Water-soluble, biodegradable film based on casein and / or caseinate for the production of packaging or labels and its production process

Abstract

The present invention relates to a film comprising casein and / or caseinate, and cellulose. This film can be used as packaging, in particular as water-soluble packaging, or for producing water-soluble labels.

Description

Title of the invention: Biodegradable water-soluble film based on casein and / or caseinate for the production of packaging or labels and method for obtaining it Technical field

[0001] The field of the invention is that of thermoplastic, water-soluble and bio-sourced films, more precisely that of thermoplastic films based on casein and / or caseinate.

[0002] In particular, the present invention relates to a film comprising casein and / or caseinate, and cellulose. This film can in particular be used as packaging or for producing water-soluble labels or multi-layer materials. Technological background

[0003] The reduction of non-renewable resources, such as oil, and the increase in pollution linked to these resources are leading to the development of alternative solutions that are less polluting and more respectful of the environment.

[0004] In the field of plastic films, new biodegradable materials are being developed. These new films can be made from naturally occurring polymers or synthetic polymers. For example, plant proteins, such as corn and soy proteins, or animal proteins can be used to make packaging.

[0005] Among animal proteins, casein is particularly interesting. Indeed, this protein from milk is accessible in large quantities and casein-based films have good transparency and good biodegradability.

[0006] Document FR2963013 describes biodegradable thermoplastic films based on casein and / or caseinate and their manufacturing process. However, these thermoplastic films are not easily exploitable industrially. For example, the film may have insufficient mechanical properties and may be sticky. It is then difficult, or even impossible, to pull on the film to unwind the film reels using industrial equipment because the different layers stick together. Thus, it is impossible to unwind the reels without the film breaking.

[0007] Improving these properties is therefore necessary to be able to use this type of film in certain applications such as packaging or water-soluble labels. The latter are generally composed of a layer of adhesive and a layer of plastic film (polypropylene, polyethylene terephthalate or other). Thus, it would therefore be interesting to use a water-soluble and biodegradable film based on casein / caseinate for this type of product.

[0008] In this context, the present invention aims to satisfy at least one of the following objectives.

[0009] One of the objectives of the present invention is the provision of a casein / caseinate based film having improved mechanical properties.

[0010] Another object of the present invention is to provide a casein / caseinate based film having low reel tack so that it can be reeled and then unwound.

[0011] Another object of the present invention is the provision of a casein / caseinate based film which can be used to produce water-soluble labels. Abstract

[0012] The invention relates firstly to a film characterized in that it comprises (in % by mass): a. between 25 and 80% casein and / or caseinate, preferably between 30 and 70%, preferably between 40 and 65%; b. between 1 and 20% cellulose, preferably between 2 and 15%; c. between 3 and 17% water, preferably between 5 and 15%; and d. between 10 and 30% of at least one plasticizer different from c), preferably between 15 and 25%.

[0013] The inventors discovered that the mixture of casein / caseinate and cellulose made it possible to obtain a film having improved mechanical properties, in particular a higher Young's modulus and breaking stress. In addition, this film has a low reel stickiness, so the film reel can be unwound easily. These improved properties make it possible to use this film industrially.

[0014] In particular, it is possible to use this film to produce water-soluble packaging and / or labels.

[0015] The invention also relates to a multilayer material comprising: i) At least one layer of support A, preferably a cellulosic material A, and ii) At least one layer of material B comprising a film

[0016] The invention also relates to a water-soluble label comprising a film.

[0017] The invention also relates to the use of a film for producing a water-soluble label, or a multi-layer material.

[0018] The invention also relates to a packaging comprising at least one layer of film or at least one multi-layer material.

[0019] The invention also relates to a product, characterized in that it is packaged by a film, a multilayer material, or by packaging.

[0020] The invention also relates to a method of manufacturing a film characterized in that it comprises the following steps: 1. implementation of an extruder, preferably a twin-screw extruder; 2. introduction of compounds a) to d) into the extruder; 3. recovery of granules at the outlet of the extruder; 4. possibly drying the granules; 5. extrusion swelling of the granules to obtain a film

[0021] The invention also relates to a method of manufacturing a film, characterized in that it comprises the following steps: 1. Mixture of compounds a) to d) in water; 2. Casting the mixture obtained in step 1 onto a casting surface; and 3. Evaporation of part of the water to form a film.

[0022] The invention also relates to a method for packaging a product using a film, a multilayer material or a package, characterized in that it comprises the following steps: 1. Thermoforming of a first piece of film, multi-layer material or packaging; 2. Wrapping the product in the first piece of multi-layer material film or thermoformed packaging; and 3. Sealing with a second piece of film, multi-layer material or packaging, preferably with water or an aqueous solution.

[0023] The invention also relates to a method for packaging a product using a film, a multilayer material, or a package, characterized in that it comprises the following steps: 1. Wrapping the product to be packaged in a piece of film, multi-layer material or packaging; 2. Heat sealing of film, multi-layer material or packaging; 3. Optionally, humidification of the film, multi-layer material or packaging; and 4. Heat shrinkage of the film, multi-layer material or packaging, at a temperature between 80°C and 200°C.

[0024] Furthermore, the film may be bio-sourced. The film may be thermoplastic. The film may be biodegradable. Detailed description

[0025] By "film" is meant, for example, a film or a sheath (tubular film) obtained by inflation extrusion, flat die extrusion or solvent route. It is well known to those skilled in the art that inflation extrusion makes it possible to obtain a sheath which is then cut to obtain a film.

[0026] By "packaging" is meant an object intended to contain and protect goods, to allow their handling and their transport from the producer to the consumer or user, and to ensure their presentation, conservation, protection and / or use.

[0027] By "thermoplastic" is meant, for example, a material which becomes malleable and pliable above a given temperature, the glass transition temperature Tg, but which below this Tg becomes hard again, these transformations being reversible.

[0028] By "biodegradable" is meant, for example, a film that can be decomposed under the action of micro-organisms (bacteria, fungi, algae, etc.). The result of this decomposition is the formation of water, CO2 and / or methane and possibly by-products (residues, new biomass) that are non-toxic to the environment. This is, for example, a film according to the European standard EN NF 13432.

[0029] By "between x and y" we mean, for example, that the limits x and y are included in the interval [%, y],

[0030] By "water-soluble" is meant, for example, that which dissolves in water. The water solubility of a film can be measured as follows: a piece of film (5 cm x 5 cm, cut with a die cutter) is fixed on a slide holder and then immersed in a 1000 ml capacity beaker, containing 600 ml of distilled water at 20°C while stirring, with a magnetic bar, at 300 rpm. The time taken for the film to break through is measured. The disintegration of the film leads to the formation of film particles. The test lasts 10 minutes after which the particles are passed through a 2 mm sieve to check the particle size. When there are no particles in the sieve, the film is considered water-soluble.

[0031] By "plasticizer" is meant, for example, a substance making it possible to lower the glass transition temperature Tg of the film.

[0032] By "detergent" is meant, for example, a composition which has cleaning properties. Among the detergents, mention may be made of dishwasher products and laundry detergents. The detergents may be in powder, compacted powder or liquid form.

[0033] By "hydrophobic" is meant, for example, a compound having little affinity for water and tending not to dissolve in it. Typically, it is a predominantly apolar compound.

[0034] By "hydrophilic" is meant, for example, a compound having an affinity for water and having a tendency to dissolve therein. Typically, it is a compound having polar groups capable of forming hydrogen bonds.

[0035] By "surfactant" is meant, for example, an amphiphilic molecule, that is to say a molecule possessing both hydrophilic and hydrophobic properties.

[0036] By "HLB" is meant, for example, the hydrophilic-lipophilic balance. The HLB value can be calculated according to the following method: HLB=20 x (Molar mass of the hydrophobic part) / (Molar mass of the molecule).

[0037] By "sequestering agent" is meant, for example, ligands which form chemical complexes with metal ions such as copper, iron, nickel, calcium and magnesium.

[0038] By "fatty acid" is meant, for example, an aliphatic monocarboxylic acid.

[0039] By “bio-sourced” we mean, for example, a product manufactured from materials of biological origin.

[0040] By "reel stickiness" is meant, for example, the adhesion of 2 or more turns of film reels to each other. When the reel stickiness is high, it is difficult, or even impossible, to unwind the film because the turns are difficult to separate. The present invention seeks to have a low reel stickiness in order to be able to unwind the film easily. The reel stickiness can for example be determined by means of an unwinding test, as presented in the examples.

[0041] Unless otherwise indicated, the percentages are expressed by mass relative to the total mass of the film. Movie

[0042] The invention relates firstly to a film characterized in that it comprises (in % by mass): a. between 25 and 80% casein and / or caseinate, preferably between 30 and 70%, preferably between 40 and 65%; b. between 1 and 20% cellulose, preferably between 2 and 15%; c. between 3 and 17% water, preferably between 5 and 15%; and d. between 10 and 30% of at least one plasticizer different from c), preferably between 15 and 25%.

[0043] The proportions of the different constituents a), b), c), d), and of the other constituents potentially present are expressed in % by mass relative to the total mass of the film.

[0044] The film may be water-soluble. It may be printable and / or printed. The film may be biodegradable. According to a preferred embodiment, the film is water-soluble and biodegradable.

[0045] The film comprises a) between 25 and 80% of casein and / or caseinate. The film may comprise between 30 and 70%, between 40 and 65%, or between 45 and 65% of casein and / or caseinate.

[0046] Casein is a protein derived from milk that is poorly soluble in water. It is mainly obtained by precipitation by adding an acid (acid casein) or rennet (rennet casein) to the milk, or by filtration (micellar casein). Casein consists of a mixture of α-casein, β-casein and K-casein having molar masses between between 19000 and 25000g / mol. Caseinate means, for example, a casein salt whose counter cation is chosen from the group comprising - preferably consisting of - calcium, potassium, ammonium, sodium and magnesium.

[0047] According to one embodiment of the film, a) comprises at least one casein.

[0048] According to another embodiment of the film, a) comprises at least one caseinate, for example a sodium caseinate, or a mixture of caseinates.

[0049] According to another embodiment of the film, a) comprises a mixture of casein and at least one caseinate. In this case, the mass ratio between the casein and the caseinate(s) may be between 5 / 95 and 95 / 5, 20 / 80 and 80 / 20 or 40 / 60 and 60 / 40.

[0050] The film comprises b) between 1 and 20% of cellulose, preferably between 2 and 15%. The film may comprise between 2.5 and 15% of cellulose.

[0051] The addition of cellulose improves the mechanical properties of the film. The addition of cellulose also reduces the film's reel stickiness. It is therefore possible to use film reels in industrial applications.

[0052] By cellulose is meant any type of cellulose, and its derivatives. Among the celluloses which can be used in the present invention, mention may be made of ultrafine cellulose, microcrystalline cellulose, cellulose fibers, cellulose powder, methylcellulose, ethylcellulose, hydroxymethylcellulose, hydroxypropylmethylcellulose, ethylmethylcellulose, and carboxymethylcellulose. According to a particular embodiment, the film comprises ultrafine cellulose, or microcellulose.

[0053] The film comprises c) between 3 and 17% of water, preferably between 5 and 15%, and preferentially between 8 and 14%. The water acts as a plasticizer which must be distinguished from the plasticizer d) entering into the composition of the film according to the invention.

[0054] The film comprises d) between 10 and 30% of at least one plasticizer different from c), preferably between 15 and 25%, preferentially between 16 and 24%.

[0055] This plasticizer d) can be chosen from polyols, glycerol acetates, glycerol propionates and their mixtures.

[0056] Examples of polyols include glycerol, hexanetriol, glycols, including ethylene glycol, and sugars and their derivatives.

[0057] Examples of sugars include disaccharides, such as maltose, lactose, sucrose, and monosaccharides such as fructose.

[0058] Among the sugar derivatives, mention may be made of their hydrogenated derivatives such as sorbitol, maltitol, mannitol, and xylitol, or even the transformation products of these hydrogenated derivatives such as sorbitan.

[0059] According to one embodiment of the film, the plasticizer d) is chosen from glycerol, sorbitol, mannitol, ethylene glycol and mixtures thereof. Preferably, the plasticizer d) is chosen from glycerol, sorbitol, and mixtures thereof. According to one embodiment, the plasticizer d) is glycerol.

[0060] Plasticizer d) may contain residual water.

[0061] Plasticizer d) makes it possible to lower the viscosity of the product by increasing the mobility molecular chains.

[0062] Advantageously, the plasticizer d) is a hydrophilic plasticizer.

[0063] The film may further comprise between 0.01 and 8% of a hydrophobic agent e), preferably between 0.1 and 4%, and preferentially between 0.1 and 2%.

[0064] Advantageously, the film comprises between 0.5 and 6%, preferably between 1 and 3%, of a hydrophobic agent e).

[0065] The hydrophobic agent e) can be chosen from: - polycarboxylic acid esters; - C3-C33 carboxylic acids, preferably C4-C28 fatty acids, and even more preferably C6-C28 unsaturated fatty acids; - and their mixtures.

[0066] The polycarboxylic acid esters may be derived from at least one polycarboxylic acid and at least one alcohol, preferably a C1-C18 alcohol.

[0067] Among the polycarboxylic acids preferentially retained within the scope of the invention, mention may be made of citric acid, hydroxycitric acid, tartaric acid, malic acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, maleic acid, fumaric acid.

[0068] Among the preferred alcohols in accordance with the invention, mention may be made of C2-C6 alcohols, such as for example ethanol, n-propanol, Ao-propanol, n-butanol and tert-butanol.

[0069] According to one embodiment of the film, the hydrophobic agent e) is chosen from triethyl citrate, tributyl O-acetyl citrate, tributyl citrate and mixtures thereof.

[0070] According to one embodiment, the hydrophobic agent e) is a C3-C33 carboxylic acid, preferably a C4-C28 fatty acid, and even more preferably an unsaturated C6-C28 fatty acid.

[0071] Among the C4-C28 fatty acids retained within the scope of the invention, mention may be made of caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, and mixtures thereof.

[0072] Among the particularly interesting C6-C28 unsaturated fatty acids, mention may be made of palmitoleic acid, oleic acid, linoleic acid, and mixtures thereof.

[0073] The film may further comprise between 0.5 and 6% of at least one surfactant f), preferably chosen from zwitterionic surfactants whose HLB is between 2 and 8

[0074] Advantageously, the film comprises between 0.1 and 5% of at least one surfactant f), preferably between 1 and 4.5%, and even more preferably between 1.5 and 3%.

[0075] Among the preferred surfactants, mention may be made of lecithin and / or its analogues such as Diacetylene phosphonates, and polysorbates. Polysorbates are esters of fatty acids and polyoxyethylene sorbitan. Polysorbates include polysorbate 20, polysorbate 40, polysorbate 60, and polysorbate 80.

[0076] According to one embodiment of the film, the ratio of the quantities of d) to f) is greater than or equal to 1. For example, this ratio may be between 1.3 and 3; preferably between 1.5 and 2.5.

[0077] The film may also comprise gelatin g).

[0078] Gelatin is a protein that has a high level of glycine and proline. It is obtained by partial hydrolysis of collagen, mainly from collagen contained in animal skins and bones. It can be type A (it then comes from an acid treatment of collagen) or type B (it then comes from a basic treatment of collagen). It can also be obtained by enzymatic treatment of collagen. The gelatin used has preferably not been chemically modified. According to one embodiment of the invention, the gelatin used is commercially available food gelatin or type B, it can be in the form of sheets, powder or granules. Advantageously, the gelatin used is type B.

[0079] The ratio of quantities a): g) may be between 99:1 and 60:40, preferably between 95:25 and 70:30.

[0080] ” According to one embodiment of the film, said film also comprises an additive i) selected from colorants, protein coagulants, anti-caking agents, slip agents and mixtures thereof. Among the coagulants, mention may be made of citric acid and acetic acid. Among the anti-caking agents, mention may be made of colloidal silica. Among the slip agents, mention may be made of polyethylene glycols and fatty chain compounds, preferably C12-C28, having an amide termination. The film may comprise between 0.001% and 15% of i).

[0081] According to one embodiment, the film comprises an additive i) which is a colorant.

[0082] By colorant is meant any substance capable of giving a color, such as for example pigments. The film according to the invention may therefore contain at least one pigment, which may be chosen from TiO2, calcium carbonate and their mixture. According to one embodiment, the film comprises between 0.001% and 15% of at least one pigment i), preferably between 0.1 and 12%, and preferentially between 1 and 10%, and more preferentially between 5 and 8%.

[0083] According to a particular embodiment, the film comprises: a. between 25 and 80% casein and / or caseinate, preferably between 30 and 70%, preferably between 45 and 65%; b. between 1 and 20% cellulose, preferably between 2 and 15%; c. between 3 and 17% water, preferably between 5 and 15%; d. between 10 and 30% of at least one plasticizer different from c) chosen from glycerol, sorbitol, and their mixtures, preferably between 15 and 25%; e. optionally, between 0.1 and 8% of a hydrophobic agent which is a C4-C28 fatty acid, preferably between 1 and 4%, and f. between 0.5 and 6% of at least one surfactant, preferably lecithin.

[0084] Typically, the film has a thickness of between 15 and 150 microns, preferably between 25 and 150 microns, preferably between 30 and 120 microns and more preferably between 40 and 100 microns. The film can be printed directly before winding or in a second step of unwinding, cutting and rewinding by a conventional plastics printing process such as flexography.

[0085] The film may be heat-shrinkable. The film may be bio-sourced, in particular at more than 60%, 70%, 80% or 90%.

[0086] The invention also relates to a package comprising at least one layer of film as described above. The package may be a package comprising several layers, for example a layer of plastic and a layer of film. These packages may be manufactured by lamination, coating, laminating, co-extrusion or extrusion coating processes well known to those skilled in the art.

[0087] The invention also relates to the use of a film or packaging for packaging various products (pharmaceutical, food, chemical, cosmetic, etc.) such as, for example, hygroscopic products, and more specifically detergents. The product may be in solid or liquid form. The packaged product may be a liquid product.

[0088] The invention also relates to a product packaged by a film as described above, or by a package as described above. The product may be in solid, liquid or gel form. The packaged product may be chosen from pharmaceutical, food, chemical and cosmetic products.

[0089] According to one embodiment, the packaged product is a food product, such as for example meat, fish, vegetables, fruits, pastries, Viennese pastries, food additives, ingredients, dry preparations, food powders.

[0090] According to one embodiment, the packaged product is a cosmetic product.

[0091] According to one embodiment, the packaged product is a liquid product, such as example liquid shampoo or liquid detergent.

[0092] According to another particular embodiment, the packaged product is a chemical product, for example a detergent, in liquid or powder form.

[0093] According to one embodiment, the packaged product is a detergent, preferably liquid laundry detergent.

[0094] Detergents can be in liquid or powder form, whether compact or not. For example, it can be a detergent tablet. Detergent tablets include dishwasher tablets and laundry tablets. It can also be a liquid detergent, such as liquid laundry detergent.

[0095] The invention also relates to a detergent packaged by a film or packaging.

[0096] The invention also relates to a water-soluble label comprising a film such as as described above. The label consists of a water-soluble film layer and an adhesive layer. The film can serve as a water-soluble and biodegradable carrier for the adhesive.

[0097] Multilayer material

[0098] The present disclosure relates to a multilayer material comprising: (i) At least one support layer A, and ii) At least one layer of material B comprising a film as described above.

[0099] The support layer A can be made of any type of material, such as for example a plastic material or a cellulosic material.

[0100] By “cellulosic material” is meant, for example, a material that can be derived from a cellulose pulp. This cellulose pulp can be produced by chemical and / or mechanical treatment, which is well known to those skilled in the art. This cellulose pulp can be derived from any suitable source such as wood, recycled wood, annual plants, agricultural residues (bagasse, straws, ...), grasses (e.g., sugar cane, bamboo) or cardboards.

[0101] The present disclosure also relates to a multilayer material obtained: - either by coating a support layer A, with a solution comprising the components of the material layer B, - either by assembling a support layer A and a layer of material B comprising a film as described above, possibly by means of a binder, the assembly preferably being carried out by complexing or lamination - either by extrusion coating of a layer of material B on a support A.

[0102] The support A is preferably a cellulosic material. The multilayer material is preferably recyclable and / or bio-sourced. The multilayer material may be recyclable according to Directive 2018 / 852 / EU of May 30, 2018. According to one embodiment, the multilayer material may be compostable, preferably according to standard NF T 51-800.

[0103] The multilayer material may have a thickness of between 0.01 and 100 mm, preferably between 0.05 and 50 mm.

[0104] When the support A is a cellulosic material, it is preferably chosen from papers and cardboards. According to one embodiment, the cellulosic material A has a grammage of between 20 and 500 g / m2, preferably between 50 and 450 g / m2. According to one embodiment, the cellulosic material A is chosen from papers having a weight of between 20 and 225 g / m2, and cardboards having a weight of between 225 and 500 g / m2.

[0105] The layer of cellulosic material A may have a thickness of between 0.01 and 50 mm, preferably between 0.05 and 20 mm.

[0106] The cellulosic material A comprises cellulose, preferably at least 80% by weight, and preferably at least 90% by weight. The cellulosic material A may comprise a mineral layer, for example of the kaolin type.

[0107] Support A may be colored and comprise a pigment layer.

[0108] By "binder" is meant, for example, an agent for creating a bonding layer between the support layer A and the material layer B. The binder used in the present invention may be a binder conventionally used in the manufacture of multilayer materials and in particular, multilayer films. Among the binders, mention may be made of acrylic aqueous dispersions.

[0109] The multilayer material may be manufactured by lamination, coating, laminating, co-extrusion or extrusion coating processes well known to those skilled in the art.

[0110] The present disclosure also relates to a method of manufacturing a multilayer material, characterized in that it is carried out - either by coating a support layer A with a solution S - either by assembling a support layer A and a layer of material B, possibly using a binder, the assembly preferably being carried out by complexing or lamination - either by extrusion coating of a layer of material B on a layer of support A.

[0111] According to one embodiment, the manufacture of the multilayer material is carried out by coating. In this case, the support layer A is coated with a solution S. This can be done using a coating material well known to those skilled in the art. After coating, the coated support A can be dried, for example in an oven, in order to obtain the multilayer material.

[0112] According to another embodiment, the manufacture of the multilayer material is carried out by assembling a support layer A and a layer of material B. In this case, the assembly can be carried out by complexing or lamination.

[0113] Lamination can be carried out cold or hot. In the case of cold lamination, a binder can be used. In the case of hot lamination, this step can be carried out without a binder.

[0114] The complexing can be carried out by a counter-gluing, co-extrusion or extrusion coating step, with or without binder.

[0115] When a binder is used, the assembly can for example be carried out by coating one of the faces of one of the materials A or B with a binder, then bringing the two materials into contact so that the binder is between the two materials. This assembly can be carried out by means of a calender. Method of manufacturing a film

[0116] According to another of its aspects, the invention relates to a method of manufacturing the film as described above comprising the following steps: 1. implementation of an extruder, preferably a twin-screw extruder; 2. introduction of compounds a) to d) into the extruder; 3. recovery of granules at the outlet of the extruder; 4. possibly drying the granules; 5. extrusion swelling of the granules to obtain a film.

[0117] Advantageously, step 1) consists of operating the extruder with the following parameters: rotation speed between 100 and 700 rpm, and at a temperature between 40 and 150°C.

[0118] In step 2), compounds a) to d) are introduced simultaneously or successively, preferably successively.

[0119] In a preferred embodiment, the compounds in solid form, advantageously in powder form, are compounds a) & b); while the compounds in liquid form are compounds c), d).

[0120] According to another of its aspects, the invention relates to a method of manufacturing the film as described above comprising the following steps: 1. Mixture of compounds a) to d), in water; 2. Casting the mixture obtained in step 1 onto a casting surface; and 3. Evaporation of part of the water to form a film.

[0121] The casting surface can be any surface, for example it can be a plate.

[0122] The evaporation step can be carried out at room temperature or by heating, for example at a temperature between 25°C and 100°C, and / or under air flow.

[0123] The evaporation step may be followed by a film coating step.

[0124] It is therefore possible to manufacture the film by extrusion or by solvent method.

[0125] According to another of its aspects, the invention relates to a method of packaging a product using the film as described above or a package as described above. The packaging can be carried out by thermoforming and / or sealing, which are techniques well known to those skilled in the art.

[0126] According to one embodiment, the packaging method comprises the following steps: 1. Thermoforming of a first piece of film or packaging; 2. Wrapping the product in the first piece of film or thermoformed packaging; and 3. Seal with a second piece of film or packaging, preferably with water or an aqueous solution.

[0127] The film or packaging may be thermoformed by passing a flow of air at a temperature between 70°C and 200°C, preferably between 80 and 170°C, and even more preferably between 90 and 150°C, for a time between 0.05 seconds and 60 seconds, preferably between 1 and 30 seconds, and more preferably between 2 and 10 seconds.

[0128] According to one embodiment, during step 3), the film or packaging is moistened with water or an aqueous solution by means of a mist sprayer and / or a humidifier and / or a vaporizer for a duration which may range from 0.01 seconds to 60 seconds, on at least one of the two faces and / or perimeter of the tablet.

[0129] Conditioning may also be carried out by placing the film or packaging in an oven whose relative humidity level can be controlled. The relative humidity level may, for example, be between 10 and 80%, between 10 and 40%, or between 20 and 40%, or be greater than or equal to 30%.

[0130] According to another embodiment, the packaging method comprises the following steps: 1. Wrapping the product to be packaged in a piece of film or packaging; 2. Heat sealing of the film or packaging; 3. Optionally, moistening the film or packaging; and 4. Heat shrinkage of the film or packaging, at a temperature between 80°C and 200°C. Examples

[0131] Example 1

[0132] Thermoplastic granules were prepared by extrusion from sodium caseinate and cellulose. The cellulose used is an ultrafine cellulose (ARBOCEL UFC M8 / ARBOCEL UFC 100 from JRS Rettenmaier)

[0133] The extruder used is a BC 21 co-rotating twin-screw extruder from Clextral®. This extruder has at least 4 zones: a first introduction zone, a second introduction zone, a third degassing zone, and a fourth die zone.

[0134] The rotation speed of the twin screws is between 175 and 400 rpm and the tem The temperatures of the different zones are between 30 and 120°C. The first zone of the extruder is a zone for introducing powders: caseinate, cellulose and lecithin. The liquids (plasticizers) are introduced in the second zone. The extruder also has a degassing zone in the open air and a final zone consisting of a cylindrical rod die with a diameter of 4 mm. At the outlet of the extruder, the rod is cooled and introduced into a granulator to produce granules of 2 to 3 mm in diameter.

[0135] These granules are then transformed into film by extrusion-inflation. The extruder used is of the Diani® brand, the screw has a diameter of 30 mm and is equipped with an annular die of 30 mm diameter. The film produced is approximately 130 mm wide and its thickness can vary between 130 and 20 μm. The temperatures are between 90 and 130°C.

[0136] The process is as follows: 1. Passing a purge through the extruder; 2. Passage of dry granules based on caseinate and cellulose into the extruder; 3. Formation of the bubble by injection of compressed air; 4. Passage of the sheath between several rollers 5. Cutting the film sheath; and 6. Double winding of the film onto mandrels to form the film reels. The resulting film is wound over a length of 500 m for characterization.

[0137] The final composition of the film is as follows: 60% sodium caseinate, 5.9% cellulose, 20.5% glycerol, 10% demineralized water, 2.3% soy lecithin, and 1.3% oleic acid.

[0138] Comparative example (NaCas)

[0139] A comparative film (without cellulose) was produced according to the procedure described in Example 1. The final composition of the film is as follows: 63% sodium caseinate, 23.5% glycerol, 10% demineralized water, 2.3% soy lecithin, and 1.1% oleic acid.

[0140] Mechanical properties

[0141] The breaking stress, Young's modulus and elongation at break of the films were evaluated as follows. The samples were selected in the direction Ion- gitudinal to measure the mechanical properties, and conditioned 24 hours in a climatic chamber where the temperature and relative humidity are controlled, they are programmed at 23°C and 50% RH. The equipment used is a Shimadzu AGS-X brand tensile bench, equipped with a 50 N measuring cell and connected to a computer with data processing software, TrapeziumX. The tests were conducted on the film, on dumbbell specimens in 5 valid repetitions, the tensile speed is fixed at 20 mm / min.

[0142] The results are presented below.

[0143] [Tables 1] Example Example 1 Comparative example Young's modulus (Mpa) 457.6 ± 35.3 250 ± 20 Elongation (%) 13.8 ± 1.9 19 ±2 Stress at break (Mpa) 7.3 ±0.9 5.4 ± 1 Maximum stress (Mpa) 9.3 ±0.3 6.5 ± 1

[0144] These results show that the films according to the invention have good mechanical properties. The Young's modulus and the breaking stress are significantly improved for the films according to the invention compared to a film without cellulose. Furthermore, the elongation remains entirely acceptable.

[0145] Water solubility

[0146] The dissolution tests were conducted after conditioning the films (square specimens) in a climatic chamber at 23°C and 50% RH. They were evaluated in demineralized water at 20°C.

[0147] The piercing time of the films according to the invention is 44s. This test shows that the films according to the invention are soluble in water.

[0148] Unwinding test

[0149] This test is carried out on an unwinding installation including a force sensor. This force sensor is used to measure the tension at the film winder during unwinding, and therefore the stickiness of the reel. The results are shown in the table below. The length of the reel is 200 meters, 114mm wide

[0150] [Tables2] Example Example 1 Comparative example Start of coil 0.063 N 0.8 N Middle of coil 0.25 N 1.1 N End of coil 0.66 N Not measurable / Film tear

[0151] These results show that the films according to the invention have much lower unwinding forces, and it is not possible to completely unwind the film reel of the comparative example.

[0152] The stability of the film was also evaluated. Film reels according to the invention and according to the comparative example were stored at 40°C for 4 days. After 4 days, it is still possible to unwind the film reels according to the invention, whereas it is impossible to unwind the film reel according to the comparative example.

Claims

Claims

1. Film characterized in that it comprises (in % by mass): a. between 25 and 80% of casein and / or caseinate, preferably between 30 and 70%, preferentially between 40 and 65%; b. between 1 and 20% of cellulose, preferably between 2 and 15%; c. between 3 and 17% of water, preferably between 5 and 15%; and d. between 10 and 30% of at least one plasticizer different from c), preferably between 15 and 25%.

2. Film according to claim 1, characterized in that it further comprises between 0.1 and 6% of at least one surfactant f), preferably chosen from zwitterionic surfactants whose HLB is between 2 and 8.

3. Film according to one of the preceding claims, characterized in that it comprises at least one pigment i)

4. Multilayer material comprising: i) At least one support layer A, preferably a cellulosic material A, and ii) At least one layer of material B comprising a film according to one of claims 1 to 3.

5. Water-soluble label comprising a film according to one of claims 1 to 3.

6. Water-soluble label according to claim 5, characterized in that it comprises a layer of adhesive.

7. Use of a film according to one of claims 1 to 3 for producing a water-soluble label, or a multi-layer material.

8. Packaging comprising at least one layer of film according to one of claims 1 to 3 or at least one multilayer material according to claim 4.

9. Product, characterized in that it is packaged by a film according to one of claims 1 to 3, a multilayer material according to claim 4, or by packaging according to claim 8.

10. A method of manufacturing a film according to any one of claims 1 to 3, characterized in that it comprises the following steps:

1. use of an extruder, preferably a twin-screw extruder; 2. introduction of compounds a) to d), into the extruder;

11.

12.

13. 3. recovery of granules at the outlet of the extruder; 4. possibly, drying of the granules; 5. extrusion swelling of the granules to obtain a film. Method of manufacturing a film according to any one of claims 1 to 3, characterized in that it comprises the following steps:

1. Mixture of compounds a) to d) in water; 2. Casting the mixture obtained in step 1 onto a casting surface; and 3. Evaporation of part of the water to form a film. Method of packaging a product using a film according to any one of claims 1 to 3, a multilayer material according to claim 4, or packaging according to claim 8, characterized in that it comprises the following steps:

1. Thermoforming of a first piece of film, multi-layer material or packaging; 2. Wrapping the product in the first piece of multi-layer material film or thermoformed packaging; and 3. Sealing with a second piece of film, multi-layer material or packaging, preferably with water or an aqueous solution. Method of packaging a product using a film according to any one of claims 1 to 3, a multilayer material according to claim 4, or packaging according to claim 8, characterized in that it comprises the following steps:

1. Wrapping the product to be packaged in a piece of multi-layer material or packaging film; 2. Heat sealing of the multi-layer material film or packaging; 3. Optionally, moistening the film of multi-layer material or packaging; and 4. Heat shrinkage of the multi-layer material or packaging film, at a temperature between 80°C and 200°C.