Layered structure

Abstract

The layered structure comprises a paper base layer and a barrier layer. The barrier layer comprises a water-soluble polymer and a salt. The layered structure can be produced by applying the barrier layer as a foil-like element to the paper base layer.

Description

[Technical field]

[0001] The present invention relates to the field of layered structures.The present invention relates to a layered structure and a method for producing a layered structure as described in the preamble of the independent claims. [Background technology]

[0002] Currently existing packaging materials suitable for perishable foods such as coffee, cereals, cheese, meat or chocolate usually consist of multi-layer films or multi-layer architectures, e.g. PET / Alu / PE or paper / PET / Alu / PE.

[0003] Paper packaging, such as paper boxes, is known. Nevertheless, paper packaging often cannot be recycled in traditional paper recycling cycles.

[0004] For coated papers, several approaches are known, for example US Pat. No. 5,399,623, US Pat. No. 5,433,366, US Pat. No. 5,433,396, US Pat. No. 5,433,366. US Pat. No. 5,433,366 discloses a method in which a water-soluble polymer and a crosslinker are cured on the surface of a cellulose substrate, including MFC (microfibrillated cellulose). US Pat. No. 5,433,366 discloses a porous base layer with a non-uniform surface coating. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] International Publication No. 2019 / 042694 [Patent Document 2] U.S. Patent Publication No. 2019 / 177920 [Patent Document 3] International Publication No. 2006042364 [Patent Document 4] U.S. Patent Publication No. 2022 / 112663 [Patent Document 5] International Publication No. 2021 / 090192 [Patent Document 6] Chinese Patent No. 113201160 Summary of the Invention [Means for solving the problem]

[0006] It is therefore an object of the present invention to create an alternative layered structure and a method for producing the layered structure.

[0007] The present invention achieves these objects by means of a layer structure and a method for producing the layer structure according to the independent claims.

[0008] The layered structure comprises a paper base layer and a barrier layer. The barrier layer can be a coating. The barrier layer can be applied on the surface of the paper base layer. In other words, the layered structure is a system comprising at least two layers, namely, a paper base as a first layer and a barrier layer as a second layer. The first and second layers can have essentially the same area size. The layered structure can be considered as a stack of layers and can be constructed into a hierarchy.

[0009] The barrier layer comprises a water-soluble polymer and a salt. The barrier layer may contain further additives.

[0010] The salt may be present as an essentially solid material. The solid salt may be embedded in the water soluble polymer of the first layer. The salt may be incorporated into the first layer. The salt may also be partially or completely soluble in the polymer, which may contain further additives.

[0011] In an embodiment, the barrier layer is designed as a film. The film is a solid-state object and can be applied onto the paper-based layer. The barrier layer and the paper-based layer can build a laminated layered structure. The barrier layer can be a coextrusion cast film.

[0012] In an embodiment, the barrier layer does not include a synthetic surface sizing agent, which may be, for example, a styrene acrylic emulsion (SAE), ScripSet™ styrene maleic anhydride (SMA), or an alkyl ketene dimer (AKD), as disclosed, for example, in U.S. Pat. No. 5,399,633.

[0013] In an embodiment, the water-soluble polymer is cold water-soluble, which means that the water-soluble polymer is soluble in cold water. The water-soluble polymer may be soluble in water at a temperature of up to 40° C., in particular at most 38° C., in particular at most 35° C., in particular at most 30° C. Such water solubility allows the integration of the barrier layer, for example, into a paper recycling cycle, in particular paper recycling according to DIN EN13430 (as of the end of 2021).

[0014] The paper base layer can be paper, a fibrous substrate, or paperboard.

[0015] The paper may in particular be a nonwoven material, a pulp-based material. A pulp-based material is a material made from pulp, i.e. from fibers suspended in a liquid (in particular water) that is at least partially removed for production. The fibers may comprise plant fibers (in particular cellulosic fibers (from wood-based or fiber crops)), in particular at least 50% or at least 80% plant fibers or 100% plant fibers. Additionally or alternatively, the fibers may comprise mineral fibers or other natural fibers, or man-made fibers, for example on a calcium carbonate base.

[0016] The water-soluble polymer may include a polymer having multiple vinyl alcohol [CHCH(OH)] groups in the polymer chain, and in particular, the water-soluble polymer is poly(vinyl alcohol) (PVOH).

[0017] The water-soluble polymer is - poly(vinyl alcohol) (PVOH), - cellulose ether polymers, butenediol-vinyl alcohol-copolymer (BVOH), and - Ethylene-vinyl alcohol-copolymer (EVOH) It can be at least one of:

[0018] The water-soluble polymer may comprise at least one vinyl-alcohol copolymer and / or a mixture and / or blend of two or more vinyl-alcohol copolymers. The copolymers may differ in molar mass, molecular structure, e.g., branching, comonomer type, and amount, to name just a few of the parameters of variation.

[0019] The water-soluble polymer may contain additional polar comonomers. Examples include maleic acid, maleic anhydride, fumaric acid, and itaconic acid.

[0020] PVOH can be vinyl alcohol rich copolymer and / or vinyl alcohol homopolymer. Water-soluble polymers, especially polyvinyl alcohol (PVOH), can have a degree of hydrolysis of 70% to 99.9%. The degree of saponification can control the performance on oxygen permeation barrier. Higher saponification can improve oxygen permeation barrier performance, for example.

[0021] The vinyl alcohol-containing polymer may comprise monomer units with more than 75%, especially more than 90%, of OH units.

[0022] The barrier layer may be made of the following polymers, to name just a few: poly(vinyl alcohols), obtained for example by saponification of poly(vinyl ester) homopolymers or copolymers, - ethylene-vinyl alcohol-copolymer (EVOH), - Butenediol-vinyl alcohol-copolymer (BVOH) may include at least one of:

[0023] In one embodiment, at least one of the barrier layer and the layered structure is at least one of biodegradable and compostable, in particular home compostable. This means that the barrier layer is biodegradable and / or compostable. This also means that the layered structure as a whole may be biodegradable and / or compostable.

[0024] In this specification, "biodegradable" may mean biologically degradable according to European standard EN 13432 (as of the end of 2021). Additionally or alternatively, "biodegradable" may mean biologically degradable according to European standard EN 14995 (as of the end of 2021). Thus, "biodegradable" refers in particular to "biodegradable according to EN 13432 and / or according to EN 14995".

[0025] In this specification, "compostable" or "home compostable" means compostable or home compostable according to European Standard EN 13432 (as of the end of 2021) for packaging and / or according to European Standard EN 14995 (as of the end of 2021) for plastics / synthetic materials.

[0026] In one embodiment, the barrier layer and / or the layered structure may be biodegradable in at least one of soil, water, wastewater.

[0027] Biodegradable in wastewater in this context means biodegradable in wastewater according to EN ISO 9888 (end of 2021), in particular according to the Zahn-Welens test, in particular at 20°C.

[0028] In other words, insofar as reference is made in this specification to a water-soluble polymer, such a water-soluble polymer may optionally be (biodegradable) in a sewage treatment plant, in particular at 20°C, determined according to the so-called Zahn-Welens test according to EN ISO9888 (as of the end of 2021).

[0029] Biodegradation in the context of this specification means the degradation of the polymer of the barrier layer by microorganisms. Biodegradability means that the material must be more than 90% decomposed into water, carbon dioxide (CO2) and biomass in the presence of microorganisms or fungi under specific defined conditions of temperature, oxygen and humidity after a specified time.

[0030] The term compostable refers to biodegradation under certain conditions.

[0031] For a barrier layer, in particular the first and / or second layer, to be compostable, at least the following conditions must be met: - At least 90% of the organic material must be verifiably biodegradable in CO2 within six months. - The residue remaining after 3 months of composting and subsequent screening through a 2 mm mesh sieve must not exceed 10% of the original mass. - There must be no adverse effects on the composting process in general. - The resulting compost has no adverse effects on plant growth (agronomic tests) and / or ecotoxicity tests - Maximum concentrations of heavy metals (Cu, Zn, Ni, Cd, Pb, Hg, Cr, Mo, Se, As) and florins must not be exceeded.

[0032] For a barrier layer, in particular the first layer and / or the second layer, to be home compostable, at least the following conditions may be met: - Within six months in the compost pile (at approximately 30°C) at least 90% of the material must have decomposed into water, carbon dioxide and biomass. - Neither organic pollutants nor heavy metals should enter the soil. - The substance must not adversely affect the quality of the compost. - The product can be disposed of in garden compost and organic waste bins.

[0033] During composting, the barrier layer and / or layered structure may decompose. The barrier layer and / or layered structure may be formed and / or decomposed into carbon dioxide (CO2) and water (H2O) and biomass in a short period of time.

[0034] The barrier layer and / or layered structure may be industrially compostable and / or home compostable. Home compostability should not adversely affect the industrial composting process.

[0035] In addition, salt has been found to improve solubility, disintegration, and biodegradation rate, for example, for composting. The addition of salt can make the polymer home compostable, whereas without salt it can only be industrially compostable, but would not be home compostable in nature. Thus, salt content can be used to adjust the properties of the polymer composition according to the intended use and the intended recycling process.

[0036] The water-soluble polymer may be biodegradable, although this is not necessarily true for all water-soluble polymers. The water-soluble polymer of the layered structure may be biodegradable in addition to being water-soluble.

[0037] In an embodiment, all components of the layered structure are made from biodegradable materials.

[0038] In an embodiment, the layered construction comprises a biodegradable laminating adhesive.

[0039] The adhesive improves the adhesion between the paper base layer and the barrier layer.

[0040] The adhesive can be at least one of a water-based Epotal ECO, polyester-polyurethane laminating adhesive for paper-plastic laminates.

[0041] In an embodiment, the layered structure is recyclable in a paper recycling process, in particular in a paper recycling process according to DIN EN 13430 (as of the end of 2021). DIN is a European standard.

[0042] The layered structure is compatible with the requirements of paper recycling processes, which means that the layered structure can be disposed of in a paper waste bin.

[0043] In an embodiment, the barrier layer is provided on one flat surface of the paper base layer.

[0044] The paper-based layer, like paper, has two flat surfaces. In an embodiment, at least one flat surface of the paper-based layer is provided adjacent to a barrier layer. In an embodiment, one flat surface of the paper-based layer is free of a barrier layer.

[0045] In an embodiment, both planar surfaces of the paper base layer are provided adjacent to a barrier layer.

[0046] In an embodiment, a lamination adhesive is provided between the paper base layer and the barrier layer.

[0047] In embodiments, the barrier layer may comprise an additional coating, which may be provided between the paper base layer and the barrier layer and / or on the barrier layer facing away from the paper base layer.

[0048] The coating can be at least one of a plasma coating, an acrylic coating, a wax coating, and an Ormocer coating.

[0049] In an embodiment, the barrier layer comprises at least a first sublayer and a second sublayer: The first sublayer comprises a water soluble polymer and a salt and is configured to act as an oxygen barrier.

[0050] The second sublayer is configured to act as a water vapor barrier and / or a moisture barrier.

[0051] In an embodiment, the layered structure, in particular the barrier layer, in particular the second sublayer, has a water vapor barrier and / or moisture barrier of up to 15 g / m per day at 23° C. and 85% relative humidity. 2 , especially up to 10 g / m per day at 23°C and 85% relative humidity 2 , especially at 7 g / m per day at 23°C and 85% relative humidity 2 , especially up to 1 g / m per day at 23°C and 85% relative humidity 2 , especially up to 0.5 g / m per day at 23°C and 85% relative humidity 2 , especially up to 0.1 g / m per day at 23°C and 85% relative humidity 2 It could be.

[0052] The water vapor barrier and / or moisture barrier herein are determined in accordance with ISO 15106-2 (as of April 2022).

[0053] The second sublayer may include at least one of the following components: - Polyester - Aliphatic polyester - Poly(hydroxyalkanoates) (PHAs) - Polylactic acid (PLA) - Polybutylene succinate (PBS) - poly(hydroxybutyric acid) (PHB), in particular poly(3-hydroxybutyric acid), and - Copolymers containing 3-hydroxybutyric acid as a comonomer.

[0054] The second sublayer may also be water soluble. The water solubility of the second sublayer may be less than the water solubility of the first sublayer.

[0055] In one embodiment, the sublayers of the barrier layer may be at least partially separable from one another.

[0056] According to the prior art, layers of chemically similar materials are irreversibly bonded to each other. The resulting material may be called a monomaterial. Such monomaterials are difficult to impossible to recycle. In contrast, the sublayers of the present barrier layer can be separated from each other and recycled individually.

[0057] In embodiments, the barrier sublayers are separable from one another under the conditions of the recycling process, in particular the sublayers are separable at temperatures of up to 40° C., in particular at most 38° C., in particular at most 35° C., in particular at most 30° C. in an aqueous environment.

[0058] In an embodiment, the first sub-layer may be provided facing the paper base layer, with the second sub-layer facing away from the flat surface of the paper base layer.

[0059] In an embodiment, the second sub-layer may be provided facing the paper base layer, with the first sub-layer facing away from the flat surface of the paper base layer.

[0060] In an embodiment, the layered structure is a high barrier paper. The high barrier paper may provide a water vapor barrier and / or a moisture barrier.

[0061] In an embodiment, the high barrier paper has a water vapor barrier and / or moisture barrier of up to 15 g / m2 per day at 23° C. and 85% relative humidity. 2 , especially up to 10 g / m per day at 23°C and 85% relative humidity 2 , especially at 7 g / m per day at 23°C and 85% relative humidity 2 , especially up to 1 g / m per day at 23°C and 85% relative humidity 2 , especially up to 0.5 g / m per day at 23°C and 85% relative humidity 2 , especially up to 0.1 g / m per day at 23°C and 85% relative humidity 2 It could be.

[0062] In embodiments, the layered structure provides adhesion between the paper base layer and the barrier layer with sufficient peel strength that allows for complex pouch and package constructions and high packaging line speeds.

[0063] The barrier layer is more stable than the paper base layer. The peel strength can be considered as an inherent property of the paper base layer. When peeling the barrier layer from the paper base layer, the fibers of the paper base layer are pulled out of the paper base layer. The fibers break and at least partially tear. This demonstrates good adhesion of the barrier layer onto the paper base layer.

[0064] In an embodiment, the paper base layer has a thickness of 40 μm to 150 μm, in particular 50 μm to 130 μm, in particular 60 μm to 120 μm. The paper base layer may have a maximum thickness of 67 μm, in particular 50 μm. The thickness of the paper base layer may be 114 μm at an 80 gsm basis weight.

[0065] In an embodiment, the paper base layer comprises a basis weight of approximately 40 to 100 gsm. The basis weight of the paper base layer may range from 45 gsm to 80 gsm. Gsm means grams per square meter, and g / m 2 Also known as.

[0066] The paper base layer may be coated to further improve the barrier properties of the layered construction.

[0067] For example, organic-inorganic hybrid coatings such as the Ormocer coatings developed by Fraunhofer ISC in Würzburg, or related coatings offered by Nanopool GmbH in Switzerland, can be used. Due to their high crosslink density and partially inorganic nature, such coatings can enhance barrier properties even when applied as very thin layers.

[0068] In an embodiment, a plasma coating may also be applied to the paper base layer and / or the barrier layer. In some applications (especially products with very high barrier requirements), the barrier properties of the existing composite may need to be further enhanced. For this purpose, it is possible to apply an additional plasma coating to the material. The coating may be applied via a roll-to-roll process in a vacuum chamber (see S. Günther, "Der Prozess der plasmauntersttitzten Aluminiumbedampfung und die Eigenschaften dadurch hergestellter Schichten"). However, the plasma treatment may also be carried out under normal pressure. The coated films show good barrier properties and are also suitable for use in converting machines. The plasma coating may be applied in combination with an organic-inorganic hybrid coating for further improved barrier performance.

[0069] The thickness, basis weight, and tensile strength of the paper are major factors that can determine the mechanical properties, such as the stiffness, of a package such as a bag or pouch.

[0070] In an embodiment, at least one of the following conditions, in particular all of the following conditions, are met: The layered structure has a total thickness of about 130 μm. - The processability of the layered structure in the lamination / extrusion / coating line is guaranteed. - Processability on packaging machines must be ensured.

[0071] In embodiments, the layered structure provides for easy manufacturing of vinyl alcohol rich copolymer formulations without degradation, which can be prevented by adjusting the processing temperature, especially to lower temperatures.

[0072] In embodiments, the layered construction provides high barrier performance with respect to oxygen and water / moisture transmission.

[0073] In embodiments, the layered structure is recyclable and may even enhance the output of the recycle stream.

[0074] The barrier layer may have a thickness of 30 to 300 micrometers, in particular at least 30 micrometers, or at least 50 micrometers, or even at least 100 micrometers. The maximum thickness of the barrier layer may be at most 100 micrometers, or 120 micrometers, or 150 micrometers, or 200 micrometers, or 300 micrometers.

[0075] The first sublayer can be between 2 micrometers and 200 micrometers thick. The first sublayer can be at least 2 micrometers, or at least 3 micrometers, or at least 5 micrometers, or at least 10 micrometers, or at least 20 micrometers thick. The maximum thickness of the first sublayer can be at most 20 micrometers, or 40 micrometers, or 50 micrometers, or 70 micrometers, or 100 micrometers, or 200 micrometers.

[0076] The second sublayer can be between 2 micrometers and 200 micrometers thick. The second sublayer can be at least 2 micrometers, or at least 3 micrometers, or at least 5 micrometers, or at least 10 micrometers, or at least 20 micrometers thick. The maximum thickness of the first sublayer can be at most 20 micrometers, or 40 micrometers, or 50 micrometers, or 70 micrometers, or 100 micrometers, or 200 micrometers.

[0077] In an embodiment, the barrier layer is an oxygen barrier.

[0078] In an embodiment, the layered structure, in particular the barrier layer, has an oxygen transmission rate (OTR) of up to 3 cm per day at room temperature (RT, room temperature = 23 °C) and 50% relative humidity (rel. H 3 / m 2 , oxygen transmission rate is up to 1 cm per day, especially at 23°C and 50% relative humidity. 3 / m 2 , up to 0.2 cm per day at room temperature (23°C) and 50% relative humidity 3 / m 2 , especially at room temperature (23°C) and 50% relative humidity, up to 0.05 cm per day 3 / m 2 It could be.

[0079] Oxygen Transmission Rate (OTR) is the steady-state rate at which oxygen gas will permeate a film at specified conditions of temperature and relative humidity. Values ​​are expressed in metric (or SI) units as cc / m2 / 24hr, where cc is cm 3 where m is cubic centimeters, m2 is square meters, and 24hr is 24 hours in a day. The OTR in this specification is determined according to ISO15105-2 (as of April 2022). The test gas is oxygen, the carrier gas is nitrogen, and water is added to the test gas to achieve 50% relative humidity at 23°C. A sample of the layered structure is cut with a lid diameter of 105 mm to fit a test area diameter of 80 mm. The sample is mounted on the lid and clamped in the measurement device. Water vapor in nitrogen or oxygen is supplied to the sample through the lid. The measurement sensor is located on the opposite side of the sample. The sample is mounted between the test chambers at ambient atmospheric pressure. One chamber contains oxygen and the other is slowly purged by a stream of nitrogen. The concentration difference between the two chambers causes oxygen molecules to pass through the sample to the nitrogen side and be carried to the sensor, which generates a corresponding electrical signal. The signal is then analyzed and calculated to obtain the oxygen transmission rate.

[0080] In embodiments, the salt of the barrier layer comprises at least one salt of an alkali metal, alkaline earth metal, aluminum-containing salt and / or mixtures thereof, particularly NaCl, Na citrate, and the respective potassium analogs.

[0081] In an embodiment, the salt of the barrier layer comprises at least 1 wt. %, especially at least 2 wt. % salt.

[0082] In an embodiment, the salt of the barrier layer comprises from 1 to 40% by weight of the salt, especially from 2 to 30% by weight.

[0083] The salt may be present in an amount of at least 1%, or at least 2%, or at least 3%, or at least 10%, or at least 15%, or even at least 20%, or at least 25%, with a maximum amount being 55% or 40% or 35% salt. All percentages herein refer to % by weight unless otherwise specified.

[0084] The salt content of the barrier layer may also be specified in volume percent, which may be recalculated from the wt% using the density of the salt and the composition of the first layer.

[0085] The barrier layer may comprise at least 1% by volume, or at least 2% by volume, or at least 3% by volume, or at least 10% by volume, or at least 15% by volume, or even at least 20% by volume, or at least 25% by volume of salt, with a maximum amount being 55% by volume, 40% by volume, or 35% by volume.

[0086] In an embodiment, the barrier layer comprises a vinyl-alcohol copolymer that contains 1 to 25 mole % of a comonomer that is not vinyl alcohol.

[0087] In an embodiment, the barrier layer comprises an inorganic filler.

[0088] In embodiments, platelet-like nanoscale fillers distributed at least partially in the form of their primary particles may be added, enhancing their barrier performance by increasing the effective paths that diffusing molecules such as oxygen and water have to travel through the volume of the barrier layer, respectively. Nanoclays represent one example of a possible filler that provides what is also known as a tortuous path for diffusing molecules.

[0089] In embodiments, the inorganic filler may be specifically a clay mineral, especially bentonite, montmorillonite, to name just a few.

[0090] In embodiments, the inorganic filler may be, in particular, a single metal or mixed metal carbonate, in particular calcium carbonate, including precipitated calcium carbonate. In embodiments, the inorganic filler may be, in particular, silica, in particular fumed silica.

[0091] In an embodiment, the barrier layer comprises an organic filler. cellulose, cellulose derivatives such as cellulose esters, cellulose ethers, lignocelluloses and / or mixtures thereof, in particular the low molar mass oligomers thereof, starch and starch derivatives, in particular their low molar mass oligomers, - Chitin, chitosan and their derivatives - Coffee Silver Skin It can be at least one of:

[0092] In an embodiment, the barrier layer comprises a minimum of 35% by weight of one or more respective vinyl alcohol rich copolymers.

[0093] In an embodiment, the barrier layer has a maximum moisture content of 10%, for example a moisture content of 5% or less, in particular 1% or less, or 0.5% or less.

[0094] In an embodiment, the barrier layer comprises a plasticizer, which may be selected from the group consisting of polyols (oligo and polyhydroxy compounds), low molecular weight amides, in particular triols, diols, polymeric triols, polymeric diols, such as glycerin, ethylene glycol, propylene glycol, triethylene glycol, low molecular weight amides of low molecular weight polyethylene glycols, and lower molecular weight amides.

[0095] In embodiments, the plasticizer may be selected from the group consisting of dipropylene glycol, higher oligomers of ethylene glycol or propylene glycol, butylene glycol, glycerol, pentaerythritol, sorbitol, 1,4-monoanhydrohexitol, 1,4-3,6-dianhydrohexitol, and esters thereof. Preferred plasticizers are glycerin and polypropylene glycol. Glycerin or other plasticizers may be present in an amount between 2% and 25%, particularly between 5% and 18%.

[0096] Examples of suitable compositions of barrier layers can be found, for example, in WO 2014 / 155059.

[0097] In an embodiment, the barrier layer is essentially evenly distributed on the paper base layer. In other words, the barrier layer may be a uniform layer without holes. The barrier layer may essentially cover one flat surface of the paper base layer. The barrier layer may be a continuous layer.

[0098] In an embodiment, the barrier layer does not include starch.

[0099] The method for producing the layered structure, and in particular the layered structure described in this application, comprises the steps of: - providing a paper base layer; - applying a barrier layer onto the paper base layer; Includes.

[0100] In an embodiment, the barrier layer is applied to the paper base layer as a foil-like element. Thus, the barrier layer can be applied on the paper base layer at a low temperature. The barrier layer is in a solid state when applied to the paper base layer. This differs from the impregnation of the components of the barrier layer into the paper base layer at least in the application temperature. This allows working at a lower temperature and can reduce the risk of degradation of the layered structure.

[0101] In an embodiment, the barrier layer applied comprises a first sublayer and a second sublayer.

[0102] Use of the layered structure described in the present application for packaging, in particular food packaging, in particular coffee packaging.

[0103] A package comprising the layered structure described in the present application.

[0104] In an embodiment, the face of the paper-based layer adjacent the barrier layer faces towards the interior volume of the package, thereby allowing the consumer to get tactile feedback of the paper on the outside of the package, while the inside of the package still provides the barrier properties associated with the barrier layer.

[0105] The subject matter of the invention is explained in more detail in the following text with reference to exemplary embodiments illustrated in the attached drawings. [Brief description of the drawings]

[0106] [Figure 1] Shown is a layered structure 1 comprising a paper base layer and a barrier layer. [Diagram 2] 1 shows a layered structure with a coating facing away from the paper base layer. [Diagram 3] A layered structure 1 is shown with a multilayer barrier layer 3 and a coating. [Figure 4] A layered structure 1 with a multi-layer barrier layer 3 is shown. [Diagram 5] 1 shows a layered structure 1 with an alternative multi-layer barrier layer 3. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0107] The reference symbols used in the drawings and their meanings are listed in summary form in the reference symbol list. As a rule, identical parts in the drawings are provided with the same reference symbols.

[0108] Figure 1 shows a layered structure 1 comprising a paper base layer 2 and a barrier layer 3. The barrier layer 3 comprises a water-soluble polymer and a salt. The barrier layer 3 is configured to act as an oxygen permeation barrier.

[0109] The salt is essentially present as a solid material. The solid salt may be incorporated into the water-soluble polymer of the barrier layer 3.

[0110] The paper base layer 2 is a paper sheet.

[0111] A barrier layer 3 is provided on one flat surface of the paper base layer 2. The barrier layer 3 comprises an additional coating 6. The barrier layer 3 is adhered to the paper base layer 2 with an adhesive 4. The coating 6 faces the paper base layer 2 which is provided next to the adhesive 4.

[0112] The paper base layer 2 has a thickness of 50-82 micrometers. The barrier layer 3 has a thickness of 50-70 micrometers. The coating 6 has a barrier layer thickness of 3-5 micrometers. The adhesive 4 has a layer structure thickness of 1-5 micrometers.

[0113] FIG. 2 shows a similar embodiment to FIG. 1, but in which the coating 6 faces away from the paper base layer 2 and is not in contact with the adhesive 4 .

[0114] In Figure 3, the barrier layer 3 is multi-layered and comprises a first sub-layer 51 and a second sub-layer 52. The first sub-layer 51 comprises a water-soluble polymer and a salt.

[0115] The first sublayer 51 is configured to act as an oxygen permeation barrier, and the second sublayer 52 is configured to act as a water vapor and / or humidity barrier.

[0116] The first sub-layer 51 is covered on both sides by a second sub-layer 52 .

[0117] Similar to Figure 2, a coating 6 is applied to the multi-layer barrier layer 3. The coating 6 faces away from the paper base layer 2.

[0118] The multi-layer barrier layer 3 is 70 micrometers thick, with the first sub-layer 51 being 50 micrometers thick and each second sub-layer 52 being 10 micrometers thick.

[0119] Figures 4 and 5 show a layered structure 1 with a paper-based layer 2 and a barrier layer 3 which is a multi-layer barrier layer 3 that is a co-extruded cast film. The multi-layer barrier layer 3 comprises three layers, the two outer layers being essentially identical and covering a middle layer which is different from the outer layers.

[0120] The outer layer is 20 micrometers thick and the middle layer is 40 micrometers thick.

[0121] A multi-layer barrier layer 3 is applied to the paper base layer 2 .

[0122] In Fig. 4 the outer layer is the second sub-layer 52 with a water vapor and / or moisture barrier and the middle layer is the first sub-layer 51 with an oxygen permeation barrier. The second sub-layer 52 faces towards the paper base layer 2. The first sub-layer 51 does not contact the paper base layer 2.

[0123] 5 the outer layer corresponds to a first sub-layer 51 with an oxygen permeability barrier and the middle layer is a second sub-layer 52 with a vapor and / or moisture barrier. The first sub-layer 51 faces towards the paper base layer 2. The second sub-layer 52 does not contact the paper base layer 2.

[0124] The first sublayer 51 may be 12 to 15 micrometers thick, and the second sublayer 52 may be 25 micrometers thick.

Claims

1. - Paper-based layer (2), - Barrier layer (3), Equipped with, The barrier layer (3) is - Water-soluble polymers, - Salt and, Includes, The barrier layer (3) does not contain a synthetic surface sizing agent. Layered structure (1).

2. The barrier layer (3) of the layered structure (1) has a maximum capacity of 3 cm per day at 23°C and 50% relative humidity. ３ / m ２ A layered structure (1) according to claim 1, having an oxygen permeability of .

3. The layered structure (1) according to claim 1, wherein the water-soluble polymer comprises a polymer having a plurality of vinyl alcohol [CH₂CH(OH)] groups in the polymer chain.

4. The layered structure (1) according to claim 1, wherein at least one of the paper-based layer (2) and the barrier layer (3) is biodegradable and at least one of compostable.

5. The layered structure (1) according to claim 3, wherein at least one of the paper-based layer (2) and the barrier layer (3) is biodegradable and compostable.

6. The layered structure (1) according to claim 4, wherein the layered structure (1) is recyclable in a paper recycling process in accordance with EN13430 (as of the end of 2021).

7. The layered structure (1) according to claim 5, wherein the layered structure (1) is recyclable in a paper recycling process in accordance with EN13430 (as of the end of 2021).

8. The layered structure (1) according to claim 1, wherein the barrier layer (3) is provided on one flat surface of the paper base layer (2).

9. The barrier layer (3) comprises a first sublayer and a second sublayer, The first sublayer comprises the water-soluble polymer and the salt, and is configured to act as an oxygen barrier. The second sublayer is configured to act as a water vapor barrier and / or humidity barrier. The layered structure (1) according to claim 1.

10. The barrier layer (3) is subject to the following conditions: - The barrier layer (3) is an oxygen barrier. - The barrier layer (3) comprises, as the salt, an alkali metal, an alkaline earth metal, an aluminum-containing salt, and / or a mixture of the alkali metal, the alkaline earth metal, and the aluminum-containing salt. - The barrier layer (3) contains at least 1% by weight of the salt, - The barrier layer (3) contains 1 to 55% by weight of the salt, A layered structure (1) according to claim 1, satisfying at least one of the following conditions.

11. The layered structure (1) according to claim 1, wherein the barrier layer (3) is designed as a film.

12. The aforementioned paper-based layer (2) is subject to the following conditions: - The paper-based layer (2) has a thickness of 40 μm to 150 μm. - The paper-based layer (2) has a basis weight of approximately 40 to 100 gsm. A layered structure (1) according to claim 1, satisfying at least one of the following conditions.

13. The paper-based layer (2) is subject to the following conditions: - The paper-based layer (2) has a thickness of 40 μm to 150 μm. - The paper-based layer (2) has a basis weight of approximately 40 to 100 gsm. A layered structure (1) according to claim 2, satisfying at least one of the following conditions.

14. The paper-based layer (2) is subject to the following conditions: - The paper-based layer (2) has a thickness of 40 μm to 150 μm. - The paper-based layer (2) has a basis weight of approximately 40 to 100 gsm. A layered structure (1) according to claim 3, satisfying at least one of the following.

15. The paper-based layer (2) is subject to the following conditions: - The paper-based layer (2) has a thickness of 40 μm to 150 μm. - The paper-based layer (2) has a basis weight of approximately 40 to 100 gsm. A layered structure (1) according to claim 4, satisfying at least one of the following conditions.

16. The paper-based layer (2) is subject to the following conditions: - The paper-based layer (2) has a thickness of 40 μm to 150 μm. - The paper-based layer (2) has a basis weight of approximately 40 to 100 gsm. A layered structure (1) according to claim 5, satisfying at least one of the following conditions.

17. The paper-based layer (2) is subject to the following conditions: - The paper-based layer (2) has a thickness of 40 μm to 150 μm. - The paper-based layer (2) has a basis weight of approximately 40 to 100 gsm. A layered structure (1) according to claim 9, satisfying at least one of the following conditions.

18. The paper-based layer (2) is subject to the following conditions: - The paper-based layer (2) has a thickness of 40 μm to 150 μm. - The paper-based layer (2) has a basis weight of approximately 40 to 100 gsm. A layered structure (1) according to claim 10, satisfying at least one of the following.

19. The paper-based layer (2) is subject to the following conditions: - The paper-based layer (2) has a thickness of 40 μm to 150 μm. - The paper-based layer (2) has a basis weight of approximately 40 to 100 gsm. A layered structure (1) according to claim 11, satisfying at least one of the following conditions.

20. A method for manufacturing a layered structure (1) according to any one of claims 1 to 19, - A step of providing a paper-based layer (2), - The step of applying a barrier layer (3) onto the paper-based layer (2) A method that includes this.

21. The method according to claim 20, wherein the barrier layer (3) is applied to the paper-based layer (2) as a foil-like element.

22. A layered structure for food packaging, comprising the layered structure (1) described in any one of claims 1 to 19.

23. Packaging comprising a layered structure (1) according to any one of claims 1 to 19.

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