Barrier coatings for paper and paperboard

Abstract

The present invention relates to an aqueous barrier coating composition comprising: 50-99.9 wt. % of one or more anionic low molecular weight polysaccharides having a degree of polymerization (DP) in the range of 2-12; 0.1-10 wt. % of a polycationic polymer; based on the total dry weight of the aqueous barrier coating composition.

Description

Technical Field

[0001] The present disclosure relates to a coating for coating a fiber-based substrate, such as paper or paperboard, to improve its barrier properties, particularly oxygen and grease barrier properties. The present disclosure further relates to a fiber-based substrate coated with such a coating composition. Background Art

[0002] In the packaging industry, effective gas, aroma and / or moisture barriers are needed to protect sensitive products. In particular, oxygen-sensitive products require oxygen barriers to extend their shelf-life. Oxygen-sensitive products include many food products, as well as pharmaceutical products and products of the electronics industry. Known packaging materials with oxygen barrier properties may include one or more (one or more) polymer films, or fiber-based substrates, such as paper or paperboard, coated with one or more oxygen barrier polymer layers (usually as part of a multilayer coating structure).

[0003] Another important property of food product packaging is grease resistance.

[0004] Barriers are typically formed by coating a fiber-based substrate with a composition that imparts barrier properties to the substrate. Different coatings may be applied depending on the barrier properties required. When forming barriers on fiber-based substrates, the most commonly used materials are polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), ethylene vinyl alcohol (EVOH), or ethylene vinyl acetate (EVA). EVOH is typically used to create an oxygen barrier, and PE or PET are typically used to create a liquid and / or vapor barrier. These polymers are generally laminated or extrusion coated onto a fiber-based substrate. However, the polymer layer that imparts barrier properties to the product typically needs to be relatively thick, and therefore, the cost of producing such barriers is quite high.

[0005] The most common way to reduce the oxygen transmission rate (OTR) through paper or paperboard is to use multiple polymer layers. In this way, one layer can provide low OTR, while other layers can provide water resistance and / or low water vapor transmission rate.

[0006] Another commonly used barrier material is aluminum. Aluminum layers are often used to improve the oxygen and light barrier of paper or paperboard products. The aluminum layer is thin, typically about 7-9 microns. Aluminum provides excellent barrier properties, but it greatly increases the carbon dioxide load of the product.

[0007] Polymer and aluminum layers also face the problem that they reduce biodegradability and the possibility of effectively recycling the packaging material.

[0008] Manufacturers, converters and end users require the avoidance of synthetic polymers and aluminum layers in paper or paperboard products in order to reduce the CO2 load and to increase the biodegradability and recyclability of the products.

[0009] Therefore, there is a need for improved processes to provide fiber-based substrates such as paper or paperboard having improved barrier properties. Summary of the invention

[0010] It is an object of the present disclosure to provide a barrier film or coating for fiber-based substrates that alleviates at least some of the problems of prior art barrier films and coatings.

[0011] Another object of the present disclosure is to provide a barrier film or coating for fiber-based substrates that provides good resistance to oxygen and / or grease.

[0012] It is another object of the present disclosure to provide a barrier film or coating that can be effectively applied to fiber-based substrates using conventional coating methods.

[0013] Natural polymers from plants are biodegradable, renewable and recyclable, and constitute the interesting source of the raw material of the barrier film in the packaging material. Hemicellulose is a polysaccharide biosynthesized in most plants, wherein they serve as a matrix material present between cellulose microfibrils, and serve as a connection between lignin and cellulose. Hemicellulose has been used commercially as a sweetener, thickener and emulsifier for food. It has been shown before that the barrier film formed by hemicellulose can provide good oxygen and grease barrier properties. However, due to the high viscosity of the hemicellulose composition limiting the solid content, causing this film to be difficult to effectively manufacture.

[0014] According to a first aspect shown herein, there is provided an aqueous barrier coating composition comprising:

[0015] 50-99.9 wt. % of one or more anionic low molecular weight polysaccharides having a degree of polymerization (DP) in the range of 2-12;

[0016] 0.1-10% by weight of poly(poly)cationic polymer,

[0017] Based on the total dry weight of the aqueous barrier coating composition.

[0018] The present invention is based on the surprising discovery that short anionic polysaccharides, such as anionic hemicelluloses such as xylan, having a degree of polymerization (DP) in the range of 2-12, can form good barrier films when combined with polycationic polymers. Such low molecular weight polysaccharides having a degree of polymerization (DP) in the range of 2-12 have not previously been considered for use in barrier films.

[0019] The present inventors have discovered that, in addition to providing barrier films and coatings having excellent oxygen and grease barrier properties, the combination of relatively high amounts of low molecular weight polysaccharides and relatively low amounts of polycationic polymers also enables the preparation of aqueous barrier coating compositions having high total solids content (e.g., at least 50 wt%) while still maintaining a reasonably low viscosity. This allows the aqueous barrier coating composition to be effectively applied to a substrate by conventional coating methods.

[0020] The aqueous barrier coating composition comprises a low molecular weight polysaccharide having a degree of polymerization (DP) in the range of 2-12, and a polycationic polymer dissolved or dispersed in an aqueous medium. The aqueous medium may be water or an aqueous solution, or it may comprise a mixture of water or an aqueous solution with an organic solvent. In a preferred embodiment, the aqueous medium is water-based, i.e. it comprises more than 50% by weight of water. In a more preferred embodiment, the aqueous medium is water.

[0021] The aqueous barrier coating composition may be a thin or high solids composition. However, high solids compositions are generally preferred.

[0022] One advantage of the coating composition of the present invention is that it allows for high total solids content, such as 30 wt% or even higher, while still maintaining a reasonably low viscosity. As used herein, the term "total solids content" or "solids content" refers to the total fraction of dissolved solids plus suspended and settleable solids in an aqueous solution or suspension.

[0023] The high solids content combined with the low viscosity reduces the transportation costs of the coating composition and allows the preparation of coatings with high basis weights in a single coating step. The high solids content also reduces the amount of water to be removed when drying the film or coating, which can reduce the drying energy requirements of the coating process. Preferably, the total solids content of the coating composition is at least 10% by weight, more preferably at least 20%, or at least 30% by weight, based on the total weight of the coating composition.

[0024] The total solids content of the coating composition is generally 90 wt % or less, preferably 80 wt % or less, more preferably 70 wt % or less, based on the total weight of the coating composition.

[0025] In some embodiments, the total solids content of the aqueous barrier coating composition is in the range of 10-90 wt %, preferably in the range of 20-80 wt %, more preferably in the range of 30-70 wt %, based on the total weight of the coating composition.

[0026] The total solid content of the aqueous barrier coating composition comprises one or more anionic low molecular weight polysaccharides as its main component. The total solid content of the aqueous barrier coating composition comprises 50-99.9 wt % of one or more anionic low molecular weight polysaccharides.

[0027] In some embodiments, the aqueous barrier coating composition comprises 75-99 weight percent of one or more anionic low molecular weight polysaccharides, based on the total dry weight of the aqueous barrier coating composition.

[0028] The number of monosaccharide units in a polysaccharide is referred to as the degree of polymerization (DP). The term low molecular weight polysaccharide as used herein generally refers to a short sugar chain comprising 2-12 monosaccharide units. In some embodiments, the DP of one or more low molecular weight polysaccharides is in the range of 2-8, preferably in the range of 2-7. This is a very short chain length compared to cellulose, which consists of, for example, 7,000-15,000 glucose molecules. The molecular weight of the low molecular weight polysaccharide used herein may typically be in the range of 250-2000 g / mol, for example, in the range of 250-1500 g / mol or 250-1000 g / mol.

[0029] The monosaccharide units can be of the same type (homopolysaccharides) or of different types (heteropolysaccharides). Low molecular weight polysaccharides can be prepared by natural synthesis, for example by chemical or synthetic hydrolysis of longer polysaccharides. Examples of anionic low molecular weight polysaccharides that can be used in the present invention include, but are not limited to, the following anionic low molecular weight polysaccharides: gellan, dextran, pullulan, cellulose, hemicellulose, hyaluronic acid, alginate, xanthan gum, zooglan, succinylglucan and glucomannan.

[0030] The low molecular weight polysaccharide is anionic, meaning that the low molecular weight polysaccharide includes at least one anionic functional group. The anionic functional group is typically a carboxylate / carboxylic acid functional group, but other anionic functional groups are also possible. The anionic functional group may be naturally present in the low molecular weight polysaccharide, such as the carboxylate / carboxylic acid functional group in glucuronic acid or galacturonic acid, or introduced by chemical modification (e.g. oxidation or grafting of the low molecular weight polysaccharide).

[0031] In some embodiments, the one or more low molecular weight polysaccharides having a degree of polymerization (DP) in the range of 2-12 are selected from anionic hemicellulose, anionic cellulose and anionic starch, or a combination thereof.

[0032] In some embodiments, the one or more low molecular weight polysaccharides having a degree of polymerization (DP) in the range of 2-12 are anionic hemicelluloses.

[0033] Hemicelluloses are substituted / branched polysaccharides ranging from low to high molecular weight. They are composed of different sugar units arranged in different parts and with different substituents.

[0034] Hemicelluloses can be divided into the major classes of xylans, xyloglucans, glucomannans and mixed linked beta-glucans. Some hemicelluloses are naturally negatively charged due to the presence of glucuronic acid and / or galacturonic acid units in the sugar chain. Hemicelluloses used in aqueous barrier coating compositions are preferably such anionic hemicelluloses. Hemicelluloses are readily hydrolyzed by dilute acids or bases and by various hemicellulases.

[0035] In some embodiments, the one or more low molecular weight polysaccharides having a degree of polymerization (DP) in the range of 2-12 are xylans. Xylans are present in biomass such as wood, grains, grasses and herbs and they are considered to be the second most abundant biopolymer in the plant kingdom. In order to separate xylans from other components in various biomass sources, extraction with water and aqueous alkali (alkaline water) can be used.

[0036] The total solids content of the aqueous barrier coating composition further comprises 0.1-10 wt % of a polycationic polymer. In some embodiments, the aqueous barrier coating composition comprises 0.5-6 wt % of a polycationic polymer, based on the total dry weight of the aqueous barrier coating composition.

[0037] Polycationic polymers are synthetic or natural polymers with multiple cationic functional groups. Examples of polycationic polymers for use in the present invention can be selected from: poly (N-methylvinylamine), polyallylamine, polyallyldimethylamine, polydiallylmethylamine, polydiallyldimethylammonium chloride (pDADMAC), polydiallyldimethylammonium trifluoromethanesulfonate (pDADMAT), polydiallyldimethylammonium nitrate (pDADMAN), polydiallyldimethylammonium perchlorate (pDADMAP), polyvinylpyridinium chloride, poly (2-vinylpyridine), poly (4-vinylpyridine), polyvinylimidazole, poly (4-aminomethylstyrene), poly (4-aminostyrene), polyvinyl (acrylamide-to-dimethylaminopropylacrylamide), polyvinyl (acrylamide-to-dimethylaminoethylmethacrylate), polyethyleneimine, polylysine, DAB-Am and PAMAM dendrimers, polyaminoamides, polyhexamethylene biguanide (polyhe 1-(2-aminoethyl)-3-aminopropyltrimethoxysilane, N-trimethoxysilylpropyl-N,N,N-trimethylammonium chloride, bis(trimethoxysilylpropyl)amine, chitosan, cationic starch, cationic gelatin, products of polyethyleneimine alkylated with methyl chloride, products of polyaminoamide alkylated with epichlorohydrin, cationic polyacrylamide with cationic monomers, dimethylaminoethyl acrylate methyl chloride (AETAC), dimethylaminoethyl methacrylate methyl chloride (METAC), acrylamidopropyltrimethylammonium chloride (APTAC), methacrylamidopropyltrimethylammonium chloride (MAPTAC), diallyldimethylammonium chloride (DADMAC), ionenes, silanes and mixtures thereof.

[0038] In some embodiments, the cationic polymer is selected from the group consisting of: polyaminoamide, polyethyleneimine, polyvinylamine, polydiallyldimethylammonium chloride (pDADMAC), chitosan, cationic starch, and cationic gelatin.

[0039] In a preferred embodiment, the polycationic polymer is polyethyleneimine (PEI).

[0040] In some embodiments, the polycationic polymer has a weight average molecular weight in the range of 2 000-1 000 000 g / mol, preferably in the range of 10 000-100 000 g / mol.

[0041] The formulation of the aqueous barrier coating composition can vary greatly depending on the intended use of the coating and the coated substrate. In some embodiments, the total solid content of the aqueous barrier coating composition consists only of one or more low molecular weight polysaccharides and polycationic polymers. In other embodiments, the coating composition may further include a wide range of ingredients in varying amounts to improve the final properties of the product or the processing of the coating (coating).

[0042] In some embodiments, a plasticizer is added to the aqueous barrier coating composition to increase the elasticity of the resulting film or coating and make it less brittle. This allows the formed film or coating to better withstand bending without losing its barrier properties.

[0043] In some embodiments, the aqueous barrier coating composition comprises 1 to 10 weight percent of a plasticizer, based on the total dry weight of the aqueous barrier coating composition.

[0044] In some embodiments, the plasticizer is selected from the group consisting of glycerol, xylitol, sorbitol, maltitol, ethylene glycol, propylene glycol, butylene glycol, and combinations thereof.

[0045] In some embodiments, fillers are added to the waterborne barrier coating composition to improve the barrier and mechanical properties of the resulting film or coating.

[0046] In some embodiments, the aqueous barrier coating composition further comprises 5-40 wt % of a filler, based on the total dry weight of the aqueous barrier coating composition.

[0047] In some embodiments, the filler is selected from clay (such as kaolin or calcined kaolin), talc, CaCO3 (such as PCC or GCC), TiO2, Al2O3, SiO2, bentonite, fiber or a mixture thereof. The fiber may preferably have a hydrophilic surface and a density close to the density of water (i.e., preferably in the range of 0.85-1.15 g / cm 3 In the range of 0.90-1.10g / cm 3 any fiber within the range of

[0048] In some embodiments, the filler is selected from clay, talc, CaCO3, and fiber, or a combination thereof.

[0049] The coating composition is preferably provided in a formulation suitable for application to paper or paperboard using conventional paper coating equipment and techniques (e.g., knife coaters and rod coaters). Thus, the coating composition may include various additives to impart suitable coating properties. Such coating additives may include, but are not limited to, dispersants (e.g., surfactants), lubricants (e.g., stearates), rheology modifiers, insolubilizers, humectants, barrier chemicals, and pH adjusters (e.g., NaOH).

[0050] The aqueous barrier coating composition can be applied to a substrate and dried to form a barrier film or coating. Therefore, according to the second aspect shown herein, there is provided a barrier film or coating comprising:

[0051] 50-99.9 wt. % of one or more anionic low molecular weight polysaccharides having a degree of polymerization (DP) in the range of 2-12;

[0052] 0.1-10 wt% polycationic polymer;

[0053] Based on total dry weight of barrier film or coating.

[0054] The barrier film or coating is preferably dry or substantially dry. The barrier film or coating preferably has a total solids content of above 90 wt%, preferably above 95 wt%.

[0055] It will be appreciated that the composition of the barrier film or coating according to the second aspect will correspond to the composition of the total solids content of the aqueous barrier coating composition according to the first aspect. For example, a dry content of 50-99.9 wt. % of the one or more anionic low molecular weight polysaccharides in the aqueous barrier coating composition results in a content of 50-99.9 wt. % of the one or more anionic low molecular weight polysaccharides in the dry barrier film or coating.

[0056] The film or coating according to the present invention may generally have a thickness of 30 g / m 2 Or lower basis weight. Usually, at least 1g / m 2 In some embodiments, the basis weight of the film or coating is 5-15 g / m 2 In the range of 5-10 g / m 2 within the range.

[0057] The film or coating according to the present invention may generally have a thickness of 100 μm or less. In particular, the film or coating may have a thickness of 50 μm or less, or more specifically, the film or coating may have a thickness of 15 μm or less or 10 μm or less. In some embodiments, the thickness of the film or coating is in the range of 1-15 μm, preferably in the range of 5-10 μm.

[0058] The barrier film or coating is preferably prepared from the aqueous barrier coating composition described above with reference to the first aspect.

[0059] The barrier film or coating of the present invention has good oxygen and grease barrier properties.

[0060] In some embodiments, the barrier film or coating has an oxygen transmission rate (OTR) of less than 100 cc / m2 / 24h / atm, preferably less than 50cc / m 2 / 24h / atm, and more preferably less than 10cc / m 2 / 24h / atm.

[0061] In some embodiments, the film or coating has a KIT value of above 8, preferably above 10, measured according to standard TAPPI T559.

[0062] According to a third aspect shown herein, there is provided a coated substrate comprising a substrate coated with the aqueous barrier coating composition according to the first aspect.

[0063] The aqueous barrier coating composition according to the first aspect is particularly interesting for coating (coating) of fiber-based substrates. Therefore, in some embodiments, the coated substrate is a fiber-based substrate. The fiber-based substrate is preferably paper or paperboard.

[0064] Paper generally refers to a material made in sheets or rolls from wood pulp or other fibrous substances containing cellulose fibers, used, for example, for writing, drawing or printing thereon, or as packaging material. Paper may be bleached or unbleached, coated or uncoated, and produced in various thicknesses, depending on the end-use requirements.

[0065] Paperboard generally refers to a strong, thick paper or cardboard comprising cellulose fibers, used, for example, as a flat substrate, trays, boxes and / or other types of packaging. Paperboard can be bleached or unbleached, coated or uncoated, and produced in various thicknesses, depending on the end-use requirements.

[0066] The aqueous barrier coating composition can be added on the paper machine (on-machine coating) or on a separate machine (off-machine coating). Various paper coating equipment and techniques can be used to apply the coating composition, such as blade coaters, air knife coaters, and cast coaters. The coating composition can be applied to one or both sides of the paper or paperboard.

[0067] The surface of the paper or paperboard to which the waterborne barrier coating is to be applied may preferably be pre-treated, for example by dispersion coating with a mineral coating, to reduce the porosity of the surface. This allows the amount of waterborne barrier coating to be reduced. Thus, in some embodiments, the coated substrate is a dispersion coated, preferably mineral coated, paper or paperboard.

[0068] The coated substrate is preferably suitable for repulping. In some embodiments, the coated substrate has a repulpability characterized by a reject rate (determined according to the PTS RH 021 / 97 test method) of less than 20%, preferably less than 10%, more preferably less than 5%, and most preferably less than 1%.

[0069] According to a fourth aspect shown herein, there is provided a method of manufacturing a barrier film or coating, comprising:

[0070] a) preparing the aqueous barrier coating composition according to the first aspect;

[0071] b) forming a wet film or coating of the aqueous barrier coating composition; and

[0072] c) Drying the wet film or coating to obtain a barrier film or coating.

[0073] In some embodiments, the aqueous barrier coating composition has a total solids content in the range of 10-90 wt %, preferably in the range of 20-80 wt %, more preferably in the range of 30-70 wt %, based on the total weight of the coating composition.

[0074] In the drying step c), the total solid content of the wet film or coating is increased by evaporation of water. The total solid content of the resulting barrier film or coating is preferably above 90% by weight.

[0075] In some embodiments, the dried barrier film or coating has a basis weight of 5-15 g / m 2 In the range of 5-10 g / m 2 within the range.

[0076] In some embodiments, the thickness of the dried barrier film or coating is in the range of 5-15 μm, preferably in the range of 5-10 μm.

[0077] The term coating as used herein generally refers to a finishing operation in which the surface of a substrate (e.g., a fiber-based substrate such as paper or paperboard) is covered with a composition to impart a desired finish or texture to the substrate or to improve its printability or other properties, such as optical or barrier properties. The term barrier coating as used herein generally refers to a coating designed to impart improved barrier properties to a substrate.

[0078] The term film as used herein generally refers to a material formed in a continuous sheet.The term barrier film as used herein generally refers to a film designed to provide good barrier properties.

[0079] Typically, although products, polymers, materials, layers and methods are described as “comprising” various components (components) or steps, the products, polymers, materials, layers and methods may also “essentially consist of” or “consist of” the various components (components) or steps.

[0080] Although the present invention has been described with reference to various exemplary embodiments, it will be appreciated by those skilled in the art that various changes may be made and that equivalents may be substituted for its elements without departing from the scope of the present invention. In addition, many modifications may be made to adapt specific situations or materials to the teachings of the present invention without departing from the basic scope of the present invention. Therefore, it is intended that the present invention is not limited to the specific embodiments disclosed as the best mode contemplated for carrying out the present invention, but that the present invention will include all embodiments falling within the scope of the appended claims. Example

[0081] Material:

[0082] -Dried xylan powder, DP2-7, 95% purity, 8% moisture content (Coreychem)

[0083] - Glycerol, 87% concentration in water (Merck)

[0084] - Clay, 72% concentration, in water (Omya)

[0085] -PEI, 50 wt% concentration in water (Sigma Aldrich)

[0086] Example 1 - Preparation of Xylan / Water Mixture

[0087] A 20% xylan mixture was prepared by gradually adding 20 g of xylan powder to a stirred vessel containing 80 g of water. The mixture had a very low viscosity of about 16 LmPa (Brookfield viscosity of a 19% solution, spindle 2, at 21°C).

[0088] 47%, 51% and 53% xylan mixtures were prepared by gradually adding 47g, 51g and 53g xylan powder to a stirred container containing 53g, 49g and 47g water, respectively. The mixture had a medium viscosity level of about 16LmPa (Brookfield viscosity of a 39% solution, spindle 2, at 21°C), which was suitable for rod coating.

[0089] Example 2 - Preparation of paint colors

[0090] Xylan-based coatings with different chemical compositions were prepared by mixing xylan with additives (glycerol, clay, and PEI) at room temperature. pigment , as shown in Table 1.

[0091] Example 3 - Coating of Paperboard

[0092] The coating pigments were applied to the surface of a paperboard substrate (Tambrite 200 gsm, print coated) using a laboratory bar coater equipped with IR drying. All samples were coated 2 times with a grooved bar (red). The samples were conditioned at 23°C and 50% RH for several days prior to analysis.

[0093] analyze

[0094] The samples were tested for the appearance of pinholes, grease resistance (KIT) and oxygen permeability (oxygen transmission rate, OTR) as follows:

[0095] - Oxygen Transmission Rate (OTR) is measured according to ASTM D3985 at a temperature of 23°C and at 50% relative humidity (RH).

[0096] - Pinhole count is measured according to EN 13676: 2001. The measurement involves treating the packaging material with a coloring solution (eg the dye E131 Blue in ethanol) and examining the surface with a microscope.

[0097] - The KIT value is a measure of grease resistance and is measured according to TAPPI T559.

[0098] The analysis results are shown in Table 1.

[0099] Table 1

[0100]

[0101]

[0102] 1 Prepared from 47% xylan mixture

[0103] 2 Prepared from 51% xylan mixture

[0104] 3 Prepared from 53% xylan mixture

[0105] 5 OR = Out of range, meaning value > 5000cm 3 / m 2 .

Claims

1. A water-based barrier coating composition comprising: 50-99.9 wt. % of one or more anionic low molecular weight polysaccharides having a degree of polymerization in the range of 2-12; 0.1-10 wt% of a polycationic polymer; Based on the total dry weight of the aqueous barrier coating composition.

2. The aqueous barrier coating composition according to claim 1, comprising 75-99 wt% of one or more anionic low molecular weight polysaccharides, based on the total dry weight of the aqueous barrier coating composition.

3. The aqueous barrier coating composition according to any one of claims 1-2, wherein the one or more low molecular weight polysaccharides having a degree of polymerization in the range of 2-12 are selected from anionic hemicellulose, anionic cellulose and anionic starch or a combination thereof.

4. The aqueous barrier coating composition according to any one of claims 1 to 2, wherein the one or more low molecular weight polysaccharides having a degree of polymerization in the range of 2 to 12 are anionic hemicelluloses.

5. The aqueous barrier coating composition according to any one of claims 1 to 2, wherein the one or more low molecular weight polysaccharides having a degree of polymerization in the range of 2 to 12 is xylan.

6. The aqueous barrier coating composition according to any one of claims 1-2, wherein the one or more low molecular weight polysaccharides have a degree of polymerization in the range of 2-8.

7. The aqueous barrier coating composition according to claim 6, wherein the one or more low molecular weight polysaccharides have a degree of polymerization in the range of 2-7.

8. The aqueous barrier coating composition according to any one of claims 1 to 2, further comprising 0.5 to 6 wt% of a polycationic polymer, based on the total dry weight of the aqueous barrier coating composition.

9. The aqueous barrier coating composition according to claim 8, wherein the polycationic polymer is polyethyleneimine.

10. The aqueous barrier coating composition according to any one of claims 8 or 9, wherein the polycationic polymer has a weight average molecular weight in the range of 2 000-1 000 000 g / mol.

11. The aqueous barrier coating composition according to claim 10, wherein the polycationic polymer has a weight average molecular weight in the range of 10 000-100 000 g / mol.

12. The aqueous barrier coating composition according to any one of claims 1 to 2, further comprising 1 to 10 wt% of a plasticizer, based on the total dry weight of the aqueous barrier coating composition.

13. The aqueous barrier coating composition according to claim 12, wherein the plasticizer is selected from glycerol, xylitol, sorbitol, maltitol, ethylene glycol, propylene glycol, butylene glycol and combinations thereof.

14. The aqueous barrier coating composition according to any one of claims 1 to 2, further comprising 5 to 40 wt% of a filler, based on the total dry weight of the aqueous barrier coating composition.

15. The aqueous barrier coating composition according to claim 14, wherein the filler is selected from clay, talc, CaCO3 and fiber or a combination thereof.

16. A barrier film or coating comprising: 50-99.9 wt. % of one or more anionic low molecular weight polysaccharides having a degree of polymerization in the range of 2-12; 0.1-10 wt% polycationic polymer; Based on total dry weight of barrier film or coating.

17. The barrier film or coating according to claim 16, wherein the basis weight of the film or coating is 5-15 g / m 2 within the range.

18. The barrier film or coating according to claim 17, wherein the basis weight of the film or coating is 5-10 g / m 2 within the range.

19. A coated substrate comprising a substrate coated with the aqueous barrier coating composition according to any one of claims 1 to 15.

20. The coated substrate of claim 19, wherein the coated substrate is a fiber-based substrate.

21. The coated substrate of claim 20, wherein the coated substrate is paper.

22. The coated substrate of claim 21, wherein the coated substrate is a mineral coated paper.

23. The coated substrate of claim 20, wherein the coated substrate is paperboard.

24. The coated substrate of claim 23, wherein the coated substrate is a mineral coated paperboard.

25. The coated substrate of any one of claims 19-24, wherein the coated substrate has a repulpability characterized by a reject rate below 20%, as determined according to the PTS RH 021 / 97 test method.

26. The coated substrate of claim 25, wherein the sludge ratio is below 10%.

27. The coated substrate of claim 26, wherein the sludge ratio is less than 5%.

28. The coated substrate of claim 27, wherein the sludge content is less than 1%.

29. A method of making a barrier film or coating comprising: a) preparing an aqueous barrier coating composition according to any one of claims 1 to 15; b) forming a wet film or coating of the aqueous barrier coating composition; as well as c) Drying the wet film or coating to obtain a barrier film or coating.

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