A method for manufacturing a paper or paperboard based packaging laminate

Abstract

The present invention relates to a method for manufacturing a paper or paperboard based packaging laminate, said method comprising:a) providing a multiply paper or paperboard substrate comprisinga first outermost ply comprising at least 70 wt% bleached kraft pulp or hardwood pulp based on the dry weight of the ply, anda second outermost ply comprising at least 70 wt% unbleached kraft pulp and / or high yield pulp based on the dry weight of the ply;b) providing a barrier paper comprising at least 70 wt% cellulosic material based on the dry weight of the barrier paper; andc) laminating the barrier paper to an outer surface of the second outermost ply of the multiply paper or paperboard substrate using a foamed adhesive composition, which forms a tie layer between the barrier paper and the outer surface of the second outermost ply.

Description

The present disclosure relates to paper or paperboard based packaging laminates comprising a barrier paper as a barrier layer, and to methods for manufacturing such laminates.BackgroundAseptic packaging for long shelf-life products such as milk and juices are usually made from liquid or food packaging board comprising a multilayer paper or paperboard based substrate, an outermost heat-sealable polyolefin (e.g. polyethylene, PE) layer and innermost layers of polyolefin and aluminum. The aluminum foil layer, which is included to provide water vapor and oxygen barrier properties, is usually incorporated between tie layers of polyethylene to provide the following structure: PE / paperboard / PE / aluminum foil / PE.Paper generally refers to a material manufactured in thin sheets or webs from the pulp of wood or other fibrous substances comprising cellulose fibers, used for writing, drawing, or printing on, or as packaging material. Paperboard generally refers to strong and / or stiff, thick paper or cardboard comprising cellulose fibers used for boxes and other types of packaging. Paper or paperboard can either be bleached or unbleached, coated or uncoated, and produced in a variety of thicknesses, depending on the end use requirements. Paper or paperboard for use in packaging is typically a multiply material comprised of two or more cellulose based plies. A multiply structure allows for the different plies to be designed differently in order to fulfill specific functional requirements. Often, the paper or paperboard is comprised of a lower density mid-ply sandwiched between two higher density outer plies. The 3-ply structure permits the optimization of the outer layers without compromising the intrinsic stiffness and paperboard conversion benefits provided by the mid-ply. Normally, the outer ply formed closest to the wire in the paper machine, is optimized to have high elastic modulus and provide good bending stiffness to the 3-ply structure. However, the same ply should preferably also be kept porous to allow for reasonably fast dewatering of the paper or paperboard through the ply in the wire section and fast drying of the board in the drying section. A negative effect of the high porosity is that the ply will not be a good base for further surface treatment such as sizing, mineral coating, barrier dispersion coating, etc.Coating of paper and paperboard with plastics is often employed to combine the mechanical properties of the paper or paperboard with the barrier and sealing properties of a plastic film or layer. Paper or paperboard provided with even a relatively small amount of a suitable plastic material can provide the properties needed to make the paper or paperboard suitable for many demanding applications, for example as liquid or food packaging. In liquid or food packaging board, polyolefin coatings are frequently used as liquid barrier layers, heat sealing layers and adhesives. However, the recycling of such polymer coated board is difficult since it is difficult to separate the polymers from the fibers.Also, in many cases the water vapor barrier properties of the polymer coated paper or paperboard are still insufficient unless the coating layers are thick or combinations of different polymer coating layers are used. Therefore, in order to ensure high water vapor barrier properties, the polymer coated paper or paperboard is often combined with one or more layers of aluminum foil. The aluminum foil is typically bonded to the laminate using one or more polymeric tie layers. However, the addition of polymer and aluminum foil add significant costs and the combination of polymeric layers and aluminum foils makes recycling of the materials more difficult. Also, due to its high carbon footprint there is a wish to replace aluminum foils in paper and paperboard based packaging materials.In the prior art, attempts have been made to replace the aluminum foil with more environmentally friendly and / or easier to recycle solutions. For example, microfibrillated cellulose (MFC) films and coatings have been developed, in which cellulosic fibrils provided by fibrillation of cellulose fibers have been dispersed e.g. in water and thereafter re-organized and rebonded together to form a dense film or coating with excellent gas barrier properties. The MFC films are typically laminated to the paper or paperboard in the same manner as aluminum foils, using PE-based tie layers or water based adhesives e.g. containing water soluble PVOH. However, challenges still remain in terms of providing sufficient barrier properties, mechanical strength and durability, at an acceptable cost, in order to effectively replace aluminum foils and plastic films with cellulose based alternatives.There remains a need for improved solutions to replace the combination of plastic films and aluminum foils in paper and paperboard based packaging materials, while maintaining acceptable liquid and oxygen barrier properties. At the same time, there is a need to replace the combination of plastic films and aluminum foils with alternatives that facilitate re-pulping and recycling of the used packaging materials. New paperboard materials should also preferably provide either improved rigidity at the same fiber amount, or retained rigidity at a lower fiber amount as compared to conventional paperboards.Description of the inventionIt is an object of the present disclosure to provide an alternative to the paper or paperboard based laminates comprising combinations of plastic films and aluminum foils commonly used in packaging materials, such as liquid or food packaging board.It is a further object of the present disclosure to provide a simplified method for manufacturing a paper or paperboard based packaging laminate comprising a barrier paper.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.According to a first aspect illustrated herein, there is provided a method for manufacturing a paper or paperboard based packaging laminate, said method comprising:a) providing a multiply paper or paperboard substrate comprisinga first outermost ply comprising at least 70 wt% bleached kraft pulp or hardwood pulp based on the dry weight of the ply, anda second outermost ply comprising at least 70 wt% unbleached kraft pulp and / or high yield pulp based on the dry weight of the ply, andoptionally a mid ply arranged between the first and second outermost plies, said mid ply comprising at least 70 wt% unbleached kraft pulp and / or high yield pulp, and optionally 1-30 wt% bleached kraft pulp or hardwood pulp, based on the dry weight of the ply;b) providing a barrier paper comprising at least 70 wt% cellulosic material based on the dry weight of the barrier paper, wherein the barrier paper has an oxygen transmission rate (OTR) measured according to the standard ASTM F1927-20 at 50% relative humidity and 23 °C of less than 50 cc / m2 / 24h, and a cross direction (CD) strain at break measured according to the standard ISO 1924-3:2005 of at least 1.8 %; andc) laminating the barrier paper to an outer surface of the second outermost ply of the multiply paper or paperboard substrate using a foamed adhesive composition, which forms a tie layer between the barrier paper and the outer surface of the second outermost ply.Paper generally refers to a material manufactured in thin sheets or webs from the pulp of wood or other fibrous substances comprising cellulose fibers, used for writing, drawing, or printing on, or as packaging material.Paperboard generally refers to strong and / or stiff, thick paper or cardboard comprising cellulose fibers used for boxes and other types of packaging.Paperboard can either be bleached or unbleached, coated or uncoated, and produced in a variety of thicknesses, depending on the end use requirements.Paperboard is typically a multiply material comprised of two or more cellulose based plies.A paper or paperboard based packaging laminate is a packaging material formed mainly from a paper or paperboard substrate. In the Inventive paper or paperboard based packaging laminate, both the paper or paperboard substrate and the barrier paper are formed mainly from cellulose-based materials. In some embodiments, the paper or paperboard based packaging laminate comprises more than 70 wt%, preferably more than 75 wt%, more preferably more than 80 wt%, and most preferably more than 85 wt%, of cellulose-based material, based on the dry weight of the paper or paperboard based packaging laminate.The inventive paper or paperboard based packaging laminate can provide an alternative to conventional packaging laminates using aluminum foil layers, which can more readily be repulped and recycled.The paper or paperboard substrate of the present disclosure comprises a first outermost ply comprising at least 70 wt% bleached kraft pulp or hardwood pulp based on the dry weight of the ply. The first outermost ply has an outer surface forming a first outer surface of the paper or paperboard substrate.The paper or paperboard substrate further comprises a second outermost ply comprising at least 70 wt% unbleached kraft pulp and / or high yield pulp based on the dry weight of the ply. The second outermost ply has an outer surface forming a second outer surface of the paper or paperboard substrate.Optionally, the paper or paperboard substrate further comprises a mid ply arranged between the first and second outermost plies, said mid ply comprising at least 70 wt% unbleached kraft pulp and / or high yield pulp, and optionally 1-30 wt% bleached kraft pulp or hardwood pulp, based on the dry weight of the ply. The bleached kraft pulp or hardwood pulp optionally present in the mid ply may for example include bleached kraft pulp or hardwood pulp derived from broke substrate or laminate recycled in the manufacturing method.In addition to the paper or paperboard substrate, the paper or paperboard based packaging laminate comprises a barrier paper which is laminated to the outer surface of the second outermost ply of the paper or paperboard substrate. The barrier paper comprises at least 70 wt% cellulosic material based on the dry weight of the barrier paper, wherein the barrier paper has an oxygen transmission rate (OTR) measured according to the standard ASTM F 1927-20 at 50% relative humidity and 23 °C of less than 50 cc / m2 / 24h, and a cross direction (CD) strain at break measured according to the standard ISO 1924-3:2005 of at least 1.8 %.In the present disclosure, the barrier paper in addition to providing barrier properties to the packaging laminate, also takes the place of a conventional bleached kraft pulp or hardwood pulp back ply commonly used to achieve a board with high bending resistance. In order to achieve this, the barrier paper should have a sufficient strain at break.The barrier paper is laminated to the outer surface of the second outermost ply of the paper or paperboard substrate. The outer surface of the second outermost ply of the paper or paperboard substrate has high roughness and porosity, the surface typically has a Bendtsen roughness of at least 300 ml / min according to standard ISO 8791-2, and is not a good base for lamination. The ply will absorb a large portion of the applied adhesive, increasing the amount of adhesive required, causing densification of the second outermost ply and mid ply, and reducing the bending resistance of the obtained laminate.The present inventors have found that these problems as well as other problems can be remedied by using a foamed adhesive composition. Thus, in the method of the present disclosure, the barrier paper is laminated to the outer surface of the second outermost ply of the paper or paperboard substrate using a foamed adhesive composition, which forms a tie layer between the barrier paper and the outer surface of the second outermost ply. The foamed adhesive composition is applied as a wet foam. The foam may be at least partially collapsed during lamination and drying. With the foamed adhesive composition, preferably very little adhesive penetrates into the second outermost ply of the paper or paperboard substrate, and substantially no adhesive will penetrate into an optional mid ply of the paper or paperboard substrate, as verified by cross-section imaging of the obtained laminates.The paper or paperboard based packaging laminate may also comprise additional layers or coatings designed to improve the performance and / or appearance of the packaging laminate.The paper or paperboard based packaging laminate typically has a first outermost surface intended to serve as the outside surface, or print side, and a second outermost surface intended to serve as the inside surface of a packaging container. The first outermost surface intended to serve as the outside surface, or print side, of the laminate may optionally be surface sized or pigment coated to provide high print quality.The paper or paperboard based packaging laminate obtained by the inventive method can provide excellent gas barrier properties, as evidenced by a low oxygen transmission rate (OTR) measured according to the standard ASTM F 1927-20 at 50% relative humidity and 23 °C, and excellent water vapor barrier properties, as evidenced by a low water vapor transmission rate (WVTR) measured according to the standard ASTM F1249-20 at 50% relative humidity and 23 °C.The paper or paperboard substrate used in the inventive method is a multiply paper or paperboard substrate. The paper or paperboard substrate comprises at least two plies.In some embodiments, each ply of the multiply paper or paperboard substrate has a grammage in the range of 20-240 g / m2. Unless otherwise stated, the grammages herein are determined according to the standard ISO 536.In some embodiments, the multiply paper or paperboard substrate has a total grammage in the range of 100-400 g / m2.In some embodiments, the multiply paper or paperboard substrate has a density in the range of 300-650 kg / m3, preferably in the range of 300-600 kg / m3, and more preferably in the range of 300-550 kg / m3. Unless otherwise stated, the densities herein are determined according to the standard ISO 534.In some embodiments, the multiply paper or paperboard substrate has a thickness of at least 150 pm, preferably at least 200 pm, and more preferably at least 250 pm or at least 300 pm. The thicknesses herein are determined according to the standard ISO 534.In some embodiments, the bleached kraft pulp or hardwood pulp of the first outermost ply has a Schopper Riegler (SR) value in the range of 15-35 according to standard ISO 5267-1.In some embodiments, the unbleached kraft pulp and / or high yield pulp of the second outermost ply has a Schopper Riegler (SR) value below 28, preferably below 25, and more preferably below 22, according to standard ISO 5267-1.In some embodiments, the unbleached kraft pulp and / or high yield pulp of the optional mid ply has a Schopper Riegler (SR) value below 28, preferably below 25, and more preferably below 22, according to standard ISO 5267-1.In some embodiments, the optional bleached kraft pulp or hardwood pulp of the optional mid ply has a Schopper Riegler (SR) value in the range of 15-35 according to standard ISO 5267-1.In some embodiments, the second outermost ply, and the optional mid ply, has a density below 600, below 550, below 500, below 450, below 400 or below 350 kg / m3. The first outermost ply typically has a higher density than the second outermost ply, and the optional mid ply. In some embodiments, the first outermost ply has a density at least 100 kg / m3 higher, preferably at least 200 kg / m3 higher than the second outermost ply.As used herein, the term "high yield pulp" refers to a class of pulp derived from lignocellulosic material characterized by a yield that significantly exceeds the yield typically associated with conventional chemical pulping processes. Specifically, "High Yield Pulp" is defined as pulp that is produced with a process yield of at least 65%, preferably at least 75%, and more preferably at least 85%, of the original dry weight of the lignocellulosic material used in its production.This pulp retains a substantial portion of the lignin and hemicellulose present in the original biomass, distinguishing it from lower-yield pulps where such components are largely removed. The preservation of lignin and hemicellulose contributes to the distinctive properties of high yield pulp, including improved strength, increased bulk, and enhanced sustainability attributes due to reduced chemical usage and waste generation during the pulping process. In some embodiments the high yield pulp has a Klason lignin content >15 wt%. In some embodiments, the high yield pulp has a KAPPA number of at least 50, preferably at least 70, and more preferably at least 80, measured according to ISO 302:2015.High yield pulp is produced through a modified pulping process that may involve mechanical, semi-chemical, or chemi-thermomechanical methods, or combinations thereof, designed to minimize the degradation or removal of cellulose, hemicellulose, and lignin. The high yield pulp may be bleached, delignified or unbleached.In some embodiments, the unbleached kraft pulp has a KAPPA number of at least 20, such as in the range of 25-100, measured according to ISO 302:2015.In some embodiments, the unbleached kraft pulp and / or high yield pulp of the second outermost ply and / or the mid ply is chemi-thermomechanical pulp (CTMP) or high-temperature chemi-thermomechanical pulp (HT-CTMP). In some embodiments, the high yield pulp of the second outermost ply and / or the mid ply is softwood CTMP or softwood HT-CTMP. In some embodiments, the high yield pulp of the second outermost ply and / or the mid ply is hardwood CTMP or hardwood HT-CTMP. In some embodiments, the high yield pulp of the second outermost ply and / or the mid ply comprises a mixture of two or more of softwood CTMP, softwood HT-CTMP, hardwood CTMP and hardwood HT-CTMP.In some embodiments, the unbleached kraft pulp and / or high yield pulp of the second outermost ply and / or the mid ply comprises recycled unbleached kraft pulp fibers and / or recycled high yield pulp fibers. The recycled fibers may be fibers obtained from recycled packaging waste and especially from used beverage cartons. The structure of the inventive paper or paperboard based packaging laminate enables the use of a larger amount of recycled fibers, such as fibers obtained from used beverage cartons, in the paper or paperboard substrate since the barrier paper, and in some cases also the tie layer, hinders the migration of mineral oil based contaminants. Thus, in some embodiments, the second outermost ply and / or the mid ply comprises at least 5 wt% recycled high yield pulp fibers, preferably at least 10 wt% recycled high yield pulp fibers, such as 5-30 wt% or 10-30 wt%, based on dry weight of the ply.Preferably, the extractive content of the unbleached kraft pulp and / or high yield pulp is less than 0.3%, preferably less than 0.25%, and more preferably less than 0.2% as measured by extraction in acetone according to standard SCAN CM-49:03. This can minimize odor or taste caused by subsequent drying of the foamed adhesive composition.In some embodiments, the second outermost ply and / or the mid ply comprises unbleached kraft pulp and / or high yield pulp that has been washed to reduce the content of cellulosic and non-cellulosic fines and other contaminants.In some embodiments, the second outermost ply and / or the mid ply comprises 0.1-10 wt%, preferably 0.15-5 wt%, of a strength enhancement agent based on the dry weight of the ply. The strength enhancement agent may comprise a polysaccharide or a derivative thereof. In some embodiments the strength enhancement agent is selected from highly refined cellulose, such as microfibrillated cellulose, or starch, or a combination thereof. The strength enhancement agent may be present in the bulk of the plies or at an interface between the two plies, such as in the form of a ply bond layer.In some embodiments, the second outermost ply and / or the mid ply, preferably at least the second outermost ply, comprises 0.05-5 wt%, preferably 0.1-4 wt%, and more preferably 0.2-3 wt%, of a hydrophobizing internal sizing agent based on the dry weight of the ply. These amounts of a hydrophobizing internal sizing agent, at least in the second outermost ply, have surprisingly been found to facilitate the application of the foamed adhesive composition by more even and better spreading of the composition.The outer surface of the first outermost ply is preferably configured to serve as an outer surface, or print surface, of a packaging formed of the finished packaging laminate.In some embodiments, the paper or paperboard substrate further comprises a mineral coating layer on the outer surface of the first outermost ply. In some embodiments, the mineral coating layer comprises 50-95 wt% of a particulate mineral, and 5-50 wt% of a binder, based on the dry weight of the mineral coating layer. In some embodiments, the particulate mineral is selected from the group consisting of kaolin, calcium carbonate, bentonite, talc, and combinations thereof, preferably kaolin or calcium carbonate, and more preferably calcium carbonate. The binder may preferably comprise a water-dispersible or water-soluble binder, or a combination thereof. In some embodiments, the water-dispersible binder comprises a latex binder. In some embodiments, the grammage of the mineral coating layer is in the range of 4-30 g / m2, more preferably in the range of 6-14 g / m2.In some embodiments, the multiply paper or paperboard substrate is provided by: i) forming a first web layer by applying a first suspension comprising at least 70 wt% bleached kraft pulp or hardwood pulp based on the dry weight of the suspension on a first wire, and partially dewatering the first web layer on the first wire;ii) forming a second web layer by applying a second suspension comprising at least 70 wt% unbleached kraft pulp and / or high yield pulp based on the dry weight of the suspension on a second wire, and partially dewatering the second web layer on the second wire;iii) optionally forming a third web layer by applying a third suspension comprising at least 70 wt% unbleached kraft pulp and / or high yield pulp, and optionally 1-30 wt% bleached kraft pulp or hardwood pulp, based on the dry weight of the suspension on a third wire, and partially dewatering the third web layer on the third wire;iv) couching the partially dewatered first web layer and the partially dewatered second web layer, and optionally the partially dewatered third web layer, to obtain a laminate web, wherein the first web layer forms a first outermost ply and the second web layer forms a second outermost ply, and the optional third web layer forms an optional mid ply; andv) dewatering and drying the formed laminate web to obtain the multiply paper or paperboard substrate.In some embodiments, the dewatering comprises passing the formed laminate web through at least one shoe press and preferably through at least two shoe presses, preferably wherein at least one shoe press is a double felted shoe press.Roughness of the outer surface of second outermost ply can be high thanks to the use of the foamed adhesive composition.In some embodiments, the outer surface of the second outermost ply has a Bendtsen roughness of at least 300 ml / min, preferably at least 400 ml / min, at least 500 ml / min, at least 600 ml / min, at least 700 ml / min, or at least 800 ml / min, according to standard ISO 8791-2.In some embodiments, the outer surface of the second outermost ply has a PPS surface smoothness at 1.0 MPa in the range of 1-20 μm, preferably in the range of 1.5-10 μm, and more preferably in the range of 2-8 μm, as determined according to ISO 8791-4:2007.The paper or paperboard substrate, before the barrier paper film is laminated to the substrate, typically has high oxygen transmission rate (OTR) and water vapor transmission rate (WVTR) values, i.e. poor oxygen and water vapor transmission resistance.A barrier paper is provided as a barrier for oxygen and water vapor in the paper or paperboard based packaging laminate.The barrier paper comprises at least 70 wt% cellulosic material based on the dry weight of the barrier paper, wherein the barrier paper has an oxygen transmission rate (OTR) measured according to the standard ASTM F1927-20 at 50% relative humidity and 23 °C of less than 50 cc / m2 / 24h, and a cross direction (CD) strain at break measured according to the standard ISO 1924-3:2005 of at least 1.8 %.In some embodiments, the grammage of the barrier paper is in the range of IB-120 g / m2, preferably in the range of 25-80 g / m2, and more preferably in the range of 25-60 g / m2. Unless otherwise stated, the grammage is determined according to the standard ISO 536.In some embodiments, the barrier paper has a density in the range of 800-1500 kg / m3, preferably in the range of 850-1050 kg / m3. Unless otherwise stated, the density is determined according to the standard ISO 534.In some embodiments, the density of the barrier paper is higher than the density of the first outermost ply of the paper or paperboard substrate. Thus, in these embodiments the density of the first outermost ply is higher than the density of the second outermost ply and the optional mid ply, and the density of the barrier paper is higher than the density of the first outermost ply.In some embodiments, the barrier paper has a thickness in the range of 15-170 μm, preferably in the range of 15-114 μm, more preferably in the range of 15-57 μm.In some embodiments, the barrier paper comprises at least 50 wt% highly refined cellulose having a Schopper Riegler (SR) value in the range of 70-98, preferably in the range of 80-98, and more preferably in the range of 85-95, according to standard ISO 5267-1, based on the dry weight of the barrier paper. In some embodiments, the barrier paper comprises at least 70 wt%, preferably at least 75 wt%, and more preferably at least 80 wt%, of highly refined cellulose having a Schopper Riegler (SR) value in the range of 70-98, preferably in the range of 80-98, and more preferably in the range of 85-95, according to standard ISO 5267-1, based on the dry weight of the barrier paper.In some embodiments, the highly refined cellulose is microfibrillated cellulose (MFC). 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 followed by refining or high shear disintegration or liberation of fibrils. One or several pre-treatment steps is usually required in order to make MFC manufacturing both energy efficient and sustainable. The cellulose fibers of the pulp used when producing MFC may thus be native or pre-treated enzymatically or chemically, for example to reduce the quantity of hemicellulose or lignin. The cellulose fibers may be chemically modified before fibrillation, wherein the cellulose molecules contain functional groups other (or more) than found in the original cellulose. Such groups include, among others, carboxymethyl (CM), aldehyde and / or carboxyl groups (cellulose obtained by N-oxyl mediated oxidation, for example "TEMPO"), or quaternary ammonium (cationic cellulose). After being modified or oxidized in one of the above-described methods, it is easier to disintegrate the fibers into MFC.MFC is produced from wood cellulose fibers, both from hardwood and softwood fibers. It can also be made from microbial sources, agricultural fibers such as wheat straw pulp, bamboo, bagasse, or other non-wood fiber sources. It is preferably made from pulp including pulp from virgin fiber, e.g. mechanical, chemical and / or thermomechanical pulps. It can also be made from broke or recycled paper.In some embodiments, the barrier paper further comprises 1-30 wt% of unrefined or slightly refined cellulose based on the dry weight of the barrier paper, wherein the unrefined or slightly refined cellulose has a Schopper Riegler (SR) value in the range of 10-35, preferably in the range of 10-30, according to standard ISO 5267-1. A barrier paper comprising a high amount of highly refined cellulose and a lower amount of unrefined or slightly refined cellulose is useful as it combines the barrier properties of a highly refined cellulose with the mechanical strength properties, such as tear strength and burst strength, of unrefined or slightly refined cellulose.In some embodiments, the barrier paper further comprises 0.1-10 wt%, preferably 0.15-5 wt%, of a strength enhancement agent based on the dry weight of the barrier paper. The strength enhancement agent may comprise a polysaccharide or a derivative thereof. In some embodiments the strength enhancement agent is selected from highly refined cellulose, such as microfibrillated cellulose, or starch, or a combination thereof.In some embodiments, the barrier paper further comprises 0.1-30 wt% of a polyvinyl alcohol (PVOH) based on the dry weight of the barrier paper. The PVOH may be PVOH or a derivative or analogue thereof. The PVOH may be a single type of PVOH, or it can comprise a mixture of two or more types of PVOH, differing, e.g., in degree of hydrolysis or viscosity. The PVOH may for example have a degree of hydrolysis in the range of 80-99.9 mol%, preferably in the range of 88-99.9 mol%.The barrier paper may be a single ply or a multiply barrier paper.In some embodiments, the barrier paper is polymer coated, mineral coated, and / or metallized. The barrier paper preferably has an ash content less than 20 wt%, preferably less than 15 wt%, ISO 1762:2019.The barrier paper has an oxygen transmission rate (OTR) measured according to the standard ASTM F1927-20 at 50% relative humidity and 23 °C of less than 50 cc / m2 / 24h. In some embodiments, the barrier paper has an oxygen transmission rate (OTR), measured according to the standard ASTM F1927-20 at 50% relative humidity and 23 °C, of less than 30 cc / m2 / 24h, preferably less than 10 cc / m2 / 24h.In some embodiments, the barrier paper has a water vapor transmission rate (WVTR), measured according to the standard ASTM F1249-20 at 50% relative humidity and 23 °C, of less than 30 g / m2 / 24h, preferably less than 20 g / m2 / 24h, more preferably less than 10 g / m2 / 24h, and most preferably less than 5 g / m2 / 24h.In the present disclosure, the barrier paper in addition to providing barrier properties to the packaging laminate, also takes the place of a conventional bleached kraft pulp or hardwood pulp back ply commonly used to achieve a board with high bending resistance. In order to achieve this, the barrier paper should have a sufficient strain at break, and preferably also tensile stiffness.The barrier paper has a cross direction (CD) strain at break measured according to the standard ISO 1924-3:2005 of at least 1.8 %. In some embodiments, the barrier paper has a cross direction (CD) strain at break measured according to the standard ISO 1924-3:2005 of at least 2 %, preferably at least 2.5 %, and more preferably at least 3 %.In some embodiments, the barrier paper has a tensile stiffness measured according to the standard ISO 1924-3:2005 of at least 4*106 Nm / kg, preferably at least 5*106 Nm / kg, and more preferably at least 4*106 Nm / kg.The barrier paper is laminated to the outer surface of the second outermost ply of the paper or paperboard substrate using a foamed adhesive composition, which forms a tie layer between the barrier paper and the outer surface of the second outermost ply. The lamination typically comprises:i) applying the foamed adhesive composition onto the outer surface of the second outermost ply of the multiply paper or paperboard substrate, onto the surface of the barrier paper, or onto both, such that a layer of the foamed adhesive composition is formed,ii) laminating the barrier paper to the outer surface of the second outermost ply of the multiply paper or paperboard substrate by contacting the barrier paper and the outer surface of the second outermost ply of the paper or paperboard substrate with the layer of foamed adhesive between them, and allowing the foamed adhesive composition to dry and / or set to form the tie layer.In some embodiments, the foamed adhesive composition is only applied onto the outer surface of the second outermost ply of the multiply paper or paperboard substrate, since this surface may be less sensitive to rewetting than the barrier paper. The applied foamed adhesive composition may optionally be partially dried before the lamination is performed. This may be advantageous in order to reduce the amount of liquid carrier trapped in the formed laminate. Too much trapped liquid carrier may lead to blistering and delamination as the laminate dries.The foamed adhesive composition may be applied in one or several steps.The term foam or foamed, as used herein, refers to a liquid, preferably an aqueous liquid, comprising air or gas bubbles dispersed therein. Typically, the volume of gas is much larger than that of the liquid, with thin films separating gas pockets. Three requirements must be met in order for foam to form. Mechanical work is needed to increase the contact area between the gas and the liquid. This can occur by agitation, dispersing a large volume of gas into a liquid, or injecting a gas into a liquid. The second requirement is that a foamable component, typically an amphiphilic substance, a surfactant or surface active component, must be present to decrease surface tension. Finally, the foam should form more quickly than it breaks down.Foams may be open-cell or closed-cell in nature. Pores connect the gas regions in open-cell foams, while closed-cell foams have enclosed cells. The cells are usually disordered in their arrangement, with varying bubble sizes. The cells present minimal surface area, forming honeycomb shapes or tessellations.Using a foamed adhesive composition in the method of the present disclosure has been found advantageous for several reasons.The foamed adhesive composition is particularly useful for laminating a barrier paper to a multiply paper or paperboard substrate having a relatively high surface roughness. Application of the adhesive in foamed form gives less absorption of adhesive into the relatively rough surface of the second outermost ply, leading to better contact between the polymeric adhesive and the substrate and barrier paper respectively, reduced rewetting of the substrate and barrier paper respectively, and reduced amount of polymeric adhesive required.The barrier paper is typically sensitive to moisture. Using a conventional water based adhesive composition on the barrier paper may lead to dimensional stability problems, cockling, wrinkles, and shrinkage in the barrier paper and in the resulting paper or paperboard based packaging laminate. Application of the polymeric adhesive in foamed form is advantageous as it allows for application at higher solids content compared to a non-foamed application. A foamed composition comprises less water and causes less problems due to rewetting of the substrate and barrier paper.The adhesive composition comprises at least one adhesive component and one foamable component, or at least one adhesive and foamable component, in a liquid carrier. The adhesive composition may also further comprise other additives for facilitating the coating process or improving the properties of the foamed adhesive composition.In some embodiments, the foamed adhesive composition is water-based, i.e. the liquid carrier is water.The adhesive composition is capable of being foamed to form a stable foam. By "stable foam” as used herein is meant that the foam of the foamed adhesive composition is sufficiently stable to remain in foam form at least until the foamed adhesive composition has been applied.The adhesive component comprises one or more compounds capable of creating an adhesive layer. The adhesive component may preferably comprise or consist of one or more adhesive polymers. Examples of adhesive components include, but are not limited to, water soluble polymers selected from polyvinyl alcohol (PVOH), polysaccharides, proteins, alginate, pectin, agar, lignin and lignin derivatives.The polysaccharides may be anionic, cationic, non-ionic or amphiphilic or amphoteric. Examples of polysaccharides include, but are not limited to, starch, modified starch, bean gum, guar gum, cellulose derivatives and hemicellulose.In some embodiments, the adhesive component of the adhesive composition is at least partially soluble in cold water or in hot water, e.g. at a temperature below 100 °C or even above 100 °C, for a given period of time. In some embodiments, the adhesive component of the adhesive composition is fully soluble in cold water or in hot water, e.g. at a temperature below 100 °C or even above 100 °C, for a given period of time. The solubility of the adhesive component of the adhesive composition allows for the tie layer to dissolve, to fully or partially disintegrate, or to become substantially weakened, when subjected to water such as during repulping.The foamable component is a compound capable of forming and / or stabilizing a foam in the adhesive composition. The foamable component is typically an amphiphilic substance, i.e. a chemical compound possessing both hydrophilic and hydrophobic (lipophilic) properties. A foamable component reduces the work needed to create the foam by reducing the surface tension of the liquid and increases the colloidal stability of the foam by inhibiting coalescence of bubbles.The foamable component is typically a surfactant, such as SDS, or a surface active polymer, or a combination thereof. In some embodiments, the foamable component is a non-polymeric or polymeric surfactant, or a combination thereof. The surfactant may be anionic, non-ionic, or zwitter-ionic.In some embodiments, the foamable component is a non-polymeric surfactant, preferably sodium dodecyl sulfate (SDS).The foamable component is preferably an amphiphilic polymer, i.e. a polymer possessing both hydrophilic and hydrophobic (lipophilic) properties. In some embodiments, the foamable component is water-soluble. The foamable component may for example be a water-soluble polymer with hydrophobic moieties, such as a hydrophilic polymeric backbone provided with hydrophobic sidechains, or a block copolymer comprised of hydrophilic and hydrophobic sections.In some embodiments, the foamable component is selected from the group consisting of optionally hydrophobically modified polysaccharides, proteins, polyvinyl alcohol, polyvinyl acetate and mixtures thereof. The optional hydrophobic modification typically comprises one or more hydrophobic groups, e.g. alkyl groups, covalently attached to the foamable component.In some embodiments, the foamable component is an optionally hydrophobically modified polysaccharide selected from the group consisting of optionally hydrophobically modified cellulose, starch, hemicellulose and mixtures thereof.In some embodiments, the foamable component is an optionally hydrophobically modified polysaccharide selected from the group consisting of optionally hydrophobically modified cellulose acetate (CA), ethyl(hydroxyethyl)cellulose (EHEC), methylcellulose (MC), ethylcellulose (EC), hydroxyethylcellulose (HEC), hydroxypropylcellulose (HPC), sodium carboxymethylcellulose (CMC), hydroxypropylmethylcellulose (HPMC), sulfoethylcellulose, starch, and mixtures thereof.In some embodiments, the foamable component is selected from the group consisting of ethyl(hydroxyethyl)cellulose, hydrophobically modified ethyl(hydroxyethyl)cellulose (HM-EHEC), hydroxyethylcellulose, hydrophobically modified hydroxyethyl cellulose (HM-HEC), methylcellulose (MC), hydrophobically modified methylcellulose (HM-MC), hydrophobically modified carboxymethylcellulose (HM-CMC), and hydrophobically modified starch (HM-starch). Examples of useful hydrophobically modified starch derivatives include, but are not limited to dialdehyde starch, hydroxypropylated starch, octenyl succinic anhydride (OSA) starch, and dodecyl succinic anhydride (DDSA) starch.In some embodiments, the foamable component is an optionally hydrophobically modified methyl cellulose.In some embodiments, the foamable component is a hydrophobically modified polyvinyl alcohol (PVOH), such as ethylene modified PVOH. In some embodiments, the foamable component is a polyvinyl alcohol containing at least 2% acetate groups, more preferably at least 10% acetate groups, and even more preferably at least 15% acetate groups.In some embodiments, the foamable component is the adhesive component itself, i.e. the adhesive composition comprises at least one adhesive and foamable component. In some embodiments, the foamable component is a designated foamable component used together with a designated adhesive component. An example of an adhesive component which may also act as a foamable component is polyvinyl alcohol (PVOH).In some embodiments, the foamed adhesive composition comprises a polyvinyl alcohol (PVOH). The PVOH may be a single type of PVOH, or it can comprise a mixture of two or more types of PVOH, differing, e.g., in degree of hydrolysis or viscosity. The PVOH may for example have a degree of hydrolysis in the range of 50-99.9 mol%, preferably in the range of 80-99.9 mol%, and more preferably in the range of 88-99.9 mol%. In some embodiments, the PVOH has an average molecular weight Mw in the range of 15 000-150000 g / mol.In some embodiments, the foamed adhesive composition comprises the foamable component in an amount of 0.1-30 wt% based on the total dry weight of the foamed adhesive composition. In some embodiments, the foamed adhesive composition comprises the foamable component in an amount of 0.1-10 wt% based on the total dry weight of the foamed adhesive composition. The rest of the total dry weight of the foamed adhesive composition can be made up of the adhesive component, and optionally other additives.When the foamed adhesive composition comprises an adhesive and foamable component, the composition may comprise the adhesive and foamable component in an amount of up to 100 wt% based on the total dry weight of the foamed adhesive composition. The rest of the total dry weight of the foamed adhesive composition can be made up of additional adhesive components, additional foamable components, and / or other additives.In some embodiments, the foamed adhesive composition further comprises up to a total of 15 wt% of other water soluble or non-soluble additives, based on the dry weight of the foamed adhesive composition. The other additives in the foamed adhesive composition may include nanoparticles, cross-linkers, reinforcement agents or texturing agents.In some embodiments, the foamed adhesive composition further comprises nanoparticles, such as bentonite, in an amount of 0.1-15 wt% based on the total dry weight of the foamed adhesive composition. The nanoparticles can enhance foam stability or impart barrier performance to the tie layer.In some embodiments, the foamed adhesive composition further comprises a reinforcement agent or texturing agent, preferably selected from the group consisting of carboxymethyl cellulose (CMC), microfibrillated cellulose (MFC), nanocrystalline cellulose (NCC), and starch, in an amount of 0.1-15 wt% based on the total dry weight of the foamed adhesive composition. In some embodiments the foamed adhesive composition comprises microfibrillated cellulose (MFC) or nanocrystalline cellulose (NCC) in an amount of 0.1-15 wt% based on the total dry weight of the foamed adhesive composition.The solid content of the foamed adhesive composition is preferably above 5 wt%, such as above 7.5 wt%, and more preferably in the range of 10-45 wt%, such as in the range of 12-35 wt%, based on the dry weight of the foamed adhesive composition.The foamed adhesive composition may be prepared by shearing or mixing the composition into a foam using for example a high shear mixer or a foam generator.The viscosity of the foamed adhesive composition during application is preferably in the range of 100-5000 mPas, and more preferably in the range of 100-4000 mPas, determined according to standard SCAN-P 50:84 using a Brookfield viscosimeter at rotational speed of 100 rpm.In some embodiments, the foamed adhesive composition has a foam density in the range of 0.1-0.95 kg / dm3 preferably in the range of 0.2-0.85 kg / dm3, and more preferably in the range of 0.2-0.75 kg / dm3.The foamed adhesive composition is preferably applied by means of a liquid film coating process. In some embodiments, the foamed adhesive composition is applied by a non-contact application method. In some embodiments, the foamed adhesive 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 foamed adhesive composition may be applied directly or indirectly, for example via a transfer roll or belt.The temperature of the applied foamed adhesive composition is preferably in the range of 35-65 °C. This allows for faster drying and / or setting of the foamed adhesive composition before or during the lamination step.The lamination pressure should be high enough to obtain good adhesion, but not so high that the bulk of paper or paperboard substrate is destroyed. In some embodiments the lamination pressure is in the range of 0.5-100 kg / cm, preferably in the range of 1-50 kg / cm. Pressure and heating may for example be provided in a heated nip or an extended nip.The foamed adhesive composition is dried to obtain the tie layer. The drying may cause the foam to collapse fully or partially. The drying may for example cause the average thickness of the applied foam layer to decrease by at least 50% as compared to the initial wet thickness of the foam layer before the drying. In some embodiments the average thickness of the formed tie layer is less than 50% of the thickness of the applied layer of the foamed adhesive composition.Thus, the formed tie layer may be porous or non-porous. In preferred embodiments, the formed tie layer is porous. The porous tie layer will have a lower density than a solid tie layer would have at the corresponding grammage, and may be advantageous since it will be easier to repulp and recycle.In some embodiments, the drying comprises subjecting the foamed adhesive composition to heating. In some embodiments, the drying comprises subjecting the foamed adhesive composition to at least one non-contact drying step, such as infrared radiation, electron beam radiation, ultraviolet radiation, microwave radiation, steam, hot air or a combination thereof. Optionally, the foamed adhesive 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.In some embodiments, the foamed adhesive composition is applied in at least two different coating steps with drying of the coated layer between the steps.In some embodiments, the grammage of the formed tie layer is in the range of 0.5-15 g / m2, preferably in the range of 0.5-12 g / m2, and more preferably in the range of 1-8 g / m2, based on dry weight.In some embodiments, the density of the formed tie layer is in the range of 0.5-1.2 kg / dm3. In some embodiments, the density of the formed tie layer is in the range of 0.5-1 kg / dm3. In some embodiments, the density of the formed tie layer is in the range of 0.5-0.8 kg / dm3. The density of the formed tie layer may be estimated from cross section images and reference samples on a smooth surface.The obtained paper or paperboard based packaging laminate has a low permeability for oxygen. This makes the inventive packaging laminate an interesting and viable alternative to conventional materials using aluminum foil layers.In some embodiments, the obtained paper or paperboard based packaging laminate has an oxygen transmission rate (OTR), measured according to the standard ASTM F1927-20 at 50% relative humidity and 23 °C, of less than 30 cc / m2 / 24h, preferably less than 20 cc / m2 / 24h, more preferably less than 10 cc / m2 / 24h, and most preferably less than 5 cc / m2 / 24h.Thanks to the multi-layer structure with coarse and bulky fibers in the second outermost ply and optional mid ply sandwiched between the bleached kraft or hardwood fibers in the first outermost ply and the laminated barrier paper, the final laminate will have high bending resistance.In some embodiments, the obtained paper or paperboard based packaging laminate hasa bending resistance, L&W 15° in the machine direction, of at least 600 mN, preferably at least 700 mN, according to standard ISO 2493, and / ora bending resistance, L&W 15° in the cross direction, of at least 180 mN, preferably at 250 mN, according to standard ISO 2493, and / ora bending resistance, L&W 15° geometric mean, of at least 350 mN, preferably at least 380 mN, according to ISO 2493, and / ora bending moment, Taber 15° geometric mean, of at least 15 nNm, preferably at least 20 nNm according to standard ISO 2493.In some embodiments, the obtained paper or paperboard based packaging laminate has a bending resistance index of at least 5 Nm6 / kg3 according to standard ISO 2493.In some embodiments, the obtained paper or paperboard based packaging laminate has a Scott Bond of at least 80 J / m2 according to standard TAPPI um-403.In some embodiments, the obtained paper or paperboard based packaging laminate has a Z-strength of at least 200 kPa according to standard SCAN-P 80:98.In some embodiments, the obtained paper or paperboard based packaging laminate comprises more than 70 wt%, preferably more than 75 wt%, more preferably more than 80 wt%, and most preferably more than 85 wt%, of cellulosebased material, based on the dry weight of the paper or paperboard based packaging laminate.The inventive packaging laminate is an interesting and viable alternative to conventional materials using metallic or metal based layers, such as aluminum foil layers. Thus, in some embodiments the obtained paper or paperboard based packaging laminate comprises no metallic or metal based layer.In some embodiments the obtained paper or paperboard based packaging laminate comprises no extrusion coated plastic layer.In some embodiments, the obtained paper or paperboard based packaging laminate has a total reject according to PTS-RH 021 :2012 of less than 20 %, and preferably less than 15 %.According to a second aspect illustrated herein, there is provided a paper or paperboard based packaging laminate comprising:a multiply paper or paperboard substrate comprisinga first outermost ply comprising at least 70 wt% bleached kraft pulp or hardwood pulp based on the dry weight of the ply, anda second outermost ply comprising at least 70 wt% unbleached kraft pulp and / or high yield pulp based on the dry weight of the ply, andoptionally a mid ply arranged between the first and second outermost plies, said mid ply comprising at least 70 wt% unbleached kraft pulp and / or high yield pulp, and optionally 1-30 wt% bleached kraft pulp or hardwood pulp, based on the dry weight of the ply; anda barrier paper comprising at least 70 wt% cellulosic material based on the dry weight of the barrier paper, wherein the barrier paper has an oxygen transmission rate (OTR) measured according to the standard ASTM F 1927-20 at 50% relative humidity and 23 °C of less than 50 cc / m2 / 24h, and a cross direction (CD) strain at break measured according to the standard ISO 1924-3:2005 of at least 1.8 %;wherein the barrier paper is laminated to an outer surface of the second outermost ply of the multiply paper or paperboard substrate by a tie layer formed from a foamed adhesive composition.In some embodiments of the paper or paperboard based packaging laminate, the multiply paper or paperboard substrate is further defined as set out above with reference to the first aspect.In some embodiments of the paper or paperboard based packaging laminate, the barrier paper is further defined as set out above with reference to the first aspect.In some embodiments of the paper or paperboard based packaging laminate, the tie layer is further defined as set out above with reference to the first aspect.In some embodiments, the paper or paperboard based packaging laminate is further defined as set out above with reference to the first aspect.The paper or paperboard based packaging laminate may further be provided with polymeric sealing layer(s) on one side or on both sides thereof. The polymeric sealing layer(s) preferably serve as the outermost layers of the packaging laminate. The polymeric sealing layer(s) preferably provide liquid barrier properties and mechanical protection for the paper or paperboard based packaging laminate surface. At least one of the polymeric sealing layer(s) is preferably also heatsealable.Thus, in some embodiments, the method further comprises the step:d) applying a first polymeric sealing layer to the barrier paper side of the laminate.In some embodiments, the method further comprises the step:e) applying a second polymeric sealing layer to the paper or paperboard substrate side of the laminate.The polymeric sealing layer(s) may of course interfere with repulpability but may still be required or desired in some applications. The polymeric sealing layer(s) may for example be applied by extrusion coating, film lamination or dispersion coating.The polymeric sealing layer(s) may comprise any of the thermoplastic polymers commonly used in protective and / or heat-sealable layers in paper or paperboard based packaging laminates in general or polymers used in liquid or food packaging board in particular. Examples include polyethylene (PE), polyethylene terephthalate (PET), polyethylene furanoate (PEF), polypropylene (PP), polyhydroxyalkanoates (PHA), polylactic acid (PLA), polyglycolic acid (PGA), starch and cellulose.In some embodiments, the first and / or second polymeric sealing layer comprises a polyolefin, preferably a polyethylene (PE). Polyethylenes, especially low density polyethylene (LDPE) and high density polyethylene (HDPE), are the most common and versatile polymers used in liquid or food packaging board. Modified PE such as ethylene and acrylic acid (EAA) copolymers may also be used. The polymers used are preferably manufactured from renewable materials.Thermoplastic polymers are useful since they can be conveniently processed by extrusion coating techniques to form very thin and homogenous films with good liquid barrier properties. In some embodiments, the additional polymer layer(s) comprise polypropylene or polyethylene. In preferred embodiments, the polymeric sealing layer(s) comprise polyethylene, more preferably LDPE or HDPE.In some embodiments, the polymeric sealing layer(s) are formed by extrusion coating of the polymer onto a surface of the paper or paperboard substrate or laminate. Extrusion coating is a process by which a molten plastic material is applied to a substrate to form a very thin, smooth and uniform layer. The coating can be formed by the extruded plastic itself, or the molten plastic can be used as an adhesive to laminate a solid plastic film onto the substrate. Common plastic resins used in extrusion coating include polyethylene (PE), polypropylene (PP), and polyethylene terephthalate (PET).The basis weight of each of the polymeric sealing layer(s) is preferably less than 50 g / m2. In order to achieve a continuous and substantially defect free film, a basis weight of the polymeric sealing layer of at least 8 g / m2, preferably at least 12 g / m2 is typically required. In some embodiments, the basis weight of the polymeric sealing layer is in the range of 8-50 g / m2, preferably in the range of 12-50 g / m2.Generally, while the products, polymers, materials, layers and processes are described in terms of "comprising” various components or steps, the products, polymers, materials, layers and processes can also “consist essentially of or "consist of the various components and steps.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

1. A method for manufacturing a paper or paperboard based packaging laminate, said method comprising:a) providing a multiply paper or paperboard substrate comprisinga first outermost ply comprising at least 70 wt% bleached kraft pulp or hardwood pulp based on the dry weight of the ply, anda second outermost ply comprising at least 70 wt% unbleached kraft pulp and / or high yield pulp based on the dry weight of the ply, andoptionally a mid ply arranged between the first and second outermost plies, said mid ply comprising at least 70 wt% unbleached kraft pulp and / or high yield pulp, and optionally 1-30 wt% bleached kraft pulp or hardwood pulp, based on the dry weight of the ply;b) providing a barrier paper comprising at least 70 wt% cellulosic material based on the dry weight of the barrier paper, wherein the barrier paper has an oxygen transmission rate (OTR) measured according to the standard ASTM F1927-20 at 50% relative humidity and 23 °C of less than 50 cc / m2 / 24h, and a cross direction (CD) strain at break measured according to the standard ISO 1924-3:2005 of at least 1.8 %; andc) laminating the barrier paper to an outer surface of the second outermost ply of the multiply paper or paperboard substrate using a foamed adhesive composition, which forms a tie layer between the barrier paper and the outer surface of the second outermost ply.

2. The method according to any one of the preceding claims, wherein the multiply paper or paperboard substrate has a total grammage in the range of 100-400 g / m2.

3. The method according to any one of the preceding claims, wherein the multiply paper or paperboard substrate has a density in the range of 300-650 kg / m3, preferably in the range of 300-600 kg / m3, and more preferably in the range of 300-550 kg / m3.

4. The method according to any one of the preceding claims, wherein the unbleached kraft pulp and / or high yield pulp of the second outermost ply and / or the mid ply is chemi-thermomechanical pulp (CTMP) or high-temperature chemithermomechanical pulp (HT-CTMP), preferably softwood CTMP or softwood HT-CTMP.

5. The method according to any one of the preceding claims, wherein the second outermost ply and / or the mid ply comprises 0.1-10 wt%, preferably 0.15-5 wt%, of a strength enhancement agent based on the dry weight of the ply.

6. The method according to any one of the preceding claims, wherein the outer surface of the second outermost ply has a Bendtsen roughness of at least 300 ml / min, preferably at least 400 ml / min, at least 500 ml / min, at least 600 ml / min, at least 700 ml / min, or at least 800 ml / min, according to standard ISO 8791-2.

7. The method according to any one of the preceding claims, wherein the grammage of the barrier paper is in the range of 18-120 g / m2, preferably in the range of 25-80 g / m2, and more preferably in the range of 25-60 g / m2.

8. The method according to any one of the preceding claims, wherein the barrier paper has a density in the range of 800-1500 kg / m3, preferably in the range of 850-1050 kg / m3.

9. The method according to any one of the preceding claims, wherein the barrier paper further comprises 0.1-10 wt%, preferably 0.15-5 wt%, of a strength enhancement agent based on the dry weight of the barrier paper.

10. The method according to any one of the preceding claims, wherein the barrier paper is polymer coated, mineral coated, and / or metallized.

11. The method according to any one of the preceding claims, wherein the barrier paper has a cross direction (CD) strain at break measured according to the standard ISO 1924-3:2005 of at least 2 %, preferably at least 2.5 %, and more preferably at least 3 %.

12. The method according to any one of the preceding claims, wherein the grammage of the formed tie layer is in the range of 0.5-15 g / m2, preferably in the range of 0.5-12 g / m2, and more preferably in the range of 1-8 g / m2, based on dry weight.

13. The method according to any one of the preceding claims, wherein the foamed adhesive composition is water-based.

14. The method according to any one of the preceding claims, wherein the foamed adhesive composition comprises a polyvinyl alcohol (PVOH).

15. The method according to any one of the preceding claims, wherein the foamed adhesive composition has a foam density in the range of 0.1-0.95 kg / dm3 preferably in the range of 0.2-0.85 kg / dm3, and more preferably in the range of 0.2-0.75 kg / dm3.

16. The method according to any one of the preceding claims, wherein the obtained paper or paperboard based packaging laminate has an oxygen transmission rate (OTR), measured according to the standard ASTM F1927-20 at 50% relative humidity and 23 °C, of less than 30 cc / m2 / 24h, preferably less than 20 cc / m2 / 24h, more preferably less than 10 cc / m2 / 24h, and most preferably less than 5 cc / m2 / 24h.

17. The method according to any one of the preceding claims, wherein the obtained paper or paperboard based packaging laminate has a bending resistance index of at least 5 Nm6 / kg3 according to standard ISO 2493.

18. The method according to any one of the preceding claims, wherein the obtained paper or paperboard based packaging laminate comprises more than 70 wt%, preferably more than 75 wt%, more preferably more than 80 wt%, and most preferably more than 85 wt%, of cellulose-based material, based on the dry weight of the paper or paperboard based packaging laminate.

19. The method according to any one of the preceding claims, wherein the obtained paper or paperboard based packaging laminate has a total reject according to PTS-RH 021 :2012 of less than 20 %, and preferably less than 15 %.

20. A paper or paperboard based packaging laminate comprising:a multiply paper or paperboard substrate comprisinga first outermost ply comprising at least 70 wt% bleached kraft pulp or hardwood pulp based on the dry weight of the ply, anda second outermost ply comprising at least 70 wt% unbleached kraft pulp and / or high yield pulp based on the dry weight of the ply, andoptionally a mid ply arranged between the first and second outermost plies, said mid ply comprising at least 70 wt% unbleached kraft pulp and / or high yield pulp, and optionally 1-30 wt% bleached kraft pulp or hardwood pulp, based on the dry weight of the ply; anda barrier paper comprising at least 70 wt% cellulosic material based on the dry weight of the barrier paper, wherein the barrier paper has an oxygen transmission rate (OTR) measured according to the standard ASTM F1927-20 at 50% relative humidity and 23 °C of less than 50 cc / m2 / 24h, and a cross direction (CD) strain at break measured according to the standard ISO 1924-3:2005 of at least 1.8 %; wherein the barrier paper is laminated to an outer surface of the second outermost ply of the multiply paper or paperboard substrate by a tie layer formed from a foamed adhesive composition.