Easy-perforation polypropylene MONO-material film for capsules

Abstract

The multilayer film for the sealing of a capsule for making beverages according to the present invention comprises : an outer layer (10) made of polypropylene with gas and / or vapor barrier properties; an inner layer (20) intended to come into contact with said capsule to be sealed, said inner layer (20) being a micro-perforated film provided with a plurality of through holes (201); a joining layer (30) between the inner layer (20) and the outer layer (10), wherein said joining layer (30) is integral with the outer layer (10) and is detachable from the inner layer (20). Advantageously, such a film may be easily and correctly perforated and, at the same time, recyclable in the plastics section of household waste.

Description

"EASY -PERFORATION POLYPROPYLENE MONO-MATERIAL FILM FORCAPSULES" DESCRIPTION

[0001] The present invention relates to a multilayer, easy- perforation, polypropylene mono-material film for making a capsule for the preparation of infusion or soluble beverages. The object of the invention is also a polypropylene mono-material capsule, provided with an outer lid (top lid) made of such a film.

[0002] In the sector, capsules are known for the packaging of concentrated products (for example in the form of powder, granules or leaves) in predetermined, single-use doses, for the impromptu preparation of beverages (such as tea, coffee, herbal teas, milk, chocolate, etc.) by means of the introduction, into said capsule, of a pressurized fluid (mostly hot water) . Said flow of hot water, delivered by an extraction machine, passes through the essence to be infused or dissolved contained inside the capsule, which results in the impromptu preparation of the beverage.

[0003] Different types of automatic or semi-automatic beverage preparation machines are known in the industry. One type of machine provides for the perforation of the capsule on both sides, in order to allow the pressurized fluid to be injected into the cup on one side, and thebeverage to flow out from the opposite side . This type of machine is intended for capsules comprising a cup that is closed on both sides , respectively by a bottom and a lid . In such applications , the high temperature and high pressure extraction water enters the bottom o f the capsule and flows out from the lid, which opens by perforating itsel f at various points against an appropriate element of the extraction machine . The extraction device of the dispensing machine in fact comprises a plurality of piercing elements that engage with the lid and perforate it at a plurality of dif ferent zones when the pressure of the liquid inside the capsule increases . The final product may flow into the final container through the perforations produced by the extraction device of the dispens ing machine . It follows that for the dispensing to be success ful , the piercing elements need to correctly perforate the lid element and the resulting perforations need to remain open during the entire dispensing of the final product .

[0004] The structure of the lid, which is generally multilayer, must therefore firstly allow for the correct opening and subsequently the correct emergence of the product . In the case of the lids , the multilayer is applied to the edge of the capsule body filled with a food product ( in powder or granular form) by means ofheat welding or similar techniques. The choice of film used to make the lid of the capsule is particularly difficult insofar as such a film has to be easy to perforate, easy to fasten to the flange edge of the capsule, for example by means of welding, and ensure the airtightness of the cavity closure. An example of a known multilayer lid is described in the document US 2019 / 0055070 Al. Such a lid is a laminate of three layers: an inner heat-sealable layer; a second brittle layer; a third layer, half of the circumference thereof being firmly fixed to the second layer, the remaining half of the circumference being separated from the second layer in such a way as to create a tab that allows the user to remove, by tearing it off, the entire lid from the cup to allow the capsule to be emptied at the end of dispensing .

[0005] Known multilayer films comprise at least one outer barrier layer and an inner filter (made of paper or nonwoven fabric) joined together by means of an adhesive. An example of a known multilayer film is described in the document EP 3 362 377 Bl. Such a film is a laminate of three layers: an inner layer made of polylactic acid (PLA) or compostable polypropylene (PP) ; a second layer, which is a barrier against oxygen, e.g., PVOH; a third layer made of filter paper. The three layers are firmlyj oined together by means of an adhesive .

[0006] Such structures have some disadvantages . It has been noted that dispensing may be interrupted after a few seconds without completion of the dispensing and even that the dispensing machine may become blocked . The reason for this has been identi fied by the fact that , after the first perforations , the pressure of the fluid within the capsule reduces and such a reduced pressure does not allow the multilayer film to be perforated any further . Under these conditions the paper or non-woven fabric inner layer, stressed by the pressure ins ide the capsule , tends to insert itself into the perforations generated in the multilayer film and to obstruct them, thereby interrupting the dispensing of the final product . The dispensing of the final product is therefore compromised and, simultaneously, a loss of liquid from the housing whereinto the capsule is inserted is observed . Known structures with a paper or non-woven fabric inner layer therefore have numerous disadvantages : - the pores of the non-woven fabric NWF layer are meshes that may stretch under the momentum of the high-pressure liquid, thereby allowing the food product in powder form ( for example co f fee ) to infiltrate into the meshes themselves , ef fectively clogging the system and affecting the proper functioning thereof and thus preventing properdispensing; the non-woven fabric NWF is a non-uni form porous material , wherein the pores have a totally random distribution . Since the NWM also represents the layer that welds with the capsule , this non-uni form distribution of the pores renders the zone that welds with the capsule body uneven, thereby leading to uneven weldability profiles .

[0007] Furthermore , in known structures , the outer barrier layer is generally a standard multilayer, such as PET- PETALOX-PP, PET-PET-PP, PET-PET-PE or similar . As is evident , such multi-material structures are not recyclable , resulting in environmental impacts .

[0008] The obj ect of this invention is to provide a film for making the l id of a capsule that solves the problems of the prior art while taking into account the needs of the industry .

[0009] In particular, the obj ect of the present invention is to provide a multilayer film for the manufacture of the lid of a capsule that is easily and correctly perforated and, at the same time , recyclable in the plastics section of household waste .

[0010] The obj ect of the present invention is also to provide a capsule made from such a film, which ensures the correct extraction of the beverage and which may berecycled into the plastics section of household waste .

[0011] This obj ect is achieved by a film according to claim 1 and by a capsule according to claim 9 . The dependent claims describe preferred embodiments of the invention .

[0012] The features and the advantages of the invention will appear more clearly from the following description, made by way of an indicative and non-limiting example with reference to the accompanying figures , wherein :- Figures 1 and 2 show, respectively, a lateral view and an axonometric view of a capsule for making infusion or soluble beverages , provided with a lid according to the present invention;- Figures 3a to 3c show, in a lateral view, the steps of opening the capsule for the extraction of the beverage ;- Figures 4a to 4c show, in an axonometric view, the steps of opening the capsule for the extraction of the beverage .

[0013] With reference to the attached figures , a capsule for the preparation of infusion or soluble beverages is shown, indicated by the reference number 1 .

[0014] The capsule 1 comprises a cup-shaped body 2 suitable for defining an inner volume V wherein at least one substance to be infused or dis solved is typical ly contained in powder or granular form .

[0015] The cup-shaped body 2 is provided, on one side , with a bottom 3 and, on the opposite side , with an opening defined by an externally proj ecting edge 4 . The capsule 1 comprises a lid 6 fastened to the edge 4 for sealing the capsule . In one usage example of the capsule , the high temperature and high pressure extracted water enters the base 3 of the cup-shaped body 2 and emerges from the lid 6 which opens by perforating itsel f at various points against an appropriate element of the extraction machine .

[0016] The film comprises an outer layer 10 and an inner layer 20 intended to come into contact with the cup to seal the capsule 1 , j oined together in a yielding manner by means of a j oining layer 30 .

[0017] The outer layer 10 is a gas , light and vapor barrier layer . For example , it has barrier properties against oxygen, humidity, water, fats , aromas and light . Such properties may alternatively derive from process ing that does not include surface treatments , or else from surface treatments , such as for example metal lization .

[0018] The outer layer 10 is a brittle fi lm, that is to say with appropriate brittleness characteristics , capable of appropriately fracturing itsel f against the perforating elements of the dispensing machine . The brittleness is to be understood, for example , as the least possible elongation following breakage and perforation on the partof the perforating elements of the dispensing machine.

[0019] The outer layer 10 preferably has a uniform thickness of between 10 pm and 90 pm.

[0020] The outer layer 10 is made of polypropylene with barrier properties, preferably metallized.

[0021] The inner layer 20 is a micro-perforated film. In other words, the inner layer 20 is provided with a plurality of through holes 201.

[0022] Preferably, the texture of the micro-holes of the inner layer 20 is optimized so as to ensure the best lid properties. Preferably, the diameter of the micro-holes 201 is between 0.1 mm and 1.0 mm, and even more preferably between 0.3 mm and 0.8 mm. Preferably, said density of micro-holes is between 5 and 25 micro- holes / cm2, even more preferably between 8 and 20 microholes / cm2.

[0023] The micro-perforated inner layer 20 is made of a plastics material that is chemically similar and weldable to the edge 4 of the cup-shaped body 2 of the capsule. The inner layer 20 is made of polypropylene.

[0024] In an example, the inner layer 20 also has barrier properties against gas, light and vapor. For example, it has barrier properties against oxygen, humidity, water, fats, aromas and light. In such an example, the outer layer 10 is made of polypropylene, preferably metallized.

[0025] In one embodiment , the j oining layer 30 is made of a polymer material and is applied in a particular manner to the inner layer 20 in such a way that said inner layer 20 is at least partially incorporated into the intermediate layer 30 . The j oining layer 30 is cast , whilst stil l hot , onto the micro-perforated inner layer 20 , in such a way as to fill the micro-holes 201 . The j oining layer 30 is made of a plastics material that is chemically similar and weldable to the edge 4 of the cup-shaped body 2 of the capsule . Preferably, the j oining layer 30 is made of a plastics material that is chemically similar and weldable also to the outer layer 10 and to the inner layer 20 . The j oining layer 30 is made of polypropylene ( PP ) or another polymer similar to polypropylene .

[0026] Preferably, the j oining layer 30 is loaded with additives which promote the peelability thereof and possibly loaded with polymers that promote the brittleness thereof . Suitable additives for ensuring peelability include polyethylene ( PE ) and polypropylene ( PP ) , and more generally other polyolefins ( PO) such as polybutadiene ( PB ) . The aim of such additives is that of making it possible to peel the polymer away from the inner layer 20 under certain conditions of temperature and pressure within the capsule 1 during the extraction step of the beverage .

[0027] In one exemplary embodiment , the j oining layer 30 i s an adhesive . In such an exemplary embodiment it is possible to obtain the formation of one or more thrust chambers taking advantage of in-register lamination, that is , spreading the adhesive only in certain areas of the laminate , thereby creating zones of variable adhesion by means of variable geometry configurations . Alternatively, zones of variable adhesion may be obtained by means of the depositing of signi ficantly varying values of weight , in such a way as to create a peelable ef fect .

[0028] In the present discussion, the level of adhesion is measured by means of a measurement method that is considered standard for the flexible packaging industry . The reference method is ASTM F904 . It should be noted that there is no di f ference in the retaining method of the specimen ( free or 90 ° ) .

[0029] The adhesion between the micro-perforated inner layer 20 and the j oining layer 30 is suf ficiently high to keep the laminated multilayer film j oined during the actual lamination step and during the subsequent steps of transportation and handling up and until the production of the capsule . At the same time , such adhesion is suf ficiently low to allow for delamination between the micro-perforated inner layer 20 and the j oining layer 30 under certain conditions of temperature and pressureduring the dispensing step. Following the lamination step, such adhesion is low and has values between 0.10 and 5.00 N / 15mm, preferably between 0.25 and 5.00 N / 15mm, even more preferably between 0.50 and 1.50 N / 15mm.

[0030] The laminated multilayer film therefore has, for all intents and purposes, features of peelability between the micro-perforated inner layer 20 and the joining layer 30.

[0031] During the capsule 1 packaging step, and in particular during the step of welding the lid 6, implemented with the laminated multilayer film according to the present invention, onto the edge 4 of the capsule 1, as a result of the action of heat sources, and exploiting the mutual chemical affinity thereof, the adhesion between the micro-perforated inner layer 20 and the joining layer 30 is increased only in some zones of the lid, for example by means of the use of appropriate welding bars. Following such a welding action, this adhesion is elevated and has values that are greater than 1.50 N / 15mm, preferentially greater than 5.00 N / 15mm, only within those zones that are subject to welding, whereupon the welding bars have acted.

[0032] The lid 6 therefore has zones with a different level of adhesion between the micro-perforated inner layer 20 and the joining layer 30. In particular, the lid 6 has a high level of adhesion at least at the outer perimetercorresponding to the welding zone with the edge 4 of the cup-shaped body 2 and a low level of adhesion in the remaining part of the lid 6 , for example within the central zone .

[0033] In other words , the lid 6 has at least one low adhesion level zone between the micro-perforated inner layer 20 and the j oining layer 30 , and therefore a delamination zone at the central zone 203 .

[0034] In a further exemplary embodiment , the lid 6 has a grid with a high level of adhesion at the central zone 203 , which defines a plurality of low adhesion level zones between the micro-perforated inner layer 20 and the j oining layer 30 .

[0035] During the extraction step of the capsule 1 in the extraction machine , the action of the pressure of the hot liquid within the cup-shaped body 2 causes separation, that is to say delamination, of the inner layer 20 from the j oining layer 30 within the low adhesion zones only . Given that the perforation of the lid 6 , and in particular the tearing thereof against the appropriate perforating elements of the dispensing machine , occurs in a moment in time after the entry of the extraction liquid through the bottom 4 of the capsule 1 , at least one thrust chamber 205 is formed between the inner layer 20 and the j oining layer 30 . The extraction liquidaccumulates within such a thrust chamber 205 for a fraction of a second, thereby generating a push towards the outside of the remaining layers of the laminated multilayer film, at least of the outer layer 10 , layers that are pushed so as to tear against the perforating elements of the dispensing machine . A plurality of beverage outlet openings 206 is thus easily and correctly formed within the outer layer 10 . Such a solution ensures the correct opening of the capsule 1 and the correct dispensing of the beverage . By virtue of the presence of the micro-perforated inner layer 20 , interposed between the food substance contained within the cup-shaped body 2 and the outer layer 10 , the final product passes through the micro-perforated layer before intercepting the outer layer 10 and the pressure of the final product i s thus evenly distributed over the outer layer 10 ensuring that it is perforated evenly . Furthermore , by virtue of fact that the micro-perforated inner layer 20 separates itsel f from the outer layer 10 , the perforations within such outer layer 10 are not blocked in any way .

[0036] On the other hand, the high adhesion level zones are not af fected by the delamination and within such high adhesion level zones the inner layer 20 and the j oining layer 30 remain firmly j oined together . In fact , the polymer that is used to make the j oining layer 30 iscast , whilst sti ll hot , onto the micro-perforated inner layer 20 , penetrates through the micro-holes 201 and fills them, and the inner layer 20 is at least partial ly incorporated within the polymer of the j oining layer 30 . This j oining layer 30 therefore forms a welding material thickness that i s ideal for ensuring the weldability of the lid 6 to the flange , or edge 4 , of the cup-shaped body 2 of the capsule 1 .

[0037] Furthermore , delamination does not occur between the j oining layer 30 and the outer layer which remain firmly j oined together .

[0038] In one exemplary embodiment the polymer material of the j oining layer 30 is loaded, that is , supplemented, with appropriate embrittlement additives that render it fit for purpose . The obj ect of such additives is that of rendering the polymer brittle to the right degree depending upon the piercing system that is included in the dispensing machine . All of the constituents of such a layer, and therefore the polymer matrix with the addition of embrittlement additives , are found to be suitable for coming into contact with foodstuf fs . Preferably, the final weight of such a layer, composed of a polymer and embrittlement additives , is between 4 g / m2 and 40 g / m2 , preferably between 10 g / m2 and 25 g / m2 .

[0039] In some particular cases and for particularrequirements the multilayer laminated film comprises a further outer covering 40. For example, the further coating 40 comprises a polypropylene film joined to the inner layer 10 by means of an extruded polypropylene- based polymer layer PP, or by means of an adhesive.

[0040] The multilayer film according to the present invention is a mono-material film and is made of at least 80% polypropylene, preferably at least 85% polypropylene, even more preferably at least 90% polypropylene.

[0041] Two embodiments of a lid according to the present invention will now be described.

[0042] EXAMPLE A)- outer layer 10: Bi-oriented, metallized (on the inner side of the multilayer) polypropylene, total thickness 16 micron; joining layer 30: in-line extruded polypropylene, lOg / sqm, supplemented with polyethylene with a mineral filler (for example talc) ;- inner layer 20: bi-oriented polypropylene, 20 micron thick, micro-perforated with 0.5 micron diameter holes.

[0043] EXAMPLE B)- outer layer 10: Bi-oriented, metallized (inner side of the multilayer) polypropylene, total thickness 12 micron;- bonding layer 30: in-line extruded polyethylene, from lOg / sqm, supplemented with polyethylene with a mineralfiller (e.g. talc) ;- inner layer 20: bi-oriented polypropylene, 30 micron thick, micro-perforated with 0.5 micron diameter holes.

[0044] The object of the present invention is also a capsule 1 for pressure-extractable beverages, comprising a cup-shaped body 2 closed by a sealing lid as described above .

[0045] The capsule comprising a cup-shaped body 2 made of polypropylene that defines an inner volume in which at least one food substance to be infused or dissolved is contained. The cup-shaped body 2 is closed by a lid 6 made with the film described above, i.e. comprising an outer layer 10 made of polypropylene and an inner microperforated layer 20 made of polypropylene joined together by a joining layer 30. In particular, in the lid 6, the joining layer 30 is: integral with the outer layer 10, integral with the inner layer 20 at the outer perimeter 204 corresponding to the welding zone with the edge 4 of the cup-shaped body 2, and detachable from the inner layer 20 in a central zone 203.

[0046] The capsule, object of the present invention, is therefore a mono-material and made of polypropylene.

[0047] In one example, the capsule is for the preparation of soluble beverages, and therefore soluble powder is housed inside the cup. In this example, at the end ofdispensing, the capsule is empty because the soluble powder of is dissolved to form the beverage , and the capsule may be directly recyclable in the plastics section of household waste .

[0048] In one example , the capsule is for making espres so cof fee , and therefore an insoluble powder is housed inside the cup . In this example , at the end of the dispensing, the cof fee grounds are located inside the cup . Once these cof fee grounds have been removed, the capsule may be directly recyclable in the plastics section of household waste .

[0049] Innovatively, a film for the lid of a capsule for the preparation of infusion or soluble beverages according to the present invention is easily and correctly perforated and, at the same time , recyclable in the plastics section of household waste .

[0050] The laminated multilayer film according to the present invention is devoid of known structural defects , and has many advantages :- the micro-holes of the micro-perforated layer do not widen and do not risk being clogged with powdered food product ;- the micro-perforated layer is not impregnated with the beverage and does not compromise the correct di spensing of the beverage ;the micro-holes are uni formly distributed within the micro-perforated layer ensuring a uni form welding zone with the edge of the capsule body leading to uni form weldability profiles ; the laminate as a whole has barrier properties , obtained for example by metalli zation ;- the outer layer 10 is made of a brittle material so as to be able to tear itsel f against appropriate perforating elements that are found within the dispensing machine , thereby favoring the dispensing of the beverage itsel f .- the laminate as a whole , as well as the capsule in its entirety, is recyclable in the plastics section of household waste according to the usual regulations in force .

[0051] It is understood that a person skilled in the art could make modi fications to the capsule for the preparation of infusion or soluble beverages described above , all of which are contained within the scope of protection as defined by the following claims .

Claims

CLAIMS1. A multilayer film for sealing a capsule for preparing beverages, comprising: an outer layer (10) made of polypropylene with gas and / or vapor barrier properties;- an inner layer (20) intended to come into contact with said capsule to be sealed, said inner layer (20) being a micro-perforated film made of polypropylene and provided with a plurality of through holes (201) ;- a joining layer (30) between the inner layer (20) and the outer layer (10) , wherein said joining layer (30) is integral with the outer layer (10) and is detachable from the inner layer (20) .

2. A multilayer film according to claim 1, wherein the inner layer (20) and the outer layer (10) are joined to each other by means of said joining layer (30) with adhesion values between 0.10 and 5.00 N / 15mm (ASTM F904 method) .

3. A multilayer film according to claim 2, wherein the inner layer (20) and the outer layer (10) are joined to each other by means of said joining layer (30) with adhesion values between 0.25 and 5.00 N / 15mm (ASTM F904 method) .

4. A multilayer film according to claim 2 or 3, wherein said adhesion values are between 0.50 and 1.50 N / 15mm(ASTM F904 method) .

5. A multilayer film according to any one of the preceding claims, wherein the diameter of the micro-holes (201) of the micro-perforated inner layer (20) is between 0.1 mm and 1.0 mm, and even more preferably between 0.3 mm and 0.8 mm.

6. A multilayer film according to any one of the preceding claims, wherein the density of the micro-holes (201) of the micro-perforated inner layer (20) is between 5 and 25 micro-holes / cm2 , even more preferably between 8 and 20 micro-holes / cm2.

7. A multilayer film according to any one of the preceding claims, wherein the joining layer (30) is made of polypropylene.

8. A multilayer film according to any one of claims 1 to 6, wherein the joining layer (30) is an adhesive.

9. A multilayer film according to any one of the preceding claims, made of at least 80% polypropylene, preferably at least 85% polypropylene, even more preferably at least 90% polypropylene.

10. A capsule (1) for pressure extractable beverages, comprising a cup-shaped body (2) made of polypropylene, wherein said cup-shaped body (2) defines an inner volume in which at least one food substance to be infused or dissolved is contained, and wherein said cup-shaped body(2) is closed by a lid (6) made from the film according to any one of the preceding claims; characterized in that, in the lid (6) , the joining layer (30) is: - integral with the outer layer (10) ; integral with the inner layer (20) at an outer perimeter (204) corresponding to the welding area with an edge (4) of the cup-shaped body (2) ;- detachable from the inner layer (20) in a central area (203) .

11. A capsule (1) according to claim 10, wherein said food substance is a soluble substance.

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