Packaging laminate

Abstract

In order to provide a packaging laminate (1) with good recyclability, lower carbon footprint and which allows conversion into packaging, especially with sufficient mechanical properties, like bending stiffness, and shelf life, the packaging laminate (1) having a coextruded central connecting layer (4) sandwiched between a first BOPP layer (2) and a second BOPP layer (3), wherein at least one of the first and second BOPP layer (3) has a layer thickness between 4 µm and 18 µm, preferably between 4 µm and 12 µm, wherein the central connecting layer (4) comprises a central bulk PP layer (9) with at least 70 wt% PP, preferably at least 80 wt% PP, and at least one laminate tie layer (7), wherein the laminate tie layer (7) is coextruded next to the bulk PP Layer (9) and wherein the thickness of the central connecting layer (4) is thicker than the thinner of the first BOPP layer (2) and the second BOPP layer (3), and wherein the packaging laminate (1) comprises at least 90 wt% PP, and wherein the central connecting layer (4) is connected to the first BOPP layer (2) or to the second BOPP layer (3) via the laminate tie layer (7).

Description

[0001] Packaging Laminate

[0002] The present invention pertains to a package laminate and to a method for producing the packaging laminate.

[0003] Today, packaging laminates are multilayer plastic films comprising several different layers, also dependent on their application. Typical packaging laminates are structures comprising layers of different materials. A typical duplex structure is BOPP I printing ink (with primer) I tie layer / PE bulk layer / Aluminium (Al) metallised BOPP, in which two biaxially oriented polypropylene (BOPP) films are connected with each other via a PE (polyethylene) bulk layer and the tie layer. “ / ” stands for a direct contact at the interface of two adjacent layers (reading from left to right means from outside to inside of the laminate structure, where the inside is the side of the laminate structure which is facing to the filling good in the converted packaging). BOPP is a biaxially oriented polypropylene (PP) and a metallised BOPP is such a biaxially oriented polypropylene that is metallised, with aluminium, for example, on one side (usually the side facing the opposite BOPP layer). That aluminium layer is deposited on the substrate by vacuum deposition process (PVD). The metallisation is usually applied over the full area of the substrate surface, but in special cases it can also be applied partially, like in a so- called strip metallisation, for example. The printing ink layer may also comprise a primer layer over the print facing the tie layer. The two outer BOPP layers are rather thick and have layer thicknesses of typically 15 to 18 pm. Due to the thick outer BOPP layers, the central PE layer can be thinner, applied with a coating weight of typically 7 to 13 g / m2for achieving the desired mechanical properties (like bending stiffness) of the laminate. With densities of PE materials between 0,915 (LDPE) to 0,97 g / cm3(HDPE), this results in layer thicknesses of the central PE layer in the range of about 7 pm to 15 pm. In general, in known packaging laminates, the outer BOPP layers are thicker than the inner bulk layer. Such a packaging laminate is used for pouches for crisps, for example. However, packaging laminates are also used for non-food packaging applications, for example for pouches or flowpacks.

[0004] The problem with such layer structures is the limited recyclability (if the laminate is recyclable at all), especially mechanical recyclability, due to the different materials comprised in the laminate, which in addition are distributed in a disadvantageous sequence in terms of layer thicknesses (and grammages for that layers). The different layers with the different materials are required to give the packaging laminate the required or necessary technical characteristics and properties, like bending stiffness, puncture resistance, barrier properties (water vapor, oxygen, aroma, light / U V barrier) and so on. The barrier property is important for sufficient shelf life, for example. The bending stiffness is important for achieving the required mechanical stability of the laminate and packaging. The puncture resistance is important to allow handling of the packaging. Beside these characteristics, also further or different characteristics can play a role for the desired packaging, dependent on the application.

[0005] Apart from the limited recyclability, such a packaging laminate does also have a high carbon footprint as certain raw materials and energy is required for the production of the packaging laminate. The high carbon footprint is mainly caused by the energy intensive stretching step for producing the BOPP layers, which is usually done on a sequential tenter-frame stretching line.

[0006] It is therefore an object of the present invention to provide a packaging laminate with good recyclability, lower carbon footprint and which allows conversion into packaging, especially with sufficient mechanical properties, like stiffness, and shelf life.

[0007] This object is achieved with a method for producing the packaging laminate and with a packaging laminate according to the independent claims. By coextruding a central connecting layer with the high amount of PP between the two BOPP layers, the outer BOPP layers may be reduced in thickness and the thickness of the central connecting layer of PP may be increased in thickness dependent on the requirements (bending stiffness, for example) of the application of the packaging laminate. This leads to a packaging laminate with reduced carbon footprint but without losing mechanical properties. Due to the predominantly PP material in the packaging laminate, the recyclability of the packaging laminate is also increased and allows even mechanical recycling.

[0008] A packaging laminate with high internal bonding strength can be achieved when coextruding the central connecting layer with a first laminate tie layer on a first side of the bulk PP layer and second laminate tie layer on an opposite second side of the bulk PP layer, wherein the central bulk PP layer is sandwiched between the first laminate tie layer and the second laminate tie layer, so that the central connecting layer is connected to the first BOPP layer via the first laminate tie layer and to the second BOPP layer via the second laminate tie layer.

[0009] The carbon footprint of the packaging laminate can be further decreased, when the thickness of the central laminate film is thicker than the first BOPP layer and the second BOPP layer.

[0010] For applications of the packaging laminate with high barrier requirements, it is advantageous when at least one of the first BOPP layer and second BOPP layer comprises at least one barrier layer. The barrier layer can be a coating layer, preferably a metal oxid layer, organic coating layer or a metallisation layer, or a layer of a barrier polymer, preferably EVOH or PA, or a barrier lacquer layer, preferably a PVOH, BVOH, Ethylen-PVOH copolymer, or semicrystalline Polyurethane based or containing lacquer, or a combination of at least two of a coating layer, preferably a metal oxid layer, organic coating layer or a metallisation layer, a layer of a barrier polymer, preferably EVOH or PA, and a barrier lacquer layer, preferably a PVOH, BVOH, Ethylen-PVOH copolymer, or semicrystalline Polyurethane based or containing lacquer. This gives great flexibility in choosing the right material for the barrier layer according to the application of the packaging laminate.

[0011] In an advantageous embodiment, the barrier layer is a layer of a barrier polymer, preferably EVOH or PA, and the first BOPP layer or the second BOPP layer with the barrier layer comprises at least two PP layers with the barrier layer being arranged between two of the at least two PP layers. This allows integration and protection of the barrier layer within the respective BOPP layer.

[0012] In order to increase the bonding strength in the BOPP layer with a barrier polymer barrier layer, a barrier tie layer is arranged between the barrier polymer and an adjacent PP layer. When the barrier polymer is embedded between two PP layers of the BOPP layer, then the barrier tie layer can be provided on each side of the barrier polymer.

[0013] In a possible embodiment, the barrier layer is arranged between a PP layer of the first BOPP layer or the second BOPP layer and the central connecting layer and in that a laser-barrier lacquer is provided between the PP layer and the barrier layer. The laser-barrier lacquer provides protection against laser beams with which the packaging laminate is treated, for example perforated, for certain applications. The laser energy is absorbed by the laser-barrier lacquer and, hence, cannot damage the barrier layer.

[0014] In a further advantageous embodiment, one of the first BOPP layer and second BOPP layer is printed on at least one of its sides, optionally with an additional primer, or one of the first BOPP layer and second BOPP layer is printed with a washable ink, optionally in contact with a washable primer, on its side facing away from the central laminate layer, wherein a washable protective lacquer is applied over the print with the washable ink. The washable ink allows removal of the print before recycling of the packaging laminate.

[0015] The present invention is described below in greater detail with reference to Figs.1 to 6, which show schematic and non-limiting advantageous embodiments of the invention by way of example. In the drawings:

[0016] Fig.1 shows the basic structure of the inventive packaging laminate,

[0017] Fig.2, 2a and 3 to 5 show possible embodiments of the structure of the packaging laminate and

[0018] Fig.6 shows a production line for producing the packaging laminate. In a typical packaging laminate as used today, two BOPP (biaxially oriented polypropylene) films are connected with each other by a connecting layer arranged between the two outer BOPP layers. The connecting layer is usually applied by an extrusion lamination process in which the connecting layer is extruded between the two outer BOPP layers. Depending on the required bonding strength between the layers of the packaging laminate, an additional tie layer can be (and is usually) provided between a BOPP layer and the connecting layer. A typical known packaging laminate has the structure BOPP (15 pm to 18 pm) I print I tie-layer I polyethylene (PE) connecting layer (7 to 13 g / m2) / Al metallization layer / BOPP (15 pm to 18 pm). The Al metallization is provided on the BOPP layer.

[0019] Such a packaging laminate is hardly (mechanically) recyclable because of the mixture of PP and PE polymers in the laminate. Mechanical recycling is basically the process of recovering plastic waste by mechanical processes such as sorting, washing, drying, grinding, re-granu- lating and compounding. Apart from that, the step of biaxially stretching a PP film, in a sequential tenter-frame production line, for example, is energy-intensive and the required energy increases with increasing thickness of the BOPP layer. Therefore, such a packaging laminate with BOPP layers has inherently a high carbon footprint, mainly determined by their related thicknesses, measured in microns of meter [pm], for example.

[0020] The thickness of the BOPP layer in such packaging laminates is necessary because of the required mechanical properties of the packaging laminate, especially the bending stiffness of the packaging laminate or the puncture resistance, but also because of the required barrier properties of the packaging laminate in order to achieve the necessary shelf life of the packed filling good. In order to be able to convert the packaging laminate into pouches, the laminate needs a certain bending stiffness, for example.

[0021] Therefore, in the inventive packaging laminate 1, the two outer BOPP layers are made thinner as compared to the conventional packaging laminate. But thinner BOPP layers would affect the mechanical properties of the packaging laminate 1, especially the bending stiffness. Therefore, according to the invention, the thickness of the connecting layer, arranged between the two outer BOPP layers, is increased, and can be more increased as the outer BOPP layers are simultaneously decreased in their thicknesses. The two outer BOPP layers contribute more to the bending stiffness as the central connecting layer. Consequently, it is not necessary to increase the thickness of the central connecting layer too much. The thicknesses of the two outer BOPP layers and of the central connecting layer can be adapted to the required properties of the packaging laminate 1 , especially to the required bending stiffness. Despite more material is provided in the connecting layer (as compared to conventional packaging laminates) it has been found that the carbon footprint of the total packaging laminate is significantly reduced, especially when the thicknesses of the two outer BOPP layers (or at least one of them) is being reduced to a certain minimum thickness, that is technically reasonable or feasible (in terms of production). This is mainly due to the fact, that thinner BOPP layers require less energy for the biaxial stretching process, which results in a lower carbon footprint. The global warming potential measured in kg CO2-eq (carbon dioxide equivalent) per kg PP-layer is about 0,25kg higher for cast BOPP compared to cast PP, for example. Therefore, reducing the amount of biaxially stretched PP in the packaging laminate 1 and increasing the PP amount in the central connecting layer decreases the (cumulative) carbon footprint of the packaging laminate 1. Last but not least, the central connecting layer in the inventive packaging laminate 1 is predominantly made of PP materials. This results in a packaging laminate 1 predominantly made of PP materials (monomaterial laminate), which is recyclable, also in conventional mechanical recycling processes. The PP resins, used in the connecting layer and / or at least in one of the BOPP layers, can even contain recycled material, preferably selected from PP-based post-industrial waste, and / or material made from renewable sources, in order to further reduce carbon footprint of the packaging laminate 1 , for instance reasoned by a mass-balance calculation.

[0022] The inventive packaging laminate 1 , as shown in Fig.1 , is a multilayer plastic film with three main layers, namely a first BOPP layer 2, a second BOPP layer 3 and a central connecting layer 4 that is sandwiched between the first BOPP layer 2 and the second BOPP layer 3. The central connecting layer 4 is directly connected to the first BOPP layer 2 on one of its sides and to the second BOPP layer 3 on its other side. The structure of the packaging laminate 1 in this embodiment is first BOPP layer 2 I central connecting layer 41 second BOPP layer 3, whereas “ / ” stands for a direct contact at the interface between two adjacent layers.

[0023] The connecting layer 4 comprises a central PP layer with at least 70 wt% PP (weight %), preferably at least 80 wt% PP, wherein the thickness of the central connecting layer 4 is thicker than the thinner of the first BOPP layer 2 and the second BOPP layer 3, preferably thicker than the first BOPP layer 2 and the second BOPP layer 3. The total packaging laminate 1 comprises at least 90 wt% PP, in order to achieve sufficient recyclability, e.g. for mechanical recycling. The maximum amount of PP of a single layer of the packaging laminate 1 or in the packaging laminate 1 is of course 100 wt%, which is however usually not achieved because of additives used in the different layers and / or because of low amounts of other non-PP materials in the packaging laminate 1.

[0024] In the following the structure and the function of the different layers of the packaging laminate 1 is described in more detail.

[0025] The first BOPP layer 2 and the second BOPP layer 3 are films with thicknesses between 4 pm and 18 pm, preferably between 4 pm and 12 pm. The BOPP layers are usually prefabricated films, according to state of the art, like in a cast film or blown film extrusion process. It would be technically possible to provide BOPP layers as thin as 1 pm, but for packaging applications the useful thickness starts at 4 pm, in order to allow good technical characteristics for instance for converting. It would also be possible to provide BOPP layers with thicknesses above 18 pm, but this would be disadvantageous with regard to the carbon footprint of the packaging laminate 1 as explained above. Therefore, at least one of the first and second BOPP layers 2, 3, preferably both of them, has a layer thickness between 4 pm and 18 pm, preferably between 4 pm and 12 pm. The thicknesses of the first BOPP layer 2 and the second BOPP layer 3 in the packaging laminate 1 can be the same or can also be different.

[0026] The first BOPP layer 2 and / or the second BOPP layer 3 can itself be multi-layered, depended on its manufacture. The first BOPP layer 2 and / or the second BOPP layer 3 can be manufactured by extrusion or coextrusion of the PP material, for example by cast film extrusion or blown film extrusion. The PP material can be a PP homopolymer or a PP (block or random) copolymer (for example a copolymer comprising ethylene and / or higher alpha-olefins). The extruded or coextruded PP film is then biaxially stretched, i.e. stretched in machine direction and transverse direction (transverse the machine direction), according to state-of-the-art.

[0027] The first BOPP layer 2 and the second BOPP layer 3 may comprise low amounts of typical additives, like a stabilizing agent, an agent facilitating processing, an adhesion agent, a filler, a plasticiser and so on, but not more than 5 wt% of additives.

[0028] At least one of the first BOPP layer 2 and the second BOPP layer 3 can be printed on one of its outer sides. The print layer 6 (indicated in Fig.1 in dashed line) can be arranged in the packaging laminate 1 at the inside (reverse printing), i.e. facing the central connecting layer 4 or at the outside, i.e. facing away from the central connecting layer 4. Especially in the latter case, the print layer 6 can be made with a washable ink, wherein a protective lacquer is applied over the print with the washable ink. The protective lacquer can also be washable. As an option there can be placed a primer between the ink and the BOPP surface, this primer (lacquer) can also be washable. This allows an easy removal of the print layer 6 (with a protective lacquer or a primer), in or before a recycling process, for example. To this end, a suitable solvent (or mixture of solvents), for instance a ketone, acetate or an alcohol, or mixtures of it, for the washable ink (and optionally also for the washable primer and protective lacquer) can be used for removing the print layer 6 by a washing process. The grammage of such a protective lacquer can be very low, usually below 0,5g / m2dry coating weight (or below 0,5pm thickness), preferably not more than 0,3g / m2(dry). In another advantageous embodiment, at least one of the first BOPP layer 2 and second BOPP layer 3 comprises at least one barrier layer 5. In this case, the first BOPP layer 2 and / or the second BOPP layer 3 can be multi-layered having at least one PP layer 2a, 2b, 3a, 3b and a barrier layer 5. The barrier layer 5 can be applied before or after biaxially stretching the PP layer(s) 2a, 2b, 3a, 3b of the first BOPP layer 2 and / or the second BOPP layer 3.

[0029] The barrier layer 5 can be provided on the inside (as in Fig.2), i.e. the side of the first BOPP layer 2 and / or the second BOPP layer 3 facing the central connecting layer 4, or on the outside (as in Fig.3), i.e. the side of the first BOPP layer 2 and / or the second BOPP layer 3 facing away from the central connecting layer 4. The additional barrier layer 5 can however also be provided within the first BOPP layer 2 and the second BOPP layer 3, for example embedded between two PP layers 2a, 2b of the first BOPP layer 2 and / or embedded between two PP layers 3a, 3b of the second BOPP layer 3 (as in the example of Fig.4). In the latter case, the barrier layer 5 would also be biaxially stretched together with the respective PP layer.

[0030] In an embodiment of the invention, the barrier layer 5 is a coating layer, preferably a metal oxide layer, like an aluminium oxide (AlOx)-layer or silicon oxide (SiOx)-layer (the metalloid Silicon is regarded as metal in this regard), “x” indicates that the metal oxide layer may be present in different states of oxidation. But barrier layer 5 in form of the coating layer is not limited to an inorganic layer, like a AIOx layer, but can also be an organic layer, like silicon oxycarbid (SixOyCz), for example. Besides that, mixtures of different metal oxides, like AIOx, SiOx, can be also used as well. The coating can be applied to the first BOPP layer 2 and / or second BOPP layer 3 by well-known coating techniques like vacuum, sputter or chemical vapor deposition processes. In case of a coating, the barrier layer 5 is applied after biaxially stretching the PP layer(s) 2a, 2b, 3a, 3b of the first BOPP layer 2 and / or the second BOPP layer 3. In another embodiment, the barrier layer 5 is a metallisation layer, like an aluminium or copper layer. The metallization can be applied by well-known metallization techniques like vacuum (PVD), sputter or chemical vapor deposition (OVD) processes. In case of a metallization, the barrier layer 5 is applied after biaxially stretching the PP layer(s) 2a, 2b, 3a, 3b of the first BOPP layer 2 and / or the second BOPP layer 3. The layer thickness of a coating or metallization layer is typically in the nanometer order of magnitude, preferably 30nm to 50nm.

[0031] For the metal oxide layer, like AIOx or SiOx layers, thicknesses between 8nm are 30nm are usual, each due to limitations which are described well in the state of the art and literature. It is also an option to place a protective lacquer or additional barrier lacquer on top of the coating or metallization. This lacquer can be comprised of PVOH, EVOH, E / PVOH, BVOH, semicrystalline polyurethane, or mixtures of it. Typically, the application weight of such lacquers is below 1g / m2(dry), preferably below 0,5g / m2(dry), more preferably below 0,3g / m2(dry).

[0032] In order to enhance the anchorage of such barrier coatings, comprising for instance AIOx, SiOx, SixOyCz or aluminium metallization or other metal metallization, on the surface of the substrate it is applied, it is also possible to add an additional chemical surface pre-treatment, like a primer layer (lacquer), or a physical surface pre-treatment, like corona-, plasma- or flame-treatment on the respective PP surface, before depositing the AIOx, SiOx, SixOyCz or metallization on top of that surface treated surface. The chemical pre-treatment is typically applied with very thin thicknesses of 0,3pm or below, but preferably 0,1 pm and below. There can also be applied (in addition or alternatively to pre-treatment) a post-treatment of the vacuum-deposited layer by plasma-treatment, which is applied directly after the deposition of the vacuum-deposited coating in the vacuum chamber, what is well known by vacuum deposition experts.

[0033] In yet another embodiment, the barrier layer 5 is at least one layer of a barrier polymer. A barrier polymer is a polymer with high barrier properties against oxygen, water vapor and / or aroma. The barrier property is typically measured as oxygen transmission rate (OTR) or water transmission rate (WVTR). As is well-known, the OTR or WVTR is dependent on temperature and relative humidity is often given as cm3 / (m2*day) at x°C, y% relative humidity, x is often 23°C and y often 50% relative humidity for measuring OTR according to DIN 53380-3 and a permeant concentration of 100% oxygen for the measurement setup, x is often 38°C and y often 90% relative humidity for measuring WVTR according to DIN EN ISO 15106-3 or DIN EN ISO 15106-2, where the measurement-cell facing to the sensor is dry with a relative humidity of 0%, given for the measurement setup. In typical packaging laminates, the OTR is between 0,05 and 100 cm3 / (m2*day) and the WVTR is between 0,05 and 10g / (m2*day), given for measurement conditions like described above. The barrier property against aroma cannot be measured by norm, but is usually determined empirically (sensory, executed by educated specialists). Often used barrier polymers are ethylene vinyl alcohol copolymer (EVOH), usually comprising a mol% of 24-48% ethylene, or polyamide (PA), for instance PA6. The barrier polymer can be coextruded with the PP layer(s) of the first BOPP layer 2 and / or the second BOPP layer 3 and biaxially stretched with the PP layer(s) afterwards. The barrier polymer can also be bonded to the BOPP layer, by lamination techniques using lamination adhesives, for example. Stretching a barrier polymer usually increases the barrier effect of the barrier polymer, as is well-known, mainly due an increase of its crystallinity, caused by a higher degree of orientation of molecular chains, which is being induced by the stretching process. The barrier polymer, and if present also the barrier tie-layer(s) 8, are typically applied with a thickness between 0,5 pm and 5 pm, preferably 0,7 - 3pm (the thinner the better), but in any case, in such a thickness, that the total amount of PP contained in the packaging laminate 1 does not fall below 90 wt%.

[0034] In case of a barrier polymer, like EVOH or PA, as barrier layer 5, it is also conceivable to use a barrier tie layer 8 between a PP layer 2a, 2b, 3a, 3b of the first BOPP layer 2 and / or the second BOPP layer 3 and the barrier polymer. Fig.2a exemplarily shows a first BOPP layer 2 with a barrier tie layer 8 between the barrier layer 5 and the PP layer 2a. In an embodiment as in Fig.5 with a barrier layer 5 embedded between PP layers 3a, 3b, a tie layer could be provided on each side of the barrier layer 5. Such a barrier tie layer 8 improves the bonding strength between the PP layer(s) 2a, 2b, 3a, 3b and the barrier polymer. The barrier tie layer 8 could be made of Maleic anhydride grafted PP (PP-g-MAH) or a Maleic anhydrid grafted PE (PE-g-MAH), EAA or EMAA, for example.

[0035] The barrier polymer as barrier layer 5 could be coextruded with the other PP layer(s) 2a, 2b, 3a, 3b of the first BOPP layer 2 and / or the second BOPP layer 3, also together with additional barrier tie layers 8 when present. Alternatively, the barrier layer 5 could be laminated to the other PP layer(s) 2a, 2b, 3a, 3b using a suitable lamination adhesive. A suitable adhesive could be a polyolefine-based adhesive (preferably a PE or PP based), and is for instance a solvent-based dry-lamination adhesive.

[0036] In case of reverse printing, described above, a barrier layer 5 can be placed on the printed first BOPP layer 2 and / or the second BOPP layer 3, which is not in contact with the print layer 6. That allows to protect the barrier functionality of the packaging laminate 1 , even if the printed BOPP layer 2, 3 is (micro-)perforated (mechanically perforated or perforated by laserscoring or laser technology) on the side facing the connecting layer 4. Such a (micro-)perfo- ration allows a drastically higher diffusion rate of the solvent passing through the BOPP layer 2, 3 for removing the print in recycling, since the solvent molecules are passing with quite fast velocity and thus with relatively high quantities of molecules per second through the perforation holes / tunnels. The number (per m2, for example) and geometries of that holes / tun- nels, may be adapted to improve the diffusion rate. The holes / tunnels may by formed wide enough in diameter and long enough in distance (tunnel length), so that ideally the complete thickness of the BOPP layer 2, 3 is locally removed at the area and volume of that holes / tunnels. The number and geometries of the holes / tunnels can be adapted in order to optimize the diffusion rates of the used solvent, passing through. As a result of such (micro-perforations, a relatively short time being needed for the delamination of the packaging laminate 1 during recycling and finally achieves the complete removal of the inks (protective lacquer and primer). This delamination and ink removal procedure works especially well if the washable ink layer is covering preferably all of the area of the BOPP layer 2, 3 surface. The (micro)per- forations would not affect the barrier layer 5 as the barrier layer 5 is not in contact with the print layer 6 and, hence, the barrier effect of the barrier layer 5 would not be affected.

[0037] In order to further protect the full functionality of the barrier layer 5, in cases where the packaging laminate 1 is manipulated (perforated, for example) by a laser beam, and for instance the packaging laminate 1 is comprised of barrier layer 5 in form of a metal oxide coating or metallization on one of the BOPP layers 2, 3 and this coating or metallization is facing towards the other BOPP layer, optionally an additional, so called laser-barrier lacquer can be placed between the coating and the metallization and the BOPP layer 2, 3 of the such treated BOPP layer 2, 3. Such laser-barrier lacquer are well-known in the field and may be chosen by the person skilled in the art in accordance with the application of the packaging laminate 1. The laser-barrier lacquer is able to significantly absorb and / or reflect the energy of the laser(-beam ) when laser beam is entering this layer, before that laser beam can hit the barrier layer 5 and cause a damage on it (and thus on its quality of barrier or barrier functionality). Since a damage would result in a deterioration of the barrier functionality by, for instance, creating holes in the coating or metallization. The grammage of such kind of a laserbarrier lacquer can be low, usually below 2,5g / m2dry weight (or below 2,5pm thickness), preferably not more than 1 ,5g / m2(dry). The composition and application methods for such kind of laser-barrier lacquer lacquers are quite well known by coating experts and can also be found in dedicated literature.

[0038] Last but not least, in yet another embodiment, the barrier layer 5 is applied as barrier lacquer layer. In this case a barrier polymer is dissolved in a solvent and is applied in liquid form on the PP layer(s) 2a, 2b, 3a, 3b and dried afterwards. The barrier lacquer can be on basis of or containing polyvinyl alcohol copolymer (PVOH), EVOH or butendiol vinyl alcohol copolymer (BVOH), Ethylen-PVOH-copolymer, semicrystalline polyurethane or mixtures of it. The barrier lacquer is typically applied with a thickness of 0,1 to 1 g / m2(dry), preferably 0,3-0,7g / m2, but in any case, in such a thickness, that the total PP amount of the packaging laminate 1 does not fall below 90 wt%.

[0039] A combination of at least two of above-mentioned barrier layers is also conceivable. Hence, the barrier layer 5 could be a combination of a barrier polymer (e.g. EVOH, PA) with a metal oxide coating, in general inorganic or organic coating, or an additional metallization or an additional barrier lacquer, like EVOH I metal oxide or EVOH / Al or EVOH I PVOH lacquer, for example, or a combination of a barrier lacquer and a metal oxide coating or an additional metallization, like PVOH lacquer / metallization, for example. That means that the sequence of the applied lacquers on top of the substrate can be widely variable. It can also be an option, to have the metal oxide coating or metallisation layer embedded between two barrier lacquers. Such combinations would provide especially high barrier properties (like ultra-high barrier), for high barrier applications of the packaging laminate 1 , for example.

[0040] In order to enhance the anchorage (bonding) of any of the barrier related layers mentioned above on the surface of the substrate (like a PP layer 2a, 2b, 3a, 3b) there can be applied an additional (lacquer, tie) layer or pretreatment layer on the surface of the substrate, like for instance a plasma-, flame- or corona-treatment. Additionally, for achieving highest anchorage a chemical treatment layer is also possible to apply, for instance a layer of (about) 0,1 pm of a polyethyleneimine-based primer (lacquer), according to state of the art.

[0041] BOPP layers 2, 3, also with barrier layers 5, especially a BOPP, which is containing an EVOH barrier layer, are commercially available. Such BOPP layers only need to be printed as required before they are used to manufacture a packaging laminate 1. Such BOPP layers could also be treated as described above, for applying a barrier layer 5, lacquer, barrier tielayer 8, for example.

[0042] The main material of the connecting layer 4 is PP that is comprised in a bulk PP layer 9 comprising at least one PP layer 4a. The PP material of the bulk PP layer 9 of the connecting layer 4 can be a PP homopolymer or a PP (block or random) copolymer (for example a copolymer comprising ethylene and / or higher alpha-olefins). Depending on the available extrusion line and / or depending on the application of the packaging laminate 1 , the bulk PP layer 9 can comprise a single PP layer 4a or can also be multilayered, with several PP layers 4a (Fig.5). Also a mixture of different PP materials in the bulk PP layer 9 is conceivable, also provided in different PP layers 4a of the bulk PP layer 9, in case of a multilayered bulk PP layer 9. It is also possible to use different PP materials in different PP layers 4a of the connecting layer 4 or to have PP layers 4a of different thicknesses.

[0043] In order to improve processability of the PP material (for extrusion) and / or to increase the bonding strength, maximum 30 wt% polyethylene (PE) materials could be added to the PP bulk material of the connecting layer 4. As PE material to be added to the PP bulk material all types of polyethylene and copolymer of ethylene are possible, as long as the processability of the PP material is not hampered. The amount of PE in the connecting layer 4 should however be as low as possible, but in any case, in such a low amount, that the total PP amount of the packaging laminate 1 does not fall below 90 wt%.

[0044] The connecting layer 4 does also include at least one laminate tie layer 7 as shown in Fig.5, preferably two laminate tie layers 7 (shown in Fig.5 in dashed line). The main task of the laminate tie layer 7 is to ensure sufficient bonding strength between the connecting layer 4 and the adjacent first BOPP layer 2 or second BOPP layer 3, or to be more precise between the connecting layer 4 and the surface of the adjacent first BOPP layer 2 or second BOPP layer 3 facing the connecting layer 4. Consequently, a laminate tie layer 7 is provided at the outside of the connecting layer 4, i.e. facing the first BOPP layer 2 and / or the second BOPP layer 3 in the packaging laminate 1 , and is in direct contact with the first BOPP layer 2 and / or the second BOPP layer 3. The bonding strength to be achieved is dependent on the application of the packaging laminate 1 and is usually specified. The bonding strength is usually measured as the force that is required to pull two layers apart.

[0045] The bonding strength is measured in accordance with DIN 55543-5 (in the version valid at the time of the application). For measuring the bonding strength, the laminate layers of the sample of width 15mm are pulled apart on a dedicated testing machine with different pulling angles and with a linear constant pulling speed. A typical minimum bonding strength is higher than 0,5 N / 15mm (pulling angle 90° and pulling speed 50mm / min), preferably more than 1,0N / 15mm, and most preferably more than 2,0N / 15mm. For instance, for measuring the pulling force or separation force a tensile testing machine of company Zwick is common to use.

[0046] A laminate tie layer 7 usually provides the required bonding strength in the packaging laminate 1 and the materials used in the laminate tie layer 7 are usually more expensive than the other PP materials, used in the laminate structure. Therefore, and also for reason of recyclability, the thickness of a laminate tie layer 7 should be as thin as possible. The thickness of a laminate tie layer 7 is preferably between 1 pm and 2 pm.

[0047] A laminate tie layer 7 can be PE based or PP based, whereas also mixtures of PE I PP are conceivable as material for the laminate tie layer 7. A PE based tie layer usually provides higher bonding strengths but would decrease the total PP amount in the packaging laminate 1. In order to achieve high PP amounts in the packaging laminate 1 , a PP based tie layer 7 or a PP based tie layer 7 with low amounts (maximum 35 wt%) of PE based tie layer material is preferred.

[0048] Typical PE based materials for the laminate tie layer 7 are for instance Ethylene Acrylic Acid Copolymer (EAA), Ethylene Methacrylic Acid (EMAA), Maleic anhydride-modified derivates of the latter one, Maleic anhydride grafted polyethylene (PE-g-MAH), or mixture or terpolymers thereof. A typical PP based materials for the laminate tie layer 7 is for instance Maleic anhydride grafted PP (PP-g-MAH), either based on PP homopolymers or PP copolymers.

[0049] The structure of the connecting layer 4 is therefore A / B or A / B / A or A / B / C, with A, C being a laminate tie layer 7 and B being a bulk PP layer 9 (single layered or multilayered). When the laminate tie layers A, C are different, the laminate tie layers 7 can be selected according to the structure and specification of the packaging laminate 1 . Also the available extrusion line may affect the possible structure of the connecting layer 4. When only a two-layer coextrusion is possible, then the structure is limited to A / B or A / B / A, for example.

[0050] When the packaging laminate 1 comprises a print layer 6, for example, it is known that direct bonding a PP layer onto the printing ink of the print layer 6 results in poor bonding strengths. Bonding can be improved by providing a laminate tie layer 7 between the print layer 6 and the bulk PP layer 8 of the connecting layer 4 (A / B structure). A possible laminate tie layer 7 can be made of random ethylene-methyl acrylate-maleic anhydride terpolymer, Lotader 4503 from SK functional polymer, for example. Such a laminate tie layer 7 does also provide a good bonding to PP or to a barrier layer 5, like a metallization or barrier polymer. Therefore, such a laminate tie layer 7 could also be provided between the other BOPP layer 2, 3 and the bulk PP layer 9 (structure A / B / A). When a printing line allows application of (water-based) primer, Mica A-131X of Mica Corporation, for example, over the print, then simpler composed tie layer materials could be used, as the primer increases the bonding strength. In such a case, EAA could be used in the laminate tie layer 7 between the print layer 6 and the bulk PP layer 8. When the simpler composed laminate tie layer 7 does not provide sufficient bonding strength to the opposite BOPP layer 2, 3, especially when it is provided with a barrier layer 5, then a different laminate tie layer 7 (A / B / C structure) can be provided as well.

[0051] With a first BOPP layer 2 and second BOPP layer 3 with given or specified layer thickness it is possible to adapt or affect the bending stiffness of the packaging laminate 1 via the central connecting layer 4, especially via the bulk PP layer 9. The bending stiffness can be affected by the thickness of the central connecting layer 4, especially the thickness of the bulk PP layer 9. The thicker the bulk PP layer 9, the higher the bending stiffness of the packaging laminate 1 will become. The bending stiffness of the packaging laminate 1 may also, or in addition to the thickness, be influenced by the resulting tensile modulus of the central connecting layer 4, especially of the bulk PP layer 9. The tensile modulus may be affected by choosing PP homopolymers for the bulk PP layer 9, which PP homopolymers are stiffer than PP copolymers. Using stiffer PP homopolymers, such having a preferable high Young’s modulus with a minimum of 1300MPa, may also allow to make the bulk PP layer 9 thinner (for a given desired bending stiffness).

[0052] This is reasoned by the fact, that the bending stiffness of a laminate is basically affected by the combined adjustment of the Young modulus of each layer of the laminate and their thickness distribution.

[0053] The bending stiffness is measured in accordance with ISO 2493-1 (in the version valid at the time of the application). The preferred range of the bending stiffness is between a minimum bending stiffness and a maximium bending stiffness, depending on the application of the packaging laminate 1. For typical packaging applications, the minimum bending stiffness is 1 ,5 mN, preferably 2 mN, more preferably 5 mN and especially preferably 10 mN. For typical packaging applications, the maximum bending stiffness is 35 mN, preferably 20 mN, and more preferably 15 mN.

[0054] The connecting layer 4 with the bulk PP layer 9 and the at least one laminate tie layer 7 is coextruded. As explained above, different materials are used in the connecting layer 4. In order to facilitate the coextrusion, the materials are preferably selected or chosen so that the different layers of the connecting layer 4 can be coextruded together. This can also be dependent from the available extrusion line. A person skilled in the art is able to do that using his experience or experiments. Possible material parameters could be the viscosity of the used materials, the melt strength or the melt flow index (MFI). For PE materials an MFI of 2 to 15g / 10 min (190°C, 2,16kg) may be suitable, and for PP materials an MFI of 10 to 40g / 10 min (230°C, 2,16kg). In order to achieve the required material properties, like the MFI, blends or mixtures of different materials may be used in the different layers of the connecting layer 4.

[0055] Additionally, it is possible to partially print a BOPP layer 2, 3 with not more than 30% surfacearea print coverage (e.g. by rotogravure printing). It is also possible to provide a heat-seal lacquer on at least one of the outer surfaces of the first BOPP layer 2 and / or the second BOPP layer 3, in order to modify the sealability of the respective BOPP layer 2, 3. Such additional sealing lacquers would be added to the packaging laminate 1 in such a low amount, that the total PP amount of the packaging laminate 1 does not fall below 90 wt%.

[0056] It is also possible that instead of such a sealing lacquer a decorative or tactile lacquer is placed on the outer surface of a BOPP layer 2, 3, in order to modify the optical or tactile characteristics of the packaging laminate 1 , for instance in order to allow matte or matte / gloss effects for special “eye-catching” visual appearance, or paper-like haptics for special end-consumer experiences, when touching the final packaging. It is possible to apply such a lacquer partially on the surface of the BOPP layer 2, 3. Such additional lacquers are added to the packaging laminate 1 in such a low amount, that the total PP amount of the packaging laminate 1 does not fall below 90 wt%.

[0057] It is also possible that at least one of the BOPP layers 2, 3 is containing a LDPE / / LLDPE- based outer skin-layer in order to also modify the sealing characteristics of the packaging laminate 1 , for instance if sealing for a lap-seal setup is being needed. Such skin-layers are typically rather thin, like usually not more than 2pm, preferably below 1 ,5pm, and most preferably below 1 pm, and are applied by coextrusion process together with the PP layer(s) 2a, 2b, 3a, 3b before biaxially stretching the film. Such additional sealing (skin-)layers are added to the packaging laminate 1 in such a low amount, that the total PP amount of the packaging laminate 1 does not fall below 90 wt%.

[0058] The inventive packaging laminate 1 is manufactured in that the first BOPP layer 2 and the second BOPP layer 3 are provided, possibly with a barrier layer 5 and all other additional layers and treatments, as described above. The first BOPP layer 2 and the second BOPP layer 3 could be provided as films wound on a roll 11 , for example, as shown in Fig.6. The central connecting layer 4 in the structure A / B or A / B / A or A / B / C is coextruded between the first BOPP layer 2 and the second BOPP layer 3 using a coextrusion machine 12. The coextrusion machine 12 comprises one (or more) extruder 13 and a coextrusion die 14, for example. The coextrusion process is well-known and can be realised as cast film coextrusion (as in Fig.6) or as blown film coextrusion. The coextruded connecting layer 4 is led between the first BOPP layer 2 and the second BOPP layer 3, so that the connecting layer 4 is sandwiched between the first BOPP layer 2 and the second BOPP layer 3. Possible guiding rolls for guiding the first BOPP layer 2, the second BOPP layer 3 and the connecting layer 4 are not shown in Fig.6. The first BOPP layer 2, the second BOPP layer 3 and the connecting layer 4 arranged in between are then pressed together by (optionally heated) pressing rolls 17, 18 (in the so-called lamination nip), for example. When the coextruded connecting layer 4 cools down, the first BOPP layer 2, the second BOPP layer 3 and the connecting layer 4 are firmly bonded together. The final packaging laminate 1 may then be wound on a coil 15, or led to further processing, in a packaging line, for example. In Fig.6, also a printing machine 16 is shown to apply a print layer 6 onto one of the BOPP layers 2, 3 (reverse print in Fig.6) before bonding the first BOPP layer 2, the second BOPP layer 3 and the coextruded connecting layer 4 together.

[0059] Possible embodiments of the resulting packaging laminate 1 have the following structure (“ / ” stands for a direct contact at the interface between two adjacent layers), for example:

[0060] BOPP layer 2 (8 pm) I bulk PP layer 9 (16 pm) I EAA laminate tie layer 7 (1 pm) I Al metallized (0,03pm) BOPP layer 3 (8 pm) (or that layer up to 18 pm)

[0061] BOPP layer 2 (8 pm) I EAA laminate tie layer 7 (1 pm) I bulk PP layer 9 (16 pm) I EAA laminate tie layer 7 (1 pm) I Al metallized (0,03pm) BOPP layer 3 (8 pm) (or that layer up to 18 pm)

[0062] BOPP layer 2 (8 pm) I print layer 6 with primer I EAA laminate tie layer (1 pm) I bulk PP layer 9 (16 pm) I EAA laminate tie layer 7 (1 pm) I Al metallized BOPP layer 3 (8 pm) (or that layer up to 18 pm) In above examples, instead of the Al metallized BOPP layer a EVOH (0,7 pm) I BOPP layer (15 pm) may be used, also including a barrier tie-layer 8 of 0,7pm PP-g-MAH or PE-g-MAH, or in case if such EVOH-layer is embedded in the BOPP layer itself, two barrier tie-layers 8.

[0063] BOPP layer 2 (8 pm) I EAA laminate tie layer 7 (1 pm) I bulk PP layer 9 (16 pm) I EAA laminate tie layer 7 (1 pm) I EVOH barrier layer 5 (0,7 pm) I PP-g-MAH barrier tie layer 8 (0,7 pm) I BOPP layer 3 (8 pm) (or that layer up to 18 pm)

[0064] BOPP layer 2 (8 pm) I EAA laminate tie layer 7 (1 pm) I bulk PP layer 9 (16 pm) I EAA laminate tie layer 7 (1 pm) I EVOH barrier layer 5 (0,7 pm) I barrier tie layer 8 (0,7 pm) I PP layer 4a (4 pm) of BOPP layer 31 PP-g-MAH barrier tie layer 8 (0,7 pm) I PP layer 4a (4 pm) of BOPP layer 3

[0065] Also a metal oxide (AIOx and / or SiOx) I EVOH (0,7 pm) I BOPP layer (15 pm) (or that layer up to 18 pm) or a metal (Al or Cu) or an organic deposited-coating instead of metal oxide could be used instead of the Al metallized BOPP layer in any of the cases above.

[0066] BOPP layer 2 (4pm) (optional Al metallized or AIOx or SiOx coated) I EAA laminate tie layer 7 (1 pm) I bulk PP layer 9 (16 pm) I EAA laminate tie layer 7 (1 pm) I AIOx or SiOx coated BOPP layer (8 pm) (or that layer up to 18 pm)

[0067] Print layer 6 (optionally with primer) / BOPP layer 2 (4pm) (optional Al metallized or AIOx or SiOx coated, each facing direction is possible) I EAA laminate tie layer 7 (1 pm) I bulk PP layer 9 (16 pm) I EAA laminate tie layer 7 (1 pm) I Al metallized (optionally AIOx or SiOx coated instead of Al metallized) BOPP layer 3 (8 pm) (or that layer up to 18 pm)

[0068] Protective lacquer (0,3pm) I Print layer 6 (optionally with primer I BOPP layer 2 (4pm) (optional Al metallized or AIOx or SiOx coated, each facing direction is possible) I EAA laminate tie layer 7 (1 pm) I bulk PP layer 9 (16 pm) I EAA laminate tie layer 7 (1 pm) I Al metallized (optionally AIOx or SiOx coated instead of Al metallized) BOPP layer 3 (8 pm) (or that layer up to 18 pm)

[0069] Washable Print layer 6 with washable primer / BOPP layer 2 (4pm) (optional Al metallized or AIOx or SiOx coated, each facing direction is possible) I EAA laminate tie layer 7 (1 pm) I bulk PP layer 9 (16 pm) I EAA laminate tie layer 7 (1 pm) I Al metallized (optionally AIOx or SiOx coated instead of Al metallized) BOPP layer 3 (8 pm) (or that layer up to 18 pm)

[0070] Washable Protective lacquer (0,3pm) I Washable Print layer 6 with washable primer / BOPP layer 2 (4pm) (optional Al metallized or AIOx or SiOx coated, each facing direction is possible) / EAA laminate tie layer 7 (1 pm) / bulk PP layer 9 (16 pm) / EAA laminate tie layer 7 (1 m) I Al metallized (optionally AIOx or SiOx coated instead of Al metallized) BOPP layer 3 (8 pm) (or that layer up to 18 pm)

[0071] In all examples above another suitable material could be used in one of the laminate tie layers 7, like EMAA, PE-g-MAH or PP-g-MAH. In the examples above another suitable material could be used in one of the barrier tie layers 8 (if present), like EMAA, EAA, PE-g-MAH.

[0072] In a possible embodiment, two BOPP films as described above may also be bonded together to form the first BOPP layer 2 or the second BOPP layer 3. This can be done by providing at least one of the two BOPP films with a thin skin layer, preferably 1 pm to 2 pm thick. The skin layer could be applied during manufacture of the BOPP film, like coextruded with the PP and then biaxial ly stretched together with the PP. The skin layer can be PE of any suitable type, like low density PE (LDPE) or linear-low density PE (LLDPE), middle density PE (MDPE) or high density PE (HDPE), PE copolymer, for example, or mixtures of it. The two BOPP films may then be bonded together by thermo-pressing the two films together. In the manufacturing process as described with respect to Fig.6, it would be possible to provide an additional BOPP film with such a skin layer facing the first BOPP layer 2. The additional BOPP film with the skin layer would be pressed together (for instance with a line-pressure of 3 to 5 bar in the lamination-nip) with the other BOPP film to form the first BOPP layer 2, the connecting layer 4 and the second BOPP layer 3 between the pressing rolls 13. In the lamination nip heat can be applied and transferred to the skin layers for the thermo-pressing step, in order to achieve sufficiently high bond strength. Such an additional BOPP layer may be applied on one side (asymmetric structure) or on both sides of the packaging laminate 1 (symmetric structure). The advantage would be that the packaging laminate 1 could be produced in one go and without the use of any lamination adhesives (in most cases such adhesives are on basis of polyurethane (Pll), and can be i.e. solvent-based, solventless or water-borne adhesives), in a typical thickness range of 1,5 - 5pm. Furthermore, the chemical constitution of such an adhesive is not limited to polyurethane, it can be also comprising polyolefin-based adhesives, applied also in a typical thickness range of 1,5 - 5pm. Such adhesives can be used for thermal lamination purposes or dry lamination purposes, according to state-of-the-art.

Claims

Claims1. Method for producing a packaging laminate (1) comprising the steps ofProviding a first BOPP layer (2) and a second BOPP layer (3), wherein at least one of the first BOPP layer (2) and second BOPP layer (3) has a layer thickness between 4 pm and 18 pm, preferably between 4 pm and 12 pm,Coextruding a central connecting layer (4), wherein the central connecting layer (4) comprises a central bulk PP layer (9) with at least 70 wt% PP, preferably at least 80 wt% PP, and at least one laminate tie layer (7), wherein the laminate tie layer (7) is coextruded next to the bulk PP Layer (9) and wherein the thickness of the central connecting layer (4) is thicker than the thinner of the first BOPP layer (2) and the second BOPP layer (3), and wherein the packaging laminate (1) comprises at least 90 wt% PPBonding the central connecting layer (4) to the first BOPP layer (2) and to the second BOPP layer (3) such that the central connecting layer (4) being sandwiched between the first BOPP layer (2) and the second BOPP layer (3) and thereby connecting the central connecting layer (4) to the first BOPP layer (2) or to the second BOPP layer (3) via the laminate tie layer (7).

2. Method according to claim 1 , characterised, in that the method comprises coextruding the central connecting layer (4) with a first laminate tie layer (7) on a first side of the bulk PP layer (9) and second laminate tie layer (7) on an opposite second side of the bulk PP layer (9), wherein the central bulk PP layer (9) is sandwiched between the first laminate tie layer (7) and the second laminate tie layer (7) and in that the central connecting layer (4) is connected to the first BOPP layer (2) via the first laminate tie layer (7) and to the second BOPP layer (3) via the second laminate tie layer (7).

3. Method according to claim 1 or 2, characterised, in that the thickness of the central connecting layer (4) is thicker than the first BOPP layer (2) and the second BOPP layer (3).

4. Method according to one of claims 1 to 3, characterised, in that at least one of the first BOPP layer (2) and second BOPP layer (3) comprises at least one barrier layer (5).

5. Method according to claim 4, characterised, in that the barrier layer (5) is a coating layer, preferably a metal oxid layer, organic coating layer or a metallisation layer, or a layer ofa barrier polymer, preferably EVOH or PA, or a barrier lacquer layer, preferably a PVOH, BVOH, Ethylen-PVOH copolymer, or semicrystalline Polyurethane based or containing lacquer, or the barrier layer (5) is a combination of at least two of a coating layer, preferably a metal oxid layer, organic coating layer or a metallisation layer, a layer of a barrier polymer, preferably EVOH or PA, and a barrier lacquer layer, preferably a PVOH, BVOH, Ethylen- PVOH copolymer, or semicrystalline Polyurethane based or containing lacquer.

6. Method according to claim 4, characterised, in that the barrier layer (5) is a layer of a barrier polymer, preferably EVOH or PA, and the first BOPP layer (2) or the second BOPP layer (3) with the barrier layer (5) comprises at least two PP layers (2a, 2b, 3a, 3b) with the barrier layer (5) being arranged between two of the at least two PP layers (2a, 2b, 3a, 3b).

7. Method according to claim 4, characterised, in that the barrier layer (5) is a layer of a barrier polymer, preferably EVOH or PA, and the first BOPP layer (2) or the second BOPP layer (3) with the barrier layer (5) comprises at least one PP layer (2a, 2b, 3a, 3b) with the barrier layer (5) being connected to the at least one PP layer (2a, 2b, 3a, 3b) and facing the central connecting layer (4) or facing away from the central connecting layer (4).

8. Method according to any of claims 6 to 7, characterised, in that a barrier tie layer (8) is arranged between the barrier polymer and an adjacent PP layer (2a, 2b, 3a, 3b).

9. Method according to any of claims 4 to 8, characterised, in that the barrier layer (5) is arranged between a PP layer (2a, 2b, 3a, 3b) of the first BOPP layer (2) or the second BOPP layer (3) and the central connecting layer (4) and in that a laser-barrier lacquer is provided between the PP layer (2a, 2b, 3a, 3b) and the barrier layer (5).

10. Method according to claim 9, characterised, in that the PP layer (2a, 2b, 3a, 3b) comprises perforations.

11. Method according to one of claims 1 to 10, characterised, in that one of the first BOPP layer (2) and second BOPP layer (3) is printed on at least one of its sides, optionally with an additional primer, or one of the first BOPP layer (2) and second BOPP layer (3) is printed with a washable ink, optionally in contact with an washable primer, on its side facing away from the central laminate layer, wherein a washable protective lacquer is applied over the print with the washable ink.

12. Method according to any of claims 1 to 11 , characterised, in that the bulk PP layer (9) is coextruded as multilayer structure comprising at least two PP layers (4a).

13. Packaging laminate having a coextruded central connecting layer (4) sandwiched between a first BOPP layer (2) and a second BOPP layer (3), wherein at least one of the first and second BOPP layer (3) has a layer thickness between 4 pm and 18 pm, preferably between 4 pm and 12 pm, wherein the central connecting layer (4) comprises a central bulk PP layer (9) with at least 70 wt% PP, preferably at least 80 wt% PP, and at least one laminate tie layer (7), wherein the laminate tie layer (7) is coextruded next to the bulk PP Layer (9) and wherein the thickness of the central connecting layer (4) is thicker than the thinner of the first BOPP layer (2) and the second BOPP layer (3), and wherein the packaging laminate (1) comprises at least 90 wt% PP, and wherein the central connecting layer (4) is connected to the first BOPP layer (2) or to the second BOPP layer (3) via the laminate tie layer (7).

14. Packaging laminate according to claim 13, characterised, in that the central connecting layer (4) comprising a laminate tie layer (7) on each side of the bulk PP layer (9) so that the bulk PP layer (9) is sandwiched between the two laminate tie layers (7), and in that the central connecting layer (4) is connected to the first BOPP layer (2) via one of the laminate tie layers (7) and to the second BOPP layer (3) via the other one of the laminate tie layers (7).

15. Packaging laminate according to claim 13 or 14, characterised, in that the thickness of the central connecting layer (4) is thicker than the first BOPP layer (2) and the second BOPP layer (3).

16. Packaging laminate according to one of claims 13 to 15, characterised, in that at least one of the first BOPP layer (2) and second BOPP layer (3) comprises at least one barrier layer (5).

17. Packaging laminate according to claim 16, characterised, in that the barrier layer (5) is a coating layer, preferably a metal oxid layer, organic coating layer or a metallisation layer, or a layer of a barrier polymer, preferably EVOH or PA, or a barrier lacquer layer, preferably a PVOH, BVOH, Ethylen-PVOH copolymer, or semicrystalline Polyurethane based or containing lacquer, or the barrier layer (5) is a combination of at least two of a coating layer, preferably a metal oxid layer, organic coating layer or a metallisation layer, a layer of a barrier polymer, preferably EVOH or PA, and a barrier lacquer layer, preferably a PVOH, BVOH, Ethylen-PVOH copolymer, or semicrystalline Polyurethane based or containing lacquer.

18. Packaging laminate according to claim 16, characterised, in that the barrier layer (5) is a layer of a barrier polymer, preferably EVOH or PA, and the first BOPP layer (2) or the second BOPP layer (3) with the barrier layer (5) comprises at least two PP layers (2a, 2b, 3a,3b) with the barrier layer (5) being arranged between two of the at least two PP layers (2a, 2b, 3a, 3b).

19. Packaging laminate according to claim 16, characterised, in that the barrier layer (5) is a layer of a barrier polymer, preferably EVOH or PA, and the first BOPP layer (2) or the second BOPP layer (3) with the barrier layer comprises at least one PP layer (2a, 2b, 3a, 3b) with the barrier layer (5) being connected to the at least one PP layer (2a, 2b, 3a, 3b) and facing the central connecting layer (4) or facing away from the central connecting layer (4).

20. Packaging laminate according to one of claims 16 to 19, characterised, in that a barrier tie layer (8) is arranged between the barrier polymer and an adjacent PP layer (2a, 2b, 3a, 3b).

21. Packaging laminate according to one of claims 13 to 20, characterised, in that the barrier layer (5) is arranged between a PP layer (2a, 2b, 3a, 3b) of the first BOPP layer (2) or the second BOPP layer (3) and the central connecting layer (4) and in that a laser-barrier lacquer is provided between the PP layer (2a, 2b, 3a, 3b) and the barrier layer (5).

22. Packaging laminate according to claim 21 , characterised, in that the PP layer (2a, 2b, 3a, 3b) comprises perforations.

23. Packaging laminate according to one of claims 13 to 22, characterised, in that one of the first BOPP layer (2) and second BOPP layer (3) is printed on at least one of its sides, optionally with an additional primer, or one of the first BOPP layer (2) and second BOPP layer (3) is printed with a washable ink, optionally in contact with an washable primer, on its side facing away from the central laminate layer, wherein a washable protective lacquer is applied over the print with the washable ink.

24. Packaging laminate according to one of claims 13 to 23, characterised, in that the bulk PP layer (9) is coextruded in the central connecting layer (4) as multilayer structure comprising at least two PP layers (4a).

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