Metallized paper multilayer packaging material

Abstract

The present invention relates generally to the field of multilayer packaging materials. In particular, the present invention relates to a metallized paper-based multilayer packaging material comprising a paper layer, a coating layer outer than the metal coating, a metal coating layer, and at least one coating layer inner than the metal coating. The present invention further relates to the use of the metallized paper-based multilayer packaging material according to the present invention for packaging food products, and to food packages made from the metallized paper-based multilayer packaging material. In one embodiment of the present invention, the metallized paper-based multilayer packaging material can be recycled together with other paper packaging materials.

Description

[Technical Field]

[0001] The present invention generally relates to the field of multilayer packaging materials. In particular, the present invention relates to a metallized paper-based multilayer packaging material comprising a paper layer, a pre-metallized coating layer, a metallized layer, and at least one post-metallized coating layer. The present invention further relates to the use of the metallized paper-based multilayer packaging material according to the present invention for packaging food, and to food packaging manufactured from the metallized paper-based multilayer packaging material. In one embodiment of the present invention, the metallized paper-based multilayer packaging material can be recycled together with other paper packaging materials and non-packaging materials.

[0002] [Background technology] Plastic packaging is frequently used in economic activities and people's daily lives. Plastic packaging offers several advantages, including flexibility and light weight. Lightweight packaging contributes, for example, to fuel savings and CO2 reduction during transportation. The barrier properties of plastic packaging have a positive effect on extending shelf life, thus helping to reduce food waste. Barrier properties also help ensure food safety.

[0003] However, according to the European Strategy on Plastics in the Circular Economy, recently published by the European Commission, approximately 25.8 million tons of plastic waste are generated in Europe every year, less than 30% of which is recovered for recycling, and 150,000 to 500,000 tons of plastic waste end up in the oceans each year.

[0004] Significant efforts are being made in industry and commerce to ensure the reduction of plastic waste. Some supermarkets, for example, are replacing plastic bags with paper bags. However, replacing plastic with paper in food packaging is not an easy task. Changes to packaging materials must not compromise consumer safety. Packaging must not only serve to protect food, but also be strong enough to withstand machine handling during the manufacturing process and effectively protect food products.

[0005] Therefore, multilayer packaging materials have been developed that comprise a paper layer or cardboard layer and one or more layers of plastic or metal film, providing robustness and, in particular, barrier properties against oxygen and moisture.

[0006] Currently, when manufacturing multilayer packaging material structures, if layers of plastic are applied using known techniques, particularly extrusion (extrusion lamination or extrusion coating), or similarly by adhesive lamination processes, the thickness of the resulting plastic film on paper is inevitably thick.

[0007] A second problem with the multilayer extruded polymers described above is that even when the polymer is thinly coated onto the substrate, the polymer film exhibits very high cohesive strength, resulting in a high level of adhesion of the polymer to paper or cardboard (i.e., cellulose-based) substrates. This hinders the removal of the polymer from the substrate during recycling, thus impeding the recycling and repulping of the cellulose fiber portion in the paper stream recycling process.

[0008] Therefore, multilayer structures comprising paper and a plastic (polymer) film that has been extruded or bonded (by a standard technique such as extrusion lamination or extrusion coating) cannot be recycled in paper stream recycling processes because the plastic layer is too thick to disperse during subsequent recycling processes, and the plastic layer has too high agglomeration strength and adhesion levels to separate from other adjacent material layers in the structure, particularly from the paper fibers. The extruded plastic film remains intact in the paper pulp tank, making it difficult to recycle the paper pulp through the repulping process.

[0009] 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)).

[0010] Therefore, there is a need for paper-based materials with improved barrier properties and better recyclability. In particular, there is a need for paper-based materials with improved barrier properties that do not contain a thick plastic film layer, in order to enable easier sorting and separation of paper-based materials during recycling.

[0011] International Publication No. 2000 / 076862(A9) describes a laminated structure for packaging applications comprising a paper substrate and at least one polymer / nanoclay composite layer having a thickness in the range of 0.7 to 9 nanometers and containing clay particles, which is applied to the paper substrate by an extrusion or lamination process.

[0012] Similarly, WO 00 / 77300 (A1) and WO 96 / 13380 (A1) disclose multilayer packaging materials in which a thick plastic layer is extruded, co-extruded or laminated onto a cellulose layer.

[0013] In the art, there is still a need to further improve the barrier properties and recyclability of such paper-based packaging materials. In particular, there is a need for packaging materials that can be easily recycled in a paper or cardboard recycling stream.

[0014] Furthermore, in the packaging of food products, good barrier properties are essential to maintain the safety and quality of the packaged food. Typically, such barrier properties include gas permeability, e.g. O2, CO2 and N2, vapour permeability, e.g. water vapour, liquid permeability, e.g. water or oil, aroma permeability, and light permeability.

[0015] One way to provide a good barrier to paper-based packaging materials is the introduction of a metal layer. Indeed, currently, metal-coated paper materials are available on the market as an alternative to current state-of-the-art multilayer packaging.

[0016] Problems associated with the introduction of a metal layer into a paper-based packaging material are the sensitivity of the metal layer to mechanical stress, as well as the insufficient smoothness and high porosity of the paper material. Mechanical stress can, for example, easily lead to the loss of the necessary barrier properties that the metallised packaging material should provide. Such loss of barrier properties can be due to the loss of integrity of the metal and metal oxide layers formed during the deposition process.

[0017] Therefore, there is a desire in the art to provide metallised paper-based multilayer packaging materials that exhibit sufficient barrier properties, particularly when subjected to mechanical stress, are easily recyclable in a paper recycling process, the use of such metallised paper-based multilayer packaging materials for packaging food products, and food packages made from such metallised paper-based multilayer packaging materials.

[0018] 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.

[0019] [Overview of the prefecture] The object of the present invention is to enhance or improve the current state of the art, in particular to provide a metallized paper multilayer packaging that provides sufficient barrier properties for packaging food products even under mechanical stress and is easier to recycle, to provide the use of a metallized paper multilayer packaging for packaging dry food products, or at least to provide a useful alternative to existing packaging solutions in the art.

[0020] Vacuum-deposited metal layers are typically used in the art for visual appearance and are therefore often found, for example, in high-end packaging for alcoholic beverages, tobacco, or cosmetics.

[0021] Aluminum coatings are also used to coat plastic films, for example, to reduce the permeability of oxygen and water vapor.

[0022] However, to the best of the inventor's knowledge, no metallized paper-based packaging material is known in the art that is suitable for food products, is easily recyclable, and possesses excellent barrier properties even when subjected to mechanical stress.

[0023] To our surprise, the inventors have discovered that the objective of the present invention can be achieved by applying at least one coating layer located inside the metal coating on the metal coating layer of a metallized paper-based packaging material.

[0024] At least one coating layer located inside the metal coating, A tie layer coating located inside the metal coating containing an ethylene acrylic acid copolymer dispersion, A coating inside the metal coating, which is applied on a tie layer coating inside the metal coating, and which contains a plain or mineral-filled ethyl vinyl, butyl vinyl, or polyvinyl alcohol copolymer, Particularly good results were obtained when this feature was included.

[0025] In particular, the use of butyl vinyl alcohol (BVOH) in coatings outside and / or inside the metal coating provides excellent biodegradability, especially making the packaging material compostable in accordance with the EN17427 (2000) standard for "home compostability".

[0026] Therefore, the object of the present invention is achieved by the subject matter of the independent claim. The dependent claims further develop the concept of the present invention.

[0027] Therefore, the present invention provides a metallized paper-based multilayer packaging material comprising a paper layer, a coating layer outside the metal coating, a metal coating layer, and at least one coating layer inside the metal coating.

[0028] The present invention further provides the use of the metallized paper-based multilayer packaging material according to the present invention for packaging food products.

[0029] 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.” [Brief explanation of the drawing]

[0030] 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 diagram of a metallized multilayer paper structure. [Figure 2] This is a scanning electron microscope image of a cross-section of a metallized multilayer paper structure after it has been folded.

[0031] [Modes for carrying out the invention] The present invention is, in part, a metallized paper-based multilayer packaging material, wherein the material is layered sequentially from the outside (i.e., the outer surface of the packaging) to the inside (i.e., the side that comes into contact with the product enclosed in the packaging), paper layer, The coating layer located outside the metal coating, Metal coating layer, At least one coating layer located inside the metal coating, This relates to a metallized paper-based multilayer packaging material.

[0032] The dispersion coating layer outside the metal coating smooths the paper surface, closing so-called "pinholes" that, if present, would cause barrier loss after vacuum metal coating, improving barrier properties and preparing the surface for depositing metal atoms. The smoother (i.e., more uniform) the paper surface, the more homogeneous the metal layer will be. The physical vapor deposition process (metal coating) is a line-of-sight application, and if the surface to be metallized has a non-uniform surface topography, metal atoms cannot deposit inside cracks (valleys / holes) present on the paper surface, resulting in insufficient filling of metal flakes and ultimately loss of barrier properties. The layer outside the metal coating itself also provides, to some extent, a moderate oxygen barrier (OTR) and moisture barrier (WVTR). Furthermore, the coating outside the metal coating acts as a flexible interface between the paper layer and the metal coating layer, thus improving the mechanical elasticity of the metal layer. This coating also protects the metal from oxidation and direct interaction with water vapor.

[0033] The metal coating layer, in combination with a dispersion coating located outside the metal coating, provides a moisture barrier (WVTR) and an oxygen barrier (OTR).

[0034] The layer inside the metal coating provides an oxygen barrier (OTR), as well as heat sealing functionality and protection of the metal layer from physical damage, and may also provide an oxygen barrier (OTR) depending on the chemical properties of the coating.

[0035] Generally, dispersion coating layers located outside and inside the metal coating are used to sandwich extremely thin layers of metal. The advantages are that, on the one hand, the layer outside the metal coating provides a suitable medium for depositing metal atoms and a barrier against oxygen and moisture, and on the other hand, the layer inside the metal coating protects the metal layer from mechanical damage, especially when the entire packaging material is bent, folded, or subjected to mechanical stress such as during heat sealing (when manufacturing and closing a three-dimensional packaged article from the packaging material).

[0036] The inventors have found that if one or the other of a layer located outside or inside the metal coating is missing around the metal layer, or if the mechanical and adhesive properties of such a layer are inadequate, the overall barrier properties, mechanical resistance, and flexibility of the structure are lost. The main role of the layer located inside the metal coating is to mechanically reinforce the structure and improve its flexibility, but these effects are found to be further enhanced by the presence of the layer located outside the metal coating.

[0037] The packaging material of the present invention can be used to package a product by positioning a metal coating layer on the side of the paper layer facing the product being packaged. The product being packaged may be, for example, a food product.

[0038] With regard to the object of the present invention, the term "food" means any substance, whether processed, semi-processed, or unprocessed, intended for human consumption, 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.

[0039] Thanks to the polymer dispersion coating, the total thickness of the polymer material in the structure is drastically reduced compared to the thickness of the paper material. Therefore, the inventors have achieved overcoming the technical limitations of known multilayer barrier structures and have achieved a packaging multilayer structure with excellent barrier properties against the movement of oxygen and moisture, while simultaneously achieving a total cellulose fiber content preferably comprising 80% to 95% of the total material weight. Furthermore, the thin thickness of the polymer dispersion coating avoids high aggregation and adhesion of the polymer to the fibers, thus solving the problem of recyclability (solid polymer particles dispersed in a water carrier medium are easily separated from the fibers). The inventors have succeeded in forming a multilayer structure that completely removes the polymer layer formed by extrusion (extrusion lamination or extrusion coating), providing a multilayer structure with a very high fiber content, having cellulose fibers in a certain ratio to non-cellulose materials. The polymer layer easily disintegrates in the repulping process because the polymer aggregation strength is relatively low and the adhesion of the polymer to the rest of the substrate (especially the cellulose fibers) is also relatively low. Therefore, the resulting structure exhibits excellent repulping ability and high fiber yield, making it acceptable for waste paper recycling in most countries. Unlike existing structures known in the art, the vacuum-deposited metal layer of non-cellulosic polymers and metallic materials, with very low content, readily disintegrates, dissolves, and separates from the cellulose.

[0040] In one embodiment of the present invention, a printed layer can be applied to a paper layer.

[0041] One advantage of the metallized paper-based packaging material of the present invention is that it does not require a polyolefin layer. As a result, the metallized paper-based packaging material is easier to recycle than paper-based packaging materials that include a polyolefin layer, such as a polyethylene (PE) layer or a polypropylene (PP) layer.

[0042] Therefore, the subject of the present invention is also a metallized paper-based multilayer packaging material, wherein the material is arranged sequentially from the outside (i.e., the outer surface of the packaging) to the inside (i.e., the side that comes into contact with the product enclosed in the packaging), paper layer, The coating layer located outside the metal coating, Metal coating layer, At least one coating layer located inside the metal coating, The present invention relates to a metallized paper-based multilayer packaging material that comprises a metallized paper-based multilayer packaging material that does not include an extruded or laminated polyolefin layer.

[0043] The present invention also relates to a metallized paper-based multilayer packaging material, wherein the material is sequentially applied from the outside (i.e., the outer surface of the packaging) to the inside (i.e., the side that comes into contact with the product enclosed in the packaging), paper layer, The coating layer located outside the metal coating, Metal coating layer, At least one coating layer located inside the metal coating, The present invention relates to a metallized paper-based multilayer packaging material that includes a metallized paper-based multilayer packaging material, wherein the metallized paper-based multilayer packaging material does not include a PE layer.

[0044] The present invention further relates to a metallized paper-based multilayer packaging material, wherein the material is arranged sequentially from the outside (i.e., the outer surface of the packaging) to the inside (i.e., the side that comes into contact with the product enclosed in the packaging), paper layer, The coating layer located outside the metal coating, Metal coating layer, At least one coating layer located inside the metal coating, The present invention relates to a metallized paper-based multilayer packaging material that includes a metallized paper-based multilayer packaging material, wherein the metallized paper-based multilayer packaging material does not include a PP layer, for example, an extruded or laminated PP layer.

[0045] In one embodiment of the present invention, the metallized paper-based multilayer packaging material of the present invention is arranged sequentially from the outside (i.e., the outer surface of the packaging) to the inside (i.e., the side that comes into contact with the product enclosed in the packaging), paper layer, The coating layer located outside the metal coating, Metal coating layer, At least one coating layer located inside the metal coating, It's okay if it's from there.

[0046] In one preferred embodiment of the present invention, the paper-based multilayer packaging material is constructed sequentially from its outside (i.e., the outer surface of the packaging) to its inside (i.e., the side that comes into contact with the product enclosed in the packaging), 40-120g / m 2 A paper layer having a basis weight within the range, A first dispersion coating layer located outside the metal coating, containing a compound of BVOH (corresponding to 10% of the total material weight in solids) and clay (corresponding to 5% of the total material weight in solids), A second dispersion coating layer located outside the metal coating, containing BVOH (equivalent to 10% of the total material weight in solids), A metal coating layer comprising vacuum-deposited aluminum, or a thin layer deposit of aluminum oxide (AlOx) or silicon oxide (SiOx), wherein the layer has a thickness within the range of 6 nm to 80 nm, 0.5~10g / m 2 A dispersion coating layer inside the metal coating containing an amount of BVOH, It is equipped with.

[0047] To our surprise, the inventors have found that multiple (at least two) separate dispersion coating layers, rather than just one, located outside the metal coating, offer unexpected advantages, as follows:

[0048] Firstly, it was found that applying the dispersion coating outside the metal coating in multiple passes maximizes the planarization of the paper surface by applying the dispersion coating outside the metal coating, thereby providing the greatest benefit in reducing pinholes. In other words, multiple applications of the dispersion coating layer outside the metal coating increase the effect of planarization of the paper surface and the closure of pinholes on the paper surface. Furthermore, the presence of clay in the first layer of coating can further improve the surface coverage and planarization.

[0049] Preferably, a certain amount of time is given between the application of two consecutive dispersion coating layers, so that the layers are completely dry before the next layer is applied.

[0050] Secondly, in addition to the moisture barrier (WVTR), a specific layer providing an oxygen barrier (OTR) is necessary to bring oxygen barrier functionality to the entire structure. The first layer outside the metal coating generally provides surface planarization and moisture barrier, while the second layer outside the metal coating provides the oxygen barrier. For oxygen barrier functionality, polymers such as PVOH and BVOH (and sometimes polyurethane (PU)) have been found to provide the best results. By having an outer (before) moisture barrier of a moisture-sensitive coating such as PVOH and BVOH, the harmful effects of plasticization at high relative humidity are avoided, and high oxygen barrier and high moisture barrier (over 60%) are achieved.

[0051] Thirdly, there are economic and technical advantages to having a separate layer outside the metal coating in the structure. Specifically, oxygen barrier coating materials are expensive. When applied directly to the paper as a single layer, more coating material is needed to cover pinholes. In this case, it becomes more important that the entire amount of oxygen barrier material required is applied in one step, and the cost of the material to achieve a given barrier level increases. To solve this, a very thin first layer is applied to the paper as a "base planarization" pre-layer, and then, after drying, a second "barrier-enhancing" layer outside the metal coating is applied on top of the "pre-layer" (i.e., not directly onto the paper).

[0052] Fourth, oxygen barrier coating materials often have a low content of dry solids, which makes it easier to apply them as a thinner layer on top of another coating rather than directly onto the paper itself.

[0053] The use of BVOH as a component outside the metal coating, and BVOH (or alternatively, bio-PBS, or a blend of PBS and PBSA dispersion coatings) as a component inside the metal coating, provides compostability for the entire multilayer structure, as these two polymers, used in very small amounts, also meet the criteria for compostability in a home environment.

[0054] The metallized paper-based multilayer packaging material may also be a metallized flexible paper-based multilayer packaging material. For the purposes of the present invention, a packaging material is considered flexible if it can be bent without damage. Furthermore, for example, such a flexible material may be a material that can be bent by hand without damage. Typically, the flexible multilayer packaging material according to the present invention has a density of 140 g / m². 2 It may have the following basis weights.

[0055] Those skilled in the art can select an appropriate paper layer based, for example, on the product to be packaged, the intended shelf life, and whether the paper material is used as primary, secondary, or tertiary packaging.

[0056] The metal coating layer can be applied to the packaging material by any method known in the art.

[0057] For example, in the metallized paper-based multilayer packaging material according to the present invention, the metal coating layer may have a thickness in the range of about 20 to 500 nm, about 20 to 400 nm, or about 20 to 300 nm.

[0058] The metal coating layer may have an optical density corresponding to approximately 1 to 4, approximately 1.2 to 3.9, or approximately 1.4 to 3.8.

[0059] The metal coating layer may be, for example, an aluminum layer. The aluminum layer may be an aluminum oxide layer.

[0060] The aluminum layer may be applied to the packaging material by physical vapor deposition. For example, the aluminum layer may be applied by a vacuum deposition process. An example of a vacuum deposition process is described in Thin Solid Films, Vol. 666, November 30, 2018, pp. 6-14. Vacuum deposition is an evaporation process in which aluminum moves from the solid phase to the gas phase and then back to the solid phase, gradually building up a film thickness. Coatings produced by vacuum deposition have the advantages of good abrasion resistance, impact and temperature strength, and the ability to deposit on complex surfaces. The optical density of the aluminum layer may range from 1.4 to 3.8, which corresponds to a thickness of 30 to 200 nanometers.

[0061] Those skilled in the art can appropriately adjust the thickness of the aluminum layer depending, for example, the intended shelf life, the packaged product, and the total thickness of the packaging material. In the multilayer flexible packaging material according to the present invention, the aluminum layer may have a thickness in the range of, for example, 20 to 500 nm, 30 to 400 nm, or 50 to 200 nm.

[0062] The packaging material of the present invention may be a food product packaging material. This packaging material may be, for example, a primary packaging material, a secondary packaging material, or a tertiary packaging material. If the packaging material is a food product packaging material, the primary food product packaging material may be a food product packaging material that comes into direct contact with the actual food product. The secondary food product packaging material 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 the consumer in a single container. The tertiary food product packaging material 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.

[0063] In the packaging material of the present invention, the coating layer located inside the metal coating may include a tie layer coating located inside the metal coating. The tie layer coating may be a coating that bonds two incompatible layers. The tie layer coating located inside the metal coating used in the framework of the present invention may include an ethylene acrylic acid copolymer dispersion or another polyolefin dispersion. The polyolefin dispersion may be functionalized with methacrylic acid groups and / or carboxylic acid groups.

[0064] The appropriate thickness of the coating layer inside the metal covering can be determined by those skilled in the art depending on the intended purpose of the packaging material. For example, the coating layer inside the metal covering may be approximately 0.5 to 10 g / m². 2 , about 2~8g / m 2 , or approximately 5-7 g / m 2 It may be applied in an amount within the range of [amount].

[0065] The coating layer inside the metal coating of the packaging material according to the present invention may further comprise a layer containing a copolymer of ethyl vinyl, butyl vinyl, and / or polyvinyl alcohol. This layer may be applied on top of the tie layer coating inside the metal coating. The copolymer of ethyl vinyl, butyl vinyl, and / or polyvinyl alcohol may be mineral-filled. Typical minerals (fillers) that can be used for the purposes of the present invention include pulverized calcium carbonate, precipitated calcium carbonate, bentonite clay, and other high aspect ratio clays, talc, titanium dioxide, or combinations thereof. For example, such minerals (fillers) may have particle sizes having a length in the range of about 5 to 200 μm, a width in the range of about 5 to 200 μm, and a height in the range of about 0.1 to 100 μm. Using mineral-filled copolymers for the purposes of the present invention has the advantage of improving the wettability of the coating, increasing the flexibility of the coating and thus the barrier properties, changing the coefficient of friction, and ensuring the adhesion of the cold seal latex adhesive.

[0066] A layer containing ethyl vinyl, butyl vinyl and / or polyvinyl alcohol copolymer that can be mineral-filled may be present in an amount that can be adjusted according to the purpose of the packaging material. For example, the metallized paper-based multilayer packaging material according to the present invention has a weight of about 0.5 to 10 g / m 2 , about 1 to 8 g / m 2 , or about 2 to 5 g / m 2 of a plane or mineral-filled copolymer layer of ethyl vinyl, butyl vinyl or polyvinyl alcohol, and may have a coating inside the metal coating.

[0067] The packaging material according to the present invention may further include a heat-sealable coating as an inner layer. The inner layer faces the packaged product. The heat-sealable inner coating layer may include a propylene copolymer, a polylactic acid copolymer, vinyl acetate, or a combination thereof. This heat-sealable inner coating layer may be applied in an amount in the range of about 1 to 10 g / m 2 . Such a heat-sealable inner coating layer may have a coefficient of friction (coating-to-coating) of less than 0.5 and / or a seal start temperature exceeding 70°C.

[0068] Additionally or alternatively, the last layer of the coating may have a polarity and dispersion energy suitable for functioning as a substrate for a cold-seal latex adhesive.

[0069] The inventors have found that, using the metallized paper-based multilayer packaging material according to the present invention, which includes a primer coating outside the metal coating in an amount of about 1 to 10 g / m 2 , a metal coating in an amount corresponding to an optical density in the range of about 1 to 4, a tie layer coating inside the metal coating in an amount in the range of about 0.25 to 9.75 g / m 2 , and a layer containing a copolymer of ethyl vinyl, butyl vinyl and / or polyvinyl alcohol in an amount in the range of about 0.25 to 9.75 g / m 2 , very good results have been obtained, particularly with regard to stability under mechanical stress and maintenance of barrier properties.

[0070] In some applications of the present invention, it may be preferable that the paper layer be non-porous. If the paper layer has a porous surface, an additional surface layer may be added to cover the porous paper surface to make it air-impermeable. Such an additional surface layer may contain or consist of starch, pigment-starch, or pigment-latex formulations. The ratio of the pore volume of the paper material to the total volume is called the porosity of the paper material. For the purposes of the present invention, a paper layer is considered non-porous if it has a Gurley permeability of less than 20 mL / min (Tappi T547), a porosity of less than 40%, for example less than 30%, or less than 20%. Therefore, in one embodiment of the present invention, the paper layer is a non-porous paper layer.

[0071] It may be preferable for the paper layer to have a low surface roughness. The inventors have found that low surface roughness is beneficial to the objectives of the present invention. For example, the paper layer may have a Bendsten roughness of less than 100 mL / min. The Bendsten roughness can be determined according to ISO 8791-2:2013, which is incorporated herein by reference.

[0072] The thickness and stability of the paper used in the metallized paper-based multilayer packaging material may be adjusted based on the intended purpose of the packaging material. Typically, thicker paper may be used for tertiary packaging than for primary packaging. For example, the metallized paper-based multilayer packaging material according to the present invention has a thickness of approximately 40-120 g / m². 2 It may have a paper layer in an amount within the range of [amount].

[0073] Furthermore, the total thickness of the metallized paper-based multilayer packaging material according to the present invention may be adjusted by those skilled in the art based on the intended purpose of the packaging material.

[0074] The metallized paper-based multilayer packaging material according to the present invention can have any thickness suitable for packaging. Those skilled in the art can determine an appropriate thickness. However, typically, when the packaging material is intended for use in packaging food products, the packaging material should be as thin as possible while ensuring the safety and shelf life of the food product. For example, in the case of food packaging, it may be preferable that the metallized paper-based multilayer packaging material according to the present invention has a total thickness in the range of about 30-150 μm, 40-120 μm, or 50-100 μm.

[0075] The present inventors have obtained excellent resistance to mechanical stress with the metallized paper-based multilayer packaging material according to the present invention, and the packaging material is sequentially constructed from the outside (i.e., the outer surface of the packaging) to the inside (i.e., the side that comes into contact with the product enclosed in the packaging), Approximately 40~120g / m 2 A paper layer having a basis weight in the range of and a back surface Beck smoothness in the range of approximately 300 to 1000 seconds, A coating layer located outside the metal coating, with a density of approximately 1-10 g / m². 2 A coating layer is applied in an amount containing ethylene acrylic acid copolymer, which is located outside the metal coating, An aluminum layer having an optical density of approximately 1 to 4 and a thickness in the range of 20 to 500 nm, This is a tie-layer coating located inside the metal coating, with a density of approximately 0.5 to 10 g / m². 2 A tie layer coating located inside the metal coating is applied in an amount containing ethylene acrylic acid copolymer, A heat-seal coating located inside the metal covering, with a density of approximately 0.5 to 10 g / m². 2 A heat-seal coating, located inside the metal coating, is applied in a certain quantity and contains mineral-filled polyvinyl alcohol. It was equipped with these features.

[0076] In a preferred embodiment of the present invention, the metallized paper-based multilayer packaging material according to the present invention is recyclable in a paper recycling stream because the polymer and metal coating can be easily separated from the pulp fibers. During recycling, the aluminum layer is separated from the rest of the packaging. The fact that the subject matter of the present invention achieves the elimination of polyolefin layers such as PE or PP layers improves the separability of the packaging material of the present invention during recycling. Typically, the aluminum is separated from the rest of the packaging material during recycling in a hydra pulper. Thus, the multilayer flexible packaging material according to the present invention may be recyclable as paper and / or carton.

[0077] One advantage of the subject matter of the present invention is that excellent barrier properties are achieved despite the omission of polyolefin layers such as PE or PP layers. The metallized paper-based multilayer packaging material according to the present invention has a density of 1 g / m² 2 Less than / day (23℃, 85%RH), e.g., 0.8g / m 2 Less than / day (23℃, 85%RH), and furthermore, for example, 0.5g / m 2 A barrier with a water vapor transmission rate (WVTR) of less than / day (23°C, 85%RH), and / or approximately 3cm 3 / m 2 Less than bar / day (23℃, 50% RH), for example, about 1.5 cm 3 / m 2 Less than bar / day (23℃, 50% RH), and also, for example, about 1 cm 3 / m 2 It may have a barrier with an oxygen permeability (OTR) of less than bar / day (23°C, 50% RH). Notably, these excellent barrier properties are maintained after the packaging material of the present invention is folded 180° under a compressive load of 2 kilograms, such that the coated side of the paper is subjected to compressive stress during the folding process.

[0078] Due to these excellent barrier properties and superior mechanical resistance to bending, food can be packaged using the metallized paper-based multilayer packaging material according to the present invention.

[0079] Notably, due to its excellent barrier properties, the metallized paper-based multilayer packaging material according to the present invention can be used to package dried food products. Examples of dried food products include powders and granules, such as powders and granules reconstituted with milk or water. The dried food products may have a water content of, for example, 5% or less.

[0080] The subject matter of the present invention also extends to food packaging comprising the metallized paper-based multilayer packaging material according to the present invention.

[0081] For the purpose of presenting information to consumers and designing the product, an ink layer may be applied to the outer surface of the paper layer. The ink may be applied using, for example, water-based ink, by a web gravure printing or flexographic printing process.

[0082] It may be preferable to apply a primer between the paper layer and the ink layer. Suitable primers are known to those skilled in the art and may include, for example, a polyurethane primer.

[0083] To provide a high-quality finish to the outer surface of the packaging material according to the present invention, an overprint varnish (OPV) can be applied to the surface of the ink layer. OPVs are well known to those skilled in the art and can be selected, for example, according to the intended purpose of the packaging material of the present invention. For example, the OPV can be selected from the group consisting of conventional offset letterpress varnishes, acrylic varnishes, UV varnishes, and gravure varnishes, which can be represented by water or solvent-based polymer formulations.

[0084] 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.

[0085] 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. The present invention may also be in the following embodiments. Item 1. A metallized paper-based multilayer packaging material, wherein the layers are arranged from the outside to the inside in order: 40-120g / m 2 A paper layer having a basis weight that falls within the range, At least one dispersion coating layer located outside the metal coating, A vacuum-deposited metal coating layer, Approximately 0.5-10 g / m² inside the metal coating. 2 A dispersion coating layer of an amount in the range of, A metallized paper-based multilayer packaging material that possesses the following features. Item 2. The metallized paper-based multilayer packaging material according to item 1, wherein the coating layer located inside the metal coating comprises an ethylene acrylic acid (EEA) copolymer dispersion or another polyolefin dispersion functionalized with methacrylic acid groups and / or carboxylic acid groups, and further comprises a tie layer coating located inside the metal coating. Item 3. The metallized paper-based multilayer packaging material according to item 1 or 2, wherein the coating layer located inside the metal coating further comprises a plain or mineral-filled copolymer layer of ethyl vinyl alcohol (EVOH), butyl vinyl alcohol (BVOH), or polyvinyl alcohol (PVOH) applied on top of the tie layer coating located inside the metal coating. Item 4. The coating located inside the aforementioned metal coating is approximately 0.5 to 10 g / m². 2 A metallized paper-based multilayer packaging material according to item 3, comprising a copolymer layer of plain or mineral-filled ethyl vinyl alcohol (EVOH), butyl vinyl alcohol (BVOH), or polyvinyl alcohol (PVOH) in the range of . Item 5. Approximately 1-10 g / m² outside the metal coating 2 A primer coating in the range of , a metal coating in the range of approximately 1 to 4 (corresponding to an optical density), and approximately 0.25 to 9.75 g / m² inside the metal coating. 2 The amount of Thai layer coating in the range of approximately 0.25-9.75 g / m² 2 A metallized paper-based multilayer packaging material according to any one of items 1 to 4, comprising a layer containing an amount in the range of ethyl vinyl alcohol (EVOH), butyl vinyl alcohol (BVOH), or polyvinyl alcohol (PVOH) copolymer. Item 6. The metallized paper-based multilayer packaging material according to any one of items 1 to 5, wherein the metal coating layer has an optical density corresponding to approximately 1 to 4 and a thickness in the range of 20 to 500 nm. Item 7. A metallized paper-based multilayer packaging material according to any one of items 1 to 6, wherein the packaging material has a total thickness in the range of 30 to 150 μm. Item 8. The aforementioned packaging material Approximately 40~120g / m 2 A paper layer having a basis weight in the range of and a back surface Beck smoothness in the range of approximately 300 to 1000 seconds, A coating layer located outside the metal coating, with a density of approximately 1-10 g / m². 2 A coating layer is applied in an amount containing ethylene acrylic acid copolymer, which is located outside the metal coating, An aluminum layer having an optical density of approximately 1 to 4 and a thickness in the range of 20 to 500 nm, This is a tie-layer coating located inside the metal coating, with a density of approximately 0.5 to 10 g / m². 2 A tie layer coating located inside the metal coating is applied in an amount containing ethylene acrylic acid copolymer, A heat-seal coating located inside the metal covering, with a density of approximately 0.5 to 10 g / m². 2 A heat-seal coating, applied in an amount containing mineral-filled polyvinyl alcohol, is located inside the metal coating. A metallized paper-based multilayer packaging material comprising any of items 1 to 7. Item 9. A metallized paper-based multilayer packaging material according to any of items 1 to 8, wherein the packaging material is recyclable as paper and / or carton. Item 10. The packaging material is folded 180° under a compressive load of 2 kilograms, such that the coated side of the paper is under compressive stress while the material is folded, and then 1 g / m 2 WVTR barrier less than d (23℃, 85%RH) and / or about 3cm 3 / m 2 A metallized paper-based multilayer packaging material according to any of items 1 to 9, having an OTR barrier of less than d bar (23℃, 50%RH). Item 11. Use of metallized paper-based multilayer packaging materials as described in any of items 1-10 for packaging food products. Item 12. Food packaging comprising a metallized paper-based multilayer packaging material as described in any of items 1 to 10.

[0086] 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.

[0087] [Examples] Figure 1 shows a schematic diagram of a metallized multilayer paper structure, which consists of paper, a coating layer outside the metal coating, a metal layer, and two different coating layers inside the metal coating.

[0088] 62g / m 2 A paper substrate having a basis weight and a reverse Beck smoothness of 650 seconds was coated with a coating layer containing ethylene acrylic acid copolymer located outside the metal coating. The coating layer outside the metal coating had a density of 4.5 g / m². 2 An amount equivalent to [amount] was applied to the paper surface. An aluminum layer equivalent to an optical density of 3.5 was deposited on the coated paper. The metallized paper was then coated with 3.4 g / m². 2 The first coating layer, located outside the metal coating, is made of ethylene acrylic acid copolymer functionalized with methacrylic acid. The second coating layer is made of 2.9 g / m². 2An amount equivalent to this is applied on the first coating layer located inside the metal coating. The second coating layer located inside the metal coating consists of an ethyl vinyl alcohol copolymer filled with minerals.

[0089] The metallized multilayer paper structure was subjected to WVTR measurements at 23°C and 85%RH in both its unfolded state and after being folded 180° under a compressive load of 2 kg with the metallized side under compressive stress. The samples were also subjected to OTR measurements at 23°C and 50%RH.

[0090] The results are shown in the following table.

[0091] [Table 1]

[0092] Figure 2 shows a scanning electron microscope (SEM) image of a cross-section of a folded metallized multilayer paper. The SEM image shows that the metal-coated paper structure is undamaged after being subjected to compressive stress due to folding. The coating layer inside the metal coating exhibits a high degree of conformity to bending in the folded section, preventing damage to the metal layer during folding. As a result, the barrier resilience of the metallized multilayer paper structure is high.

Claims

1. Metallized paper-based multilayer packaging material, paper layer, A primer coating comprising at least one layer containing a polymer selected from the group consisting of ethylene acrylic acid (EAA) copolymer, polyvinyl alcohol (PVOH), butyl vinyl alcohol (BVOH), and polyurethane (PU), A vacuum-deposited metal coating layer, A tie-layer coating containing ethylene acrylic acid (EAA) copolymer, A layer containing a copolymer of ethyl vinyl alcohol (EVOH), butyl vinyl alcohol (BVOH), or polyvinyl alcohol (PVOH), filled with minerals, is provided in this order. The aforementioned paper layer is 40 to 120 g / m² ２ The basis weight falls within the range of 1 to 10 g / m², and the primer coating is 1 to 10 g / m². ２ The amount is in the range of , the amount of the metal coating layer corresponds to an optical density in the range of 1 to 4, and the amount of the tie layer coating is 0.5 to 10 g / m ２ The amount is in the range of 0.5 to 10 g / m², and the layer containing a copolymer of ethyl vinyl alcohol (EVOH), butyl vinyl alcohol (BVOH), or polyvinyl alcohol (PVOH) filled with the aforementioned mineral is 0.5 to 10 g / m². ２ It is a quantity within a range, The aforementioned metallized paper-based multilayer packaging material does not contain a polyethylene layer or a polypropylene layer, and does not contain a polymer layer formed by extrusion. Metallized paper-based multilayer packaging material.

2. The metallized paper-based multilayer packaging material according to claim 1, wherein the metal coating layer has an optical density corresponding to the range of 1 to 4 and a thickness in the range of 20 to 500 nm.

3. The metallized paper-based multilayer packaging material according to claim 1 or 2, wherein the metallized paper-based multilayer packaging material has a total thickness in the range of 30 to 150 μm.

4. The aforementioned metallized paper-based multilayer packaging material 40-120 g / m ２ A paper layer having a basis weight in the range of and a back surface Beck smoothness in the range of 300 to 1000 seconds, 1-10 g / m ２ It is applied in an amount containing an ethylene acrylic acid copolymer, and An aluminum layer having an optical density of 1 to 4 and a thickness in the range of 20 to 500 nm, 0.5–10 g / m ２ It is applied in an amount and consists of a tie layer coating containing ethylene acrylic acid copolymer, 0.5–10 g / m ２ A layer containing mineral-filled polyvinyl alcohol is applied in an amount, A metallized paper-based multilayer packaging material according to any one of claims 1 to 3, comprising the elements in this order.

5. The metallized paper-based multilayer packaging material according to any one of claims 1 to 4, wherein the metallized paper-based multilayer packaging material is recyclable as paper and / or carton.

6. The metallized paper-based multilayer packaging material is bent 180° under a compressive load of 2 kilograms so that the coated side of the paper is under compressive stress during bending, and then has a WVTR barrier of less than 1 g / m ２ d (23°C, 85% RH) and / or an OTR barrier of less than 3 cm ３ / m ２ d bar (23°C, 50% RH). The metallized paper-based multilayer packaging material according to any one of claims 1 to 5.

7. A metallized paper-based multilayer packaging material according to any one of claims 1 to 6, for use in packaging food products.

8. Food packaging comprising a metallized paper-based multilayer packaging material according to any one of claims 1 to 7.

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