EP2776336B1

EP2776336B1 - Container for food products

Info

Publication number: EP2776336B1
Application number: EP12731651.1A
Authority: EP
Inventors: Arne MOHN; Pier Luigi LOCCHI
Original assignee: Ipi SRL
Current assignee: Ipi SRL
Priority date: 2011-11-11
Filing date: 2012-05-11
Publication date: 2017-07-19
Anticipated expiration: 2032-05-11
Also published as: WO2013068797A1; RU2628966C2; CN104024124B; CN104024124A; EP2776336A1; RU2014123674A; ITMI20112054A1

Description

FIELD OF THE INVENTION

The present invention relates to a container.
In particular, such a container, of the type comprising a laminate provided with at least one paper layer and one aluminium layer, is used for containing high density food products, such as puddings, homogenized fruit or the like, etc, to be consumed, preferably, directly from the container.

KNOWN PREVIOUS ART

Such high density food products, usually, are packaged in glass or plastic containers, generally having the shape of pot, or tub, provided with an upper opening relatively large in size to allow a spoon or tea spoon to be introduced within the container, and with a screwed plastic lid or a tab welded to the edges of the opening of the container itself.
Next, for emptying the container, once the lid, or the tab, has been removed, a spoon, or tea spoon, is used, which because of the size of the opening, can deeply enter to collect the food product lying on the bottom of the container. All along the manufacturers of containers comprising a laminated layer provided with at least one paper layer and an aluminium layer advised against using such a kind of containers for containing highly dense food products since it is known that is very difficult to realize such a container which is provided with an upper perforated portion, i.e. located on the upper base, dimensioned so to receive a spoon to empty the container itself and in the meanwhile ensuring the sterility of the product and a suitable structural strength of the container. In fact, concerning this last aspect, when the perforated portion increases, which is made of the paper, or cardboard, layer, the stiffness offered by the container decreases significantly. Also by lowering the container such that the base and the bottom are wider, to obtain a larger opening portion, and consequently by reducing the height, the closing of the container itself would present problems because the triangle folding would be difficult to realize with enormous and unaffordable costs. Moreover, a further drawback in the use of laminates for such containers is that the opening of the container is not easy at all because the layers composing the laminate are rather tenacious and resistant and they are prone to delamination problems, that is the detachment between two or more adjoining layers forming the container.
EP - A1-1939 094 discloses a method for making a container in a multilayer material 1 for pourable products having at least one breakable portion suitable for being removed before pouring said pourable product out of said container.
Therefore, object of the present invention is to realize a container for food products, in particular of the type comprising at least one laminate, allowing a user to consume the product directly from the container.
Further object of the present invention is to realize a container which is simple to produce and is not provided with only a suitable structural stiffness, but also it guarantees significantly to preserve the sterility of the food product contained thereon.
These objects are reached by the present container for pourable products, comprising a laminate of the type provided with at least one layer made of paper or cardboard, having at least one perforated portion, and with at least one aluminium layer directly or indirectly applied to the inside of said at least one paper or cardboard layer, and means for opening said container at least at said at least one perforated portion, characterized in that said at least one paper or cardboard layer has at least two discrete pre-weakening lines extending from said at least one perforated portion of said at least one paper or cardboard layer, and in that said means for opening the container comprises at least one tab provided with at least one grip graspable from outside, and with at least one constraining portion comprising at least one first region which is directly or indirectly constrained to at least part of said at least one aluminium layer at said at least one perforated portion, said at least one grip portion being adapted for lifting said at least one aluminium layer at said at least one first region and said at least one paper or cardboard layer between said at least two pre-weakening lines under the action of an external force.
In practice, such a solution allows the user to take advantage of a large opening that therefore allows the introduction of a spoon, or similar tools, to collect the food product contained in the container. In fact, the tab, when pulled, drags with it both part of the aluminium layer on which the first region is constrained, also only indirectly, and part of the paper, or cardboard, layer between said two pre-weakening lines, this allows to use the container as if it was a jar and allows the user to consume the food product directly from the container since it provides a large opening, made in part of the perforated portion, obtained by rising the above said layers, through which a spoon or tea spoon for collecting the food product contained in the container is to be introduced. This is also aided by the food product contained in the container being dense and, therefore, during the dragging of said tab, also when such action is made forcefully, the container does not collapses due to the side pressure exerted by the hand of the user on the container itself. Therefore, the food product does not spatter outwardly during the opening of the container, but it remains well fixed therein.
Still according to the invention, said at least one first region substantially delimits the edge of said perforated portion comprised between said at least two pre-weakening lines. Thereby, when a force is exerted on the grip portion, this is discharged on the two end sides of the first region and, therefore, at the two pre-weakening lines, significantly facilitating the rising of the paper, or cardboard, layer comprised between said two pre-weakening lines.
Again, according to a preferred embodiment of the invention, said at least one constraining portion comprises, as well, at least one second region directly or indirectly constrained to at least part of said at least one paper or cardboard layer between said at least two pre-weakening lines, wherein said at least one first region and said at least one second region are continuously connected to each other. Thereby, the force exerted by the user on the grip portion is transmitted and distributed both on the first region and the second region and therefrom to the surfaces wherein said first and said region are constrained. This significantly aids and facilitates the opening of the container.
Further, said at least one first region and/or said at least one second region, as well as preferably said at least one perforated portion, extend widthwise substantially between said at least two pre-weakening lines.
Further, said opening means comprise, as well, at least one cutter to sever at least partially, outside of said at least one first region, said at least one aluminium layer arranged at said perforated portion of said at least one paper, or cardboard, layer, on the opposite side of the above said edge of said perforated portion comprised between said at least two pre-weakening lines. In practice, to facilitate the opening of the container, in a step preceding the step of exerting a force on the grip portion of the tab, the user severs the aluminium layer located at the perforated portion by the use of a cutter which, preferably, comprises a spoon - shaped portion. Therefore the cutter is also employed to collect the food product contained in the container.
In accordance with an alternative embodiment of the invention, said at least one tab and said at least one cutter are made in a single piece and that said at least one cutter and said at least one grip portion are rotatable with respect to said at least one constraining portion such that said at least one cutter at least partially severs, outwardly from said at least one first region, said at least one aluminium layer arranged at said perforated portion of said at least one paper, or cardboard, layer.
Still according to said embodiment, said at least one cutter and said at least one tab are made of plastic material, and preferably, by molding. Note that, in this case, the cutter, preferably provided with a plurality of teeth, has a curved shape and it extends for most of the length comprised between said two pre-weakening lines. Moreover, said at least one cutter and said at least one grip portion rotate with respect to said constraining portion, integral with the container, around a plastically deformable hinge.
Still more in detail said at least two pre-weakening lines are straight and, preferably, one parallel to another. Also, each of said at least two pre-weakening lines has one or more "T"-, "L"- or "I"- or "C" -shaped orthogonal branches. In this way the lifting of the paper or cardboard layer is significantly simplified and the integrity of the cardboard is preserved, particularly of the aluminium layer, during all the production, packaging and delivering steps, up to the final user.
According to a further embodiment of the invention, each pre-weakening line is provided with at least one first plurality of herringbone branches and at least one second plurality of herringbone branches, tilted one with respect to another in an opposing way such that said at least one second plurality of herringbone branches aids to facilitate the rupture of said at least one first plurality of herringbone branches. In practice, the said at least one second plurality of herringbone branches is made so that the branches follow a weakening line intersecting the branches of said at least one first plurality of herringbone branches, to facilitate the rupture of the latter. In this way, as the paper layer lifts, the pre-weakening and branching lines are followed the user being unable to deviate from them. This allows avoiding the container to be severed along not pre-established lines and, thus, generating unwanted delamination of the material.
Still more in detail, said at least one perforated portion, preferably having a rectangular shape, is arranged on the front, or back side face, of said container so that it has even more surface for obtaining the opening through which the food product contained in the container is collected. Such a solution avoids the need of realizing containers ad hoc obtained by a wider upper and lower portion, but with a reduced height.
The above mentioned objects are also reached by a method for the realization of a container according to the claims from 1 to 17, comprising the steps of: a) forming at least one perforated portion on said at least one paper or cardboard layer; b) applying, either directly or indirectly, said at least one aluminium layer onto the inside of said at least one paper or cardboard layer; c) applying said at least one tab onto said at least one laminate at said at least one perforated portion; characterized in that said step a) includes the step of d) forming at least two discrete pre-weakening lines extending from said at least one perforated portion of said at least one paper or cardboard layer, and that said step c) includes the step of e) constraining, either directly or indirectly, said at least one first region of said at least one tab onto at least part of said at least one aluminium layer. Further, said step e) of the method includes the step of constraining, either directly or indirectly, said at least one second region of said at least one tab onto at least part of said at least one paper or cardboard layer between said at least two pre-weakening lines.
Lastly, the invention comprises a further method for opening of a container according to one of the claims from 1 to 17, comprising the steps of: at least partially severing said at least one aluminium layer from the side opposite said edge of said perforated portion and outwardly from said at least one first region, by means of said at least one cutter; dragging said at least one tab in the direction of said at least first region; lifting both said at least one aluminium layer constrained to said at least one first region and said at least one paper or cardboard layer comprised between said at least two discrete pre-weakening lines.
Again, said severing step by said cutter is preceded by the step of rotating said tab around said plastically deformable hinge.

BRIEF DESCRIPTION OF THE DRAWINGS

For purposes of illustrations and not limitative, more particular preferred embodiments of the present invention will be now provided with reference to the accompanying figures, in which:

figures 1a, 1b, 1c are three perspective views of a container according to the invention in three different steps during the opening of the container;
figure 2 is a partial longitudinal sectional view of the container of figure 1a;
figures 3a, 3b and 3c are three perspective views of a container in accordance with a further embodiment of the invention in three different steps during the opening of the containers;
figure 4 is a partial longitudinal sectional view of the container of figure 3a;
figure 5 is a perspective view of an alternative embodiment of the opening means;
figure 6 is a sectional view of the opening means of figure 5;
figure 7 is a perspective view from bottom of the opening means of figure 5;
figure 8 is a top view of the container according to a particular shape of the pre-weakening lines;
figure 9 is a top view of the container according to a further embodiment of the pre-weakening lines;
figure 10 is a top view of the container according to a third embodiment of the pre-weakening lines.

DETAILED DESCRIPTION OF SOME EMBODIMENTS OF THE PRESENT INVENTION

Referring particularly to such figures, with numeral 1 is shown a container according to the invention.
Figure 1 shows a container 1 for high density pourable products 100 such as, for example, a pudding, comprising a laminate 2 provided with a paper layer 3, having a perforated portion 4, and with aluminium layer 5 indirectly internally applied to said paper layer 3. Further, said laminate 1 comprises an outer layer 20 made of thermoplastic material applied outside of said paper layer 3 and an intermediate layer 21 made of thermoplastic material applied between said paper layer 3 and said aluminium layer 5. Therefore, in practice, such an intermediate layer 21 is directly welded to said outside layer 20 at said perforated portion 4. Note that, although not described herein, a container comprising a laminate 2, further provided with a plurality of layers made of thermoplastic material or the like applied on the inner face of the aluminium layer, still falls within the scope of protection of the present invention.
Further, said container comprises means 6 for opening said container 1 at least at said perforated portion 4.
According to the invention, said paper layer 3 has two discrete pre-weakening lines 7, 8 extending from said perforated portion 4 of said paper layer 3. Further, said opening means 6 of the container 1 comprise a tab 9, totally in aluminium, provided with a grip portion 10, graspable by the user, and with a constraining portion 11 comprising a first region 12 indirectly constrained, at said perforated portion 4, on at least part of said aluminium layer 5. In practice, the tab 9 is welded, by heat - welding, on the outer layer 20, but at the end of the welding it remains substantially constrained both to the intermediate layer 21 and the aluminium layer 5, thus remaining firmly constrained to the latter.
According to the invention, therefore, said grip portion 10 is adapted to lift said paper layer 3 under the action of an external force exerted by the user, at said first region 12, said aluminium layer 5 and, between said at least two pre-weakening lines 7 and 8. In fact, once the aluminium layer 5 starts lifting, the cuts produced in said aluminium layer 5 propagate towards said paper layer 3 comprised between said two pre-weakening lines 7 and 8, thus causing it to lift said paper layer 3 comprised between said two pre-weakening lines too. In the meanwhile, the aluminium layer 5 arranged under the paper layer 3 keeps being cut along the direction of the two pre-weakening lines 7 and 8 such that an opening 200, much wider than the perforated portion 4 initially present in the container 1, before the opening step, can be obtained. According to the invention, as it will be more evident in the following description, the opening of the container 1 can be facilitated by severing at least part of said aluminium layer 5 by at least one cutter 75, at the available region 70 of said perforated portion 4 and from side opposite to said paper layer 3 comprised between said two pre-weakening lines 7 and 8. Still according to the invention, and as shown in figure 1, said first region 12 substantially delimits the edge 4a of said perforated portion 4 comprised between said at least two pre-weakening lines 7 and 8. Said first region 12 also extends in width L between said two pre-weakening lines 7 and 8. Said perforated portion 4 also extends in width L between said two pre-weakening lines 7 and 8. In view of what said, therefore, the above mentioned available region 70 is on the opposite side of the edge 4a of said perforated portion 4. In accordance with a further embodiment of the invention visible in figures 3 and 4, said constraining portion 11 comprises, as well, a second region 13 constrained between said two pre-weakening lines 7 and 8, indirectly on part of said paper layer 3. In practice said second region 13 of the tab 9 is welded on the outer layer 20, but at the end of the welding it remains substantially constrained to the paper layer 3 to the intermediate layer 21 made of thermoplastic material and to the underlying aluminium layer 5.
Said first region 12 and said second region 13 are continuously connected one to another forming a single body. Also, both said first region 12 and said second region 13 extend widthwise L substantially between said two pre-weakening lines 7 and 8.
In practice, in this way, when a force is exerted on the grip portion 10, this is released on the two end sides of the first region 12, and therefore, at the two pre-weakening lines 7 and 8, significantly facilitating the lifting of the paper layer 3 comprised between said two pre-weakening lines 7 and 8. In fact, the force exerted by the user on the grip portion 10 is transmitted and shared both on the first region 12 and on the second region 13 and from here to the surfaces to which said first 12 and said second 13 region are constrained. The Applicant tested that such a solution facilitates significantly the opening of the container 1 without creating delamination problems of the laminate and without the user having to use an excessive force to open the container. Both the embodiments herein shown provide the two pre-weakening lines 7 and 8 to be straight and parallel one to another, however an alternative embodiment, wherein said two pre-weakening lines are not parallel and not straight, still falls within the scope of protection of the present invention.
In accordance with an embodiment not shown here, both said pre-weakening lines 7 and 8 show a plurality of branches orthogonal with respect to the main direction, "T-shaped", or "L-shaped" or "I-shaped", or "C-shaped".
In accordance with an embodiment shown in figure 8, both pre-weakening lines 7, 8 are provided with a first plurality of herringbone branches 7a, 8a and with a second plurality of herringbone branches 7b, 8b, one opposing to another and such that said branches of said second plurality of herringbone branches 7b, 8b aid in facilitating the rupture of the branches of said first plurality of herringbone branches 7a, 8a. In practice, as can be also observed in figure 8, the branches of said second plurality of herringbone branches 7b, 8b are made so that to follow a weakening line which at a certain point intersects the branches of said first plurality of herringbone branches 7a, 8a. In this way, as the paper layer 3 lifts, the pre-weakening 7, 8 and branching 7a, 7b, 8a, 8b lines are followed, the user being unable to deviate from them. This allows avoiding the container to be severed along a not pre-established pattern and, thus, giving rise to unwanted delamination of the material. Further, as can be seen in figure 9, at the end 7c and 8c of said pre-weakening lines 7, 8, in a position opposite to the perforated portion 4 of said container 1, a further pre-weakening 300 line, or creasing, is comprised which connect said two pre-weakening lines 7, 8 and allows to completely remove the paper layer 3 lifted during the opening of the container 1. In accordance with an embodiment shown in figure 10 also said further pre-weakening lines 300 can have a shape similar to the shape of the pre-weakening lines 7, 8. In order to realize an opening of the paper layer 3 occurring along one tear direction only, said further pre-weakening line 300 has a "V" shape it and shows a further series of herringbone branches 300a. Further, as can be seen from the figures 1 and 3, said perforated portion 4 is arranged on the front side face 1 a of said container 1. In this way two advantages can be obtained. For one thing a greater area can be exploited, with respect to the area offered by the upper side 1 b of the container 1, and for another the depth of the container 1, when used by the user, is smaller than the area that would be available in case of opening obtained on the upper face 1 b. Also, still according to the invention, said perforated portion 4 has a substantially rectangular shape. In this way the dimensions of the perforated portion 4 larger than the classical circular dimensions are exploited.
Again, still according to both the embodiments shown here, said opening means 6 comprise, as well, a cutter 75 (see figures 1b and 3b) to sever, outside of said first region 12, from a side opposite to the edge 4a of said perforated portion 4, both said aluminium 5 layer and said outer layer 20 and said intermediate layer 21, each of these latter layers made of thermoplastic material such as, for example, LDPE, being arranged at said perforated portion 4 of said paper layer 3. In practice the severing occurs at the available region 70 of said perforated portion 4 (also denoted with solid line in figures 1b and 3b).
According to an embodiment herein not shown, said cutter 75 is integral with the grip portion of said tab 9. Further, said cutter 75 comprises a spoon - shaped portion such that this cutter 75 can be used as a collecting means also to collect the contents of the container.
In accordance with an alternative embodiment shown in figures 5, 6 and 7, said opening means 6, comprising a tab 9 and a cutter 75 integral one with another, are made of plastic material and made in a single piece, preferably, by molding. In practice, therefore, each of the grip portion 10 and the constraining portion 11 and the cutter 75 are obtained in a single piece.
Said cutter 75 and said grip portion 10 of the tab 9 are further rotatable with respect to the above mentioned constraining portion 11 of the tab 9 such that the cutter 75, provided with a plurality of teeth 76, severs at least partly, outside of said first region 12, therefore at the above mentioned available region 70, each of said aluminium layer 5 and said outer layer 20 and said intermediate layer 21, arranged at said perforated portion 4 of said paper layer 3. Further it has to be noted that the cutter 75, provided - as mentioned - with a plurality of teeth 76, has a curved shape and extends for most of the length comprised between said two pre-weakening lines 7 and 8. Further, said cutter 75 and said grip portion 10, integral one to another, rotate with respect to said constraining portion 11 around a plastically deformable hinge 77. Practically, by rotating the grip portion 10 the cutter 75 is rotated too, which, in turn, contacts at least the aluminium layer 5, severing it.
Always according to the invention, a method is described for realizing a container 1 according to one or more of the claims from 1 to 17. Specifically, such a method comprises the steps of: a) forming one perforated portion 4 on said paper or layer 3; b) applying, either directly or indirectly as in the case of the described embodiment, said aluminium layer 5 onto the inside of said paper layer 3; c) applying said tab 9 onto said laminate 2 at said perforated portion 4. Said step a) includes advantageously the step of d) forming at least two discrete pre-weakening lines 7, 8 extending from said perforated portion 4 of said paper layer 3 and said step c) includes the step of e) constraining, either directly or indirectly, said first region 12 of said tab 9 onto at least part of said aluminium layer 5, as in the case of the described embodiment. Such a solution allows obtaining a container 1 able to allow reaching the objects put forward by the invention.
Further, said step e) includes the step of constraining, either directly or indirectly (see figures 2 and 4), said second region 13 of said at tab 9 onto at least part of said paper layer 3, between said at least two pre-weakening lines 7 and 8. Again, said step b) is preceded by the step of f) applying an outer layer 20 made of a thermoplastic material to the outside of said at least one paper layer 3, and the step of g) applying an intermediate layer 21 made of a thermoplastic material to the inside of said paper layer 3 so as to weld said intermediate layer 3 directly to said outer layer 20 at said perforated portion 4.
Further, the invention allows obtaining a method for opening the container 1 according to one or more of the claims from 1 to 17. Such a method for opening the container 1 comprises the steps of:

at least partially severing said aluminium layer 5 from the side opposite said edge 4a of said perforated portion 4 and outwardly from said first region 12 (see figures 1b and 3b), i.e. at the available region 70 of said perforated portion 4, by means of said cutter 75;
dragging said tab 9, by grasping it at said grip portion 10, towards said first region 12, that is to say towards the edge 4a of said perforated portion comprised between said two pre-weakening lines 7 and 8: and ultimately
lifting both said aluminium layer 5 constrained to said first region 12 and said paper layer 3 comprised between said two discrete pre-weakening lines 7, 8.

Lastly, said severing step by said cutter 75 is preceded by the step of rotating said tab 9 around said plastically deformable hinge 76.

Claims

Container (1) for pourable products (100), comprising a laminate (2) provided with at least one layer (3) made of paper or cardboard having at least one perforated portion (4) and with at least one aluminium layer (5) directly or indirectly applied to the inside of said paper or cardboard layer, and means (6) for opening said container at least at said perforated portion (4) comprising at least one tab (9) provided with at least one grip portion (10) graspable from outside and with at least one constraining portion (11) comprising at least one first region (12) which is directly or indirectly constrained to at least part of said aluminium layer at said perforated portion, said grip portion being adapted for lifting said aluminium layer at said first region, characterized in that said paper or cardboard layer has at least two discrete pre-weakening lines (7, 8) extending from said perforated portion, said grip portion being adapted for lifting said paper or cardboard layer between said pre-weakening lines under the action of an external force.
Container according to claim 1, characterized in that said first region (12) substantially delimits the edge (4a) of said perforated portion (4) between said pre-weakening lines.
Container according to claim 1 or 2, characterized in that said constraining portion (11) comprises, as well, a second region (13) directly or indirectly constrained to at least part of said paper or cardboard layer (3) between said pre-weakening lines (7, 8), said first region (12) and said second region (13) being continuously connected to each other.
Container according to claim 1 or 2 or 3, characterized in that said first region (12) and/or said second region (13) extend widthwise (L) substantially between said at least two pre-weakening lines (7, 8).
Container according to one of claims 1 to 4, characterized in that said opening means (6) comprises, as well, at least one cutter (75) for at least partially severing said aluminium layer (5) arranged at said perforated portion (4) of said paper or cardboard layer (3) outwardly from said first region (12).
Container according to claim 5, characterized in that said cutter (75) is integral with said grip portion (10) of said tab (9).
Container according to one of the claims 1 to 6, characterized in that said tab (9) is made of aluminium.
Container according to claim 5 or 6 or 7, characterized in that said cutter (75) comprises a spoon shaped portion.
Container according to claim 6, characterized in that said tab (9) and said cutter (75) are made in a single piece and that said cutter (75) and said grip portion (10) are rotatable with respect to said constraining portion (11) such that said cutter at least partially severs, outwardly from said first region (12), said aluminium layer (5) arranged at said perforated portion (4) of said paper, or cardboard, layer (3).
Container according to claim 9, characterized in that said cutter (75) and said tab (9) are made of plastic.
Container according to one of the preceding claims, characterized in that said pre-weakening lines (7, 8) are straight.
Container according to one of the preceding claims, characterized in that said pre-weakening lines are parallel to each other.
Container according to claim 11 or 12, characterized in that each of said two pre-weakening lines has one or more "T"-, "L"- or "I"- or "C" -shaped orthogonal branches.
Container according to claim 11 or 12, characterized in that each of said pre-weakening lines (7; 8) is provided with at least one first plurality of herringbone branches (7a; 8a) and at least a second plurality of herringbone branches (7b, 8b), one opposite to another and such that said second plurality of herringbone branches (7b, 8b) follows a weakening line intersecting said first plurality of herringbone branches (7a; 8a), to facilitate the rupture of said first plurality of herringbone branches.
Container according to one of the preceding claims, characterized in that said perforated portion (4) is arranged on the front (1a) or rear side face of said container.
Container according to one of the preceding claims, characterized in that said laminate (2) further comprises at least one external layer (20) made of a thermoplastic material, applied to the outside of said paper or cardboard layer, and at least one intermediate layer (21) made of a thermoplastic material, applied between said paper or cardboard layer and said aluminium layer and welded directly to said external layer at said perforated portion (4), said tab (9) being welded directly to said external layer (20) made of a thermoplastic material.
Method for producing a container (1) according to one of the preceding claims, comprising the steps of:
a) forming at least one perforated portion (4) on said paper or cardboard layer (3);

b) applying, either directly or indirectly, said aluminium layer (5) onto the inside of said paper or cardboard layer (3);

c) applying said tab (9) onto said laminate (2) at said perforated portion;
characterized in that said step a) includes the step of d) forming at least two discrete pre-weakening lines (7, 8) extending from said perforated portion of said paper or cardboard layer (3), and said step c) includes the step of e) welding, either directly or indirectly, said first region (12) of said tab (9) onto at least part of said aluminium layer (5).
Method according to claim 17, characterized in that said step e) further includes the step of welding, either directly or indirectly, said second region (13) of said tab (9) onto at least part of said paper or cardboard layer (3) between said pre-weakening lines (7, 8).
Method according to claim 17 or 18, characterized in that said step b) is preceded by the step of f) applying at least one outer layer made of a thermoplastic material to the outside of said paper or cardboard layer, and the step of g) applying at least one intermediate layer made of a thermoplastic material to the inside of said paper or cardboard layer so as to weld said intermediate layer directly to said outer layer at said perforated portion.