Method for producing paper or paperboard-based packaging laminates

Abstract

The present invention relates to a method of making a paper or paperboard based packaging laminate comprising: a) providing a paper or paperboard substrate; b) providing a microfibrillated cellulose (MFC) membrane comprising at least 50% by weight of MFC, based on the dry weight of the MFC membrane; and c) laminating a surface of the paper or paperboard substrate to a surface of the MFC membrane in a melt bonding process using a melt adhesive comprising at least 50% by weight of a water soluble thermoplastic polymer, based on the dry weight of the melt adhesive, wherein the melt adhesive is applied to the surface of the paper or paperboard substrate and / or the surface of the MFC membrane in a low-solvent or solvent-free form.

Description

[Technical Field]

[0001] The present disclosure relates to paper or paperboard based packaging laminates that include a microfibrillated cellulose (MFC) membrane as a barrier layer, and methods for making such laminates. [Background technology]

[0002] Coating paper and paperboard with plastics is often used to combine the mechanical properties of paper or paperboard with the barrier and sealing properties of a plastic film or layer. Adding even a relatively small amount of a suitable plastic material to paper or paperboard can provide the properties necessary to make the paper or paperboard suitable for many demanding applications, such as liquid or food packaging. In cardboard for liquid or food packaging, polyolefin coatings are frequently used as liquid barrier layers, heat-sealing layers, and adhesives. However, recycling such polymer-coated cardboard is difficult because it is difficult to separate the polymer from the fibers.

[0003] Furthermore, in many cases, the water vapor barrier properties of polymer-coated paper or paperboard remain insufficient unless the coating layer is thick or a combination of different polymer coating layers is used. Therefore, to ensure high water vapor barrier properties, polymer-coated paper or paperboard is often combined with one or more layers of aluminum foil. The aluminum foil is usually adhered to the laminate using one or more polymer adhesion layers. However, adding polymer and aluminum foil significantly increases costs, and the combination of the polymer layer and aluminum foil makes the material more difficult to recycle. Furthermore, due to its large carbon footprint, there is a desire to replace aluminum foil in paper- and paperboard-based packaging materials.

[0004] Aseptic packaging for shelf-stable products such as milk and juice is typically made from liquid or food packaging cardboard containing a multi-layer paperboard base substrate, an outermost layer of heat-sealable polyolefin (e.g., polyethylene, PE), and an innermost layer of polyolefin and aluminum. The aluminum foil layer required to provide water vapor and oxygen barrier properties is typically incorporated between cohesive layers of polyethylene, giving a PE / paperboard / PE / aluminum foil / PE structure.

[0005] Prior art efforts have attempted to replace aluminum foil with more environmentally friendly and / or recyclable solutions, but to date have been unsuccessful. For example, microfibrillated cellulose (MFC) membranes and coatings have been developed in which cellulose fibrils, obtained by fibrillating cellulose fibers, are dispersed in, for example, water and then reorganized and recombined to form dense films or coatings with excellent gas barrier properties. MFC membranes are typically laminated to paper or paperboard using a PE-based cling layer, similar to aluminum foil, but this cling layer limits the recyclability of the laminate. Conventional water-based adhesives, including, for example, water-soluble PVOH, have been considered as alternatives to PE-based cling layers. However, due to the moisture sensitivity of MFC membranes, conventional water-based adhesive compositions can cause dimensional stability issues, such as cockling, wrinkling, and shrinkage, in the MFC membrane and the resulting paper- or paperboard-based packaging laminate.

[0006] Thus, there remains a need for improved solutions to replace the combination of plastic film and aluminum foil in paper and paperboard based packaging materials while maintaining acceptable liquid and oxygen barrier properties, and at the same time, there is a need to replace the combination of plastic film and aluminum foil with alternatives that facilitate the repulping and recycling of post-consumer packaging materials. Summary of the Invention

[0007] An object of the present disclosure is to provide an alternative to the combination of plastic film and aluminum foil that is commonly used as a barrier layer to provide water vapor barrier properties to packaging materials such as cardboard for liquid or food packaging.

[0008] It is a further object of the present disclosure to provide a paper or paperboard based packaging laminate, such as cardboard for liquid or food packaging, that provides good water vapor barrier properties even at higher relative humidities and temperatures.

[0009] A further object of the present disclosure is to provide a method for treating a pulmonary artery disease (PA) comprising administering to a patient a pulmonary artery disease (PAG) having a PAG of 30 cc / m 2 or less, as measured in accordance with ASTM standard F1249-20 at 50% relative humidity and 23°C. 2 / 24h less than 5cc / m 2 The objective of the present invention is to provide a paper or paperboard based packaging laminate having a water vapor transmission rate (WVTR) of less than 1 / 24h.

[0010] It is a further object of the present disclosure to provide a paper or paperboard based packaging laminate, such as cardboard for liquid or food packaging, that includes a water vapor barrier layer that facilitates repulping of the cardboard compared to packaging laminates that use conventional combinations of plastic film and aluminum foil.

[0011] A further object of the present disclosure is to provide a paper or paperboard based packaging laminate having a reject rate of less than 20%, preferably less than 15%, according to PTS-RH 021:2012.

[0012] The above-mentioned objectives, as well as other objectives which will be realized by those skilled in the art in light of this disclosure, are achieved by various aspects of the present disclosure.

[0013] According to a first aspect presented herein, a) providing a paper or paperboard substrate; b) providing a microfibrillated cellulose (MFC) membrane comprising at least 50 wt. % MFC based on the dry weight of the MFC membrane; and c) laminating the surface of a paper or paperboard substrate to the surface of an MFC membrane in a melt bonding process using a melt adhesive comprising at least 50% by weight of a water-soluble thermoplastic polymer based on the dry weight of the melt adhesive, wherein the melt adhesive is applied to the surface of the paper or paperboard substrate and / or the surface of the MFC membrane in a low-solvent or solvent-free form.

[0010] A method for producing a paper or paperboard based packaging laminate is provided, comprising:

[0014] Paper generally refers to a material made from wood pulp or other fibrous substances containing cellulose fibers in thin sheets or webs and used for writing, drawing, or printing, or as a packaging material.

[0015] Paperboard generally refers to a strong and / or stiff, thick paper or board containing cellulose fibers used in boxes and other types of packaging. Paperboard can be bleached or unbleached, coated or uncoated, and produced in a variety of thicknesses, depending on the end-use requirements. Paperboard can be a single-ply material or a multi-ply material made up of two or more layers.

[0016] A paper or paperboard-based packaging laminate is a packaging material formed primarily from a paper or paperboard substrate. The paper or paperboard substrate can be made from pulp, including pulp derived from virgin fibers, such as mechanical pulp, chemical pulp, and / or thermomechanical pulp. Broken or recycled paper can also be included. In addition to the paper or paperboard substrate, a paper or paperboard-based packaging laminate can include additional layers or coatings designed to improve the performance and / or appearance of the packaging laminate.

[0017] Paper or paperboard based packaging laminates typically have a first outermost surface intended to function as the exterior or printed surface and a second outermost surface intended to function as the interior surface of the packaging container.

[0018] The paper or paperboard based packaging laminate obtained by the method of the present invention provides excellent water vapor barrier properties and, by providing a polymeric sealing layer as the outermost layer, can also provide excellent liquid barrier properties.

[0019] The paper or paperboard substrate used in the method of the present invention preferably has a density of at least 80 g / m 2 Basis weight and 800kg / m 3 It is a relatively thick paper or paperboard having a density less than 1000 MPa.

[0020] The paper or paperboard substrate may be even heavier. In some embodiments, the paper or paperboard substrate is at least 100 g / m 2 In some embodiments, the paper or paperboard substrate has a basis weight of at least 150 g / m 2 , 200g / m 2 , 250g / m 2 , 300g / m 2 , 350g / m 2 , or 400 g / m 2 The basis weight of the paper or paperboard substrate is preferably 1000 g / m 2 Less than 800g / m 2 Less than or 600g / m 2 Unless otherwise specified, basis weight is determined in accordance with ISO standard 536.

[0021] In some embodiments, the paper or paperboard substrate has a viscosity of 700 kg / m 3 less than 600 kg / m 3 Unless otherwise specified, density is determined in accordance with ISO standard 534.

[0022] The paper or paperboard substrate can be single-ply paperboard or multi-ply paperboard. In some embodiments, the paperboard substrate is multi-ply paperboard. In some embodiments, the paperboard substrate is multi-ply paperboard consisting of two or more plies. In some embodiments, the paperboard substrate is multi-ply paperboard consisting of three or more plies. In some embodiments, the paperboard substrate is multi-ply paperboard consisting of a low-density middle ply sandwiched between two high-density outer plies. The low-density middle ply is typically 750 kg / m 3 less than 700 kg / m 3 Less than 650 kg / m 3 Less than 600 kg / m 3 Less than 550 kg / m 3 Less than 500 kg / m 3 Less than 450 kg / m 3 Less than 400 kg / m 3 Less than or 350 kg / m 3 The dense outer layer may have a density less than 100 kg / m 2. The dense outer layer typically has a density at least 100 kg / m 2 less than the density of the middle layer. 3 higher, preferably at least 200 kg / m higher than the density of the intermediate layer 3 It has a high density.

[0023] In some embodiments, the paper or paperboard substrate is foam-molded paperboard. In some embodiments where the paperboard substrate is multi-ply paperboard, at least one of the plies, preferably the middle ply, is foam-molded.

[0024] In the construction of the paper or paperboard-based packaging laminate of the present invention, the MFC membrane prevents the migration of mineral oil-based compounds, allowing for the use of greater amounts of recycled fibers in the paper or paperboard substrate, such as fibers obtained from used beverage cartons. Thus, in some embodiments, the paper or paperboard substrate comprises at least 5% by weight recycled fibers, preferably at least 10% by weight recycled fibers.

[0025] In some embodiments, the paper or paperboard substrate further comprises a mineral coating layer on one or both of its major surfaces. In some embodiments, the mineral coating layer comprises 50-95% by weight of particulate mineral and 5-50% by weight of 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 kaolin. The binder may comprise a single binder or a combination of binders. The binder may preferably comprise a water-dispersible or water-soluble binder, or a combination thereof. In some embodiments, the water-dispersible binder may comprise a latex binder. In some embodiments, the water-soluble binder comprises starch, PVOH, cellulose derivatives (e.g., CMC, protein, or seaweed). An advantage of using a water-soluble binder is that the laminate may be more easily recycled. In some embodiments, the basis weight of the mineral coating layer is 4-30 g / m 2 in the range of 6 to 14 g / m 2 The range is.

[0026] Paper or paperboard substrates typically have high water vapor transmission rate (WVTR) values, i.e., poor water vapor transmission resistance, before the MFC membrane is laminated to the substrate. In some embodiments, the paper or paperboard substrate has a water vapor transmission rate (WVTR) of 100 g / m 2 as measured according to ASTM standard F1249-20 at 50% relative humidity and 23° C. 2 / 24h or more, typically 200g / m 2 / Over 24h, 300g / m 2 / 24h or more, or 1000g / m 2 / Has a water vapor transmission rate (WVTR) of over 24 hours.

[0027] Microfibrillated cellulose (MFC) membranes comprising at least 50 wt. % MFC, based on the dry weight of the MFC membrane, are provided as oxygen and water vapor barriers in paper or paperboard-based packaging laminates. In some embodiments, the MFC membranes comprise at least 70 wt. %, preferably at least 75 wt. %, and more preferably at least 80 wt. % MFC, based on the dry weight of the MFC membrane.

[0028] Microfibrillated cellulose (MFC), in the context of patent applications, refers to cellulose particles, fibers, or fibrils with a width or diameter between 20 nm and 1000 nm. Various methods exist for the production of MFC, including single-pass or multi-pass purification, prehydrolysis followed by purification, or shear dispersion or fibril release. One or several pretreatment steps are typically required to ensure that MFC production is both energy-efficient and sustainable. The cellulose fibers of the pulp used in MFC production can be natural or can be enzymatically or chemically pretreated, for example, to reduce the amount of hemicellulose or lignin. Cellulose fibers can also be chemically modified before fibrillation, so that the cellulose molecules contain functional groups other than (or more than) those found in the original cellulose. Such groups include, among others, carboxymethyl (CM), aldehyde and / or carboxyl groups (cellulose obtained by N-oxyl-mediated oxidation, e.g., "TEMPO"), or quaternary ammonium (cationic cellulose). After being modified or oxidized by any of the above methods, the degradation of the fibers into MFC becomes easier.

[0029] MFCs are made from wood cellulose fibers, both hardwood and softwood. They can also be made from microbial sources, agricultural fibers such as wheat straw pulp, bamboo, bagasse, or other non-wood fiber sources. They are preferably made from pulp, including pulp from virgin fibers, such as mechanical, chemical, and / or thermomechanical pulp. They can also be made from shredded or recycled paper.

[0030] In some embodiments, the MFC has a Schopper-Riegler (SR) value in the range of 80-100, preferably in the range of 85-100, and more preferably in the range of 90-100, according to ISO standard 5267-1.

[0031] In some embodiments, the MFC has a water retention value (WRV) of at least 230%, preferably at least 280%, according to ISO standard 23714:2014.

[0032] In some embodiments, the MFC membrane further comprises 1 to 30 wt. % unrefined or slightly refined cellulose pulp, based on the dry weight of the MFC membrane, the unrefined or slightly refined cellulose pulp having a Schopper-Riegler (SR) value according to ISO Standard 5267-1 in the range of 10 to 50, preferably in the range of 15 to 40, and more preferably in the range of 20 to 30. In some embodiments, the MFC membrane further does not comprise unrefined or slightly refined cellulose pulp.

[0033] In some embodiments, the MFC membrane further comprises 1-30 wt. % polyvinyl alcohol (PVOH), based on the dry weight of the MFC membrane. The PVOH can be PVOH or a derivative or analog thereof. The PVOH can be one type of PVOH or a mixture of two or more types of PVOH, e.g., with different degrees of hydrolysis or viscosities. The PVOH can have, for example, a degree of hydrolysis in the range of 80-99.9 mol.%, preferably in the range of 88-99.9 mol.%.

[0034] In some embodiments, the MFC membrane further comprises 1 to 30 wt. % nanoclay based on the dry weight of the MFC membrane.

[0035] In some embodiments, the MFC membrane further comprises 1-30 wt. % of a humectant, based on the dry weight of the MFC membrane. In some embodiments, the humectant is selected from the group consisting of a nonionic or anionic polyol, a sugar alcohol, and a wood hydrolyzate. In some embodiments, the humectant is selected from the group consisting of sorbitol, hemicellulose, xylan, and glucose.

[0036] To obtain an MFC membrane with low oxygen and water vapor permeability, suitable as a replacement for, for example, aluminum foil, the MFC membrane is preferably formed by cast molding (also called casting). The term "casting," when used in the context of MFC membrane formation, is a well-known term referring to a method of depositing an MFC suspension onto a support, typically an endless belt, by a contact or non-contact deposition and leveling method to form a wet web. Examples of such deposition and leveling methods include curtain coating / application, slot die casting, or a method in which the MFC suspension is administered by a spraying method or similar method and leveled with a doctor blade or rod. The deposited suspension is then dewatered and / or dried to obtain the MFC membrane. Dewatering is preferably constrained dewatering and drying, whereby the membrane is kept under tension in one or two directions. Thus, in some embodiments, the MFC membrane is a cast MFC membrane.

[0037] In some embodiments, the basis weight of the MFC membrane is 10 to 120 g / m 2 in the range of 15 to 80 g / m 2 in the range of 20 to 40 g / m 2 Unless otherwise specified, basis weight is determined in accordance with ISO standard 536.

[0038] In some embodiments, the MFC membrane has a thickness in the range of 7 to 170 μm, preferably in the range of 10 to 114 μm, and more preferably in the range of 13 to 57 μm.

[0039] In some embodiments, the MFC membrane has a flow rate of 700 to 1500 kg / m 3 , preferably 800 to 1500 kg / m 3 , and most preferably 900 to 1500 kg / m 3 Unless otherwise specified, density is determined in accordance with ISO standard 534.

[0040] In some embodiments, the MFC membrane has a flow resistance of 4 mN m, as determined in accordance with ISO Standard 1974. 2 / g, preferably less than 3.5 mN m 2 / g, more preferably less than 3 mN m 2 / g or less.

[0041] In some embodiments, the MFC membrane has a wet tensile strength retention of less than 70%, preferably less than 50%, more preferably less than 30%, e.g., in the range of 0-30% or 1-25%, according to ISO standard 3781:2011. Wet tensile strength retention is calculated as wet strength * 100 / dry strength. Samples for wet strength testing are immersed in distilled water at 40°C for 30 minutes.

[0042] In some embodiments, the MFC membrane has a permeability of 30 cc / m as measured according to ASTM standard F1927-20 at 50% relative humidity and 23°C. 2 / 24h less than 20cc / m 2 / 24h less than 10cc / m 2 / 24h, most preferably less than 5cc / m 2 / Has an oxygen transmission rate (OTR) of less than 24h.

[0043] In some embodiments, the MFC membrane has a water solubility of 30 g / m as measured according to ASTM standard F1249-20 at 50% relative humidity and 23° C. 2 / 24h less than 20g / m 2 / 24h or less, preferably 10g / m 2 / 24h, most preferably less than 5g / m 2 / 24h water vapor transmission rate (WVTR) of less than

[0044] The surface of the resulting paper or paperboard substrate is laminated to the surface of the resulting MFC membrane by a melt-bonding process using a melt adhesive containing at least 50% by weight of a water-soluble thermoplastic polymer, based on the dry weight of the melt adhesive, where the melt adhesive is applied to the surface of the paper or paperboard substrate and / or the surface of the MFC membrane in a low-solvent or solvent-free form. Melt adhesives (also called hot-melt adhesives or hot glues) are generally solid formulations based on thermoplastic polymers and typically contain no water or solvents. Melt adhesives are solid at room temperature but become activated when heated above their melting point. Once melted, the melt adhesive can be applied to the substrate in the molten state. The molten adhesive wets the substrate, penetrates the surface and cavities, and then hardens to enhance adhesive strength. This hardening process is typically very fast.

[0045] Lamination by the melt bonding process involves applying a melt adhesive, either in a molten or solid state, to the surface of the paper or paperboard substrate and / or the surface of the MFC membrane to be laminated, followed by melting, bringing the surfaces to be laminated into contact, and allowing the molten melt adhesive to harden, thereby forming a laminate in which the paper or paperboard substrate and the MFC membrane are bonded by the melt adhesive.

[0046] According to the present disclosure, the melt adhesive is applied in a low-solvent or solvent-free form. The term "low-solvent or solvent-free form" is used herein to mean that the melt adhesive is not applied to the surface of the paper or paperboard substrate and / or the surface of the MFC membrane as a solution or dispersion in water or other liquid solvent. The term "low-solvent or solvent-free form" as used herein should be interpreted as a form containing less than 10% by weight, preferably less than 8%, 6%, 4%, or 2% by weight of liquid solvent, based on the dry weight of the melt adhesive. In some preferred embodiments, the melt adhesive is applied to the surface of the paper or paperboard substrate and / or the surface of the MFC membrane in a form containing less than 2% by weight of liquid solvent, based on the dry weight of the melt adhesive. In some preferred embodiments, the melt adhesive is applied to the surface of the paper or paperboard substrate and / or the surface of the MFC membrane in a form that does not contain liquid solvent.

[0047] Because MFC membranes are generally sensitive to moisture, it is preferable to apply the hot melt adhesive in a low-solvent or solvent-free form. The use of conventional water-based adhesive compositions with MFC membranes can result in dimensional stability problems, cockling, wrinkling, and shrinkage in the MFC membrane and the resulting paper or paperboard-based packaging laminate.

[0048] The low-solvent or solvent-free form of the hot melt adhesive is preferably in the molten or solid state.

[0049] The molten adhesive can be preferably applied to the surface of a paper or paperboard substrate and / or the surface of an MFC membrane by extrusion coating. The applied molten adhesive can then be used to laminate the paper or paperboard substrate to the MFC membrane. The lamination can be applied directly in connection with the extrusion coating while the molten adhesive is still in a molten state. This process is called extrusion coating lamination. Thus, in some embodiments, the melt bonding process is extrusion coating lamination. Alternatively, it may be possible to cure the applied molten adhesive and then melt it again during lamination.

[0050] The solid state melt adhesive can be applied to the surface of the paper or paperboard substrate and / or the surface of the MFC membrane, for example, in the form of a solid melt adhesive film or solid particles of melt adhesive, which are then melted to the surface of the paper or paperboard substrate and / or the surface of the MFC membrane during lamination.

[0051] The melt adhesive is applied to the paper or paperboard substrate, or to the MFC membrane, or both. In some embodiments, the melt adhesive is applied to the MFC membrane. In some embodiments, the melt adhesive is applied only to the MFC membrane.

[0052] The hot melt adhesive can be applied as a single layer and / or as two or more layers onto the paper or paperboard substrate or onto the MFC membrane, for example by coextrusion. When the hot melt adhesive is applied as two or more layers, the basis weight and composition of the hot melt adhesive in the two or more layers can be the same or different.

[0053] An MFC membrane that contacts a paper or paperboard substrate via a molten adhesive can be subjected to various treatments to improve the adhesion between the MFC membrane and the paper or paperboard substrate. In some embodiments, an MFC membrane that contacts a paper or paperboard substrate via a molten adhesive is subjected to pressure, heat, and / or radiation to improve the adhesion between the MFC membrane and the paper or paperboard substrate.

[0054] The temperature can vary depending on the contact time and lamination pressure, but should typically be in the range of 40-250°C, preferably in the range of 60-150°C. The lamination pressure should be high enough to obtain good adhesion, but not so high that the bulk of the 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 heat can be provided, for example, by a heated nip or an extended nip.

[0055] The hot melt adhesive comprises one or more thermoplastic polymers. The hot melt adhesive may be composed of one or more thermoplastic polymers or may further comprise other additives to facilitate the coating process or to improve the properties of the hot melt adhesive.

[0056] The hot melt adhesives of the present disclosure comprise at least 50% by weight of water soluble thermoplastic polymer based on the dry weight of the hot melt adhesive, hi some embodiments, the hot melt adhesive comprises at least 70%, preferably at least 75%, at least 80%, at least 85%, at least 90%, or at least 95% by weight of water soluble thermoplastic polymer based on the dry weight of the hot melt adhesive.

[0057] Having a melt adhesive that includes at least 50% by weight of a water soluble thermoplastic polymer facilitates separation of the MFC membrane, paper or paperboard substrate, and optional additional plastic layers during repulping.

[0058] In some embodiments, the water soluble thermoplastic polymer is selected from the group consisting of polyvinyl alcohol (PVOH), a water soluble thermoplastic modified polysaccharide, and a water soluble thermoplastic acrylic copolymer.

[0059] In some embodiments, the water soluble thermoplastic polymer is selected from the group consisting of polyvinyl alcohol (PVOH), hydroxypropyl cellulose (HPC), hydroxypropyl methylcellulose (HPMC), hydroxypropyl methylcellulose acetate succinate (HPMCAS), and methacrylic acid-methyl methacrylate copolymers, and combinations thereof.

[0060] In a preferred embodiment, the water-soluble thermoplastic polymer is PVOH. The PVOH can be PVOH or a derivative or analog thereof. The PVOH can be modified with, for example, silanol, carboxyl, or ethylene groups to provide better adhesion to the MFC membrane. Thus, in some embodiments, the water-soluble thermoplastic polymer is PVOH, optionally modified with silanol, carboxyl, or ethylene groups.

[0061] The PVOH can be a single type of PVOH or can include a mixture of two or more types of PVOH, e.g., with different degrees of hydrolysis or viscosities. The PVOH can have a degree of hydrolysis ranging from 50 to 99.9 mol%, preferably from 80 to 99.9 mol%, and more preferably from 88 to 99.9 mol%. In some embodiments, the PVOH has an average molecular weight Mw ranging from 15,000 to 150,000 g / mol.

[0062] In some embodiments, the water soluble thermoplastic polymer has a viscosity of 1.1 to 1.6 g / cm 3 Unless otherwise specified, polymer density is determined in accordance with ISO 1183-1:2019.

[0063] In some embodiments, the water-soluble thermoplastic polymer has a melting point in the range of 100 to 320° C., preferably in the range of 120 to 240° C., and more preferably in the range of 140 to 220° C. Unless otherwise specified, melting points are determined according to ISO 11357-3:2018.

[0064] In some embodiments, the water-soluble thermoplastic polymer has a glass transition temperature (T) of less than 80°C, preferably less than 60°C, for example in the range of 20 to 65°C. g )

[0065] In some embodiments, the hot melt adhesive has a melting point in the range of 100 to 320°C, preferably in the range of 120 to 240°C, and more preferably in the range of 140 to 220°C.

[0066] The water soluble thermoplastic polymer of the hot melt adhesive is at least partially soluble in cold or hot water, for example, at temperatures below or above 100° C., for a given period of time. In some embodiments, the water soluble thermoplastic polymer of the hot melt adhesive is completely soluble in cold or hot water, for example, at temperatures below or above 100° C., for a given period of time.

[0067] The solubility of the water-soluble thermoplastic polymer of the hot melt adhesive allows the hot melt adhesive to dissolve, completely or partially disintegrate, or substantially weaken when subjected to water, such as during repulping.

[0068] In some embodiments, the water-soluble thermoplastic polymer has a solubility in distilled water of at least 60%, preferably at least 70%, and more preferably at least 80% after 30 minutes at 40° C. The solubility is about 20 g / m 2 The dissolution rate is determined by preparing a thin film having a basis weight of 0.1% and adding pieces of the film to a calculated amount of distilled water to achieve a concentration of 0.1% by weight. Dissolution is achieved under gentle agitation, and the solubility after a given dissolution time is determined using UV absorbance based on a completely dissolved sample.

[0069] In some embodiments, the hot melt adhesive further comprises up to 50% by weight of microfibrillated cellulose (MFC), thermoplastic starch, or thermoplastic cellulose, based on the dry weight of the hot melt adhesive.

[0070] In some embodiments, the hot melt adhesive further comprises up to a total of 30% by weight of other water soluble or non-water soluble additives, based on the dry weight of the hot melt adhesive.

[0071] In some embodiments, the hot melt adhesive comprises a plasticizer added to the hot melt adhesive to improve the processability of the hot melt adhesive by extrusion coating and to improve the elasticity and reduce brittleness of the resulting hot melt adhesive layer, hi some embodiments, the hot melt adhesive comprises up to 30 wt % plasticizer based on the dry weight of the hot melt adhesive.

[0072] The plasticizer is preferably a water-soluble plasticizer. In some embodiments, the plasticizer is an organic compound containing multiple hydroxyl groups, such as a diol, triol, or other polyol, or a sugar alcohol. In some embodiments, the plasticizer is selected from the group consisting of glycerol, xylitol, sorbitol, maltitol, ethylene glycol, propylene glycol, butanediol, pentaerythritol, trimethylolpropane, polyethylene glycol, polypropylene glycol, xylose, dextrin, and combinations thereof. In some embodiments, the plasticizer is a sugar alcohol. In some embodiments, the plasticizer is sorbitol. In some embodiments, the hot melt adhesive comprises 1 to 30 wt %, preferably 1 to 20 wt %, and more preferably 1 to 15 wt %, of the plasticizer based on the dry weight of the hot melt adhesive.

[0073] The water-insoluble additives can include, for example, water-insoluble fillers such as nanoclays.

[0074] The total amount of other water-soluble or water-insoluble additives preferably does not exceed 30% by weight based on the dry weight of the hot melt adhesive, as this may impair the adhesive properties of the hot melt adhesive.

[0075] In some embodiments, the basis weight of the hot melt adhesive is between 2 and 30 g / m 2 in the range of 3 to 25 g / m 2 in the range of 4 to 20 g / m 2 in the range of 10 to 20 g / m 2 is in the range.

[0076] In some embodiments, films formed from the hot-melt adhesive have a wet tensile strength retention of less than 20%, preferably less than 10%, more preferably less than 5%, e.g., in the range of 0-10% or 0-5%, according to ISO Standard 3781:2011. Wet tensile strength retention is calculated as wet strength * 100 / dry strength. Samples for wet strength testing are immersed in distilled water at 40°C for 30 minutes.

[0077] In some embodiments, the hot melt adhesive is in the form of a foam. In some embodiments, the hot melt adhesive in the form of a foam has a viscosity of 50 to 900 kg / m 3 range, preferably 100 to 800 kg / m 3 range, more preferably 150 to 750 kg / m 3 It has a density in the range of

[0078] The paper or paperboard-based packaging laminate may further be provided with one or more polymeric sealing layer(s) on one or both sides. The polymeric sealing layer(s) preferably function as the outermost layer(s) of the packaging laminate. The polymeric sealing layer(s) preferably provide liquid barrier properties and mechanical protection to the surface of the paper or paperboard-based packaging laminate. At least one of the polymeric sealing layer(s) is preferably also heat-sealable.

[0079] Thus, in some embodiments, the method further comprises: d) applying a first polymer sealing layer to the MFC side of the stack.

[0080] In some embodiments, the method further comprises: e) applying a second polymeric sealing layer to the paper or paperboard substrate side of the laminate.

[0081] The polymeric sealing layer(s) may, of course, impair repulpability, but may still be necessary or desirable in some applications. The polymeric sealing layer(s) may be applied, for example, by extrusion coating, film lamination, or dispersion coating.

[0082] The polymeric seal layer(s) may generally comprise any of the thermoplastic polymers commonly used for protective and / or heat seal layers in paper or paperboard based packaging laminates, or particularly for cardboard used in liquid or food packaging. Examples include polyethylene (PE), polyethylene terephthalate (PET), polyethylene furanoate (PEF), polypropylene (PP), polyhydroxyalkanoates (PHAs), polylactic acid (PLA), polyglycolic acid (PGA), starch, and cellulose.

[0083] In some embodiments, the first and / or second polymer sealing layers comprise a polyolefin, preferably polyethylene (PE). Polyethylene, particularly low-density polyethylene (LDPE) and high-density polyethylene (HDPE), is the most common and versatile polymer used in cardboard for liquid or food packaging. Preferably, the polymer used is made from renewable materials.

[0084] Thermoplastic polymers are useful because they can be easily processed by extrusion coating techniques to form very thin, uniform films with good liquid barrier properties. In some embodiments, the additional polymer layer comprises polypropylene or polyethylene. In preferred embodiments, the polymer sealing layer(s) comprises polyethylene, more preferably LDPE or HDPE.

[0085] In some embodiments, the polymer sealing layer(s) are formed by extrusion coating a polymer onto the surface of a paper or paperboard substrate or laminate. Extrusion coating is a process in which molten plastic material is applied to a substrate to form a very thin, smooth, and uniform layer. The coating can be formed from 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).

[0086] The basis weight of each of the polymer sealing layer(s) is preferably 50 g / m 2 To achieve a continuous, substantially defect-free film, the basis weight of the polymeric sealing layer is typically at least 8 g / m 2 , preferably at least 12 g / m 2 In some embodiments, the basis weight of the polymeric sealing layer is between 8 and 50 g / m 2 in the range of 12 to 50 g / m 2 The range is.

[0087] Some examples of possible embodiments are given below: - Polyolefin / Paperboard substrate / Melting adhesive / MFC film / Polyolefin - Paperboard substrate / melt adhesive / melt adhesive / MFC film / polyolefin - Polyolefin / Paperboard substrate / Mineral coating / Hot melt adhesive / MFC film / Polyolefin - Paperboard substrate / melt adhesive / MFC film / polyolefin - Ink receiving layer / Paperboard substrate / Melting adhesive / MFC film / Polyolefin

[0088] The resulting paper or paperboard based packaging laminate has high resistance to oxygen and water vapor, which makes the packaging laminate of the present invention an interesting and viable alternative to traditional materials that use an aluminum foil layer.

[0089] In some embodiments, the resulting paper or paperboard based packaging laminate has a moisture content of 30 cc / m as measured according to ASTM standard F1927-20 at 50% relative humidity and 23°C. 2 / 24h less than 20cc / m 2 / 24h less than 10cc / m 2 / 24h, most preferably less than 5cc / m 2 / Has an oxygen transmission rate (OTR) of less than 24h.

[0090] In some embodiments, the resulting paper or paperboard based packaging laminate has a modulus of at least 30 g / m 2 as measured according to ASTM standard F1249-20 at 50% relative humidity and 23°C. 2 / 24h less than 20g / m 2 / 24h or less, preferably 10g / m 2 / 24h, most preferably less than 5g / m 2 / 24h water vapor transmission rate (WVTR) of less than

[0091] The packaging laminates of the present invention are an interesting and viable alternative to conventional materials that use metal or metal-based layers, such as aluminum foil layers, and thus, in some embodiments, the resulting paper or paperboard-based packaging laminate does not include a metal or metal-based layer.

[0092] According to a second aspect presented herein, there is provided a method for manufacturing a container, in particular a container for liquid or food packaging, the method comprising the steps of: a) producing a paperboard-based packaging laminate according to the first aspect described herein; and b) Converting paperboard-based packaging laminates into containers Includes.

[0093] Converting a paperboard-based packaging laminate into a container may typically include printing, cutting, scoring, folding, and sealing the packaging laminate to form a container, and optionally attaching a lid, cap, or other closure to the container. The container may advantageously be for the aseptic packaging of dry or semi-moist foods, or liquids.

[0094] In some embodiments, the MFC membrane faces the inside of the vessel.

[0095] According to a third aspect presented herein, - a paper or paperboard substrate, and - a microfibrillated cellulose (MFC) membrane containing at least 50 wt. % MFC based on the dry weight of the MFC membrane Including, A surface of a paper or paperboard substrate is laminated to a surface of the MFC membrane by a melt adhesive comprising at least 50% by weight of a water-soluble thermoplastic polymer based on the dry weight of the melt adhesive; A paper or paperboard based packaging laminate is provided.

[0096] In some embodiments, the MFC membrane of the paper or paperboard based packaging laminate is further defined herein with reference to the first aspect.

[0097] In some embodiments, the hot melt adhesive of the paper or paperboard based packaging laminate is further defined herein with reference to the first aspect.

[0098] In some embodiments, the paper or paperboard based packaging laminate comprises: - A first polymer sealing layer applied to the MFC side of the laminate Further includes:

[0099] In some embodiments, the paper or paperboard based packaging laminate comprises: - a second polymeric sealing layer applied to the paper or paperboard substrate side of the laminate; Further includes:

[0100] In some embodiments, the first and / or second polymeric sealing layers comprise a polyolefin, preferably polyethylene (PE).

[0101] In some embodiments, the paper or paperboard based packaging laminate is further defined herein with reference to the first aspect.

[0102] A paper or paperboard-based packaging laminate is a packaging material formed primarily from cellulose-based materials. In the paper or paperboard-based packaging laminate of the present invention, both the paper or paperboard substrate and the MFC membrane are formed primarily 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 materials based on the dry weight of the paperboard-based packaging laminate.

[0103] The paper or paperboard-based packaging laminate of the present invention can provide an alternative to conventional materials using aluminum foil layers and can be more easily repulped and recycled. The hot-melt adhesive of the paper or paperboard-based packaging laminate of the present invention comprises at least 50% by weight of a water-soluble thermoplastic polymer on a dry weight basis. The water-soluble thermoplastic polymer disposed between and in contact with the paper or paperboard substrate and the MFC membrane has been found to effectively enable separation of the MFC membrane from the paper or paperboard substrate during repulping. In some embodiments, the paper or paperboard-based packaging laminate has a total reject rate of less than 20%, preferably less than 15%, in accordance with PTS-RH 021:2012.

[0104] According to a further aspect presented herein, there is provided a container, in particular a container for liquid or food packaging, obtainable by the method according to the second aspect presented herein. The container may advantageously be a container for the aseptic packaging of dry or semi-moist food, or liquid.

[0105] Generally, products, polymers, materials, layers, and processes are described in terms of "comprising" various components or steps, but the products, polymers, materials, layers, and processes can also be said to "consist essentially of" or "consist of" the various components and steps.

[0106] While the present invention has been described with reference to various exemplary embodiments, it will be apparent to those skilled in the art that various modifications can be made and equivalents can be substituted for elements of the present invention without departing from the scope of the invention. In addition, many modifications can be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope of the invention. Therefore, it is not intended that the invention be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but rather, it is intended to include all embodiments falling within the scope of the appended claims.

Claims

1. 1. A method for producing a paper or paperboard based packaging laminate, comprising: a) providing a paper or paperboard substrate; b) providing a microfibrillated cellulose (MFC) membrane comprising at least 50 wt. % MFC, based on the dry weight of the MFC membrane; and c) laminating a surface of a paper or paperboard substrate to a surface of an MFC membrane in a melt bonding process using a melt adhesive comprising at least 50% by weight of a water soluble thermoplastic polymer based on the dry weight of the melt adhesive, wherein the melt adhesive is applied to the surface of the paper or paperboard substrate and / or the surface of the MFC membrane in a low-solvent or solvent-free form. A method comprising:

2. 2. The method of claim 1, wherein the MFC membrane comprises at least 70 wt.%, preferably at least 75 wt.%, more preferably at least 80 wt.% MFC, based on the dry weight of the MFC membrane.

3. 3. The method according to claim 1 or 2, wherein the MFC has a Schopper-Riegler (SR) value in the range of 80 to 100, preferably in the range of 85 to 100, more preferably in the range of 90 to 100, according to ISO standard 5267-1.

4. 4. The method according to any one of claims 1 to 3, wherein the MFC has a water retention value (WRV) according to ISO standard 23714:2014 of at least 230%, preferably at least 280%.

5. 5. The method according to any one of claims 1 to 4, wherein the MFC membrane further comprises 1 to 30 wt. % of unrefined or slightly refined cellulose pulp, based on the dry weight of the MFC membrane, and the unrefined or slightly refined cellulose pulp has a Schopper-Riegler (SR) value in the range of 10 to 50, preferably in the range of 15 to 40, more preferably in the range of 20 to 30, according to ISO standard 5267-1.

6. 6. The method of any one of claims 1 to 5, wherein the MFC membrane further comprises 1 to 30 wt% polyvinyl alcohol (PVOH), based on the dry weight of the MFC membrane.

7. 7. The method according to claim 1, wherein the MFC membrane is a cast MFC membrane.

8. The basis weight of the MFC membrane is 10 to 120 g / m ２ in the range of 15 to 80 g / m ２ in the range of 20 to 40 g / m ２ 8. The method of claim 1, wherein the solubility of the solubility of the solubility of the

9. 9. The method according to any one of claims 1 to 8, wherein the MFC membrane has a thickness in the range of 7 to 170 μm, preferably in the range of 10 to 114 μm, more preferably in the range of 13 to 57 μm.

10. MFC membrane: 700 to 1500 kg / m ３ , preferably 800 to 1500 kg / m ３ , most preferably 900 to 1500 kg / m ３ 10. The method of claim 1, wherein the density is in the range of

11. The MFC membrane has a resistance of 4 mN m, determined in accordance with ISO standard 1974. ２ / g, preferably less than 3.5 mN m ２ / g, more preferably less than 3 mN m ２ 11. The method of claim 1, wherein the film has a tear index (geometric mean) of less than 1 / g.

12. 12. The method according to any one of claims 1 to 11, wherein the MFC membrane has a wet tensile strength retention according to ISO standard 3781:2011 of less than 70%, preferably less than 50%, more preferably less than 30%.

13. The MFC membrane has a permeability of 30 cc / m as measured in accordance with ASTM standard F1927-20 at 50% relative humidity and 23°C. ２ / 24h less, preferably 20cc / m ２ / 24h or less, more preferably 10cc / m ２ / 24h or less, most preferably 5cc / m ２ 13. The method of claim 1, wherein the composition has an oxygen transmission rate (OTR) of less than 1 / 24h.

14. The MFC membrane has a water solubility of 30 g / m2 as measured according to ASTM standard F1249-20 at 50% relative humidity and 23°C. ２ / 24h or less, preferably 20g / m ２ / 24h or less, more preferably 10g / m ２ / 24h or less, most preferably 5g / m ２ 14. The method of claim 1, wherein the composition has a water vapor transmission rate (WVTR) of less than 1 / 24h.

15. 15. The method of any one of claims 1 to 14, wherein the hot melt adhesive comprises at least 70 wt%, preferably at least 90 wt%, of water soluble thermoplastic polymer, based on the dry weight of the hot melt adhesive.

16. 16. The method of any one of claims 1 to 15, wherein the water-soluble thermoplastic polymer is selected from the group consisting of polyvinyl alcohol (PVOH), water-soluble thermoplastic modified polysaccharides, and water-soluble thermoplastic acrylic copolymers.

17. 17. The method of any one of claims 1 to 16, wherein the water soluble thermoplastic polymer is selected from the group consisting of polyvinyl alcohol (PVOH), hydroxypropyl cellulose (HPC), hydroxypropyl methylcellulose (HPMC), hydroxypropyl methylcellulose acetate succinate (HPMCAS), and methacrylic acid-methyl methacrylate copolymers, and combinations thereof.

18. 18. The method of any one of claims 1 to 17, wherein the water-soluble thermoplastic polymer is PVOH, optionally modified with silanol, carboxyl, or ethylene groups.

19. A method according to any one of the preceding claims, wherein the hot melt adhesive has a melting point in the range of 100 to 320°C, preferably in the range of 120 to 240°C, more preferably in the range of 140 to 220°C.

20. 20. The method of any one of claims 1 to 19, wherein the hot melt adhesive further comprises up to 50 wt. % of microfibrillated cellulose (MFC), thermoplastic starch, or thermoplastic cellulose, based on the dry weight of the hot melt adhesive.

21. 21. The method of any one of claims 1 to 20, wherein the hot melt adhesive further comprises up to 30% by weight of a plasticizer, based on the dry weight of the hot melt adhesive.

22. The basis weight of the melt adhesive is 2 to 30 g / m ２ in the range of 3 to 25 g / m ２ in the range of 4 to 20 g / m ２ in the range of 10 to 20 g / m ２ 22. The method of any one of claims 1 to 21, wherein the

23. 23. The method of any one of claims 1 to 22, wherein the film formed from the hot melt adhesive has a wet tensile strength retention of less than 20%, preferably less than 10%, more preferably less than 5%, according to ISO standard 3781:2011.

24. 24. The method of any one of claims 1 to 23, wherein the hot melt adhesive is in the form of a foam.

25. 25. The method according to any one of claims 1 to 24, wherein the melt bonding process is extrusion coating lamination.

26. d) applying a first polymeric sealing layer to the MFC side of the laminate; 26. The method of any one of claims 1 to 25, further comprising:

27. e) applying a second polymeric sealing layer to the paper or paperboard substrate side of the laminate; 26. The method of any one of claims 1 to 25, further comprising:

28. 28. The method of claim 26 or 27, wherein the first and / or second polymeric sealing layer comprises a polyolefin, preferably polyethylene (PE).

29. 29. The method of any one of claims 1 to 28, wherein the resulting paper or paperboard based packaging laminate does not include a metal layer or a metal-based layer.

30. The resulting paper or paperboard based packaging laminate has a moisture content of 30 cc / m as measured according to ASTM standard F1927-20 at 50% relative humidity and 23°C. ２ / 24h less, preferably 20cc / m ２ / 24h or less, more preferably 10cc / m ２ / 24h or less, most preferably 5cc / m ２ 30. The method of claim 1, wherein the composition has an oxygen transmission rate (OTR) of less than 1 / 24h.

31. The resulting paper or paperboard based packaging laminate has a packing density of 30 g / m2 as measured according to ASTM standard F1249-20 at 50% relative humidity and 23°C. ２ / 24h or less, preferably 20g / m ２ / 24h or less, more preferably 10g / m ２ / 24h or less, most preferably 5g / m ２ 31. The method of claim 1, wherein the composition has a water vapor transmission rate (WVTR) of less than 1 / 24h.

32. 1. A method for producing a container, in particular a packaging container for liquids or food products, comprising the steps of: a) producing a paper or paperboard based packaging laminate according to any one of claims 1 to 31, and b) Converting the paperboard-based packaging laminate into a container A method comprising:

33. 33. The method of claim 32, wherein the MFC membrane faces the inside of the container.

34. A paper or paperboard based packaging laminate comprising: - Paper or paperboard substrates, and - Microfibrillated cellulose (MFC) membranes comprising at least 50% by weight of MFC based on the dry weight of the MFC membrane. Including, a surface of a paper or paperboard substrate is laminated to a surface of the MFC membrane by a melt adhesive comprising at least 50% by weight of a water soluble thermoplastic polymer based on the dry weight of the melt adhesive; Paper or paperboard based packaging laminates.

35. 35. The paper or paperboard based packaging laminate of claim 34, wherein the MFC membrane is further defined as described in any one of claims 2 to 14.

36. 36. The paper or paperboard based packaging laminate of claim 34 or 35, wherein the hot melt adhesive is further defined as in any one of claims 15 to 24.

37. - a first polymer sealing layer applied to the MFC side of the laminate 37. The paper or paperboard based packaging laminate of any one of claims 34 to 36, further comprising:

38. - a second polymeric sealing layer applied to the paper or paperboard substrate side of the laminate; 38. The paper or paperboard based packaging laminate of any one of claims 34 to 37, further comprising:

39. 39. A paper or paperboard based packaging laminate according to claim 37 or 38, wherein the first and / or second polymeric sealing layer comprises a polyolefin, preferably polyethylene (PE).

40. 40. The paper or paperboard based packaging laminate of any one of claims 34 to 39, wherein the paper or paperboard based packaging laminate is further defined as described in any one of claims 29 to 31.

41. 41. The paper or paperboard based packaging laminate according to any one of claims 34 to 40, wherein the paper or paperboard based packaging laminate comprises more than 70% by weight, preferably more than 75% by weight, more preferably more than 80% by weight, and most preferably more than 85% by weight of cellulose-based material, based on the dry weight of the paperboard based packaging laminate.

42. 42. The paper or paperboard based packaging laminate according to any one of claims 34 to 41, wherein the paper or paperboard based packaging laminate has a total rejection according to PTS-RH 021:2012 of less than 20%, preferably less than 15%.

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