US20050150891A1

US20050150891A1 - Packaging having a perforable lid

Info

Publication number: US20050150891A1
Application number: US11/011,786
Authority: US
Inventors: Gerwin Schalk; Uwe Obermann
Original assignee: Amcor Flexibles Europe AS
Current assignee: Amcor Flexibles ApS
Priority date: 2003-12-16
Filing date: 2004-12-15
Publication date: 2005-07-14
Also published as: IL165795A0; DE60323245D1; ES2312739T3; ATE406325T1; EP1544127B1; IL165795A; EP1544127A1; DK1544127T3

Abstract

The packaging (10) comprises a container (12) in the form of a cup which delimits an access opening (16) bordered by a peripheral band (20) for the fused bonding of a lid (14), and a lid (14) made of polymer for the initial sealing of the access opening (16), which lid (14) is maintained on the band (20) along a peripheral fused bond (22). The lid (14) comprises, away from the peripheral fused bond (20), in an area covering the access opening (16), a line (24) of weakening of the lid. The weakening line (24) and the fused bond (22) of the lid on the container (12) are such that the tear strength of the lid (14) along the weakening line (24) is lower than the tear strength of the fused bond (22).

Description

The present invention relates to a packaging comprising a container in the form of a cup which delimits an access opening bordered by a peripheral band for the fused bonding of a lid, and a lid made of polymer or other material for the initial sealing of the opening fuse bonded along said peripheral band.
Nowadays, many food products are packaged in trays or beakers which are initially sealed by a lid. Such products may be solid, such as rice, pasta or dishes in sauce. They may also be semi-liquid products such as soups or desserts, or liquids such as refreshing drinks or yoghurts.
In the known types of packaging, the lid is formed by a polymer film fuse bonded to the periphery of the access opening. In order to reach the contents of the packaging, the lid must be cut or torn off. In particular, in order to allow the lid to be torn off by breaking of the peripheral fused bond, it is known to provide a tab on the edge of the lid, which projecting tab can be grasped by hand by the user in order to exert a pull on the lid.
Such a tab which extends the lid beyond the access opening is sometimes difficult to grasp, and it is often difficult to open the packaging by breaking the peripheral fused bond. In particular, controlled fused bonding is required, with a breaking load of the fused bond that is sufficiently high to provide effective protection for the products to be packed and sufficiently low to allow the bond to be broken without the user's having to exert too great a force.
Accordingly, such types of packaging are not wholly satisfactory and are, especially, difficult to open.
The object of the invention is to propose a packaging which can be opened more easily.
To that end, the invention relates to a packaging according to claim 1.
According to particular embodiments, the invention has one or more of the features of the dependent claims.
The invention relates also to a method of opening a packaging according to any one of claims 18 to 22.
The invention will better be understood upon reading of the following description, which is given solely by way of example and with reference to the drawings, in which:
FIG. 1 is a perspective view of a first embodiment of a packaging prior to opening;
FIGS. 2, 3, 4 and 5 are views identical to that of FIG. 1 at successive stages of opening of the packaging;
FIG. 6 is a perspective view of another embodiment of a packaging according to the invention prior to opening;
FIG. 7 is a view identical to that of FIG. 6 of the packaging during opening; and
FIG. 8 is a perspective view of yet another embodiment of a packaging according to the invention.
FIG. 1 shows a packaging 10 for the packaging of a solid cooked dish or of solid food products. Such a packaging is especially suitable for a product that has intended to be re-heated especially in a microwave oven. The packaging may likewise be used for the packaging of liquid or semi-liquid food products or of non-food products such as cosmetic products, shampoos, adhesives or mechanical elements such as screws.
The packaging is constituted by a generally circular tray 12 and a flexible lid 14 for sealing an access passage or opening 16 to the inside of the tray 12.
The tray is made of a thermoformed polymer film. It is relatively rigid and, especially, self-supporting, so that it retains its shape whether or not it is filled with contents, such as a food product. The tray 12 is constituted, for example, by an outer support layer of a suitable material, for example polyvinyl chloride (PVC), which is covered on its inner surface with a layer that can be fuse bonded, for example of polyethylene (PE). By way of variation, the tray is formed of a thermoformable polymer such as amorphous polyester (APET), polypropylene (PP), polystyrene (PS) or an amorphous polyester (APET)/polyethylene (PE) complex.
The tray defines a receptacle 18 which is bordered over its entire periphery by an edge 20 delimiting a flat surface for the fused bonding of the lid 14 along a peripheral fused bond 22.
The lid 14 is constituted by a flexible polymer film formed of one or more superposed layers. The shape of the lid 14 is identical with the outer periphery of the peripheral edge of the tray and, more precisely, identical with the shape of the fused bond 22. Accordingly, the lid beyond the fused bond 22 as a continuation of a weakening line.
Initially, the lid is kept tight on the edge 20 across the access opening 16. In particular, the lid is held away from the food products contained in the packaging, so that a free space 23 (FIG. 4) filled with air or any other gas is interposed between the lid and the food products contained in the packaging and resting on the bottom of the tray.
The gas contained in the free space 23 may be at atmospheric pressure, at a higher pressure or at a lower pressure. In the latter case, a more or less high vacuum is created in the packaging when it is sealed.
According to the invention, the lid 14 comprises, away from the peripheral fused bond 22, in the area covering the access opening 16, a line of weakening 24 of the lid. The weakening line 24 does not pass through the thickness of the lid. The weakening line and the fused bond 22 of the lid on the container are such that the tear strength of the lid along the weakening line is lower than the tear strength of the fused bond when a pressure is applied to the lid.
Preferably, the tensile strength of the lid on either side of the weakening line is from 1 N/15 mm to 70 N/15 mm and preferably from 2 N/15 mm to 25 N/15 mm.
In the embodiment of FIG. 1, the weakening line 24 delimits a closed shape and the whole of its trace is contained within the area covering the access opening 16. The closed shape delimits a profile corresponding generally to the profile of the edge 20 bordering the passage 16.
More precisely, in the embodiment shown, the weakening line 24 delimits a generally circular profile and has locally a tongue 26 which projects outwards relative to the general trace of the weakening line.
The tongue has a generally concave profile of substantially constant curvature. Its dimensions correspond generally to the dimensions of the end of a human being's finger. Accordingly, the tongue has a width of from 2 cm to 5 cm and also a length of from 2 cm to 5 cm.
It is advantageous, but not compulsory, for the weakening line 24 delimiting the tongue to have at least one angular point (not shown) which forms an acute angle suitable for promoting tearing of the lid.
The lid 14 has a visible marking identifying the position of the weakening line 24. In the embodiment shown in FIG. 1, that marking is constituted by a discontinuous black line printed on the lid.
The weakening line 24 is produced by treatment of the film constituting the lid 14.
According to a first embodiment, the weakening line 24 is produced by the application of high-energy radiation, such as a laser, by application of a laser beam along the trace of the weakening line 24, before the lid 14 is placed on the tray. Treatment by high-energy radiation is carried out on one or more films of the lid 14 when the latter comprises more than one film.
According to another embodiment, the weakening line is formed by a mechanical weakening of the lid which extends along the trace of the weakening line 24. That mechanical treatment is carried out on one or more films of the lid when the latter comprises more than one film.
According to a first example, a microporous weakening is provided along a strip of small width in order to form at least part of the weakening line 24. Such a microporous strip of a film is obtained, for example, by passing the film of the lid between two rollers, one of which rollers has been rendered abrasive along the trace of the weakening line. Such a treatment is described, for example, in document FR-2.717.449.
According to a second example, the mechanical weakening is formed by cutting the thickness of one or more films of the lid when the latter comprises more than one film. The cuts are formed by a matrix of cutting elements, the lid being pressed between the matrix and a support, as is known per se.
According to yet another example, the weakening line is obtained by a line of micro-perforations which do not pass through the lid, the micro-perforations being formed through one or more films when the lid comprises a plurality of films.
According to a particular embodiment, the weakening of the lid along the weakening line is variable according to the position along the weakening line. For example, the tongue 26 than at the generally circular periphery bordering the peripheral fused bond.
Such differences in weakening are obtained, for example, by locally combining several weakening treatments on one or more films constituting the lid, or by carrying out a more or less deep or more or less dense weakening treatment along the regions of the weakening line 24. Such more or less dense or deep treatment is achieved in a particularly successful manner by subjecting the film to high-energy radiation.
According to a first embodiment, the lid 14 is unilayer and is formed by a base film of polymer or paper. Accordingly, the lid 14 is a single-material lid. In order to bond it to the edge of the tray, the film of polymer or paper forming the lid is advantageously coated on its inner surface with a sealing material which is applied, for example, by extrusion, coating, co-extrusion or coating during the application of printing ink to the base film.
The base film is preferably formed by a bioriented polymer film, which may be co-extruded. It may also be a mono-oriented or non-oriented film obtained by co-extrusion. That film is formed, for example, of polypropylene (OPP), polyester (OPET) or polyvinyl chloride (PVC). The thickness of the base film is generally from 5 to 500 microns and preferably from 15 microns to 150 microns.
The sealing material is chosen to be compatible with the material constituting the tray, in order to permit fused is from 10 to 40 microns, the amount of sealing material deposited being from 1 to 12 g/m².
In that case, the weakening is formed in the base film.
According to a second embodiment, the lid 14 is formed by two complexed films. Accordingly, the lid comprises a base film formed of polymer or paper which is associated, along its face facing the tray, with a sealing film of polymer which is compatible with the material of the tray, in order to permit fused bonding.
The base film and the sealing film are bonded with one another by complexing with the aid of an adhesive or by resin extrusion.
The base film is advantageously formed of a bioriented polymer film. However, it may also be a cast film. The polymer forming the base film is preferably polyester (PET), polyamide (OPA) or polypropylene (OPP).
The sealing film is formed, for example, of polyethylene (PE), optionally in admixture or co-extruded with other polymers. By way of variation, the sealing film is formed of polypropylene (PP), preferably cast polypropylene, of the homopolymer type or of the copolymer type with ethylvinyl acetate (EVA).
According to another variant, the sealing film is constituted by amorphous polyester or copolyester (PETG).
When the lid is formed by two complexed films, the film on its face that is in contact with the tray, as in the case of a single-material film.
In this embodiment, where the lid is formed by two films, the weakening is effected on the outer layer and optionally on a portion of the thickness of the inner layer. According to a particular embodiment, the outer film is weakened by treatment with high-energy radiation, while the inner film is weakened by mechanical treatment such as a microporous weakening, or vice versa. By way of variation, the same mechanical or high-energy radiation treatment is carried out on both films.
By way of variation, the lid 14 is formed of a two-layer complex film formed, for example, of polyester (PET)/polypropylene (PP), aluminium film/polyester (PET), aluminium film/oriented polypropylene (OPP) or layer of paper/polypropylene (PP).
Polyethylene films are advantageously complexed by co-extrusion with a small thickness.
According to yet another embodiment, the lid comprises three films, of which the two outside films are as defined above for a lid formed of two films, an intermediate film being interposed between the two outside films.
The intermediate film is formed, for example, of an aluminium foil of from 6 to 100 microns and preferably from 7 to 38 microns. The aluminium foil is annealed or cold-hammered.
Accordingly, the lid is formed, for example, of polyester (PET)/aluminium/cast polypropylene (PPC) or of polyester (PET)/aluminium/polyethylene (PE) or of oriented polyamide (OPA)/aluminium/polypropylene (OPA)/aluminium/cast polypropylene (PPC) or of oriented polyamide (OPA)/aluminium/cast polyethylene (PEC).
By way of variation, the intermediate film is a bioriented film, for example a film of oriented polyamide, especially in a polyester (PET)/polyamide (OPA)/polypropylene (PP) and polyester (PET)/polyamide (OPA)/polyethylene (PE) structure.
When the lid comprises three films, the intermediate film is advantageously weakened by treatment with high-energy radiation along the weakening line.
According to another variant, the lid is formed of three films and is composed, for example, of polyester (PET)/polypropylene (PP)/polyester (PET).
Such a packaging is opened as follows.
When the packaging is placed with the bottom of the tray on a flat surface, the user pushes the tongue 26 of the lid into the packaging by pressing with his finger, as illustrated in FIG. 2. Because the contents of the packaging are not located immediately beneath the lid, the lid can be distorted inwards, causing it to start tearing along the weakening line 24 without the lid's coming into contact with the contents of the packaging resting on the bottom of the tray.
Because the tear strength of the lid along the weakening line is lower than the tear strength of the fused bond, the film tears in the vicinity of the user's finger. In particular, because the curvature of the tongue is relatively great, the lid tears along the contour of the tongue.
During the initial perforation of the lid by pressure with the finger, a characteristic noise such as a “pop” is audible to the user owing to the passage of gas contained in the tray through the torn lid when the pressure of that gas is greater than atmospheric pressure.
Likewise, a characteristic noise is also audible to the user during the initial tearing of the lid when the initial pressure in the packaging is below atmospheric pressure. That noise arises from the passage of air from outside the packaging to the inside through the torn lid.
If necessary, the packaging is placed in a microwave oven while the lid is torn only over the periphery of the tongue. Under the action of the radiation in the microwave oven, the products contained in the packaging are heated and gas escapes through the opening formed in the region of the tongue 26. In addition, the tongue heats up and tends to bend towards the outside of the packaging, as illustrated in FIG. 3.
When the packaging has been removed from the oven, the user easily grasps the tongue so deformed and pulls on the portion of the lid delimited by the weakening line 24. The lid thus gradually tears along the weakening of the lid is completely detached, as illustrated in FIG. 5, thus allowing access to the food product contained in the packaging.
By way of variation, the packaging is placed in a microwave oven before the lid is torn. The microwave radiation causes the products contained in the packaging to be heated, so that the pressure in the packaging increases. Under the action of the pressure in the packaging, the lid is urged outwards until it tears along the weakening line, especially over the contour of the tongue 26. After removal from the microwave oven, the detached part of the lid is torn off and detached fully from the remainder of the packaging, as illustrated in FIG. 5.
FIGS. 6 and 7 show another embodiment of a packaging according to the invention.
In this embodiment, elements which are identical or analogous to those of the first embodiment are designated with the same reference numerals.
In this case, the tray 12 is replaced by a beaker designated by the same reference numeral, the beaker being deeper than the tray and being suitable for receiving a liquid.
Furthermore, the weakening line, denoted 124, defined on the surface of the lid 14 forms a transverse line which extends in the area covering the access opening between two separate points of the peripheral fused bond 16. More precisely, the weakening line 124 connects two opposite tongue 126 of a shape comparable with the tongue 26 of the preceding embodiment.
In this embodiment, the tongue 126 has, along its contour, an angular point 128 which facilitates the start of tearing of the lid along the weakening line.
When the lid is pushed in, for example by pressing with a finger on the surface of the tongue 126, the lid first tears along the point 128. The tear propagates along the contour of the tongue 126 on either side thereof. The operator then grasps the tongue 126 and pulls on the detached portion of the lid, as illustrated in FIG. 7. This causes the lid to tear fully along the weakening line 124 and the gradual delamination of the peripheral fused bond 22. This delamination causes the exposure of a band, denoted 130, of the edge, which band was initially covered by the lid. This newly exposed band allows the user to place his lips on a clean surface in order to drink the liquid contained in the beaker.
In this embodiment, the lid is advantageously formed of a complex film comprising three layers formed, for example, of polyester (PET)/aluminium film/polyethylene (PE) or oriented polypropylene (OPP)/aluminium film/polyethylene (PE). By way of variation, the lid is constituted by a complex film comprising at least two layers, for example of polyester (PET)/polyethylene (PE), oriented polypropylene (OPP)/polyethylene (PE) or paper/polyethylene (PE).
The materials described for the packaging of FIGS. 1 to 5 may likewise advantageously be used.
In this embodiment, the weakening line 124 is produced by one of the methods envisaged for the preceding embodiment.
FIG. 8 shows another variant of a packaging according to the invention. In this embodiment, the weakening line 124 extends only in the area of the lid covering the access opening. Accordingly, the weakening line does not extend over the peripheral fused bond 22. The weakening line here defines a shape that is not closed. It forms in particular a tongue 126 which is extended laterally on either side by two curved portions.
The weakening line allows the lid to be opened partially in order to introduce an object or a substance into the packaging. Accordingly, the opening formed in the lid allows the introduction of a straw, for example. It also allows certain substances, such as sugar or salt, to be added to the packaging. It also allows the introduction of a member for mixing, such as a spoon or a rigid stirrer.

Claims

1. Packaging (10) comprising a container (12) in the form of a cup which delimits an access opening (16) bordered by a peripheral band (20) for the fused bonding of a lid (14), and a flexible lid (14) for the initial sealing of the access opening (16), which lid (14) is maintained on the band (20) along a peripheral fused bond (22), characterised in that the lid (14) comprises, away from the peripheral fused bond (22), in an area covering the access opening (16), a line (24; 124) of weakening of the lid which does not pass through the lid, the weakening line (24; 124) and the fused bond (22) of the lid on the container (12) being such that the tear strength of the lid (14) along the weakening line (24; 124) is lower than the tear strength of the fused bond (22) when a pressure is applied to the lid, said lid (14) being without a gripping tab which outwardly extends the weakening line beyond the peripheral fused bond (22).

2. Packaging according to claim 1, characterised in that the weakening line (24) extends along a trace which is wholly contained within the area covering the access opening (16).

3. Packaging according to claim 2, characterised in that the weakening line (24) delimits a closed shape which is wholly contained within the area covering the access opening (16).

4. Packaging according to claim 1, characterised in that the weakening line (124) forms a line which extends at least in the area covering the access opening (16), between two separate points of the peripheral fused bond (22).

5. Packaging according to claim 1, characterised in that the tensile strength of the lid along the weakening line (24; 124) is from 1 N/15 mm to 70 N/15 mm.

6. Packaging according to claim 1, characterised in that the weakening line (24; 124) delimits a tongue (26) whose dimensions correspond substantially to the dimensions of a human finger.

7. Packaging according to claim 6, characterised in that the weakening line (24; 124) forms at least one angular point (128) on the contour of said tongue (26).

8. Packaging according to claim 1, characterised in that the lid (14) has a visible marking identifying the position of the weakening line (24; 124).

9. Packaging according to claim 1, characterised in that the lid (14) has, along the weakening line (24; 124), at least one mechanical weakening treatment on at least one film of the lid.

10. Packaging according to claim 9, characterised in that said mechanical weakening treatment comprises a microporous weakening.

11. Packaging according to claim 9, characterised in that said mechanical weakening treatment comprises partially cutting at least one film of the lid (14) with the aid of a matrix of blades along the trace of the weakening line (24).

12. Packaging according to claim 1, characterised in that the lid (14) has, along the weakening line (24; 124), a weakening treatment by high-energy radiation along at least one film of the lid.

13. Packaging according to claim 12 characterised in that the lid comprises at least two complexed films, the first film having undergone mechanical weakening treatment along the trace of the weakening line (24), the second film having undergone weakening treatment by means of high-energy radiation along the trace of the weakening line (24).

14. Packaging according to claim 1, characterised in that the lid (14) is a complex in which the combination of films is selected from the group consisting of polyester (PET)/polyamide (OPA)/polypropylene (PP), polyester (PET)/polyamide (OPA)/polyethylene (PE), polyester (PET)/polypropylene (PP), aluminium/polyester (PET), aluminium/oriented polypropylene (OPP), layer of paper/polypropylene (PP), polyester (PET)/aluminium/cast polypropylene (PPC), polyester (PET)/aluminium/polyethylene (PE), oriented polyamide (OPA)/aluminium/cast polypropylene (PPC), oriented polyamide (OPA)/aluminium/cast polyethylene (PEC), polyester (PET)/polypropylene (PP)/polyester (PET), polyester (PET)/aluminium/polyethylene (PE), oriented polypropylene (OPP)/aluminium/polyethylene (PE), polyester (PET)/polyethylene (PE), oriented polypropylene (OPP)/polyethylene (PE), and paper/polyethylene (PE).

15. Packaging according to claim 1, characterised in that the weakening line (24; 124) is in such a form that a sound is emitted when it is initially torn under the action of a gas flowing through the torn lid (14).

16. Packaging according to claim 1, characterised in that it comprises a product contained in the container (12) and resting on a face of the container remote from the lid (14), and in that a free space (23) filled with a gas is defined between the lid (14) and the product, which free space (23) is sufficient to allow deformation of the lid inside the container (12) to initiate tearing of the lid (14), without the lid's coming into contact with the product.

17. Packaging according to claim 1, characterised in that the weakening line (24) has a tear strength by application of a pressure on the lid (14) which varies along the length of the weakening line (24).

18. Method of opening a packaging as defined in claim 1, characterised in that it comprises steps consisting in:

urging the lid (14) from the outside to the inside of the packaging by means of pressure, until the lid (14) tears along the weakening line (24; 124);

grasping the lid (14) torn along the weakening line (24; 124); and

pulling on the part of the lid (14) that has been grasped in order to continue tearing the lid (14) along the weakening line (24; 124).

19. Method according to claim 18, characterised in that it comprises a final phase of removing from the container (12) the part of the lid that has been grasped.

20. Method according to claim 19, characterised in that the packaging is cording to claim 4 and in that the method comprises a step of baring a portion of the peripheral nd for the fused bonding of the lid formed on the container.

21. Method according to claim 18, characterised in that it comprises a step of introducing an auxiliary element through the torn lid.

22. Method of opening a packaging as defined in claim 1, characterised in that it comprises steps consisting in:

heating the inside of the packaging in order to increase the pressure inside the packaging;

maintaining heating at least until the lid tears along the weakening line (24; 124).