Method for producing molded fiber product and molded fiber product thereof

Abstract

There is provided a method for producing a molded fiber based article by forming the molded fiber based article from a first aqueous pulp suspension and a second aqueous suspension comprising refined fiber material. Additionally, is provided a molded fiber based article produced with said method.

Description

[0001] METHOD FOR PRODUCING MOLDED FIBER PRODUCT AND MOLDED FIBER

[0002] PRODUCT THEREOF

[0003] TECHNICAL FIELD

[0004] The present disclosure generally relates to a method for increasing grease and oil resistance of a fiber based article.

[0005] BACKGROUND

[0006] This section illustrates useful background information without admission of any technique described herein representative of the state of the art.

[0007] Pollution caused by single use plastic containers and packaging materials is epidemic, scarring the global landscape and threatening delicate ecosystems and the life forms that inhabit them. Single use containers migrate along waterways to the oceans e.g. in the form of styrofoam and expanded polystyrene (EPS) packaging, to-go containers, bottles, thin film bags and photo-degraded plastic pellets. Sustainable solutions for reducing plastic pollution are gaining momentum. However, continuing adoption requires that these solutions not only be good for the environment, but also competitive with plastics from both a performance and a cost standpoint.

[0008] Molded paper pulp (molded fiber) has been used since the early 20thcentury to make containers, trays and other packages, but experienced a decline in the 1970s after the introduction of fossil based plastic foam packaging. Paper pulp can be produced e.g. from old newsprints, corrugated boxes and other plant fibers. Today, molded pulp packaging is widely used for electronics, household goods, automotive parts, medical products and as an edge / corner protector or pallet tray for shipping electronic and other fragile components.

[0009] Cellulose fiber-based packaging products are biodegradable, compostable and, unlike fossil based plastics, do not migrate into the ocean. However, presently known fiber technologies are not well suited for use with meat and poultry, prepared food, produce, microwavable food, or as lids for beverage containers such as hot coffee. In particular, selectively integrating one or more oil, water, vapor, and / or oxygen barrier chemicals into pulp slurry, and / or selectively applying one or more barrier layers to all or a portion of the surface of the finished packaging product, can be cumbersome, time consuming, and expensive.

[0010] Depending on molded pulp application, oil, grease, water, water vapor, oxygen and / or other gas, liquid etc. barrier properties are needed in different container types. Use of suitable pulp slurry chemicals can improve process efficiency, mechanical properties, barrier properties and / or surface coatability and therefore, make production of molded pulp products more competitive against products made from planar board.

[0011] SUMMARY

[0012] The following presents a simplified summary of the features disclosed herein to provide a basic understanding of some exemplary aspects of the invention. This summary is not an extensive overview of the invention. It is not intended to identify key / critical elements of the invention or to delineate the scope of the invention. Its sole purpose is to present some concepts disclosed herein in a simplified form as a prelude to a more detailed description.

[0013] In a first aspect the present invention provides a method for producing a molded fiber product comprising the steps of:

[0014] - providing a first aqueous pulp suspension with a dry content between 0.01 and 10 wt%;

[0015] - providing a forming tool having a forming surface, and immersing at least a portion of said forming surface into the first aqueous pulp suspension under applied vacuum so that said forming surface is covered with a wet layer of pulp from said first aqueous pulp suspension, said layer representing a precursor structure comprising a dry content between 10 and 99 wt%;

[0016] - providing a second aqueous suspension

[0017] (a) comprising refined cellulose fibers having Schopper Riegler (SR) value >95 on average basis and a sizing agent, wherein the second aqueous suspension (a) is produced by introducing the refined cellulose fibers having SR value >95 on average basis to water prior introducing the sizing agent to the water;

[0018] (b) comprising refined cellulose fibers having SR value >95 on average basis, sizing agent and polyhydroxy alkanoate (PHA), wherein the second aqueous suspension (b) is produced by introducing the refined cellulosic fibers having SR value >95 on average basis, the PHA and the sizing agent to water, or

[0019] (c) comprising refined cellulose fibers having SR value >95 on average basis, sizing agent and acrylate dispersion, wherein the second aqueous suspension (c) is produced by introducing the refined cellulosic fibers having SR value >95 on average basis, the acrylate dispersion and the sizing agent to water;

[0020] - immersing the precursor structure into the second aqueous suspension (a), (b) or (c) under applied vacuum so that a top barrier layer is formed on at least a portion of said precursor structure; or

[0021] - applying the second aqueous suspension (a), (b) or (c) on at least a portion of said precursor structure so that a top barrier layer is formed; and

[0022] - dewatering and / or drying said precursor structure comprising the top barrier layer under temperature >100°C to a dry content of >85 wt% to achieve the molded fiber product.

[0023] In a second aspect the present invention provides a molded fiber product comprising at least a first layer and a second top barrier layer, said product being produced by means of a method comprising the steps of:

[0024] - providing a first aqueous pulp suspension with a dry content between 0.01 and 10 wt%;

[0025] - providing a forming tool having a forming surface, and immersing at least a portion of said forming surface into the first aqueous pulp suspension under applied vacuum so that said forming surface is covered with a wet layer of pulp from said first aqueous pulp suspension, said layer representing a precursor structure comprising a dry content between 10 and 99 wt%;

[0026] - providing a second aqueous suspension

[0027] (a) comprising refined cellulose fibers having Schopper Riegler (SR) value >95 on average basis and a sizing agent, wherein the second aqueous suspension (a) is produced by introducing the refined cellulose fibers having SR value >95 on average basis to water prior introducing the sizing agent to the water; (b) comprising refined cellulose fibers having SR value >95 on average basis, sizing agent and polyhydroxy alkanoate (PHA), wherein the second aqueous suspension (b) is produced by introducing the refined cellulosic fibers having SR value >95 on average basis, the PHA and the sizing agent to water, or

[0028] (c) comprising refined cellulose fibers having SR value >95 on average basis, sizing agent and acrylate dispersion, wherein the second aqueous suspension (c) is produced by introducing the refined cellulosic fibers having SR value >95 on average basis, the acrylate dispersion and the sizing agent to water;

[0029] - immersing the precursor structure into the second aqueous suspension (a), (b) or (c) under applied vacuum so that a top barrier layer is formed on at least a portion of said precursor structure, or

[0030] - applying the second aqueous suspension (a),(b) or (c) on at least a portion of said precursor structure so that a top barrier layer is formed; and

[0031] - dewatering and / or drying said precursor structure comprising the top barrier layer under temperature >100°C to a dry content of >85 wt% to achieve the molded fiber product.

[0032] It has been surprisingly found that polyhydroxyalkanoate (PHA) significantly increases oil penetration time when applied with highly (=SR >95) refined cellulose fibers and a sizing agent (such as AKD) as an aqueous solution on a surface of wet vacuum formed molded fiber article by wet vacuum forming coating and then dried by hot pressing / thermoforming.

[0033] It was also found that increased oil penetration time is obtained also by applying the aqueous solution comprising the PHA, the highly refined cellulose and the sizing agent on a surface of wet vacuum formed molded fiber article by another method, such as spraying, laminating and other coating methods, preferably laminating.

[0034] It has also been surprisingly found that oil penetration time can be significantly increased by applying an aqueous solution, prepared by addition of a sizing agent (such as AKD) after addition of refined cellulose fibers (such as CMC) to water, on a surface of wet vacuum formed molded fiber article by wet vacuum forming coating and then dried by hot pressing / thermoforming. It is also believed, without bounding to any theory, that increased oil penetration time is obtained also by applying the aqueous solution, prepared by addition of a sizing agent (such as AKD) after addition of refined cellulose fibers (such as CMC) to water, on a surface of wet vacuum formed molded fiber article by another method, such as spraying, laminating and other coating methods.

[0035] The appended claims define the scope of protection.

[0036] BRIEF DESCRIPTION OF THE FIGURES

[0037] Figure 1 shows oil, grease (=KIT) and water barrier properties of cellulose fiber based product with top barrier layer comprising pulp with calculated Schopper Riegler (SR) value of about 120. AKD dosage is 10 kg AKD wax / t dry top barrier layer pulp. PHA, CMC and vMfC dosages are 30 kg as dry / t dry top barrier layer pulp.

[0038] Figure 2 shows oil, grease (=KIT) and water barrier properties of cellulose fiber based product with top barrier layer comprising pulp with average calculated Schopper Riegler (SR) value of about 105. AKD dosage is 7.5 kg AKD wax / t dry top barrier layer pulp. CMC dosage is 30 kg as dry / t dry top barrier layer pulp.

[0039] DETAILED DESCRIPTION

[0040] In a first aspect the present invention provides a method for producing a molded fiber product comprising the steps of:

[0041] - providing a first aqueous pulp suspension with a dry content between 0.01 and 10 wt%, preferably between 0.2 and 0.8 wt%;

[0042] - providing a forming tool having a forming surface, and immersing at least a portion of said forming surface into the first aqueous pulp suspension under applied vacuum so that said forming surface is covered with a wet layer of pulp from said first aqueous pulp suspension, said layer representing a precursor structure comprising a dry content between 10 and 99 wt%, preferably between 15 and 50 wt%;

[0043] - providing a second aqueous suspension

[0044] (a) comprising refined cellulose fibers having Schopper Riegler (SR) value >95 on average basis and a sizing agent, wherein the second aqueous suspension (a) is produced by introducing the refined cellulose fibers having SR value >95 on average basis to water prior introducing the sizing agent to the water;

[0045] (b) comprising refined cellulose fibers having SR value >95 on average basis, sizing agent and polyhydroxy alkanoate (PHA), wherein the second aqueous suspension (b) is produced by introducing the refined cellulosic fibers having SR value >95 on average basis, the PHA and the sizing agent to water, or

[0046] (c) comprising refined cellulose fibers having SR value >95 on average basis, sizing agent and acrylate dispersion, wherein the second aqueous suspension (c) is produced by introducing the refined cellulosic fibers having SR value >95 on average basis, the acrylate dispersion and the sizing agent to water;

[0047] - immersing the precursor structure into the second aqueous suspension (a), (b) or (c) under applied vacuum so that a top barrier layer is formed on at least a portion of said precursor structure, or

[0048] - applying, by another method than immersing the precursor structure into the second aqueous suspension (a), (b) or (c), the second aqueous suspension (a),(b) or (c) on at least a portion of said precursor structure so that a top barrier layer is formed; and

[0049] - dewatering and / or drying said precursor structure comprising the top barrier layer under temperature >100°C (such as >100°C and less than 250°C), preferably >150°C (such as >150°C and less than 220°C) to a dry content of >85 wt%, preferably >90 wt%, more preferably >95% to achieve the molded fiber product.

[0050] The aqueous solution (b) can be produced by adding the refined cellulosic fibers having SR value >95 on average basis, the PHA and the sizing agent in any order to water, or as a mixture to water, or simultaneously but separately to water.

[0051] In one embodiment the aqueous solution (b) is produced by introducing the refined cellulosic fibers having SR value >95 on average basis to water followed by introducing PHA to the water and refined cellulose fibers suspension followed by introducing the sizing agent to the water, the refined cellulose fibers and PHA suspension. The aqueous solution (c) can be produced by adding the refined cellulosic fibers having SR value >95 on average basis, the acrylic dispersion and the sizing agent in any order to water, or as a mixture to water, or simultaneously but separately to water.

[0052] In one embodiment the aqueous solution (c) is produced by introducing the refined cellulosic fibers having SR value >95 on average basis to water followed by introducing the acrylic dispersion to the water and refined cellulose fibers suspension followed by introducing the sizing agent to the water, the refined cellulose fibers and acrylic dispersion suspension.

[0053] In the method at least a part of a forming portion of a forming tool is immersed into the slurry bath comprising a first aqueous pulp suspension. Said forming portion is arranged to represent a mirror image of the article to be formed. Pulp is drawn onto the forming portion by means of vacuum suction through the tool until a wet pulp layer of desired thickness has been formed, whereupon the forming tool is removed from the suspension, thus a wet intermediate precursor structure has been obtained.

[0054] In the next step, a second aqueous suspension is provided. The wet intermediate precursor structure is immersed into the second aqueous suspension and drawn onto the surface thereof by means of vacuum suction so that a top layer providing barrier properties is formed.

[0055] The precursor structure having been covered with a top barrier layer is then dewatered and dried. Preferably, dewatering of said molded precursor structure is performed as a onesided dewatering by means of applying suction at the non-coated side of the structure. Sucking from the untreated side leads to that the top layer substances are partially drawn into the substrate and gets integrated therewith, and binding of the top surface components onto the substrate is improved.

[0056] Dewatering and / or drying can be done in various ways. In a wet curing procedure, the wet layer is pressed under elevated temperatures to be compressed and dried to a certain thickness, thereby yielding a smooth external surface of the end structure. In a dry curing process, the wet layer is subjected to heated air thereby removing moisture.

[0057] In one embodiment of the method, the forming tool is kept immersed in the first aqueous pulp suspension under vacuum suction until 300-400 g / m2(on dry basis) layer i.e. precursor structure is formed with vacuum suction and then is lifted up from the first aqueous pulp suspension and then free water may is removed from the wet precursor structure with vacuum until dryness is 15-25%. The wet precursor structure is then immersed into the second aqueous suspension and is kept there under vacuum suction until a 20-30 g / m2 (on dry basis) top barrier layer structure is formed on the precursor structure.

[0058] In one embodiment the refined cellulose fibers comprise nanofibrillated cellulose (NFC), microfibrillated cellulose (MFC), non-wood microfibrillated cellulose, cellulose fiber fines, modified cellulose, such as carboxy methyl cellulose (CMC), or a mixture thereof.

[0059] The non-wood MFC (can also be referred as vegetable microfibrillated cellulose, vMFC) suitable for use in the present invention may originate from agricultural biomass, such as vegetables, fruits, grasses, cereals, pseudocereals, legumes or any combination thereof. For example, the microfibrillated non-wood cellulose may originate from one or more of the following; vegetables selected from sugar beet, beetroot, potato, cassava, sweet potato, carrot, parsnip, radish or any mixtures thereof; fruits selected from apple, pear, tomato, cranberry, blueberry, citrus fruits, such as orange, lime, lemon, grapefruit, or any mixtures thereof; grasses selected from maize, wheat, oat, rye, barley, sugar cane, sorghum or any mixtures thereof; pseudocereals selected from amaranth, quinoa, buckwheat or any mixtures thereof; legumes selected from plants of the family Fabaceae (or Leguminosae), such as alfalfa, clover, different species of peas, different species of beans, such as soybeans, vicia fabas, lentils, lupins, and any mixtures thereof.

[0060] Nanofibrillated cellulose (NFC) shall in the context of the patent application mean a nanoscale cellulose particle fiber or fibril with at least one dimension equal or less than 100 nm, preferably having a width or diameter from 5 nm to 100 nm. Various methods exist to make NFC.

[0061] Microfibrillated cellulose (MFC) shall in the context of the patent application mean a cellulose particle, fiber or fibril having a width or diameter of from 20 nm to 1000 nm. Various methods exist to make MFC, such as single or multiple pass refining, pre-hydrolysis.

[0062] Non-wood microfibrillated cellulose shall in the context of the patent application mean a non-wood cellulose particle, fiber or fibril having a width or diameter of from 20 nm to 1000 nm. Various methods exist to make non-wood microfibrillated cellulose.

[0063] Cellulose fibers shall in the context of the patent application mean cellulose fiber particles and / or fibrils passing a 35-mesh screen but not a 200-mesh screen. Various methods exist to make cellulose fiber fines. It is known in the art that SR value can be measured up to SR value 100. Higher SR values are calculated values based on extrapolation of the SR value up to 100 - refining time and / or refining energy curve.

[0064] In one embodiment the refined cellulose fibers have SR value more than 95 but less than 130 on average basis, preferably SR value more than 100 but less than 130 on average basis.

[0065] In one embodiment the refined cellulose fibers are a mixture of two or more refined cellulose fibers having different SR values, such as for example SR value 90 and SR value 120.

[0066] In the context of the patent application term “on average basis” in connection with SR value shall mean an average SR value of SR values of two or more refined cellulose fibers having different SR values.

[0067] As an example, the refined cellulose fibers can be a mixture of two refined cellulose fibers having different SR values, such as a mixture of1Zs of refined cellulose fiber having SR value 90 and % of refined cellulose fiber having SR value 120. Thus, an average SR value of said refined cellulose fiber mixture can be expressed to be “SR value >95 on average basis”.

[0068] In one embodiment the first aqueous pulp suspension is provided with consistency between 0.05-10wt%, preferably 0.2 - 1.5 wt%. The pulp may be any one of wood pulps, non-wood pulps, unbleached chemical pulp, defibrated fiber material, bagasse, straws, bamboo, spruce CTMP, eucalyptus CTMP, spruce HT CTMP, sulphate, sulphite, PGW, GW, DIP, recycled paper and board, broke, RMP, TMP, CMP, NSSC, dissolving pulp, and regenerated fibers or a combination thereof.

[0069] The refined cellulose fibers of a second aqueous suspension can be derived from one of wood pulps, non-wood pulps, unbleached chemical pulp, defibrated fiber material, bagasse, straws, bamboo, spruce CTMP, eucalyptus CTMP, spruce HT CTMP, sulphate, sulphite, PGW, GW, DIP, recycled paper and board, broke, RMP, TMP, CMP, NSSC, dissolving pulp, and regenerated fibers or a combination thereof.

[0070] In one embodiment the first aqueous pulp suspension comprises a sizing agent.

[0071] In one embodiment the sizing agent comprises alkyl ketene dimer (AKD), alkenyl succinic anhydride (ASA), copolymer of styrene and ester (SAE), rosin size, such as soap or rosin emulsion, polyurethane and / or styrene maleic anhydrides or a combination thereof, preferably AKD.

[0072] In one embodiment the concentration of the sizing agent in the first aqueous pulp suspension is between 0.1-50 kg / tn, preferably 3-15 kg / tn, such as 5-15 kg / tn, based on the dry content of the wet layer.

[0073] In one embodiment the concentration of the sizing agent in the second aqueous suspension (a),(b) and (c) is between 0.1-50 kg / tn, preferably 3-15 kg / tn, such as 5-15 kg / tn, based on the dry content of the top barrier layer.

[0074] In one embodiment the concentration of the sizing agent in the first aqueous pulp suspension is between 0.1-50 kg / tn, preferably 3-15 kg / tn, such as 5-15 kg / tn, based on the dry content of the wet layer and / or the concentration of the sizing agent in the second aqueous suspension (a),(b) and (c) is between 0.1-50 kg / tn, preferably 3-15 kg / tn, such as 5-15 kg / tn, based on the dry content of the top barrier layer.

[0075] In one embodiment concentration of the PHA in the second aqueous suspension (b) is between 0.1-300kg / tn, preferably 1-200 kg / tn, more preferably 10-100 kg / tn, more preferably 20-40 kg / tn, based on the dry content of the top barrier layer.

[0076] In one embodiment concentration of the acrylic dispersion in the second aqueous suspension (c) is between 0.1-300kg / tn, preferably 1-200 kg / tn, more preferably 10-100 kg / tn, more preferably 20-40 kg / tn, based on the dry content of the top barrier layer.

[0077] The acrylic dispersion comprises acrylic polymer. The acrylic polymer is produced by polymerizing acrylate monomers, preferably by radical polymerization.

[0078] In one embodiment the acrylate monomer comprises vinyl monomers, preferably the vinyl monomers comprise at least one first monomer (a) selected from C1-C8 alkyl (meth)acrylates or any of their mixture and optionally at least one second monomer (b) selected from vinyl monomers containing aromatic structure or any of their mixture and / or optionally at least one monomer (c) comprising other vinyl monomers.

[0079] The at least one monomer (c) comprises different vinyl monomers that the at least one first monomer (a) and the at least one monomer (b). In one embodiment the acrylate monomer comprises at least one monomer (a), at least one monomer (b) and at least one monomer (c).

[0080] In one embodiment the acrylate monomer comprises at least one monomer (a) and at least one monomer (b).

[0081] In one embodiment the acrylate monomer comprises at least one monomer (a) and at least one monomer (c).

[0082] In one embodiment of the vinyl monomers may comprise at least one first monomer (a) which is selected from alkyl (meth)acrylates, such as C1-C8 alkyl (meth)acrylates and any of their mixtures. Suitable first monomer (a) may be, for example, methyl acrylate; methyl methacrylate; ethyl acrylate; ethyl methacrylate; n-propyl or iso-propyl acrylate and corresponding propyl methacrylates; n-butyl, iso-butyl, tert-butyl or 2-butyl acrylate and the corresponding butyl methacrylates; n-pentyl or neopentyl acrylate and the corresponding pentyl methacrylates; 2-hexyl or 2-ethylhexyl acrylate and corresponding methacrylates; n- octyl or isooctyl acrylate and corresponding methacrylates. For example, the first monomer (a) may be a mixture of n-butyl acrylate, methyl methacrylate, 2-ethylhexyl acrylate or isobutyl methacrylate.

[0083] In one embodiment the first monomer (a) is selected from C1-C6-alkyl acrylates, C1-C6- alkyl methacrylates or any of their mixtures, such as methyl acrylate; methyl methacrylate; ethyl acrylate; ethyl methacrylate; n-butyl, iso-butyl, tert-butyl or 2-butyl acrylate and the corresponding butyl methacrylates; n-hexyl, iso-hexyl, or 2-hexyl acrylate and corresponding methacrylates. For example, the first monomer (a) may be a mixture of n- butyl acrylate, methyl methacrylate, n-hexyl acrylate or iso-butyl methacrylate.

[0084] In one embodiment the vinyl monomers may comprise at least one second monomer (b) which may be selected from aromatic vinyl monomers such as styrene, a-methylstyrene, vinyltoluene, ethylvinyltoluene, divinylbenzene, vinyl phenol, and any of their mixtures.

[0085] The polymeric material may be obtained by radical polymerization of 25 - 100 weight-%, preferably 30 - 100 weight-%, more preferably 45 - 99.9 weight-%, of the first monomer (a), and 0 - 75 weight-%, preferably 0 - 70 weight-%, more preferably 0 - 55 weight-%, of the second monomer (b), calculated from the total dry solids content of the monomers (a) and (b). In one embodiment the polymeric material may be obtained by radical polymerization of at least first monomers (a), at least one second monomer (b) and at least one third monomer (c), which is ethylenically unsaturated and different from the at least one first monomer (a) and the at least one second monomer (b). Suitable ethylenically unsaturated third monomers (c) are stearyl acrylate, stearyl methacrylate, esters of acrylic and methacrylic acid with alcohols which have more than eight C atoms, and further acrylonitrile, methacrylonitrile, acrylamide, vinyl acetate or anionic comonomers, such as acrylic acid, methacrylic acid. Acrylic acid and methacrylic acid may be preferred as third monomer (c). The amount of third monomer (c) may be 0 - 9 weight-%, preferably 0 - 7 weight-%, more preferably 0.1 - 5 weight-%, calculated from the total dry solids content of the monomers (a)+(b)+(c).

[0086] In one embodiment the acrylic dispersion is aqueous acrylic dispersion.

[0087] In one embodiment the first aqueous pulp suspension comprises a retention agent, a dewatering enhancing agent, a formation enhancing agent, a barrier enhancing agent, a strength enhancing agent, a coatability enhancing agent or a combination thereof.

[0088] In one embodiment the second aqueous suspension (a), (b) and (c) comprise a retention agent, a dewatering enhancing agent, a formation enhancing agent, a barrier enhancing agent, a strength enhancing agent, a coatability enhancing agent or a combination thereof.

[0089] In one embodiment the first aqueous pulp suspension and / or the second aqueous suspension (a), (b) and (c) comprise a retention agent, a dewatering enhancing agent, a formation enhancing agent, a barrier enhancing agent, a strength enhancing agent, a coatability enhancing agent or a combination thereof.

[0090] In one embodiment the retention agent comprises polyacrylamide (PAM), cationic polyacrylamide (CPAM), polyethyleneimine (PEI), polydiallyldimethylammonium chloride (PDACMAC), colloidal silica, bentonite or a combination thereof, preferably CPAM.

[0091] In one embodiment the first aqueous pulp suspension comprises a retention agent at a concentration between 0.05-2.0 kg / tn, preferably between 0.1-1.0 kg / tn, more preferably between 0.15-0.5 kg / tn, based on the dry content of the wet layer. In one embodiment the second aqueous suspension (a), (b) and (c) comprise a retention agent at a concentration between 0.05-2.0 kg / tn, preferably between 0.1 -1.0 kg / tn, more preferably between 0.15-0.5 kg / tn, based on the dry content of the top barrier layer.

[0092] In one embodiment the first aqueous pulp suspension comprises a wet strength agent at a concentration between 1-100 kg / tn, preferably between 5-75 kg / tn, more preferably between 10-50 kg / tn, based on the dry content of the wet layer.

[0093] In one embodiment the second aqueous suspension (a), (b) and (c) comprise a wet strength agent at a concentration between 1-100 kg / tn, preferably between 5-75 kg / tn, more preferably between 10-50 kg / tn, based on the dry content of the top barrier layer.

[0094] In one embodiment the first aqueous pulp suspension comprises a wet strength agent at a concentration between 1-100 kg / tn, preferably between 5-75 kg / tn, more preferably between 10-50 kg / tn, based on the dry content of the wet layer and / or the second aqueous suspension (a),(b) and (c) comprise a wet strength agent at a concentration between 1-100 kg / tn, preferably between 5-75 kg / tn, more preferably between 10-50 kg / tn, based on the dry content of the top barrier layer.

[0095] In one embodiment the wet strength agent comprises polyamide epichlorohydrin, polyethylene imine, dialdehyde starch, polyacryl amides, glyoxal or melamine formaldehyde, urea formaldehyde melamine or a combination thereof.

[0096] In one embodiment the applying, by another method than immersing the precursor structure into the second aqueous suspension (a),(b) or (c), comprises spray coating, dip coating, flow coating, curtain coating, pad coating, laminating, rod coating, blade coating, flexographic coating, gravure coating, air-knife coating or a combination thereof.

[0097] In one embodiment a first sheet is produced from the first aqueous pulp suspension by applying the first aqueous pulp suspension on a wire for obtaining a web and dewatering and / or drying the web for obtaining a first sheet.

[0098] In one embodiment a second sheet is produced from the second aqueous suspension (a), (b) or (c) by applying the second aqueous suspension (a), (b) or (c) on a wire for obtaining a web and dewatering and / or drying the web to obtain a second sheet.

[0099] In one embodiment a layered structure is formed from the first sheet and the second sheet. In one embodiment the layered structure is produced with a method comprising placing the second sheet on the first sheet; optionally applying pressure over the sheets for improving adhesion of the sheets and / or applying suction at the sheets for dewatering the sheets; and wet pressing and / or hot pressing the layered structure. Optionally, the layered structure can be produced by placing the first sheet on the second sheet. In one embodiment at least two layers are made from the second aqueous suspension (a), (b) or (c).

[0100] In one embodiment at least one layer is made by means of the vacuum-assisted suction from an aqueous suspension comprising barrier components to form a water barrier layer, gas barrier layer and / or vapour barrier layer.

[0101] In one embodiment at least one layer is made by applying, by other method than by means of the vacuum-assisted suction, an aqueous suspension comprising barrier components to form a water barrier layer, gas barrier layer and / or vapour barrier layer. The applying comprises spray coating, dip coating, flow coating, curtain coating, pad coating, laminating, rod coating, blade coating, flexographic coating, gravure coating, air-knife coating or a combination thereof.

[0102] In one embodiment the barrier components comprise alkyl ketene dimer (AKD), rosin, alkenyl succinic anhydride (ASA), modified starch, styrene maleic anhydride (SMA), polyurethane (PUR), styrene acrylic acid (SAA), styrene acrylic emulsion (SAE), ethylene acrylic acid (EAA), gelatin, starch, acrylic, styrene butadiene, polyvinylalcohol (PVOH), ethylene vinyl alcohol (EVOH), polyvinyl alcohol (PVA), polyethylene (PE), polyethylene terephthalate (PET), poly propylene (PP) based chemical or a combination thereof.

[0103] In one embodiment the dewatering of the molded precursor structure is performed as a onesided dewatering.

[0104] In one embodiment the drying of the molded structure is performed as unrestrained or restrained by drying in oven, between hot press molds and / or between thermoforming molds or a combination thereof.

[0105] In a second aspect the present invention provides a molded fiber product comprising at least a first layer and a second top barrier layer, said product being produced by means of a method comprising the steps of: - providing a first aqueous pulp suspension with a dry content between 0.01 and 10 wt%, preferably between 0.2 and 0.8 wt%;

[0106] - providing a forming tool having a forming surface, and immersing at least a portion of said forming surface into the first aqueous pulp suspension under applied vacuum so that said forming surface is covered with a wet layer of pulp from said first aqueous pulp suspension, said layer representing a precursor structure comprising a dry content between 10 and 99 wt%, preferably between 15 and 50 wt%;

[0107] - providing a second aqueous suspension

[0108] (a) comprising refined cellulose fibers having Schopper Riegler (SR) value >95 on average basis and a sizing agent, wherein the second aqueous suspension (a) is produced by introducing the refined cellulose fibers having SR value >95 on average basis to water prior introducing the sizing agent to the water;

[0109] (b) comprising refined cellulose fibers having SR value >95 on average basis, sizing agent and polyhydroxy alkanoate (PHA), wherein the second aqueous suspension (b) is produced by introducing the refined cellulosic fibers having SR value >95 on average basis, the PHA and the sizing agent to water; or

[0110] (c) comprising refined cellulose fibers having SR value >95 on average basis, sizing agent and acrylate dispersion, wherein the second aqueous suspension (c) is produced by introducing the refined cellulosic fibers having SR value >95 on average basis, the acrylate dispersion and the sizing agent to water;

[0111] - immersing the precursor structure into the second aqueous suspension (a), (b) or (c) under applied vacuum so that a top barrier layer is formed on at least a portion of said precursor structure; or

[0112] - applying, by another method than immersing the precursor structure into the second aqueous suspension (a), (b) or (c), the second aqueous suspension (a), (b) or (c) on at least a portion of said precursor structure so that a top barrier layer is formed; and

[0113] - dewatering and / or drying said precursor structure comprising the top barrier layer under temperature >100°C (such as >100°C and less than 250°C), preferably >150°C (such as >150°C and less than 220°C) to a dry content of >85 wt%, preferably >90 wt%, more preferably >95% to achieve the molded fiber product.

[0114] In one embodiment the molded fiber product having the top barrier layer formed from the aqueous solution (a) has oil penetration time at 60 °C at least 10min, preferably at least 3 h, more preferably at least 24 h.

[0115] In one embodiment the molded fiber product having the top barrier layer formed from the aqueous solution (b) has oil penetration time at 60 °C at least 15 min, preferably 3 h, more preferably at least 24 h.

[0116] In one embodiment the molded fiber product having the top barrier layer formed from the aqueous solution (c) has oil penetration time at 60 °C at least 15 min, preferably 3 h, more preferably at least 24 h.

[0117] In one embodiment the precursor structure has a basis weight between 150-600 g / m2, preferably 200-600 g / m2, more preferably between 200-500 g / m2.

[0118] In one embodiment the top barrier layer has a basis weight between 1-100 g / m2, preferably 10-50 g / m2, preferably between 15-40 g / m2.

[0119] In one embodiment the molded fiber product has an average density between 200-1500 kg / m3, preferably 400-1200 kg / m3or more preferably 600-900 kg / m3.

[0120] In one embodiment the molded fiber product comprises a top side with the top barrier layer, and a back side opposite to said top side, wherein the density of said top side is >400 kg / m3, more preferably >800 kg / m3(such as >800 kg / m3and less than 1800 kg / m3), and the density of said back side is between 2-1200 kg / m3.

[0121] EXAMPLES

[0122] Preparation of molded fiber product with top barrier layer, according to the present invention

[0123] After addition of chemicals to the first, to the second or to more aqueous suspensions all the suspensions are mixed properly under turbulent conditions before immersing a metal wire covered forming tool first into the first aqueous pulp suspension and applying a vacuum suction. The forming tool is kept immersed in the first aqueous pulp suspension under vacuum suction until targeted basis weight of a layer i.e. precursor structure is formed and then lifted up from the first aqueous pulp suspension and then free water is removed from the wet precursor structure with vacuum and optionally additionally with mechanical pressing until dryness is preferably 15-50%.

[0124] The wet precursor structure is then immersed into the second aqueous suspension and kept there under vacuum suction until targeted basis weight of a top or first barrier layer is formed on the precursor structure. The precursor structure having the top or first barrier layer on it is lifted up from the second aqueous suspension and water is removed from the wet precursor structure comprising the top or first barrier layer with vacuum and optionally additionally with mechanical pressing until dryness is preferably 15-50%.

[0125] After the immersion into the second aqueous suspension the said procedure can be repeated with a third or more aqueous suspension. The precursor structure having at least one barrier layer on it, is then hot press dried and thermoformed under vacuum suction until sufficient dryness is reached at sufficient temperature under sufficient mechanical pressure to get sufficient drying rate, density, porosity, smoothness, barrier and other properties.

[0126] Example 1 according to the present invention, using a second aqueous solution (a)

[0127] 0.01 - 0.4 % by dry weight of alkyl ketene dimer (AKD) is first added to a first aqueous pulp suspension having 0.1 - 2.0 % consistency, pH 7.5 and conductivity 0.5 mS / cm adjusted with calcium acetate (70%) + sodium sulfate (20%) + NaHCO3 (10%) mixture and made from 100% birch kraft pulp having Schopper Riegler (SR) value of 20-30. Then 0.005 - 0.05 % by dry weight of cationic polyacrylamide (CPAM) is added to the first aqueous pulp.

[0128] 0.5 - 1.5 % by dry weight of alkyl ketene dimer (AKD) is first added to a second aqueous suspension having 0.02 - 0.1 % consistency made from 100% bleached hardwood kraft pulp having Schopper Riegler (SR) value about 120 based on calculation from the SR valuerefining time curve of the pulp.

[0129] After addition of the said chemicals to the first aqueous pulp suspension and to the second aqueous suspension both suspensions are mixed for at least 5 minutes under turbulent conditions before immersing a metal wire covered forming tool first into the first aqueous pulp suspension. The forming tool was kept immersed in the first aqueous pulp suspension under vacuum suction until 300-400 g / m2 (on dry basis) layer i.e. precursor structure was formed with vacuum suction and then lifted up from the first aqueous pulp suspension and then free water was removed from the wet precursor structure with vacuum until dryness was 15-25%.

[0130] The wet precursor structure was then immersed into the second aqueous suspension and kept there under vacuum suction until a 20-30 g / m2 (on dry basis) top barrier layer structure was formed on the precursor structure. The precursor structure having the top barrier layer on it was lifted up from the second aqueous suspension and water was removed from the two layer wet structure with vacuum until dryness was 15-25%. The two-layer structure was then hot press dried and thermoformed above 95% dryness and 700-800 kg / m3 density at 170-190 °C temperature. Oil, grease and water barrier properties were measured from the hot press dried and thermoformed structure (Figure 1).

[0131] Example 2, according to the present invention, using a second aqueous solution (b)

[0132] 0.01 - 0.4 % by dry weight of alkyl ketene dimer (AKD) is first added to a first aqueous pulp suspension having 0.1 - 2.0 % consistency, pH 7.5 and conductivity 0.5 mS / cm adjusted with calcium acetate (70%) + sodium sulfate (20%) + NaHCO3 (10%) mixture and made from 100% birch kraft pulp having Schopper Riegler (SR) value of 20-30. Then 0.005 - 0.05 % by dry weight of cationic polyacrylamide (CPAM) is added to the first aqueous pulp.

[0133] 0.1-5.0% by dry weight of polyhydroxyalkanoate (PHA) is first added to a second aqueous suspension having 0.01 - 0.5 % consistency made from 100% bleached hardwood kraft pulp having Schopper Riegler (SR) value about 120 based on calculation from the SR value - refining time curve of the pulp. Then 0.01 - 2.0 % by dry weight of alkyl ketene dimer (AKD) is added to the second aqueous suspension.

[0134] After addition of the said chemicals to the first aqueous pulp suspension and to the second aqueous suspension both suspensions are mixed for at least 5 minutes under turbulent conditions before immersing a metal wire covered forming tool first into the first aqueous pulp suspension. The forming tool was kept immersed in the first aqueous pulp suspension under vacuum suction until 300-400 g / m2 (on dry basis) layer i.e. precursor structure was formed with vacuum suction and then lifted up from the first aqueous pulp suspension and then free water was removed from the wet precursor structure with vacuum until dryness was 15-25%.

[0135] The wet precursor structure was then immersed into the second aqueous suspension and kept there under vacuum suction until a 20-30 g / m2 (on dry basis) top barrier layer structure was formed on the precursor structure. The precursor structure having the top barrier layer on it was lifted up from the second aqueous suspension and water was removed from the two-layer wet structure with vacuum until dryness was 15-25%. The two-layer structure was then hot press dried and thermoformed above 95% dryness and 700-800 kg / m3 density at 170-190 °C temperature. Oil, grease and water barrier properties were measured from the hot press dried and thermoformed structure (Figure 1).

[0136] Example 3, according to the present invention, using a second aqueous solution (a)

[0137] 0.01 - 0.4 % by dry weight of alkyl ketene dimer (AKD) is first added to a first aqueous pulp suspension having 0.1 - 2.0 % consistency, pH 7.5 and conductivity 0.2 mS / cm adjusted with NaHCO3 and made from mixture of hardwood + softwood (70+30%) bleached kraft pulps having Schopper Riegler (SR) value of 20-30. Then 0.005 - 0.05 % by dry weight of cationic polyacrylamide (CPAM) is added to the first aqueous pulp.

[0138] 0.1-5.0% by dry weight of carboxymethylated cellulose (CMC) is first added to a second aqueous suspension having 0.01 - 0.5 % consistency made from 1 / 3 + 2 / 3 mixture of bleached hardwood kraft pulps having Schopper Riegler (SR) values of 90 and 120 respectively. The 120 SR value was based on calculation from the SR value - refining time curve of the pulp. Then 0.01 - 2.0 % by dry weight of alkyl ketene dimer (AKD) is added to the second aqueous suspension. Addition order of the CMC and the AKD to the second aqueous pulp suspension was made also so that the AKD was added before the CMC.

[0139] After addition of the said chemicals to the first aqueous pulp suspension and to the second aqueous suspension both suspensions are mixed for at least 5 minutes under turbulent conditions before immersing a metal wire covered forming tool first into the first aqueous pulp suspension. The forming tool was kept immersed in the first aqueous pulp suspension under vacuum suction until 300-400 g / m2 (on dry basis) layer i.e. precursor structure was formed with vacuum suction and then lifted up from the first aqueous pulp suspension and then free water was removed from the wet precursor structure with vacuum until dryness was 15-25%.

[0140] The wet precursor structure was then immersed into the second aqueous suspension and kept there under vacuum suction until a 20-30 g / m2 (on dry basis) top barrier layer structure was formed on the precursor structure. The precursor structure having the top barrier layer on it was lifted up from the second aqueous suspension and water was removed from the two layer wet structure with vacuum until dryness was 15-25%. The two-layer structure was then hot press dried and thermoformed above 95% dryness and 700-800 kg / m3 density at 170-190 °C temperature. Oil, grease and water barrier properties were measured from the hot press dried and thermoformed structure (Figure 2).

[0141] Oil and grease resistance test

[0142] 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.

[0143] Figure 1 shows that the hot press dried and thermoformed molded fiber structure comprising AKD and PHA in the top barrier layer (option (b)) exhibits significantly increased oil resistance compared to top barrier layer having CMC and (option (a)) and to top barrier layer having only AKD.

[0144] Figure 2 shows that adding AKD after CMC instead of vice versa to the second aqueous suspension gave surprisingly higher oil penetration time. Figure 2 also shows that having mixture of bleached hardwood and softwood in the precursor structure and / or having 1 / 3 + 2 / 3 mixture of bleached hardwood pulps with SR 90 and SR 120 respectively in the top barrier layer can give significantly higher level of oil penetration time and grease barrier (KIT value).

[0145] Example 4, according to the present invention, preparation of layered structure

[0146] A structure having two layers was produced from a first sheet and a second sheet. The first sheet was produced from the first aqueous pulp suspension, and the second sheet was produced from the second aqueous suspension (b) or (c).

[0147] Pulp of the first aqueous pulp suspension was composed of 70 / 30 mixture of SR 24-26 bleached hardwood kraft pulp / bleached softwood kraft pulp. The pulp had 0.4% consistency, pH was adjusted to 7.5 and conductivity to 0.5 mS / cm.

[0148] Pulp of the second aqueous suspension was composed of SR 100 bleached hardwood kraft pulp. The pulp had 0.04% consistency, pH was adjusted to 7.5 and conductivity to 0.5 mS / cm.

[0149] Table 1 shows the chemicals used in preparation of the first and second sheets. Table 1. Chemicals.

[0150] In Tests 1 and 2 the top layer (second sheet) is produced from second aqueous suspension

[0151] (b). In Tests 3-6 the top layer (second sheet) is produced from second aqueous suspension

[0152] (c). The acrylic dispersion 1 and acrylic dispersion 2 comprise different acrylic polymers. The different acrylic polymers are produced by polymerizing different acrylate monomers.

[0153] Rapid Kothen (RK) sheet former was used for forming the sheets, and modified Lorentzen & Wettre (L&W) press was used for wet pressing and hot pressing the sheets.

[0154] Preparation of the second sheet (top layer) First PHA or acrylic dispersion and AKD were added to the second aqueous suspension and mixed for 90 s after each addition. Then the pulp was poured into the RK sheet former column, which had a fabric wire at the bottom. After forming, the first sheet was lifted off the sheet former column with the fabric wire still attached, and moved to the side. Grammage of the second sheet was 28 gsm. Preparation of the first sheet (base layer)

[0155] First, AKD and retention chemical were added to the first aqueous pulp suspension, and mixed for 90 s after each addition. Then the pulp was poured into the RK sheet former column, that had the standard wire at the bottom. First sheet grammage was 350 gsm. Preparation of layered structure

[0156] The second sheet was carefully placed on top of the first sheet to form layered structure in the RK sheet former column. Then the RK couch roll was used to roll once over the wet layered structure to improve adhesion. Then a manual suck off stage was performed in the RK sheet former for 45 s to ensure proper dewatering, and to further enhance the adhesion of the two sheets.

[0157] After the dewatering was pressing stage, first wet pressing and then hot pressing. For wet pressing, the layered structure was placed on top of 3 blotting papers, top side towards the blotting papers. A silicone mat was placed on top of the layered structure. Then heat- resistant plates were placed at the top and bottom of the layered structure, and the layered structure was pressed at 4 bars for 5 seconds. For hot pressing, the layered structure was put into 185°C hot press and pressed at 4 bars until it was completely dry.

[0158] Cobb15 min, oil penetration, TLC oil and KIT tests

[0159] Cobb15 min, oil penetration, TLC oil and KIT tests were made for the prepared layered structures having base layer (first sheet) and top layer (second sheet). Table 2 shows the test results.

[0160] Cobb15 min test was done according to ISO 535 / TAPPI T441 standard.

[0161] Canola oil penetration test was done according to ASTM F119-82:2015 standard.

[0162] TLC oil test was done with canola oil. The tests were carried out by using room temperature (RT) canola oil. In the test, a 2 mm layer of canola oil with the given temperature was poured on top of a sample sheet (diameter 21 mm). A rubber mould was placed on top of the sample to contain the oil used for the testing. The time it took for the oil to penetrate the sample sheet was measured.

[0163] KIT test was done according to TAPPI T559 standard. Table 2. Test results.

[0164] 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.

[0165] 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.

[0166] 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.

Claims

1. CLAIMS1 . A method for producing a molded fiber product comprising the steps of:- providing a first aqueous pulp suspension with a dry content between 0.01 and 10 wt%;- providing a forming tool having a forming surface, and immersing at least a portion of said forming surface into the first aqueous pulp suspension under applied vacuum so that said forming surface is covered with a wet layer of pulp from said first aqueous pulp suspension, said layer representing a precursor structure comprising a dry content between 10 and 99 wt%;- providing a second aqueous suspension(a) comprising refined cellulose fibers having Schopper Riegler (SR) value >95 on average basis and a sizing agent, wherein the second aqueous suspension (a) is produced by introducing the refined cellulose fibers having SR value >95 on average basis to water prior introducing the sizing agent to the water;(b) comprising refined cellulose fibers having SR value >95 on average basis, sizing agent and polyhydroxy alkanoate (PHA), wherein the second aqueous suspension (b) is produced by introducing the refined cellulosic fibers having SR value >95 on average basis, the PHA and the sizing agent to water, or(c) comprising refined cellulose fibers having SR value >95 on average basis, sizing agent and acrylate dispersion, wherein the second aqueous suspension (c) is produced by introducing the refined cellulosic fibers having SR value >95 on average basis, the acrylate dispersion and the sizing agent to water;- immersing the precursor structure into the second aqueous suspension (a), (b) or (c) under applied vacuum so that a top barrier layer is formed on at least a portion of said precursor structure, or- applying, by another method than immersing the precursor structure into the second aqueous suspension (a), (b) or (c), the second aqueous suspension (a), (b) or (c) on at least a portion of said precursor structure so that a top barrier layer is formed; and- dewatering and / or drying said precursor structure comprising the top barrier layer under temperature >100°C to a dry content of >85 wt% to achieve the molded fiber product.

2. The method according to claim 1 , wherein the refined cellulose fibers comprise nanofibrillated cellulose (NFC), microfibrillated cellulose (MFC), non-wood microfibrillated cellulose, cellulose fiber, cellulose fiber fines, modified cellulose, such as carboxy methyl cellulose (CMC) or a mixture thereof.

3. The method according to claim 1 or 2, wherein the refined cellulose fibers have SR value more than 95 but less than 130 on average basis, preferably SR value more than 100 but less than 130 on average basis.

4. The method according to any one of claims 1-3, wherein the first aqueous pulp suspension comprises a sizing agent.

5. The method according to any one of claims 1-4, wherein the first aqueous pulp suspension and / or the second aqueous suspension (a), (b) and (c) comprise a retention agent, a dewatering enhancing agent, a formation enhancing agent, a barrier enhancing agent, a strength enhancing agent, a coatability enhancing agent or a combination thereof.

6. The method according to any one of claims 1-5, wherein the concentration of the sizing agent in the first aqueous pulp suspension is between 0.1-50 kg / tn, based on the dry content of the wet layer and the concentration of the sizing agent in the second aqueous suspension (a),(b) or (c) is between 0.1-50 kg / tn, based on the dry content of the top barrier layer.

7. The method according to any one of claims 1-6, wherein concentration of the PHA in the second aqueous suspension (b) is between 0.1-300kg / tn, based on the dry content of the top barrier layer.

8. The method according to any one of claims 1-7, wherein concentration of the acrylic dispersion in the second aqueous suspension (c) is between 0.1-300kg / tn, based on the dry content of the top barrier layer.

9. The method according to any one of claims 1-8, wherein the first aqueous pulp suspension comprises a wet strength agent at a concentration between 1-100 kg / tn, based on the dry content of the wet layer and the second aqueous suspension (a),(b) and (c)comprise a wet strength agent at a concentration between 1-100 kg / tn, based on the dry content of the top barrier layer.

10. The method according to claim 9, wherein the wet strength agent comprises polyamide epichlorohydrin, polyethylene imine, dialdehyde starch, polyacryl amides, glyoxal or melamine formaldehyde, urea formaldehyde melamine or a combination thereof.

11. The method according to any one of claims 1-10, wherein the applying, by another method than immersing the precursor structure into the second aqueous suspension (a), (b) or (c), comprises_spray coating, dip coating, flow coating, curtain coating, pad coating, laminating, rod coating, blade coating, flexographic coating, gravure coating, air-knife coating or a combination thereof.

12. The method according to any one of claims 1-6, wherein at least two layers are made from the second aqueous suspension (a), (b) or (c).

13. The method according to any one of claims 1-12, wherein at least one layer is made by means of the vacuum-assisted suction from an aqueous suspension comprising barrier components or by applying, by other method than by means of the vacuum-assisted suction, an aqueous suspension comprising barrier components, to form a water barrier, gas barrier layer and / or vapour barrier layer.

14. The method according to any one of claims 1-13, wherein the dewatering of said molded precursor structure is performed as a one-sided dewatering.

15. The method according to any one of claims 1-14, wherein drying of said molded structure is performed as unrestrained or restrained by drying in oven, between hot press molds and / or between thermoforming molds or a combination thereof.

16. A molded fiber product comprising at least a first layer and a second top barrier layer, said product being produced by means of a method comprising the steps of:- providing a first aqueous pulp suspension with a dry content between 0.01 and 10 wt%;- providing a forming tool having a forming surface, and immersing at least a portion of said forming surface into the first aqueous pulp suspension under applied vacuum so that said forming surface is covered with a wet layer of pulp from said first aqueous pulp suspension,said layer representing a precursor structure comprising a dry content between 10 and 99 wt%;- providing a second aqueous suspension(a) comprising refined cellulose fibers having Schopper Riegler (SR) value >95 on average basis and a sizing agent, wherein the second aqueous suspension (a) is produced by introducing the refined cellulose fibers having SR value >95 on average basis to water prior introducing the sizing agent to the water,(b) comprising refined cellulose fibers having SR value >95 on average basis, sizing agent and polyhydroxy alkanoate (PHA), wherein the second aqueous suspension (b) is produced by introducing the refined cellulosic fibers having SR value >95 on average basis, the PHA and the sizing agent to water, or(c) comprising refined cellulose fibers having SR value >95 on average basis, sizing agent and acrylate dispersion, wherein the second aqueous suspension (c) is produced by introducing the refined cellulosic fibers having SR value >95 on average basis, the acrylate dispersion and the sizing agent to water;- immersing the precursor structure into the second aqueous suspension (a), (b) or (c) under applied vacuum so that a top barrier layer is formed on at least a portion of said precursor structure, or- applying, by another method than immersing the precursor structure into the second aqueous suspension (a), (b) or (c), the second aqueous suspension (a), (b) or (c) on at least a portion of said precursor structure so that a top barrier layer is formed; and- dewatering and / or drying said precursor structure comprising the top barrier layer under temperature >100°C to a dry content of >85 wt% to achieve the molded fiber product.

17. The molded fiber product according to claim 16, wherein the refined cellulose fibers comprise nanofibrillated cellulose (NFC), microfibri Hated cellulose (MFC), vegetable microfibrillated cellulose (vMFC), cellulose fiber fines, modified cellulose, such as carboxy methyl cellulose (CMC) or a mixture thereof.

18. The molded fiber product according to claim 16 or 17, wherein the refined cellulose fibers have SR value more than 95 but less than 130 on average basis, preferably SR value more than 100 but less than 130.

19. The molded fiber product according to any one of claims 16-18, wherein the first aqueous pulp suspension comprises a sizing agent.

20. The molded fiber product according to any one of claims 16-19, wherein the first aqueous pulp suspension and / or the second aqueous suspension (a), (b) or (c) comprise a retention agent, a dewatering enhancing agent, a formation enhancing agent, a barrier enhancing agent, a strength enhancing agent, a coatability enhancing agent or a combination thereof.

21. The molded fiber product according to any one of claims 16-20, wherein the concentration of the sizing agent in the first aqueous pulp suspension is between 0.1-50 kg / tn, based on the dry content of the wet layer and the concentration of the sizing agent in the second aqueous suspension (a),(b) and (c) is between 0.1-50 kg / tn, based on the dry content of the top barrier layer.

22. The molded fiber product according to any one of claims 16-20 wherein concentration of the PHA in the second aqueous suspension (b) is between 0.1-300kg / tn, based on the dry content of the top barrier layer.

23. The molded fiber product according to any one of claims 16-22 wherein concentration of the acrylic dispersion in the second aqueous suspension (c) is between 0.1-300kg / tn, based on the dry content of the top barrier layer.

24. The molded fiber product according to any one of claims 16-23, wherein the molded fiber product having the top barrier layer formed from the aqueous solution (a)has oil penetration time at 60 °C at least 10min.

25. The molded fiber product according to any one of claims 16-24, wherein the first aqueous pulp suspension comprises a wet strength agent at a concentration between 1- 100 kg / tn, based on the dry content of the wet layer and / or the second aqueous suspension (a),(b) and (c) comprise a wet strength agent at a concentration between 1-100 kg / tn, based on the dry content of the top barrier layer.

26. The molded fiber product according to claim 25, wherein the wet strength agent comprises polyamide epichlorohydrin, polyethylene imine, dialdehyde starch, polyacryl amides, glyoxal or melamine formaldehyde, urea formaldehyde melamine or a combination thereof.

27. The molded fiber product according to any one of claims 16- 26, wherein the applying, by another method than immersing the precursor structure into the second aqueous suspension (a), (b) or (c), comprises spray coating, dip coating, flow coating, curtain coating, pad coating, laminating, rod coating, blade coating, flexographic coating, gravure coating, air-knife coating or a combination thereof.

28. The molded fiber product according to any one of claims 16-27, wherein at least two layers are made from the second aqueous suspension (a), (b) or (c).

29. The molded fiber product according to any one of claims 16-28, wherein at least one layer is made by means of the vacuum-assisted suction from an aqueous suspension comprising barrier components or by applying, by other method than by means of the vacuum-assisted suction, an aqueous suspension comprising barrier components, to form a water barrier, gas barrier layer and / or vapour barrier layer.

30. The molded fiber product according to any one of claims 16-29, wherein the dewatering of said molded precursor structure is performed as a one-sided dewatering.

31. The molded fiber product according to any one of claims 16-30, wherein drying of said molded structure is performed as unrestrained or restrained by drying in oven, between hot press molds and / or between thermoforming molds or a combination thereof.

32. The molded fiber product according to any one of claims 16-31 , wherein the molded fiber product having the top barrier layer formed from the aqueous solution (b) has oil penetration time at 60 °C at least 15 min.

33. The molded fiber product according to any one of claims 16-32, wherein the molded fiber product having the top barrier layer formed from the aqueous solution (c) has oil penetration time at 60 °C at least 15 min.

34. The molded fiber product according to any one of claims 16-33 wherein the precursor structure has a basis weight between 150-600 g / m2.

35. The molded fiber product according to any one of claims 16-34, wherein the top barrier layer has a basis weight between 1-100 g / m2.

36. The molded fiber product according to any one of claims 16-35, wherein the molded fiber product has an average density between 200-1500 kg / m3.

37. The molded fiber product according to any one of claims 16-36 comprising a top side with the top barrier layer, and a back side opposite to said top side, wherein the density of said top side is >400 kg / m3, more preferably >800 kg / m3and the density of said back side is between 2-1200 kg / m3.

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