High-barrier packaging laminate

Abstract

High-barrier packaging laminate (1) comprising a first laminate layer (2), a second laminate layer (3) and a third laminate layer (4), wherein the first laminate layer (2) is a co-extruded and stretched composite of a substrate layer (21) having a PE or PP content of at least 60 vol%, a bonding layer (23) and a barrier layer (22) made of a barrier polymer, preferably polyamide or ethylene-vinyl alcohol copolymer or polyvinyl alcohol or butenediol vinyl alcohol copolymer, with a thickness of at most 20% of the total thickness of the first laminate layer (2), wherein the bonding layer (23) is arranged between the substrate layer (21) and the barrier layer (22), wherein the first laminate layer (2) is bonded on one side to the second laminate layer (3) by a further bonding layer (5) and on the opposite second side to the third laminate layer (4) by a further bonding layer (6),characterized in that the packaging laminate (1) has a WVTR value of less than 0.1 g / (m², 2 *24h), preferably less than 0.05 g / (m²) 2 *24h) by providing the first laminate layer (2) with a barrier coating (24, 25) on both sides, or the first laminate layer (2) with a first barrier coating (24) and a second barrier coating (25) on one side, or the first laminate layer (2) with a first barrier coating (24) on one side and additionally the second laminate layer (3) with a second barrier coating (25) on the side facing the first laminate layer (2) and / or the third laminate layer (4) with a second barrier coating (25) on the side facing the first laminate layer (2).

Description

[0001] The present invention relates to a high-barrier packaging laminate comprising a first laminate layer, a second laminate layer and a third laminate layer, wherein the first laminate layer is a co-extruded and stretched composite of a substrate layer having a PE or PP content of at least 60 vol%, a bonding layer and a barrier layer made of a barrier polymer, preferably polyamide or ethylene-vinyl alcohol copolymer, with a thickness of at most 20% of the total thickness of the first laminate layer, wherein the bonding layer is arranged between the substrate layer (4) and the barrier layer, wherein the first laminate layer is bonded to the second laminate layer by a further bonding layer on one side and to the third laminate layer by a further bonding layer on the opposite second side.

[0002] The packaging industry uses packaging laminates made of plastic materials, which are required to have different properties depending on the application. These packaging laminates are typically multilayer plastic films produced by extrusion, co-extrusion (in both cases, both flat film and blown film), or lamination (bonding individual layers using a laminating agent, such as a laminating adhesive), or combinations thereof. The packaging laminate usually also has an outer sealing layer to allow it to be heat-sealed into the desired packaging, such as a bag, sack, pouch, etc.

[0003] A typical requirement for a packaging laminate is a barrier function against water vapor, oxygen, and aroma. For this purpose, the packaging laminate usually contains a barrier layer made of aluminum or a suitable barrier polymer, such as ethylene-vinyl alcohol copolymer (EVOH), polyamide (PA), polyvinyl alcohol (PVOH), or butenediol vinyl alcohol copolymer (BVOH). Additional layers may also be included to give the packaging laminate desired properties, such as toughness, stiffness, shrinkage resistance, tear resistance, etc. A sealing layer is typically made of a polyolefin, usually polypropylene (PP) or polyethylene (PE) in various densities such as LLDPE, LDPE, MDPE, or HDPE.

[0004] Furthermore, it is known to modify the properties of packaging laminates by mono- or biaxially orienting one or more of the layers that comprise the laminate. Such orientation can be achieved during the extrusion process, for example, in a multiple bubble extrusion process, or after extrusion by stretching the laminate in the machine direction (longitudinal direction) and / or in the transverse direction (perpendicular to the machine direction). Orienting the packaging laminate can improve its mechanical properties, particularly its stiffness, tensile strength, and toughness. Furthermore, orientation can also result in higher transparency after stretching even inherently opaque materials, such as HDPE.Last but not least, the barrier properties of the packaging laminate can also be improved, especially if barrier polymers such as EVOH, PA, PVOH or BVOH are used in the packaging laminate.

[0005] Such packaging laminates are known from WO 2018 / 202479 A1 or WO 2020 / 038579 A1. These documents describe a packaging laminate with a core layer in the form of a barrier layer (EVOH or PA) / bonding layer / HDPE (min. 60 vol%), which is oriented unidirectionally or bidirectionally, wherein the core layer is bonded on one side to a PE sealing layer (min. 70 vol%) and on the other side to another multilayer laminate layer. The barrier layer provides a certain barrier effect.

[0006] For certain applications, such as hermetically sealed packaging for instant coffee powder or powdered milk, high-barrier films are required. In the context of packaging laminates, "high barrier" refers to a barrier effect against water vapor (Water Vapor Transmission Rate (WVTR)) of <0.1 g / (m²). 2 *24h), preferably <0.05 g / (m²) 2 *24h). The WVTR is measured according to ISO 15106-2 at 38°C / 90% rh to 0% rh or ASTM F1249. The water vapor permeability (WVTR) can be measured, for example, with the Permatran™ 3 / 34G measuring device from Mocon, with the arrangement such that the barrier layer in the packaging laminate is measured facing the sensor of the measuring device in the measuring cell.

[0007] High-barrier films of this type are currently primarily achieved using aluminum foil with a thickness greater than 5 µm as the barrier layer in the packaging laminate. The major disadvantage of a packaging laminate with an aluminum foil barrier layer is its difficult recyclability. Recyclability, as defined in the application, means that at least a large proportion of the packaging laminate materials can be economically recovered through mechanical recycling and further processed. Further processing is understood to mean that the recovered materials, possibly mixed with virgin raw materials, can be extruded again to produce high-quality packaging laminates.A composite of plastics and aluminum is either impossible or extremely difficult to separate, meaning that a large proportion of the materials used cannot be recovered, or only with very high costs (so that recycling would at least not be economically viable). Similar recycling problems arise when different plastics, incompatible with regard to recycling, are used in the packaging laminate. To increase or achieve the recyclability of a packaging laminate, the aim is therefore to use packaging laminates that are as pure as possible, i.e., packaging laminates consisting primarily of only one type of plastic, such as polyethylene (PE) or polypropylene (PP). PE or PP content of at least 70% by volume, preferably at least 80% by volume or even higher, is targeted.Small amounts of foreign matter, especially in quantities of less than 20 vol%, such as a small amount of barrier material like EVOH or PA, do not impair recyclability.

[0008] One of the objectives of the present invention is to provide a recycling-friendly, high-barrier packaging laminate.

[0009] This task is solved by a packaging laminate with a WVTR value of less than 0.1 g / (m²). 2 *24h), preferably less than 0.05 g / (m²) 2*24h). The WVTR is measured according to ISO 15106-2 at 38°C / 90% rh to 0% rh or ASTM F1249. This is achieved by applying a barrier coating to both sides of the first laminate layer, or by applying a first and second barrier coating to one side of the first laminate layer, or by applying a first barrier coating to one side of the first laminate layer and additionally applying a second barrier coating to the side of the second laminate layer facing the first laminate layer, and / or by applying a second barrier coating to the side of the third laminate layer facing the first laminate layer. The additional barrier coatings, in combination with the first laminate layer already having an integrated barrier layer, allow for a simple barrier effect without compromising recyclability.

[0010] The barrier effect can be further increased by laminate constructions as claimed in the dependent requirements.

[0011] The first barrier coating and / or the second barrier coating (the further first barrier coating and / or the further second barrier coating) is advantageously designed as a metallization or as a SiOx coating or AIOx coating or as an organically modified SiOx coating, or a mixture of at least two of the aforementioned coatings, or as a barrier lacquer based on PVOH, EVOH or BVOH, or a copolymer of PVOH, EVOH or BVOH or a mixture of at least two of the aforementioned barrier polymers, which allows for very thin barrier coatings.

[0012] The present invention is described below with reference to the Fig. Sections 1 to 7 explain in more detail, illustrating advantageous embodiments of the invention in an exemplary, schematic, and non-restrictive manner. Fig. 1 the basic structure of a packaging laminate according to the invention, Fig. 2 the basic structure of the first laminate layer of the packaging laminate according to the invention, Fig. 3 an embodiment of the barrier coatings in the packaging laminate according to the invention, Fig. 4 a further embodiment of the barrier coatings in the packaging laminate according to the invention, Fig. 5 a further embodiment of the barrier coatings in the packaging laminate according to the invention, Fig. 6 a further embodiment of the barrier coatings in the packaging laminate according to the invention and Fig. 7. A design of the packaging laminate with two first laminate layers with barrier coatings.

[0013] All standards mentioned in the application are the respective latest versions as of the application date.

[0014] The Fig. Figure 1 shows a packaging laminate 1 according to the invention, comprising a first laminate layer 2, a second laminate layer 3 connected to it at a first side of the first laminate layer 2, and a third laminate layer 4 connected to it at a second side of the first laminate layer 2 opposite the first side. A connecting layer 5 serves to connect the first laminate layer 2 to the second laminate layer 3, and a connecting layer 6 serves to connect the first laminate layer 2 to the third laminate layer 4. The resulting structural composition of the packaging laminate 1 is thus: second laminate layer 3 / connecting layer 5 / first laminate layer 2 / connecting layer 6 / third laminate layer 4." The """ here indicates that two layers are directly connected to each other, i.e., lie directly adjacent to one another.

[0015] The first laminate layer 2 in the packaging laminate 1 is designed as described in WO 2018 / 202479 A1 or WO 2020 / 038579 A1.

[0016] The first laminate layer 2 therefore has an asymmetrical layer structure and, in one embodiment, consists of a substrate layer 21 and a barrier layer 22, which are connected to each other by a bonding layer 23. Thus, the structural structure of the first laminate layer 2 is: substrate layer 21 / bonding layer 23 / barrier layer 22.

[0017] The thickness of the first laminate layer 2 is preferably 10 to 50µm.

[0018] The substrate layer 21 has a high-density polyethylene (HDPE) content of at least 60 vol%, preferably at least 70 vol%, and most preferably at least 80 vol%. The HDPE content can approach 100 vol%, although due to common additives (such as slip additives, antiblocking additives, fillers, etc.), 100 vol% is generally never reached. Additives are usually added in small quantities, preferably a maximum of 10 vol%, and particularly advantageously a maximum of 5 vol%, to the substrate layer 21. As is common practice in plastics engineering, a PE layer with a density between 0.94 and 0.97 g / cm³ is used beneath the HDPE. 3with a weakly branched polymer chain, high crystallinity (70–90%), a modulus of elasticity (tensile modulus) of 700–1500 MPa, and a melting point of 125–140°C. For the purposes of this application, medium-density polyethylene (MDPE) with a density of ≥ 0.94 g / cm³ is also understood to be such high-density polyethylene (HDPE). The remainder of the substrate layer 21 (apart from any additives) is a polyolefin material compatible with regard to recyclability, preferably a linear low-density polyethylene (LLDPE) (with a density between 0.87–0.94 g / cm³). 3 ), a low-density polyethylene (LDPE) (with a density between 0.915-0.935 g / cm³) 3) or a linear metallocene low-density polyethylene (mLLDPE), particularly to increase toughness. These PE types also differ in their degree of branching and crystallinity, especially compared to HDPE. In principle, any type of polyethylene is suitable as a recyclable polyolefin material, particularly ethylene copolymers such as ethylene-vinyl acetate copolymer (EVA), ethyl methacrylate (EMA), ethylene / acrylic acid copolymer (EAA), or ethylene-butyl acrylate copolymer (EBA). Polypropylene (PP) or a cycloolefin copolymer (COC) can also be used as a recyclable polyolefin material, up to a maximum of 20 vol% of the substrate layer 21.In the case of PP, preferably a polypropylene random copolymer with ethylene as a comonomer (usually 5 to 15%), a polypropylene copolymer with ethylene or a polypropylene homopolymer that is sufficiently compatible with linear PE types, such as mLLDPE, LLDPE or HDPE, is used to achieve at least limited recyclability.

[0019] The HDPE and the compatible polyolefin material can be present as a mixture in substrate layer 21. However, substrate layer 21 can also be multilayered (extruded or co-extruded) with one (or more) HDPE layers and one (or more) layers of the compatible polyolefin material.

[0020] The thickness of the substrate layer 21 is preferably 5 to 35µm.

[0021] The barrier layer 22 consists of a barrier polymer, i.e., a polymer with sufficient barrier properties, particularly against oxygen, water vapor, and / or aroma. The barrier polymer is preferably a polyamide (PA), an ethylene-vinyl alcohol copolymer (EVOH), a polyvinyl alcohol (PVOH), or a butenediol vinyl alcohol copolymer (BVOH). EVOH is preferably used as the barrier polymer.

[0022] The barrier layer 22 has a thickness of at most 20%, preferably 5 to 10%, of the total thickness of the first laminate layer 2, i.e., a maximum of 2 to 8 µm. The small thickness of the barrier layer 22 does not impair recyclability because the amount of barrier polymer is sufficiently small compared to the main component PE.

[0023] The bonding layer 23 serves to connect the barrier layer 22 and the substrate layer 21. Sufficient adhesion is to be achieved, in particular to reliably prevent undesired delamination of the first laminate layer 2. Suitable bonding layers 23 preferably consist of polymers with increased polarity, for example, based on maleic anhydride-modified polyolefins (such as PE or PP), ethylene-vinyl acetate copolymer (EVA), ethylene / acrylic acid copolymer (EAA), ethylene-butyl acrylate copolymer (EBA), or similar polyolefin copolymers.

[0024] The thickness of a bonding layer 23 of the first laminate layer 2 is a maximum of 20%, preferably a maximum of 10%, of the total thickness of the first laminate layer 2, typically 2 to 8 µm, preferably 1 to 5 µm. The small thickness of the bonding layer 23 does not impair recyclability because the amount of material in the bonding layer 23 is sufficiently small compared to the main component PE, and plastics compatible with PE can also be used.

[0025] The second laminate layer 3 consists primarily of a PE, whereby the PE content of the total polymer quantity of the second laminate layer 3, excluding any added additives such as mineral or other fillers, should be at least 80% by volume. Various PE types can be used here, i.e., LDPE, LLDPE, MDPE, HDPE, either as a single type or as a mixture, in the form of copolymers, or even in multilayer configurations.

[0026] The thickness of the second laminate layer 3 is typically between 8 and 200 µm, depending on the application of the packaging laminate 1.

[0027] In the second laminate layer 3, the remaining portion will also consist of a polyolefin material compatible with regard to recyclability, as described above, to achieve the desired recyclability.

[0028] The second laminate layer 3 preferably forms a sealing layer within the packaging laminate 1, which, in a package made of the packaging laminate 1, is generally oriented towards the packaged product. The packaging is produced by cutting, folding, and heat-sealing the packaging laminate 1. Possible packaging types include pouches, bags, sacks, etc.

[0029] The second laminate layer 3 can also be multi-layered, for example extruded or co-extruded.

[0030] The first laminate layer 2 is produced by co-extrusion because this allows for particularly simple and cost-effective manufacturing. Preferably, the well-known blown film or flat film extrusion process is used. Naturally, raw materials suitable for co-extrusion must be used.

[0031] The first laminate layer 2 is stretched after co-extrusion either exclusively in the machine direction (generally the longitudinal or extrusion direction) or bidirectionally (in the machine direction and in the transverse direction). The stretch ratio for monodirectional stretching is preferably at least 4:1 in the machine direction. The stretch ratio in the machine direction and in the transverse direction for bidirectional stretching need not be the same. The stretch ratio in the machine direction is preferably at least 4:1 to 8:1, and the stretch ratio in the transverse direction is preferably at least 5:1 to 10:1. The stretching can be performed in-line (i.e., immediately after co-extrusion) or out-of-line (i.e., at a later time after co-extrusion).

[0032] It should be noted that in blown film extrusion and flat film extrusion, the extrusion gap (1.5 to 2.5 mm for blown film) or the gap of the extrusion die is significantly larger than the final thickness of the extruded film (typically between 10 and 200 µm). This is achieved by stretching the extruded melt at temperatures well above the melting point of the extruded polymer, thus giving it its final thickness. In blown film extrusion, for example, the melt is typically stretched transversely by a factor of approximately 2 to 3 (the so-called blow-up ratio) and longitudinally by a factor of 1:10 to 1:100 (the so-called take-up ratio). However, this stretching during extrusion cannot be compared to the stretching of a plastic film, since stretching usually takes place at temperatures just below the melting point of the polymer in order to permanently align the disordered polymers and the semi-crystalline areas in the stretching direction.

[0033] However, stretching can also take place during co-extrusion if a known multiple blown film extrusion process is used.

[0034] The first laminate layer 2 is preferably produced using blown film extrusion because this results in less edge trimming due to the production process, leading to lower costs for the packaging laminate 1, especially with the more expensive barrier polymers. Blown film extrusion also allows the use of more viscous HDPE materials with a mass flow rate (MFR) (190°C / 5kg) of less than 3. The MFR is measured according to ASTM D1238 or DIN EN ISO 1133-1 and is specified as MFR 190°C / 5kg, 190°C / 21.6kg, or 190°C / 2.16kg. One possible HDPE has an MFR (190°C / 5kg) of 1.8 and an MFR (190°C / 21.6kg) of 23 g / 10min. Such HDPE materials have a higher molecular weight and better mechanical properties, which is advantageous for use in a packaging laminate 1.

[0035] For the production of the packaging laminate 1, the stretched first laminate layer 2 and the second laminate layer 3 are joined together, preferably by extrusion lamination, extrusion coating or adhesive lamination, wherein the second laminate layer 3 is joined to the barrier layer 22 or the substrate layer 21 of the first laminate layer 2.

[0036] In extrusion coating, one layer (here, for example, the second laminate layer 3) is extruded onto another layer (here, for example, the first laminate layer 2) using an extrusion process. An adhesion promoter (for example, bonding layer 5) should also be included in between to increase bond strength. One possible adhesion promoter is the product MICA A-131-X.

[0037] In lamination, one layer (here, for example, the second laminate layer 3 or the third laminate layer 4) is bonded to another layer (here, for example, the first laminate layer 2) using a suitable laminating agent (for example, bonding layer 6), such as polyurethane adhesives or polyolefin copolymers in the case of extrusion lamination. In extrusion lamination, the laminating adhesive is applied using an extrusion process, while in lamination, it is applied using a different process, for example, as a lacquer. The thickness of the laminating adhesive is preferably 2 to 5 g / m². 2 with standard polyurethane-based adhesives or 5 to 20 g / m² 2 during extrusion lamination.

[0038] The third laminate layer 4 is multi-layered, for example like the first laminate layer 2, and is bonded to the first laminate layer 2 by lamination or extrusion lamination.

[0039] The third laminate layer 4 can, for example, also be designed like the polyethylene film described in WO 2020 / 074688 A1, whereby an EVOH (for example, an EVOH with 24 mol% to 48 mol% ethylene content) could be used on the outer side instead of the heterophase PP block copolymer. The third laminate layer 4 is thus, for example, structured in the form of HDPE (min. 60 vol%, max. 40 µm) / PP (or EVOH) (max. 5 µm).

[0040] The third laminate layer 4 primarily serves as a printing substrate in the packaging laminate 1 and is preferably printed on the PE layer, wherein the PE layer is arranged on the inside of the packaging laminate 1 and the PP layer or the EVOH layer is arranged on the outside of the packaging laminate 1. However, it is also possible to arrange the printed PE layer on the outside, optionally with an overprint varnish, e.g., a PU-based varnish with a basis weight in the range of 0.5–2 g / m². 2 dry.

[0041] To achieve the high-barrier function in the packaging laminate 1, it is provided that the first laminate layer 2 is barrier-coated on both sides, or that the first laminate layer 2 is double-barrier-coated on one side, or that the first laminate layer 2 is barrier-coated on one side and additionally the second laminate layer 3 is barrier-coated on the side facing the first laminate layer 2, and / or the third laminate layer 4 is barrier-coated on the side facing the first laminate layer 2.

[0042] The barrier coating is considered an integral part of the layer on which it is applied, for example as an integral part of the substrate layer 21 or the barrier layer 22 of the first laminate layer 2, because such a barrier coating is applied with very small layer thicknesses.

[0043] The barrier coating is applied, for example, by applying a barrier lacquer, such as a polyvinyl alcohol (PVOH), ethylene-vinyl alcohol copolymer (EVOH), or butenediol-vinyl alcohol copolymer (BVOH) dissolved in a solvent, or their copolymers, or mixtures of two or more of the aforementioned barrier polymers. Such lacquer layers can be applied very thinly, for example, by smooth roller application, typically in the range of 0.5 to 5 g / m². 2 (dry basis weight), and thus do not impair the recyclability of the packaging laminate 1.

[0044] The barrier coating can also be in the form of an inorganic material deposited on a surface. Such a coating can be produced by metallizing a surface with a metal, preferably aluminum, or with silicon dioxide (SiOx) or aluminum oxide (AlOx), or mixtures of at least two of the aforementioned. The coating is applied, for example, using a chemical or physical gas deposition process and results in very thin layers of the coating, for example, in the range of a few to a few hundred nanometers (e.g., 5 to 200 nm, preferably 10 to 50 nm), and thus does not impair the recyclability of the packaging laminate 1.

[0045] A barrier coating in the form of a deposited inorganic material is applied after any necessary stretching of the layer on which the coating is applied.

[0046] The layer onto which the coating is applied can also undergo a known pretreatment, such as corona or flame treatment, to improve the adhesion of the coating. Additionally or alternatively, an adhesion promoter, such as an adhesive layer, can be provided to improve the bond between the coating and the layer supporting the coating.

[0047] Finally, it should be noted that each of the layers described above in the first laminate layer 2, second laminate layer 3 or third laminate layer 4, especially the layers made primarily of PE, can itself be multi-layered.

[0048] By using predominantly PE and compatible materials in the packaging laminate 1, a particularly recycling-friendly laminate can be produced that can be easily and cost-effectively recycled using common methods in mechanical recycling.

[0049] The invention has been described above for a packaging laminate 1 based primarily on PE materials. However, the packaging laminate 1 can alternatively and analogously also be produced based primarily on PP materials. Suitable polyolefin materials compatible with PP include PP copolymers, such as random copolymers and block copolymers. An addition of up to 20% polyethylene as a compatible polyolefin material hardly impairs recyclability.

[0050] Exemplary embodiments of a packaging laminate 1 according to the invention are described below.

[0051] Fig. Figure 3 shows a structure of a packaging laminate 1 with a first laminate layer 2, a second laminate layer 3 and a third laminate layer 4.

[0052] The first laminate layer 2 consists of a substrate layer 21, a barrier layer 22, and an intermediate bonding layer 23. The substrate layer 21 consists of at least 60 vol% HDPE (alternatively at least 70 vol% or at least 80 vol%). The remainder (apart from any additives) consists of recyclable materials as described above. The barrier layer 22 consists of EVOH (alternatively PA, PVOH, or BVOH), and the bonding layer 23 consists of one of the aforementioned materials. Barrier coatings 24, 25 made of aluminum metallizations (or alternatively SiOx, AIOx, or an organically modified SiOx layer) are applied to the substrate layer 21 and the barrier layer 22 (or as a mixture of at least two of the aforementioned), forming part of the substrate layer 21 and the barrier layer 22.The substrate layer 21, the barrier layer 22, and the intervening bonding layer 23 are co-extruded and then unidirectionally (or alternatively bidirectionally) stretched as described above. The barrier coatings 24 and 25 are applied after stretching. The thickness of the first laminate layer 2 in the packaging laminate 1 is 15 to 40 µm.

[0053] Alternatively or additionally, the barrier layer 22 and the substrate layer 21 within the first laminate layer 2 can also be exchanged, so that the barrier layer 22 is in contact with the bonding layer 6 and the substrate layer 21 is in contact with the bonding layer 5. The provisions regarding the arrangement of the barrier coatings 24, 25 apply analogously to the structure described above.

[0054] The second laminate layer 3 is extruded or co-extruded (in the case of a multilayer second laminate layer 3 with several sublayers 31, 32 as in Fig. (3, indicated by dashed lines) Layer made of min. 80 vol% PE material, such as LDPE or LLDPE, and forms a sealing layer. The thickness of the second laminate layer 3 in the packaging laminate 1 is, for example, 60 µm.

[0055] The first laminate layer 2 and the second laminate layer 3 are bonded to the bonding layer 5 with a laminating adhesive, as described above. The basis weight of the bonding layer 5 is 1 to 6 g / m². 2 dry.

[0056] The third laminate layer 4 consists of a layer 41 of at least 60 vol% HDPE, preferably at least 80 vol% HDPE, and a layer 42 of a heterophase PP block copolymer (or alternatively of EVOH (24 to 48 mol% ethylene content)), which is arranged on the outside of the packaging laminate 1. The layer 41 can be printed on the side facing away from the layer 42 with a printing layer 43 (as shown in Fig. 3 (indicated by dashed lines). The printing layer 43 is considered part of layer 41.

[0057] Between layers 41, 42, a further bonding layer can be provided as an adhesion promoter (for example, a MAH-grafted polymer), especially in the case of the use of an EVOH extrusion layer, to better anchor the EVOH layer 42 to the HDPE layer 41.

[0058] The first laminate layer 2 and the third laminate layer 4 are bonded to the bonding layer 6 with a laminating adhesive as described above. The thickness of the bonding layer 6 is 1 to 6 g / m². 2 .

[0059] The double barrier coating 24, 25 enables WVTR values ​​of <0.05 g / (m²). 2 *24h). At the same time, OTR values ​​(oxygen barrier) of less than 0.05 cm can be achieved. 3 / (m 2 *24h) can be achieved, measured with DIN 53380-3 at 23°C / 0%rh or ASTM D3985.

[0060] For achieving very high barrier values, such as WVTR or OTR, decoupling the barrier layers in the packaging laminate 1 is advantageous. This is demonstrated in the exemplary embodiment of Fig. 3 through which the first laminate layer 2 located between the two barrier coatings 24, 25 is reached.

[0061] In another embodiment according to Fig. 4 is the packaging laminate 1 as above with reference to the Fig. The embodiment described in Figure 3 differs in the design of the barrier coatings 24, 25 of the first laminate layer 2. In this embodiment, the first laminate layer 2 is provided on one side, for example on the barrier layer 22 made of EVOH (28-44 mol% ethylene content), with a double barrier coating 24, 25. For this purpose, the barrier layer 22 is provided with a first barrier coating 24 in the form of a metallization, or an AIOx or SiOx coating, or an organically modified SiOx layer, or as a mixture of at least two of the aforementioned. The second barrier coating 25 is applied in the form of a known transfer metallization.

[0062] In transfer metallization, a metallization or AIOx is applied to a substrate, for example, a PET (polyethylene terephthalate) film. An adhesive 26 is applied to the first barrier coating 24 and / or the second barrier coating 25 on the substrate. The substrate with the metallization is then laminated to the first barrier coating 24 of the first laminate layer 2 using the adhesive 26. The substrate is then removed, possibly after a certain curing time, so that the second barrier coating 25 remains on the adhesive 26 and thus on the first laminate layer 2. The transfer of the inorganic layer is complete if the adhesive strength of the transfer medium on the surface of the PET film is sufficiently low, preferably <0.1 N / 15 mm².

[0063] In this embodiment, the decoupling of the two barrier coatings 24, 25 is achieved by the adhesive 26.

[0064] In transfer metallization, an additional layer, for example in the form of a release agent, can be provided between the substrate and the second barrier coating 25 to facilitate the removal of the metallization from the substrate. This additional layer adheres poorly to the substrate, ensuring a low adhesion strength of less than 0.1 N / 15 mm.

[0065] The release agent itself can be a PVOH-based coating, thus simultaneously increasing the barrier effect against oxygen.

[0066] The metallization or AIOx on the substrate can also be carried out in two or more layers to increase the barrier effect in the packaging laminate 1.

[0067] In another embodiment according to Fig. 5 is the packaging laminate 1 as above with reference to the Fig. 3 described. The difference lies in the design of the barrier coatings 24, 25 of the first laminate layer 2. In this embodiment, the first laminate layer 2 is provided on one side, for example on the barrier layer 22 made of EVOH, with a double barrier coating 24, 25. For this purpose, the barrier layer 22 is designed with a first barrier coating 24 in the form of an AlOx coating. A second barrier coating 25 in the form of a metallization is applied to this first barrier coating 24. An adhesion promoter can also be provided between the first barrier coating 24 and the second barrier coating 25 to decouple the coatings.

[0068] Another embodiment is shown in Fig. Figure 6 shows the first laminate layer 2, which again consists of a substrate layer 21, a barrier layer 22, and an intermediate bonding layer 23 as described above. A first barrier coating 24 in the form of a metallization (or alternatively made of SiOx or AIOx or a barrier lacquer) is applied to the barrier layer 22. The second laminate layer 3 is constructed as explained above.

[0069] The third laminate layer 4 also consists of a substrate layer 44, a barrier layer 46, and an intermediate bonding layer 45, structured as described above for the first laminate layer 2. A second barrier coating 25 in the form of a metallization (or alternatively made of SiOx or AIOx or a barrier lacquer) is applied to the barrier layer 46 of the third laminate layer 4.

[0070] The first laminate layer 2 is joined to the second laminate layer 3 and / or to the third laminate layer 4 by extrusion lamination with suitable laminating agents, for example based on polyethylene or polypropylene, for the bonding layers 5, 6. The bonding layer 6 again decouples the two barrier coatings 24, 25.

[0071] In the following embodiment, more than two barrier coatings are layered on top of each other in the packaging laminate 1 to increase the barrier effect. In this embodiment of the packaging laminate 1, the structure of the first laminate layer 2 is: substrate layer 21 (HDPE) / bonding layer 23 / barrier layer 22 (EVOH) + further barrier layers. An adhesive layer, for example with a thickness of 3 g / m², is applied to the EVOH barrier layer 22. 2If the adhesive is a barrier adhesive, i.e., made of a material with barrier properties, then the adhesive layer forms a further barrier layer within the packaging laminate 1. An aluminum, AIOx, or SiOx coating with a thickness of 8–200 nm, preferably 10–50 nm, is applied to the adhesive layer, forming another barrier layer within the packaging laminate 1. A lacquer layer, for example with a thickness of 2 g / m², is applied to this coating. 2 (Dry basis weight). This coating layer can also be designed as a barrier coating to form an additional barrier layer. An adhesive layer, for example with a thickness of 3 g / m², is applied to the coating layer. 2(Dry basis weight). If the adhesive is designed as a barrier adhesive, then the adhesive layer forms a further barrier layer in the packaging laminate 1. An aluminum, AlOx, SiOx, or organically modified SiOx layer (or a mixture of at least two of the aforementioned) with a thickness of 8–200 nm, preferably 10–50 nm, is applied to the adhesive layer, forming a further barrier layer in the packaging laminate 1. A lacquer layer, for example with a thickness of 2 g / m², is applied to this coating. 2This lacquer layer can also be designed as a barrier lacquer to form a further barrier layer. In this construction of the packaging laminate 1, the adhesive layers and the lacquer layers each ensure decoupling of the barrier coatings, which has a beneficial effect on the overall barrier performance. This first laminate layer 2 can then be combined with a laminate layer 3 and a third laminate layer 4 as described above.

[0072] It is also possible to laminate a first laminate layer 2 with at least one barrier coating with another first laminate layer 2, also with at least one further barrier coating (for example, using a laminating agent or as extrusion lamination). In this case, the barrier coatings of the two first laminate layers 2 would face each other and be separated and decoupled from each other by the laminating agent or by the extrusion lamination. This would also be possible with a first laminate layer 2 with multiple barrier layers, for example, as described above.

[0073] This leads, for example, to a packaging laminate 1 as in Fig.Figure 7 shows a further first laminate layer 2' arranged between the first laminate layer 2 and the third laminate layer 4 (optionally additionally or alternatively between the second laminate layer 3 and the first laminate layer 2). This further first laminate layer 2' is a co-extruded and stretched composite consisting of a further substrate layer 21' with a PE or PP content of at least 60 vol%, a further bonding layer 23', and a further barrier layer 22' made of a barrier polymer, preferably polyamide or ethylene-vinyl alcohol copolymer, with a thickness of at most 20% of the total thickness of the further first laminate layer 2'. The further bonding layer 23' is arranged between the further substrate layer 21' and the further barrier layer 22'.The further first laminate layer 2' is provided on one side with a further first barrier coating 24' and a further second barrier coating 25' (whereby the further barrier coatings 24', 25' can also be distributed differently in the further first laminate layer 2', as described above for the first laminate layer 2). At least one of the barrier coatings 24, 25 of the first laminate layer 2 and at least one of the further barrier coatings 24', 25' of the further first laminate layer 2' are arranged facing each other and are connected to each other via a laminating agent 27.

[0074] Another way to create a particularly good high barrier is to layer several barrier coatings, especially metallization layers, on top of each other in the packaging laminate 1, either by direct vapor deposition + transfer metallization, or vice versa. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] WO 2018 / 202479 A1 [0005, 0015] WO 2020 / 038579 A1 [0005, 0015] WO 2020 / 074688 A1

[0039]

Claims

[1] High-barrier packaging laminate (1) comprising a first laminate layer (2), a second laminate layer (3) and a third laminate layer (4), wherein the first laminate layer (2) is a co-extruded and stretched composite of a substrate layer (21) having a PE or PP content of at least 60 vol%, a bonding layer (23) and a barrier layer (22) of a barrier polymer, preferably of polyamide or ethylene-vinyl alcohol copolymer or polyvinyl alcohol or butenediol vinyl alcohol copolymer, with a thickness of at most 20% of the total thickness of the first laminate layer (2), wherein the bonding layer (23) is arranged between the substrate layer (21) and the barrier layer (22), wherein the first laminate layer (2) is bonded on one side to the second laminate layer (3) by a further bonding layer (5) and on the opposite second side to the third laminate layer (4) by a further bonding layer (6),characterized by , that the packaging laminate (1) has a WVTR value of less than 0.1 g / (m²) 2 *24h), preferably less than 0.05 g / (m²) 2 *24h) by providing the first laminate layer (2) with a barrier coating (24, 25) on both sides, or the first laminate layer (2) with a first barrier coating (24) and a second barrier coating (25) on one side, or the first laminate layer (2) with a first barrier coating (24) on one side and additionally the second laminate layer (3) with a second barrier coating (25) on the side facing the first laminate layer (2) and / or the third laminate layer (4) with a second barrier coating (25) on the side facing the first laminate layer (2). [2] High-barrier packaging laminate according to claim 1, characterized by, that the first barrier coating (24) and / or the second barrier coating (25) is designed as a metallization or as a SiOx coating or AIOx coating or as an organically modified SiOx coating, or a mixture of at least two of the aforementioned coatings, or the first barrier coating (24) and / or the second barrier coating (25) is designed as a barrier varnish based on PVOH, EVOH or BVOH, or a copolymer of PVOH, EVOH or BVOH or a mixture of at least two of the aforementioned barrier polymers. [3] High-barrier packaging laminate according to claim 1 or 2, characterized by , that the second laminate layer (3) has a PE content of at least 80 vol% if the substrate layer (21) of the first laminate layer (2) consists primarily of PE, or has a PP content of at least 80 vol% if the substrate layer (21) of the first laminate layer (2) consists primarily of PP. [4] High-barrier packaging laminate according to one of claims 1 to 3, characterized by , that the third laminate layer (4) consists of a first layer (41) having a PE or PP content of at least 80 vol% and an associated second layer (42) of a heterophase PP block copolymer or an EVOH, wherein the first layer (41) consists primarily of PE if the substrate layer (21) of the first laminate layer (2) consists primarily of PE, or consists primarily of PP if the substrate layer (21) of the first laminate layer (2) consists primarily of PP. [5] High-barrier packaging laminate according to any one of claims 1 to 4, characterized by, that the third laminate layer (4) is a stretched composite of a further substrate layer (44) with a PE or PP content of at least 60 vol%, a further bonding layer (45) and a further barrier layer (46) made of a barrier polymer, preferably polyamide or ethylene-vinyl alcohol copolymer, with a thickness of at most 20% of the total thickness of the third laminate layer (4), wherein the further bonding layer (45) is arranged between the further substrate layer (44) and the further barrier layer (46). [6] High-barrier packaging laminate according to any one of claims 1 to 4, characterized by, that between the first laminate layer (2) and the second laminate layer (3) and / or between the first laminate layer (2) and the third laminate layer (4) a further first laminate layer (2') is arranged, wherein the further first laminate layer (2') is a co-extruded and stretched composite of a further substrate layer (21') with a PE or PP content of at least 60 vol%, a further bonding layer (23') and a further barrier layer (22') made of a barrier polymer, preferably of polyamide or ethylene-vinyl alcohol copolymer or polyvinyl alcohol or butenediol vinyl alcohol copolymer, with a thickness of at most 20% of the total thickness of the further first laminate layer (2'), wherein the further bonding layer (23') is arranged between the further substrate layer (21') and the further barrier layer (22') and,wherein the further first laminate layer (2') is provided on one side with a further first barrier coating (24') and a further second barrier coating (25'), or the further first laminate layer (2') is provided on one side with a first barrier coating (24') and additionally the second laminate layer (3) is provided on the side facing the further first laminate layer (2') with a further second barrier coating (25') and / or the third laminate layer (4) is provided on the side facing the further first laminate layer (2') with a further second barrier coating (25'). [7] High-barrier packaging laminate according to claim 6, characterized by, that the further first barrier coating (24') and / or the further second barrier coating (25') is designed as a metallization or as a SiOx coating or AIOx coating or as an organically modified SiOx coating, or a mixture of at least two of the aforementioned coatings, or the further first barrier coating (24') and / or the further second barrier coating (25') is designed as a barrier varnish based on PVOH, EVOH or BVOH, or a copolymer of PVOH, EVOH or BVOH or a mixture of at least two of the aforementioned barrier polymers.

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