Method for producing a coating for application on biobased substrates

Abstract

The present invention relates to the preparation and application of a coating of 60 g / m2 or less comprising a polymer and an additive, produced by means of electrohydrodynamic, aerohydrodynamic processing or any combination thereof. The coating is recyclable and / or biodegradable and / or compostable and can be applied on any type of virgin biobased substrate or with one or more coatings. The coating of the invention serves to provide the biobased substrate on which it is applied with barrier properties against gases, vapours and liquids, in addition to allowing the assembly to be heat-sealed and / or heat-formed. This invention can be used to produce packaging materials, among other uses.

Description

[0001] DESCRIPTION

[0002] METHOD FOR OBTAINING A COATING FOR APPLICATION ON BIOBASED SUBSTRATES

[0003] SECTOR AND OBJECT OF THE INVENTION

[0004] The present invention lies in the development and application of a 60 g / m coating 2 or less, comprising a polymer and an additive, obtained by electrohydrodynamic processing, aerohydrodynamic processing, or any combination thereof. The coating is recyclable and / or biodegradable and / or compostable and can be applied to any type of virgin biobased substrate or with one or more coatings. The coating of the invention has the function of providing the biobased substrate to which it is applied with barrier properties to gases, vapors, and liquids, in addition to allowing heat sealing and / or thermoforming of the assembly. This invention can be applied, among other applications, to obtain packaging materials.

[0005] BACKGROUND OF THE INVENTION

[0006] Plastic, particularly petroleum-derived plastic, represents a major social problem due to its long decomposition and degradation times. Furthermore, the large production of packaging made from these materials in both the food and cosmetics sectors makes waste management problematic. Therefore, sustainable packaging alternatives are being studied using renewable raw materials that can degrade in the environment and / or be fully recycled, if possible, with an emphasis on promoting a circular economy.

[0007] A promising alternative, one on which the industry is focusing, is the use of bio-based materials, such as paper or cardboard, which come from cellulose fibers, which have a low cost due to their high availability. In addition, they are biodegradable, recyclable, and renewable. They differ mainly in their thickness, the latter being a superposition of layers of the former. [Adibi, A.; Trinh, BM; Mekonnen, TH Recent Progress in Sustainable Barrier Paper Coating for Food Packaging Applications. Prog Org Coat 2023, 181 , 107566.] Another advantage is that these substrates allow the creation of flexible, low-cost paper packaging with good printing characteristics and ease of functionalization, making them also safe for humans, which makes them competitive in the packaging sector.However, the bio-based and often very porous structure of these materials and their hydrophilicity means that they have certain disadvantages compared to petroleum-based plastic materials, such as their low gas barrier properties and their low resistance to water and grease. [Kunam, PK; Ramakanth, D.; Akhila, K.; Gaikwad, K.K. Bio-Based Materials for Barrier Coatings on Paper Packaging. Biomass Convers Biorefin 2022.].

[0008] Efforts are being made to overcome some of these drawbacks through polymeric coatings or inorganic particulate additives [Basak, S.; Dangate, MS; Samy, S. Oil- and Water-Resistant Paper Coatings: A Review. Prog Org Coat 2024, 186, 107938.] or through lamination with polymeric materials and aluminum, as is the case with the well-known Tetra Brik. [Guinamard, C. Millions of Tetra-Brik Packages. Industries Alimentaires et Agricoles 1990, 107, 399-401 .]

[0009] However, despite improvements in these areas, the production of materials from biobased substrates, for example, of cellulosic origin, with improved characteristics that are competitive with petroleum-derived materials, remains a challenge. One alternative is the application of biopolymer coatings using melt processing techniques. However, these biopolymers are difficult to apply to biobased substrates or degrade during application. In this regard, the present invention solves the problem by proposing optimized coatings obtained through techniques such as electrohydrodynamic and / or aerohydrodynamic processing, as they are applied at moderate or ambient temperatures and allow for extensive control over the deposition process to generate thin and stable biopolymer-based coatings.

[0010] DESCRIPTION OF THE INVENTION

[0011] The present invention proposes a methodology based on electro-hydrodynamic, aero-hydrodynamic processing, or a combination thereof, of biodegradable and / or compostable materials to generate a coating on bio-based substrates with properties 1) barrier to hydrophilic and lipophilic gases, vapors and liquids, 2) heat sealing and thermoforming, 3) recyclability and / or biodegradation and / or compostability, and with 4) weights equal to or less than 60 g / m 2 Method of obtaining the invention

[0012] In a first aspect, the present invention relates to a method for obtaining a multilayer material with or without previous coating or coatings, comprising a coating obtained by electro-hydrodynamic processing, aero-hydrodynamic processing or a combination of both with a weight equal to or less than 60 g / m 2with barrier properties to gases, vapors and liquids and with heat-sealing, thermoforming capacity, recyclable and / or biodegradable and / or compostable comprising the following steps: a) preparing a mixture of two components, a polymer, as component A, in a solvent at a concentration between 0.01 and 90% w / w with at least one additive, as component B different from component A, in a concentration between 0.01 and 80% w / w with respect to the polymer, preferably the additive is in a concentration between 0.01 and 70% w / w with respect to the polymer, more preferably between 1% and 50% w / w with respect to the polymer, b) subjecting the mixture prepared in step (a) to an electrohydrodynamic process, aero-hydrodynamic, or a combination thereof, and c) coating a biobased substrate with the material obtained in step (b) with at least one layer and subjecting it at least once to a curing process to reduce or eliminate porosity, through a thermal post-processing process,also called annealing or annealing, which consists of a heat treatment with or without pressure at a temperature below 800, e C and higher than room temperature (16-25 e C).

[0013] In a preferred embodiment, when the biobased substrate already has one or several coatings prior to step (c) which may be coatings different from the layers obtained by the steps of the method of the invention, then the coating of the invention obtained in step (c) is constituted by a single layer (A) that is applied over the previous coating(s) of the substrate.

[0014] In a preferred embodiment, when the biobased substrate does not have any coating prior to step (c), then the coating obtained in step (c) is made up of at least two layers, preferably two layers, a first inner layer (A') and a second outer layer (A). In the case of applying at least two or more layers of coating on the substrate, the curing process of step (c) is carried out first on the first layer and then again on the second layer and so on successively as many times as the number of layers, or in a single step after applying at least the two layers. In the case of applying two layers, the curing process of step (c) can be done first on layer (A') and then again after applying layer (A), or in a single step after applying the two layers (A' and A).

[0015] In a preferred embodiment, the coating of the present invention is carried out on both sides of the biobased substrate.

[0016] "Biobased substrates" refer to substrates that are manufactured, either wholly or partially, from renewable raw materials. Substrates can be commercially available and sometimes contain pre-coatings of various types, such as aluminized, latex, PVOH, or mineral, among others.

[0017] In a preferred embodiment, the biobased substrate is cellulose-based and more preferably the substrate is paper or cardboard.

[0018] The term “paper” refers in the present invention to a material consisting of a thin sheet made from cellulose pulp, prepared from a paste of ground plant fibers suspended in water and subsequently dried and hardened.

[0019] The term "cardboard" refers in the present invention to a material formed by several layers of virgin fiber paper or recycled paper, superimposed and bonded together by moisture compression and dried by evaporation. It is thicker, harder, and more resistant than paper.

[0020] The term “barrier properties” refers to the properties of a material that prevent the transmission of liquids, gases, and vapors through it.

[0021] The term "heat sealing" refers to the application of pressure and heat to a material to bond and seal it to itself or another material, for example, but not limited to, forming a container for closure and sealing. It serves to isolate products from external agents and oxidizers such as bacteria or air.

[0022] The term "thermoforming" refers to the process by which the material is heated and, as it softens, takes the shape of a mold by pressure and / or vacuum or the action of a countermold. In the present invention, the mixture prepared in step (a) may be a solution, an emulsion, or a suspension.

[0023] The term "solution" can be defined as a homogeneous mixture in which one or more solutes are dissolved in a solvent. As understood by those skilled in the art, homogenization techniques or methods known in the art can be used to prepare the solution, such as, but not limited to, magnetic stirring or the use of homogenizers.

[0024] The term "emulsion," as used here, refers to a dispersion of a liquid (dispersed phase) in the form of small particles within another liquid (continuous phase) with which it is generally immiscible. Emulsions can be direct, inverse, or multiple. Direct emulsions are those in which the dispersed phase is a lipophilic substance and the continuous phase is hydrophilic. These emulsions are often referred to as L / H or O / W emulsions. Inverse emulsions, on the other hand, are those in which the dispersed phase is a hydrophilic substance and the continuous phase is lipophilic. These emulsions are often referred to as H / L or W / O emulsions. Multiple emulsions are those in which the dispersed phase contains an inverse emulsion and the continuous phase is an aqueous liquid. These emulsions are known as H / L / H or W / O / W emulsions. So-called Pickering-type emulsions can also be formulated, which use particles to separate the phases and through any other type of emulsion technology.

[0025] The term “suspension” as used herein refers to a heterogeneous mixture consisting of small particles of an insoluble solid dispersed in a liquid medium.

[0026] In the present invention, the mixture prepared in step (a) comprises a polymer, preferably an environmentally biodegradable and / or compostable biopolymer. Examples of biodegradable biopolymers include, but are not limited to, polyhydroxyalkanoates (PHAs), such as polyhydroxybutyrate or polyhydroxybutyric acid (PHB), polyhydroxyvalerate (PHV), long chain length PHAs (Icl-PHA), medium chain length PHAs (mcl-PHA), and short chain length PHAs (scl-PHA), and all possible copolymers and hybrids thereof, such as polyhydroxybutyrate-valerate (PHBV), among others; poly-8-caprolactone (PCL) and all its copolymers, such as PEG-PCL and PCLA; polylactic acid (PLA) and all its copolymers, such as poly(lactic-co-glycolic acid) (PLGA); polyphosphazenes, polyorthoesters, polyesters obtained from natural precursors such as polymethylene terephthalate (PTT), polybutylene terephthalate (PBT), polybutylene succinate (PBS),and all possible copolymers thereof such as poly(butylene succinate-co-adipate) (PBSA), poly(butylene adipate-co-terephthalate) (PBAT), polyvinyl alcohols (PVOH) and their copolymers with ethylene (EVOH), polyacrylates (PAC), polyacrylic acid (PAA), water-soluble polyacrylonitriles (PAN), acrylic / methacrylic ester polymers, proteins such as zein, gluten and its derivatives, collagen, gelatin, casein, whey protein, soy proteins and their derivatives, silk fibroma, elastin, among others, polysaccharides such as carrageenans and derivatives, alginates, pullulan, dextran, gum arabic, chitosan and its derivatives, cellulose and its derivatives such as ethylcellulose, methylcellulose, cellulose acetate, cellulose acetate butyrate or hydroxypropyl methylcellulose, glycogen, starch, and polymers derived from these such as thermoplastic starch (TPS),lignin and derivatives such as sulfonated lignin (SL) and also non-polar substances such as lipids, for example and without limitation, waxes, resins, vegetable or mineral oils, acetoglycerides, fatty acids, among others and any combination thereof.

[0027] More preferably, the selected biopolymers will be polyhydroxyalkanoates and / or mixtures of different polyhydroxyalkanoates, or poly-8-caprolactone (PCL) and / or any of its copolymers, or any mixture of all of the foregoing. Even more preferably, copolymers based on polyhydroxybutyrate with contents of comonomers other than hydroxybutyrate of less than 10 mol% or PCL will be selected.

[0028] In a preferred embodiment, polymer grades with a molecular weight (Mw) of less than 2,000,000 Daltons will be selected. More preferably, grades with a molecular weight below 500,000 Daltons will be selected.

[0029] The mixture prepared in step (a) contains at least one additive, preferably biodegradable and / or environmentally compostable. Examples of biodegradable additives include, but are not limited to, proteins such as zein, gluten and its derivatives, collagen, gelatin, casein, whey protein, soy proteins and their derivatives, silk fibroin, elastin, polysaccharides such as carrageenans and derivatives, alginates, pullulan, dextran, gum arabic, chitosan and its derivatives, cellulose and its derivatives such as ethylcellulose, methylcellulose, cellulose acetate, cellulose acetate butyrate or hydroxypropylmethylcellulose, glycogen, starch, and polymers derived therefrom such as thermoplastic starch (TPS) and lipids such as waxes, resins, vegetable or mineral oils, acetoglycerides, fatty acids, lignin and derivatives such as sulfonated lignin (SL), among others, and any combination thereof.In a preferred embodiment, the selected additives will be organomodified, nanometric (1 nm-1 pm) in at least one of their three dimensions measured by scanning electron microscopy (SEM) and suitable for use in consumer products in the food, pharmaceutical and cosmetics sectors. More preferably, the additives will be selected from celluloses, lignins or any mixture of the foregoing. Even more preferably, the additive will be organomodified cellulose with groups, for example and not limited to, acetate, butyrate, methyl, ethyl, hydroxyethyl, hydroxypropyl, carboxyls, carboxymethyl, acetate phthalate, cyanoethylated, acetate propionate, sulfoxyethyl, derivatives and combinations thereof with substitution ratios between 0.01 and 99%. In an even more preferred embodiment, the additive will be cellulose acetate butyrate (CAB) in any degree of substitution.

[0030] In a preferred embodiment, additives with a molecular weight (Mn) of less than 500,000 Daltons will be selected. More preferably, grades with a molecular weight below 50,000 Daltons will be selected.

[0031] On the other hand, the mixture prepared in step (a) may comprise other additives, which include, but are not limited to, plasticizers, surfactants, reinforcements, process additives, antioxidants, colorants and / or nanoreinforcements, among others.

[0032] Examples of plasticizers, which are compounds that increase the “free volume” between polymer chains thereby increasing the flexibility of the material, could include compounds such as acetylated monoglycerides, citrates such as triethyl citrate (TEC), trioctyl citrate (TOC), trihexyl citrate (THC), acetyl tributyl citrate (ATBC), and polyols such as glycerol, deep eutectic point solvents (DES) and natural deep eutectic point solvents (NADES) or combinations thereof.

[0033] Examples of surfactants, which are amphiphilic compounds used to modify surface tension, could include sorbitan esters and polysorbates (Span Tween, TEGO), poly(vinylpyrrolidone), polyglycerol, polyricinoleate, poly(vinyl alcohol), cytotyltrimethylammonium bromide (CTAB), hexadecyltrimethylammonium bromide (HDTMAB), toctylphenesinpolyethoxyethanol (Triton), Lauryl Betaine, polyaxomers (Pluronic) and block copolymers. Examples of antioxidants include, but are not limited to, p-phenylenediamines, quinolines, quinones and derivatives, phenols, polyphenols and derivatives, thiols, henna, melatonin, carotenoids, flavonoids, uric acid, lipoic acid, glutathione or ascorbic acid among others.

[0034] Examples of colorants include, but are not limited to, oxides, sulfides, hydroxides, chromates and other metal-based complexes, such as cadmium, zinc, titanium, lead, iodine, aluminum, silver, gold and molybdenum, indigo, betanin, chlorophyll, stilbene, compounds with ethylenic, azo or heteroaromatic groups, triphenylmethane, phthalocyanines, carotenoids, quinacridones, dioxazines, isoindolines, perylenes, flavantrones, anthraquinones, triarylmethanes and derivatives thereof, among others.

[0035] Examples of reinforcements, but not limited to, are carbon black, titanium dioxide, magnetite, calcium carbonate or silica.

[0036] Examples of nanoreinforcements include carbon nanotubes, graphene, fullerenes, metals, metal oxides, nanosilica, nanoclays, among others, and any combination thereof.

[0037] The solvents used in step (a) are selected from water, alcohol (preferably ethanol, isopropanol or butanol) and organic solvents such as, but not limited to, toluene, acetone, ethyl acetate, methylene chloride, chloroform, dimethyl sulfoxide (DMSO), dimethylformamide (DMF), tetrahydrofuran (THE), trifluoroethanol (TFE), deep eutectic solvents (DES), natural deep eutectic solvents (NADES), ionic or inorganic solvents, and any combination of all of the above.

[0038] In a second stage, stage (b) of the method of the invention, comprises subjecting the mixture prepared in stage (a) to an electro-hydrodynamic, aero-hydrodynamic process, or a combination thereof, obtaining one or more polymeric coatings on the substrate, which may or may not be previously coated.

[0039] Electrohydrodynamic processes are based on the use of electrohydrodynamic techniques, which are based on the formation of micro, submicro, nano or ultrafine polymeric structures, from a polymeric solution to which an electric field is applied.

[0040] Examples of electro-hydrodynamic techniques include, but are not limited to, electrospinning, electrospinning assisted by pressurized gas or jacket electrospinning, coaxial electrospinning, electrohydrodynamic jet (E-jet) printing, electrohydrodynamic direct writing, melt electrospinning, electrostatic-solution blow spinning, electrospraying, coaxial electrospraying, electrospraying assisted by pressurized gas.Thus, in a preferred embodiment, alone or in combination with the rest of the preferred embodiments, the electro-hydrodynamic process comprises the use of an electro-hydrodynamic technique selected from the list consisting of electrospinning, electrospinning assisted by pressurized gas or jacket electrospinning, coaxial electrospinning, electrohydrodynamic jet (E-jet) printing, electrohydrodynamic direct writing, melt electrospinning, electrostatic-solution blow spinning, electrospraying, coaxial electrospraying, electrospraying assisted by pressurized gas.In a more preferred embodiment, alone or in combination with the other preferred embodiments, the electro-hydrodynamic process is electrospinning.

[0041] Aero-hydrodynamic processes are based on the use of aero-hydrodynamic techniques, which are based on the formation of micro, sub-micro, nano or ultra-fine polymeric structures, from a polymeric solution to which a flow of pressurized gas is applied through a jacket concentric to that of the solution.

[0042] Examples of aero-hydrodynamic techniques include, but are not limited to, centrifugal jet spinning, pull spinning, solution blow spinning, blown-centrifugal spinning, and solution blow spraying. Thus, in a preferred embodiment, alone or in combination with the rest of the preferred embodiments, the aero-hydrodynamic process comprises the use of an aero-hydrodynamic technique selected from the list consisting of: centrifugal jet spinning, pull spinning, solution blow spinning, blown-centrifugal spinning, and solution blow spraying, more preferably solution blow spinning.Thus, in this most preferred embodiment of step (b) of the method of obtaining the invention, it comprises subjecting the mixture prepared in step (a) to an electrospinning process.

[0043] The term electrospinning can be defined as a type of electrohydrodynamic technique based on the use of electrostatic forces, such as the voltage applied between an emitter and a collector, promoting the formation of microfibers or nanofibers from polymer mixtures or solutions. Different parameters can determine the electrospinning process and its effects, such as the voltage applied between the emitter and the collector, the solution flow rate, the distance between the emitter and the collector, the temperature at which the process is carried out, the relative humidity, as well as other parameters related to the polymer solution such as solids concentration, viscosity of the mixture or solution, surface tension, or conductivity.

[0044] In the present invention, the electrospinning process contemplates the use of a single emitter or a multi-emitter or multiple emitter, including, but not limited to, emitter(s) with or without needles (needle-less, also called free surface), and also including, but not limited to, emitter(s) with a monoaxial or coaxial structure.

[0045] In another preferred embodiment, alone or in combination with the other preferred embodiments, the electrospinning process is carried out using a multi-emitter system, with more than one emission point.

[0046] The present invention also contemplates, but is not limited to, fiber collection in a flat collector, a rotating collector, a disc-shaped collector, a collector ring, a roll-to-roll collector, codeposition, or layer-by-layer deposition. Codeposition means that the same or different materials can be deposited simultaneously as mixtures of fibers, using different injectors.

[0047] In a more preferred embodiment, the electrospinning process is preferably carried out on an industrial scale with multiple multi-emitters with or without needles, and with a roll-to-roll system for collection. This system could optionally be purged with nitrogen or any other inert gas.

[0048] To carry out the electrospinning process, injectors can be used as emitters. The injector can be of different types depending on its configuration. Injector types include, but are not limited to, single, needle, or capillary injectors, coaxial injectors, needleless injectors (needle-less or free surface), multi-needle injectors, or similar injectors, or those made of porous materials. In a preferred embodiment, alone or in combination with the other preferred embodiments, the electrospinning process comprises the use of multi-needle or capillary injectors, or multi-needleless injectors.

[0049] In a preferred embodiment of the method for obtaining the invention, alone or in combination with the other preferred embodiments, the electrospinning process comprises an emitter voltage of between 0.01 kV and 5000 kV (including the extreme values ​​of the range), and a collector voltage of between 0.01 kV and -5000 kV (including the extreme values ​​of the range). More preferably, the electrospinning process comprises an emitter voltage of between 0.1 and 100 kV (including the extreme values ​​of the range) and a collector voltage of between -0.1 and -100 kV (including the extreme values ​​of the range).

[0050] In another preferred embodiment, alone or in combination with the rest of the preferred embodiments, the electrospinning process is carried out at a temperature between 1 e C and 100 e C, preferably at a temperature between 10 e C and 60 e C (including extreme values ​​of the range).

[0051] In another preferred embodiment, alone or in combination with the other preferred embodiments, the electrospinning process is carried out at a relative humidity of between 1 and 99% (including the extreme values ​​of the range), preferably at a relative humidity of between 10 and 70% (including the extreme values ​​of the range).

[0052] In another more preferred embodiment, alone or in combination with the rest of the preferred embodiments, the electrospinning process is carried out at a temperature less than or equal to 50 e C and a relative humidity of less than or equal to 60%.

[0053] In another preferred embodiment, alone or in combination with the rest of the preferred embodiments, the electrospinning process is carried out with a flow rate of between 0.001 mL / min and 500 mL / min per emitter, and even more preferably, between 0.01 mL / min and 50 mL / min per emitter.

[0054] In another preferred embodiment, alone or in combination with the other preferred embodiments, when the injector is used in single-jet mode, the electrospinning process is carried out with an injector speed of between 0.01 and 1000 mm / s. In another preferred embodiment of the electrospinning process, alone or in combination with the other preferred embodiments, the emitter-collector distance is between 0.1 and 5000 cm (including the extreme values ​​of the range), more preferably, between 1 and 100 cm (including the values ​​at the extreme end of the range).

[0055] In another preferred embodiment of the electrospinning process, alone or in combination with the other preferred embodiments, the electrospinning process is carried out using a roll-to-roll collector for fiber collection. The roll-to-roll speed is preferably between 0.01 m / minute and 10,000 m / minute, and more preferably above 100 m / minute.

[0056] In another preferred embodiment, the percentage by mass of the material used for the coating must preferably be less than 80% with respect to the mass of the substrate prior to step (c), more preferably less than 50% and even more preferably less than 30%.

[0057] In a preferred embodiment, the weight of the material, used for the coating, obtained in step (b) and applied on the biobased substrate is equal to or less than 60 g / m 2 , in another more preferred embodiment is less than or equal to 45 g / m 2 and in another even more preferred it is equal to or less than 15 g / m 2 .

[0058] In the present invention, the fibers obtained in step (b) may be, but are not limited to, smooth or pearly. These terms refer to different types of morphology found in the generated fibrous structure. Thus, in a preferred embodiment, alone or in combination with the other preferred embodiments, the fibers obtained are smooth fibers. In another preferred embodiment, the fibers are pearly fibers.

[0059] The term "smooth fibers" refers to fibers that have a smooth surface with a fairly regular cross-section in diameter. The term "pearled fibers" refers to fibers that have spherical, oblong, or other irregular beads or pearls interspersed throughout the fiber cross-section.

[0060] Furthermore, the fibers may be arranged in a random or aligned orientation. In a random orientation, each fiber has a distinct orientation, while in an aligned orientation, all fibers have the same orientation. In an even more preferred embodiment, alone or in combination with the remaining preferred embodiments, the fiber size is between 0.01 and 100 pm (including the extreme values ​​of the range), and more preferably between 0.1 and 10 pm (including the extreme values ​​of the range). The size is the average diameter measured by scanning electron microscopy (SEM).

[0061] The material obtained in step (b) of the method for obtaining the invention is placed on the biobased substrate, previously coated or not, and both materials are subjected to a curing step. Therefore, the method for obtaining the invention comprises an additional step (c) of curing by means of heat treatment with or without pressure, which can be in a single step or in two or more and which leads to the coalescence of the fibers obtained in step (b) to reduce their high surface energy and porosity. During the process, the fibers adhere to the substrate, previously coated or not, and to each other, and at the same time they reduce in a controlled manner and / or completely eliminate the porosity to obtain the coating of the invention.

[0062] In a preferred embodiment of step (c) of the method for obtaining the invention, the curing step comprises subjecting the substrate, previously coated or not, and the electrospun fiber coating obtained in step (b) to a heat treatment process using any pressure rolling or calendering machinery, preferably wherein said process is carried out at a temperature below 800 ° C, obtaining a homogeneous coating without porosity. More preferably, step (c) is carried out at a temperature below 300 ° C, and even more preferably below 200 ° C. In another preferred embodiment, step (c) is carried out at a pressure between 0.001 and 300 MPa (both values ​​included). In another preferred embodiment, step (c) is carried out between 0.001 s and 60 min of contact.In another preferred embodiment, step (c) of the method for obtaining the invention is carried out by pressureless calendering at a speed of between 0.001 and 3000 meters per minute (including the extreme values ​​of the range).

[0063] The term "calendering" refers to a material preparation process, with or without pressure, involving the use of two or more rollers, at least one of which is at the required specific temperature. This process allows for the closure of pores between fibers, adhesion to the substrate, and filling of the substrate's porosity, generating a continuous material with no or reduced porosity and improved barrier properties. The term "curing," "annealing," or "annealing" of a material can be defined as a heat treatment at moderate temperatures and below the glass transition and / or melting and / or degradation temperature of the polymer or biopolymer, which allows for the production of a reduced-porosity or continuous material with improved physical properties from the fibers. This technique can be applied with or without pressure.

[0064] Thus, in a preferred embodiment, alone or in combination with the remaining preferred embodiments, the heat treatment includes, but is not limited to, continuous and discontinuous processes, such as simultaneous thermal and pressure processes, or thermal and then pressure processes in two steps. The heat treatment can be carried out, but is not limited to, contact or non-contact in a heated chamber, such as an infrared, resistance, ultraviolet (UV) radiation, microwave, radiofrequency, convection heating, conduction heating, induction heating chamber, continuous dryers on conveyor belts, vacuum dryers, through direct or indirect steam generators, and any combination thereof.

[0065] In an even more preferred embodiment, alone or in combination with the other preferred embodiments, the heat treatment is carried out in a calender at a speed between 0.01 and 100,000 rpm (including the extreme values ​​of the range), temperature below 200 ° C, pressure between 0.001 and 300 MPa (both values ​​included) and between 0.001 s and 60 min of contact time; or in a heated chamber with pressure below 200 ° C, at a pressure between 0.001 and 300 MPa (both values ​​included) and between 0.001 s and 60 min of contact time.

[0066] Biobased substrate with barrier properties

[0067] In a second aspect, the invention relates to a multilayer material with a monolayer or bilayer coating on bio-based substrates, preferably paper or cardboard, pre-coated or not, which offers improved barrier, heat-sealing and thermoforming properties, hereinafter "the material of the invention". "The material of the invention" is the material obtained by the method described above, which comprises a bio-based substrate with or without pre-coating and a monolayer or bilayer coating with at least one polymer and one additive, preferably both of which are recyclable and / or biodegradable and / or compostable, and which has:

[0068] - a coating weight equal to or less than 60 g / m 2

[0069] - a water vapour transmission rate between 0 and 150 g / m 2 d - an oxygen transmission rate between 0 and 50 cm 3 / m 2 d

[0070] - a water and oil absorption between 0 and 6 g / m 2 , and

[0071] - a grease resistance with a kit value greater than 6.

[0072] In a preferred embodiment when the biobased substrate already has one or several previous coatings, then the coating of the invention consists of a single layer (A).

[0073] In a preferred embodiment when the biobased substrate does not have any previous coating, then the coating of the invention is made up of at least two layers, preferably a first inner layer (A') and a second outer layer (A).

[0074] In a preferred embodiment, the material of the invention is coated on both sides of the biobased substrate.

[0075] In a preferred embodiment, the biobased substrate is cellulose-based and more preferably the substrate is paper or cardboard.

[0076] The terms “paper” and “cardboard” have been previously defined and explained in the previous aspect of the invention, and are also applicable to the present aspect of the invention.

[0077] Polymers, both biodegradable and non-biodegradable, may be comprised in the material of the invention.

[0078] Examples of biodegradable polymers include, but are not limited to, polyhydroxyalkanoates (PHAs), such as polyhydroxybutyrate or polyhydroxybutyric acid (PHB), polyhydroxyvalerate (PHV), long chain length PHAs (Icl-PHA), medium chain length PHAs (mcl-PHA), and short chain length PHAs (scl-PHA), and all possible copolymers and hybrids thereof such as polyhydroxybutyrate-valerate (PHBV), among others; poly-8-caprolactone (PCL) and all its copolymers such as PEG-PCL and PCLA; polylactic acid (PLA), all its copolymers such as poly(lactic-co-glycolic acid) (PLGA);polyphosphazenes, polyorthoesters, polyesters obtained from natural precursors such as polymethylene terephthalate (PTT), polybutylene terephthalate (PBT), polybutylene succinate (PBS), and all possible copolymers thereof such as poly(butylene succinate-co-adipate) (PBSA), poly(butylene adipate-co-terephthalate) (PBAT), polyvinyl alcohols (PVOH) and their copolymers with ethylene (EVOH), polyachlates (PAC), polyacrylic acid (PAA), water-soluble polyacrylic nitriles (PAN), lignin and derivatives such as sulfonated lignin (LS), acrylic / methacrylic ester polymers, pullulan, zein, celluloses and their derivatives such as ethylcellulose, methylcellulose, cellulose acetate, cellulose acetate butyrate or hydroxypropyl methylcellulose, glycogen, starch and polymers derived from it such as thermoplastic starch (TPS) among others.

[0079] More preferably, the selected polymers will be polyhydroxyalkanoates and / or mixtures of different polyhydroxyalkanoates, or poly-8-caprolactone (PCL) and / or any of its copolymers, or any mixture of all of the foregoing. Even more preferably, copolymers based on polyhydroxybutyrate with contents of comonomers other than hydroxybutyrate of less than 10 mol% or PCL will be selected.

[0080] In a preferred embodiment, polymer grades with a molecular weight (Mw) of less than 2,000,000 Daltons will be selected. More preferably, grades with a molecular weight below 500,000 Daltons will be selected.

[0081] The coating additive of the material of the invention is biodegradable and / or environmentally compostable. Examples of biodegradable additives include, but are not limited to, proteins such as zein, gluten and its derivatives, collagen, gelatin, casein, whey protein, soy proteins and their derivatives, silk fibroin, elastin, polysaccharides such as carrageenans and derivatives, alginates, pullulan, dextran, gum arabic, chitosan and its derivatives, cellulose and its derivatives such as ethylcellulose, methylcellulose, cellulose acetate, cellulose acetate butyrate or hydroxypropylmethylcellulose, glycogen, starch, and polymers derived therefrom such as thermoplastic starch (TPS) and lipids such as waxes, resins, vegetable or mineral oils, acetoglycerides, fatty acids, lignin and derivatives such as sulfonated lignin (SL), among others, and any combination thereof.

[0082] In a preferred embodiment, the selected additives will be organomodified, nanometric (1 nm-1 pm) in at least one of their three dimensions and suitable for use in consumer products in the food, pharmaceutical and cosmetics sectors. More preferably, the additives will comprise celluloses, lignins or any mixture of the foregoing. Even more preferably, the additive will be organomodified cellulose with groups, for example and not limited to, acetate, butyrate, methyl, ethyl, hydroxyethyl, hydroxypropyl, carboxyls, carboxymethyl, acetate phthalate, cyanoethylated, acetate propionate, sulfoxyethyl, derivatives and combinations thereof with substitution ratios between 0.01 and 99%. In an even more preferred embodiment, the additive will be cellulose acetate butyrate (CAB) in any degree of substitution. In a preferred embodiment, additives with a molecular weight in number (Mn) of less than 500,000 Daltons will be selected.More preferably, grades with molecular weight below 50,000 Daltons will be selected.

[0083] On the other hand, the material of the invention may also comprise additives, which include, but are not limited to, plasticizers, surfactants, reinforcements, process additives, antioxidants, colorants and / or nanoreinforcements, among others.

[0084] Examples of plasticizers, which are compounds that increase the “free volume” between polymer chains thereby increasing the flexibility of the material, could include compounds such as acetylated monoglycerides, citrates such as triethyl citrate (TEC), trioctyl citrate (TOC), trihexyl citrate (THC), acetyl tributyl citrate (ATBC), and polyols such as glycerol, deep eutectic point solvents (DES) and natural deep eutectic point solvents (NADES) or combinations thereof.

[0085] Examples of amphiphilic compounds used to modify surface tension could include sorbitan esters and polysorbates (Span Tween, TEGO), poly(vinylpyrrolidone), polyglycerol, polyricinoleate, poly(vinyl alcohol), cytolyltrimethylammonium bromide (CTAB), hexadecyltrimethylammonium bromide (HDTMAB), toctylphenesinpolyethoxyethanol (Triton), Lauryl Betaine, polyaxomers (Pluronic) and block copolymers.

[0086] Examples of antioxidants include, but are not limited to, p-phenylenediamines, quinolines, quinones and derivatives, phenols, polyphenols and derivatives, thiols, henna, melatonin, carotenoids, flavonoids, uric acid, lipoic acid, glutathione or ascorbic acid, among others.

[0087] Examples of colorants include, but are not limited to, oxides, sulfides, hydroxides, chromates and other metal-based complexes, such as cadmium, zinc, titanium, lead, iodine, aluminum, silver, gold and molybdenum, indigo, betanin, chlorophyll, stilbene, compounds with ethylenic, azo or heteroaromatic groups, triphenylmethane, phthalocyanines, carotenoids, quinacridones, dioxazines, isoindolines, perylenes, flavantrones, anthraquinones, triarylmethanes and derivatives thereof, among others.

[0088] Examples of reinforcements, but not limited to, include carbon black, titanium dioxide, magnetite, calcium carbonate, and silica, among others. Examples of nanoreinforcements include carbon nanotubes, graphene, fullerenes, metals, metal oxides, nanosilica, nanoclays, among others, as well as any combination thereof.

[0089] In a preferred embodiment of the material of the invention, alone or in combination with the rest of the preferred embodiments, the material of the invention comprises at least one additive from the family of celluloses and / or lignins, organomodified and nanometric in at least one of its three dimensions and suitable for use in consumer products in the food, pharmaceutical and cosmetics sectors. In a more preferred embodiment, the additive will be organomodified cellulose with groups, for example and not limited to, acetate, butyrate, methyl, ethyl, hydroxyethyl, hydroxypropyl, carboxyls, carboxymethyl, acetate phthalate, cyanoethylated, acetate propionate, sulfoxyethyl, derivatives and combinations thereof with substitution ratios between 0.01 and 99%. In an even more preferred embodiment, the additive will be cellulose acetate butyrate (CAB) in any degree of substitution.

[0090] In a preferred embodiment, alone or in combination with the other preferred embodiments, other additives are encapsulated or in coaxial format in the material of the invention.

[0091] The material of the invention can be obtained by electrohydrodynamics, aerohydrodynamics, or any combination of both. Thus, in a preferred embodiment, the material of the invention is obtained by electrohydrodynamics and / or aerohydrodynamics. In another preferred embodiment, alone or in combination with the other preferred embodiments, the material of the invention is obtained by the electrohydrodynamic technique of electrospinning.

[0092] The terms “electro-hydrodynamics”, “aero-hydrodynamics” and “electrospinning” have been previously explained in the previous aspect of the invention, and both they and their preferred embodiments are applicable to the present aspect of the invention.

[0093] Furthermore, the material of the invention can be provided in the form of a coating on the biobased substrate, whether previously coated or not, in the form of fibers, particles, or in the form of a film. In a preferred embodiment, alone or in combination with the other preferred embodiments, the coating material is provided in the form of a film. As already mentioned in the previous aspect of the invention, the fibers can be, but are not limited to, smooth or pearly. Thus, in a more preferred embodiment, the fibers are pearly fibers. In another more preferred embodiment, the fibers are smooth fibers.

[0094] In an even more preferred embodiment, alone or in combination with the other preferred embodiments, the fiber size is between 0.01 and 100 pm (including the extreme values ​​of the range), and more preferably between 0.1 and 10 pm (including the extreme values ​​of the range). The size is the average diameter as measured by scanning electron microscopy (SEM).

[0095] In another preferred embodiment, the percentage by mass of coating should preferably be less than 80% with respect to the mass of the substrate, more preferably less than 50% and even more preferably less than 30%.

[0096] In a preferred embodiment, the grammage of the coating applied on the biobased substrate is equal to or less than 60 g / m 2 , in another more preferred embodiment is less than or equal to 45 g / m 2 and in another even more preferred it is equal to or less than 15 g / m 2 .

[0097] In another preferred embodiment, the material of the invention has water barrier properties of interest, which can be characterized according to the standard method ASTM E96-9 [ASTM-E96 / E96M Standard Test Methods for Water Vapor Transmission of Materials, West Conshohocken. 2016, 14p.], according to ISO 2528:2017, or any other, using Payne permeability cups with relative humidity up to 100% (RH) or any other typical equipment that allows measuring water vapor permeability at different temperatures and relative humidities.

[0098] In another preferred embodiment, the water vapor transmission rate values ​​at 38 °C and 92%RH of the material of the invention are less than 150 g / m 2 d, more preferably less than 100 g / m 2 d, and even more preferably less than 15 g / m 2 d.

[0099] In another preferred embodiment, the material of the invention exhibits oxygen barrier properties, which can be characterized according to the ASTM D3985-05 standard method using an oxygen permeability analyzer with temperature and humidity control. In another preferred embodiment, the oxygen permeability values ​​of the material of the invention are less than 50 cm 3 / m 2 d measured at 23 °C and 50% relative humidity, more preferably less than 10 cm 3 / m 2 d measured at 23 °C and 50% relative humidity, and even more preferably less than 3 cm 3 / m 2 d measured at 23 °C and 50% relative humidity.

[0100] In another preferred embodiment, alone or in combination with the previous preferred embodiments, the material of the invention has resistance to water and oil, which can be characterized according to UNE-EN ISO 535:2023 standard where the absorption of water and oil of the sample was determined for 1800 s at 23 °C and 50% relative humidity.

[0101] In another preferred embodiment, the water and oil absorption values ​​of the material of the invention measured for 1800 s at 23 °C and 50% relative humidity are less than 6 g / m 2 , in another even more preferred embodiment less than 3 g / m 2 and even more preferably less than 1 g / m 2 .

[0102] In another preferred embodiment, alone or in combination with the previous preferred embodiments, the material of the invention has grease resistance, which can be characterized according to the TAPPI standard method T559 cm-12 [Wang, W.; Gu, F.; Deng, Z.; Zhu, Y.; Zhu, J.; Guo, T.; Song, J.; Xiao, H. Multilayer Surface Construction for Enhancing Barrier Properties of Cellulose-Based Packaging. Carbohydr Polym 2021 , 255, 117431.] or similar.

[0103] In another preferred embodiment, the grease resistance values ​​of the material of the invention measured by the TAPPI T559 cm-12 standard method are greater than a kit 6, and even more preferably greater than a kit 1 1.

[0104] On the other hand, the material of the invention is preferably a heat-sealable system, resistant to bending, with printing capacity, mechanical resistance and / or flexibility, among others.

[0105] The terms used to define the material of the invention have been previously explained in the previous aspect of the invention, and both they and their preferred embodiments may be applicable to the material of the invention. Another aspect of the invention relates to the use of the multilayer material of the invention as packaging in the food, pharmaceutical, and cosmetics sectors.

[0106] DESCRIPTION OF THE FIGURES

[0107] Fig. 1: A) Photograph of an uncoated paper substrate, B) Photograph of the paper substrate coated with a layer of 30 g / m2 PHBV 2%HV + 9% w / w CAB electrospun fibers 2 after heat treatment.

[0108] Fig. 2: A) Scanning electron microscopy (SEM) image in front view of an uncoated paper substrate, B) Scanning electron microscopy (SEM) image in front view of the electrospun fibers of the PHBV 2% HV + 9% w / w CAB coating, C) Scanning electron microscopy image of a cross-section of the paper substrate coated with the electrospun fibers after heat treatment with 30 g / m 2 on one side and 15 g / m 2 on the other hand.

[0109] Fig. 3: A) Photograph of an uncoated cardboard substrate, B) Photograph of the cardboard substrate coated with a layer of 45 g / m2 PHBV 2%HV + 9% w / w CAB electrospun fibers 2 after heat treatment.

[0110] Fig. 4: A) Scanning electron microscopy (SEM) image of a front view of an uncoated cardboard substrate, B) Scanning electron microscopy (SEM) image of a cross-section of the cardboard substrate coated with the electrospun fibers of PHBV 2%HV + 9% w / w CAB of 45 g / m 2 after heat treatment.

[0111] Fig. 5: A) Photograph of a pre-coated paper substrate, B) Photograph of the pre-coated paper substrate, coated with a layer of 30 g / m2 PHBV 2%HV + 9% w / w CAB electrospun fibers 2 after heat treatment.

[0112] Fig. 6: A) Scanning electron microscopy (SEM) image of a front view of a pre-coated paper, B) Scanning electron microscopy (SEM) image of a cross-section of the pre-coated paper, coated with a layer of 30 g / m PHBV 2%HV + 9% w / w CAB electrospun fibers. 2on both sides after heat treatment. Fig. 7: A) Photograph of an uncoated cardboard substrate, B) Photograph of the cardboard substrate coated with a layer of 30 g / m2 PHBV 2%HV + 9% w / w CAB electrospun fibers 2 after heat treatment.

[0113] Fig. 8: A) Scanning electron microscopy (SEM) image of the uncoated cardboard substrate in front view, B) Scanning electron microscopy (SEM) image of a cross-section of the cardboard substrate coated with a layer of 30g / m2 PHBV 2%HV + 9%w / w CAB electrospun fibers. 2 after heat treatment.

[0114] Fig. 9: A) Photograph of an uncoated aluminized paper substrate, B) Photograph of the aluminized paper substrate coated with a 15 g / m layer of PCL 12%w / w + 8%w / w CAB 2 after heat treatment.

[0115] Fig. 10: A) Front view scanning electron microscopy (SEM) image of the uncoated aluminized paper substrate, B) front view scanning electron microscopy (SEM) image of the electrospun fibers of the 12%w / w PCL + 33%w / w CAB coating, C) scanning electron microscopy (SEM) image of a cross section of the aluminized paper substrate coated with a layer of 10 g / m² PCL 12%w / w + 33%w / w CAB electrospun fibers 2 after heat treatment.

[0116] EXAMPLES

[0117] The invention will now be illustrated by examples provided by the inventors, which demonstrate the effectiveness of the method and product of the invention.

[0118] Example 1

[0119] A TFE solution of 2% HV PHBV and CAB (cellulose acetate butyrate, Mn: 30,000) was prepared with a total solids concentration of 1.1% by weight and a weight percentage of cellulose with respect to the polymer of 9%. It was magnetically stirred for 12 h at 40 °C.

[0120] The electrospinning process was carried out on a high-performance Fluidnatek LE-100 (Bioinicia SL) equipment with controlled environmental conditions using a multi-injector system with movement on the X axis and a rotating collector at 200 rpm. The process parameters were: injector voltage 20 kV, collector voltage -10 kV, needle-collector distance 27.5 cm, flow rate of 4 mL / h per needle (15-needle injector, 22G), injector speed of 50 mm / s. The process was carried out at a temperature of 33 e C and 20% relative humidity (RH). The coating obtained was 15 g / m 2 .

[0121] The material obtained in the electrospinning process was then deposited on both sides of a bleached commercial Kraft paper with a grammage of 70 g / m 2 and a heat treatment was applied using a hot platen press. The treatment was carried out in two steps: 1) at 165 °C for the top platen and 160 °C for the bottom platen for 25 s with 1500 psi of pressure. 2) A second layer of the material obtained in the electrospinning process was deposited only on the top side and the material was subjected to 165 °C for the top platen and 160 °C for the bottom platen for 30 s with 1500 psi of pressure. Finally, a paper with a coating of 30 g / m 2 on one side and 15 g / m 2 on the other hand, 45 g / m 2 in total.

[0122] Results

[0123] Figure 1 shows photographs of the uncoated paper (A) and coated paper (B), observing that the coated sample has a somewhat brighter appearance than the uncoated paper.

[0124] Figure 2 shows scanning electron microscopy (SEM) images taken with a Hitachi S-4800 microscope of the uncoated paper (A) and the electrospun PHBV + CAB fibers (B). It can be seen that the PHBV fibers are nonwoven and their average size is 1.9 ± 0.3 pm in diameter. Figure 2C shows a scanning electron microscopy image of a cross-section of the coated sample where it can be observed that the heat treatment allows the polymer mixture to adhere perfectly to the morphology of the paper.

[0125] Oxygen transmission rate (OTR) values ​​were determined. Oxygen barrier properties were characterized according to the ASTM D3985-05 standard method at 50% RH and 23 °C. Table 1 shows the results obtained. The coated paper sample showed a very good oxygen barrier compared to paper. In addition, grease resistance was evaluated for both the paper and coated paper samples using the TAPPI T559 cm-12 method. The test involves depositing a series of numbered solutions, which present different surface tension and viscosity, onto the sample surface. The solutions are numbered from 1 (least aggressive) to 12 (most aggressive). The highest numbered solution that does not leave a mark on the sample surface corresponds to its rating according to this Kit. The results are shown in Table 1 .While the uncoated paper has no resistance, the coated sample shows the greatest resistance. Furthermore, the sample was heat-sealed into a pouch, a test that could only be performed with the coated material, as it allows adhesion between layers with the application of pressure and heat.

[0126] Table 1. Oxygen transmission rate (OTR) and grease resistance values ​​of coated paper and heat sealing test success.

[0127] Sample ÓTR (cm 3 / m 2 d) Heat-sealed KIT value

[0128] Bleached Kraft paper 70 g / m 2 >4000 Ó Ño

[0129] Coated paper <1 12 Yes

[0130] Example 2

[0131] A TFE solution of 2% HV PHBV and CAB (cellulose acetate butyrate) was prepared with a total solids concentration of 1.1% by weight and a weight percentage of cellulose relative to the polymer of 9%. It was magnetically stirred for 12 h at 40 °C.

[0132] The electrospinning process was carried out on a high-performance Fluidnatek LE-100 (Bioinicia SL) equipment with controlled environmental conditions using a multi-injector system with movement on the X axis and a rotating collector at 200 rpm. The process parameters were: injector voltage 20 kV, collector voltage -10 kV, needle-collector distance 27.5 cm, flow rate of 4 mL / h per needle (15-needle injector, 22G), injector speed of 50 mm / s. The process was carried out at a temperature of 33 °C and 20% relative humidity (RH). The coatings obtained were 15 g / m 2 and 30 g / m 2 .

[0133] The material obtained in the electrospinning process was then deposited on cardboard with a weight of 170 g / m 2 and heat treated using a Labtech hot plate press (model LP20-B). The treatment was carried out in two steps, adding a total of 45 g / m 2 coating: 1 ) to 145 e C the top plate and 150 °C the bottom plate for 25 s with 500 psi of pressure adding a layer of 15 g / m 2 , 2) at 150 °C the top plate and 155 °C the bottom plate for 30 s with 1500 psi of pressure adding a layer of 30 g / m 2 on the previously deposited one. Results

[0134] Figure 3 shows photographs of uncoated paper (A) and coated paper (B), observing that the coated sample has more shine and the biobased substrate can still be seen, that is, it is not an opaque coating.

[0135] Figure 4 shows scanning electron microscopy (SEM) images taken with a Hitachi S-4800 microscope of the uncoated paper (A) and a cross-sectional image of the coated sample (B). It can be seen that the heat treatment allows the coating fibers, on the one hand, to coalesce into a continuous, pore-free layer, and on the other, to adhere perfectly to the surface of the board, replicating its morphology.

[0136] The water vapor transmission rate (WVTR) and oxygen transmission rate (OTR) values ​​were determined. The water vapor transmission rate (WVTR) was determined by an ASTM E96-9 test using Payne permeation cups with a relative humidity of 92% RH on one side of the material and 0% RH on the other. The Payne cups were stored at 38 °C and their weight was measured periodically until a constant weight was reached. Aluminum foils were used as controls to estimate water vapor loss through the seal. Oxygen barrier properties were characterized according to the ASTM D3985-05 standard method using an Oxygen Permeation Analyzer M8001 from Systech Illinois (Thame, UK) at 50% RH and 23 q C. Table 2 shows the results obtained. The coated cardboard sample showed a very good barrier to water vapor and oxygen compared to the uncoated cardboard.

[0137] Table 2. Water vapor transmission rate (WVTR) and oxygen transmission rate (OTR) values ​​of the coated cardboard.

[0138] WVTR sample (g / m 2 d) OTR (cm 3 / m 2 d)

[0139] Cardboard 170 g / m 2 657 ± 8 >1000

[0140] Coated cardboard 64 ± 4 9.6 ± 0.1

[0141] Grease resistance was evaluated for both the paperboard and coated paperboard samples using TAPPI method T559 cm-12. The test involves depositing a series of numbered solutions, each with different surface tensions and viscosities, onto the sample surface. The solutions are numbered from 1 (least aggressive) to 12 (most aggressive). The highest-numbered solution that leaves no mark on the sample surface corresponds to its rating according to this kit. The results are shown in Table 3. While the uncoated paperboard had no resistance, the coated sample showed the greatest resistance.

[0142] Table 3. KIT values ​​of the grease resistance test for cardboard and coated cardboard.

[0143] Sample Value KIT

[0144] Cardboard i 70 g / m 2 EITHER

[0145] Coated cardboard 12

[0146] Example 3

[0147] A TFE solution of 2% HV PHBV and CAB (cellulose acetate butyrate) was prepared with a total solids concentration of 1.1% by weight and a weight percentage of cellulose relative to the polymer of 9%. It was magnetically stirred for 12 h at 40 °C.

[0148] The electrospinning process was carried out on a high-performance Fluidnatek LE-100 (Bioinicia SL) equipment with controlled environmental conditions using a multi-injector system with movement on the X axis and a rotating collector at 200 rpm. The process parameters were: injector voltage 20 kV, collector voltage -10 kV, needle-collector distance 27.5 cm, flow rate of 4 mL / h per needle (15-needle injector, 22G), injector speed of 50 mm / s. The process was carried out at a temperature of 33 e C and 20% relative humidity (RH). The coating obtained was 30 g / m 2 .

[0149] The material obtained in the electrospinning process was then deposited on a commercial Kraft paper coated with a water barrier layer and with a weight of 97 g / m 2 and heat treated using a Labtech hot platen press (model LP20-B). The treatment was carried out in one step: 1) at 145 °C for the top platen and 150 °C for the bottom platen for 30 s with 1500 psi of pressure, adding 30 g / m 2 coating on each side of the paper.

[0150] Results

[0151] Figure 5 shows photographs of uncoated water-barrier paper (A) and coated water-barrier paper (B), showing that the coated sample has a higher gloss. Figure 6 shows scanning electron microscopy (SEM) images taken with a Hitachi S-4800 microscope of the uncoated water-barrier paper (A) and a cross-section of the coated sample (B). It can be seen that the heat treatment allows the coating fibers to coalesce, forming a continuous, pore-free layer, and to adhere perfectly to the paper surface, copying its morphology.

[0152] The water vapor transmission rate (WVTR) and oxygen transmission rate (OTR) values ​​were determined. The water vapor transmission rate (WVTR) was determined by an ASTM E96-9 test using Payne permeation cups with a relative humidity of 92% RH on one side of the material and 0% RH on the other. The Payne cups were stored at 38 °C and their weight was measured periodically until a constant weight was reached. Aluminum foils were used as controls to estimate water vapor loss through the seal. Oxygen barrier properties were characterized according to the ASTM D3985-05 standard method using an Oxygen Permeation Analyzer M8001 from Systech Illinois (Thame, UK) at 50% RH and 23 qC. Table 4 shows the results obtained. The coated treated paper sample showed a very good oxygen barrier compared to the uncoated treated paper and an improvement in the water vapor barrier. In addition, the sample was heat-sealed into a pouch, a test that could only be performed with the coated material since the coating allows adhesion between layers with the application of heat.

[0153] Table 4. Water vapor transmission rate (WVTR), oxygen transmission rate (OTR) values ​​and heat sealing study of coated treated paper.

[0154] Heat Sealing Sample

[0155] Kraft paper with coating

[0156] 76 ± 2 > 4000 NO water barrier 97 g / m 2

[0157] Coated paper 29 ± 2 46 ± 2 SI

[0158] Grease resistance was evaluated for both the paper sample and the coated paper using TAPPI Method T559 cm-12. The test involves depositing a series of numbered solutions, each exhibiting different surface tensions and viscosities, onto the sample surface. The solutions are numbered from 1 (least aggressive) to 12 (most aggressive). The highest-numbered solution that leaves no mark on the sample surface corresponds to its rating according to this Kit. The results are shown in Table 5. Both the uncoated and coated treated paper showed the highest resistance.

[0159] The water and oil absorption of the paper sample and the coated paper were determined using the Cobb method according to UNE-EN ISO 535:2023. The absorption value indicated by the Cobb index was calculated by measuring the amount of water or oil absorbed by a 100 cm2 area of ​​paper. 2for 1800 s at 23 °C and 50% relative humidity. The Cobb value or absorption value is represented by the quantity of water or oil absorbed by the paper per unit area (g / m 2 ). It can be seen that after applying the coating the hydrophilic and lipophilic absorption decreases.

[0160] Table 5. KIT values ​​of the grease resistance test and water and oil absorption values ​​for treated paper and coated treated paper.

[0161] Sample Value Kit Cobb water 1800 (g / m 2 ) Cobb oil 1800 (g / m 2 )

[0162] Kraft paper with 4.5 layer 1 >5 water barrier 97 g / m 2

[0163] Coated paper 12 0.4 0.3

[0164] Example 4

[0165] A TFE solution of 2% HV PHBV and CAB (cellulose acetate butyrate) was prepared with a total solids concentration of 11% by weight and a weight percentage of cellulose relative to the polymer of 9%. It was magnetically stirred for 12 h at 40 °C.

[0166] The electrospinning process was carried out on a high-performance Fluidnatek LE-100 (Bioinicia SL) equipment with controlled environmental conditions using a multi-injector system with movement on the X axis and a rotating collector at 200 rpm. The process parameters were: injector voltage 20 kV, collector voltage -10 kV, needle-collector distance 27.5 cm, flow rate of 4 mL / h per needle (15-needle injector, 22G), injector speed of 50 mm / s. The process was carried out at a temperature of 33 °C and 20% relative humidity (RH). The coatings obtained were 15 g / m 2 and 30 g / m 2 .

[0167] The material obtained in the electrospinning process was then deposited on cardboard with a weight of 220 g / m 2 and heat treatment was applied using a Labtech hot platen press (model LP20-B). The treatment was carried out in two steps: 1) at 145 °C for the top platen and 150 °C for the bottom platen for 25 s with 500 psi of pressure, adding a 15 g / m layer 2 , 2) at 150 °C the top plate and 155 °C the bottom plate for 30 s with 1500 psi of pressure adding a layer of 15 or 30 g / m 2 on the one previously deposited.

[0168] Results

[0169] Figure 7 shows photographs of uncoated paper (A) and coated paper (B), observing that the coated sample has a higher gloss.

[0170] Figure 8 shows scanning electron microscopy (SEM) images taken with a Hitachi S-4800 microscope of the uncoated paper (A) and a cross-section of the coated sample (B). It can be seen that the heat treatment allows the coating fibers to coalesce, forming an impenetrable, pore-free layer, and to adhere perfectly to the surface of the cardboard, replicating its morphology.

[0171] The water vapor transmission rate (WVTR) and oxygen transmission rate (OTR) values ​​were determined. The water vapor transmission rate (WVTR) value was determined by an ASTM E96-9 test according to ISO 2528:2017, using Payne permeability cups at 90% relative humidity (RH) and 38 °C. The cups contain a desiccant (silica gel) on the unprotected side and are sealed with molten wax. They were stored in a controlled atmosphere and their weight was measured periodically (every 3 hours) until a constant weight was reached. The oxygen barrier properties were characterized according to the ASTM D3985-05 standard method using an Oxygen Permeation Analyzer M8001 from Systech Illinois (Thame, United Kingdom) at 50% RH and 23 °C. Table 6 shows the results obtained. The coated cardboard sample showed a very good oxygen barrier compared to the uncoated cardboard.In addition, the sample was heat-sealed to create a pouch, a test that could only be performed with the coated material since the coating allows adhesion between layers with the application of heat.

[0172] Table 6. Water vapor transmission rate (WVTR) and oxygen transmission rate (OTR) values ​​of coated paper and heat sealing test success.

[0173] WVTR sample (g / m 2 d) OTR (cm 3 / m 2 d) Heat sealing

[0174] Cardboard 220 g / m 2 >600 >4000 No

[0175] 45 g / m coated cardboard 2 100 ± 14 0 ± 0 Yes

[0176] Cardboard coated with 30 g / m 2140 ± 10 8 ± 4 Yes Grease resistance was evaluated for both the paper and coated paper samples using TAPPI method T559 cm-12. The test involves depositing a series of numbered solutions, which present different surface tension and viscosity, onto the sample surface. The solutions are numbered from 1 (least aggressive) to 12 (most aggressive). The solution with the highest number that does not leave a mark on the sample surface corresponds to its rating according to this Kit. The results are shown in Table 7. While the uncoated board has no resistance, the coated sample shows the maximum resistance.

[0177] The water and oil absorption of the cardboard sample and the coated cardboard were determined using the Cobb method according to UNE-EN ISO 535:2023. The absorption value indicated by the Cobb index was calculated by measuring the amount of water or oil absorbed by a 100 cm2 area of ​​cardboard. 2 for 1800 s at 23 °C and 50% relative humidity. The Cobb value or absorption value is represented by the quantity of water or oil absorbed by the cardboard per unit area (g / m 2 ).

[0178] Table 7. KIT values ​​of the grease resistance test and water and oil absorption values ​​for cardboard and coated cardboard.

[0179] Sample Value Kit Cobb water 1800 (g / m 2 ) Cobb oil 1800 (g / m 2 )

[0180] Cardboard 220 g / m 2 0 N / AN / A

[0181] Cardboard coated with 45 12 1 ,5 ± 0,5 1 ,7 ± 0,4 g / m 2

[0182] Cardboard coated with 30

[0183] 12 1 .0 ± 0.5 4.7 ± 0.2 g / m 2

[0184] Example 5

[0185] A PCL solution with a concentration of 12% by weight in chloroform / methanol with a ratio of 9:1 and a weight percentage of CAB with respect to the polymer of 8% or 33% was prepared and magnetically stirred for 48 h at 37 °C.

[0186] The electrospinning process was carried out on a high-performance Fluidnatek LE-100 (Bioinicia SL) equipment with controlled environmental conditions using a 15-needle multi-injector system, with movement on the X axis and a rotating collector at 200 rpm. The process parameters were: injector voltage 14 kV, collector voltage -12 kV, needle-collector distance 20 cm, flow rate of 4 mL / h per needle, injector speed of 50 mm / s. The process was carried out at a temperature of 30 °C and 25% relative humidity (RH). The obtained coating was 15 g / m 2 for 8% w / w of CAB.

[0187] To obtain 10 g / m 2 with 33% w / w CAB, a 15-needle multi-injector system was used, moving along the X axis and with a rotating collector at 200 rpm. The process parameters were: injector voltage 20 kV, collector voltage -15 kV, needle-collector distance 25 cm, flow rate 2 mL / h per needle, injector speed 50 mm / s. The process was carried out at a temperature of 30 °C and 25% relative humidity (RH).

[0188] The material obtained in the electrospinning process was then deposited on a barrier Kraft paper bearing an aluminized coating with a weight of 69 g / m 2 and a heat treatment was applied in a single step on a calender at 70 °C, without pressure and at a speed of 0.45 m / min.

[0189] Results

[0190] Figure 9 shows photographs of uncoated barrier paper (A) and coated barrier paper (B), observing that the coated sample has a matte and whitish tone.

[0191] Figure 10 shows scanning electron microscopy (SEM) images taken with a Hitachi S-4800 microscope of the uncoated barrier paper (A) and the electrospun PCL + 33% w / w CAB fibers (B) with an average size of 2.8 ± 0.4 pm. Figure 10C shows a scanning electron microscopy image of a cross-section of the coated sample where it can be observed that the heat treatment allows the coating fibers, on the one hand, to coalesce, forming a layer that will protect the barrier substrate, and on the other hand, to adhere to the surface of the sample, copying its morphology.

[0192] The water vapor transmission rate (WVTR) and oxygen transmission rate (OTR) values ​​were determined. The water vapor transmission rate (WVTR) value was determined by an ASTM E96-9 test according to ISO 2528:2017, using Payne permeation cups at 90% relative humidity (RH) and 38 °C. The cups contain a desiccant (silica gel) on the unprotected side and are sealed with molten wax. They were stored in a controlled atmosphere and their weight was measured periodically (every 3 hours) until a constant weight was reached. The oxygen barrier properties were characterized according to the ASTM D3985-05 standard method using an Oxygen Permeation Analyzer M8001 from Systech Illinois (Thame, United Kingdom) at 50% RH and 23 °C. Table 8 shows the results obtained. The coated aluminized paper sample showed an improved barrier to water vapor and oxygen compared to the uncoated aluminized paper.In addition, the sample was heat-sealed to create a pouch, a test that could only be performed with the coated material since it allows adhesion between layers with the application of heat.

[0193] Table 8. Water vapor transmission rate (WVTR) and oxygen transmission rate (OTR) values ​​of coated aluminized paper and heat sealing test success.

[0194] WVTR sample (g / m 2 d) OTR (g / m 2 d) Heat sealing

[0195] Aluminized paper 69 g / m 2 11 ± 12 2.8 ± 0.1 No

[0196] Coated aluminized paper

[0197] 5 ± 3 0 ± 0 Yes with PCL + 8% w / w CAB

[0198] Coated aluminized paper

[0199] 4 ± 3 0 ± 0 Yes with PCL + 33% w / w CAB

[0200] Grease resistance was evaluated for both the paper and coated paper samples using TAPPI Method T559 cm-12. The test involves depositing a series of numbered solutions, each with different surface tensions and viscosities, onto the sample surface. The solutions are numbered from 1 (least aggressive) to 12 (most aggressive). The highest-numbered solution that leaves no mark on the sample surface corresponds to its rating according to this Kit. The results are shown in Table 9. Both the uncoated and coated paper exhibited resistance up to Kit 12.

[0201] The water and oil absorption of the paper sample and the coated paper were determined using the Cobb method according to UNE-EN ISO 535:2023. The absorption value indicated by the Cobb index was calculated by measuring the amount of water or oil absorbed by a 100 cm2 area of ​​paper. 2for 1800 s at 23 °C and 50% relative humidity. The Cobb value or absorption value is represented by the quantity of water or oil absorbed by the paper per unit area (g / m 2 ). Table 9. KIT values ​​of the grease resistance test and water and oil absorption values ​​for aluminized paper and coated aluminized paper.

[0202] Sample Value Kit Cobb water 1800 (g / m 2 ) Cobb oil 1800 (g / m 2 )

[0203] Aluminized paper 69 g / m 2 12 1 .5 ± 0.5 1 .2 ± 0.3

[0204] Coated aluminized paper 12 0.55 ± 0.07 2.7 ± 0.6 with PCL + 8% w / w CAB

[0205] Coated aluminized paper

[0206] 12 0.5 ± 0.2 2.8 ± 0.3 with PCL + 33%w / w CAB

Claims

CLAIMS 1.- Method for obtaining a multilayer material comprising a coated biobased substrate and comprising the following steps: a) preparing a mixture of two components, a polymer as component A in a solvent at a concentration of between 0.01 and 90% w / w with at least one additive as component B, different from component A and in a concentration of between 0.01 and 80% w / w with respect to the polymer, b) subjecting the mixture prepared in step (a) to an electrohydrodynamic process, aero-hydrodynamic, or a combination of both, and c) coating a biobased substrate with the coating material obtained in step (b) with at least one layer and subjecting it at least once to a curing process to reduce or eliminate porosity, by means of a heat treatment with or without pressure at a temperature lower than 800 e C. 2.- Method according to claim 1, wherein the substrate has at least one coating prior to step (c), and the coating obtained in step (c) consists of a single layer (A) that is applied over the previous coating(s) of the substrate. 3.- Method according to claim 1, wherein the substrate has no coating prior to step (c) and is coated in step (c) with two layers, a first inner layer (A') and a second outer layer (A). 4.- Method according to any of claims 1 to 3, wherein the coating of step (c) is carried out on both sides of the substrate. 5.- Method according to any of claims 1 to 4, wherein the substrate is paper or cardboard. 6.- Method according to any of claims 1 to 5, wherein the mixture prepared in step (a) is a solution, emulsion or suspension. 7.- Method according to any of claims 1 to 6, wherein the polymer of step (a) is selected from: polyhydroxyalkanoates (PHA), selected from polyhydroxybutyrate, polyhydroxybutyric acid (PHB), polyhydroxyvalerate (PHV), polyhydroxybutyrate-valerate (PHBV), Long chain length PHA (Icl-PHA), medium chain length PHA (mcl-PHA), short chain length PHA (scl-PHA), and any of their copolymers, - poly-s-caprolactone (PCL) and its copolymers, - polylactic acid (PLA) and its copolymers, - polyphosphazenes, - polyorthoesters, - polyesters obtained from precursors selected from polymethylene terephthalate (PTT), polybutylene terephthalate (PBT), polybutylene succinate (PBS) and any of their copolymers, - polyvinyl alcohols (PVOH) and their copolymers with ethylene (EVOH), - polyacrylates (PAC) and polyacrylic acid (PAA), - water-soluble polyacrylonitriles (PAN), - acrylic / methacrylic aster polymers, - proteins selected from zein, gluten, collagen, gelatin, casein, whey protein, soy proteins, silk fibroma and elastins, - polysaccharides selected from carrageenans, alginates, pullulan, dextran, gum arabic, and chitosan, - cellulose and its derivatives selected from ethylcellulose, methylcellulose, cellulose acetate, cellulose acetate butyrate or hydroxypropylmethylcellulose, - glycogen, starch, and thermoplastic starch (TPS), - lipids selected from waxes, resins, vegetable or mineral oils, acetoglycerides, and fatty acids -lignin and sulfonated lignin (SL), and - any combination of the above. 8.- Method according to claim 7, wherein the polymer has a molecular weight by mass (Mw) of less than 2,000,000 Daltons. 9.- Method according to claim 7, wherein the polymer has a molecular weight by mass of less than 500,000 Daltons. 10.- Method according to any of claims 1 to 9, wherein the polymer is a polyhydroxyalkanoate or PCL. 11.- Method according to claim 10, wherein the polymer is a polyhydroxyalkanoate with comonomer contents other than hydroxybutyrate of less than 10 mol%. 12.- Method according to any of claims 1 to 11, wherein the additive is selected from: - proteins selected from zein, gluten, collagen, gelatin, casein, whey protein, soy proteins, silk fibroin, elastin, -polysaccharides selected from carrageenans, alginates, pullulan, dextran, gum arabic, and chitosan, - cellulose and its derivatives selected from ethylcellulose, methylcellulose, cellulose acetate, cellulose acetate butyrate or hydroxypropylmethylcellulose, - glycogen, starch, and thermoplastic starch (tps) - lipids selected from waxes, resins, vegetable or mineral oils, acetoglycerides, and fatty acids, - lignin and sulfonated lignin (Is), - any combination of the above. 13.- Method according to any of claims 1 to 12, wherein the additive is organomodified, and is nanometric in at least one of its three dimensions. 14.- Method according to any of claims 1 to 13, wherein the selected additive is cellulose and / or lignin. 15.- Method according to claim 13 or 14, where the organomodification of the additive is selected from: - acetate, butyrate groups, - methyl, ethyl, hydroxyethyl, hydroxypropyl groups, - carboxyl groups, carboxymethyl, - acetate phthalate groups, cyanoethylated, acetate propionate, - sulfoxyethyl groups, - and combinations of them. 16.- Method according to any of claims 1 to 15, wherein the additive is cellulose acetate butyrate (CAB) in any degree of substitution. 17.- Method according to any of claims 13 to 16, wherein the degree of substitution of the organomodification of the additive is between 0.01 and 99%. 18.- Method according to any of claims 1 to 17, wherein the mixture prepared in step (a) comprises other additives that are selected from plasticizers, surfactants, reinforcements, process additives, antioxidants, colorants, nanoreinforcements or any combination thereof. 19.- Method according to any of claims 1 to 18, wherein the mixture in step (b) is subjected to an electro-hydrodynamic process.

20. The method of claim 19, wherein the electro-hydrodynamic process is selected from the list consisting of electrospinning, pressurized gas assisted electrospinning, coaxial electrospinning, electrohydrodynamic jet printing, electrohydrodynamic direct writing, melt electrospinning, electrospraying, coaxial electrospraying, and pressurized gas assisted electrospraying. 21.- Method according to claim 20, wherein the electro-hydrodynamic process is electrospinning. 22.- Method according to claim 21, wherein the process is electrospinning with multi-injectors, with or without needles. 23.- Method according to any of claims 20 to 22, wherein the electrospinning process is carried out with a voltage at the emitter of between 0.01 and 5000 kV, and a voltage at the collector of between 0.01 and -5000 kV. 24.- Method according to any of claims 20 to 23, wherein the electrospinning process is carried out at a temperature between 1 °C and 100 °C. 25.- Method according to any of claims 20 to 24, wherein the electrospinning process is carried out at a relative humidity of between 1 and 99%. 26.- Method according to any of claims 20 to 25, wherein the electrospinning process is carried out at a flow rate per emitter of between 0.001 ml / min and 500 ml / min. 27.- Method according to any of claims 20 to 26, wherein the electrospinning process is carried out with an injector speed in a mode between 0.01 and 1000 mm / s. 28.- Method according to any of claims 20 to 27, wherein the electrospinning process is carried out with an emitter-collector distance of between 0.1 and 5000 cm. 29.- Method according to any of claims 20 to 28, wherein the electrospinning process is carried out with a roll-to-roll collector system at a speed between 0.01 m / min and 10,000 m / min. 30.- Method according to any one of claims 1 to 18, wherein the mixture in step (b) is subjected to an aero-hydrodynamic process that is selected from the list consisting of: centrifugal jet spinning, draw-assisted spinning, solution-blown spinning, centrifugal blow-spinning and solution-blown spray spinning, preferably solution-blown spinning. 31.- Method according to any one of claims 1 to 30, wherein the curing process of step (c) is carried out by means of a calendering process or in a heated chamber with pressure at a temperature lower than 800 °C and at a speed between 0.01 and 100,000 rpm, pressure between 0.001 and 300 MPa and between 0.001 s and 60 min of contact time. 32.- Method according to any of claims 1 to 31, wherein the curing process of step (c), in the case of applying at least two layers of coating on the substrate, is carried out first on the first layer and then again on the second layer and so on successively as many times as the number of layers, or in a single step after applying at least the two layers. 33- Method according to any of claims 1 to 32, wherein the percentage by mass of the coating material is less than 80%, preferably less than 50% and more preferably less than 30% with respect to the mass of the substrate prior to step (c). 34.- Method according to any of claims 1 to 33, wherein the grammage of the coating material applied on the substrate is equal to or less than 60 g / m 2 , preferably less than or equal to 45 g / m 2 and more preferably is equal to or less than 15 g / m 2 . 35.- Multilayer material obtained by the method according to any of claims 1 to 34, comprising a biobased substrate with or without prior coating and a coating with at least one polymer and an additive and where the material has: - a coating weight equal to or less than 60 g / m 2 - a water vapour transmission rate between 0 and 150 g / m 2 d - an oxygen transmission rate between 0 and 50 cm 3 / m 2 d - a water and oil absorption between 0 and 6 g / m 2 - a grease resistance with a kit value greater than 6.

36. Material according to claim 35, wherein the coating further comprises additives selected from among plasticizers, surfactants, reinforcements, process additives, antioxidants, colorants, nanoreinforcements, or any combination thereof.

37. Use of the multilayer material according to any of claims 35 or 36, as packaging in the food, pharmaceutical, and cosmetics sectors.

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