SE546586C2 - Method for manufacturing a film comprising highly refined cellulose - Google Patents

Abstract

The invention discloses a method for manufacturing a barrier film comprising highly refined cellulose, the method comprising the steps of:a) providing a web comprising at least 50 % of highly refined cellulose having a Schopper-Riegler (SR) value in the range of 80 - 100, which web has a density in the range of 700-1500 kg/m3, and a wet tensile strength retention (MD) of less than 15%,b) applying an aqueous-based solution or dispersion comprising a polymer on the web, which aqueous based solution or dispersion has a solid content of between 5 - 50 wt%, andc) drying the web applied with the aqueous-based solution or dispersion to a solid content of at least 80 wt%, thereby forming the film.

Description

Technical field The present disclosure relates to a method for manufacturing a barrier film, e.g. for a paper or paperboard based packaging material, which barrier film is recyclable and has good barrier properties, in particular gas and water vapour barrier properties. ln addition, the present disclosure relates to a method for manufacturing a paper or paperboard based packaging material laminate, a barrier film, and a paper or paperboard based packaging material laminate comprising the barrier film.

Background Barrier films comprising cellulose fibers or polymers (cellulose-based barrier films), including films comprising high amounts of highly refined cellulose, nanocellulose or microfibrillated cellulose (MFC), are known in the art. Depending on how they are produced the cellulose-based barrier films may have particularly advantageous strength and/or barrier properties, whilst being biodegradable and recyclable (or repulpable). Such barrier films may be used in, for example, the manufacture of packaging materials and may be laminated or otherwise provided on the surface of paper or paperboard materials. Use of cellulose-based barrier films in packaging materials oftentimes facilitate repulping and recycling of the used packaging materials.

However, the barrier properties of cellulose-based barrier films may be sensitive to moisture or higher relative humidity ln particular, the gas barrier properties of such barrierfilms tend to deteriorate at high temperatures and high humidity, such as when exposed to tropical conditions or conditions allowing condensation.

One approach for improving the barrier properties towards oxygen and water vapour disclosed in the art involves applying the cellulose-based film with a coating layer providing additional barrier properties. To improve the repulpability and recyclability of the thereby produced film, it is oftentimes preferred that suchcoatings layers are applied as aqueous-based solutions or dispersions. However, difficulties may arise when applying aqueous-based coatings and surface treatments on cellulose-based substrates. When such water-based solutions or dispersions are applied onto a thin cellulose-based web or substrate, the web may break or problems with dimensional stability may occur causing e.g. cockling, wrinkles, shrinkage and/or curl of the web. This is due to water sorption and penetration into the hydrophilic substrate, affecting for example the hydrogen bonds between the fibrils, fibers, and the additives. Thus, web tension control may be difficult in the machine direction. Also, the web handling in the cross machine direction may be difficult.

One solution to this problem is to increase the solids of the applied solutions or dispersions, although this often leads to higher coat weight and higher viscosity of the solution. The application ofa solution/dispersion with a high viscosity might generate higher stresses on the substrate.

Another solution is to provide a cellulose-based film with high wet strength properties, e.g. by the addition of wet strength agents. This, on the other hand, makes the film difficult to repulp and recycle.

Another solution is to provide the cellulose-based film with hydrofobizing chemicals, such as internal sizing agents, which reduced the wettability and protects the fiber-fiber bonds. The disadvantage with this method, especially at high amount of internal sizing agents, is that the barrier properties of the film might be negatively affected and that the pulpering may be inefficient which might lead to increased reject at the recycling thereof.

Thus, there is still room for improvements of methods for producing cellulose- based barrier films, e.g. for paper or paperboard based packaging materials, which have good barrier properties such as water vapour barrier properties and that are repulplable and/or recyclable.

Description of the inventionlt is an object of the present invention to provide an improved method for manufacturing a barrier film, e.g. for a paper or paperboard based packaging material, which barrier film has good barrier properties such as oxygen and/or water vapour barrier properties, which method eliminates or alleviates at least some of the disadvantages of the prior art methods. lt is a further object of the present invention to provide a method for manufacturing a barrier film, e.g. for a paper or paperboard based packaging material, which barrier film has good barrier properties and is repulpable and/or recyclable.

The above-mentioned objects, as well as other objects as will be realized by the skilled person in the light of the present disclosure, are achieved by the various aspects of the present disclosure.

According to a first aspect illustrated herein, there is provided a method for manufacturing a film comprising highly refined cellulose, the method comprising the steps of: a) providing a web comprising at least 50 % of highly refined cellulose having a Schopper-Riegler (SR) value in the range of 80 - 100 as measured according to standard ISO 5267-1, the percentage calculated on the total dry weight of the web, which web has a density in the range of 700-1500 kg/m3 as measured according to standard ISO 534, preferably of 800-1350 kg/m3, most preferably of 900-1350 kg/m3 and a wet tensile strength retention value (MD) as measured according to standard ISO 3781 :2011 of less than 15%, preferably of less than 10%, and most preferably of less than 5%, b) applying an aqueous-based solution or dispersion comprising a polymer on the web, which aqueous based solution or dispersion has a solid content of between 5 - 50 wt%, preferably of between 7.5 - 35 wt% or more preferably of between 10 - 30 wt%, and c) drying the web applied with the aqueous-based solution or dispersion to a solid content of at least 80 wt%, thereby forming the film.The inventive method is based on the inventive realization that it is possible to coat a web comprising a high amount of highly refined cellulose with an aqueous- based solution or dispersion at quite low solid contents. This is accomplished by providing a web with a density of between 700-1500 kg/m3 and a wet tensile strength retention (MD) within the claimed interval. lt has been found that a film made according to the inventive method is easily repulpable and recyclable but does not involve problems with dimensional instability or web breakage at the processing (e.g. coating or impregnation) thereof. ln addition, the application of the aqueous-based solution or dispersion at such low solid contents provides an even coverage of the web and enables good barrier properties at low coat weights.

The term film as used herein refers generally to a thin continuous sheet formed material. Depending on the composition of the web, the film can also be considered as a thin paper or even as a membrane.

The term highly refined cellulose as used herein preferably refers to refined cellulose having a Schopper-Riegler (SR) value in the range of 80-100, preferably in the range of 80-98, more preferably in the range of 85-98, as determined by standard ISO 5267-1. Refining, or beating, of cellulose pulps refers to mechanical treatment and modification of the cellulose fibers in order to provide them with desired properties The highly refined cellulose can be produced from different raw materials, for example bleached or unbleached softwood pulp or hardwood pulp. ln some embodiments, the highly refined cellulose is produced from unbleached kraft pulp. The highly refined cellulose is preferably never dried cellulose. ln some embodiments, the highly refined cellulose is native highly refined cellulose. ln the context of the application, "native cellulose" refers to non-chemically modified cellulose. ln some embodiments, the highly refined cellulose has a water retention value (WRV) of at least 2.0 g/g, preferably at least 2.2 g/g.The web comprises at least 50 wt% of highly refined cellulose. ln embodiments, the web may oomprise at least 70 wt% of highly refined cellulose or at least 80 wt% of highly refined cellulose, such as between 70 - 99.9 wt% or 80 - 99.9 wt% of highly refined cellulose, all percentages calculated on the total dry weight of the web. The web may further oomprise cellulosic fibers from hardwood and/or softwood, such as between 49 - 0 wt%, or 30 - 0 % cellulosic fibers. Such cellulosic fibers preferably have a Schopper Riegler value between 15 - 45, as determined by standard ISO 5267-1, more preferably between 20 - 35. Most preferably, the cellulosic fibers are never-dried, bleached kraft pulp. The web may further comprise other ingredients or additives as outlined below. ln some embodiments, the highly refined cellulose is microfibrillated cellulose (MFC).

Microfibrillated cellulose (MFC) shall in the context of the patent application be understood to mean a cellulose particle, fiber or fibril having a width or diameter of from 20 nm to 1000 nm.

Various methods exist to make MFC, such as single or multiple pass refining, pre- hydrolysis followed by refining or high shear disintegration or liberation of fibrils. One or several pre-treatment steps is usually required in order to make MFC manufacturing both energy efficient and sustainable. The cellulose fibers of the pulp used when producing MFC may thus be native or pre-treated enzymatically or chemically, for example to reduce the quantity of hemicellulose or lignin.

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

There are different acronyms for MFC such as cellulose microfibrils, fibrillated cellulose, nanofibrillated cellulose, fibril aggregates, nanoscale cellulose fibrils, cellulose nanofibers, cellulose nanofibrils, cellulose microfibers, cellulose fibrils,microfibrillar cellulose, microfibril aggregates and cellulose microfibril aggregates. MFC can also be characterized by various physical or physical-chemical properties such as its large surface area or its ability to form a gel-like material at low solids (1-5 wt%) when dispersed in water.

The grammage (also referred to as basis weight) of the web, on total dry weight is typically less than 110 g/m2, preferably in the range of 15 - 100 g/m2 or in the range of 20 - 60 g/m2. Pinhole free films with basis weights in these ranges have been found have good oxygen barrier properties.

The web has a wet tensile strength retention (MD) of less than 10%. Preferably less than 5%. ln some embodiment the wet tensile strength retention (MD) may be less than 3%, preferably less than 2% or less than 1%, such as between 0.1 - 10%, or 0.1- 5%, 0.1 - 3%, 0.1 - 2 % or 0.1 -1%. The wet tensile strength retention is measured in accordance with ISO 3781 :201 1, the standard used for tensile strength testing is 1924-222008. The wet tensile strength retention may e.g. be regulated to be within the claimed interval by optimizing the amount of wet strength agents and dry strength agents in the web. ln embodiments, the web has a wet tensile strength (MD) of less than 0.3 kN/m, preferably less than 0.2 or less than 0.15, preferably between 0 - 0.29, or 0.1 - 0.29 or 0 - 0.2 or 0.1 - 0.2 or 0 - 0.15 or 0.1 - 0.15, as measured according to standard ISO 3781z comprises less than 5wt%, preferably less than 3 wt% or less than 2 wt%, such as 0 - 5wt%, or 0 - 3wt% or 0 - 2 wt%, by dry weight of wet strength agents. The term "wet strength agents" as used herein refers to wet strength chemicals, typically wet strength resins, that improve the tensile properties of a cellulose containing web in wet state by crosslinking the cellulose fibers with covalent bonds. Wet strength agents may include both permanent and temporary wet strength agents and may include e.g. urea resins, melamine resins, polyamidoamine-epichlorhydrine (PAAE) resins and dialdehyde- starch.ln embodiments, the web has a dry tensile strength (MD) as measured according to ISO 1942-2 of at least 3 kN/m, preferably at least 5 kN/m or at least 6 kN/m. comprises at least 5 kg/ton dry strength agents, more preferably at least 6 kg/ton or at least 10 kg/ton dry strength agents. The term "dry strength agents" as used herein refers to dry strength chemical that improve the tensile properties of a cellulose containing web in dry state, for example by forming hydrogen bonding. Dry strength agents improve the friction between fibers whereby the initial web wet strength is enhanced. Dry strength agents may include e.g. natural gums or polymers, such as cationic starch, carboxymethyl cellulose (CMC) and guar gum, and synthetic polymers, such as polyacrylamide (cationic, anionic and amphoteric), glyoxalated polyacrylamides (GPAMs), and polyvinylamines. ln embodiments, the web comprises natural gums and a surface active polymer preferably chosen from the group of proteins or hydrophob- modified polysaccharides.

Preferably, the step of providing the web comprises the step of providing a first web comprising said amount of highly refined cellulose, which first web is subjected to dewatering in at least one extended nip press, such as a shoe press or metal belt press. The wet pressing preferably takes place at a temperature (wet web temperature) of between 40-95 °C and more preferably of between 50-95 °C and most preferably of between 50-95 °C, and with a nip length of at least 10 mm, preferably at least 15 mm and most preferably at least 20 mm. The linear load is preferably 500-3000 N/m. Optionally, the wet press nip comprises at least one surface roll, belt or felt having a temperature 50-250 such as 60-180 °C. An example of a wet press configuration contains two shoe nips such as Symbelt or OptiPress Linearfrom Valmet or NipcoFlex from Voith GmbH. The extended nip dewatering can be integrated or part of a normal press section. Most preferable the dewatered web is further dried and then calendered e.g. with a machine or soft nip or extended nip calender, preferably at a temperature of above 60 such as 70- 250 °C (roll temp). A preferred configuration is a two soft nip station (for example soft-hard roll and hard-soft roll.). Preferably, prior to the extended nip dewatering and/or calendering, the web is subjected to steam at e.g. an amount of 1-5 gsm on at least one side, at a temperature above 60 °C. As an alternative to using a softcalender, a metal belt type of calender, such as a Valzone from Valmet, can be used, preferably with the following conditions: heated roll surface temperature of 50 - 250 °C, heated steel belt surface temperature: 50 - 250 °C, nip loads: 10 - 250 kN/m, preferably 20 - 150 kN/m. The web may be further moisturized with water before the metal belt calendaring, preferably at an amount of 0.5 - 5 g/m Without being bound to any theories, it is believed that the optimized shoe press and higher solid content after press section, enables improved strength required for in-line coating. Also, in-line calender with pre-steaming enables improved bonding in the sheet, and hence better dimensional stability. Especially, soft-nip calendering provides more homogenous density which hence reduces problem with dimensional stability during and after coating. ln addition, the web is easier to repulp/recycle.

The web may be manufactured at wide machines, preferably with a web width more than 3 m and even more than 3.5 m at high speeds, such as abovem/min such as between 500 - 1500 m/minute. ln embodiments, the aqueous-based solution or dispersion has an ÅAGWR water retention value (WRV) as measured according to standard TAPPI TM-701PM-01 of between 10 - 500 g/m2, preferably between 10 - 300, or 10 - 100 g/m2. The use of a solution or dispersion with such a WRV minimizes the amount of water that is released into the web whereby the dimension stability is further enhanced. ln this way, the web may be further processed and dried without problems with web breakage. ln embodiments, the aqueous based solution or dispersion has a Brookfield viscosity of 250 - 3500 mPa, preferably of 300 - 2500 mPas, as measured according to standard SCAN- P50:84, spindle number 6 at 100 rpm. A viscosity within the claimed interval facilitates an even application of the coating on the web.

Preferably, the aqueous-based solution or dispersion comprises a polymer selected from the group consisting of polyvinyl alcohol (PVOH), a modified polyvinyl alcohol, a polysaccharide or a modified polysaccharide, or combinationthereof. The polysaccharide or modified polysaccharide is preferably chosen from the group of starch, carboxymethyl cellulose (CMC) hemicellulose, chitosan and cellulose nanocrystals (CNC). The polymer is preferably selected to provide barrier properties, such as additional oxygen barrier properties or liquid or water vapor barrier properties. The polymer may further be cross-linked. The aqueous-based solution or dispersion may further comprise pigments, such as 0 - 15wt% pigments as calculated on the total solid content of the aqueous-based solution or dispersion. The aqueous-based solution or dispersion is preferably applied to the web in an amount to provide a coating layer with a grammage of between 1 - 10 g/m2, preferably 1 - 5 g/m2. The coated barrier film has preferably a moisture content of 2 - 8 wt%, such as between 3 - 7 wt%.

The step of forming the web may comprise the step of forming a multilayer web. Thus, the web may be formed of two or more web layers comprising highly cellulose, such as two, three or even four layers. The use of a multilayer web enables the manufacturer to design the web such that the initial wet web strength is improved so that coating of the web with a low solid content dispersion or solution is facilitated, while the wet strength is low enough to allow repulping. This can be achieved e.g. by forming one layer (first web layer) comprising a high amount of highly refined cellulose to provide barrier performance and another layer (second web layer) comprising a high amount of coarser fibers to provide dimensional stability. Such a first web layer can be made more hydrophilic and thinner to enable rewetting and repulping of the layer (even though it is denser) and such second web layer can be made to allow for faster liquid penetration, but simultaneously provide enough strength and dimensional stability needed for coating and converting. ln embodiments, the step of forming the multilayer web comprises - forming a first web layer comprising at least 50wt% of highly refined cellulose having a Schopper-Riegler (SR) value in the range of 80 - 100 as calculated on the total fiber content of said first web layer, and - forming a second web layer comprising at least 50wt% of highly refined cellulose having a Schopper-Riegler (SR) value in the range of 80 - 100 as calculated on the total fiber content of said second web layer - applying the second web layer onto said first web layer to form a multilayer web.

The forming of the web may e.g. be made in a paper-machine type of process. ln one embodiment, a multilayer web may be formed by applying a first furnish on a substrate (such as a wire) to form a first web layer whereupon a second furnish is applied on the first layer to form a second web layer. Preferably, the first web layer is at least partly dewatered before the application of the second furnish. Alternatively, a multilayer web may be formed by applying a first furnish on a first substrate (such as a first wire) and partly dewatering said first furnish on the substrate to form a first web layer, and applying a second furnish on a second substrate (such as a second wire) and partly dewatering said second furnish on the second substrate to form a second web layer, whereupon said second web layer is applied on said first web layer to form the multilayerweb. ln embodiments, the step of forming the multilayer web comprises - forming a first web layer comprising at least 50 wt% of highly refined cellulose having a Schopper Riegler (SR) value, as measured by standard ISO 5267-1, in the range of 80 - 100 as calculated on the total fiber content of said first web layer, and - forming a second web layer comprising cellulose fibers and less than 50 wt% of highly refined cellulose fibers having a Schopper Riegler (SR) value, as measured by standard ISO 5267-1, in the range of 80 - 100 as calculated on the total fiber content of said second web layer - applying said second web layer on said first web layer to form a multilayer web. ln embodiments, the method of forming the multilayer web comprises - forming a first web layer comprising between 80 - 100 wt% of highly refined cellulose having a Schopper Riegler (SR) value, as measured by standard ISO 5267-1, in the range of 80 - 100 as calculated on the total fiber content of said first web layer, and - forming a second web layer comprising between 65 - 95 wt% of cellulosic fibers and 5 - 35 wt% of highly refined cellulose having a Schopper Riegler(SR) value, as measured by standard ISO 5267-1, in the range of 80 - 100, as calculated on the total fiber content of said second web, - applying said second web layer on said first web layer to form a multilayer web.

The cellulosic fibers in the second layer preferably have a Schopper Riegler value between 15-45, as measured by standard ISO 5267-1, more preferably between 20-35. The cellulosic fibers are preferably fibers from either hardwood or softwood pulp. The cellulosic fibers can be a mixture of fibers from hardwood and softwood pulp. It may be preferred to use hardwood pulp since hardwood fibers has shown to improve the formation of the multilayer barrier film. The pulp can be pulp from virgin fiber, e.g. mechanical, semichemical, chemical, chemithermomechanical and/or thermomechanical pulps. lt may be preferred that the cellulosic fibers are made from kraft pulp, more preferably bleached kraft pulp.

Preferably, the aqueous-based solution or dispersion is applied on the first web layer, comprising a high amount of highly refined cellulose. ln this way, the barrier properties are optimized. ln embodiments, the second layer comprises an additive chosen from the group of natural gum, preferably guar gum and nano particles, preferably nano PCC. Preferably, such additive is added to the second layer in an amount of 1 - 15 kg/ton as calculated on the dry weight of said second layer. ln this way the fiber/fiber friction is improved, whereby the initial wet strength is further enhanced. lt has been shown that it is beneficial to add such natural gum or nano particles to the layer comprising the coarser cellulosic fibers (i.e. the second layer), since if such chemicals are added to the layer comprising the highly refined cellulose (the first layer), dewatering might be a challenge.

While the second web layer can comprise a small amount of wet strength agents, such as between 0 - 5 kg/ton or 0.1 - 5 kg/ton, it is preferred that the first web layer does not comprise any wet strength agents. As described above, if the layer comprising a high amount of highly refined cellulose is made more hydrophilic the rewetting and repulping of the film is facilitated.ln embodiments, the first layer has a grammage in the range of 8 - 30 g/m2, preferably in the range of 12 - 25 g/m2 and the second layer has a grammage in the range of 12 - 90 g/m2, preferably in the range of 15 - 35 g/m2. Preferably, the first layer has a lower grammage than the second layer.

The obtained film comprising the highly refined cellulose is easily repulpable and recyclable. Preferably, the obtained film has a reject rate according to PTS RH- 021/97 of less than 5%, preferably less than 3%.

The method enables the manufacturing of a film with high barrier properties. ln embodiments, the obtained barrier film comprising the highly refined cellulose has an oxygen transfer rate (OTR), measured according to the standard ASTM F1927- 98 at 50% relative humidity and 23 °C, of less than 100 cc/m2/24h/atm, preferably less than 50 cc/m2/24h/atm, more preferably less than 20 cc/m2/24h/atm and/or a KIT value of at least 10, preferably at least 12 as measured according to standard ISO 16532- ln embodiments, the obtained barrier film has a water vapor transfer rate (WVTR) measured according to the standard ASTM F1249-20 at 50% RH/23 °C of less than 40 g/m2/24h, preferably less than 20 g/m2/24h, and most preferably less than 15 g/m2/24h. The obtained film comprising the highly refined cellulose may preferably have an oxygen transfer rate (OTR), measured according to the standard ASTM F1927-98 at 85% relative humidity and 23 °C, of less than 150 cc/m2/24h/atm, preferably less than 100 cc/m2/24h/atm, most preferably less than 75 cc/m2/24h/atm. ln embodiments, the obtained film comprising the highly refined cellulose has a wet tensile strength (MD or CD) of greater than 0.1 kN/m as measured according to standard ISO 3781 :201 1. This facilitates the further converting of the obtained barrier film.

Moreover, the method enables the manufacturing of a film with high barrier properties that contains no or a low amount of synthetic polymers. lnembodiments, the obtained film contains less than 10 weight%, preferably less than 5 weight% of synthetic polymers as calculated on the total weight of the film.

Preferably, the obtained film does not comprise any fluorochemicals.

According to a .laspect illustrated herein, there is provided a method of manufacturing a paper or paperboard-based packaging material laminate, comprising the steps of: - performing the method according to the first aspect so as to form said barrier film, and - laminating said barrier film with a paper or paperboard- based material so as to form said paper or paperboard-based packaging material laminate.

The barrier film may be laminated to the paper or paperboard-based material using an adhesive tie layer in the form of an extrusion coating or in the form of a water-based solution or dispersion using liquid coating methods. ln embodiments, the aqueous-based solution or dispersion comprising a polymer applied on the web in the method of the first aspect may be used as the adhesive layer and/or to improve the adhesion to the paperboard. ' \ .åpaper or paperboard-based packaging material satsas.gsslšssaës--further polymer layers, such as extruded or laminated polyolefin layers applied on one or both side of the paper or paperboard based packaging material laminate. Such polymer layer/s may comprise any of the thermoplastic polymers commonly used in paper or paperboard based packaging materials in general or polymers used in liquid packaging board in particular. Examples includepolyethylene (PE), polyethylene terephthalate (PET), polypropylene (PP), polylactic acid (PLA), polyglycolic acid (PGA) and polyhydroxyalkanoates (PHA). Polyethylenes, especially low density polyethylene (LDPE) and high density polyethylene (HDPE), are the most common and versatile polymers used in liquid packaging board. The polyolefins can also be oriented, such as biaxially oriented or even vacuum coated or both.

Thus, a possible laminate structure is PoIyolefin/Paperboard/water soluble adhesive/barrier film/polyolefin/Polyolefin Thermoplastic polymers, are useful since they can be conveniently processed by extrusion coating techniques to form very thin and homogenous films with good liquid barrier properties. ln some embodiments, the polymer layer comprises polypropylene or polyethylene. ln preferred embodiments, the polymer layer comprises polyethylene, more preferably LDPE or HDPE.

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

Claims (28)

Claims

1. A method for manufacturing a barrier film comprising highly refined cellulose, the method a) providing a web comprising at least 50 % of highly refined cellulose having a Schopper-Riegler (SR) value in the range of 80 - 100 as measured according to standard ISO 5267-1, the percentage calculated on the total dry weight of the web, which web has a density in the range of 700-1500 kg/m3 as measured according to standard ISO 534, and a wet tensile strength retention (MD) as measured according to standard ISO 3781 :2011 of less than 15%, wherein the web comprises less than 5 wt% by dry weight of wet strength agents and at least 5 kg/ton dry strength agents, applying an aqueous-based solution or dispersion comprising a polymer on the web, which aqueous based solution or dispersion has a solid content of between 5 - 50 wt%, and drying the web applied with the aqueous-based solution or dispersion to a solid content of at least 80 wt%, thereby forming the film.

2. The method according to claim 1, wherein the highly refined cellulose has an SR value in the range of 80-98, preferably in the range of 85-

3. The method according to any one of the preceding claims, wherein the highly refined cellulose has a water retention value (WRV) of at least 2.0 g/g, preferably at least 2.2 g/g.

4. The method according to any one of the preceding claims, wherein the highly refined cellulose is microfibrillated cellulose (MFC).

5. The method according to any one of the preceding claims, wherein the grammage of the web is in the range of 15 -100g/m2, preferably in the range of 20 - 60 g/m

6. The method according to any one of the preceding claims, wherein the web has a wet tensile strength (MD) of less than 0.3 kN/m, as measured according to standard ISO

7. The method according to any one of the preceding claims, wherein the web has a dry tensile strength (MD) as measured according to ISO 1924-2 of at least 3 kN/m.

8. The method according to claim 7, wherein the web comprises a natural gum and a surface active polymer preferably chosen from the group of proteins or hydrophobe-modified polysaccharides.

9. The method according to any one of the preceding claims, wherein the step of providing the web comprises the steps of: - forming a first web comprising at least 50 % of highly refined cellulose having a Schopper-Riegler (SR) value in the range of 80 - 100 as measured according to standard ISO 5267-1, the percentage calculated on the total dry weight of the web, and - subjecting the first web to dewatering in at least one extended nip press.

10. The method according to claim 9, wherein the step of providing the web further comprises the steps of: - at least partly drying the first web, and - calendaring said at least partly dried first web.

11. The method according to any one of the preceding claims, wherein the aqueous-based solution or dispersion has an ÅAGWR water retention value (WRV) as measured according to standard TAPPI TM-701PM-01 of between 10 - 500 g/m

12. The method according to any one of the preceding claims, wherein the aqueous based solution or dispersion has a Brookfield viscosity of 250 - 3500 mPa as measured according to standard SCAN- P50:84, spindle number 6 atrpm.

13. The method according to any one of the preceding claims, wherein the aqueous-based solution or dispersion comprises a polymer selected from the group consisting of a polyvinyl alcohol, a modified polyvinyl alcohol, a polysaccharide or a modified polysaccharide, or combinations thereof.

14. The method according to any one of the preceding claims, wherein the step of providing the web comprises the step of forming a multilayer web.

15. The method according to claim 14, wherein the step of forming the multilayer web comprises - forming a first web layer comprising at least 50wt% of highly refined cellulose having a Schopper-Riegler (SR) value in the range of 80 - 100 as calculated on the total fiber content of said first web layer, and - forming a second web layer comprising at least 50wt% of highly refined cellulose having a Schopper-Riegler (SR) value in the range of 80 - 100 as calculated on the total fiber content of said second web layer - applying the second web layer onto said first web layer to form a multilayer web.

16. The method according to claim 15, wherein the step of forming the multilayer web comprises - forming a first web layer comprising at least 50 wt% of highly refined cellulose having a Schopper Riegler (SR) value in the range of 80 - 100 as calculated on the total fiber content of said first web layer, and - forming a second web layer comprising cellulose fibers and less than 50 wt% of highly refined cellulose fibers having a Schopper Riegler (SR) value in the range of 80 - 100 as calculated on the total fiber content of said second web layer - applying said second web layer on said first web layer to form a multilayer web.

17. The method according to claim 16, wherein the step of forming the multilayer web comprises- forming a first web layer comprising between 80 - 100 wt% of highly refined cellulose having a Schopper Riegler (SR) value in the range of 80 - 100 as calculated on the total fiber content of said first web layer, and - forming a second web layer comprising between 65 - 95 wt% of cellulosic fibers and 5 - 35 wt% of highly refined cellulose having a Schopper Riegler (SR) value in the range of 80 - 100, as calculated on the total fiber content of said second web, - applying said second web layer on said first web layer to form a multilayer web.

18. The method according to any one of claims 16 or 17, wherein the aqueous- based solution or dispersion is applied onto the first web layer.

19. The method according to any one of the claims 16 - 18, wherein the second web layer comprises an additive chosen from the group of natural gum, preferably guar gum, and nano particles, preferably nano PCC.

20. The method according to any one of the claims 16 - 19, wherein the first web layer does not comprise any wet strength agents.

21. The method according to any one of the claims 16 - 20, wherein the first web layer has a grammage in the range of 8 - 30 g/m2, preferably in the range of 12 - 25 g/m2 and the second web layer has a grammage in the range of 12 -g/m2, preferably in the range of 15 - 35 g/m

22. The method according to any one of the preceding claims, wherein the obtained film comprising the highly refined cellulose has an oxygen transfer rate (OTR), measured according to the standard ASTM F1927-98 at 50% relative humidity and 23 °C, of less than 100 cc/m2/24h/atm, preferably less than 50 cc/m2/24h/atm, more preferably less than 20 cc/m2/24h/atm and/or a KIT value of at least 10, preferably at least 12 as measured according to standard ISO 16532-

23. The method according to any one of the preceding claims, wherein the obtained film comprising the highly refined cellulose has a water vapor transfer rate (WVTR) measured according to the standard ASTM F1249-20 at 50% RH/23 °C of less than 40 g/m2/24h, preferably less than 20 g/m2/24h, and most preferably less than 15 g/m2/24h.

24. The method according to any one of the preceding claims, wherein the obtained film comprising the highly refined cellulose has an oxygen transfer rate (OTR), measured according to the standard ASTM F1927-98 at 85% relative humidity and 23 °C, of less than 150 cc/m2/24h/atm, preferably less than 100 cc/m2/24h/atm, most preferably less than 75 cc/m2/24h/atm.

25. The method according to any one of the preceding claims, wherein the obtained film comprising the highly refined cellulose has a wet tensile strength (MD or CD) of greater than 0.1 kN/m as measured according to standard ISO 3781 :201

26. The method according to any one of the preceding claims, wherein the obtained film comprising the highly refined cellulose has a reject rate according to PTS RH-021/97 of less than 5 %, preferably less than 3%.

27. The method according to any one of the preceding claims, wherein the obtained film comprising the highly refined cellulose contains less than 10 weight%, preferably less than 5 weight% of synthetic polymers as calculated on the total weight of the film.

28. A method of manufacturing a paper or paperboard based packaging material laminate, steps of: - performing the method according to any one of claims 1 - 27 so as to form said barrier film, and - laminating said barrier film with a paper or paperboard based material so as to form said paper or paperboard based packaging material laminate.