Use of a single- or multi-layer film as a sliding film or preliner

Abstract

Use of a single- or multi-layer film as a sliding film (2) or preliner (1) in pipe rehabilitation using cured-in-place pipe (CIPP) lining technology for application to the inner wall of an underground pipe to be rehabilitated, preferably a sewer pipe (K), so that an insert hose (7) with a curable carrier material (8) can be slid through the pipe on the sliding film (2) or preliner (1) laid in the pipe, wherein the film (1; 2) comprises at least one layer (3) containing at least one thermoplastic olefin homo- or copolymer, optionally modified, characterized in that said layer (3) additionally contains at least one polyester.

Description

The invention relates to the use of a single- or multi-layered film as a sliding film or preliner in pipe rehabilitation using cured-in-place pipe (CIPP) lining technology for application to the inner wall of an underground pipe to be rehabilitated, preferably a sewer pipe, so that an insert hose with a curable carrier material can be slid through the pipe on the sliding film or preliner laid in the pipe, wherein the film comprises at least one layer containing a thermoplastic olefin homo- or copolymer, optionally modified. Such films have been known for a long time. Products made from polyethylene (PE), and especially low-density polyethylene (LDPE), include garbage bags, shrink films, and agricultural films. Numerous multilayer films are also known, which may have three, five, or seven layers, one or more of which contain PE or PP (polypropylene). US Patent 2007 / 0259142A1 describes a trough-forming package made of a thermoplastic multilayer film consisting of different layers, including two polyamide layers, an ethylene / vinyl alcohol copolymer layer, an oxygen barrier component, and a rigid or semi-rigid component. The latter component can be selected from a wide range of materials, including polypropylene, polyvinyl chloride, polystyrene, polyethylene terephthalate, polycarbonate, and others. US patent 2006 / 0286323A1 also discloses a multilayer packaging that includes a myoglobin colorant and an oxygen barrier in a meat-contacting layer. Another layer, designed as the outer layer, may contain polyolefins, polyamides, polyesters, polystyrene, or mixtures thereof. US Patent 2010 / 0043906A1 discloses an insulated high-temperature transport conduit for offshore deep water areas, which incorporates a high-temperature resistant thermoplastic that can be selected from a variety of chemical compounds, including mixtures thereof. Similar disclosures can be found in EP 2 508 927 A2, which relates to an optical waveguide with a protective lining, and WO 2010 / 015 872 A1, which describes a protective device for signal cables. Generally speaking, the range of applications for films containing olefin homo- or copolymers is very broad. One of these applications is the cured-in-place pipe (CIPP) lining method for trenchless sewer pipe rehabilitation. For example, in the fiberglass CIPP liner system with UV or steam curing, a thick-walled, high-density polyethylene (HDPE) film is inserted into the pipe to be rehabilitated. This film, usually in a semicircular cross-section, is placed against the inner wall of the pipe. A flexible liner (also called a CIPP liner or simply a liner) is then pulled into the pipe (pulling-in method), sliding over the liner film. This prevents damage to the liner from the inner pipe wall.Objects are avoided in the pipe; on the other hand, the friction between the liner and the sliding film is very low, facilitating the insertion of the liner. This function is similar to that of a shoehorn. Such a liner (pipe liner) in the fiberglass pipe liner system with UV or steam curing typically has an inner and an outer tube, between which a carrier material (e.g., fiberglass) is inserted, impregnated with reactive resin. Commercially available UP resins (polyester or unsaturated polyester resins), VE resins (vinyl ester resins), or EP resins (epoxy resins) are used as reactive resins. The resins are cured using photoinitiators, for example, in the case of UP or VE resins. Curing can also be thermal. The liner is inflated in the pipe until it reaches the inner pipe wall.The inner film of the liner is applied to the sliding foil, allowing the resin to cure – for example, using UV light from a UV light source slowly pulled through the pipe. Finally, the inner foil of the liner is peeled off and removed. The layer with the carrier material is then exposed to the substances to be conducted through the pipe. Instead of the slip sheet described above, a preliner (also called a preliner film) is often inserted into the pipe to be rehabilitated, particularly in the case of synthetic fiber pipe liner systems with hot water or steam curing. A preliner, usually made of high-density polyethylene (HDPE), is a thick-walled film that completely lines the pipe and also prevents direct contact between the pipe liner and the inner pipe wall. The preliner is placed directly against the inner wall of the pipe. The pipe liner is then pulled into the pipe (pulling method) or inverted (inversion method). The preliner prevents, for example, the resin of the pipe liner from adhering to the pipe wall and from contact between the uncured resin and dirt and water. Furthermore, the preliner film also prevents resin from leaking out of the pipe rehabilitation system and from contaminating the soil and groundwater.The preliner film also protects the inlets from excess resin penetrating, preventing resin plugs and blockages from forming. During the insertion process, a preliner performs a similar function to the sliding films described above for the pipe liner being inserted, reducing friction. In this case, low coefficients of friction between the sliding film or preliner and the outer film of the pipe liner are crucial. This prevents the liner from being damaged by the pipe's inner wall or objects inside the pipe during insertion. Furthermore, the very low friction between the pipe liner and the sliding film or preliner facilitates insertion. The preliner can therefore also be described as a sliding sleeve. One disadvantage of the aforementioned HDPE film used as a sliding film or preliner is its required thickness of approximately 500 µm to 800 µm or more, and consequently the large quantity needed to achieve reasonable mechanical stability and strength. Otherwise, the sliding film or preliner would crack due to the mechanical stresses within the pipe, particularly those caused by sharp or rough irregularities, and would then no longer be able to fulfill its purpose. The well-known HDPE film also exhibits very high elasticity, which can reach up to 200%. This can easily create an "accordion effect," meaning the film contracts when the tensile force is removed. If, during the relative movement of the liner sleeve to the sliding film or preliner, the latter is stretched and the tensile force exerted by the liner sleeve eventually decreases, the sliding film or preliner can contract again, creating the risk of a blockage in the sewer pipe being rehabilitated. This blockage can be caused by the sliding film or preliner and the liner sleeve. On the other hand, HDPE reaches its maximum force even under sudden dynamic stretching. If further stretching is applied, for example, abruptly with even greater force, the film begins to flow irreversibly before tearing. This creates the risk of the liner being pulled in uncontrollably, potentially becoming stuck in the pipe and unable to be easily removed or properly reinstalled. Furthermore, the PE films used in the prior art to date, in particular HDPE films, are insufficient with regard to their mechanical properties such as (further) tear resistance, tear strength, impact resistance or puncture resistance due to material properties. Finally, the PE films used as preliner films in the prior art also do not have a barrier effect against resin components such as styrene. The object of the present invention is to provide a film for use as a sliding film or preliner in pipe rehabilitation which meets high requirements regarding its stability while maintaining a relatively low thickness. This problem is solved by the foil according to claim 1. The advantages of the invention are particularly evident in the fact that films used according to the invention exhibit good mechanical properties such as robustness, resistance, puncture resistance, good inherent stiffness, low elongation and good sliding properties. It was surprisingly discovered that it is possible to homogenize and make compatible two completely different, inherently incompatible polymers, such as A-PET and PE, during extrusion. The outstanding mechanical properties achieved with the film used according to the invention were particularly surprising. Due to these properties, the films are ideally suited for use as sliding films or as preliners in trenchless sewer rehabilitation. When the film is used as such a sliding film or preliner (sliding tube), it is on the one hand very resistant, and on the other hand the insert tube can be pulled through the pipe with only slight friction. The coefficient of friction (COF) against another film with a PE outer layer is, for example, between 0.05 and 0.5, preferably between 0.1 and 0.3. It has also been shown that the tear resistance and propagation strength of films used according to the invention are very high; that is, the films are practically tear-proof, or if they are torn, the force required to tear further is very high. Furthermore, they exhibit only very low to negligible elongation in the machine direction (md), i.e., in the direction in which the films are manufactured. In other words, a high force in the machine direction is required to generate any elongation at all. Thus, the aforementioned "accordion effect" can be prevented. In its application as a sliding film or preliner, it is advantageous in a particular embodiment that the film has no sharp corners or edges to avoid damaging the insert tube. Preferably, it is cut with sharp knives without the film fraying during this process. The cutting surface of the knife or an inserted cutting wire is preferably heated to a high temperature, as this allows the sharp edges and corners to be smoothed and blunted by melting the polymers at these points. It should be noted that olefin homo- or copolymers within the meaning of the present invention are thermoplastic polymers of α,β-unsaturated olefins with two to six carbon atoms, such as polyethylene (PE, in particular LDPE or HDPE), polypropylene (PP), polybutylene (PB), polyisobutylene (PI), or mixtures of at least two of the aforementioned polymers. "LDPE" refers to low-density polyethylene, which has a density in the range of 0.86–0.93 g / cm³ and is characterized by a high degree of molecular branching. "HDPE" refers to high-density polyethylene, which has only a low degree of molecular branching, with a density ranging from 0.94–0.97 g / cm³. According to a preferred embodiment, said at least one layer contains more than 50 wt.% of thermoplastic olefin homo- or copolymer and 0.1 to 50 wt.% of polyester. According to an alternative, particularly preferred embodiment of the invention, said at least one layer comprises more than 50 wt.% polyester and 0.1 to 50 wt.% thermoplastic olefin homo- or copolymer. Advantageously, said layer contains at least one layer of between 10 wt.% and 35 wt.% thermoplastic olefin homo- or copolymer. Polyester in amorphous form has proven to be particularly suitable in the said at least one layer of the film used according to the invention, with amorphous polyethylene terephthalate (A-PET) being particularly preferred. The material used is preferably commercially available A-PET. This can also be regenerated or recycled. Additionally, shredded material from edge trimmings, etc., can be used. Commercially available A-PET is readily available, for example under the names Wellman PermaClear® from the US company DAK Americas, Novapet® from Novapet SA, Spain, or Texpet R from Texplast GmbH, Wolfen, or SABIC® PET. According to an advantageous embodiment, the at least one polyester, in particular in the form of A-PET, is contained in the said layer to a weight of more than 25 wt.%, preferably more than 40 wt.% and particularly preferably more than 50 wt.%, in particular more than 65 wt.%. The addition of polyolefin components in the form of thermoplastic olefin homo- and / or copolymer to A-PET, or their presence, leads to a significant improvement in toughness and tear resistance. Furthermore, it has proven advantageous if the olefin homo- or copolymer in said layer has a glass transition temperature Tg in the range of -90°C to +110°C, particularly from -80°C to +40°C. This reduces excessive stiffness of the polyester, especially A-PET, thereby decreasing the film's modulus of elasticity. The olefin homo- or copolymer is preferably polyethylene (PE). This is preferably used in the form of high-density polyethylene (HDPE). LDPE and / or LLDPE (linear low-density polyethylene) are also advantageously suitable. Furthermore, polyolefins, especially polyethylenes polymerized using metallocene catalysts (mPE), such as mLDPE (metallocene LDPE) and mLLDPE (metallocene LLDPE), are also suitable. Polyethylene is classified into different categories, mainly with regard to its density and branching. Its mechanical properties depend significantly on variables such as the length and type of branching, the crystal structure, and the molecular weight. The most commonly sold polyethylenes are HDPE, LLDPE, and LDPE.Specifically, the order is as follows (English spelling of the polymers): Ultra-high Molecular Weight Polyethylene (UHMWPE), Ultra Low Molecular Weight Polyethylene (ULMWPE or PE-WAX), High Molecular Weight Polyethylene (HMWPE), High Density Polyethylene (HDPE), High Density Cross-linked Polyethylene (HDXLPE), Cross-linked Polyethylene (PEX or XLPE), Medium-density Polyethylene (MDPE), Linear Low Density Polyethylene (LLDPE), Low Density Polyethylene (LDPE), Very Low Density Polyethylene (VLDPE), Chlorinated Polyethylene (CPE). VLDPE (very low-density polyethylene) is defined by a density range of 0.880–0.915 g / cm³. It is essentially a linear polymer with a high proportion of short side chains, typically produced by linear copolymerization of ethylene with short-chain alpha olefins (e.g., 1-butene, 1-hexene, and 1-octene). VLDPE is very often produced using metallocene catalysts because these catalysts allow for the incorporation of more co-monomers. According to another advantageous alternative, polypropylene (PP) is used as an olefin homo or copolymer. Mixtures of different olefin homo- or copolymers, including those listed above, in said at least one layer according to claim 1 are readily possible. Hostalen® from LyondellBasell Industries, for example, may be used as an HDPE material in the inventive mixture of said layer according to claim 1. The at least one olefin homo- or copolymer in the at least one said layer according to claim 1 can be configured as an adhesion promoter or be provided or modified with adhesion-promoting functional groups. Such an adhesion promoter or an olefin homo- or copolymer with an adhesion-promoting function contains corresponding functional groups, for example, epoxy groups, peroxide groups, ketone groups, aldehyde groups, (carbonic) acid groups, amine or amide groups, acid anhydride groups, and / or hydroxyl groups. Such functionalization can improve the compatibility of the polymers polyester and polyolefin, which are generally considered incompatible. Modification with at least one organic acid or at least one organic anhydride, preferably a cyclic organic anhydride, is particularly advantageous. Modification with maleic anhydride groups is especially preferred, wherein these groups act as adhesion promoters between the at least one polyester and the at least one olefin homo- or copolymer. It is also possible that, in addition to modified polyolefin, unmodified polyolefin is also contained in the said at least one layer according to claim 1. It should be emphasized that, surprisingly, extrusion of polyester and polyolefin to produce the film used according to the invention was possible even without appropriate compatibility modification. The chemically different materials were successfully homogenized using a conventional extruder. In other words, the mixture in question can be extruded even without functionalization. However, according to the variant described above, the aforementioned functionalized polymers, such as compatibilizers or conventional adhesion promoters, can also be used. In a preferred embodiment, these are added in small quantities of 0.1 to 10 wt.% to the olefin homo- or copolymer in the at least one of the aforementioned layers. Although not strictly necessary, the various components A-PET and polyolefin can be pre-mixed by compounding to further improve the homogeneity of the mixture. The film used according to the invention preferably has a thickness of 20 to 2000 µm, more preferably 50 to 1500 µm, and particularly preferably 100 to 1000 µm, especially 200 to 900 µm. The latter thickness range has proven particularly advantageous for use as a sliding film or preliner. However, it should be emphasized that the term "foil" does not imply a maximum thickness. According to an advantageous embodiment, the film used according to the invention has at least one independent barrier layer. Such a barrier layer is preferably based on ethylene vinyl alcohol (EVOH) or polyamide (PA), or both. Advantageously, the barrier layer acts as a barrier against monomers such as styrene and / or against oils and greases. The chemical compound that performs the barrier function (e.g., PA) can be present in the barrier layer up to 100%. Alternatively or additionally, the film used according to the invention can advantageously have a separate layer containing at least one chemical compound acting as a barrier against the passage of chemical substances, preferably against monomers (e.g., styrene), and / or at least one chemical compound acting as a barrier against UV and, advantageously, visible light. The use of polyamide as the chemical compound for the barrier effect is advantageous. To achieve a UV light barrier, a wide variety of compounds can be used—alone or in combination—to absorb and / or reflect UV radiation and, advantageously, also visible radiation (at least a part of the visible spectrum, preferably short-wavelength visible light).Preferably, UV radiation in the wavelength range of 200 to 400 nm and visible light radiation in the wavelength range of 400 to 800 nm are absorbed and / or reflected, preferably to a degree exceeding 90%. In particular, the film used according to the invention largely or completely blocks transmission in the wavelength range of 300 to 500 nm, preferably from 350 to 450 nm. Organic and / or inorganic color pigments, dyes, or compounds known to those skilled in the art can be used for this purpose (see, for example, DE 10 2009 041 841 A1). In an advantageous embodiment, the film used according to the invention contains at least one independent layer with at least one chemical compound acting as a mechanical barrier as well as at least one chemical compound to achieve a UV barrier and a barrier against areas of visible light. Depending on the application, one or more of the following polymers and substances may be present in the polyester, preferably in the form of A-PET, or added to the layer containing the polyester, with these additives being added up to a maximum of 15 wt%: polystyrene (PS); polyhalides, such as PVC and / or polyvinylidene chloride (PVdC); polyamide (PA); polyvinyl alcohol (PVOH or PVAL); ethylene vinyl alcohol copolymer (EVOH); adhesion promoters; ethylene vinyl acetate (EVAc); one or more ionomers; one or more poly(meth)acrylates; ethylene-containing poly(meth)acrylates; polyvinyl acetate (PVAc); polycarbonate (PC); polyacrylonitrile (PAN); other polyesters such as polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), polylactic acid (PLA) and / or polyhydroxyalkanoates (PHA); one or more ethylene acrylic acid copolymers (EAA); polyvinyl butyral (PVB); polyvinyl acetal; Cellulose acetate (CA); Cellulose acetobutyrate (CAB); Polysaccharides; Starch; Cyclic olefin copolymer (COC). To improve film properties, the following components or additives can be used during extrusion in one or more layers, with these components or additives being added at a maximum weight of 15%. Examples of additives include optical brighteners, thermal stabilizers, antioxidants, oxygen scavengers, lubricants, spacers (e.g., silica particles, SAS), slip / antiblocking agents, colors, pigments, foaming agents, antistatic agents, processing aids, lubricating agents, flame retardants, impact modifiers, impact improvers, anti-hydrolysis agents, UV absorbers, UV protectants, stabilizers, anti-fog additives, waxes, wax additives, release agents, sealing or peel additives, nucleating agents, compatibilizers, flow agents, melt strength enhancers, molecular weight increasers, crosslinkers, and plasticizers. The film used according to the invention can have a mono- or multi-layer structure. In the latter case, intermediate and / or cover layers (outer layer) can be provided in addition to the aforementioned at least one layer, comprising at least one thermoplastic olefin homo- or copolymer and at least one polyester. If the film used according to the invention has its own cover or outer layer (i.e., not identical to the aforementioned layer according to claim 1) on one or both sides, such an outer layer can, for example, be a pure A-PET outer layer, generally a polyester layer, or a pure HDPE outer layer, generally a polyolefin layer. Both outer layers can also be polyester layers. Likewise, mixtures of polyester and polyolefin are possible in one or both outer layers.It is of course also possible that a pure polyester layer is provided on one outer surface and a pure polyolefin layer on the other outer surface, while the said composite layer according to claim 1, which contains at least one thermoplastic olefin homo- or copolymer and at least one polyester, is arranged between these outer layers. One or more intermediate layers are possible in any case. The films used according to the invention can be produced in various ways. A preferred method is extrusion or coextrusion, for example by blown film extrusion or cast extrusion. One possible coextrusion process is the chill-roll process (wide-slot die technology). Furthermore, individual layers as well as all layers of the film used according to the invention can be formed by extrusion, in particular by blown film extrusion and / or flat film extrusion, especially blown film co-extrusion and / or flat film co-extrusion. The flat film co-extrusion process has proven to be particularly suitable. Extrusion coating is also possible, as is a smoothing process. Furthermore, lamination techniques can be used. The film used according to the invention can be laminated with other films to obtain a film combination, for example, by thermal lamination, extrusion lamination, or adhesive lamination. According to a corresponding advantageous embodiment, lamination with a film that corresponds to the material of the outer film of an insert tube as described above is recommended. An advantageous base for the laminating film is a polyolefin, with a PE base being preferred. In the film used as a sliding film or preliner according to the invention, a PE base for the laminating film is preferred in one embodiment, since during the exothermic curing of the reactive resins serving as carrier material in the liner tube, the temperature increase due to initiation with UV light (or, for example, hot water or steam as alternative sources for resin curing) also allows the sliding film or preliner – containing at least one thermoplastic olefin homo- or copolymer – to bond to the (cured) liner tube. This significantly increases the stability of the liner tube, particularly after curing, which contributes to improving the strength of the pipe rehabilitated with the pipe liner. Alternatively or additionally, a film combination comprising a film used according to the invention and at least one additional, preferably laminated, film includes a light-protective film as such an additional film. This light-protective film is preferably a UV light-absorbing and / or reflecting film, and advantageously also visible radiation (at least a part of the visible spectrum, advantageously short-wavelength visible light). Preferably, the UV radiation in the wavelength range of 200 to 400 nm and the visible light rays in the wavelength range of 400 to 800 nm are at least partially absorbed and / or reflected, preferably to more than 90% and particularly preferably to more than 99%. In particular, the film used according to the invention largely to almost completely blocks transmission in the wavelength range of 300 to 500 nm, preferably from 350 to 450 nm.Organic and / or inorganic color pigments, dyes, or compounds known to those skilled in the art (e.g., DE 10 2009 041 841 A1) may be used for this purpose. The UV and, if applicable, light-protective film can therefore be completely opaque, or it can be transparent or at least contact-transparent. Such a UV and, if applicable, light protection film is preferably laminated to the outer surface of the film facing the resin-impregnated carrier material when used as a sliding film or as a preliner, and advantageously borders the outer film of the insert tube. In such a laminated UV and, optionally, light-protective film, chemical compounds can also be included—according to a particularly preferred embodiment—that act as a barrier against, in particular, monomers, resins, oils, greases, gases, etc. Reference is made to the above descriptions regarding the integration of a barrier layer in the film itself, as used in the invention. The corresponding chemical compounds acting as barriers can accordingly be contained in the laminated film. A film with such a barrier layer can also be laminated onto a film used in the invention according to claim 1, either as an alternative or in addition to the UV and, optionally, light-protective film. As an alternative to using the film according to the invention as a pure sliding film (approximately semicircular in cross-section) or as a pure preliner (sliding sleeve) in trenchless sewer rehabilitation for use with a conventional pipe liner, the aforementioned film combination consisting of said film as a preliner (sliding sleeve) and advantageously laminated UV and, if applicable, light protection film – optionally with at least one chemical compound acting as a barrier (e.g., EVOH, PA, etc.) – can be used as an outer sleeve (also called outer sleeve) for a pipe liner system. In this case, the commonly used pipe liner, consisting at least of an inner film (inner film), a resin-impregnated carrier system, and an outer film (outer film), is modified by laminating the outer film (UV and, if applicable, light protection film) to the preliner (sliding sleeve). The "slimmed-down" pipe liner then no longer includes the outer sleeve.the outer film (outer foil), but only the resin-impregnated carrier system and the inner tubular film (as well as any other films or layers). In a particularly preferred embodiment, the integrated anti-slip film or combination film of an anti-slip film and a UV-protective film, including a barrier, can also only partially constitute the outer system of a pipe liner. For example, an anti-slip film is laminated with a UV and light-protective film that has a barrier against monomers such as styrene, with this combination film forming only the lower part of the outer film of the pipe liner (e.g., a lower half-shell). The upper part of the outer system, which is a flexible UV and light-protective film with a styrene barrier (without being laminated with the anti-slip film), is then joined—for example, by sealing—to the lower anti-slip film or the lower outer film to form a tube.In this process, the longitudinal edges of the unlaminated part of the outer film, i.e., the upper part of the outer system, are connected, preferably sealed, to the longitudinal edges of the open sliding film or to the part of the outer film laminated onto the sliding film. The upper and lower parts of the outer film preferably have the same layer structure and composition, although their layer thicknesses and overall thicknesses may differ. Figuratively speaking, the liner consists of a more rigid and mechanically very stable and robust lower half-shell, which is connected to a flexible, stretchable upper half-shell by sealing. This resulting tubular outer membrane system protects the inner resin from UV and light radiation, as well as from drying out, since it creates a comprehensive barrier against monomers such as styrene. Such a liner-outer membrane system is very advantageous because the significantly more stable lower section protects the liner from damage during insertion into the sewer being rehabilitated, while the more flexible upper section makes the liner much more stretchable, which facilitates its installation in the sewer. According to an alternative design, a sliding film, essentially semicircular in cross-section, is laminated with a tubular UV and light protection film, which in turn provides a barrier against monomers such as styrene. The lower part of this combination film thus forms, for example, a lower half-shell, while the upper part is formed by the other, unlaminated half of the tubular UV and light protection film. Here, the UV and light protection film is tubular in shape and not – in cross-section – divided into two parts, so that a sealing system as previously described is unnecessary. According to another embodiment of the invention, the entire pipe liner (inner hose, resin-impregnated carrier material, outer hose) is connected to a preliner (sliding hose) which comprises the layer according to the invention, so that this assembly as a whole is introduced into a pipe to be rehabilitated. The preliner (sliding tube) can also be laminated in the form of a flat film with a UV and light protection film, which preferably also has a barrier against monomers and oils such as styrene or gases and is likewise in the form of a flat film, in order to then be sealed or welded to form a tube. The film used in the invention can also be stretched or embossed afterwards. Printing is also possible. The structuring of the film surface can also be achieved by pouring it onto a suitably structured roller. Preferably, the film surface is roughened by adding spacers (antiblocking agents), for example by applying a batch of coarser particles with a diameter of 0.01 to 10 µm. For example, silica particles are used for this purpose in at least one of the outer layers. This prevents adhesion between the sliding film or preliner and the insert tube. The film can also be coated with a powder or granules on the surface(s). Talc is preferably used for this purpose. In the aforementioned context, it should also be noted that the coefficient of friction of the sliding film or preliner against the outer film of the liner, which is inserted into the sewer for rehabilitation using the sliding film or preliner, is preferably low. According to an advantageous embodiment in this respect, a reduction of the coefficient of friction (COF) can be achieved with wax additives, for example ethylene bis-stearamide (EBS), erucamide (ESA), etc., as well as with release agents. These wax additives or release agents are preferably applied to the surface of the sliding film facing the outer film of the liner. The film used according to the invention can also be foamed or contain at least one foamed layer. The layer according to the invention, for example, comprising a mixture of PE and A-PET, can also be foamed, which is likewise a preferred embodiment. Furthermore, it is advantageously possible to laminate the film used according to the invention with a non-woven material, textile, needle felt, synthetic fibers, or nonwoven fabric. In particular, the lamination is carried out with a material absorbent for liquids and resins. Such lamination of the film used according to the invention, which additionally has a UV and light protection film with or without a barrier, with a non-woven material is also possible. However, it is particularly preferred that the film used according to the invention be laminated against a UV and light protection film, which in turn has already been laminated with a non-woven material. The lamination with the film used according to the invention against the UV and light protection film is preferably carried out on the side of the UV and light protection film not laminated with non-woven material. Thus, the side laminated with a non-woven material (here, the UV and light protection film including the barrier) can be exposed.barrier) are still available for connection with the reactive resin. Further processing options include combining the film used according to the invention with a "laid-on" or knitted fabric, e.g., a plastic mesh. Alternatively, this "laid-on" or knitted fabric can be incorporated into the film for the purpose of further reinforcement. The figures schematically illustrate various embodiments of the invention. They show: Fig. 1 a sewer pipe to be rehabilitated with a preliner (sliding sleeve), in cross-section; Fig. 2 a sewer pipe to be rehabilitated with a sliding film, in cross-section; Fig. 3 a cross-section through the preliner or the sliding film according to Fig. 1 or Fig. 2, respectively; Fig. 4 a sewer pipe to be rehabilitated with a preliner (sliding sleeve) with a laminated UV protection film, in cross-section; Fig. 5 a cross-section through the preliner and the laminated UV protection film, in cross-section; Fig. 6 a sewer pipe to be rehabilitated with a preliner and a pipe liner, in cross-section; Fig. 7 a sewer pipe to be rehabilitated with a sliding film and a first, lower outer sleeve laminated onto the sliding film, as well as a second, upper outer sleeve sealed to this assembly, in cross-section; and Fig. 8, Fig. 8a, Fig.8b a schematic cross-section through a tray, especially for food, and two enlarged detail views of two different film constructions. Figure 1 shows a cross-section of a sewer pipe K to be rehabilitated, into which a preliner 1 (sliding sleeve) according to the invention has been inserted. A sliding film 2, which is substantially semicircular in cross-section, is shown in Figure 2; it is applied accordingly to the lower semicircular shell of the sewer pipe K. The preliner 1 according to Figure 1 and the sliding film 2 according to Figure 2 have a layer 3 with the inventive mixture of at least one thermoplastic olefin homopolymer or copolymer, optionally modified, and at least one polyester (see claim 1). They are mechanically resistant and also have low friction to allow the insertion of a pipe liner. Figure 3 shows a cross-sectional view of a possible three-layer structure of the preliner 1 according to Figure 1 and the sliding film 2 according to Figure 2. Here, the aforementioned layer 3 with the aforementioned mixture is arranged between two outer layers 4 and 5, both of which contain 100% polyester, e.g., A-PET (see also corresponding Example 1 below). In a variant not shown, at least one independent barrier layer against the passage of gases and / or chemical substances, preferably based on ethylene vinyl alcohol (EVOH) or polyamide (PA), or both, and more preferably each consisting of 100% of these compounds, can be provided in addition to layer 3 (and possibly further layers).This or another layer may also contain at least one chemical compound that acts as a barrier against UV light and visible light, so that transmission of radiation in the wavelength range of 350 to 450 nm is at least largely prevented. Figure 4 shows that a film 6 is laminated onto the preliner 1 according to Figure 1, or that such a film has been formed by coextrusion. In this case, the additional film 6 is designed as a UV protection film with a barrier function against, for example, styrene. As the more detailed cross-section according to Figure 5 shows, the film 6 laminated onto the preliner 1 has a five-layer structure, for example, with the layer sequence polyethylene (6a) / HV (6b) / polyamide (6c) / HV (6d) / polyethylene (6e). In this case, this film 6 corresponds to an outer tubular film which—unlike in the prior art—is not connected to a tubular liner, but to the preliner 1. According to the prior art, such a tubular liner in its simplest form typically comprises an inner tube or a tubular inner film, a carrier system with UV-curable resin, and an outer tube or a tubular outer film.In this case, however, the outer tube 6 forms a film composite with the preliner 1. The resulting hose liner then expediently no longer has an outer tube. According to an alternative (not shown), another film (or several films), for example a separate or additional UV protection film, is laminated between the preliner 1 and the additional outer film (outer film) 6. Such a composite can also be produced by coextrusion. Figure 6 shows a complete system of a sewer pipe K to be rehabilitated, into which a preliner 1 has been inserted. The outer liner 6 can either be connected to the preliner 1 (see Figure 4) or be part of the – then constructed as known – cured-in-place pipe (CIPP) liner 7, which then comprises an inner liner 9, a resin carrier system 8, and the aforementioned outer liner 6. According to another alternative, the preliner 1 and the entire CIPP liner 7 can also form a single unit that is inserted into the sewer pipe K. The tubular preliner 1 with a laminated additional film (above: the outer film 6) can be obtained by extrusion lamination or by sealing the laminated film composite. Such a composite structure is particularly preferably produced by coextrusion. Figure 7 shows a variant in which a sliding film 2 – which, when installed in the channel, has a substantially hemispherical cross-section – is laminated with an outer film 6' designed as a UV and light protection film including a styrene barrier. When installed in the channel, this outer film 6' also assumes a hemispherical cross-section. This outer film 6' forms the lower part of the outer system of a pipe liner 7. The upper part of the outer system is formed by another outer film 6'', which is also designed as a flexible UV and light protection film with a styrene barrier (but is not laminated with the sliding film 2). The two outer films 6', 6'', which preferably both have the same layer structure and composition, are sealed together at the sealing points 10 running in the longitudinal direction of the pipe (perpendicular to the plane of the drawing) to form a single pipe.Alternatively, the upper outer film 6'' can be sealed with the sliding film 2. The remaining part of the pipe liner 7, separate from the two semicircular outer films 6', 6'', consists in this case of a resin carrier system 8 and an inner film 9. The lamination of the lower outer film 6' with the sliding film 2 and the sealing of the lower with the upper outer film 6', 6'' (or the sliding film 2 with the upper outer film 6'') takes place before installation in the sewer pipe. Figure 8 shows a schematic cross-section of a tray 15 of a widely known shape, preferably deep-drawn, which can be used for packaging foodstuffs (cheese, sausage, etc.) and has a film structure according to the invention with respect to its base and side walls. The tray 15 or tray can be closed by means of a top film 16, whereby the known systems of permanent closure, easy peel, or re-sealing can be used. These closure systems can be installed in the bottom film and / or the top film. As can be seen from the enlarged detail sections according to Figures 8a and 8b, the film 11 (bottom film) from which the tray 15 is made has an inner layer 3 which is designed according to claim 1, i.e., contains at least one thermoplastic olefin homo- or copolymer, optionally modified, and additionally at least one polyester.The two outer layers 4 and 5 consist, for example, of 100% foamed or unfoamed A-PET. Alternatively, the two outer layers 4 and 5 can also be configured differently, i.e., with regard to their components as well as their processing, thickness, etc. Figure 8a schematically shows that layer 3, with its mixture of olefin homo- or copolymer and polyester, is unfoamed, while layer 4, as shown in Figure 8b, is foamed. The films shown in Figure 8 can also be co-extruded with one or more further layers and / or laminated with one or more further films, for example, those with barrier properties. These include layers or films with EVOH and PA. Furthermore, it is possible that the film used according to the invention (possibly also co-extruded with further layers or laminated with further films) is designed as the top film 16 for food packaging.Such films used according to the invention can also be used in both the bottom and top layers. Other food containers, such as cups or pouches, can also be designed as described. Examples of foils for use according to the invention Example 1: The film according to Example 1 had an ABA structure with three layers, a 50:410:50 ratio, a total thickness of 510 µm, and an areal weight of 661 g / m², resulting in an average density of 1.296 g / cm³: Layer A: - Mono A-PET with an average density of 1.34 g / cm³, - an antiblocking agent was added at a concentration of 1%, - thickness of Layer A: 50 µm, - areal weight of Layer A: 67 g / m²; Layer B: - mixture of A-PET and LDPE, - the A-PET content was 78 wt%, the PE content was 20 wt%, - density of the A-PET was 1.34 g / cm³, the density of the LDPE was 0.92 g / cm³, - a white pigment (TiO₂) was added as a color pigment (in the form of a color batch). 2 wt.% and a density of 1.74 g / cm3,- Thickness of layer B: 410 µm,- Basis weight of layer B: 527 g / m2, the average density was 1.285 g / cm3. Layer A (both layers A were identical):- Mono A-PET with antiblocking agent,- Thickness of layer A: 50 µm,- Basis weight of layer A: 67 g / m2. Example 2: The film according to Example 2 largely corresponded to that of Example 1. The two A layers were identical to those of Example 1. Layer B also corresponded to layer B in Example 1, except that the A-PET content was 98 wt% and the LDPE content was 2 wt%. No white pigment or other substances were added. Example 3 (not measured): The film according to Example 3 largely corresponded to that of Example 1. The two layers A were identical to those of Example 1. Layer B also corresponded to layer B in Example 1, except that the A-PET content was 75 wt%, the PE content 22 wt%, and the white pigment (TiO2) content 3 wt%. Example 4 (not measured): The film according to Example 4 largely corresponded to that of Example 1. The two A layers were identical to those of Example 1. Layer B also corresponded to layer B in Example 1, except that the A-PET content was 99.5 wt% and the LDPE content was 0.5 wt%. No white pigment or other substances were added. Example 5 (not measured): Combination film or integrated anti-slip film The film according to Example 4 was laminated with a 230 µm thick PE-HV-PA-HV-PE film (5-layer film). The PE-PA-PE film was completely impermeable to UV radiation and visible light radiation (UV-Vis (abbreviation for visible = visible light) transmission in the wavelength range 200 nm to 800 nm below 0.5%). Example 6 (not measured): Outer foil system of a pipe liner The (laminated) film from Example 5, with a width of 500 mm, was sealed along its two outer longitudinal edges with a 500 mm wide, 230 µm thick PE-PA-PE film, resulting in a closed tube (circumference approx. 1000 mm). During sealing, the PE side of the combination film from Example 5 was sealed to the PE side of the unlaminated 230 µm thick PE-PA-PE UV and light protection film. The PE-PA-PE film was completely impermeable to UV radiation and visible light radiation (UV-Vis transmission in the wavelength range of 200 nm to 800 nm below 0.5%). The antiblocking agents in the aforementioned examples prevent the adhesion of the film used according to the invention to another material. Antiblocking agents are, for example, solids that create a micro-roughness on the plastic surface, thereby generating a very thin air layer as a separating layer when two films are placed on top of each other or when the films move relative to each other. In the case of a sliding film or a preliner, an outer layer containing the antiblocking agent faces the insert tube, so that when the insert tube is pulled over the sliding film or preliner laid in the pipe, it does not adhere to this outer layer of the sliding film or preliner. Comparative examples Comparison example V1: Whitish, cloudy, commercially available HDPE film (monofilm), already used as a sliding film in sewer rehabilitation; manufactured by cast extrusion; thickness 500 µm. Material Hostalen® GD 4755, density 0.953 g / cm³. Comparison example V2: Whitish, cloudy, commercially available HDPE film (monofilm); produced using the "Sheet Extrusion Process", i.e., a slot die with calender to produce a sheet-shaped film; thickness 600 µm. Measurement results: Both tensile tests and tear propagation tests were carried out with the example foils B1 and B2 as well as with the comparison foils V1 and V2. The samples were prepared by hand (samples cut onto the test material) and stored for 24 hours at standard climate conditions of 23°C and 50% relative humidity before testing. The tensile properties were measured according to DIN EN ISO 527 Part 3. The tensile strength σmax of a plastic film is given in N / mm². The elongation at break εBin % indicates how far the film can be stretched before tearing. A Zwick / Roell Z020 universal testing machine in "Macro 50 mm" mode, equipped with a macro displacement sensor for measuring the Young's modulus, was used for the tensile tests. The tests were performed on strips 140 mm long and 15 mm wide at a speed of 1 mm / min for the tensile modulus and a test speed of 500 mm / min for the tensile strength. The preload was 1 N, and the maximum force of the load cell was 2500 N. The tear strength was measured according to the DIN 53363 standard - Trapezoidal. The tensile strength Fmaxin N is defined as the force required to tear a piece of plastic film. The aforementioned Zwick / Roell Z020 universal testing machine, in "50 mm crosshead" mode with a crosshead displacement sensor, was used to measure the tear strength. The test was performed on strips 120 mm long and 50 mm wide with a 25 mm notch according to DIN 53363 - trapezoidal. The test speed was 300 mm / min, and the tensile modulus speed was also 300 mm / min. The preload was set to 1 N. The penetration resistance was measured according to the standard DIN EN ISO 6603 ff. An Instron / CEAST 9350 drop-bolt tester was used to measure the puncture resistance. The specimen dimensions were 60 x 60 mm². A circular recess with a diameter of 40 mm was incorporated into the bearing surface for the passage of the 5 kg bolt. The penetration velocity was 4.4 m / s. The point of penetration was measured at 50% (average of several measurements). Explanations for Table 1: - Et: Modulus of elasticity; - Sigma (σ) x%: Stress in N / mm² relative to the respective strain, here in the range of 1% to 25%; - Sigma Y (σY): Yield stress; - Epsilon Y (εY): Strain in % relative to the yield stresses; - Sigma M (σM): Maximum stress (tensile strength) in N / mm²; - Sigma M² (σM²): Maximum force in N; - Epsilon M (εM): Strain in % relative to the maximum stress; - Sigma B (σB): Tensile stress; - Epsilon B (εB): Elongation at break in % relative to the tensile stress. Table 1 lists the results of the tensile tests. For easier reference, unfavorable values ​​in the rows for V1 and V2 are printed in italics. Particularly unfavorable values ​​are shown in italics and bold. In the rows for B1 and B2, the particularly favorable values ​​are printed in bold. Table 1 clearly shows that conventional, commercially available sliding films based on HDPE (comparative examples V1 and V2) – compared to the films B1 and B2 used according to the invention – exhibit considerable elongation even at low tensile stress σ. For V1, an elongation of 1% in md (machine direction; first value in each cell) is already achieved with a tensile stress of 15.6 N / mm². For V2, an even lower tensile stress of 10.1 N / mm² is required. In contrast, examples B1 and B2 show a significantly higher required tensile stress at 1% elongation in the machine direction md, by a factor of 2 to 3 (22.6 N / mm² and 27.0 N / mm², respectively) compared to the reference foils V1 and V2. The results for B1 and B2 are also considerably more favorable than for V1 and V2 at 2.5% elongation. The very high elongation at V1 is also particularly pronounced in the machine direction md, which is especially disadvantageous. Furthermore, the elongation at the yield point (extensile strain) in the machine direction md is 32.2% for V1 and 11.0% for V2. The elongation at fracture in the machine direction md is 62.6% for V1 and 84.1% for V2. It is also noticeable that the commercially available film V1 is particularly anisotropic, meaning that the values ​​for the machine direction md and the cross direction cd (i.e., perpendicular to the machine direction md) differ significantly in the tensile test. In contrast, the strain at fracture in example B1 is only 3.5% and in example B2 only 3.6% in md. The strain at the yield point (extensile strain) is only 3.5% in md for B1. The strain at fracture in the machine direction md is only 3.5% for B1 and only 3.6% for B2. Furthermore, both films B1 and B2 exhibit very low anisotropy in the machine direction md and the transverse direction cd. The films B1 and B2 used according to the invention therefore require significantly more tensile stress and thus a higher tensile force for an elongation (of 1% and 2.5%, respectively) than the comparative examples V1 and V2. This is very advantageous for their use as a sliding film for the liners in trenchless sewer rehabilitation. As a result, the sliding film in the case of B1 and B2 remains unchanged in its position and does not stretch when the liner is pulled through the sewer. The "accordion effect" is thus almost completely avoided when the liner is no longer being pulled, so that the system cannot retract once the tensile force ceases. The sliding films according to the invention therefore serve as an ideal "guide" for the liner in the sewer being rehabilitated. The tensile test thus shows that the films B1 and B2 used according to the invention exhibit practically no stretching – neither in the transverse direction cd nor in the important machine direction md. The elongation at the yield point Epsilon Y (εY; tensile strain) is only about 1 / 10 of the elongation determined for film V1 in the case of B1. The same applies to the maximum elongation Epsilon M (εM) for both B1 and B2. The elongation at fracture Epsilon B (εεB) is approximately 20 times lower for the films B1 and B2 used according to the invention compared to V1 and approximately 24 times lower compared to V2. Consequently, the films B1 and B2 used according to the invention remain virtually unchanged in their shape and dimensions when the insert tube sliding on the sliding film is pulled through the channel. The films withstand high forces and are robust. They are therefore ideally suited for use as a sliding film or preliner. Table 2 lists the results of the tear strength tests. For easier reference, unfavorable values ​​are again printed in italics in the rows for V1 and V2. Particularly unfavorable values ​​are shown in italics and bold. In the rows for B1 and B2, the particularly favorable values ​​are printed in bold. The testing and comparison of the tear resistance (WRF) of examples B1 and B2 and comparative examples V1 and V2 yielded the following result: As in the tensile test, the films B1 and B2 used according to the invention require a significantly higher force to be stretched or torn at all. This aspect is particularly important in the machine direction md for use as a sliding film or preliner, since the insert tube is usually pulled through the tube in the machine direction md of the sliding film or preliner. As already observed in the tensile test, film V1 exhibits a significant weakness in the machine direction md, which is further evidence of the anisotropy of this film. In the machine direction md, the tear force is only 56 N and the tensile strength only 2.2 N / mm². Slightly better values ​​are found for the commercially available film V2 (171 N and 5.7 N / mm², respectively). In contrast, the films B1 and B2 used according to the invention, with the mixtures of A-PET and LDPE in layer B, exhibit significantly higher tensile strength (248 and 197 N, respectively) and tear resistance (9.8 and 9.9 N / mm², respectively) in the machine direction md compared to V1 and V2. The tear resistance of films B1 and B2 is 4-5 times higher than that of V1 in the machine direction md and approximately twice as high as that of V2. Therefore, these films are ideally suited as a sliding film or preliner for inserting pipe liners during trenchless sewer rehabilitation. Table 3 lists the results of the puncture resistance tests. For easier reference, unfavorable values ​​are again printed in italics in the rows for V1 and V2. Particularly favorable values ​​are printed in bold in the rows for B1 and B2. The standard V1 foil has a maximum puncture force Fmax of 419.9 N and a penetration force Fp of 209.2 N. These values ​​are rather low for use as a sliding foil in sewer rehabilitation, as the sliding foil serves a protective function against the inserted liner due to potential corners and edges on the sewer walls. In the case of the V1 foil, the sliding foil would offer only minimal protection, as it can be punctured with relatively little force. Higher values ​​are obtained for both the V2 foil (with a thickness of 600 µm) and the B2 foil (with a thickness of 500 µm). These foils are far better suited for use as sliding foils than the V1 foil. Table 3 clearly shows the beneficial effect of an increased amount of polyethylene on the polyester-based film in Example B1. While the film in Example B2 contains 2 wt% PE in addition to 98 wt% A-PET in the middle layer B and achieves a maximum puncture force of 520.54 N, the addition of 20 wt% polyethylene in addition to 78 wt% A-PET in the middle layer B leads to a significant increase in the puncture force to 601.22 N. Thus, the film used according to the invention in Example B1 is both particularly puncture-resistant and robust (see Tables 1 and 2). Table 1: Tensile test in md (machine direction) / cd (cross direction) UnitN / mm 2N / mm 2N / mm 2N / mm 2N / mm 2N / mm 2N / mm 2%N / mm 2N%N / mm 2% V11240 / 176015.6 / 18,530.6 / 30,840.9 / 30,449.1 / 19,454 / -54.3 / 33,932,214,554.3 / 33,9409.3 / 255,032.2 / 4,546.7 / 21,262.6 / 10.9 V2844 / 105010.1 / 12.118.4 / 21.423.4 / 27.125.4 / 28.624.7 / 17.725.4 / 28.611.0 / 8.725.4 / 28.6230 / 26110.818.19.1 / 16.484.1 / 47.4 B12350 / 224022.6 / 22,047.8 / 46,543.5 / 27.4- / -- / -- / -3.5 / 3,454.3 / 51.7- / -3.5 / 3,425.4 / 37.33.5 / 3.4 B22800 / 26202 7.0 / 25,858.2 / 55.6- / -- / -- / -- / -- / -68.4 / 64.7412 / 3943.5 / 3,367.2 / 643.6 / 3.3 Table 2: Tear strength (WRF) in md / cd Table 2: Tear strength (WRF) in md / cd Unit / mm² V11.9 / 1.53.9 / 2.89.6 / 6.127.9 / 25.637.9 / 23030.1 / 30056.0 / 4972.2 / 19.9 V22.1 / 1.94.3 / 4.010.5 / 10.034.1 / 39.6139 / 195156 / 238171 / 2975.7 / 9.9 B12.5 / 2.55,715,514.6 / 13.851.3 / 48.4179 / 174214 / 208248 / 2519.8 / 9.9 B22.2 / 2.14.8 / 4,612.8 / 11,947.2 / 45,6148 / 158175 / 187197 / 2199.9 / 11.0 Table 3: Puncture resistance in md / cd Table 3: Puncture resistance in md / cd UnitNN V1419,9209,2 V2525,5262.6 B1601,22294,3 B2520,54259,3

Claims

Use of a single- or multi-layer film as a sliding film (2) or preliner (1) in pipe rehabilitation using cured-in-place pipe (CIPP) lining technology for application to the inner wall of an underground pipe to be rehabilitated, preferably a sewer pipe (K), so that an insert hose (7) with a curable carrier material (8) can be slid through the pipe on the sliding film (2) or preliner (1) laid in the pipe, wherein the film (1; 2) comprises at least one layer (3) containing at least one thermoplastic olefin homo- or copolymer, optionally modified, characterized in that said layer (3) additionally contains at least one polyester. Use of a film according to claim 1, characterized in that said at least one layer (3) contains more than 50 wt.% of thermoplastic olefin homo- or copolymer and 0.1 to 50 wt.% of polyester, wherein the respective mass fractions of the substances present in the film total 100 wt.%. Use of a film according to claim 1, characterized in that said at least one layer (3) contains more than 50 wt.% polyester and 0.1 to 50 wt.%, preferably between 10 wt.% and 35 wt.%, thermoplastic olefin homo- or copolymer, wherein the respective mass fractions of the substances present in the film total 100 wt.%. Use of a film according to one or more of the preceding claims, characterized in that the at least one polyester is amorphous, in particular in the form of amorphous polyethylene terephthalate (A-PET). Use of a film according to one or more of the preceding claims, characterized in that the at least one polyester, in particular present as A-PET, is contained in the layer (3) according to claim 1 to more than 25 wt.%, preferably to more than 40 wt.% and particularly preferably to more than 50 wt.%, in particular to more than 65 wt.%. Use of a film according to one or more of the preceding claims, characterized in that the at least one olefin homo- or copolymer is polyethylene (PE), preferably in the form of low-density polyethylene (LDPE), metallocene low-density polyethylene (mLDPE), linear low-density polyethylene (LLDPE), very low-density polyethylene (VLDPE), medium-density polyethylene (MDPE) and / or high-density polyethylene (HDPE), and / or polypropylene (PP). Use of a film according to one or more of the preceding claims, characterized in that the at least one olefin homo- or copolymer is an adhesion promoter or has an adhesion-promoting function, preferably by modification with functional groups, in particular with epoxy groups, (carbon) acid groups, hydroxyl groups and / or acid anhydride groups, preferably cyclic organic acid anhydride groups, particularly preferably with maleic anhydride groups. Use of a film according to one or more of the preceding claims, characterized in that the film (1; 2; 11) has, in addition to the said at least one layer (3) according to claim 1, at least one intermediate and / or cover or outer layer (4, 5). Use of a film according to one or more of the preceding claims, characterized in that the film (1; 2; 11) has a thickness of 20 to 2000 µm, particularly preferably of 50 to 1500 µm, most preferably of 100 to 1000 µm, in particular of 200 to 900 µm. Use of a film according to one or more of the preceding claims, characterized in that the film (1; 2; 11) has at least one independent barrier layer against the passage of gases and / or chemical substances, preferably based on ethylene vinyl alcohol (EVOH) or polyamide (PA) or both and further preferably each consisting of 100% of these compounds. Use of a film according to one or more of the preceding claims, characterized in that the film (1; 2; 11) has an independent layer which contains at least one chemical compound acting as a barrier against the passage of chemical substances, preferably against monomers, preferably polyamide (PA), and / or at least one chemical compound acting as a barrier against UV light and visible light, so that transmission of radiation in the wavelength range of 350 to 450 nm is at least largely prevented. Use of a film according to one or more of the preceding claims, characterized in that one or more of the following substances are contained in said at least one layer (3) according to claim 1: polystyrene (PS); polyhalides, such as PVC and / or polyvinylidene chloride (PVdC); polyamide (PA); ethylene vinyl alcohol copolymer (EVOH), polyvinyl alcohol (PVOH or PVAL), adhesion promoter, ethylene vinyl acetate (EVAc); one or more ionomers; one or more poly(meth)acrylates; ethylene-containing poly(meth)acrylates, polyvinyl acetate (PVAc); polycarbonate (PC); polyacrylonitrile (PAN); other polyesters such as polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), polylactic acid (PLA) and / or polyhydroxyalkanoates (PHA); one or more ethylene acrylic acid copolymers (EAA); polyvinyl butyral (PVB); polyvinyl acetal; cellulose acetate (CA); Cellulose acetobutyrate (CAB); polysaccharides; starch; cyclic olefin copolymer (COC). Use of a film according to one or more of the preceding claims, characterized in that the following substances are added during extrusion in one or more layers (3, 4, 5): adhesion promoters, functionalized polymer such as EVOH, optical brighteners, thermal stabilizers, lubricants, antioxidants, oxygen scavenger, spacers (e.g. silica particles, SAS), slip / antiblocking agents, colors, pigments, foaming agents, antistatic agents, processing aids, lubricating agents, flame retardants, flame inhibitors, impact modifiers, impact improvers, anti-hydrolysis agents, UV absorbers, UV protectants, stabilizers, anti-fog additives, waxes, wax additives, release agents, sealing or peel additives, nucleating agents, compatibilizers, flow agents, melt strength enhancers, molecular weight increasers, crosslinkers or plasticizers. Use of a film according to one or more of the preceding claims, characterized in that one or more layers (3, 4, 5) of the film (1; 2; 11), including said at least one layer (3) according to claim 1, are foamed. Use of a film according to one or more of the preceding claims in a film combination, characterized in that at least one additional film (6; 6') is applied to said film (1; 2; 11) according to one or more of the preceding claims, preferably laminated. Use of a film in a film combination according to the previous claim, characterized in that the additional film (6; 6') is a light protection film, preferably a UV and light protection film. Use of a film in a film combination according to one of the two preceding claims, characterized in that the additional film (6; 6') contains at least one chemical compound to achieve a barrier against monomers such as styrene, oils and / or fats. Use of a film in a film combination according to one of the three preceding claims, characterized in that the additional film (6') is laminated onto a sliding film (2) open at the longitudinal edges according to one of the preceding claims, wherein a further film (6''), which may be constructed like the laminated additional film (6'), is connected at its longitudinal edges to the longitudinal edges of the sliding film (2) or the laminated additional film (6'), preferably sealed. Use of a film in a composite of a film combination according to one of the four preceding claims as well as at least one resin-impregnated carrier system (8) and an inner film (9) in the sequence: a) said film (1; 2) b) at least one laminated film (6; 6'), preferably a UV and light protection film, c) resin-impregnated carrier system (8), d) inner film (9).

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