Method for vacuum skin packaging a product arranged in a tray

Abstract

The invention relates to a vacuum skin packaging process, to a tray suitable for a vacuum skin packaging process and to the package thus obtained. The vacuum skin packaging process of the invention comprises providing a tray loaded with a product said tray comprising a bottom wall, a side wall upwardly extending from said bottom wall and terminating in an outwardly projecting horizontal rim, said side wall comprising at least one hole; placing the product loaded tray in a vacuum chamber; positioning a film above the product loaded tray; forming an airtight contact between the film and the rim of the tray; evacuating air from above the film to bring it into contact with a heating platen to heat the film; evacuating air from within the tray through the at least one hole; introducing air from above the film pushing the film in contact with the product and welding it to the inner surface of the tray closing the at least one hole in the side wall characterized in that the film is held in contact with the heating platen while air begins to be evacuated from within the tray. Preferably the film is positioned above the product loaded tray is a discrete piece of film having the size of the tray thus reducing the amount of film which is scrapped during a vacuum skin packaging process.

Claims

1. A vacuum skin packaging process comprising the steps of: providing a vacuum chamber comprising an upper portion opposing a lower tray-holding portion; placing in the lower tray-holding portion of the vacuum chamber a semi-rigid or rigid tray loaded with a product, the tray comprising a bottom wall, a circumferential side wall upwardly extending from the bottom wall and terminating in an outwardly projecting rim, the side wall comprising at least one hole; heating a film in contact with the upper portion of the vacuum chamber; evacuating air from within the tray through the at least one hole while the film is in contact with the upper portion of the vacuum chamber; and introducing air to push the film from contact with the upper portion to contact the product and weld the film around the product to the whole of the inner surface of the tray not occupied by the product and to close the at least one hole in the side wall.

2. The process according to claim 1 wherein an airtight contact is formed between the film and the rim of the tray before air is evacuated from within the tray through the at least one hole.

3. The process according to claim 1 wherein the film is held in contact with the upper portion of the vacuum chamber by vacuum also while being positioned above the product loaded tray and while an airtight contact is formed between the film and the rim of the tray.

4. The process according to claim 1 wherein the film is positioned above the product loaded tray and secured to the rim of the tray in at least one spot before said product loaded tray is placed in said vacuum chamber.

5. The process according to claim 4 wherein the film is heat-sealed to the whole rim of the tray.

6. The process according to claim 1 wherein the film is a discrete piece of film having the size of the tray.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Embodiments of the present invention will be described, by way of example only, with reference to the accompanying drawings in which:

(2) FIG. 1 is a perspective view of a tray according to one embodiment of the present invention;

(3) FIG. 2 is a cross-sectional view of a package according to one embodiment of the present invention

(4) FIG. 3 is a representative schematic view of the vacuum chamber 50 used in a process embodiment of the present invention.

(5) FIG. 1 shows a rectangular tray of the invention. Tray 10 comprises a bottom wall 2 and extending upwardly from said bottom wall a side wall 3. Side wall 3 forms the perimeter of the tray. The side wall terminates in a continuous rim 4 outwardly extending from the side wall. The side wall comprises four angled corners 6. A ledge 7 is present in each corner, close to the upper end of the side wall but at some distance below the rim of the tray. In the embodiment shown in FIG. 1, four holes 8 are provided in tray 10. One hole is located in each ledge 7. The placement of the holes is selected to be sufficiently high along the side wall of the tray to reduce the risk of clogging of the holes during the loading of the product or its shifting during the handling of the product loaded tray. The positioning of the holes in the recessed ledges 7 located in the corner areas of the side wall facilitates the air removal step as the film adheres later to these areas of the tray, thus allowing more air to be removed from the interior of the tray.

(6) FIG. 2 shows a cross-sectional view of a package 20 obtained by the vacuum skin packaging process of the invention. Once the vacuum packaging process has been completed, the film 40 forms a tight skin over the product and welds to the inner surface of the tray which is not covered by the product sealing the holes in the side wall of the tray.

(7) Package 20 comprises a rectangular tray 10, a product 30 arranged in the tray and skin film 40 draped over the product and welded to the side wall 3 and rim 4 of the tray in a skin packaging arrangement. Film 40 conforms tightly with the whole inner surface of the tray and seals holes 8 located in recessed portions 7 of side wall 3. As can be seen in FIG. 2, film 40 is welded to the rim of the tray but does not extend beyond said rim. The film is not welded to the outer surface of the tray in any place.

(8) The seal between the inner surface of the tray and the heat-sealable layer of the film is such that no air penetrates the package through the holes in the tray. Such a hermetic seal is obtained by suitably selecting the polymers making up the heat-sealable layers of both the film and the tray. For instance strong seals in a vacuum skin package can be obtained between a first LDPE or LLDPE layer and a second ethylene/vinyl acetate copolymer layer. Compared to prior art vacuum skin packages the shelf-life of products stored in the package of the invention is the same.