SE2151588A1

SE2151588A1 - Cellulose product with barrier

Info

Publication number: SE2151588A1
Application number: SE2151588A
Authority: SE
Inventors: Martin Malmqvist
Original assignee: Stora Enso Oyj
Priority date: 2021-12-22
Filing date: 2021-12-22
Publication date: 2023-06-23
Also published as: WO2023119004A1; SE545417C2

Abstract

A method for manufacturing a formed cellulose product (20) is disclosed. The method comprises forming a cellulose substrate (10) into a formed cellulose product (20). The method also comprises applying at least one polymerizable fatty acid or an oil or oil mixture comprising at least one polymerizable fatty acid to the cellulose substrate (10) prior to and/or during forming the cellulose substrate (10) into the formed cellulose product (20) and/or to the formed cellulose product (20). The method further comprises polymerizing the at least one polymerizable fatty acid to form a hydrophobation and grease barrier (25) of the formed cellulose product (20). The invention also relates to a cellulose article (10, 20) comprising such a hydrophobation and grease proofing barrier (25).

Description

CELLULOSE PRODUCT WITH BARRIER TECHNICAL FIELD The present invention generally relates to cellulose products and articles, and in particular to such cellulose products and articles comprising hydrophobation and grease prooﬁng barriers and methods for manufacturing formed cellulose products and articles comprising hydrophobation and grease prooﬁng barriers.

BACKGROUND Cellulose substrates, such as in the form of pulp sheets and air-laid blanks, are employed to manufacture formed cellulose products by means of, for instance, cutting, pressing, folding, thermoforming and/or dry molding the cellulose substrate. Some illustrative examples of such formed cellulose products include cutlery, plates, bowls, lids and caps, which can be employed as environmentally friendly products for use, for example, with beverages or food. Further examples include packaging products used to protect goods and articles against impact or shock, and/or providing thermal insulation for temperature sensitive goods and articles.

Surfaces of the formed cellulose products generally need to be protected by barriers, often referred to as hydrophobation and grease proofing barriers or surface sizing, to make the formed cellulose products more resistant against absorption of grease and liquids from goods, articles, foodstuff and beverage that will be in contact with the surfaces of the formed cellulose products during use.

Traditionally, barrier agents, such as hydrophobation and grease prooﬁng agents, are in the form of aqueous solutions or emulsions of, for instance, starches. The barrier agents are applied to the cellulose substrates prior to forming. The barrier agents cannot be applied to the formed cellulose products after forming since the formed cellulose products will absorb water from the aqueous solutions or emulsions causing undesired swelling and deformation of the formed cellulose products.

However, the manufacture of the formed cellulose products generally includes one or more cutting operations to get the desired shape of the formed cellulose products. The cutting operations lead to cut edges of the formed cellulose products that are not protected by any barrier agent since the barrier agent had been applied to the surfaces of the cellulose substrates prior to forming and cutting. These exposed edges are thereby not protected by any hydrophobation and grease prooﬁng barrier and may, thus, absorb liquid and grease when the formed cellulose products are in contact with goods, articles, beverages or food.

There is, thus, a need for formed cellulose products comprising hydrophobation and grease prooﬁng barriers for restriction of absorption of liquid and grease during use of the formed cellulose product. There is also a need for a formed cellulose product that e|iminates or a||eviates at least some of the disadvantages associated with prior art products.

SUMMARY lt is a general objective to provide cellulose products and articles comprising a hydrophobation and grease prooﬁng barrier.

This and other objectives are met by embodiments of the present invention.

The present invention is deﬁned in the independent claims. Further embodiments of the invention are deﬁned in the dependent claims.

An aspect of the invention relates to a method for manufacturing a formed cellulose product. The method comprises forming a cellulose substrate into a formed cellulose product. The method also comprises applying at least one polymerizable fatty acid or an oil or oil mixture comprising at least one polymerizable fatty acid to the cellulose substrate prior to and/or during forming the cellulose substrate into the formed cellulose product and/or to the formed cellulose product. The method further comprises polymerizing the at least one polymerizable fatty acid to form a hydrophobation and grease prooﬁng barrier of the formed cellulose product.

Another aspect of the invention relates to a cellulose article comprising a hydrophobation and grease proofing barrier on at least one surface of the cellulose article. The hydrophobation and grease prooﬁng barrier comprises at least one polymerized fatty acid or an oil or oil mixture comprising at least one polymerized fatty acid.

The present invention forms hydrophobation and grease prooﬁng barriers on cellulose products and articles that effectively protect the cellulose products or articles from liquids and grease when in contact with, for instance, beverages or food and food stuff or other goods and articles. The hydrophobation and grease prooﬁng barriers of the invention can be produced even onto formed cellulose products following forming the products from cellulose substrates.

BRIEF DESCRIPTION OF THE DRAWINGS The embodiments, together with further objects and advantages thereof, may best be understood by making reference to the following description taken together with the accompanying drawings, in which: Figs. 1A and 1B schematically illustrate hot pressing of a cellulose substrate into a formed cellulose product according to an embodiment; Fig. 2 schematically illustrates molding of a cellulose substrate into a formed cellulose product according to an embodiment; Fig. 3 schematically illustrates a cellulose substrate (top) and a corresponding formed cellulose product (bottom) according to an embodiment; Fig. 4 illustrates an example of a formed cellulose product according to an embodiment; and Fig. 5 is a ﬂow chart of a method for manufacturing a formed cellulose product according to an embodiment.

DETAILED DESCRIPTION The present invention generally relates to cellulose products and articles, and in particular to such cellulose products and articles comprising hydrophobation and grease proofing barriers and methods for manufacturing formed cellulose products and articles comprising hydrophobation and grease prooﬁng barriers.

Cellulose products have become more and more popular as environmentally friendly replacements of disposable plastic products for usage as containers or tools in connection with beverages and food. For instance, disposable cups, plates, bowls, lids, caps and cutlery have traditionally be manufactured in plastics, such as polystyrene and other plastic materials, but alternatives to plastics are needed from environmental and sustainability point of view and due to possible health hazards associated with plastic materials with chemicals leaching into the beverage or food. Cellulose products are also employed as environmentally more friendly replacements to packaging products made of or from foamed polymers, for instance expanded polystyrene (EPS).

Cellulose substrates can be formed by means of, for instance, cutting, pressing, folding, thermoforming and/or dry molding, into formed cellulose products for usage with, for instance, beverage and food, such as disposable cups, plates, bowls, lids, caps and cutlery. However, such cellulose products may readily absorb liquids and grease from the beverage or food unless surfaces of the cellulose products that come into contact with the beverage or food are treated to prevent or at least restrict absorption of liquids and grease.

A similar problem with absorbing liquid and grease is also present for cellulose-based packaging products employed to protect goods and articles during storage and/or transport. For instance, liquids and/or grease may leak from the goods and articles packaged in the cellulose based packaging products and be absorbed therein. ln addition, moisture or other liquids may come in contact with outer surfaces of the packaging products during use.

The present invention uses polymerizable fatty acids and/or oils or oil mixtures comprising such polymerizable fatty acids to form so called hydrophobation and grease prooﬁng barrier of cellulose products and articles. This type of hydrophobation and grease barrier agent, also referred to as hydrophobation and grease prooﬁng agent, has significant advantages over the traditional hydrophobation and grease barrier agents in the form of aqueous solutions or emulsions of, for instance, starches. The prior art aqueous hydrophobation and grease barrier agents need to be applied to the cellulose substrate prior to forming since the cellulose material will absorb water from the aqueous hydrophobation and grease barrier agent causing undesired swelling and deformation of the cellulose material. This swelling and deformation can be compensated for during the forming process, for instance, by pressing, thermoforming or molding the swelled and deformed cellulose substrate. However, such a swelling and deformation cannot be compensated for if it occurs in the formed cellulose product. Hence, the prior art aqueous hydrophobation and grease barrier agents need to be applied to the cellulose substrate prior to forming. The polymerizable fatty acids or oils as hydrophobation and grease barrier agents of the invention do not cause the same degree of swelling and deformation of the cellulose material as the aqueous solutions or emulsions and may therefore be applied to the formed cellulose product and/or to the cellulose substrate prior to or during the forming process.

An advantage of applying the hydrophobation and grease barrier agents of the invention to the cellulose product after forming is that all surfaces of the formed cellulose product that may be in contact with liquids, moisture, beverages or food may be treated to present hydrophobation and grease prooﬁng barriers. This includes also surfaces of the formed cellulose product that are exposed following cutting operations. This is in clear contrast to prior art treated cellulose products, which may have cut edges of the formed cellulose products that are not protected by any hydrophobation and grease proofing barriers since the hydrophobation and grease barrier agent had been applied to surfaces of the cellulose substrate prior to forming and cutting. These exposed edges are thereby not protected by any hydrophobation and grease proofing barrier and may, thus, absorb liquid and grease when in contact with goods, articles, beverages or food, or indeed moisture or liquid from the surroundings.

The present invention can achieve hydrophobation and grease prooﬁng barriers also for cut edges in the formed cellulose product even if the hydrophobation and grease barrier agent is applied prior to or during the forming process. The polymerizable fatty acids or oils of the invention may penetrate into the bulk of the cellulose substrate to proof or impregnate the whole cellulose substrate or at least a thick portion thereof with the polymerizable fatty acids or oils. Hence, also edges exposed when cutting the formed cellulose product will thereby present hydrophobation and grease prooﬁng barriers and restrict absorption of liquids and grease.

Hydrophobation and grease proofing barrier as used herein is thereby not only limited to such barriers present on the surface of the formed cellulose product. The hydrophobation and grease prooﬁng barrier may in fact extend into at least a portion of the thickness of the formed cellulose product or indeed extend through the whole thickness and bulk of the formed cellulose product.

Fig. 5 is a flow chart illustrating a method for manufacturing a formed cellulose product according to the invention. Reference is also made to Fig. 3 illustrating a cellulose substrate 10 (top) and a corresponding formed cellulose product 20 (bottom) and Fig. 4 illustrating an example of a formed cellulose product 20 according to an embodiment.

The method comprises forming, in step S1, a cellulose substrate 10 into a formed cellulose product 20. The method also comprises applying, in step S2, at least one polymerizable fatty acid or an oil or oil mixture comprising at least one polymerizable fatty acid to the cellulose substrate 10 prior to and/or during forming the cellulose substrate 10 in step S1 into the formed cellulose product 20 and/or to the formed cellulose product 20. The method further comprises polymerizing, in step S3, the at least one polymerizable fatty acid to form a hydrofobation and grease proofing barrier 25 of the formed cellulose product 20.

The present invention thereby applies at least one polymerizable fatty acid or an oil or oil mixture comprising at least one polymerizable fatty acid as hydrophobation and grease barrier agent by applying the least one polymerizable fatty acid or the oil or oil mixture to the cellulose substrate 10 and/or to the formed cellulose product 20 and then polymerize the at least one polymerizable fatty acid or the oil or oil mixture to obtain the hydrophobation and grease proofing barrier 25 of the formed cellulose product 20. Polymerization of the at least one polymerizable fatty acid causes formation of at least one polymerized fatty acid or an oil or oil mixture comprising at least one such polymerized fatty acid. The at least one polymerized fatty acid is solid on or on and in the cellulose substrate 10 and/or the formed cellulose product 20. This means that the at least one polymerized fatty acid forms a solid hydrophobation and grease prooﬁng barrier at least onto a surface, or a portion thereof, of the cellulose substrate 10 and/or the formed cellulose product 20. The at least one polymerizable fatty acid may also penetrate into the cellulose substrate 10 and/or the formed cellulose product 20 and when polymerized therein, the at least one polymerized fatty acid forms a hydrophobation and grease proofing barrier also within the bulk of the cellulose substrate 10 and/or the formed cellulose product 20.

The at least one polymerizable fatty acid or the oil or oil mixture is applied in step S2 to at least one surface, or at least a portion of at least one surface, of the cellulose substrate 10 prior to and/or during forming the cellulose substrate 10 into the formed cellulose product 20 and/or to at least one surface, or at least a portion of at least one surface, of the formed cellulose product 20, which is further described herein.

The formed cellulose product 20 as manufactured in accordance with Fig. 5 is suitable for being in contact with beverages and/or food or foodstuff. The hydrophobation and grease prooﬁng barrier 25 of the formed cellulose product 20 obtained in step S3 of Fig. 5 thereby protects the formed cellulose product 20 and prevents or at least restricts absorption of liquid and/or grease from the beverages and/or food or foodstuff. The formed cellulose product 20 as manufactured in accordance with Fig. 5 is also suitable for usage as a packaging product for protecting goods and particles against impact and shock. The formed cellulose product 20 could also be used to thermally protect temperature sensitive goods and articles, such as foodstuff, packaged and possibly enclosed in the packaging product. The hydrophobation and grease proofing barrier 25 of the formed cellulose product 20 obtained in step S3 of Fig. 5 then protects the formed cellulose product 20 and prevents or at least restricts absorption of liquid and/or grease from the protected goods and articles, and also from the surroundings, such as moisture or liquids falling onto the formed cellulose product 20 during usage.

As is schematically illustrated by the lines L1 to L3 in Fig. 5, the at least one polymerizable fatty acid or the oil or oil mixture could be applied to the cellulose substrate 10 prior to forming the cellulose substrate 10 into the formed cellulose product 20 as indicated by line L1. Alternatively, the at least one polymerizable fatty acid or the oil or oil mixture could be applied to the cellulose substrate 10 during forming the cellulose substrate 10 into the formed cellulose product 20 as indicated by line L2. ln yet an alternative, the at least one polymerizable fatty acid or the oil or oil mixture could be applied to the formed cellulose product 20 as indicated by line L3. lt is also possible to combine two or all of these alternatives. Hence, in an embodiment, the at least one polymerizable fatty acid or the oil or oil mixture is applied in step S2 to the cellulose substrate 10 prior to and during forming the cellulose substrate 10 into the formed cellulose product 20. ln another embodiment, the at least one polymerizable fatty acid or the oil or oil mixture is applied in step S2 to the cellulose substrate 10 prior to forming the cellulose substrate 10 into the formed cellulose product 20 and to the formed cellulose product 20. ln a further embodiment, the at least one polymerizable fatty acid or the oil or oil mixture is applied in step S2 to the cellulose substrate 10 during forming the cellulose substrate 10 into the formed cellulose product 20 and to the formed cellulose product 20. ln yet another embodiment, the at least one polymerizable fatty acid or the oil or oil mixture is applied in step S2 to the cellulose substrate 10 prior to and during forming the cellulose substrate 10 into the formed cellulose product 20 and in addition to the formed cellulose product 20. ln some applications it may be advantageous to apply the at least one polymerizable fatty acid or the oil or oil mixture in step S2 at least prior to forming the cellulose substrate 10 into a formed cellulose product 20 in step S1. ln these applications, the forming operation in step S1 may comprise heating the cellulose substrate 10, such as in thermoforming operations, which will be described further herein. ln such a case, the heating of the cellulose substrate 10 accelerates the polymerization of the at least one polymerizable fatty acid in step S3 so that the polymerization operation in step S3 may be performed simultaneously with or at least partly overlapping with the forming operation in step S1.

The heating applied in step S1 preferably heats the cellulose substrate 10 at a sufﬁcient temperature to accelerate the polymerization but not at too high temperature to degrade the cellulose substrate 10. As an illustrative, but non-limiting, example, the cellulose substrate 10 could be heated to a temperature up to but not exceeding 210°C, preferably up to but not exceeding 190°C.

Correspondingly, if the cellulose substrate 10 is at least partly wetted prior to the forming operation in step S1, it may be advantageous to apply the at least one polymerizable fatty acid or the oil or oil mixture in step S2 to the formed cellulose product 20. The reason being that the at least one polymerizable fatty acid or the oil or oil mixture may othen/vise, if applied at least prior to the forming operation in step S1, restrict the water or moisture in the cellulose substrate 10 from escaping therefrom during the forming operation in step S1. This would then mean that the formed cellulose product 20 would contain an undesired amount of moisture that cannot escape due to the presence of the hydrophobation and grease prooﬁng barrier 25. Hence, in such applications, it is advantageous to apply the at least one polymerizable fatty acid or the oil or oil mixture to the formed cellulose product 20 or to the cellulose substrate 10 during the forming operation once moisture in the cellulose substrate 10 has been allowed to escape from the bulk of the cellulose substrate 10. ln an embodiment, step S2 in Fig. 5 comprises spraying the at least one polymerizable fatty acid or the oil or oil mixture onto at least one surface 11-14 of the cellulose substrate 10 and/or at least one surface 21-24 of the formed cellulose product 20. The at least one polymerizable fatty acid or the oil or oil mixture will thereby form a surface coating on the at least one surface 11-14, 21-24 of the cellulose substrate 10 or the formed cellulose product 20 but preferably also penetrate into at least a portion of the thickness of the cellulose substrate 10 or the formed cellulose product 20 from the at least one surface 11-14, 21-24. ln another embodiment, step S2 in Fig. 5 comprises coating at least one surface 11-14 of the cellulose substrate 10 and/or at least one surface 21-24 of the formed cellulose product 20 with the at least one polymerizable fatty acid or the oil or oil mixture. Various coating techniques could be used to apply the at least one polymerizable fatty acid or the oil or oil mixture. lllustrative, but non-limiting, examples include curtain coating and roller coating. The at least one polymerizable fatty acid or the oil or oil mixture will thereby form a surface coating on the at least one surface 11-14, 21-24 of the cellulose substrate 10 or the formed cellulose product 20 but preferably also penetrate into at least a portion of the thickness of the cellulose substrate 10 or the formed cellulose product 20 from the at least one surface 11-14, 21-24. ln a further embodiment, step S2 in Fig. 5 comprises immersing at least a portion of the cellulose substrate 10 and/or at least a portion of the formed cellulose product 20 into the least one polymerizable fatty acid or the oil or oil mixture. Hence, in this embodiment, the cellulose substrate 10 and/or the formed cellulose product 20, or at least a portion thereof, is immersed in a bath of the at least one polymerizable fatty acid or the oil or oil mixture to soak the cellulose substrate 10 and/or the formed cellulose product 20, or at least a portion thereof, with the at least one polymerizable fatty acid or the oil or oil mixture. ln this embodiment, the complete cellulose substrate 10 and/or formed cellulose product 20 could be immersed in the at least one polymerizable fatty acid or the oil or oil mixture or merely a portion thereof is immersed in the at least one polymerizable fatty acid or the oil or oil mixture. The at least one polymerizable fatty acid or the oil or oil mixture will thereby form a surface coating on the at least one surface 11-14, 21-24 of the cellulose substrate 10 or the formed cellulose product 20 but preferably also penetrate into at least a portion of the thickness of the cellulose substrate 10 or the formed cellulose product 20 from the at least one surface 11-14, 21-24. lt is also possible to combine tvvo or more of the above described embodiments of applying the at least one polymerizable fatty acid or the oil or oil mixture, for instance, combining spraying and coating, combining spraying and immersing, combining coating and immersing and combining spraying, coating and immersing. As an example, one of the applying embodiments could be used to apply the at least one polymerizable fatty acid or the oil or oil mixture to the cellulose substrate 10, whereas another applying embodiment could be used for applying the at least one polymerizable fatty acid or the oil or oil mixture to the formed cellulose product 20. ln an embodiment, step S2 in Fig. 5 comprises applying the at least one polymerizable fatty acid or the oil or oil mixture to at least one surface 11-14 of the cellulose substrate 10 and/or to at least one surface 21-24 of the formed cellulose product 20 and into at least a portion of a thickness of the cellulose substrate 10 and/or of the formed cellulose product 20 extending from the at least one surface 11-14, 21-24. Hence, in this embodiment, the at least one polymerizable fatty acid or the oil or oil mixture is not only present at a surface 11-14, 21-24 of the cellulose substrate 10 and/or of the formed cellulose product 20 but also penetrates into at least a portion of the thickness of the cellulose substrate 10 and/or of the formed cellulose product 20 from the at least one surface 11-14, 21-24. Hence, the at least one polymerizable fatty acid or the oil or oil mixture is present in at least a portion of the bulk of the cellulose substrate 10 and/or of the formed cellulose product 20, where this at least a portion of the bulk faces the at least one surface 11-14, 21-24. ln a particular embodiment, the at least one polymerizable fatty acid or the oil or oil mixture penetrates into the complete thickness of the cellulose substrate 10 and/or of the formed cellulose product 20. ln such a particular embodiment, preferably all surfaces 11-14, 21-24 and the bulk of the cellulose substrate 10 and/or of the formed cellulose product 20 comprise the at least one polymerizable fatty acid or the oil or oil mixture. This particular embodiment can, for instance, be achieved by immersing the complete cellulose substrate 10 and/or the formed cellulose product 20 into the at least one polymerizable fatty acid or the oil or oil mixture.

The at least one polymerizable fatty acid or the oil or oil mixture is applied in a sufficient quantity in step S2 to the cellulose substrate 10 and/or to the formed cellulose product 20 to form a hydrofobation and grease proofing barrier 25 of the formed cellulose product 20 following step S3. This means that the at least one polymerizable fatty acid or the oil or oil mixture is applied onto at least one surface 11-14 of the cellulose substrate 10 and/or at least one surface 21-24 of the formed cellulose product 20 to form the hydrofobation and grease prooﬁng barrier 25 onto the at least one surface 21-24 of the formed cellulose product 20 and optionally also within the bulk, or a portion thereof, of the formed cellulose product 20. The hydrofobation and grease proofing barrier 25 thereby prevents or at least restricts moisture, liquid and/or grease to penetrate into the formed cellulose product 20 through this at least one surface 21-24.

The amount of polymerizable fatty acid or oil or oil mixture applied in step S2 depends, among others, on the size or volume of the formed cellulose product 20 to be protected by the hydrofobation and grease prooﬁng barrier 25, the type of polymerizable fatty acid or oil or oil mixture, the type of material of the cellulose substrate 10 and/or formed cellulose product 20, whether any processing has been applied to the polymerizable fatty acid or oil or oil mixture prior to application in step S2 and whether any forming operations have been applied to the cellulose substrate 10 and/or formed cellulose product 20 prior to application in step S2. ln a particular embodiment, step S2 comprises saturating the cellulose substrate 10 and/or the formed cellulose product 20 with the at least one polymerizable fatty acid or the oil or oil mixture. The at least one polymerizable fatty acid or the oil or oil mixture is then present throughout the whole cellulose substrate 10 and/or the formed cellulose product 20 including on its surfaces 11-14, 21-24 and within the interior of the cellulose substrate 10 and/or the formed cellulose product 20.

The at least one polymerizable fatty acid is polymerized in step S3 of Fig. 5. Polymerization of the at least one polymerizable fatty acid may, in an embodiment, take place in an oxygen containing atmosphere. The at least one polymerizable fatty acid can thereby be polymerized in ambient air without any particular treatment. However, such a polymerization generally takes quite a long time and would be most suited if the polymerization is allowed to proceed while the formed cellulose product 20 11 is stored, i.e., during its shelf life, or transport of the formed cellulose product 20. lt is, however, generally preferred to accelerate the polymerization of the at least one polymerizable fatty acid in step S3 by treating the cellulose substrate 10 and/or the formed cellulose product 20. lllustrative, but non- limiting examples, of such polymerization accelerating treatments include heat treatment, ultraviolet (UV) light treatment, oxygen treatment (partial pressure of oxygen above 0.21 bar) and using polymerization catalysts. These various polymerization accelerating treatments may also be combined. ln an embodiment, step S3 in Fig. 5 comprises exposing at least a portion of the cellulose substrate 10 and/or the formed cellulose product 20 to heat and/or UV light in the presence of oxygen to form the hydrophobation and grease prooﬁng barrier 25 of the formed cellulose product 20. ln such an embodiment, the heat and/or UV light treatment could be a separate treatment operation or may be part of the forming operation in step S1. The application of heat and/or UV light could be performed in ambient air or in an oxygen enriched (>21 %) atmosphere.

The heat treatment applied to the cellulose substrate 10 and/or the formed cellulose product 20 preferably involves heating the cellulose substrate 10 and/or the formed cellulose product 20 at a sufﬁcient temperature to accelerate the polymerization but not at too high temperature to degrade the cellulose substrate 10 and/or the formed cellulose product 20. As an illustrative, but non-limiting example, the cellulose substrate 10 could be heated to a temperature up to but not exceeding 210°C, preferably up to but not exceeding 190°C. ln another embodiment, step S2 in Fig. 5 comprises applying the at least one polymerizable fatty acid or the oil or oil mixture and a polymerization catalyst to the cellulose substrate 10 prior to and/or during forming the cellulose substrate 10 into the formed cellulose product 20 and/or to the formed cellulose product 20. ln this embodiment, step S3 comprises exposing at least a portion of the cellulose substrate 10 and/or the formed cellulose product 20 to oxygen to form the hydrophobation and grease proofing barrier 25 of the formed cellulose product 20. The exposure of the at least a portion of the cellulose substrate 10 and/or the formed cellulose product 20 to oxygen could be simply exposing the at least a portion of the cellulose substrate 10 and/or the formed cellulose product 20 to ambient air or, to accelerate the polymerization reaction, an oxygen enriched atmosphere. lllustrative, but non-limiting, examples of polymerization catalysts that could be used according to the invention include cobalt(ll) 2-ethylhexanoate and oil drying agents, also referred to as siccatives. 12 The polymerization of the at least one polymerizable fatty acid or the oil or oil mixture in step S3 does not necessarily have to be in the form of a so-called oxypolymerization but could instead be in the form of condensation polymerization or radical polymerization of the at least one polymerizable fatty acid or the oil or oil mixture.

The cellulose substrate 10 used as starting material in the method of Fig. 5 can be any cellulose substrate 10 that can be formed into formed cellulose products 20, and in particular into such formed cellulose products 20 to be in contact with beverages and/or food, such as disposable containers for beverages and/or food, disposable lids or caps, or disposable cutlery, and formed cellulose products 20 to be used as packaging products, such as inserts.

Examples of such cellulose substrates 10 include pulp sheets and air-laid substrates.

Pulp sheets, also referred to as cellulose pulp sheets, could be any sheet or thicker products, such as boards, comprising cellulose pulp. lllustrative, but non-limiting, examples of such pulp sheets include paper, paper boards, fiber based sheets, ﬂuff pulp sheets, dried pulp sheets, and pulp sheets obtained by wet molding of cellulose pulp.

An air-laid substrate or material, such as in the form of an air-laid blank, sometimes also referred to as, dry-laid blank, air-laid mat, dry-laid mat, air-laid web or dry-laid web, is formed by a process known as air-laying, in which cellulose and/or lignocellulose fibers, and optionally a binder, such as a polymer binder, are mixed with air to form a porous ﬁber mixture deposited onto a support and consolidated or bonded by heating or thermoforming. This air-laid substrate is characterized by being porous, having the character of an open cell foam and being produced in a so-called dry forming method, i.e., generally without addition of water. The air-laying process was initially described in U.S. patent no. 3,575,749. The air-laid substrate may be in the form as produced in the air-laying process.

An example of an air-laid substrate or material that can be used according to the invention is such substrates made from a ﬂuff pulp material in an air-laying process.

The pulp sheet or air-laid substrate may be in the form of a single-layer cellulose substrate 10 or may be in the form of a multi-layer cellulose substrate 10 comprising multiple, i.e., at least two, layers of 13 cellulose materials, such as multiple pulp sheets stacked, bonded or pressed together to form a thicker pulp board, or multiple layers of air-laid substrates. ln an embodiment, the cellulose substrate 10 comprises cellulose and/or lignocellulose ﬁbers. Hence, in an embodiment, the cellulose substrate 10 comprises cellulose, such as in the form of cellulose and/or lignocellulose, i.e., a mixture of cellulose and lignin. The fibers may contain lignin, such as in the form of lignocellulose. The fibers may additionally contain hemicellulose. ln a particular embodiment, the cellulose and/or lignocellulose fibers are cellulose and/or lignocellulose pulp ﬁbers produced by chemical, mechanical and/or chemi-mechanical pulping of softwood and/or hardwood. For instance, the cellulose and/or lignocellulose pulp fibers are in a form selected from the group consisting of sulfate pulp, sulfite pulp, dissolving pulp, thermomechanical pulp (TMP), high temperature thermomechanical pulp (HTMP), mechanical ﬁber intended for medium density ﬁberboard (MDF-fiber), chemi- thermomechanical pulp (CTMP), high temperature chemi-thermomechanical pulp (HTCTMP), and a combination thereof.

The cellulose and/or lignocellulose fibers can also be produced by other pulping methods and/or from other cellulosic or lignocellulosic raw materials, such as flax, jute, hemp, kenaf, bagasse, cotton, bamboo, straw or rice husk. lt is also possible to use cellulose and/or lignocellulose fibers that are a mixture of ﬁbers from different raw materials, such as a mixture of wood and any of the materials mentioned above.

The cellulose substrate 10 may also include a binder, in particular for cellulose substrates 10 in the form of air-laid blanks 10. Such a binder may then be included to bind the cellulose substrate together and preserve its form and structure during use, handling and storage. ln an embodiment, the binder may also assist in building up the foam-like structure of the cellulose substrate 10. The binder is, in such an embodiment, intermingled with the cellulose and/or lignocellulose fibers during an air-lying process forming a fiber mixture. The binder may be added in the form of a powder, but is more often added in the form of ﬁbers that are intermingled with the cellulose and/or lignocellulose fibers in the air- laying process. Alternatively, or in addition, the binder may be added as solution, emulsion or dispersion into and onto the cellulose substrate 10.

The binder is preferably a polymer binder and could be a natural or synthetic polymer binder, or a mixture of natural polymer binders, a mixture of synthetic polymer binders, or a mixture of natural and synthetic polymer binders, but is preferably a thermoplastic polymer binder. 14 ln an embodiment, the polymer binder is made from i) a material selected from the group consisting of polyethylene (PE), ethylene acrylic acid copolymer (EAA), ethylene-vinyl acetate (EVA), polypropylene (PP), poiystyrene (PS), such as styrene-butadiene rubber (SBR) or styrene acryiate copoiymer, polybutylene adipate terephthaiate (PBAT), polybutylene succinate (PBS), polylactic acid (PLA), polyethylene terephthaiate (PET), polycaprolactone (PCL), polyvinyl alcohol (PVA), polyethylene glycol (PEG), poly(2-ethyl-2-oxazoline) (PEOX), polyvinyl ether (PVE), polyvinylpyrrolidone (PVP), polyacrylic acid (PAA), polymethacrylic acid (PMAA), polyvinyl acetate (PVAc), polyurethane (PU) and copolymers thereof and/or mixtures thereof, and ii) optionally one or more additives. ln an embodiment, the polymer binder is a thermoplastic polymer binder and preferably selected from the group consisting of a thermoplastic polymer powder, thermoplastic polymer ﬁbers and a combination thereof.

The forming step S1 can be performed according to various embodiments comprising one or multiple different forming operations. ln an embodiment, step S1 of Fig. 5 comprises at least one of cutting the cellulose substrate 10, dry molding the cellulose substrate 10, thermoforming the cellulose substrate 10, folding the cellulose substrate 10 and pressing the cellulose substrate 10.

The cellulose substrate 10 may be cut in step S1. This cutting operation could include any process of separating the cellulose substrate 10 or the formed cellulose product 20 from any remaining cellulose material and/or from debris cellulose material. The cutting operation may include various cutting operations including, but not limited to, sawing, punching, or cutting the cellulose substrate 10 or indeed the formed cellulose product 20.

Dry molding the cellulose substrate 10 involves molding the cellulose substrate 10 in a pair of tools or molds, typically between a male tool or mold and a female tool or mold. Fig. 2 schematically illustrates such a process, in which the cellulose substrate 10 is pressed between a male tool 30 and a female tool 50. Generally, the cellulose substrate 10 is pressed into the female tool 50 by the male tool 30. The male tool 30 may optionally comprise one or more protruding structures that are conﬁgured to be depressed into the cellulose substrate 10. ln such a case, the three dimensional (3D) shape of the resulting formed product 20, see Fig. 3, is defined by the form of the female tool 50 and the male tool 30, including any protruding structures of the male tool 30. Dry molding implies that the cellulose substrate 10 is in a dry form or substantially dry form. This is in clear contrast to wet molding, in which a wet pulp is drawn by vacuum onto a wire mesh mold. However, the cellulose product obtained from such a wet molding operation could be used, when dried, as a cellulose substrate 10 of the invention.

Thermoforming of the cellulose substrate 10 includes any forming processing involving heating the cellulose substrate 10, such as by using heating tools employed in the forming process. Dry molding and pressing could be thermoforming operations if any of the tools used in the dry molding or pressing operation is heated. Figs. 1A and 1B illustrate an example of a thermoforming operation by compacting or pressing a heated male tool 30 into a cellulose substrate 10 positioned on a base platen 40. The male tool 30 may then comprise heating elements 34 that are preferably controllable heating elements 34 to heat the male tool 30 to a desired temperature for hot pressing of the cellulose substrate 10. Fig. 1B illustrates the heated male tool 30 pressed into the cellulose substrate 10. ln this illustrative example, the male tool 30 comprises protruding structures 32 that will be pressed into the cellulose substrate 10 to impart a 3D shape into the surface 11 of the cellulose substrate 10 facing the male tool 30.

Pressing of the cellulose substrate 10 may also be performed without any heating of the cellulose substrate, such as performing pressing at ambient temperature.

The forming step S1 may also comprise folding the cellulose substrate 10. This folding may be preceded by forming a crease or folding line in the cellulose substrate 10, such as by pressing a die into the cellulose substrate 10 to form a folding line, along which the cellulose substrate 10 may be folded to obtain a formed cellulose product 20.

A particular example of a forming operation is to arrange a cellulose substrate 10, such as a cellulose substrate or blank 10, preferably comprising less than 45 weight percent water in a mold and heating the cellulose substrate 10, preferably to a temperature selected within an interval of from 100°C to 200°C, such as from 140°C to 200°C. The forming operation also comprises pressing the cellulose substrate 10 by means of the mold with a pressure acting on the cellulose substrate 100 across a forming surface of the mold. The pressure is preferably selected within an interval of from 1 MPa to 100 MPa, preferably at least 4 MPa.

As mentioned in the foregoing, the forming step S1 in Fig. 5 may comprise a combination of the above exempliﬁed forming operations. For instance, dry molding, thermoforming or pressing is usually 16 combined with cutting the dry molded, thermoformed or pressed cellulose product to obtain a separate formed cellulose product 20. Furthermore, a thermoformed cellulose product may also be folded to obtain a ﬁnal formed cellulose product 20 having a desired 3D shape. ln an embodiment, step S2 comprises applying a single polymerizable fatty acid to the cellulose substrate 10 and/or to the formed cellulose product 20. ln another embodiment, a mixture of multiple different polymerizable fatty acids could be applied to the cellulose substrate 10 and/or to the formed cellulose product 20. lllustrative, but non-limiting, examples of such polymerizable fatty acids that can be used in step S2 include unsaturated fatty acids including monounsaturated fatty acids, such as oleic acid, elaidic acid and palmitoleic acid, and/or polyunsaturated fatty acids, such as linoleic acid and linolenic acid, including mixtures thereof. ln a preferred embodiment, the polymerizable fatty acids are polyunsaturated fatty acids, a mixture of different polyunsaturated fatty acids or a mixture of at least one polyunsaturated fatty acid and at least one monounsaturated fatty acid. ln another embodiment, step S2 comprises applying the oil to the cellulose substrate 10 prior to and/or during forming the cellulose substrate 10 into the formed cellulose product 20 and/or to the formed cellulose product 20. Hence, in this embodiment, an oil comprising at least one polymerizable fatty acid, including a mixture of different polymerizable fatty acids, is applied to the cellulose substrate 10 and/or to the formed cellulose product 20. ln an embodiment, the oil is a vegetable oil. ln a particular embodiment, the vegetable oil is selected from the group consisting of flaxseed oil, avocado oil, sesame oil, safﬂower oil, sunflower oil, grapeseed oil, rapeseed oil, linseed oil and rosehip seed oil. ln a preferred embodiment, the vegetable oil is selected from the group consisting of rapeseed oil, sunflower oil and linseed oil, preferably selected from the group consisting of sunﬂower oil and linseed oil. A particular illustrative example of a vegetable oil that could be used according to the invention is linseed oil. Another particular example of a vegetable oil that could be used according to the invention is sunﬂower oil.

The oil, such as vegetable oil, could be a processed oil. For instance, the oil could be a fractionated oil. ln such a case, the processing, such as fractionation, of the oil could be done to remove fractions that may othen/vise become rancid. ln such a case, a fraction of the oil is applied in step S2. This fraction preferably comprises polymerizable fatty acids whereas constituents of the oil that provide an odor or taste are preferably removed during the fractionation. 17 ln an embodiment, a mixture of oils comprising at least one polymerizable fatty acid is used. ln such a case, the multiple oils can be selected among the above mentioned examples.

The result of the polymerization in step S3 is fatty acid based polymers, including fatty acid dimers, fatty acid trimers and/or longer fatty acid based polymers. lf multiple different polymerizable fatty acids are applied in step S2, such as in the form of a mixture of polymerizable fatty acids or an oil, the resulting fatty acid based polymers may be in the form of co-polymers of different fatty acid monomers. The at least one polymerizable fatty acid or the oil or oil mixture becomes hardened during the polymerization and forms a solid hydrophobation and grease prooﬁng barrier 25 either only on the surface of the formed cellulose product 20 or on the surface and within at least a portion of the thickness of the formed cellulose product 20.

Another aspect of the invention relates to a cellulose article 10, 20 comprising a hydrophobation and grease proofing barrier 25 on at least one surface 11-14, 21-24 of the cellulose article 10, 20. The hydrophobation and grease proofing barrier 25 comprises at least one polymerized fatty acid or an oil or oil mixture comprising at least one polymerized fatty acid.

The cellulose article 10, 20 could the in the form of the above described formed cellulose product 20 or the cellulose substrate 10.

Hence, an embodiment relates to a formed cellulose product 20 comprising a hydrophobation and grease prooﬁng barrier 25 on at least one surface 21-24 of the formed cellulose product 20. The hydrophobation and grease prooﬁng barrier 25 comprises at least one polymerized fatty acid or an oil or oil mixture comprising at least one polymerized fatty acid.

The formed cellulose product 20 is preferably in the form of a formed cellulose product 20 intended to be in contact with beverages and/or food and food stuff. The formed cellulose product 20 is preferably a disposable formed cellulose product 20, such as disposable cups, plates, bowls, lids, caps and cutlery. ln another embodiment, the formed cellulose product 20 is intended to be used as a packaging product designed to protect articles and goods packed in the packaging product from, among others, impacts and shock during transport and storage. The packaging product could also be used to enclose temperature sensitive or tempered articles, such as food or beverages, which should be kept within deﬁned temperature ranges. 18 Another embodiment relates to a cellulose substrate 10 comprising a hydrophobation and grease proofing barrier on at least one surface 11-14 of the cellulose substrate 10. The hydrophobation and grease proofing barrier comprises at least one polymerized fatty acid or an oil or oil mixture comprising at least one polymerized fatty acid.

The cellulose substrate 10 is preferably in the form of a pulp sheet or an air-laid substrate. ln an embodiment, the polymerized fatty acid or the oil or oil mixture is present from the at least one surface 11-14, 21-24 of the formed cellulose article 10, 20 into at least a portion of a thickness of the cellulose article 10, 20 extending from the at least one surface 11-14, 21-24. ln an embodiment, the cellulose article 10, 20 comprises the hydrophobation and grease prooﬁng barrier 25 on all surfaces 11-14, 21-24 of the cellulose article 10, 20. ln an embodiment, the cellulose article 10, 20 is saturated with the polymerized fatty acid or the oil or oil mixture. ln an embodiment, the cellulose article 10, 20 comprises cellulose and/or lignocellulose fibers. ln a particular embodiment, the cellulose article 10, 20 comprises cellulose and/or lignocellulose pulp ﬁbers produced by chemical, mechanical and/or chemi-mechanical pulping of softvvood and/or hardwood. ln an embodiment, the cellulose and/or lignocellulose fibers are cellulose and/or lignocellulose pulp ﬁbers in a form selected from the group consisting of sulfate pulp, sulﬁte pulp, dissolving pulp, TMP, HTMP, MDF-ﬁber, CTMP, HTCTMP, and a combination thereof. ln an embodiment, the hydrophobation and grease prooﬁng barrier 25 comprises the oil or oil mixture. ln this embodiment, the oil is a vegetable oil, preferably selected from the group consisting of ﬂaxseed oil, avocado oil, sesame oil, safflower oil, sunflower oil, grapeseed oil, rapeseed oil, linseed oil and rosehip seed oil. Correspondingly, the oil mixture is a mixture of vegetable oils, preferably selected from the above mentioned group.

The cellulose article 10, 20 may optionally comprise one or more additives traditionally employed when manufacturing cellulose substrates 10 and formed cellulose products 20. These additives should then 19 be compatible with the at least one polymerizable fatty acid or the oil or oil mixture and should preferably not signiﬁcantly interfere with polymerization of the at least one polymerizable fatty acid. ln an embodiment, the cellulose article 10, 20 is a formed cellulose product 20 formed by cutting, dry molding, thermoforming, folding and/or pressing a cellulose substrate 10. ln another embodiment, the cellulose article 10, 20 is a cellulose substrate 10 conﬁgured to be formed into a formed cellulose product 20 by cutting, dry molding, thermoforming, folding and/or pressing the cellulose substrate 10. ln an embodiment, the cellulose substrate 10 is selected from the group consisting of a pulp sheet, and an air-laid substrate.

EXAMPLE Spoons were manufactured by pressing a wetted ﬂuff pulp material in a form shaped mold. The spoons were then treated with a) linseed oil (Selder & Company) or b) sunﬂower oil (food grade) by immersing the forks into the linseed oil or the sunﬂower oil for 5 minutes.

The oil treated spoons were heated treated in a laboratory oven to polymerize polymerizable fatty acids in the linseed oil or the sunflower oil according to the following heating schedules: i) 150°C for 2, 6, 12 or 24 hours; ii) 170°C for 2, 6, 12 or 24 hours; or iii) 200°C for 2, 6, 12 or 24 hours.

All oil treated spoons were water resistant and did not absorb water following the heat treatments. The degree of polymerization of the oil was dependent on the temperature and time with a higher degree of polymerization at higher temperatures (given the same heating time period) and at longer heating time periods (given the same temperature).

The cellulose and/or lignocellulose ﬁbers in the spoons started to darken at the longest heat treatments (12 and 24 hours) for all tested temperatures, and also at 200°C for 6 hours. Fig. 4 illustrates an example of the oil and heated treated spoons.

The embodiments described above are to be understood as a few illustrative examples of the present invention. lt will be understood by those skilled in the art that various modifications, combinations and changes may be made to the embodiments without departing from the scope of the present invention. ln particular, different part solutions in the different embodiments can be combined in other configurations, where technically possible.

Claims

1. A method for manufacturing a formed cellulose product (20), the method comprises: forming (S1) a cellulose substrate (10) into a formed cellulose product (20); applying (S2) at least one polymerizable fatty acid or an oil or oil mixture comprising at least one polymerizable fatty acid to the cellulose substrate (10) prior to and/or during forming the cellulose substrate (10) into the formed cellulose product (20) and/or to the formed cellulose product (20); and polymerizing (S3) the at least one polymerizable fatty acid to form a hydrophobation and grease proofing barrier (25) of the formed cellulose product (20).

2. The method according to claim 1, wherein applying (S2) the at least one polymerizable fatty acid or the oil or oil mixture comprises spraying the at least one polymerizable fatty acid or the oil or oil mixture onto at least one surface (11-14, 21-24) of the cellulose substrate (10) and/or the formed cellulose product (20).

3. The method according to claim 1 or 2, wherein applying (S2) the at least one polymerizable fatty acid or the oil or oil mixture comprises coating, preferably curtain coating or roller coating, at least one surface (11-14, 21-24) of the cellulose substrate (10) and/or the formed cellulose product (20) with the at least one polymerizable fatty acid or the oil or oil mixture.

4. The method according to any one of claims 1 to 3, wherein applying (S2) the at least one polymerizable fatty acid or the oil or oil mixture comprises immersing at least a portion of the cellulose substrate (10) and/or at least a portion of the formed cellulose product (20) into the at least one polymerizable fatty acid or the oil or oil mixture.

5. The method according to any one of claims 1 to 4, wherein applying (S2) the at least one polymerizable fatty acid or the oil or oil mixture comprises applying the at least one polymerizable fatty acid or the oil or oil mixture to at least one surface (11-14, 21-24) of the cellulose substrate (10) and/or the formed cellulose product (20) and into at least a portion of a thickness of the cellulose substrate (10) and/or the formed cellulose product (20) extending from the at least one surface (11-14, 21-24).

6. The method according to claim 5, wherein applying (S2) the at least one polymerizable fatty acid or the oil or oil mixture comprises saturating the cellulose substrate (10) and/or the formed cellulose product (20) with the at least one polymerizable fatty acid or the oil or oil mixture.

7. The method according to any one of claims 1 to 6, wherein polymerizing (S3) the at least one polymerizable fatty acid comprises exposing at least a portion of the cellulose substrate (10) and/or the formed cellulose product (20) to heat and/or ultraviolet light in the presence of oxygen to form the hydrophobation and grease proofing barrier (25) of the formed cellulose product (20).

8. The method according to any one of claims 1 to 7, wherein applying (S2) the at least one polymerizable fatty acid or the oil or oil mixture comprises applying the at least one polymerizable fatty acid or the oil or oil mixture and a polymerization catalyst to the cellulose substrate (10) prior to and/or during forming the cellulose substrate (10) into the formed cellulose product (20) and/or to the formed cellulose product (20); and polymerizing (S3) the at least one polymerizable fatty acid comprises exposing at least a portion of the cellulose substrate (10) and/or the formed cellulose product (20) to oxygen to form the hydrophobation and grease proofing barrier (25) of the formed cellulose product (20).

9. The method according to any one of claims 1 to 8, wherein the cellulose substrate (10) is selected from the group consisting of a pulp sheet and an air-laid substrate.

10. The method according to any one of claims 1 to 9, wherein the cellulose substrate (10) comprises cellulose and/or lignocellulose ﬁbers, preferably cellulose and/or lignocellulose pulp ﬁbers produced by chemical, mechanical and/or chemi-mechanical pulping of softvvood and/or hardwood.

11. The method according to claim 10, wherein the cellulose and/or lignocellulose fibers are cellulose and/or lignocellulose pulp ﬁbers in a form selected from the group consisting of sulfate pulp, sulﬁte pulp, dissolving pulp, thermomechanical pulp (TMP), high temperature thermomechanical pulp (HTMP), mechanical ﬁber intended for medium density ﬁberboard (MDF-fiber), chemi-thermomechanical pulp (CTMP), high temperature chemi-thermomechanical pulp (HTCTMP), and a combination thereof.

12. The method according to any one of claims 1 to 11, wherein forming (S1) the cellulose substrate (10) comprises at least one of: cutting the cellulose substrate (10); dry molding the cellulose substrate (10); thermoforming the cellulose substrate (10); folding the cellulose substrate (10); and pressing the cellulose substrate (10).

13. The method according to any one of claims 1 to 12, wherein applying (S2) the at least one polymerizable fatty acid or the oil or oil mixture comprises applying the oil or oil mixture to the cellulose substrate (10) prior to and/or during forming the cellulose substrate (10) into the formed cellulose product (20) and/or to the formed cellulose product (20); and the oil is a vegetable oil or the oil mixture is a mixture of vegetable oils, preferably selected from the group consisting of ﬂaxseed oil, avocado oil, sesame oil, safflower oil, sunﬂower oil, rapeseed oil, grapeseed oil, linseed oil and rosehip seed oil.

14. A cellulose article (10, 20) comprising a hydrophobation and grease prooﬁng barrier (25) on at least one surface (11-14, 21-24) of the cellulose article (10, 20), wherein the hydrophobation and grease prooﬁng barrier (25) comprises at least one polymerized fatty acid or an oil or oil mixture comprising at least one polymerized fatty acid.

15. The cellulose article according to claim 14, wherein the polymerized fatty acid or the oil or oil mixture is present from the at least one surface (11-14, 21-24) of the cellulose article (10, 20) into at least a portion of a thickness of the cellulose article (10, 20) extending from the at least one surface (11-14, 21-24).

16. The cellulose article according to claim 14 or 15, wherein the cellulose article (10, 20) comprises the hydrophobation and grease proofing barrier (25) on all surfaces (11-14, 21-24) of the cellulose article (10, 20).

17. The cellulose article according to any one of the claims 14 to 16, wherein the cellulose article (10, 20) is saturated with the polymerized fatty acid or the oil or oil mixture.

18. The cellulose article according to any one of claims 14 to 17, wherein the cellulose article (10, 20) comprises cellulose and/or lignocellulose ﬁbers, preferably cellulose and/or lignocellulose pulp ﬁbers produced by chemical, mechanical and/or chemi-mechanical pulping of softvvood and/or hardwood.

19. The cellulose article according to claim 18, wherein the cellulose and/or lignocellulose fibers are cellulose and/or lignocellulose pulp ﬁbers in a form selected from the group consisting of sulfate pulp, sulfite pulp, dissolving pulp, thermomechanical pulp (TMP), high temperature thermomechanical pulp(HTMP), mechanical fiber intended for medium density fiberboard (MDF-ﬁber), chemi- thermomechanical pulp (CTMP), high temperature chemi-thermomechanicai pulp (HTCTMP), and a combination thereof.

20. The cellulose article according to any one of claims 14 to 19, wherein the hydrophobation and grease prooﬁng barrier (25) comprises the oil or oil mixture; and the oil is a vegetable oil or the oil mixture is a mixture of vegetable oils, preferably selected from the group consisting of flaxseed oil, avocado oil, sesame oil, safﬂower oil, sunﬂower oil, grapeseed oil, rapeseed oil, linseed oil and rosehip seed oil.

21. The cellulose article according to any one of claims 14 to 20, wherein the cellulose article (10, 20) is a formed cellulose product (20) formed by cutting, dry molding, thermoforming, folding and/or pressing a cellulose substrate (10).

22. The cellulose article according to any one of claims 14 to 20, wherein the cellulose article (10, 20) is a cellulose substrate (10) configured to be formed into a formed cellulose product (20) by cutting, dry molding, thermoforming, folding and/or pressing the cellulose substrate (10).

23. The cellulose article according to claim 21 or 22, wherein the cellulose substrate (10) is selected from the group consisting of a pulp sheet andan air-laid substrate.