Recyclable packaging laminate with improved heat resistance during sealing

Abstract

A method for producing a packaging laminate (1), wherein an outer sealing layer (2) with a polyethylene content of at least 80% by volume is bonded to a substrate layer (4) with a polyethylene content of at least 60% by volume, preferably at least 70% by volume and most preferably at least 80% by volume and to a thermal stability layer (6), wherein the thermal stability layer (3) is disposed externally, opposite the sealing layer (2) and the substrate layer (4) is disposed between the sealing layer (2) and the thermal stability layer (3), characterized in that the thermal stability layer (3) is produced from ethylene-vinyl alcohol copolymer and the thickness of the thermal stability layer (3) represents up to 10%, preferably up to 5%, of the total thickness of the packaging laminate (1), but at most 10 μm.

Description

Recyclable packaging laminate with improved heat resistance during sealing The present invention relates to a recyclable packaging laminate and a process for producing such a packaging laminate, wherein an outer sealing layer with a polyethylene content of at least 80% by volume is bonded to a substrate layer with a polyethylene content of at least 60% by volume and to a thermal stability layer, wherein the thermal stability layer is disposed externally, opposite the sealing layer, and the substrate layer is disposed between the sealing layer and the thermal stability layer. Packaging laminates are used in the packaging industry, and these laminates must have different properties depending on the application.Such packaging laminates are generally multilayer plastic films produced by extrusion, co-extrusion (in both cases using flat film and blown film processes), or lamination (bonding individual layers with a laminating adhesive, also known as extrusion lamination), or mixtures thereof. Packaging laminates may also incorporate non-plastic layers, such as aluminum or paper. They typically also feature an outer sealing layer for heat-sealing to form the desired packaging, such as a bag or sack. In other applications, packaging laminates may also be made as shrink film, which, depending on the application, can be produced in a sealable but unprinted form, e.g.for packaging larger portions of meat. A typical requirement for packaging laminate is a barrier function against water vapor, oxygen, and / or aroma. For this purpose, packaging laminate generally contains a barrier layer of aluminum or a suitable barrier polymer, such as ethylene-vinyl alcohol copolymer (EVOH) or polyamide (PA). A barrier layer, for example, of EVOH, is usually sandwiched between two other laminate layers, since the barrier properties of EVOH can be impaired by moisture (including atmospheric humidity). At the same time, other layers may still be contained to give the packaging laminate the desired properties, such as toughness, rigidity, shrinkage capacity, tear resistance, etc. In order to process the packaging laminate easily, the packaging laminate also cannot be warped or curled (so called curling), so symmetrical layer structures are usually used. Furthermore, the properties of packaging laminate can be modified through unidirectional or bidirectional orientation. One type of orientation can be achieved during the extrusion process, for example, in a multiple bubble extrusion process. However, orientation is usually only achieved after the orientation process by stretching the packaging laminate in the machine direction (the longitudinal direction of the packaging laminate) and / or in the transverse direction (normal to the longitudinal direction). This orientation of the packaging laminate primarily improves stiffness, tensile strength, and toughness. Additionally, orientation allows for the shrinkage property of the packaging laminate, so that even inherently opaque materials, such as HDPE, become more transparent after stretching.For recyclability reasons, it is also possible to make an effort to produce packaging laminates of a variety, i.e., for example, packaging laminates based only on polyethylene or as a mixture of polyethylene-based plastics with compatible plastics with a view to recyclability in acceptably low quantities. A sealing layer is typically made of a polyolefin, generally polypropylene (PP) or polyethylene (PE) in various densities such as LLDPE, LDPE, MDPE, or HDPE, and also as blends, where other materials are obviously also considered for the sealing layer. For sealing, for example, in the production of packaging such as bags, the folded packaging laminate is compressed between two heated sealing jaws. When sealing containers with cover films, a packaging laminate is also compressed between heated sealing jaws. This melts the sealing medium, so that after cooling, a bond is formed between the adjacent sealing layers. In this case, it is naturally desirable to reduce the sealing time as much as possible, since this can increase productivity on a packaging machine.This can be achieved, among other things, with higher sealing temperatures, since this allows heat to be conducted more quickly from the outside to the sealing point. However, the maximum possible sealing temperature naturally depends, in particular, on the material of the outermost layer of the packaging laminate facing the sealing jaw, and above all, on the melting point of this material. For example, HDPE has a melting point of approximately 130 °C. When starting from a minimum required sealing temperature of 80 °C (or slightly higher), it is clear that the sealing window (the temperature range within which sealing must occur) is narrow. This complicates process management and also reduces the achievable sealing times. This could be countered by using materials with high thermal stability, such as polyester (PET), in the outermost layer. However, a packaging laminate made from PE materials with a PET layer cannot be recycled. A blend of polypropylene (PP) with the HDPE outer layer would also increase thermal stability. But in this case, it would also negatively impact the laminate's recyclability. A blend of HDPE with a cycloolefin copolymer (COC) would also increase thermal stability and be acceptable from a recyclability standpoint by adding small amounts of COC. However, COCs are more expensive, making them rather unattractive for use in packaging laminates, where cost is a critical factor. US patent 2018 / 0079188 A1 describes, for example, a recyclable polyethylene laminate with a core layer of LLDPE, surrounded on each side by a layer of HDPE. The two HDPE layers must be at least four times thicker than the core layer. To increase thermal stability, it is proposed to blend a PP or COC with HDPE on one outer layer or to apply a PP or COC layer. EP 764519 A1 discloses a deep-drawing laminate with an outer EVOH layer, which must form a barrier layer and provide the laminate with the thermal stability required for deep drawing. Simultaneously, the EVOH layer must prevent the laminate from sticking to the deep-drawing mold. The barrier properties of EVOH are known to be impaired by moisture, which is why EVOH is not commonly used in an outer layer. Due to the intended barrier properties of the EVOH layer, the EVOH layer in the laminate of EP 764519 A1 is therefore relatively thick, comprising 1–30% of the total laminate thickness, in order to still achieve a sufficient barrier effect. However, since EVOH is an expensive material, this significantly increases the cost of the deep-drawing laminate. An objective of the present invention is to specify a recyclable packaging laminate exhibiting improved thermal stability for sealing, as well as to specify a production process for such a packaging laminate. This objective is achieved because the thermal stability layer is made of ethylene-vinyl alcohol copolymer, and its thickness represents up to 10%, preferably up to 5%, of the total thickness of the packaging laminate, but at most 10 µm. It has been surprisingly found that a thin layer of EVOH on the outer surface of the packaging laminate can significantly increase its thermal stability for sealing, without compromising recyclability. Despite its small thickness, the sealing temperature can be significantly raised in this way, shortening sealing times and making the sealing process more flexible, as it also significantly increases the sealing window. The sealing process can thus be made faster, safer, and more flexible, without the outer EVOH layer sticking to the sealing jaw or creating unwanted optical marks on the packaging laminate. Additionally, a bonding layer can be advantageously placed between the substrate layer and the thermal stability layer to increase adhesion in the packaging laminate. Packaging laminate can be advantageously produced by co-extrusion or lamination, or as a combination of both, which increases the possibilities for production. The specific invention is explained in more detail below with reference to Figures 1 to 5, which schematically illustrate, by way of example, advantageous and non-limiting configurations of the invention. In this regard, it shows Fig. 1 a first configuration of a packaging laminate according to the invention, Fig. 2 a second configuration of a packaging laminate according to the invention, Fig. 3 another advantageous configuration of a packaging laminate according to the invention, Fig. 4 a bag produced by sealing a packaging laminate according to the invention and Fig. 5 the closure of a container by sealing a covering film of a packaging laminate according to the invention. Fig. 1 shows a packaging laminate 1 according to the invention with two outer layers, a sealing layer 2 and a thermal stability layer 3 and a substrate layer 4 arranged in the middle. The substrate layer 4 is primarily made of polyethylene (PE) and is therefore recyclable. Advantageously, the substrate layer 4 has a PE content, preferably high-density polyethylene (HDPE), of at least 60% by volume, preferably at least 70% by volume, and most preferably at least 80% by volume. In this respect, the PE content can reach up to 100% by volume, although due to the usual additives in packaging laminates 1 (such as anti-slip additives, anti-blocking additives, dyes, fillers, etc.), the PE content is generally never reached. The remainder (along with any additives) is a recyclable polyolefin material, which does not impair recyclability.Compatible polyolefin materials include virtually any type of polyethylene, particularly ethylene copolymers such as ethylene-vinyl acetate copolymer (EVA), ethyl methacrylate ester (EMA), ethylene-acrylic acid copolymer (EAA), or ethylene-butyl acrylate copolymer (EBA). Polypropylene (PP) or a cycloolefin copolymer (COC) can also be used as compatible polyolefin materials up to a maximum of 20% by volume. For PP, a random polypropylene copolymer with ethylene as a comonomer (usually 5 to 15%), a polypropylene copolymer with ethylene, or a polypropylene homopolymer is preferred. These are sufficiently compatible with linear PE types such as mLLDPE, LLDPE, or HDPE to achieve at least limited recyclability. In substrate layer 4, a specific type of PE can be used, but a mixture of different types of PE, or different types of PE in copolymer or multilayer form, can also be used. HDPE is understood to be a type of PE with a density between 0.94 and 0.97 g / cm³. Other possible types of PE include, for example, linear low-density polyethylene (LLDPE) (with a density between 0.87 and 0.94 g / cm³), low-density polyethylene (LDPE) (with a density between 0.915 and 0.935 g / cm³), or metallocene linear low-density polyethylene (mLLDPE). In an advantageous configuration, HDPE is used primarily in substrate layer 4, with at least 60% by volume, preferably at least 70% by volume, and most preferably at least 80% by volume. The remainder is a compatible polyolefin material, which does not impair recyclability, for example, as described above. The additives are added in small quantities (at most 5% by volume) and therefore do not impair the recyclability of the packaging laminate 1. In this regard, PE and the compatible polyolefin material may be present in substrate layer 4 as a mixture. However, substrate layer 4 may also be constructed (extruded or co-extruded) in a multi-layered form with one or more layers of PE and one or more layers of the compatible polyolefin material. The thickness of substrate layer 4 is preferably from 5 to 35 µm. A substrate layer 4 could be made, for example, with a central PE layer and two HDPE layers connected to it, preferably an HDPE layer with a low proportion of mLLDPE or LLDPE (for example, 5 to 10% by volume) or corresponding layers of mLLDPE or LLDPE. In such a symmetrical structure, the two outer layers of substrate layer 4 can also be made thicker than the inner layers, i.e., for example, in the form of an x / 1 / x structure with x > 1, in particular x = 1, 5, 2, 3, or 4. The thermal stability layer 3 is made of ethylene-vinyl alcohol copolymer (EVOH) and has a thickness of at most 10%, preferably at most 5%, of the total thickness of the packaging laminate 1, i.e., at most 3 to 10 µm with a typical laminate thickness between 30 and 100 µm. However, the laminate thickness of the packaging laminate 1 can also naturally be greater than 100 µm, in which case the thickness of the thermal stability layer 3 is no greater than 10 µm. Due to the small thickness of the thermal stability layer 3, the recyclability of the packaging laminate 1 is not compromised. EVOH with a PE content of at most 50 mol%, preferably between 30 mol% and 50 mol%, is used for the thermal stability layer 3 to achieve a sufficiently high melting temperature for the thermal stability layer 3.Depending on the PE content in the EVOH, a melting point of at least 155 °C, preferably at least 165 °C, is achieved. The thermal stability layer 3 only partially provides a barrier effect in the packaging laminate 1, despite the use of a barrier polymer. Due to its small thickness and its position on the outside of the packaging laminate 1, the barrier properties of the EVOH (particularly as a gas barrier, e.g., against oxygen) are significantly reduced, partly due to humidity, including atmospheric humidity, during production and storage. The EVOH thermal stability layer 3 cannot, on its own, provide the typically required barrier properties and therefore cannot be used primarily as a barrier layer. Preferably, only EVOH is used in stability layer 3. However, a mixture of EVOH with a small proportion of an ethylene (co)polymer, up to a maximum of 20% by volume, could also be used. The sealing layer 2 is primarily made of PE material, where the proportion of PE in the total polymer quantity of sealing layer 2, without any other fillers or added mineral additives, must be at least 80% by volume. Various types of PE can be used, such as LDPE, LLDPE, MDPE, and HDPE, either individually, as a blend, in the form of copolymers, or in multilayer form. Depending on the application of the packaging laminate 1, the thickness of sealing layer 2 is typically between 20 and 100 µm. In sealing layer 2, for the intended recyclability, the remaining material (along with any small amounts of additives) will naturally be made of a compatible polyolefin material, as described above. Sealing layer 2 can also be multilayered, for example, by extrusion, coextrusion, or lamination. By using mainly PE and compatible materials in the packaging laminate 1, a particularly recyclable laminate can be produced, which can be recycled easily and economically using methods common in mechanical recycling. Furthermore, it was surprisingly found that the EVOH thermal stability layer 3 can significantly improve the thermal stability during the sealing of packaging laminate 1, despite its very small thickness of at most 10%, preferably at most 5%, of the total thickness of packaging laminate 1 (absolutely at most 10 µm). Tests have shown that the sealing jaw temperature during the sealing of packaging laminate 1 can be significantly increased due to the improved thermal stability. When using an EVOH with 44 mol% PE, the sealing jaw temperature can be raised, for example, from a maximum of 130 °C in the case of HDPE in the outer layer to 150 °C, and in the case of an EVOH with 32 mol% PE to at least 160 °C, without the EVOH outer layer sticking to the sealing jaw or causing any optically undesirable markings on packaging laminate 1.The higher the melting point of EVOH, the higher the sealing jaw temperature can be. Since barrier properties must be considered, the PE content in the EVOH can be optimized for thermal stability. In this case, sufficient thermal stability means that sealing can be performed at a certain temperature without compromising the EVOH's thermal stability layer 3. Therefore, the melting point of the EVOH must be correspondingly high. Between the thermal stability layer 3 and the substrate layer 4, a bonding layer 5 may also be arranged, as shown in Fig. 2, to potentially increase the composite adhesion between the thermal stability layer 3 and the substrate layer 4. The bonding layer 5 therefore primarily serves to improve the adhesion between the thermal stability layer 3 and the substrate layer 4, to achieve sufficient composite adhesion in the packaging laminate 1, in particular to reliably prevent unwanted delamination of the thermal stability layer 3 and the substrate layer 4. Additionally, the bonding layer 5 may increase toughness.The appropriate bonding layers 5 are preferably made of polymers with high polarity, for example, polymers compatible with polyethylenes for recycling purposes, such as maleic anhydride-modified polyolefin (such as PE or PP), ethylene vinyl acetate (EVA) copolymers, ethylene-acrylic acid (EAA) copolymers, or ethylene-butyl acrylate (EBA) copolymers, or similar polyolefin copolymers. The thickness of a bonding layer 5 is typically 1 to 5 pm. Regardless of the bonding layer 5 between the thermal stability layer 3 and the substrate layer 4, a barrier layer 6 may be provided in the packaging laminate 1 between the sealing layer 2 and the substrate layer 4, as shown in Fig. 3. The barrier layer 6 is preferably made of a barrier polymer, i.e., a polymer with sufficient barrier properties, particularly against oxygen, hydrogen, and / or aroma. The barrier polymer is preferably a polyamide (PA) or an ethylene-vinyl alcohol (EVOH) copolymer. EVOH is preferred as the barrier polymer. When using a barrier layer 6, it is important that the barrier layer 6 and the thermal stability layer 3 together represent no more than 10%, and preferably no more than 5%, of the total thickness of the packaging laminate 1, so that the proportion of barrier polymer in the packaging laminate 1 does not become too high, which would impair recyclability.The barrier layer 6 itself has a thickness of at most 10%, preferably 5%, of the total thickness of the packaging laminate 1, i.e., at most 3 to 10 µm in the case of a typical laminate thickness between 30 and 100 µm. However, the combined thickness of the barrier layer 6 and the thermal stability layer 3 is independent of the total thickness of the packaging laminate 1, which in any case is absolutely limited to a maximum of 10 µm. The small thickness of the barrier layer 6 thus does not compromise recyclability. Additionally, between barrier layer 6 and substrate layer 4 and / or between barrier layer 6 and sealing layer 2, another suitable bonding layer could also be provided, for example, as explained above, to increase compound adhesion. Packaging laminate 1 can be produced, for example, by coextrusion. Preferably, the blown film or flat film extrusion process is used. However, it is also possible that the thermal stability layer 3 and the substrate layer 4 can be co-extruded with the connecting layer 5 in between, forming a first laminate layer 7 (e.g., Fig. 2). In the case of a connecting layer 5, the connection could also be made by lamination or extrusion lamination using the connecting layer 5 as the laminating medium. The laminate layer 7 could also be configured in this way with a barrier layer 6 (e.g., Fig. 3). If a barrier layer 6 is provided, a particularly advantageous symmetrical structure of the first laminate layer 7 is achieved, for example, with two outer EVOH layers in the laminate layer 7 and other layers in between, where the two EVOH layers can also be of the same thickness.Thanks to the symmetrical structure, the first layer of laminate 7 has little to no tendency to curl, which facilitates the subsequent processing of the laminate 7 layer. This first laminate layer 7 can then be bonded to the sealing layer 2, for example, by extrusion lamination or extrusion coating of the sealing layer 2 onto the first laminate layer 7, or by bonding with a suitable laminating medium. In the case of lamination, the sealing layer 2 is bonded to the first laminate layer 7 using a suitable laminating adhesive, for example, polyurethane-based adhesives or polyolefin copolymers in extrusion lamination. The thickness of the laminating adhesive is preferably 2 to 5 g / m² for standard polyurethane-based adhesives or 5 to 20 g / m² for extrusion lamination. If a barrier layer 6 is provided in the first laminate layer 7, it is advantageous for the first laminate layer 7 to connect very quickly after processing with the sealing layer 2, in order to reduce water absorption by the barrier layer 6. It may also be necessary or reasonable to protect the film roll with the first laminate layer 7 from water absorption until it connects with the sealing layer 2 by means of suitable packaging. Additionally, the first laminate layer 7 can be elongated before joining with the sealing layer 2 in the machine direction (generally the longitudinal or extrusion direction). In this respect, the elongation ratio is preferably at least 4:1 in the machine direction. This elongation can be performed in-line (i.e., immediately after the production of the first laminate layer 7) or off-line (i.e., at a later time after production). Unidirectional elongation is significantly simpler and more economical than bidirectional elongation, thus reducing production costs. However, the first laminate layer 7 can also be elongated bidirectionally. It should be noted that in blown film and flat film extrusion, the extrusion gap (1.5 to 2.5 mm in blown film) or the extrusion nozzle gap is significantly larger than the final thickness of the extruded film (typically between 10 and 200 µm). To achieve this, the extruded melt is stretched at temperatures well above the melting point of the polymer being extruded, thus obtaining the final thickness. In blown film extrusion, the melt is typically stretched, for example, in the transverse direction by approximately a factor of 2 to 3 (the so-called blowing ratio) and in the longitudinal direction by a factor of 1:10 to 1:100 (the so-called drawing ratio).But this extension during extraction cannot be compared in effect with the elongation of a plastic film, since the elongation is usually carried out at temperatures just below the melting point of the polymer, in order to orient the disordered polymers and partial crystalline areas by elongating in the direction of elongation. Thanks to the elongation, high transparency is also achieved, primarily in the substrate layer 4. Additionally, the elongation increases the barrier properties of the barrier layer 6 by approximately three to four times compared to a similar non-elongated barrier polymer, allowing the use of a less expensive barrier polymer with the same barrier effect. This also significantly reduces the costs of the first laminate layer 7 and, consequently, the packaging laminate 1. Preferably, the first layer of laminate 7 is produced using the blown film extrusion process, as this results in a smaller edge section due to the production process, leading to lower packaging laminate 1 costs, especially when using more expensive barrier polymers. More viscous HDPE materials with a Mass Flow Index (MFI) of less than 3 can also be used in blown film extrusion. Such HDPE materials have a higher molecular weight and improved mechanical properties, which is advantageous for use in packaging laminate 1. Furthermore, the barrier layer 6 can be metallized on the side facing the sealing layer 6 to enhance the barrier effect and / or coated (e.g., with aluminum oxide or silicon oxide) to further improve the barrier effect and / or adhesion before the first laminate layer 7 is bonded to the sealing layer 2. Metallization with aluminum is preferred. The barrier layer 6 and / or the substrate layer 4 can also be printed, and for this purpose, the surface to be printed can be pretreated, for example, with corona or flame treatment, to improve the adhesion of the printed layer to the barrier layer 6 and / or the substrate layer 4. In this case, standard printing processes can be used, such as gravure or flexographic printing. Such treatments naturally occur after any necessary elongation. By printing at least one layer of the first laminate layer 7 or also the side of the sealing layer 2 facing the first laminate layer 7 with a barrier lacquer, for example, polyvinyl alcohol (PVOH), the barrier effect of the packaging laminate 1 can be further increased. Such lacquer layers cannot be applied very thinly, typically in the range of 0.5 to 2.0 g / m2, and consequently impair the recyclability of the packaging laminate 1. The packaging laminate 1 according to the invention is commonly used for the production of packaging, for example, for food. For this purpose, the packaging laminate 1 can be cut and shaped into the packaging 10, for example, by folding and sealing, as shown in Fig. 4, where in the example a bag 11 with a longitudinal seal 12 and two transverse seals 13. However, the packaging laminate 1 can also be processed directly on known continuous packaging machines, e.g., so-called form-filling machines or tubular bag machines. For sealing, the folded packaging laminate 1 is compressed in a known manner at the sealing point between two heated sealing jaws. In this respect, the thermal stability layer 3 of the packaging laminate 1 faces the sealing jaws.However, the cover plates 21 for closing the containers 20 as packaging 10 can also be punched from the packaging laminate 1, as shown in Fig. 5. In all cases, the sealing is done to the sealing layer 2 of the packaging laminate 1, either against its own sealing layer (e.g., in folded packages such as bags or sacks) or against another sealing layer (e.g., on a sealing edge 22 of a container 20). In this respect, the sealing layer 2 in the finished packaging faces the packaged product, while the thermal stability layer 3 faces outwards.

Claims

1. A method for producing a packaging laminate (1), wherein an outer sealing layer (2) with a polyethylene content of at least 80% by volume is bonded to a substrate layer (4) with a polyethylene content of at least 60% by volume, preferably at least 70% by volume and most preferably at least 80% by volume, and to a thermal stability layer (6), wherein the thermal stability layer (3) is disposed externally, opposite the sealing layer (2) and the substrate layer (4) is disposed between the sealing layer (2) and the thermal stability layer (3), characterized in that the thermal stability layer (3) is produced from ethylene-vinyl alcohol copolymer and the thickness of the thermal stability layer (3) represents up to 10%, preferably up to 5%, of the total thickness of the packaging laminate (1), but at most 10 µm. 2.A method according to claim 1, characterized in that a thermal stability layer (3) is made of an ethylene-vinyl alcohol copolymer with a polyethylene content of at most 50 mol%, preferably between 30 mol% and 50 mol%.

3. A method according to claim 1 or 2, characterized in that a barrier layer (6) of an ethylene-vinyl alcohol copolymer or polyamide is provided between the sealing layer (2) and the substrate layer (4), wherein the thickness of the thermal stability layer (3) and the thickness of the barrier layer (6) together represents up to 10%, preferably up to 5%, of the total thickness of the packaging laminate (1), but at most 10 µm.

4. A method according to claim 1 or 2, characterized in that a bonding layer (5) is provided between the substrate layer (4) and the thermal stability layer (3). 5.A method according to any one of claims 1 to 4, characterized in that the individual layers of the packaging laminate (1) are coextruded.

6. A method according to claim 1 or 4, characterized in that the substrate layer (4) and the thermal stability layer (3) or the substrate layer (4), the connecting layer (5), and the thermal stability layer (3) are coextruded and then connected to the sealing layer (2).

7. A method according to claim 6, characterized in that the coextruded substrate layer (4) and the thermal stability layer (3) or the coextruded substrate layer (4), connecting layer (5), and thermal stability layer (3) are elongated in the machine direction and / or in the transverse direction before being connected to the sealing layer (2). 8.A method according to claim 3 or 4, characterized in that the barrier layer (6), the substrate layer (4), and the thermal stability layer (3), or the barrier layer (6), the substrate layer (4), the connection layer (5), and the thermal stability layer (3), are coextruded and then connected to the sealing layer (2).

9. A method according to claim 8, characterized in that the coextruded barrier layer (6), substrate layer (4), and thermal stability layer (3), or the coextruded barrier layer (6), substrate layer (4), connection layer (5), and thermal stability layer (3), are elongated in the machine direction and / or in the transverse direction before being connected to the sealing layer (2).

10. A method according to claim 3, characterized in that the barrier layer (6) is metallized or coated. 11.Packaging laminate with an outer sealing layer (2) having a polyethylene content of at least 80% by volume, bonded to a substrate layer (4) having a polyethylene content of at least 60% by volume, preferably at least 70% by volume and most preferably at least 80% by volume, and with a thermal stability layer (3), wherein the thermal stability layer (3) is disposed externally, opposite the sealing layer (2) and the substrate layer (4) is disposed between the sealing layer (2) and the thermal stability layer (3), characterized in that the stability layer (3) is produced from ethylene-vinyl alcohol copolymer and the thickness of the thermal stability layer (3) represents up to 10%, preferably up to 5%, of the total thickness of the packaging laminate (1), but at most 10 µm. 12.Packaging laminate according to claim 11, characterized in that the thermal stability layer (3) is an ethylene-vinyl alcohol copolymer with a polyethylene content of at most 50 mol%, preferably between 30 mol% and 50 mol%.

13. Packaging laminate according to claim 11 or 12, characterized in that a barrier layer (6) of an ethylene-vinyl alcohol copolymer or polyamide is disposed between the sealing layer (2) and the substrate layer (4), wherein the thickness of the thermal stability layer (3) and the thickness of the barrier layer (6) together represent up to 10%, preferably up to 5%, of the total thickness of the packaging laminate (1), but at most 10 µm.

14. Packaging laminate according to claim 13, characterized in that the barrier layer (6) is metallized or coated. 15.Packaging laminate according to any of claims 11 to 14, characterized in that a connection layer (5) is arranged between the substrate layer (4) and the thermal stability layer (3).

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