Recyclable cardboard packaging material containing a metallized barrier layer applied by transfer metallization.

Abstract

The present invention relates to a paper-based barrier multilayer packaging structure (1) formed as a unit sheet and comprising, from its outer surface to its inner surface, a layer of water-based or solvent-free adhesive (6) having a thickness of 1 μm to 10 μm, at least one protective coating (5) layer having a thickness of 1 μm to 10 μm, a layer (4) of aluminum, aluminum oxide or silicon oxide having an optical density corresponding to 2 to 5, a release coating (3) having a thickness of 0.1 μm to 2 μm, and at least one water-resistant polyolefin sealable coating (2) having a thickness of 10 to 50 μm, preferably 25 to 35 μm.

Description

【Technical Field】 【0001】 The present invention relates to a packaging cardboard material having high barrier properties and recyclable in a recycled paper stream, and a beverage carton made from such a material. 【Background Art】 【0002】 For example, current packages for aseptic filling of edible liquids such as milk, fruit juice, tea, or plant-based beverages, soft drinks, tomato puree, sauces or semi-liquid food formulations are often manufactured from multilayer materials having a paper or cardboard base, in which at least one polymer and at least one metal layer (having a minimum thickness of 6 microns) are assembled by extrusion or adhesive lamination. Such multilayer packaging materials are well known, manufactured as flat blanks or continuous webs, folded into three-dimensional articles, and sealed by induction, ultrasonic or heat transfer sealing to form a sealed package. 【0003】 Optionally, a thermoplastic spout and closure assembly can be assembled leak-free and made into a package so that the consumer can easily dispense the contents. 【0004】 Such packages are well known and are commercially available under trademark names such as "Tetra Brik® Aseptic", "Tetra Prisma® Aseptic", "Combibloc®" or "Combifit®". Such packages are very easy to use and very practical because they can easily form packages of various formats and shapes (e.g., having a square, circular, or oval cross-section) that can be stacked as compact assemblies during transport and storage by folding as described above. For example, when stacked on a pallet, the shape is such that there is little wasted space between two adjacent packages, making these packages an environmentally friendly solution from a transportation perspective. 【0005】 Since many raw materials contained in edible liquids are susceptible to oxidation, visible light, UV light, and / or moisture loss, typical packaging laminates known from the prior art include at least one outer polymer layer (e.g., low-density polyethylene ("LDPE")), a polymer layer (e.g., low-density polyethylene) used as a tie layer between the cardboard and an aluminum foil layer that acts as a barrier, and one or more innermost layers of polyethylene ("PE") that act as a barrier to water contained in the sealable medium and the product packaged therein. 【0006】 Alternatively, the known prior art multilayer packaging structures cited above may also include, for example, high-barrier polymer films made from various metallization techniques, particularly reactive and non-reactive physical vapor deposition (PVD), instead of the oxygen barrier aluminum foil layer described above, to obtain metallized polyethylene terephthalate ("PET-AlOx"), silicon dioxide-coated PET ("PET-SiOx"), metallized polyethylene ("MetPE"), and metallized oriented polypropylene ("OPP-Alox"). Furthermore, the PE layer between the cardboard and the barrier layer can be replaced with an adhesive layer such as a polyurethane ("PU") layer. 【0007】 Such laminated materials for manufacturing beverage carton packaging are adapted for aseptic (or non-aseptic) filling processes. Aseptic filling is a well-known technique that involves heating the liquid to be packaged above a predetermined temperature, passing the liquid under germicidal light (typically ultraviolet light), or exposing the packaging material to a chemical treatment (e.g., ozone, hydrogen peroxide, or chlorine treatment) for a predetermined time, and then filling the pre-treated packages with the treated liquid in a controlled environment where most common bacteria are substantially removed. Such aseptic filling processes ensure that the shelf life of the product is extended, particularly when the packaged product is stored under ambient temperature conditions. 【0008】 For these aseptic filling conditions, the packaging laminate material must be resistant to temperature, light, and chemicals used for decontamination as described above, as well as to the temperature applied to the raw materials or products packed within the material. Such temperatures can reach up to 95°C in a short period of time (generally 1 to 20 seconds, preferably 3 to 10 seconds). 【0009】 When these known packages are to be recycled, they must be separated from other packaging waste and processed separately using specific recycling technologies. These known packages are collected at a mixed collection facility and then separated from other types of packages, either manually or by automated technologies such as near-infrared (NIR) sorting. They are then recycled in specific recycling streams where each of their specific constituent materials is separated from other materials and sent to specialized recyclers. Such recycling processes are complex, and therefore the associated recycling fees, so-called "extended producer responsibility" (EPR) fees, paid by producers and / or end-users are high. 【0010】 The recycling process for the known multilayer barrier packaging structures described above is extremely complex and cannot be carried out using the simpler recycling processes used for standard paper packaging. This is due to the fact that the total content of cellulose fibers in the entire structure is approximately 75% or less, with the remainder being plastic polymers (approximately 20% of the entire structure) and metals (approximately 5% of the entire structure). 【0011】 Therefore, the problem in recycling such structures is that different layers must be separated for individual recycling; in particular, the aforementioned structures contain hydrophobic plastic material on their inner and outer surfaces, and the cellulose fibers are "trapped" and cannot be recovered during standard repulping processes. Even if pre-treatment of the packaging is performed, such as shredding individual packages into flakes to access the fibers through the edges of the flakes, the repulping time will be longer than that of recycling paper packaging, corrugated cardboard, or any packaging made entirely of paper, or containing at least a high proportion of cellulose fibers. More precisely, polyolefins such as polyethylene, and metals (e.g., aluminum) cannot be recycled in the same way as the cellulose fiber-containing layers (paper or cardboard). 【0012】 Currently, when manufacturing multilayer packaging material structures, if plastic layers are applied by known techniques, particularly extrusion (extrusion lamination or extrusion coating) (or similarly by an extrusion coating process), the thickness of the resulting plastic film on paper is inevitably thick. Polymer films obtained by extrusion have thicknesses ranging from 15 μm to several millimeters (up to 5-6 mm for most packaging applications). 【0013】 A second problem with the multilayer extruded polymers described above is that even when the polymer coating on the substrate is thin, the polymer film exhibits very high cohesive strength and a high level of adhesion to the substrate. This hinders the removal of the polymer from the substrate during recycling, thus impeding the recycling and repulping of the cellulose portion in the paper stream recycling process. 【0014】 Therefore, multilayer structures comprising paper and an extruded plastic (polymer) film (by a standard technique such as extrusion lamination or extrusion coating) cannot be recycled in paper stream recycling processes because the plastic layer, having a thickness exceeding 15 μm, is too thick to disperse, and the plastic layer has a cohesive strength and adhesion level that is too high to separate it from other material layers, particularly paper fibers, relative to adjacent layers in the structure. The extruded plastic film remains intact in the paper pulp tank, and therefore it becomes difficult to recycle the paper pulp through the repulping process. 【0015】 Furthermore, the aforementioned known recycling processes for laminated materials are costly, energy-intensive, and have a relatively low yield of recycled paper fibers (approximately 60% of the total amount of packaging material in the entire structure), and are therefore not sufficiently environmentally friendly from a waste and recycling perspective. There is also room to improve the recyclability of the remaining parts of the packaging material (i.e., plastic polymers and metal parts (e.g., aluminum parts)). 【0016】 Last but important, a certain amount of the aforementioned packaging is not recycled because some consumers do not clearly understand which recycling stream (paper, plastic, or metal bin) these packages should be disposed of in. 【0017】 A novel method for improving the barrier properties of paper involves coating the paper with aqueous polymer dispersions such as styrene-butadiene, EEA, PVOH, acrylates, PVDC, and polyurethane. In this case, the coating weight of the applied polymer is generally lower than that of coating by classical extrusion techniques (extrusion lamination or extrusion coating). Generally, the thickness of the polymer applied to a surface coated by aqueous dispersion coating ranges from 1 to 15 microns, and is generally about 5 microns. Furthermore, even when the thickness of the polymer applied to the substrate by dispersion coating techniques is greater than the above, the cohesive strength of the polymer film thus obtained is low, and the level of adhesion of the same polymer to the substrate is also low. "Low" means that, during use, the resulting structure meets all the necessary mechanical strength criteria, but at the same time, the polymer particles applied as a dispersion to the substrate can easily separate in the repulping process applied to the paper recycling stream. However, a drawback of dispersion coating alone is that it does not provide sufficient barrier properties for paper-based packaging materials. 【0018】 Different multilayer structures have been described in the past, including laminations of paper or cellulose-based materials with cardboard, which have additional barrier properties, for use in packaging food or beverage products. 【0019】 U.S. Patent No. 5021298 is a U.S. patent application disclosing a laminated high-barrier metallized plastic film. More precisely, the publication discloses the application of a thin but smooth layer of a plastic coating with relatively low inherent barrier properties to the surface of a polyolefin or regenerated cellulose film, and the metallization of the coating layer. With such a structure, the applicant claims that very high barrier properties can be achieved, generally at least 10 to 1000 times better than the barrier properties of an uncoated metallized film. The smoothness of the coating is important to the above invention. Therefore, a flexible plastic film is provided in which one or both sides are coated with a thin coating to give a smooth finish, and one or both of the coated surfaces are metallized. Consequently, the total content of cellulosic fibers in this structure is very low, and therefore such a structure cannot be recycled in paper recycling processes. Furthermore, the requirements for metallization of polymers and cellulosic fiber materials differ greatly, particularly with respect to the adhesion requirements of metal atoms to the cellulose medium, due to the hygroscopicity and porosity of the cellulosic fiber network. 【0020】 U.S. Patent No. 6,472,081 is also a U.S. patent application disclosing a metallized polymer film. In this patent, the metallized layer is a very thin metal layer with a thickness of 5 nm or less, which is 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 strongly bonds the metal atoms to the polymer atoms. This document does not address the requirements for metallization of cellulose media, which are in fact quite different from the requirements for bonding metal atoms to plastic polymer media. More precisely, the presence of trapped air and water vapor between the fibers of the cellulose media (which is not present in polymer films) means that metallization of fiber-based cellulose media requires much higher manufacturing equipment capabilities to maintain an acceptable vacuum level around the cellulose film during metallization. Thus, metallization of cellulosic fiber media is more complex. 【0021】 International Publication No. 2011003565, a PCT application to Tetra Laval, discloses a non-foil packaging laminate for liquid food packaging, comprising a paper layer, the paper layer located on the inner side of the laminated packaging material. The packaging laminate further comprises a gas barrier coating layer coated on the inside of the paper layer by liquid film dispersion coating of a liquid gas barrier composition onto the paper layer and subsequent drying. The packaging laminate further comprises an auxiliary barrier metal layer deposited on the 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 innermost and outermost protection of the laminated structure and heat-sealability, the packaging laminate disclosed in International Publication No. 2011003565 further comprises inner and outer layers of polyolefin, extruded onto already formed metallized paper or laminated with the metallized paper as an already formed polymer film. 【0022】 Although it is a cost-effective packaging structure, the inner and outer layers are made of polyolefin film and extruded into the rest of the structure. As a result, the overall amount of plastic polymer in the structure is so large that, as with the other multilayer packaging structures mentioned above, the recycling of the entire packaging material in the paper stream recycling process is hindered. In other words, the recycling of the material disclosed in International Publication No. 201103565 requires a complex recycling process that separates a large amount of strong polymer film from the paper layer before each can be recycled or repulped. 【0023】 Considering the above, there is a need for a packaging laminate material that enables the manufacture of packages using known forming techniques, has high barrier properties and a format that is efficient for stacking and transport, and, as described above, has a significantly reduced plastic polymer content, and as a result can generally be recycled in paper stream recycling processes together with other paper packaging such as corrugated cardboard waste ("OCC") or mixed paper waste. Furthermore, there is a need to provide a packaging material with high abrasion resistance, in particular a packaging material in which the metal layer is not damaged by mechanical stress during storage, transport, or use of the packaging material. 【0024】 [Overview of the prefecture] The above objective is a barrier multilayer packaging material structure, formed as a semi-rigid or rigid unit sheet, wherein the outer surface to the inner surface (i) A polymer dispersion coating layer comprising at least one layer selected from the list of ethylene-acrylic acid or methacrylic acid copolymer, vinyl acetate, styrene acrylate, acrylic, modified polyvinyl alcohol, ethyl acetate, polyhydroxyalkanoate (PHA) and its copolymer, polyurethane (PU), polybutylene adipate terephthalate (PBAT), polybutylene succinate (PBS), poly(butylene succinate-co-adipate) (PBSA), polylactic acid (PLA), or any mixture thereof, wherein the coating layer has a thickness of 1 to 10 μm, and (ii) 120 g / m 【0026】 , ~500 g / m 2 of semi-rigid or rigid paperboard having a basis weight of (iii) an aqueous or solvent-free adhesive layer selected from the list of polyvinyl acetate (PVAc), polyurethane (PU), acrylic, polyvinyl alcohol (PVOH), ethylene vinyl alcohol (EVOH), butenediol vinyl alcohol copolymer (BVOH), starch-based adhesives, or mixtures thereof, the adhesive layer having a thickness included between 1 μm and 10 μm, an adhesive layer; (iv) at least one protective coating layer selected from the list of polyvinyl alcohol (PVOH), ethylene ethyl acrylate (EEA), or polyurethane (PU), the protective coating layer having a thickness of 1 μm to 10 μm, a protective coating layer; (v) a layer of aluminum, or aluminum oxide, or silicon oxide having an optical density corresponding to 2 to 5, a metallization layer applied by physical vapor deposition or chemical vapor deposition processes or by transfer metallization; (vi) a release coating layer selected from the list of vinyl chloride, acrylic polymers, polyurethane (PU), nitrocellulose, or mixtures thereof, the release coating layer having a thickness of 0.1 μm to 4 μm, a release coating layer; (vii) a layer of at least one water-resistant polyolefin sealable coating of low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), or a blend of ethyl-acrylate and low-density polyethylene (EEA-LDPE), the coating layer having a thickness of 10 to 50 μm, preferably 25 to 35 μm, a coating layer; achieved by a barrier multilayer packaging material structure comprising. 【0025】 According to the present invention, the total fiber content of the above structure is 90% to 96% by weight. 【0026】 The "inside" of the packaging structure means the side of the package produced from the above packaging structure that is intended to face the filled food contents. 【0027】 The present invention provides a packaging material composed of a paperboard layer (also referred to herein as "paperboard" or "carton") mainly made of cellulose fibers, joined by adhesive lamination using an adhesive that can be repulped, and the paperboard layer is metallized with a very thin layer of metal atoms transferred by a direct transfer metallization process. The direct transfer metallization process involves the transfer of a metal layer from a first substrate (e.g., a polyethylene terephthalate (PET) film) onto a second substrate (in this case, a paperboard layer pre-coated with an adhesive layer and a protective coating layer for the preparation of metal transfer). 【0028】 Fiber-based packaging materials having a basis weight exceeding 120 g / m2 are generally difficult to metallize because they release a significant amount of water vapor and air during the evacuation process. The release of vapor and air is difficult to control and adversely affects the barrier obtained on the thick fiber-based packaging substrate. Therefore, the transfer metallization process in which metallization is performed on a PET film and then transferred to the board only as a result is more suitable for creating a high barrier against water vapor and oxygen on the paperboard. 【0029】 Furthermore, the multilayer structure according to the present invention includes a layer dispersion-coated with a heat-sealable coating that provides a seal on its outer surface. 【0030】 By dispersion coating, the total thickness of the polymer material in the structure is significantly reduced compared to the thickness of the cardboard (i.e., thick paper) material. As a result, the inventors have overcome the technical limitations of known multilayer barrier structures and achieved a packaging multilayer structure with excellent barrier properties against oxygen and moisture movement, as well as resistance to liquid contact from its inner or outer surface, while simultaneously achieving a total content of cellulose fibers, preferably comprising 90% to 96% of the total material weight. Furthermore, the polymer dispersion coating avoids high aggregation and adhesion of the polymer, thus solving the problem of recyclability (by coating the substrate with solid particles of polymer dispersed in a water carrier medium, rather than liquid polymer). The inventors have succeeded in forming a multilayer structure having only a small amount of polymer layer formed by extrusion (extrusion lamination or extrusion coating), providing a multilayer structure with cellulose material in a certain ratio to non-cellulose material and with an extremely high cellulose content. The polymer layer described above has relatively low cohesive strength and relatively low adhesion to the rest of the substrate (especially the cellulose layer), so it easily disintegrates in the paper repulping tank. Therefore, the resulting structure exhibits excellent paper stream recycling capabilities. 【0031】 The multilayer packaging structure according to the present invention is well suited to the manufacture of carton bricks for aseptic filling. However, aseptic filling cartons are not the only type of package that can be formed from this structure. In general, any type of package formed from a flat blank into a 3D package is also applicable. In particular, the structure according to the present invention can be used to pack liquids, semi-liquids, gels, solids, particles, powder products, or mixtures thereof. For example, the structure according to the present invention can be used to form capsules, pods, or pads for roasted and ground coffee, or powdered soluble products, for use in beverage preparation systems. The structure according to the present invention can also be used to form beverage bottles, or to form flexible, rigid, or semi-rigid sachets for particle or powdered food products such as snacks, pet food, or nutritional preparations. Alternatively, the structure according to the present invention can be used to form packaging for ice cream. 【0032】 Furthermore, in a preferred embodiment of the present invention, the interlayer adhesion strength measured between each of the above layers is greater than 1.5 N / 15 mm, preferably 5 to 10 N / 15 mm. 【0033】 In one embodiment, the structure is inverted so that the transfer metallization layer is applied to the cardboard side facing the outer surface of the material structure. 【0034】 Preferably, the cardboard layer is A pigment coating, or an outer layer of bleached chemical pulp, an intermediate layer composed of bleached or unbleached chemothermetic pulp or thermomechanical pulp, or unbleached chemical pulp, and an inner layer composed of unbleached chemical pulp, or A pigment-coated bleached chemical pulp outer layer, a bleached chemothermetic pulp or bleached chemical pulp intermediate layer, and an inner layer composed of bleached chemical pulp. It is a multilayer cardboard containing [a specific material]. 【0035】 In one embodiment, unbleached pulp can be present on the outside or inside of the structure. 【0036】 Preferably, when measured by bending the material at a 15° angle in the mechanical direction according to the ISO 2493 standard test procedure, the bending stiffness of the above material falls within the range of 200 to 700 mN. 【0037】 The present invention further relates to a package made from such a barrier multilayer structure having excellent moisture, liquid, and gas (especially oxygen) barrier properties. 【0038】 The above packaging is easily recyclable in the paper stream recycling process, and due to its very high cellulosic fiber content, the repulping process is easy, efficient, and cost-effective, and the ratio of cellulose fibers to the total weight of the packaging is similar to that obtained when recycling conventional paper or cardboard packaging. 【0039】 Such packaging can be used to pack all kinds of products in liquid, semi-liquid, powder, or flake form for consumption by humans and / or animals. Preferably, packaging made from the packaging structure according to the present invention is particularly suitable for packing food or beverage products. The above packaging provides a long shelf life (at least 6 months) and a particularly efficient barrier against liquid, moisture, and oxygen transfer. Furthermore, packaging manufactured from the structure according to the present invention provides an excellent light barrier, as well as a barrier against fat transfer. 【0040】 The manufacturing process for such packages corresponds to well-known forming, filling, and sealing processes in the art, which involve forming a package from a flat, multilayer structure, folding it, and then sealing along its edges to form a sealed package; therefore, it will not be described in further detail herein. 【0041】 Advantageously, the package comprises a known type of one-piece plastic spout having a distribution wall through which a drinking straw (made of paper, carton, or any other suitable material) can penetrate, and / or a closure. In the latter case, the spout and closure are preferably made from readily recyclable or compostable plastic material (e.g., PHA, PLA, PBS, PBAT, recycled polyolefin, or a combination thereof). [Brief explanation of the drawing] 【0042】 Additional features and advantages of the present invention are described below in reference to the drawings and will become apparent therefrom. [Figure 1] This is a schematic cross-sectional view of a preferred embodiment of a multilayer barrier structure according to the present invention. [Modes for carrying out the invention] 【0043】 Generally, in this specification, “extrusion coating” means a method of providing a thick layer of polymer by using an extruder to extrude molten thermoplastic resin (e.g., polyethylene) through a horizontal slot die onto a moving web of a substrate (e.g., paper). The resulting product is a permanently coated web structure. 【0044】 "Extrusion lamination" refers to a process similar to extrusion coating, in which a polymer resin is extruded between two substrates (for example, a layer of paper and another layer of polymer film) and acts as a binder. 【0045】 "Adhesive lamination" refers to the process in which one paper material is coated with an adhesive and then laminated onto a second paper or cardboard material. 【0046】 In the lamination process, two thick layers of material are combined by either extrusion lamination or adhesive lamination, and the thickness of each layer is much greater than the thickness obtained by dispersion coating. 【0047】 "Dispersion coating" refers to a coating technique in which an aqueous dispersion or polymer solution of fine polymer particles is applied directly to the surface of paper or cardboard to form a solid, non-porous film after drying. Dispersion coating can be carried out by gravure, flexogravure, rod, blade, slot die, curtain air knife, or any other known paper coating method. Because the polymer is mixed in an aqueous solution, dispersion coating can produce much thinner layers than extrusion. This offers advantages in terms of polymer usage, its barrier performance, and the recyclability of the resulting paper structure. The goal of dispersion coating is to create a barrier layer against water, water vapor, grease, oil, gas, etc., through an environmentally friendly coating. Another goal is to prepare the surface of cellulosic materials for vacuum deposition processes. 【0048】 Figure 1 illustrates a preferred embodiment of the present invention. This figure shows a multilayer structure 1 comprising multiple layers, starting from an inner layer (i.e., the layer that comes into contact with the final packed product after the structure is formed into a package) to an outer layer (i.e., the layer that comes into contact with the external atmosphere after the structure is formed into a package). 【0049】 In a specific example of the structure 1 according to the present invention, as shown in Figure 1, the first innermost layer 2 is a liquid-tight, sealable layer of polyethylene (PE) having a thickness of 27 μm. This layer ensures that the formed package can be sealed along its edges due to the sealing properties of the structure, in order to realize the finished package. In aseptic filling, it is essential to provide protection from external liquid contact during the filling process so as to protect the internal liquid-sensitive layer from liquid degradation ("soggy effect") and thereby protect the overall structural integrity. 【0050】 The next layer is a release coating layer 3 made of vinyl chloride and having a thickness of 0.7 μm. 【0051】 The next layer, layer 4, is a vacuum-deposited aluminum layer with an optical density of 3. 【0052】 The next layer, layer 5, is a protective coating layer composed of polyvinylidene dichloride (PVDC) and has a thickness of 3 μm. 【0053】 The next layer, 6, has a thickness of 3 μm and is a laminated adhesive containing polyurethane (PU). 【0054】 The next layer, layer 7, is 300g / m². 2 This is a cardboard layer having a basis weight of . This cardboard (or thick cardboard) layer consists of multiple layers of bleached pulp, unbleached pulp, and chemothermetic pulp. This layer provides rigidity to the entire structure 1. However, its thickness is selected so as not to make it too rigid, and the final structure 1 can be folded to form a package in a conventional form-fill-seal (FFS) process to produce brick and tube-type dense packages. 【0055】 The final outermost layer 8 is a polymer dispersion coating layer made of styrene acrylate with 30% inorganic filler added (in this example). This layer has a thickness of 5 μm. Its role is to protect the other layers of the structure from mechanical and chemical damage and to provide liquid-tightness from the external environment. 【0056】 The total cellulosic fiber content in this structure is 95%, ensuring excellent recycling efficiency in the paper stream process. The ratio of cellulose components to plastic components is very high, resulting in excellent results in the repulping process of the entire material. 【0057】 The packaging material of the present invention may be a flexible packaging material structure for food products. This packaging material may be, for example, a primary packaging material, a secondary packaging material, or a tertiary packaging material. The primary packaging material for food products is in direct contact with the actual food product. The secondary packaging material for food products may be a food product packaging material that helps to secure one or more food products contained in the primary packaging. The secondary packaging material is typically used when multiple food products are provided to consumers in a single container. The tertiary packaging material for food products may be a food product packaging material that helps to secure the primary packaging and / or one or more food products contained in the primary and secondary packaging during transport. 【0058】 In some applications of the present invention, it may be preferable that the packaging material coated with the polymer dispersion be nonporous. The ratio of the pore volume of a paper material to the total volume is called the porosity of the paper material. For the purposes of the present invention, a cardboard material is considered nonporous if it has a porosity of less than 40%, for example, less than 30% or less than 20%. Additionally or alternatively, porosity can also be measured by the air permeability of the material being tested, and the cardboard material described in the present invention may have an air permeability of less than 10 mL / min. Therefore, in one embodiment of the present invention, the material is a nonporous cardboard material. 【0059】 For the purposes of the present invention, the dispersion coating may be one or more layers comprising, for example, acrylic acid copolymer, polyester, polyhydroxyalkanoate, natural and chemically modified starch, xylan and chemically modified xylan, polyvinylidene dichloride, polyvinyl alcohol, ethyl vinyl alcohol, vinyl acetate, ethyl vinyl acetate, cellulose nitrate, wax, microfibrillated cellulose, polyolefin, silane, polyurethane, or a combination thereof. However, it is preferable that the coating does not contain polyolefin. 【0060】 In dispersion coating technology, the dispersion-coated polymer layer on the paper layer has a thickness within the range of 1 μm to 10 μm, preferably within the range of 3 μm to 7 μm. More preferably, the dispersion-coated polymer layer has a thickness of about 5 μm, in either case within the range separately provided herein. 【0061】 It should be understood that various changes and modifications to the current preferred embodiments described herein will be apparent to those skilled in the art. Such changes and modifications may be made without departing from the scope of the invention and without diminishing the incidental advantages of the invention. Accordingly, such changes and modifications are intended to be covered by the appended claims.

Claims

[Claim 1] A barrier multilayer packaging material structure (1), formed as a semi-rigid or rigid unit sheet, wherein from its outer surface to its inner surface, (i) At least one polymer dispersion coating layer (8) selected from the list of ethylene-acrylic acid or methacrylic acid copolymer, vinyl acetate, styrene acrylate, acrylic, modified polyvinyl alcohol, ethyl acetate, polyhydroxyalkanoate (PHA) and its copolymer, polyurethane (PU), polybutylene adipate terephthalate (PBAT), polybutylene succinate (PBS), poly(butylene succinate-co-adipate) (PBSA), polylactic acid (PLA), or any mixture thereof, having or not having an inorganic filler, and having a thickness of 1 to 10 μm, (ii) 120g / m ２ ~500g / m ２ A semi-rigid or rigid cardboard layer (7) having a basis weight, (iii) A layer (6) of an adhesive layer (6) selected from the list of polyvinyl acetate (PVAc), polyurethane (PU), acrylic, polyvinyl alcohol (PVOH), ethylene vinyl alcohol (EVOH), butenediol vinyl alcohol copolymer (BVOH), starch-based adhesives, or mixtures thereof, having a thickness between 1 μm and 10 μm, (iv) At least one protective coating layer (5) selected from the list of polyvinyl alcohol (PVOH), ethylene ethyl acrylate (EEA), or polyurethane (PU), wherein the protective coating layer (5) has a thickness of 1 μm to 10 μm, (v) A layer (4) of aluminum, aluminum oxide, or silicon oxide having an optical density of 2 to 5, which is coated by a physical vapor deposition or chemical vapor deposition process, or by transfer metallization, (vi) A release coating layer (3) selected from the list of vinyl chloride, acrylic polymer, polyurethane (PU), nitrocellulose, or mixtures thereof, having a thickness of 0.1 μm to 4 μm, (vii) A water-resistant polyolefin sealable coating layer (2) of at least one of low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), or a blend of ethyl acrylate and low-density polyethylene (EEA-LDPE), having a thickness of 10 to 50 μm or 25 to 35 μm, A barrier multilayer packaging material structure (1) having a total fiber content of 90% to 96% by weight. [Claim 2] The 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 or between 5 and 10 N / 15 mm. [Claim 3] The aforementioned cardboard layer (7) An outer layer of pigment-coated or bleached chemical pulp, an intermediate layer composed of bleached or unbleached chemothermetic pulp or thermomechanical pulp, or unbleached chemical pulp, and an inner layer composed of unbleached chemical pulp, or A pigment-coated bleached chemical pulp outer layer, a bleached chemothermetic pulp or bleached chemical pulp intermediate layer, and an inner layer composed of bleached chemical pulp. A barrier multilayer packaging material structure (1) according to claim 1 or 2, comprising multilayer cardboard. [Claim 4] A barrier multilayer packaging material structure (1) according to any one of claims 1 to 3, wherein the bending stiffness measured by bending at a 15° angle in the machine direction according to the ISO 2493 standard test procedure is 200 to 700 mN. [Claim 5] A package made of a barrier multilayer packaging material structure (1) according to any one of claims 1 to 4. [Claim 6] The package according to claim 5, comprising a plastic spout having a dispensing wall through which a drinking straw can penetrate and / or a closure, wherein the plastic spout and the closure are made from polyhydroxyalkanoate (PHA), polybutylene adipate terephthalate (PBAT), polylactic acid (PLA), polybutylene succinate (PBS), recycled polyolefin, or a combination thereof.

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