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(11) | EP 1 160 175 A1 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | Lined container with rim |
| (57) A container (1) to be used as a package comprising at least one compartment (3) defining
an opening (2) for receiving objects to be packed and a surrounding rim (6), at least
the upper side of the container (1) defining an opening (2) being lined with a peelable
plastic film (4). In order to prevent the plastic film (4) to be unintentionally peeled
from the container when removing a lid, the peripheral area of the rim (6) is such
that there is no bond between the cover (8) and the plastic sheet (4). |
TECHNICAL FIELD
[0001] The present invention relates to a container to be used as a package comprising at least one compartment defining an opening for receiving objects to be packed and a surrounding rim, at least the upper side of the container defining an opening being lined with a peelable plastic film as set forth in the preamble of independent claims 1 and 8.
BACKGROUND ART
[0002] A container of this kind is disclosed in DE-4 327 669. Containers that can be hermetically sealed, for example for packing food or beverages, require the use of materials that display a barrier capacity to certain gases such as oxygen. On the other hand, containers made on the basis of a usually permeable substrate of inorganic materials such as for example foamed plastic, or organic materials such as moulded pulp, or mixtures of organic and inorganic materials such as starch and chalk are a desirable form of packaging since they can be mass produced in an inexpensive manner and are environmental friendly.
[0003] In order to be able to use these permeable and moist sensitive materials for this purpose a plastic film is laminated to the substrate on at least one side to render the package moist resistant and gas tight so that it can be used to contain wet products such as food or beverages and allow the above mentioned hermetic sealing for preservation purposes. After the goods to be packed have been placed in the container cover (also called top sheet) is put over the opening of the container and bonded to the plastic film on the rim surrounding the opening thus hermetically sealing the container.
[0004] In order to unpack the goods the top sheet has to be torn off from the container. This step leads to problems because the force for tearing off the top sheet tends to also tear the plastic film lining the container off the base material. If this happens, the goods remain in an unstable possibly leaking package like a bag which is formed by the top sheet and the plastic film. This situation is highly undesirable since it will be very difficult to remove the packed goods without spilling.
[0005] The problem is so prone because the bond between the plastic film and the base material is chosen low in order to render the film peelable from the base, such as required by the German "Duales System" in order to get the so-called "Grüner Punkt", for recycling and material selection purposes. By virtue of the properties that the container is required to have there is a dilemma between the requirements for safe opening of the container and the requirements for the environment in that it must be easy to peel off the plastic film from the base material.
DISCLOSURE OF THE INVENTION
[0006] On this background, it is the object of the present invention to provide a container of the kind referred to initially, which overcomes the above-mentioned problems. This object is achieved in accordance with claim 1 by the peripheral edge of the plastic film being disposed below the upper surface of the rim and by claim 8 by the peripheral zone of the plastic film being not bonded to the cover.
[0007] By placing the peripheral edge of the plastic film below the upper surface of the rim or by not bonding the cover to the peripheral areas of the plastic film the force required for tearing off the cover is reduced by the notch effect leading to a stress concentration and thus a lower overall force for tearing off is required. Further, by disposing the peripheral edge of the plastic film below the upper surface of the rim or by not bonding the cover peripheral zone of the plastic film a stress concentration on the bond between the plastic film and the substrate is avoided. Thus a relatively weak bond between the plastic film and the substrate can be used whilst avoiding unintended peeling of the plastic film from the substrate.
[0008] According to an embodiment of the invention, the rim comprises a flange for handling purposes. The plastic film may be bent around the peripheral edge of the rim. Further, the rim may have a peripheral area with an upper surface that is below the upper surface of the inner area of the rim.
[0009] In order to provide further security against unintended tearing of the plastic film from the container, the bond between the plastic film and the rim can be made substantially stronger than the bond between the film and the container in the other areas of the tray, for example by welding the plastic film to the rim. Preferably, the container is made of permeable material.
[0010] The container may be in the form of a tray and may have more than one compartment. The container can also have the shape of a drinking cup or a can.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] In the following detailed portion of the present description, the invention will be explained in more detail with reference to the exemplary embodiments shown in the drawings, in which
Figure 1 is a perspective view of a an embodiment of the container
Figure 2a to 2f are details in section of the rim of a container according to different embodiments of the invention,
Figure 3 is another embodiment of the container, and
Figure 4 is a detail in section of the rim of the container according to a last embodiment.
DETAILED DESCRIPTION OF THE INVENTION
[0012] With reference to Figure 1 and 2a) to 2f) of the drawings, a container 1 according to an embodiment of the invention is shown with reference numeral 1. The container 1 according to this embodiment is a so-called food tray comprising a three-dimensionally contoured body, preferably of a permeable material such as moulded pulp and covered on one side with a plastic film 4. It will be appreciated that materials other than moulded pulp material could be used for the container 1. The container 1 defines a compartment 3 for receiving goods. Such goods may be wet or in liquid form. The compartment 3 defines an opening 2 in the container 1 which is surrounded by a peripheral ring flange 6. The moulded pulp material of the container 1 is laminated on at least one side with a plastic film 4 such as polyester to prevent the contents, normally food stuffs including liquid, of the container 1 permeating the board material. The plastic film 4 material is laminated to the container 1 by hot pressing and the application of a vacuum through the container in a conventional manner. Thus the plastic film 4 is bonded all over to the one side of the container. A suitable material for the film 4 is extruded polyester film, although other materials could be used. The plastic film 4 may be multilayered and also biodegradable films may be used. The film 4 should preferably display gas barrier qualities in order to be able to hermetically seal the goods for preserving reasons. The so-called EVOH film is particularly suitable if gas barrier properties are required. A cover 8 can be sealed to the plastic film 4 around the rim 6 of the container 1 in a conventional manner, once the container 1 has been filled with the required contents. This operation may be carried out by welding or heat sealing.
[0013] The cover 8 may be provided with an ear 5 for gripping the cover when tearing it off. Also the plastic film 4 may be provided with an ear (not shown) for peeling the plastic film 4 off the container when recycling.
[0014] Upon tearing off the cover 8 from a conventional container 1, a problem, as shown in Figures 2a and 2b, occurs in that there is a tendency of the plastic film 4 to be torn off the container 1 at the same time. The problem has become more prone in recent years due to requirements in respect of separability of waste in the recent years. According to such requirements, the plastic film 4 must be easily separable from the container material. Therefore, the bond between the plastic film 4 and for example the moulded pulp has to be relatively weak. In order to prevent an unintended pealing off of the plastic film 4, the rim area 6 of the present container 1 has a special construction.
[0015] According to the embodiment shown in Figure 2e, the plastic film 4 is folded over the edge 9 of the rim 6 so that the edge of the plastic film 4 is facing down. In all the embodiments the cover 8 is sealed only to the top of the rim 6 and therefore a peripheral zone of the plastic film 4 is not bonded to the cover 8. Thus, when tearing off the cover 8, the forces pulling the plastic film 4 away from the container are evenly distributed without a notch factor aggravating the tension to peal off. Due to the even distribution of the force, its stress concentration is avoided.
[0016] Such a peripheral zone of the plastic film 4 that is not bonded to the cover 8 can be achieved in other ways which are shown in the embodiments according to Figures 2d to 2f. The rim 6 may, as shown in Figure 2c, be provided with a flange 7 with an upper surface disposed below the upper surface of the rim 6 as shown in Figure 3. Thus, when the cover 8 is sealed with an ordinary hot tool to the plastic film 4 at the rim 6, bonding between the cover 8 and the plastic film 4 at the lower flange 7 is not established. The flange 7 is disclosed in the drawings as extending horizontally, it is understood, however, that the flange may extend non-horizontally.
[0017] Figure 2d discloses a further embodiment of the container 1 in which the rim 6 comprises a thin peripheral section forming a kind of flange 7, thus leading to the upper surface of the thinner section being disposed below the upper surface of the rim 6. After a container 1 is laminated, the waste material surrounding the rim is removed by die-cutting. When a hot knife is used, the plastic film is partially melted and drawn down with the knife, thus forming a peripheral zone of the plastic film 4 that will not be bonded to the cover 8 (as shown in Figure 2f).
[0018] Figure 3 shows a multicompartment tray 1, which could be used to be filled with different components of a ready-meal. The rim 6 surrounds the openings of the compartments 3. The rims between adjacent openings 2 are not normally affected by the above-mentioned problem of unintended peeling off of the plastic film 4, but may as described in more detail with reference to Figure 4 be only partially bonded with the cover 8.
[0019] Another way of achieving a peripheral zone of the plastic film 4 that is not bonded to the cover 8 is by selectively bonding the cover 8 to the plastic film 4 at the rim 6. As shown in Figure 4, the container 1 has a conventionally shaped rim 6. The plastic film 4 ends at-the edge of the rim 6. The cover 8 is, however, not bonded to the total area of the rim 6. By applying a selective hot tool (not shown), only the inner area 10 of the rim 6 is bonded to the cover 8, whereas the peripheral area of the rim 6 is not bonded to the cover 8. Thus, a container 1 is obtained in which the stress on the plastic film 4 during the tearing off of the cover 8 is reduced and therefore the risk of unintentional pealing off of the plastic film 4 is reduced.
[0020] Bonding the cover 8 to a selected area 10 of a conventional rim 6 may also be obtained by selectively applying adhesive to the desired area 10.
[0021] According to an embodiment of the invention, the bond between the plastic film 4 and the rim 6 is substantially stronger than the bond between the plastic film 4 and the rest of the container 1 due to welding (temperature or high frequency) the plastic film 4 to the rim 6. This stronger bond may also be obtained by applying a special adhesive to the rim 6 when laminating the plastic film 4 onto the container 1.
[0022] The film 4 has been addressed as "plastic film". The term "plastic film" is meant to comprise any shapable film such as starch based (biodegradable), rubber based, cellulose based and polymer based films, which are suitable for lamination onto a container.
[0023] Although the preferred embodiments have been described with a container of permeable material, it is understood that the container according to this invention may be made of non-permeable material.
LIST OF REFERENCE NUMERALS
1. Container (1) to be used as a package comprising at least one compartment (3) defining
an opening (2) for receiving objects to be packed and a rim (6) surrounding the opening
or openings (2), at least the upper side of the container which defines the opening
or openings (2) being lined with a peelable plastic film (4) covering the compartment
(3) and the surrounding rim (6), characterised in that the peripheral edge of the plastic film 4 is disposed below the upper surface of
the rim (6).
2. Container according to claim (1), characterised by the rim (6) comprising a flange (7).
3. Container according to claim 1 or 2, characterised in that the plastic film (4) is bent around the peripheral edge of the rim (6).
4. Container according to any of claims 1 to 3, characterised in that the rim (6) has a peripheral area with an upper surface that is below the upper surface
of the inner area of the rim (6).
5. Container according to claim 1 to 4, characterised in that bond between the plastic film (4) and the rim (6) is substantially stronger than
the bond between the plastic film (4) and the container (1) in the other areas of
the container (1), preferably due to welding the plastic film (4) to the rim (6).
6. Container according to any of claims 1 to 5, characterised by comprising a cover (8), preferably of plastic, bonded to the plastic film (4) at
the rim (6).
7. Container according to any of claims 1 to 6, characterised in that the container (1) made of permeable material.
8. Container 1 comprising at least one compartment (3) defining an opening (4) for receiving
objects to be packed and a rim (6) surrounding the opening (2), at least the upper
side of the container (1) which defines an opening (2) being lined with a peelable
plastic film (4) covering the compartment (3) and the surrounding rim (6), a cover
(8) bonded to the plastic film (4) at the rim (6), characterised in that the peripheral zone of the plastic film (4) is not bonded to the cover (8).
9. Container according to claim 8, characterised by the rim (6) comprising a flange (7).
10. Container according to claim 8 or 9, characterised in that the plastic film (4) is bent around the peripheral edge of the rim (6).
11. Container according to any of claims 8 to 10, characterised in that the rim (6) has a peripheral area with an upper surface that is below the upper surface
of the inner area of the rim (6).
12. Container according to claim 8 to 11, characterised in that the bond between the plastic film (4) and the rim (6) is substantially stronger than
the bond between the film (4) and the container (1) in the other areas of the container
(1), preferably due to welding the plastic film (4) to the rim.
13. Container according to any of claims 8 to 12, characterised in that the container is made of permeable material.