EP0745539B1

EP0745539B1 - Method of making an easily openable packing for an article such as a foodstuff

Info

Publication number: EP0745539B1
Application number: EP19960303802
Authority: EP
Inventors: Jean-Pierre Faivre; Guy Desveaux
Original assignee: Cryovac LLC
Current assignee: Cryovac LLC
Priority date: 1995-05-29
Filing date: 1996-05-29
Publication date: 2002-01-23
Anticipated expiration: 2016-05-29
Also published as: FR2734792A1; BR9602512A; DE69618714T2; EP0745539A1; FR2734792B1; MX9602024A; DE69618714D1; CA2177557A1

Description

The present invention relates to a method of making a packing for an article such as a foodstuff, which may be easily opened (see particularly US-A-3 641 732).
There is known packing under vacuum of a foodstuff of the type comprising film of heat-shrinkable material in the shape of a bag into which the foodstuff is placed. This unit is then brought into a machine which can create a vacuum within the bag before closing the latter by a transverse line of heat-sealing and cutting it off in the vicinity of this line. The evacuated unit then passes into a hot air tunnel or a hot water bath at a predetermined temperature to shrink the packing by heat so that it tightly encloses the foodstuff.
There is also known a foodstuff packing containing a modified atmosphere and made in a machine by which a flat film of a heat-shrinkable material is shaped into a tube by longitudinal heat-sealing while at the same time the foodstuff is inserted into this tube which is heat-sealed transversely at one end A gas of modified atmosphere comprising for example a mixture of oxygen, of carbon dioxide and of nitrogen is then fed into the film wrapping the foodstuff prior to hermetically closing the tube through transverse heat-sealing of the opposite end of the tube. Finally this unit is inserted into a tunnel containing air heated to a predetermined temperature for shrinking the film which thus tightly encloses the foodstuff.
The packings of the kind described hereinabove have the major inconvenience of being difficult to open.
The present invention proposes a packing for an article permitting easy opening thereof while preserving the vacuum or the modified atmosphere therein as long as the packing is not opened.
The invention provides a method of making a packaging for an article such as a foodstuff including the steps of wrapping the article in a film of a heat-shrinkable material, welding the film over at least one portion of its periphery and then heat-shrinking the film wherein the packaging is formed with an edge zone isolated from the rest of the film by an area where opposed faces of the film are welded to each other, and with a cut entirely within the edge zone extending inwards from one edge of the film, characterized in that the hermetically isolated zone is distinct from and located adjacent the or each welded portion of the periphery of the film whereby, on heat-shrinkage of the film around a wrapped article a tongue is formed to facilitate opening.
With the invention, when the film is shrunk by heat to engage more tightly around the article, a tongue is formed which projects outwards from the resulting package. This tongue has a cut enabling relatively easy tearing and opening of the package.
The invention will be better understood and further objects, preferred features, details and advantages thereof will appear more clearly in the course of the explanatory description which will follow, made with reference to the attached diagrammatic drawings given by way of example only illustrating two embodiments of the invention and in which:-
FIGURE 1 is a plan view of an article packaging bag for the use with the invention;
FIGURE 2 is a perspective view showing the packaging bag of Figure 1 ready to receive an article;
FIGURE 3 is a partial plan view of a packaging bag according to an alternative embodiment;
FIGURE 4 is a perspective view showing the article packed under vacuum within the packaging bag prior to heat-shrinking the packaging film;
FIGURE 5 is a perspective view showing the heat-shrunk packaging bag; and
FIGURE 6 shows the application of the invention to a packaging of the type containing a modified atmosphere.
The invention will be described as applied to a packaging for an article under vacuum but it is well understood that it also applies to any other type of article packing such as that containing a modified atmosphere as will be described subsequently.
Referring to Figures 1 to 5, the reference numeral 1 designates a packaging bag made from a synthetic film of a heat-shrinkable thermoplastic material, one end of which is hermetically closed by a transverse welded seam 2. An article 3 such as a food product is inserted into the packaging bag 1 and the whole is brought into a machine for providing the vacuum within the bag 1 and then the other end of the bag 1 is hermetically closed by a second transverse welded seam 4 and cut off to the desired length of the bag 1. The whole thus formed is then brought into a hot air tunnel or a hot water bath at a predetermined temperature for heat-shrinking the film of the bag 1 so that the latter tightly wraps the article 3.
According to the invention the packaging bag 1 in its initial state, i.e. before being heat-shrunk comprises a zone 5 hermetically isolated from the remainder of the film of the bag 1 and extending from a longitudinal edge 1a of the bag 1. As shown in particular in Figures 1 and 2, the zone 5 is hermetically isolated by welding opposed faces of the film over the whole area of the zone 5 whereas according to an alternative embodiment shown on Figure 3 this zone 5 is hermetically isolated by welding opposed faces of the film 1 along only the periphery 6 of the zone 5.
Moreover a cut 7 is made in the hermetically isolated zone 5 inwards starting from the edge 1a of the bag 1.
The hermetically isolated zone 5 is distinct from a welded portion 2, 4 of the bag 1 and this zone is located near a welded seam, in the present case the end seam 2.
The hermetically isolated zone 5 and the cut 7 are described hereinabove as being formed in the packaging bag 1 intended subsequently to receive an article 3 but they may be made during or after the steps of evacuating the bag 1 and of welding and severing the latter, the essential point being that they be formed before the step of heat-shrinking the film forming the bag 1. In addition the cut 7 may be carried out by any suitable means for example by a mechanical cutting means either automatically during the making of the bag 1 or during the steps of packing the article 3 prior to the heat-shrinking operation or manually with the assistance of a cutting tool before the heat-shrinking step.
When the unit constituted by the packaging bag 1 and the article 3 such as shown in Figure 4 is heated in order that the film of the bag 1 shrinks through heat, the hermetic zone 5 is deformed so that a tongue 8 intended to facilitate the opening of the packaging under vacuum is formed near the welded seam 2 as shown in Figure 5. This tongue 8 constituted by the welded zone 5 fully and hermetically isolates the cut 7 from the interior of the packaging so that no outward vacuum leakage in the packaging is to be feared.
To open the packaging, it suffices to pull on one portion of the tongue 8 so as to tear the packaging along the seam of heat-sealing 2.
The invention described hereinabove may also be applied to the type of packaging which contains a modified atmosphere, diagrammatically shown in Figure 6.
As is known, such packagings are made in a horizontal film forming machine from a heat-shrinkable film 1 shaped into a tube by a longitudinal weld S1 while at the same time the article to be packaged, such as for example a foodstuff placed upon a tray or a small boatshaped trough is inserted into this tube under a modified atmosphere comprising for example a mixture of oxygen, of carbon dioxide and of nitrogen. Then after withdrawal of the excess gaseous mixture the tube is closed at its two ends by two hermetic transverse welds S2 and S3, respectively, to preserve the modified atmosphere within the packaging thus made. Figure 6 shows that a zone 5 hermetically isolated from the remainder of the packaging film has been provided by welding in the same conditions as those of Figure 1 or of Figure 3 while being preferably located near one of the transverse welds S2 and S3.
When the film 1 wrapping the modified atmosphere of the corresponding article is brought into a hot air tunnel, the film would heat-shrink to enclose tightly the article and during the deformation of the film a tongue is formed in the same manner as the tongue 8 of Figure 5 to permit afterwards the easy opening of the packaging along the weld line S3.
The films used for this type of packaging are preferably of the barrier film type known per se with a core layer forming an oxygen barrier and for example based upon a copolymer of ethylene and of vinyl alcohol, or upon polyvinyl alcohol or upon polyvinylidenechloride (PVDC).
The method enabling the packaging of an article to be made,whether it is of the type made under vacuum or under a modified atmosphere is clearly apparent from the foregoing description and need not be described in detail.
The packaging which has just been described therefore permits the opening of the packaging to be facilitated while guaranteeing a total protection of the vacuum or of the modified atmosphere in the packaging as long as the packaging has not been opened.

Claims

A method of making a packaging for an article such as a foodstuff including the steps of wrapping the article (3) in a film (1) of a heat-shrinkable material, welding the film (1) over at least one portion of its periphery and then heat-shrinking the film (1), wherein the packaging is formed with an edge zone (5) isolated from the rest of the film (1) by an area where opposed faces of the film are welded to each other, and with a cut (7) entirely within the edge zone (5) extending inwards from one edge (1a) of the film, characterized in that the hermetically isolated zone (5) is distinct from and located adjacent the or each welded portion (2;4) of the periphery of the film (1) whereby, on heat-shrinkage of the film (1) around a wrapped article (3) a tongue (8) is formed to facilitate opening.
A method according to claim 1, characterized in that it comprises the step of evacuating the film (1) prior to the step of welding the film (1) over at least one portion of its periphery.
A method according to claim 1, characterized in that it comprises the step of modifying the atmosphere within the film (1) prior to the step of welding the film (1) over at least one portion of its periphery.