This invention relates to a method and a device for heat-sealing a film/foil onto a peripheral top edge of a packaging.

Packagings may consist of a more or less dimensionally stable holder with an opening. In practice, such holders are often covered with a lid and/or by a layer of film/foil material. For decorative purposes, a cover made of a film/foil material is sometimes arranged over the opening, such as for example paper or textile, which not only covers the opening, but also hangs down along the periphery of the holder (or the contour of the holder, respectively). Such a decorative overhanging edge is also referred to as a “skirt”. The skirt gives a “traditional” appearance to products, such as for example jars filled with pates and jam. The skirt may also be clamped securely by the lid or - if attached to the outside of a lid - may be clamped around the lid and/or an edge of the holder by means of, for example, a piece of string, ribbon or rubber band. However, fitting a skirt in this manner is labour-intensive.

Heat-sealing a film/foil layer onto a packaging is known from the prior art. One of the known ways is to use a heat-shrinking head.

Document DE3047932 discloses a crimping head, which crimping head is capable of crimping a film/foil around a packaging. Ring parts of the crimping head can crimp the film/foil around the holder by means of a movement. However, the crimping head is only suitable for crimping a film/foil. The drawback of this invention is that the invention cannot heat-seal the film/foil onto the packaging. Another drawback of the crimping head is that there is a considerable risk of damage to the film/foil which is to be arranged around the packaging, leading to unsightly effects, damage to the film/foil, or as a result of which any text is hardly legible by the end user, if at all.

Document GB1085834 describes an apparatus which is capable of heat-sealing a film/foil onto a peripheral top edge of a packaging. The remaining film/foil can be crimped against the wall of the packaging by means of a pivoting arm. This apparatus is only suitable for producing a heat-seal at one location of the holder. The apparatus is not suitable for producing heat-seals at multiple locations of a packaging. Another drawback of the apparatus is that the remaining film/foil is pushed over the packaging, resulting in a bad finish of the packaging. Another drawback of the apparatus from this document is that the overhanging part of the film/foil is pushed over the packaging by an arm, in which case the arm slides across the packaging. The risk of this movement causing damage to the film/foil during heat-sealing is considerable.

In this application, the term heat-sealing is, inter alia, understood to mean the following; the actual fusing together of a film/foil to be applied and the packaging, bonding a film/foil to be applied with the packaging by means of an applied coating, in which case the coating may be applied to the packaging and/or the film/foil. It is conceivable for this fusing and/or bonding to be brought about by way of a coating by means of an elevated temperature. However, it is also conceivable for this fusing and/or bonding to be brought about by way of a coating by means of a chemical process. More particularly, such a chemical process may comprise the use of a bonding agent, such as an adhesive. This adhesive may be applied separately or may, for example, already be present on one of the two components to be bonded. It is also conceivable for the adhesive to be multi-component adhesive, in which case one of the two types of adhesive is applied to each of the parts. In certain cases, a chemical process, and in particular the use of an adhesive, may make it possible to effect the bonding without (optionally local) heating. In particular, according to the present invention, a film/foil may be used as a bonding agent, in combination with heating, together with a coating as bonding agent, unheated or in combination with heating, or with an adhesive layer as heat- seal medium, unheated or in combination with heating.

The object of the present invention is to offer an alternative method and a device for efficiently heat-sealing a film/foil on a packaging at multiple locations which overcomes the abovementioned drawbacks.

To this end, the invention proposes a method for sealing an opening of a packaging, in which the packaging comprises at least a peripheral wall with a peripheral top edge, which peripheral top edge forms the contour of the opening, comprising the following process steps: positioning a flexible film/foil layer over the peripheral top edge in such a way that the opening is completely covered and the film/foil layer overhangs beyond the peripheral top edge; heat-sealing the film/foil layer to the peripheral top edge of the packaging; folding the part of the film/foil layer overhanging beyond the opening towards the peripheral wall; heat-sealing the folded-over film/foil layer to the peripheral wall at a distance from the peripheral top edge, in which case a contact point of a device for heat-sealing the folded-over film/foil layer to the peripheral wall at a distance from the peripheral top edge does not move with respect to the film/foil layer during the heat-sealing, at least for as long as the contact point is in contact with the film/foil layer.

By means of this method, it is possible to apply a heat-seal to the peripheral top edge and the peripheral wall of a packaging, in which case the film/foil is not broken or damaged by the contact point of the device. Due to the fact that movement of the device and the film/foil with respect to each other is avoided at the moment of contact with the film/foil layer, the film/foil layer can be applied without damage. Heat-sealing onto the peripheral wall of the packaging takes place at at least one location on the peripheral wall, and preferably in several locations.

In an alternative variant embodiment, the heat-seal locations are uniformly distributed on the peripheral wall of the packaging in a peripheral direction. This results in the best distribution of the contact points and is also good for the uniform bonding of the film/foil layer to the peripheral wall. In an alternative variant embodiment, it is also conceivable for the film/foil layer to be heat-sealed to the peripheral wall in a sealing manner. In a further variant embodiment of the method, the contact point approaches the film/foil layer only in a direction towards the peripheral wall and forces the film/foil layer towards the peripheral wall during heat sealing. By only moving the contact point in a direction towards the peripheral wall, the present invention produces a high-quality heat-seal on the peripheral wall. Preferably, the contact point approaches the peripheral wall of the packaging in a substantially perpendicular direction.

In another alternative variant embodiment, the part of the film/foil layer overhanging beyond the peripheral top edge is arranged in wave- or zigzag-shaped folds when heat-sealing the film/foil layer against the peripheral wall of the packaging at the at least one heat-seal location. In this way, the local excess of film/foil material is distributed over the periphery in a controlled manner and, in addition, this may be advantageous from an aesthetic point of view and may also have a protective effect due to the voluminous arrangement.

In another alternative variant embodiment, the film/foil layer is also punched before and/or during one of the steps a-c. The advantage of punching the film/foil is that it can be applied to the packaging in a uniform manner, so that all sides or parts of the wall comprise equal amounts of film/foil. Punching of the film/foil may be performed for steps a-c of a film/foil layer which is wound to form a roll, in which case the resulting punched film/foils can immediately be used in the heat-sealing process. In addition, the film/foils may already be ordered in a form which is adapted to a packaging and may subsequently be positioned above the packaging in such a way, in which case a punching member punches the film/foil in such a way that the overhanging part is uniform around the packaging.

In yet another alternative variant embodiment, the at least one contact point of the device moves in a substantially circular motion towards the heat-seal location on the peripheral wall of the packaging during folding over in step c, the centre of the circle being situated on the peripheral top edge. This movement of the contact point reduces the shear between the contact point of the device and the film/foil layer, or even removes it completely. By removing this shear, the film/foil layer remains intact, which produces a high-quality heat-seal.

In another alternative variant embodiment, the folding in step c is performed with at least one directional component perpendicular to a plane which is enclosed by the peripheral top edge. In this variant embodiment, the contact point of the device is configured for folding the film/foil layer with a directional component which is perpendicular to the enclosed plane, and subsequently heat-sealing the film/foil layer onto the peripheral wall. Folding the film/foil layer with a perpendicular directional component again reduces the shear between the contact point and the film/foil layer, which results in a heat-seal of better quality.

In another variant embodiment, the film/foil layer is heat-sealed to the peripheral top edge so as to be medium-tight with the packaging. This is advantageous with regard to preventing the foodstuffs from perishing and may make additional sealing of the packaging superfluous. It also reduces the risk of leakage from the packaging. It should be noted that the film/foil layer may be attached to the packaging so as to be detachable in order to allow access to the contents of the packaging, and that it is also conceivable for the removed film/foil layer to be re attached again and thus to be resealable. Alternatively, the film/foil layer may, on the contrary, be attached in such a way that the packaging can only be opened once by cutting and thus damaging the film/foil. As a result thereof, it is clear to a user of an unopened packaging or film/foil layer that the food in the packaging is fresh and untouched.

The invention also relates to a device for sealing an opening of a packaging with a film/foil, wherein the packaging comprises at least a peripheral wall with a peripheral top edge, which peripheral top edge forms the contour of the opening, the device comprising a holder for the packaging; means for positioning a flexible film/foil layer over the peripheral top edge in such a way that the opening is completely covered and the film/foil layer overhangs beyond the peripheral top edge; a first heat-seal element which is movable to and from the opening of a packaging placed in the holder and is configured to heat-seal a film/foil layer onto the peripheral top edge of a packaging placed in the holder; a bending element for bending the part of the film/foil overhanging beyond the peripheral top edge over the peripheral top edge as far as against the peripheral wall of a packaging; a second heat-seal element which is movable to and from the peripheral wall of a packaging placed in the holder, wherein the second heat-seal element, at least when touching the peripheral wall, is only movable perpendicularly to the plane of the packaging and the film/foil folded against it

The device differs from those of the prior art in that the present device is capable of producing a double heat-seal, the second heat-seal being performed by means of a movable heat-seal element, wherein the second heat-seal element, at least with one directional component, is movable substantially perpendicularly to the peripheral wall, and wherein the second heat-seal element is configured to force the film/foil layer towards the peripheral wall during heat-sealing. Therefore, the contact point between the device and the film/foil layer does not move during the movement, and the entire film/foil layer remains intact. It is important that the film/foil layer does not become damaged, as this may contain advertising or other text which may be rendered illegible as a result of such damage.

In a further alternative variant embodiment of the device, the device also comprises a punching member configured for punching the film/foil layer. Punching the film/foil layer may be performed at various points in time. The punching operation may, for example, be performed at the same time as the application of the heat-seal to the peripheral top edge, but may also be performed after the heat-seal has been applied to the peripheral top edge and before the film/foil layer is bent.

In an alternative variant embodiment of the device, the bending element, the first and the second heat-seal element are formed by one component. By limiting the number of separate components, a more compact device may be achieved. In one alternative embodiment, the bending element and the second heat-seal element may be the same element, and wherein the first and the second heat-seal element only differ with respect to each other in the contact point with the film/foil layer.

The present method and device will be explained in more detail below by means of the following figures, in which

- Figs. 1a-1c show a diagrammatic view of the method, and

- Figs. 2a and 2b show a diagrammatic view of a variant embodiment of the device.

Here, Figs. 1a-1c diagrammatically show the steps of the method for sealing an opening of a packaging 3, wherein the packaging comprises at least a peripheral wall 4 with a peripheral top edge 1 , which peripheral top edge 1 forms the contour of the opening, comprising the following process steps: positioning a flexible film/foil layer 2 over the peripheral top edge in such a way that the opening is completely covered and the film/foil layer 2 overhangs beyond the peripheral top edge 1 is illustrated in Fig. 1a; heat-sealing 5 the film/foil layer to the peripheral top edge 1 of the packaging 3 is illustrated in Fig. 1 b; folding the part of the film/foil layer 2 overhanging beyond the opening towards the peripheral wall 4; heat-sealing the folded-over film/foil layer 2 to the peripheral wall 4 at a distance from the peripheral top edge 1 , in which case a contact point 6 of a device for heat-sealing the folded- over film/foil layer 2 to the peripheral wall 4 at a distance from the peripheral top edge 1 does not move with respect to the film/foil layer 2 during the heat-sealing, at least for as long as the contact point 6 is in contact with the film/foil layer 2, is shown in Fig. 1c. During folding over, the at least one contact point 6 of the device moves in a substantially circular motion 7 towards the heat-seal location 6 on the peripheral wall 4 of the packaging, the centre of the circle 5 being situated on the peripheral top edge 1 .

Figs. 2a and 2b diagrammatically show the device for sealing an opening of a packaging with a film/foil, wherein the packaging comprises at least a peripheral wall with a peripheral top edge, which peripheral top edge forms the contour of the opening, the device comprising a holder for the packaging; means for positioning a flexible film/foil layer over the peripheral top edge in such a way that the opening is completely covered and the film/foil layer overhangs beyond the peripheral top edge; a first heat-seal element 9 which is movable to and from the opening of a packaging placed in the holder and is configured to heat-seal a film/foil layer onto the peripheral top edge of a packaging placed in the holder; a bending element for bending the part of the film/foil overhanging beyond the peripheral top edge over the peripheral top edge as far as against the peripheral wall of a packaging; a second heat-seal element 8 which is movable to and from the peripheral wall of a packaging placed in the holder, wherein the second heat-seal element, at least when touching the peripheral wall, is only movable perpendicularly to the plane of the packaging and the film/foil folded against it.