Packaging material for food with an inner barrier layer

Abstract

A packaging material for food is proposed, which packaging material comprises a first and a second paper substrate, wherein a coating is applied on at least one side of the first paper substrate, which coating forms a barrier against the penetration of oxygen, and wherein a coating is applied on at least one side of the second paper substrate, which coating forms a barrier against the penetration of water vapour, and wherein the first and the second paper substrate are connected to one another in the packaging material, with the result that the coating of the first paper substrate and the coating of the second paper substrate face one another.

Description

[0001] FOOD PACKAGING MATERIAL

[0002] WITH INTERNAL BARRIER LAYER

[0003] FIELD OF THE INVENTION

[0004] The invention relates to a packaging material for packaging food. In particular, it relates to a laminate of at least two paper substrates, each provided with a coating, which are bonded together so that the coatings face each other. This provides better protection against environmental influences. The packaging material is easy to manufacture and easily recyclable.

[0005] BACKGROUND AND STATE OF THE ART

[0006] Food packaging materials are subject to many different and sometimes contradictory requirements. A primary function of the packaging material is to protect the packaged food from environmental influences. This requires at least a certain degree of mechanical strength and chemical resistance to typical environmental influences. A second function is that the packaging material should also protect the environment from influences caused by the packaged food with which it may come into contact. For food, these two functions primarily require sufficient resistance to the penetration of fats, oils, water, water vapor, and oxygen through the packaging material.

[0007] Another important feature is good printability of the packaging material, at least on one side, since many food packaging materials are printed to identify the packaged food and its origin, and to give the packaged food an attractive appearance.

[0008] Since packaging material for food is very often used only once, it makes sense for ecological reasons if the packaging material can be recycled as easily as possible or, if it is not disposed of properly, can at least be biodegradable.

[0009] For ecological reasons, fibers from recycled paper are also used to produce food packaging materials. These fibers can be contaminated with petroleum products, so one function of the packaging material can also be to reduce the migration of contaminants from the packaging material into the food. To fulfill these functions as effectively as possible, packaging materials often consist of a laminate made up of several layers. Plastic films and aluminum foil form very effective barriers in the laminate and are well known from the state of the art. However, the packaging material is then no longer easily recyclable. For this reason, coated paper substrates are often used as packaging material. These paper substrates have complex layer structures to achieve the desired barrier effect.Especially if the coatings are biodegradable, they must be protected from environmental influences, which can usually be achieved by applying additional layers or more coating material to the paper substrate. The production of paper substrates with multiple layers is therefore complex and the use of the coating material inefficient.

[0010] There is therefore a need in the industry to have a packaging material that forms a good barrier, is recyclable and can be easily manufactured.

[0011] SUMMARY OF THE INVENTION

[0012] The present invention is based on the object of providing a packaging material for food which offers sufficiently high resistance to the penetration of water vapor and oxygen, can be easily recycled or biodegraded and can be produced relatively easily.

[0013] This object is achieved by a packaging material according to claim 1 and by a method for its production according to claim 50. Advantageous further developments are specified in the dependent claims.

[0014] The packaging material according to the invention comprises a first and a second paper substrate, wherein the first paper substrate comprises cellulose fibers, a basis weight of at least 20 g / m 2 and a maximum of 65 g / m 2 and a coating is applied to at least one side of the first paper substrate which forms a barrier against the penetration of oxygen and the oxygen permeability through the first paper substrate at a temperature of 23°C and a relative humidity of 50% is at least 0.1 cm 3 / (m 2 -d-bar) and a maximum of 5000 cm 3 / (m 2-d-bar), and wherein the second paper substrate comprises cellulose fibers, a basis weight of at least 20 g / m 2 and a maximum of 65 g / m 2 and a coating is applied to at least one side of the second paper substrate, which coating forms a barrier against the penetration of water vapor and the water vapor permeability through the second paper substrate at a temperature of 23°C and a relative humidity of 85% is at least 0.1 g / (m 2 -d) and not more than 200 g / (m 2 -d), and wherein the first and second paper substrates are bonded together in the packaging material such that the coating of the first paper substrate and the coating of the second paper substrate face each other.

[0015] The inventors have discovered that the barrier layers on the paper substrates can be effectively protected from environmental influences by not applying them to an outer side of the packaging material, as is common in the prior art, but by forming a composite of two coated paper substrates, so that the coatings are located on the inside and the paper substrates form the outer layers of the packaging material. This allows a good barrier to be formed with comparatively little coating material, eliminating the need to protect the barrier layers from environmental influences with more coating material or additional layers.

[0016] Furthermore, such a packaging material can be produced efficiently by first producing and coating the two paper substrates, for example, on one paper machine, and then bonding them together on another machine. This eliminates the need to apply multiple layers to the paper substrate on an additional device.

[0017] Furthermore, such packaging material is easily recyclable because it does not require plastic film or aluminum foil, meaning it is not necessary to separate the layers of the packaging material for recycling.

[0018] Finally, the paper substrate facing away from the packaged food can contain, for example, fibers from recycled paper, because the barrier between the two paper substrates prevents the migration of contaminants from the recycled paper fibers into the packaged food. This is another ecological advantage of the invention.

[0019] The first paper substrate has a basis weight of at least 20 g / m 2 and a maximum of 65 g / m 2 preferably at least 25 g / m 2 and a maximum of 45 g / m 2 .

[0020] The second paper substrate has a basis weight of at least 20 g / m 2 and a maximum of 65 g / m 2 preferably at least 25 g / m 2 and a maximum of 45 g / m 2 .

[0021] The basis weight can be determined according to ISO 536:2019 and refers to the basis weight of the respective paper substrate, i.e., without coating. The basis weight of the first and second paper substrates can be relatively low because the packaging material according to the invention exhibits good mechanical strength due to the composite of the paper substrates, which can only be achieved with a significantly higher basis weight for a packaging material consisting of a single coated paper substrate. This results in a further advantage of the packaging material according to the invention because material is saved.

[0022] The packaging material also remains flexible and is therefore particularly suitable for flexible packaging, unlike cardboard.

[0023] The first paper substrate comprises cellulose fibers, wherein the cellulose fibers are preferably obtained wholly or partially from coniferous woods, hardwoods, spruce, pine, fir, beech, birch, eucalyptus, hemp, flax, sisal, abaca, or esparto grass, or are formed wholly or partially by a mixture of cellulose fibers from two or more of these plants. Additionally or alternatively, the cellulose fibers of the first paper substrate may be formed wholly or partially by regenerated cellulose fibers.

[0024] In the first paper substrate, the cellulose fibers preferably constitute at least 50% and at most 100%, and more preferably at least 60% and at most 100%, and most preferably at least 60% and at most 95% of the mass of the paper substrate.

[0025] The second paper substrate comprises cellulose fibers, wherein the cellulose fibers are preferably obtained wholly or partially from coniferous woods, hardwoods, spruce, pine, fir, beech, birch, eucalyptus, hemp, flax, sisal, abaca, or esparto grass, or are formed wholly or partially by a mixture of cellulose fibers from two or more of these plants. Additionally or alternatively, the cellulose fibers of the second paper substrate may be formed wholly or partially by regenerated cellulose fibers.

[0026] In the second paper substrate, the cellulose fibers preferably constitute at least 50% and at most 100%, and more preferably at least 60% and at most 100%, and most preferably at least 60% and at most 95% of the mass of the paper substrate.

[0027] The cellulose fibers of the first or second paper substrate can be bleached or unbleached, with preferably at least 20% and at most 100%, particularly preferably at least 50% and at most 90%, of the mass of the cellulose fibers in the first or second paper substrate being unbleached. Preferably, at least 20% and at most 100%, particularly preferably at least 50% and at most 90%, of the mass of the cellulose fibers in that of the two paper substrates intended to face the packaged foodstuff are unbleached. The production of unbleached cellulose fibers is more environmentally friendly because the bleaching process is eliminated. However, the paper substrate then has a brownish color and is more difficult to print on in an aesthetically pleasing manner. Therefore, it is preferred if the paper substrate not visible from the outside, i.e., the paper substrate facing the packaged foodstuff, contains unbleached cellulose fibers.

[0028] The cellulose fibers of the first or second paper substrate can preferably be obtained from recycled paper, with at least 20% and at most 100%, particularly preferably at least 50% and at most 90%, of the mass of the cellulose fibers in the first or second paper substrate being obtained from recycled paper. Preferably, at least 20% and at most 100%, particularly preferably at least 50% and at most 90%, of the mass of the cellulose fibers in that of the two paper substrates are obtained from recycled paper that is intended to be facing away from the packaged food.

[0029] Cellulose fibers from recycled paper can contain contaminants, such as mineral oil products, that should not migrate into the food. However, the use of cellulose fibers from recycled paper offers ecological advantages; therefore, it is preferred if the paper substrate facing away from the packaged food contains cellulose fibers from recycled paper, as the coatings between the paper substrates reduce the migration of contaminants into the food.

[0030] The first paper substrate may contain filler, wherein the filler is preferably selected from the group consisting of calcium carbonate, magnesium hydroxide, aluminum hydroxide, titanium dioxide, magnesium oxide, talc, kaolin, silicates, nanocellulose and mixtures thereof.

[0031] The second paper substrate may contain filler, wherein the filler is preferably selected from the group consisting of calcium carbonate, magnesium hydroxide, aluminum hydroxide, titanium dioxide, magnesium oxide, talc, kaolin, silicates, nanocellulose and mixtures thereof.

[0032] The first paper substrate may contain filler, wherein the filler preferably constitutes at least 1% and at most 45% and more preferably at least 5% and at most 45% of the mass of the first paper substrate.

[0033] The second paper substrate may contain filler, with the filler preferably constituting at least 1% and at most 45%, and more preferably at least 5% and at most 45%, of the mass of the second paper substrate. The filler in the first or second paper substrate can increase the whiteness of the paper substrate and thus improve its visual appearance. However, the filler can also contribute to the barrier effect. Furthermore, the filler can replace some of the cellulose fibers, thus making the paper substrate more cost-effective to produce.

[0034] The first or second paper substrate may contain additional substances, such as additives or processing aids, the type and amount of which can be selected by the skilled person based on their experience. These include, for example, sizing agents such as alkyl ketene dimers (AKD) or alkenyl succinic anhydrides (ASA), wet strength agents such as epichlorohydrin, or strength-enhancing agents such as starch or cellulose derivatives, for example, carboxymethyl cellulose. Processing aids such as defoamers or dispersants may be used preferentially for the production of the paper substrate. They are not intended to remain in the paper substrate, but may be present in trace amounts.

[0035] The first paper substrate preferably has a thickness of at least 30 pm and at most 80 pm, particularly preferably at least 40 pm and at most 60 pm.

[0036] The second paper substrate preferably has a thickness of at least 30 pm and at most 80 pm, particularly preferably at least 40 pm and at most 60 pm.

[0037] The thickness can be determined according to ISO 534:2011 and refers to the thickness of the respective paper substrate, i.e. without coating.

[0038] A thickness in the preferred and particularly preferred intervals is favorable because it slows down the migration of contaminants, contributes to the barrier effect of the packaging material according to the invention against the penetration of oxygen and water vapor, and imparts to the packaging material favorable mechanical stability, which allows particularly efficient further processing of the packaging material.

[0039] The first paper substrate may preferably be calendered and has a thickness of at least 30 pm and at most 60 pm.

[0040] The second paper substrate may preferably be calendered and has a thickness of at least 30 pm and at most 60 pm.

[0041] Calendering the first or second paper substrate reduces the thickness of the paper substrate and imparts a smooth surface that is particularly suitable for coating or printing. The first paper substrate preferably has a Gurley air permeability of at least 100 s and at most 50,000 s, more preferably at least 100 s and at most 45,000 s.

[0042] The second paper substrate preferably has a Gurley air permeability of at least 100 s and at most 50,000 s, particularly preferably of at least 100 s and at most 45,000 s.

[0043] Gurley air permeability can be determined according to ISO 5636-5:2013 and refers to the air permeability of the respective paper substrate without coating in at least one of the two directions through the paper substrate.

[0044] The air permeability of the first and second paper substrates is relatively low so that the packaging material forms a good barrier against the penetration of oxygen and water vapor. By allowing air permeability at the preferred or particularly preferred intervals, the paper substrate can contribute to the barrier effect, thus requiring less coating material to achieve a given barrier effect.

[0045] A coating is applied to at least one side of the first paper substrate, forming a barrier against the penetration of oxygen. The type and quantity of the coating are selected such that the first paper substrate has an oxygen permeability of at least 0.1 cm³ at a temperature of 23°C and a relative humidity of 50%. 3 / (m 2 -d-bar) and a maximum of 5000 cm 3 / (m 2 -d-bar), preferably of at least 0.5 cm 3 / (m 2 -d-bar) and a maximum of 300 cm 3 / (m 2 -d-bar).

[0046] The oxygen permeability can be determined according to ISO 15105-1:2007, wherein the characteristic is fulfilled if the oxygen permeability in at least one direction through the first paper substrate is within the inventive or preferred interval.

[0047] The oxygen permeability of the first paper substrate allows the production of a packaging material with particularly low oxygen permeability, so that the food packaged in it has a long shelf life.

[0048] Preferably, the coating of the first paper substrate comprises a polymer selected from the group consisting of polyvinyl alcohol, ethylene-vinyl alcohol copolymer, polysaccharides, starches, pectins, glucans, and mixtures thereof. Particularly preferably, the polymer is biodegradable, and most preferably, the polymer is selected from the group consisting of polysaccharides, starches, pectins, glucans, and mixtures thereof.

[0049] Preferably, the polymer of the coating of the first paper substrate makes up at least 20% and at most 100%, more preferably at least 30% and at most 100% and most preferably at least 40% and at most 90% of the mass of the coating.

[0050] Preferably, the basis weight of the coating of the first paper substrate is at least 0.5 g / m 2 and a maximum of 10 g / m 2 , particularly preferably at least 1 g / m 2 and a maximum of 5 g / m 2 , where the basis weight is the mass of the coating relative to the area to which the coating is actually applied.

[0051] Preferably, the coating of the first paper substrate is applied to at least 50% of the area and at most 100% of the area, more preferably to at least 70% of the area and at most 100% of the area and most preferably to at least 70% and at most 95% of the area of ​​the first paper substrate.

[0052] The first paper substrate may have at least one further layer between the paper substrate and the oxygen-resistant coating. In a preferred embodiment, this further layer comprises starch and / or a filler, and the basis weight of this further layer is at least 1 g / m 2 and a maximum of 5 g / m 2 , where the weight per unit area is the mass of the additional layer relative to the surface to which the additional layer is actually applied. This makes it easier to apply a homogeneous coating that prevents oxygen penetration.

[0053] The preferred type and amount of coating on the first paper substrate achieves a favorable barrier against oxygen penetration with a small application quantity. Because the coating is located inside the packaging material, it is well protected from environmental influences, especially water, which can damage the barrier against oxygen penetration. This way, a good barrier can be achieved despite the use of relatively little coating material. A full-surface coating is preferred, but application in the packaging often does not require that the entire surface of the paper substrate is actually coated. For example, in places where the packaging material is glued to itself, no such coating is required, so that in a preferred embodiment, coating material can be saved by applying it only where it is needed as a barrier in the packaging.A coating is applied to at least one side of the second paper substrate, forming a barrier against the penetration of water vapor. The type and amount of the coating are selected so that the second paper substrate has a water vapor permeability of at least 0.1 g / (m²) at a temperature of 23°C and a relative humidity of 85%. 2 -d) and not more than 200 g / (m 2 -d), preferably of at least 0.5 g / (m 2 -d) and not more than 20 g / (m 2 -d).

[0054] The water vapor permeability can be determined according to ISO 2528:2017, wherein the characteristic is fulfilled if the water vapor permeability in at least one direction through the second paper substrate is within the inventive or preferred interval.

[0055] The water vapor permeability of the second paper substrate makes it possible to produce a packaging material with particularly favorable water vapor permeability, so that the food packaged in it does not dry out but also does not become too moist.

[0056] The coating of the second paper substrate preferably comprises a polymer, and particularly preferably the polymer is selected from the group consisting of poly(meth)acrylate, polyacrylate, polystyrene, polybutadiene, polyethylene, polyacrylonitrile, polyacrylic acid, polyhydroxyalkanoates, polylactides, waxes, paraffins, and mixtures thereof. Particularly preferably, in order to achieve a particularly good barrier against the penetration of water vapor, the polymer is selected from the group consisting of polystyrene, polybutadiene, and mixtures thereof.

[0057] The most preferred polymers are readily biodegradable and offer ecological advantages in the packaging material according to the invention and are therefore selected from the group consisting of polyhydroxyalkanoates, polylactides, food-approved waxes, paraffins and mixtures thereof.

[0058] Preferably, the polymer of the coating of the second paper substrate makes up at least 20% and at most 100%, more preferably at least 30% and at most 100% and most preferably at least 40% and at most 90% of the mass of the coating.

[0059] Preferably, the basis weight of the coating of the second paper substrate is at least 0.5 g / m 2 and a maximum of 10 g / m 2 , particularly preferably at least 1 g / m 2 and a maximum of 5 g / m 2 , where the basis weight is the mass of the coating relative to the area to which the coating is actually applied.

[0060] Preferably, the coating of the second paper substrate is applied to at least 50% of the area and at most 100% of the area, more preferably to at least 70% of the area and at most 100% of the area, and most preferably to at least 70% and at most 95% of the area of ​​the second paper substrate.

[0061] The second paper substrate may have at least one additional layer between the paper substrate and the coating to prevent water vapor penetration. In a preferred embodiment, this additional layer forms a barrier against the penetration of oils and fats or the absorption of water. The basis weight of this additional layer is preferably at least 1 g / m 2 and a maximum of 5 g / m 2, wherein the basis weight is the mass of the further layer relative to the surface to which the further layer is actually applied. Depending on the type of further layer, in this preferred embodiment the second paper substrate has on at least one side a water absorption capacity, characterized by the Cobb 3OO -value of at least 0.1 g / m 2 and a maximum of 30 g / m 2 and particularly preferably at least 0.5 g / m 2 and a maximum of 10 g / m 2 and / or the second paper substrate has on at least one side a resistance to oil penetration, characterized by the KIT level, of at least 4 and at most 12 and particularly preferably of at least 7 and at most 11.

[0062] The Cobb 3OO The value can be determined according to ISO 535:2014. The KIT level can be determined according to TAPPI T559 (2012).

[0063] This additional layer makes it easier to apply a homogeneous coating to the second paper substrate to prevent the penetration of water vapor.

[0064] The type and quantity of coating on the second paper substrate achieves a favorable barrier against the penetration of water vapor with a small application quantity.

[0065] In the packaging material according to the invention, the first paper substrate with the coating applied thereon and the second paper substrate with the coating applied thereon are bonded such that the coating of the first paper substrate and the coating of the second paper substrate face each other.

[0066] In a preferred embodiment of the packaging material according to the invention, the first and second paper substrates are bonded together by at least one of the coatings of the first and second paper substrates being heat-sealable. In this case, the first and second paper substrates can be bonded to form the packaging material according to the invention by elevated temperature and mechanical pressure, without the need for an additional adhesive. In a preferred embodiment of the packaging material according to the invention, the first and second paper substrates are bonded together by an additional layer of adhesive, which layer is located between the coating of the first and second paper substrates.In this preferred embodiment, the adhesive is preferably selected from the group consisting of heat-sealable adhesives, cold-sealable adhesives, solvent-based adhesives and water-based adhesives.

[0067] When choosing an adhesive, it is important to ensure that it is compatible with the coatings of the first and second paper substrates. This means that the adhesive allows for a good bond between the coated paper substrates without damaging the coatings. The adhesive itself can also contribute to the barrier effect of the coating of the first or second paper substrate or form an additional barrier, for example, against the penetration of grease or oil.

[0068] In this preferred embodiment, the thickness of the layer of adhesive is particularly preferably at least 1 pm and at most 10 pm and very particularly preferably at least 2 pm and at most 7 pm.

[0069] The packaging material according to the invention may have further coatings which may be applied to at least one or both sides of the packaging material.

[0070] In a preferred embodiment of the packaging material according to the invention, a coating material is applied to that side of the packaging material which is intended to form the outer side, i.e., the side facing away from the packaged food. In this preferred embodiment, the coating material preferably forms a barrier against the penetration of oxygen, water vapor, water, fats, or oils.

[0071] In a preferred embodiment of the packaging material according to the invention, a coating material is applied to the side of the packaging material intended to form the outer side, i.e., the side facing away from the packaged food. In this preferred embodiment, the coating material serves to improve printability.

[0072] In a preferred embodiment of the packaging material according to the invention, the side of the packaging material that is intended to form the outer side, i.e. that is facing away from the packaged food, is printed.

[0073] In a preferred embodiment of the packaging material according to the invention, a coating material is applied to that side of the packaging material which is intended to form the inner side, i.e., the side facing the packaged food. In this preferred embodiment, the coating material preferably forms a barrier against the penetration of oxygen, water vapor, water, fats, or oils.

[0074] In a preferred embodiment of the packaging material according to the invention, an adhesive is applied to that side of the packaging material which is intended to form the inner side, i.e. which faces the packaged food. In this preferred embodiment, the adhesive is preferably a heat-sealable adhesive, a cold-sealable adhesive, a solvent-based adhesive, or a water-based adhesive. In a particularly preferred embodiment, the adhesive is applied only to part of that side of the packaging material, wherein the adhesive is applied to at least 2% and at most 50%, very particularly preferably to at least 3% and at most 30% of the area of ​​that side. The packaging material can thus be easily bonded to itself to form a package.

[0075] In a preferred embodiment of the packaging material according to the invention, the packaging material comprises exactly two paper substrates.

[0076] In a further preferred embodiment of the packaging material according to the invention, the packaging material comprises exactly three paper substrates, wherein the third paper substrate is arranged between the first and the second paper substrate.

[0077] In a preferred embodiment of the packaging material according to the invention, the packaging material comprises any further layers, which can particularly preferably be formed by paper substrates, biodegradable films or coating materials, in particular by coating materials that form a barrier against aromas.

[0078] In a preferred embodiment of the packaging material according to the invention, no coating material intended to form a barrier against water, water vapor, oxygen, fats or oils is applied to the side of the packaging material which is intended to face away from the packaged food.

[0079] In a preferred embodiment of the packaging material according to the invention, no coating material intended to form a barrier against water, water vapor, oxygen, fats, or oils is applied to the side of the packaging material intended to face the packaged food. In a particularly preferred embodiment of the packaging material according to the invention, no coating material intended to form a barrier against water, water vapor, oxygen, fats, or oils is applied to either side of the packaging material.

[0080] The packaging material according to the invention preferably has a basis weight of at least 41 g / m 2 and a maximum of 150 g / m 2 , particularly preferably at least 45 g / m 2 and a maximum of 100 g / m 2 and most preferably at least 50 g / m 2 and a maximum of 80 g / m 2 .

[0081] The basis weight can be determined according to ISO 536:2019 and refers to the basis weight of the entire packaging material.

[0082] The relatively low basis weight of the packaging material allows material to be saved and the packaging material is flexible, so it can be easily processed further.

[0083] The packaging material according to the invention preferably has a thickness of at least 40 μm and at most 250 μm, particularly preferably at least 80 μm and at most 120 μm. The thickness can be determined according to ISO 534:2011 and refers to the thickness of the entire packaging material.

[0084] The packaging material according to the invention preferably has a tensile strength of at least 20 N / 15 mm and at most 200 N / 15 mm, and particularly preferably of at least 40 N / 15 mm and at most 80 N / 15 mm.

[0085] Tensile strength can be determined according to ISO 1924-2:2008. The tensile strength may depend on the direction in which the sample for the tensile strength test was taken from the packaging material. However, the directional dependence is small, so the characteristic is met if the tensile strength lies within the preferred or particularly preferred interval in at least one direction.

[0086] The packaging material according to the invention preferably has an elongation at break of at least 1% and at most 4%, and particularly preferably of at least 2% and at most 3%.

[0087] The elongation at break can be determined according to ISO 1924-2:2008. The elongation at break may depend on the direction in which the specimen for the elongation at break test was removed from the packaging material. However, the directional dependence is small, so the characteristic is met if the elongation at break lies within the preferred or particularly preferred interval in at least one direction.

[0088] The preferred and particularly preferred intervals for tensile strength and elongation at break of the packaging material according to the invention allow particularly good further processing into a packaging.

[0089] The packaging material according to the invention preferably contains a wet strength agent in the first and / or second paper substrate and has as a whole a wet strength of at least 3 N / 15 mm and at most 20 N / 15 mm, particularly preferably of at least 5 N / 15 mm and at most 10 N / 15 mm.

[0090] Wet strength can be determined according to ISO 3781:2011 and refers to the entire packaging material.

[0091] Wet strength is important because, on the one hand, the packaging may be exposed to water in the environment, and, on the other hand, packaged foods, especially hot foods, often release water vapor, which condenses on the inside of the packaging. In both cases, the packaging material should exhibit good tensile strength when wet. For the same reason, it is also advantageous if the packaging material absorbs little water.

[0092] The packaging material according to the invention therefore preferably has a water absorption capacity on at least one side, characterized by the Cobb 3O o-value of at least 0.1 g / m 2 and a maximum of 30 g / m 2 particularly preferably at least 0.5 g / m 2 mm and a maximum of 10 g / m 2 .

[0093] The Cobb 3O o-value can be determined according to ISO 535:2014.

[0094] The packaging material according to the invention preferably has a water vapor permeability of at least 0.1 g / (m 2 -d) and not more than 100 g / (m 2 -d), particularly preferably at least 0.5 g / (m 2 -d) and not more than 10 g / (m 2 -d) on.

[0095] The water vapor permeability can be determined according to ISO 2528:2017, whereby the characteristic is met if the water vapor permeability in at least one direction through the packaging material lies in the preferred or particularly preferred interval.

[0096] The water vapor permeability of the packaging material is a key parameter to ensure that the packaged food neither dries out nor becomes too moist. With the packaging material according to the invention, a particularly low water vapor permeability can be achieved with a small amount of coating material.

[0097] The packaging material according to the invention preferably has an oxygen permeability of at least 0.1 cm at 23°C and a relative humidity of 50% 3 / (m 2 -d-bar) and a maximum of 2000 cm 3 / (m 2 -d-bar), particularly preferably of at least 0.5 cm 3 / (m 2 -d-bar) and a maximum of 100 cm3 / (m 2 -d-bar).

[0098] The oxygen permeability can be determined according to ISO 15105-1:2007, whereby the characteristic is met if the oxygen permeability in at least one direction through the packaging material lies in the preferred or particularly preferred interval.

[0099] The oxygen permeability of the packaging material is a key parameter for ensuring the long shelf life of the packaged food. With the packaging material according to the invention, particularly low oxygen permeability can be achieved with minimal coating material.

[0100] The packaging material according to the invention can be produced by a process according to the invention which comprises the following steps AE:

[0101] A - Providing a first paper substrate comprising cellulose fibers,

[0102] B - applying a coating composition to at least one side of the first paper substrate from step A,

[0103] C - Providing a second paper substrate comprising cellulose fibers,

[0104] D - applying a coating composition to at least one side of the second paper substrate from step C,

[0105] E - Bonding the coated first paper substrate from step B to the coated second paper substrate from step D such that the sides of the first and second paper substrates to which the coating composition was applied in steps B and D face each other, wherein the first paper substrate in step A has a basis weight of at least 20 g / m 2 and a maximum of 65 g / m 2and the coating composition in step B contains a material capable of forming a barrier against the penetration of oxygen, and the oxygen permeability through the first coated paper substrate from step B at a temperature of 23°C and a relative humidity of 50% is at least 0.1 cm 3 / (m 2 -d-bar) and a maximum of 5000 cm 3 / (m 2 -d-bar) and the second paper substrate in step C has a basis weight of at least 20 g / m 2 and a maximum of 65 g / m 2 and the coating composition in step D contains a material capable of forming a barrier against the penetration of water vapor and the water vapor permeability through the second coated paper substrate from step D at a temperature of 23°C and a relative humidity of 85% of at least 0.1 g / (m 2 -d) and not more than 200 g / (m 2-d).

[0106] The first paper substrate from step A has a basis weight of at least 20 g / m 2 and a maximum of 65 g / m 2 preferably at least 25 g / m 2 and a maximum of 45 g / m 2 .

[0107] The first paper substrate from step A comprises cellulose fibers, wherein the cellulose fibers are preferably obtained wholly or partially from coniferous woods, hardwoods, spruce, pine, fir, beech, birch, eucalyptus, hemp, flax, sisal, abaca, or esparto grass, or are formed wholly or partially by a mixture of cellulose fibers from two or more of these plants. Additionally or alternatively, the cellulose fibers of the first paper substrate from step A can be formed wholly or partially by fibers from regenerated cellulose.

[0108] In the first paper substrate from step A, the cellulose fibers preferably constitute at least 50% and at most 100%, and more preferably at least 60% and at most 100%, and most preferably at least 60% and at most 95% of the mass of the first paper substrate.

[0109] The first paper substrate from step A may contain filler, wherein the filler is preferably selected from the group consisting of calcium carbonate, magnesium hydroxide, aluminum hydroxide, titanium dioxide, magnesium oxide, talc, kaolin, silicates and mixtures thereof.

[0110] The first paper substrate from step A may contain filler, wherein the filler preferably constitutes at least 5% and at most 45% and more preferably at least 25% and at most 45% of the mass of the first paper substrate.

[0111] Providing the first paper substrate in step A preferably comprises producing the paper substrate on a paper machine, more preferably on a fourdrinier paper machine. Preferably, the material of the coating composition in step B capable of forming a barrier against oxygen penetration is a polymer selected from the group consisting of polyvinyl alcohol, ethylene-vinyl alcohol copolymer, polysaccharides, starches, pectins, glucans, and mixtures thereof. More preferably, the polymer is biodegradable, and most preferably, the polymer is selected from the group consisting of polysaccharides, starches, pectins, glucans, and mixtures thereof.

[0112] Preferably, the coating composition in step B comprises a solvent, and more preferably the solvent is water.

[0113] Preferably, the material of the coating composition in step B which is capable of forming a barrier against the penetration of oxygen constitutes at least 10% and at most 100%, more preferably at least 25% and at most 100%, and most preferably at least 40% and at most 95% of the mass of the coating composition.

[0114] The coating composition is applied in step B to at least one side of the first paper substrate from step A, wherein the coating composition is preferably applied to at least 50% of the area and at most 100% of the area, more preferably to at least 70% of the area and at most 100% of the area, and most preferably to at least 70% and at most 95% of the area of ​​the first paper substrate from step A.

[0115] The application of the coating composition in step B preferably comprises application in a paper machine or in a separate application device, as well as drying the paper substrate after application of the coating composition.

[0116] Particularly preferably, the coating composition in step B is applied in a size press or a film press of a paper machine.

[0117] Particularly preferably, the drying of the coating composition in step B is carried out by drying by means of hot air, contact with heated surfaces, microwave radiation or infrared radiation.

[0118] The second paper substrate from step C has a basis weight of at least 20 g / m 2 and a maximum of 65 g / m 2 preferably at least 25 g / m 2 and a maximum of 45 g / m 2The second paper substrate from step C comprises cellulose fibers, wherein the cellulose fibers are preferably obtained wholly or partially from coniferous woods, hardwoods, spruce, pine, fir, beech, birch, eucalyptus, hemp, flax, sisal, abaca, or esparto grass, or are formed wholly or partially by a mixture of cellulose fibers from two or more of these plants. Additionally or alternatively, the cellulose fibers of the second paper substrate from step C can be formed wholly or partially by fibers of regenerated cellulose.

[0119] In the second paper substrate from step C, the cellulose fibers preferably constitute at least 50% and at most 100%, and more preferably at least 60% and at most 100%, and most preferably at least 60% and at most 95% of the mass of the second paper substrate.

[0120] The second paper substrate from step C may contain filler, wherein the filler is preferably selected from the group consisting of calcium carbonate, magnesium hydroxide, aluminum hydroxide, titanium dioxide, magnesium oxide, talc, kaolin, silicates and mixtures thereof.

[0121] The second paper substrate in step C may contain filler, wherein the filler preferably constitutes at least 5% and at most 45% and more preferably at least 25% and at most 45% of the mass of the second paper substrate.

[0122] Providing the second paper substrate in step C preferably comprises producing the paper substrate on a paper machine, particularly preferably on a fourdrinier paper machine.

[0123] Preferably, the material of the coating composition in step D is a polymer, and particularly preferably, the polymer is selected from the group consisting of poly(meth)acrylate, polyacrylate, polystyrene, polybutadiene, polyethylene, polyacrylonitrile, polyacrylic acid, polyhydroxyalkanoates, polylactides, waxes, paraffins, and mixtures thereof. Particularly preferably, the polymer is selected from the group consisting of polystyrene, polybutadiene, and mixtures thereof.

[0124] Most preferably, the polymer is selected from the group consisting of polyhydroxyalkanoates, polylactides, food-grade waxes, paraffins, and mixtures thereof. Preferably, the coating composition in step D comprises a solvent, and most preferably, the solvent is water.

[0125] Preferably, the material of the coating composition in step D constitutes at least 10% and at most 100%, more preferably at least 30% and at most 100%, and most preferably at least 40% and at most 95% of the mass of the coating composition.

[0126] The coating composition is applied in step D to at least one side of the second paper substrate from step C, wherein the coating composition is preferably applied to at least 50% of the area and at most 100% of the area, more preferably to at least 70% of the area and at most 100% of the area, and most preferably to at least 70% and at most 95% of the area of ​​the second paper substrate from step C.

[0127] The application of the coating composition in step D preferably comprises application in a paper machine or in a separate application device, as well as drying the paper substrate after application of the coating composition.

[0128] Particularly preferably, the coating composition in step D is applied in a size press or the film press of a paper machine.

[0129] Particularly preferably, the drying of the coating composition in step D is carried out by drying by means of hot air, contact with heated surfaces, microwave radiation or infrared radiation.

[0130] In a preferred embodiment of the method according to the invention, the bonding in step E comprises heat sealing the two paper substrates, wherein particularly preferably the coating composition in step B or the coating composition in step D comprises a material that enables heat sealing.

[0131] In a preferred embodiment of the method according to the invention, the bonding in step E comprises applying an adhesive to the coating from step B or step D, contacting the coated paper substrates from step B and step D, and activating the adhesive, wherein the adhesive is particularly preferably a heat-sealable adhesive. In this particularly preferred case, the activation of the adhesive consists in warming or heating it.In a preferred embodiment of the method according to the invention, the bonding in step E comprises applying an adhesive composition to the coating from step B or step D, wherein the adhesive composition contains adhesive and a solvent, contacting the coated paper substrates from step B and step D and removing the solvent from the adhesive composition, wherein the solvent is particularly preferably water or an organic solvent.

[0132] SHORT DESCRIPTION OF THE CHARACTERS

[0133] Fig. i shows a cross section through a packaging material according to the invention

[0134] Fig. 2 shows a cross section through another packaging material according to the invention, comprising a layer of adhesive for bonding the paper substrates

[0135] Fig. 3 shows a cross section through another packaging material according to the invention, comprising several additional layers and a print.

[0136] DESCRIPTION OF THE PREFERRED EMBODIMENT

[0137] The advantages of the invention will be demonstrated using exemplary packaging materials for food according to the invention.

[0138] Fig. 1 shows, by way of example, a cross-section through a packaging material according to the invention, in which a first paper substrate 11 is bonded to a second paper substrate 14. A coating 12 forming a barrier against the penetration of oxygen is applied to the first paper substrate 11, and a coating 13 forming a barrier against the penetration of water vapor is applied to the second paper substrate 14. The two paper substrates 11 and 14 can be bonded by heat sealing, with a heat-sealable material being present in the coating 12 or the coating 13.

[0139] Fig. 2 shows, by way of example, a cross-section through another packaging material according to the invention, in which a first paper substrate 21 is bonded to a second paper substrate 24. A coating 22 is applied to the first paper substrate 21, forming a barrier against the penetration of oxygen, and a coating 23 is applied to the second paper substrate 24, forming a barrier against the penetration of water vapor. A layer of adhesive 25 bonds the two paper substrates 21 and 24 such that the coatings 22 and 23 face each other. Fig.3 shows, by way of example, a cross-section through yet another packaging material according to the invention, in which a first paper substrate 31 is bonded to a second paper substrate 34, wherein a coating 32 is applied to the first paper substrate 31, forming a barrier against the penetration of oxygen, and a coating 33 is applied to the second paper substrate 34, forming a barrier against the penetration of water vapor. In addition, a layer 36 is applied between the first paper substrate 31 and the coating 32, which, for example, prepares the surface of the paper substrate 31 for the application of the coating 32. A layer 37 is applied between the second paper substrate 34 and the coating 33, which forms, for example, a barrier against the penetration of fats and oils.The paper substrates 31 and 34 are bonded together by a layer of adhesive 35 so that the coatings 32 and 33 face each other.

[0140] Furthermore, the paper substrate 31 is provided on the outside with a layer 38 to improve the quality of a print 39. The printed layer 39 is intended to form the outer surface of the packaging material. An additional layer 40 is applied to the second paper substrate 34, which layer can be heat-sealable, for example, to enable the packaging material to be bonded to itself, so that a package can be produced from the packaging material. The layer 40 is intended to face the packaged food and can, for example, be applied only to those surfaces that will later be used for bonding.

[0141] Because the coatings of the first and second paper substrates are located inside the packaging material, they are well protected and provide effective barriers against the penetration of oxygen and water vapor. Therefore, additional barrier coatings on the packaging material are unnecessary.

[0142] In one embodiment, a first paper substrate was made from cellulose fibers, with 50% of the cellulose fiber mass being pulp fibers derived from softwoods and 50% of the cellulose fiber mass being pulp fibers derived from hardwoods. The first paper substrate had a basis weight according to ISO 536:2019 of 30 g / m² before coating. 2 It was coated on one side with a composition comprising ethylene-vinyl alcohol copolymer and kaolin as a barrier material, so that after coating 4.5 g / m 2remained on the coated paper substrate. This coating served to form a barrier against oxygen penetration. Starch was applied to the other side of the paper substrate to improve printability. After coating, the tensile strength and elongation at break in the machine direction were measured according to ISO 1924-2:2008 and yielded values ​​of 50 N / 15 mm and 1.8%, respectively.

[0143] The tensile strength and elongation at break were also measured in the transverse direction according to ISO 1924-2:2008 and the values ​​obtained were 23 N / 15 mm and 6.0%, respectively.

[0144] The Cobb 3OO -value according to ISO 535:2014 was determined for the side coated with the barrier material and the result was 19 g / m 2 .

[0145] The oxygen permeability was determined according to ISO 15105-1:2007 at a temperature of 23°C and a relative humidity of 50% and a value of 62 cm 3 / (m2 -d-bar) was obtained.

[0146] The water vapor permeability was determined according to ISO 2528:2017 at 23°C and 85% relative humidity and a value of 350 g / (m 2 -d) was obtained. The side coated with the barrier material was exposed to high humidity.

[0147] The resistance to oil penetration was determined by the KIT test according to TAPPI T559 (2012) for the side coated with the barrier material and resulted in a value of 1.

[0148] A second paper substrate was made from cellulose fibers, with 40% of the cellulose fiber mass being pulp fibers derived from softwoods and 60% of the cellulose fiber mass being pulp fibers derived from hardwoods. The second paper substrate contained 7.5% kaolin as a filler, based on the mass of the paper substrate. The second paper substrate had a basis weight of 40 g / m² before coating, according to ISO 536:2019. 2 It was coated on one side with a composition comprising a polymer and a wax as a barrier material, so that after coating 4.5 g / m 2 remained on the coated paper substrate. This coating served to form a barrier against the penetration of water vapor. Starch was applied to the other side of the paper substrate to improve printability.

[0149] After coating, the tensile strength and elongation at break in the machine direction were measured according to ISO 1924-2:2008 and the values ​​obtained were 50 N / 15 mm and 2.2%, respectively.

[0150] The tensile strength and elongation at break were also measured in the transverse direction according to ISO 1924-2:2008 and the values ​​obtained were 28 N / 15 mm and 7.0%, respectively.

[0151] The Cobb 3OO -value according to ISO 535:2014 was determined for the side coated with the barrier material and the result was 8 g / m 2 The oxygen permeability was determined according to ISO 15105-1:2007 at a temperature of 23°C and a relative humidity of 50% and a value of approximately 30000 cm 3 / (m 2 -d-bar) was obtained.

[0152] The water vapor permeability was determined according to ISO 2528:2017 at 23°C and 85% relative humidity and a value of 30 g / (m 2-d) was obtained. The side coated with the barrier material was exposed to high humidity.

[0153] The resistance to oil penetration was determined by the KIT test according to TAPPI T559 (2012) for the side coated with the barrier material and resulted in a value of 7.

[0154] In order to obtain the packaging material according to the invention, the first coated paper substrate and the second coated paper substrate were bonded by means of a solvent-based heat-seal adhesive in such a way that the sides of the paper substrates coated with the barrier material faced each other and were bonded together.

[0155] The packaging material had a basis weight according to ISO 536:2019 of 81 g / m 2 on.

[0156] The Cobb 3OThe o-value of the packaging material was determined for the side of the first paper substrate according to ISO 535:2014 and the value was 26 g / m 2 .

[0157] The oxygen permeability of the packaging material was determined according to ISO 15105-1:2007 at a temperature of 23°C and a relative humidity of 50% and a value of 56 cm 3 / (m 2 -d-bar) was obtained.

[0158] The water vapor permeability of the packaging material was determined according to ISO 2528:2017 at 23°C and 85% relative humidity and a value of 28 g / (m 2 -d) was obtained. The side of the packaging material with the second paper substrate was exposed to high humidity.

[0159] The resistance of the packaging material to oil penetration was determined by the KIT test according to TAPPI T559 (2012) for the side of the packaging material with the second paper substrate and the value was 1.

[0160] It turns out that, without additional coatings to protect the barrier materials and without the use of plastic films or aluminum foils, a packaging material can be produced that is very well suited for packaging food in terms of its permeability to oxygen and water vapor, its resistance to oils and its water absorption capacity.

Claims

Claims: Packaging material for foodstuffs comprising a first and a second paper substrate, wherein the first paper substrate comprises cellulose fibers, with a basis weight of at least 20 g / m² 2 and at most 65 g / m² 2 has a coating applied to at least one side of the first paper substrate that forms a barrier against the penetration of oxygen, such that the oxygen permeability through the first paper substrate with the said coating is at least 0.1 cm at a temperature of 23°C and a relative humidity of 50%. 3 / (m 2 -d-bar) and at most 5000 cm 3 / (m 2 -d-bar), and wherein the second paper substrate comprises cellulose fibers, has a basis weight of at least 20 g / m² 2 and at most 65 g / m² 2has a coating applied to at least one side of the second paper substrate that forms a barrier against the penetration of water vapor, such that the water vapor permeability through the second paper substrate with said coating at a temperature of 23°C and a relative humidity of 85% is at least 0.1 g / (m²). 2 -d) and at most 200 g / (m²) 2 -d), and wherein the first and second paper substrates in the packaging material are bonded together such that the coating of the first paper substrate and the coating of the second paper substrate face each other. Packaging material according to claim 1, wherein the first paper substrate has a basis weight of at least 25 g / m². 2 and at most 45 g / m² 2 Packaging material according to claim 1 or 2, wherein the second paper substrate has a basis weight of at least 25 g / m². 2 and at most 45 g / m² 2comprising packaging material according to one of the preceding claims, wherein the cellulose fibers in the first paper substrate are wholly or partly derived from coniferous wood, deciduous wood, spruce, pine, fir, beech, birch, eucalyptus, hemp, flax, sisal, abaca or esparto grass, or are wholly or partly formed by a mixture of cellulose fibers from two or more of these plants, and / or wherein the cellulose fibers of the first paper substrate are wholly or partly formed by fibers of regenerated cellulose. - Packaging material according to any one of the preceding claims, wherein the cellulose fibers in the first paper substrate constitute at least 50% and at most 100%, preferably at least 60% and at most 100%, and particularly preferably at least 60% and at most 95% of the mass of the first paper substrate. Packaging material according to any one of the preceding claims, wherein the cellulose fibers in the second paper substrate are obtained wholly or partly from softwoods, hardwoods, spruce, pine, fir, beech, birch, eucalyptus, hemp, flax, sisal, abaca, or esparto grass, or are formed wholly or partly by a mixture of cellulose fibers from two or more of these plants, and / or wherein the cellulose fibers of the second paper substrate are formed wholly or partly by fibers of regenerated cellulose.Packaging material according to any one of the preceding claims, wherein the cellulose fibers in the second paper substrate constitute at least 50% and at most 100%, preferably at least 60% and at most 100%, and particularly preferably at least 60% and at most 95% of the mass of the paper substrate. Packaging material according to any one of the preceding claims, wherein at least 20% and at most 100%, preferably at least 50% and at most 90% of the mass of the cellulose fibers in the first or second paper substrate are unbleached. Packaging material according to claim 8, wherein at least 20% and at most 100%, preferably at least 50% and at most 90% of the mass of the cellulose fibers in the paper substrate intended to face the packaged foodstuff during its intended use are unbleached.Packaging material according to any of the preceding claims, wherein at least 20% and at most 100%, preferably at least 50% and at most 90%, of the mass of the cellulose fibers in the first or second paper substrate are derived from recycled paper.

1. Packaging paper according to claim 10, wherein at least 20% and at most 100%, preferably at least 50% and at most 90%, of the mass of the cellulose fibers in the paper substrate intended to be facing away from the packaged foodstuff during its intended use are derived from recycled paper. Packaging material according to any one of the preceding claims, wherein at least one of the first and the second paper substrates contains filler, the filler preferably being selected from the group consisting of calcium carbonate, magnesium hydroxide, aluminum hydroxide, titanium dioxide, magnesium oxide, talc, kaolin, silicates, nanocellulose, and mixtures thereof. Packaging material according to claim 12, wherein the filler constitutes at least 1% and at most 45%, preferably at least 5% and at most 45%, of the mass of the first or second paper substrate. Packaging material according to any one of the preceding claims, wherein the first or the second paper substrate contains a sizing agent, in particular alkyl ketene dimers (AKD) or alkenyl succinic anhydrides (ASA), a wet-strength agent, in particular epichlorohydrin, or a strength-enhancing agent, in particular starch or one or more cellulose derivatives, preferably carboxymethyl cellulose.Packaging material according to any one of the preceding claims, wherein the first and / or the second paper substrate has a thickness of at least 30 pm and at most 80 pm, preferably at least 40 pm and at most 60 pm. Packaging material according to any one of claims 1 to 14, wherein the first and / or the second paper substrate is calendered and has a thickness of at least 30 pm and at most 60 pm. Packaging material according to any one of the preceding claims, wherein the first and / or the second paper substrate has a Gurley air permeability of at least 100 s and at most 50,000 s, preferably at least 100 s and at most 45,000 s.Packaging material according to one of the preceding claims, wherein the type and quantity of the coating applied to said at least one side of the first paper substrate are selected such that the first paper substrate has an oxygen permeability of at least 0.5 cm at a temperature of 23°C and a relative humidity of 50%. 3 / (m 2 -d-bar) and at most 300 cm 3 / (m 2 -d-bar). - Packaging material according to any one of the preceding claims, wherein the coating of the first paper substrate comprises a polymer selected from the group consisting of polyvinyl alcohol, ethylene-vinyl alcohol copolymer, polysaccharides, starches, pectins, glucans, and mixtures thereof. - Packaging material according to claim 19, wherein the polymer of the coating of the first paper substrate constitutes at least 20% and at most 100%, preferably at least 30% and at most 100%, and particularly preferably at least 40% and at most 90% of the mass of the coating. - Packaging material according to any one of the preceding claims, wherein the basis weight of the coating of the first paper substrate is at least 0.5 g / m². 2 and at most 10 g / m² 2 , preferably at least 1 g / m³ 2 and at most 5 g / m² 2where the basis weight is the mass of the coating relative to the area to which the coating is actually applied. Packaging material according to any one of the preceding claims, wherein the coating of the first paper substrate is applied to at least 50% and at most 100% of the area, preferably to at least 70% and at most 100% of the area, and particularly preferably to at least 70% and at most 95% of the area of ​​the first paper substrate. Packaging material according to any one of the preceding claims, wherein the first paper substrate has at least one further layer between the paper substrate and the coating to prevent oxygen penetration. Packaging material according to claim 23, wherein said further layer comprises starch and / or a filler, and the basis weight of this further layer is at least 1 g / m². 2 and at most 5 g / m² 2is, wherein the basis weight is the mass of the additional layer in relation to the area to which the additional layer is actually applied. Packaging material according to one of the preceding claims, wherein the type and amount of coating applied to said at least one side of the second paper substrate are selected such that the second paper substrate, at a temperature of 23 °C and a relative humidity of 85%, exhibits a Water vapor permeability of at least 0.5 g / (m²) 2 -d) and at most 20 g / (m³ 2-d) has. Packaging material according to any one of the preceding claims, wherein the coating of the second paper substrate comprises a polymer, the polymer preferably being selected from the group consisting of poly(meth)acrylate, polyacrylate, polystyrene, polybutadiene, polyethylene, polyacrylonitrile, polyacrylic acid, polyhydroxyalkanoates, polylactides, waxes, paraffins, and mixtures thereof. Packaging material according to claim 26, wherein the polymer of the coating of the second paper substrate constitutes at least 20% and at most 100%, preferably at least 30% and at most 100%, and particularly preferably at least 40% and at most 90% of the mass of the coating. Packaging material according to any one of the preceding claims, wherein the basis weight of the coating of the second paper substrate is at least 0.5 g / m². 2 and a maximum of 10 g / m² 2 , preferably at least 1 g / m³ 2 and at most 5 g / m² 2where the basis weight is the mass of the coating relative to the area to which the coating is actually applied. Packaging material according to any one of the preceding claims, wherein the coating of the second paper substrate is applied to at least 50% and at most 100% of the area, preferably to at least 70% and at most 100% of the area, and particularly preferably to at least 70% and at most 95% of the area of ​​the second paper substrate. Packaging material according to any one of the preceding claims, wherein the second paper substrate has at least one further layer between the paper substrate and the coating to prevent the penetration of water vapor. Packaging material according to claim 30, wherein said further layer has a basis weight of at least 1 g / m². 2 and at most 5 g / m² 2exhibits, wherein the basis weight is the mass of the further layer in relation to the area on which the further layer is actually applied, wherein said further layer preferably forms a barrier against the penetration of oils and fats or the absorption of water, such that the second paper substrate has on at least one side a water absorption capacity characterized by the Cobb 3OO -value, of at least 0.1 g / m³ 2 and at most 30 g / m² 2 and preferably of at least 0.5 g / m 2 and at most 10 g / m² 2The packaging material according to any of the preceding claims, wherein the coating of the first and / or the second paper substrate is heat-sealable and the connection of the first and the second paper substrate is effected by heat sealing.Packaging material according to any one of claims 1 to 31, wherein the bonding of the first and second paper substrates is effected by a layer of adhesive, this layer being located between the coating of the first and the coating of the second paper substrate, the adhesive preferably being selected from the group consisting of heat-sealable adhesives, cold-sealable adhesives, solvent-based adhesives, and water-based adhesives. Packaging material according to claim 33, wherein the thickness of the adhesive layer is at least 1 pm and at most 10 pm, preferably at least 2 pm and at most 7 pm.Packaging material according to any of the preceding claims, wherein a further coating material is applied to the side of the packaging material intended to face away from the packaged foodstuff during the intended use of the packaging material, wherein the further coating material preferably forms a barrier against the penetration of oxygen, water vapor, water, fats, or oils, or wherein the further coating material preferably improves the printability of the side facing away from the packaged foodstuff. Packaging material according to any of the preceding claims, wherein the side of the packaging material intended to face away from the packaged foodstuff during the intended use of the packaging material is printed. Packaging material according to any of the preceding claims, wherein the side of the packaging material intended to face away from the packaged foodstuff during the intended use of the packaging material is printed.Packaging material according to any of the preceding claims, wherein the packaging material is intended to face the packaged food, and a further coating material is applied to that side of the packaging material which is intended to face the packaged food during its intended use, wherein the adhesive is preferably a heat-sealable adhesive, a cold-sealable adhesive, a solvent-based adhesive, or a water-based adhesive.Packaging material according to claim 38, wherein said adhesive is applied only to a portion of said side of the packaging material, the adhesive being applied to at least 2% and at most 50%, preferably at least 3% and at most 30%, of the surface of said side. Packaging material according to any one of the preceding claims, wherein the packaging material comprises exactly two paper substrates. Packaging material according to any one of claims 1 to 39, wherein the packaging material comprises exactly three paper substrates, the third paper substrate being arranged between the first and the second paper substrate. Packaging material according to any one of the preceding claims, having a basis weight of at least 41 g / m². 2 and at most 150 g / m² 2 , preferably of at least 45 g / m² 2 and at most 100 g / m² 2 and especially preferably of at least 50 g / m² 2 and at most 80 g / m² 2Packaging material according to any one of the preceding claims, having a thickness of at least 40 pm and at most 250 pm, preferably at least 80 pm and at most 120 pm. Packaging material according to any one of the preceding claims, having a tensile strength of at least 20 N / 15 mm and at most 200 N / 15 mm, and preferably at least 40 N / 15 mm and at most 80 N / 15 mm. - Packaging material according to any one of the preceding claims, having an elongation at break of at least 1.0% and at most 4.0%, and preferably at least 2.0% and at most 3.0%. Packaging material according to any one of the preceding claims, wherein the packaging material contains a wet-strength agent in the first and / or second paper substrate and as a whole has a wet strength of at least 3 N / 15 mm and at most 20 N / 15 mm, preferably at least 5 N / 15 mm and at most 10 N / 15 mm. Packaging material according to any one of the preceding claims, which has a water absorption capacity on at least one side, characterized by the Cobb test. 3OO - Value of at least 0.1 g / m³ 2 and at most 30 g / m² 2 , preferably of at least 0.5 g / m³ 2 mm and at most 10 g / m² 2exhibits. . Packaging material according to one of the preceding claims, which, at a temperature of 23 °C and a relative humidity of 85%, exhibits a water vapor permeability of at least 0.1 g / (m²). 2 -d) and at most 100 g / (m²) 2 -d), preferably of at least 0.5 g / (m³) 2 -d) and at most 10 g / (m²) 2 -d) exhibits. . Packaging material according to one of the preceding claims, which, at a temperature of 23°C and a relative humidity of 50%, has an oxygen permeability of at least 0.1 cm. 3 / (m 2 -d-bar) and at most 2000 cm 3 / (m 2 -d-bar), preferably of at least 0.5 cm 3 / (m 2 -d-bar) and at most 100 cm 3 / (m 2 -d-bar). . Method for producing a packaging material, comprising the following steps AE: A - Providing an initial paper substrate comprising cellulose fibers, B - Applying a coating composition to at least one side of the first paper substrate from step A, C - Providing a second paper substrate comprising cellulose fibers, D - Applying a coating composition to at least one side of the second paper substrate from step C, E - Joining the coated first paper substrate from step B to the coated second paper substrate from step D, such that the sides of the first and second paper substrates, onto which the coating composition was applied in steps B and D, are facing each other, wherein The first paper substrate in step A must have a basis weight of at least 20 g / m² 2 and at most 65 g / m² 2exhibits, and the coating composition in step B contains a material capable of forming a barrier against the penetration of oxygen, such that the oxygen permeability through the first coated paper substrate from step B at a temperature of 23°C and a relative humidity of 50% is at least 0.1 cm 3 / (m 2 -d-bar) and at most 5000 cm 3 / (m 2 -d-bar) is and the second paper substrate in step C has a basis weight of at least 20 g / m² 2 and at most 65 g / m² 2 exhibits, and the coating composition in step D contains a material capable of forming a barrier against the penetration of water vapor, such that the water vapor permeability through the second coated paper substrate from step D at a temperature of 23°C and a relative humidity of 85% is at least 0.1 g / (m²). 2 -d) and at most 200 g / (m²) 2-d). A method according to claim 50, wherein the packaging material is a packaging material according to any one of claims 1 to 49. A method according to claim 50 or 51, wherein providing the paper substrate in step A and / or C comprises producing the paper substrate on a paper machine, preferably on a Fourdrinier paper machine. A method according to any one of claims 50 to 52, wherein said material of the coating composition in step B, which is capable of forming a barrier against the penetration of oxygen, is a polymer, and in particular a polymer selected from the group consisting of polyvinyl alcohol, ethylene-vinyl alcohol copolymer, polysaccharides, starches, pectins, glucans and mixtures thereof, wherein the coating composition in step B preferably further comprises a solvent, wherein the solvent is preferably water.Method according to one of claims 50 to 53, wherein the material of the coating composition in step B, which is able to form a barrier against the penetration of oxygen, constitutes at least 10% and at most 100%, preferably at least 25% and at most 100% and particularly preferably at least 40% and at most 95% of the mass of the coating composition. - A method according to any one of claims 50 to 54, wherein the application of the coating composition in step B and / or D comprises application in a paper machine or in a separate application device, as well as drying the respective paper substrate after application of the respective coating composition. A method according to any one of claims 50 to 55, wherein the application of the coating composition in step B and / or D is carried out in a size press or a film press of a paper machine. A method according to any one of claims 55 or 56, wherein the drying of the coating composition in step B is carried out by drying with hot air, contact with heated surfaces, microwave radiation, or infrared radiation.A method according to any one of claims 50 to 57, wherein the material of the coating composition in step D, which is capable of forming a barrier against the penetration of water vapor, is a polymer, and in particular a polymer selected from the group consisting of poly(meth)acrylate, polyacrylate, polystyrene, polybutadiene, polyethylene, polyacrylonitrile, polyacrylic acid, polyhydroxyalkanoates, polylactides, waxes, paraffins and mixtures thereof, wherein the coating composition in step D preferably further comprises a solvent, wherein the solvent is preferably water.A method according to any one of claims 50 to 58, wherein the material of the coating composition in step D, which is capable of forming a barrier against the penetration of water vapor, comprises at least 10% and at most 100%, preferably at least 30% and at most 100%, and particularly preferably at least 40% and at most 95% of the mass of the coating composition. A method according to any one of claims 50 to 59, wherein the joining in step E comprises the heat sealing of the two paper substrates, wherein the coating composition in step B or the coating composition in step D particularly preferably comprises a material that enables heat sealing. A method according to any one of claims 50 to 59, wherein the joining in step E comprises the application of an adhesive to the coating from step B or step D, the contacting of the coated paper substrates from step B and step D, and the... Activating the adhesive comprises, wherein the adhesive is preferably a heat-sealable adhesive. A method according to any one of claims 50 to 59, wherein the bonding in step E is the The process includes applying an adhesive composition to the coating from step B or step D, wherein the adhesive composition contains adhesive and a solvent, contacting the coated paper substrates from step B and step D, and removing the solvent from the adhesive composition, wherein the solvent is preferably water or an organic solvent.

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