Sterilizable barrier layer laminate, method for producing the laminate and use of same

Abstract

The invention relates to a sterilizable barrier layer laminate (10) comprising a polypropylene (PP) outer layer (20) which has barrier properties, a reverse printing (30) to which a primer layer (40) has been applied, and a PP inner layer (60) situated opposite the PP outer layer, wherein a primer layer is located on the reverse printing and a PP connecting layer (50) is extruded in between the primer layer and the PP inner layer, and wherein the PP outer layer is an outermost layer of a multilayer barrier film (21) which, from the outside in, i.e. as seen from the PP outer layer in the direction toward the PP inner layer, comprises the following layers: at least one functional skin layer (22), an aluminum oxide layer (25) and a top coating layer (23). The invention also alternatively relates to a sterilizable barrier layer laminate comprising: an outer PP layer (20'), a reverse printing and a PP inner layer situated opposite the outer PP layer (20'), wherein between the outer PP layer, in particular the reverse printing, and the PP inner layer there is a multilayer barrier film which, from the outside in, i.e. as viewed from the outer PP layer in the direction toward the PP inner layer, comprises the following layers: a PP outer layer, at least one functional skin layer, an aluminum oxide layer and a top coating layer, wherein the multilayer film is connected on one side to the reverse printing and on the other side to the PP inner layer by means of an adhesive layer (80). The invention further relates to a method for producing the laminate and to the use of same.

Description

[0001] Huhtamaki Flexible Packaging Germany September 1, 2025 GmbH & Co. KG M / VRG-196-PC PF / lz

[0002] Sterilizable barrier layer laminate, as well as methods for manufacturing the laminate and its use

[0003] Description

[0004] The invention relates to a sterilizable barrier layer laminate according to the preamble of claim 1 and according to the preamble of claim 2, a method for producing such laminates according to the preamble of claim 15 and their use according to the preamble of claim 16.

[0005] Sterilizable, or sterilizable, barrier layer laminates have been known for some time and are used, for example, for packaging food, animal feed or medicines, especially when perishable goods need to be packaged in a water- and airtight manner.

[0006] However, a significant disadvantage of previously known sterilizable barrier layer laminates is that their barrier effect diminished considerably as a result of the sterilization process. Furthermore, these laminates always contained very high proportions of adhesives, particularly polyurethane-based ones, to maintain their structural integrity and ensure adhesion between the different laminate layers. A further problem is that these adhesives tend to migrate within the laminate, leading to contamination of the contents packaged in or with such laminates.

[0007] Another significant disadvantage of such previously known sterilizable barrier layer laminates is that they cannot be recycled due to the high proportion of adhesive material.

[0008] Furthermore, such previously known sterilizable barrier layer laminates were also complicated in their construction and expensive due to high material requirements, as such barrier layer laminates required a three-layer polypropylene structure, namely an inner polypropylene layer and an outer polypropylene layer as well as an intermediate central polypropylene layer coated with aluminum oxide and / or silicon oxide, MEISSNER BOLTE M / VRG-196-PC

[0009] 2, which was held in place by means of adhesive between the two outer polypropylene layers. The outer polypropylene layer was also necessary, among other things, to provide a printing layer, namely usually for reverse printing. Figure 1 schematically illustrates such a structure of a sterilizable barrier layer laminate known from the prior art.

[0010] The object of the invention is to avoid the aforementioned disadvantages and to provide a sterilizable barrier laminate with a durable and high barrier effect, which is cost-effective to manufacture with reduced material requirements, is easily recyclable, and is suitable for the production of packaging for, among other things, food, animal feed, and pharmaceuticals. Furthermore, the object of the invention includes a method for producing such a barrier laminate and its use in the production of packaging for, among other things, food, animal feed, and pharmaceuticals.

[0011] This problem is solved by a sterilizable barrier layer laminate according to alternative claims 1 and 2, and by a method for producing such sterilizable laminates according to claim 15, and by using such laminates to produce packaging according to claim 16.

[0012] In particular, this problem is solved by a sterilizable barrier layer laminate with a polypropylene outer layer exhibiting barrier properties, a reverse print, a primer layer applied to the print, and a polypropylene inner layer arranged opposite the polypropylene outer layer, wherein a primer layer is arranged on the reverse print and a polypropylene bonding layer is extruded between the primer layer and the polypropylene inner layer, and wherein the polypropylene outer layer is an outermost layer of a multilayer barrier film which, viewed from the outside in, i.e., from the polypropylene outer layer towards the polypropylene inner layer, has the following layers: at least one functional skin layer, an aluminum oxide layer (AIO). X ) and a topcoat layer.

[0013] A significant advantage of such a sterilizable barrier layer laminate according to the invention is that this new barrier layer laminate structure requires only two instead of the previous three MEISSNER BOLTE M / VRG-196-PC

[0014] 3

[0015] The invention requires polypropylene layers, namely an outer polypropylene layer exhibiting barrier properties, which advantageously also serves as a printable layer, and an inner polypropylene layer which, when the new barrier layer laminate according to the invention is used to manufacture packaging, faces the product to be packaged and serves as a sealing layer. According to the invention, these two polypropylene layers are joined by means of a very thin polypropylene compound layer extruded between them, which is chemically identical to the two outer polypropylene layers in its polymer composition. Due to the chemically identical material, a strong and excellent bond between this thin, extruded polypropylene compound layer and the inner polypropylene layer is ensured.Compared to the reverse-printed polypropylene outer layer, optimal bond adhesion is also ensured due to the use of an extrudable or printable primer on the printing, i.e. facing the polypropylene compound layer.

[0016] A further significant advantage of the invention is that, according to the invention, an outer polypropylene monolayer, which is then reverse printed, as was used, for example, in the prior art, is replaced by a multilayer barrier film in which only the outermost polypropylene layer is placed by the polypropylene outer layer, to which a functional skin layer layer, an aluminum oxide layer applied to the skin layer layer, and a topcoating layer applied to this aluminum oxide layer are immediately attached.

[0017] The multi-layer barrier film is thus formed by the layers, viewed from the outside in: polypropylene outer layer - functional skin layer - aluminum oxide layer - topcoating layer.

[0018] The key advantage of this multi-layer barrier film is that it offers multiple functionalities, namely, firstly, very good adhesion of the aluminum oxide layer to the inside of the polypropylene outer layer, whereby this very good adhesion of the aluminum oxide layer is facilitated by the functional skin layer on the inside MEISSNER BOLTE M / VRG-196-PC

[0019] 4. The polypropylene outer layer is ensured. On the other hand, the aluminum oxide layer, in turn, ensures very good printability of the aluminum oxide layer through the topcoating layer.

[0020] Due to the fact that the outer polypropylene layer is made of polypropylene that is at least unidirectionally, but preferably bidirectionally, stretched, and which already provides a good barrier against oxygen, moisture and water vapor, this barrier effect is further improved according to the invention by the application of an aluminum oxide layer, which replaces a silicon oxide layer that is conventional according to the invention.

[0021] A further advantage of the multilayer barrier film used according to the invention is that the multilayer barrier film is transparent, so that reverse printing, i.e., printing not on the visible side but on the reverse side of the printed film, can easily be applied to the back side, i.e., the inside side facing the polypropylene inner layer, of the multilayer barrier film, whereby the printing is then protected against water vapor, oxygen and mechanical stress by the outer layers, in particular the outermost polypropylene outer layer.

[0022] Due to this interaction of the multilayer barrier film and the extruded polypropylene compound layer optimized according to the invention, the barrier layer laminate according to the invention not only achieves very good barrier properties, but also very good bond adhesion including very low shrinkage, so that the sterilizable barrier layer laminate according to the invention can be sterilized even at high temperatures, such as those prevailing in an autoclave, i.e. in a hot steam atmosphere at 120 °C to 130 °C under pressure, without the risk of becoming brittle and / or the associated risk of loss of the barrier layer.

[0023] According to the invention, one or even several adhesive layers, as were necessary in previous barrier layer laminates, can therefore be dispensed with.

[0024] Likewise, according to the invention, an additional central polypropylene layer arranged within the laminate structure, which according to the prior art MEISSNER BOLTE M / VRG-196-PC, can be used.

[0025] 5 the barrier property provided there, can be dispensed with, whereby according to the invention such a basic structure already known from the prior art of previously defective barrier layer laminates can also be used if, instead of the central polypropylene inner layer which previously provided only insufficient barrier properties, a multilayer barrier film according to the invention with the prescribed structure is used. In this case, the polypropylene outer layer is then not actually located on the outside of the sterilizable barrier layer laminate according to the invention, but is integrated into it, but still represents the layer facing the outer polypropylene layer of known barrier laminates, i.e.The side of the multilayer barrier film facing away from the polypropylene inner layer is represented, with a functional skin layer, an aluminum oxide layer and a topcoat layer then adjoining this polypropylene outer layer in that order.

[0026] Since the multilayer barrier film according to the invention has significantly improved barrier properties compared to previous barrier films made of polypropylene, conventional barrier films can also be significantly improved using this multilayer barrier film according to the invention, although adhesive can still be used in such barrier films.

[0027] Alternatively, due to the use of the multilayer barrier film according to the invention, it is also possible, according to the invention, to dispense with the adhesive layer facing the polypropylene inner layer and, as already described above, to use a thin, co-extruded polypropylene compound layer at this point. This is possible according to the invention due to the use of the topcoat layer, which ensures very good bonding with the co-extruded polypropylene compound layer, which in turn adheres particularly well to the polypropylene inner layer, especially due to the material uniformity. Thus, the adhesive content according to the invention can also be minimized in a conventional barrier layer laminate with an outer polypropylene inner layer modified using the multilayer barrier film according to the invention. Because the remaining adhesive layer is then only present on the outside, i.e.,The side of the multilayer barrier film facing away from the polypropylene inner layer is also subject to migration of adhesive towards a potential filler of the MEISSNER BOLTE M / VRG-196-PC according to the invention.

[0028] 6 sterilizable barrier layer laminate containers are practically no longer a concern.

[0029] In this respect, the object of the invention is also achieved in particular by a sterilizable barrier layer laminate comprising an outer polypropylene layer, a reverse print on the outer polypropylene layer, and a polypropylene inner layer arranged opposite the outer polypropylene layer, wherein a multilayer barrier film is arranged between the outer polypropylene layer, in particular between the reverse print, and the polypropylene inner layer, which, viewed from the outside inwards, i.e., from the outer polypropylene layer towards the polypropylene inner layer, has the following layers: a polypropylene outer layer, at least one functional skin layer, an aluminum oxide layer, and a topcoat layer, wherein the multilayer film is bonded on one or both sides to both the reverse print and the polypropylene inner layer by means of an adhesive layer or alternatively a primer.

[0030] Several significant advantages of the sterilizable barrier layer laminate according to the first embodiment described above are that the laminate requires considerably less material, namely only two polypropylene layers, i.e., an inner polypropylene layer and a multilayer barrier film with the polypropylene outer layer exhibiting barrier properties. Furthermore, the structure of the barrier layer laminate according to the first embodiment described above requires no adhesive whatsoever, and in particular, no polyurethane-based adhesive, so that any migration risk from such an adhesive is eliminated according to the invention.As a further advantage, the barrier layer laminate according to the invention is practically pure, particularly due to the lack of adhesive, with the exception of an extremely thin printing and primer layer, so that the recyclability of the sterilizable barrier layer laminate according to the invention is significantly improved compared to previously known sterilizable barrier layer laminates.

[0031] The sterilizable barrier layer laminate according to the second variant described above has essentially the same advantages as that of the first variant, with the difference that, according to the second variant, some adhesive remains in the barrier layer laminate, wherein the MEISSNER BOLTE M / VRG-196-PC

[0032] 7

[0033] The adhesive content can be significantly reduced and at least halved compared to previously known sterilizable barrier layer laminates, and adhesive no longer needs to be used on the product side, but can be replaced at least on this side by a very thin primer.

[0034] According to the invention, the functional skin layer has a thickness in the range of 0.2 pm to 1.5 pm, preferably in the range of 0.4 pm to 1.0 pm, and particularly preferably in the range of 0.6 pm to 0.9 pm, and consists of polyamide (PA) or ethylene vinyl alcohol copolymer (EVOH) or a mixture of polyamide and ethylene vinyl alcohol copolymer, wherein these two substances are present either in a substantially homogeneous mixture with each other and / or as two discrete, intimately bonded, co-extruded layers. A significant advantage of the functional skin layer according to the invention is that the skin layer provides a more polar surface on the polypropylene outer layer compared to the polypropylene itself, to which aluminum oxide adheres significantly better than to the pure polypropylene outer layer without the need for a primer or adhesive.

[0035] According to the invention, the polypropylene outer layer is preferably multilayered, for example, three-layered, and consists in particular of at least one, preferably several, highly crystalline polypropylene layer(s), and optionally an adhesion promoter, for example in the form of an adhesive or primer, based on or similar to polypropylene, and the at least one functional skin layer. According to the invention, this layered composite of highly crystalline polypropylene layer(s), adhesion promoter, and functional skin layer is coextruded and has an at least uniaxial orientation, preferably in the machine direction, which improves the barrier layer effect of the polypropylene outer layer.increased, wherein the adhesion promoter is arranged between the highly crystalline polypropylene layer(s) and the functional skin layer, and the total thickness of the polypropylene outer layer is in the range of 10 pm to 40 pm, preferably in the range of 15 pm to 30 pm and particularly preferably in the range of 18 pm to 25 pm.

[0036] A layer thickness of the adhesion promoter or primer, which is preferably polypropylene-based or polypropylene-like, is specified in MEISSNER BOLTE M / VRG-196-PC.

[0037] 8 according to the invention in the range of 0.2 pm to 1.8 pm, preferably in the range of 0.4 pm to 1.6 pm and particularly preferably in the range of 0.6 pm to 1.5 pm.

[0038] The topcoating layer comprises one or more of, or consists of, one or more of the following materials: polyacrylic acid, ethylene vinyl alcohol copolymer and / or polyvinyl alcohol copolymer, and has a layer thickness in the range of 0.2 pm to 1.8 pm, preferably in the range of 0.4 pm to 1.6 pm and particularly preferably in the range of 0.6 pm to 1.5 pm.

[0039] Furthermore, according to the invention, the primer layer has a layer thickness in the range of 0.1 pm to 3 pm, preferably in the range of 0.5 pm to 2 pm and particularly preferably in the range of 1 pm to 1.5 pm.

[0040] According to a further advantageous embodiment of the invention, the primer layer is applied to the printed surface by means of a printing process or by extrusion. Such an application is particularly advantageous because the primer layer can be applied in this way extremely thinly, namely with the aforementioned layer thickness down to a minimum of 0.1 pm on the multilayer barrier film or the reverse print. Such a thin primer layer thickness, namely in the aforementioned range of 0.1 pm to 3 pm, preferably in the range of 0.5 pm to 2 pm, and particularly preferably in the range of 1 pm to 1.5 pm, contributes significantly to the excellent recyclability of the sterilizable barrier layer laminate according to the invention, since this allows the proportion of foreign matter in the otherwise chemically almost pure polypropylene material to be extremely minimized.

[0041] According to the invention, the polypropylene inner layer has a layer thickness in the range of 35 pm to 100 pm, preferably in the range of 50 pm to 90 pm and particularly preferably in the range of 60 pm to 80 pm.

[0042] The polypropylene inner layer thus constitutes the primarily stabilizing layer of the barrier layer laminate according to the invention and also a contact layer to a filling material that is filled into or packaged in a package made from the sterilizable barrier layer laminate according to the invention. Optionally, this polypropylene inner layer can also be stretched, preferably in the machine direction, which in turn contributes to increasing the barrier effect of the barrier layer laminate according to the invention. MEISSNER BOLTE M / VRG-196-PC

[0043] 9

[0044] According to a preferred embodiment of the invention, the polypropylene inner layer exhibits a maximum shrinkage of -2.5%, preferably -2% and particularly preferably -1.8% in the machine direction and a maximum shrinkage of -1%, preferably -0.8% and particularly preferably -0.5% in the transverse direction at a temperature of 130°C over a period of 30 minutes.

[0045] This highly advantageous property of the polypropylene inner layer of the sterilizable barrier layer laminate according to the invention is achieved by using a polypropylene film that, during its production, has been stretched and tempered and subsequently relaxed, wherein the stretching and tempering are carried out at a temperature in the range of 130°C to 145°C and the subsequent relaxation is achieved by reducing the speed of the last of the rollers used for stretching to a factor in the range of 0.9–0.99, preferably in the range of 0.95–0.975. In this way, a stretched polypropylene film could be produced according to the invention which, during a sealing process and / or sterilization, even in humid environments, and at a temperature of 130°C for a period of up to half an hour, exhibits practically no significant shrinkage or elongation.

[0046] A further significant advantage of such a polypropylene inner layer according to the invention is that the sterilizable barrier layer laminate according to the invention achieves a significantly improved stiffness compared to previous sterilizable barrier layer laminates, which on the one hand significantly improves the machine processability of the sterilizable barrier layer laminate according to the invention, and on the other hand significantly improves the feel and stability of packaging made from this barrier layer laminate.

[0047] In summary, the sterilizable barrier layer laminate according to the invention thus exhibits significantly higher stiffness, very good, especially straight, tear resistance, and very reduced, almost non-existent shrinkage compared to previously known sterilizable barrier layer laminates.

[0048] 10 significantly improved overall quality of the laminate itself and of packaging made from it, which is evident both visually and in terms of optimized sealability and thus also seal strength as well as sterilizability and also in a significantly more attractive appearance.

[0049] Thus, the sterilizable barrier layer laminate according to the invention can be easily sealed and sterilized even at high temperatures, such as those found in an autoclave, i.e., in a hot steam atmosphere at 120°C to 130°C under pressure, without the risk of shrinkage and / or stretching and / or becoming brittle and / or the associated risk of loss of the barrier layer.

[0050] Furthermore, the contact transparency can be adjusted towards any filling material, for example by adding titanium dioxide to the polypropylene inner layer to whiten the polypropylene inner layer.

[0051] According to a particularly preferred embodiment of the invention, the polypropylene inner layer has a two-layer structure, wherein a layer of the two-layer structure facing a sealing side comprises a, in particular soft, randomly heterophasic copolymer, for example of the polymer components polypropylene and polyethylene, with a copolymer matrix and two components of these randomly arranged copolymers, each having two different melt flow indices. Furthermore, a layer facing a laminating side, i.e.,The layer of the two-layer structure facing the polypropylene compound layer (50) comprises, in particular, a soft, randomly heterophasic copolymer, for example again consisting of the monomer units of polypropylene and polypropylene, with a copolymer matrix, which further comprises a heterophasic copolymer with a homo-polypropylene matrix and with a white masterbatch, wherein the layer facing the sealing side preferably corresponds to substantially one quarter to one third of the layer thickness of the layer of the two-layer structure facing the lamination side and both layers are preferably joined together by coextrusion.According to the invention, the layer facing the sealing side is a low-temperature sealing layer made of polypropylene, which melts at a temperature in the range of 110°C to 135°C, preferably at a temperature in the range of 120°C to 130°C, wherein the polypropylene, in particular in random arrangement, comprises a polyolefin with a lower melting point than polypropylene, preferably polyethylene, wherein the MEISSNER BOLTE M / VRG-196-PC.

[0052] 11

[0053] The polyolefin content has a lower melting point, preferably a polyethylene content of less than 50%, particularly preferably less than 35% and particularly preferably approximately 30%.

[0054] A significant advantage of the invention resulting from this two-layer structure is that such a stretched and relaxed polypropylene inner layer has an extremely low sealing start-up temperature, at which a very good sealing strength in the range of up to 200 N / 15 mm, but in any case greater than or equal to 100 N / 15 mm, can already be achieved.Such a very low sealing start temperature, which is extremely useful according to the invention, is achieved in particular by the fact that the two-layer structure used for the polypropylene inner layer is essentially composed of two parts, namely a relatively thick layer facing a laminating side and a comparatively relatively thin layer facing a sealing side, which in turn is ultimately responsible for the low sealing start temperature and the high sealing strength even at a low sealing temperature, while the side, or layer, facing the laminating side of the two-layer structure serves primarily to ensure the structural integrity and stability of the polypropylene inner layer.

[0055] Particularly with regard to preventing shrinkage of the sterilizable barrier layer laminate during a sealing process or heat sterilization, for example auto-kiaving, at elevated temperatures up to approximately 130 °C for a period of up to approximately half an hour, the use of the aforementioned oriented and relaxed two-layer polypropylene structure is an important point, since this oriented and relaxed, i.e.After the actual stretching of the two-layer polypropylene structure, the relaxed two-layer polypropylene structure as a component of the sterilizable barrier layer laminate according to the invention is particularly dimensionally stable even under elevated temperatures and, unlike previously known stretched polypropylene films, exhibits practically no significant shrinkage at temperatures up to 130°C ± 10% even under humid conditions and is nevertheless ideally suited as a low-temperature sealing layer with very good strength values ​​after sealing.

[0056] Furthermore, it should be noted that the polypropylene compound layer according to the invention is designed as an extrusion layer and is very thin in a material-saving manner MEISSNER BOLTE M / VRG-196-PC

[0057] 12. Thus, according to the invention, the polypropylene compound layer has a layer thickness in the range of 10 pm to 18 pm, preferably in the range of 12 pm to 17 pm and particularly preferably in the range of 15 pm to 16 pm.

[0058] As mentioned above, a significant advantage of the barrier layer laminate according to the invention is that this new barrier layer laminate is low in adhesive or essentially free of adhesives, and in particular free of polyurethane-based adhesives, so that it is precluded from the outset that adhesive can migrate into any contents of packaging made from this new barrier layer laminate and thereby contaminate the contents. Avoiding such contamination is particularly important with regard to the packaging of food, animal feed, and pharmaceuticals, and represents a significant advantage of the barrier layer laminate according to the invention.

[0059] A further significant advantage of the sterilizable barrier layer laminate according to the invention is its very good recyclability, which is based on the fact that the laminate according to the invention is almost pure and has a polypropylene content of greater than 91 wt.%, preferably greater than 95 wt.% and particularly preferably greater than 98 wt.%, in particular greater than 99 wt.%.

[0060] As a further particularly advantageous feature of the invention, it should also be noted that the laminate according to the invention can be sterilized non-destructively with hot steam, especially at a temperature in the range of 120°C to 130°C, which is based on the fact that the individual layers of the sterilizable barrier layer laminate according to the invention adhere extremely well and inseparably to one another, which is achieved according to the invention by extruding the polypropylene compound layer in a hot state between the polypropylene inner layer and the polypropylene outer layer having barrier properties, so that an intimate bond is already created between the polypropylene compound layer and the polypropylene inner layer due to the material properties.Compared to the multilayer barrier film, a primer layer also ensures an excellent bond between the polypropylene compound layer and the multilayer barrier film, so that the barrier layer laminate according to the invention is also resistant to hot steam and high temperatures in the range of 120 °C to 130 °C. MEISSNER BOLTE M / VRG-196-PC.

[0061] 13

[0062] Furthermore, the problem according to the invention is also solved by a method for producing a sterilizable barrier layer laminate according to the above descriptions, wherein the following steps are carried out:

[0063] According to the first variant mentioned above:

[0064] To provide a multi-layer barrier film comprising, from the outside in, the following layers: a polypropylene outer layer, at least one functional skin layer, an aluminum oxide layer, and a topcoating layer;

[0065] Printing the multilayer barrier film using a reverse printing process to create a reverse print; subsequent coating of the print, optionally using a printing process, with a primer layer to create a barrier layer structure;

[0066] Extruding a polypropylene compound layer between the barrier layer structure and the polypropylene inner layer using a polypropylene compound layer to create a bond between the barrier layer structure and the polypropylene inner layer to produce the sterilizable barrier layer laminate;

[0067] According to the second variant mentioned above: providing an outer oriented polypropylene layer;

[0068] Printing the outer polypropylene layer using a reverse printing process to create a reverse print; subsequent coating of the print with a first adhesive layer; providing a multilayer barrier film comprising, from the outside in, the following layers: a polypropylene outer layer, at least one functional skin layer, an aluminum oxide layer, a topcoat layer, and bonding the first adhesive layer to the polypropylene outer layer of the multilayer barrier film; MEISSNER BOLTE M / VRG-196-PC

[0069] 14

[0070] Bonding the topcoating layer to the polypropylene inner layer using a second adhesive layer to produce the sterilizable barrier layer laminate.

[0071] It should be noted here that the polypropylene outer layer, which may be stretched, preferably in the machine direction, has an inner coating of aluminum oxide, i.e., facing the direction of the polypropylene inner layer, to further improve the barrier effect, particularly against gases. This coating has virtually no effect on the transparency of the polypropylene outer layer. This aluminum oxide layer is a standard component of the multilayer barrier film.

[0072] Furthermore, the object of the invention, as mentioned above, is also achieved by using a sterilizable barrier layer laminate according to the above descriptions for the production of packaging, in particular food, animal feed or pharmaceutical packaging, whereby it should be particularly emphasized that, in particular due to the practically non-existent adhesive in the sterilizable barrier layer laminate according to the invention, excellent "cat acceptance" can be ensured for packaging produced from this barrier layer laminate.

[0073] The main points of the invention can therefore be summarized as follows.

[0074] A well-known sterilizable barrier laminate on the market is in the form of a triplex OPP (oriented polypropylene) / OPP barrier / PP (polypropylene) structure laminated with adhesive. Adhesives reduce the polypropylene content and thus the recyclability of the laminate.

[0075] According to the invention, by using extrusion lamination, both the polypropylene (PP) content and the recyclability of the barrier layer laminate can be increased.

[0076] According to the invention, a multilayer barrier film, consisting of a polypropylene outer layer, at least one functional skin layer, an aluminum oxide layer, and a topcoat layer, is printed with an extrusion primer. The printed multilayer barrier film is then extrusion laminated with a polypropylene sealing layer, i.e., the polypropylene inner layer. MEISSNER BOLTE M / VRG-196-PC

[0077] 15

[0078] An important advantage of the invention lies in the possibility of directly printing on the multilayer barrier film and the possibility of performing extrusion lamination of the printed multilayer barrier film, particularly for sterilization applications. A further important aspect of the invention is that the previously known structure of a sterilizable barrier layer laminate according to the prior art can be largely retained, and existing machines can be used for its production, if the previously known central polypropylene layer with silicon oxide coating is replaced by the multilayer barrier film according to the invention.With the extrusion primer used, a very good bond strength can be achieved for the sterilizable barrier layer laminate according to the above variant 1, while for the sterilizable barrier layer laminate according to the above variant 2, at least the inner adhesive layer facing any filler can be replaced by a very thin primer layer, thereby increasing the proportion of polypropylene in the barrier layer laminate while maintaining good coherence of the layers of the laminate and good barrier effect, and thus improving its recyclability.

[0079] The advantages of the invention can therefore be summarized as follows.

[0080] Increased polypropylene content of up to 99 wt.% compared to pure adhesive lamination according to the state of the art with max. 91 wt.%; resulting in increased recyclability of the barrier layer laminate; reduced number of polypropylene layers from three to two in variant 1; virtually free of adhesive; thus avoiding the migration risk of adhesive and improving cat acceptance of pouches or packaging for pet food or pharmaceutical applications;

[0081] These advantages are particularly enhanced by the use of a multi-layer barrier film according to the invention, the structure and properties of which are as follows.

[0082] The multilayer barrier film consists of an OPP film with a polyamide skin layer. Mixtures of amorphous and crystalline polyamide resins can be used for the skin layer. MEISSNER BOLTE M / VRG-196-PC

[0083] 16

[0084] The layers of the OPP film with the polyamide skin layer are simultaneously stretched, resulting in improved shrinkage during sealing and sterilization processes, especially at elevated temperatures, as specified above.

[0085] The OPP film with the polyamide skin layer has a thickness of preferably 25 pm.

[0086] The barrier layer film according to the invention is suitable for sterilization, since all resins meet all regulatory requirements for sterilization.

[0087] The barrier layer film according to the invention has heat stability during sterilization and sealing, with shrinkage in the oven at 130 °C / 30 min being < 3 % in MD (machine direction) and TD (transverse direction).

[0088] The surface of the polyamide skin layer is suitable for an all-in-one (AIO) application without the need for a primer. x-Deposition is well suited because the polyamide skin layer provides a polar and uniform skin layer surface.

[0089] The oxygen barrier of the finished laminate, at a temperature of 23°C and a relative humidity of 50%, after sterilization according to the above specification, has an oxygen permeability rate (OTR) of < 1.0 cm³ / m². 2 *Day.

[0090] The water vapor barrier of the finished laminate, after sterilization according to the above specification at a temperature of 38°C and a relative humidity of 90%, has a water vapor permeability (WVTR) of <1.3 g / m². 2 *Day.

[0091] The bond strength of the polyamide skin layer to the aluminum oxide (PA / AIOx) after sterilization according to the above specification is > 2 N / 15 mm.

[0092] The bond strength of the oriented polypropylene (polypropylene inner layer) to polypropylene (polypropylene compound layer), or generally OPP / PP, is > 2 N / 15 mm after sterilization according to the above specification. MEISSNER BOLTE M / VRG-196-PC

[0093] 17

[0094] Further embodiments of the invention are set out in the dependent claims.

[0095] The invention is described below with reference to two exemplary embodiments, which are explained in more detail with reference to the figures. These show:

[0096] Fig. 1 shows a schematic representation of a sterilizable barrier layer laminate according to the prior art;

[0097] Fig. 2 shows a schematic representation of the sterilizable barrier layer laminate according to the invention in a preferred embodiment of the invention according to variant 1;

[0098] Fig. 3 shows a schematic representation of the sterilizable barrier layer laminate according to the invention in an embodiment of the invention according to variant 2;

[0099] Fig. 4 shows a schematic representation of the structure of the OPP film according to the invention with the skin layer made of polyamide according to one embodiment of the invention.

[0100] In the following description, the same reference numbers are used for identical and equivalent parts.

[0101] Fig. 1 shows a barrier layer laminate 10' according to the prior art. This barrier layer laminate 10' has an outer polypropylene layer 20' which is provided with a reverse print 30. This polypropylene layer 20', including the reverse print 30, is bonded to a central polypropylene layer 70 by means of a first adhesive layer 81. The central polypropylene layer 70 is in turn bonded to an inner polypropylene layer 60' by means of a further, i.e., second, adhesive layer 82. The central polypropylene layer 70, which provides the barrier layer, also has a coating of aluminum oxide and / or silicon oxide facing towards the first adhesive layer 81.

[0102] Fig. 2 shows a schematic representation of the sterilizable barrier layer laminate 10 according to the invention in a preferred embodiment of the invention according to variant 1, wherein this barrier layer laminate 10 according to the invention has only two polypropylene layers (20, 60), namely a multilayer barrier film 21 with a MEISSNER BOLTE M / VRG-196-PC

[0103] 18

[0104] The total layer thickness is slightly more than 25 µm. The multilayer barrier film 21 has an outer polypropylene outer layer 20 and an adhesion promoter layer 24, to which a functional skin layer 22 in the form of a layer of a mixture of amorphous and crystalline polyamide resins is attached. An aluminum oxide layer 25 is attached to this skin layer 22, and a solvent-containing polyacrylic acid layer as a topcoat layer 23 is attached to this aluminum oxide layer 25. The topcoat layer 23 has a print 30 on its inner side, i.e., facing a polypropylene inner layer 60, which is not part of the multilayer barrier film 21. The sterilizable barrier layer laminate 10 according to the invention has a second polypropylene inner layer 60 with a layer thickness of either 60 µm or 80 µm.This polypropylene inner layer 60 can be colored white, for example with titanium dioxide, to achieve the desired contact transparency. These two polypropylene layers are joined together by means of a polypropylene bonding layer 50, which is extruded between the multilayer barrier film 21 and the polypropylene inner layer 60 in a warm or hot state. Adhesion to the print 30 applied to the multilayer barrier film 21 is optimized by applying a primer layer 40 to the print 30.

[0105] Fig. 3 shows a schematic representation of the sterilizable barrier layer laminate according to the invention in an embodiment of the invention according to variant 2. This embodiment corresponds essentially to the barrier layer laminate shown in Fig. 1, except that the central polypropylene layer 70 is replaced by the multilayer barrier film 21 according to the invention. Furthermore, the second adhesive layer 82 can be a primer layer 40 according to this variant 2.

[0106] Fig. 4 shows a schematic representation of the structure of the polypropylene outer layer 20 according to the invention, i.e., the OPP film, with the functional skin layer 22 made of polyamide or of a mixture of polyamide and ethylene vinyl alcohol copolymer according to one embodiment of the invention. The polypropylene outer layer 20, i.e., the OPP film, is bonded to the functional skin layer 22 by means of an adhesion promoter layer 24.

[0107] According to this embodiment, the polypropylene outer layer 20 itself is composed of three layers, namely a first and innermost first layer 20a with MEISSNER BOLTE M / VRG-196-PC

[0108] The polypropylene outer layer 20 consists of a first layer 20a with a thickness of 20.2 pm, a middle second layer 20b with a thickness of 1.5 pm, and an outermost third layer 20c with a thickness of 1.0 pm. The innermost first layer 20a of the polypropylene outer layer 20 is bonded to the functional skin layer 22 by an adhesive layer 24, which serves as an adhesion promoter 24. The adhesive layer 24 has a thickness of 1.5 pm and consists of a polypropylene-based adhesion promoter. The functional skin layer 22 consists of a mixture of amorphous and crystalline polyamide resin and has a thickness of 0.8 pm.

[0109] The polypropylene outer layer 20, together with the adhesive layer 24 and the functional skin layer 22, is part of the multilayer barrier film 21 according to the invention, wherein the aforementioned structure in the multilayer barrier film 21 according to the invention is additionally supplemented by an aluminum oxide layer 25 and a topcoating layer 23.

[0110] In a highly advantageous manner, an excellent oxygen barrier of less than 1.0 cm can be achieved using this multilayer barrier film 21, for example according to the variants shown in Fig. 2 and Fig. 3. 3 / square meter per day at a temperature of 23°C and a relative humidity of 50%, as well as excellent resistance to water vapor, namely less than 1.3 g / square meter per day at a temperature of 38°C and a humidity of 90%, which is maintained in particular even after sterilization at a temperature of 130°C for a period of 30 minutes.

[0111] Similarly, the bond strengths between polyamide and aluminium oxide, as well as between oriented polypropylene and polypropylene, reach values ​​greater than 2 N / 15 mm after sterilization at a temperature of 130°C for a period of 30 minutes, with shrinkage at 130°C for 30 minutes in an oven being < 3% in both the machine direction and the transverse direction.

[0112] It should be noted here that all parts described above, considered individually and in any combination, especially the details shown in the drawings, are claimed as essential to the invention. Modifications to this are familiar to those skilled in the art. MEISSNER BOLTE M / VRG-196-PC

[0113] 20

[0114] Reference symbol list

[0115] 10' laminate according to the state of the art

[0116] 10 laminate

[0117] 20' outer polypropylene layer

[0118] 20 Polypropylene outer layer

[0119] 20a first layer of the polypropylene outer layer

[0120] 20b second layer of the polypropylene outer layer

[0121] 20c third layer of the polypropylene outer layer

[0122] 21 Multi-layer barrier film

[0123] 22 functional skin layer

[0124] 23 Topcoat layer

[0125] 24 liability mediators

[0126] 25 Aluminum oxide layer (AIO) x -Layer)

[0127] 30 printing

[0128] 40 primer layer

[0129] 50 Polypropylene compound layer

[0130] 60 Polypropylene inner layer

[0131] 60' inner polypropylene layer

[0132] 70 central polypropylene layer

[0133] 81 first adhesive layer

[0134] 82 second adhesive layer

Claims

Huhtamaki Flexible Packaging Germany September 1, 2025 GmbH & Co. KG M / VRG-196-PC PF / lz Sterilizable barrier layer laminate, as well as methods for manufacturing the laminate and its use Claims 1. Sterilizable barrier layer laminate (10) comprising a polypropylene outer layer (20) having barrier properties, a reverse print (30), a primer layer (40) applied to the print (30), and a polypropylene inner layer (60) arranged opposite the polypropylene outer layer (20), wherein a primer layer (40) is arranged on the reverse print (30) and a polypropylene compound layer (50) is extruded between the primer layer (40) and the polypropylene inner layer (60), and wherein the polypropylene outer layer (20) is an outermost layer of a multilayer barrier film (21) which, viewed from the outside inwards, i.e. from the polypropylene outer layer (20) towards the polypropylene inner layer (60), comprises the following layers: at least one functional skin layer layer (22), an aluminum oxide layer (25), and a topcoating layer (23).

2. Sterilizable barrier layer laminate (10) comprising an outer polypropylene layer (20'), a reverse print (30) and a polypropylene inner layer (60) arranged opposite the outer polypropylene layer (20'), wherein a multilayer barrier film (21) is arranged between the outer polypropylene layer (20'), in particular between the reverse print (30), and the polypropylene inner layer (60), the barrier film comprising, from the outside in, i.e. from the outer polypropylene layer (20') towards the polypropylene inner layer (60), the following layers: a polypropylene outer layer (20), at least one functional skin layer (22), an aluminum oxide layer (25), and a topcoating layer (23), wherein the multilayer film (21) is bonded on both sides to the reverse print (30) and to the polypropylene inner layer (60) by means of an adhesive layer (80).

3. Laminate according to one of the preceding claims, characterized in that MEISSNER BOLTE M / VRG-196-PC 2 the functional skin layer (22) has a layer thickness in the range of 0.2 pm to 1.5 µm, preferably in the range of 0.4 pm to 1.0 pm and particularly preferably in the range of 0.6 pm to 0.9 pm and consists of polyamide (PA) or ethylene vinyl alcohol copolymer (EVOH) or a mixture of polyamide and ethylene vinyl alcohol copolymer, wherein these two substances are either in a substantially homogeneous mixture with each other and / or as two adjacent coextruded layers.

4. Laminate according to one of the preceding claims, characterized by the fact that the polypropylene outer layer (20) is multilayered, for example three-layered, in particular consisting of highly crystalline polypropylene layers, optionally an adhesion promoter (24), for example in the form of an adhesive or primer, and the at least one functional skin layer (22), wherein these layers are co-extruded together and have an at least uniaxial orientation, preferably in the machine direction, and wherein the adhesion promoter (24) is arranged between the highly crystalline polypropylene layer(s) and the functional skin layer (22), and the total thickness of the polypropylene outer layer (20) is in the range of 10 pm to 40 pm, preferably in the range of 15 pm to 30 pm and particularly preferably in the range of 18 pm to 25 pm.

5. Laminate according to claim 4, characterized by the fact that the adhesion promoter (24) is polypropylene-based and has a layer thickness in the range of 0.2 pm to 1.8 pm, preferably in the range of 0.4 pm to 1.6 pm and particularly preferably in the range of 0.6 pm to 1.5 pm.

6. Laminate according to one of the preceding claims, characterized by the fact that the topcoating layer (23) comprises or consists of one or more of the following materials: polyacrylic acid, ethylene vinyl alcohol copolymer and / or polyvinyl alcohol copolymer and has a layer thickness in the range of 0.2 pm to 1.8 pm, preferably in the range of 0.4 pm to 1.6 pm and particularly preferably in the range of 0.6 pm to 1.5 pm.

7. Laminate according to one of the preceding claims, characterized by the fact that the primer layer (40) has a layer thickness in the range of 0.1 pm to 3 pm, MEISSNER BOLTE M / VRG-196-PC 3 preferably in the range of 0.5 pm to 2 pm and particularly preferably in the range of 1 pm to 1.5 pm.

8. Laminate according to one of the preceding claims, characterized by the fact that the primer layer (40) is applied to the printing by means of a printing process or by means of extrusion.

9. Laminate according to one of the preceding claims, characterized by the fact that the polypropylene inner layer (60) has a layer thickness in the range of 35 pm to 100 pm, preferably in the range of 50 pm to 90 pm and particularly preferably in the range of 60 pm to 80 pm.

10. Laminate according to one of the preceding claims, characterized by the fact that the polypropylene inner layer (60) has an orientation, preferably in the machine direction, and at a temperature of 130°C over a period of 30 minutes has a maximum shrinkage of -2.5%, preferably -2% and particularly preferably -1.8% in the machine direction and a maximum shrinkage of -1%, preferably -0.8% and particularly preferably -0.5% in the transverse direction.

11. Laminate according to one of the preceding claims, characterized by the polypropylene compound layer (50) having a layer thickness in the range of 10 pm to 18 pm, preferably in the range of 12 pm to 17 pm and particularly preferably in the range of 15 pm to 16 pm.

12. Laminate according to any of the preceding claims, characterized by the fact that the laminate (10) is free of polyurethane-based adhesive.

13. Laminate according to one of the preceding claims, characterized by the fact that the laminate (10) has a polypropylene content of greater than 91 wt.%, preferably greater than 95 wt.% and particularly preferably greater than 98 wt.%, in particular greater than 99 wt.%. MEISSNER BOLTE M / VRG-196-PC 4 14. Laminate according to one of the preceding claims, characterized in that the laminate (10) can be sterilized non-destructively with hot steam, in particular at a temperature in the range of 120°C to 130°C.

15. Method for producing a sterilizable barrier layer laminate (10) according to one of the preceding claims, characterized by the following steps: providing a multilayer barrier film (21) comprising, from the outside inwards, the following layers: a polypropylene outer layer (20), at least one functional skin layer (22), an aluminum oxide layer (25), a topcoating layer (23); Printing the multilayer barrier film (21) using a reverse printing process to create a reverse print (30); subsequent coating of the print (30), optionally by means of a printing process, with a primer layer (40) to create a barrier layer structure; extruding a polypropylene compound layer (50) between the barrier layer structure and the polypropylene inner layer (60) to create a bond between the barrier layer structure and the polypropylene inner layer (60) to produce the sterilizable barrier layer laminate; or by the following steps: providing an outer oriented polypropylene layer (20'); Printing the outer polypropylene layer (20') using a reverse printing process to create a reverse print (30); subsequently coating the print (30) with a first adhesive layer (81); providing a multilayer barrier film (21) comprising, from the outside in, the following layers: a polypropylene outer layer (20), at least one functional skin layer (22), a MEISSNER BOLTE M / VRG-196-PC 5 aluminium oxide layer (25), a topcoating layer (23) and joining the first adhesive layer (81) with the polypropylene outer layer (20) of the multilayer barrier film (21); Joining the topcoating layer (23) to the polypropylene inner layer (60) by means of a second adhesive layer (82) to produce the sterilizable barrier layer laminate.

16. Use of a sterilizable barrier layer laminate (10) according to any one of the preceding claims 1 to 14 for the manufacture of a container, in particular packaging, especially food, animal feed or drug packaging.

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