Method for manufacturing a capsule intended to receive a substance for preparing a beverage

Abstract

The invention relates to a method for manufacturing a capsule (1) intended to receive a substance for preparing a beverage, the capsule comprising a body (1a) having a side wall (2) bordered on either side by a bottom (3) and by a rim (4) surrounding an opening (5) in the body, the method including: forming the body (1a) by molding a cellulose pulp, coating at least the side wall (2) of the body with a chemical formulation capable of forming a hydrophobic coating on the wall by means of a reaction mechanism of the sol-gel type, and then subjecting the coated formulation to reaction conditions so as to form the hydrophobic coating.

Description

[0001] DESCRIPTION

[0002] Method for manufacturing a capsule intended to receive a substance for the of a drink

[0003] The invention relates to a method for manufacturing a capsule intended to receive a substance for the preparation of a beverage, as well as such a capsule.

[0004] Capsules are known whose body has a side wall bordered on both sides by a bottom and a rim surrounding an opening of said body, the substance for the preparation of a drink being introduced into said capsule through said opening, then enclosed inside said capsule by association, for example by gluing, of a lid on the rim to cover the opening.

[0005] Such capsules are primarily intended for preparing hot beverages such as coffee, tea, or infusions. To do this, a capsule is inserted into a designated compartment in a machine, where it is held in place by a piston while an extraction liquid, such as hot water, is passed through it and the substance it contains. The capsule is then expelled from the machine by gravity after the piston is removed.

[0006] The capsule must be opened to allow the drink to flow through it, but the substance must be kept in the capsule with good barrier properties against oxygen and air moisture in order to preserve its organoleptic properties.

[0007] To achieve this, capsules are known whose body is formed by stamping a sheet of metallic material, particularly aluminum. Such capsules offer good airtight and moisture-proof properties, but are expensive to produce and difficult to recycle.

[0008] We also know, for example from documents WO-2024 / 028247 and WO-2024 / 28248, of capsules whose body is formed by molding a cellulose pulp, the side wall of said body being covered with a coating and / or a sealing label.

[0009] These capsules have an improved ecological impact, in that they are biodegradable and compostable, both industrially and domestically, and also guarantee good organoleptic preservation of the substance they contain.

[0010] However, a cellulose capsule has the disadvantage of not being inert with respect to water, particularly under the combined effect of the temperature and pressure to which it is subjected during the preparation of the drink.

[0011] Thus, after use, swelling and / or softening of the capsule may be observed, which may hinder its expulsion by gravity, particularly due to poor interference between the machine and the edge of said capsule.

[0012] The invention aims to improve the prior art by proposing in particular a manufacturing process and a cellulose capsule whose expulsion by gravity after use is made more reliable.

[0013] To this end, according to a first aspect, the invention proposes a method for manufacturing a capsule intended to receive a substance for the preparation of a beverage, said capsule comprising a body having a lateral wall bordered on both sides by a bottom and by a rim surrounding an opening of said body, said method providing for forming the body by molding a cellulose pulp, coating at least the lateral wall of said body with a chemical formulation capable of forming on said wall a hydrophobic coating by a sol-gel type reaction mechanism, and then subjecting said coated formulation to reaction conditions to form said hydrophobic coating.

[0014] According to a second aspect, the invention proposes a capsule intended to receive a substance for the preparation of a beverage, said capsule comprising a body having a lateral wall bordered on both sides by a bottom and by a rim surrounding an opening of said body, the body being formed by molding a cellulose pulp, at least the lateral wall of said body being provided with a hydrophobic coating formed by a sol-gel type reaction mechanism.

[0015] Other features and advantages of the invention will become apparent in the following description, made with reference to the attached Figure 1, which represents an axial section of a capsule according to the invention.

[0016] In relation to this figure, a manufacturing process for a capsule 1 intended to receive a substance for the preparation of a beverage is described below, as well as a capsule 1 which can in particular be manufactured by implementing such a process.

[0017] The capsule 1 comprises a body 1a having a lateral wall 2 bordered on both sides by a bottom 3 and by a rim 4 surrounding an opening 5 of said body.

[0018] Body 1a is formed by molding a cellulose pulp, and preferably contains exclusively cellulose, in particular 100% from sustainable and / or organic farming.

[0019] Thus, it is possible to manufacture a capsule 1 that is easily recyclable in a low cost and with high yield, with reduced carbon dioxide emissions, especially compared to injection molding of a plastic material.

[0020] Furthermore, the exclusive use of cellulose results in a capsule whose body can be easily composted, both industrially and domestically, with a significantly reduced composting time (approximately one month) compared to the average composting time of capsules made from molded compostable plastic (around six months). Specifically, capsule 1 is biodegradable and / or compostable according to standard EN 13432.

[0021] According to one embodiment, the body 1 of the capsule 1 is formed by dry molding of a sheet of cellulose pulp, which makes it possible to considerably increase the manufacturing yield of the capsule while limiting the number, size and cost of the facilities required, as well as the costs in water and energy.

[0022] In particular, the use of such a manufacturing process makes it possible to obtain a production yield of capsules 1 of the order of 1000 capsules per minute, for an annual production volume exceeding one billion capsules 1.

[0023] The dry molding manufacturing process of the body 1a of the capsule 1 involves forming a sheet of cellulose pulp, then thermoforming the body 1a of the capsule 1 by hot molding said sheet.

[0024] According to one embodiment of this process, prior to thermoforming, air is injected into the cellulose pulp layer. Specifically, the process may involve:

[0025] - separating cellulose fibers from a cellulose source, in particular by grinding a natural cellulose source, such as wood pulp, cotton, flax, hemp, or sugar cane, or a recycling source, such as paper, cardboard, or textiles;

[0026] - to collect the cellulose fibres thus separated on a conveyor belt, in particular by injecting air into them upstream of their grinding, following a process called "air 'ugly'", so as to form on said conveyor belt a fluffy, thick and dense layer, with a basis weight of between 300 and 15000 g / m 2 ;

[0027] - compact said downy layer, in particular by passing between two compressor rollers, possibly heated, so as to obtain a cellulose pulp layer of controlled thickness, in particular between 500 and 700 pm; - preheat said layer, in particular to a temperature between 150 and 170°C;

[0028] - compress said preheated sheet in a mold of suitable shape, in particular by means of a hydraulic press, with a pressure of the order of 45 MPa, in order to obtain by thermoforming bodies 1a of capsule 1 from said compressed sheet.

[0029] According to another embodiment of dry molding the body 1a of capsule 1, the layer is to be formed as a sheet of cellulose pulp, having a thickness of between 0.5 and 1 mm, for example, approximately 0.75 mm. In particular, the sheet can be made from NBSK (Northern Bleached Softwood Kraft) type cellulose pulp.

[0030] Advantageously, the sheet can be moistened, for example by spraying water on the surface, before thermoforming, in order to improve its molding capacity while allowing the water to evaporate during thermoforming.

[0031] According to another embodiment, the process can provide for forming the body 1a of the capsule 1 by wet molding, that is to say by preparing a paste comprising cellulose pulp suspended in water, the body 1a of the capsule 1 being formed with said paste before it dries.

[0032] The cellulose pulp used makes it possible to obtain the food compatibility which is necessary for the packaging of a beverage preparation substance in capsule 1, in particular by eliminating the need for the addition of an internal food-compatible coating.

[0033] In particular, the cellulose pulp used is free of substances harmful to health and / or the environment, which could contaminate the beverage preparation substance by contact with the body 1a of the capsule 1. Advantageously, the process involves molding the body 1a from a cellulose pulp comprising microfibrillated cellulose (MFC, for Micro-Fibrillated Cellulose), in particular between 1% and 50% by weight of microfibrillated cellulose MFC.

[0034] Microfibrillated cellulose (MFC) consists of individual cellulose microfibrils or aggregates. These microfibrils typically have a diameter of 2 to 20 nanometers and a length on the order of a few micrometers. Microfibril aggregates are composed of several cellulose microfibrils agglomerated together.

[0035] The production of microfibrillated cellulose (MFC) is based on the release of the secondary cell wall components of lignocellulosic fibers by mechanical means coupled with enzymatic or chemical pretreatments. The fibers used can be raw or bleached chemical pulps, mechanical pulps produced from wood, recycled pulps, etc.

[0036] In relation to the figure, the body 1a of the capsule 1 presents a geometry of revolution around a central axis A forming a lateral wall 2 which is generally inscribed in a truncated cone with a right generatrix between the bottom 3 and the upper rim 4.

[0037] In an alternative not shown, the side wall 2 may have a substantially cylindrical geometry of revolution.

[0038] Capsule 1 is equipped with a top lid (not shown) which is associated with the rim 4 to cover the opening 5, forming in said body a compartment for loading the substance.

[0039] In one embodiment, the opening 5 allows the substance to be loaded into the compartment, which is closed at the opposite end by the bottom 3. This opening is then closed by the upper lid after loading. In the figure, the bottom 3 includes a lower opening 6 intended to be covered by a lower lid (not shown). In particular, the lower opening 6 can first be covered by the lower lid, so that the substance can be loaded into the compartment through the upper opening 5, which is then closed by the upper lid.

[0040] Alternatively, the capsule 1 shown in the figure can be loaded from the bottom 3. In this case, the upper opening 5 is first covered by the upper lid, then the capsule 1 is turned over so that the substance can be loaded through the lower opening 6, the lower lid then being associated with said capsule to close said compartment before the preparation of the drink.

[0041] Capsule 1 is specifically designed for preparing hot beverages such as coffee, tea, or infusions. To do this, capsule 1 can be placed in the housing of a machine designed for this purpose, where at least one pin passes through to inject extraction liquid, such as hot water, into the substance contained within capsule 1. In particular, capsule 1 is held in a piston during extraction before being expelled by gravity after the piston is removed at the end of the preparation process.

[0042] The injection of the liquid induces an increase in pressure in the compartment to allow, after rupture of a frangible wall of capsule 1, the flow of the drink out of said capsule.

[0043] During beverage preparation, capsule 1 is subjected to an injection of water at a temperature between 86°C and 90°C and under a pressure of up to 20 bars, for a duration of approximately 2 minutes. Specifically, to prepare a coffee-type beverage, the quantity of water injected into capsule 1 is between 40 mL and 150 mL.

[0044] The capsule 1 shown in the figure is adapted to be placed in a machine where it is held by a piston equipped with pins to pierce its base 3 or lower lid. In addition, the base 3 or lower lid is pierced by at least one pin to inject extracting liquid into the substance contained in the capsule 1, which induces a pressure increase in the compartment to allow, after the upper lid ruptures, the flow of the beverage through the opening 5.

[0045] In particular, the lower lid can be arranged to be easily passed through by the injection pins, especially more easily than the cellulose base 3 of capsule 1, in order to limit the risks of deformation of said capsule during its use.

[0046] Furthermore, the machine includes a base equipped with a network of pins, on which the upper lid is designed to break under the effect of the increase in pressure in the capsule 1, in order to allow the flow of the drink.

[0047] According to an embodiment not shown, the capsule can be arranged to allow the preparation of a beverage by piercing its upper lid with injection pins for extracting liquid, the bottom of the capsule then having means to allow its opening under the effect of the increase in pressure in said capsule, in order to allow the beverage to flow from said bottom.

[0048] For this purpose, the base may have a central opening which leads into the compartment for conditioning the substance, as well as an upper wall which extends substantially radially into said compartment, and on which is formed a network of raised studs, a perforable membrane being disposed in said compartment between the substance and the raised studs.

[0049] Alternatively, the base may have perforation means in the form of projections extending outside the capsule, supported by a plate with openings allowing the passage of the beverage, a lower operculum being positioned opposite said projections inside the compartment for packaging the substance, being associated with an annular rim radially surrounding said projections.

[0050] Thus, when the capsule 1 is placed in a machine to prepare a drink, the upper lid 16 is pierced by at least one pin to inject extracting liquid into the compartment, which causes an increase in pressure, under the effect of which the lower membrane or lid tears on the perforation means of the bottom 3, in order to allow the drink to flow through said bottom.

[0051] After manufacturing body 1a, the process involves coating at least the side wall 2 of said body with a chemical formulation capable of forming on said wall a hydrophobic coating by a sol-gel type reaction mechanism, and then subjecting said coated formulation to reaction conditions to form said hydrophobic coating.

[0052] The plaintiff noted that such a hydrophobic coating made it possible to greatly improve the reliability of the gravity expulsion of capsule 1 after use, in particular in that it makes said capsule substantially inert with respect to the pressure and temperature of the extracting liquid.

[0053] In particular, the performance of a hydrophobic coating formed by a sol-gel type reaction mechanism makes it possible to guarantee the dimensional stability and mechanical properties of the body 1a of the capsule 1 after use, in particular by preventing its swelling and / or softening, in order to maintain the interference between the machine and the capsule which allows its expulsion by gravity at the end of the preparation of the drink.

[0054] According to one embodiment, the process involves coating the chemical formulation over the entire surface of the body 1a of the capsule 1, in order to benefit from the performance of the hydrophobic coating over the entire capsule 1. Alternatively, the process involves coating the chemical formulation over most of the surface of the body 1a, notably with the exception of a ring formed on the lower wall 4a of the rim 4, on which a peripheral edge of the machine piston is intended to come into contact during the preparation of the beverage.

[0055] This latter variant allows a portion of cellulose without hydrophobic coating to be left at the level of the ring, which promotes the sealing of the piston support, and thus limits the risks of leakage of extractor liquid and / or beverage during extraction.

[0056] Advantageously, the chemical formulation is biodegradable and / or compostable, thus facilitating the recycling of capsule 1 after use. Furthermore, the chemical formulation exhibits food-grade compatibility, thereby avoiding the need for an additional layer between the hydrophobic coating and the beverage preparation substance. Such coatings are described in particular in documents FR-3 136 236, WO-2022 / 112566, WO-2022 / 171893, and WO-2021 / 119220.

[0057] According to one embodiment, the chemical formulation comprises a suspension of colloidal particles, which is prepared by mixing in particular suitable chemical precursors, including alkoxides and / or metallic salts, for example of silicon (tetraethylorthosilicate TEOS and / or tetramethoxysilane TMOS), titanium (tetra-n-butyl-titanate) and / or aluminium (aluminium isopropoxide), with water, possibly supplemented with a non-aqueous solvent, in particular based on ethanol and / or methanol.

[0058] According to a preferred embodiment, the chemical formulation is prepared from silicon precursors, in particular based on TEOS and / or TMOS.

[0059] The solvent is arranged to dissolve chemical precursors and facilitate chemical reactions within the suspension, and can also influence the rate of the sol-gel reaction mechanism required for the formation of the hydrophobic coating, as well as the final structure of the material on which said hydrophobic coating is formed.

[0060] The presence of water is also essential to allow the hydrolysis of the precursors, which is a key step in the formation of the gel that constitutes the hydrophobic coating. Indeed, water causes the breaking of the M-OH chemical bonds (where M is a metal), replacing the alkoxyl groups with hydroxyl groups (-OH), which allows the polymerization of the colloidal particle network to begin.

[0061] The chemical formulation may also include at least one catalyst, in particular an acid such as hydrochloric acid or a base such as ammonia, in order to control the rate of the hydrolysis and condensation reactions, the nature and / or quantity of said catalyst(s) determining the final properties of the material on which the hydrophobic coating is applied.

[0062] To obtain hydrophobic properties, the chemical formulation includes specific hydrophobic agents such as fluorinated silanes and / or organosilanes.

[0063] The chemical formulation may also include other additives and / or modifying agents, such as complexing agents, stabilizing agents, and / or surface modifiers, to adjust its physicochemical properties, including viscosity, stability, and / or wettability. Such additives can also be used to control the porosity and / or texture of the final hydrophobic coating.

[0064] To form the hydrophobic coating, the process may involve:

[0065] - prepare the chemical formulation by: o hydrolysis, by mixing the chosen chemical precursors with water, in order to replace the alkoxyl groups of said precursors with hydroxyl groups (-OH); o condensation, by reaction of the hydroxyl groups with each other, so as to form MOM bonds (where M is a metal), and to release water and / or alcohol, thus obtaining a three-dimensional network; o freezing, by allowing the three-dimensional network to extend over the entire volume of the liquid, and thus trap the water and any solvent;

[0066] - coat the chemical formulation at least on the lateral wall 2 of a capsule body 1a 1, in particular by dipping, spraying or transferring;

[0067] - to form the hydrophobic coating by allowing said chemical formulation to age and then dry on said side wall, so as to eliminate water and any solvent, and thus form a porous and solid hydrophobic coating layer.

[0068] Temperature, pH, and / or reaction time can be adjusted at any stage of coating formation to influence the final physicochemical properties. For example, lower temperatures allow for more delicate chemical formulations, while higher temperatures accelerate network polymerization.

[0069] In particular, after its coating on the body 1a of the capsule 1, the hydrophobic formulation can be subjected to further heat treatment, in order to harden and densify the structure of the coating, but also to improve its adhesion to the side wall 2 of said body and to develop its final physicochemical properties.

[0070] Once the coating has dried, the hydrophobic agents it contains orient themselves towards the surface of the coating, creating a water-repellent surface layer. This results in a low surface energy coating that causes droplets to bead and roll off, thus minimizing water absorption and contamination of the capsule body 1a. Due to its water content, the use of such a hydrophobic coating reduces the use of volatile organic compounds (VOCs), making it more environmentally friendly than alternatives based on non-aqueous solvents.

[0071] The formation of a coating by sol-gel reaction also proves to be particularly versatile, notably for the following reasons:

[0072] - it can be carried out at relatively low temperatures compared to other coating processes, which helps to reduce energy consumption;

[0073] - it allows for very precise control of the chemical composition of the final coating;

[0074] - it allows a homogeneous mixing of precursors at the molecular level, which makes it possible to obtain a uniform distribution of materials in said final coating, essential to obtaining uniform physical and chemical properties throughout said coating;

[0075] - it allows the manufacture of different forms of coatings, including thin films.

[0076] Such a hydrophobic sol-gel coating also offers the following advantages:

[0077] - good mechanical stability;

[0078] - resistance to abrasion;

[0079] - good durability, particularly under different environmental conditions;

[0080] - optical transparency;

[0081] - additional features, including protection against sunlight (UV), fogging, corrosion resistance, and self-cleaning properties.

[0082] In order to preserve the organoleptic characteristics of the stored substance before its use in preparing a beverage, the capsule 1 must be airtight, in particular by forming a barrier against the circulation of oxygen and moisture, both into the capsule, to prevent alteration of the substance it contains by ambient air and humidity, and outwards, in particular to prevent the drying out of a substance packaged in a moist and / or fatty form.

[0083] In particular, to ensure optimal preservation of the substance, capsule 1 has the following characteristics:

[0084] - an oxygen transmission rate of less than 10 cm 3 / m 2 .day.atm, in particular of no more than 5 cm 3 / m 2 .day.atm, and more specifically less than 1 cm 3 / m 2 .day.atm, measured according to ASTM D3985 standard;

[0085] - a water vapor transmission rate of less than 60 g / m 2 .24h, and more specifically less than 10 g / m 2 .24h, measured according to ASTM E96 standard in tropical conditions (38°C and 90% humidity).

[0086] With such characteristics, capsule 1 can notably be stored:

[0087] - before filling with a beverage preparation substance: at a temperature between 15 and 25°C, and up to 50°C for a maximum of 6 weeks during transport;

[0088] - after filling: in a dry and temperate place, with a maximum ambient humidity level between 35 and 55%.

[0089] To do this, the body of capsule 1 can be subjected to a preliminary treatment to close the pores of the cellulose layer constituting it, in order to form a first barrier against oxygen and water vapor.

[0090] Furthermore, the use of a cellulose pulp comprising microfibrillated cellulose MFC contributes favorably to the sealing of the capsule against oxygen and water vapor, while promoting the mechanical hold of the hydrophobic coating on the body 1a.

[0091] Advantageously, the hydrophobic coating obtained by the sol-gel reaction mechanism is designed to also exhibit barrier properties against oxygen and moisture, thereby reducing the number of components required to manufacture capsule 1, and thus facilitating its production at lower costs. Furthermore, the hydrophobic coating allows for a reduction in the number of additives incorporated into the cellulose pulp.

[0092] The hydrophobic coating can advantageously be made from a chemical formulation including silicic acid, in particular silicon oxoacid (SiO₂). xwith x varying between 1.5 and 5, and in particular SiC), of carbon and nanoparticles. Indeed, the use of silicon oxoacid makes it possible to obtain a coating with effective barrier properties against the diffusion of gases and water vapor, but also with low density, a large specific surface area, and good thermal insulation properties.

[0093] Alternatively, an additional sealing coating and / or label may be applied to the side wall 2 of the capsule 1 in addition to the hydrophobic coating, in order to reinforce and / or provide the specific oxygen and / or water vapor barrier properties required to ensure the preservation of the substance's organoleptic properties.

Claims

DEMANDS 1. A method for manufacturing a capsule (1) intended to receive a substance for the preparation of a beverage, said capsule comprising a body (1a) having a side wall (2) bordered on both sides by a bottom (3) and by a rim (4) surrounding an opening (5) of said body, said method comprising forming the body (1a) by molding a cellulose pulp, coating at least the side wall (2) of said body with a chemical formulation capable of forming on said wall a hydrophobic coating by a sol-gel type reaction mechanism, and then subjecting said coated formulation to reaction conditions to form said hydrophobic coating.

2. Manufacturing process according to claim 1, characterized in that the body (1a) of the capsule (1) is formed by dry molding of a sheet of cellulose pulp or by wet molding of a paste comprising cellulose pulp suspended in water.

3. Manufacturing method according to claim 2, characterized in that it involves forming a sheet of cellulose pulp and then thermoforming the body (1a) of the capsule (1) by hot molding said sheet.

4. A manufacturing process according to any one of claims 1 to 3, characterized in that it involves molding a cellulose pulp comprising microfibrillated cellulose MFC.

5. A manufacturing process according to any one of claims 1 to 4, characterized in that the chemical formulation is biodegradable and / or compostable.

6. A manufacturing process according to any one of claims 1 to 5, characterized in that the chemical formulation is coated on the side wall (2) by dipping, spraying or transfer.

7. A manufacturing method according to any one of claims 1 to 6, characterized in that the chemical formulation is coated over the entire surface of the body (1a) of the capsule (1).

8. A manufacturing method according to any one of claims 1 to 6, characterized in that the chemical formulation is not coated along a ring formed on the lower wall (4a) of the rim (4).

9. Capsule (1) intended to receive a substance for the preparation of a beverage, said capsule comprising a body (1a) having a lateral wall (2) bordered on both sides by a bottom (3) and by a rim (4) surrounding an opening (5) of said body, said body being formed by molding a cellulose pulp, at least the lateral wall (2) of said body being provided with a hydrophobic coating formed by a sol-gel type reaction mechanism.

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