Polymer coated paper and paperboard

Abstract

The present invention relates to a paper or paperboard comprising at least one biodegradable coating layer and a first polymer coating layer formed by extrusion coating of a furandicarboxylic acid (FDCA) based resin onto the least one biodegradable coating layer characterized in that the FDCA based resin comprises at least 50 % by weight of a FDCA based polymer and the biodegradable coating layer comprises at least 30 % by weight of a compostable polymer. The invention also relates to a 3D formed package and a method for coating said paper or paperboard.

Description

[0001] POLYMER COATED PAPER AND PAPERBOARD

[0002] Technical field

[0003] The present disclosure relates to polymer coated paper and paperboard suitable for containers and 3D forming of packages, such as trays. More specifically, the present disclosure relates to paper or paperboard comprising at least one biodegradable coating layer and at least one coating layer formed by extrusion coating of a FDCA based resin.

[0004] Coating of paper or paperboard with polymer is often done to combine the mechanical properties of the paperboard with the barrier and sealing properties of a polymer film. Paperboard provided with even a relatively small amount of a suitable polymer material can provide the properties needed to make the paperboard suitable for many demanding applications.

[0005] Paper or paperboard as such is generally suitable for the packaging of dry food products. However, untreated paperboard is of limited use in direct contact with moist or greasy products, because moisture will affect the mechanical properties of the packaging and absorbed oil or grease will cause staining of the paper or paperboard. These effects will impair the protective function as well as the appearance of the packaging.

[0006] Extrusion coating or lamination drastically expands the range applications for paper or paperboard. The thin polymer coating imparts resistance to liquids, grease and moisture and also in some instances heat resistance. The polymer coatings can also be used for heat sealing. Depending on the application, the paper or paperboard may be extrusion coated on one or both sides.

[0007] Extrusion coating is a process by which a molten polymer material is applied to a substrate, such as paper or paperboard to form a very thin, smooth and uniform coating layer. The coating can be formed by the extruded polymer itself, or the molten polymer can be used as an adhesive to laminate a solid polymer film onto the substrate. Common polymer resins used in extrusion coating include polyethylene (PE), polypropylene (PP), and polyethylene terephthalate (PET). A big disadvantage with these polymers, such as PE and PET that they are a petrol-based polymer and their production and disposal have negative environmental impacts. There is therefore a need to find more sustainable polymers when making polymer coated paper or paperboard.

[0008] Polyethylene terephthalate (PET) has many interesting properties and multiply uses such as frozen food and heated food products including both microwave oven and oven. Despite its thermal stability, the PET polymer might lose barrier properties when exposed to heat and moisture, due to for example chain relaxation but also due to hydrolysis.

[0009] Thus, polyethylene terephthalate (PET) may show hydrolytic degradation under high temperature and moist conditions, which leads to reduced barrier properties and mechanical properties.

[0010] Furandicarboxylic acid (FDCA) based polymers are a more sustainable polymer option since these are derived from renewable sources, such as vegetable or plantbased feedstocks like wood, sugarcane, sugar beet, or other agricultural crops or residues. These are then converted to saccharides such as fructose or glucose and then to intermediates before obtaining the FDCA. This bio-based origin of FDCA based polymers makes it more environmentally friendly.

[0011] One challenge with the use of FDCA based polymers, such as polyethylene furanoate (PEF), as a coating layer, is to have sufficient adhesion between the polymer layer and the paper or paperboard. Also, there is a need for the FDCA based polymer to have good dimensional stability to make it stable also after heating.

[0012] Also, there is a need to find a base paper or paperboard structure with pre-formed barrier properties and that facility circularity. Extrusion of FDCA based polymer may involve risks of blistering or evaporating moisture from the base board, which hence leads to non-uniform moisture distribution and development of curl. Application of high amount of FDCA based may also promote the development of curl or dimensional stability problem. One solution to avoid such as problem with de-moisturizing (evaporating) the base board due to the high temperature is to use glue lamination. Application of wet glue may, on the other hand, lead to encapsulated water in the laminate which then cause problem with adhesion and delamination.

[0013] 3D forming, such as thermoforming, of paper or paperboard products is a growing market since it is a more sustainable packaging solution. Thermoforming involves heating the paperboard to make it possible the shape it into a specific form, such as a tray. It is important that the paper or paperboard product being 3D formed maintains its structural form after the forming process, especially in high humidity environments. It is also important that the paper or paperboard is provided with good barrier properties to make it suitable for packaging of food or personal care packages

[0014] There is thus a need to find a more sustainable polymer coating that would provide the coated paper or paperboard with good barrier properties, especially good grease resistance and aroma barrier and dimensional stability even if the fiber amount of the paper or paperboard is reduced, to make it suitable for 3D forming of packages.

[0015] Description of the invention

[0016] It is an object of the present disclosure to provide a paper or paperboard coated with FDCA based resin having good barrier properties, especially grease and aroma barrier properties.

[0017] It is a further object of the present disclosure to provide a paper or paperboard coated with FDCA based resin having good adhesion to the paper or paperboard or other coating layers.

[0018] It is a further object of the present disclosure to provide a coated paper or paperboard that is compostable.

[0019] It is a further object of the present disclosure to provide a coated paper or paperboard that is more sustainable. It is a further object of the present disclosure to provide a paper or paperboard suitable for making 3D formed packages, such as paperboard trays, tubes, plates or cups.

[0020] Another object of the present disclosure to provide a method for manufacturing of a polymer coated paper or paperboard, which is compostable and having good barrier properties.

[0021] The above mentioned objects, as well as other objects as will be realized by the skilled person in the light of the present disclosure are achieved by the various aspects of the present disclosure.

[0022] According to a first aspect illustrated herein, there is provided a paper or paperboard comprising at least one biodegradable coating layer and a first polymer coating layer formed by extrusion coating of a furandicarboxylic acid (FDCA) based resin onto at least one of said biodegradable coating layer characterized in that the FDCA based resin comprises at least 50 % by weight of a FDCA based polymer and the biodegradable coating comprises at least 30 % by weight of a compostable polymer.

[0023] It has been found that the combination of a first coating layer comprising at least 50 % by weight of a FDCA based polymer and a biodegradable coating layer comprising at least 30 % by weight of a compostable polymer makes it possible to produce a coated paper or paperboard having very good barrier properties and that also is compostable. With compostable is means that it is home and / or industrially compostable according to EN 13432:2000, ASTM D6868-21 and / or AS-4736-2006. Furthermore, the combination of the first FDCA based coating layer and the biodegradable coating layer has been found to prevent curl of the coated paper or paperboard.

[0024] In some embodiments, the biodegradable coating layer comprises a compostable polymer in an amount of 30-100 weight%, preferably in an amount of 50-90 weight%, and more preferably in an amount of 60-90 weight%, based on the total dry weight of the biodegradable coating layer. The compostable polymer may be polyhydroxyalkanoate (PHA), polybutylene succinate (PBS), polylactic acid (PLA), polybutylene adiapate terephthalate (PBAT) and / or polysaccharide derivatives. The PHA may be selected from the group consisting of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), poly(3- hydroxybutyrate-co-3-hydroxyhexanoate) ( P H B H ) , poly(3-hydroxybutyrate-co-4- hydroxybutyrate) (P3HB4HB), poly(3-hydroxyoctanoate-co-3-hydroxyhexanoate) (PHOHH), poly(3-hydroxyoctanoate-co-3-hydroxydecanoate) (PHOHD), and poly(3- hydroxyoctanoate-co-3-hydroxydodecanoate) (PHDHDD), or a mixture thereof. The polysaccharide derivatives are preferably a ester such as starch acetate, cellulose acetate, starch phosphate, starch succinate, starch laurate, cellulose acetate butyrate and / or cellulose propionate.

[0025] Another advantage with the biodegradable coating layer is that it will prevent dehydration of the paper or paperboard during extrusion coating of the FDCA based resin. The paper or paperboard coated with the biodegradable coating preferably has a water vapor barrier less than 200 g / m2 / day at 23 °C / 50% RH measured according to ASTM D1249-21 . It is important that the biodegradable coated paper or paperboard has relative good water vapor barrier properties so that the paper or paperboard will have a certain moisture content to ensure that it keeps the stretchability during future converting processes.

[0026] In some embodiments, the biodegradable coating layer has a grammage in the range of 0.3-10 gsm, preferably in the range of 0.3-8 gsm, and more preferably in the range of 0.5-5 gsm. It has been found that it is sufficient with a low amount of biodegradable coating layer and still be able to provide the paper or paperboard with good barrier properties. The biodegradable coating layer can be applied in one or more layers.

[0027] The biodegradable coating layer may further comprise between 5-70 % by weight of a pigment, preferably between 10-60 % by weight or even more preferred between 15-45 % by weight. The pigment is preferably a high reflective pigment such as calcined clay, precipitated calcium carbonate (PCC), ground calcium carbonate (GCC) and / or titanium dioxide. The addition of a pigment to the biodegradable coating layer will improve the light barrier properties of the biodegradable coating layer and thus also on the coated paper or paperboard. Furthermore, the addition of a pigment will reduce the total cost, since less compostable polymer is needed and the drying of the coated paper or paperboard can be more efficient.

[0028] There might be an adhesion layer located between the biodegradable coating and the FDC based coating to improve the adhesion between the two layers. The adhesive may be a FDCA based or biodegradable based polymer derivative.

[0029] The FDCA based resin of the invention comprises at least 50 % by weight of the FDCA based polymer. In some embodiments, the FDCA based resin comprises at least 70 % by weight, preferably at least 90 % by weight, of the FDCA based polymer. The FDCA based resin of the invention may also consist, or substantially consist, of the FDCA based polymer. For some end use, it is preferred that the FDCA resin consists, or substantially consists, of the same FDCA polymer since such mono-material coating is easier to recycle.

[0030] The FDCA based resin may have an intrinsic viscosity of less than 0.9 dl / g, preferably between 0.5-0.9 dl / g, and even more preferred between 0.5-0.7 dl / g, as determined according to ISO 1628. It has been found that the use of a FDCA based polymer with the mentioned intrinsic viscosity will improve the bonding of the FDCA based resin to the biodegradable coating layer and the runnability of the polymer in the extruder. It is also believed that the FDCA based polymer with the lower intrinsic viscosity would be less prone to degradation compared other polymers such as PET.

[0031] The FDCA based resin may have an intrinsic viscosity of 0.9 dl / g or higher, as determined according to ISO 1628. In some embodiments, 5-50% by weight of the FDCA based resin is comprised of a FDCA based polymer having an intrinsic viscosity 0.9-1 .2 dl / g, as determined according to ISO 1628. It can be an advantage to use a mixture of FDCA based polymers having different intrinsic viscosity. FDCA based polymers with a higher intrinsic viscosity will contribute to improved mechanical and barrier properties of the polymer coating.

[0032] The FDCA based polymer preferably has a melting temperature above 210 °C, preferably above 225 °C, the melting temperature is preferably between 220-270 °C and even more preferred between 225-255 °C. The melting temperature is determined by differential scanning calorimetry according to standard ASTM D3418- 21. In order for the coated paper or paperboard to be suitable for food packaging it needs to be heat treated, e.g. by retorting, autoclaving or sterilization. It is therefore necessary for the FDCA based polymer to be stable after being subjected to such heat treatment to be able to be used in packaging products. With stable is meant that the FDCA based polymer both is mechanically stable and having maintained barrier properties even after heat treatment. The barrier properties, such as grease barrier, water vapor transmission rate and oxygen transmission rate should be at a good value, i.e. not deviating more than 20% from the original value, preferably not more than 15% from the original value, at least 2 weeks after heat treatment, preferably after 4 weeks. The high melting temperature is thus important to be able to use the coated paperboard in ovenable products, such as ovenable or micro-ovenable trays. However, a drawback with the high melting temperature is that the adhesion properties of the polymer is reduced and that a higher extrusion temperature is needed.

[0033] The FDCA based polymer preferably has a crystallinity of between 5-40%, preferably between 10-35% and even more preferred between 15-25%. Crystallinity is measured according to ASTM E794-06 (2018). Low crystallinity is preferred since it will improve heat sealability sealability such as heat or ultrasonic properties and adhesion of the FDCA based polymer. Also, the stability, stretchabilty and barrier properties has also been found to improve for FDCA based polymers having a lower crystallinity.

[0034] The formulation of a resin used for coating may vary greatly depending on the intended use of the coated paper or paperboard. The FDCA based resin may include a wide range of ingredients in varying quantities to improve the end performance of the product or processing of the coating. The FDCA based resin can comprise other polymeric or non-polymeric coating components. In other words, the FDCA based resin can be a blend of the FDCA based polymer and another polymer. The FDCA based resin preferably comprises at least one additional component selected from the group consisting of a polymer other than a FDCA based polymer, a colorant, (e.g. Titanium dioxide or carbon black), a dye, a filler or a pigment (e.g. CaCOsor talc). The FDCA based resin my also comprise other additives such as lubricants, slip agents, plasticizers, antioxidants and / or UV stabilizers.

[0035] The term coating, as used herein, refers to an operation in which the surface of a substrate is covered with a composition to impart a desired properties, finish or texture to the substrate. The coating can be applied to one side or both sides of the paper or paperboard. The coating may be added by extrusion coating or lamination. In some embodiments the first coating layer is the only coating layer applied to the paper or paperboard. In some embodiments the first coating layer is a single coating layer. In some embodiments the first coating layer is a multiply coating layer. The first coating layer is preferably located on the inside on a package formed from the coated paper or paperboard.

[0036] The paper or paperboard may also comprise at least one second coating layer disposed on top of the first coating layer. It may be preferred to add more than one coating layer on the paper or paperboard to form a multilayer coating. The second coating layer can have the same composition as the first coating layer. As the FDCA based coating layer provides good stability of the film formation and adhesion of the FDCA based resin to the paper or paperboard, it may preferably be used as the first (or innermost) coating layer applied directly onto the paper or paperboard surface. The extrusion coated FDCA based coating layer may serve to promote adhesion of subsequently applied or coextruded polymeric coating layers. The extrusion coated FDCA based coating layer may serve as an adhesive for a polymeric film in an extrusion film lamination process.

[0037] In some embodiments, the paper or paperboard extrusion coated with the FDCA based resin, further comprises a second coating layer disposed on top of the first coating layer, wherein the second coating layer has a composition that is different from the first coating layer.

[0038] It may be preferred that the second coating layer has a different composition than the first coating layer. The second coating layer preferably comprises a FDCA based polymer, polyethylene terephthalate (PET), polyethylene (PE), polypropylene (PP) and / or polylactic acid (PLA). In a preferred embodiment, the at least one additional coating layer comprises a FDCA based resin, preferably polyethylene furanoate (PEF).

[0039] In some embodiments, the at least one additional coating layer is formed by extrusion coating or by extrusion film lamination.

[0040] The first and eventual second coating layer / s are preferably applied to the paper or paperboard at a combined grammage of less than 60 gsm, preferably less than 50 gsm, more preferably less than 40 gsm. It may be preferred that the first and eventual second coating layer / s is applied in an amount of 10-60 gsm, preferably between 15-50 gsm and even more preferred between 20-40 gsm. It has been found that it is possible to add small amount of coating layer / s and still be able to achieve sufficient adhesion and stability of the film.

[0041] The paper or paperboard may also comprise at least one additional coating layer added to the opposite side on the paper or paperboard from the biodegradable coating layer. The additional coating layer is preferably located on the outside on a package formed from the coated paper or paperboard. The additional coating layer may comprise a biodegradable coating layer, a FDCA based polymer, polyethylene terephthalate (PET), polyethylene (PE), polypropylene (PP) and / or polylactic acid (PLA). It may be preferred to make a symmetrical paper or paperboard product, having the same coating layers on both side of the paper or paperboard, i.e. both a biodegradable coating layer and a FDCA based coating layer on both sides of the paper or paperboard substrate.

[0042] Paper generally refers to a material manufactured in sheets or rolls from the pulp of wood or other fibrous substances comprising cellulose fibers, used for e.g. writing, drawing, or printing on, or as packaging material. Paper can either be bleached or unbleached and produced in a variety of thicknesses, depending on the end-use requirements.

[0043] Paperboard generally refers to strong, thick paper or cardboard comprising cellulose fibers used for example as flat substrates, trays, boxes and / or other types of packaging. Paperboard can either be bleached or unbleached and produced in a variety of thicknesses, depending on the end-use requirements.

[0044] The paper or paperboard according to the present disclosure is preferably a multiply paperboard product comprising at least two cellulose based plies, preferably at least three cellulose plies. Each of the cellulose based plies can have a certain composition of pulp fibers, such as bleached and / or unbleached Kraft pulp, sulfite pulp, dissolving pulp, thermomechanical pulp (TMP), chemi-thermomechanical pulp (CTMP), high-temperature CTMP (HT-CTMP), broke, and / or mixtures thereof. The chemimechanical pulps such as CTMP or HT-CTMP may also be bleached or unbleached. The paper or paperboard preferably comprises at least 40% of chemimechanical pulp. The different plies can have different grammages and / or thicknesses and may contain different amounts of additives, such as internal sizing agents. The internal sizing agent may be, rosin resin, ASA and / or AKD. The total amount of internal sizing is preferably in the range of 0.2-5 kg / tn. Due to the high temperature in the heat treatment, e.g. autoclaving, sterilization or retorting, the internal sizing will improve the dimensional stability of the coated paper or paperboard after heat treatment.

[0045] It may be preferred that the paper or paperboard is free from optical brightening agents and per- and polyfluoroakyl substances (PFAS) since these might discolor the paper or paperboard.

[0046] The paper or paperboard may comprise recycled fibers. It is preferred that the paperboard comprises between 5-50 % by weight of recycled fibers. The paper or paperboard comprising the recycled fibers will preferably fulfill the requirements for paper and board for food contact according to BfR XXXVI as of 01 .04.2021 It is preferred that the recycled fibers are located in the midply of a multiply paperboard substrate. It may be possible that one ply of a multiply paperboard substrate comprises between 50-85 % by weight of recycled fibers. The use of at least one FDCA based coating and a biodegradable coating improves the stability and makes it possible to use a high amount of recycled fibers. In some embodiments, the grammage of the fiber-based substrate is in the range of 80-550 gsm, preferably in the range of 100-500 gsm. Unless otherwise stated, the grammage is determined according to the standard ISO 536. It has been found that by applying a FDCA based coating to the paperboard it is possible to reduce the grammage of the paperboard and still be able to provide a stable and rigid coated paperboard product that is suitable for many different packaging applications.

[0047] The paper or paperboard, prior to application of any coating layer, preferably has a stretch of at least 6% (CD) measured according to ISO1924-3, preferably above 7% and even more preferred above 8%. It has been found that the combination of a stretchable paper or paperboard with a FDCA based coating layer improves the forming properties.

[0048] The paper or paperboard preferably has a thickness above 18000pm, preferably above 200 pm, preferably between 180-800 pm measured according to ISO 534. It has been found that a high thickness of the paper or paperboard will improve the compression and contact in the extruder, which will improve the adhesion of the FDCA based coating to the paper or paperboard.

[0049] The paper or paperboard may further comprise a peeling layer located between the biodegradable coating layer and the FDCA based coating layer. The peeling layer is preferably a pressure sensitive adhesive, hot melt adhesive, water or solvent based adhesive or re-sealable adhesive. The peeling layer preferably has a grammage between 0.8-12 gsm, preferably between 1.6-8 gsm. The peeling layer will facilitate separation and recycling of the coated paper or paperboard and polymer layer, respectively. It will then be possible to remove the FDCA based coating layer. In this way it is possible to both recycle and reuse the polymer coating layer / s and the paper or paperboard substrate. The paper or paperboard with the biodegradable coating layer will still be compostable and can easily be recycled.

[0050] The paper or paperboard may also be surface sized. In some embodiments, the paper or paperboard is surface sized on one or both sides with a surface sizing composition. It is preferred that the sizing composition comprises a starch or starch derivative, a cellulose derivative, microfibri Hated cellulose, nanocrystalline cellulose, or polyvinyl alcohol (PVOH) or a combination thereof. The starch derivative may be a slightly modified starch, such as oxidized or cationized starch. The cellulose derivative may be a sodium carboxymethyl cellulose with a degree of substitution higher than 0.4 such as in the range of 0.5-1.5. The use of surface sizing will improve the surface strength of the paper or paperboard. It is preferred that the paper or paperboard has a dry pick strength of at least 1.3 m / s, preferably at least 1 .5 m / s and even more preferred at least 2.0 m / s, determined according to ISO 3783:2006. Good surface strength will reduce the risk for delamination when the FDCA based coating is applied.

[0051] In some embodiments, the grammage of the surface sizing composition is 0.2-10 gsm, preferably 0.4-8 gsm, and more preferably 0.8-5 gsm per side, based on dry weight.

[0052] The FDCA based polymer is preferably polyethylene furanoate (PEF), polybutylene furanoate (PBF), polytrimethylene furandicarboxylate (PTF), polypentamehylene furanoate (PPeF), polyheamethylene furanoate (PHF) or polypropylene furanotate (PPF). It is preferred that the FDCA based polymer is polyethylene furanoate (PEF).

[0053] The inventive paper or paperboard is useful in the manufacture of conatainers, such as tubes, trays, plates and cups. The inventive paper or paperboard is particular useful in the manufacture of 3D formed packages. 3D formed packages can be formed by thermoforming or deep drawing. According to a second aspect illustrated herein, there is provided a 3D formed package comprising paper or paperboard according to the first aspect described herein. The package may be in the form of a tray. The tray may be thermoformed or deep drawn into a tray. The tray can be used for packaging dry, wet or semidry food products such as ready meals for heating in oven or micro-oven. The 3D formed package may also be in the form of a tube, bowl or a cup suitable for packaging e.g. soups.

[0054] The coated paper or paperboard or the 3D formed package preferably has a KIT value above 11 , preferably above 12, measured according to TAPPI T559. KIT is a value of grease resistance. It is important that the coated paper or paperboard has improved grease resistance. The coated paper or paperboard or the 3D formed package preferably also has a fat resistance above 48 hours, preferably above 56 hours, according to the modified ASTM F119-82 method evaluated at 60 °C and 0% RH. It is important that the coated paper or paperboard has a very high fat resistance which makes it suitable for packaging greasy products, such as pizza, bakery products, fresh food products, including fish and berries as well as frozen food products.

[0055] The 3D formed package preferably has an oxygen transmission rate below 50 cc / m2 / day at 23 C / 50% RH measured according to ASTM F1927-20, preferably below 20 cc / m2 / day at 23 C / 50% RH. It is important that the oxygen transmission rate value is stable also after heat treatment, such as autoclaving, sterilization or retorting.

[0056] The 3D formed package preferably has a water vapor transmission rate (WVTR) below 20 g / m2 / day at 23 °C / 50% RH measured according to ASTM D1249-20. It is important that the VWTR value is stable also after heat treatment, such as autoclaving, sterilization or retorting.

[0057] According to a third aspect illustrated herein, there is provided a method for manufacturing a coated paper or paperboard substrate, wherein said method comprises the steps of; providing a paper or paperboard substrate, providing a biodegradable coating composition, applying said biodegradable coating composition onto at least one surface of the paper or paperboard substrate to form a biodegradable coating layer, providing a FDCA based resin, applying the FDCA based resin directly onto at least one of the biodegradable coating layer by extrusion coating to form a first coating layer, cooling the FDCA based resin, thereby forming the coated paper or paperboard substrate, wherein the FDCA based resin comprises at least 50 % by weight of a FDCA based polymer and that the biodegradable coating composition comprises at least 30 % by weight of a compostable polymer.

[0058] The biodegradable layer is preferably formed by applying the coating composition in form of a dispersion, such as water or solvent based dispersion, comprising the compostable polymer on the surface of the paper or paperboard substrate and drying the coating composition at a drying temperature in the range of 90-180 °C and / or at least 20 °C below the melting point of the biodegradable polymer. In some embodiments, the drying temperature is in the range of 95-145 °C, preferably in the range of 100-120 °C.

[0059] In some embodiments, the drying temperature is at least 30 °C below the melting point of the biodegradable polymer, preferably at least 40 °C below the melting point of the biodegradable polymer, and more preferably at least 50 °C below the melting point of the biodegradable polymer.

[0060] The biodegradable layer is preferably formed by means of a liquid film coating process, i.e. in the form of an aqueous dispersion which, on application, is spread out to a thin, uniform layer on the paper or paperboard substrate and thereafter dried.

[0061] In some embodiments, the aqueous coating composition is applied by a non-contact application method. In some embodiments, the aqueous coating composition is applied by an application method selected from the group consisting of roller coating, spray coating, curtain, blade coating, slot coating, immersion coating, gravure roll coating, reverse direct gravure coating, rod coating, soft-tip blade coating, short dwell, and soft-tip rod coating, and combinations thereof. The aqueous coating composition may be applied directly onto the fiber-based substrate or indirectly, for example via a transfer roll or belt.

[0062] In some embodiments, the drying comprises subjecting the aqueous coating composition to heating. In some embodiments, the drying comprises subjecting the aqueous coating composition to at least one non-contact drying step, such as infrared radiation, electron beam radiation, ultraviolet radiation, microwave radiation, hot air or a combination thereof. Optionally, the aqueous coating composition is then subjected to at least one additional drying step, which can be a hot air drying step or a contact drying step, e.g. using a heated belt or heated cylinders. The method may further comprise a cooling step after application of the FDC based resin. The cooling step is preferably done by the use of a chill roll. The chill roll preferably has an extended chill nip. The cooling step is preferably done at a temperature of between 5-60 °C for a time of at least 0.15 s, preferably between 0.15-10 seconds, even more preferred between 0.2-6 seconds. It may be possible to use more than one chill roll placed subsequent of each other during the cooling step. It is important to cool the extruded FDCA resin for a sufficient time, especially when extruding a FDCA based polymer, in order to achieve sufficient adhesion to the biodegradable coating layer.

[0063] The pressure used in the nip during the extrusion coating of the FDCA based resin is preferably between 30-800 kPa, preferably between 40-500 kPa and even more preferred between 50-350 kPa. By using increase pressure during extrusion coating the adhesion of the FDCA based resin can be improved.

[0064] The method may further comprise the step of applying at least one second coating layer disposed on top of the first coating layer. The at least one second coating layer may comprise a FDCA based polymer, polyethylene terephthalate (PET), polyethylene (PE), polypropylene (PP) and / or polylactic acid (PLA). In a preferred embodiment, the at least one additional coating layer comprises a FDCA based polymer, preferably polyethylene furanoate (PEF), having a composition different from the first extrusion coated FDCA based resin.

[0065] In some embodiments, the at least one additional coating layer is formed by extrusion coating or by extrusion film lamination. In a preferred embodiment, the at least one additional coating layer is formed by coextrusion coating together with the first FDCA based resin, preferably by the use of a twin extruder.

[0066] The method may further comprise the step of drying the paper or paperboard substrate to a moisture content of between 5-14 % by weight before application of the FDCA based coating, preferably between 8-11 % by weight. The moisture content is measured according to ISO 287. By reducing the moisture content of the paper or paperboard substrate it is possible to improve the adhesion of the coating layer to the biodegradable coating layer. It is also important that the surface moisture content of the paper or paperboard substrate is controlled so that it is not too low. Too low moisture content will make the paper or paperboard more brittle and not as stretchable and consequently less suitable for forming packages.

[0067] The method may further comprise the step of applying a peeling layer between the biodegradable coating layer and the first polymer coating layer. The peeling layer may be a pressure sensitive adhesive, water or solvent based adhesives and / or re- sealable adhesives. It is preferred that the peeling layer has a grammage between 0.8-12 gsm. The peeling layer will facilitate recycling of the coated paper or paperboard substrate. It will be easier to remove the FDCA based coating layer. In this way it is possible to both recycle and reuse the polymer coating layer / s and the paper or paperboard substrate. The paper or paperboard with the biodegradable coating layer will still be compostable and can easily be recycled.

[0068] The method may further comprise the step of subjecting the paper or paperboard substrate to a flame, plasma, ozone and / or corona treatment before applying the biodegradable coating layer. By treating the paper or paperboard substrate with flame, plasma, ozone and / or corona treatment the surface energy of the paper or paperboard substrate is increased. Also, the flame, plasma, ozone and / or corona treatment will remove impurities from the surface of the paper or paperboard substrate. Increased surface energy and removal of impurities will affect the bonding properties in a positive way.

[0069] The FDCA based resin of the third aspect may be further defined as set out above with reference to the first aspect.

[0070] Unless otherwise stated, the unit “% by weight” mentioned in the present disclosure refers to % by weight of the total dry weight of the relevant layer, composition, resin or the like.

[0071] Description of the figure

[0072] Figure 1 describes an example of a paperboard (1 ) according to the present invention. The paperboard (1 ) comprises a biodegradable coating layer (3), two coating layers of FDCA based resin (2, 2) and a peeling layer (4) located between the biodegradable layer (3) and the FDCA based layer.

[0073] While the invention has been described with reference to various exemplary embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims.

Claims

CLAIMS1 . Paper or paperboard comprising at least one biodegradable coating layer and a first polymer coating layer formed by extrusion coating of a furandicarboxylic acid (FDCA) based resin onto the biodegradable coating layer characterized in that the FDCA based resin comprises at least 50 % by weight of a FDCA based polymer and that the biodegradable coating layer comprises at least 30 % by weight of a compostable polymer.

2. The paper or paperboard according to claim 1 wherein the biodegradable coating layer comprises between 30-100 % by weight of the compostable polymer.

3. The paper or paperboard according to any of the preceding claim wherein the compostable polymer is a polyhydroxyalkanoate (PHA) polybutylene succinate (PBS), polylactic acid (PLA) or polysaccharide derivatives.

4. The paper or paperboard according to claim 3 wherein the PHA is selected from the group consisting of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBH), poly(3- hydroxybutyrate-co-4-hydroxybutyrate) (P3HB4HB), poly(3-hydroxyoctanoate- co-3-hydroxyhexanoate) (PHOHH), poly(3-hydroxyoctanoate-co-3- hydroxydecanoate) (PHOHD), and poly(3-hydroxyoctanoate-co-3- hydroxydodecanoate) (PHDHDD), or a mixture thereof.

5. The paper or paperboard according to any of the preceding claims wherein the biodegradable coating layer further comprises between 5-70 % by weight of a pigment.

6. The paper or paperboard according to claim 5 wherein the pigment is a high reflective pigment such as calcined clay, precipitated calcium carbonate (PCC), ground calcium carbonate (GCC) and / or titanium dioxide.

7. The paper or paperboard according to any one of the preceding claims, wherein said FDCA based resin comprises at least 70 % by weight, preferably at least 90 % by weight, of said FDCA based polymer.

8. The paper or paperboard according to any of the preceding claims wherein the FDCA based polymer has a melting temperature (Tm) above 210 °C, preferably above 225 °C.

9. The paper or paperboard according to any of the preceding claims wherein the FDCA based polymer has a crystallinity between 5-40%, preferably between 10-35% and even more preferred between 15-25%, measured according to ASTM E794-06 (2018)10. The paper or paperboard according to any one of the preceding claims, wherein the paper or paperboard further comprises at least one second polymer coating layer disposed on top of the first coating layer.

11. The paper or paperboard according to claim 10, wherein the at least one second polymer coating layer comprises a FDCA based polymer, polyethylene terephthalate (PET), polyethylene (PE), polypropylene (PP) and / or polylactic acid (PLA).

12. The paper or paperboard according to any one of the preceding claims, wherein the first and / or second coating layer / s are applied to the paper or paperboard at a grammage of less than 50 gsm, preferably less than 40 gsm, more preferably less than 35 gsm.

13. The paper or paperboard according to any of the preceding claims wherein the paper or paperboard is a multiply paperboard product comprises at least two cellulose based plies, preferably at least three cellulose based plies.

14. The paper or paperboard according to any of the preceding claims wherein the paper or paperboard further comprises a peeling layer located between the paper or paperboard and the biodegradable coating layer.

15. The paper or paperboard according to any of the preceding claims wherein the FDCA based polymer is polyethylene furanoate (REF), polybutylene furanoate (PBF), polytrimethylene furandicarboxylate (PTF), polypentamehylene furanoate (PPeF), polyheam ethylene furanoate (PHF) or polypropylene furanotate (PPF).

16. A 3D formed package comprising the paper or paperboard according to any one of the preceding claims.

17. A method for manufacturing a coated paper or paperboard substrate, wherein said method comprises the steps of: a) providing a paper or paperboard substrate, b) providing a biodegradable coating composition c) applying said biodegradable coating composition onto at least one surface of the paper or paperboard substrate to form a biodegradable coating layer, d) providing a FDCA based resin, e) applying the FDCA based resin directly onto at least one of the biodegradable coating layer by extrusion coating to form a first coating layer, f) cooling the FDCA based resin, thereby forming the coated paper or paperboard substrate, characterized in that the FDCA based resin comprises at least 50 % by weight of a FDCA based polymer and that the biodegradable coating composition comprises at least 30 % by weight of a compostable polymer.

18. The method according to claim 17 wherein the cooling step is done in a chill roll at a temperature of between 5-60 °C for a time of at least 0.15 s, preferably between 0.15-10 seconds.

19. The method according to any of the claims 17 or 18 wherein the pressure used during extrusion coating of the FDCA based resin is between 30-800 kPa, preferably between 40-500 kPa and even more preferred between 50- 350 kPa.

20. The method according to any of the claims 17-19 wherein the biodegradable composition is applied by a liquid film coating process.

21. The method according to any of the claims 17-20, wherein the method further comprises the steps of: applying at least one second polymer coating layer disposed onto of the first polymer coating layer or onto the biodegradable coating layer.

22. The method according to claim 21 , wherein the at least one second polymer coating layer comprises a FDCA based polymer, polyethylene terephthalate (PET), polyethylene (PE), polypropylene (PP) and / or polylactic acid (PLA).

23. The method according to any of the claims 17-22 wherein the method further comprises the step of drying the paper or paperboard substrate to a moisture content of between 5-14 % by weight before application of the biodegradable coating composition.

24. The method according to any of the claims 17-23 wherein the method further comprises the step of applying a peeling layer between the biodegradable coating layer and the first polymer coating layer.

25. The method according to any of the claims 17-24 wherein the method further comprises the step of subjecting the paper or paperboard substrate to a flame, plasma and / or corona treatment before applying the biodegradable coating composition.

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