Aluminum-containing laminated packaging material with improved recyclability

Abstract

The present invention relates generally to the field of laminated packaging. In particular, the present invention relates to a laminated flexible package comprising aluminum and a plastic sealant layer present on only one side of the aluminum. One embodiment of the present invention relates to a laminated flexible package made at least in part from a laminated flexible packaging material comprising an aluminum foil layer, a plastic sealant layer, and a coating, wherein the aluminum foil layer is laminated to the plastic sealant layer on a side facing the packaged product, and the other side of the aluminum foil layer is coated with a coating but is not laminated to a plastic or paper layer, and the laminated flexible package is produced from the laminated flexible packaging material on a horizontal form, fill, and seal (HFFS) machine.

Description

Technical Field

[0001] The present invention generally relates to the field of laminated packaging. In particular, the present invention relates to a laminated flexible packaging comprising aluminum and a plastic sealant layer present only on one side of the aluminum. One embodiment of the present invention relates to a laminated flexible packaging at least partially made from a laminated flexible packaging material comprising an aluminum foil layer, a plastic sealant layer and a coating, the aluminum foil layer being laminated to the plastic sealant layer on the side facing the packaged product, the other side of the aluminum foil layer being coated with a coating but not laminated to a plastic layer or a paper layer, and the laminated flexible packaging being manufactured from the laminated flexible packaging material by a horizontal or vertical form-fill-seal machine.

Background Art

[0002] Laminated structures with aluminum foil are widely used in packaging because aluminum foil offers many advantages, including exceptional barrier performance, fold retention, a specific tactile feel, and a specific appearance. In the category of flexible packaging formed in horizontal fill-fill-seal (HFFS) or vertical fill-fill-seal (VFFS) lines, the current state of the art of aluminum foil-containing laminated flexible packaging materials suggests that the aluminum foil layer is laminated not only on the side facing the product, but also on the other side (outside) with an additional layer containing either paper or PET film, or matte OPP film, or another plastic film (examples of final laminated structures with aluminum foil include PET / Alu / PE, PET / Alu / PET / PE, PET / Alu / PP, PET / Alu / OPA / PP, OPP / Alu / PE, paper / Alu / PE, paper / PE / Alu / PE, etc.). One important function of the outer film in the current state of the art is that it is possible to apply images by reverse printing on the outer film rather than printing directly on the surface of the aluminum foil. Other important functions of the outer film in current state-of-the-art solutions are to protect the aluminum foil from exposure to various types of mechanical abuse, including abrasion and puncture, and to modify the surface friction and mechanical properties of the laminate to ensure high packaging efficiency, defined as the ability to rapidly manufacture tight (airtight) flexible packaging on an HFFS or VFFS line without causing holes and breaks in the aluminum foil layer resulting from stretching of the film when pulled through the packaging line, or from impacts to the seam area when a heated seal jaw strikes and compresses the packaging material to create a seal, or from abrasion and breakage that may occur in the laminate while being pulled on static metal elements of the packaging line. In current state-of-the-art designs described for laminated flexible packaging in which aluminum foil is sandwiched between two layers of plastic or a layer of plastic and a layer of paper, the weight percentage of aluminum in the packaging material is, in principle, less than 30%.

[0003] However, current levels of flexible packaging compositions are inferior to packaging solutions containing at least 30% by weight of aluminum from the perspective of packaging life management. Existing optimal life management for aluminum-containing flexible packaging includes the collection of packaging waste, sorting at material recovery facilities (MRFs), and recycling.

[0004] The percentage of aluminum by weight in a structure is known to directly affect the yield of automated sorting by the eddy current sorting lines installed in the MRF. While the exact sorting rate varies among MRFs, it is known that, at the current level of technology, aluminum foil-containing flexible packaging is largely lost for recycling because its aluminum weight percentage does not guarantee efficient sorting by the equipment used in the MRF.

[0005] On the other hand, as the aluminum content increases, the repulsive force generated during separation in the eddy current line also increases. Therefore, increasing the weight percentage of aluminum can increase the separation yield of flexible packaging, in which case the flexible packaging will contain more than 30% by weight of aluminum. It is also known that the separation efficiency by eddy currents increases when the flexible packaging piece is not flat and is crushed or kneaded. Therefore, it is expected that materials with a higher tendency towards permanent deformation than elastic deformation will show better separation efficiency.

[0006] Materials successfully separated by eddy current lines on the MRF are sent to recycling without issue. Recycling of flexible packaging laminates with aluminum foil involves a pyrolysis process to separate aluminum from plastic, during which the aluminum remains in the solid phase and the plastic moves to the gas phase. It is known that the material and energy losses during pyrolysis depend on the weight ratio of aluminum to plastic. That is, prioritizing the proportion of aluminum and reducing the proportion of plastic reduces losses.

[0007] It is also known that prioritizing the proportion of aluminum and reducing the proportion of plastic increases the profitability of recycling through thermal decomposition.

[0008] The possibility of manufacturing and using aluminum foil laminates having an organic content of up to 20% by weight of the total weight of the laminate was suggested in International Publication No. 94 / 27818 in 1994. This publication highlights the promising advantage that aluminum foil laminates with an organic content of up to 20% by weight have in a typical aluminum can recycling process that does not require a thermal decomposition step prior to the melting operation. However, the inventors consider the following:

[0009] 1) With the recent advancements in pyrolysis used in the recycling process of aluminum-containing waste mixtures since 1994, limiting the organic content to 20% by weight as a step to separate organic components and collect the aluminum fraction before the aluminum enters the melting recycling process is no longer as essential as it was at the time of publication of International Publication No. 94 / 27818. Today, industrial-scale pyrolysis is common as a pretreatment step for recycling aluminum-containing waste mixtures with an aluminum content of 30% by weight.

[0010] 2) Limiting the content of organic parts, including plastic film, to 20% of the total weight of the laminate will correspondingly limit the mechanical properties of such laminates, such as puncture resistance. The properties of the plastic film and their thickness are known to play an important role in the puncture performance of the final laminate. It is also known that reducing the proportion of plastic parts in aluminum foil laminates increases the risk of cuts when consumers press on sharp corners and when attempting to tear such packaging. The inventors surmise that the above limitations in mechanical performance and safety will significantly limit the competitiveness of aluminum foil laminates with an organic content of up to 20% by weight as a promising flexible packaging solution.

[0011] Finally, flexible packaging laminates containing aluminum at the current level of technology do not fold very well due to their low aluminum content and the elastic properties of the plastic. Packaging made from such laminates tends to unfold after folding, making it difficult to completely empty and reseal the packaging.

[0012] The novel flexible packaging materials presented herein address these needs. Therefore, the laminated flexible packaging according to the present invention is characterized by a lower proportion of plastic and a higher proportion of aluminum compared to laminates having aluminum foil layers of the current state of the art.

[0013] Therefore, the lifespan of the new flexible packaging material is advantageous for the following reasons: Increased fractionation yield by eddy current lines in MRF. Reduction of losses in recycling by pyrolysis, and / or Improving the profitability of pyrolysis can facilitate the rapid progress of collection, sorting, and recycling.

[0014] Therefore, it is desirable to provide in the technical field a laminated flexible packaging that can be manufactured from aluminum-containing laminated flexible packaging material using conventional packaging machines, particularly HFFS or VFFS machines, and that has better lifespan management than prior art packaging materials, is easier to recycle and / or more efficient.

[0015] No reference to prior art documents in this specification should be construed as an acknowledgment that such prior art is well known or forms part of a general understanding common in the art.

[0016] The object of the present invention is to improve the current state of the art, and in particular to provide in the art aluminum-containing laminated flexible packaging that has better life management and / or is easier and / or more efficient to recycle, contains a relatively small amount of plastic, can be easily emptied and / or is easier to reseal, or provides at least a useful alternative.

[0017] [Overview of the prefecture] The inventors have surprisingly found that the object of the present invention can be achieved by the subject matter of the independent claim. The dependent claim further develops the idea of ​​the present invention.

[0018] In particular, the inventors have surprisingly found that (i) an aluminum foil layer wherein aluminum is present in an amount of 30% to 80% of the total weight of the laminated flexible packaging material, (ii) A plastic sealant layer comprising polyolefin (PO), polyamide (PA), and ethylene vinyl alcohol (EVOH), wherein the plastic layer is present in an amount of 20% to 70% of the total weight of the laminated flexible packaging material, (iii) We found that good results can be obtained with a laminated flexible packaging made at least partially from a laminated flexible packaging material including a coating, Here, the aluminum foil layer is laminated to a plastic sealant layer on the side facing the packaged product, while the other side of the aluminum foil layer is coated with a film but not laminated to a plastic or paper layer, and the laminated flexible packaging is manufactured from laminated flexible packaging material in a horizontal fill-and-seal (HFFS) machine.

[0019] Current plastic-aluminum laminates consist of aluminum foil sandwiched between two layers of plastic film or between a layer of plastic film and a layer of paper. During recycling, the plastic and paper in the laminate are subjected to thermal decomposition, a process in which organic materials such as plastic are heated and decomposed in the absence of oxygen. Surprisingly, the inventors have confirmed that it is possible to manufacture plastic-aluminum laminates in which the aluminum foil is not sandwiched between two layers of plastic film or between a layer of plastic film and a layer of paper, but is laminated to the plastic film on one side and coated only on the other side. This enables even better recovery of aluminum. Furthermore, the amount of plastic required is reduced, and the amount of organic material that needs to be subjected to thermal decomposition is reduced.

[0020] Accordingly, the present invention provides a laminated flexible packaging material at least partially made from a laminated flexible packaging material comprising an aluminum foil layer, a plastic sealant layer, and a coating, wherein the aluminum foil layer is laminated to the plastic sealant film layer only on the side facing the packaged product. The other side of the aluminum foil layer may be coated with a coating, but may not be laminated to the plastic layer. For the purposes of the present invention, the term "coating" may include printed material.

[0021] Waste fractions containing 30-80% by weight of aluminum and 20-70% by weight of organic components are readily accepted for recycling by being subjected to pyrolysis as a pre-dissolution step in the recycling process. It is important that the recycled aluminum obtained through this recycling route is a valuable recycled resource that is in demand in the market. The ability to stabilize the value of recycled aluminum makes the recycling of this type of waste attractive. The inventors believe that an aluminum content of 30-80% by weight in primary flexible packaging provides a commercial incentive for recycling and stimulates further development of recycling infrastructure and recycling implementation, such as the advancement of centralized and commercial collection of this type of waste. The inventors hypothesize that, due to the economic incentives provided by the recycling of aluminum by pyrolysis, primary flexible packaging containing 30-80% by weight of aluminum is less likely to leak into the environment or be lost in other ways during recycling, at least in certain regions, compared to primary flexible packaging that does not contain aluminum or contains less than 30% by weight of aluminum.

[0022] Laminated flexible packaging may be manufactured from laminated flexible packaging material using a horizontal fill-and-seal (HFFS) machine or a vertical fill-and-seal (VFFS) machine.

[0023] The laminated flexible packaging of the present invention may be pre-fabricated pouches. The difference from other types of packaging produced by HFFS or VFFS technology is that the formation and filling of pre-fabricated pouches are not necessarily performed in a single process; rather, in the case of pre-fabricated pouches, they are formed in one machine and then transported to another machine for filling.

[0024] As used herein, the words “comprises,” “comprising,” and similar words should not be interpreted as exclusive or exhaustive. In other words, they are intended to mean “includes, but not limited to.”

[0025] The inventors have shown that a laminated flexible package made from a laminated flexible packaging material comprising an aluminum foil layer, a plastic sealant layer, and a coating can be provided by conventional packaging machines including vertical form-fill-seal (VFFS) machines and horizontal form-fill-seal (HFFS) machines, and by filling machines that use pre-made pouches, and that the aluminum foil layer is laminated to the plastic sealant film layer only on the side facing the packaged product. Surprisingly, using a coating on the outside of the aluminum foil is sufficient to modify the properties of the packaging material of the present invention such that it can be used to form flexible packages on a VFFS or HFFS line without causing holes and breaks in the aluminum foil, which can result from stretching of the film when pulled through a packaging line, or from impact on the seam area when a heated seal jaw hits and compresses the packaging material to make a seal, or from abrasion and breakage that the laminate may experience while being pulled over static metal elements of the packaging line. The level of protection required on the printed or unprinted aluminum foil surface to enable use of the packaging material of the present invention on a VFFS or HFFS line is thought to be facilitated by the ability of the coating to ensure a stable and sufficiently low coefficient of friction against metal on the outer surface of the laminate. Also, the level of protection required on the surface of the printed or unprinted aluminum foil to enable use of the packaging material of the present invention on a VFFS or HFFS line is now thought to be facilitated by the ability of the coating material to dissipate energy and to redistribute forces due to certain types of mechanical abuse characterized by the concentration of excessive force (abuse force) in small areas, such as what is referred to as "scrubbing" and "puncturing", over a larger area of the surface of the aluminum foil. Furthermore, the protective function of the coating is thought to be enhanced here by the ability of the coating to stably maintain a coefficient of dynamic friction outside the packaging material of the present invention below 0.55, preferably below 0.45, more preferably below 0.35. The protective function of the coating is assumed to be enhanced by a coating thickness exceeding 0.25 micrometers, preferably exceeding 1.5 micrometers, more preferably exceeding 2.5 micrometers.

[0026] The resulting laminated flexible packaging has a higher aluminum content and a lower plastic content than the state-of-the-art materials, and in particular, the recyclability of aluminum can be improved more effectively. In addition, the resulting laminated flexible packaging can be easily reclosed. In the bursting test, the packaging has excellent bursting resistance and reaches a bursting resistance of 1.2 bar or more with an aluminum foil having a thickness of 20 μm. 1 bar is a SI-derived unit corresponding to 100,000 N / m2.

[0027] In the practical test using food, it was found that it is possible to use the packaging according to the present invention for packaging gravy and perform a thermal sterilization treatment typical of wet pet food without any problems.

Brief Description of the Drawings

[0028] Additional features and advantages of the present invention are described in the following description of the presently preferred embodiments, which are made clear from the description with reference to the drawings. [Figure 1] It is a diagram showing a schematic configuration of a state-of-the-art structure example (left) and a new structure (right). [Figure 2] It shows a flexible pouch of Alu, 12 μm / MDO CPP, 60 μm, which is formed on an HFFS line and has no product inside. [Figure 3] It shows a flexible pouch of Alu, 20 μm / MDO CPP, 75 μm after retort treatment, which is formed on an HFFS and filled with gravy of pet food. [Figure 4] It shows the back side of the pouch according to FIG. 3. [Figure 5] It shows the appearance of the sample after forming the fold. [Figure 6] It shows the positioning of the sample for measuring the angle recovery. [Figure 7] It shows a depiction of two consecutive folds with a width of 10 mm. [Figure 8] It shows a comparative weight gain curve of moisture adsorption of a reclosed pouch in a proUmid SPSx-1μ vapor adsorption measuring device at 23°C and a relative humidity of 50%. [Figure 9] This shows a typical puncture curve. [Figure 10] This shows a comparison of COF curves. [Figure 11] This shows the surface appearance of the OPV-coated packaging material PMSP0_12-75 after COF testing. [Figure 12] This shows the surface appearance of Alu 12 / SB ADH / mdo PP 75, a packaging material with no coating on the surface of aluminum foil, after COF testing. [Figure 13] A pouch formed from the material according to the present invention is shown. This pouch contains printing damage in the heat-sealed side barrier blade area, which was observed only in samples from the first few cycles after machine startup, but no visible damage was observed in the aluminum layer thereafter. [Modes for carrying out the invention]

[0029] Accordingly, the present invention relates in part to laminated flexible packaging made at least in part from a laminated flexible packaging material comprising an aluminum foil layer, a plastic sealant layer, and a coating, wherein the aluminum foil layer is laminated to the plastic sealant layer on the side facing the packaged product, and the other side of the aluminum foil layer is coated with a coating but not laminated to the plastic layer, and the laminated flexible packaging is manufactured from the laminated flexible packaging material using conventional packaging machines, including vertical form-fill-seal (VFFS) machines and horizontal form-fill-seal (HFFS) machines, as well as filling machines that use pre-made pouches.

[0030] HFFS machines are well known in the art. The two most widely used form-fill-seal (HFFS) machines and vertical form-fill-seal (VFFS) machines are the HFFS machines. A key difference between these two types of form-fill-seal machines is the method by which they feed the product into the packaging. HFFS machines are known for their versatility. They are widely used to form both rigid and flexible packaging. Typical examples of rigid packaging formed on an HFFS line include capsules, blisters, trays, and cups with lids.

[0031] For the purposes of the present invention, packaging and / or packaging materials should be considered flexible if they can be easily bent without damage. For example, the flexible packaging and / or flexible packaging materials according to the present invention may be bendable by hand.

[0032] The flexible packaging and / or flexible packaging materials according to the present invention can be manufactured from many materials, including paper, film, or combinations thereof, in addition to aluminum and plastic. Typical flexible packaging according to the present invention can be selected from the group consisting of sachets, pouches, stand-up pouches, gusseted pouches, doi packs, pillow bags, flow wraps, bags, labels, liners, sachets, wraps, and roll stocks.

[0033] Using aluminum in laminated packaging has the advantage of being generally easily recyclable and providing the packaging with high-performance barrier properties against oxygen, flavor, and light.

[0034] Any aluminum foil can be used as the aluminum foil for the purposes of the present invention. Typically, the thickness of the aluminum foil is less than 0.2 mm. The thickness of ordinary household aluminum foil is 0.024 mm. The inventors have found that particularly beneficial results are obtained for the laminated flexible packaging according to the present invention when the thickness of the aluminum foil layer of the laminated flexible packaging material is in the range of about 8 to 30 μm, preferably in the range of about 10 to 22 μm. This allows for optimal stability of the safety guaranteed by the packaging, while simultaneously providing an excellent barrier against moisture, light, and odor.

[0035] The flexible packaging and / or flexible packaging material according to the present invention may have an aluminum content of at least 30% by weight of aluminum, at least 40% by weight of aluminum, or at least 50% by weight of aluminum. As described above, a high aluminum content ensures good aluminum recovery during automatic sorting by the eddy current sorting line provided in the MRF.

[0036] The surface of the aluminum foil layer can be treated by applying a primer, silicating, or titaniumizing. Applying a primer, silicating, or titaniumizing the surface of the aluminum foil layer can further improve the bonding strength between the aluminum foil layer and the plastic sealant layer. Furthermore, the corrosion resistance of the packaging of the present invention can also be improved by applying a primer, silicating, or titaniumizing the aluminum foil layer.

[0037] Any plastic sealant layer may be used as the plastic sealant layer. A person skilled in the art can select a suitable plastic sealant layer. It may be advantageous if the plastic sealant layer is formulated using a plastic that contains as few heteroatoms as possible in its main chain. For example, the plastic sealant layer may be formulated using a plastic that contains less than 10% heteroatoms in its main chain, less than 5% heteroatoms in its main chain, less than 2% heteroatoms in its main chain, or less than 0.1% heteroatoms in its main chain. This has the advantage of improving recyclability.

[0038] For example, the plastic sealant layer may be formulated with aliphatic polyolefin (PO), and further may be formulated with aliphatic PO selected from the group consisting of, for example, polypropylene homopolymer; polypropylene copolymers including but not limited to block copolymers or random copolymers of propylene, ethylene, and other alpha-olefins; polyethylene homopolymer; polyethylene copolymers including but not limited to copolymers of ethylene, alpha-olefin (LLDPE), cyclic olefin (COC), vinyl acetate (EVA), acrylic acid (EAA), methacrylic acid (EMA), acrylic acid ester, methacrylic acid ester, acrylate, or methacrylic acid (ionomer); maleic anhydride grafted variations of the above plastics; or combinations of the above-listed plastics. The plastic sealant layer can be produced, for example, by compounding, extrusion blending, co-extrusion, extrusion lamination, extrusion coating, lamination with adhesive, or a combination thereof.

[0039] In the present invention, although the plastic sealant layer is referred to herein as a single layer, it may comprise multiple separate plastic film laminates joined together by an adhesive, for example, in an extrusion lamination. The multiple plastic films joined by lamination to form the plastic sealant layer do not need to be made of the same type of material and may be a combination of different types of materials, including both sealable and non-sealable materials. For example, the plastic sealant layer may be constructed by laminating a polyamide film with a polyolefin film.

[0040] To meet the requirements of the specific application for which the laminate is designed, any of the plastic sealant layer films may have a functional coating or may include a co-extruded layer of a functional material such as ethylene vinyl alcohol (EVOH) or polyamide (PA).

[0041] In a preferred embodiment of the present invention, the plastic sealant layer laminated to the aluminum layer includes one stretched polypropylene (OPP) layer laminated to a cast polypropylene (cPP) layer. The bonding of these three layers—aluminum, OPP, and cPP—has been found to achieve remarkably good results. The OPP and cPP layers are preferably laminated by adhesive lamination or by extrusion lamination. Such a structure has been found to yield a combination of valuable properties, including puncture resistance, ultrasonic sealing without damaging the aluminum layer, and a reduced incidence of aluminum cracks under mechanical stress.

[0042] Those skilled in the art can select an appropriate thickness for the plastic sealant layer. The plastic sealant layer should be able to effectively seal the packaging, and sealing is often performed under heat and pressure. For example, the plastic sealant layer of laminated flexible packaging material may have a thickness in the range of about 30 to 100 μm, preferably in the range of about 45 to 80 μm. If the plastic sealant layer is too thick, it becomes plastic waste, while if the sealant layer is too thin, it may lead to problems in the sealing process, reduced mechanical properties including puncture resistance, or the risk of consumers cutting their hands when tearing the packaging.

[0043] By applying a plastic sealant layer to the side of the aluminum foil layer facing the product being packaged, the two sealant layers in contact with each other can be fused together to form a seal through heating and pressurizing for a specific period of time.

[0044] Furthermore, the presence of a plastic sealant layer on the side of the aluminum foil layer facing the packaged product protects the packaged product and the aluminum foil from redox reactions that could otherwise be caused by contact between the aluminum and the product.

[0045] In some applications, it can be advantageous for the plastic sealant layer to include a stretched PO film. This has the advantage of improving the mechanical properties of the laminate. Polymer deformation processes, such as viscous deformation caused by molecular sliding, are minimized. Molecular orientation caused by unwinding is maximized. Furthermore, the packaging can be torn straight when unwrapped.

[0046] Therefore, in the laminated flexible packaging according to the present invention, the plastic sealant layer may include a stretched polyolefin (PO) film. The stretched PO film can be selected from the group consisting of, for example, longitudinally stretched (MDO) film, tenterframe biaxially stretched (BO) film, double-bubble blown film, triple-bubble blown film, or a combination thereof.

[0047] In some applications, it may be preferable to have an adhesive layer between the aluminum foil layer and the plastic sealant layer. The adhesive layer ensures optimal adhesion between the aluminum foil layer and the plastic sealant layer while avoiding adhesive gaps. Such adhesive gaps can lead to corrosion or other deterioration of the resulting packaging, which can be exacerbated, for example, in the case of retort pouches during aseptic processing. Therefore, the present invention also relates to a laminated flexible packaging according to the present invention, wherein there is an adhesive layer between the aluminum foil layer and the plastic sealant layer of the laminated flexible packaging material. The adhesive layer may be, for example, a solvent-based laminated adhesive layer. Furthermore, the adhesive layer, for example, a solvent-based laminated adhesive layer, may have a thickness in the range of 1.5 to 10 μm, preferably in the range of about 2 to 5 μm.

[0048] The laminated flexible packaging according to the present invention may be further coated with one or more coatings that provide the laminated flexible packaging according to the present invention with further functionality, optical properties, tactile properties, or other further properties.

[0049] For example, the laminated flexible packaging according to the present invention may be further coated with one or more coatings on the outside of the packaging. For example, in the laminated flexible packaging of the present invention, the aluminum layer of the laminated flexible packaging material may be coated with a coating on the side opposite to the packaged product. Thus, the subject of the present invention extends to the laminated flexible packaging according to the present invention in which the aluminum layer of the laminated flexible packaging material is coated on the side not facing the packaged product with a coating comprising overprint varnish (OPV), at least one layer of printing ink, a primer, or a combination thereof. For example, this coating may be a single overprint varnish (OPV), or an ink layer, or another type of coating that functions functionally as an OPV, or a combination of printing ink and an OPV on top of the ink. Any of the above coatings can be used without a primer, or in combination with a primer and on top of a primer. The coating can be applied by various techniques known to those skilled in the art, including application by printing using an engraved cylinder.

[0050] While we do not wish to be bound by theory, the inventors currently believe that the protective function of the coating is enhanced by its ability to stably reduce the coefficient of dynamic friction on the outside of the packaging material of the present invention to less than 0.55, preferably less than 0.45, and more preferably less than 0.35. The protective function of the coating is assumed to be enhanced by the thickness of the coating. Therefore, the thickness of the coating may be greater than about 0.25 μm, preferably greater than about 1.5 μm, and more preferably greater than about 2.5 μm.

[0051] If the coating includes printed material, such printing may be flexographic or web gravure printing. In many cases, the ink is applied over a primer and covered with an OPV (Optical Printing Vinyl).

[0052] Flexographic printing uses a flexible relief board for printing. This printing process is suitable, for example, for printing on aluminum foil. It is often used in the food industry. Flexographic printing on non-porous substrates is preferred.

[0053] Rotary gravure printing can be considered a form of intaglio printing. The material to be printed is an image carrier, usually a cylinder, which is engraved and then used in a rotary printing press.

[0054] Additionally or alternatively, the laminated flexible packaging according to the present invention may also be printed using other printing techniques, such as digital printing, inkjet printing, or laser printing.

[0055] Preferably, digital printing, inkjet printing, or laser printing processes can be carried out in parallel with the packaging process. Parallel printing offers the advantage of being able to affix symbols that provide actual information determined at the time of packaging, such as the "best before" date, as well as individual decorations for separate packaging, to a single packaging material.

[0056] The laminated flexible packaging of the present invention may be further embossed. Embossing is a packaging finishing technique that can be used to create visual and tactile effects that can be used to aid brand messaging. Furthermore, embossing can encode information for visually impaired consumers or information for other additional functions.

[0057] The inventors have also found that the laminated flexible packaging according to the present invention has fold retention properties that improve the resealability function. While not wishing to be bound by theory, the inventors currently believe that this effect is due to the relatively high aluminum / plastic weight ratio of the packaging according to the present invention. A high plastic content causes the folded packaging to unfold on its own, while a low plastic content causes the folded packaging of the present invention to remain folded. This makes it possible to reseal the packaging of the present invention, improving safety and helping to avoid the generation of food waste. Therefore, additional elements to enable resealing can be used in the packaging of the present invention, but are not necessarily required. Such additional elements are well known to those skilled in the art and include, for example, sealing spouts, sealing valves, sealing ziplocks, sealing easy locks, clips, staples, stickers, and pressure-sensitive adhesive (PSA) coatings.

[0058] The laminated flexible packaging material used in the framework of the present invention can be manufactured by methods well known to those skilled in the art. For example, the laminated flexible packaging material can be manufactured by laminating aluminum foil onto a plastic sealant film and simultaneously applying a coating such as primer ink and / or OPV.

[0059] The fact that the laminated flexible packaging according to the present invention can have only one plastic layer instead of two plastic layers allows for a relatively high aluminum content and / or a relatively low plastic content in the packaging according to the present invention. For example, the laminated flexible packaging according to the present invention may contain at least 30% by weight of aluminum, at least 40% by weight of aluminum, or at least 50% by weight of aluminum. Furthermore, for example, the laminated flexible packaging according to the present invention may contain less than about 70% by weight of plastic, less than about 60% by weight of plastic, or less than about 50% by weight of plastic. As a result, the laminated flexible packaging according to the present invention may have an aluminum / plastic weight ratio greater than 0.4, greater than 0.6, or greater than 0.8.

[0060] The present inventors have found that the laminated flexible packaging according to the present invention has functional properties that make it suitable for packaging products such as food. With regard to the object of the present invention, the term "food" means any substance intended for human consumption, whether processed, semi-processed or unprocessed, in accordance with the International Food Standard (Codex Alimentarius), and includes beverages, chewing gum, and any substance used in the manufacture, preparation, or processing of "food," but does not include substances used solely as cosmetics, tobacco, or drugs.

[0061] The inventors have further discovered that the laminated flexible packaging according to the present invention has functional properties that make it suitable for packaging pet food products.

[0062] For example, in the laminated flexible packaging according to the present invention, the laminated flexible packaging may have puncture resistance of at least a puncture force of 7 N, a puncture elongation of 2.1 mm, and a puncture work of 8 mJ (Figures 6 and 7). Puncture resistance was measured from the outside to the inside at a speed of 100 mm / min, and other parameters of the test were in accordance with DIN 14477, which is incorporated herein by reference in whole. Surprisingly, the inventors found that by using a sealable plastic layer containing a 20 μm thick BOPP (biaxially oriented polypropylene) film adhesive laminated onto a 33 μm thick cPP (cast polypropylene) film, puncture resistance was further increased to a puncture force of 14 N and a puncture work of 10 mJ.

[0063] Furthermore, the laminated flexible packaging according to the present invention may have resistance to thermal sterilization during retort processing at a temperature of at least 121°C, at least 128°C, or at least 134°C.

[0064] The barrier properties of the resulting laminate, such as oxygen permeability (OTR), water vapor permeability (WVTR), and light barrier properties, are primarily determined by the inherent barrier properties of the aluminum foil used in the laminated flexible packaging material according to the present invention. Additionally or alternatively, the laminated flexible packaging according to the present invention can withstand burst pressure of at least 1.0 bar, 1.2 bar, or 1.3 bar in a burst test. The burst test can be performed using a Thimonnier burst tester with an air injection rate of 6 L / min.

[0065] Those skilled in the art will understand that all features of the present invention disclosed herein can be freely combined. In particular, features described for the products of the present invention may be combined with uses of the present invention, and vice versa. Furthermore, features described for different embodiments of the present invention may be combined.

[0066] Although the present invention has been described by examples, it should be understood that modifications and alterations can be made without departing from the scope of the present invention as defined in the claims.

[0067] Furthermore, where known equivalents exist for a particular feature, such equivalents are incorporated as specifically referred to herein. Further advantages and features of the present invention are evident from the figures and non-limiting embodiments. [Examples]

[0068] material: 1. Raw materials for the manufacture of packaged samples: • 12μm thick aluminum foil (Alu) (Alu12), reel, commercially available packaging grade 8021 alloy with elongation A50mm exceeding 5% (compliant with EN10002 and EN546), • 20μm thick aluminum foil (Alu20), reel, commercially available packaging grade 8021 alloy with elongation A50mm exceeding 5% (compliant with EN10002 and EN546), • 60μm thick longitudinally oriented cast polypropylene film (mdo PP) (mdo PP 60), reel, commercial packaging grade, heat (retort) sterilization resistant. • 75μm thick longitudinally oriented cast polypropylene film (mdo PP 75), reel, commercial packaging grade, heat (retort) sterilization resistant. • Biaxially oriented polypropylene (OPP) film, 20 μm thick, plasma or corona treated on both sides. Example grade: Jindai Bicor (trademark) NNH 20.0 • Cast polypropylene film (CPP), retort-processable grade, 33 μm thickness • A two-component solvent-based lamination adhesive (SB ADH) suitable for moist pet food packaging, which is heat-sterilized after packaging. • A two-component solvent-based overprint varnish (OPV) that provides a static COF of less than 0.43 against metals on coated Alu. • Printable solutions of the developed products: Printing primers and inks 2. Samples of packaging materials: Samples of packaging materials are listed in Table 1 below.

[0069] [Table 1]

[0070] method: 1. Preparation of packaging material samples: The four packaging material samples described in the "Materials" section above were prepared using a two-step process. The first step involved using a Nordmeccanica Labo-Combi 400 combi laminator with standard rotary gravure coating technology at a speed of 30 m / min and a density of 3.5 g / m². 2 A laminate of Alu and mdo PP was fabricated using SB ADH coated with the dry film weight of 3.3 g / m². The second step involved using a Nordmeccanica Labo-Combi 400 combi laminator with standard rotary gravure coating technology at a speed of 30 m / min and 3.3 g / m². 2A protective OPV was applied to the aluminum surface with a dry film weight of . Between the two steps and after the completion of the second step, the laminate was cured according to the instructions described in the SB ADH technical description. After curing, the laminate was cut into strips 280 mm wide and prepared for use in the HFFS line to produce four-sided sealed pouches 140 mm high and 93 mm wide.

[0071] 2. Preparation of filled pouches on the HFFS line: Pouches were formed from materials PMSP0_12-60, PMSP0_12-75, PMSP0_20-60, PMSP0_20-75, and reference PET12 / Alu7 / CPP60. 30g of imitation pet food (gravy sauce) was filled into the pouches, and they were sealed using a Volpak SP 170 HFFS packaging line. The filled pouches were heat-sterilized at 128°C according to standard procedures.

[0072] HFFS line setup: The packaging line was operated at a fixed speed of 50 cycles per minute. Only heat sealing was used, without ultrasonic assistance. The thermal settings of the vertical seal jaws, top seal jaws, and bottom seal jaws were determined in an experiment consisting of forming and sealing an unfilled pouch, followed by confirmation of airtightness by a burst test. The burst test was performed using a Thimonnier burst tester with an air injection rate of 6 L / min.

[0073] 3. Preparation of filling pouches in two steps: Pouches made of material PMSP3_20-20-33 were formed on a Volpak SP170 HFFS packaging line by creating bottom seals and vertical seals. After formation, 75g of moist pet food was filled into the pouches and sealed on a Toyo Automatic Machinery TT8DR filling line. The sealing after filling on the Toyo Automatic Machinery TT8DR line was performed by ultrasonic sealing followed by heat sealing of the top of the pouch. The filled pouches were heat sterilized at 128°C according to a standard procedure.

[0074] 4. Pouch fabrication on the VFFS line: Pouches made from materials PMSP0_12-60 and PMSP0_12-75 were formed on a Wolf VPC 180 VFFS line. Seal integrity was controlled using an Infocin Contura S400 leak tester. Seal integrity was evaluated by testing 10 pouches, and acceptance was granted if all tested pouches demonstrated a leak rate of less than 0.01 mbar / L / s / sec.

[0075] VFFS settings for integrated sealing: For sample PMSP0_12-60: cycle time 0.6 seconds, longitudinal seal temperature: 210°C, transverse seal temperature: 200°C; for sample PMSP0_12-75: cycle time 0.5 seconds, longitudinal seal temperature: 220°C, transverse seal temperature: 250°C.

[0076] 5. Reopening after folding: An internal method has been developed to analyze the ability of a material to unfold after being folded. The sample was cut into rectangles with a width of 15 mm and a minimum length of 70 mm, and stored at room temperature (20-25°C). A transverse fold 25 mm from the edge of the laminated elongated piece was measured at a weight of 2.611 kg and a base of 3.75 cm. 2 The sample was secured by placing a metal cylinder on top of it. Figure 5 shows the appearance of the sample after the fold was formed. The weight was removed after 30 seconds: the angle recovery was calculated using the relationship millimeter paper and morphological angle = Asin(distance between the table and the top of the edge after angle recovery / distance between the fold and the edge, i.e., 25 mm). Figure 6 shows the positioning of the sample for measuring the angle recovery. Distance and angle measurements were performed at least three times for 30 seconds after the removal of the mass.

[0077] 6. Reclosing efficiency: An internal method has been developed to analyze the resealing efficiency of pouches made from different types of materials.

[0078] Pouches measuring 93 mm in width and 140 mm in height were characterized after being stored at room temperature (20-25°C) for at least 24 hours. All pouches were manufactured on the HFFS line as described in "Methods" (2. Pouch production on the HFFS line), but without filling. The pouches were opened and filled with 2 g of desiccant. A metal cylinder was placed 10 mm from the edge of the opened pouch and rolled over the pouch to create a fold. The metal cylinder weighed 2.611 kg, had a diameter of 75 mm, and a height of 75.5 mm. A second fold above the first fold was created by rotating the same metal cylinder again in the same manner. Figure 7 shows the positions of the two consecutive folds, each 10 mm wide. The method for creating the second fold above the first fold is shown in the photograph in Figure 7. The filled pouches were analyzed for over 60 hours at 23°C and 50% relative humidity using a proUmid SPSx-1μ vapor adsorption analyzer, in accordance with the EN ISO 7783-1 standard.

[0079] 7. Puncture resistance: Puncture resistance was measured from the outside to the inside (i.e., from the aluminum layer to the CPP layer) at a probe speed of 100 mm per minute, according to ISO standard EN 14477.

[0080] The laminates were characterized at least 24 hours after being stored in a conditioning chamber (23°C, 50% RH). Ten measurements were taken for each sample, and the average value is shown as the result.

[0081] 8. Surface friction properties: The coefficient of friction (COF) was measured according to the ASTM D1894 method. After the friction test, the outer surface was visually inspected to detect any surface defects.

[0082] 9. Ultrasonic sealing: The quality of ultrasonic sealing was evaluated by visual inspection of the seam area and measurement of seam strength using a Zwick tensile testing machine.

[0083] Results and Discussion 1. Results of airtightness and burst test of the seal Airtightness was concluded if, in a series of 10 burst measurements, there were no outliers, no pouches showing leakage during measurement, or no pouches showing gradual opening rather than burst (instantaneous) opening.

[0084] Airtight sealing was achieved for all samples. The mean and standard deviation of the 10 rupture measurements are summarized in Table 2 below.

[0085] [Table 2]

[0086] 2. Heat (retort) sterilization: Packaging material samples: Using PMSP0_12-75 and PMSP0_20-75, 100 pouches filled with 30g of gravy were subjected to heat (retort) sterilization without steam injection in an industrial sterilizer set to gradually heat to 128°C over 15 minutes, followed by heating at a stable temperature of 128°C for 16 minutes, and then gradually cooling to 50°C over 15 minutes. After cooling and on the 5th day after retort processing, the pouches were examined for leakage. No leakage was found. It was concluded that the pouches successfully withstand heat (retort) sterilization.

[0087] 3. Reopening after folding: The measured angle recovery is summarized in Table 3 below.

[0088] [Table 3]

[0089] Tests have shown that a lower re-opening angle can be achieved by replacing the current state-of-the-art structure of the reference with the material of the present invention, such as PMSP0_12-75, preferably PMSP0_20-60. This property is presumed to be valuable in the following respects: By folding the top of the pouch for a longer period of time, the freshness of food residue inside the pouch is preserved after it has been opened, partially emptied, and resealed. When eddy current-based automatic sorting is used for packaging lifecycles, deformed pouches tend to be sorted more easily than flat pouches because their aerodynamic properties change.

[0090] 4. Reclosing efficiency: The re-closing efficiency results are shown in Table 4 below in g / pouch / day, and the respective weight increase curves are shown in Figure 8.

[0091] [Table 4]

[0092] The new structure is clearly much less moisture-absorbent than the reference structure, and by folding the top of the pouch for a longer period of time, it may help maintain the freshness of food residue inside the pouch after it has been opened, partially emptied, and resealed.

[0093] 5. Puncture resistance: The results of puncture resistance are shown in Table 5, and a comparison of typical puncture curves is shown in Figure 9.

[0094] [Table 5]

[0095] Experiments have shown that the material of the present invention can demonstrate a reduction in "peak force," an improvement in "extension to peak force," and an improvement in "energy to peak force" in puncture tests. Further research is needed to investigate how this change in puncture behavior affects the robustness of the packaging throughout its lifecycle.

[0096] 6. Surface friction properties: The COF measurement results are shown in Table 6, a comparison of typical COF curves is shown in Figure 10, the surface appearance of the OPV-coated packaging material after the COF test is shown in Figure 11, and the surface appearance of the uncoated packaging material on the aluminum foil surface after the COF test is shown in Figure 12.

[0097] [Table 6]

[0098] The OPV-coated packaging material PMSP0_12-75 exhibits a lower COF value, a relatively smoother COF curve shape, and no scratches on the surface of the coated material after COF testing, demonstrating that the coating protects the aluminum foil surface from abrasion. The inventors hypothesize that this demonstrated protection of the aluminum foil surface from abrasion contributes to the ability of the packaging material of the present invention to form flexible packaging on the HFFS line.

[0099] 7. Ultrasonic sealing: Based on the results summarized in Table 7 below, the quality of ultrasonic sealing for samples manufactured from material PMSP3_20-20-33 using the Toyo Automatic Machinery TT8DR line was concluded to be good.

[0100] [Table 7]

[0101] With materials PMSP0_12-60, PMSP0_12-75, PMSP0_20-60, and PMSP0_20-75, it was impossible to avoid visual damage to the aluminum layer and provide consistent sealing quality.

Claims

1. A laminated flexible packaging made at least partially from a laminated flexible packaging material, The aforementioned laminated flexible packaging material, (i) an aluminum foil layer, wherein the aluminum foil layer is present in an amount of 30% to 80% of the total weight of the laminated flexible packaging material, (ii) A plastic sealant layer comprising polyolefin (PO), polyamide (PA), or ethylene vinyl alcohol (EVOH), wherein the plastic sealant layer is present in an amount of 20% to 70% of the total weight of the laminated flexible packaging material, (iii) coating and, The coating comprises overprint varnish (OPV) The thickness of the aluminum foil layer is 10 to 22 μm. The thickness of the aforementioned plastic sealant layer is 60 to 80 μm. A laminated flexible packaging comprising an aluminum foil layer laminated onto the plastic sealant layer on the side facing the packaged product, and the other side of the aluminum foil layer coated with the film but not laminated onto the plastic layer.

2. The laminated flexible packaging according to claim 1, wherein at least one side of the surface of the aluminum foil layer is treated to increase bonding strength by applying a primer, silicating, or titaniumizing.

3. The laminated flexible packaging according to claim 1 or 2, wherein the plastic sealant layer is selected from the group consisting of a single-layer cast film, a co-extruded multilayer cast film, and a co-extruded multilayer blown film.

4. The laminated flexible packaging according to any one of claims 1 to 3, wherein the plastic sealant layer includes a stretched PO film selected from the group consisting of longitudinally stretched (MDO) PO film, tenterframe biaxially stretched (BO) PO film, double-bubble blown film, triple-bubble blown film, and combinations thereof.

5. The laminated flexible packaging according to any one of claims 1 to 4, wherein the plastic sealant layer comprises a laminate of an stretched polypropylene (OPP) layer and a cast polypropylene (cPP) layer.

6. The laminated flexible packaging according to any one of claims 1 to 5, wherein the laminated flexible packaging material has an adhesive layer between the aluminum foil layer and the plastic sealant layer having a thickness in the range of 1.5 to 10 μm.

7. The laminated flexible packaging according to any one of claims 1 to 6, wherein the aluminum foil layer of the laminated flexible packaging material is coated on the side not facing the packaged product with a coating comprising overprint varnish (OPV) and at least one layer of printing ink, primer, or a combination thereof.

8. The laminated flexible packaging according to any one of claims 1 to 7, wherein the laminated flexible packaging contains at least 30% by weight of aluminum.

9. The laminated flexible packaging according to any one of claims 1 to 8, wherein the laminated flexible packaging contains less than 70% by weight of plastic.

10. The laminated flexible packaging according to any one of claims 1 to 9, wherein the laminated flexible packaging has puncture resistance of at least a puncture force of 7 N, a puncture elongation of 2.1 mm, and a puncture work of 8 mJ.

11. The laminated flexible packaging according to any one of claims 1 to 10, wherein the laminated flexible packaging has resistance to heat sterilization during retort processing at least 121°C.

12. The laminated flexible packaging according to any one of claims 1 to 11, wherein the laminated flexible packaging withstands at least 1.0 bar in a burst test.

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