EP0602203B1 - Sealed flexible bag and method for making same - Google Patents

Abstract

A sachet for preparation of a beverage. The sachet has a compact roast and ground coffee cake having first and second cake opposed surfaces extending between to a peripheral cake edge. The first opposed surface is substantially convex and configured for ensuring leaktightness in an extraction chamber that is configured for injecting water and extracting the coffee. The peripheral edge has a peripheral surface that is generally normal to the opposed surfaces. An outer sheet of a flexible material is impermeable to oxygen and water vapor and contains and impermeably seals the cake therein.

Description

The invention relates to a closed flexible bag, intended to be extracted under pressure, containing at least one pulverulent substance for the preparation of a drink. The invention further relates to the method of manufacturing said sachet.

The use of pre-dosed and prepackaged portions of ground coffee for the preparation of espresso type coffee has the advantage of facilitating the operations of preparing coffee while guaranteeing a relative consistency of product quality.

These portions currently come in three main forms. According to a first version, the portions, described in documents CH-A-636311, US-A-5012629 and EP-A-0272432, consist of two sheets of filter paper welded on their periphery and filled with ground coffee. This solution has the disadvantage of having to overpack in a sealed manner in order to avoid any oxidation of the product during storage, which constitutes a higher cost and an additional operation for the consumer in order to obtain the desired coffee extract.

The same type of solution is envisaged in document CH-A-495,138 concerning a packaging containing roasted and ground coffee with a first packaging in filter paper and an overpack. Document US-A-3,607,299 relates to a method of manufacturing a capsule made with nonwoven.

According to a second version, described in patent application WO-A-92/07775, the portion consists of a sealed capsule opening in its extraction device under the effect of the introduction of the extraction fluid after deformation then successively perforation by points.

This capsule, consisting of a sealed envelope forming a side wall and two walls, one of which constitutes the bottom of the cartridge and the other closes the opposite end of the cartridge, has the drawback of using different materials. 'packaging, some thick enough to give them semi-rigidity and can only be used in one direction, that is to say with the sealed side up with a perfectly adapted extraction device and the capsule and at his disposal.

According to a third version, document US-A-3607297 proposes sachets for the preparation of beverages in the form of a strip having filling cavities and a flat cover on the upper face. According to the author, these bags are intended for gravity flow and must be perforated on both sides by toothed plates, one of which is pushed by a spring.

The object of the present invention is to provide a closed flexible sachet containing roast and ground coffee and intended to be extracted under pressure for the preparation of a drink, said sachet not requiring any overpackaging and the extraction system being only suitable for sachet and not at the disposal of said sachet, because it is perfectly capable of being extracted in one direction or the other.

The present invention also aims to minimize the amount of material necessary for packaging a portion.

The invention relates to a flexible bag in the form of an individual portion consisting of two thin sheets and identical, of circular, oval or polygonal shape, leaving between them a space for the pulverulent substance and welded on their periphery so that said sachet is substantially symmetrical with respect to its welding plane. The material used for the flexible sheets is impermeable to oxygen and water vapor. The sachet is opened under the effect of the pressure rise alone during the injection of the extraction fluid.

The bag according to the invention is intended to be used as it is in the extraction device provided.

As the bag according to the invention is symmetrical, the user can introduce it into the extraction system without paying attention to the direction of introduction. On the other hand, the sachet is directly ready for use and does not require any prior preparation before putting it in the extraction system.

Alternatively, for reasons specific to manufacturing, the two flexible sheets may however be slightly different from each other in shape and / or material, without detracting from the symmetry sought for the extraction.

The method and the device used for the extraction of sachets according to the invention may advantageously be of the type which is the subject of patent application EP No 92'107'548.7 or EP 92'112'364. The upper face of the sachet is first opened by one or more perforating elements provided under the upper face of said device and the lower face is opened by localized ruptures consecutive to its deformation against the raised and hollow elements neither perforating nor sharp arranged on the underside of said device under the effect of the pressure rise alone during the injection of the extraction fluid. There is therefore no need to open the sachet beforehand or remove a fraction of the material before use. After use, said bag can be easily removed with a minimum of waste.

However, in the case where there is only a partial extraction device with respect to that described above, that is to say not comprising the means for opening one or the other of the two faces. , for example a device such as that of conventional espresso machines, it can be produced, just before placing in this partial extraction device, in one and / or the other side of the bag of openings, allowing the fluid to pass through. extraction.

The inside diameter of the bag is preferably between 25 and 70 mm and the welded edge has a width of 3 to 15 mm. Once filled, the bag has a thickness at its center, preferably between 5 and 20 mm. The dose of pulverulent substance contained can vary between 5 and 20 g, depending on its use.

The sachet is filled with a powdery substance for the preparation of a drink. This substance is preferably roasted and ground coffee, but can also be tea, soluble coffee, a mixture of ground coffee and soluble coffee, a chocolate product or any other edible dehydrated substance.

The outer shape of the bag is preferably circular, but can also be oval or polygonal from 4 to 10 sides with possibly rounded edges, or can be a combination of these three elements. Its section is preferably substantially flattened hexagonal, but may also have a lenticular shape.

In an alternative embodiment, not shown below, the bag is provided with at least one lateral tab facilitating its installation. This tab is simply provided when cutting the bag.

According to a first configuration, the sachet consists of two sheets welded on their periphery, the welding being carried out on a flat face.

In a first manufacturing variant, the two sheets will have been stretched beforehand (deformation in the plastic area) in order to avoid any random folds due to the volume of an originally flat material, either by means of compression in a matrix-piston assembly, either by means of the pressurization by a gas of the interior faces and / or possibly of a suction of the exterior faces in a mold of suitable shape at controlled temperature where the sheets are maintained planes at their periphery.

In a second variant, the material is simply pushed back as in the two previous examples, but in this case it is not retained on its periphery and will then have folds, more or less random resulting from the setting in volume of a surface plane.

According to a second configuration, the two sheets are preformed in a systematic and controlled manner and the welding is carried out, after filling of the pulverulent substance, according to a three-dimensional device. Indeed, by setting in volume a flat surface without stretching neither elastic nor plastic, one modifies the apparent diameter of the material compared to its real diameter. This excess material must be compensated by an adequate geometric shape in order to avoid any random folds.

To achieve this goal, the systematic and controlled molding takes place in a mold where, in any place, the principle of equality of the apparent diameter deployed and the actual diameter is ensured. This is obtained in the mold by the creation of more or less high undulations and widening towards the outside. In the central part of the leaves of the bag, the deformation is nonexistent or reduced because it is the reference plane. On the other hand, by evolving towards the outside diameter, these undulations increase in height and flare. The corrugation is maximum at the weld edge. This undulation depends on the ratio between the diameter of the bag and the distance between the planes of the welding zone and that in the central zone of the bag, that is to say the half-depth of the bag.

The two sheets of the sachet undergo an equivalent volume setting and are positioned during the welding, after filling, so as to be superposed perfectly on one another. The welding area of the two sheets is therefore in the form of a circular corrugated strip.

This molding of the sheets is ensured, either by means of compression in a matrix-piston assembly, or by means of the pressurization by a gas of the interior faces and / or of a suction of the exterior faces. In both cases the mold has the desired relief.

According to a third configuration, the bag can have bellows, on one or more sides. The bellows, resulting from a folding prior to the welding of the sheets, make it possible to give a defined volume to the assembly while eliminating random folds. The bags according to this latter embodiment can be manufactured in a manner known per se.

• couche extérieure: PET (normal, tissé ou non tissé), PE, PP, PA, PS ou papier
• couche centrale haute barrière: aluminium d'une épaisseur de 5 à 20 µm, EVOH, PVDC, PET, ou PVA
• couche intérieure: plastique, de préférence PE ou PP ou OPP. On peut envisager les combinaisons multicouches suivantes: PET-EVOH-PE ou PET-aluminium-PE. L'utilisation de matériau biodégradable ou hydrosoluble est également possible en monocouche ou en combinaison avec d'autres matériaux.

The sheets can be made of flexible material such as aluminum with a thickness of 5 to 40 µm or plastic such as PET. Preferably, the sheets will be made of a flexible multilayer material suitable for welding by the usual methods while constituting sufficient protection of the product against oxygen and water vapor. The following combination of materials is recommended:

• outer layer: PET (normal, woven or non-woven), PE, PP, PA, PS or paper
• high barrier central layer: aluminum with a thickness of 5 to 20 µm, EVOH, PVDC, PET, or PVA
• inner layer: plastic, preferably PE or PP or OPP. The following multilayer combinations can be envisaged: PET-EVOH-PE or PET-aluminum-PE. The use of biodegradable or water-soluble material is also possible in a monolayer or in combination with other materials.

In the case where PET is used, it can be presented in a single layer combining the exterior and the central, especially if it is loaded with a layer of silicon oxide or if it is metallized.

In an alternative embodiment, the heat-sealing operation is facilitated by the insertion between the two sheets of an intermediate material, such as a food adhesive or a lining of plastic material. This material can then form an additional thickness used to achieve a perfect seal during extraction.

The sachet according to the invention preferably contains a compacted substance, in the form of one or more pieces, the compaction rate being such that there is a reduction in volume compared to the non-compacted substance of between 10 and 60% . This compaction is carried out so that the free space between the two flexible sheets and said substance represents between 1 and 20% of the total space between said flexible sheets. This free space is necessary to allow the coffee, when extraction, swell enough to ensure good extraction.

The compacted substance also has, on at least one of its faces, imprints forming water circulation channels of suitable shape (for example cross, circle) making it possible to improve the pre-wetting of the sachet and its extraction. The shape of these imprints is chosen in relation to the extraction device used.

The compacted material can also have on at least one of its faces a concave or convex shape allowing, if necessary, to modify the compacting state during its positioning in the extraction device.

This shape is adapted to the layout of the extraction chamber and can be used to ensure good sealing of the sachet in the peripheral zone of the injection, ie between the upper face of the extraction chamber and the upper sheet. from the sachet.

The invention further relates to the method of manufacturing the sachet described above, in which two flexible sheets impermeable to oxygen and water vapor are deformed symmetrically by molding or by stretching, the quantity of pulverulent substance, said substance is deposited on one of the deformed flexible sheets and the two sheets are welded around their periphery.

The pulverulent substance is usually compacted during the manufacturing process.

According to a first embodiment, the substance can be compacted after dosing and depositing it between the leaves of the sachet.

According to a second preferred embodiment, the substance is compacted then dosed and deposited between the sheets of the sachet. Depending on the shape and size of the pieces of compacted substance, one or more pieces are used to obtain the desired dose.

The compaction is carried out in a conventional manner, either by rollers or by a matrix-piston assembly, the physico-chemical parameters such as pressure, temperature, humidity of the coffee are adapted to the nature of the substance to be compacted.

According to a particular embodiment, the compacted substance can be partially or completely unpacked after closing the bag, for example by vibration or by any other known mechanical means.

A new compacting according to a pressure and an appropriate shape can still be carried out after the closure of the sachet.

When the pulverulent substance is subject to oxidation, the manufacturing operations can be carried out under the protection of a stream of inert gas free of oxygen, for example under nitrogen or CO2.

Certain plastics have the property of substantially resuming their initial shape after being temporarily deformed. The bag according to the invention takes advantage of this property, together with an appropriate configuration of its extraction device. Thus the lips of the openings formed by the perforated parts of the sachet close around tapered perforating organs such as needles, ensuring the desired seal around this organ during extraction. After extraction, this same property effectively limits disgorgement of the sachet when released, including on the parts torn by the extraction system.

The symmetry of the sachet, both in shape and in material, its flexibility and the property noted above allow to vary at will the mode and location of the introduction of water and extraction. Both can for example be concentric, on the same face or on the opposite faces, the objective remaining to make the water travel an optimal path.

The flexibility of the walls of the bag is also used to allow, by its deformation without rupture in the extraction device, a reconfiguration of the volume of coffee contained. This controlled deformation then aims to improve the distribution of the flow in the coffee bed and consequently the quality of extraction.

Furthermore, taking into account the method of extraction for which it is intended, the sachet consists of a combination of materials chosen according to an additional criterion of plasticity. The deformability by elongation of its material must be sufficient to allow the shaping described above, but it must also, under the effect of the pressure of the liquid and at the location of the reliefs of the extraction device, rupture in the form of small tears without its elongation being too great.

• Fig. 1 est une représentation schématique en coupe du sachet selon l'invention,
• Fig. 2 est une représentation schématique en coupe du sachet selon une seconde forme de réalisation,
• Fig. 3 est une perspective de la feuille moulée utilisée pour le sachet de la Fig. 2,
• Fig. 4 est une vue en plan d'un sachet selon une troisième forme de réalisation,
• Fig. 5 est une représentation schématique en coupe selon la ligne A-A' de la Fig 4,
• Fig. 6 est une perspective d'une feuille du sachet, dans une quatrième forme de réalisation.
• Fig. 7 est une vue perspective du café compacté non emballé.

The following description is made with reference to the drawings given by way of nonlimiting examples in which:

• Fig. 1 is a schematic sectional representation of the bag according to the invention,
• Fig. 2 is a schematic sectional representation of the bag according to a second embodiment,
• Fig. 3 is a perspective view of the molded sheet used for the bag of FIG. 2,
• Fig. 4 is a plan view of a bag according to a third embodiment,
• Fig. 5 is a diagrammatic representation in section along line AA ′ in FIG. 4,
• Fig. 6 is a perspective of a sheet of the sachet, in a fourth embodiment.
• Fig. 7 is a perspective view of the unpackaged compacted coffee.

The sachet (1) of circular shape comprises two sheets of flexible material (2) and (3) welded on their periphery (4) by heat sealing and containing ground roasted coffee (5) compacted for the preparation of a drink. The compacted coffee has concave faces (35), the general shape of its section being a flattened octagon, while that of the sachet is hexagonal. The purpose of the cylindrical blank (38) of the wafer is to avoid the undesirable presence of grains in the welding zone.

To give a numerical example, there is a sachet leaving a total space between the two sheets of 15 cm3, the volume of the compacted coffee being 14 cm3 with a compaction rate of 30%.

The bag (10), of FIG. 2 obtained from two molded sheets (6, 7) has undulations (8), (12) and (13) whose amplitude and the distance from one to the other increases from the flat face (11) towards the welding edge (9). In this example, the coffee cake has a single concave face (35) and is not exactly symmetrical, but this difference is not related to the shape of the bag.

Fig. 3 clearly shows a molded sheet (7) with a flat bottom (11) and more and more pronounced corrugations as one approaches the outer edge. These corrugations have bumps (14) and hollows (15).

After having deposited the roasted and ground coffee on the bottom (11), the sheet (6) is placed so as to have opposite the bumps of (6) facing the hollows of (7) and vice versa. We can then heat seal.

With reference to Figs. 4 and 5, the bag (18) is square in shape with two bellows on the opposite sides. The two sheets (20) and (22) are welded along the two bellows at (19, 23, 24, 25) and at the edges (26, 27) where the two sheets are simply joined. The bellows make it possible to give a defined volume to the bag without the appearance of a random fold.

Fig. 6 shows a sheet (30) having undulations (31) on the edge, but also on the bottom (32). The manufacturing is done in the same way as for the bag of FIG. 2.

Fig. 7 shows the compacted substance alone (36). It has on at least one face areas (37) of water circulation in the form of channels allowing uniform pre-wetting and extraction.

Explanation of abbreviations

PVDC

: Polyvinylidene chloride

EVOH

: Copolymer of ethylene and vinyl alcohol

PP

: Polypropylene

PE

: Polyethylene

FART

: Polyester

PA

: Polyamide

PVA

: Polyvinyl alcohol

OPP

: Oriented polypropylene

Claims (18)

1. A sealed flexible sachet in the form of an individual portion, adapted to be extracted under pressure, containing at least one powdered substance for the preparation of a beverage selected from ground roast coffee, tea, soluble coffee, a mixture of ground coffee and soluble coffee, a chocolate product or any other edible dehydrated substance, consisting of two identical flexible sheets of circular, oval or polygonal shape, which provide between one another a space for a powdered substance and are sealed over their periphery so that the said sachet is substantially symmetrical with respect to its plane of sealing, the material used for the flexible sheets being impermeable to oxygen and water vapour for its storage and the sachet being opened only under the effect of the increase in pressure when the extraction fluid is injected.
2. A sachet as claimed in claim 1, characterized by the presence of at least one tongue prolonging the edge of the sachet.
3. A sachet as claimed in any one of claims 1 or 2, characterized in that the two sheets are stretched in order to support volume expansion without folding.
4. A sachet as claimed in one of claims 1 or 2, characterized in that corrugations are intentionally and systematically provided in the two sheets.
5. A sachet as claimed in one of claims 1 or 2, characterized in that it comprises one or two gussets.
6. A sachet as claimed in any one of claims 1 to 5, characterized in that the substance to be extracted is compacted and takes the form of one or a plurality of pieces, the degree of compaction being such that there is a volume reduction of between 10% and 60%.
7. A sachet as claimed in claim 6, characterized in that the free space between the two flexible sheets and the compacted substance represents between 1 and 20% of the total space between the said flexible sheets.
8. A sachet as claimed in one of claims 6 or 7, characterized by the general hexagonal shape of the section of the sachet and the general octagonal shape of the compacted cake, providing an empty volume in the peripheral space, this space facilitating sealing free from powder.
9. A sachet as claimed in any one of claims 1 to 8, characterized in that the compacted material has impressions on at least one of its surfaces adapted to facilitate the optimum distribution of water.
10. A sachet as claimed in any one of claims 1 to 9, characterized in that the compacted material has at least one concave or convex surface.
11. A sachet as claimed in any one of claims 1 to 10, characterized in that the powdered material is ground roast coffee.
12. A sachet as claimed in any one of claims 1 to 11, characterized in that the material for the flexible sheets is selected from aluminium, PET, PE, PP, PA, PS, paper, EVOH, PVDC and PVA, the said sheets being single-layer or multi-layer.
13. A sachet as claimed in any one of claims 1 to 12, characterized in that the material for the flexible sheets has the property that it creates leak-tightness about the water introduction means and closes again at least partially during removal to prevent discharges.
14. A method for the manufacture of a sachet as claimed in any one of claims 1 to 13, characterized in that two flexible sheets impermeable to oxygen and water vapour are deformed in a symmetrical manner by moulding or by stretching, the quantity of powdered substance is metered out, this substance is placed on one of the deformed flexible sheets and the two sheets are sealed over their periphery.
15. A method as claimed in claim 14, characterized in that the powdered substance is compacted into one or a plurality of pieces prior to metering.
16. A method as claimed in claim 14, characterized in that the powdered substance is compacted after being placed on one of the flexible sheets.
17. A method as claimed in any one of claims 14 to 16, characterized in that the compacted substance is decompacted after the closure of the sachet during the manufacturing process, for instance by vibration or by any other known mechanical means.
18. A method as claimed in any one of claims 14 to 16, characterized in that the operations prior to the closure of the sachet are carried out under a current of an inert, oxygen-free, gas.

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