METHOD FOR PRODUCE A GRAPHED FILM OR A GRAPHED, MULTI-LAYER FILM LAMINATE

Description

[0001] The invention relates to a process for producing a grained film or a grained, multilayer film laminate comprising a top film and at least one bottom film or at least one polyolefin-based foam. This process involves forming a polymer mass including a polyolefin recyclate, shaping the mass into a film, and bonding the film to a bottom film or a polyolefin foam. A grain is then applied to the film. The present invention further relates to grained polymer films produced by such a process and their use as artificial leather, particularly in automotive or clothing applications. State of the art

[0002] Documents US 6,828,384 B2 and US 9,669,600 B2, for example, are known from the prior art. Artificial leather plays a significant role in the automotive and clothing industries today, as the demand for surface coverings for automotive applications is so great that it can no longer be met by natural leather.

[0003] Artificial leather typically consists of a composite of a textile base (e.g., fabric) and a plastic cover layer, which can be provided with a corresponding grain, e.g., to convey the typical optical surface impression of the hair side of natural leather. Depending on the surface material used for the artificial leather, such a grain can either be embossed or generated during the production of the surface film by applying a corresponding negative to which a liquid precursor of the surface film is then cured.

[0004] Artificial leathers in which the surface film is formed from polyolefin-containing materials are often cross-linked to improve the stability of the surface film and the grain generated thereon against deforming processing, such as occurs in deep-drawing processes. A method for producing such artificial leather is described, for example, in EP 1 149 858 B2, in which an artificial leather with a grained polyolefin top film is first cross-linked with electron beams and then deep-drawn into the desired shape.

[0005] EP 1 538 175 B1 describes a process for producing a grained multilayer molded article with a grained upper film that has been stabilized by electron beams to prevent damage to the grain during a subsequent deep-drawing process. EP 1 538 175 B1 uses a foamed polymer material as the lower film, which has a density of 35 to 120 g / L and a gel content of less than 80%.

[0006] EP 1 688 460 B1 describes a process for producing a grained film or a grained multilayer film laminate with a top and a bottom film, wherein the material forming the cover layer contains polyolefins and optionally further polymers and additives (e.g., crosslinkers). After an embossing step for applying a grain, the mass is adjusted to a gel content of 3 to 15% using electron beams.

[0007] EP 2 263 857 A2 describes a process in which a film body for the interior trim of motor vehicles is produced from a starting material containing uncrosslinked polyolefins and uncrosslinked ionomers and is then subjected to a grain-forming negative deep-drawing process to generate the hub, wherein the film is deep-drawn into a component shape which contains the desired grain image as a negative.

[0008] During the further processing of the artificial leather and films produced in this way, waste cannot be avoided, despite the fact that cutting of artificial leather, for example for interior applications in vehicles, is now generally computer-assisted planning. This is because even with the best planning it is not possible to distribute the required pieces of artificial leather on a given length of artificial leather in such a way that no leftovers are created. In addition, the industrial production of film webs can repeatedly lead to production errors or products that do not meet the quality criteria and specifications specified by the customer. Due to this almost unavoidable waste in the production process, which leads to increasing damage to the environment, the plastics industry is currently subject to considerable criticism. There is therefore a need for measures with which the corresponding waste can be either minimized or recycled and thus returned to the product cycle.

[0009] One problem with the artificial leathers described above is that they are usually varnished on the visible side to impart an attractive appearance, often using a cross-linked polyurethane-based varnish. This means that such residues cannot be easily recycled, as specks (surface defects) form during normal processing and can lead to deposits during the production of new films. Such defects and sink marks are unacceptable to the consumers of the artificial leather end products.

[0010] Against this background, there is a need for processes that allow film residues or waste to be recycled into the manufacturing process and that avoid the problems described above. Furthermore, there is a need for polyolefin films suitable for processing into grained films or top films for artificial leather, and that contain the highest possible proportion of polyolefin recyclates without significantly compromising the quality properties of the films.

[0011] The present invention addresses this need. Description of the invention

[0012] In a first aspect, the present invention relates to a process for producing a grained film or a grained, multi-layer film laminate having a top film and at least one bottom film or at least one polyolefin-based foam, the process comprising the following steps: i) forming a mass containing the following polymer components: 5 to 75 wt% of a polyolefin recyclate having a melting point < 165 °C, 5 to 75 wt% of an ethylene polymer or a mixture of several ethylene polymers having a density < 0.97 g / cm 3< , 0 to 50 wt% of a polypropylene having a density < 0.92 g / cm 3< , and ii) forming the mass into a film, and optionally iii) combining the film produced in (ii) with a base film or a foam, wherein the film is embossed following step (ii) or after the optional step (iii) to apply a scar.

[0013] In the described process, the film can consist of the specified polymer mass or be in the form of a film laminate in which the upper film is produced from the specified polymer mass. A compact lower film or a foam, such as a polyolefin-based foam, can be used as the lower film. A foam can also simultaneously offer a protective function for the grained upper film against a carrier material pressed onto the back of the film. If the lower film is in the form of foam, this preferably has a density in the range of 35 to 200 g / l. The lower film or foam can be cross-linked or uncross-linked, with cross-linked lower films and foams being preferred. In this case, the lower film or foam expediently has a gel content of less than 80%. Furthermore or alternatively, the lower film is preferably made of a polyolefin foam based on polyethylene and / or polypropylene.

[0014] To form the polymer mass, the individual substances can be mixed together under suitable conditions, preferably at a temperature in the range of or above the melting point of the polymer components and / or in the range of or above the melting point of the highest-melting polymer component. In principle, any device that allows such mixing can be used for this purpose. However, mixing is preferably carried out in an extruder with one or more mixing zones, since extrusion allows films to be produced directly from the molten polymer mass.

[0015] In addition to a melting point of <165°C, the polyolefin recyclate preferably has a gel content of at least 10 wt.%, preferably at least 15 wt.%, and more preferably at least 20 wt.%. Due to the process, the gel content of the polyolefin recyclate is not unlimited; however, a reasonable upper limit for the gel content can be specified as 40 wt.%, in particular 35 wt.%, and even more preferably 30 wt.%. The gel content of the polyolefin recyclate is determined by extracting the recyclate with boiling xylene for 24 hours, with the solid fraction remaining after extraction corresponding to the gel content.

[0016] Based on the total composition of the polymers in the polymer mass, the gel content should preferably be in the range of about 1 to about 20 wt.%, more preferably about 2 to about 15 wt.%, and even more preferably about 2.5 to about 12 wt.%.

[0017] A particularly suitable proportion of polyolefin recyclate in the polymer mass can be specified as a range from 10 to 60 wt.% and in particular a range from 10 to 45 wt.%, whereby the weight specifications are based on the total weight of the polymers in the polymer film. Since the polyolefin recyclate is in most cases a polyolefin recyclate produced from coated polyolefin films, the polyolefin recyclate regularly contains detectable amounts of the varnish, which, however, do not have an adverse effect on the product and processing properties. A polyolefin recyclate produced from a starting product with a polyurethane varnish, for example, contains polyurethane residues, which can be detected by means of carbonyl absorption bands that are clearly visible in infrared spectroscopy, and in de novoare not contained in the polyolefins produced. Amounts of paint residues contained, particularly in the form of polyurethane residues, are normally in the range from 1.3 wt.% to the detection limit for paint residues (when determined by infrared spectroscopy), with amounts of less than 0.9 wt.% being preferred, amounts of less than 0.4 wt.% being more preferred, amounts of less than 0.1 wt.% being even more preferred, and amounts of less than 0.05 wt.% even more preferred.

[0018] Another property of the polyolefin recyclates from de novo The only difference between the polyolefins produced is the smell. While this smell is de novoWhile the odor suppression effect of the polyolefins produced is usually unspecific or undetectable, the processing of used polyolefin leads to the development of odors that are perceived as unpleasant due to substances that have migrated into the polyolefins and the thermal stress during processing. In order to suppress these odors, an odor-suppressing substance can be added to the polyolefin recyclate, e.g. in the form of the zinc salt of ricinoleic acid or zeolite. Accordingly, the polyolefin recyclate in the process according to the invention and products produced therefrom preferably contain a detectable amount of odor-suppressing substances, in particular zinc salt of ricinoleic acid and / or zeolite, e.g. 1 to 5 wt.% and in particular 1.5 to 3 wt.%, in each case based on the total amount of polyolefin recyclate. By adding these additives, an odor rating of 2 to 3 according to VDA 270 (2018) can be achieved.

[0019] Polyolefin recyclates are produced within the process according to the invention for producing a grained film by a process comprising the steps (a) shredding film waste containing a proportion of cross-linked polyolefins, wherein the films underlying the film waste comprise a coated polyolefin-based film, optionally as a top film together with a compact polyolefin-based bottom film or a polyolefin-based foam, (b) extruding the shredded film waste, (c) filtering the molten extrudate, to form the polyolefin recyclate. Accordingly, a particularly preferred embodiment of the invention comprises a process that comprises the steps (i) to (iii) specified above, and steps (a) to (c) for producing the polyolefin recyclate to be included in step (i). The film waste has a proportion of cross-linked polyolefins, which in the case of a multi-layer film can be present in the upper film (from the visible side) and / or in a lower film or a foam used under the upper film. A polyolefin recyclate that is particularly suitable for further processing can be produced in particular via filtration in step (c), in which a sieve with a mesh size in the range of 40 to 300 µm and in particular 60 to 100 µm is used. Processes with the steps (a) to (c) specified above, as well as suitable devices for carrying out such processes, are known to the person skilled in the art, for example from EP 3 088 157 A2 or the DE 20 2019 102 066 U1 common.

[0020] The film waste to be included in this processing can consist of polyolefin-based films based on cross-linked polyolefins, and preferably cross-linked polyolefin blends of polypropylene and copolymers of ethylene and propylene. It is particularly preferred if the film waste consists of polymer materials with a similar composition to the ethylene copolymer to be included in the process in (i) or the mixture of several ethylene copolymers, optionally in combination with the optional polypropylene.

[0021] The second polymer component used in the polymer composition is an ethylene polymer or a mixture of several ethylene polymers with a density < 0.97 g / cm 3 <. Ethylene polymers include ethylene homopolymers and ethylene copolymers with other monomers. Particularly suitable ethylene copolymers are, for example, ethylene copolymers with C 3 to C 12 α-olefins, such as propylene, butylene or hexylene, particularly preferred are Ethylene / propylene copolymers.

[0022] The proportion of this ethylene polymer in the polymer mass is preferably 6 to 60 wt.%, more preferably 8 to 50 wt.% and even more preferably 9 to 40 wt.%.

[0023] The ethylene polymer or the ethylene polymers preferably have a melt flow index of < 10 g / 10 min (190°C / 2.16 kg), in particular of < 5 g / 10 min (190°C / 2.16 kg) and even more preferably < 2 g / 10 min (190°C / 2.16 kg).

[0024] As a third optional component, the polymer composition contains a polypropylene. The polypropylene may also contain other olefins, e.g., ethylene, to a small extent, but only in an amount that does not significantly affect the performance properties of the polypropylene. Accordingly, the proportion of any other olefins present should not exceed 5 wt.%, preferably 2 wt.%, and more preferably 1 wt.%. Most preferably, the polypropylene is a pure polypropylene homopolymer.

[0025] The polypropylene can be in the form of isotactic polypropylene, atactic polypropylene (also referred to as polypropylene-R) or polypropylene with atactic and isotactic segments (also referred to as polypropylene-H), with polypropylene-R and polypropylene-H being preferred.

[0026] The polypropylene preferably has a melt flow index of < 10 g / 10 min (230°C / 2.16 kg), in particular of < 5 g / 10 min (230°C / 2.16 kg) and even more preferably in the range of about 2 g / 10 min (230°C / 2.16 kg) to 0.5 g / 10 min (230°C / 2.16 kg).

[0027] The proportion of polypropylene included in the polymer mass is preferably 2 to 40 wt%, more preferably 4 to 30 wt% and even more preferably 5 to 20 wt%.

[0028] With regard to the aforementioned ethylene polymers and polypropylene, if the latter are present in the polymer mass, it is preferred if they are present in a ratio in the range of 1:1 to 4:1, more preferably a ratio in the range of 1.5:1 to 3:1 and even more preferably a ratio in the range of about 2:1.

[0029] As a further optional component, the polymer composition to be incorporated into the process according to the invention may additionally contain a polyolefin rubber. Rubber materials containing double bonds are particularly suitable as additional polyolefin rubbers, since the double bonds they contain promote further crosslinking without the need to add low-molecular-weight compounds such as conventional crosslinking aids. A particularly suitable polyolefin rubber in this context is ethylene propylene diene rubber (EPDM).

[0030] A polyolefin rubber can be incorporated into the polymer mass in an amount suitable for setting the desired product properties, with a proportion of 10 to 60 wt.% being advantageous, a proportion of 15 to 50 wt.% being particularly advantageous and a proportion of 20 to 40 wt.% being particularly advantageous.

[0031] In addition to the polymer components, the polymer mass used for film production preferably contains one or more auxiliaries, such as pigments, crosslinking agents, antioxidants, light stabilizers, lubricants and / or ageing inhibitors.

[0032] For example, in order to achieve a sufficient degree of crosslinking after the embossing step, a crosslinking aid is preferably added. This applies in particular to polymer masses that do not contain polymer components with double bonds (such as EPDM Polymers) in which chain scission, which competes with crosslinking, has a noticeable effect. This particularly affects polyolefins with tertiary carbon atoms, such as polypropylene.

[0033] Suitable crosslinking agents include, in particular, mono- or polyunsaturated compounds, such as acrylates of mono- or polyhydric alcohols, e.g., trimethylolpropane triacrylate; methacrylates of mono- or polyhydric alcohols, e.g., trimethylolpropane trimethacrylate; vinyl-functional compounds, such as styrene and divinylbenzene; and allyl compounds, such as triallyl isocyanate, p-quinone dioxime, p,p'-dibenzoylquinone dioxime, N-methyl-N,4-dinitrosoaniline, nitrobenzene, diphenylguanidine, or trimethylolpropane-N,N'-m-phenylenedimaleimide. Particularly good results are achieved using trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, triallyl cyanurate, divinylbenzene, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, and / or polyethylene glycol dimethacrylate. The crosslinking agents should be incorporated into the polymer mass in the amount required to achieve the desired degree of crosslinking, with amounts of up to about 6 wt.-%, preferably up to about 3 wt.% and particularly preferably up to about 2 wt.%, based on the content of the mass of uncrosslinked polyolefins.

[0034] Particularly advantageous antioxidants for use in the polymer compositions according to the invention are, in particular, phenol derivatives, lactones and / or phosphites and, as light stabilizers, sterically hindered amines or benzotriazines, which can advantageously be incorporated into the polymer composition in an amount of less than about 5% by weight, preferably up to 3.5% by weight, in particular from 0.2 to 2.5% by weight, based on the total weight.

[0035] In a preferred embodiment, the forming of the film in step (ii) comprises forming a film from the mass; the film can then be embossed to apply a grain. The film is formed by methods known to those skilled in the art, such as extrusion and calendering processes. The thickness of the film should be adjusted to a suitable level, with a film thickness in the range of 0.1 to 2.0 mm being preferred, and a thickness in the range of 0.2 to 0.6 mm being particularly preferred.

[0036] Due to the film's moderate gel content prior to embossing, it is easily embossed using embossing rollers, and the roller speed can be set to high. A particularly suitable embossing speed, which can be adjusted within the process, is approximately 5 to 12 m / min and, in particular, 6 to 10 m / min. Alternatively, embossing can also be applied to the film using an IMG or negative thermoforming process, in which the film is thermoformed with its visible side on a molded body provided with the negative of a grain.

[0037] Following embossing, the material is further cross-linked to ensure high grain strength, for example, during deep drawing and / or forming. Further cross-linking is achieved using radiation, particularly electron beams.

[0038] In the case of compact films, irradiation is preferably carried out with an irradiation dose of 10 to 300 kGy, in particular 30 to 150 kGy, and in the case of film laminates with an irradiation dose of 20 to 150 kGy, in particular 30 to 100 kGy.

[0039] To create a visually appealing impression, a coating can be applied to the film produced using the described process. A polyurethane-based coating is preferably used, which is applied to the resulting film or top film. A coating can be applied before or after embossing, although application before embossing is preferred because a uniform coating application is difficult to achieve, especially with deeper grains and the associated greater level differences.

[0040] In optional step (iii) of the described process, the film produced in (ii) is bonded to a base film or a polyolefin-based foam. For this purpose, methods for bonding films known to those skilled in the art can be used, such as bonding by introducing an adhesive or bonding by activating one or both films, for example, by melting the surface and then pressing the films together. If necessary, a primer, e.g., based on polyurethane, can also be applied to the film to ensure a good bond.

[0041] The method described above can be advantageously further developed by subjecting the grained film obtained in step (ii) or (iii) to a positive deep-drawing process (ie a deep-drawing process in which the grained side of the film is located on the side opposite the forming tool).

[0042] Alternatively, it is also possible for the film formed from the polymer mass in step (ii), optionally after bonding to a base film or a polyolefin-based foam according to step (iii), to be subjected to a negative deep-drawing process for applying the scar, wherein a mold with the negative of the scar is used, and the scar is transferred to the film by the energy introduced into the film during the molding.

[0043] A further aspect of the present invention relates to a grained polymer film obtainable by a process as described above. Due to the process involved, i.e., because it is produced using a recycled material, the corresponding grained polymer film contains, within its interior, finely distributed residues of a coating applied to films from which the recycled material was generated. Such residues are, as explained above, detectable, for example, by infrared spectroscopy.

[0044] A still further aspect of the present invention relates to the use of a grained polymer film as described above as a plastic decorative material or artificial leather, and in particular as an artificial leather covering in the automotive sector, in particular as an interior panel, preferably as a dashboard panel, or in a garment.

[0045] The films or film laminates produced by the process according to the invention, as well as the molded articles produced therefrom, offer numerous advantages. Due to their good embossability and grain reproduction, the films or film laminates are very easy to produce, and the embossing speed can be maintained at a high level without compromising the embossed structure, thus achieving good production process efficiency.

[0046] The films or film laminates produced by the process according to the invention and converted into molded articles are particularly suitable for use as interior trim in motor vehicles, e.g., as instrument panels, due to their stable, clean grain pattern. Due to the long service life of motor vehicles, interior trim in particular is subject to high levels of stress. A stable, clean grain pattern is particularly important for the quality impression of the vehicle interior trim. The process according to the invention largely eliminates any disruption to the homogeneity of the grain pattern. A distinctive grain pattern is obtained, and an undesirable surface shine is prevented.

[0047] In the following, the invention is further illustrated by means of some illustrative examples, which are not to be considered in any way limiting the technical contribution of the invention. Examples

[0048] For the following description, the Shore A hardness was determined according to DIN ISO 7619-1 (2012). Gloss was determined after deep drawing at a stretch of 80 to 100% at an angle of 60° using a Byk Gardner Mikro Gloss device according to DIN 67530 (1982) and is expressed as gloss units. Example 1

[0049] Various films with the compositions listed in Table 1 (each in parts by weight) were produced by blending the corresponding polymers and additives in an extruder at temperatures ranging from 175 to 195°C (die temperature 200°C). The films were then coated and subjected to an IMG or negative thermoforming process. The thermoforming behavior and observed properties of the produced films are also listed in Table 1. Table 1 substance Comparison example 1 Example 1 Example 2 Example 3 TPE-V 1< 60 50 60 PP2< 14 19,3 5,3 10,5 Ethylene / propylene copolymer 3< 26 35,7 9,7 19,5 TPO recyclate 4< 45 35 10 pigment 1 1 1 1 stabilizer 2 2 2 2 Characteristics Extrusion behavior In order In order In order In order Deep drawing in the IMG 5< process Distinctive scar, no shine Distinctive scar, no shine Distinctive scar, no shine Distinctive scar, no shine Shine 1,0 - 1,3 0,8 - 0,9 0,8 - 1,0 0,9 - 1,2 Shore A 85 86 86 85 Haptics (manual) pleasant pleasant pleasant pleasant 1< = Thermoplastic elastomer consisting of 35 wt% polypropylene and 65 wt% cross-linked polyethylene-polypropylene-diene copolymer, MFI 15 g / 10 min (230°C / 10 kg), gel content 28%; 2< = Polypropylene-R, density 0.90 g / cm 3< , MFI 1.0 g / 10 min (230°C / 2.16 kg); 3< = Copolymer of ethylene and propylene, density 0.89 g / cm 3< , MFI 1 g / 10 min (190°C / 2.16 kg); 4< = Mixture of polyethylene, polypropylene, MFI 0.5 to 1 g / 10 min (230°C / 2.16 kg); 5< = In Mold Graining process.

[0050] The table above shows that the TPE-V conventionally used for the production of polyolefin film can be almost entirely replaced by TPO recyclate without any noticeable impact on the processing and final product properties. Likewise, some of the PP and ethylene / propylene copolymer conventionally used can be replaced by TPO recyclate without any significant effect on the final product. Example 2

[0051] Various films with the compositions listed in Table 2 (each in parts by weight) were produced by blending the corresponding polymers and additives in an extruder at temperatures ranging from 175 to 195°C (die temperature 200°C). The films were then coated and embossed to apply a grain (embossing speed 3 m / min (comparative examples) or 8 m / min) and crosslinked with electron beams. Finally, the grained films thus produced were subjected to a positive thermoforming process. The crosslinking parameters, thermoforming behavior, and observed properties of the produced films are also listed in Table 2. Table 2 substance Comparison example 1 Comparison example 2 Example 1 Example 2 Example 3 TPE-V 1< 30 EPDM 2< 30 20 33,25 33,25 33,25 PP3< 24,5 17,5 12,87 16,36 19,86 Ethylene / propylene copolymer 4< 45,5 32,5 23,88 30,39 36,89 TPO recyclate 5< 30 20 10 pigment 1 1 1 1 1 Covernetzer 2 2 Crosslinking dose 75 kGy 75 kGy 40 kGy 40 kGy 40 kGy Characteristics Extrusion behavior In order In order In order In order In order Deep drawing positive process Distinctive scar, no shine Distinctive scar, no shine Distinctive scar, no shine Distinctive scar, no shine Distinctive scar, no shine Shine 1,0 - 1,3 1,1 - 1,5 0,8 - 1,0 0,8 - 1,0 0,8 - 1,0 Shore A 91 90 85 88 90 Haptics (manual) pleasant pleasant pleasant pleasant pleasant 1< = Thermoplastic elastomer consisting of 35 wt% polypropylene and 65 wt% cross-linked polyethylene-polypropylene-diene copolymer, MFI 15 g / 10 min (230°C / 10 kg), gel content 28%; 2< = ethylene-propylene-diene copolymer, density 0.89 g / cm 3< , MFI 1 g / 10 min (230°C / 2.16 kg); 3< = Polypropylene-H, density 0.92 g / cm 3< , MFI 1.0 g / 10 min (230°C / 2.16 kg); 4< = Copolymer of ethylene and propylene, density 0.89 g / cm 3< , MFI 1 g / 10 min (190°C / 2.16 kg); 5< = Mixture of polyethylene, polypropylene, MFI 0.5 - 1 g / 10 min (230°C / 2.16 kg).

[0052] The table above shows that TPE-V in the polymer compositions can be replaced with TPO recyclate without significantly affecting the processing and final product properties. Favorable product properties can be achieved by adding amounts in the range of 10 to 30 wt.% (based on the total amount of polymer).

Claims

1. Method for producing a grained film or a grained, multi-ply film laminate with an upper film and at least one lower film or at least one polyolefin-based foam, the method comprising the following steps: forming a polyolefin recyclate with a melting point < 165 °C by (a) comminuting film wastes having a fraction of crosslinked polyolefins, where the films comprising the film wastes include a varnished polyolefin-based film, optionally as an upper film together with a compact polyolefin-based lower film or a polyolefin-based foam, (b) extruding the comminuted film wastes, (c) filtering the melted extrudate, preferably via a screen with a mesh size in the range from 40 to 100 µm, and i) forming a compound containing polymer constituents as follows: - 5% to 75% by weight of the polyolefin recyclate produced in (a) to (c), - 5% to 75% by weight of an ethylene polymer or a mixture of two or more ethylene polymers with a density < 0.97 g / cm3, - 0% to 50% by weight of a polypropylene with a density < 0.92 g / cm3, and ii) moulding the compound into a film, and optionally iii) joining the film produced in (ii) to a lower film or a polyolefin-based foam, the film being embossed following step (ii) or after optional step (iii) for applying a grain, and the grained film being subsequently radiation-crosslinked.

2. Method according to Claim 1, additionally comprising a step of applying a coating system, preferably a polyurethane-based varnish, to the film or upper film formed, preferably before this film is embossed in the following step.

3. Method according to at least one of the preceding claims, wherein the moulding in step ii) comprises the extrusion of the polymer compound into a film.

4. Method according to at least one of the preceding claims, wherein the grained film formed in the method is electron beam-crosslinked.

5. Method according to at least one of the preceding claims, wherein the compound in step (i) contains 10% to 60% and preferably 10% to 45% by weight of polyolefin recyclate, based on the total weight of the polymers in the polymer film.

6. Method according to at least one of the preceding claims, characterized in that the ethylene polymer used in the compound in (i) is a copolymer having a melt flow index of less than 10 g / 10 min (190°C / 2.16 kg) and is preferably in the form of an ethylene-propylene copolymer.

7. Method according to at least one of the preceding claims, characterized in that the polypropylene used in the compound in (i) is a polypropylene-R or a polypropylene-H.

8. Method according to at least one of the preceding claims, wherein the compound used in step (i) further contains 10% to 60% by weight of a rubber, preferably a polyolefin rubber, and more preferably an ethylene-propylene-diene rubber.

9. Method according to at least one of the preceding claims, wherein the film formed from the compound in (i) has a thickness in the range from 0.1 to 2 mm and preferably 0.2 to 0.6 mm.

10. Method according to at least one of the preceding claims, wherein additionally one or more additives selected from pigments, crosslinking assistants, antioxidants, light stabilizers, lubricants and anti-ageing agents is incorporated into the compound in step (i).

11. Method according to at least one of the preceding claims, wherein the grained film in step (iii) is joined to a compact or foamed polymer layer, preferably to a foamed polymer layer having a density in the range from 35 to 200 g / L and a gel content of less than 80%.

12. Method according to at least one of the preceding claims, wherein the grained film obtained in the method is subjected to a positive thermoforming process or the film obtained is subjected to a negative thermoforming process for applying the grain.