EP3752673A1

EP3752673A1 - Heat-sealable barrier paper

Info

Publication number: EP3752673A1
Application number: EP19706430.6A
Authority: EP
Inventors: Lena-Maria Grundl; Nadia EL-KARZAZI; Dieter Becker; Konstantinos Kalessios; Jochen Schlegel
Original assignee: Mitsubishi HiTec Paper Europe GmbH
Current assignee: Mitsubishi HiTec Paper Europe GmbH
Priority date: 2018-02-13
Filing date: 2019-02-13
Publication date: 2020-12-23
Also published as: US20210002828A1; NZ766713A; CA3089434A1; AU2019221521A1; JP2021513010A; DE102019103343A1; CN111712599A; WO2019158566A1; US11371189B2; AU2019221521B2

Abstract

The invention relates to a heat-sealable barrier paper comprising or consisting of a) a carrier substrate, having a front side and a rear side opposite the front side, b) optionally an intermediate layer arranged on the front side of the carrier substrate, comprising a bonding agent, c) a first barrier layer arranged on the front side of the carrier substrate or, insofar as there is an intermediate layer, on the intermediate layer, comprising a cross-linked polysaccharide, d) a second barrier layer arranged on the first barrier layer, consisting of or comprising i) an acrylate-copolymer and/or ii) a vegetable oil-based wax. The invention further relates to the use of a barrier paper for packaging products, to a method for heat sealing a barrier paper according to the invention and to a method for producing a barrier paper.

Description

Heat-sealable barrier paper

The present invention relates to a heat-sealable barrier paper comprising or consisting of a) a carrier substrate, having a front side and a rear side opposite the front side, b) optionally an intermediate layer arranged on the front side of the carrier substrate, comprising a binder, c) one on the front side of the carrier substrate or, if an intermediate layer is present, a first barrier layer arranged on the intermediate layer, comprising a crosslinked polysaccharide, d) a second barrier layer arranged on the first barrier layer, consisting of or comprising i) an acrylate copolymer and / or ii) a wax based on a vegetable oil. The present invention further relates to the use of a barrier paper for the packaging of products, a method for heat-sealing a barrier paper according to the invention and a method for producing a barrier paper.

Lots of offered foods, such as sausage, cheese or baked goods, are usually handed over to customers in a packaging for reasons of hygiene or freshness. High demands are placed on the packaging, especially for fatty foods. When using conventional paper-based packaging, it is possible for fat-containing foods to penetrate the packaging material with the fat from the food. This may cause the packaging material to soften and tear or contaminate other items with the grease when in contact with the package. No. 8,557,0033 B2 describes a film-bonding composition comprising a hemicellulose. The films produced are characterized by a good liquid or moisture resistance.

In DE 10 2014 1 19 572 A1, a packaging paper for foodstuffs with a basis weight of between 20 g / m ² and 40 g / m ² , and with a mass fraction of filler, which is less than 20% based on the mass of the uncoated paper has, describe. The packaging paper has at least on one side a coating comprising a vegetable oil encapsulated in a polymer, talc and a binder. For the packaging of fatty foods is often a wood-free, grease-proof "sandwich paper" used, which has a certain grease resistance due to a greasy grinding of the fibers. Often, however, the grease resistance of these butter bread papers is not enough.

A greasy grind is achieved by wide, widely spaced knives or a basalt stone reinforcement with a long grinding time. The fibers are not cut but squeezed. The result is a strongly swelling fiber slime, a slippery-greasy substance that dehydrates only slowly on the paper machine. The paper gains high density but loses opacity. It gets translucent. Slight fiber shortening is referred to as "greasy-long." Stronger shortened fibers are termed "greasy-short." If the substrate is made predominantly greasy-short fibers, it has only a low tear and tear propagation resistance.

A more durable alternative to sandwich paper is often a composite packaging material. A composite packing material may for example consist of a composite material formed from a paper and a plastic and / or aluminum foil. If no polyethylene (PE) coating is used, fluorocarbons can be used as water repellent chemicals. In this case, for example, paper is coated on one side with polyethylene, often in an extrusion process, or on an aluminum foil. These composite packaging materials are characterized by a high grease resistance. However, these composite packaging materials can not be readily recycled for paper recycling, since first the film layer has to be removed. Nor is it possible to compost these composites because the plastic or aluminum foils used are not biodegraded. Growing concern over the shortage of fossil, non-renewable resources, such as coal (such as hard coal or lignite), oil or natural gas, has led to a growing interest in the production of materials from renewable resources. In this connection, reference may be made, for example, to polyethylene enfuranoate, a plastic based on 2,5-furandicarboxylic acid, or to polylactic acid (PLA), a plastic based on lactic acid, the starting substances of which can be prepared from sugars. However, it has been shown that the polymers known to date from renewable raw materials can either not be biodegraded or do not have the properties required for use in packaging materials.

The term "fossil raw materials" is understood as meaning gaseous, liquid and solid fuels which are composed of organic substances and which have been produced by conversion of biomass, especially since the Mesozoic era. They consist predominantly of carbon and hydrogen, but also contain oxygen, nitrogen and sulfur as well as mineral admixtures. The most important fossil raw materials are coal, oil and natural gas.

Renewable resources belong to the renewable resources. This refers to substances that come from living matter and are used by humans targeted for purposes outside the food and feed area. The requirements placed on the barrier paper of a high or defined resistance to penetration by fats, oils, water and water vapor and the good recyclability or biodegradability are requirements that are typically contradictory. There is therefore a great need in the industry to provide food packaging paper that can be made wholly or predominantly from renewable resources while being easily recycled or biodegraded.

In addition, it is desirable for the packaging of the products if the barrier paper is heat-sealable, ie it can be bonded to surfaces under the action of heat and possibly pressure. The object of the present invention is to provide a packaging material which has a low gas permeability, in particular for water vapor and / or oxygen. Another object of the present invention is to provide the packaging material so that it is suitable for contact with food and thereby has a high resistance and barrier effect against fats and / or oils and / or water or water vapor. A further object of the present invention is to design the packaging material such that it can be produced completely or predominantly from renewable raw materials. An additional object of the present invention is to make the barrier paper heat-sealable. In addition, it is desirable if the barrier paper can be recycled well and / or biodegraded, ie, composted.

These objects are achieved according to the invention by a heat-sealable barrier paper comprising or consisting of a) a carrier substrate having a front side and a rear side opposite the front side, b) optionally an intermediate layer arranged on the front side of the carrier substrate, comprising a binder, c) one the front side of the carrier substrate or, if an intermediate layer is present, a first barrier layer arranged on the intermediate layer, comprising a cross-linked polysaccharide, d) a second barrier layer arranged on the first barrier layer, consisting of or comprising i) an acrylate copolymer and / or ii) a wax based on a vegetable oil.

Surprisingly, it has been shown in own investigations that the combination of a first barrier layer comprising a crosslinked polysaccharide and a second barrier layer consisting of or comprising an acrylate copolymer, a wax based on a vegetable oil or a mixture of acrylate copolymer and a wax based on a vegetable oil, a particularly low gas permeability, in particular to water vapor and oxygen, and also have has a particularly good barrier effect against fats, oils and water. In the process, our own investigations have shown that the combination of the first and the second barrier layer has a synergistic barrier effect, which is not only due to the presence of two layers or the resulting thickness of both layers.

In barrier papers according to the invention, it is possible to completely dispense with the use of extruded films or on vapor-deposited or bonded metal foils, since the individual layers of the barrier paper according to the invention can be produced by the application of dispersions. The individual layers of the barrier paper according to the invention are not extruded.

Under a wax based on a vegetable oil is understood in the context of this invention, a wax, which is obtained by chemical modification of a vegetable oil. The chemical modification may be, for example, a partial or complete hydrogenation with a metallic catalyst, for example nickel, and hydrogen, all or part of the double bonds of the oil being hydrogenated to single bonds. Unlike vegetable oils, the waxes are not liquid at 20 ° C, but solid. The chemical modification of the vegetable oil thus causes a melting point increase.

By a vegetable oil is meant a fatty acid triglyceride derived from plants or parts of plants. The extraction of the oil is usually carried out by pressing, extraction or refining of the oils from the plants or parts of plants. The extraction of the oils is known to the skilled person. If plant seeds are used for oil production, they are referred to as oilseeds. In the seeds, the oil occurs in the form of lipids, which represent its cell membrane and energy reserves. Depending on the proportion of unsaturated fatty acids in the oil, a distinction is made between non-drying (for example olive oil), semi-drying (for example soybean or rapeseed oil) and drying oils (for example linseed or poppy seed oil). The term "drying" does not denote evaporation, but the solidification of the oil due to oxidation and polymerization of the unsaturated fatty acids. The use of semi-drying and drying oils as starting material for the production of the waxes used according to the invention is preferred.

Possible sources of vegetable oil are agai oil, algae oil, argan oil (from the fruits of the argan tree), avocado oil (from the avocado flesh of the avocado tree), Babagu oil, cottonseed oil (from the seeds of the cotton plant), borage oil or borage seed oil (from the seeds of the borage plant), cupuagu butter, cashew peel oil, thistle oil (also called "safflower oil", from the seeds of safflower or carthamus), peanut oil (ex the fruit of the peanut plant), hazelnut oil (from the hazelnuts of the hazelnut bush), hemp oil (from the seeds of the edible hemp), jatropha oil (from the seed of the Jatropha curcas), jojoba oil (actually a liquid wax, from the seeds of the jojoba shrub), camellia oil ( from the seeds of Camellia oleifera, Camellia sinensis or Camellia japonica, cocoa butter, coconut oil (from coconut seed, coconut palm tree fruit), pumpkin seed oil (also referred to as seed oil, from the seed kernels of Styrian oil pumpkin), linseed oil (from mature flaxseed of the flax), camelina oil (from the seeds of the Leindotter, family of the Kreuzblütengewächse), Macadamiaöl (from the nuts of the Macadamiabaums), Maiske oil (from the germs of maize), almond oil (from the almonds of the almond tree), mango butter (from Mangifera indica), apricot kernel oil or apricot kernel oil (from the apricot kernel - the apricot or apricot), poppy seed oil (from the seeds of the poppy), evening primrose oil, olive oil (from the pulp and the kernel of the olive, the fruit of the olive tree, palm oil (from the pulp of the palm fruit, the fruit of the oil palm), palm kernel oil (from the kernels of the palm fruit, the fruit of the oil palm ), Papaya oil, pistachio oil, pecan oil, perilla oil from the seeds of the perilla plant (shiso, sesame leaf), rapeseed oil (from the seed of rapeseed, family of the cruciferous plants), rice oil, castor oil (from the seed of the miracle tree), sea buckthorn oil (from the pulp of the sea-buckthorn berry, the fruit of the sea-buckthorn shrub), sea-buckthorn seed oil (from the cores of the sea-buckthorn berry, the fruit of the buckthorn shrub), mustard oil (from the seeds of the black mustard), black-k corn oil (from the seeds of the blackcurrant seed capsule), sesame oil (from the seeds of the sesame plant), shea butter (from the seeds of the shea tree), soybean oil (from the beans of the soybean), sunflower oil (from the sunflower seeds), tung oil, walnut oil (from kernels of nuts of walnut tree), watermelon seed oil, grapeseed oil (from kernels of fruit (grape) of grapevine or grapevine), wheat germ oil (from germs of wheat) and / or cedar oil (from wood of cedar Lebanon) , This list is not to be regarded as completed, it shows ways to obtain vegetable oils, which can be converted to a wax used in the invention.

According to the invention, a barrier paper is preferred, the wax based on a vegetable oil being an oil-based wax selected from the list comprising palm oil, coconut oil, poppy seed oil, olive oil, linseed oil, soybean oil, sunflower oil, Thistle oil and rapeseed oil, preferably the wax based on a vegetable oil is a wax based on a soybean oil, ie soybean oil wax or soya wax.

Our own investigations have shown that waxes of the oils mentioned above as being preferred have particularly good properties. The waxes produced from these oils (in particular soybean oil) are characterized by high resistance and can be produced with high melting points. The waxes used according to the invention, namely palm oil wax, coconut oil wax, poppy seed wax, olive oil wax, linseed oil wax, soybean oil wax, sunflower oil wax, thistle oil wax and rapeseed oil wax, show a significant increase in the resistance to fats and / or oils and / or moisture when used in barrier papers according to the invention. In particular, the use of soybean oil wax is preferred according to the invention. Our own investigations have shown that the use of soybean oil wax in addition to the resistance to grease, oil and moisture and very low water vapor permeability can be obtained. The soybean oil wax also has the advantage that it can be produced tasteless and odorless.

Barrier papers are preferred according to the invention, the wax having a melting point above 40 ° C., preferably above 50 ° C., particularly preferably above 60 ° C.

Our own investigations have shown that when using waxes with a melting point of more than 20 ° C already very good results can be obtained. However, it has surprisingly been found that when using waxes with a melting point above 40 ° C, the resistance of the barrier papers to mechanical stress can be increased. This resistance is further increased at even higher melting points of the waxes. Our own investigations have also shown that the optimum melting point of the waxes is in the range of 60 to 80 ° C, if the barrier papers are to be used at temperatures between 6 ° C and 30 ° C. If the barrier papers are also to be used at higher temperatures, it may be useful to use a wax with a higher melting point.

According to the invention, barrier papers are preferred, the mass fraction of the wax in the second barrier layer being from 6 to 98%, preferably from 20 to 90%, particularly preferably from 50 to 89%, based on the total mass of the barrier layer. Our own investigations have surprisingly shown that at a wax mass fraction of less than 6%, the barrier properties over fat, oil and moisture decrease disproportionately strong while at a wax mass fraction of about 98% excellent barrier properties can be obtained, however, the mechanical resistance of the barrier layer disproportionately decreases. Own investigations have shown that particularly good barrier papers with optimum barrier and mechanical properties can be obtained when the wax mass fraction is 50 to 89%.

Our own investigations have shown that it is advantageous if, in addition to the wax, a polymeric binder is present in the second barrier layer. As polymeric binders which may be present in the second barrier layer next to the wax, all binders customary in papermaking are suitable. Our own investigations have shown, however, that a suitable selection of the polymeric binder can significantly improve the mechanical properties of the barrier layer and / or the biodegradability of the barrier paper. Our own investigations have shown that it is advantageous and thus preferred according to the invention if the polymeric binder which can be present in the second barrier layer next to the wax is a crosslinked or uncrosslinked binder selected from the group consisting of starch, polyvinyl alcohol , carboxyl group-modified polyvinyl alcohol, ethylene-vinyl alcohol copolymer, a combination of polyvinyl alcohol and ethylene-vinyl alcohol copolymer, ethylene-vinyl acetate copolymer, silanol group-modified polyvinyl alcohol, diacetone-modified polyvinyl alcohol, modified polyethylene glycol, unmodified polyethylene glycol, a-isodecyl-u hydroxy-poly (oxy-1,2-ethanediyl), styrene-butadiene latex, styrene-acrylate polymers, acrylic copolymers, and mixtures thereof.

In a particularly preferred embodiment of the present invention, the second barrier layer consists of or the second barrier layer comprises an acrylate copolymer and a wax based on a vegetable oil.

Our own investigations have shown that barrier papers according to the invention have a particularly high resistance to grease, oil and moisture, if the polymeric binder which can be present in the second barrier layer next to the wax is one or more styrene-acrylate polymers or the binder comprises these. It has been shown that waxes based on a vegetable oil, and in particular wax based on soybean oil, interact particularly well with acrylate copolymers. By combining the acrylate copolymer with a vegetable oil-based wax, improved barrier layer properties can be obtained which can not be obtained by a combination of an acrylate copolymer with other waxes. Without wishing to be bound by any particular theory, it is believed that waxes based on a vegetable oil can interact with the acrylate copolymer due to the high content of unsaturated fatty acids and the high density of double bonds. Although more waxes can be added, very good barrier layers are obtained when acrylate copycerers and waxes based on a vegetable oil are used in the barrier layer.

It is inventively preferred if the mass fraction of the polymeric binder, which is present in addition to the wax in the second barrier layer in the second barrier layer 94 to 2%, preferably 80 to 10%, more preferably 50 to 1 1% , based on the total mass of the second barrier layer.

Our own investigations have shown that a content of polymeric binders, which are present in addition to the wax in the second barrier layer below a mass fraction of 2% leads to barrier papers in which the mechanical resistance of the second barrier layer decreases disproportionately. With a content of polymeric binders above a mass fraction of 94%, the mechanical resistance of the second barrier layer is sufficiently high, but it has been shown that the barrier properties to fat, oil and moisture disproportionately decrease. In the process, our own investigations have shown that particularly good barrier papers with optimum barrier and mechanical properties can be obtained if the content of polymeric binders is 50-1 1% by mass.

It is particularly preferred according to the invention when the mass fraction of the polymeric binder in the second barrier layer is 94 to 2% and the mass fraction of the wax in the second barrier layer is 6 to 98% and it is even more preferred if the mass fraction of the polymeric binder in the second barrier layer is 80 to 10% and the mass fraction of the wax in the second barrier layer is 80 to 90%, and it is even more preferable if the mass fraction of the polymeric binder in the barrier layer is 50 to 1 1% and the weight percentage of the wax in the second barrier layer is 50 to 89%. Our own investigations have shown that it is particularly advantageous if the polymeric binder, which may be present in the second barrier layer next to the wax, consists of two or more binders and at least one binder is an anionic binder. An anionic binder is understood to mean a binder which contains a plurality of negative charges which are stabilized by cations (eg metal cations or ammonium).

It is inventively preferred if the determined by differential scanning calorimetry (DSC) glass transition temperature of the anionic binder is less than or equal to 120 ° C. Our own investigations have shown that at a glass transition temperature of more than 120 ° C, the production of the second barrier layer is very difficult and the barrier papers produced do not have as good properties as barrier papers according to the invention, using an anionic binder with a glass transition temperature of less than or equal to 120 ° C were produced.

It is preferred according to the invention if the anionic binder present in the second barrier layer next to the wax is a copolymer.

Suitable anionic binders which are present in addition to the wax in the second barrier layer are, for example, partially or completely deprotonated polyacrylic acid (or copolymers thereof, for example with acrylic acid esters), partially or completely deprotonated polymethacrylic acid (or copolymers thereof, for example with methacrylate esters), copolymers of Polyacrylic acid esters (preferably methyl or ethyl esters), copolymers of polymethacrylic acid esters (preferably methyl or ethyl esters) or polyacrylamides or copolymers thereof.

It is inventively preferred if an aqueous solution or dispersion of the anionic binder, which is present in addition to the wax in the second barrier layer, has a basic pH, provided that it is dissolved or dispersed in water at a mass fraction of 10%, preferably in the range from 8 to 10%.

In order to determine the pH of the anionic binder, an aqueous solution or dispersion of the anionic binder can be prepared which has a mass fraction of 10% and the pH can be determined by conventional means. In the context of the present invention, a polymeric binder is understood to mean a binder which has been built up by polycondensation from a large number of molecules, and in which one or more types of atoms or atomic groups (so-called repeat units) are lined up repeatedly and the number repeating units per molecule is more than 25.

A barrier paper according to the invention is preferred, wherein the binder in the intermediate layer is starch or a synthetic polymer, preferably a binder selected from the group comprising starch, styrene-butadiene latex, polyvinyl alcohol, carboxyl group-modified polyvinyl alcohol, ethylene-vinyl alcohol copolymer, silane. polyol-modified polyvinyl alcohol, acetoacetyl-modified polyvinyl alcohol, diacetone-modified polyvinyl alcohol, acrylate copolymer and acrylic film-forming copolymer.

It is particularly preferred according to the invention if the binder in the intermediate layer is a synthetic polymer based on acrylic ester (preferably methyl acrylate or ethyl acrylate), styrene and acrylonitrile.

In a preferred embodiment of the present invention, the second barrier layer comprises one or more polymers selected from the group consisting of acrylic acid-acrylamide copolymer (poly (acrylic acid-co-acrylamide), acrylic acid-acrylic ester-acrylonitrile copolymer, acrylic acid ethyl ester-carboxylic acid Copolymer, acrylic acid ethyl ester-acrylic acid copolymer, ethyl acrylate-carboxylic acid copolymer, ethyl acrylate-acrylic acid copolymer, polymethyl methacrylate and alkali or alkaline earth metal salts (preferably sodium salts) of the aforementioned polymers to 1.0%, preferably 0.10 to 0.30%, more preferably 0.14 to 0.20%, based on the solids content of the second barrier layer.

In a particularly preferred embodiment of the present invention, the second barrier layer comprises an acrylic acid-acrylamide copolymer (poly (acrylic acid-co-acrylamide) and / or an and alkali or alkaline earth metal salt of an acrylic acid-acrylamide copolymer (preferably the sodium salt of acrylic acid-acrylamide Here, it is preferred if the mass fraction of acrylic acid-acrylamide copolymer is from 0.1 to 1.0%, preferably 0.10 to 0.30%, more preferably 0.14 to 0.20% , based on the solids content of the second barrier layer Preferably, the acrylic acid-acrylamide copolymer is a random copolymer.

When barrier papers are folded, especially with two cross-folds, the grease resistance of the barrier paper decreases significantly in the fold area and especially in the cut area of two or more folds, as the barrier effect of the barrier paper decreases due to the fold. Our own investigations have surprisingly shown that the addition of polymers selected from the group consisting of acrylic acid-acrylamide copolymer (poly (acrylic acid-co-acrylamide), acrylic acid-acrylic ester-acrylonitrile copolymer, acrylic acid ethyl ester-carboxylic acid copolymer, acrylic acid ethyl ester-acrylic acid- Copolymer, ethyl acrylate-carboxylic acid copolymer, ethyl acrylate-acrylic acid copolymer, polymethyl methacrylate and alkali or alkaline earth metal salts (preferably sodium salt) of the aforementioned polymers can significantly improve the grease resistance of a barrier paper according to the invention in the rebate area of the barrier paper .. The grease resistance is positive of all polymers listed above wherein the use of an acrylic acid-acrylamide copolymer or the sodium salt of the acrylic acid-acrylamide copolymer leads to particularly good grease resistance in the fold region of the barrier paper.

A further aspect of the present invention relates to the use of one or more polymers for improving the grease resistance of a (barrier) paper (preferably a barrier paper according to the invention) in the fold region of the (barrier) paper, wherein the one or more polymers are selected from of the group consisting of acrylic acid-acrylamide copolymer (poly (acrylic acid-co-acrylamide), acrylic acid-acrylic ester-acrylonitrile copolymer, acrylic acid ethyl ester-carboxylic acid

Copolymer, acrylic acid ethyl ester-acrylic acid copolymer, ethyl acrylate-carboxylic acid copolymer, ethyl acrylate-acrylic acid copolymer, polymethyl methacrylate and alkali or alkaline earth metal salts (preferably sodium salts) of the aforementioned polymers, preferably acrylic acid-acrylamide copolymer (poly (acrylic acid-co-acrylamide) and the sodium salt of acrylic acid-acrylamide copolymer (poly (acrylic acid-co-acrylamide).

A barrier paper according to the invention is preferred, the intermediate layer comprising, in addition to the binder, a pigment, preferably comprising an inorganic pigment, more preferably selected from the group comprising natural or calcined aluminum silicate (in particular natural or calcined kaolinite or natural or calcined kaolin), magnesium silicate hydrate (talc) , Aluminum hydroxide (especially boehmite), bentonite, calcium carbonate and silica (silica). It is particularly preferred according to the invention if the pigment in the intermediate layer is platelet-shaped. Our own investigations have shown that platelet-shaped pigments further improve the barrier effect of the resulting barrier paper. It is assumed that platelet-shaped pigments store one above the other in the intermediate layer and thereby form individual pigment layers. The individual pigment layers of platelet-shaped pigments are in this case poets or have a higher barrier effect than, for example, spherical pigments.

It is particularly preferred if platelet-shaped pigments in the intermediate layer have an (average) aspect ratio of from 3 to 100, preferably from 5 to 95, particularly preferably from 10 to 90. In a preferred embodiment, the (preferably average) aspect ratio of the pigment is greater than 15. The aspect ratio (also called "aspect ratio" or "shape factor") is the quotient between the diameter and the thickness of the platelet of the inorganic Pigments before mixing with the other components. An aspect ratio of 15 means that the diameter of the plate is 15 times larger than the thickness of the plate.

A barrier paper according to the invention is preferred, wherein the intermediate layer i) contains a mass fraction in the range from 50 to 90% pigment, preferably contains 60 to 80% pigment, more preferably contains 65 to 75% pigment and ii) has a mass fraction in the range from 10 to 50 Contains% binder, preferably 20 to 40% binder, more preferably 25 to 35% binder, in each case based on the total mass of the intermediate layer. In a likewise preferred embodiment of the present invention, the second barrier layer consists of or the second barrier layer comprises an acrylate copolymer and a wax based on saturated hydrocarbons. Barrier papers are preferred according to the invention, the wax having a melting point above 40 ° C., preferably above 50 ° C., particularly preferably above 60 ° C., based on saturated hydrocarbons.

Barrier papers are preferred according to the invention, the wax based on saturated hydrocarbons containing one, two, three or more than three alkanes or being selected from the group consisting of heneicosan, docosan, tricosane, tetracosane, pentacosane, hexacosane, heptacosane, octacosane, nonacosane, Triacontan, Hentriacontan, Dotriacontan, Tritriacontan, Tetratriacontan, Pentatriacontan, Hexatriacontan, Heptatriacontan, Octatriacontan and Nonatriacontan, preferably selected from the group consisting of hexacosan, heptacosan, octacosan, nonacosan and triacontane. Barrier papers are particularly preferred according to the invention, the wax based on saturated hydrocarbons being a wax based on octacosane.

According to the invention, the acrylate copolymer in the second barrier layer is a copolymer having an average molar mass in the range of 50,000 to 150,000 g / mol, preferably in the range of 80,000 to 130,000 g / mol, particularly preferably in the range of 90,000 up to 100,000 g / mol. The mean molar mass is determined with the aid of gel permeation chromatography (GPC) using tetrahydrofuran (THF; tetramethylene oxide, 1,4-epoxybutane, oxacyclopentane) as solvent, polystyrene as standard and detection using RI detector (refractive index detector).

According to the invention, the acrylate copolymer in the second barrier layer is a copolymer prepared using two, three, four, five, six or all monomers selected from the group consisting of methyl acrylate, methyl methacrylate, butyl acrylate, methacrylic acid butyl ester, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate and styrene.

By selecting the monomers used to prepare the acrylate copolymer, the properties of the resulting acrylate copolymer can be optimized. Surprisingly, our own investigations have shown that an acrylate copolymer prepared from methyl acrylate, methyl methacrylate, butyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate and / or styrene has particularly good barrier properties. In addition to methyl acrylate, methyl methacrylate, butyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate and styrene, further monomers may have been used to prepare the acrylate copolymer or the copolymer has been prepared from two, three, four, five , six or all monomers selected from the group consisting of methyl acrylate, methyl methacrylate, butyl acrylate, butyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate and styrene.

According to the invention, the acrylate copolymer is particularly preferably a random copolymer. Preferred according to the invention is a barrier paper, wherein, if there is no intermediate layer arranged on the front side of the carrier substrate, the second barrier layer i) comprises an acrylate copolymer and ii) a wax based on a vegetable oil and, if not arranged on the front side of the carrier substrate Intermediate layer is present, the second barrier layer i) comprises an acrylate copolymer or ii) a wax based on a vegetable oil.

Particularly preferred according to the invention is a heat-sealable barrier paper comprising or consisting of a) a carrier substrate, having a front side and a rear side opposite the front side, b) optionally an intermediate layer arranged on the front side of the carrier substrate, comprising a binder, c) one on the front side of the carrier substrate or, if an intermediate layer is present, a first barrier layer arranged on the intermediate layer, comprising a crosslinked polysaccharide, d) a second barrier layer arranged on the first barrier layer, consisting of or comprising i) an acrylate copolymer having an average molar mass in the range of 50,000 to 150,000 g / mol, wherein the acrylate copolymer was prepared from two, three, four, five, six or seven monomers selected from the A group consisting of methyl acrylate, methyl methacrylate, butyl acrylate, butyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate and styrene, and ii) a saturated hydrocarbon based wax, wherein the

Wax based on saturated hydrocarbons is octacosane or wherein the wax based on saturated hydrocarbons comprises octacosane.

In a likewise preferred embodiment of the present invention, the second barrier layer consists of or the second barrier layer comprises an acrylate copolymer and a wax based on saturated hydrocarbons and a wax based on a vegetable oil.

Also particularly preferred according to the invention is a heat-sealable barrier paper comprising or consisting of a) a carrier substrate, having a front side and a rear side opposite the front side, b) optionally an intermediate layer arranged on the front side of the carrier substrate, comprising a binder, c) one on the front side of the Carrier substrate or, if an intermediate layer is present, a first barrier layer arranged on the intermediate layer, comprising a crosslinked polysaccharide, d) a second barrier layer arranged on the first barrier layer, consisting of or comprising i) an acrylate copolymer having an average molar mass in the range of 50,000 to 150,000 g / mol, wherein the acrylate copolymer was prepared from two, three, four, five, six or seven monomers selected from the group consisting of methyl acrylate, methyl methacrylate, butyl acrylate, butyl methacrylate, Acrylic acid-2- ethylhexyl ester, 2-ethylhexyl methacrylate and styrene; and ii) a saturated hydrocarbon wax, wherein the saturated hydrocarbon wax is octacosane or wherein the saturated hydrocarbon wax comprises octacosane and iii) a wax-based wax a vegetable oil.

Also particularly preferred according to the invention is a heat-sealable barrier paper comprising or consisting of a) a carrier substrate, having a front side and a rear side opposite the front side, b) optionally an intermediate layer arranged on the front side of the carrier substrate, comprising a binder, c) one on the front side of the Carrier substrate or, if an intermediate layer is present, a first barrier layer arranged on the intermediate layer, comprising a cross-linked polysaccharide, d) a second barrier layer arranged on the first barrier layer, consisting of or comprising an acrylic acid-acrylamide copolymer and / or the sodium salt of one Acrylic acid-acrylamide copolymer (preferably with a mass fraction of acrylic acid-acrylamide copolymer of 0.1 to 1, 0%, preferably from 0.10 to 0.30%, particularly preferably from 0.14 to 0.20%, based on the solids content of the second barrier layer) and one, two or all components i) to iii) i) an acrylate copolymer having an average molar mass in the range of

50,000 to 150,000 g / mol, the acrylate copolymer consisting of two, three, four, five, six or seven monomers was selected from the group consisting of methyl acrylate, methyl methacrylate, butyl acrylate, butyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate and styrene, ii) a wax based on saturated hydrocarbons, wherein the

Wax based on saturated hydrocarbons for octacosane or wherein the wax based on saturated hydrocarbons octacosane comprises, iii) a wax based on a vegetable oil. In one embodiment of the barrier paper according to the invention, the carrier substrate is a paper, a cardboard or a cardboard. For the purposes of the present invention, paper, board and cardboard and sheet-like materials which can be produced from the same basic materials and, in principle, the same production methods are used. In the context of this invention, a distinction is made between paper, cardboard and cardboard only on the basis weight, cardboard has a grammage of more than 600 g / m ² , cardboard has a grammage of greater than 150 and less than 600 g / m ² and paper has a weight per square meter of less than or equal to 150 g / m ² . Irrespective of whether paper, cardboard or paperboard is used as the carrier substrate, the resulting product according to the invention is referred to as barrier paper in the context of the present invention, without this being intended to limit the weight per square meter. In the context of the present invention, the term barrier paper thus also includes the terms barrier board and barrier board, provided that no specification of the square meter weight is made.

A barrier paper according to the invention is preferred, wherein the carrier substrate contains a pulp having a Schopper-Riegler degree in the range of 24 to 54 ° SR, preferably in the range of 29 to 49 ° SR, more preferably in the range of 34 to 44 ° SR.

A barrier paper according to the invention is preferred, wherein the support substrate comprises or consists of a pulp comprising a short fiber pulp and a long fiber pulp. In this case, a ratio between short-fiber pulp and long-fiber pulp in the range of 2: 1 to 1: 2, preferably in the range of 1, 5: 1 to 1: 1, 5, more preferably of about 1: 1 preferred. It has been shown in own investigations that the combination of a short fiber pulp and a long fiber pulp with the Schopper-Riegler grades used according to the invention leads to a particularly dense paper which has a very high barrier effect to fat. This barrier effect can be improved even further if the Schopper-Riegler grade is in the ranges marked as preferred or particularly preferred or has the values marked as preferred or particularly preferred.

In one embodiment, the barrier paper according to the invention is a barrier paper, wherein the short fiber pulp is wholly or partially, preferably at least to a mass fraction of more than 50%, based on the total mass of short fiber pulp, from fibers of hardwoods, preferably birch fibers, beech fibers or eucalyptus fibers and the long-fiber pulp wholly or partly, preferably at least more than 50%, based on the total mass of the long-fiber pulp, consists of fibers of softwoods, preferably of pine fibers, Spruce fibers or fir fibers.

Our own investigations have shown that particularly good properties of the resulting barrier paper are obtained when the carrier substrate is made from a mixture of a short fiber pulp and a long fiber pulp and this mixture is leveled again before the preparation of the carrier substrate to the desired Schopper -Riegler degrees in the range of 24 to 54 ° SR, preferably in the range of 29 to 49 ° SR, more preferably in the range of 34 to 44 ° SR. The short fiber and long fiber pulps used before milling may have a Schopper-Riegler grade that is outside the preferred range, and the Schopper-Riegler grade of short fiber pulps and long fiber pulps used are preferably smaller before milling, than after grinding.

A barrier paper according to the invention is preferred, wherein the crosslinked polysaccharide is a crosslinked xylan or contains a crosslinked xylan, preferably a crosslinked arabinoxylan or contains a crosslinked arabinoxylan. In this case, a barrier paper is particularly preferred according to the invention, wherein the xylan is a xylan from wheat or barley peas. Although xylans from other plant sources are also very suitable, our own investigations have shown that xylans from wheat or barley pelts have a particularly good barrier effect against oxygen when used in the first barrier layer.

A barrier paper according to the invention is preferred in which the crosslinked polysaccharide is a mixture of crosslinked starch and crosslinked xylan. In this case, it is particularly preferred if a mixture of starch and xylan (preferably arabinoxylan) is crosslinked so that crosslinking also takes place between starch and xylan molecules. In this case it is particularly preferred if more starch than xylan is used, i. the amount of starch in the first barrier layer is higher than the xylan content. When considering the starch content and the xylan content, reference is made to the respective mass fractions prior to crosslinking. If necessary, if the proportions of a cross-linked product already have to be determined, a corresponding calculation of the originally present fractions is carried out on the basis of the determined proportion of D-glucose and D-xylose, which can be determined, for example, by NMR.

Own investigations have shown that barrier papers comprising a first and a second barrier layer have particularly good properties when the polysaccharide is crosslinked in the first barrier layer. If polysaccharides are used in the first barrier layer, which are not cross-linked, occurs during the orders of the second barrier layer, a resolution or dissolution of the first barrier layer. After the first barrier layer or the polysaccharides in the first barrier layer has been applied or dissolved, the polysaccharides are mixed with the components of the second barrier layer. As a result, barrier papers are obtained which have no distinct first and second barrier layers and which have poorer barrier properties (particularly with respect to the barrier to gases (especially oxygen)). According to the invention barrier papers are preferred in which the crosslinking of the polysaccharide was carried out with a crosslinking agent selected from the group consisting of zirconium carbonate, polyamidaminepichlorohydrin resins, boric acid, ammonium zirconium carbonate, methacrylate polymer, diacarboxylic acid, adipic acid, glutaric acid glyoxal, dihydroxy bis (ammonium lactato) titanium (IV) ( CAS No. 65104-06-5; Tyzor LA) and Glycol xalderivaten, preferably, the crosslinking agent is a glyoxal or a glyoxal derivative.

It is inventively preferred if the crosslinking by adding the crosslinking agent with a mass fraction of 0.05 to 1%, preferably 0, 1 to 0.45%, more preferably 0.35 to 0.425%, based on the total mass of all polysaccharides in the first barrier layer.

The carrier substrate, the intermediate layer, the first barrier layer and the second barrier layer may additionally contain additives commonly used in papermaking, such as sizing agents, pigments (in addition to the pigments already described above), optical brighteners, biocides, dispersants, release agents, defoamers, Retention aids, fixatives, flocculants, deodorizing agents, wetting agents, leveling agents, slimicides or thickeners. The additives are commonly used to adjust the properties of the coating compositions used to make the particular layer (eg, defoamers or retention aids) or to adjust the properties of the resulting layer (eg, optical brightener).

A barrier paper according to the invention is preferred, wherein

A) the basis weight of the paper substrate is 40 to 100 g / m ² , preferably 60 to 80 g / m ² , more preferably 65 to 75 g / m ² , and / or

B) the basis weight of the intermediate layer is 2 to 20 g / m ² , preferably 5 to 15 g / m ² , more preferably 8 to 12 g / m ² , and / or

C) the basis weight of the first barrier layer is 2 to 10 g / m ² , preferably 3 to 8 g / m ² , more preferably 5 to 6 g / m ² , and / or D) the basis weight of the second barrier layer is 1 to 20 g / m ² , preferably 7 to 15 g / m ² , more preferably 9 to 12 g / m ² , and / or

E) the basis weight of the barrier paper is 40 to 120 g / m ² , preferably 65 to 100 g / m ² , more preferably 80 to 95 g / m ² .

A barrier paper according to the invention is preferred, the carrier substrate having further layers on the back side. For example, the back may be coated with a starch layer, preferably modified starch, particularly preferably modified corn starch. A backside coating improves the properties of the barrier paper. For example, it is thus possible to ensure a backside printability of the barrier paper.

A barrier paper is preferred according to the invention, the barrier paper having a water vapor permeability according to DIN 53122-1 of less than or equal to 30 g / (m ² d), preferably less than or equal to 20 g / (m ² d), particularly preferably less than or equal to 15 g / ( m ² d). Surprisingly, it has been found that the barrier paper according to the invention not only has a very high resistance to grease, but also a low water vapor permeability. A low water vapor permeability in packaging is desirable in food, as the packaged food does not dry out prematurely and stay fresh longer. A barrier paper is preferred according to the invention, wherein the barrier paper has a KIT value of at least 7, preferably of at least 11, more preferably of at least 12; measured by method Tappi 559.

Our own investigations have shown that barrier papers according to the invention can have a KIT value of more than 12 and thus show an excellent bed stability, which lies in the same range as the grease resistance of barrier papers coated with plastic or aluminum foil.

It is inventively preferred if the barrier paper does not comprise plastic or aluminum foils. In particular, it is preferred if the barrier paper according to the invention does not comprise extruded plastic films or plastic films. It is According to the invention, it is particularly preferred if the barrier paper does not comprise plastic films of polyethylene terephthalate (PET), polyethylene (PE), flexible polyethylene (LDPE) or polyethylene (PE).

A barrier paper is preferred according to the invention if the barrier paper has a fat permeability with Tappi 454 turpentine oil of at least 1300 s, preferably of at least 1500 s, more preferably of at least 1800 s.

According to the invention, a barrier paper is preferred, the barrier paper having a fat permeability of at least Level 5, preferably of at least Level 3, particularly preferably of at least Level 1; measured according to method DIN 531 16. A barrier paper is preferred according to the invention, the barrier paper having an oxygen permeability according to DIN 53880-3 of less than or equal to 90 cm ³ / (m ² d), preferably less than or equal to 70 cm ³ / (m ² d), especially preferably less than or equal to 50 cm ³ / (m ² d).

A barrier paper is preferred according to the invention, the barrier paper having a hexane vapor permeability at 23 ° C. and 50% rH of less than or equal to 70 g / (m ² d), preferably less than or equal to 60 g / (m ² d), particularly preferably less than or equal to 50 g / (m ² d).

It is preferred according to the invention if the barrier paper on the second barrier layer has a Bekk smoothness determined in accordance with ISO 5627 in the range from 10 to 1200 s, provided that the second barrier layer is an outer layer. In contrast to ISO 5627, the Bekk smoothness in this case is not determined on both sides of the barrier paper, but only on the second barrier layer of the barrier paper.

Another aspect of the present invention relates to the use of a barrier paper according to the invention as wrapping paper, pouches, sachets, backing paper, inter- and / or release paper, preferably for food, preferably for wrapping, lining, interposing and / or separating baked goods, fried and / or fried goods, snack foods, sandwiches, bread, burgers, meat products, sausages and / or cheese.

In addition, own investigations have shown that in addition to the use of the barrier paper according to the invention in the foodstuffs sector, use in the "non- food "area is possible. Own investigations have shown that in particular the packaging of flavored articles is possible. Barrier papers according to the invention have a high barrier action to gaseous or vaporized flavorings and aroma oils. The use of a barrier paper according to the invention as wrapping paper, pouches, sachets, backing paper, intermediate and / or release paper for products other than food, such as ink cartridges, electronic components or ink pads, is possible according to the invention.

A further aspect of the present invention relates to a method for heat-sealing a barrier paper according to the invention, comprising the following steps:

Providing a barrier paper according to the invention,

Placing the provided barrier paper according to the invention on a surface so that at least part of the second barrier layer rests on the surface, pressing the barrier paper resting on the surface under the influence of heat, so that the second barrier layer at least in the surface resting on the surface into the molten Condition is heated,

Reducing the pressure and the action of heat, so that cool the layer in the molten state. Another aspect of the present invention relates to a process for producing a barrier paper, preferably a barrier paper according to the invention, comprising the following steps

Providing or producing a carrier substrate, comprising a front side and a rear side opposite the front side, providing or producing an intermediate layer

Coating composition, said interlayer coating composition comprising a binder, Applying the interlayer coating composition to the front side of the substrate,

Drying and / or crosslinking of the applied interlayer

Coating composition such that an intermediate layer is formed, providing or producing a first barrier

A coating composition, said first barrier coating composition comprising a polysaccharide and a crosslinking agent and / or a crosslinked polysaccharide,

Applying the first barrier coating composition to the intermediate layer,

Drying and / or crosslinking of the applied first barrier

Coating composition, so that a first barrier layer is formed,

Providing or preparing a second barrier coating composition consisting of or comprising i) an acrylate copolymer and / or ii) a vegetable oil-based wax applying the second barrier coating composition to the first barrier layer,

Applying the second barrier coating composition to the first barrier layer,

Drying and / or crosslinking of the applied second barrier

Coating composition, so that a second barrier layer is formed. In the context of the present invention, preferably several of the aspects described above as being preferred are realized simultaneously; Especially preferred are the combinations of such aspects and the corresponding features resulting from the appended claims. With regard to the coating composition used in a method according to the invention for the production of a barrier paper, reference is hereby made to the comments on the composition of the individual layers. The coating compositions are designed such that the resulting layers in a barrier paper according to the invention result. In this case, the coating compositions are usually in the form of an aqueous dispersion and contain the constituents or compounds present in the individual layers (for example monomers or crosslinking agents) which react with the constituents.

In addition, the coating compositions may also contain additives commonly used in papermaking, such as biocides, dispersants, release agents, defoamers, or thickeners, which are added to adjust the properties of the coating composition and usually remain in the layer made from the coating composition. Here, additives commonly used in papermaking can be used in the usual amounts. For the application of the coating composition to the carrier substrate or a layer already present on the carrier substrate (eg intermediate layer or first barrier layer), the person skilled in the art knows various techniques which are referred to as brushing, for example: blading, brushing with film press, cast coating, curtain coating (" Curtain Coating "), knife coating, air brushing or spray painting. All of these known abovementioned coating techniques are suitable for applying the coating composition according to the invention to a carrier substrate, preferably a paper substrate which comprises one or more precursors or which also comprises no precoat or intermediate coat. In accordance with the invention, preference is given to curtain coating ("curtain coating"). The barrier paper according to the invention is preferably at least biodegradable.

Biodegradability is defined so that a material can be biodegraded under anaerobic or aerobic conditions, so that in this process each after environmental conditions CO2, H2O, methane, biomass and mineral salts are released. Naturally occurring microorganisms, which mainly feed on organic waste, play an important role here.

The barrier paper according to the invention is preferably compostable. Composting describes the decomposition process of organic waste via microbial digestion for the production of compost. Compost is of many uses, for example to improve and fertilize the soil. For the composting process, the organic waste needs the right temperature and the right amount of water and oxygen. In a pile of organic waste, there are millions of tiny microbes that allow them to migrate through their digestive system, turning organic materials into compost.

Both specifications require that a biodegradable / compostable barrier paper be completely degraded, within a set timeframe, and without leaving any environmentally harmful residues. The barrier paper according to the invention is particularly preferably recyclable.

The recycling of material residues is understood to mean a return of matter used in production or consumption.

The invention will be further explained below by way of examples.

Examples: Example 1

The carrier substrate used was a paper substrate which consisted of a 1: 1 mixture of short fiber and long fiber pulp with a grinding of 39 ° SR and an additive with a mass fraction of 1% talc as filler, based on the total mass of the paper substrate, on a paper machine mass-produced resin-sizing paper web having a basis weight of 70 g / m ^{2 was} prepared. The prepared paper substrate was calendered at a line load of 80 kN / m and a temperature of 80 ° C. Using a nozzle applicator unit and a doctor blade was at the front, an intermediate layer coating composition that was present as an aqueous dispersion, coated, and this coating composition was then using IR, air drying and drying cylinder dried, so that an intermediate layer having a basis weight of 10 g / m ² resulted. The composition of the interlayer coating composition (excluding water) is shown in Table 1.

Using an air brush, a first barrier coating composition, which was in the form of an aqueous dispersion, was applied to the prepared intermediate layer, and this coating composition was then dried by means of IR and air drying to give a first barrier layer having a basis weight of 5.5 g / m ² resulted. The composition of the first barrier coating composition (excluding water) is given in Table 1. Using a volumetric squeegee, a second barrier coating composition, which was present as an aqueous dispersion, was applied to the prepared first barrier layer, and this coating composition was then dried by IR and air drying to provide a second barrier layer having a basis weight of 9.5 g / m ² resulted. The composition of the second barrier coating composition (excluding water) is shown in Table 1.

The resulting barrier paper, which was heat-sealed at 120 ° C, had a basis weight of 95 g / m ² and was measured for its properties. The results are summarized in Table 2. Table 1 :

Table 2:

Claims

Claims:

A heat-sealable barrier paper comprising or consisting of a) a carrier substrate having a front side and a rear side opposite the front side, b) optionally an intermediate layer arranged on the front side of the carrier substrate, comprising a binder, c) one on the front side of the carrier substrate or, if provided an intermediate layer is present, a first barrier layer arranged on the intermediate layer, comprising a cross-linked polysaccharide, d) a second barrier layer arranged on the first barrier layer, consisting of or comprising i) an acrylate copolymer and / or ii) a wax based on a vegetable oil ,

2. Barrier paper according to claim 1, wherein the crosslinked polysaccharide is a crosslinked

Xylan or contains a cross-linked xylan, preferably a cross-linked arabinoxylan or contains a cross-linked arabinoxylan.

3. Barrier paper according to one of the preceding claims, wherein the second barrier layer comprises an i) acrylate copolymer and ii) a wax based on a vegetable oil.

The barrier paper of any one of the preceding claims wherein the second barrier layer comprises an acrylate copolymer and a saturated hydrocarbon based wax.

5. Barrier paper according to one of the preceding claims, wherein the second barrier layer comprises an i) acrylate copolymer, ii) a wax based on a vegetable oil and iii) a wax based on saturated hydrocarbons.

6. Barrier paper according to one of the preceding claims, wherein the wax based on a vegetable oil is an oil-based wax selected from the list comprising palm oil, coconut oil, poppy oil, olive oil, linseed oil, soybean oil, sunflower oil, thistle oil and rapeseed oil.

7. Barrier paper according to one of the preceding claims, wherein the wax based on a vegetable oil is a wax based on soybean oil.

8. Barrier paper according to one of claims 4 to 7, wherein the wax based on saturated hydrocarbons contains one or two, three or more than three alkanes selected from the group consisting of heneicosan, docosan, tricosane, tetracosane, pentacosane, hexacosan, Heptacosan, Octacosan, Nonacosan, Triacontan, Hentriacontan, Dotriacontan, Tritriacontan, Tetratriacontan, Pentatriacontan, Hexatriacontan, Heptatriacontan, Octatriacontan and Nonatriacontan, preferably selected from the group consisting of Hexacosan, Heptacosan, Octacosan, Nonacosan and Triacontan.

A barrier paper according to any one of claims 4 to 8, wherein the wax based on saturated hydrocarbons is octacosane.

Barrier paper according to one of the preceding claims, wherein the paper substrate contains a pulp having a Schopper-Riegler degree in the range of 24 to 54 ° SR, preferably in the range of 29 to 49 ° SR, more preferably in the range of 34 to 44 ° SR.

1 1. Barrier paper according to one of the preceding claims, wherein the barrier paper has a KIT value of at least 7, preferably of at least 1 1, more preferably of at least 12; measured by method Tappi 559.

12. Barrier paper according to one of the preceding claims, wherein

A) the basis weight of the paper substrate is 40 to 100 g / m ² , preferably 60 to 80 g / m ² , more preferably 65 to 75 g / m ² , and / or B) the basis weight of the intermediate layer is 2 to 20 g / m is ² , preferably 5 to 15 g / m ² , more preferably 8 to 12 g / m ² , and / or

C) the basis weight of the first barrier layer is 2 to 10 g / m ² , preferably 3 to 8 g / m ² , more preferably 5 to 6 g / m ² , and / or

D) the basis weight of the second barrier layer is 1 to 20 g / m ² , preferably 7 to 15 g / m ² , more preferably 9 to 12 g / m ² , and / or

13. Barrier paper according to one of the preceding claims, wherein the intermediate layer comprises, in addition to the binder, a pigment, preferably an inorganic pigment, more preferably selected from the group comprising natural or calcined aluminum silicate (in particular natural or calcined kaolinite or natural or calcined kaolin) , Magnesium silicate hydrate (talc), aluminum hydroxide (especially boehmite), bentonite, calcium carbonate and silica (silica).

14. Barrier paper according to one of the preceding claims, wherein the binder in the intermediate layer is starch or a synthetic polymer, preferably a binder selected from the group comprising starch, styrene-butadiene latex, polyvinyl alcohol, carboxyl group-modified polyvinyl alcohol, ethylene Vinyl alcohol copolymer, silanol group-modified polyvinyl alcohol, acetoacetyl-modified polyvinyl alcohol, diacetone-modified polyvinyl alcohol, acrylate copolymer and acrylic film-forming copolymer.

15. Barrier paper according to one of the preceding claims, wherein the carrier substrate is a paper, a cardboard or a cardboard.

16. Barrier paper according to one of the preceding claims, wherein the second barrier layer additionally comprises iv) an acrylic acid-acrylamide copolymer and / or a sodium salt thereof.

17. Barrier paper according to claim 16, wherein the mass fraction of acrylic acid-acrylamide copolymer 0, 1 to 1, 0%, preferably 0.10 to 0.30%, more preferably 0.14 to 0.20%, based on the solids content of the second barrier layer.

18. Use of a barrier paper according to one of claims 1 to 17 as wrapping paper, bags, sachets, backing paper, intermediate and / or release paper for products, preferably for wrapping, lining, interposing and / or

Separating baked goods, fried and / or fried goods, snack foods, sandwiches, bread, burgers, meat products, sausages and / or cheese.

19. heat sealing a barrier paper according to one of claims 1 to 17 comprising the following steps - providing a barrier paper according to the invention,

Placing the provided barrier paper according to the invention on a surface such that at least part of the second barrier layer rests on the surface,

Pressing the barrier paper resting on the surface under the influence of heat, so that the second barrier layer is heated up to the molten state, at least in the part resting on the surface, Reducing the pressure and the action of heat, so that cool the layer in the molten state.

20. A method for producing a barrier paper, preferably according to one of claims 1 to 17, comprising the following steps - providing or producing a paper substrate comprising a front side and a rear side opposite the front side,

Providing or producing an interlayer coating composition, said interlayer coating composition comprising a binder, applying said interlayer coating composition to said substrate

Front of the substrate,

Drying and / or crosslinking the applied interlayer coating composition such that an intermediate layer is formed, providing or producing a first barrier layer

Applying the first barrier coating composition to the intermediate layer,

Drying and / or crosslinking the applied first barrier coating composition such that a first barrier layer is formed,

Providing or preparing a second barrier coating composition consisting of or comprising i) an acrylate copolymer and / or ii) a wax based on a vegetable oil, applying the second barrier coating composition to the first barrier layer, drying and / or crosslinking the applied second barrier layer,

Coating composition, so that a second barrier layer is formed.