Barrier paper

Abstract

The present invention relates to a barrier paper comprising at least - a base paper, - at least one coating colour layer S1 applied indirectly or directly to the base paper, - at least one barrier layer B1 applied indirectly or directly to the coating colour layer S1, - a coating B2 applied indirectly or directly to the barrier layer B1.

Description

[0001] MEISSNER BOLTE

[0002] PO Box 860624

[0003] 81633 Munich

[0004] April 14, 2023

[0005] Koehler Innovation & Technology GmbH M / PFK-142-PC

[0006] Barrier paper

[0007] Description

[0008] The present invention relates to a barrier paper, a process for producing such a barrier paper, the use of the barrier paper as packaging material and a packaging comprising the barrier paper.

[0009] Packaging generally refers to the covering or (partial or complete) wrapping of an object, particularly for its protection or ease of handling. Consequently, packaging material includes the material that forms such a package.

[0010] Packaging materials can be based on paper, plastics, and / or metals, for example. The present invention relates to paper-based packaging materials.

[0011] The main requirements for packaging materials of any origin are to protect the packaged goods from external influences and to prevent leakage. To achieve this, the packaging material must meet different criteria depending on the packaged goods and the packaging process. Suitable packaging materials should not only possess barrier properties against, for example, water, grease, oxygen, or mineral oil, but also meet mechanical and process-specific requirements. Depending on the packaging system, a packaging material should possess sufficient tear strength, an appropriate friction coefficient, and flexibility. It should be sealable, particularly heat-sealable and ultrasonically sealable, or compatible with a cold-seal adhesive. It should also be printable from the outside, and it should not lose its protective effect throughout the entire conversion and packaging process.Depending on its composition and basis weight, paper can meet many mechanical requirements, but due to its physical properties and porous structure, it requires an additional coating that provides it with, for example, heat sealability or barriers.

[0012] Common paper-based, coated packaging materials often contain compounds such as polyvinylidene chloride (containing halogens), or are composites of paper and plastic films. They exhibit poor tear resistance, which can lead to running problems on packaging lines. They are often not recyclable due to excessive coating content, adhesive components, optical inhomogeneities, or the formation of so-called sticky contaminants (stickies) via the paper fiber stream. They are not sufficiently kink-resistant due to their metallic surface coating. They are not effective in humid climates due to their respective polymers. Furthermore, coatings applied via vacuum deposition generally require a particularly smooth and chemically suitable surface, which is usually created by a primer.

[0013] Polyvinyl alcohols are widely known as linear, water-soluble, biodegradable barrier coatings, including for paper. Such coatings provide good barriers against oil, grease, oxygen, solvents, and other non-polar gases, liquids, or solids. However, due to their hydrophilicity, polyvinyl alcohols exhibit very high permeability to polar compounds, such as water. This can also influence the barrier effect against non-polar migrants, as polyvinyl alcohols absorb moisture very well, swell, and thus create pathways through the barrier coating at the molecular level.

[0014] There are many attempts to reduce barrier strength at relative humidities above 50 or 60% by adding pigments, as disclosed, for example, in WO 2010 / 129032, or by crosslinking the polymer chains, as disclosed, for example, in WO 2020 / 109401 or US Pat. No. 6,444,750. However, these microscopic defects are not the only detrimental factors to the use of polyvinyl alcohols as barriers; the occurrence of macroscopic defects due to mechanical stress in packaging and converting systems also, and above all, impairs the range of applications of polyvinyl alcohols. Polyvinyl alcohol is understood to be a fully saponified polyvinyl acetate, which is a (thermoplastic) polymer of the following formula (I), which is usually synthesized by radical polymerization of vinyl acetate.

[0015] The ester groups in polyvinyl acetate are relatively easily saponified with alkali, which converts the polymer into polyvinyl alcohol and thus makes it hydrophilic and water-sensitive.

[0016] Partially saponified polyvinyl acetate is also called partially saponified polyvinyl alcohol.

[0017] In the present invention, the term partially saponified polyvinyl acetate can be used synonymously with the term partially saponified polyvinyl alcohol.

[0018] The degree of saponification indicates the proportion of ester groups that have been saponified and are now present as -OH groups. For example, a polyvinyl alcohol with a degree of saponification of 90% is a vinyl acetate polymer in which 90% of the originally present ester groups have been saponified. Therefore, this polyvinyl alcohol contains 90% OH groups and 10% ester groups. A degree of saponification of 100% contains only OH groups, since all originally present ester groups have been saponified.

[0019] In addition to the pure homopolymer, many copolymers of polyvinyl alcohol are also of great industrial importance. Copolymers are defined as all polymers that consist predominantly (>50%) of vinyl alcohol or vinyl acetate units, regardless of the number of different monomers used in the synthesis.

[0020] Such polyvinyl alcohol copolymers preferably comprise polyethylene vinyl alcohols.

[0021] In the narrower sense, saponification refers to the hydrolysis of an ester by an aqueous solution of a hydroxide, such as sodium hydroxide, or by special enzymes (esterases). Unlike acidic ester hydrolysis (the reverse reaction of esterification), these reactions are irreversible because the carboxylic acid lacks the proton required for esterification. The products of the reaction are the alcohol and the acid salt (carboxylation) from which the ester was formed. In the broader sense, any hydrolysis of an ester can be described as saponification.

[0022] In addition, metallized barrier papers are already known, for example from WO 2021 / 023661 A1, which have a low water vapor transmission rate (WVTR) of less than 5 g / m 2 / d at 38 °C and 90% relative humidity.

[0023] From the document WO 2021 / 251449 A1, a paper substrate for metal vapor deposition is known, comprising a base paper and, on the base paper, a layer containing a polyvinyl alcohol resin.

[0024] Preferably, the paper substrate comprises a further layer containing a water vapor barrier resin as a filler layer, which layer preferably contains a sheet pigment. Examples of the metal vapor deposition layer include aluminum, tin, nickel, copper, gold, platinum, silver, cobalt, chromium, and the like. Aluminum is preferred due to its high light-shielding properties and low cost.

[0025] WO 2021 / 260043 Al also describes metallizable barrier papers.

[0026] The object of the present invention is to eliminate the disadvantages of the known materials and to provide a material that is suitable as a packaging material, particularly for moisture- and oxidation-sensitive and fatty foods, and can be used for the production of packaging such as tubular bags using heat- or cold-sealing processes. Furthermore, the material should not contain barrier layers based on halogen-containing compounds. Furthermore, the material according to the invention should exhibit one or more of the following properties compared to known packaging materials:

[0027] Improved oxygen barrier, improved grease barrier, improved mineral oil barrier, improved crease resistance and flexibility of the barrier papers (equivalent to no or minimal loss of barrier properties due to bending or folding of the barrier papers or packaging made from them), recyclability via the waste paper cycle, improved heat-sealing properties, improved cold-sealing properties (compatible with the sealing medium, such as a water-based cold-seal adhesive), high tear resistance, the taste of the packaging contents is not altered, aroma-tight, the outside and inside should be printable. The material should also have an improved water vapor barrier, and the seal seam should be as moisture-resistant as possible. Finally, the material should be as economical to produce as possible.

[0028] Furthermore, it is an object of the present invention to further improve the application properties of metallized barrier papers, to find a process for producing improved barrier papers and to specify their use

[0029] This object is achieved by a barrier paper according to claim 1 having the following features:

[0030] Barrier paper comprising at least

[0031] - a base paper,

[0032] - at least one coating layer Sl applied directly or indirectly to the base paper,

[0033] - at least one barrier layer Bl applied directly or indirectly to the coating layer Sl,

[0034] - a coating B2 applied directly or indirectly to the barrier layer Bl.

[0035] Surprisingly, it has been shown that the inventive structure of such barrier papers has significantly improved their performance properties. In particular, as an environmentally friendly and sustainable replacement for plastic packaging for consumer goods and food, at least equivalent properties have now been achieved, while maintaining the excellent recycling properties of paper packaging, especially in waste paper cycles. In addition to the arrangement of the coating layer S1, its properties are of particular importance, both for the subsequent barrier layer B1 and for the properties of the barrier paper as a flexible packaging material.

[0036] It has been shown that barrier papers according to the invention can be used without any problems in conventional packaging machines for plastic packaging and that conventional packaging, such as heat-sealed tubular bags for sensitive foodstuffs such as chips and chocolate or ultrasonically welded inner liners for tobacco products, can be formed and sealed tightly enough.

[0037] Preferred embodiments of the barrier paper according to the invention are listed below:

[0038] Preferred is a barrier paper, wherein the coating layer S1 has at least one of the following properties: a) water vapor barrier b) oxygen barrier, c) mineral oil barrier, d) grease barrier e) aroma barrier, f) creasing resistance, at least one property g) grease resistance, h) sealability, i) Bekk smoothness of at least 200 Bekk seconds.

[0039] The grease resistance of a barrier paper according to the invention, according to the palm kernel fat test, has in particular at least one of the following values ​​listed under a) to f) (number of penetrations with a diameter < 1 mm / number of penetrations with a diameter > 1 mm): a) Indicator paper (AP): < 5 / < 5, preferably < 2 / < 2, in particular 0 / 0 b) Sample paper (PP): < 5 / < 5, preferably < 2 / < 2, in particular 0 / 0 c) Indicator paper (AP) - inner crease: < 5 / < 5, preferably < 2 / < 2, in particular 0 / 0 d) Sample paper (PP) - inner crease: < 5 / < 5, preferably < 2 / < 2, in particular 0 / 0 e) Indicator paper (AP) - outer crease: < 5 / < 5, preferably < 2 / < 2, in particular 0 / 0 f) Sample paper (PP) - outer crease: < 5 / < 5, preferably < 2 / < 2, in particular 0 / 0

[0040] Palm kernel fat test: Analogous to DIN 53116. For bent samples, a

[0041] A bend of 180° is created with a roller which exerts a load of 330 g / cm on the resulting bend and where the coating can be on the inside (inner bend) or outside (outer bend).

[0042] Indicator paper: Evaluation of the indicator paper mentioned in DIN 53116. Grease penetration points with a diameter (d) of < 1 mm (first value in the table) and > 1 mm (second value in the table) are counted.

[0043] Sample paper: Evaluation of the back of the paper mentioned in DIN 53116

[0044] Sample paper. This is not part of the standard, but was carried out for better differentiation.

[0045] Barrier paper wherein the coating layer S1 comprises or consists of at least one water-soluble polymer and / or a water-dispersible polymer.

[0046] Preferred is a barrier paper, wherein the at least one water-soluble

[0047] Polymer and / or the at least one water-dispersible polymer is selected from the group: a) polyvinyl alcohol, in particular partially saponified or fully saponified; b) polyvinyl alcohol copolymer, in particular copolymerized with ethylene, polyvinylamine, acrylic acid derivatives, partially saponified or fully saponified; c) modified fully or partially saponified polyvinyl alcohols or copolymers, in particular modifications with acyl, alkyl, acrylamide, silanol, diacetone, acetoacetyl, itaconic acid; d) polymer with an onset temperature determined by DSC of less than 210°C; e) acrylic-based polymers; f) polyester-based polymers; g) nitrocellulose-based polymers; h) polyvinyl acetate-based polymers.

[0048] For the purposes of this disclosure and unless otherwise stated, the onset temperature is determined by DSC according to DIN EN ISO 11357-1:2010-03 as the intersection point of the extrapolated baseline and the inflection tangent at the beginning of the melting or crystallization peak.

[0049] In particular, in the case of polymers selected from this group, the barrier layer Bl can be applied directly to the coating layer, e.g. without an intermediate layer, without adhesion promoter or pretreatment of the coating layer, e.g. by means of corona or plasma treatment.

[0050] In addition, due to the special suitability of polyvinyl alcohols, a primer is not required and a barrier layer B1, in particular a metallization, can still be applied easily and reliably.

[0051] Preferred is a barrier paper, wherein the at least one water-soluble polymer and / or the at least one water-dispersible polymer comprises an at least partially saponified polyvinyl alcohol and / or an at least partially saponified polyvinyl alcohol copolymer, each having an onset temperature determined by DSC of less than 210°C.

[0052] Preferred is a barrier paper wherein the at least one water-soluble polymer and / or the at least one water-dispersible polymer comprises a partially saponified polyvinyl alcohol having a degree of saponification of 30% to 95%, an average molecular weight of greater than 0 and less than 100,000 g / mol, and an onset temperature of less than 200°C, determined by DSC. Preferred is a barrier paper wherein the at least one water-soluble polymer and / or the at least one water-dispersible polymer comprises a partially saponified polyvinyl alcohol having a degree of saponification of greater than 95% to 100%, an average molecular weight of greater than 70,000 g / mol, and an onset temperature of less than 200°C, determined by DSC.

[0053] Preferred is a barrier paper wherein the at least one polymer comprises a partially saponified polyvinyl alcohol copolymer, preferably a partially saponified polyethylene vinyl alcohol, having a degree of saponification of 95% to 100%, an average molecular weight of greater than 60,000 g / mol and an onset temperature determined by DSC of less than 210°C.

[0054] Preferred is a barrier paper wherein the partially saponified polyvinyl alcohol and / or the partially saponified polyvinyl alcohol copolymer has a viscosity of less than 30 mPas, particularly preferably less than 20 mPas and very particularly preferably less than 15 mPas at a dry matter content of 4%.

[0055] Preferred is a barrier paper, wherein the at least one polymer comprises a mixture of water-soluble polymers and / or water-dispersible polymers previously mentioned as preferred.

[0056] Preferred is a barrier paper, wherein the coating color layer S1 has a surface tension in the range of 25 to 80 mN / m, in particular 25 to 75 mN / m. Particularly preferred ranges are 45 to 70 mN / m. The polar component of the surface tension is preferably in the range of 55 to 80%.

[0057] These surface tensions (surface energies) are particularly advantageous for the direct application of the barrier layers B1, especially during metallization ("wetting", "nucleation", growth). Conventional coatings, e.g., based on BOPP or PET, must first be treated, e.g., using corona plasma, to achieve a surface tension of at least 25 mN / m, preferably at least 35 mN / m.

[0058] Due to their high surface tension (surface energy) of approximately 50 to 70 mN / m, which in particular also includes a high polar content of approximately 70 to 80%, polyvinyl alcohols are suitable as a polymer for the coating layer SI, in particular for thin metal layers, which have a significantly lower and predominantly disperse surface tension. For example, we determined a surface tension of 27.6 mN / m with a polar content of only 3.6% for a coating layer S1 based on polyvinyl alcohol, vapor-deposited with Al using physical vapor deposition. Pure aluminum has a very high surface tension of 1200 mN / m. In reality, aluminum is coated with an oxide layer, resulting in a surface tension of approximately 40 mN / m. As a result, the metal layer (barrier layer B1) adheres not only via weak forces as on the mostly non-polar plastics (polyolefins, polyesters, acrylic copolymers, etc.), but is more firmly anchored, resulting in a high bond strength, which also proves to be an advantage when the barrier paper is bent, since the metal layer (barrier layer Bl) does not detach when bent, even with the more demanding outer bend.

[0059] There are also other preferred water-soluble, and thus polar, polymers that possess a certain oxygen barrier and are particularly suitable for the coating layer S1 but also for the coating B2. These include native and modified starches, partially degraded starches, modified soluble celluloses, nanocelluloses, and other polymeric carbohydrates such as chitosan, pullulan, curdlan, xanthan, hemicelluloses, pectins, dextran, gum arabic, karaya, guar gum, gellan gum, etc. Since many carbohydrates tend to be brittle, it is recommended to add smaller molecules that act as plasticizers in hydrophilic polymers. Examples include sugar alcohols such as glycerol and sorbitol, and poly(ethylene) glycols.Other natural polymers that can be used include proteins such as casein, cornseed protein, keratin, collagen, gelatin, whey protein, wheat gluten, rapeseed protein, soy protein, kafirin, oat avenin, rice bran protein, lupin protein, cotton proteins, or peanut proteins. Non-water-soluble polymers can also be used, especially those that do not form an oxygen barrier but still act as a barrier against fats and mineral oil vapors. These also have a high, predominantly polar surface energy.

[0060] Pigments can also be added to all of the above-mentioned polymers to improve the barrier effect. However, care must be taken to ensure that these do not significantly impair the smoothness of the respective layer. This can be achieved by selecting platelet-shaped pigments with a high form factor (aspect ratio), whose thickness is less than that of the respective layer, and whose proportion does not exceed 50% by weight of the layer. Examples of such pigments are kaolins, natural and synthetic phyllosilicates (mica), talc, and precipitated calcium carbonates.

[0061] The coating layer S1 can be applied to one side of the base paper or to both sides. Multiple coating layers S1 can be arranged on one side of the base paper, wherein, in particular, the composition, layer thickness, or basis weight can be the same or different. The coating B2 and the coating layer S1 can be the same or different, wherein, in particular, the composition, layer thickness, or basis weight can be the same or different.

[0062] Basis weight can be the same or different

[0063] Preferred is a barrier paper, wherein the barrier layer B1 comprises or consists of metals, in particular Al, Cu, Sn, Zn, Ag, Au, Ti, In, Si, metal alloys, metal oxides, in particular Al2O3, SiCh, mixed oxides or a combination thereof.

[0064] Preferred is a barrier paper, wherein the barrier layer B1 is applied by means of vacuum deposition or other known or conventional methods.

[0065] Preferred is a barrier paper, wherein the barrier layer B1 has at least one of the following features: a) optical density > 1.5 and < 6.0, b) layer thickness > 5 nm, preferably > 10 nm, particularly preferably > 15 nm, in particular 5 nm to 150 nm.

[0066] The barrier layer B1 can be applied to one side of the base paper or to both sides. Multiple barrier layers B1 can be arranged on one side of the base paper, whereby, in particular, the composition or layer thickness can be the same or different.

[0067] Preferred is a barrier paper, wherein the coating B2 comprises or consists of at least one polymer, in particular a polymer selected from the group a) polyethylene-acrylic acid copolymers, b) polyolefins c) polyvinyl alcohols, d) cellulose nitrates, e) bio-based polymers f) non-bio-based polymers g) styrene-butadiene latices, h) acrylate latices.

[0068] Preferred is a barrier paper, wherein the coating B2 has at least one of the following properties: a) protection of the barrier layer B1 against external influences, in particular mechanical influences such as kinking in packaging systems, e.g. when closing the packaging (e.g. sealing seams) or rubbing or chemical influences, b) sealable, in particular heat-, ultrasonically, cold-sealable, c) grease resistance, d) water resistance, e) moisture resistance, f) printability, g) additional barrier property, h) optimization of the existing barrier properties.

[0069] Preferred is a barrier paper, wherein the barrier paper has at least one of the following features: a) WVTR < 5 g / m 2 / d at 23°C and 50% relative humidity b) WVTR internal bend < 5 g / m 2 / d at 23°C and 50% relative humidity c) WVTR external bend < 5 g / m 2 / d at 23°C and 50% relative humidity d) WVTR < 15 g / m 2 / d at 38°C and 90% relative humidity e) WVTR internal bend < 15 g / m 2 / d at 38°C and 90% relative humidity f) WVTR external bend < 15 g / m 2 / d at 38°C and 90% relative humidity g) OTR < 10 cm 3 / m 2 / d at 23°C and 50% relative humidity h) OTR internal bend < 10 cm 3 / m 2 / d at 23°C and 50% relative humidity i) OTR outer bend < 10 cm 3 / m 2 / d at 23°C and 50% relative humidity j) kink resistance of at least one barrier property, in particular in the area of ​​the inner kick and / or the outer kick, k) residual moisture of at least 2.5% by weight, in particular at least 3.0% by weight based on the total weight of the barrier paper.

[0070] Preferred is a barrier paper, wherein the barrier paper has at least one of the following features: a) WVTR < 3 g / m 2 / d at 23°C and 50% relative humidity b) WVTR internal bend < 3 g / m 2 / d at 23°C and 50% relative humidity c) WVTR external bend < 3 g / m 2 / d at 23°C and 50% relative humidity d) WVTR < 10 g / m 2 / d at 38°C and 90% relative humidity e) WVTR internal bend < 10 g / m 2 / d at 38°C and 90% relative humidity f) WVTR external bend < 10 g / m 2 / d at 38°C and 90% relative humidity g) OTR < 5 10 cm 3 / m 2 / d at 23°C and 50% relative humidity h) OTR inner bend < 5 cm 3 / m 2 / d at 23°C and 50% relative humidity i) OTR outer bend < 5 cm 3 / m 2 / d at 23°C and 50% relative humidity j) kink resistance of at least one barrier property, in particular in the area of ​​the inner kick and / or the outer kick, k) residual moisture of at least 2.5% by weight, in particular at least 3.0% by weight based on the total weight of the barrier paper.

[0071] By crease resistance of at least one barrier property, in particular in the area of ​​the inner kick or outer kick, is meant that the at least one barrier property deviates from the barrier property of the barrier paper by less than a maximum of 100%, preferably a maximum of 75%, particularly preferably a maximum of 50%, and most particularly preferably a maximum of 25%, in the area of ​​the kick or in the kick. For example, if the measured value for a barrier paper according to the invention is WVTR = 1.5 g / m 2 / d (at 38°C and 90% relative humidity), the measured value for WVTR is in the area of ​​the inner bend (ie the inner bend is in the measuring area) or directly at the inner bend in the range of 0 to 3 g / m 2 / d (less than maximum 100%).

[0072] Preferred is a barrier paper, wherein the coating layer Sl, the barrier coating Bl and the barrier coating B2 are removable in the waste paper cycle.

[0073] A barrier paper is preferred, whereby after processing the

[0074] Barrier paper according to INGEDE Method 11, the following scores are achieved according to the Assessment of Printed Product Recyclability, Deinkability Score: a) Brightness Y maximum 35 points, b) Color coefficient a* in the CIELAB system maximum 20 points, c) Dirt points A in the two different size classes A50 maximum 15 points and A250 maximum 10 points, d) Degree of dye removal (printing ink removal) IE maximum 10 points and e) Filtrate darkening AY maximum 10 points, whereby the sum of all points is in the range from 0 to 100, preferably in the range from 51 to 70, particularly preferably in the range from 71 to 100, and / or preferably no individual point value is negative.

[0075] Preferred is a barrier paper, wherein a primer comprising at least one inorganic pigment and a polymeric binder is present between the base paper and the coating color layer S1, wherein the inorganic pigment is preferably platelet-shaped and preferably comprises a talc, a precipitated calcium carbonate, a silicate, preferably a layered silicate or kaolin and / or wherein the polymeric binder comprises a polymeric binder based on a polyacrylate.

[0076] The primer preferably comprises at least one polymeric binder and at least one organic and / or one inorganic pigment and optionally further coating color components in the usual amounts.

[0077] Pigments: phyllosilicates.

[0078] Polymeric binders: styrene-acrylate latex, butadiene latex. Rheology modifiers such as acrylate-based thickeners and / or zirconium-based crosslinkers.

[0079] Preferred is a barrier paper, wherein the basis weight of the coating layer S1 and the coating B2 is in the range from 4 to 20 g / m 2 , preferably from 8 to 15 g / m 2 , based on the dried final product (Lutro).

[0080] Preferred is a barrier paper, which is free of halogen-containing compounds except for unavoidable traces.

[0081] Preferred is a barrier paper, the base paper having a basis weight of 20 to 120 g / m 2 , preferably from 40 to 100 g / m 2 , is preferred. A barrier paper is preferred, wherein the base paper has a long fiber content of 10 to 80% and a short fiber content of 20 to 90% by weight, wherein a long fiber is a fiber with a fiber length of 2.6 to 4.4 mm and a short fiber is a fiber with a fiber length of 0.7 to 2.2 mm.

[0082] Preferred is a barrier paper, wherein the base paper comprises or consists of 100% virgin fiber pulp and up to 100% recycled fibers or comprises or consists of mixtures of both.

[0083] Preferred is a barrier paper, the base paper comprising up to 90% recycled fibers.

[0084] The base paper preferably has a starch coating or starch-containing coating on one or both sides, in particular to improve printability.

[0085] The present invention further relates to a process for producing a barrier paper, which is characterized in that an aqueous suspension comprising the starting materials of the coating color layer S1 is applied directly or indirectly to a base paper, wherein the aqueous application suspension has a solids content of 5 to 50% by weight, preferably of 10 to 30% by weight, and is applied by a curtain coating process, preferably by a double curtain coating process (double curtain coating) at an operating speed of the coating system of at least 200 m / min.

[0086] Preferably, after the usual drying of the coating layer S1, the barrier paper is remoistened with a dampening system or a steam box in order to achieve a moisture content based on the total mass of between 2.5 and 7%, preferably between 3.5 and 5%, particularly preferably between 4 and 4.5%. This is ideal for the barrier coating B1, in particular if it is a metallization, in order to maintain the flexibility of the coating layer S1 and the base paper, but also to prevent too much moisture from entering a coating chamber (e.g. vacuum chamber). Preferably, after the usual remoistening of the coating layer S1, the barrier paper is remoistened with a dampening system or a steam box in order to achieve a moisture content based on the total mass of between 2.5 and 7%, preferably between 3.5 and 5%, particularly preferably between 4 and 4.5%.

[0087] Preferably, after the usual re-moistening of the coating layer S1, the surface of the coating layer S1 is smoothed / satinized with one or more roller polishing units, calenders or shoe calenders to a smoothness value of at least 200 Bekk seconds, in particular 500 Bekk seconds.

[0088] Preferably after the usual smoothing of the coating layer S1, the barrier layer Bl is applied directly or indirectly to the coating layer S1 by means of conventional methods.

[0089] The coating B2 can then be applied directly or indirectly to the barrier layer Bl using conventional methods and, if necessary, dried using conventional methods.

[0090] Following coating B2, a full-surface or partial sealing varnish, in particular a hot-seal varnish or cold-seal varnish, can be applied directly or indirectly to the coating B2 and / or to the opposite outer side of the barrier paper using conventional methods and dried directly or indirectly using conventional methods.

[0091] Following coating B2, a full-surface or partial print can be applied directly or indirectly to coating B2 or to the opposite outer side to make the packaging recognizable and to provide information using conventional methods and dried directly or indirectly using conventional methods.

[0092] The present invention also relates to the use of the barrier paper according to the invention or of the barrier paper produced according to the process as packaging material for foodstuffs, consumer goods, tobacco products or as a component of packaging material, in particular of packaging material based on cardboard or paperboard, in particular as packaging material for foodstuffs, in particular for sausage, cheese, coffee, muesli bars, chocolate, chocolate-containing products, or chips.

[0093] The present invention also relates to a packaging comprising a barrier paper according to the invention or a barrier paper produced according to the method, wherein the packaging is preferably a cold-sealed packaging, a heat-sealed packaging, an ultrasonically sealed packaging, in particular a tubular bag packaging.

[0094] In a preferred embodiment, the coated side (inner side) of the packaging is directed inward (inside of the packaging) and the outer side is directed outward. This makes it possible to package moist and / or greasy products in particular. In this case, the outer side is printed and the inner side is sealed to the inner side (A:A sealing) and / or the inner side is sealed to the outer side (A:B sealing).

[0095] In particular, the packaging design consists of a coating facing outward (outside of the packaging) and the outer side facing inward. This makes it possible to protect particularly moisture-sensitive packaged goods from drying out. In this case, the inner side is printed and the outer side is sealed to the outer side (A:A sealing) and / or the outer side is sealed to the inner side (A:B sealing).

[0096] The quality of the barrier paper according to the invention, in particular with regard to its resistance to creasing, can be determined, among other things, by dynamic mechanical thermal analysis (DMTA).

[0097] Dynamic mechanical thermal analysis (DMTA) / DMTA measurements:

[0098] Dynamic mechanical thermal analysis (DMTA) is a method for measuring the viscoelastic properties of a polymer or material system. By applying cyclic sinusoidal stress / strain forces to induce deformation without destruction, a phase angle can be calculated by shifting the material's sinusoidal response. The phase angle of a viscoelastic material is defined as a value greater than 0° (a purely elastic material) and less than 90° (a purely viscous material). The tan value is therefore a value that represents the relationship between the elastic modulus (G') and the viscous modulus (G") – given by the following equation:

[0099] G' (elastic-storage modulus) tanö = -

[0100] G” (viscous loss modulus)

[0101] The tan value (a quantified loss damping effect), elastic modulus (G'), and viscosity modulus (G") of packaging materials that retain their barrier properties after folding can be compared with packaging materials that lose their intended barrier properties. We obtained a tan for a material that retains its barrier properties after folding and a tan for a material that loses its barrier properties after folding. The tan (loss factor) is within the acceptable range for viscoelastic materials (tan = 0 - 1.0).

[0102] The barrier paper according to the invention is further preferably characterized in that the values ​​for the loss factor tan Delta measured by means of dynamic mechanical thermal analysis (DMTA) of the barrier paper as a function of temperature pass through a maximum at temperature Tg and a first inflection point at temperature Tw with increasing temperature.

[0103] Preferably, the temperature Tg is lower than the temperature Tw.

[0104] Barrier papers which have measured values ​​for the loss factor tan Delta with increasing temperature, a maximum at temperature Tg and a first inflection point at temperature Tw, preferably where Tg is lower than Tw, are characterized in that they advantageously retain the barrier properties after bending.

[0105] Preferably, the difference between tan delta at temperature Tg and tan delta at temperature Tw is > 0.013, preferably > 0.014, and particularly preferably > 0.015. Particularly with such values ​​for the difference between tan delta at temperature Tg and tan delta at temperature Tw, the barrier properties are advantageously retained after the bending.

[0106] As already explained above, the onset temperature is determined using DSC as follows:

[0107] The (extrapolated) onset temperature (according to DIN EN ISO 11357-1:2010-03) is the intersection point of the extrapolated baseline and the inflection tangent at the beginning of the melting or crystallization peak in a DSC measurement. The baseline and the inflection tangent are determined from the temperature-dependent heat flow signal. For pure and homogeneous materials, the initial temperature can be specified as the melting temperature. In contrast to the peak temperature, the onset temperature is less dependent on the heating rate and sample mass. Furthermore, onset temperatures are commonly used for temperature calibration of a DSC.

[0108] The barrier paper according to the invention is particularly distinguished by its suitability as a packaging material for moisture- and oxidation-sensitive, as well as greasy, objects, especially foodstuffs, and its use in the production of bags by means of hot- or cold-sealing applications. A water-based cold-sealing adhesive can be used for the cold-sealing application. Furthermore, no layers or barrier layers based on halogen-containing compounds are required.

[0109] Partially saponified polyvinyl alcohols have the advantage over fully saponified polyvinyl alcohols (PVOH) or polyethylene vinyl alcohols (EVOH) in that they have a significantly lower optimal sealing temperature during the heat-sealing process. This does not negatively affect the seal strength. Furthermore, partially saponified polyvinyl alcohols have a slightly lower viscosity, with otherwise identical concentrations. A high viscosity is considered disadvantageous, as the PVOH solution must be more diluted, requiring a larger amount of water to be dried during the coating process. This not only consumes energy and therefore requires a coating system with a higher drying capacity, but can also be technically difficult to implement depending on the desired application weight. Furthermore, the diffusion of water molecules at high viscosities, and thus the drying process itself, is slowed.Furthermore, this can lead to the accumulation of gaseous water in the coating, which leads to the formation of macroscopic coating defects.

[0110] Therefore, partially saponified polyvinyl alcohols or partially saponified polyvinyl alcohol copolymers, such as polyethylene vinyl alcohols, are preferred over the fully saponified variants.

[0111] Particularly in the case of water- and moisture-sensitive coating layers (S1), e.g., those based on polyvinyl alcohols, it is important to protect them from humid environments. This can be achieved by vacuum deposition of metals with minimal application. Vacuum deposition also requires high smoothness or minimal roughness.

[0112] Due to its minimal thickness, the vacuum deposition layer must be protected against scratching, abrasion, oxidation, and breakage. Furthermore, an additional sealing layer is necessary for certain packaging applications, such as bags or similar packaging. This is achieved by applying a coating B2 to the barrier layer B1 (e.g., a vacuum deposition layer). In addition, the coating B2 can further improve the oxygen or water vapor barrier.

[0113] The barrier paper according to the invention is also characterized by an improved oxygen barrier, an improved grease barrier, an improved mineral oil barrier and an improved water vapor barrier.

[0114] The barrier paper according to the invention further exhibits improved crease resistance without impairing the barrier effect and is also characterized by high tear resistance.

[0115] The barrier paper according to the invention is also recyclable via the waste paper cycle.

[0116] When used as a packaging material for food, the barrier paper according to the invention is particularly characterized by the fact that it does not affect and / or alter the flavor of the packaged food. The barrier paper according to the invention is also heat-sealable and exhibits improved cold-sealing properties (compatible with the sealing medium, such as a water-based cold-seal adhesive), with the seal seams each exhibiting sufficient moisture resistance.

[0117] The barrier paper according to the invention is also easy to print on the uncoated side (outside) and on the coated side (inside).

[0118] Finally, the barrier paper according to the invention can be produced relatively easily and with low application weights and can be recycled via the waste paper cycle.

[0119] In the following, the term "comprise" may also mean "consisting of".

[0120] "Hydrophobic" refers to substances that are immiscible with water or can only be wetted by water with the use of surfactants. "Hydrophilic" refers to substances that are miscible with water or can be wetted by water without the use of surfactants. Hydrophobic polymers are also called nonpolar polymers, and hydrophilic polymers are also called polar polymers.

[0121] Hydrophobicity or hydrophilicity can be defined, for example, by the logP value. The n-octanol-water partition coefficient K ow(also spellings such as octanol / water partition coefficient are common and correct) is a dimensionless partition coefficient known to those skilled in the art that indicates the ratio of the concentrations of a chemical in a two-phase system of n-octanol and water and is thus a measure of the hydrophobicity or hydrophilicity of a substance. The logP value is the decimal logarithm of the n-octanol-water partition coefficient K ow . Where: and log P = log f = log c w o sl - c w sl with c0 Si = concentration of a chemical in the octanol-rich phase and c w Si= Concentration of a chemical in the water-rich phase. Kow is greater than one if a substance is more soluble in lipid-like solvents such as n-octanol, and less than one if it is more soluble in water. Accordingly, log P is positive for hydrophobic / lipophilic substances and negative for hydrophilic / lipophobic substances.

[0122] The low permeability of polyvinyl alcohols to oxygen, mineral oil, grease and other non-polar migrants is due to their relatively high hydrophilicity.

[0123] In addition, ethylene-containing polymers, such as (saponified) polyethylene vinyl alcohols, have a lower water vapor permeability, which is due to the ethylene content and the associated lower hydrophilicity.

[0124] The base paper used in the coated paper according to the invention is in principle not limited.

[0125] However, it is preferred that the base paper has a basis weight of 20 to 120 g / m 2 , preferably from 40 to 100 g / m 2 , has.

[0126] Furthermore, it is preferred that the base paper has a composition with a long fiber content of 10 to 80 wt.%, preferably 20 to 50 wt.%, and a short fiber content of 20 to 90 wt.%, preferably 50 to 80 wt.%.

[0127] A long fiber is defined as a fiber with a fiber length of 2.6 to 4.4 mm and a short fiber is defined as a fiber with a fiber length of 0.7 to 2.2 mm.

[0128] In addition, 0% to 20%, preferably 0% to 5% of fillers, preferably excluding 0%, such as GCC (ground calcium carbonate), known for example under the trade name Hydrocarb 60 or Hydroplex 60, PCC (precipitated calcium carbonate), known for example under the trade name Precarb 105, natural kaolin and / or talc, as well as customary auxiliaries such as retention agents and / or sizing agents, may be included.

[0129] The advantage of such a base paper is, on the one hand, its high flexibility and low stiffness and, on the other hand, its good processability on existing packaging lines for flexible materials such as plastic films, maintaining high machine availability and achieving the necessary puncture resistance, burst strength and tear resistance.

[0130] Common packaging systems include vertical and horizontal form-fill-seal machines for producing stand-up pouches, flow packs, pillow packs, and others; machines that combine two webs of the same or different materials and join them using heat sealing, cold sealing, or ultrasonic sealing, such as tray sealers; chamber belt machines (also with vacuum); bag filling and closing machines; thermoforming packaging machines; linear filling machines that apply lids using heat sealing; wrapping machines with a final heat sealing step; blister packaging machines; and X-fold packaging machines.

[0131] The barrier paper according to the invention is further preferably characterized in that a precoat comprising at least one inorganic pigment and a polymeric binder is present between the base paper and the coating color layer S1.

[0132] The inorganic pigment is preferably platelet-shaped and comprises in particular a talc, precipitated calcium carbonate or silicates, preferably phyllosilicates and very particularly preferably a kaolin.

[0133] Suitable polymeric binders include, in particular, acrylate-based or styrene / butadiene-based binders. In principle, all polymers that can be used as binders for pigment coatings in the paper industry are suitable. Starch-based binders (solutions of modified starches, dispersions of cross-linked starches, so-called biolatices) and polymer-starch hybrid latices are also possible.

[0134] The polymeric binder preferably comprises a polymeric binder based on a polyacrylate.

[0135] The primer can be a hydrophobic primer overall.

[0136] In another embodiment, the primer is entirely hydrophilic. The primer preferably contains 1 to 70 wt.%, more preferably 5 to 50 wt.%, of polymeric binder. This amount refers to the dried primer in the final product.

[0137] The primer preferably further contains 50 to 95% by weight, more preferably 80 to 90% by weight, of inorganic pigment. This amount refers to the dried primer in the final product.

[0138] The primer can also contain additives such as thickeners, e.g., acrylate-based thickeners, surfactants, and / or rheology modifiers. The use of crosslinking agents is also conceivable. The primer preferably contains a zirconium-based crosslinking agent and is itself crosslinked with formaldehyde.

[0139] These additives are preferably present in an amount of 0 to 2 wt.%, preferably greater than 0 to 2 wt.%, with the value 0% preferably being excluded. This amount refers to the dried primer in the final product.

[0140] The application quantity of the primer is preferably 1 to 10 g / m 2 and particularly preferably 2 to 6 g / m 2 . The quantity refers to the dried primer in the final product.

[0141] Applying such a primer has the advantage of sealing the paper surface, allowing the subsequent coating layer 1 applied to it to migrate only slightly into the paper, thus creating sufficient interlayer adhesion. Furthermore, this primer reduces the average roughness of the base paper and provides a beneficial "holdout," characterized by a comprehensive application and a defined surface energy, allowing the applied coating layer 1 to form optimally. Furthermore, the primer promotes interlayer adhesion between the base paper and the coating layer 1, which can be important for subsequent sealing applications.

[0142] The coating layer 1 applied to the primer preferably comprises an at least partially saponified polyvinyl alcohol and / or an at least partially saponified polyvinyl alcohol copolymer. The formulation used for the processing preferably contains an amount of 10 to 100 wt.%, particularly preferably 50 to 99.8 wt.%, of polymer.

[0143] The coating layer 1 may further contain additives such as thickeners, e.g. acrylate-based thickeners, surfactants, e.g. sulfosuccinates, extensional rheology aids, e.g. polyacrylamides, carboxymethylcellulose, polyvinyl alcohols, and / or crosslinking agents such as aldehydes and polyhydric aldehydes, zirconates, polyhydric epoxides, epichlorohydrin resins and / or hydrazides.

[0144] These additives are preferably each contained in an amount of 0.1 to 1 wt.%, based on the total weight of the coating layer 1.

[0145] In one embodiment, the barrier paper according to the invention is further preferably characterized in that the at least partially saponified polyvinyl alcohol and / or the at least partially saponified polyvinyl alcohol copolymer has an average molecular weight of less than 100,000 g / mol.

[0146] In another embodiment, the barrier paper according to the invention is further preferably characterized in that the at least partially saponified polyvinyl alcohol and / or the at least partially saponified polyvinyl alcohol copolymer has an average molecular weight of greater than 30,000 g / mol or greater than 40,000 g / mol or greater than 50,000 g / mol or greater than 60,000 g / mol or greater than 70,000 g / mol.

[0147] In one embodiment, the barrier paper according to the invention is further preferably characterized in that the at least partially saponified polyvinyl alcohol and / or the at least partially saponified polyvinyl alcohol copolymer has a degree of saponification of 30% to 100%.

[0148] In another embodiment, the barrier paper according to the invention is further preferably characterized in that the at least partially saponified polyvinyl alcohol and / or the at least partially saponified polyvinyl alcohol copolymer has a degree of saponification of 30% to less than 100%.

[0149] In another embodiment, the barrier paper according to the invention is further preferably characterized in that the at least partially saponified polyvinyl alcohol and / or the at least partially saponified polyvinyl alcohol copolymer has a degree of saponification of less than 95% or of 30% to 95%.

[0150] In another embodiment, the barrier paper according to the invention is further preferably characterized in that the at least partially saponified polyvinyl alcohol and / or the at least partially saponified polyvinyl alcohol copolymer has a degree of saponification of 95% to 100%.

[0151] In another embodiment, the barrier paper according to the invention is further preferably characterized in that the at least partially saponified polyvinyl alcohol and / or the at least partially saponified polyvinyl alcohol copolymer has a degree of saponification of 95% to less than 100%.

[0152] In another embodiment, the barrier paper according to the invention is further preferably characterized in that the at least partially saponified polyvinyl alcohol and / or the at least partially saponified polyvinyl alcohol copolymer has an onset temperature determined by DSC of less than 200°C

[0153] The barrier paper according to the invention is further preferably characterized in that the at least one polymer comprises a partially saponified polyvinyl alcohol having a degree of saponification of less than 95% or of 30% to 95%, an average molecular weight of greater than 0 and less than 100,000 g / mol and an onset temperature determined by DSC of less than 200°C.

[0154] In another embodiment, the barrier paper according to the invention is further preferably characterized in that the at least one polymer comprises a partially saponified polyvinyl alcohol having a degree of saponification of 95% to 100%, an average molecular weight of greater than 70,000 g / mol and an onset temperature determined by DSC of less than 200°C.

[0155] In another embodiment, the barrier paper according to the invention is further preferably characterized in that the at least one polymer comprises a partially saponified polyvinyl alcohol copolymer, preferably a partially saponified polyethylene vinyl alcohol, with a degree of saponification of 95% to 100%, an average molecular weight of greater than 60,000 g / mol, and an onset temperature determined by DSC of less than 210°C. It has been shown that a partially saponified polyvinyl alcohol copolymer such as polyethylene vinyl alcohol is generally more flexible than a polyvinyl alcohol.

[0156] In another embodiment, the barrier paper according to the invention is preferably characterized in that the at least one polymer is a mixture of a partially saponified polyvinyl alcohol with a degree of saponification of 1% to 95%, an average molecular weight of greater than 0 and less than 100,000 g / mol and an onset temperature determined by DSC of less than 200°C, a partially saponified polyvinyl alcohol with a degree of saponification of 95% to 100%, an average molecular weight of greater than 70,000 g / mol and an onset temperature determined by DSC of less than 200°C and / or a partially saponified polyvinyl alcohol copolymer, preferably a partially saponified polyethylene vinyl alcohol, with a degree of saponification of 95% to 100%, an average molecular weight of greater than 60,000 g / mol and an onset temperature determined by DSC of less than 210°C.

[0157] The degree of saponification was determined in accordance with DIN EN ISO 3681 as follows:

[0158] Polyvinyl alcohol (PVOH) (1 g) is mixed with distilled water (70 mL) and neutralized ethanol (30 mL) and heated under reflux until completely dissolved. After cooling, the solution is neutralized with potassium hydroxide solution (0.1 M). In the case of partially saponified PVOH types, additional potassium hydroxide solution (50 mL, 0.1 M) is added and heated under reflux (60 min). In the case of fully saponified PVOH types, a reduced amount of additional potassium hydroxide solution (25 mL, 0.1 M) is used to prevent the absorption of carbon dioxide in the excess hydroxide solution, with a likewise reduced reflux time (30 min). The excess hydroxide solution is then back-titrated with hydrochloric acid (0.1 M) against phenolphthalein as an indicator. A blank test is carried out in parallel.

[0159] The degree of saponification (%) can be calculated using Eq. 1:

[0160] (100 — 0.1535) x ester number ((

[0161] Saponification

[0162] 6sg 6rad ( v%) 7 = - x 100 'T (100 - 0.0749) x ester number where the ester number is determined according to equation 2: (consumption KOH PVOH (mg) — Consumption KOH Blindwert (mg)) x 5.61

[0163] Ester number (mg KOH / g) = 100 (Eq. 2)

[0164] Weight (g)

[0165] The average molecular weights were determined by size exclusion chromatography (GPC) under the following conditions:

[0166] Eluent: DMSO / + 0.1 M LiCl; Precolumn: 10 pm, Guard, ID 8.00 mm x 50.00 mm; Columns: 10 pm, 30 Å, ID 8.00 mm x 300.00 mm; 10 pm, 3000 Å, ID 8.00 mm x 300.00 mm; 10 pm, 3000 Å, ID 8.00 mm x 300.00 mm; Pump: 1260 HPLC pump; Flow rate: 1.0 mL / min; Injector: 1260 autosampler; Injection volume: 200 pL; Sample concentration: 5.0 g / L; Temperature: 80 °C; Detectors: SECcurity 2 Refractive index detector (RI) - WEG eta 1001 HT viscometer; calculation: WinGPC UniChrom version 8.33

[0167] The samples were dissolved in the solvent (5 mg / mL) at a temperature of 80 °C for three hours and injected by autosampler.

[0168] To determine the calibration curve, several PMMA standards with different molecular weights were measured. By measuring the intrinsic viscosity, the calibration curve was converted into a universal calibration curve.

[0169] The barrier paper according to the invention is further preferably characterized in that the polyvinyl alcohol has a viscosity of less than 30 mPas or less than 20 mPas, particularly preferably less than 15 mPas, at a dry matter content of 4%.

[0170] The viscosity is determined at 23°C using a Brookfield viscometer at 100 rpm.

[0171] A viscosity in this range has the advantage that higher solids contents can be utilized in the application, thus requiring less energy for drying. Furthermore, higher process speeds can be achieved. This translates not only to a financial advantage but also to the use of a larger drying window on coating lines. As already mentioned above, the quality of the barrier paper according to the invention, particularly with regard to its crease resistance, can be determined by dynamic mechanical thermal analysis (DMTA).

[0172] Dynamic mechanical thermal analysis (DMTA) can also be used to determine the glass transition temperature (Tg)—the temperature at which the polymer chains transition from a solid, frozen state to a mobile state, but before the polymer chains slide past each other, which corresponds to the melting point (Tm). It is advantageous for a packaging material to have a viscoelastic state to maintain a barrier property after bending or folding—therefore, a Tg below the operating and use temperature is ideal. The Tg is determined in DSC by the temperature at which browning reaches a maximum. Preferred polymers have a glass transition temperature Tg corresponding to the tan maximum.

[0173] The barrier paper according to the invention preferably has a breaking strength of > 80 N / 15 mm, preferably > 90 N / 15 mm in the running direction, and > 40 N / 15 mm, preferably > 50 N / 15 mm transverse to the paper running direction.

[0174] The barrier paper according to the invention further preferably has a dynamic coefficient of friction (CoF) of <0.7, preferably <0.6, particularly preferably <0.5. This refers to the friction of the coated side on the coated side (coating against coating).

[0175] The barrier paper according to the invention is further preferably characterized in that the surface coating weight of the individual layers is 4 to 20 g / m 2 , preferably from 4 to 15 g / m 2 , based on the dried final product (Lutro).

[0176] The barrier paper according to the invention is further preferably characterized in that the coating B2 can be wetted with common water-based cold-seal adhesives. For this purpose, the surface energy of the coating B2 is > 35 mN / m > 40 mN / m, preferably > 50 mN / m, particularly preferably > 55 mN / m. Such wettability of the coating B2 has the advantage that no non-streakable areas form during the application and drying process of cold-seal adhesives, and sufficient adhesion is also ensured for the application.

[0177] The barrier paper according to the invention is further preferably characterized in that the barrier paper has an oxygen permeability (OTR) 10 cm 3 / m 2 / d (23°C, 0% relative humidity) of less than 10, preferably less than 5.

[0178] The barrier paper according to the invention is further preferably characterized in that the barrier paper has an oxygen permeability (OTR) 10 cm 3 / m 2 / d (23°C, 50% relative humidity) of less than 10, preferably less than 5.

[0179] The barrier paper according to the invention is further preferably characterized in that the barrier paper has an oxygen permeability (OTR) 10 cm 3 / m 2 / d (23°C, 70% relative humidity) of less than 20, preferably less than 15.

[0180] The barrier paper according to the invention is further preferably characterized in that the barrier paper has an oxygen permeability (OTR) 10 cm 3 / m 2 / d (23°C, 80% relative humidity) of less than 50, preferably less than 40.

[0181] The barrier paper according to the invention preferably does not lose this oxygen barrier even through the mechanical stress of 180° bends with a roller which exerts a load of 330 g / cm on the resulting bend and in which the coating can be located inside (inner bend) or outside (outer bend).

[0182] The oxygen transmission rate (OTR) is determined according to ISO 15105-2. The barrier paper according to the invention is further preferably characterized in that the barrier paper has a grease barrier corresponding to test condition I according to DIN 53116.

[0183] The barrier paper according to the invention preferably does not lose this grease barrier even through the mechanical stress of 180° bends with a roller that exerts a load of 330 g / cm on the resulting bend and in which the coating can be located inside (inner bend) or outside (outer bend).

[0184] The barrier paper according to the invention is further preferably characterized in that the barrier paper has a mineral oil barrier (hexane) of < 10 g / m 2 / d.

[0185] The barrier paper according to the invention preferably does not lose this mineral oil barrier (hexane) even through the mechanical stress of 180° bends with a roller which exerts a load of 330 g / cm on the resulting bend and in which the coating can be located inside (inner bend) or outside (outer bend).

[0186] The mineral oil barrier is determined by filling a beaker (solvent-resistant) with hexane, sealing it tightly with the coated paper, and monitoring the weight loss over time.

[0187] The barrier paper according to the invention is further preferably characterized in that the barrier paper has a water vapor permeability g / m 2 / d (23°C, 50% relative humidity) of less than 10, preferably less than 5.

[0188] The barrier paper according to the invention is further preferably characterized in that the barrier paper has a water vapor permeability g / m 2 / d (23°C, 85% relative humidity) of less than 10, preferably less than 5.

[0189] The barrier paper according to the invention is further preferably characterized in that the barrier paper has a water vapor permeability g / m 2 / d (38°C, 50% relative humidity) of less than 10, preferably less than 5. The barrier paper according to the invention is further preferably characterized in that the barrier paper has a water vapor permeability g / m 2 / d (38°C, 70% relative humidity) of less than 20, preferably less than 10.

[0190] The barrier paper according to the invention is further preferably characterized in that the barrier paper has a water vapor permeability g / m 2 / d (38°C, 90% relative humidity) of less than 20, preferably less than 10.

[0191] The barrier paper according to the invention is further preferably characterized in that the barrier paper has a water vapor barrier. This remains intact even when the coating comes into contact with grease, which is not the case for all water vapor barriers.

[0192] The barrier paper according to the invention is further preferably characterized in that it is kink-resistant both when not folded and in the inner fold and in the outer fold.

[0193] The coated paper according to the invention is characterized by its recyclability through the waste paper cycle. Preferably, it is rated as conditionally recyclable or preferably recyclable according to PTS PTS-RH 021.

[0194] The coated paper according to the invention is characterized by recyclability through the waste paper cycle. Preferably, it meets UNI 11743 Level C, preferably Level B, particularly preferably Level A, and very particularly preferably Level A+.

[0195] The coated paper according to the invention is characterized by biodegradability in the maritime sector according to ASTM D7081

[0196] The barrier paper according to the invention is sensory safe and achieves at least a value of < 2 (according to standard DIN1230-l:2010-02).

[0197] The barrier paper according to the invention is heat-sealable and at the optimum sealing temperature preferably results in a seal seam strength (cold tack) of > 3.5 N / 15 mm, particularly preferably > 5.0 N / 15 mm, wherein the seal seam strength for the barrier paper was determined as follows:

[0198] The barrier paper was sealed at 3.3 bar for 0.3 seconds in the temperature range from 100°C to 230°C across the paper grain and the seal seam strength (cold tack) was determined according to DIN 55529 (2012).

[0199] "Heat sealing" is preferably understood to mean the joining of two layers of the barrier paper by means of local heat and / or pressure. In further embodiments, the coated side of the paper can also be joined to a non-heat sealable opposite side of the paper, to a heat sealable opposite side of the paper, or to another paper by heat sealing.

[0200] The barrier paper according to the invention is also cold-sealable due to its compatibility with common cold-seal media. Cold sealing generally refers to the application of a cold-seal adhesive to the section of a flat packaging material to be sealed using a printing process. A cold-seal adhesive has the property that it only develops an adhesive effect under and after increased pressure between the sealing jaws of a packaging machine and is otherwise non-sticky or only tacky to a limited extent.

[0201] Ultrasonic sealing involves focusing ultrasound energy on the weld site, generating heat through friction, particularly for heat sealing. Typical sealing times are between 100 and 200 milliseconds. Unlike heat sealing, e.g., using sealing jaws, the required heat with ultrasonic technology is generated only within the materials to be welded. The tools remain cool and facilitate heat dissipation.

[0202] Both the heat-sealed barrier paper, the cold-sealed barrier paper and the ultrasonically sealed barrier paper are characterized by a high moisture resistance of the sealing seam.

[0203] The barrier paper according to the invention is also tear-resistant. The barrier paper according to the invention is further characterized by the fact that the taste of the food packaged therein is not affected.

[0204] The barrier paper according to the invention can be produced economically using known manufacturing processes.

[0205] However, it is preferred to obtain the barrier paper according to the invention by a process in which an aqueous suspension comprising the starting materials of the coating color layer S1 is applied to the base paper, the aqueous application suspension having a solids content of 5 to 50% by weight, preferably 10 to 30% by weight, and is applied by a curtain coating process, preferably by a double curtain coating process (double curtain coating) at an operating speed of the coating system of at least 200 m / min.

[0206] This process is particularly advantageous from an economic point of view and due to the uniform application across the paper web.

[0207] If the solids content falls below approximately 10 wt.%, the cost-effectiveness deteriorates, as a large amount of water must be removed quickly through gentle drying, which adversely affects the coating speed. On the other hand, if the value exceeds 50 wt.%, this simply leads to increased technical effort to ensure the stability of the coating curtain during the coating process and the drying of the applied film, as the machine must again run at very high speeds.

[0208] In the curtain coating process, a freely falling curtain of a coating dispersion is formed. The coating dispersion, in the form of a thin film (curtain), is "poured" onto a substrate by free fall in order to apply the coating dispersion to the substrate. DE 10 196 052 TI discloses the use of the curtain coating process in the production of information recording materials, wherein multilayer recording layers are realized by applying the curtain consisting of several coating dispersion films to substrates. In a preferred embodiment of the process according to the invention, the aqueous deaerated application suspension has a viscosity of approximately 100 to approximately 800 mPas (Brookfield, 100 rpm, 20 °C). If the value falls below approximately 100 mPas or exceeds approximately 100 mPas, the viscosity can be increased to approximately 100 mPas.If the value of approximately 800 mPas is exceeded, this leads to poor runnability of the coating slip on the coating unit. The viscosity of the aqueous, deaerated application suspension is particularly preferably between approximately 200 and 500 mPas.

[0209] In a preferred embodiment, to optimize the process, the surface tension of the aqueous coating suspension can be adjusted to about 25 to about 70 mN / m, preferably to about 35 to about 60 mN / m (measured in accordance with the standard for bubble pressure tensiometry (ASTM D 3825-90), as described below). Better control over the coating process is achieved by determining the dynamic surface tension of the coating color and adjusting it specifically by selecting the appropriate surfactant and determining the required amount of surfactant.

[0210] It has been shown that polyvinyl alcohol solutions require significantly less surfactant to generate an identical surface tension compared to dispersions, especially those with small particle size and thus high particle surface area.

[0211] Dynamic surface tension is measured using a bias pressure tensiometer. It measures the maximum internal pressure of a gas bubble formed in a liquid via a capillary. The internal pressure p of a spherical gas bubble (Laplace pressure) depends, according to the Young-Laplace equation, on the radius of curvature r and the surface tension o: n — 2o

[0212] If a gas bubble is created at the tip of a capillary in a liquid, the curvature initially increases and then decreases again, resulting in a pressure maximum. The greatest curvature and thus the greatest pressure occur when the radius of curvature equals the capillary radius. Pressure curve during bubble pressure measurement, position of the pressure maximum:

[0213] The capillary radius is determined using a reference measurement performed with a liquid with a known surface tension, usually water. Once the radius is known, the surface tension can be calculated from the maximum pressure pmax. Since the capillary is immersed in the liquid, the hydrostatic pressure pO, which results from the immersion depth and the density of the liquid (this is done automatically with modern measuring instruments), must be subtracted from the measured pressure. This yields the following formula for the bubble pressure method:

[0214] The measured value corresponds to the surface tension at a specific surface age, the time from the onset of bubble formation to the occurrence of the pressure maximum. By varying the bubble generation rate, the dependence of surface tension on surface age can be determined, resulting in a curve plotting surface tension over time.

[0215] This dependence plays an important role in the use of surfactants, since the equilibrium value of the interfacial tension is not reached in many processes due to the sometimes low diffusion and adsorption rates of surfactants.

[0216] The formation of the individual coatings can be carried out online on a paper machine with a coating unit or in a separate coating process offline on a coating machine.

[0217] In further embodiments, the individual layers can also be applied to the base paper using the following methods:

[0218] The coating layer S1 can be applied to the base paper and / or to existing pre-coats by means of a printing process.

[0219] The coating layer S1 can be applied by extrusion onto the base paper and / or existing precoats. This technique has the advantage that significantly more material can be applied, but this is only of interest if the overall product does not need to be recyclable as paper. Disadvantages, however, include lower application speeds, higher energy consumption, and a higher minimum application weight.

[0220] The coating layer S1 can be applied by lamination or covering of paper, e.g. in the form of plastic films, onto the base paper and / or onto existing primers.

[0221] The coating layer S1 and the primer can also be applied successively in several application steps.

[0222] The present invention further relates to a barrier paper which is obtainable by the processes described above.

[0223] Due to its comparatively high polarity, the coating layer S1 is also suitable for applying additional barriers in the form of aqueous polymer solutions or dispersions, by melt extrusion or lamination with films.

[0224] The coating layer S1 can be smoothed to achieve a Bekk smoothness of at least 200 Bekk seconds, in particular 500 Bekk seconds.

[0225] A further layer is applied to the metallized layer by vacuum deposition.

[0226] The coating layer S1 can be improved with regard to all barriers, if necessary, by applying a barrier layer B1, in particular an ultra-thin metal layer, metal oxide layer, or other inorganic compound by vapor deposition or, more specifically, vacuum vapor deposition. Such thin barrier layers are only effective if they adhere to a very smooth, flexible substrate that contains no particles (e.g., inorganic pigments) and can form a continuous layer thereon. The comparatively high surface energy of the coating layer S1, in particular that of the polymers it comprises, promotes the interlayer adhesion of polar materials such as metal oxides and other inorganic oxides, as well as polarizable, electrically conductive materials such as metals.The barrier papers thus obtained can in turn be made sealable by applying a heat-sealing layer or a cold-sealing adhesive.

[0227] A further coating B2 is applied to the barrier layer B1, which has been applied by vacuum deposition, using gravure printing (also known as curtain coating or other printing processes). Contactless application has the advantage that the surface of the material to be coated cannot be damaged or adversely affected.

[0228] The present invention also relates to the use of a barrier paper as described above or a barrier paper obtainable by the method described above as packaging material.

[0229] Finally, the present invention also relates to the use of a barrier paper as described above or a barrier paper obtainable by the method described above as packaging material for foodstuffs, in particular for fatty, moisture-sensitive and oxidation-sensitive foodstuffs.

[0230] The present invention further preferably relates to the use of a barrier paper as described above or a barrier paper obtainable by the process described above as packaging material for e.g. muesli bars, chocolate, meat, sausage, cheese, chocolate-containing products, butter and margarine, snacks, chips, e.g. potato or lentil chips, products fried in vegetable oil such as chips, salty snacks, biscuits, crackers, protein bars, sports and fitness bars, food supplements, soup cubes, cosmetic products such as powder and make-up, coffee and tea, pet food, tobacco products (inter alia as inner liners), yoghurt (as lids).

[0231] In a further preferred embodiment of the invention, the barrier paper according to the invention is applied to cardboard or paperboard, in particular by lamination, gluing, or bonding. Finally, the present invention also relates to the use of a composite in which a barrier paper according to the invention is applied to cardboard or paperboard, in particular by lamination, gluing, or bonding, as a packaging material for foodstuffs, in particular for fatty and oxidation-sensitive foods.

[0232] This makes it possible to produce packaging materials in a simple and cost-effective way that offer the advantages of both material components, such as the increased strength and rigidity of cardboard or paperboard compared to coated paper, as well as the aforementioned advantages of barrier papers. Application can be achieved using starch or aqueous dispersion adhesives, for example.

[0233] Preferably, the barrier paper can be a component of packaging materials based on cardboard or paperboard.

[0234] With these packaging materials according to the invention, especially heavier food products can be packaged safely and presented to the customer in an attractive manner in the form of upright packaging.

[0235] These packaging materials preferably have a mass fraction of greater than 95% by weight of the uniform material type paper, cardboard, or paperboard. A further advantage of the present invention is that these packaging materials according to the invention are not composite packaging according to Section 3 (5) of the Packaging Act, and thus this embodiment of the present invention contributes significantly to reducing the impact of packaging waste on the environment.

[0236] The present invention also relates to a packaging comprising a barrier paper as described above or in a composite with cardboard or paperboard as described above.

[0237] The features of the use according to the invention apply analogously to the packaging according to the invention.

[0238] The packaging can be cold-sealed. Cold-sealed packaging is particularly suitable for packaging food products such as chocolate, chocolate-containing products, bars (e.g., muesli bars), and / or other confectionery. This is due partly to the heat sensitivity of chocolate and partly to the potential for higher machine speeds. Packaging machines based on cold seals can operate faster, as heating a heat-sealing medium takes a comparatively long time.

[0239] The packaging can also be heat-sealed. Heat-sealed packaging is preferably used as secondary packaging or for packaging containers via dosing and filling scales.

[0240] The packaging can also be cold-sealed packaging

[0241] The packaging can also be primary or secondary packaging, in particular heat-sealed or cold-sealed tubular bag packaging, flow wrap, stand-up pouches, wrapping paper, 3- and 4-edge sealed bags, lids.

[0242] The barrier paper can also be used inverted, so that the inside faces out and the outside faces in. This ensures excellent performance in humid environments. In this case, sealing wax must be applied partially or completely, or the packaging must be sealed ultrasonically. In this case, the B2 coating is coated or printed.

[0243] Coating B2 can be opaque to prevent the barrier layer B1 from showing through. Alternatively, coating B2 can also be printed with an opaque layer.

[0244] The barrier paper according to the invention preferably comprises at least one base paper with two sides (surfaces) of different roughness (rougher side r and smoother side g). The rougher side (r) of the base paper is preferably used for coating by means of a precoat, coating color layer S1, barrier layer B1 and barrier layer B2 (inner side). The less rough side (r) is preferably used for printing by means of gravure printing (outer side). In a particular embodiment, the smoother side (g) can also be used for coating by means of a precoat, coating color layer S1, barrier layer B1 and barrier layer B2 (inner side) and the rougher side (r) can be used for printing (outer side). This embodiment has poorer printability, but leads to an improvement in the barrier properties of the coating color layer S1 or B2 due to its less rough surface.to a saving of material in the coating layer Sl while maintaining the same barrier properties (e.g. the same property with a lower layer thickness).

[0245] The invention is explained in detail below using non-limiting examples and figures.

[0246] Figures:

[0247] Figure 1 shows two basic structures a) and b) of barrier papers according to the invention with the following reference numerals:

[0248] 1: Base paper g: smoother surface of the base paper r: rougher surface of the base paper 2: Coating layer Sl 3: Barrier layer Bl 4: Coating B2 5: Primer, optional for better coating hold-out to prevent the coating layer Sl from seeping into the base paper 6: Starch coat, optional for better printability 7: Barrier paper according to the invention

[0249] A: A-sealing area of ​​the barrier paper B: B-sealing area of ​​the barrier paper A / A-sealing A / B-sealing

[0250] 8: additional coating layer Sl, same or different composition / layer thickness as 2

[0251] Not shown: Printing of the barrier paper using conventional printing processes, particularly flexographic, gravure, or digital printing. Figure 2 shows two SEM surface images of comparative example V3 (inner crease) at different resolutions. The topmost coating (B1) is shown as a top view. It can be seen that the surface has cracked due to the bending stress.

[0252] Figure 3 shows two SEM surface images of Example B1 (inner bend) at different resolutions. The topmost coating (coating B2) is shown as a top view. It can be seen that it was stressed by the buckling but did not fracture.

[0253] Figure 4 shows two SEM surface images of comparative example V5 (inner bend). The top coating (B2) is shown as a top view. The coating layer S1 is missing here. It can be seen that this layer has cracked due to the bending stress.

[0254] Figure 5 shows two images after the palm kernel fat test (inner crease on the left, outer crease on the right) of Comparative Example VI. The top coating (coating layer S1) is shown as a top view. In this case, the layer thickness was halved. It can be seen that this halving does not lead to any problems with the surface fat barrier (to the right and left of the crease), but does lead to problems with crease resistance (fat penetration in the crease and in the edge area of ​​the crease).

[0255] Figure 6 shows two images after the palm kernel fat test (inner crease on the left, outer crease on the right) of comparative example V2. The top coating (coating layer S1) is viewed from above. In this case, a preferred layer thickness was chosen. It can be seen that there are no problems with the surface fat barrier (right and left of the crease) or with the crease resistance (no fat penetration in the crease or in the edge area of ​​the crease).

[0256] Figure 7 shows various packaging forms according to the invention with A:A sealing.

[0257] Figure 8 shows an envelope packaging according to the invention with A:B sealing on the front side.

[0258] Figure 9 shows a schematic representation of a graph of a typical DMTA measurement for a barrier paper according to the invention. The measured values ​​for the loss factor tan delta are plotted as a function of temperature. With increasing temperature, a maximum is initially observed at temperature Tg, followed by a first inflection point at temperature Tw.

[0259] Figure 10 shows a DMTA measurement for the inventive examples 9 and 10 in comparison with the comparative example V2 according to Table 2.

[0260] The present invention is explained in more detail below using several examples. These examples serve merely to illustrate the invention and do not limit it.

[0261] Examples:

[0262] The following coatings were applied to a base paper with a basis weight of 60 g / m 2 or 70 g / m 2and with 40% long fiber and 60% short fiber content each, using 100% virgin fiber pulp.

[0263] Primer:

[0264] In all examples, the primer contains 75.9% pigment (layered silicate), 22.8% latex (styrene-acrylate latex) and 1.3% rheology modifiers (0.2% acrylate-based thickener, 1.1% zirconium-based crosslinker).

[0265] The primer was applied to the base paper using a squeegee (blade).

[0266] Coating layer Sl:

[0267] In Examples 1 to 5, polyvinyl alcohols were used as polymers. In Examples 6 to 8, partially saponified polyethylene vinyl alcohols were used as polymers.

[0268] The coating layer S1 of Examples 1 to 5 comprises a pure polymer coating. Example 1' comprises a polymer coating with 99.8% polyvinyl alcohol as the polymer (Example 1; degree of saponification: 87%; M w: 50900) and 0.2% rheology modifiers (Na-Dokusate).

[0269] The coating layer S1 of Examples 9 and 10 and Comparative Examples 1, 2, 3, and 5 corresponds to the coating layer S1 of Example 1. The use of the coating layer S1 of Example 1' led to comparable results.

[0270] Barrier layer Bl:

[0271] In Examples 9 and 10 and Comparative Examples 1, 2, 3 and 5, a barrier layer Bl approximately 40 nm to 80 nm thick was applied directly onto the coating color layer Sl or onto the precoat by means of vacuum deposition of aluminum.

[0272] Coating B2:

[0273] The gravure printing and curtain coating processes were investigated. The following properties were tested:

[0274] Area or application weight: Application weight of the coatings in g / m 2This is determined by differential weighing between coated and uncoated papers.

[0275] Viscosity: The viscosity was determined using a Brookfield viscometer at 23°C and a speed of 100 rpm, with a dry content of 4%.

[0276] WVTR: Water vapor transmission rate, determined according to ASTM D 1653. For bent samples, a 180° bend is created with a roller that exerts a load of 330 g / cm on the resulting bend and where the coating can be on the inside (inner bend) or outside (outer bend).

[0277] OTR: Oxygen transmission rate, determined according to DIN 15105-2

[0278] For bent samples, a bend of 180° is created with a roller that exerts a load of 330 g / cm on the resulting bend and where the coating can be located inside (inner bend) or outside (outer bend).

[0279] HVTR: Hexane vapor transmission rate. In this test, n-hexane is poured into a solvent-resistant beaker, tightly sealed with the test specimen, and the weight loss is monitored over time. For bent specimens, a 180° bend is created using a roller that applies a load of 330 g / cm to the resulting bend. The coating can be on the inside (inner bend) or outside (outer bend).

[0280] Palm kernel fat test: Analogous to DIN 53116. For bent samples, a bend of 180° is created with a roller that exerts a load of 330 g / cm on the resulting bend and where the coating can be on the inside (inner bend) or outside (outer bend).

[0281] Indicator paper: Evaluation of the indicator paper mentioned in DIN 53116. Grease penetration points with a diameter (d) of < 1 mm (first value in the table) and > 1 mm (second value in the table) are counted.

[0282] Sample paper: Evaluation of the back of the sample paper mentioned in DIN 53116. This is not part of the standard, but was performed for better differentiation.

[0283] Seal seam strength: The samples are sealed at 3.3 bar for 0.3 seconds across the paper grain at a temperature range of 100°C to 220°C, and the seal seam strength is determined according to DIN 55529 (2012). The optimal sealing temperature is given, along with the sealing force at 150°C (optimal sealing temperature of Example 1) for comparison.

[0284] Friction coefficients: The static and kinetic friction coefficients were determined according to ISO 8295.

[0285] Friction coefficient back to back:

[0286] Two test specimens are aligned with their functionally coated sides to each other and the coefficient of friction is determined (inside / inside)

[0287] Friction coefficient back against barrier side:

[0288] A measurement is taken of the functionally coated side (barrier side) of the barrier paper against the metal surface of the device (inside / barrier side).

[0289] DSC melting temperature / onset:

[0290] The DSC curves were recorded using a Mettler DSC 20 S in cold-welded aluminum crucibles with perforated lids. Heating rates were 10 K / min in the range between 30°C and 280°C. Melting temperatures were determined using the peak minima of the melting process. Necessary?

[0291] Surface tension (surface energy): Contact angle measuring device OCA 20 (DataPhysics) with software SCA 20. Measuring principle: OWRK method (Owens, Wendt, Rabel, Kaelble). Used measuring fluids and origin of the entered material constants: Water and diiodomethane (according to Buscher) as well as 1,5-pentanediol (according to Gebhardt).

[0292] Friction sensitivity 1) Measure barrier property of the upper barrier paper

[0293] Osertest 2) Place barrier papers on top of each other in the Oser tester

[0294] (Barriers facing down), add a 500g weight, and turn the device on for 60 seconds. Then lift the weight again.

[0295] 3) Measuring the barrier property of the upper barrier paper.

[0296] The resulting barrier papers were tested. The results are presented in the following tables.

[0297] Table 1 shows the results for intermediate products containing only the coating layer S1 but no barrier layer Bl and no

[0298] Coating B2 (Examples Ex. 1 to Ex. 8). Table 2 shows the results for barrier papers according to the invention, which in particular have a coating layer S1, a barrier layer B1, and a coating B2 (Examples Ex. 9 and Ex. 10), as well as Comparative Examples VI to V5.

[0299] The partially saponified polyvinyl alcohols used exhibit very low hexane and oxygen transmission rates. This is presumably due to their relatively high hydrophilicity.

[0300] Polyvinyl alcohols with a higher degree of saponification are characterized by a higher viscosity in the coating color at the same dry content. This makes sense from a chemical point of view, since the higher polarity allows each molecule to interact more strongly with the surrounding solvent (water).

[0301] This is rather disadvantageous, since at low dry contents, a large amount of water must be dried during the coating process. This not only costs energy, but can also be technically difficult to achieve depending on the desired application weight. Furthermore, the diffusion of water molecules and thus the drying process itself is slowed. Furthermore, this can lead to the accumulation of gaseous water in the coating, which leads to the formation of macroscopic coating defects.

[0302] The water vapor permeability of the polyethylene vinyl alcohols investigated is lower than that of the polyvinyl alcohols, which is probably due to the ethylene content and the associated lower hydrophilicity.

[0303] In general, fully saponified polyvinyl alcohols (PVOH) should be more brittle than partially saponified PVOH due to the larger number of hydrogen bonds they can form.

[0304] In particular, in order to retain the essential or all barrier properties even in the crease or crease area after the barrier papers have been folded, the barrier papers according to all exemplary embodiments of the invention have the following: a) For all barrier papers according to these examples, the values ​​for the loss factors tan delta measured by means of dynamic mechanical thermal analysis (DMTA) of the barrier papers as a function of temperature pass through a maximum at temperature Tg and a first inflection point at temperature Tw with increasing temperature. b) For all barrier papers according to these examples, the temperature Tg is also lower than the temperature Tw. c) The absolute value of the difference between tan delta at temperature Tg and tan delta at temperature Tw is > 0.013 for all barrier papers according to these examples.

[0305] Without being bound by these theories, the inventors made the following considerations:

[0306] Dynamic mechanical thermal analysis (DMTA) shows that the barrier papers of the invention can maintain a barrier after buckling if the barrier papers have a significant viscoelastic component. A so-called "rubber-elastic regime" state can be interpreted by quantifying the change in the tan delta value (tan δ) at the glass transition temperature (Tg) to the first inflection point (Tw) of the tan delta curve with increasing temperature. A barrier material, which may also include a metal-coated layer, that retains its barrier properties after buckling exhibits a tan delta change of > 0.013.

[0307] Dynamic mechanical thermal analysis (DMTA) also provides the glass transition temperature (Tg)—the temperature at which the macromolecular polymer chains transition from a solid, frozen state to a mobile state, but before the macromolecular polymer chains slide past each other, which is the melting point (Tm). It is advantageous for a barrier paper to have an elastic state to maintain a barrier after folding or creasing—therefore, a Tg below the operating and service temperature is ideal. The Tg is determined in DSC by the temperature at which the tan delta reaches a maximum. One of the examples has a glass transition temperature Tg = 8.4 °C, corresponding to a tan delta maximum of 0.099 and a tan delta change of 0.0185.

[0308]

[0309]

[0310]

[0311]

[0312]

[0313]

[0314]

[0315]

Claims

Claims 1. Barrier paper, comprehensive at least - a basic paper, - at least one coating layer Sl applied directly or indirectly to the base paper, - at least one barrier layer Bl applied directly or indirectly to the coating layer Sl, - a coating B2 applied directly or indirectly to the barrier layer Bl.

2. Barrier paper according to claim 1, characterized in that the coating layer Sl has at least one of the following properties: - Water vapor barrier, - Oxygen barrier, - Mineral oil barrier, - Aroma barrier, - Fat barrier, - Buckling resistance of at least one property, - Grease resistance, - Sealability, - Smoothness according to Bekk of at least 200 Bekk seconds.

3. Barrier paper according to claim 1 or 2, characterized in that the coating layer Sl comprises or consists of at least one water-soluble polymer and / or at least one water-dispersible polymer.

4. Barrier paper according to claim 3, characterized in that the at least one water-soluble polymer and / or the at least one water-dispersible polymer is selected from the group: - Polyvinyl alcohol, especially partially saponified or fully saponified; - Polyvinyl alcohol copolymer, in particular copolymerized with ethylene, polyvinylamine, acrylic acid derivatives, partially or fully saponified; - Modified fully or partially saponified polyvinyl alcohols or copolymers, in particular modifications with acyl, alkyl, acrylamide, silanol, diacetone, acetoacetyl, itaconic acid; - Polymer with an onset temperature of less than 210°C determined by DSC, wherein the onset temperature is determined by DSC as per DIN EN ISO 11357-1:2010-03 as the intersection of the extrapolated baseline and the inflection tangent at the beginning of the melting or crystallization peak; - Acrylic-based polymers; - Polyester-based polymers; - Nitrocellulose-based polymers; - Polyvinyl acetate-based polymers.

5. Barrier paper according to at least one of claims 3 or 4, characterized in that the at least one water-soluble polymer and / or the at least one water-dispersible polymer comprises at least partially saponified polyvinyl alcohol and / or at least partially saponified polyvinyl alcohol copolymer, each with an onset temperature determined by DSC of less than 210°C.

6. Barrier paper according to at least one of claims 3 to 5, characterized in that the at least one water-soluble polymer and / or the at least one water-dispersible polymer comprises a partially saponified polyvinyl alcohol with a degree of saponification of 30% to 95%, an average molecular weight of greater than 0 and less than 100000 g / mol and with an onset temperature of less than 200°C as determined by DSC.

7. Barrier paper according to at least one of claims 3 to 6, characterized in that the at least one water-soluble polymer and / or the at least one water-dispersible polymer comprises a partially saponified polyvinyl alcohol with a degree of saponification greater than 95% to 100%, an average molecular weight greater than 70000 g / mol and with an onset temperature of less than 200°C as determined by DSC.

8. Barrier paper according to at least one of claims 3 to 7, characterized in that the at least one water-soluble polymer and / or the at least one water-dispersible polymer is a partially saponified polyvinyl alcohol copolymer, preferably a partially saponified polyethylene vinyl alcohol, with a degree of saponification of 95% to 100%, a The average molecular weight is greater than 60000 g / mol and the onset temperature determined by DSC is less than 210°C.

9. Barrier paper according to at least one of claims 3 to 8, characterized in that the partially saponified polyvinyl alcohol and / or the partially saponified polyvinyl alcohol copolymer has a viscosity of less than 30 mPas, particularly preferably less than 20 mPas and most preferably less than 15 mPas at a dry content of 4%.

10. Barrier paper according to at least one of claims 3 to 9, characterized in that the at least one water-soluble polymer and / or the at least one water-dispersible polymer comprises a mixture of the polymers defined in claims 3 to 8.

11. Barrier paper according to at least one of the preceding claims, characterized in that the coating layer S1 has a surface tension in the range of 25 to 80 mN / m, in particular 25 to 75 mN / m.

12. Barrier paper according to at least one of the preceding claims, characterized in that the barrier layer Bl comprises or consists of metals, in particular Al, Cu, Sn, Zn, Ag, Au, Ti, In, Si, metal alloys, metal oxides, in particular Al2O3, SiÜ2, mixed oxides or a combination thereof.

13. Barrier paper according to at least one of the preceding claims, characterized in that the barrier layer Bl is applied by means of vacuum deposition.

14. Barrier paper according to at least one of the preceding claims, characterized in that the barrier layer Bl has at least one of the following features: a) optical density > 1.5 and < 6.0, b) layer thickness > 5 nm, preferably > 10 nm, particularly preferably > 15 nm, in particular 5 nm to 150 nm 15. Barrier paper according to at least one of the preceding claims, characterized in that the coating B2 comprises or consists of at least one polymer, in particular a polymer selected from the group comprising a) polyethylene acrylic acid copolymers, b) polyolefins, c) polyvinyl alcohols, d) cellulose nitrates, e) bio-based polymers, f) non-bio-based polymers, g) styrene-butadiene latices, h) acrylate latices.

16. Barrier paper according to at least one of the preceding claims, characterized in that the coating B2 has at least one of the following properties: a) protection of the barrier layer Bl against external influences, in particular mechanical or chemical influences, b) sealable, in particular heat-sealable, ultrasonically or cold-sealable, c) grease resistance, d) water resistance, e) moisture resistance, f) printability, g) additional barrier property.

17. Barrier paper according to at least one of the preceding claims, characterized in that the barrier paper has at least one of the following features: a) WVTR < 5 g / m² / d at 23°C and 50% relative humidity, b) WVTR inner fold < 5 g / m² / d at 23°C and 50% relative humidity, c) WVTR outer fold < 5 g / m² / d at 23°C and 50% relative humidity, d) WVTR < 15 g / m² / d at 38°C and 90% relative humidity, e) WVTR inner fold < 15 g / m² / d at 38°C and 90% relative humidity, f) WVTR outer fold < 15 g / m² / d at 38°C and 90% relative humidity, g) OTR < 10 g / m² 2 / d at 23°C and 50% relative humidity, h) OTR inner kink < 10 g / m 2 / d at 23°C and 50% relative humidity, i) OTR outer bend < 10 g / m 2 / d at 23°C and 50% relative humidity, j) kinking resistance of at least one barrier property, in particular in the area of ​​the inside kink and / or the outside kink, k) Residual moisture at least 2.5 wt.%, in particular at least 3.0 wt.% based on the total weight of the barrier paper.

18. Barrier paper according to at least one of the preceding claims, characterized in that the coating layer Sl, the barrier coating Bl and the coating B2 are removable in the waste paper cycle.

19. Barrier paper according to claim 18, characterized in that, after processing the barrier paper according to INGEDE method 11, the following scores according to the Assessment of Printed Product Recyclability, Deinkability Score, are achieved: a) brightness Y maximum 35 points, b) color coefficient a* in the CIELAB system maximum 20 points, c) dirt points A in the two different size classes A50 maximum 15 points and A250 maximum 10 points, d) degree of dye removal (printing ink removal) IE maximum 10 points and e) filtrate darkening AY maximum 10 points, wherein the sum of all points is in the range of 0 to 100, preferably in the range of 51 to 70, particularly preferably in the range of 71 to 100, and / or preferably no individual point value is negative.

20. Barrier paper according to at least one of the preceding claims, characterized in that a primer comprising at least one inorganic pigment and a polymeric binder is present between the base paper and the coating layer S1, wherein the inorganic pigment is preferably platelet-shaped and preferably comprises talc, precipitated calcium carbonate, a silicate, preferably a layered silicate or kaolin and / or that the polymeric binder comprises a polymeric binder based on a polyacrylate or styrene-butadiene.

21. Barrier paper according to at least one of the preceding claims, characterized in that the basis weight of the coating layer S1 and the coating B2 is in the range of 4 to 20 g / m² 2 , preferably from 4 to 15 g / m² 2 , based on the dried end product (Lutro).

22. Barrier paper according to any of the preceding claims, characterized by the fact that the barrier paper is free of halogenated organic compounds.

23. Barrier paper according to at least one of the preceding claims, characterized in that the base paper has a basis weight of 20 to 120 g / m² 2 , preferably from 40 to 100 g / m² 2 , exhibits.

24. Barrier paper according to at least one of the preceding claims, characterized in that the base paper has a long fiber content of 10 to 80% and a short fiber content of 20 to 90% by weight, wherein a long fiber is a fiber with a fiber length of 2.6 to 4.4 mm and a short fiber is a fiber with a fiber length of 0.7 to 2.2 mm.

25. Barrier paper according to at least one of the preceding claims, characterized in that the base paper comprises up to 90% recycled fibers.

26. Barrier paper according to at least one of the preceding claims, characterized in that the values ​​for the loss factor tan Delta measured by means of dynamic mechanical thermal analysis (DMTA) of the barrier paper as a function of temperature pass through a maximum at temperature Tg and a first inflection point at temperature Tw with increasing temperature.

27. Barrier paper according to claim 26, characterized in that the temperature Tg is lower than the temperature Tw.

28. Barrier paper according to claim 26 or claim 27, characterized in that the amount of the difference between tan Delta at temperature Tg and tan Delta at temperature Tw is > 0.013, preferably > 0.014 and particularly preferably > 0.

015.

29. A method for producing a barrier paper according to any of the preceding claims, characterized in that an aqueous suspension comprising the starting materials of the coating layer Sl is applied to the base paper, wherein the aqueous coating suspension has a solids content of 5 to 50 wt.%, preferably 10 to 30 wt.%, and is combined with a The coating is applied using a curtain coating process, preferably with a double curtain coating process, at an operating speed of the coating system of at least 200 m / min.

30. Use of the barrier paper according to any one of claims 1 to 25 or of the barrier paper obtainable by the method according to claim 26 as packaging material for food, consumer goods, tobacco products or as a component of packaging material, in particular packaging material based on cardboard or paperboard, especially as packaging material for food, in particular for sausage, cheese, coffee, muesli bars, chocolate, chocolate-containing products, snacks, chips.

31. Packaging comprising a barrier paper according to any one of claims 1 to 28 or of the barrier paper obtainable by the method according to claim 29, wherein the packaging is preferably a cold-sealed packaging, a heat-sealed packaging, an ultrasonically sealed packaging, in particular a tubular bag packaging.

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