Method for manufacturing a laminate and laminate

Abstract

The present invention relates to a method for manufacturing a laminate comprising a paper or paperboard substrate and a microfibrillated cellulose (MFC) film. A first web comprising a substrate of paper or paperboard is provided. A second web of the MFC film is provided, and the MFC film has a) an MFC content between 50 and 100 wt% based on the total dry weight, b) a moisture content of 5 to 20 wt%, and c) a ratio of the machine direction tensile index to the cross direction tensile index of 0.8 to 1.4. The MFC film is further dried until it has a moisture content of less than 4 wt%. The first web and the second web are joined using at least one adhesive layer provided between the webs after further drying to form a laminate. The MFC film has a moisture content of less than 4 wt% at the time of joining. The present invention also relates to the laminate and a packaging material comprising the laminate.

Description

Technical Field

[0001] The present disclosure relates to a method for manufacturing a laminate comprising a paper or cardboard substrate and a barrier film, wherein the barrier film is a microfibrillated cellulose (MFC) film. Further, the present disclosure relates to a laminate comprising a paper or cardboard substrate and an MFC film, a packaging material comprising the laminate, and the use of the laminate in a packaging material.

Background Art

[0002] In many applications of paper and cardboard packaging, barrier properties against oxygen, grease, water vapor and / or aroma are required. However, paper and cardboard substrates inherently do not have these properties. Most commonly, the barrier properties of paper and cardboard substrates are created by adding one or more barrier coatings and / or laminated barrier layers based on plastics or other non-renewable materials. The disadvantages of these coatings and barrier layers are that, since they use non-renewable raw materials, the carbon dioxide emissions of the materials may increase, and paper and cardboard that are originally biodegradable may become non-biodegradable and, in some cases, non-recyclable. Furthermore, in order to improve the barrier including a barrier coating and / or a laminated barrier layer based on plastic or other non-renewable materials, it is usually necessary to increase the amount of the polymer and / or various polymer layers used. Therefore, it becomes even more difficult to decompose and recycle the fiber portion of a paper or cardboard substrate provided with such an improved barrier.

[0003] Recently, microfibrillated cellulose (MFC) films have been developed in which cellulose nanofibers obtained by fibrillation of cellulose fibers are suspended, for example, in water and then reorganized and recombined to form a dense film having barrier properties such as oxygen, aroma and grease barrier properties. MFC films are not only recyclable and biodegradable, but also based on renewable raw materials.

[0004] Laminates comprising a paper or cardboard substrate and an MFC film are disclosed for use, for example, in packaging materials or applications such as liquid or food packaging materials. Such laminates can be manufactured from substantially completely bio-based materials, preferably cellulose-based materials, thereby facilitating the repulping and recycling of packaging materials including used laminates, and enabling, for example, an aluminum foil-free laminate structure for aseptic packaging. However, such laminates are further provided with an outermost polymer layer on one or both sides. The outermost polymer layer preferably provides liquid barrier properties and mechanical protection against the laminate surface. Preferably, the outermost polymer layer is also heat sealable. The outermost polymer layer is also used for decorative purposes such as printing and protection of printing.

[0005] To provide an MFC film on a paper substrate or a cardboard substrate, a self-standing MFC film can be manufactured from an MFC suspension and then laminated with the paper substrate or the cardboard substrate.

[0006] One approach for manufacturing a self-standing MFC film from an MFC suspension is to use the film casting method, i.e., casting the MFC suspension on a non-porous support such as a plastic or metal support to form a film, and then dehydrating and / or drying the film. It has been demonstrated that the casting method can produce MFC films with a very smooth surface having excellent barrier properties such as oxygen barrier properties and / or water vapor barrier properties.

[0007] Another approach to manufacturing self-standing MFC films is to use wet-laying techniques, i.e., applying a layer of MFC suspension to a dewatering wire or membrane and dewatering it on the wire or membrane by vacuum, gravity, capillary dewatering, press dewatering, or a combination thereof, followed by drying or liquid evaporation. However, one drawback of this approach is that film additives dissolved or emulsified in the aqueous phase of the MFC suspension are mostly removed from the MFC layer during dewatering. Therefore, a retention agent and / or a flocculant may be required to prevent the removal of film additives. However, retention agents and / or flocculants usually have an adverse effect on barrier properties and do not guarantee complete retention. Also, in this approach, there are limitations on the type of MFC used, and very fine MFCs cannot be used because they may pass through or penetrate the wire or clog the wire or membrane. Also, other very small dissolved or solid particles dispersed in the aqueous phase of the MFC suspension, such as mineral nanofillers, tend to penetrate through the wire or membrane during the dewatering step.

[0008] Generally, self-standing MFC films, such as those manufactured by casting or wet-laying methods, have low elasticity (i.e., high brittleness). This can lead to conversion difficulties, such as when such MFC films are unwound from a reel and transported to or during a lamination step for lamination with a paper or paperboard substrate, making web handling difficult in the lamination step. Therefore, when used for lamination, their brittleness can cause problems with runnability, resulting in web breakage or defects such as torn edges, cracks, and wrinkles in such MFC films.

[0009] One approach to reducing the brittleness problem of MFC films is to use a moisturizing agent in the MFC film. However, a moisturizing agent, especially a large amount of it, can change the relative moisture content of the MFC film. When laminating the MFC film between two polymer layers, for example, between a tie layer (used to laminate the MFC film to a paper or cardboard substrate) and a liquid barrier layer (i.e., the outermost polymer layer), further problems may occur. Trapped moisture and potential VOCs (volatile organic compounds) can cause peeling problems and swelling. The greater the amount of trapped moisture, the higher, of course, the risk of back layer peeling. Therefore, using a high concentration of moisturizing agent increases this risk. Also, elevated temperatures during post-treatment such as printing and processing of the laminate, forming and sealing of the final product (such as a packaging product) including the laminate, or filling and storage of the product in the final product can increase the risk of back layer peeling.

[0010] Therefore, there is still room for improvement in the method for manufacturing a laminate including a paper or cardboard substrate and a barrier film (where the barrier film is an MFC film).

Summary of the Invention

[0011] The object of the present invention is an improved method for manufacturing a laminate including a paper or cardboard substrate and a barrier film, where the barrier film is an MFC film, and this method reduces the difficulty of the brittleness of the MFC film in the handling of the web related to the lamination to the paper or cardboard substrate, and eliminates or reduces at least some of the drawbacks of the prior art methods. The object is to provide such a method.

[0012] The above object, as well as other objects realized by those skilled in the art in view of the present disclosure, are achieved by various aspects of the present disclosure.

Mode for Carrying Out the Invention

[0013] The present invention is defined by the appended independent claims. Embodiments are described in the appended dependent claims and the following description.

[0014] According to a first aspect described herein, a method of manufacturing a laminate comprising a base material of paper or paperboard and a microfibrillated cellulose (MFC) film, comprising: - providing a first web comprising a base material of paper or paperboard; - providing a second web of MFC film, the MFC film having a) an MFC content between 50% and 100% by weight based on the total dry weight, b) a moisture content of 5 to 20% by weight, preferably 5 to 15% by weight, c) a ratio of the machine direction tensile index to the cross direction tensile index of 0.8 to 1.4, preferably 0.8 to 1.2, most preferably 0.9 to 1.1; - further drying the MFC film of the second web to a moisture content of less than 4% by weight, preferably less than 2% by weight, most preferably less than 1.5% by weight; - joining the first web and the second web using at least one adhesive layer provided between the first web and the second web to form the laminate. The method includes the step of joining, which is performed after the step of further drying the MFC film of the second web, and the MFC film of the second web has a moisture content of less than 4% by weight, preferably less than 2% by weight, most preferably less than 1.5% by weight at the time of joining. A method is provided.

[0015] Thus, the method of the first aspect provides a laminate comprising a base material of paper or paperboard and an MFC film as a barrier film. Thus, the laminate is a barrier laminate.

[0016] Generally, self-supporting MFC films, such as those made by casting or wet lamination methods, have low elasticity (i.e., high brittleness). This can lead to conversion problems such as difficulties in handling the web in the lamination process. For example, difficulties in handling the web can include difficulties that occur when such an MFC film is transported to a substrate, such as a paper or cardboard substrate (e.g., after being unwound from a reel), and / or during the lamination process for laminating with the substrate. Therefore, when used for lamination, its brittleness can cause problems with runnability, such as the web breaking or defects such as torn edges and cracks in such MFC films.

[0017] A common problem regarding the brittleness of self-supporting MFC films in the handling of webs related to lamination is, at least in part, due to the fact that self-supporting MFC films are manufactured to have a low moisture content, i.e., dried to a low moisture content of usually less than 5 wt%, for example, 1.5 - 4.5 wt%. In fact, it is desirable to produce self-supporting MFC films with a low moisture content. This is because it is desirable that the moisture content of the MFC film in the laminate is low, for example, to avoid problems such as peeling due to moisture escaping or evaporating from the MFC film during a conversion process step at high temperature. Further, when forming a package using the laminate at a later stage and sealing the seams of the package, moisture may evaporate from the wet MFC film, potentially causing delamination. Additionally, the barrier properties such as oxygen barrier and water vapor barrier of the MFC film may decrease if the moisture content in the film is high, so a low moisture content is desirable for the barrier properties. Also, the MFC film is manufactured with a low moisture content to ensure sufficient film formation and cross-linking during the manufacture of the MFC film. Further, the MFC film is manufactured with a low moisture content to promote the dimensional stability of the manufactured MFC film. However, as described above, when using a low moisture content MFC film in a lamination process, its brittleness can cause problems with runnability and web breakage or defects. Also, the disadvantages of a low moisture content MFC film are low strain at break and higher strain rate sensitivity.

[0018] According to the method according to the first aspect, in the handling step of the web of the MFC film, such as unwinding and conveying from a reel for the lamination process, particularly for lamination onto a paper or cardboard substrate, the problems due to the brittleness of the self-supporting MFC film can be essentially reduced or alleviated. At the same time, the dimensional stability of the MFC film is promoted, and a low moisture content in the MFC film of the formed laminate is brought about. Also, according to the method according to the first aspect, the problems related to the brittleness of the self-supporting MFC film in the lamination process can be essentially reduced or alleviated without using a humectant or at least without using a large amount of humectant. More specifically, by using a specific MFC film for lamination having an MFC content between 50% and 100% by weight, a moisture content of 5 - 20% by weight, and a ratio of the machine direction tensile index to the cross direction tensile index of 0.8 - 1.4, based on the total dry weight, and by including an additional drying step of drying the MFC film to a moisture content of less than 4% by weight, for example, immediately before joining the MFC film to the paper or cardboard substrate using at least one adhesive layer, the problems due to the brittleness of the MFC film during web handling in the lamination process are essentially reduced or alleviated. At the same time, the dimensional stability of the MFC film is promoted, and a low moisture content is brought about in the MFC film of the formed laminate. Also, the adjustment to a very low level of moisture content immediately before the lamination process means that the surface is more reactive and less hydrated.

[0019] By using a specific MFC film having a moisture content of 5 to 20% by weight and including an additional drying step of the MFC film before bonding, it becomes possible to reduce the brittleness problem during handling of the web of the MFC film in the lamination process, i.e., before bonding the MFC film to a paper or paperboard substrate. This is because the MFC film has a moisture content that can reduce the brittleness problem up to a further drying step before bonding, and at the same time, a lower moisture content of the MFC film is provided during bonding to form a laminate. Also, with an MFC film having a ratio of longitudinal tensile index to transverse tensile index of 0.8 to 1.4, the dimensional stability of the MFC film is promoted even when the moisture content is 5 to 20% by weight during web handling of the MFC film before bonding.

[0020] Paper generally refers to a thin sheet made from wood pulp or other fibrous substances containing cellulose fibers, and is used for writing, drawing, or printing on packaging materials, or as a packaging material. Paper can be either bleached or unbleached, coated or uncoated, depending on the requirements of the end use, and can be manufactured in various thicknesses. Paper can be a single-layer material or a multi-layer material composed of two or more layers.

[0021] Paperboard generally refers to a strong, thick paper or cardboard containing cellulose fibers used for boxes and other types of packaging materials. Paperboard can be either bleached or unbleached, coated or uncoated, depending on the requirements of the end use, and can be manufactured in various thicknesses. Paperboard can be a single-layer material or a multi-layer material composed of two or more layers. A common type of multi-layer paperboard is composed of a lower-density intermediate layer (sometimes called the "bulk layer") sandwiched between two higher-density outer layers. The lower-density intermediate layer typically has a density of less than 750 kg / m 3 3, less preferably less than 700, less than 650, less than 600, less than 550, less than 500, less than 450, less than 400, or less than 350 kg / m 3can have a density lower than. The outer layer with a higher density is typically at least 100 kg / m less than the intermediate layer 3 higher, preferably at least 200 kg / m less than the intermediate layer 3 and has a high density.

[0022] The paper or paperboard used as a substrate according to the present disclosure can be made from pulp from virgin fibers, such as mechanical pulp, semi-chemical pulp, chemical pulp, and / or thermomechanical pulp. It can also be made from waste paper, recycled paper, or paperboard. The paper or paperboard used as a substrate according to the present disclosure is manufactured using methods known in the art.

[0023] In some embodiments, the paper or paperboard substrate contains at least 10% recycled material, such as at least 20%, at least 40%, at least 50%, at least 60%, or at least 70% recycled material, which can be either pre-consumer grade or post-consumer grade.

[0024] The paper substrate used in the method of the first aspect preferably has a basis weight in the range of 10 - 200 g / m 2 and more preferably in the range of 20 - 100 g / m 2 . Unless otherwise specified, the basis weight is determined in accordance with standard ISO 536.

[0025] The paperboard substrate used in the method of the first aspect preferably has a basis weight in the range of 120 - 600 g / m 2 or 120 - 450 g / m 2 and more preferably in the range of 200 - 500 g / m 2 or 180 - 380 g / m 2 . Unless otherwise specified, the basis weight is determined in accordance with standard ISO 536.

[0026] The base material of paper or cardboard may be single-layer paper or cardboard, or multi-layer paper or cardboard. In some embodiments, the cardboard base material is multi-layer cardboard. In some embodiments, the cardboard base material is multi-layer cardboard composed of two or more layers. In some embodiments, the cardboard base material is multi-layer cardboard composed of three or more layers. In some embodiments, the cardboard base material is multi-layer cardboard composed of a lower-density intermediate layer sandwiched between two higher-density outer layers.

[0027] In some embodiments, the cardboard base material is foamed cardboard. In some embodiments where the cardboard base material is multi-layer cardboard, at least one layer, preferably the intermediate layer, is a foam. In some embodiments where the cardboard base material is multi-layer cardboard, at least one of the layers, preferably the intermediate layer, is a bulging layer.

[0028] The base material of paper or cardboard can be optionally coated, such as with a mineral coating, to improve smoothness and printability. Such a mineral coating can be provided on one or both sides of the base material and is part of the base material in the context of the present disclosure. The paper or cardboard base material can be subjected to surface sizing or surface treatment on at least one side of the base material. Such surface sizing or surface treatment is part of the paper or cardboard base material in the context of the present disclosure. Preferably, the surface sizing composition used for surface sizing contains starch or a starch derivative.

[0029] As used herein, the term "film" generally refers to a thin continuous sheet-forming material, such as a thin base material having good barrier properties against gases, aromas, greases or oils, for example, oxygen barrier properties and / or water vapor barrier properties. Depending on the composition of the MFC suspension from which it is formed, the MFC film can also be considered as thin paper (such as nanopaper or micropaper) or a membrane.

[0030] In the context of a patent application, microfibrillated cellulose (MFC) shall mean cellulose particles, fibers or fibrils having a width or diameter of 20 nm to 1000 nm.

[0031] To produce MFC, there are various methods, such as purification by single or multiple passes, purification after pre-hydrolysis, or high-shear decomposition or fibrillation liberation. To realize MFC production from both the perspectives of energy efficiency and sustainability, usually one or more pretreatment procedures are required. Therefore, the cellulose fibers of the pulp used for MFC production can be natural or, for example, pretreated enzymatically or chemically to reduce the amount of hemicellulose or lignin. The cellulose fibers can be chemically modified before fibrillation, in which case the cellulose molecules contain functional groups other than (or in addition to) those found in the original cellulose. Such groups include, inter alia, carboxymethyl (CM), aldehyde and / or carboxyl groups (cellulose obtained by oxidation, such as 2,2’,6,6’-tetramethylpiperidine-N-oxyl (TEMPO)-mediated oxidation), or quaternary ammonium (cationic cellulose). After modification or oxidation by any of the above methods, the fibers are ready to be broken down into MFC.

[0032] MFC can be produced from hardwood and / or softwood wood cellulose fibers. It can also be made from microbial sources, agricultural fibers such as wheat straw pulp, bamboo, bagasse, or other non-wood fiber sources. For example, it can be produced from pulp containing virgin fibers such as mechanical pulp, chemical pulp, and / or thermomechanical pulp. It can also be made from waste paper or recycled paper.

[0033] As described above, the MFC film of the second web contains 50 wt% to 100 wt% of MFC based on the dry weight. In some embodiments, the MFC film contains 60 wt% to 100 wt%, preferably 70 wt% to 100 wt%, more preferably 80 wt% to 100 wt% of MFC based on the total dry weight, which is related to the amount of MFC in the film itself.

[0034] In some embodiments, the basis weight of the MFC film provided on the second web (i.e., the provided MFC film with a moisture content of 5 to 20 wt%) is 4 to 80 g / m 2 , preferably 10 to 60 g / m 2 or 15 to 50 g / m 2 or 18 to 45 g / m 2 or 20 to 40 g / m 2 . The specific basis weight of the provided MFC film is 4 to 10 g / m 2 , 10 to 20 g / m 2 , 20 to 30 g / m 2 , 30 to 40 g / m 2 , 40 to 50 g / m 2 , 50 to 60 g / m 2 , 60 to 70 g / m 2 , or 70 to 80 g / m 2 .

[0035] In some embodiments, the density of the MFC film provided on the second web is 700 to 1400 kg / m 3 , for example 800 to 1300 kg / m 3 or 850 to 1200 kg / m 3 .

[0036] In some embodiments, the average film thickness of the provided MFC film of the second web is 5 to 60 μm, preferably 10 to 50 μm, 15 to 45 μm, or 20 to 40 μm. The specific average film thickness may be 5 to 10 μm, 10 to 15 μm, 15 to 20 μm, 20 to 25 μm, 25 to 30 μm, 30 to 35 μm, 35 to 40 μm, 40 to 45 μm, 45 to 50 μm, 50 to 55 μm, or 55 to 60 μm. The average film thickness can be defined as the average thickness across the entire width of the film. The thickness of the MFC film can be measured, as non-limiting examples, by white light interferometry, laser profilometry, or optically, by cutting the sample with a line in the machine transverse direction (whether cast in resin or not) and taking a microscopic image in the thickness direction of the cut cross-section (e.g., scanning electron microscopy or other applicable methods).

[0037] In some embodiments, the width of the provided MFC film of the second web is 0.3 to 4 m, preferably 0.5 to 4 m, 1 to 4 m, or 2 to 4 m.

[0038] In some embodiments, the provided MFC film of the second web has an oxygen transmission rate (OTR) measured in accordance with standard ASTM F1927-20 at 50% relative humidity and 23 °C of less than 50 cc / m 2 / 24 h, preferably less than 20 cc / m 2 / 24 h, most preferably less than 10 cc / m 2 / 24 h.

[0039] In some embodiments, the provided MFC film of the second web has a water vapor transmission rate (WVTR) measured in accordance with standard ASTM F1249-20 at 50% relative humidity and 23 °C of less than 100 g / m 2 / 24 h, preferably less than 50 g / m 2 / 24 h, more preferably less than 20 g / m 2 / 24 h.

[0040] In some embodiments, the provided MFC film of the second web has at least 10, preferably 12 KIT values when measured in accordance with standard ISO 16532-2.

[0041] In some embodiments, the provided MFC film of the second web has less than 10 pinholes per m 2 and preferably less than 6 pinholes per m. 2

[0042] The MFC of the MFC film may be composed of one or more fractions of MFC. In some embodiments, the MFC of the MFC film comprises one fraction of fine-grade MFC. In some embodiments, the MFC of the MFC film comprises two or more fractions of MFC of different fine grades. In some embodiments, the MFC of the MFC film comprises one fraction of a fine grade and one fraction of a coarse grade, and the coarse grade may be, for example, an additive. The Shopper-Reigl value of the coarse MFC in this case is usually 80-100 SR°, for example, 80-99 SR°, 90-99 SR°, or 95-99 SR°, but the fine MFC fibrillates to a Shopper-Reigl value exceeding the measurement range (theoretical value is about 100 SR° or more) determined by standard ISO 5267-1. In some embodiments, the fine-grade MFC is chemically derivatized such as carboxymethylated MFC.

[0043] ​In addition to MFC, the MFC film may contain a film-forming agent, a dispersant, a filler, a pigment, a wet strength improver, a cross-linking agent, a plasticizer, a softening agent, a humectant, an adhesion primer, a wetting agent, a biocide, a colorant, an antifoaming agent, a hydrophobizing agent such as alkyl ketene dimer (AKD), alkenyl succinic anhydride (ASA), wax, rosin resin, mineral additives (fillers) such as bentonite, kaolin, talc, mica, montmorillonite, organic clay, graphene and graphene oxide, and conventional papermaking additives or chemicals such as stearate, starch, silica, precipitated calcium carbonate, cationic polysaccharides, and rheology modifiers. Therefore, these additives or chemical substances may be process chemicals or film performance chemicals added to impart specific properties to the final product film and / or to facilitate the production of the film. In some embodiments, the MFC film contains at least one additional polymer capable of forming the film and / or improving the bonding between cellulose fibers. Typical examples of such polymers are natural gums or polysaccharides or their derivatives such as carboxymethylated cellulose (CMC), hemicellulose, starch, polyvinyl alcohol (PVOH), or analogs thereof. In some embodiments, the MFC film contains at least one additive selected from the following group: PVOH and its derivatives or analogs, polysaccharides such as starch and CMC, sorbitol, and polyethylene glycol.

[0044] PVOH may be a single type of PVOH or a mixture of two or more types of PVOH with different degrees of hydrolysis or viscosities. PVOH may have a degree of hydrolysis in the range of, for example, 80 to 99 mol%, preferably 88 to 99 mol%.

[0045] In some embodiments, the MFC film comprises additives that are 50 wt% or less, such as 35 wt% or less, 30 wt% or less, 25 wt% or less, or 20 wt% or less, based on the total dry weight of the MFC film. For example, the MFC film can comprise 1-50 wt%, or 1-35 wt%, or 1-30 wt%, or 1-25 wt%, or 1-20 wt% of additives based on the total dry weight of the MFC film.

[0046] In some embodiments, the MFC film comprises one or more humectants and / or plasticizers, such as sugar alcohols (e.g., sorbitol), glycols, or other polyols, that are 0-30 wt%, or 0.5-20 wt%, or 3-15 wt% based on the total dry weight.

[0047] In some embodiments, the MFC film comprises up to 20 wt% of a mineral filler (conventional filler or nanofiller), such as bentonite, kaolin, talc, mica, montmorillonite, organoclay, graphene, graphene oxide, or combinations thereof.

[0048] In some embodiments, the MFC film comprises up to 30 wt% of nanocrystals and / or cellulose derivatives based on the total dry weight.

[0049] The MFC film can be a single-layer or multi-layer film, or a single-layer or multi-layer ply. Thus, in some embodiments, the MFC film is composed of a single film layer, or two or more film layers stacked on top of each other.

[0050] In some embodiments, in addition to MFC, the MFC film comprises one or more additional cellulose pulp fractions, such as a cellulose pulp fraction having a Schopper - Riegler value of ≦70 SR°, such as 15-70 SR° or 25-60 SR° as determined by standard ISO 5267-1, and / or additional fractions of conventional cellulose fibers and / or lignocellulose fibers.

[0051] The MFC film is preferably formed from an MFC suspension, preferably an aqueous MFC suspension (i.e., containing water as the suspension medium), and contains MFC and optional additives and / or chemicals and / or further cellulose pulp fractions as defined above. The MFC suspension is preferably cast onto a non-porous support, such as a metal belt, particularly a steel belt, a polymer belt, or a polymer-coated belt, using known casting techniques to form a wet MFC film. The non-porous support is typically an endless belt. Preferably, the wet MFC film is dehydrated and / or dried on the non-porous support using methods known in the art to obtain an MFC film having a moisture content of 5 to 20% by weight. After peeling the MFC film from the non-porous support, a web of MFC film having a moisture content of 5 to 20% by weight is obtained.

[0052] The term "casting", when used in film formation, refers to a known term for depositing a suspension onto a support (usually an endless belt) by contact or non-contact deposition and flattening methods to form a wet web. Examples of such deposition and flattening methods include curtain coating / applying, slot die casting, or administering the MFC suspension using a spray or similar device and flattening using a doctor blade or rod.

[0053] As described above, the MFC film used in the method of the first aspect, i.e., the MFC film of the second web provided to the lamination process, has a moisture content of 5 to 20% by weight, preferably 5 to 15% by weight, or 6 to 15% by weight, or 6 to 14% by weight, or 7 to 13% by weight. The moisture content of the MFC film provided to the lamination process can be determined, for example, in accordance with the standard ISO 638 by determining the dry content, by calculating the moisture content, or by spectroscopy. Alternatively, the moisture content can also be determined using the apparatus or equipment used to determine the dry moisture content. The moisture content can be measured under ambient conditions. The specific moisture content of the MFC film is suitable for handling the web by unwinding the second web of the MFC film during conveyance before the MFC film is joined to the first web to form a laminate, i.e., until joining with the first web, and thus, problems related to the brittleness of the MFC film are reduced.

[0054] The ductility of the MFC film can be explained by the tensile strength and the strain at break of the MFC film. In some embodiments, the MFC film has a tensile index in the machine direction of at least 20 Nm / g, preferably at least 30 Nm / g or at least 40 Nm / g. In some embodiments, the MFC film has a strain at break in the machine direction of at least 1.5%, for example 2 to 20% or 3 to 15%.

[0055] Also, as described above, the MFC film used in the method of the first aspect has a ratio of the machine direction (MD) tensile index to the cross direction (CD) tensile index of 0.8 to 1.4, preferably 0.8 to 1.2, and most preferably 0.9 to 1.1. This means that the microfibrils have no or essentially no orientation, thereby contributing to the high dimensional stability (low moisture absorption expansion) of the MFC film. The specified MD / CD ratio of the tensile index can be obtained during the production of the MFC film, for example, by manufacturing the MFC film using a casting technique on a non-porous casting support and ensuring that there is no velocity difference between the MFC suspension flowing out of the casting unit and the casting support on which the MFC is cast to form the wet MFC film.

[0056] The tensile index in the machine direction, the strain at break, and the MD / CD ratio of the tensile index are measured using a vertical testing machine such as a Zwick vertical tensile testing machine in accordance with standard ISO 1924-3, with the following minor modifications: Test span (distance between clamps): 20 mm (ISO 1924-3 100 mm); constant elongation rate: 2 mm / min (ISO 1924-3 100 mm / min); sample width 15 mm (in accordance with ISO 1924-3); sample length: 55 mm (ISO 1924-3 defines that it must be a length that can be clamped); load cell: 0.5 kN.

[0057] The dimensional stability of the MFC film used in the first aspect of the method can be further promoted by using suppressed dehydration and / or drying, that is, by manufacturing the MFC film using a casting technique on a non-porous casting support and maintaining the manufactured MFC film in contact with the non-porous casting support until the moisture content reaches 5 to 20 wt% (i.e., maintaining the manufactured MFC film in contact with the non-porous casting support during dehydration and / or drying until the moisture content reaches 5 to 20 wt%).

[0058] In some embodiments, the MFC film comprises at least one crosslinking chemical substance and / or at least one other chemical substance that occupies free hydroxyl groups that bind to water. These chemical substances contribute to reducing the moisture swelling rate of the MFC film. Examples of such chemical substances include citric acid, glyoxal, ammonium zirconium carbonate, urea formaldehyde, melamine formaldehyde resin, metal salts, zirconium chelates, reactive starches such as dialdehyde starch, amino resins, and the like.

[0059] As described above, the MFC film of the provided second web having a moisture content of 5 to 20% by weight is further dried until it has a moisture content of less than 4% by weight or less than 3% by weight, preferably less than 2% by weight, most preferably less than 1.5% by weight or less than 1% by weight. Further drying the MFC film of the second web to a moisture content of less than 4% by weight can be selected from the group consisting of contact drying, infrared (IR) drying, near-infrared (NIR) drying, microwave (MW) drying, ultraviolet (UV) drying, electron beam (EB) drying, hot gas impingement drying such as thermal gas impingement drying, other types of radiation drying, and combinations thereof.

[0060] In some embodiments, further drying the MFC film is radiation drying selected from the following group: IR drying, NIR drying, MW drying, UV drying, EB drying, and combinations thereof.

[0061] In some embodiments, further drying the MFC film is selected from the following group: IR drying, UV drying, EB drying, and combinations thereof.

[0062] By using radiation drying, particularly IR drying, UV drying and / or EB drying, a sterilizing effect, i.e., sterilization and / or inactivation of potential microorganisms and / or enzymes, can be achieved, and / or a crosslinking effect can be achieved in addition to the drying effect. Also, particularly when EB drying is utilized, further drying may mean that the viscosity of the adhesive layer changes due to depolymerization.

[0063] For example, the moisture content of the MFC film can be measured, for example, online, by spectroscopic methods such as infrared (IR) spectroscopy, near-infrared (NIR) spectroscopy, or Raman spectroscopy. For example, an infrared moisture sensor based on a common single-sided infrared gauge mounted in a single head package with a halogen light source focused on the sheet can be used. Part of the beam is absorbed, part is reflected (scattered) and collected, and detected. The moisture content can be determined under ambient conditions. Alternatively, the dry content of the MFC film can be measured and the moisture content can be determined using the dry content. Alternatively, the dry content can be measured to determine the moisture content. Therefore, the moisture content of the MFC film can be measured using ISO 638 offline, the dry content can be determined, and the moisture content can be calculated from the measured value of the dry content. The moisture content can be measured under ambient conditions.

[0064] As described above, the first web containing a paper or paperboard substrate and the second web of the MFC film are joined using at least one adhesive layer (i.e., tie layer) provided between the first web and the second web to form a laminate. The joining is carried out after further drying the MFC film of the second web, and the moisture content of the MFC film of the second web is less than 4 wt% or less than 3 wt%, preferably less than 2 wt%, most preferably less than 1.5 wt% or less than 1 wt% at the time of said joining (i.e., at the first contact point of the first web and the second web (via at least one adhesive layer)) when the first web and the second web are brought together. For example, the moisture content of the paper or paperboard substrate may be 2 to 9 wt%, preferably 3 to 8 wt%, more preferably 3 to 7 wt% or 3 to 6 wt% at the time of joining. The moisture content of the paper or paperboard substrate can be determined by determining the dry content in accordance with ISO 638 and calculating the moisture content, or by using a spectroscopic method.

[0065] Preferably, the joining of the first web and the second web is performed immediately after further drying. In some embodiments, the joining of the first web and the second web is performed at 20 to 1200 milliseconds, preferably 40 to 600 milliseconds, after further drying (i.e., after the completion of further drying by the drying device used for further drying). Thus, in these embodiments, the time frame between the completion of further drying by the drying device used for further drying and the joining, i.e., the time between the point of the completed / last impact of the drying device used for further drying on the MFC film and the point of the first contact (via at least one adhesive layer) between the first web and the second web, is 20 to 1200 milliseconds, preferably 40 to 600 milliseconds. The point of the final / last impact of the drying device used for further drying on the MFC film can be defined as the last point in time when the MFC film receives heat or radiation (energy) from the drying device used for further drying. In some embodiments, the joining of the first web and the second web is performed at 0.01 to 20 meters, preferably 0.03 to 10 meters, after further drying (i.e., after the completion of further drying by the drying device used for further drying). Thus, in these embodiments, the distance between the completion of further drying by the drying device used for further drying and the joining, i.e., the position of the completed / last impact of the drying device used for further drying on the MFC film and the position of the first contact (via at least one adhesive layer) between the first web and the second web in the laminating unit, such as the web path length of the production line (i.e., the path length of the MFC film), is 0.01 to 20 meters, preferably 0.03 to 10 meters. The position of the final / last impact of the drying device used for further drying on the MFC film can be defined as the most downstream position when the MFC film receives heat or radiation (energy) from the drying device used for further drying.By drying the MFC film immediately before bonding, a low water content is maintained in the bonding process, ensuring that the MFC film provides a low water content to the laminate. Furthermore, the risk of operating failures associated with the brittle film is minimized. Films with low water content also mean high reactivity and a small amount of the required adhesive. Also, heating the MFC film during further drying may improve its adhesion to the applied adhesive polymer.

[0066] Bonding can be carried out at a lamination station including one or more lamination nips such as a pressure roller nip. Thus, the first web and the second web are joined and laminated at a lamination station including one or more lamination nips, and the first web and the second web are pressed together at one or more lamination nips with at least one adhesive layer disposed between the first web and the second web. In some embodiments, the lamination nip is formed between two rolls at least one of which is coolable. In some embodiments, the lamination nip is formed between a cooling roll and an un-temperature-controlled nip roll or pressure roll. In some embodiments, the nip roll or pressure roll may be a heating roll.

[0067] The adhesive layer can generally include any suitable adhesive commonly used in paper or paperboard-based packaging laminates, or adhesives used particularly in liquid or food packaging laminates. In the present invention, various types of adhesives and adhesive coating methods can be used. Typically, the adhesive layer is composed of one or more adhesive polymers. The adhesive layer may be composed of only one or more adhesive polymers, or may further include other additives for improving the properties of the adhesive layer.

[0068] In some embodiments, the adhesive layer includes at least 50 wt% of an adhesive polymer or a mixture of adhesive polymers based on the dry weight.

[0069] In some embodiments, the adhesive layer comprises or consists of one or more adhesive polymers selected from the group consisting of polyolefins, polyesters, polyurethanes, and acrylic copolymers. In some embodiments, the adhesive layer comprises or consists of one or more adhesive polymers selected from the group consisting of polyolefins and polyesters. In some embodiments, the adhesive layer comprises or consists of one or more of polypropylene and polyethylene, such as low density polyethylene (LDPE or LLDPE), medium density polyethylene (MDPE), or high density polyethylene (HDPE). In some embodiments, the adhesive layer comprises or consists of components selected from adhesive thermoplastic polymers such as modified polyolefins based primarily on LDPE or LLDPE copolymers, or graft copolymers having functional group-containing monomer units such as carboxyl groups or glycidyl functional groups, for example (meth)acrylic acid monomers or maleic anhydride (MAH) monomers, (i.e., ethylene acrylic acid copolymer (EAA) or ethylene methacrylic acid copolymer (EMAA)), ethylene glycidyl (meth)acrylate copolymer (EG(M)A), or MAH-grafted polyethylene (MAHg-PE). Another example of such modified polymers or adhesive polymers is so-called ionomers or ionomer polymers. Preferably, the modified polyolefin is ethylene acrylic acid copolymer (EAA) or ethylene methacrylic acid copolymer (EMAA).

[0070] In some embodiments, the adhesive layer comprises at least 50 wt% of a water-soluble polymer or a mixture of water-soluble polymers based on dry weight. The water-soluble polymer of the adhesive layer is soluble in cold water for a certain period of time, or is soluble in warm water at a temperature, for example, below 100 °C or above 100 °C. In some embodiments, the water-soluble polymer is selected from the group consisting of polyvinyl alcohol (PVOH) or its derivatives or analogs, carboxymethyl cellulose (CMC), starch, alginates, and hemicelluloses, preferably PVOH.

[0071] The adhesive layer can be applied by any suitable method known in the art. The adhesive layer can be applied, for example, as a solution or dispersion in an aqueous or organic solvent carrier using a liquid coating method known in the art, or in a molten form using an extrusion coating. Extrusion coating is a process of applying a molten plastic material to a substrate to form a very thin, smooth, and uniform layer. In embodiments where the adhesive layer includes one or more adhesive polymers selected from the group consisting of polyolefins, polyesters, polyurethanes, and acrylic copolymers, extrusion coating is preferably utilized for the application of the adhesive layer.

[0072] In embodiments where the adhesive layer includes a water-soluble polymer, the adhesive layer may be formed in the form of a solution or dispersion that is spread as a thin, uniform layer on the substrate during application and then dried by a liquid film coating process. The adhesive layer can be applied by a contact or non-contact coating method.

[0073] In some embodiments, at least one adhesive layer is applied in the form of a foam. Foam coating is advantageous because it can form a film with a higher solids content and a lower moisture content compared to non-foam coatings. Since the moisture content of the foam coating is lower, the problem of rewetting of the barrier substrate is also reduced. The foam can be formed using a polymeric or non-polymeric blowing agent. Examples of polymeric blowing agents include PVOH, hydrophobically modified starch, hydrophobically modified ethyl hydroxyethyl cellulose, and the like.

[0074] In some embodiments, the adhesive layer further includes a crosslinking agent capable of crosslinking the water-soluble polymer. Crosslinking improves the water vapor barrier properties of the adhesive layer. Suitable crosslinking agents include, but are not limited to, polyfunctional organic acids or aldehydes such as citric acid, glyoxal, glutaraldehyde, etc. In some embodiments, the crosslinking agent is an organic acid, more preferably citric acid. The concentration of the crosslinking agent can be, for example, 1 to 20 wt%, preferably 1 to 15 wt% based on the dry weight of the adhesive layer.

[0075] In some embodiments, the adhesive layer comprises PVOH and citric acid. By crosslinking PVOH with citric acid, the water vapor barrier properties of the adhesive layer are improved.

[0076] In some embodiments, the adhesive layer comprises one or more additional polymers in a total amount of 0 to 50 wt% based on the dry weight.

[0077] In some embodiments, the adhesive layer further comprises, based on the dry weight, up to 50 wt% of microfibrillated cellulose (MFC), nanocrystalline cellulose, sodium carboxymethyl cellulose, hydroxypropyl cellulose, ethyl hydroxyethyl cellulose, cellulose acetate, hydroxyethyl cellulose, hemicellulose, or other chemically modified cellulose derivatives, or combinations thereof.

[0078] In some embodiments, one adhesive layer is provided between the first web and the second web to form a laminate. In some embodiments, two or more adhesive layers are provided between the first web and the second web to form a laminate. The total coat weight of the one or more adhesive layers is typically in the range of 1 to 20 g / m 2 . In some embodiments, the total coat weight of the one or more adhesive layers is in the range of 2 to 15 g / m 2 and more preferably in the range of 3 to 12 g / m 2 .

[0079] In some embodiments, at least one adhesive layer is provided on the surface of the first web before joining the first web to the second web of the MFC film. Thus, in these embodiments, at least one adhesive layer is provided on the surface of the first web, and in the joining step, the first web is joined to the second web of the MFC film by the adhesive layer provided between the first web and the second web after joining. The adhesive layer may be provided on the surface of the first web by extrusion coating. In these embodiments, the joining may include joining the first web to the second web using the adhesive layer provided between the first web and the second web at a lamination station including at least one lamination nip.

[0080] In some embodiments, at least one adhesive layer is provided on the surface of the MFC film of the second web before joining to the first web. Thus, in these embodiments, at least one adhesive layer is provided on the surface of the MCF film, and in the joining step, the first web is joined to the MFC film by the adhesive layer provided between the first web and the MCF film after joining. The adhesive layer may be provided on the surface of the MCF film by extrusion coating. In these embodiments, the joining may include joining the first web to the second web using the adhesive layer provided between the first web and the second web at a lamination station including at least one lamination nip. In these embodiments, it is particularly advantageous to use a moistureless adhesive such as a moistureless adhesive or a foaming adhesive.

[0081] In some embodiments, joining comprises joining a first web and a second web at a lamination station that includes a lamination nip, for example, by supplying or injecting a composition or component used to form an adhesive layer into the lamination nip, at least one adhesive layer is provided between the first web and the second web at the lamination nip by forming an adhesive layer between the first web and the second web at the lamination nip. In these embodiments, the adhesive may be extruded into the lamination nip.

[0082] In embodiments where multiple adhesive layers are used to join the first web and the second web, all of the adhesive layers can be provided on the first web, provided on the second web, or formed and provided within the lamination nip between the first web and the second web by injection. Alternatively, in embodiments where multiple adhesive layers are used to join the first web and the second web, one or more adhesive layers may be provided on the first web, and / or one or more adhesive layers may be provided on the second web, and / or one or more adhesive layers may be formed and provided within the lamination nip between the first web and the second web.

[0083] In some embodiments, the second web is guided through at least one spreading roll (also called a spreader roll), preferably through at least one spreading roll, and then through a configuration including a web stabilization unit on the side opposite the support member (i.e., the second web is guided between the web stabilization unit on the side opposite the support member), after the MFC film is further dried to a moisture content of less than 4% by weight, and before joining according to the method of the first aspect. In these embodiments, wrinkles, curls, and / or air intrusion at the joint can be prevented or substantially reduced. The support member and the web stabilization unit on the opposite side may be a mechanical contact device (flat / cylindrical) or a non-contact device (air levitation). Suitable known spreading rolls that provide a spreading action for the second web can be used.

[0084] In some embodiments, the second web is supported by one or more rolls, whereby the second web of the MFC film has no open draw between further drying and bonding.

[0085] In some embodiments, the step of providing the first web includes providing a first reel of the first web and unwinding the first web from the first reel. Thus, in these embodiments, the unwound first web is joined to the second web.

[0086] In some embodiments, the step of providing the second web includes providing a second reel of the second web of the MFC film and unwinding the second web from the second reel. In these embodiments, the MFC film of the unwound second web is further dried and joined to the first web.

[0087] In some embodiments, the method of the first aspect is - providing a first reel of a first web comprising a paper or paperboard substrate and unwinding the first web from the first reel; - providing a second reel of a second web of an MFC film, the MFC film having a) an MFC content of 50 to 100 wt% based on the total dry weight, b) a moisture content of 5 to 20 wt%, preferably 5 to 15 wt%, and c) a ratio of the machine direction tensile index to the cross direction tensile index of 0.8 to 1.4, preferably 0.8 to 1.2, most preferably 0.9 to 1.1, and unwinding the second web from the second reel; - further drying the MFC film of the unwound second web to a moisture content of less than 4 wt%, preferably less than 2 wt%, most preferably less than 1.5 wt%; - joining the unwound first web and the unwound second web using at least one adhesive layer provided between the first web and the second web to form a laminate It includes, and the joining is carried out after further drying the MFC film of the second web. At the time of joining, the MFC film of the second web has a moisture content of less than 4% by weight, preferably less than 2% by weight, and most preferably less than 1.5% by weight.

[0088] In some embodiments, the method is a manufacturing and in-line or continuous process of the MFC film. The step of providing the second web of the MFC film includes providing the second web of the MFC film directly from the manufacturing of the MFC film, that is, without winding the MFC film onto a reel. Therefore, in these embodiments, the step of providing the second web of the MFC film forming a wet MFC film of the MFC suspension by casting on a non-porous support, dehydrating and / or drying the wet MFC film on the non-porous support to provide an MFC film having a moisture content of 5-20% by weight, and peeling the MFC film from the non-porous support to provide a web of the MFC film (i.e., the second web) having a moisture content of 5-20% by weight may be included.

[0089] There is a need for an improved solution to replace barrier plastic layers such as aluminum foil and polyolefin films as the barrier layer and substrate of packaging materials with alternatives that facilitate the repulping and recycling of used packaging materials. The laminate according to the present disclosure can advantageously be manufactured from substantially completely bio-based materials, preferably cellulose-based materials, thereby facilitating the repulping and recycling of used packaging materials containing the laminate according to the present disclosure.

[0090] The laminate according to the present disclosure replaces conventional materials that use barrier plastic layers such as polyolefin films and / or aluminum foil layers, and can be more easily repulped and recycled. In some embodiments, the laminate has a defect rate compliant with PTS RH 021 / 97 of less than 30%, preferably less than 20%, more preferably less than 10%, and most preferably less than 5%. The laminate according to the present disclosure can at least reduce the use of barrier plastic layers and / or aluminum foil layers used in conventional materials.

[0091] However, the laminate of the present invention can further be provided with an outermost polymer layer on one or both sides. The outermost polymer layer preferably provides mechanical protection such as liquid barrier properties and print protection against the laminate surface. It is also preferred that the outermost polymer layer is heat sealable.

[0092] In some embodiments, the method of the first aspect further includes providing a laminate having a first polymer layer of the outermost layer on the MFC film. In some embodiments, the outermost first polymer layer includes a thermoplastic polymer. In some embodiments, the first polymer layer of the outermost layer includes a polymer selected from the group consisting of polyolefins and polyesters. In some embodiments, the first polymer layer of the outermost layer includes a polymer selected from the group consisting of thermoplastic polyolefins and thermoplastic polyesters. In some embodiments, the first polymer layer of the outermost layer includes polypropylene or polyethylene. In some embodiments, the first polymer layer of the outermost layer includes polyethylene, more preferably LDPE or HDPE.

[0093] In some embodiments, the method of the first aspect further includes providing a laminate having a second polymer layer as the outermost layer on a paper or cardboard substrate. In some embodiments, the outermost second polymer layer comprises a thermoplastic polymer. In some embodiments, the second polymer layer of the outermost layer comprises a polymer selected from the group consisting of polyolefins and polyesters. In some embodiments, the second polymer layer of the outermost layer comprises a polymer selected from the group consisting of thermoplastic polyolefins and thermoplastic polyesters. In some embodiments, the second polymer layer of the outermost layer comprises polypropylene or polyethylene. In some embodiments, the second polymer layer of the outermost layer comprises polyethylene, more preferably LDPE or HDPE.

[0094] The outermost polymer layer can typically include either a thermoplastic polymer commonly used for the protective layer and / or heat-sealing layer of paper or cardboard-based packaging laminates, or a polymer specifically used for liquid or food packaging boards. Examples include polyethylene (PE), polyethylene terephthalate (PET), polyethylene furanoate (PEF), polypropylene (PP), polyhydroxyalkanoate (PHA), polylactic acid (PLA), polyglycolic acid (PGA), starch, cellulose, and the like. Polyethylene, particularly low-density polyethylene (LDPE) and high-density polyethylene (HDPE), are the most common and widely used polymers for liquid and food packaging boards. The polymers used are preferably manufactured from renewable materials. The first polymer layer of the outermost layer and the second polymer layer of the outermost layer may comprise the same polymer or different polymers.

[0095] The outermost polymer layer, while potentially interfering with repulping, may still be necessary or desirable in some applications. Additional polymer layers can be applied, for example, by extrusion coating, film lamination, or dispersion coating after forming the laminate. Thermoplastic polymers are useful because they can be easily processed by extrusion coating techniques and can form very thin, homogeneous films with excellent liquid barrier properties.

[0096] In some embodiments, the outermost polymer layer is formed by extrusion coating a polymer onto the laminate. Extrusion coating is a process of applying a molten plastic material 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).

[0097] The basis weight of each of the outermost polymer layers is preferably less than 50 g / m 2 . To achieve a continuous and substantially defect-free film, when provided by extrusion coating, a basis weight of at least 6 g / m 2 , preferably at least 8 g / m 2 , or at least 12 g / m 2 of each of the outermost polymer layers is typically required. In some embodiments, the basis weight of each outermost polymer layer ranges from 6 to 50 g / m 2 , preferably from 8 to 50 g / m 2 or from 10 to 25 g / m 2 or from 10 to 20 g / m 2 and the outermost polymer layer is provided by extrusion coating. In some embodiments, the basis weight of the outermost polymer layer ranges from 2 to 10 g / m 2 and the outermost polymer layer is provided by a foamed film.

[0098] According to a second aspect of the present disclosure, there is provided a laminate comprising a paper or cardboard substrate and an MFC film joined by at least one adhesive layer provided between the paper or cardboard substrate and the MFC film, the laminate being obtained by the method of the first aspect.

[0099] The laminate obtained by the method of the first aspect can be used as it is. Alternatively, it can also be made into a laminate material in combination with one or more additional layers, for example, one or more additional paper or cardboard layers and / or other layers. When the laminate is combined with one or more additional layers, for example one or more paper or cardboard layers, to form a laminate material, an outermost polymer layer (corresponding to the above outermost polymer layer) can be provided on one or both sides as required. Other examples of additional layers that can be combined with the laminate obtained by the method of the first aspect include additional polymer layers such as multiple polymer layers of the same or different polymers on each side, a protective varnish layer, a decorative layer on top of the laminate, and a sealing layer that can be activated (melted) by heat.

[0100] For example, the laminate or laminate material can be used as a packaging material such as for food or liquid packaging materials, or in packaging materials. For example, the laminate or laminate material can be part of a flexible packaging material such as an opaque or translucent self-standing pouch or bag. Thus, the laminate or laminate material can be used as a bag material for a box when packaging dry foods such as cereal. Further, the laminate or laminate material can be used as a wrapping substrate such as a flow wrap material, as a laminate material of paper, paperboard, or plastic, and / or as a substrate for disposable electronic devices. The laminate or laminate material can also be included in, for example, closures, lids, or labels. The laminate or laminate material can be incorporated into any type of package such as boxes, bags, wraps, wrapping films, cups, containers, trays, bottles, etc. The present disclosure also relates to a packaging product comprising a laminate or laminate material obtained by the method of the first aspect.

[0101] The laminate produced by the method of the first aspect is a paper or paperboard-based laminate, i.e., a laminate mainly formed from paper or paperboard such as a paper or paperboard-based packaging laminate. The laminate typically has a first outermost surface intended to function as the outer or printed surface and a second outermost surface intended to function as the inner surface of the packaging container. The side surface of the paper or paperboard substrate constituting the MFC film may be intended to function as the inner surface of the packaging container.

[0102] In some embodiments, 10 or 15 g / m 2 Using LDPE as a laminate adhesive, 10 or 15 g / m 2 Using LDPE as a coating on the MFC film side (back side), 20 g / m 2 as a coating on the opposite side (upper side), when using liquid packaging board as the paper substrate, the oxygen transmission rate of the produced laminate is 1 cc / m at 23 °C and 50% relative humidity (RH). 2 / day or less, 10 cc / m 2 / day or less, for example, 0.1 to 5 cc / m at 23 °C and 80% RH 2 / day or 5 to 10 cc / m 2 / day (in accordance with standard ASTM F1927-20). The manufactured laminate, in accordance with standard ASTM F1249-20, has a water vapor transmission rate of less than 1 g / m per day at 23 °C and 50% relative humidity, less than 10 g / m per day at 38 °C and 85% relative humidity, for example, 0.1 to 5 g / m 2 / day or 5 to 10 g / m 2 / day. 2 / day or 5 to 10 g / m 2 / day.

[0103] Some examples of possible structures of the laminate according to the present disclosure are shown below. - A / B / C - D / A / B / C - A / B / C / D - D / A / B / C / D - D / A / B / C / D / D - D / D / A / B / C / D / D wherein A is a paper substrate or a cardboard substrate, B is a tie layer (adhesive layer), C is an MFC film, and D is a seal and / or liquid barrier such as a polyolefin.

[0104] Generally, products, materials, layers, and processes are described from the perspective of "including" various components or steps, but products, materials, layers, and processes may also be "essentially composed of" or "composed of" various components and steps.

[0105] Considering the above detailed description of the present invention, other modifications and changes will be apparent to those skilled in the art. However, it is clear that such other modifications and changes can be made without departing from the spirit and scope of the present invention.

Claims

1. A method for producing a laminate comprising a paper or cardboard substrate and a microfibrillated cellulose (MFC) film, - A step of providing a first web including a paper or cardboard substrate, - A step of providing a second web of an MFC film, wherein the MFC film has a) an MFC content between 50% and 100% by weight based on total dry weight, b) a moisture content of 5 to 20% by weight, preferably 5 to 15% by weight, and c) a ratio of mechanical tensile index to transverse tensile index of 0.8 to 1.4, preferably 0.8 to 1.2, most preferably 0.9 to 1.

1. - A step of further drying the MFC film of the second web until its moisture content is less than 4% by weight, preferably less than 2% by weight, and most preferably less than 1.5% by weight, - A step of joining the first web and the second web using at least one adhesive layer provided between the first web and the second web in order to form the laminate. A method comprising the bonding step being performed after the further drying step of the MFC film of the second web, wherein the MFC film of the second web has a moisture content of less than 4% by weight, preferably less than 2% by weight, and most preferably less than 1.5% by weight in the bonding step.

2. The method according to claim 1, wherein the step of providing the first web includes providing a first reel of the first web and unwinding the first web from the first reel.

3. The method according to claim 1, wherein the step of providing the second web includes providing a second reel of the second web and unwinding the second web from the second reel, and the further drying step includes further drying the MFC film of the unwound second web.

4. The method according to claim 1, wherein the step of joining the first web and the second web is performed 20 to 1200 milliseconds, preferably 40 to 600 milliseconds, after the further drying step.

5. The method according to claim 1, wherein the step of joining the first web and the second web is performed for a distance of 0.01 to 20 meters, preferably 0.03 to 10 meters, after the further drying step.

6. The method according to claim 1, wherein the step of further drying the MFC film of the second web is selected from the group consisting of contact drying, infrared drying, near-infrared drying, microwave drying, ultraviolet drying, electron beam drying, hot gas impact drying such as hot air impact drying, other types of radiation drying and combinations thereof.

7. The method according to claim 1, wherein the MFC film has an MFC content between 70% and 100% by weight, based on total dry weight.

8. The MFC film has a density of 4 to 80 g / m². ２ Preferably 10 to 60 g / m ２ The method according to claim 1, having a dry basis weight.

9. The method according to claim 1, wherein the MFC film comprises at least one crosslinking agent.

10. The method according to claim 1, wherein the MFC film has a mechanical tensile index of at least 20 Nm / g, preferably at least 30 Nm / g or at least 40 Nm / g.

11. The method according to claim 1, wherein the MFC film has a mechanical strain at break of at least 1.5%, preferably at least 2%, and most preferably at least 3%.

12. The method according to claim 1, wherein the adhesive layer comprises at least 50% by weight of an adhesive polymer or a mixture of adhesive polymers, based on dry weight.

13. The method according to claim 1, wherein the adhesive layer comprises one or more adhesive polymers selected from the group consisting of polyolefins, polyesters, polyurethanes, and acrylic copolymers.

14. The method according to claim 1, wherein the adhesive layer comprises at least 50% by weight of a water-soluble polymer or a mixture of water-soluble polymers, based on dry weight.

15. The method according to claim 1, wherein at least one of the at least one adhesive layers is provided on the surface of the first web before the joining step.

16. The method according to claim 1, wherein at least one of the at least one adhesive layers is provided on the surface of the second web before the joining step.

17. The method according to claim 1, wherein the joining step includes joining the first web and the second web using the at least one adhesive layer in a lamination station including at least one lamination nip.

18. The method according to claim 1, wherein the joining step includes joining the first web and the second web in a lamination station including a lamination nip, and at least one of the at least one adhesive layer is formed and provided between the first web and the second web in the lamination nip.