laminate

Abstract

The present invention relates to a packaging material in the form of a laminate comprising a paper or paperboard substrate and a barrier film. The barrier film is based on microfibrillated cellulose. The laminate comprises a paper or paperboard substrate, wherein the substrate is in contact with a first adhesive layer, which first adhesive layer is in contact with a second adhesive layer, which second adhesive layer is in contact with a barrier film. The invention also relates to a method for manufacturing such a laminate.

Description

TECHNICAL FIELD

[0001] The present invention relates to a packaging material in the form of a laminate comprising a paper or paperboard substrate and a barrier film. The barrier film is based on microfibrillated cellulose. The laminate has excellent grease barrier properties, good interlayer adhesion strength, and contains a high proportion of renewable material. The invention also relates to a method for manufacturing such a laminate. BACKGROUND

[0002] Coating of paper and paperboard with plastics is commonly used to combine the mechanical properties of paperboard with the barrier and sealing properties of e.g. polymeric films. However, in many cases the grease barrier properties of polymeric coated paperboard are still insufficient, or the use of non-renewable polymeric material is required.

[0003] An alternative to overcome the above-mentioned problems of providing a packaging material with a barrier coating that at the same time provides good repulpability is to use water-soluble polymers such as cellulose derivatives or polyvinyl alcohol. The drawbacks of these are typically low solid content and the need for high coating weights. This type of coating concept also increases the risk of drying induced stress and dimensional stability problems. Recently, microfibrillated cellulose (MFC) films have been developed, where defibrillated cellulose fibrils are suspended in e.g. water and thereafter reorganize and rebind together to form a dense film with excellent barrier properties. Unfortunately, the barrier properties of such MFC films tend to deteriorate at high humidity and in contact with water.

[0004] When preparing a laminate comprising a paper or paperboard substrate and a MFC film, it is essential but challenging to obtain sufficient adhesion between the substrate and the MFC film, especially at low adhesive dosages. Furthermore, it is important that the laminate is essentially free from curling and has high dimensional stability also at high relative humidity.

[0005] Hence, there is still a need for improved solutions to provide a packaging material in the form of a laminate with grease barrier properties, while using as little non-renewable material as possible. SUMMARY

[0006] Surprisingly it has been found that a packaging material in the form of a laminate with excellent grease barrier properties can be prepared without the use of high temperatures and with a very high proportion of renewable materials. Surprisingly it has also been found that excellent bending stiffness of the laminate is obtained. It is therefore an object of the present invention to provide an improved laminate with excellent grease barrier properties and bending stiffness. Furthermore, it has been found that a laminate substantially free of curling can be obtained (e.g. can be measured according to the ISO 11556:2005 standard). A particular benefit of the present invention is that a laminate can be obtained wherein the side with grease barrier properties is substantially free of plastic and is suitable for use in contact with food.

[0007] The present invention also relates to a method of preparing a laminate comprising the steps of:

[0008] a) providing a paper or paperboard substrate;

[0009] b) applying a first adhesive to the paper or paperboard substrate;

[0010] c) providing a barrier film comprising at least 50 wt% microfibrillated cellulose (MFC);

[0011] d) applying a second adhesive to the barrier film;

[0012] e) laminating the products of steps b) and d) together such that the first adhesive layer is in contact with the second adhesive layer.

[0013] Steps c) and d) can be performed separately, whereby the barrier film is provided with the second adhesive alone, followed by step e).

[0014] The present invention relates to a laminate comprising a paper or paperboard substrate, wherein the substrate is in contact with a first adhesive layer, the first adhesive layer is in contact with a second adhesive layer, the second adhesive layer is in contact with a barrier film, the barrier film comprises at least 50 wt% microfibrillated cellulose (MFC).

[0015] The present invention also relates to the use of the laminate as a packaging material.

[0016] The present invention also relates to a packaging product comprising the laminate. DETAILED DESCRIPTION

[0017] As used herein, the term paper refers to a material made in a sheet from wood pulp or other fibrous material containing cellulose fibers, used for writing, drawing, or printing on, or as a packaging material.

[0018] As used herein, the term "paperboard" refers to a strong, thick paper or cardboard containing cellulose fibers used for 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.

[0019] The paper or paperboard used as a substrate according to the present invention is prepared using methods known in the art. The paperboard can be, for example, SBS board, solid bleached board (SBB), solid unbleached board (SUB), folding box board (FBB), liner for corrugated board. It can also be paper, such as greaseproof paper, glassine paper, parchment paper, or bag paper.

[0020] The paper or paperboard substrate used in the laminate according to the present invention can comprise a plurality of layers. In one embodiment of the present invention, the paper or paperboard substrate comprises at least 10% recycled material, such as at least 20% or at least 40% or at least 50% or at least 60% or at least 70% recycled material, which can be pre-consumer or post-consumer rejects. A benefit of the laminate according to the present invention is that migration of ink residues, such as mineral oil or ink components or other contaminants, from the recycled material in the substrate into other parts of the laminate is minimized according to the present invention.

[0021] MFC has been identified as an interesting component for use in barrier films for paper and paperboard packaging materials. It has been found that MFC films provide a low oxygen transmission rate under conditions of moderate temperature and humidity, for example at 50% relative humidity and 23°C. Unfortunately, the barrier properties of such MFC films tend to deteriorate significantly at higher temperatures and humidity, for example at 85% relative humidity and 38°C, which makes the film unsuitable for many packaging applications requiring grease barrier properties.

[0022] The present inventors have now found that these deficiencies of prior art laminates comprising MFC can be remedied by providing a first adhesive layer and a second adhesive layer between the paper or paperboard substrate and the barrier film.

[0023] The adhesives used according to the present invention are adhesives commonly used for the preparation of laminates used as packaging products. The adhesives are typically provided in liquid form, for example in the form of a dispersion, emulsion or solution. The first adhesive, the second adhesive or both can also be provided in the form of a foam. If a foam is used, the density of the foam is preferably less than 1.0 kg / dm 3 , more preferably less than 0.9 kg / dm 3 and most preferably less than 0.8 kg / dm 3 , such as less than 0.7 kg / dm 3 . A benefit of using a foam is that the amount of transferred liquid can be reduced, thereby reducing the risk of dimensional stability and curling issues.

[0024] The first adhesive layer used according to the present application is preferably applied to the surface of the paper or paperboard substrate using methods known in the art. It can be applied in an online process when the paper or paperboard substrate is produced or separately, preferably in a printing machine. When applied, the first adhesive preferably has a solids content of at least 20 wt.%, preferably at least 30 wt.%, more preferably at least 40 wt.% or at least 50 wt.%. By using an adhesive with such a high solids content, the amount of liquid transferred and migrated into the substrate is minimized and curling of the laminate can be avoided. The amount of the first adhesive layer is in the range of 1 to 20 gsm, preferably in the range of 1 to 10 gsm. The amount of liquid, such as water or solvent, applied as part of the first adhesive is preferably less than 10 gsm, more preferably less than 8 gsm, most preferably less than 6 gsm. Preferably, the first adhesive layer is selected such that it adheres well to the substrate. The first adhesive layer is prepared from one or more adhesives and preferably has a high level of tack. If more than one adhesive is used in the first adhesive layer, the adhesives can be provided in the form of a mixture or in the form of one or more sub-layers in the first adhesive layer. The glass transition temperature of the first adhesive is preferably in the range of -20°C to 60°C, such as between 0°C to 40°C or between 0°C to 20°C. Suitable adhesives include terpolymer based adhesives, styrene / acrylate emulsions, which can include co-adhesives such as starch, dextrin, as well as polyvinyl acetate and polyvinyl alcohol dispersions. The first adhesive can also include additives, such as WVTR chemicals. The WVTR chemical is preferably a film forming polymer, such as a styrene / acrylate emulsion, PVDC, PVOH or modified PVOH polymer, a wax and / or an oil based emulsion.

[0025] The second adhesive layer used according to the present application is preferably applied to the surface of the barrier film using methods known in the art. It can be applied in an in-line process when the barrier film is produced or separately. When applied, the second adhesive preferably has a solids content of at least 20 wt.%, preferably at least 30 wt.%. By using an adhesive with such a high solids content, the amount of liquid migrating into the barrier film is minimized and deterioration of the barrier film can be avoided. The amount of the second adhesive layer is in the range of 1 to 20 gsm, preferably in the range of 1 to 10 gsm. Preferably, the adhesive(s) in the second adhesive layer are different from the ones in the first adhesive layer. Preferably, the second adhesive is chosen such that it adheres well to the barrier film. The second adhesive layer is prepared from one or more adhesives. Suitable adhesives include adhesives based on terpolymers, styrene / acrylate emulsions, which can contain co-adhesives such as starch, dextrin, as well as polyvinyl acetate and polyvinyl alcohol dispersions. The glass transition temperature of the second adhesive is preferably higher than 30°C, preferably higher than 40°C. The second adhesive layer can optionally be subjected to drying, such as IR drying, prior to lamination. If more than one adhesive is used in the second adhesive layer, the adhesives can be provided in the form of a mixture or in the form of one or more sub-layers in the first adhesive layer. If the second adhesive layer comprises more than one adhesive, it is preferred that the adhesive or sub-layers of adhesives facing the barrier film have a high water resistance to minimize water uptake into the barrier film.

[0026] Lamination can be carried out using methods known in the art. Lamination can for example be carried out in a printing press, wherein the first adhesive is preferably applied to the paper or paperboard substrate. The second adhesive is preferably applied to the barrier film. Subsequently, the barrier film is laminated to the paper or paperboard substrate such that the surfaces of the first and second adhesive layers are in contact with and adhere to each other to obtain a laminate according to the present application.

[0027] According to the present application, lamination is carried out at a temperature between 30°C and 200°C, preferably at a temperature between 30°C and 90°C (temperature measured on the barrier surface).

[0028] The laminate according to the present application provides excellent grease barrier properties. Grease barrier properties can be quantified by measuring the KIT value (TAPPI T559) on the barrier film side of the laminate. The laminate according to the present application preferably has a KIT value of at least 10, such as 11 or 12.

[0029] The laminate according to the present application typically has a low gloss on the barrier film side (i.e. the side facing away from the substrate as well as the first and second adhesive layers), preferably lower than 60, more preferably lower than 50, even more preferably lower than 40, and most preferably lower than 30. Gloss is determined according to ISO 8254-1 at 75°C.

[0030] The barrier film comprises at least 50 wt.-% of MFC, based on the weight of the barrier film. The barrier film can also be described as a MFC film. The barrier film preferably has a low water uptake. The density of the barrier film is preferably greater than 800 kg / m 3 and more preferably greater than 850 kg / m 3 and most preferably greater than 900 kg / m 3 or 950 kg / m 3 The barrier film preferably comprises less than 15 wt.-% of inorganic material, more preferably less than 10 wt.-% of inorganic material.

[0031] The barrier film used according to the present application preferably has a Gurley Hill porosity value of at least 2000 s / 100 ml, more preferably at least 10000 s / 100 ml, determined according to ISO 5636 / 6, before the adhesive is applied. The barrier film preferably has a PPS10 roughness (determined according to ISO 8791-4:2007) of greater than 1.5 pm, more preferably greater than 2 pm, before the adhesive is applied.

[0032] The barrier film used according to the present application has a low oil absorbency. Preferably, the barrier film is omniphobic, i.e. provides temporary resistance to water and oil.

[0033] The barrier film used according to the present application preferably has a Cobb value (Cobb 30s (H20), determined according to ISO 535:2014 after 30 seconds) of less than 35 g / m 2 , preferably less than 30 g / m 2 , more preferably in the range of 5 to 25 g / m 2 , such as in the range of 15 to 25 g / m 2 , before the adhesive is applied.

[0034] In the context of patent applications, microfibrillated cellulose (MFC) is understood to mean a nanoscale cellulose particle fiber or fibril having at least one dimension less than 100 nm. MFC includes cellulose or lignocellulose fibers that are partially or fully fibrillated. The liberated fibrils have a diameter less than 100 nm, while the actual fibril diameter or particle size distribution and / or aspect ratio (length / width) depends on the source and manufacturing method. The smallest fibrils are called primary fibrils and have a diameter of about 2-4 nm (see, e.g., Chinga-Carrasco, G., Cellulose fibres, nanofibrils and microfibrils,: The morphological sequence of MFC components from a plant physiology and fibre technology point of view, Nanoscale research letters 2011, 6:417), while the aggregated form of primary fibrils, which are also commonly defined as microfibrils (Fengel, D., Ultrastructural behavior of cell wall polysaccharides, Tappi J., March 1970, Vol 53, No. 3.) are the main product obtained when MFC is prepared, e.g., by using an extended refining process or pressure drop disintegration process. Depending on the source and manufacturing process, the length of the fibrils can vary from about 1 micron to more than 10 microns. Coarse MFC grades can contain a significant portion of fibrillated fibers, i.e., protruding fibrils from the tube cells (cellulose fibers), and a certain amount of liberated fibrils from the tube cells (cellulose fibers).

[0035] MFC has different abbreviations, such as cellulose microfibril, fibrillated cellulose, nanofibrillated cellulose, fibril aggregate, nanoscale cellulose fibril, cellulose nanofiber, cellulose nanofibril, cellulose microfiber, cellulose fibril, microfibril cellulose, microfibril aggregate, and cellulose microfibril aggregate. MFC can also be characterized by various physical or physicochemical properties, such as its large surface area or its ability to form a gel-like material at low solids content (1-5 wt%) when dispersed in water. The cellulose fibers are preferably fibrillated to such an extent that the resulting MFC has a final specific surface area of about 1 to about 200 m 2 / g, or more preferably 50-200 m 2 / g, when determined with the BET method on freeze-dried material.

[0036] The MFC used in the barrier film preferably has a FS5 fines level of less than 100, preferably less than 90. The MFC used in the barrier film preferably has a FS5 fibrillation index of higher than 1.5, more preferably higher than 1.8 or higher than 2.0. The fines level and the fibrillation index can be measured using a Valmet FS5 Fiber Image Analyzer.

[0037] There are various methods of making MFC, such as single or multiple pass refining, pre-hydrolysis followed by fibril refining or high shear disintegration or liberation. In order to make MFC production both energy efficient and sustainable, one or several pre-treatment steps are often required. Thus, the cellulose fibers of the pulp to be utilized can be pre-treated, e.g. enzymatically or chemically, to hydrolyze or swell the fibers or to reduce the amount of hemicellulose or lignin. The cellulose fibers can be chemically modified prior to fibrillation so that the cellulose molecules contain other (or more) functional groups than found in native cellulose. Such groups include inter alia carboxymethyl (CMC), aldehyde and / or carboxyl (cellulose obtained by N-oxyl mediated oxidation, e.g. "TEMPO"), quaternary ammonium (cationic cellulose) or phosphoryl. After modification or oxidation in one of the above methods, it is easier to disintegrate the fibers into MFC or nanofibrils.

[0038] The nanofibrillar cellulose can contain some hemicellulose, the amount of which depends on the plant source. The mechanical disintegration of the pre-treated fibers, e.g. hydrolyzed, pre-swollen or oxidized cellulose raw material, is performed with suitable equipment, such as refiners, grinders, homogenizers, colloiders, friction grinders, ultrasonic generators, fluidizers such as microfluidizers, macrofluidizers or homogenizers of the fluidizer type. Depending on the MFC production method, the product can also contain fines or nanocrystalline cellulose or other chemicals present in wood fibers or papermaking processes. The product can also contain various amounts of micro-sized fiber particles that have not been effectively fibrillated.

[0039] MFC can be made from wood cellulose fibers from both hardwood or softwood fibers. It can also be made from microbial sources, agricultural fibers such as wheat straw pulp, bamboo, bagasse or other non-wood fiber sources. It is preferably made from pulp including pulp from virgin fibers, e.g. mechanical, chemical and / or thermomechanical pulp. It can also be made from broke or recycled paper.

[0040] The MFC of the barrier film can be unmodified MFC or chemically modified MFC or a mixture thereof. Preferably, the MFC is unmodified MFC. By unmodified MFC is meant MFC made from unmodified or native cellulose fibers. The preferred fibers can be, for example, bleached kraft fibers from hardwood or softwood or a mixture of these. The unmodified MFC can be a single type of MFC or it can comprise a mixture of two or more types of MFC, for example differing in the selection of the cellulose raw material or the manufacturing method. By chemically modified MFC is meant MFC made from cellulose fibers that have undergone chemical modification prior to, during or after fibrillation. In some embodiments, the MFC is chemically modified MFC. The chemically modified MFC can be a single type of chemically modified MFC or it can comprise a mixture of two or more types of chemically modified MFC, for example differing in the type of chemical modification, the selection of the cellulose raw material or the manufacturing method.

[0041] The barrier film can consist only of MFC or it can comprise a mixture of MFC and other ingredients or additives. The barrier film comprises MFC as its main ingredient based on the total dry weight of the barrier film. The barrier film contains at least 50 weight-%, preferably at least 70 weight-%, more preferably at least 80 weight-% of MFC based on the total dry weight of the barrier layer.

[0042] The barrier film can be prepared as a stand-alone MFC film for lamination to a substrate. The stand-alone film is prepared using methods known in the art, for example on a paper machine or using techniques such as cast forming. The film can be treated using methods known in the art, such as calendering and / or supercalendering. The barrier film can comprise a wide range of different amounts of ingredients to improve the final properties of the product or the processing of the coating. The barrier film can further comprise additives such as polysaccharides and / or cellulose derivatives (starch, carboxymethyl cellulose, methyl cellulose, hydroxypropyl cellulose, hemicellulose), fillers, retention or drainage chemicals, flocculation additives, anti-flocculation additives, cross-linking agents, dry strength additives, humectants, softening agents or a mixture thereof. The barrier film can further comprise additives that will improve the different properties of the mixture and / or the produced film (such as latex and / or polyvinyl alcohol (PVOH)) to enhance the ductility of the film.

[0043] In some embodiments, the barrier film further comprises a polymeric binder. In some embodiments, the barrier film further comprises PVOH. The PVOH can be a single type of PVOH or it can comprise a mixture of two or more types of PVOH, for example differing in degree of hydrolysis or viscosity. The PVOH can for example have a degree of hydrolysis in the range of 80-99 mole %, preferably in the range of 88-99 mole %. Furthermore, the PVOH can preferably have a viscosity higher than 5 mPa x s in a 4% aqueous solution at 20°C DIN 53015 / JIS K 6726.

[0044] In some embodiments, the barrier film further comprises a pigment. The pigment can for example comprise inorganic particles of talc, silicates, carbonates, alkaline earth carbonates and ammonium carbonates, or oxides such as transition metal oxides and other metal oxides. The pigment can also comprise nano-sized pigments such as nano-clays and nanoparticles of layered mineral silicates, for example selected from the group consisting of montmorillonite, bentonite, kaolinite, hectorite and hallyosite.

[0045] In some embodiments, the pigment is selected from the group consisting of nano-clays and nanoparticles of layered mineral silicates, more preferably bentonite.

[0046] The basis weight (corresponding to thickness) of the barrier film is preferably in the range of 15 to 80 gsm (grams per square meter), preferably in the range of 15 to 50 gsm, more preferably in the range of 15 to 40 gsm or 20 to 35 gsm. The basis weight of the barrier film can for example depend on its mode of manufacture. The barrier film is preferably translucent. The barrier film has preferably been subjected to calendering and / or supercalendering prior to use in the laminate according to the present application.

[0047] The barrier film can be coated on one side (the side opposite to the side on which the second adhesive is provided) with a polymer to adjust dimensional stability. The polymer used is preferably a polysaccharide, a cellulose derivative, PVOH, PVOH / Ac, a wax, polyethylene glycol or a latex dispersion. The amount of polymer is preferably in the range of 1 to 8 gsm, more preferably in the range of 2 to 5 gsm.

[0048] The paper or paperboard substrate used in the laminate according to the present application preferably has a grammage in the range of 20-500 g / m 2 more preferably in the range of 80-400 g / m 2basis weight within the range of 50-300 g / m2. The paper or paperboard is optionally coated, such as mineral coated, to improve smoothness and printability. Such mineral coating can be provided on one or both sides of the substrate, then being part of the substrate, in the context of the present invention. The paper or paperboard substrate can be subjected to surface sizing on at least one side of the paper or paperboard. Such surface sizing is then part of the substrate, in the context of the present invention.

[0049] In some non-limiting embodiments, the laminate according to the present invention has the following general structure:

[0050] - paper / first adhesive layer / second adhesive layer / barrier film

[0051] - paper / first adhesive layer / second adhesive layer / barrier film / protective polymer layer

[0052] - protective polymer layer / paper / first adhesive layer / second adhesive layer / barrier film

[0053] - protective polymer layer / paper / first adhesive layer / second adhesive layer / barrier film / protective polymer layer

[0054] - paperboard / first adhesive layer / second adhesive layer / barrier film

[0055] - paperboard / first adhesive layer / second adhesive layer / barrier film / protective polymer layer

[0056] - protective polymer layer / paperboard / first adhesive layer / second adhesive layer / barrier film

[0057] - protective polymer layer / paperboard / first adhesive layer / second adhesive layer / barrier film / protective polymer layer.

[0058] The protective polymer layer comprises for example a polyolefin or a polyester, such as a bio-based polyolefin or polyester or a varnish. The protective polymer layer can comprise one or more polymers. Examples of suitable polymers include polyethylene, PLA, etc. The varnish can for example be a water-based varnish. The protective layer can be added for example by extrusion coating or film lamination. If a varnish is used, it can be added using methods known in the art, such as spraying, rotogravure, etc.

[0059] According to another aspect of the present invention, there is provided a method for manufacturing a laminate, comprising the following steps:

[0060] a) providing a paper or paperboard substrate;

[0061] b) applying a first adhesive to the paper or paperboard substrate;

[0062] c) providing a barrier film comprising at least 50 wt% microfibrillated cellulose (MFC);

[0063] d) applying a second adhesive to the barrier film;

[0064] e) laminating the products of steps b) and d) together such that the first adhesive layer is in contact with the second adhesive layer.

[0065] Lamination can be performed using methods known in the art.

[0066] Steps c) and d) in the above method can be performed separately, such that the barrier film is provided with the second adhesive alone, and step e) is then performed. In such an embodiment, the method for manufacturing a laminate comprises the steps of:

[0067] a) providing a paper or paperboard substrate;

[0068] b) applying a first adhesive to the paper or paperboard substrate;

[0069] c) providing a barrier film comprising at least 50 wt% microfibrillated cellulose (MFC) to which a second adhesive has been applied;

[0070] d) laminating the products of steps b) and c) together such that the first adhesive layer is in contact with the second adhesive layer.

[0071] Example

[0072] Comparative Example 1

[0073] A 2-ply laminate structure was prepared with one adhesive layer using about 7 g / m2of a styrene / acrylate terpolymer adhesive (glass transition point 0°C) applied to the substrate with an anilox, and then pressed together and dried. The plies consisted of 35 gsm brown kraft paper (2 x 35 gsm). The test failed because no inter-ply adhesion was obtained due to uneven distribution of the adhesive. 2

[0074] Comparative Example 2

[0075] In this case, the above brown 35 gsm kraft paper was glue-laminated with the same setup as in Example 1, but now against an uncoated 32 gsm web comprising MFC. The test failed for similar reasons as in Example 1. In both cases, the laminates exhibited dimensional stability problems due to rewetting.

[0076] Example 3

[0077] ​A SBS board with a grammage of 250 gsm, mineral coated on the printing side, was provided as a substrate.

[0078] A MFC film with a grammage of 31 gsm was prepared on a paper machine and subjected to calendering. An adhesive was applied on a rubber plate printing machine in the form of an aqueous dispersion of a terpolymer of vinyl chloride, vinyl acetate and ethylene with a solid content of about 50% and a pH between 6 and 7. The minimum film formation temperature of the polymer was about 45°C. The adhesive also comprised a WVTR chemical. The adhesive components were provided on the MFC film and dried using IR drying. The total amount of adhesive applied was 5 ± 1 g / m 2 and the ratio was 1 :3, i.e. the amount of terpolymer and WVTR chemical applied was 3 times larger than the amount of terpolymer.

[0079] Lamination was performed in a lamination unit. Before laminating the substrate and the MFC film together, a styrene / acrylate terpolymer adhesive was provided on the surface of the SBS board. The substrate was laminated to the film so that the adhesive layers on the substrate and the film became adhered to each other, respectively.

[0080] The obtained laminate did not have any visible wrinkles, bubbles or defects.

[0081] The KIT value of the laminate was 12, determined according to TAPPI T559.

[0082] The resistance to chicken fat was determined (modified ASTM F119-8, performed at 40°C and 0% RH) and it was found that the laminate provided a resistance to chicken fat of more than 48 hours.

[0083] The Gurley-Hill porosity of the laminate was determined according to ISO 5636 / 6 and it was found to be 42300 s / 100ml, which is the maximum value obtainable with the equipment used.

[0084] The water vapour transmission rate (WVTR) of the MFC film after applying the adhesive was 80 g / m 2 per day when measured according to ASTM F1249 at 23°C and 50% RH.

[0085] The oxygen transmission rate (OTR) was less than 10 cc / m 2 per day at 23°C and 50% RH when measured according to standard ASTM D-3985, using a Mocon Oxtran 2 / 22 device.

[0086] To further confirm the quality of the laminate, the cross direction (up, down), machine direction (up and down) and diagonal curl of the blanks were analyzed (visual inspection of the blanks (with printing) with dimensions of 300,5 x 168 mm). No significant curl was found.

[0087] The laminate comprises a large amount of fibres and should be reusable and disintegrable according to PTS RH 021 / 97 with a reject rate of less than 30%, preferably less than 20% and most preferably less than 10%.

[0088] The laminate was compared to a reference laminate using a plastic film instead of the MFC film. It was observed that the curling of the laminate according to the above example was less than the reference sample.

[0089] In light of the above detailed description of the application, other modifications and changes will become apparent to those skilled in the art. However, it should be clear that such other modifications and changes are not to depart from the spirit and scope of the application.

Claims

1. A laminate comprising a paper or paperboard substrate, wherein the substrate is in contact with a first adhesive layer, the first adhesive layer is in contact with a second adhesive layer, the second adhesive layer is in contact with a barrier film, the barrier film comprising at least 50% by weight of microfibrillated cellulose (MFC). The amount of the second adhesive layer is in the range of 1 to 20 gsm. The first adhesive is a terpolymer-based adhesive or a styrene / acrylate emulsion, optionally comprising a co-adhesive, and the first adhesive has a glass transition temperature between -20°C and 60°C. The second adhesive is a terpolymer-based adhesive or a styrene / acrylate emulsion, optionally containing a co-adhesive, and the second adhesive has a glass transition temperature above 30°C.

2. The laminate of claim 1, wherein the barrier membrane comprises at least 70% by weight of MFC based on the total dry weight of the barrier membrane.

3. The laminate of claim 2, wherein the barrier membrane comprises at least 80% by weight of MFC based on the total dry weight of the barrier membrane.

4. The laminate according to any one of the preceding claims, wherein the barrier film further comprises polyvinyl alcohol (PVOH).

5. The laminate according to any one of claims 1-3, wherein the basis weight of the barrier film is in the range of 15 to 80 gsm.

6. The laminate according to claim 5, wherein the basis weight of the barrier film is in the range of 15 to 40 gsm.

7. The laminate according to any one of claims 1-3, wherein the barrier membrane has a Gurley-Hill porosity value of at least 2000 s / 100 ml as determined according to ISO 5636 / 6 before the application of the adhesive.

8. The laminate according to any one of claims 1-3, wherein the barrier film has a PPS10 roughness greater than 1.5 μm before the adhesive is applied.

9. The laminate according to any one of claims 1-3, wherein the barrier film has been calendered or supercalendered prior to use in the laminate.

10. The laminate according to any one of claims 1-3, wherein the KIT value of the laminate is at least 11.

11. The laminate according to any one of claims 1-3, wherein the substrate is an SBS board.

12. A method for manufacturing a laminate, comprising the following steps: a) Provide a paper or paperboard base; b) Apply the first adhesive to the paper or paperboard substrate; c) Provide a barrier membrane containing at least 50% by weight of microfibrillated cellulose (MFC); d) Apply the second adhesive to the barrier film; e) Lay the products from steps b) and d) together so that the first adhesive layer is in contact with the second adhesive layer. The amount of the second adhesive layer is in the range of 1 to 20 gsm. The first adhesive is a terpolymer-based adhesive or a styrene / acrylate emulsion, optionally comprising a co-adhesive, and the first adhesive has a glass transition temperature between -20°C and 60°C. The second adhesive is a terpolymer-based adhesive or a styrene / acrylate emulsion, optionally containing a co-adhesive, and the second adhesive has a glass transition temperature above 30°C.

13. The method of claim 12, wherein the method is performed at least in part in a printing press.