 and less than 0.05; and wherein the relaxation factor (RTD) in the transverse direction (TD) is greater than the relaxation factor (RMD) in the machine direction (MD); wherein the film has the third temperature (T3) during the relaxation; and wherein a duration of relaxation of the film, during which the film has the third temperature (T3), is preferably greater than 5 seconds, particularly preferably greater than 10 seconds, and less than 30 seconds.

[0172] Embodiment 3 (V3)

[0173] (V3) Process according to (VI) or (V2), wherein the process further comprises cooling the film after stretching and before heat-setting; wherein, after stretching, the film is cooled to a fourth temperature (T4) of below 40°C, particularly preferably below 30°C, within a period of 0.01 to 0.5 seconds, particularly preferably 0.07 to 0.3 seconds;

[0174] Embodiment 4 (V4)

[0175] (V4) Process according to (VI), (V2) or (V3), wherein the film further contains a second polyethylene (PE2); and wherein the second polyethylene (PE2) has a density of less than 0.940 g / cm 3 , preferably less than 0.920 g / cm 3 , and greater than 0.870 g / cm 3 , measured according to DIN EN ISO 1183-1:2019-09.

[0176] Embodiment 5 (V5)

[0177] (V5) Process according to (VI), (V2), (V3) or (V4), wherein the film is multilayered; wherein the film contains ethylene-vinyl alcohol copolymer (EVOH) in a mass fraction of less than 5%, based on the total mass of the film; wherein the film has at least one layer consisting of ethylene-vinyl alcohol copolymer (EVOH).

[0178] Embodiment 6 (V6)

[0179] (V6) Process according to (VI), (V2), (V3), (V4) or (V5), wherein the film is multilayered; wherein the film contains polyvinyl alcohol (PVOH) in a mass fraction of less than 5%, based on the total mass of the film; wherein the film has at least one layer consisting of polyvinyl alcohol (PVOH).

[0180] Embodiment 7 (V7)

[0181] (V7) Process according to (VI), (V2), (V3), (V4), (V5) or (V6), wherein the film is multilayered; wherein the film has an outer layer which consists of a second polyethylene (PE2) and / or a second polypropylene (PP2); wherein the second polyethylene (PE2) has a density of less than 0.940 g / cm 3 and greater than 0.870 g / cm 3 , measured according to DIN EN ISO 1183-1:2019-09; wherein the second polypropylene (PP2) has a heat distortion temperature of less than 65 °C, particularly preferably less than 55 °C, measured according to ASTM D648-18; and wherein the outer layer contains no ethylene-vinyl alcohol copolymer (EVOH) and no polyvinyl alcohol (PVOH).

[0182] Embodiment 8 (V8)

[0183] (V8) Process according to (VI), (V2), (V3), (V4), (V5), (V6) or (V7), wherein the film is multilayered; wherein the film has an inner layer which consists of a second polyethylene (PE2) and / or a second polypropylene (PP2); wherein the second polyethylene (PE2) has a density of less than 0.940 g / cm 3 and greater than 0.870 g / cm 3 , measured according to DIN EN ISO 1183-1:2019-09; wherein the second polypropylene (PP2) has a heat distortion temperature of less than 65 °C, particularly preferably less than 55 °C, measured according to ASTM D648-18; and wherein the inner layer contains no ethylene-vinyl alcohol copolymer (EVOH) and no polyvinyl alcohol (PVOH).

[0184] Embodiment 9 (V9)

[0185] (V9) Process according to (VI), (V2), (V3), (V4), (V5), (V6), (V7) or (V8), wherein the film is multilayered; wherein the film has at least one layer which contains or consists of the first polypropylene (PPI); wherein the film has at least one layer which contains or consists of a second polyethylene (PE2) and / or a second polypropylene (PP2); wherein the second polyethylene (PE2) has a density of less than 0.940 g / cm 3 and greater than 0.870 g / cm 3, measured according to DIN EN ISO 1183-1:2019-09; wherein the second polypropylene (PP2) is a polypropylene (PP) with a heat distortion temperature of less than 65 °C, particularly preferably less than 55 °C, measured according to ASTM D648-18; wherein the film has at least one layer which contains or consists of a third polypropylene (PP3), wherein the third polypropylene (PP3) has a heat distortion temperature which is lower than the heat distortion temperature of the first polypropylene (PP1) and higher than the heat distortion temperature of the second polypropylene (PP2); and wherein the film has at least one layer which contains ethylene-vinyl alcohol copolymer (EVOH) and / or polyvinyl alcohol (PVOH) or consists of ethylene-vinyl alcohol copolymer (EVOH) or polyvinyl alcohol (PVOH).

[0186] Embodiment 10 (VI 0) (V10) Process according to (VI), (V2), (V3), (V4), (V5), (V6), (V7), (V8) or (V9), wherein the film is multilayered; wherein the film has at least one layer which contains or consists of the first polypropylene (PPI); wherein the film has at least one layer which contains or consists of a second polyethylene (PE2) and / or a second polypropylene (PP2); wherein the film has at least one layer which contains or consists of a third polypropylene (PP3); wherein the film does not contain an ethylene-vinyl alcohol copolymer (EVOH) and no polyvinyl alcohol (PVOH); wherein the second polyethylene (PE2) is a polyethylene (PE) with a density of less than 0.940 g / cm 3 and greater than 0.870 g / cm 3, measured according to DIN EN ISO 1183-1:2019-09; wherein the second polypropylene (PP2) is a polypropylene (PP) with a heat distortion temperature of less than 65 °C, particularly preferably less than 55 °C, measured according to ASTM D648-18; and wherein the third polypropylene (PP3) has a heat distortion temperature which is lower than the heat distortion temperature of the first polypropylene (PPI) and higher than the heat distortion temperature of the second polypropylene (PP2).

[0187] Embodiment 11 (VI 1)

[0188] (VI 1) Process according to (VI), (V2), (V3), (V4), (V5), (V6), (V7), (V8), (V9) or (V10), wherein the process does not comprise a step of laminating or extrusion coating the film or components thereof, particularly preferably layers of the film; and / or wherein the film is multilayered and the co-extrusion of the multilayered film is carried out in a single step. Preferred embodiments of the film according to the invention are listed below, which are preferably produced by the process according to the invention, in particular by one of the above processes VI to VI 1:

[0189] Embodiment 1 (Fl)

[0190] (F1) Single- or multi-layer, extruded, simultaneously biaxially stretched and heat-set film, preferably produced by the process according to the invention or a process according to one of embodiments (VI) to (VI1), wherein the film contains a first polypropylene (PPI); wherein the first polypropylene (PPI) has a heat deflection temperature of greater than 85°C, particularly preferably greater than 95°C, measured according to ASTM D648-18; wherein the film contains the first polypropylene (PPI) in a mass fraction of greater than 50%, preferably greater than 65%, preferably greater than 80%, particularly preferably greater than 90%, based on the total mass of the film; and wherein the film does not contain any of the following polymers selected from the group consisting of polyethylene terephthalate (PET), polyvinylidene chloride (PVDC) and polyamide (PA).

[0191] Embodiment 2 (F2)

[0192] (F2) Film according to (Fl), wherein the film is not laminated.

[0193] Embodiment 3 (F3)

[0194] (F3) Film according to (F1) or (F2), wherein the film is relaxed; wherein a residual stretch factor (RVMD) of the film in the machine direction (MD) is greater than 5.0 and less than 7.0, preferably greater than 5.5 and less than 7.0; wherein a residual stretch factor (RVTD) of the film in the transverse direction (TD) is greater than 4.0 and less than 6.0, preferably greater than 5.0 and less than 6.0; and wherein the residual stretch factor (RVMD) of the film in the machine direction (MD) is greater than the residual stretch factor (RVTD) in the transverse direction (TD); or wherein the film is relaxed; wherein a residual stretch factor (RVMD) of the film in the machine direction (MD) is greater than 5.0 and less than 7.0, and a residual stretch factor (RVTD) of the film in the transverse direction (TD) is greater than 4.0 and less than 6.0; and wherein the residual stretch factor (RVMD) of the film in the machine direction (MD) is greater than the residual stretch factor (RVTD) in the transverse direction (TD); or wherein the film is relaxed;wherein a residual stretch factor (RVMD) of the film in the machine direction (MD) is greater than 6.0 and less than 7.0, and a residual stretch factor (RVTD) of the film in the transverse direction (TD) is greater than 5.0 and less than 6.0; and wherein the residual stretch factor (RVMD) of the film in the machine direction (MD) is greater than the residual stretch factor (RVTD) in the transverse direction (TD).

[0195] Embodiment 4 (F4)

[0196] (F4) Film according to (F1), (F2) or (F3), wherein the film further contains a second polyethylene (PE2); and wherein the second polyethylene (PE2) has a density of less than 0.940 g / cm 3 , preferably less than 0.920 g / cm 3 , and greater than 0.870 g / cm 3 , measured according to DIN EN ISO 1183-1:2019-09.

[0197] Embodiment 5 (F5)

[0198] (F5) Film according to (F1), (F2), (F3) or (F4), wherein the film is multilayered; wherein the film contains ethylene-vinyl alcohol copolymer (EVOH) in a mass fraction of less than 5%, based on the total mass of the film; and wherein the film has at least one layer consisting of ethylene-vinyl alcohol copolymer (EVOH).

[0199] Embodiment 6 (F6)

[0200] (F6) Film according to (F1), (F2), (F3), (F4) or (F5), wherein the film is multilayered; wherein the film contains polyvinyl alcohol (PVOH) in a mass fraction of less than 5%, based on the total mass of the film; and wherein the film has at least one layer consisting of polyvinyl alcohol (PVOH).

[0201] Embodiment 7 (F7)

[0202] (F7) Film according to (F1), (F2), (F3), (F4), (F5) or (F6), wherein the film is multilayered; wherein the film has an outer layer which consists of a second polyethylene (PE2) and / or a second polypropylene (PP2); wherein the second polyethylene (PE2) has a density of less than 0.940 g / cm 3 and greater than 0.870 g / cm 3 , measured according to DIN EN ISO 1183-1:2019-09; wherein the second polypropylene (PP2) has a heat distortion temperature of less than 65 °C, particularly preferably less than 55 °C, measured according to ASTM D648-18; and wherein the outer layer contains no ethylene-vinyl alcohol copolymer (EVOH) and no polyvinyl alcohol (PVOH).

[0203] Embodiment 8 (F8)

[0204] (F8) Film according to (F1), (F2), (F3), (F4), (F5), (F6) or (F7), wherein the film is multilayered; wherein the film has an inner layer which contains or consists of a second polyethylene (PE2) and / or a second polypropylene (PP2); wherein the second polyethylene (PE2) is a polyethylene (PE) with a density of less than 0.940 g / cm 3 and greater than 0.870 g / cm 3 , measured according to DIN EN ISO 1183-1:2019-09; wherein the second polypropylene (PP2) is a polypropylene (PP) with a heat distortion temperature of less than 65 °C, particularly preferably less than 55 °C, measured according to ASTM D648-18; and wherein the inner layer contains no ethylene-vinyl alcohol copolymer (EVOH) and no polyvinyl alcohol (PVOH).

[0205] Embodiment 9 (F9)

[0206] (F9) Film according to (F1), (F2), (F3), (F4), (F5), (F6), (F7) or (F8), wherein the film is multilayered; wherein the film has at least one layer which contains or consists of the first polypropylene (PPI); wherein the film has at least one layer which contains or consists of a second polyethylene (PE2) and / or a second polypropylene (PP2); wherein the second polyethylene (PE2) has a density of less than 0.940 g / cm 3 and greater than 0.870 g / cm 3, measured according to DIN EN ISO 1183-1:2019-09; wherein the second polypropylene (PP2) is a polypropylene (PP) with a heat distortion temperature of less than 65 °C, particularly preferably less than 55 °C, measured according to ASTM D648-18; wherein the film has at least one layer which contains or consists of a third polypropylene (PP3), wherein the third polypropylene (PP3) has a heat distortion temperature which is lower than the heat distortion temperature of the first polypropylene (PP1) and higher than the heat distortion temperature of the second polypropylene (PP2); and wherein the film has at least one layer which contains ethylene-vinyl alcohol copolymer (EVOH) and / or polyvinyl alcohol (PVOH) or consists of ethylene-vinyl alcohol copolymer (EVOH) or polyvinyl alcohol (PVOH).

[0207] Embodiment 10 (F10)

[0208] (F10) Film according to (F1), (F2), (F3), (F4), (F5), (F6), (F7), (F8) or (F9), wherein the film is multilayered; wherein the film has at least one layer which contains or consists of the first polypropylene (PPI); wherein the film has at least one layer which contains or consists of a second polyethylene (PE2) and / or a second polypropylene (PP2); wherein the film has at least one layer which contains or consists of a third polypropylene (PP3); wherein the film does not contain an ethylene-vinyl alcohol copolymer (EVOH) and no polyvinyl alcohol (PVOH); wherein the second polyethylene (PE2) is a polyethylene (PE) with a density of less than 0.940 g / cm 3 and greater than 0.870 g / cm 3, measured according to EN ISO 1183-1:2019-09; wherein the second polypropylene (PP2) is a polypropylene (PP) with a heat distortion temperature of less than 65 °C, particularly preferably less than 55 °C, measured according to ASTM D648-18; and wherein the third polypropylene (PP3) has a heat distortion temperature which is lower than the heat distortion temperature of the first polypropylene (PPI) and higher than the heat distortion temperature of the second polypropylene (PP2).

[0209] Embodiment 11 (Fl 1)

[0210] (F1 l)Film according to (F1), (F2) or (F3), wherein the film consists of a single layer consisting of the first polypropylene (PPI); or wherein the film consists of several, preferably two, three, four or five, layers, each consisting of the first polypropylene (PPI).

[0211] Preferred embodiments of the use according to the invention are listed below:

[0212] Embodiment 1 (Ul)

[0213] (U1) Use of a first polypropylene (PPI) for a single- or multi-layer, extruded, simultaneously biaxially stretched and heat-set film, preferably for the film according to the invention or a film according to one of the embodiments (F1) to (F11), or for the production thereof; wherein the film contains the first polypropylene (PPI) in a mass fraction of greater than 50%, preferably greater than 65%, preferably greater than 80%, particularly preferably greater than 90%, based on the total mass of the film; wherein the first polypropylene (PPI) has a heat deflection temperature of greater than 85°C, particularly preferably greater than 95°C, measured according to ASTM D648-18; and wherein the film does not contain any of the following polymers selected from the group consisting of polyethylene terephthalate (PET), polyvinylidene chloride (PVDC) and polyamide (PA).

[0214] Embodiment 2 (U2)

[0215] (U2) Use according to (U1), wherein the film further contains a second polyethylene (PE2); and wherein the second polyethylene (PE2) has a density of less than 0.940 g / cm 3 and greater than 0.870 g / cm 3 , measured according to DIN EN ISO 1183-1:2019-09.

[0216] Embodiment 3 (U3)

[0217] (U3) Use of a film according to one of the embodiments (Fl) to (Fl 1) as a ready-to-use packaging material for food or for producing a ready-to-use packaging material for food by laminating a further polymer layer or several further polymer layers or a package of several polymer layers.

[0218] It is expressly part of the disclosure of the present invention to combine any selection of the features marked with “in particular” or “particularly preferred” in the claims or in the description in the sense of an overall particularly preferred embodiment of the invention.

[0219] Furthermore, it is expressly part of the disclosure of the present invention to combine any selection of the features marked with “preferably” in the claims or in the description in the sense of an overall preferred embodiment of the invention.

[0220] It is also expressly part of the disclosure of the present invention to combine any selection of the features marked "particularly preferred" in the embodiments mentioned above or below in the sense of an overall particularly preferred embodiment of the invention. Furthermore, it is expressly part of the disclosure of the present invention to combine any selection of the features marked "preferably" in the embodiments mentioned above or below in the sense of an overall preferred embodiment of the invention. Further disclosure of the invention

[0221] In the context of the present invention, the term “produced by the process” is synonymous with “producible by the process” and can be replaced by this.

[0222] The subject matter of the independent process claim may be limited by one of the following features or by any selection of the following features, including all of them:

[0223] • wherein the first polypropylene (PPI) is present in a mass fraction of greater than 50%, preferably greater than 65%, preferably greater than 80%, in particular greater than 90%, based on the total mass of the film;

[0224] • wherein a residence time during the heat-setting (= duration of the heat-setting of the film), during which the film has the third temperature (T3), is greater than 1.5 seconds and less than 50 seconds, preferably greater than 2 seconds and less than 40 seconds, in particular greater than 3 seconds and less than 30 seconds.

[0225] The subject matter of the independent product claim can be further limited by the following feature: wherein the film contains the first polypropylene (PPI) in a mass fraction of greater than 50%, preferably greater than 65%, preferably greater than 80%, in particular greater than 90%, based on the total mass of the film; Within the scope of the invention, in particular in claim 2, the feature wherein the film is cooled after extrusion within a period of 0.01 to 1 second, preferably 0.05 to 0.5 seconds, in particular 0.07 to 0.3 seconds, to a first temperature (TI) of below 20°C, preferably below 15°C, in particular below 10°C; can be replaced or supplemented by the feature wherein the film is cooled after extrusion at a cooling rate of 240 to 24,000°C / second, preferably 800 to 3,500°C / second.

[0226] Within the scope of the invention, in particular in claim 2, the feature wherein the film is heated from the first temperature (TI) to the second temperature (T2) within a period of 1 to 18 seconds, preferably 1.5 to 12 seconds, in particular 2 to 9 seconds, prior to stretching; can be replaced or supplemented by the feature wherein the film is heated from the first temperature (TI) to the second temperature (T2) at a heating rate of 5 to 170 °C / second, preferably 10 to 85 °C / second.

[0227] Within the scope of the invention, in particular in claim 6, the feature • wherein the film is cooled after stretching within a period of 0.01 to 1 second, preferably from 0.05 to 0.5 seconds, in particular from 0.07 to 0.3 seconds, to a fourth temperature (T4) of below 50 °C, preferably below 40 °C, in particular below 30 °C; by the feature

[0228] • wherein the film is cooled after stretching at a cooling rate of 100 to 10,000 °C / second to a fourth temperature (T4) of below 50 °C, preferably below 40 °C, in particular below 30 °C; replaced or supplemented.

[0229] Further disclosure of the invention

[0230] The following numbers 1 to 53 define objects which belong to and are encompassed by the present invention:

[0231] 1. A process for producing a single- or multi-layer film, the process comprising at least the following steps: a step of extruding a layer or co-extruding several layers to obtain an extruded film; a step of simultaneously biaxially stretching the extruded film; and a step of heat-setting the stretched film; wherein the film contains a first polypropylene (PPI); wherein the first polypropylene (PPI) has a heat deflection temperature of greater than 75°C, preferably greater than 85°C, in particular greater than 95°C, measured according to ASTM D648-18; wherein the film contains the first polypropylene (PPI) in a mass fraction of greater than 30%, preferably greater than 40%, preferably greater than 50%, preferably greater than 65%, preferably greater than 80%, in particular greater than 90%, based on the total mass of the film;wherein the film does not contain any of the following polymers selected from the group consisting of polyethylene terephthalate (PET), polyvinylidene chloride (PVDC) and polyamide (PA); wherein the stretch factor (VMD) in the machine direction (MD) is greater than the stretch factor (VTD) in the transverse direction (TD); wherein the film has a second temperature (T2) of greater than 120°C and less than 180°C, preferably greater than 130°C and less than 170°C, in particular greater than 140°C and less than 160°C, during stretching;and wherein the film has a third temperature (T3) of greater than 60°C and less than 200°C, preferably greater than 80°C and less than 180°C, in particular greater than 100°C and less than 160°C, during heat-setting. A process for producing a single- or multi-layer film, the process comprising at least the following steps: a step of extruding a layer or co-extruding a plurality of layers, thereby obtaining an extruded film; a step of simultaneously biaxially stretching the extruded film; and a step of heat-setting the stretched film; wherein the film contains a first polypropylene (PPI); wherein the first polypropylene (PPI) has a heat deflection temperature of greater than 75°C, preferably greater than 85°C, in particular greater than 95°C, measured according to ASTM D648-18;wherein the film contains the first polypropylene (PPI) in a mass fraction of greater than 30%, preferably greater than 40%, preferably greater than 50%, preferably greater than 65%, preferably greater than 80%, in particular greater than 90%, based on the total mass of the film; wherein the film does not contain any of the following polymers selected from the group consisting of polyethylene terephthalate (PET), polyvinylidene chloride (PVDC) and polyamide (PA); wherein the film is cooled after extrusion within a period of 0.01 to 1 second, preferably 0.05 to 0.5 seconds, in particular 0.07 to 0.3 seconds, to a first temperature (TI) of below 20°C, preferably below 15°C, in particular below 10°C; wherein the stretch factor (VMD) in the machine direction (MD) is greater than the stretch factor (VTD) in the transverse direction (TD);wherein the film has a second temperature (T2) of greater than 120°C and less than 180°C, preferably greater than 130°C and less than 170°C, in particular greater than 140°C and less than 160°C, during stretching; wherein the film is heated from the first temperature (T1) to the second temperature (T2) within a period of 1 to 18 seconds, preferably 1.5 to 12 seconds, in particular 2 to 9 seconds, before stretching; wherein a time period (At) (= t2 - t1) between a first time point (t1) at which the film reaches the second temperature (T2) and a second time point (t2) at which stretching of the film begins is 0.05 to 6 seconds, preferably 0.1 to 3 seconds, in particular 0.3 to 1.5 seconds; wherein the film has a third temperature (T3) of greater than 60 °C and less than 200 °C, preferably greater than 80 °C and less than 180 °C, in particular greater than 100 °C and less than 160 °C, during heat-setting;and wherein a residence time during heat-setting (= duration of heat-setting of the film), during which the film has the third temperature (T3), is greater than 1 second and less than 60 seconds, preferably greater than 2 seconds and less than 45 seconds, in particular greater than 3 seconds and less than 30 seconds. A process for producing a single- or multi-layer film, the process comprising at least the following steps: a step of extruding a layer or co-extruding several layers, thereby obtaining an extruded film; a step of simultaneously biaxially stretching the extruded film; and a step of heat-setting the stretched film; wherein the film contains a first polypropylene (PPI) in a mass fraction of greater than 30%, preferably greater than 40%, preferably greater than 50%, preferably greater than 65%, preferably greater than 80%, in particular greater than 90%, based on the total mass of the film;wherein the first polypropylene (PPI) has a heat deflection temperature of greater than 75°C, preferably greater than 85°C, in particular greater than 95°C, measured according to ASTM D648-18; wherein the film does not contain any of the following polymers selected from the group consisting of polyethylene terephthalate (PET), polyvinylidene chloride (PVDC) and polyamide (PA); wherein the film is cooled after extrusion within a period of 0.01 to 1 second, preferably 0.05 to 0.5 seconds, in particular 0.07 to 0.3 seconds, to a first temperature (TI) of less than 20°C, preferably less than 15°C, in particular less than 10°C; wherein a stretch factor (VMD) in the machine direction or longitudinal direction (MD) is greater than 5.0, preferably greater than 6.0, in particular greater than 7.0, and less than 8.0;wherein a stretch factor (VTD) in the transverse direction (TD) is greater than 4.0, preferably greater than 5.0, in particular greater than 6.0, and less than 7.0; wherein the stretch factor (VMD) in the machine direction (MD) is greater than the stretch factor (VTD) in the transverse direction (TD); wherein the film has a second temperature (T2) of greater than 120°C and less than 180°C, preferably greater than 130°C and less than 170°C, in particular greater than 140°C and less than 160°C, during stretching; wherein the film is heated from the first temperature (TI) to the second temperature (T2) within a period of 1 to 18 seconds, preferably 1.5 to 12 seconds, in particular 2 to 9 seconds, before stretching;wherein a time period (At) (= t2 - t1) between a first point in time (t1) at which the film reaches the second temperature (T2) and a second point in time (t2) at which the stretching of the film begins is 0.05 to 3 seconds, preferably 0.1 to 3 seconds, in particular 0.3 to 1.5 seconds; wherein the film has a third temperature (T3) of greater than 60 °C and less than 200 °C, preferably greater than 80 °C and less than 180 °C, in particular greater than 100 °C and less than 160 °C, during the heat-setting; and wherein a residence time during the heat-setting (= duration of the heat-setting of the film), during which the film has the third temperature (T3), is greater than 2 seconds and less than 60 seconds, preferably greater than 3 seconds and less than 45 seconds, in particular greater than 4 seconds and less than 30 seconds. A method according to any one of numbers 1 to 3, wherein the method further comprises relaxing the film during heat setting of the film;wherein a relaxation factor (RMD) in the machine direction (MD) is greater than 0.00 and less than 0.10, preferably greater than 0.00 and less than 0.05, in particular greater than 0.00 and less than 0.03; wherein a relaxation factor (RTD) in the transverse direction (TD) is greater than 0.00 and less than 0.20, preferably greater than 0.00 and less than 0.10, in particular greater than 0.00 and less than 0.05; and wherein the relaxation factor (RTD) in the transverse direction (TD) is greater than the relaxation factor (RMD) in the machine direction (MD). Method according to number 4, wherein the film has the third temperature (T3) during the relaxation;and wherein a duration of relaxation of the film, during which the film has the third temperature (T3), is greater than 2 seconds, preferably greater than 3 seconds, in particular greater than 4 seconds, and less than 45 seconds, preferably less than 30 seconds. Method according to one of numbers 1 to 5, wherein the method further provides for cooling the film after stretching and before heat-setting; wherein the film is cooled after stretching within a period of 0.01 to 1 second, preferably 0.05 to 0.5 seconds, in particular 0.07 to 0.3 seconds, to a fourth temperature (T4) of below 50°C, preferably below 40°C, in particular below 30°C. Method according to one of numbers 1 to 6, wherein the film is multilayered; wherein the film has at least one layer, preferably an outer layer and / or an inner layer, which contains or consists of a second polyethylene (PE2);wherein the second polyethylene (PE2) is a polyethylene (PE) with a density of less than 0.940 g / cm; 3 , preferably less than 0.920 g / cm 3 , and greater than 0.870 g / cm 3, measured according to DIN EN ISO 1183-1:2019-09. Process according to one of numbers 1 to 7, wherein the film is multilayer; wherein the film has at least one layer, preferably an outer layer and / or an inner layer, which contains or consists of a second polypropylene (PP2); wherein the second polypropylene (PP2) is a polypropylene (PP) with a heat distortion temperature of less than 75 °C, preferably less than 65 °C, in particular less than 55 °C, measured according to ASTM D648-18.Method according to one of numbers 1 to 8, wherein the film is multilayered; wherein the film has at least one layer, preferably an outer layer and / or an inner layer, which contains or consists of a third polypropylene (PP3); wherein the third polypropylene (PP3) has a heat distortion temperature which is lower than the heat distortion temperature of the first polypropylene (PP1) and higher than the heat distortion temperature of the second polypropylene (PP2).Method according to one of numbers 1 to 9, wherein the film is multi-layered; wherein the film contains ethylene-vinyl alcohol copolymer (EVOH) in a mass fraction of less than or equal to 5%, preferably less than 5%, based on the total mass of the film; wherein the film has at least one intermediate layer which contains ethylene-vinyl alcohol copolymer (EVOH) or consists of ethylene-vinyl alcohol copolymer (EVOH); wherein the at least one intermediate layer which contains ethylene-vinyl alcohol copolymer (EVOH) contains no polyethylene (PE) and no polypropylene (PP); and wherein preferably the intermediate layer which contains ethylene-vinyl alcohol copolymer (EVOH) or consists of ethylene-vinyl alcohol copolymer (EVOH) is surrounded on both sides by layers which each contain an adhesion promoter (HV).Process according to one of numbers 1 to 10, wherein the film is multilayered; wherein the film contains polyvinyl alcohol (PVOH) in a mass fraction of less than or equal to 5%, preferably less than 5%, based on the total mass of the film; wherein the film has at least one intermediate layer which contains polyvinyl alcohol (PVOH) or consists of polyvinyl alcohol (PVOH); wherein the at least one intermediate layer which contains polyvinyl alcohol (PVOH) contains no polyethylene (PE) and no polypropylene (PP); and wherein preferably the intermediate layer which contains polyvinyl alcohol (PVOH) or consists of polyvinyl alcohol (PVOH) is surrounded on both sides by layers which each contain an adhesion promoter (HV). Process according to one of numbers 1 to 9, wherein the film contains no ethylene-vinyl alcohol copolymer (EVOH) and no polyvinyl alcohol (PVOH).The process according to any one of numbers 1 to 9, wherein the film has an outer layer and an inner layer; wherein the outer layer does not contain ethylene-vinyl alcohol copolymer (EVOH) or polyvinyl alcohol (PVOH); and wherein the inner layer does not contain ethylene-vinyl alcohol copolymer (EVOH) or polyvinyl alcohol (PVOH). The process according to any one of numbers 1 to 13, wherein the film does not contain any of the following polymers selected from the group consisting of polyethylene terephthalate (PET), polyvinylidene chloride (PVDC), and polyamide (PA). The process according to any one of numbers 1 to 14, wherein the film is multilayer; wherein the film has at least one layer consisting of the first polypropylene (PPI) and at least one layer consisting of the second polyethylene (PE2).Method according to one of numbers 1 to 15, wherein the film is multi-layered; wherein the film has at least one layer consisting of the first polypropylene (PPI) and at least one layer consisting of the second polypropylene (PP2); or wherein the film has at least one layer consisting of the first polypropylene (PPI) and at least one layer consisting of the third polypropylene (PP3); or wherein the film has at least one layer consisting of the first polypropylene (PPI) and at least one layer consisting of the second polypropylene (PP2) and at least one layer consisting of the third polypropylene (PP3).Process according to one of numbers 1 to 16, wherein the film is multilayer; wherein the film has at least one layer which contains or consists of the first polypropylene (PPI); and wherein the film has at least one layer which contains ethylene-vinyl alcohol copolymer (EVOH) and / or polyvinyl alcohol (PVOH) or consists of ethylene-vinyl alcohol copolymer (EVOH) or polyvinyl alcohol (PVOH). Process according to one of numbers 1 to 17, wherein the film is multilayer; wherein the film has at least one layer which contains or consists of the first polypropylene (PPI); wherein the film has at least one layer which contains or consists of the second polyethylene (PE2); and wherein the film has at least one layer which contains ethylene-vinyl alcohol copolymer (EVOH) and / or polyvinyl alcohol (PVOH) or consists of ethylene-vinyl alcohol copolymer (EVOH) or polyvinyl alcohol (PVOH).Method according to one of numbers 1 to 18, wherein the film is multi-layered; wherein the film has at least one layer which contains or consists of the first polypropylene (PPI); wherein the film has at least one layer which contains or consists of the second polypropylene (PP2); and wherein the film has at least one layer which contains ethylene-vinyl alcohol copolymer (EVOH) and / or polyvinyl alcohol (PVOH) or consists of ethylene-vinyl alcohol copolymer (EVOH) or polyvinyl alcohol (PVOH).Method according to one of numbers 1 to 19, wherein the film is multi-layered; wherein the film has at least one layer which contains or consists of the first polypropylene (PPI); wherein the film has at least one layer which contains or consists of the third polypropylene (PP3); and wherein the film has at least one layer which contains ethylene-vinyl alcohol copolymer (EVOH) and / or polyvinyl alcohol (PVOH) or consists of ethylene-vinyl alcohol copolymer (EVOH) or polyvinyl alcohol (PVOH).Method according to one of numbers 1 to 20, wherein the film is multi-layered; wherein the film has at least one layer which contains or consists of the first polypropylene (PPI); wherein the film has at least one layer which contains or consists of the second polypropylene (PP2); wherein the film has at least one layer which contains or consists of the third polypropylene (PP3); and wherein the film has at least one layer which contains ethylene-vinyl alcohol copolymer (EVOH) and / or polyvinyl alcohol (PVOH) or consists of ethylene-vinyl alcohol copolymer (EVOH) or polyvinyl alcohol (PVOH).Process according to one of numbers 1 to 21, wherein the process does not comprise a step of laminating or extrusion coating the film or components thereof, in particular layers of the film; and / or wherein the film is multilayered and the co-extrusion of the multilayered film is carried out in a single step.Method according to one of numbers 1 to 22, wherein the film is multi-layered; wherein the film has at least one outer layer and / or one inner layer, preferably an inner layer, which contains or consists of a second polymer (PM2), preferably a second polyolefin (PO2); wherein the second polymer (PM2), preferably the second polyolefin (PO2), is preferably sealable, in particular heat-sealable, and preferably contains or consists of a polyethylene (PE), a polypropylene (PP), an ethylene-vinyl acetate copolymer (EVA), an ionomer (IO), an ethylene-methyl methacrylate copolymer (EMMA), an ethylene-methacrylic acid copolymer (EMA) or any mixture thereof.

[0232] 24. Method according to one of numbers 1 to 23, wherein the film is multi-layered; wherein the film has at least one outer layer and / or one inner layer, preferably an outer layer, which contains or consists of a third polymer (PM3), preferably a third polyolefin (PO3); wherein the third polymer (PM3), preferably the third polyolefin (PO3), is preferably not sealable, more preferably not heat sealable, in particular has a sealing temperature which is higher than the sealing temperature of the second polymer (PM2), preferably the second polyolefin (PO2), and preferably contains or consists of a polyethylene (PE) and / or a polypropylene (PP) or any mixture thereof.

[0233] 25. A single- or multi-layer, extruded, simultaneously biaxially stretched and heat-set film, preferably produced by the process according to one of numbers 1 to 24, wherein the film contains a first polypropylene (PPI); wherein the first polypropylene (PPI) has a heat deflection temperature of greater than 75°C, preferably greater than 85°C, in particular greater than 95°C, measured according to ASTM D648-18; wherein the film contains the first polypropylene (PPI) in a mass fraction of greater than 30%, preferably greater than 40%, preferably greater than 50%, preferably greater than 65%, preferably greater than 80%, in particular greater than 90%, based on the total mass of the film; and wherein the film does not contain any of the following polymers selected from the group consisting of polyethylene terephthalate (PET), polyvinylidene chloride (PVDC) and polyamide (PA).

[0234] 26. A single- or multi-layer, extruded, simultaneously biaxially stretched and heat-set film, preferably produced by the process according to one of numbers 1 to 24, wherein the film contains a first polypropylene (PPI); wherein the first polypropylene (PPI) has a heat deflection temperature of greater than 75°C, preferably greater than 85°C, in particular greater than 95°C, measured according to ASTM D648-18; wherein the film contains the first polypropylene (PPI) in a mass fraction of greater than 40%, preferably greater than 50%, preferably greater than 65%, preferably greater than 80%, in particular greater than 90%, based on the total mass of the film; and wherein the film does not contain any of the following polymers selected from the group consisting of polyethylene terephthalate (PET), polyvinylidene chloride (PVDC) and polyamide (PA).

[0235] 27. Film according to paragraph 25 or 26, which film is not laminated.

[0236] 28. The film according to number 25 or 26, wherein the film is relaxed; wherein a residual stretch factor (RVMD) of the film in the machine direction (MD) is greater than 5.0 and less than 7.0, preferably greater than 5.5 and less than 7.0, in particular greater than 6.0 and less than 7.0; wherein a residual stretch factor (RVTD) of the film in the transverse direction (TD) is greater than 4.0 and less than 6.0, preferably greater than 4.5 and less than 6.0, in particular greater than 5.0 and less than 6.0; and wherein the residual stretch factor (RVMD) of the film in the machine direction (MD) is greater than the residual stretch factor (RVTD) in the transverse direction (TD); or wherein the film is relaxed; wherein a residual stretch factor (RVMD) of the film in the machine direction (MD) is greater than 5.0 and less than 7.0, and a residual stretch factor (RVTD) of the film in the transverse direction (TD) is greater than 4.0 and less than 6.0;and wherein the residual stretch factor (RVMD) of the film in the machine direction (MD) is greater than the residual stretch factor (RVTD) in the transverse direction (TD); or wherein the film is relaxed; wherein a residual stretch factor (RVMD) of the film in the machine direction (MD) is greater than 5.5 and less than 7.0, and a residual stretch factor (RVTD) of the film in the transverse direction (TD) is greater than 4.5 and less than 6.0; and wherein the residual stretch factor (RVMD) of the film in the machine direction (MD) is greater than the residual stretch factor (RVTD) in the transverse direction (TD); or wherein the film is relaxed; wherein a residual stretch factor (RVMD) of the film in the machine direction (MD) is greater than 6.0 and less than 7.0, and a residual stretch factor (RVTD) of the film in the transverse direction (TD) is greater than 5.0 and less than 6.0;and wherein the residual stretch factor (RVMD) of the film in the machine direction (MD) is greater than the residual stretch factor (RVTD) in the transverse direction (TD). Film according to number 25 or 26, wherein the film is relaxed and the first polypropylene (PPI) has a heat distortion temperature of greater than 85°C; wherein a residual stretch factor (RVMD) of the film in the machine direction (MD) is greater than 3.6 and less than 3.9, preferably greater than 4.1 and less than 4.4, in particular greater than 5.0 and less than 5.4; wherein a residual stretch factor (RVTD) of the film in the transverse direction (TD) is greater than 2.8 and less than 3.4, preferably greater than 3.6 and less than 3.9, in particular greater than 4.1 and less than 4.4. and wherein the residual stretch factor (RVMD) of the film in the machine direction (MD) is greater than the residual stretch factor (RVTD) in the transverse direction (TD);or wherein the film is relaxed and the first polypropylene (PPI) has a heat distortion temperature of greater than 85°C; wherein a residual stretch factor (RVMD) of the film in the machine direction (MD) is greater than 3.6 and less than 3.9, and a residual stretch factor (RVTD) of the film in the transverse direction (TD) is greater than 2.8 and less than 3.4; and wherein the residual stretch factor (RVMD) of the film in the machine direction (MD) is greater than the residual stretch factor (RVTD) in the transverse direction (TD); or wherein the film is relaxed and the first polypropylene (PPI) has a heat distortion temperature of greater than 85°C; wherein a residual stretch factor (RVMD) of the film in the machine direction (MD) is greater than 4.1 and less than 4.4, and a residual stretch factor (RVTD) of the film in the transverse direction (TD) is greater than 3.6 and less than 3.9;and wherein the residual stretch factor (RVMD) of the film in the machine direction (MD) is greater than the residual stretch factor (RVTD) in the transverse direction (TD); or wherein the film is relaxed and the first polypropylene (PPI) has a heat distortion temperature of greater than 85°C; wherein a residual stretch factor (RVMD) of the film in the machine direction (MD) is greater than 5.0 and less than 5.4, and a residual stretch factor (RVTD) of the film in the transverse direction (TD) is greater than 4.1 and less than 4.4, and wherein the residual stretch factor (RVMD) of the film in the machine direction (MD) is greater than the residual stretch factor (RVTD) in the transverse direction (TD). Film according to number 25 or 26, wherein the film is relaxed and the first polypropylene (PPI) has a heat distortion temperature of greater than 75°C and less than or equal to 85°C;wherein a residual stretch factor (RVMD) of the film in the machine direction (MD) is greater than 5.0 and less than 7.0, preferably greater than 5.5 and less than 7.0, in particular greater than 6.0 and less than 7.0; wherein a residual stretch factor (RVTD) of the film in the transverse direction (TD) is greater than 4.0 and less than 6.0, preferably greater than 4.5 and less than 6.0, in particular greater than 5.0 and less than 6.0; and wherein the residual stretch factor (RVMD) of the film in the machine direction (MD) is greater than the residual stretch factor (RVTD) in the transverse direction (TD); or wherein the film is relaxed and the first polypropylene (PPI) has a heat distortion temperature of greater than 75°C and less than or equal to 85°C; wherein a residual stretch factor (RVMD) of the film in the machine direction (MD) is greater than 5.0 and less than 7.0, and a residual stretch factor (RVTD) of the film in the transverse direction (TD) is greater than 4.0 and less than 6.0;and wherein the residual stretch factor (RVMD) of the film in the machine direction (MD) is greater than the residual stretch factor (RVTD) in the transverse direction (TD); or wherein the film is relaxed and the first polypropylene (PPI) has a heat distortion temperature of greater than 75°C and less than or equal to 85°C; wherein a residual stretch factor (RVMD) of the film in the machine direction (MD) is greater than 5.5 and less than 7.0, and a residual stretch factor (RVTD) of the film in the transverse direction (TD) is greater than 4.5 and less than 6.0; and wherein the residual stretch factor (RVMD) of the film in the machine direction (MD) is greater than the residual stretch factor (RVTD) in the transverse direction (TD); or wherein the film is relaxed and the first polypropylene (PPI) has a heat distortion temperature of greater than 75°C and less than or equal to 85°C;wherein a residual stretch factor (RVMD) of the film in the machine direction (MD) is greater than 6.0 and less than 7.0, and a residual stretch factor (RVTD) of the film in the transverse direction (TD) is greater than 5.0 and less than 6.0; and wherein the residual stretch factor (RVMD) of the film in the machine direction (MD) is greater than the residual stretch factor (RVTD) in the transverse direction (TD). Film according to one of numbers 25 to 30, wherein the film is multilayer; wherein the film has at least one layer, preferably an outer layer and / or an inner layer, which contains or consists of a second polyethylene (PE2); wherein the second polyethylene (PE2) is a polyethylene (PE) with a density of less than 0.940 g / cm; 3 , preferably less than 0.920 g / cm 3 , and greater than 0.870 g / cm 3, measured according to DIN EN ISO 1183-1:2019-09. Film according to one of numbers 25 to 31, wherein the film is multilayer; wherein the film has at least one layer, preferably an outer layer and / or an inner layer, which contains or consists of a second polypropylene (PP2); wherein the second polypropylene (PP2) is a polypropylene (PP) with a heat distortion temperature of less than 75 °C, preferably less than 65 °C, in particular less than 55 °C, measured according to ASTM D648-18.Film according to one of numbers 25 to 32, wherein the film is multilayer; wherein the film has at least one layer, preferably an outer layer and / or an inner layer, which contains or consists of a third polypropylene (PP3); wherein the third polypropylene (PP3) has a heat distortion temperature which is lower than the heat distortion temperature of the first polypropylene (PP1) and higher than the heat distortion temperature of the second polypropylene (PP2).Film according to one of numbers 25 to 33, wherein the film is multi-layered; wherein the film contains ethylene-vinyl alcohol copolymer (EVOH) in a mass fraction of less than or equal to 5%, preferably less than 5%, based on the total mass of the film; wherein the film has at least one intermediate layer which contains ethylene-vinyl alcohol copolymer (EVOH) or consists of ethylene-vinyl alcohol copolymer (EVOH); wherein the at least one intermediate layer which contains ethylene-vinyl alcohol copolymer (EVOH) contains no polyethylene (PE) and no polypropylene (PP); and wherein preferably the intermediate layer which contains ethylene-vinyl alcohol copolymer (EVOH) or consists of ethylene-vinyl alcohol copolymer (EVOH) is surrounded on both sides by layers which each contain an adhesion promoter (HV).Film according to one of numbers 25 to 34, wherein the film is multilayered; wherein the film contains polyvinyl alcohol (PVOH) in a mass fraction of less than or equal to 5%, preferably less than 5%, based on the total mass of the film; wherein the film has at least one intermediate layer which contains polyvinyl alcohol (PVOH) or consists of polyvinyl alcohol (PVOH); wherein the at least one intermediate layer which contains polyvinyl alcohol (PVOH) contains no polyethylene (PE) and no polypropylene (PP); and wherein preferably the intermediate layer which contains polyvinyl alcohol (PVOH) or consists of polyvinyl alcohol (PVOH) is surrounded on both sides by layers which each contain an adhesion promoter (HV). Film according to one of numbers 25 to 33, wherein the film contains no ethylene-vinyl alcohol copolymer (EVOH) and no polyvinyl alcohol (PVOH). 37.A film according to any one of numbers 25 to 33, wherein the film has an outer layer and an inner layer; wherein the outer layer does not contain ethylene-vinyl alcohol copolymer (EVOH) and polyvinyl alcohol (PVOH); and wherein the inner layer does not contain ethylene-vinyl alcohol copolymer (EVOH) and polyvinyl alcohol (PVOH).

[0237] 38. Film according to any one of numbers 25 to 37, wherein the film does not contain any of the following polymers selected from the group consisting of polyethylene terephthalate (PET), polyvinylidene chloride (PVDC) and polyamide (PA).

[0238] 39. The film according to any one of numbers 25 to 38, wherein the film is multilayered; wherein the film has at least one layer consisting of the first polypropylene (PPI) and at least one layer consisting of the second polyethylene (PE2).

[0239] 40. Film according to one of numbers 25 to 39, wherein the film is multi-layered; wherein the film has at least one layer consisting of the first polypropylene (PPI) and at least one layer consisting of the second polypropylene (PP2); or wherein the film has at least one layer consisting of the first polypropylene (PPI) and at least one layer consisting of the third polypropylene (PP3); or wherein the film has at least one layer consisting of the first polypropylene (PPI) and at least one layer consisting of the second polypropylene (PP2) and at least one layer consisting of the third polypropylene (PP3).

[0240] 41. Film according to any one of numbers 25 to 40, wherein the film is multilayered; wherein the film has at least one layer which contains ethylene-vinyl alcohol copolymer (EVOH) and / or polyvinyl alcohol (PVOH) or consists of ethylene-vinyl alcohol copolymer (EVOH) or polyvinyl alcohol (PVOH).

[0241] 42. The film according to any one of numbers 25 to 41, wherein the film is multilayered; wherein the film has at least one layer containing or consisting of the first polypropylene (PPI); and wherein the film has at least one layer containing or consisting of ethylene-vinyl alcohol copolymer (EVOH) and / or polyvinyl alcohol (PVOH).

[0242] 43. Film according to one of numbers 25 to 42, wherein the film is multilayer; wherein the film has at least one layer which contains or consists of the first polypropylene (PPI); wherein the film has at least one layer which contains or consists of the second polyethylene (PE2); and wherein the film has at least one layer which contains ethylene-vinyl alcohol copolymer (EVOH) and / or polyvinyl alcohol (PVOH) or consists of ethylene-vinyl alcohol copolymer (EVOH) or polyvinyl alcohol (PVOH).

[0243] 44. Film according to one of numbers 25 to 43, wherein the film is multilayer; wherein the film has at least one layer which contains or consists of the first polypropylene (PPI); wherein the film has at least one layer which contains or consists of the second polypropylene (PP2); and wherein the film has at least one layer which contains ethylene-vinyl alcohol copolymer (EVOH) and / or polyvinyl alcohol (PVOH) or consists of ethylene-vinyl alcohol copolymer (EVOH) or polyvinyl alcohol (PVOH).

[0244] 45. Film according to one of numbers 25 to 44, wherein the film is multilayer; wherein the film has at least one layer which contains or consists of the first polypropylene (PPI); wherein the film has at least one layer which contains or consists of the third polypropylene (PP3); and wherein the film has at least one layer which contains ethylene-vinyl alcohol copolymer (EVOH) and / or polyvinyl alcohol (PVOH) or consists of ethylene-vinyl alcohol copolymer (EVOH) or polyvinyl alcohol (PVOH).Film according to one of numbers 25 to 45, wherein the film is multi-layered; wherein the film has at least one layer which contains or consists of the first polypropylene (PPI); wherein the film has at least one layer which contains or consists of the second polypropylene (PP2); wherein the film has at least one layer which contains or consists of the third polypropylene (PP3); and wherein the film has at least one layer which contains ethylene-vinyl alcohol copolymer (EVOH) and / or polyvinyl alcohol (PVOH) or consists of ethylene-vinyl alcohol copolymer (EVOH) or polyvinyl alcohol (PVOH). Film according to one of numbers 25 to 46, wherein the film consists of a single layer consisting of the first polypropylene (PPI); or wherein the film consists of several, preferably two, three, four or five, layers, each consisting of the first polypropylene (PPI).Film according to one of numbers 25 to 47, wherein the film is multilayer; wherein the film has at least one outer layer and / or one inner layer, preferably an inner layer, which contains or consists of a second polymer (PM2), preferably a second polyolefin (PO2); wherein the second polymer (PM2), preferably the second polyolefin (PO2), is preferably sealable, in particular heat-sealable, and preferably contains or consists of a polyethylene (PE), a polypropylene (PP), an ethylene-vinyl acetate copolymer (EVA), an ionomer (IO), an ethylene-methyl methacrylate copolymer (EMMA), an ethylene-methacrylic acid copolymer (EMA) or any mixture thereof. 49.Film according to one of numbers 25 to 47, wherein the film is multi-layered; wherein the film has at least one outer layer and / or one inner layer, preferably an outer layer, which contains or consists of a third polymer (PM3), preferably a third polyolefin (PO3); wherein the third polymer (PM3), preferably the third polyolefin (PO3), is preferably not sealable, more preferably not heat sealable, in particular has a sealing temperature which is higher than the sealing temperature of the second polymer (PM2), preferably the second polyolefin (PO2), and preferably contains or consists of a polyethylene (PE) and / or a polypropylene (PP) or any mixture thereof.

[0245] 50. Film according to one of numbers 25 to 49, wherein the film has an outer layer consisting of the first polypropylene (PPI); wherein the film has an inner layer consisting of a second polypropylene (PP2) or a third polypropylene (PP3) or a second polyethylene (PE2); wherein the second polypropylene (PP2) has a heat deflection temperature of less than 75°C, preferably less than 65°C, in particular less than 55°C, measured according to ASTM D648-18; wherein the third polypropylene (PP3) has a heat deflection temperature lower than the heat deflection temperature of the first polypropylene (PPI) and higher than the heat deflection temperature of the second polypropylene (PP2), each measured according to ASTM D648-18; and wherein the second polyethylene (PE2) has a density of less than 0.940 g / cm 3 , preferably less than 0.920 g / cm 3 , and greater than 0.870 g / cm 3, measured according to DIN EN ISO 1183-1:2019-09.

[0246] 51. Film according to one of numbers 25 to 50, wherein the film is multilayered; wherein the film contains ethylene-vinyl alcohol copolymer (EVOH) in a mass fraction of less than 5%, based on the total mass of the film; and wherein the film has at least one layer consisting of ethylene-vinyl alcohol copolymer (EVOH); or wherein the film is multilayered; wherein the film contains polyvinyl alcohol copolymer (PVOH) in a mass fraction of less than 5%, based on the total mass of the film; and wherein the film has at least one layer consisting of polyvinyl alcohol copolymer (PVOH).Use of a first polypropylene (PPI) for a single- or multi-layer, extruded, simultaneously biaxially stretched and heat-set film, preferably for a film according to one of numbers 25 to 51, or for the production thereof; wherein the film contains the first polypropylene (PPI) in a mass fraction of greater than 30%, preferably greater than 40%, preferably greater than 50%, preferably greater than 65%, preferably greater than 80%, in particular greater than 90%, based on the total mass of the film; wherein the first polypropylene (PPI) has a heat deflection temperature of greater than 75°C, preferably greater than 85°C, in particular greater than 95°C, measured according to ASTM D648-18; and wherein the film does not contain any of the following polymers selected from the group consisting of polyethylene terephthalate (PET), polyvinylidene chloride (PVDC) and polyamide (PA).Use of a film according to one of numbers 25 to 51 as a ready-to-use packaging material for foodstuffs or for producing a ready-to-use packaging material for foodstuffs by laminating a further polymer layer or several further polymer layers or a package of several polymer layers.

Claims

Claims 1. A process for producing a single- or multi-layer film, the process comprising at least the following steps: a step of extruding a layer or co-extruding a plurality of layers to obtain an extruded film; a step of simultaneously biaxially stretching the extruded film; and a step of heat-setting the stretched film; wherein the film contains a first polypropylene (PPI); wherein the first polypropylene (PPI) has a heat deflection temperature of greater than 75°C, preferably greater than 85°C, in particular greater than 95°C, measured according to ASTM D648-18; wherein the film contains the first polypropylene (PPI) in a mass fraction of greater than 30%, preferably greater than 40%, preferably greater than 50%, preferably greater than 65%, preferably greater than 80%, in particular greater than 90%, based on the total mass of the film;wherein the film does not contain any of the following polymers selected from the group consisting of polyethylene terephthalate (PET), polyvinylidene chloride (PVDC) and polyamide (PA); wherein the stretch factor (VMD) in the machine direction (MD) is greater than the stretch factor (VTD) in the transverse direction (TD); wherein the film has a second temperature (T2) of greater than 120°C and less than 180°C, preferably greater than 130°C and less than 170°C, in particular greater than 140°C and less than 160°C, during stretching; and wherein the film has a third temperature (T3) of greater than 60°C and less than 200°C, preferably greater than 80°C and less than 180°C, in particular greater than 100°C and less than 160°C, during heat-setting.

2. The method according to claim 1, wherein the film is cooled after extrusion within a period of 0.01 to 1 second, preferably from 0.05 to 0.5 seconds, in particular from 0.07 to 0.3 seconds, to a first temperature (TI) of below 20°C, preferably below 15°C, in particular below 10°C; wherein the film is heated from the first temperature (TI) to the second temperature (T2) before stretching within a period of 1 to 18 seconds, preferably 1.5 to 12 seconds, in particular 2 to 9 seconds; wherein a time period (At) (= t2 - t1) between a first time (t1) at which the film reaches the second temperature (T2) and a second time (t2) at which the stretching of the film begins is 0.05 to 6 seconds, preferably 0.1 to 3 seconds, in particular 0.3 to 1.5 seconds;wherein a residence time during the heat-setting (= duration of the heat-setting of the film), during which the film has the third temperature (T3), is greater than 1 second and less than 60 seconds, preferably greater than 2 seconds and less than 45 seconds, in particular greater than 3 seconds and less than 30 seconds; 3. The method according to claim 1 or 2, wherein a stretch factor (VMD) in the machine direction or longitudinal direction (MD) is greater than 5.0, preferably greater than 6.0, in particular greater than 7.0, and less than 8.0; wherein a stretch factor (VTD) in the transverse direction or transverse direction (TD) is greater than 4.0, preferably greater than 5.0, in particular greater than 6.0, and less than 7.0; wherein a residence time during the heat-setting (= duration of the heat-setting of the film), during which the film has the third temperature (T3), is greater than 2 seconds and less than 60 seconds, preferably greater than 3 seconds and less than 45 seconds, in particular greater than 4 seconds and less than 30 seconds.

4. The method according to any one of claims 1 to 3, wherein the method further comprises relaxing the film during heat-setting the film; wherein a relaxation factor (RMD) in the machine direction (MD) is greater than 0.00 and less than 0.10, preferably greater than 0.00 and less than 0.05, in particular greater than 0.00 and less than 0.03; wherein a relaxation factor (RTD) in the transverse direction (TD) is greater than 0.00 and less than 0.20, preferably greater than 0.00 and less than 0.10, in particular greater than 0.00 and less than 0.05; and wherein the relaxation factor (RTD) in the transverse direction (TD) is greater than the relaxation factor (RMD) in the machine direction (MD).

5. The method according to claim 4, wherein the film has the third temperature (T3) during the relaxation; and wherein a duration of the relaxation of the film, during which the film has the third temperature (T3), is greater than 2 seconds, preferably greater than 3 seconds, in particular greater than 4 seconds, and less than 45 seconds, preferably less than 30 seconds.

6. The method according to any one of claims 1 to 5, wherein the method further comprises cooling the film after stretching and before heat-setting; wherein the film is cooled after stretching within a period of 0.01 to 1 second, preferably 0.05 to 0.5 seconds, in particular 0.07 to 0.3 seconds, to a fourth temperature (T4) of below 50°C, preferably below 40°C, in particular below 30°C.

7. The method according to any one of claims 1 to 6, wherein the method does not comprise a step of laminating or extrusion-coating the film or components thereof, in particular layers of the film; and / or wherein the film is multilayered and the co-extrusion of the multilayered film is carried out in a single step.

8. A single- or multi-layer, extruded, simultaneously biaxially stretched and heat-set film, preferably produced by the process according to one of claims 1 to 7, wherein the film contains a first polypropylene (PPI); wherein the first polypropylene (PPI) has a heat deflection temperature of greater than 75°C, preferably greater than 85°C, in particular greater than 95°C, measured according to ASTM D648-18; wherein the first polypropylene (PPI) has a heat deflection temperature of greater than 75°C, preferably greater than 85°C, in particular greater than 95°C, measured according to ASTM D648-18; wherein the film contains the first polypropylene (PPI) in a mass fraction of greater than 30%, preferably greater than 40%, preferably greater than 50%, preferably greater than 65%, preferably greater than 80%, in particular greater than 90%, based on the total mass of the film;and wherein the film does not contain any of the following polymers selected from the group consisting of polyethylene terephthalate (PET), polyvinylidene chloride (PVDC) and polyamide (PA); 9. A film according to claim 8, wherein the film is not laminated.

10. The film according to claim 8 or 9, wherein the film is relaxed; wherein a residual stretch factor (RVMD) of the film in the machine direction (MD) is greater than 5.0 and less than 7.0, preferably greater than 5.5 and less than 7.0, in particular greater than 6.0 and less than 7.0; wherein a residual stretch factor (RVTD) of the film in the transverse direction (TD) is greater than 4.0 and less than 6.0, preferably greater than 4.5 and less than 6.0, in particular greater than 5.0 and less than 6.0; and wherein the residual stretch factor (RVMD) of the film in the machine direction (MD) is greater than the residual stretch factor (RVTD) in the transverse direction (TD); or wherein the film is relaxed; wherein a residual stretch factor (RVMD) of the film in the machine direction (MD) is greater than 5.0 and less than 7.0, and a residual stretch factor (RVTD) of the film in the transverse direction (TD) is greater than 4.0 and less than 6.0; and wherein the residual stretch factor (RVMD) of the film in the machine direction (MD) is greater than the residual stretch factor (RVTD) in the transverse direction (TD); or wherein the film is relaxed;wherein a residual stretch factor (RVMD) of the film in the machine direction (MD) is greater than 5.5 and less than 7.0, and a residual stretch factor (RVTD) of the film in the transverse direction (TD) is greater than 4.5 and less than 6.0; and wherein the residual stretch factor (RVMD) of the film in the machine direction (MD) is greater than the residual stretch factor (RVTD) in the transverse direction (TD); or wherein the film is relaxed; wherein a residual stretch factor (RVMD) of the film in the machine direction (MD) is greater than 6.0 and less than 7.0, and a residual stretch factor (RVTD) of the film in the transverse direction (TD) is greater than 5.0 and less than 6.0; and wherein the residual stretch factor (RVMD) of the film in the machine direction (MD) is greater than the residual stretch factor (RVTD) in the transverse direction (TD); 11. Film according to claim 8 or 9, wherein the film is relaxed and the first polypropylene (PPI) has a heat distortion temperature of greater than 85 °C and preferably a density of greater than 0.899 g / cm 3 and less than 0.920 g / cm 3 wherein a residual stretch factor (RVMD) of the film in the machine direction (MD) is greater than 3.6 and less than 3.9, preferably greater than 4.1 and less than 4.4, in particular greater than 5.0 and less than 5.4; wherein a residual stretch factor (RVTD) of the film in the transverse direction (TD) is greater than 2.8 and less than 3.4, preferably greater than 3.6 and less than 3.9, in particular greater than 4.1 and less than 4.4; and wherein the residual stretch factor (RVMD) of the film in the machine direction (MD) is greater than the residual stretch factor (RVTD) in the transverse direction (TD); or wherein the film is relaxed and the first polypropylene (PPI) has a heat distortion temperature of greater than 85°C and preferably a density of greater than 0.899 g / cm 3 and less than 0.920 g / cm 3wherein a residual stretch factor (RVMD) of the film in the machine direction (MD) is greater than 3.6 and less than 3.9, and a residual stretch factor (RVTD) of the film in the transverse direction (TD) is greater than 2.8 and less than 3.4; and wherein the residual stretch factor (RVMD) of the film in the machine direction (MD) is greater than the residual stretch factor (RVTD) in the transverse direction (TD); or wherein the film is relaxed and the first polypropylene (PPI) has a heat distortion temperature of greater than 85 °C and preferably a density of greater than 0.899 g / cm 3 and less than 0.920 g / cm 3 wherein a residual stretch factor (RVMD) of the film in the machine direction (MD) is greater than 4.1 and less than 4.4, and a residual stretch factor (RVTD) of the film in the transverse direction (TD) is greater than 3.6 and less than 3.9; and wherein the residual stretch factor (RVMD) of the film in the machine direction (MD) is greater than the residual stretch factor (RVTD) in the transverse direction (TD); or wherein the film is relaxed and the first polypropylene (PPI) has a heat distortion temperature of greater than 85 °C and preferably a density of greater than 0.899 g / cm 3 and less than 0.920 g / cm 3 wherein a residual stretch factor (RVMD) of the film in the machine direction (MD) is greater than 5.0 and less than 5.4, and a residual stretch factor (RVTD) of the film in the transverse direction (TD) is greater than 4.1 and less than 4.4, and wherein the residual stretch factor (RVMD) of the film in the machine direction (MD) is greater than the residual stretch factor (RVTD) in the transverse direction (TD).

12. Film according to claim 8 or 9, wherein the film is relaxed and the first polypropylene (PPI) has a heat distortion temperature of greater than 75 °C and less than or equal to 85 °C and preferably a density of greater than 0.895 g / cm 3 and less than or equal to 0.899 g / cm 3wherein a residual stretch factor (RVMD) of the film in the machine direction (MD) is greater than 5.0 and less than 7.0, preferably greater than 5.5 and less than 7.0, in particular greater than 6.0 and less than 7.0; wherein a residual stretch factor (RVTD) of the film in the transverse direction (TD) is greater than 4.0 and less than 6.0, preferably greater than 4.5 and less than 6.0, in particular greater than 5.0 and less than 6.0; and wherein the residual stretch factor (RVMD) of the film in the machine direction (MD) is greater than the residual stretch factor (RVTD) in the transverse direction (TD); or wherein the film is relaxed and the first polypropylene (PPI) has a heat distortion temperature of greater than 75°C and less than or equal to 85°C and preferably a density of greater than 0.895 g / cm 3 and less than or equal to 0.899 g / cm 3wherein a residual stretch factor (RVMD) of the film in the machine direction (MD) is greater than 5.0 and less than 7.0, and a residual stretch factor (RVTD) of the film in the transverse direction (TD) is greater than 4.0 and less than 6.0; and wherein the residual stretch factor (RVMD) of the film in the machine direction (MD) is greater than the residual stretch factor (RVTD) in the transverse direction (TD); or wherein the film is relaxed and the first polypropylene (PPI) has a heat distortion temperature of greater than 75 °C and less than or equal to 85 °C and preferably a density of greater than 0.895 g / cm 3 and less than or equal to 0.899 g / cm 3wherein a residual stretch factor (RVMD) of the film in the machine direction (MD) is greater than 5.5 and less than 7.0, and a residual stretch factor (RVTD) of the film in the transverse direction (TD) is greater than 4.5 and less than 6.0; and wherein the residual stretch factor (RVMD) of the film in the machine direction (MD) is greater than the residual stretch factor (RVTD) in the transverse direction (TD); or wherein the film is relaxed and the first polypropylene (PPI) has a heat distortion temperature of greater than 75°C and less than or equal to 85°C and preferably a density of greater than 0.895 g / cm 3 and less than or equal to 0.899 g / cm 3wherein a residual stretch factor (RVMD) of the film in the machine direction (MD) is greater than 6.0 and less than 7.0, and a residual stretch factor (RVTD) of the film in the transverse direction (TD) is greater than 5.0 and less than 6.0; and wherein the residual stretch factor (RVMD) of the film in the machine direction (MD) is greater than the residual stretch factor (RVTD) in the transverse direction (TD).

13. A film according to any one of claims 8 to 12, wherein the film consists of a single layer consisting of the first polypropylene (PPI); or wherein the film consists of several, preferably two, three, four or five, layers, each consisting of the first polypropylene (PPI).

14. A film according to any one of claims 8 to 13, wherein the film is multi-layered; wherein the film has at least one outer layer and / or one inner layer, preferably an inner layer, which contains or consists of a second polymer (PM2), preferably a second polyolefin (PO2); wherein the second polymer (PM2), preferably the second polyolefin (PO2), is preferably sealable, in particular heat-sealable, and preferably contains or consists of a polyethylene (PE), a polypropylene (PP), an ethylene-vinyl acetate copolymer (EVA), an ionomer (IO), an ethylene-methyl methacrylate copolymer (EMMA), an ethylene-methacrylic acid copolymer (EMA) or any mixture thereof.

15. A film according to any one of claims 8 to 14, wherein the film is multi-layered; wherein the film has at least one outer layer and / or one inner layer, preferably an outer layer, which contains or consists of a third polymer (PM3), preferably a third polyolefin (PO3); wherein the third polymer (PM3), preferably the third polyolefin (PO3), is preferably not sealable, more preferably not heat sealable, in particular has a sealing temperature which is higher than the sealing temperature of the second polymer (PM2), preferably the second polyolefin (PO2), and preferably contains or consists of a polyethylene (PE) and / or a polypropylene (PP) or any mixture thereof.

16. Film according to one of claims 8 to 15, wherein the film has an outer layer consisting of the first polypropylene (PPI); wherein the film has an inner layer consisting of a second polypropylene (PP2) or a third polypropylene (PP3) or a second polyethylene (PE2); wherein the second polypropylene (PP2) has a heat deflection temperature of less than 75°C, preferably less than 65°C, in particular less than 55°C, measured according to ASTM D648-18; wherein the third polypropylene (PP3) has a heat deflection temperature lower than the heat deflection temperature of the first polypropylene (PPI) and greater than the heat distortion temperature of the second polypropylene (PP2), each measured according to ASTM D648-18; and wherein the second polyethylene (PE2) has a density of less than 0.940 g / cm 3 , preferably less than 0.920 g / cm 3 , and greater than 0.870 g / cm 3, measured according to DIN EN ISO 1183-1:2019-09.

17. A film according to any one of claims 8 to 16, wherein the film is multilayered; wherein the film contains ethylene-vinyl alcohol copolymer (EVOH) in a mass fraction of less than 5%, based on the total mass of the film; and wherein the film has at least one layer consisting of ethylene-vinyl alcohol copolymer (EVOH); or wherein the film is multilayered; wherein the film contains polyvinyl alcohol copolymer (PVOH) in a mass fraction of less than 5%, based on the total mass of the film; and wherein the film has at least one layer consisting of polyvinyl alcohol copolymer (PVOH).

18. Use of a first polypropylene (PPI) for a single- or multi-layer, extruded, simultaneously biaxially stretched and heat-set film, preferably for a film according to one of claims 8 to 17, or for the production thereof; wherein the film contains the first polypropylene (PPI) in a mass fraction of greater than 30%, preferably greater than 40%, preferably greater than 50%, preferably greater than 65%, preferably greater than 80%, in particular greater than 90%, based on the total mass of the film; wherein the first polypropylene (PPI) has a heat deflection temperature of greater than 75°C, preferably greater than 85°C, in particular greater than 95°C, measured according to ASTM D648-18; and wherein the film does not contain any of the following polymers selected from the group consisting of polyethylene terephthalate (PET), polyvinylidene chloride (PVDC) and polyamide (PA).

19. Use of a film according to any one of claims 8 to 17 as a ready-to-use packaging material for foodstuffs or for producing a ready-to-use packaging material for foodstuffs by laminating a further polymer layer or several further polymer layers or a package of several polymer layers.

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