Recyclable paper-based laminate and beverage carton made therefrom

Abstract

This invention relates to a paper-based barrier multilayer packaging material structure (1), which is formed as a monolithic sheet and comprises the following layers from its outer surface to its inner surface: - a polymer dispersion coating (9) having a thickness of 1 μm to 10 μm; - a paperboard (8) having a thickness of 120 g / m². 2 Up to 500g / m 2 - Grammage; - Water-based or solvent-free adhesive (7) having a thickness of 1 μm to 10 μm; - Metallized barrier paper layer (MBPL) having a thickness of 30 g / m 2 Up to 120g / m 2 Between these values, 45g / m² is preferred. 2 Up to 90g / m 2 The mass weight was between [value missing], and the water vapor transmission rate (WVTR) measured at 38°C and 90% RH was 10 g / m³. 2 / d to 0.1g / m 2 / d, preferably WVTR is 1.0 g / m 2 / d to 0.1g / m 2 / d, and the oxygen transmission rate (OTR) measured at 23°C and 50% RH includes 100 cc / m 2 / d and 0.1cc / m 2 Between d, preferably OTR includes 1.0cc / m 2 / d and 0.1cc / m 2 Between / d. - Waterproof polyolefin sealable coating (2) having a thickness of 10μm to 50μm, preferably 25μm to 35μm.

Description

Technical Field

[0001] This invention relates to a paper-based packaging material and beverage cartons made therefrom, the paper-based packaging material having high barrier properties and being recyclable in a recycled paper stream. Background Technology

[0002] Currently, packaging for aseptically filled edible liquids (such as milk, juice, tea or plant-based beverages, soft drinks, tomato puree, sauces, or semi-liquid foods with plant extracts) is typically made of a multilayer material having a paper or cardboard base, with at least one polymer and at least one metal layer (minimum thickness of 6 micrometers) assembled onto the paper or cardboard base by extrusion or adhesive lamination. Such multilayer packaging materials are widely known and are manufactured as flat blanks or continuous webs, which are then folded to form a three-dimensional article, sealed using inductive, ultrasonic, or heat transfer sealing to form a closed package.

[0003] Optionally, the thermoplastic nozzle and closure assembly can be sealed and assembled into the package to allow consumers to easily dispense the contents.

[0004] This type of packaging is well-known, and is, for example, under the trademark "Tetra". Aseptic, Tetra Aseptic, Combibloc TM "or Combifit" TM "Sales. These packages are very user-friendly and extremely practical because they can be easily folded into various formats and shapes (with cross-sections such as square, round, and elliptical) as described above, making them easy to stack in compact units for transport and storage. When stacked, for example, in a pallet, their shape results in very little wasted space between two adjacent packages, making them an environmentally friendly solution from a transport perspective."

[0005] Because many components in edible liquids are sensitive to oxidation, visible light, ultraviolet light, and / or moisture loss, packaging composite materials commonly known in the art include at least one outer polymer layer – such as low-density polyethylene (“LDPE”) – a polymer layer – such as LDPE – which serves as a bonding layer between the cardboard and the aluminum foil layer that acts as a barrier, and one or more innermost polyethylene (“PE”) layers that serve as a sealable medium and block water contained in the packaged product.

[0006] Alternatively, as an alternative to the aforementioned oxygen-barrier aluminum foil layer, the known prior art packaging multilayer structure may also include a high-barrier polymer film made by various metallization techniques, particularly reactive and non-reactive physical vapor deposition (PVD), to obtain, for example, metallized polyethylene terephthalate (“PET-AlOx”), silica-coated PET (“PET-SiOx”), metallized polyethylene (“MetPE”), or oriented metallized polypropylene (“OPP-AlOx”). Furthermore, the PE layer between the cardboard and the barrier layer can be replaced by an adhesive layer such as a polyurethane (“PU”) layer.

[0007] This type of laminated material used in the manufacture of beverage carton packaging is suitable for aseptic (or non-aseptic) filling processes. Aseptic filling is a well-known technique that involves heating the liquid to be packaged to a temperature above a certain level, or exposing the liquid to antimicrobial light (typically ultraviolet light), or contacting the packaging material with a chemical treatment (e.g., ozone, hydrogen peroxide, or chlorine treatment) for a predetermined amount of time, and then filling the previously treated packages with hydrogen peroxide or other sterilization treatments with the treated liquid in a controlled environment where most common bacteria are substantially removed. This aseptic filling process ensures that the shelf life of the product will be extended, especially if the packaged product will be stored at ambient temperature conditions.

[0008] Due to aseptic filling conditions, the packaging laminate material must be resistant to temperature, light, and the chemicals used for sterilization as described above, as well as the temperatures applied to the components or products to be packaged within the material. Such temperatures can reach 95°C within a short time period (typically between 1 and 20 seconds, preferably between 3 and 10 seconds).

[0009] If these known packages are to be recycled, they need to be separated from other packaging waste and processed separately using specific recycling technologies. These known packages are collected in a mixed collection facility and then manually or automatically separated from other types of packaging using technologies such as near-infrared (NIR) sorting. They are then recycled in a specific recycling stream, where each of their specific constituent materials is sorted with other materials and transferred to a specific recycler. This recycling process is complex, and therefore the associated recycling costs paid by producers and / or end-users, the so-called "Extended Producer Responsibility" (EPR) costs, are high.

[0010] The recycling process for the aforementioned known multi-layer barrier packaging structures is very complex and cannot be carried out in the simpler recycling process, particularly for standard paper packaging. This is due to the fact that the total content of cellulose fibers in the entire structure is no more than about 75%, with the remainder being plastic polymers (about 20% of the total structure) and metals (about 5% of the total structure).

[0011] Therefore, the difficulty in recycling such a structure stems from the need to separate the layers before they can be recycled individually. Specifically, the aforementioned structure contains hydrophobic plastic materials on both the inner and outer surfaces, and the cellulose fibers are "trapped" and cannot be recovered in standard repulping processes. Even with pretreatment of the packaging, such as shredding individual packages into flakes to allow the fibers to contact the edges, the repulping time will be longer than for recycling paper packages, corrugated cardboard, or any packaging made entirely of paper, or at least containing a high percentage of cellulose fibers. More precisely, polyolefins such as polyethylene and metals (e.g., aluminum) cannot be recycled in the same way as the cellulose-containing layers (paper or cardboard).

[0012] When manufacturing multilayer packaging material structures, applying a plastic layer using known techniques, particularly extrusion (extrusion-lamination or extrusion-coating) (or similarly via extrusion coating processes), inevitably results in a plastic film of such high thickness on the paper. Polymer films obtained through extrusion have thicknesses ranging from 15 μm to several millimeters (maximum 5 mm to 6 mm for most packaging applications).

[0013] The second problem with extruded polymers in multilayer structures, as described above, is that even for low-thickness polymers applied to the substrate, the cohesive strength of the polymer film is very high, and the level of polymer adhesion to the substrate is also high. This prevents such polymers from detaching from the substrate during recycling and inhibits the recycling and repulping of the cellulose fraction during paper flow recycling.

[0014] Therefore, in subsequent recycling processes, multilayer structures comprising mixtures of paper and plastic (polymer) films, extruded (through classic techniques such as extrusion lamination or extrusion coating), cannot be recycled in paper flow recycling because the plastic layers, with a thickness exceeding 15 μm, are too thick to disperse. Simultaneously, the cohesive strength and adhesion levels of these layers, along with adjacent layers in the same structure, are too high to separate from other material layers, particularly paper fibers. The extruded plastic film remains intact in the pulp bath, thus making it difficult to recycle pulp from repulping processes.

[0015] Furthermore, the recycling process for the aforementioned known laminates is expensive and energy-intensive, and is characterized by a relatively low yield of recycled paper fibers (accounting for approximately 60% of the total packaging material in the overall structure), thus not being sufficiently environmentally friendly from a handling and recycling perspective. There is also room for improvement in the recyclability of the remaining portions of the packaging material (i.e., plastic polymers and metal components (e.g., aluminum components)).

[0016] Last but not least, a certain amount of the aforementioned packaging is not recycled because some consumers do not clearly understand in which recycling stream such packaging should be discarded (in paper, plastic, or metal bins).

[0017] An emerging approach to improving the barrier properties of paper is to coat it with water-based polymer dispersions such as styrene-butadiene, EEA, PVOH, acrylates, PVDC, and polyurethane. In this case, the weight of the applied polymer coating is generally lower than that applied via conventional extrusion techniques (extrusion lamination or extrusion coating). Typically, the thickness of the polymer applied to the surface coated with a water-based dispersion ranges from 1 to 15 micrometers, usually around 5 micrometers. Furthermore, even when applying a higher polymer thickness to the substrate using dispersion coating techniques, the resulting polymer film exhibits low cohesive strength and low adhesion of the same polymer to the substrate. "Low" means that during use, the resulting structure meets all necessary mechanical strength standards, but simultaneously, the polymer particles applied to the substrate in the dispersion can easily detach during resizing processes, such as those applied in paper recycling flows. However, a drawback of using dispersion coatings alone is that it cannot provide sufficient barrier properties for paper-based packaging materials.

[0018] Different multilayer structures have been described in the past, which involve laminating paper or cellulose-based materials with cardboard to provide additional barrier properties for packaging food or beverage products.

[0019] US Patent Application 5021298 discloses a laminated high-barrier metallized plastic film. More specifically, this publication discloses applying a thin but smooth plastic coating with a relatively small inherent barrier to the surface of a polyolefin or regenerated cellulose film, and metallizing this coating. Using this structure, the applicant claims that very high barrier properties can be achieved, typically at least ten times and up to a thousand times better than the barrier properties of an uncoated metallized film. The smoothness of the coating is crucial to this invention. Therefore, this invention provides a flexible plastic film coated with a thin layer on one or both sides to obtain a smooth finish, and metallized on one or both coated surfaces. Consequently, the total cellulose fiber content in this structure is very low, which prohibits recycling this structure during paper recycling. Furthermore, the requirements for metallizing polymer and cellulose fiber materials are very different, particularly in terms of the adhesion requirements of metal atoms to the cellulose medium, due to the hygroscopicity and porosity of the cellulose fiber network.

[0020] US Patent 6472081 also discloses a US patent application for metallized polymer films. In this patent, the metallization layer is a very thin metal layer, no more than 5 nm thick, deposited on a polypropylene (PP) core layer co-extruded with a metallizable layer of ethylene vinyl alcohol copolymer (EVOH), polyvinyl alcohol (PVOH), or polyester, using vacuum metallization on a specific adhesive that firmly bonds the metal atoms to the polymer atoms. This document does not address the requirements for metallizing cellulose media, which are actually quite different from the requirements for the adhesion of metal atoms to plastic polymer media. More precisely, due to the presence of air and water vapor (which are not present in the polymer film) trapped between the fibers of the cellulose media, metallization of fiber-based cellulose media requires a much higher manufacturing equipment capacity to maintain an acceptable vacuum level around the cellulose film during metallization. Therefore, metallization of cellulose fiber media is more complex.

[0021] WO2011003565, a PCT application by Tetra Laval, discloses a non-foil packaging laminate for liquid food packaging, comprising a paper layer positioned towards the inside of the laminated packaging material. The packaging laminate also includes a gas barrier coating, applied to the inside of the paper layer by dispersing a liquid gas barrier composition onto the paper layer and subsequently drying it. The packaging laminate also includes a supplementary barrier metal layer, which is vapor-deposited onto a dispersion coating already applied to the inner surface of the paper layer. The invention also relates to a method for manufacturing the packaging laminate and a packaging container made from the packaging laminate. To provide protection on the innermost and outermost sides of the laminate structure, as well as heat-sealing capability, the packaging laminate disclosed in WO2011003565 further includes inner and outer polyolefin layers, which are extruded onto a pre-formed metallized paper or laminated to it as a pre-formed polymer film.

[0022] Although this is a cost-effective packaging structure, the inner and outer layers are made of polyolefin films, extruded into the rest of the structure. As a result, the total amount of plastic polymer in the structure is so high that it prevents the entire packaging material from being recycled in the paper flow recycling process, as is the case with the other multi-layer packaging structures mentioned above. In other words, recycling the material disclosed in WO201103565 requires a complex recycling process to separate large amounts of strong polymer films from the paper layers, each of which can then be recycled or repulped.

[0023] Another example is US 2018 / 311940 A1, a patent application by Tetra Laval Holdings & Financ, which discloses a method for manufacturing laminated cellulose-based liquid or semi-liquid food packaging materials, wherein the laminated packaging material has a bulk material layer of paper, cardboard, or other cellulose-based material, an innermost heat-sealable and liquid-impermeable layer of thermoplastic polymer, the innermost polymer layer being intended to be in direct contact with the packaged food product, and a barrier layer laminated between the bulk layer and the innermost layer. The invention further relates to laminated packaging materials obtained by this method and packaging containers for liquid food packaging, the packaging containers comprising or made from the laminated packaging material obtained by this method. Furthermore, as mentioned above, the laminate presents recyclability issues due to the high total content of the plastic polymer in its structure.

[0024] In light of the foregoing, there is a need for a packaging laminate material that allows for the manufacture of packages using known forming techniques, and that also possesses high barrier properties and a form effective for stacking and transport. As explained above, this packaging laminate material has a significantly reduced amount of plastic polymer contents, enabling it to be recycled along with other paper packaging such as old corrugated boxes (“OCCs”) or mixed paper waste, typically during the paper flow cycle. Furthermore, there is a need to provide highly abrasion-resistant packaging materials, particularly in which the metal layers are not damaged by mechanical stress during storage, transport, or use. Summary of the Invention

[0025] The above objective is achieved by a paper-based barrier multilayer packaging material structure, which is formed as a single sheet and includes the following layers from its outer surface to its inner surface:

[0026] (i) At least one polymer dispersion coating, selected from the following list: ethylene-acrylic acid or methacrylic acid copolymer, vinyl acetate, styrene acrylate, acrylic acid, modified polyvinyl alcohol, ethyl acetate, polyhydroxyalkanoate (PHA).

[0027] Copolymers thereof, polyurethane (PU), polybutylene adipate (PBAT), polybutylene succinate (PBS), poly(butylene succinate-co-butylene adipate) (PBSA), polylactic acid (PLA), or any mixture thereof, with or without mineral fillers, wherein the coating has a thickness of 1 μm to 10 μm,

[0028] (ii) Paperboard having a strength of 120 g / m² 2 and 500g / m 2 between the weights,

[0029] (iii) A water-based or solvent-free adhesive layer selected from the following list: polyvinyl acetate (PVAc), polyurethane (PU), acrylics, polyvinyl alcohol (PVOH), ethylene vinyl alcohol (EVOH), butene glycol vinyl alcohol copolymer (BVOH), starch-based adhesives, or mixtures thereof, said adhesive layer having a thickness between 1 μm and 10 μm.

[0030] (iv) Metallized barrier paper (MBPL), which has a strength of 30 g / m 2 Up to 120g / m 2 Between, preferably between 45 g / m 2 Up to 90g / m 2 The mass weight was between [value missing], and the water vapor transmission rate (WVTR) measured at 38°C and 90% RH was 10 g / m³. 2 / d to 0.1g / m 2 / d, preferably WVTR is 1.0 g / m 2 / d to 0.1g / m 2 / d, and the oxygen transmission rate (OTR) measured at 23°C and 50% RH includes 100 cc / m 2 / d and 0.1cc / m 2 Between d, preferably OTR includes 1.0cc / m 2 / d and 0.1cc / m 2 Between / d

[0031] (v) A waterproof polyolefin sealable coating of any of the following: low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), or a blend of ethyl acrylate and low-density polyethylene (EEA-LDPE), said coating having a thickness of 10 μm to 50 μm, preferably 25 μm to 35 μm.

[0032] According to the principles of the present invention, the total fiber content of the structure is between 85% by weight and 93% by weight.

[0033] In this specification, the term "metallization" (e.g., in the expression "metallized barrier paper layer") refers to the deposition of metal or quasi-metal atoms on the surface of paper or paperboard. Embodiments involving the deposition of alloys comprising metals and quasi-metals may also be considered.

[0034] The “inner side” of a packaging laminate refers to the side intended to face the food contents of the package produced by the packaging laminate.

[0035] This invention provides a packaging material comprising a cardboard layer primarily made of cellulose fibers bonded together by an adhesive lamination using a resizing adhesive. The cardboard is adhered to a highly mechanically resilient barrier paper layer with a metallized layer capable of withstanding the mechanical stresses induced by transforming the entire laminated packaging structure into a final aseptic package. In this invention, the metallized barrier paper layer is laminated to the cardboard layer via an adhesive lamination, unlike prior art structures (e.g., those described in the aforementioned prior art document WO 2011 003565), in which paper and cardboard are bonded by polymer extrusion lamination, which, as explained earlier, presents a recycling problem (complicating fiber recovery during the recycling process in paper recycling). Unlike extrusion lamination, this adhesive lamination facilitates recycling because the different layers, despite exhibiting good structural strength in use, are easily separated from each other during resizing.

[0036] Furthermore, the multilayer structure according to the invention includes a dispersion coating that provides a tightly sealed, heat-sealable coating on its outer surface.

[0037] Due to the dispersion coating, the overall thickness of the polymer material in the structure is significantly reduced relative to the thickness of the paper and cardboard (i.e., cardboard) material. Therefore, the inventors have overcome the technical limitations of known multilayer barrier structures and achieved a multilayer packaging structure with excellent barrier properties against oxygen and moisture transfer, while maintaining a total cellulose fiber content of 85% to 93% of the total material weight. Furthermore, the polymer dispersion coating avoids the high cohesiveness and high adhesiveness of the polymer, and thus solves the recyclability problem (polymer solid particles dispersed in an aqueous carrier medium, rather than a liquid polymer applied to the substrate).

[0038] The multi-layer packaging structure according to the invention is ideally suited for producing carton bricks for aseptic filling. However, cartons for aseptic filling are not the only type of packaging that can be formed from this structure. Generally, any type of packaging formed from flat blanks into 3D packaging is also applicable. In particular, the structure according to the invention can be used to fill liquid, semi-liquid, gel, solid, granular, powdered products, or mixtures thereof. For example, it can be used to form capsules, pods, or pads for roasted and ground coffee or powdered soluble products for use in beverage preparation systems. It can also be used to form beverage bottles or to form flexible, rigid, or semi-rigid pouches for granular or powdered edible products (e.g., snacks, pet food, nutritional products). Alternatively, they can be used to form packaging for ice cream.

[0039] Advantageously, the paper-based barrier multilayer structure according to the invention is characterized in that the interlayer adhesion strength measured between each of the aforementioned layers is higher than 1.5 N / 15 mm, preferably between 5 N / 15 mm and 10 N / 15 mm.

[0040] Preferably, the paperboard layer is a multi-layer paperboard, comprising:

[0041] - An outer layer of pigment-coated or bleached chemical wood pulp, an intermediate layer of bleached or unbleached chemo-thermo-mechanical or thermodynamic wood pulp or unbleached chemical wood pulp, and an inner layer of unbleached chemical wood pulp, or

[0042] - A pigment-coated outer layer of bleached chemical wood pulp, an intermediate layer of bleached chemo-thermo-mechanical wood pulp or bleached chemical wood pulp, and an inner layer composed of bleached chemical wood pulp.

[0043] Typically, the metallized barrier paper layer has a thickness that is advantageously included in the range of 40 μm to 120 μm.

[0044] In a particularly preferred embodiment of the invention, the metallized barrier paper layer comprises, from the outer side to the inner side of the structure:

[0045] -Paper layer,

[0046] - At least one polymer dispersion coating, consisting of a water-based polymer dispersion applied to the paper layer, constitutes a pre-coating to prepare for the deposition of the next layer of inorganic material, and has a thickness ranging from 2 μm to 8 μm.

[0047] - An inorganic layer of at least one of the following materials: aluminum, or alumina, or silicon oxide, deposited onto the pre-coated dispersion coating, the inorganic layer having a thickness between 20 nm and 500 nm.

[0048] - At least one polymer dispersion coating, consisting of a water-based polymer dispersion applied on top of a vacuum-deposited layer, constitutes a post-coating to protect the deposition of the aforementioned inorganic material layer, and has a thickness between 2 μm and 8 μm.

[0049] The so-called inorganic layer refers to metallic or near-metallic deposits.

[0050] The preferred optical density of the barrier paper layer is in the range of 2-5, more preferably in the range of 3.5-4.5. Furthermore, using standard testing ISO 535 or its equivalent DIN EN 20535 or its equivalent TAPPI T 441, it has a light density of 0 g / m³. 2 The preferred water absorption rate of Cobb was measured at 60 min.

[0051] Preferably, the bending stiffness of the material, measured by bending at a 15° angle in the machine direction according to the ISO 2493 standard test procedure, is between 200 mN and 700 mN.

[0052] The present invention also relates to packaging made of the paper-based barrier multilayer structure as described above, which has excellent barrier properties against moisture, liquids and gases (especially oxygen).

[0053] It can be easily recycled in the paper-flow recycling process, and due to its very high cellulose fiber content, the repulping process is easy, efficient and cost-effective, with the ratio of cellulose fiber to the total weight of the package being similar to that obtained when recycling conventional paper or cardboard packages.

[0054] This type of packaging can be used to package all kinds of products in liquid, semi-liquid, powder, or flake form for human and / or animal consumption. Preferably, packaging constructed with the packaging structure according to the invention is particularly suitable for packaging food or beverage products. It provides a long shelf life (at least 6 months) and a particularly effective barrier against the transfer of liquids, moisture, and oxygen. Furthermore, packaging made with the structure according to the invention provides excellent light barrier and a barrier against fat transfer.

[0055] The method of manufacturing this package is not described in further detail in this specification because it corresponds to a well-known method in the art for forming, filling, and sealing a package from a flat, multi-layered structure that is folded and then sealed along its edges to form a closed package.

[0056] Advantageously, the packaging includes a dispensing wall (made of paper, cardboard, or any other suitable material) that can be pierced by a drinking straw, and / or includes an integral plastic nozzle of a known type with a closure. In the latter case, the nozzle and closure are preferably made of readily recyclable or compostable plastic materials (e.g., PHA, PLA, PBS, PBAT, recycled polyolefins, or combinations thereof). Attached Figure Description

[0057] Further features and advantages of the invention are described below in the description of the presently preferred embodiments given with reference to the accompanying drawings, and these features and advantages will be apparent from the description, wherein:

[0058] Figure 1 This is a schematic cross-sectional view of a preferred embodiment of the multilayer barrier paper-based structure according to the present invention. Detailed Implementation

[0059] Generally, in this specification, "extrusion coating" refers to a method of providing a thick polymer layer by using an extruder that forces molten thermoplastic resin (e.g., polyethylene) through a horizontal slit die onto a moving web of a substrate (e.g., paper). The resulting product is a permanently coated web structure.

[0060] The term "extrusion lamination" refers to a method similar to extrusion coating, in which a polymer resin is extruded between two substrates (e.g., a layer of paper and another layer of polymer film) and acts as a binder.

[0061] "Adhesive lamination" refers to a method in which one paper material is coated with an adhesive and laminated onto a second paper or paperboard material.

[0062] In the lamination process, two thick material layers are bonded together by extrusion lamination or adhesive lamination, where the thickness of each layer is much greater than that obtained by dispersion coating.

[0063] "Dispersion coating" refers to a coating technique that applies an aqueous dispersion of fine polymer particles or a polymer solution to the surface of paper or paperboard to form a solid, non-porous film after drying. Dispersion coating can be performed using gravure printing, flexographic printing, rod, blade, die, curtain air knife, or any other known paper coating method. Dispersion coating produces much thinner layers than extrusion because the polymer is mixed in an aqueous solution. This offers advantages in terms of polymer dosage, its barrier properties, and the recyclability of the resulting paper structure. The goal of dispersion coating is to obtain a barrier layer against water, water vapor, grease, oil, gases, etc., through environmentally friendly coating. Another goal is to prepare the surface of paper materials for vacuum deposition processes.

[0064] The term "metallized barrier paper (MBPL)" refers to a barrier paper layer comprising thin metal and / or quasi-metallic layers. Quasi-metals resemble metals in some of their properties. Silicon oxide is an example of a quasi-metal.

[0065] exist Figure 1 A preferred embodiment of the invention is shown in the figure. The figure illustrates a multilayer structure 1 comprising several layers, starting from an inner layer (i.e., the layer that will ultimately come into contact with the packaged product once the structure is formed as packaging) and then extending to an outer layer (i.e., the layer that comes into contact with the external atmosphere once the structure is formed as packaging).

[0066] The first innermost layer is an extruded layer of polyethylene 2 with a thickness of approximately 30 μm. This layer ensures the airtightness of the structure, allowing the formed package to be sealed along its edges, thus achieving finished product packaging. Aseptic filling is also necessary, providing protection against external liquid contact during the filling process to protect the inner liquid-sensitive layer from liquid degradation, thereby maintaining the integrity of the overall structure.

[0067] The next layer is a metallized barrier paper layer, in Figure 1 The term "MBPL" is used in this context. The metallized paper layer MBPL comprises, from the outside to the inside of the structure:

[0068] -Paper layer 6,

[0069] - At least one pre-metallized (pre-coated) polymer dispersion coating 5, having a thickness of 5 μm, is applied to the paper layer 6 by a water-based polymer dispersion.

[0070] - An aluminum metal layer 4 is deposited onto the pre-metallized dispersion coating 5, the metal layer having a thickness of 50 nm, and

[0071] - At least one post-metallized (post-coated) polymer dispersion coating 3, having a thickness of 5 μm, is applied on top of the vacuum-deposited layer 4 by a water-based polymer dispersion.

[0072] The next layer 7 is a 5 μm thick laminate adhesive composed of polyvinyl acetate (PVAC), polyurethane (PU), or acrylic. This layer allows the aforementioned metallized barrier paper layer MBPL to be bonded to the next layer.

[0073] The next layer, number 8, has a weight of 300g / m³. 2 The cardboard layer. This cardboard (or hardboard) layer consists of several layers of bleached, unbleached, and chemi-thermo-mechanical wood pulp. This layer provides stiffness to the entire structure 1. However, its thickness is chosen so that it is not too stiff, and the final structure 1 can be folded to form packages in a conventional forming-filling-sealing (FFS) process to manufacture brick-type and tubular tight packages.

[0074] The final outermost layer 9 is a polymer dispersion coating (in this embodiment) made of styrene acrylate with 30% mineral filler. This layer has a thickness of 5 μm. Its function is to protect the other layers of the structure from mechanical and chemical damage and to provide a liquid seal against the external environment.

[0075] The total cellulose fiber content in this structure is 89%, which ensures excellent recycling efficiency in paper-flow processes. The ratio between the cellulose component and the plastic component is very high, and the entire material repulping process provides excellent results.

[0076] In all possible embodiments of the invention, particularly Figure 1 In the illustrated embodiment, the barrier paper structure “MBPL” can be manufactured according to other embodiments described in the applicant’s patent applications EP AN 20157789.7 and EP 20188363.4.

[0077] More precisely, the paper layer structure can be a paper layer on which an extremely thin polymer layer (i.e., 1 μm to 10 μm, preferably 3 μm and 7 μm, more preferably about 5 μm thick) is applied by a dispersion coating process, and a similarly very thin metal layer, such as an Al2O3 layer, is then applied onto the dispersion-coated polymer layer by vacuum deposition. The resulting paper has excellent barrier properties while being very thin and therefore flexible. Furthermore, due to the very low amount of non-cellulose materials (polymer, metal), barrier paper according to this technology can be easily recycled during paper flow recycling. Such recyclability in the paper flow is not possible in standard laminations used in extrusion techniques for attaching polymer and metal layers to paper.

[0078] For the purposes of this invention, a paper-based packaging material is considered flexible if it is a material that can be bent without breaking. Further, for example, such a flexible material can be a material that can be bent by hand without breaking. Typically, the paper-based flexible packaging material according to the invention can have a g / m³ content of 140 g / m³. 2 Or a smaller basis weight.

[0079] The paper-based flexible packaging material of the present invention can be a packaging material for food products. For example, it can be a primary packaging material, a secondary packaging material, or a tertiary packaging material. If the paper material is a packaging material for food products, the primary packaging material for food products can be a packaging material for food products that comes into direct contact with the actual food product. The secondary packaging material for food products can be a packaging material for food products that helps to secure one or more food products contained in the primary packaging. Secondary packaging materials are typically used when multiple food products are provided to consumers in a single container. The tertiary packaging material for food products can be a packaging material for food products that helps to secure one or more food products contained in the primary packaging and / or primary and secondary packaging during transportation.

[0080] For some applications of the present invention, it may be preferred if the paper-based flexible packaging material coated with the polymer dispersion is non-porous. The ratio of the pore volume to the total volume of a paper material is called the porosity of the paper material. For the purposes of the present invention, if the porosity of a paper material is less than 40%, for example less than 30% or less than 20%, the paper material should be considered non-porous. Alternatively or additionally, since porosity can also be measured by the gas permeability of the material being tested, the paper material described in the present invention may have a gas permeability of less than 10 ml / min. Therefore, in one embodiment of the present invention, the paper material is a non-porous paper material.

[0081] For the purposes of this invention, the dispersion coating may be, for example, one or more layers comprising: acrylic copolymers, polyesters, polyhydroxyalkanoates, natural and chemically modified starches, xylan and chemically modified xylan, polyvinylidene chloride, polyvinyl alcohol, ethyl vinyl alcohol, vinyl acetate, ethyl vinyl acetate, nitrocellulose, waxes, microfibrillated cellulose, polyolefins, silanes, polyurethanes, or combinations thereof.

[0082] Using dispersion coating technology, the dispersion-coated polymer layer on the paper layer has a thickness in the range of 1 μm to 10 μm, preferably in the range of 3 μm to 7 μm. More preferably, the dispersion-coated polymer layer has a thickness of about 5 μm. The thickness of the paper layer before coating with the dispersion-coated polymer is about 60 μm, and at least within the range further provided in this patent specification.

[0083] It should be understood that various changes and modifications to the currently preferred embodiments described herein will be apparent to those skilled in the art. These changes and modifications can be made without departing from the spirit and scope of the invention and without diminishing the accompanying advantages. Therefore, such changes and modifications are intended to be covered by the appended claims.

Claims

1. A paper-based barrier multilayer packaging material structure (1), which is formed into a single sheet and includes the following layers from its outer surface to its inner surface: (i) at least one polymer dispersion coating (9) selected from the following list: ethylene-acrylic acid or methacrylic acid copolymer, polyhydroxyalkanoate (PHA), polyurethane (PU), polybutylene terephthalate (PBAT), polybutylene succinate (PBS), poly(butylene succinate-co-butylene adipate) (PBSA), polylactic acid (PLA), or any mixture thereof, with or without mineral fillers, said polymer dispersion coating having a thickness of 1 µm to 10 µm. (ii) Paperboard (8), which has a density of 120 g / m³ 2 and 500g / m 2 between the weights, (iii) A water-based or solvent-free adhesive layer (7), selected from the following list: polyvinyl acetate (PVAc), polyurethane (PU), acrylics, polyvinyl alcohol (PVOH), ethylene vinyl alcohol (EVOH), butene glycol vinyl alcohol copolymer (BVOH), starch-based adhesives, or mixtures thereof, said adhesive layer having a thickness between 1 µm and 10 µm. (iv) Metallized barrier paper, which has a strength of 30 g / m² 2 Up to 120g / m 2 The mass weight was between [value missing], and the water vapor transmission rate (WVTR) measured at 38°C and 90% RH was 10 g / m³. 2 / d to 0.1g / m 2 / d, and the oxygen transmission rate (OTR) measured at 23°C and 50%RH includes 100cc / m 2 / d and 0.1cc / m 2 Between / d (v) A waterproof polyolefin sealable coating (2) of any of the following: low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), or a blend of ethyl acrylate and low-density polyethylene (EEA-LDPE), wherein the waterproof polyolefin sealable coating has a thickness of 10 µm to 50 µm. The total fiber content of the structure is between 85% and 93% by weight.

2. The paper-based barrier multilayer packaging material structure (1) according to claim 1, wherein the metallized barrier paper has a density of 45 g / m³. 2 Up to 90g / m 2 The weight of the substances between.

3. The paper-based barrier multilayer packaging material structure (1) according to claim 1, wherein the water vapor transmission rate (WVTR) of the metallized barrier paper measured at 38°C and 90%RH is 1.0 g / m³. 2 / d to 0.1g / m 2 / d.

4. The paper-based barrier multilayer packaging material structure (1) according to claim 1, wherein the oxygen permeability (OTR) of the metallized barrier paper measured at 23°C and 50%RH is within 1.0 cc / m 2 / d and 0.1cc / m 2 Between / d.

5. The paper-based barrier multilayer packaging material structure (1) according to claim 1, wherein the waterproof polyolefin sealable coating has a thickness of 25µm to 35µm.

6. The paper-based barrier multilayer packaging material structure (1) according to claim 1, wherein the interlayer adhesion strength measured between each of the aforementioned layers is greater than 1.5 N / 15 mm.

7. The paper-based barrier multilayer packaging material structure (1) according to claim 1, wherein the interlayer adhesion strength measured between each of the aforementioned layers is between 5 N / 15 mm and 10 N / 15 mm.

8. The paper-based barrier multilayer packaging material structure (1) according to any one of claims 1 to 7, wherein the paperboard (8) is a multilayer paperboard comprising: - An outer layer of pigment-coated or bleached chemical wood pulp, an intermediate layer of bleached or unbleached chemo-thermo-mechanical or thermodynamic wood pulp or unbleached chemical wood pulp, and an inner layer of unbleached chemical wood pulp, or - A pigment-coated outer layer of bleached chemical wood pulp, an intermediate layer of bleached chemo-thermo-mechanical wood pulp or bleached chemical wood pulp, and an inner layer composed of bleached chemical wood pulp.

9. The paper-based barrier multilayer packaging material structure (1) according to any one of claims 1 to 7, wherein the metallized barrier paper layer has a thickness ranging from 40µm to 120µm.

10. The paper-based barrier multilayer packaging material structure (1) according to any one of claims 1 to 7, wherein the metallized barrier paper layer comprises, from the outside to the inside of the structure: -Paper layer (6), - At least one pre-coated polymer dispersion coating (5), which is applied to the paper layer (6) by a water-based polymer dispersion and has a thickness between 2µm and 8µm. - At least one inorganic layer (4) of aluminum, alumina, or silicon oxide, said inorganic layer (4) being vacuum deposited onto the pre-coated polymer dispersion coating (5), said layer (4) having a thickness between 20 nm and 500 nm. - At least one post-coated polymer dispersion coating (3) is applied on top of the vacuum-deposited inorganic layer (4) by a water-based polymer dispersion and has a thickness between 2µm and 8µm.

11. The paper-based barrier multilayer packaging material structure (1) according to any one of claims 1 to 7, wherein the optical density of the paper in the metallized barrier paper layer is in the range of 2 to 5.

12. The paper-based barrier multilayer packaging material structure (1) according to any one of claims 1 to 7, wherein the optical density of the paper in the metallized barrier paper layer is in the range of 3.5 to 4.

5.

13. The paper-based barrier multilayer packaging material structure (1) according to any one of claims 1 to 7, wherein the metallized barrier paper layer has a g / m² content of 0 g / m², as determined by standard testing ISO 535 or its equivalent DIN EN 20535 or its equivalent TAPPI T441. 2 Cobb's water absorption rate was measured over 60 minutes.

14. The paper-based barrier multilayer packaging material structure (1) according to any one of claims 1 to 7, wherein the flexural stiffness of the material, measured by bending at a 15° angle in the machine direction according to the ISO 2493 standard test procedure, is between 200 mN and 700 mN.

15. A package made of a paper-based barrier multilayer packaging material structure according to any one of claims 1 to 14.

16. The packaging of claim 15, wherein the packaging includes a dispensing wall pierced by a drinking straw, and / or includes a plastic nozzle with a closure, the nozzle and the closure being made of a plastic material that is readily recyclable or compostable.

17. The packaging according to claim 16, wherein the plastic material is selected from polyhydroxyalkanoate (PHA), polybutylene adipate terephthalate (PBAT), polylactic acid (PLA), polybutylene succinate (PBS), recycled polyolefins, or combinations thereof.

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