Aqueous composition, use thereof and method for providing at least one barrier property

Abstract

The present invention relates to an aqueous composition for providing at least one barrier property, such as grease, oil and / or water barrier properties, to a product comprising cellulosic fibers, and to the use of the composition. The composition comprises an alpha-(1, 3-glucan) polymer and at least 0.1% by weight, calculated by the dry solids weight of the composition, of an alkyl ketene dimer.

Description

Technical Field

[0001] The present invention relates to an aqueous composition, its use and a method for providing at least one barrier property according to the preambles of the attached independent claims. Background Art

[0002] There is a growing trend towards reducing the use of plastics as packaging materials for various goods. Natural alternatives to plastics are products based on cellulose fibers, such as paper and board. Paper and board are essentially two-dimensional sheet products that can be folded into three-dimensional packaging. Three-dimensional packaging can also be manufactured using cellulose fibers by using molded fiber technology. Cellulose fiber-based packaging materials generally provide strength properties suitable for protecting the goods being packaged.

[0003] However, in certain applications, packaging materials should also have barrier properties, thereby preventing the transfer of moisture, liquids, oils, greases and / or gases through the packaging material. The packaging material should have sufficient barrier properties to prevent the packaged goods from interacting with the surrounding environment through the packaging material. The problem is that packaging materials based on cellulose fibers do not necessarily have the barrier properties that are desired, especially for food packaging purposes.

[0004] The barrier properties of cellulose fiber-based materials can be improved by internal sizing or various surface treatments. Internal sizing alone does not necessarily provide the desired barrier properties for moisture, liquids, grease and oil. The conventional solution of laminating a plastic film on the surface of a cellulose fiber-based material is not entirely without problems. The laminated plastic film may cause problems when the packaging material is recycled (e.g. during repulping and composting). In addition, film lamination technology is not suitable for providing barrier properties for three-dimensional molded fiber products.

[0005] In view of the above, there is a constant need to improve the barrier properties of cellulosic fiber based packaging materials. In particular, there is a need for compositions that provide barrier properties and can be applied to both two-dimensional and three-dimensional articles. Preferably, the composition used to provide barrier properties is also bio-based, biodegradable and recyclable, thereby reducing the use of petroleum-based components, bioaccumulation and carbon footprint in the packaging industry. Summary of the invention

[0006] The object of the present invention is to minimize or even eliminate the disadvantages existing in the prior art.

[0007] The present invention also aims to provide an aqueous composition which provides at least one barrier property, preferably at least two barrier properties, to products comprising cellulose fibers and which can be easily applied even on three-dimensional articles.

[0008] These objects are achieved by the invention having the following features presented in the characterizing part of the independent claim. Some preferred embodiments of the invention are presented in the dependent claims. Unless explicitly stated otherwise, the features recited in the dependent claims can be freely combined.

[0009] A typical aqueous composition according to the invention for providing at least one barrier property, such as grease, oil, fat, water, gas and / or mineral oil barrier properties, to a product comprising cellulosic fibers comprises an α-(1,3→ glucan) polymer and at least 0.1 wt. % of an alkyl ketene dimer, calculated on the dry solids weight of the composition.

[0010] According to the invention, a typical use of the aqueous composition of the invention is for providing at least one barrier property, such as grease, oil, fat, water, gas and / or mineral oil barrier properties, to a product comprising cellulosic fibers by applying the aqueous composition to the surface of the product.

[0011] Typical methods for providing at least one barrier property, such as grease, oil, fat, water, gas and / or mineral oil barrier properties, to a cellulosic product comprising cellulosic fibers include:

[0012] - forming a cellulose product,

[0013] - drying of the cellulose product,

[0014] - Applying the aqueous composition of the invention to at least one surface of a product.

[0015] It has now been unexpectedly discovered that an aqueous composition comprising an α-(1,3→glucan) polymer and an alkyl ketene dimer is easily applied to the surface of a product comprising cellulose fibers using conventional surface application techniques. In addition, the composition comprising an α-(1,3→glucan) polymer and an alkyl ketene dimer prepared by mixing also provides unexpectedly good barrier properties to the product. The barrier properties obtained may include at least one selected from grease, oil, fat, water, gas and mineral oil barrier properties, and may and preferably include multiple barrier properties. Compared to other possible polysaccharide polymers such as starch or carboxymethyl cellulose, the α-(1,3→glucan) polymer provides acceptable or good barrier properties for the surface treated product. This means that the amount of bio-based and biodegradable components can be increased in the manufacture of cellulose products, especially in the manufacture of cellulose packaging materials, without seriously compromising the quality of the final product. Presumably, the recyclability of the surface treated product may be made easier, allowing repulping by using conventional repulping techniques. At a minimum, the components of the aqueous composition are readily biodegradable, which may provide additional and / or new replacement options when considering end-of-life options for surface treated products.

[0016] The present invention can provide a product comprising cellulose fibers having at least two barrier properties selected from grease, oil, fat, water, gas and mineral oil barrier properties. In general, especially in food contact applications, it is important that products comprising cellulose fibers show acceptable grease, oil and water barrier properties. Previously, this may have required the use of a variety of different barrier compositions. The present invention now provides an aqueous composition that can be used alone to provide a product with a variety of barrier properties. According to one embodiment, the aqueous composition can provide a product comprising cellulose fibers with a combination of good or at least acceptable water barrier properties and good or at least acceptable grease and oil barrier properties.

[0017] The aqueous composition may be a coating composition or a surface sizing composition, or it may form part of a coating composition or a surface sizing composition for a cellulosic fibrous web (eg, paper, board, etc.) or for a cellulosic product (eg, a molded fiber product).

[0018] The aqueous composition may comprise 65-99.9 wt %, preferably 70-99 wt %, more preferably 75-95 wt % of α-(1,3→glucan) polymer calculated on the dry solid weight of the composition. For example, the aqueous composition may comprise 60-99.9 wt %, preferably 65-90 wt %, more preferably 70-85 wt % of α-(1,3→glucan) polymer calculated on the dry solid weight of the composition. According to a preferred embodiment, the aqueous composition may comprise 60-93 wt %, preferably 65-89 wt %, more preferably 70-87 wt % of α-(1,3→glucan) polymer calculated on the dry solid weight of the composition. Surprisingly, the aqueous composition can comprise such a large amount of α-(1,3→glucan) polymer while providing appropriate barrier properties to the final product. This means that in the barrier layer formed, the amount of non-biobased components can be minimized, making the final product more environmentally sustainable.

[0019] In the present context, "α-(1,3→glucan) polymer" refers to a polymer having a polysaccharide backbone comprising D-glucose units linked together by glycosidic bonds. At least 70%, preferably at least 80%, more preferably at least 90% or 95%, sometimes even 99% or 100% of the glycosidic bonds are α-1,3-bonds. This means that in the polysaccharide backbone, the α-D-glucose units are linked to each other via carbon 1 and carbon 3 on adjacent α-D-glucose rings. The form of the glycosidic bonds can be determined by a person skilled in the art by using known methods, such as 1 Determined by HNMR.

[0020] According to one embodiment of the present invention, the α-(1,3→glucan) polymer may have a degree of polymerization within a range of 55-10000, preferably 55-5000, more preferably 100-1000.

[0021] The polysaccharide backbone of the α-(1,3→ glucan) polymer may be linear, ie it may be unbranched.

[0022] The polysaccharide backbone of the α-(1,3→glucan) polymer may be substituted, i.e., the α-(1,3→glucan) copolymer may contain substituent groups that replace the hydroxyl groups of the polysaccharide backbone. According to one embodiment of the present invention, the α-(1,3→glucan) polymer may have a degree of substitution in the range of 0.05-3, preferably 0.1-2.0, preferably 0.2-1.5, more preferably 0.2-1 or 0.2-0.8. For example, the degree of substitution may be 0.3-0.7 or 0.3-0.6. The degree of substitution refers to the average number of hydroxyl groups substituted in each D-glucose unit in the polysaccharide backbone of the α-(1,3→glucan) polymer. Since there are three hydroxyl groups in each D-glucose unit, the degree of substitution cannot be higher than 3.

[0023] According to a preferred embodiment, the α-(1,3→glucan) polymer may be a polyhydroxyalkyl α-(1,3→glucan), such as polyhydroxyethyl α-(1,3→glucan).

[0024] The aqueous coating composition may contain anionic or cationic α-(1,3→glucan) polymers. The anionicity or cationicity of the α-(1,3→glucan) polymer may have a positive effect on its water solubility.

[0025] According to one embodiment of the present invention, the α-(1,3→glucan) polymer used may be anionic, ie, its structure contains anionic groups, such as carboxyl groups.

[0026] According to a preferred embodiment, the α-(1,3→glucan) polymer is cationic, i.e. it contains cationic substituents. The cationic substituents may be substituted ammonium groups, preferably quaternary ammonium groups, more preferably trialkylammonium groups. The alkyl group in the trialkylammonium group may be, for example, methyl, hydroxymethyl, hydroxyethyl or hydroxypropyl. The substituted ammonium group may be, for example, a trimethylammonium group. The cationic substituents increase the water solubility of the α-(1,3→glucan) polymer.

[0027] According to a preferred embodiment, the α-(1,3→glucan) polymer is water-soluble. This means that the α-(1,3→glucan) polymer is soluble in water at a concentration of 1% by weight at 25°C and at pH 7. After dissolution, no solid particles are visually observed and the resulting solution is completely transparent. The water solubility provides uniform and good coverage for the obtained barrier layer formed by applying the aqueous composition.

[0028] The aqueous composition according to the present invention further comprises at least 0.1% by weight of alkyl ketene dimer calculated on the basis of the dry solid weight of the composition. According to a preferred embodiment of the present invention, the composition may comprise 0.1-35% by weight, preferably 1-30% by weight, more preferably 5-25% by weight of alkyl ketene dimer calculated on the basis of the dry solid weight of the composition. The composition may comprise 0.1-40% by weight, preferably 10-35% by weight, more preferably 15-30% by weight of alkyl ketene dimer calculated on the basis of the dry solid weight of the composition. According to a preferred embodiment, the aqueous composition may comprise 7-40% by weight, preferably 11-35% by weight, more preferably 13-30% by weight of alkyl ketene dimer calculated on the basis of the dry solid weight of the composition. Alkyl ketene dimer is able to enhance the water barrier properties provided by the aqueous composition while maintaining the obtainable grease and oil barrier properties at least at an acceptable level. Thus, as described above, the presence of the alkyl ketene dimer, even when present in relatively low amounts in the aqueous composition, improves the overall barrier properties and may provide more than one improved barrier property to a product comprising cellulosic fibers.

[0029] The alkyl ketene dimer may be a C14-C22 alkyl ketene dimer, preferably a C16-C18 alkyl ketene dimer, or a mixture thereof. When the alkyl ketene dimer is mixed with an α-(1,3→glucan) polymer to form an aqueous composition, it may be in the form of a polysaccharide-stabilized aqueous dispersion.

[0030] At pH 3.5, the alkyl ketene dimer has a charge density in the range of -100 µmeq / g to +600 µmeq / g. According to one embodiment, the alkyl ketene dimer is cationic. At pH 3.5, the cationic alkyl ketene dimer has a charge density in the range of +25 µmeq / g to +600 µmeq / g, preferably +50 µmeq / g to +250 µmeq / g, more preferably +75 to +150 µmeq / g. According to another embodiment, the alkyl ketene dimer may be anionic. At pH 3.5, the cationic alkyl ketene dimer has a charge density in the range of -100 µmeq / g to <0 µmeq / g, preferably -75 µmeq / g to 0.1 µmeq / g, more preferably -25 to -5 µmeq / g.

[0031] Preferably, the alkyl ketene dimer and the α-(1,3→glucan) polymer have the same ionicity, i.e. they are both anionic or cationic. According to a preferred embodiment, the α-(1,3→glucan) polymer and the alkyl ketene dimer are both cationic. According to another preferred embodiment, the α-(1,3→glucan) polymer and the alkyl ketene dimer are both anionic. According to another embodiment, the alkyl ketene dimer and the α-(1,3→glucan) polymer have different ionicities.

[0032] The aqueous composition according to the present invention is prepared by mixing an α-(1,3→glucan) polymer and an alkyl ketene dimer. It is expected that no chemical reaction will occur between the α-(1,3→glucan) polymer and the alkyl ketene dimer and between the alkyl ketene dimer. This means that the aqueous composition has no covalent bonds between the α-(1,3→glucan) polymer and the alkyl ketene dimer. The aqueous composition is easy to prepare by mixing with conventional mixing equipment and still provides good barrier properties when applied to the surface of a fiber product comprising cellulose fibers.

[0033] In addition to the α-(1,3→glucan) polymer and the alkyl ketene dimer, the aqueous composition may further comprise one or more additives. The amount of the additive may be 0.25-20 parts, preferably 0.5-15 parts, more preferably 1-10 parts, more preferably 2-5 parts, calculated relative to the total amount of the alkyl ketene and the α-(1,3→glucan) polymer (which has been related to a value of 100). The one or more additives may be selected from inorganic particles, such as kaolin, calcium carbonate, talc, titanium dioxide and any mixture thereof; defoamers, such as silica-based defoamers; rheology modifiers, such as acrylates, acrylic acid copolymers and / or hydrophobically modified ethoxylated urethanes; wetting agents, such as surfactants; other barrier-promoting polymers and / or heat-sealable polymers, such as styrene acrylates. The aqueous composition preferably does not contain an organic solvent.

[0034] According to one embodiment, the aqueous composition consists of an α-(1,3→ glucan) polymer and an alkyl ketene dimer and optionally inorganic particles as described above.

[0035] The aqueous composition can be applied on the surface of the product comprising cellulose fibers by using any conventional coating and / or surface sizing method, such as rod coating, curtain coating, sizing press coating or spraying. The aqueous composition can have a solid content in the range of 2.5-50% by weight, preferably 5-35% by weight, more preferably 10-25% by weight. The aqueous composition can have a viscosity in the range of 50-2000 mPas, preferably 50-1000 mPas, measured at 23 ° C, 100 rpm with Brookfield DV-E. This means that by using conventional application methods, such as surface sizing, air knife coating (air knife coating), rod coating (rod coating), bar coating (bar coating), blade coating, gravure coating, roller coating, curtain coating, sizing press coating (size press coating) or spraying, it is easy to apply the composition on the surface of the product comprising cellulose fibers. In some embodiments, the aqueous composition can be heated before application to reduce viscosity. For example, the aqueous composition may be applied at an application temperature of 15-50°C, typically 20-40°C.

[0036] The aqueous composition according to the present invention is applied on the surface of a product comprising cellulose fibers. The cellulose fibers can be virgin fibers or regenerated fibers, or a mixture of virgin fibers and regenerated fibers. The cellulose fibers can be obtained by any available pulping method, for example by mechanical pulping, chemical pulping, thermomechanical pulping or chemical thermomechanical pulping. The cellulose fibers can include any cellulose fibers separated, for example, from wood (softwood, hardwood or a combination thereof). The cellulose fibers can be bleached, unbleached or a combination thereof.

[0037] In addition to cellulose fibers, the product may also contain inorganic filler particles, such as particles of calcium carbonate, kaolin, talc, titanium dioxide or any combination thereof.

[0038] Preferably, the aqueous composition is applied directly to the surface of the product comprising cellulose fibers, i.e. without any intermediate layer. The aqueous composition can be applied to the surface of the product before and / or after the product is dried. This means that the application can be carried out, for example, by spraying on a wet surface, and / or on a dry surface, for example by using any conventional coating technique, such as spraying, rod coating or size press coating.

[0039] According to a preferred embodiment, the aqueous composition of the invention is applied by spraying on the surface of a three-dimensional product comprising cellulose fibers, for example on the surface of a molded fiber product. The molded fiber product may be a bowl, a container, a tray, a board, etc. According to one embodiment, the molded product comprising cellulose fibers may be a ready-to-eat meal packaging unit, an egg container, a meat container, a cup, a sip lid, or a food-carrying product such as a tray or a board. By applying the aqueous composition by spraying, even cavities, compartments, recesses, etc. of a three-dimensional product may be effectively covered.

[0040] According to one embodiment, an aqueous composition can be applied on the surface of a first product comprising cellulose fibers or cellulose fibers, and thereafter and before drying the applied composition, at least one second product is attached to the surface of the first product by using the applied aqueous composition as an adhesive between the first product and the second product. Therefore, the final product obtained comprises a first layer consisting of the first product and at least one second layer consisting of the second product and an intermediate adhesive layer formed by the applied aqueous composition. Optionally, an additional second product is attached to further enhance the performance and characteristics of the product, thereby applying the aqueous composition as an adhesive between additional third products. The first product and the second product can be in the form of a sheet or a net with two parallel large surfaces, wherein the aqueous composition is applied to at least one of the large surfaces of the first product, and at least one of the large surfaces of the second product is attached thereto. Alternatively, the first product and the second product can have a three-dimensional form arranged to fit closely to each other, and the aqueous composition is sprayed on the surface of the first product, and then the second product is appropriately matched to the first product for attachment.

[0041] The aqueous composition may be applied in an amount to provide a uniform barrier layer on the surface of the product or in an amount to provide adequate adhesion between a first product and a second product. The aqueous composition may be applied as two or more layers on the surface of the product. In this way, the amount of aqueous composition in each layer may be lower and / or a barrier layer with a small number of pinholes (if any) may be obtained. The chemical composition of the applied layers is the same, but the applied amount, i.e., the layer weight, may be different. In one embodiment, all applied layers are identical to one another. The aqueous composition may be applied in an amount of at least 1.5 g / m 2 , preferably 1.5-15 g / m 2 , more preferably 2-10 g / m 2 The aqueous composition is added in a total amount of .

[0042] According to one embodiment of the present invention, the aqueous composition is applied to cover a portion of the surface of the product. For example, the aqueous composition may be applied to the inner or outer surface of a three-dimensional product, such as by spraying.

[0043] If the product comprising cellulose fibers is coated with two or more successive layers of the aqueous composition, the successive layers after the first layer can be applied with or without intermediate drying (i.e. applied as a wet-dry or wet-wet coating). According to one embodiment, the surface of the product is dried between the application of the two or more successive layers.

[0044] The aqueous composition according to the invention provides at least one barrier property, such as grease, oil and / or water barrier properties, to products comprising cellulosic fibers. Preferably, the aqueous composition provides at least two barrier properties simultaneously, in particular grease and water barrier properties simultaneously. It has surprisingly been found that the aqueous composition provides a significantly increased oil penetration time to products comprising cellulosic fibers.

[0045] According to a preferred embodiment, application of the aqueous composition provides the product with a TAPPI 559 KIT test value of at least 4, preferably at least 8, more preferably at least 12. The KIT test value measures the repellency of a coating to oil and grease and is measured according to standard TAPPI method T-559. DETAILED DESCRIPTION

[0046] experiment

[0047] Example 1

[0048] Preparation of 2D sheets

[0049] A fiber masterbatch with a consistency of 0.1-0.6 wt% was prepared from 100% birch kraft pale pulp. 0.02-0.06 wt% of alkyl ketene dimer AKD (based on dry weight) was added to the fiber masterbatch, the fiber masterbatch was mixed for at least 2 minutes under turbulent conditions, and then 0.04-0.08 wt% of a mixture of synthetic retention polymers polydiallyldimethylammonium chloride and cationic polyacrylamide (PDACMAC+CPAM) (based on dry weight) was added. The retention polymers used have a high to very high average molecular weight MW (at least 2 000 000 Da), and they have a low to medium charge density (5-20 mol %, from cationic monomers). After adding PDADMAC+CPAM, the masterbatch was mixed for at least 1 minute and then vacuum formed at 200-650 mbar on a flat round forming wire with 200-400 µm openings and 10 cm. The fiber masterbatch was vacuum formed to 20-30 wt% dryness using a Dynamic Drainage Analyzer (Pulpeye AB, Sweden). The masterbatch with a grammage of 200-800 g / m 2 The wet sheet (by dry weight) is pressed between blotting paper until a dryness of 25-55% is reached. The sheet is then hot-press dried and thermoformed between metal plates at 130-200°C to a thickness of 0.2-1.2 mm until a dryness of 94-99% is reached. The final sheet obtained has a Bendtsen roughness of 300-700 ml / min measured according to ISO 8791-2 and a Bendtsen air permeability of 20-25 ml / min measured according to ISO 5636-3.

[0050] Preparation of aqueous compositions

[0051] A dried cationic α-(1,3→glucan) polymer (degree of polymerization 450; degree of substitution 0.3) was dissolved in deionized water to obtain a polymer solution having a concentration of 3.4 wt% (by dry weight). A commercially available cationic alkyl ketene dimer, which contained 95 wt% (by dry weight) of C18 alkyl ketene dimer, was obtained as a 20 wt% solution (by dry weight). The alkyl ketene dimer solution was added to the α-(1,3→glucan) polymer solution until the aqueous composition obtained had an alkyl ketene dimer concentration of 27.6 wt% calculated based on the dry solids content in the aqueous composition. The aqueous composition containing the α-(1,3→glucan) polymer and the alkyl ketene dimer was mixed until the two components were visually dispersed.

[0052] Spraying two-dimensional sheets with aqueous compositions

[0053] The prepared two-dimensional sheets were sprayed with the prepared aqueous composition by passing each sheet through the spray beam as many times as necessary to achieve a coating of 7.9-8.4 g / m 2 The coated sheets were dried in an oven at 105°C for 15 minutes. The dried sheets were conditioned at 23°C, RH 50%, and their barrier properties (oil penetration time) were measured according to ISO 535:2014 (Cobb60), Tappi T559 cm-02 (KIT), and ASTM F119-82:2015.

[0054] Reference sample R-1 was sprayed with a solution of a cationic alkyl ketene dimer having a concentration of 20 wt%, and reference samples R-2 and R-3 were sprayed with a solution of a cationic α-(1,3→glucan) polymer having a concentration of 3.6 wt%. Cationic alkyl ketene dimer and cationic α-(1,3→glucan) polymer are those used for aqueous compositions.

[0055] The results are shown in Table 1.

[0056] Table 1 Results of Example 1.

[0057]

[0058] From the results in Table 1, it can be seen that the aqueous composition according to the present invention provides the coated sheet with appropriate water barrier properties (Cobb 60) as well as good grease and oil barrier properties.

[0059] Example 2

[0060] The chemicals used in Example 2 are listed in Table 2. The chemicals were used as commercially available solutions (alkyl ketene dimer) or prepared in solution form by dissolving in hot water (α-(1,3→glucan) polymer, CMC) or cooking at 95° C. for 30 minutes (starch).

[0061] Table 2 Chemicals used in Example 2.

[0062]

[0063] According to Table 3, an aqueous composition was prepared by mixing the components of the composition in a Diaf mixer.

[0064] Table 3 Aqueous composition used in Example 2.

[0065]

[0066] In the coating experiments, the substrate used was 205 g / m 2 Folding box board. One or two coats were applied on uncoated substrates by using RK K ControlCoater rod coating unit. For single-coated samples, the coatings were applied by using coating rods 1-3. For double-coated samples, the coatings were applied by using coating rods 3-5, and the first layer was allowed to stand at room temperature for 15-30 minutes before applying the second layer. The final single / double coating was dried using an IR dryer for 60 seconds. The aqueous composition was kept at 40°C during the coating process.

[0067] The coated sheets were acclimatized for a minimum of 18 hours before measuring the coating weight.

[0068] The following barrier properties were tested using the standard methods given in brackets:

[0069] - Water vapor, WVTR (ASTM E-96, D3985 & F1927, 23°C 50% RH)

[0070] - Water, Cobb 300s (ISO 535)

[0071] - Grease and oil

[0072] • KIT test (TAPPI method T-559 pm-96)

[0073] • Olive oil permeability (ASTM F119-82:2015), 50°C

[0074] The Cobb300 value was measured from 2 replicates and the value is reported as the average of the two measurements. The olive oil permeability was measured for four replicates and the value is reported as the average of the measurements.

[0075] The results of Example 2 are given in Table 4.

[0076] As can be seen from Table 4, samples Composition-4 to Composition-7 coated with the aqueous composition according to the present invention provide better grease and oil barrier properties with acceptable water barrier properties. This difference is significant for the reference sample coated with the composition comprising alkyl ketene dimer and other polysaccharides (starch / CMC).

[0077] Table 4 Results of Example 2.

[0078]

[0079] Even though the present invention has been described with reference to what is currently considered the most practical and preferred embodiment, it should be understood that the present invention should not be limited to the above-described embodiment, but the present invention is intended to cover different modifications and equivalent technical solutions within the scope of the appended claims.

Claims

1. An aqueous composition for providing at least one barrier property, such as grease, oil and / or water barrier properties, to a product comprising cellulosic fibers, the composition comprising an α-(1,3→ glucan) polymer and at least 0.1 wt. % of an alkyl ketene dimer, calculated on the dry solids weight of the composition.

2. The aqueous composition according to claim 1, characterized in that The composition comprises 0.1-40 wt%, preferably 10-35 wt%, more preferably 15-30 wt% of alkyl ketene dimer calculated on the dry solid weight of the composition.

3. The aqueous composition according to claim 1 or 2, characterized in that α-(1,3→glucan) polymers and alkyl ketene dimers are cationic.

4. The aqueous composition according to claim 1 or 2, characterized in that α-(1,3→glucan) polymers and alkyl ketene dimers are anionic.

5. The aqueous composition according to any one of the preceding claims 1 to 4, characterized in that The α-(1,3→glucan) polymer has a degree of substitution in the range of 0.05-3, preferably 0.1-2.0, more preferably 0.2-1.5, even more preferably 0.2-1.

6. The aqueous composition according to any one of the preceding claims 1 to 5, characterized in that The α-(1,3→glucan) polymer has a degree of polymerization in the range of 55-10000, preferably 55-5000, more preferably 100-1000.

7. An aqueous composition according to any one of the preceding claims 1 to 6, characterized in that The alkyl ketene dimer is a C14-C22 alkyl ketene dimer, preferably a C16-C18 alkyl ketene dimer, or a mixture thereof, preferably in the form of a polysaccharide-stabilized aqueous dispersion.

8. An aqueous composition according to any one of the preceding claims 1 to 7, characterized in that At pH 3.5, the alkyl ketene dimers have a charge density ranging from -100 µm / g to +600 µmeq / g.

9. The aqueous composition according to any one of claims 1 to 8, characterized in that The composition has a solids content in the range of 2.5-50 wt%, preferably 5-35 wt%, more preferably 10-25 wt%, and / or a viscosity in the range of 50-2000 mPas, preferably 50-1000 mPas.

10. Use of the aqueous composition according to any one of claims 1 to 9 for providing at least one barrier property, such as grease, oil and / or water barrier properties, to a product comprising cellulosic fibers by applying the aqueous composition to the surface of the product.

11. The use according to claim 10, characterized in that The aqueous composition is applied by spraying on the surface of the product, preferably a three-dimensional product comprising cellulose fibers.

12. The use according to claim 10 or 11, characterized in that The products are molded fiber products such as bowls, containers, trays, boards, and the like.

13. The use according to claim 9, 10 or 11, characterized in that The aqueous composition is applied as two or more layers onto the surface of the product.

14. The use according to any one of the preceding claims 10 to 13, characterized in that At least 1.5 g / m 2 , preferably 1.5-15 g / m 2 , more preferably 2-10 g / m 2 The aqueous composition is added in a total amount of 15. A method for providing at least one barrier property, such as grease, oil and / or water barrier properties, to a cellulosic product comprising cellulosic fibers, the method comprising: - forming said cellulose product, - drying the cellulose product, - applying an aqueous composition according to any one of claims 1 to 9 to at least one surface of the product.

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