A method for improving grease and oil resistance of a fiber based article

Abstract

There is provided a method for improving grease and oil resistance of a moulded fiber based article comprising introducing to a fiber stock a composition comprising at least one anionic polymer and cationic polymer and moulding the fiber stock. There is also provided a moulded fiber based article and a use of the composition for improving grease and oil resistance of a moulded fiber based article. There is also provided a method for preparation of a moulded fiber based article.

Claims

1. A method for improving grease and oil resistance of a moulded fiber based article, the method comprising obtaining a fiber stock comprising cellulosic fibers, introducing to the fiber stock a composition comprising at least one anionic polymer having molecular weight at least 100 kDa, and cationic polymer, wherein the anionic polymer and the cationic polymer provide the composition with a charge density in the range of 0.1-1.5 meq/g, when measured at pH 2.8, and 0.1-3 meq/g, preferably 0.3-2.5 meq/g, more preferably 0.5-2.0 meq/g, when measured as an aqueous solution at pH 7.0, optionally introducing polyamidoamine-epichlorohydrin, glyoxalated polyacrylamide, starch or a mixture thereof to the fiber stock, and moulding the fiber stock.

2. The method according to claim 1, wherein polyamidoamine-epichlorohydrin, glyoxalated polyacrylamide, starch or a mixture thereof is introduced to the fiber stock.

3. The method according to claim 1, wherein pigment material is introduced to the fiber stock.

4. The method according to claim 1, wherein the fiber stock is moulded to a sheet.

5. The method according to claim 4, wherein the sheet is formed or moulded to a three-dimensional, 3D, article.

6. The method according to claim 1, wherein the fiber stock is moulded to a three-dimensional, 3D, article.

7. The method according to claim 1, wherein the fiber stock is wet moulded and the wet moulded fiber stock is moulded to a three-dimensional, 3D, article.

8. The method according to claim 1, wherein the moulding comprises wet forming, wet moulding, vacuum forming, vacuum moulding, extrusion forming, extrusion moulding, thermoforming, dry moulding, hot pressing, hot press drying, hot moulding, heat pressing, heat moulding, thermomoulding or a combination thereof.

9. The method according to claim 1, wherein polyamidoamine-epichlorohydrin, glyoxalated polyacrylamide, starch or a mixture thereof and the composition are introduced sequentially to the fiber stock.

10. The method according to claim 1, wherein the polyamidoamine-epichlorohydrin, glyoxalated polyacrylamide, starch or a mixture thereof is introduced to the fiber stock before introducing the composition to the fiber stock.

11. The method according to claim 1, wherein the composition is introduced to the fiber stock followed by introducing the polyamidoamine-epichlorohydrin, glyoxalated polyacrylamide, starch or a mixture thereof to the fiber stock.

12. The method according to claim 1, wherein the at least one anionic polymer and the cationic polymer are introduced sequentially to the fiber stock.

13. The method according to claim 1, wherein the at least one cationic polymer is introduced to the fiber stock before introducing the anionic polymer.

14. The method according to claim 1, wherein the at least one anionic polymer is introduced to the fiber stock followed by introducing the at least one cationic polymer.

15. The method according to claim 1, wherein the at least one anionic polymer, the cationic polymer and the polyamidoamine-epichlorohydrin, glyoxalated polyacrylamide, starch or a mixture thereof are introduced sequentially to the fiber stock.

16. The method according to claim 1, wherein the at least one anionic polymer and the cationic polymer are introduced sequentially to the fiber stock followed by introducing the polyamidoamine-epichlorohydrin, glyoxalated polyacrylamide, starch or a mixture thereof to the fiber stock.

17. The method according to claim 1, wherein the polyamidoamine-epichlorohydrin, glyoxalated polyacrylamide, starch or a mixture thereof is introduced to the fiber stock followed by introducing the at least one anionic polymer and the cationic polymer sequentially to the fiber stock.

18. The method according to claim 1, wherein the at least one anionic polymer is introduced to the fiber stock followed by introducing the polyamidoamine-epichlorohydrin, glyoxalated polyacrylamide, starch or a mixture thereof to the fiber stock followed by introducing the cationic polymer to the fiber stock.

19. The method according to claim 1, wherein the cationic polymer is introduced to the fiber stock followed by introducing the polyamidoamine-epichlorohydrin, glyoxalated polyacrylamide, starch or a mixture thereof to the fiber stock followed by introducing the at least one anionic polymer to the fiber stock.

20. The method according to claim 1, wherein the composition is introduced in an amount of 5-50 kg/t, preferably 10-40 kg/t, more preferably 20-30 kg/t, based on dry weight of the fiber stock.

21. The method according to claim 1, wherein the polyamidoamine-epichlorohydrin, glyoxalated polyacrylamide, starch or a mixture thereof is introduced in an amount of 1-8 kg/t, preferably 2-6 kg/t, more preferably 2-4 kg/t based on the dry weight of the fiber stock.

22. The method according to claim 1, wherein before introducing the composition and the polyamidoamine-epichlorohydrin, glyoxalated polyacrylamide, starch or a mixture thereof to the fiber stock pH of the fiber stock is adjusted to pH value 5-9, preferably 7-8.

23. The method according to claim 1, wherein conductivity of the fiber stock is adjusted to 0.05 mS/cm-6 mS/cm, preferably 0.1 mS/cm-1 mS/cm before introducing the composition and the polyamidoamine-epichlorohydrin, glyoxalated polyacrylamide, starch or a mixture thereof to the fiber stock.

24. The method according to claim 1, wherein sizing chemical, fixative, wet strength agent, drainage aid or a mixture thereof is introduced to the fiber stock after or before introducing the composition and polyamidoamine-epichlorohydrin, glyoxalated polyacrylamide, starch or a mixture thereof to the fiber stock.

25. The method according to claim 1, wherein a polymer having both anionic and cationic groups, preferably amphoteric polymer and/or an interpenetrating polymer network material providing the charge densities is/are introduced to the fiber stock, preferably instead of the composition.

26. A moulded fiber based article, wherein the moulded fiber based article comprises a composition comprising at least one anionic polymer having molecular weight at least 100 kDa, and cationic polymer wherein the anionic polymer and the cationic polymer provide the composition with a charge density in the range of 0.1-1.5 meq/g, when measured at pH 2.8, and 0.1-3 meq/g, preferably 0.3-2.5 meq/g, more preferably 0.5-2.0 meq/g, when measured as an aqueous solution at pH 7.0, optionally polyamidoamine-epichlorohydrin, glyoxalated polyacrylamide, starch or a mixture thereof, and optionally pigment material, or wherein the moulded fiber based article is produced with the method according to claim 1.

27. The moulded fiber based article according to claim 26, wherein the moulded fiber based article comprises food packages, food service items, drink packages, goods packages, preferably ovenable trays, microwavable trays, clamshell boxes, other food boxes, soup cups, fresh meat and poultry trays, plates or cup lids.

28. (canceled)

Description

BRIEF DESCRIPTION OF THE FIGURES

[0043] FIG. 1 shows olive oil resistance at 40 C. for 500 and 400 g/m.sup.2 hot press dried 2D molded fiber article with different fiber stock chemistries.

[0044] FIG. 2 shows dry tensile properties of 500 g/m.sup.2 hot press dried 2D molded fiber article with different fiber stock chemistries.

[0045] FIG. 3 shows high moisture tensile properties of 500 g/m.sup.2 hot press dried 2D molded fiber article with different fiber stock chemistries.

[0046] FIG. 4 shows olive oil resistance at 40 C. for 400 g/m.sup.2 hot press dried 2D molded fiber article with different fiber stock chemistries.

[0047] FIG. 5 shows dry tensile properties of 400 g/m.sup.2 hot press dried 2D molded fiber article with different fiber stock chemistries.

[0048] FIG. 6 shows vacuum formed fiber based two-dimensional articles/sheets.

[0049] FIG. 7 shows molded fiber based three-dimensional article.

DETAILED DESCRIPTION

[0050] In a first aspect the present invention provides a method for improving grease and oil resistance of a moulded fiber based article comprising [0051] obtaining a fibre stock comprising cellulosic fibers, [0052] introducing to the fiber stock a composition comprising [0053] at least one anionic polymer having molecular weight at least 100 kDa, and [0054] cationic polymer, [0055] wherein the anionic polymer having molecular weight at least 100 kDa and the cationic polymer provide the composition with a charge density in the range of [0056] 0.1-1.5 meq/g, when measured at pH 2.8, and [0057] 0.1-3 meq/g, preferably 0.3-2.5 meq/g, more preferably [0058] 0.5-2.0 meq/g, when measured as an aqueous solution at pH 7.0, [0059] optionally introducing polyamidoamine-epichlorohydrin, glyoxalated polyacrylamide, starch or a mixture thereof to the fiber stock, and [0060] moulding the fiber stock.

[0061] The anionic polymer and the cationic polymer of the composition provide the charge densities to the composition.

[0062] In one embodiment polyamidoamine-epichlorohydrin (PAAE), glyoxalated polyacrylamide, starch or a mixture thereof is introduced to the fiber stock, preferably polyamidoamine-epichlorohydrin is introduced to the fiber stock.

[0063] In one embodiment pigment material is introduced to the fiber stock. In one embodiment the pigment material is introduced to the fiber stock before addition of the composition. In one embodiment the pigment material is introduced to the fiber stock after addition of the composition. In one embodiment the pigment material is introduced to the fiber stock at the same time as the composition. In one embodiment the pigment material and the composition are introduced as a mixture to the fiber stock.

[0064] In one embodiment the pigment material comprises talc, kaolin clay calcium carbonate or a mixture thereof.

[0065] The moulding, i.e. moulding step or moulding process, can be any suitable method known in the art.

[0066] In one embodiment the moulding comprises wet forming, wet moulding, vacuum forming, vacuum moulding, extrusion forming, extrusion moulding, thermoforming, dry forming, dry moulding, hot pressing, hot press drying, hot moulding, heat pressing, heat forming, heat moulding, thermomoulding or a combination thereof, preferably thermoforming, more preferably heat pressing, hot pressing, hot press drying or thermomoulding.

[0067] In one embodiment the fiber stock is moulded to a sheet.

[0068] In one embodiment the fiber stock is formed to a sheet, preferably thermoformed to a sheet.

[0069] The fiber stock can be thermoformed to a sheet by any suitable method known in the art. An example of a suitable method is heat pressing in which elevated mechanical pressure and elevated temperature is applied to two metal plates having fiber stock there between.

[0070] In the context of the present application by term sheet is meant an article having smaller thickness than length and width.

[0071] In the context of the present application by term two-dimensional, 2D, article is meant a 2D-article originally been made to planar shape and has a smaller thickness than length and width. The 2D-article can be folded, bended, formed or moulded to a three-dimensional, 3D, article.

[0072] In the context of the present application by term three-dimensional, 3D, article is meant an article having three dimensions. In the context of the present application a sheet is not considered to be a three-dimensional, 3D, article.

[0073] In one embodiment the sheet is formed or moulded to a three-dimensional, 3D, article.

[0074] In one embodiment the fiber stock is moulded to a three-dimensional, 3D, article.

[0075] In one embodiment the fiber stock is formed to a two-dimensional, 2D, sheet having thickness of 0.1 mm-10 mm, preferably 0.3 mm-2 mm. In one embodiment the 2D sheet is further thermoformed (i.e. dry moulded, i.e. dry formed) to a three-dimensional, 3D, article having preferably length and width of 5 cm-50 cm, depth of 2 cm-20 cm and wall thickness of 0.1 mm-2 mm.

[0076] In one embodiment the fiber stock with or without foam is vacuum formed, extrusion formed, wet pressed and/or drained by help of vacuum, unrestrained and/or restrained dried, compacted in one or more directions, polymer impregnated, polymer laminated, polymer coated or a combination thereof, to a two-dimensional, 2D, sheet having thickness of 0.1 mm-10 mm, preferably 0.3 mm-2 mm. In one embodiment the 2D sheet is further thermoformed (i.e. dry moulded, i.e. dry formed) to a three-dimensional, 3D, article having preferably length and width of 5 cm-50 cm, depth of 2 cm-20 cm and wall thickness of 0.1 mm-2 mm.

[0077] In one embodiment the fiber stock is wet moulded and the wet moulded fiber stock is moulded to a three-dimensional, 3D, article.

[0078] In one embodiment the fiber stock is vacuum formed i.e. wet moulded to a three-dimensional, 3D, article having preferably length and width of 5 cm-50 cm and depth of 2 cm-20 cm and then thermoformed and dried, preferably to wall thickness of 0.1 mm-3 mm, preferably 0.3 mm-1.0 mm.

[0079] In one embodiment temperature of mould(s) in heat pressing, hot pressing, hot press drying, thermoforming or thermomoulding is 100 C.-400 C., preferably 130 C.-200 C.

[0080] In one embodiment mechanical pressure applied on fiber stock or two- or three-dimensional fiber based article in heat pressing, hot pressing, hot press drying, thermoforming or thermomoulding is 0.1 bar-1000 bar, preferably up to 20 bar and pressure can alternate during heat pressing, hot pressing, hot press drying, thermoforming or thermomoulding depending on manufacturing technology, equipment and moulded fiber product application.

[0081] In one embodiment the moulding is thermoforming, heat pressing, thermomoulding, wet or dry moulding and/or wet or dry forming, densifying or a combination thereof, to a three dimensional article.

[0082] In one embodiment the polyamidoamine-epichlorohydrin, glyoxalated polyacrylamide, starch or a mixture thereof and the composition are introduced sequentially to the fiber stock, preferably the polyamidoamine-epichlorohydrin, glyoxalated polyacrylamide, starch or a mixture thereof is introduced to the fiber stock before introducing the composition to the fiber stock.

[0083] In one embodiment the composition is introduced to the fiber stock followed by introducing the polyamidoamine-epichlorohydrin, glyoxalated polyacrylamide, starch or a mixture thereof to the fiber stock.

[0084] In one embodiment the at least one anionic polymer and the cationic polymer are introduced sequentially to the fiber stock, preferably the at least one cationic polymer is introduced to the fiber stock before introducing the anionic polymer to the fiber stock.

[0085] In one embodiment the anionic polymer is introduced to the fiber stock followed by introducing the at least one cationic polymer.

[0086] In one embodiment the at least one anionic polymer, the cationic polymer and the polyamidoamine-epichlorohydrin, glyoxalated polyacrylamide, starch or a mixture thereof are introduced sequentially to the fiber stock.

[0087] In one embodiment the at least one anionic polymer and the cationic polymer are introduced sequentially to the fiber stock followed by introducing the polyamidoamine-epichlorohydrin, glyoxalated polyacrylamide, starch or a mixture thereof to the fiber stock.

[0088] In one embodiment the polyamidoamine-epichlorohydrin, glyoxalated polyacrylamide, starch or a mixture thereof is introduced to the fiber stock followed by introducing the at least one anionic polymer and the cationic polymer sequentially to the fiber stock.

[0089] In one embodiment the at least one anionic polymer is introduced to the fiber stock followed by introducing the polyamidoamine-epichlorohydrin, glyoxalated polyacrylamide, starch or a mixture thereof to the fiber stock followed by introducing the cationic polymer to the fiber stock.

[0090] In one embodiment the cationic polymer is introduced to the fiber stock followed by introducing the polyamidoamine-epichlorohydrin, glyoxalated polyacrylamide, starch or a mixture thereof to the fiber stock followed by introducing the at least one anionic polymer to the fiber stock.

[0091] The composition comprises a mixture of anionic polymer and cationic polymer. The anionic polymer and cationic polymer may be mixed with each other before the addition of the composition as an aqueous solution to the fibre stock, i.e. before the addition as a single solution. The mixing may be performed in any suitable way of combining the anionic polymer and cationic polymer. For example, it is possible to mix the anionic polymer and the cationic polymer in dry form or as aqueous solutions, or the anionic polymer or the cationic polymer in dry form may be dissolved to an aqueous solution of the other component.

[0092] In one embodiment the composition is in form of an aqueous solution, and it is introduced to the fibre stock as an aqueous mixture. The term aqueous solution encompasses here not only true solutions but also aqueous dispersions. Preferably, the composition in form of an aqueous solution contains at most minor amounts of incompletely dissolved residue, or is completely free of solid matter and/or incompletely dissolved residues.

[0093] Alternatively, the composition may be in form of a dry particulate material. This reduces the risk of degradation of the composition during transportation and storage, and thus improves the shelf life. Especially cationic starch as the cationic polymer may be vulnerable to microbiological degradation, which could lead to loss of performance. The composition may preferably be a mixture of solid particulate anionic polymer and solid particulate cationic polymer. Such mixture in particulate form is easy and economically advantageous to store and transport. The composition in form of a dry particulate material may have a moisture content of at most 25 weight-%. The particle size of the dry particulate material may vary for example between 5 and 2000 microns.

[0094] When the composition is in form of dry particulate material, it can be dissolved into water in order to obtain an aqueous composition, for example, by using effective high-shear dissolution, such as rotor-stator mixer, and optional application of heat, or by using jet-cooker. The dissolving may be done e.g. at the site of application. According to one preferred embodiment the composition in form of a dry particulate material is dissolved into water, preferably by using a high-shear dissolution, in order to obtain an aqueous composition. The obtained aqueous composition may then be optionally diluted and then introduced, after the optional dilution, to the fibre stock.

[0095] In one embodiment an amphoteric polymer having both anionic and cationic groups providing the charge density in the range of [0096] 0.1-1.5 meq/g, when measured at pH 2.8, and [0097] 0.1-3 meq/g, preferably 0.3-2.5 meq/g, more preferably 0.5-2.0 meq/g, when measured at pH 7.0 [0098] is introduced to the fiber stock, preferably instead of the composition.

[0099] In one embodiment an IPN (interpenetrating polymer network) material having both anionic and cationic groups providing the charge density in the range of [0100] 0.1-1.5 meq/g, when measured at pH 2.8, and [0101] 0.1-3 meq/g, preferably 0.3-2.5 meq/g, more preferably 0.5-2.0 meq/g, when measured at pH 7.0 [0102] is introduced to the fiber stock, preferably instead of the composition.

[0103] In one embodiment a polymer having both anionic and cationic groups, preferably amphoteric polymer and/or an interpenetrating polymer network material providing the charge densities is/are introduced to the fiber stock, preferably instead of the composition.

[0104] In one embodiment the composition is introduced in an amount of 5-50 kg/t, preferably 10-40 kg/t, more preferably 20-30 kg/t, based on dry weight of the fiber stock.

[0105] In one embodiment the polyamidoamine-epichlorohydrin, glyoxalated polyacrylamide or a mixture thereof is introduced in an amount of 1 kg/t-8 kg/t, preferably 2 kg/t-6 kg/t, more preferably 2 kg/t-4 kg/t as dry weight, based on the dry weight of the fiber stock.

[0106] In one embodiment the starch comprises native starch, cooked starch, uncooked starch, cationic starch, native chemically modified starch, physically modified polymer grafted starch, enzyme modified starch, anionic starch, amphoteric starch, crosslinked starch, pre-gelled starch, swelled starch, granule starch or a mixture thereof.

[0107] In one embodiment the starch is introduced in an amount of 1 kg/t-100 kg/t as dry weight, based on the dry weight of the fiber stock.

[0108] In one embodiment cationic starch is introduced in an amount of 1 kg/t-20 kg/t as dry weight, based on the dry weight of the fiber stock.

[0109] In one embodiment non-ionic starch is introduced in an amount of 1 kg/t-100 kg/t as dry weight, based on the dry weight of the fiber stock.

[0110] In one embodiment before introducing the composition and the polyamidoamine-epichlorohydrin, glyoxalated polyacrylamide, starch or a mixture thereof to the fiber stock pH of the fiber stock is adjusted to pH value 5-9, preferably 7-8.

[0111] In one embodiment conductivity of the fiber stock is adjusted to 0.05 mS/cm-6 mS/cm, preferably 0.1 mS/cm-1 mS/cm before introducing the composition and the polyamidoamine-epichlorohydrin, glyoxalated polyacrylamide, starch or a mixture thereof to the fiber stock. In one embodiment the conductivity is adjusted with a composition comprising 70% calcium acetate, 20% sodium sulphate and 10% sodium bicarbonate.

[0112] In one embodiment sizing chemical, fixative, wet strength agent, drainage aid or a mixture thereof is introduced to the fiber stock after or before introducing the composition and polyamidoamine-epichlorohydrin, glyoxalated polyacrylamide, starch or a mixture thereof to the fiber stock

[0113] In one embodiment sizing chemical, fixative, wet strength agent, drainage aid or a mixture thereof is introduced to the fiber stock before introducing the composition and polyamidoamine-epichlorohydrin, glyoxalated polyacrylamide, starch or a mixture thereof to the fiber stock.

[0114] In one embodiment sizing chemical, fixative, wet strength agent, drainage aid or a mixture thereof is introduced to the fiber stock after introducing the composition and polyamidoamine-epichlorohydrin, glyoxalated polyacrylamide, starch or a mixture thereof to the fiber stock.

[0115] In one embodiment polyamidoamine-epichlorohydrin, glyoxalated polyacrylamide, starch or a mixture thereof is introduced to the fiber stock before introducing a sizing chemical to the fiber stock.

[0116] In one embodiment a sizing chemical and polyamidoamine-epichlorohydrin, glyoxalated polyacrylamide, starch or a mixture thereof is introduced to the fiber stock at the same time but separately.

[0117] In one embodiment a sizing chemical and polyamidoamine-epichlorohydrin, glyoxalated polyacrylamide or a mixture thereof is introduced to the fiber stock as a mixture.

[0118] In one embodiment the sizing chemical comprises alkyl ketene dimer (AKD), alkenyl succinic anhydride (ASA), rosin or a mixture thereof.

[0119] In one embodiment AKD, ASA, rosin or a mixture thereof and polyamidoamine-epichlorohydrin, glyoxalated polyacrylamide, starch or a mixture thereof are introduced as a mixture to the fiber stock, preferably before introducing the composition to the fiber stock.

[0120] In one embodiment AKD, ASA, rosin or a mixture thereof and polyamidoamine-epichlorohydrin, glyoxalated polyacrylamide, starch or a mixture thereof are introduced as a mixture to the fiber stock, preferably after introducing the composition to the fiber stock.

[0121] In one embodiment AKD, ASA, rosin, polyamidoamine-epichlorohydrin, glyoxalated polyacrylamide, starch or a mixture thereof are introduced as a mixture to the fiber stock, preferably before introducing the composition to the fiber stock.

[0122] In one embodiment AKD, ASA, rosin, polyamidoamine-epichlorohydrin, glyoxalated polyacrylamide, starch or a mixture thereof are introduced as a mixture to the fiber stock, preferably after introducing the composition to the fiber stock.

[0123] In one embodiment AKD, ASA, rosin or a mixture thereof is introduced in an amount of 0.1-4%, preferably 0.5-1.5% based on dry weight of the fiber stock.

[0124] In one embodiment polyamidoamine-epichlorohydrin, glyoxalated polyacrylamide or a mixture thereof is introduced in an amount of 1-8 kg/t, preferably 2-4 kg/t as dry weight, based on dry weight of the fiber stock.

[0125] In one embodiment the fixative, drainage aid or a mixture thereof comprises aluminium sulphate (ALS), polyaluminium chloride (PAC), poly(diallyldimethylammonium chloride) (PDACMAC), cationic polyacrylamide (CPAM) or a mixture thereof.

[0126] In one embodiment the wet strength agent comprises polyamide-epichlorohydrin (PAE), glyoxalated polyacrylamide (GPAM), starch or a mixture thereof. In one embodiment the wet strength agent is added after addition of a sizing agent but before addition of the composition to the fiber stock.

[0127] In one embodiment consistency of the obtained fiber stock comprising cellulosic fibers is 0.1%-10%, preferably, preferably 0.2-1.0, more preferably 0.2%-0.5%.

[0128] In one embodiment the fiber stock comprising cellulosic fibers comprises natural fibers, synthetic fibers or a mixture thereof. Preferably the fibers are plant origin comprising recycled, chemical and/or mechanical hardwood and softwood pulps, sugar cane (such as bagasse), bamboo, marley, wheat, maize, corn, oats, barley, rice, rye, tomato, sorghum, rape seed, palm oil plants, flax, hemp, ramie, cotton, kenaf, jute, banana, cannabis, peat, moss or a mixture thereof.

[0129] In one embodiment the anionic polymer has molecular weight of at least 100 kDa, preferably at least 300, more preferably from 100 kDa to 10000 kDa, even more preferably from 100 kDa to 700 kDa, even more preferably 100 kDa to 600 kDa.

[0130] In one embodiment the anionic polymer comprises carboxymethyl cellulose, microfibrillated cellulose, microfibrillated lignocellulose, anionic starch, chitosan, pectin, fatty acid esters, other anionic and or anionically derivatized polysaccharides or a mixture thereof, preferably anionic starch, carboxymethyl cellulose, microfibrillated cellulose, microfibrillated lignocellulose or a mixture thereof.

[0131] In one embodiment the cationic polymer comprises starch derivate such as hydroxypropylated starch, nanocellulose, microfibrillated cellulose, lignocellulose based derivatives, chitosan, alfaglucan, polyhydroxy alkanoate, polylactic acid, cationic starch or a mixture thereof, preferably cationic starch, chitosan, nanocellulose, microfibrillated cellulose, lignocellulose based derivatives or a mixture thereof.

[0132] Polysaccharides, as known, are natural polymers formed from polymeric carbohydrate molecules, which comprise long chains of monosaccharide units as repeating units bound together by covalent bonds. Polysaccharides may be extracted from various botanical sources, microorganisms, etc. Polysaccharide chains contain multiple hydroxyl groups capable of hydrogen bonding.

[0133] In the present context the term anionically derivatized is understood to refer not only to chemical modification of a polysaccharide by reactions which result in covalently bonded anionic groups in the polysaccharide structure, but also to any sufficient association of anionic groups with the polysaccharide structure, which provide the desired properties, such as charge density, for the composition. Such sufficient association of anionic groups may be achieved, for example, by adsorption or by other processing of the polysaccharide starting material, such as mechanical processing. It is possible to obtain anionically derivatized polysaccharide by combination of other processing, such as mechanical processing, and chemical modification. Chemical modification of the polysaccharide is preferred for providing anionically derivatized polysaccharide suitable for use in the present invention. Anionic groups may be provided e.g. by incorporating to the polysaccharide structure carboxyl, sulphate, sulphonate, phosphonate or phosphate groups, including their salt forms, or combinations thereof. Anionic groups may be introduced to the polysaccharide structure by suitable chemical modification including carboxymethylation, oxidation, sulphation, sulphonation and phosphorylation.

[0134] In one embodiment the anionically derivatized polysaccharide which is suitable for use in the present invention may have a charge density value in the range of 0.05-5.0 meq/g, such as 0.3-5.0 meq/g or 0.5-5.0 meq/g, preferably 0.7-4.5 meq/g, more preferably 1.0-4.0 meq/g, measured at pH 7. Measured charge density values are calculated per weight as dry.

[0135] Anionically derivatized polysaccharide may comprise water-soluble and/or water-dispersible anionically derivatized polysaccharide(s). In the present context aqueous solution of anionically derivatized polysaccharide covers not only true solutions but also aqueous dispersions of anionically derivatized polysaccharide(s). Preferably the anionically derivatized polysaccharides are water-soluble, meaning that they contain at most 30 weight-%, preferably at most 20 weight-%, more preferably at most 15 weight-%, even more preferably at most 10 weight-%, of water-insoluble material. The water-solubility may improve the availability of the functional groups of the polysaccharide, thereby improving the interaction with the cationic polymer, such as cationic starch of the composition, as well as the other constituents present in the fibre stock.

[0136] In one embodiment the anionically derivatized polysaccharide comprises anionically derivatized celluloses, anionically derivatized starches, or any combinations thereof, including modified celluloses and starches, such as hydroxyethyl cellulose, hydroxyethyl starch, ethylhydroxyethyl cellulose, ethylhydroxyethyl starch, hydroxypropyl cellulose, hydroxypropyl starch, hydroxypropyl hydroxyethyl cellulose, hydroxypropyl hydroxyethyl starch, methyl cellulose, methyl starch, and the like.

[0137] In one embodiment the anionically derivatized polysaccharide comprises cellulose, preferably carboxymethylated cellulose, even more preferably carboxymethyl cellulose. Anionically derivatized polysaccharide may comprise, for example, purified carboxymethyl cellulose or technical grade carboxymethyl cellulose. The carboxymethyl cellulose may be manufactured by any process known in the art. It is believed that when the composition comprises anionically derivatized polysaccharide, which comprises cellulose, the backbone structure of the polysaccharide is similar than the cellulosic fibres in the pulp, i.e. the structure showing 1,4-beta glycosidic linkages in the backbone. This matching configuration may provide stronger interaction between the composition and the fibres.

[0138] In one embodiment the anionically derivatized polysaccharide comprises carboxymethylated cellulose, preferably carboxymethyl cellulose, which may have a degree of carboxymethyl substitution >0.2, preferably in the range of 0.3-1.2, more preferably 0.4-1.0 or 0.5-1.0, providing further enhanced water-solubility. In one preferable embodiment the carboxymethylated cellulose may have a degree of carboxymethyl substitution in the range of 0.5-0.9, which provides essentially complete water-solubility for the carboxymethyl cellulose.

[0139] In one embodiment of the anionically derivatized polysaccharide comprises carboxymethylated cellulose, preferably carboxymethyl cellulose, which may have a charge density value <1.1 meq/g, preferably in the range of 1.6-4.7 meq/g, more preferably 2.1-4.1 meq/g, even more preferably 2.5-3.8 meq/g, when measured at pH 7. All measured charge density values are calculated per weight as dry.

[0140] In one embodiment the anionically derivatized polysaccharide comprises carboxymethylated cellulose, preferably carboxymethyl cellulose, which may have viscosity in the range of 100-30 000 mPas, preferably 200-20 000 mPas, more preferably 500-10 000 mPas, measured from 2 weight-% aqueous solution at 25 C., by using Brookfield LV DV1.

[0141] In one embodiment the anionically derivatized polysaccharide comprises carboxymethylated cellulose, preferably carboxymethyl cellulose.

[0142] In one embodiment the anionically derivatized polysaccharide may be at least partly in microfibrillar form. Preferably the anionically derivatized polysaccharide comprises anionic microfibrillar cellulose. Microfibrillar cellulose is sometimes referred to as nanocellulose, but as used herein, by microfibrillar cellulose or nanocellulose it is not meant crystalline cellulose derivatives known e.g. as microcrystalline cellulose (MCC), nanocrystalline cellulose (NCC), or cellulose nanowhiskers. Crystalline cellulose derivatives are thus excluded from anionic microfibrillar cellulose. Microfibrils may have an average diameter of 2-60 nm, preferably 4-50 nm, more preferably 5-40 nm, and an average length of several micrometers, preferably less than 500 m, more preferably less than 300 m, more preferably 2-200 m, even more preferably 10-100 m, most preferably 10-60 m. Microfibrillated cellulose comprises often bundles of 10-50 microfibrils.

[0143] In one embodiment the anionically derivatized polysaccharide is free from microfibrillar cellulose.

[0144] In one embodiment the composition comprises cationic starch, which of natural origin and has an amylopectin content at least 80 weight-%. Amylopectin is a branched starch molecule, where branching typically occurs with a (1->6) bonds about at every 15-30 anhydroglucose units of the starch backbone, which contains (1.fwdarw.4) bonds. Amylopectin content of the cationic starch ensures that that the size of the polyion complex to be formed has appropriate dimensions, required for good oil and grease resistance.

[0145] In one embodiment the cationic starch of the composition may have an amylopectin content 85 weight-%, preferably 90 weight-%, more preferably 95 weight-%. Cationic starch of the composition may originate from potato, waxy potato, rice, waxy corn, sweet potato, arrowroot or tapioca starch, or any combination thereof. Preferably the cationic starch originates from waxy corn starch and/or waxy potato starch.

[0146] The cationic starch may comprise starch units, i.e. starch molecules, of which at least 70 weight-%, preferably at least 80 weight-%, more preferably at least 85 weight-%, even more preferably at least 90 weight-%, sometimes even more preferably at least 95 weight-%, have an average molecular weight MW over 20 000 000 g/mol, preferably over 50 000 000 g/mol, more preferably over 100 000 000 g/mol, sometimes even over 200 000 000 g/mol, such as 200 000 000 g/mol-500 000 000 g/mol.

[0147] In one embodiment the composition comprises cationic starch, which comprises cationic non-degraded starch. The cationic non-degraded starch provides an optimal interaction with the anionically derivatized polysaccharide as well as with other constituents of the fibre stock, e.g. fibres and/or inorganic fillers. In the present context, the term non-degraded starch denotes starch which is essentially untreated by oxidative, thermal, enzymatical and/or acid treatment in a manner that would cause hydrolysis of glycosidic bonds or degradation of starch molecules or units. In case the starch is solubilized by cooking, the temperature during cooking is less than 140 C., preferably less than 120 C., often less than 110 C. or 105 C.

[0148] For example, after solubilization the non-degraded cationic starch has a viscosity at least of 20% preferably at least 50% of a viscosity of a corresponding native starch, solubilized by cooking at 97 C. for 30 min. The viscosity measurement is made by Brookfield LV-DVI viscometer, at 2% solids content and at room temperature.

[0149] Cationic starch suitable for use in the composition may be obtained by cationizing starch by any suitable method. Preferably cationic starch is obtained by using 3-chloro-2-hydroxypropyltrimethylammonium chloride or 2,3-epoxypropyltrimethylammonium chloride. It is also possible to cationize starch by using cationic acrylamide derivatives, such as (3-acrylamidopropyl)-trimethylammonium chloride. Various methods for cationization of starch are known for a person skilled in the art.

[0150] In one embodiment the cationic starch has been obtained by using cationization as the sole chemical derivatization of starch, and the cationic starch is thus non-cross-linked, non-grafted, or it has not been otherwise chemically modified.

[0151] The cationic starch of the composition may have a substitution degree of 0.025-0.3, preferably 0.03-0.16, more preferably 0.045-0.1. The substitution degree is relative to the cationicity of the starch, the higher substitution degree indicating a higher cationicity. Cationic starches having relatively high substitution degree, and cationicity, are preferred for use in the composition as they may provide additional benefits.

[0152] In one preferable embodiment the composition is free of cationic synthetic polymers.

[0153] In one embodiment the composition, the cationic starch and/or the anionically derivatized polysaccharide may comprise further auxiliaries or additives, such as preservatives, biocides, stabilizers, antioxidants, pH adjusting agents or the like.

[0154] In one embodiment the composition comprises anionically derivatized polysaccharide and cationic starch in weight ratio (dry/dry) 10:90-90:10, preferably 30:70-70:30. The weight ratio is given as dry weights. Preferably the weight ratio of the anionically derivatized polysaccharide to the cationic starch is chosen so that the composition is net anionic at the pH of the fibre stock.

[0155] In a second aspect the present invention provides a moulded fiber based article, wherein the moulded fiber based article comprises a composition comprising [0156] at least one anionic polymer having molecular weight at least 100 kDa, and [0157] cationic polymer,
wherein the anionic polymer having molecular weight at least 100 kDa and the cationic polymer provide the composition with a charge density in the range of [0158] 0.1-1.5 meq/g, when measured at pH 2.8, and [0159] 0.1-3 meq/g, preferably 0.3-2.5 meq/g, more preferably [0160] 0.5-2.0 meq/g, when measured as an aqueous solution at pH 7.0,
optionally polyamidoamine-epichlorohydrin, glyoxalated polyacrylamide, starch or a mixture thereof, and
optionally pigment material, or
wherein the moulded fiber based article is produced with the method according to the present invention.

[0161] In one embodiment the moulded fiber based article comprises polyamidoamine-epichlorohydrin, glyoxalated polyacrylamide, starch or a mixture thereof.

[0162] In one embodiment the moulded fiber based article comprises pigment material.

[0163] In one embodiment the moulded fiber based article is thermoformed fiber based article, preferably hot pressed, hot pressed dried, heat pressed fiber based article or thermomoulded fiber based article.

[0164] In one embodiment amount of the fiber in the moulded fiber based article is 50 wt. %-99 wt. %, preferably 70 wt. %-97 wt. %, more preferably 90 wt. %-97 wt. %, based on dry weight of the moulded fiber based article.

[0165] In one embodiment amount of the composition in the moulded fiber based article is 0.5 wt. %-10 wt. %, preferably 1 wt. %-3 wt. %, based on the dry weight of the moulded fiber based article.

[0166] In one embodiment amount of the polyamidoamine-epichlorohydrin, glyoxalated polyacrylamide, starch or a mixture thereof in the moulded fiber based article is 0.05 wt. %-0.8 wt. %, preferably 0.2 wt. %-0.4 wt. %, based on dry weight of the moulded fiber based article.

[0167] In one embodiment amount of the pigment material in the moulded fiber based article is 0.01 wt. %-5 wt. %, preferably 0.5 wt. %-4 wt. %, based on dry weight of the moulded fiber based article.

[0168] In one embodiment the moulded fiber based article comprises a sizing chemical, fixative, wet strength agent, drainage aid or a mixture thereof. In one embodiment amount of the sizing chemical, fixative or a mixture thereof in the moulded fiber based article is 0.1 wt. %-5 wt. %, preferably 0.5 wt. %-2.5 wt. %, based on dry weight of the moulded fiber based article.

[0169] In one embodiment the moulded fiber based article comprises food packages, food service items, drink packages, drink service items, goods packages or goods service items, preferably food service and packaging items such as ovenable trays, microwavable trays, clamshell boxes, other food boxes, soup cups, fresh meat and poultry trays, plates or cup lids.

[0170] In one embodiment the moulded fiber based article is produced with the method of the present invention.

[0171] In a third aspect the present invention provides a use of a composition comprising [0172] at least one anionic polymer having molecular weight at least 100 kDa, and [0173] cationic polymer,
wherein the anionic polymer having molecular weight at least 100 kDa and the cationic polymer provide the composition with a charge density in the range of [0174] 0.1-1.5 meq/g, when measured at pH 2.8, and [0175] 0.1-3 meq/g, preferably 0.3-2.5 meq/g, more preferably [0176] 0.5-2.0 meq/g, when measured as an aqueous solution, at pH 7.0, and in addition
optionally polyamidoamine-epichlorohydrin, glyoxalated polyacrylamide, starch or a mixture thereof, and
optionally pigment material for improving grease and oil resistance a moulded fiber based article.

[0177] In one embodiment the composition is used for improving grease resistance. In one embodiment the composition is used for improving oil resistance. In one embodiment the composition is used for improving oil and grease resistance.

[0178] In one embodiment the polyamidoamine-epichlorohydrin, glyoxalated polyacrylamide, starch or a mixture thereof is used in addition to the composition for improving oil resistance of a thermoformed fiber based article.

[0179] In one embodiment the pigment material is used in addition to the polyamidoamine-epichlorohydrin, glyoxalated polyacrylamide, starch or a mixture thereof and the composition for improving grease and oil resistance of a thermoformed fiber based article.

[0180] In one embodiment a sizing chemical, fixative or a mixture thereof is used in addition to the polyamidoamine-epichlorohydrin, glyoxalated polyacrylamide, starch or a mixture thereof, the composition and the pigment material for improving grease and oil resistance of a thermoformed fiber based article.

EXAMPLES

Example 1 According to the Present Invention

[0181] AKD, 0.1-0.3% (by dry weight) is first added to fiber stock with 0-3-0.5% consistency made from 100% birch kraft pale pulp and fiber stock. Then 0.2-0.4% (by dry weight) of polyamide-epichlorohydrin (PAE) is added to fiber stock. Then 0.2-0.4% (by dry weight) PDACMAC+CPAM is added to the fiber stock. Then 1-3% (by dry weight) of the composition comprising at least one anionic polymer having molecular weight at least 300-500 kDa and cationic polymer and optionally PAAE is added to the fiber stock. After addition of each chemical to the fiber stock the stock is mixed for at least 1 minute under turbulent conditions before addition of next chemical.

Example 2, Comparative Example(s)

[0182] Same method and chemicals were used to prepare and determine characteristics of a 2D molded fiber article/sheet as in Example 1 but now PAAE and cationic starch were tested as alone and together by adding PAAE first and then cationic starch to fiber stock. The composition comprising at least one anionic polymer having molecular weight 300-500 kDa and cationic polymer and PAAE were tested as in Example 1. PAAE was also tested with the anionic polymer of the composition by adding PAAE first and then the anionic polymer to fiber stock.

Preparation of Two-Dimensional, 2D, Article/Sheet

[0183] After introducing the chemicals according to example 1 and 2 to the fiber stock the fiber stock is vacuum formed to dryness of 20-30% using dynamic drainage analyzer under 200-650 mBar vacuum against planar round shaped 10 cm in diameter, forming wire with 200-400 micron openings. Wet 2D article/sheet with grammage of 200-800 g/m.sup.2 as dry is hot press dried and thermoformed to 0.2-1.2 mm thickness between 130-200 C. metal plates until dryness of 94-99% is reached. Hot press dried and thermoformed 2D moulded fiber articles/sheets are shown in FIG. 6.

[0184] The 2D fiber moulded article may be hot pressed and/or thermoformed to a density of 0.5 g/cm.sup.3-1.5 g/cm.sup.3, preferably 1.0-1.2 g/cm3 and thickness of 0.1-1.2 mm, preferably 0.3-0.8 mm.

Preparation of Three-Dimensional, 3D, Article

[0185] After introducing the chemicals to the fiber stock a 3D shaped forming wire with suction mould is dipped into the fiber stock and fiber stock material is drawn/formed against the 3D wire with 200-500 micron openings under up to 900 mBar vacuum. Formed 3D article is lifted up from the fiber stock and vacuum suction assisted drainage is continued until dryness of wet moulded 3D article is 33% on average. Wet moulded 3D article is then transferred on to heated counter mould (130-200 C.) and hot press dried and thermoformed to 0.2-1.2 mm thickness and final dryness of 90-96%. Dried 3D moulded fiber article is shown in FIG. 7.

[0186] The 3D article may be hot press dried and thermoformed to a wall thickness of 0.2 mm-1.2 mm, such as 0.5 mm-0.8 mm, length of 5 cm-50 cm, width of 5 cm-50 cm and depth of 2 cm-20 cm.

Oil and Grease Resistance Test

[0187] Oil and grease testing was performed using the test method based on standard ASTM F119-82:2015. Grease testing was performed using the test method based on standard TAPPI T559: 2012.

[0188] As can be seen from FIGS. 1 and 4 the thermoformed article (2D article/sheet) of the present invention exhibits increased oil resistance compared to the zero test (only fiber stock comprising cellulosic fibers, no chemicals added) and to the comparative thermoformed articles. As can be seen from FIGS. 2 and 5 the thermoformed article (2D article/sheet) of the present invention exhibits increased dry tensile properties. As can be seen from FIG. 3 the thermoformed article (2D article/sheet) of the present invention exhibits increased high moisture tensile properties.

[0189] Various embodiments have been presented. It should be appreciated that in this document, words comprise, include, and contain are each used as open-ended expressions with no intended exclusivity.

[0190] The foregoing description has provided by way of non-limiting examples of particular implementations and embodiments a full and informative description of the best mode presently contemplated by the inventors for carrying out the invention. It is however clear to a person skilled in the art that the invention is not restricted to details of the embodiments presented in the foregoing, but that it can be implemented in other embodiments using equivalent means or in different combinations of embodiments without deviating from the characteristics of the invention.

[0191] Furthermore, some of the features of the afore-disclosed example embodiments may be used to advantage without the corresponding use of other features. As such, the foregoing description shall be considered as merely illustrative of the principles of the present invention, and not in limitation thereof. Hence, the scope of the invention is only restricted by the appended patent claims.