Barrier Coatings for Paper and Board

Abstract

The present invention relates to an aqueous barrier coating composition comprising: 20-80% by weight, based on the total solids content of the aqueous barrier coating composition, of a dissolved first polysaccharide having a first degree of polymerization (DP1) of at least 150; and 20-80% by weight, based on the total solids content of the aqueous barrier coating composition, of a dissolved second polysaccharide having a second degree of polymerization (DP2) of 100 or less; the ratio of DP1:DP2 is at least 10:1; and the aqueous barrier coating composition has a total solids content in the range of 10-90% by weight.

Description

[Technical field]

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

[0002] In the packaging industry, effective barriers of gases, aromas, and / or moisture are required to protect sensitive products. In particular, oxygen-sensitive products require oxygen barriers to extend their shelf life. Oxygen-sensitive products include many foods, as well as pharmaceuticals and electronic products. Known packaging materials with oxygen barrier properties may consist of one or several polymeric films or of a fiber-based substrate, such as paper or board, coated with one or several layers of oxygen barrier polymers, usually as part of a multi-layer coating structure.

[0003] Another important property for food packaging is resistance to grease and oil.

[0004] Barriers are typically created by coating a textile substrate with a composition that provides the substrate with barrier properties. Various coatings can be applied depending on the barrier properties required. The most commonly used materials for forming barriers on textile substrates are polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), polyamide (PA), ethylene vinyl alcohol (EVOH), or ethylene vinyl acetate (EVA). EVOH is typically used to create oxygen barriers, while PE or PET are typically used to create liquid and / or vapor barriers. Polymers are typically laminated or extrusion coated onto textile substrates. However, the polymer layer that provides the barrier properties to the product typically needs to be relatively thick, which makes the creation of such barriers quite costly.

[0005] The most common way to approach reducing the oxygen transmission rate (OTR) through paper or paperboard is to use multiple polymer layers, where one layer can provide a low OTR and other layers can provide water repellency and / or low water vapor transmission rate.

[0006] Another commonly used barrier material is aluminium. Aluminium layers are typically used to improve the oxygen and light barrier of paper or paperboard products. The aluminium layer is thin, typically around 7-9 µm. Aluminium offers excellent barrier properties but significantly increases the carbon dioxide load of the product.

[0007] A problem with both the polymeric and aluminum layers is that they also reduce the biodegradability and the ability to efficiently recycle the packaging material.

[0008] There is a demand from manufacturers, converters and end users to avoid the use of synthetic polymers and aluminium layers in paper or paperboard products to reduce the carbon dioxide load and improve the biodegradability and recyclability of the products.

[0009] Thus, there is a need for improved methods for providing fiber-based substrates, such as paper or paperboard, with 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 the prior art barrier films and coatings.

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

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

[0013] According to a first aspect exemplified herein, there is provided an aqueous barrier coating composition comprising: 20-80 wt. %, based on the total solids content of the aqueous barrier coating composition, of a dissolved first polysaccharide having a first degree of polymerization (DP1) of 150 or greater; and 20-80 wt. %, based on the total solids content of the aqueous barrier coating composition, of a dissolved second polysaccharide having a second degree of polymerization (DP2) of 100 or less. Includes; the ratio of DP1:DP2 is at least 10:1; The aqueous barrier coating composition has a total solids content in the range of 10 to 90 wt. %. An aqueous barrier coating composition is provided.

[0014] The present invention is based on the surprising finding that short water-soluble polysaccharides having a degree of polymerization (DP) of 100 or less, such as anionic hemicelluloses such as xylan, can form good barrier films when combined with long water-soluble polysaccharides having a degree of polymerization (DP) of 150 or more, such as carboxymethylcellulose.

[0015] The inventors have found that in addition to providing barrier films and coatings with excellent oxygen and grease barrier properties, the combination of relatively large amounts of relatively short water-soluble polysaccharides with longer water-soluble polysaccharides allows for the preparation of aqueous barrier coating compositions having high total solids contents, for example 10, 20, or even 30 wt.% or more total solids contents, while still maintaining a reasonably low viscosity, which allows the aqueous barrier coating composition to be efficiently applied to a substrate using conventional coating methods.

[0016] It has been found that the aqueous barrier coating composition of the present invention comprising a combination of polysaccharides provides good barrier properties against air, oxygen and water vapor while at the same time having a low detrimental effect on the repulping and recycling of post-consumer barrier films. The barrier films can be applied to paper or paperboard based substrates at high speeds with good runnability on the paper machine.

[0017] The aqueous barrier coating composition comprises a first polysaccharide and a second polysaccharide dissolved in an aqueous medium. The aqueous medium may be water or an aqueous solution, or the aqueous medium may comprise a mixture of water or an aqueous solution and an organic solvent. In a preferred embodiment, the aqueous medium is water-based, i.e., the aqueous medium is composed of more than 50% water by weight. In a more preferred embodiment, the aqueous medium is water.

[0018] The first polysaccharide and the second polysaccharide are dissolved in the aqueous barrier coating composition. As used herein, the term "dissolved" indicates that the polysaccharide molecules are homogeneously mixed in the aqueous medium. Thus, the first polysaccharide and the second polysaccharide are preferably both water-soluble. As used herein, the term "water-soluble" indicates that the polysaccharide can be dissolved in the aqueous medium at atmospheric pressure and at a temperature not exceeding 100°C, at least to the concentration required to prepare the aqueous barrier coating composition.

[0019] Solutions of polysaccharides may have high viscosity even at relatively low total solids contents. An advantage of the coating composition of the present invention is that it allows for high total solids contents, for example 30% by weight 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 in an aqueous solution or suspension, plus suspended solids and sedimentable solids. The aqueous barrier coating composition has a relatively high solids content. The aqueous barrier coating composition has a total solids content in the range of 10-90% by weight. In some embodiments, the aqueous barrier coating composition has a total solids content in the range of 10-80% by weight, preferably 20-70% by weight, more preferably 20-50% by weight.

[0020] The high solids content combined with the low viscosity reduces the transportation cost of the coating composition and allows the preparation of high basis weight coatings 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 may also reduce the energy requirement for drying the coating process. Preferably, the total solids content of the coating composition is at least 10% by weight, more preferably at least 20% by weight or at least 30% by weight. The total solids content of the coating composition is typically 90% by weight or less, preferably 80% by weight or less, more preferably 70% by weight or less.

[0021] The total solids content of the aqueous barrier coating composition preferably comprises the first polysaccharide as its major component. The total solids content of the aqueous barrier coating composition preferably comprises 30-80 wt. %, preferably 40-80 wt. %, more preferably 50-80 wt. % of the first polysaccharide based on the total solids content of the aqueous barrier coating composition.

[0022] Polysaccharides comprise polymer chains of repeating monosaccharide units. The monosaccharide units can be of the same type (homopolysaccharides) or different (heteropolysaccharides). The number of monosaccharide units in a polysaccharide is called the degree of polymerization (DP). The first polysaccharide has a first degree of polymerization (DP1) of 150 or more, and the second polysaccharide has a second degree of polymerization (DP2) of 100 or less, with a ratio of DP1:DP2 of at least 10:1. That is, if DP1 is 200, then DP2 must be 20 or less. In some embodiments, the ratio of DP1:DP2 is at least 20:1, preferably at least 30:1.

[0023] In some embodiments, the first polysaccharide has a first degree of polymerization (DP1) in the range of 150-4000, preferably in the range of 150-2000, and more preferably in the range of 150-1000.

[0024] In some embodiments, the first polysaccharide is anionic, meaning that the polysaccharide comprises at least one anionic functional group. The anionic functional group is typically a carboxylate / carboxylic acid functional group, but other anionic functional groups are possible. The anionic functional group may be naturally occurring in the polysaccharide, such as a carboxylate / carboxylic acid functional group in glucuronic acid or galacturonic acid, or may be introduced by chemical modification of the polysaccharide, such as oxidation or grafting.

[0025] In some embodiments, the first polysaccharide is selected from the group consisting of water soluble hemicellulose, water soluble cellulose, water soluble starch, alginate, chitosan, pullulan, dextran, and agarose.

[0026] Hemicellulose, cellulose, and starch typically have low solubility in water in their native state. As used herein, the terms "water-soluble hemicellulose," "water-soluble cellulose," and "water-soluble starch" refer to hemicellulose, cellulose, and starch derivatives that are naturally occurring polysaccharides that have been physically, chemically, or physicochemically modified to increase their solubility in water.

[0027] In some embodiments, the first polysaccharide is selected from the group consisting of water soluble hemicellulose, water soluble cellulose, water soluble starch, and alginate.

[0028] In some embodiments, the first polysaccharide is selected from the group consisting of carboxymethylcellulose, methylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, hydroxypropylmethylcellulose, ethylhydroxyethylcellulose (EHEC), and methylethylhydroxyethylcellulose (MEHEC).

[0029] In some embodiments, the first polysaccharide is carboxymethylcellulose (CMC).

[0030] The aqueous barrier coating composition further comprises a relatively large amount of a second polysaccharide having a second degree of polymerization (DP2) of 100 or less, which is a short chain length compared to, for example, cellulose, which is comprised of about 7,000 to 15,000 glucose molecules. The aqueous barrier coating composition comprises 20 to 80 weight percent of the second polysaccharide, based on the total solids content of the aqueous barrier coating composition.

[0031] In some embodiments, the aqueous barrier coating composition comprises 20-60 wt. %, preferably 20-40 wt. %, and more preferably 20-30 wt. % of the second polysaccharide based on the total solids content of the aqueous barrier coating composition.

[0032] In some embodiments, the second polysaccharide has a first degree of polymerization (DP1) in the range of 2-50, preferably in the range of 2-25, and more preferably in the range of 2-12.

[0033] In some embodiments, the second polysaccharide is a short saccharide chain composed of 2 to 12 monosaccharide units. In some embodiments, the second polysaccharide has a DP in the range of 2 to 8, preferably in the range of 2 to 5. As used herein, the molecular weight of the second polysaccharide may typically be in the range of 250 to 2000 g / mol, for example in the range of 250 to 1500 g / mol or in the range of 250 to 1000 g / mol.

[0034] The second polysaccharide may be a naturally occurring polysaccharide or may be prepared synthetically, for example by chemical or synthetic hydrolysis of a longer polysaccharide.

[0035] In some embodiments, the second polysaccharide is anionic, meaning that the polysaccharide comprises at least one anionic functional group. The anionic functional group is typically a carboxylate / carboxylic acid functional group, but other anionic functional groups are possible. The anionic functional group may be naturally occurring in the polysaccharide, such as a carboxylate / carboxylic acid functional group in glucuronic acid or galacturonic acid, or may be introduced by chemical modification of the polysaccharide, such as oxidation or grafting.

[0036] In some embodiments, the second polysaccharide is selected from the group consisting of water soluble hemicellulose, water soluble cellulose, water soluble starch, alginate, chitosan, pullulan, dextran, and agarose.

[0037] In some embodiments, the second polysaccharide is selected from the group consisting of water soluble hemicellulose, water soluble cellulose, water soluble starch, and alginate.

[0038] Hemicelluloses are substituted / branched polysaccharides ranging from low to high molecular weight. They consist of different sugar units arranged in different parts and with different substituents.

[0039] Hemicelluloses can be divided into the main groups of xylans, xyloglucans, glucomannans, and mixed linkage beta-glucans. Some hemicelluloses naturally carry a negative charge due to the presence of glucuronic and / or galacturonic acid units in the sugar chain. Hemicelluloses for use in aqueous barrier coating compositions are preferably such anionic hemicelluloses. Hemicelluloses are easily hydrolyzed by dilute acids or bases as well as various hemicellulase enzymes.

[0040] In some embodiments, the second polysaccharide is xylan.Xylan is present in biomass, such as wood, cereals, grasses, and herbs, and is considered the second most abundant biopolymer in the plant kingdom.Extraction with water and aqueous alkaline solution can be used to separate xylan from other components in biomass from various sources.

[0041] In some embodiments, the second polysaccharide is a xylan composed of 2 to 12 monosaccharide units. In some embodiments, the xylan has a DP in the range of 2 to 8, preferably in the range of 2 to 5.

[0042] The formulation of the aqueous barrier coating composition can vary widely depending on the intended use of the coating and the coated substrate. In some embodiments, the total solids content of the aqueous barrier coating composition consists solely of the first polysaccharide and the second polysaccharide. In other embodiments, the coating composition may further include a wide range of components in different amounts to improve the final performance of the product or processing of the coating.

[0043] The aqueous barrier coating composition may further comprise additional components dissolved or dispersed in the aqueous medium, the total amount of additional components dissolved or dispersed in the aqueous medium being less than 50 wt.%, preferably less than 40 wt.%, more preferably less than 30 wt.%, based on the total solids content of the aqueous barrier coating composition.

[0044] In some embodiments, fillers are added to the aqueous barrier coating composition to improve the barrier and mechanical properties of the resulting film or coating. In some embodiments, the aqueous barrier coating composition comprises 1-30 wt. % of a filler, based on the total solids content of the aqueous barrier coating composition. In some embodiments, the amount of filler in the aqueous barrier coating composition is less than the critical pigment volume concentration (CPVC).

[0045] In some embodiments, the filler is selected from the group consisting of clay (e.g., kaolin or calcined kaolin), talcum, CaCO3 (e.g., PCC or GCC), TiO2, Al2O3, SiO2, bentonite, fibers, or mixtures thereof. The fibers preferably have a hydrophilic surface and a density close to that of water, i.e., preferably 0.85 to 1.15 g / cm3. 3 or in the range of 0.90~1.10g / cm 3 In some embodiments, the filler is selected from the group consisting of clay, talcum, CaCO3, and fiber, or combinations thereof.

[0046] In some embodiments, a plasticizer is added to the aqueous barrier coating composition to increase the elasticity and make the resulting film or coating less brittle, allowing the resulting film or coating to better withstand bending without losing its barrier properties. In some embodiments, the aqueous barrier coating composition comprises 1-30 wt. % plasticizer, based on the total solids content of the aqueous barrier coating composition.

[0047] In some embodiments, the plasticizer is an organic compound containing multiple hydroxyl groups, such as a diol, triol, or other polyol. In some embodiments, the plasticizer is selected from the group consisting of glycerol, xylitol, sorbitol, maltitol, ethylene glycol, propylene glycol, butanediol, pentaerythritol, trimethylolpropane, and combinations thereof.

[0048] The aqueous barrier coating composition may also include a polycationic polymer acting as a crosslinker or insolubilizer, which is particularly useful when the first and / or second polysaccharides are anionic.

[0049] In some embodiments, the aqueous barrier coating composition comprises 0.1 to 10 wt. % of the polycationic polymer, based on the total solids content of the aqueous barrier coating composition.

[0050] Polycationic polymers are synthetic or natural polymers that contain multiple cationic functional groups.Examples of polycationic polymers for use in the present invention are 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-co-dimethylaminopropylacrylamide), polyvinyl(acrylamide-co-dimethylaminoethylmethacrylate), polyethyleneimine, polylysine, DAB-Am, and PAMAM. Dendrimers, polyaminoamides, polyhexamethylenebiguandide, polydimethylamine-epichlorohydrin, aminopropyltriethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, N-trimethoxysilylpropyl-N,N,N-trimethylammonium chloride, bis(trimethoxysilylpropyl)amine, chitosan, cationic starch, cationic gelatin, alkylation products of polyethyleneimine with methyl chloride, alkylation products of polyaminoamides with epichlorohydrin, cationic polyacrylamides containing cationic monomers, dimethylaminoethyl acrylate methyl chloride (AETAC), dimethylaminoethyl methacrylate methyl chloride (METAC), acrylamidopropyl trimethylammonium chloride (APTAC), methacrylamidopropyl trimethylammonium chloride (methacrylamidopropyl trimethylammonium chloride), amodopropyl trimethyl ammonium chloride (MAPTAC), diallyldimethylammonium chloride (DADMAC), ionenes, silanes, and mixtures thereof.The polycationic polymer may also be a polycationic polypeptide or protein.

[0051] In some embodiments, the cationic polymer is selected from the group consisting of polyaminoamides, polyethyleneimines, polyvinylamines, polydiallyldimethylammonium chloride (pDADMAC), chitosan, cationic starch, and cationic gelatin.

[0052] In a preferred embodiment, the polycationic polymer is polyethyleneimine (PEI).

[0053] In some embodiments, the polycationic polymer has a weight average molecular weight in the range of 2 000 to 1 000 000 g / mol, preferably in the range of 10 000 to 100 000 g / mol.

[0054] The coating composition is preferably provided in a formulation suitable for application to paper or paperboard using conventional paper coating equipment and techniques, such as blade coaters, bar coaters, and curtain coaters. Thus, the coating composition may contain 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, wetting agents, barrier chemicals, and pH adjusters (e.g., NaOH).

[0055] The aqueous barrier coating composition can be applied to a substrate and dried to form a barrier film or coating. Thus, according to a second embodiment exemplified herein, a barrier film or coating is provided, comprising: 20-80 wt. % based on the total solids content of the barrier film or coating of a first polysaccharide having a first degree of polymerization (DP1) of at least 150; and 20-80 wt. % based on the total solids content of the barrier film or coating of a second polysaccharide having a second degree of polymerization (DP2) of 100 or less. Includes; The ratio of DP1:DP2 is at least 10:1, A barrier film or coating is provided.

[0056] The barrier film or coating is preferably dry or substantially dry. The barrier film or coating preferably has a total solids content of greater than 90% by weight, preferably greater than 95% by weight.

[0057] It is understood 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 20-80 wt.% dry content of the first polysaccharide in the aqueous barrier coating composition will result in a 20-80 wt.% content of the first polysaccharide in the dry barrier film or coating.

[0058] The film or coating according to the invention has a coating weight of 30 g / m 2 It may generally have a basis weight of: typically at least 1 g / m to provide acceptable barrier properties 2 In some embodiments, the basis weight of the film or coating is between 5 and 15 g / m 2 in the range of 5 to 10 g / m 2 is within the range.

[0059] The film or coating according to the 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, more particularly, 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 to 15 μm, preferably in the range of 5 to 10 μm.

[0060] In some embodiments, the barrier film or coating is prepared from an aqueous barrier coating composition as described herein with respect to the first aspect.

[0061] The barrier films or coatings of the present invention have good oxygen and grease barrier properties.

[0062] In some embodiments, the barrier film or coating has a viscosity of 50 cc / m2, measured according to ASTM D-3985 standard at 50% relative humidity and 23° C. 2 / 24h / atm or less, preferably 30cc / m 2 / 24h / atm or less, more preferably 10cc / m 2 / 24h / atm and has an oxygen transmission rate (OTR) of less than 100%.

[0063] In some embodiments, the barrier film or coating has a KIT value of at least 8, preferably at least 10, when measured according to the TAPPI T559 standard.

[0064] The aqueous barrier coating composition according to the first aspect and the barrier film or coating according to the second aspect are preferably bio-based. As used herein, the term bio-based refers to a product or material that is derived in whole or in part from biomass, such as plants, trees, or animals. The biomass may have been subjected to physical, chemical, or biological treatments. Preferably, at least 75% by weight, more preferably at least 90% by weight, of the total solids content of the aqueous barrier coating composition according to the first aspect or the barrier film or coating according to the second aspect is bio-based.

[0065] According to a third aspect exemplified herein, there is provided a coated substrate comprising a substrate coated with an aqueous barrier coating composition according to the first aspect.

[0066] The aqueous barrier coating composition according to the first aspect is particularly interesting for coating fiber-based substrates. Thus, in some embodiments, the coated substrate is a fiber-based substrate. The fiber-based substrate is preferably paper or paperboard.

[0067] Paper generally refers to a material manufactured in sheets or rolls from wood pulp or other fibrous substances containing cellulose fibers, for example, used for writing, drawing, or printing, or used as a packaging material. Paper can be bleached or unbleached, coated or uncoated, and can be made in a variety of thicknesses depending on the requirements of the end use.

[0068] Paperboard generally refers to strong, thick paper or cardboard containing cellulose fibers that is used, for example, as flat substrates, trays, boxes, and / or other types of packaging. Paperboard can be bleached or unbleached, coated or uncoated, and can be made in a variety of thicknesses depending on the requirements of the end use.

[0069] The aqueous barrier coating composition can be added on the papermaking machine (on-machine coating) or on a separate machine (off-machine coating). A variety of paper coating equipment and techniques may be used to apply the coating composition, such as blade coaters, bar coaters, air knife coaters, curtain coaters, and cast coaters. The coating composition can be applied to one or both sides of the paper or paperboard.

[0070] The surface of the paper or paperboard to which the aqueous barrier coating is applied may preferably be pretreated to reduce the porosity of the surface, for example by dispersion coating with a mineral coating. In this way, the amount of aqueous barrier coating can be reduced. Thus, in some embodiments, the coated substrate is a dispersion coated, preferably mineral coated, paper or paperboard.

[0071] The coated substrate is preferably suitable for repulping. In some embodiments, the coated substrate has a repulpability characterized by a rejection rate (as 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%.

[0072] Thus, according to a fourth aspect exemplified herein, there is provided a method for producing a barrier film or coating, comprising the steps of: a) preparing an aqueous barrier coating composition as described herein with respect to the first aspect; b) forming a wet film or coating of the aqueous barrier coating composition; c) drying the wet film or coating to obtain a barrier film or coating. A method is provided, comprising:

[0073] The aqueous barrier coating composition has a total solids content in the range of 10 to 90 wt %. In some embodiments, the aqueous barrier coating composition has a total solids content in the range of 10 to 80 wt %, preferably in the range of 20 to 70 wt %, and more preferably in the range of 20 to 50 wt %.

[0074] In the drying step c) the total solids content of the wet film or coating is increased by evaporation of water. The resulting barrier film or coating preferably has a total solids content of more than 90% by weight.

[0075] In some embodiments, the basis weight of the dry barrier film or coating is from 5 to 15 g / m 2 in the range of 5 to 10 g / m 2 is within the range.

[0076] In some embodiments, the thickness of the dry barrier film or coating is in the range of 1 to 15 μm, preferably in the range of 5 to 10 μm.

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

[0078] As used herein, the term film generally refers to a material formed into a thin continuous sheet. As used herein, the term barrier film generally refers to a film designed to provide good barrier properties.

[0079] Generally, the products, polymers, materials, layers, and processes are described in terms of "comprising" various components or steps, but the products, polymers, materials, layers, and processes can also "consist essentially of" or "consist of" various components and steps.

[0080] While the invention has been described in terms of various exemplary embodiments, those skilled in the art will recognize that various modifications can be made and equivalents substituted for elements thereof without departing from the scope of the invention. In addition, many modifications can be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is not intended that the invention be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but the invention will include all embodiments falling within the scope of the appended claims. EXAMPLES

[0081] material - Dry xylan powder, DP2~7, purity 95%, moisture content 2% (Coreychem) - Sorbitol powder, 95% purity, 2% moisture content (Cargill) - CMC powder, DP200, purity 95%, moisture content 12% (Nouryon)

[0082] Example 1 - Preparation of Xylan / CMC / Sorbitol / Water Mixture A 65% xylan solution was prepared by slowly adding 13.4 kg of xylan powder to a stirred vessel containing 7 kg of water at 70° C. 22% CMC and 50% sorbitol solutions in water at 70° C. were prepared in the same manner.

[0083] Example 2 - Preparation of coating pigment The solutions prepared in Example 1 were mixed to obtain an aqueous coating composition having a total solids content of 26.7 wt %, containing 55.5% CMC, 26% xylan, and 18.5% sorbitol based on the total solids content of the composition. The mixture had a viscosity of 670 centipoise at 40° C.

[0084] Example 3 - Coating of Paperboard Off-line coating with rod, IR and air dryer at a speed of 200 m / min was performed using a short residence time application on a paperboard substrate (Natura Life 260 g / m 2 Coating pigments were applied onto the surface of the samples (uncoated and coated). The samples were coated with either one layer (sample ID1) or two layers (sample ID2), each with a coat weight of 6 g / m2. 2 and 12 g / m 2 The samples were conditioned at 23°C and 50% relative humidity (RH) for several days before analysis.

[0085] analysis The samples were tested for pinhole formation, grease resistance (KIT), and oxygen permeability (Oxygen Transmission Rate, OTR) as follows. - Oxygen transfer rate (OTR) was measured according to ASTM D3985 at a temperature of 23°C and a relative humidity (RH) of 50%. - The number of pinholes is measured according to EN 13676: 2001. The measurement involves treating the packaging material with a colouring solution (e.g. dye E131 blue in ethanol) and examining the surface under a microscope. - The KIT value is a measure of grease resistance and is measured according to TAPPI T559.

[0086] The results of the analysis are shown in Table 1. TIFF2024523213000001.tif38170

Claims

1. 1. An aqueous barrier coating composition comprising: 20-80 wt. %, based on the total solids content of the aqueous barrier coating composition, of a dissolved first polysaccharide having a first degree of polymerization (DP1) of at least 150; and 20-80 wt. %, based on the total solids content of the aqueous barrier coating composition, of a dissolved second polysaccharide having a second degree of polymerization (DP2) of 100 or less. Including; The ratio of DP1:DP2 is at least 10:1; The aqueous barrier coating composition has a total solids content in the range of 10 to 90 wt. %. Aqueous barrier coating compositions.

2. 2. The aqueous barrier coating composition of claim 1, wherein the ratio of DP1:DP2 is at least 20:1, preferably at least 30:

1.

3. 2. The aqueous barrier coating composition of claim 1, wherein the aqueous barrier coating composition comprises 30 to 80 wt. %, preferably 40 to 80 wt. %, more preferably 50 to 80 wt. % of the first polysaccharide based on the total solids content of the aqueous barrier coating composition.

4. 2. The aqueous barrier coating composition of claim 1, wherein DP1 is in the range of 150-4000, preferably in the range of 150-2000, more preferably in the range of 150-1000.

5. 10. The aqueous barrier coating composition of claim 1, wherein the first polysaccharide is selected from the group consisting of water soluble hemicellulose, water soluble cellulose, water soluble starch, alginate, chitosan, pullulan, dextran, and agarose.

6. 10. The aqueous barrier coating composition of claim 1, wherein the first polysaccharide is selected from the group consisting of water soluble hemicellulose, water soluble cellulose, water soluble starch, and alginate.

7. 10. The aqueous barrier coating composition of claim 1, wherein the first polysaccharide is selected from the group consisting of carboxymethyl cellulose, methyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, hydroxypropyl methyl cellulose, ethyl hydroxyethyl cellulose, and methyl ethyl hydroxyethyl cellulose.

8. 10. The aqueous barrier coating composition of claim 1, wherein the first polysaccharide is carboxymethyl cellulose (CMC).

9. 2. The aqueous barrier coating composition of claim 1, wherein the aqueous barrier coating composition comprises 20-60 wt.%, preferably 20-40 wt.%, more preferably 20-30 wt.% of the second polysaccharide based on the total solids content of the aqueous barrier coating composition.

10. 2. The aqueous barrier coating composition of claim 1, wherein DP2 is in the range of 2-50, preferably in the range of 2-25, more preferably in the range of 2-12.

11. 10. The aqueous barrier coating composition of claim 1, wherein the second polysaccharide is selected from the group consisting of water soluble hemicellulose, water soluble cellulose, water soluble starch, alginate, chitosan, pullulan, dextran, and agarose.

12. 10. The aqueous barrier coating composition of claim 1, wherein the second polysaccharide is selected from the group consisting of water soluble hemicellulose, water soluble cellulose, water soluble starch, and alginate.

13. 10. The aqueous barrier coating composition of claim 1, wherein the second polysaccharide is a xylan.

14. 10. The aqueous barrier coating composition of claim 1 further comprising 1 to 30 wt. % of a filler, based on the total solids content of the aqueous barrier coating composition.

15. Fillers include clay, talcum, and CaCO ３ 15. The aqueous barrier coating composition of claim 14, wherein the polymer is selected from the group consisting of:

16. 10. The aqueous barrier coating composition of claim 1 further comprising 1 to 30 wt. % of a plasticizer, based on the total solids content of the aqueous barrier coating composition.

17. 17. The aqueous barrier coating composition of claim 16, wherein the plasticizer is selected from the group consisting of glycerol, xylitol, sorbitol, maltitol, ethylene glycol, propylene glycol, butanediol, pentaerythritol, trimethylolpropane, and combinations thereof.

18. 10. The aqueous barrier coating composition of claim 1 further comprising 0.1 to 10 wt. % of a polycationic polymer, based on the total solids content of the aqueous barrier coating composition.

19. 20. The aqueous barrier coating composition of claim 18, wherein the polycationic polymer is polyethyleneimine (PEI).

20. 2. The aqueous barrier coating composition of claim 1, wherein the aqueous barrier coating composition has a total solids content in the range of 10 to 80 wt%, preferably in the range of 20 to 70 wt%, more preferably in the range of 20 to 50 wt%.

21. 1. A barrier film or coating comprising: 20-80 wt. %, based on the total solids content of the barrier film or coating, of a first polysaccharide having a first degree of polymerization (DP1) of at least 150; and 20-80 wt. %, based on the total solids content of the barrier film or coating, of a second polysaccharide having a second degree of polymerization (DP2) of 100 or less. Including; The ratio of DP1:DP2 is at least 10:1; Barrier films or coatings.

22. The basis weight of the film or coating is 5 to 15 g / m ２ in the range of 5 to 10 g / m ２ 22. The barrier film or coating of claim 21, wherein the molecular weight is in the range of

23. 22. A barrier film or coating according to claim 21, wherein the thickness of the film or coating is in the range of 1 to 15 μm, preferably in the range of 5 to 10 μm.

24. 22. The barrier film or coating of claim 21 , wherein the barrier film or coating is prepared from the aqueous barrier coating composition of claim 1 .

25. The barrier film or coating has a viscosity of 50 cc / m2, measured according to ASTM D-3985 standard at 50% relative humidity and 23°C. ２ / 24h / atm or less, preferably 30cc / m ２ / 24h / atm, more preferably less than 10cc / m ２ 22. The barrier film or coating of claim 21 having an oxygen transmission rate (OTR) of less than 1 / 24h / atm.

26. 22. The barrier film or coating of claim 21, wherein the barrier film or coating has a KIT value of at least 8, preferably at least 10, when measured according to TAPPI T559 standard.

27. 13. A coated substrate comprising a substrate coated with the aqueous barrier coating composition of claim 1.

28. 28. The coated substrate of claim 27, wherein the coated substrate is a fiber-based substrate, preferably paper or paperboard, preferably mineral coated paper or paperboard.

29. 28. The coated substrate of claim 27, wherein the coated substrate has a repulpability characterized by a rejection rate (as determined according to 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%.

30. 1. A method for producing a barrier film or coating, comprising: a) preparing an aqueous barrier coating composition according to claim 1; b) forming a wet film or coating of the aqueous barrier coating composition; c) drying the wet film or coating to obtain a barrier film or coating. A method comprising:

31. The basis weight of the dry barrier film or coating is between 5 and 15 g / m ２ in the range of 5 to 10 g / m ２ The method of claim 30, wherein the range is:

32. The method according to claim 30, wherein the thickness of the dry barrier film or coating is in the range of 5 to 15 μm, preferably in the range of 5 to 10 μm.