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 in contact with a first adhesive layer, which is in contact with a second adhesive layer, which is in contact with the barrier film. The present invention also relates to a method for producing 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 ply bond strength, and contains a high proportion of renewable materials. The present invention also relates to a method for producing such a laminate. [Background technology]

[0002] Coating paper and paperboard with plastics is often used to combine the mechanical properties of paperboard with the barrier and sealing properties of, for example, polymer films. However, in many cases the grease barrier properties of polymer-coated paperboard are still insufficient or require the use of non-renewable polymer materials.

[0003] One alternative to overcome the above-mentioned problems of providing packaging materials with barrier coatings that simultaneously provide good repulpability is the use of water-soluble polymers such as cellulose derivatives or polyvinyl alcohol. The drawback of these is that low solids content and high coat weights are typically required. This type of coating concept also increases the risk of drying-induced stress and dimensional stability issues. More recently, microfibrillated cellulose (MFC) films have been developed, in which defibrated cellulose fibrils are suspended, for example, in water, then reorganized and recombined to form dense films 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 laminates containing paper or paperboard substrates and MFC films, it is essential to obtain sufficient adhesion between the substrate and the MFC film, which can be difficult, especially when the amount of adhesive is low. Furthermore, it is important that the laminate does not curl substantially and has high dimensional stability even at high relative humidity.

[0005] Thus, there remains a need for improved solutions for imparting grease barrier properties to packaging materials in the form of laminates using as little non-renewable materials as possible. Summary of the Invention

[0006] It has surprisingly been found that packaging materials in the form of laminates with excellent grease barrier properties can be produced without the use of high temperatures and using a very high proportion of renewable materials. It has also surprisingly been found that excellent bending stiffness of the laminates can be obtained. It is therefore an object of the present invention to provide improved laminates with excellent grease barrier properties and bending stiffness. In addition, it has been found that laminates that are essentially curl-free can be obtained (e.g., as can be measured according to the ISO 11556:2005 standard). A particular advantage of the present invention is that a laminate can be obtained in which the grease barrier side is substantially free of plastic, making it suitable for use in contact with food.

[0007] The present invention also provides a method for preparing a laminate, comprising the steps of: a) providing a paper or paperboard substrate; b) applying a first adhesive to a paper or paperboard substrate; c) applying a barrier film comprising at least 50% by weight of microfibrillated cellulose (MFC); d) applying a second adhesive to the barrier film; e) laminating the products of steps b) and d) together so that the first adhesive layer contacts the second adhesive layer. The present invention is directed to a method, including:

[0008] Steps c) and d) can be carried out separately, so that the barrier film is separately applied with the second adhesive and then step e) is carried out.

[0009] The present invention is directed to a laminate comprising a paper or paperboard substrate, the substrate in contact with a first adhesive layer, the first adhesive layer in contact with a second adhesive layer, the second adhesive layer in contact with a barrier film, the barrier film comprising at least 50% by weight of microfibrillated cellulose (MFC).

[0010] The present invention is also directed to the use of the laminate as a packaging material.

[0011] The present invention is also directed to a packaging product comprising the laminate. DETAILED DESCRIPTION OF THE INVENTION

[0012] As used herein, the term paper means a material made into thin sheets from wood pulp or other fibrous substances containing cellulose fibers, used for writing, drawing, or printing, or used as a packaging material.

[0013] As used herein, the term paperboard means a strong, thick paper or cardboard containing cellulose fibers used for boxes and other types of packaging. Paperboard may be either bleached or unbleached, coated or uncoated, and can be produced in a variety of thicknesses, depending on the end-use requirements.

[0014] The paper or paperboard used as a substrate in accordance with the present invention is prepared using methods known in the art. The paperboard may be, for example, SBS board, solid bleached board (SBB), solid unbleached board (SUB), folding box board (FBB), or a corrugated cardboard liner. It may also be paper such as greaseproof paper, glassine paper, parchment paper, or sack paper.

[0015] The paper or paperboard substrate used in the laminate according to the invention may comprise multiple layers. In one embodiment of the invention, the paper or paperboard substrate comprises at least 10% recycled material, for example at least 20%, or at least 40%, or at least 50%, or at least 60%, or at least 70% recycled material, which may be pre-consumer or post-consumer reject. An advantage of the laminate according to the invention is that the migration of ink residues, such as mineral oil or ink components or other contaminants, from the recycled material of the substrate to other parts of the laminate is minimized in accordance with the invention.

[0016] MFC has been identified as an interesting ingredient for use in barrier films for paper and paperboard packaging. MFC films have been found to provide a reduction in oxygen transfer rate at intermediate temperature and humidity conditions, e.g., 50% relative humidity and 23°C. Unfortunately, the barrier properties of such MFC films tend to decrease significantly at higher temperatures and humidities, e.g., 85% relative humidity and 38°C, making the films unsuitable for many packaging applications where grease barrier properties are required.

[0017] The inventors have now found that these deficiencies of prior art laminates comprising MFC can be improved by forming a first adhesive layer and a second adhesive layer between the paper or paperboard substrate and the barrier film.

[0018] The adhesives used in accordance with the present invention are those commonly used in preparing laminates for use as packaging products. The adhesives are usually provided in liquid form, for example as a dispersion, emulsion, or solution. The first adhesive, the second adhesive, or both, can also be provided as a foam. When a foam is used, the density of the foam is preferably 1.0 kg / dm 3 Less than 0.9 kg / dm 3 Less than 0.8 kg / dm 3 Less than, for example, 0.7 kg / dm 3The advantage of using foam is that it reduces the amount of transferred liquid, thereby reducing the risk of dimensional stability and curling problems.

[0019] The first adhesive layer used in accordance with the present invention is preferably applied to the surface of a paper or paperboard substrate using methods known in the art. It can be applied as an online process or separately, preferably on a printing press, during the production of the paper or paperboard substrate. When applied, the first adhesive preferably has a solids content of at least 20% by weight, preferably at least 30% by weight, more preferably at least 40% by weight, or at least 50% by weight. By using an adhesive with such a high solids content, the amount of liquid that migrates and transfers into the substrate is minimized, preventing curling of the laminate. The amount of the first adhesive layer is in the range of 1 to 20 gsm, preferably 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, and most preferably less than 6 gsm. Preferably, the first adhesive layer is selected to provide good adhesion to the substrate. The first adhesive layer is prepared from one or more adhesives, preferably with a high tack level. When two or more adhesives are used in the first adhesive layer, the adhesives can be provided as a mixture or as one or more sublayers within the first adhesive layer. The glass transition temperature of the first adhesive is preferably between -20°C and 60°C, for example, between 0°C and 40°C or between 0°C and 20°C. Suitable adhesives include terpolymer adhesives, styrene / acrylate emulsions, which may contain co-binders such as starch, dextrin, and polyvinyl acetate and polyvinyl alcohol dispersions. The first adhesive may also contain additives such as WVTR chemicals. The WVTR chemicals are preferably film-forming polymers, such as styrene / acrylate emulsions, PVDC, PVOH, or modified PVOH polymers, waxes, and / or oil emulsions.

[0020] The second adhesive layer used in accordance with the present invention is preferably applied to the surface of the barrier film using methods known in the art. It can be applied as an online process or separately during the production of the barrier film. When applied, the second adhesive has a solids content of at least 20% by weight, preferably at least 30% by weight. By using an adhesive with such a high solids content, the amount of liquid that migrates into the barrier film is minimized, preventing degradation of the barrier film. The weight of the second adhesive layer is in the range of 1 to 20 gsm, preferably 1 to 10 gsm. Preferably, the adhesive(s) in the second adhesive layer are not the same as those in the first adhesive layer. Preferably, the second adhesive is selected to provide good adhesion to the barrier film. The second adhesive layer is prepared from one or more adhesives. Suitable adhesives include terpolymer-based adhesives, styrene / acrylate emulsions, etc., and may contain co-binders such as starch and dextrin, as well as dispersions of polyvinyl acetate and polyvinyl alcohol. The glass transition temperature of the second adhesive is preferably greater than 30°C, preferably greater than 40°C. The second adhesive layer may optionally be dried, for example IR dried, before lamination. If more than one adhesive is used in the second adhesive layer, the adhesives may be provided as a mixture or as one or more sublayers within the first adhesive layer. If the second adhesive layer comprises more than one adhesive, it is preferred that the adhesive facing the barrier film, or the sublayer of the adhesive, is highly resistant to water to minimize water uptake into the barrier film.

[0021] The lamination can be carried out using methods known in the art. For example, the lamination can be carried out in a printing press, in which a first adhesive is preferably applied to a paper or paperboard substrate. A second adhesive is preferably applied to a barrier film. Subsequently, the barrier film is laminated onto the paper or paperboard substrate so 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 invention.

[0022] According to the invention, the lamination is carried out at a temperature between 30° C. and 200° C., preferably between 30° C. and 90° C. (measured on the barrier surface).

[0023] The laminates according to the present invention provide excellent grease barrier properties. The grease barrier properties can be quantified by measuring the KIT value (TAPPI T559) on the barrier film side of the laminate. Preferably, the laminates according to the present invention have a KIT value of at least 10, for example 11 or 12. On the barrier film side (i.e., the side facing away from the substrate and the first and second adhesive layers), the laminates according to the present invention typically have a low gloss, preferably less than 60, more preferably less than 50, even more preferably less than 40, and most preferably less than 30. The gloss is determined at 75°C according to ISO 8254-1.

[0024] The barrier film comprises at least 50% by weight of MFC by weight of the barrier film. The barrier film may also be described as an MFC film. The barrier film preferably has low water uptake. The density of the barrier film is preferably 800 kg / m 3 More preferably, 850 kg / m 3 More than 900 kg / m 3 Over or 950 kg / m 3 The barrier film preferably comprises less than 15% by weight of inorganic material, more preferably less than 10% by weight of inorganic material.

[0025] The barrier film used in accordance with the present invention preferably has a Gurley Hill porosity value, determined in accordance with ISO 5636 / 6, of at least 2000 s / 100 ml, more preferably at least 10000 s / 100 ml, before application of the adhesive. The barrier film preferably has a PPS10 roughness (determined in accordance with ISO 8791-4:2007) of greater than 1.5 μm, more preferably greater than 2 μm, before application of the adhesive.

[0026] The barrier films used in accordance with the present invention have low oil absorption. Preferably, the barrier film is omniphobic, i.e., provides temporary resistance to both water and oil.

[0027] The barrier film used in accordance with the present invention preferably has a Cobb value (Cobb 30s (H2O), determined after 30 seconds according to ISO 535:2014) of 35 g / m2 or more before the adhesive is applied. 2 less than 30 g / m 2 More preferably, it is 5 to 25 g / m 2 range, e.g., 15 to 25 g / m 2 The range is.

[0028] Microfibrillated cellulose (MFC) is understood in the context of patent applications to refer to nanoscale cellulose particle fibers or fibrils with at least one dimension less than 100 nm. MFC includes partially or fully fibrillated cellulose or lignocellulose fibers. While the diameter of the liberated fibrils is less than 100 nm, the actual fibril diameter or particle size distribution and / or aspect ratio (length / width) depend on the source and production method. The smallest fibrils, called elementary fibrils, are approximately 2–4 nm in diameter (see, e.g., Chinga-Carrasco, G., Cellulose fibers, nanofibrils, and microfibrils: The morphological sequence of MFC components from a plant physiology and fiber technology point of view, Nanoscale Research Letters 2011, 6:417). However, aggregated forms of elementary fibrils, also defined as microfibrils (Fengel, D., Ultrastructural behavior of cell wall polysaccharides, Tappi J., March 1970, Vol. 53, No. 3), are typically the primary product obtained when creating MFCs, for example, using extended purification or pressure-drop disintegration processes. Depending on the source and manufacturing process, fibril lengths can vary from approximately 1 to over 10 micrometers. Coarse MFC grades may contain a substantial fraction of fibrillated fibers, i.e., fibrils protruding from the tracheids (cellulose fibers), as well as a certain amount of fibrils free from the tracheids (cellulose fibers).

[0029] MFC has different acronyms, including cellulose microfibrils, fibrillated cellulose, nanofibrillated cellulose, fibril aggregates, nanoscale cellulose fibrils, cellulose nanofibers, cellulose nanofibrils, cellulose microfibers, cellulose fibrils, microfibrillated cellulose, microfibril aggregates, and cellulose microfibril aggregates. MFC can also be characterized by various physical or physicochemical properties, such as its large surface area and its ability to form gel-like materials at low solids contents (1–5 wt%) when dispersed in water. Cellulose fibers are characterized by the fact that the final specific surface area of ​​the formed MFC is approximately 1–200 m2, as measured on freeze-dried material using the BET method. 2 / g, or more preferably 50 to 200 m 2 It is preferable that the fiber is fibrillated to a certain extent at 1 / g.

[0030] MFC used in barrier films preferably have an FS5 fines level of less than 100, preferably less than 90. MFC used in barrier films preferably have an FS5 Fibrillation Index of greater than 1.5, more preferably greater than 1.8 or greater than 2.0. Fines level and Fibrillation Index can be measured using a Valmet FS5 Fiber Image Analyzer.

[0031] Various methods exist for creating MFCs, including single- or multiple-pass purification, prehydrolysis followed by fibril purification, or high-shear degradation or liberation. To make MFC production both energy-efficient and sustainable, one or more pretreatment steps are typically required. Thus, the cellulose fibers of the pulp utilized may be enzymatically or chemically pretreated, for example, to hydrolyze or expand the fibers or to reduce the amount of hemicellulose or lignin. Cellulose fibers may be chemically modified before fibrillation, thereby containing functional groups other than (or greater than) those found in native cellulose. Such groups include, among others, carboxymethyl (CMC), aldehyde and / or carboxyl groups (cellulose obtained by N-oxyl-mediated oxidation, e.g., "TEMPO"), quaternary ammonium (cationic cellulose), or phosphoryl groups. After modification or oxidation by one of the above methods, the fibers are easier to decompose into MFCs or nanofibrils.

[0032] Nanofibrillar cellulose may contain some hemicellulose, the amount of which depends on the plant source. Mechanical decomposition of pretreated fibers, such as hydrolyzed, preswollen, or oxidized cellulose feedstocks, is carried out in suitable equipment, such as refiners, grinders, homogenizers, colloidal grinders, attrition mills, ultrasonicators, and fluidizers, such as microfluidizers, macrofluidizers, or fluidized homogenizers. Depending on the MFC production method, the product may also contain fines, nanocrystalline cellulose, or other chemicals present in wood fiber or papermaking processes. The product may also contain varying amounts of micron-sized fiber particles that are not efficiently fibrillated.

[0033] MFC is produced from wood cellulose fibers, both hardwood and softwood. It can also be made from microbial sources, agricultural fibers such as straw pulp, bamboo, bagasse, or other non-wood fiber sources. It is preferably made from pulp, including pulp from virgin fibers, such as mechanical, chemical, and / or thermomechanical pulps. It can also be made from damaged or recycled paper.

[0034] The MFC of the barrier film may be unmodified or chemically modified, or a mixture thereof. Preferably, the MFC is unmodified. Unmodified MFC refers to an MFC made from unmodified or native cellulose fibers. Preferred fibers may be, for example, bleached kraft fibers from hardwoods or softwoods, or a mixture thereof. The unmodified MFC may be a single type of MFC, or it may comprise a mixture of two or more types of MFC, differing, for example, in the choice of cellulose raw material or manufacturing method. Chemically modified MFC refers to an MFC made from cellulose fibers that have been chemically modified before, during, or after fibrillation. In some embodiments, the MFC is chemically modified. The chemically modified MFC may be a single type of chemically modified MFC, or it may comprise a mixture of two or more types of chemically modified MFC, differing, for example, in the type of chemical modification, the choice of cellulose raw material, or the manufacturing method.

[0035] The barrier film may consist solely of MFC, or it may contain a mixture of MFC and other components or additives. The barrier film comprises MFC as its major component, based on the total dry weight of the barrier film. The barrier film comprises at least 50 wt. %, preferably at least 70 wt. %, more preferably at least 80 wt. % MFC, based on the total dry weight of the barrier layer.

[0036] The barrier film may be prepared as a free-standing MFC film for lamination to a substrate. The free-standing film may be prepared using methods known in the art, for example, on a paper machine or using techniques such as casting. The film may be subjected to processes such as calendering and / or supercalendering using methods known in the art. The barrier film may contain a wide range of ingredients in varying amounts to improve the final performance of the product or the processing of the coating. The barrier film may further contain additives, such as polysaccharides and / or cellulose derivatives (starch, carboxymethyl cellulose, methyl cellulose, hydroxypropyl cellulose, hemicellulose), fillers, retention or drainage chemicals, flocculation additives, deflocculating additives, crosslinking agents, dry strength additives, wetting agents, softening agents, or mixtures thereof. The barrier film may further contain additives to improve different properties of the mixture and / or the resulting film, such as latex and / or polyvinyl alcohol (PVOH), to enhance the ductility of the film.

[0037] In some embodiments, the barrier film further comprises a polymeric binder. In some embodiments, the barrier film further comprises PVOH. The PVOH may be a single type of PVOH or may comprise a mixture of two or more types of PVOH, differing, for example, in degree of hydrolysis or viscosity. The PVOH may, for example, have a degree of hydrolysis in the range of 80 to 99 mol%, preferably in the range of 88 to 99 mol%. Furthermore, the PVOH may preferably have a viscosity of greater than 5 mPa×s in a 4% aqueous solution at 20°C, according to DIN 53015 / JIS K 6726.

[0038] In some embodiments, the barrier film further comprises a pigment. The pigment may comprise, for example, inorganic particles of talc, silicates, carbonates, alkaline earth metal carbonates and ammonium carbonate, or oxides, such as transition metal oxides and other metal oxides. The pigment may also comprise nano-sized pigments, such as nanoclays and nanoparticles of layered mineral silicates, selected from the group including, for example, montmorillonite, bentonite, kaolinite, hectorite, and halloysite.

[0039] In some embodiments, the pigment is selected from the group consisting of nanoclays and nanoparticles of layered mineral silicates, more preferably bentonite.

[0040] The basis weight (corresponding to the 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 may depend, for example, on its manufacturing mode. The barrier film is preferably translucent. The barrier film is preferably calendered and / or supercalendered before being used in the laminate according to the invention.

[0041] The barrier film may be coated on one side (the side opposite to the side on which the second adhesive is applied) with a polymer to adjust dimensional stability. The polymer used is preferably a polysaccharide, cellulose derivative, PVOH, PVOH / Ac, wax, polyethylene glycol, or 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.

[0042] The paper or paperboard substrate used in the laminate according to the invention preferably has a basis weight of 20 to 500 g / m 2 range, more preferably 80 to 400 g / m 2The paper or paperboard substrate may be provided with a surface sizing on at least one side of the paper of the paperboard. Such a surface sizing is then considered to be part of the substrate in the context of the present invention.

[0043] In some non-limiting embodiments, laminates according to the present invention have the following general structure: - Paper / First adhesive layer / Second adhesive layer / Barrier film - Paper / First adhesive layer / Second adhesive layer / Barrier film / Protective polymer layer - Protective polymer layer / paper / first adhesive layer / second adhesive layer / barrier film - Protective polymer layer / paper / first adhesive layer / second adhesive layer / barrier film / protective polymer layer - Paperboard / First adhesive layer / Second adhesive layer / Barrier film - Paperboard / First adhesive layer / Second adhesive layer / Barrier film / Protective polymer layer - Protective polymer layer / Paperboard / 1st adhesive layer / 2nd adhesive layer / Barrier film - Protective polymer layer / paperboard / first adhesive layer / second adhesive layer / barrier film / protective polymer layer It has.

[0044] The protective polymer layer may comprise, for example, a polyolefin or polyester, such as a bio-based polyolefin or polyester, or a varnish. The protective polymer layer may comprise one or more polymers. Examples of suitable polymers include polyethylene, PLA, and the like. The varnish may be, for example, a water-based varnish. The protective layer may be applied, for example, by extrusion coating or film lamination. If a varnish is used, it may be applied using methods known in the art, such as spraying, rotogravure, and the like.

[0045] According to a further aspect of the present invention there is provided a method of manufacturing a laminate comprising the steps of: a) providing a paper or paperboard substrate; b) applying a first adhesive to a paper or paperboard substrate; c) applying a barrier film comprising at least 50% by weight of microfibrillated cellulose (MFC); d) applying a second adhesive to the barrier film; e) laminating the products of steps b) and d) together so that the first adhesive layer contacts the second adhesive layer. The present invention provides a method comprising:

[0046] Lamination can be performed using methods known in the art.

[0047] Steps c) and d) of the above method can be performed separately, such that the second adhesive is separately applied to the barrier film and then step e) is performed. In such an embodiment, the method of producing the laminate comprises: a) providing a paper or paperboard substrate; b) applying a first adhesive to a paper or paperboard substrate; c) applying a barrier film comprising at least 50% by weight of microfibrillated cellulose (MFC) and having a second adhesive applied thereto; d) laminating the products of steps b) and c) together so that the first adhesive layer contacts the second adhesive layer. Includes: [Example]

[0048] Comparative Example 1 Approximately 7 g / m applied by anilox onto the substrate before being pressed together and dried. 2 A two-ply laminate structure with one adhesive layer was prepared using a styrene / acrylate terpolymer adhesive (glass transition temperature 0°C). The layers consisted of two 35 gsm brown kraft paper sheets (2 x 35 gsm). The test failed due to uneven distribution of the adhesive, which prevented adhesion between the layers.

[0049] Comparative Example 2 In this case, the brown 35 gsm kraft paper described above was adhesively laminated using the same setup as in Example 1, but this time to an uncoated 32 gsm web containing MFC. The test failed for the same reasons as in Example 1. In both cases, the laminates exhibited dimensional stability problems on rewet.

[0050] Example 3 A mineral coated SBS board of 250 gsm basis weight was provided as the substrate on the printing side.

[0051] An MFC film with a basis weight of 31 gsm was prepared on a paper machine and calendered. On a flexographic printing press, the adhesive was applied in the form of an aqueous dispersion of a terpolymer of vinyl chloride, vinyl acetate, and ethylene, with a solids content of approximately 50% and a pH between 6 and 7. The minimum film-forming temperature of the polymer was approximately 45°C. The adhesive also contained WVTR chemicals. The adhesive components were applied to 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 three times that of terpolymer.

[0052] The lamination was carried out in layers. A styrene / acrylate terpolymer adhesive was applied to the surface of the SBS board, and then the substrate and MFC film were laminated together. The substrate was laminated to the film so that the adhesive layers on the substrate and film were adhered to each other.

[0053] None of the resulting laminates had any visible wrinkles, bubbles or defects.

[0054] The KIT value of the laminate was 12 as determined based on TAPPI T559.

[0055] Chicken fat resistance was determined (modification of ASTM F119-8, performed at 40° C. and 0% RH) and the laminate was found to provide chicken fat resistance for greater than 48 hours.

[0056] The Gurley Hill porosity of the laminate was determined according to ISO 5636 / 6 and found to be 42300 s / 100 ml, which is the maximum value obtainable with the equipment used.

[0057] The water vapor transmission rate (WVTR) of the MFC film after adhesive application is 80 g / m when measured at 23°C and 50% RH according to ASTM F1249. 2 / day.

[0058] Oxygen transmission rate (OTR) is 10 cc / m at 23°C and 50% RH when measured with a Mocon Oxtran2 / 22 device according to standard ASTM D-3985 2 was less than / day.

[0059] To further confirm the quality of the laminate, blanks (visual inspection of blanks with prints measuring 300.5 x 168 mm) were analyzed for cross-direction (upward, downward), machine-direction (upward, downward) and diagonal curl. No obvious curl was detected.

[0060] The laminate contains a high amount of fibre and should be reusable and disintegrable with a rejection rate of less than 30%, preferably less than 20%, most preferably less than 10% according to PTS RH 021 / 97.

[0061] The laminates were compared to control laminates in which a plastic film was used instead of the MFC film. The curl of the laminates according to the above examples was observed to be less than the reference sample.

[0062] It is to be understood, however, that other modifications and variations will be apparent to those skilled in the art in view of the above detailed description of the invention, and that such other modifications and variations are possible without departing from the spirit and scope of the invention.

Claims

1. 1. A laminate comprising a paper or paperboard substrate, the substrate in contact with a first adhesive layer, the first adhesive layer in contact with a second adhesive layer, the second adhesive layer in contact with a barrier film, the barrier film having a basis weight in the range of 15 to 80 gsm, the barrier film comprising at least 50% by weight of microfibrillated cellulose (MFC), the first adhesive being a terpolymer adhesive or a styrene / acrylate emulsion, optionally comprising a co-binder, the first adhesive having a glass transition temperature in the range between -20° and 60°C, and the second adhesive being a terpolymer adhesive or a styrene / acrylate emulsion, optionally comprising a co-binder, the second adhesive having a glass transition temperature above 30°C.

2. 10. The laminate of claim 1, wherein the barrier film comprises at least 70 wt%, more preferably at least 80 wt%, of MFC, based on the total dry weight of the barrier film.

3. 3. The laminate of claim 1, wherein the barrier film further comprises polyvinyl alcohol (PVOH).

4. 10. The laminate of claim 1, wherein the barrier film has a basis weight in the range of 15 to 40 gsm.

5. 5. A laminate according to any one of claims 1 to 4, wherein the barrier film has a Gurley Hill porosity value, determined in accordance with ISO 5636 / 6, of at least 2000 seconds / 100 ml before application of the adhesive.

6. 6. The laminate of any one of claims 1 to 5, wherein the barrier film has a PPS10 roughness of greater than 1.5 μm before application of the adhesive.

7. 7. The laminate of any one of claims 1 to 6, wherein the barrier film is subjected to a calender or supercalender before being used in the laminate.

8. 8. The laminate of claim 1, wherein the KIT value of the laminate is at least 11.

9. 9. A laminate according to any one of claims 1 to 8, wherein the substrate is an SBS board.

10. 1. A method for manufacturing a laminate, comprising: a) providing a paper or paperboard substrate; b) applying a first adhesive to a paper or paperboard substrate, the first adhesive being a terpolymer adhesive or a styrene / acrylate emulsion, optionally including a co-binder, said first adhesive having a glass transition temperature in the range between -20° and 60°C; c) providing a barrier film comprising at least 50% by weight of microfibrillated cellulose (MFC), wherein the barrier film is subjected to a calender and / or supercalender, and the basis weight of the barrier film is in the range of 15 to 80 gsm; d) applying a second adhesive to the barrier film, wherein the second adhesive is a terpolymer adhesive or a styrene / acrylate emulsion, optionally comprising a co-binder, and wherein said second adhesive has a glass transition temperature greater than 30°C; e) laminating the products of steps b) and d) together so that the first adhesive layer contacts the second adhesive layer. A method comprising:

11. The method of claim 10 , wherein the method is at least partially performed on a printing press.