[0002] Various capsules for use in a device for preparing beverages are known in the prior art. A known capsule, as described for example in EP0512468, comprises an essentially frustoconical housing composed of a peripheral wall, an end inlet side connected to the peripheral wall, and an engaging edge connected laterally to the peripheral wall for clamping the capsule into a capsule holder of the device for preparing beverages. The engaging edge is connected to a perforable film that also forms the outlet side of the capsule. The housing is filled with a substance to be extracted, such as ground coffee beans. This known capsule can be placed in a device for preparing a beverage. For this purpose, the capsule is placed in a capsule holder, into which the capsule is then clamped, thus causing the inlet side of the capsule to be perforated. After this, warm water at fairly high pressure (6-20 bar) is to be fed into the capsule holder and thus into the capsule via the inlet side, where the water is to come into contact with the substance, thus forming the final beverage. The pressure build-up in the capsule is to cause the film to be deformed in such a way that the film is perforated by the capsule holder, with the result that the formed beverage can leave the capsule. The housing of the capsule described in the aforementioned patent is composed of aluminium. Although aluminium has fairly favourable barrier properties, allowing it to preserve the coffee for a long period of time, the processing of aluminium is fairly problematic. Moreover, the capsule is to be discarded after use, generally by means of standard waste disposal, which leads to considerable environmental pollution.
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[0004] An objective of the invention is to provide a fairly reliably functioning capsule for preparing beverages which, particularly after use, leads to reduced environmental pollution.
[0005] For this purpose, the invention thus provides a capsule of the type mentioned initially, comprising an essentially closed housing that is at least partially filled with a substance to be extracted and/or dissolved, such as ground coffee, for preparing a beverage, with the housing being essentially closed, in which the housing is at least defined by a peripheral wall, an end side connected to the peripheral wall, and a laterally protruding engaging edge connected to the peripheral wall at a distance from the end side in order to allow the capsule to be clamped into a capsule holder of a device for preparing beverages; and at least one essentially closed closing element connected to the laterally protruding engaging edge for sealing the substance into the capsule in order to preserve it, wherein at least a part of the closing element is composed of a laminated film, which film comprises at least one oxygen barrier layer, which barrier layer is essentially impermeable to oxygen, and which film comprises at least one carrier layer connected to the oxygen barrier, wherein at least one carrier layer is provided with at least one weakened area. The film is preferably made essentially solely of plastic. For this purpose, the film is preferably composed of a plurality of polymer layers, including the oxygen barrier layer and the at least one carrier layer. Preferably, no metal layer is applied in the film. The oxygen barrier layer makes it possible to preserve, in an oxygen-free or low-oxygen manner, the substance contained in the capsule, generally ground coffee, tea leaves, instant soup, or (chocolate) milk powder for preparing coffee, soup, tea or (chocolate) milk respectively.
The oxygen barrier layer is generally configured in a completely closed manner. Preferably, the closed oxygen barrier layer is not weakened in order to make it possible to keep the oxygen barrier as favourable and uniform as possible. It is preferred in this case that the oxygen barrier have an essentially uniform layer thickness. The at least one carrier layer is configured to carry, hold in place, and support the - generally thinner - oxygen barrier layer. At least one carrier layer is provided with at least one (previously formed) weakened area, with the result that the carrier layer is weakened. This weakened area can be formed in various ways, as will be explained in further detail below. The weakened area serves to allow the film to tear in a simple, and preferably controlled, manner, when the capsule is used in a device for preparing beverages. If no weakened area is formed, a plastic (multilayer) film tends to stretch rather than tear, which can make opening of the capsule on the outlet side considerably more difficult and even impossible. Because of the (site-selective) weakened area in at least one carrier layer, tearing of the film is made considerably easier, and in general, the tearing behaviour of the film will essentially be consistent with the tearing behaviour of a classic aluminium-based film.
[0006] The film may conceivably comprise a plurality of carrier layers. It is also conceivable that the plurality of carrier layers of the film may be configured in weakened form. This makes it possible to keep the film sufficiently easy to tear while providing each carrier layer with its own functionality. For example, it is conceivable that each carrier layer could directly or indirectly play a role in supporting the oxygen barrier layer, with, for example, at least one first carrier layer functioning primarily as a carrier, while at least one other carrier layer functions more as a moisture barrier. It is preferred that at least two of the weakened film layers be adjacent to one another. More preferably, the weakened areas of the adjacent layers should be in line with one another. This can be carried out fairly easily by application of a heated stamp or laser that simultaneously processes the aforementioned carrier layers. Application of a stamp results in reduced local (site-selective) layer thickness, and thus a weakened area of the film layer. However, it is preferred that the at least one weakened carrier layer be configured with perforations. The openings made in the at least one carrier layer are preferably composed of microperforations. In this case, it is preferred for these openings to completely penetrate the at least one carrier layer. The (micro)perforation can fairly easily be formed by application of a laser that burns the perforation into the at least one polymer carrier layer. In this case, the intensity and wavelength of the laser can be adjusted in such a way that only the one or plurality of superposed carrier layers are perforated and the underlying oxygen barrier layer (and other layers if applicable) are not damaged by the laser. It is preferred in this case that the perforations be made in a pattern in the at least one weakened carrier layer. Preferably, this pattern extends over the entire surface that is limited by the inner periphery of the lateral engaging edge, and therefore over the complete outlet side of the capsule. Experiments have shown that the controlled tearing of the film can best be achieved if the pattern is composed of a plurality of broken lines (dashed lines) essentially oriented in parallel. The perforations configured in succession forming a continuous line segment are preferably designed in an elongated manner, and it is particularly preferred if they are essentially rectangular. Such a design facilitates tearing of the film, wherein the film is to tear at the sites of the lines, with the lines determining the de facto location of the tearing seams. This facilitates controlled tearing of the film. Alternative tearing patterns can for example be achieved by forming of cross-shaped and/or square weakened areas. A rectangular weakened area is also preferred to a rounded weakened area, as an angled weakened area will allow the carrier layer in question to tear more quickly.
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[0008] Preferably, at least one weakened carrier layer faces toward the substance held in the housing. This weakened carrier layer is the first layer to be exposed to pressure build-up in the capsule. Because of the applied weakening, this (innermost) layer is also the first layer that can tear on pressure build-up in the capsule during injection of water into the capsule (generally via the end side of the housing), with the result that the beverage can be displaced through this innermost layer. As the layers of the film are preferably integrally connected to one another, thus forming a composite, tearing of the innermost layer will fairly quickly lead to tearing of the other layers according to the same tearing pattern. Integral binding of the film layers to one another can be carried out by welding/melting the various film layers together and/or by gluing the film layers together. Under the effect of the pressure build-up in the capsule, the closing element is deformed and finally undergoes
controlled tearing during interaction of the deformed film with a perforation structure of a device for preparing beverages such as a coffee machine. At higher temperatures of between 90 and 100 °C, which are generally applied in extracting and/or dissolving the substance, it is specifically the oxygen barrier layer that tends to tear out and form around and/or over the perforation structure of the coffee machine instead of tearing and/or being perforated. By connecting the oxygen barrier layer to the at least one weakened carrier layer, one can force controlled rupturing of the oxygen barrier layer to occur, which facilitates the preparation process of the beverage.
[0009] The film is essentially fully compostable. As the capsule is manufactured from one of a plurality of (biologically) compostable materials, the capsule is to be discarded after use, preferably in VFG waste (vegetable, fruit, and garden waste), after which the capsule is biodegraded on the molecular level by micro-organisms, if applicable after application of activation heat and moisture (water). In this case, it is also preferred to manufacture the capsule components from biomaterials ("bio based materials"), which are materials originating from living or formerly living organisms, as this further increases the durability of the capsule and further reduces environmental pollution. In this process, organic molecules, of which the capsule is essentially composed, are converted into smaller organic molecules, and finally into water, carbon dioxide, and biomass (humus), and possible mineral components such as salts. In industrial composting facilities, the entire composting process generally requires several weeks. This type of composting process is also referred to as biodegradation. Manufacturing of all of the components of the capsule from fully compostable materials provides a considerable benefit with respect to environmental pollution. This provides a solution in the ongoing efforts to keep the discharge of waste to a manageable level and deal responsibly with residual waste. In addition to the reduction in environmental pollution accompanying use of the capsule according to the invention, the essentially closed capsule is extremely well-suited for allowing the substance, generally coffee, to be preserved for long periods of time by using an oxygen barrier, preferably in both the housing and the closing element. For this reason, no separate packaging is required in order to maintain the quality of the substance, specifically coffee.
The oxygen barrier layer is preferably at least partially manufactured from a material selected from the group composed of polyvinyl alcohol (PVOH), polyvinylpyrrolidone (PVP), and polyvinyl acetate (PVAc). PVOH is generally the most preferred of these substances, as PVOH can be fairly easily applied as a sealed oxygen-impermeable film and has favourable adhesion properties. The oxygen barrier layer is preferably composed of a hybrid coating of an organic phase, for example by application of at least one of the aforementioned components, and an inorganic fraction that functions as a precursor. More preferably, the inorganic fraction is composed of silicon alkoxide (Si(OR)4), wherein R denotes an organic tail derived from one of the aforementioned organic molecules. Such hybrid coatings generally show particularly favourable composting properties, and also possess satisfactory impermeability to oxygen. As a less environmentally-friendly alternative, the oxygen barrier layer may also be composed of, for example, polyvinylidene chloride (PVdC), ethene vinyl alcohol (EVOH), or a metal oxide such as SiO2 or Al2O3.
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[0015] Preferably, the housing is composed of a laminate of a plurality of material layers. In this case, each material layer should preferably be essentially compostable. By applying a laminate of material layers, it is possible to efficiently provide the housing with the desired properties. For example, at least one material layer may form a barrier layer against oxygen and/or water (vapour). One may use e.g. a plurality of synthetic or natural polymers such as nitrocellulose, polysaccharides such as hydroxyethylcellulose, polyvinyl alcohol (PVOH), or ethylene vinyl alcohol (EVOH), polylactic acid (PLA), polyvinylidene chloride (PVDC), chitosan, carboxymethylcellulose, polyacrylate, polyglycolide, polybutylene succinate (PBS), acrylonitrile-butadiene-styrene (ABS), polyolefins, polyester, co-polyesters, polyamide, PLA/caprolactone copolymers, polyhydroxyalkanoates, biodegradable polyethylene (PE), polypropylene (PP), polybutene (PB) and copolymers and mixtures thereof, optionally mixed with starch. A barrier layer for oxygen comprising a plurality of synthetic or natural polymers may further include a crosslinker such as silane, glyoxal, melamine resin, and the like. This barrier layer for oxygen is preferably composed of compostable material, and natural polymers such as starch and chitosan and synthetic polymers such as PVOH, EVOH, and PLA are therefore preferred. In one embodiment, the material layer also comprises a wax and/or a filler, such as clay, which further strengthens the barrier function. Where applicable, the polymer is dispersed or dissolved in an aqueous or other solvent-based medium, with said medium containing inorganic particles. Such inorganic particles are preferably composed of inorganic layered or plate-like particles containing natural or synthetic clay minerals such as mica, kaolinite, vermiculite, halloysite, montmorillonite, and the like. Where applicable, a metallised film may also be used as an oxygen barrier and/or a water (vapour) barrier in the housing. For this purpose, an aluminium coating is preferably applied to a preformed material layer of the laminate. It is also conceivable to use a plurality of oxygen barriers, which can optionally be applied on top of one another. For example, it is conceivable to coat a PVOH layer with an aluminium coating. In this manner, a multiple oxygen barrier is produced. A further material layer of the laminate can optionally function as a shielding coating and/or a coloured layer in order to impart a desired colour to the housing of the capsule. An example of such a layer is composed of a compostable polymer selected from the group composed of compostable polyesters, PLA, polyhydroxyalkanoates, polycaprolactones, polybutylene succinate adipate, polybutylene adipate co-terephthalate, PLA/caprolactone co-polymers, biodegradable polyethylene, and nitrocellulose.