EP0665173A1

EP0665173A1 - Easy-to-open heat shrunk package

Info

Publication number: EP0665173A1
Application number: EP95300136A
Authority: EP
Inventors: Yanase Mitsuyuki
Original assignee: GRACE JAPAN KK
Current assignee: WR Grace and Co Conn
Priority date: 1994-01-11
Filing date: 1995-01-11
Publication date: 1995-08-02
Also published as: WO1995018753A1; NZ270317A; CN1135741A; CA2139901A1; TW262452B; BR9500068A; KR960705724A; AU1015595A; JPH07242266A

Abstract

To provide an easy-to-open heat-shrunk package, a package is prepared by wrapping an article 1 with a heat-shrinkable film 2 which is heat-sealed and cut off along the edge portions 3, 4, 3' and subsequently heat-shrunk but with a tab 6 in at least one position in the sealed portions of said film as an aid in opening the package. The tab 6 is formed by making a cut 8 in an edge portion of the film to form a cut seal, and thereafter heat-shrinking the film. If desired, a marker line 7 serving as an aid in opening the package may be provided on or around the tab.

Description

The present invention relates to an easily openable heat-shrunk package.
One of the packaging methods in common practice today is heat shrink packaging, in which an article is wrapped with a heat-shrinkable synthetic resin film, for example in the form of a bag, or a centre-folded (double) sheet, or the like, and the film is heat-sealed and cut off along the edge portions and subsequently heat-shrunk to provide a tight package. Heat-shrunk packaging is gaining increased popularity for two major reasons: firstly, it adds to the aesthetic appeal of the packaged articles or goods, thereby enhancing their commercial value; secondly, it permits easy packaging of articles even if they have complex shapes.
On the other hand, heat-shrunk packaging has a serious limitation in that the package is difficult to open. Various methods have so far been proposed with a view to overcoming this problem and facilitating the opening of packages that are made of heat-shrunk films. They include: i) forming a line of perforations in a specified position on a heat-shrinkable film so that one can open the package by tearing it along said line; ii) making a U-shaped hole in a specified site on the film and attaching a paper seal over the hole to form a seal label that serves as an aid in opening the package; and iii) additionally attaching a so-called "opening tape".
However, these conventional methods have their own limitations.
In the first approach (i), the perforations will grow in size upon heat treatment of the heat-shrinkable film and contaminants can potentially get into the package through the holes, thereby reducing the commercial value of the contents. In some cases, the perforations may rupture during handling.
The second approach (ii) needs a special apparatus for opening the U-shaped hole and, furthermore, the use of paper seals adds to the production cost.
The third approach (iii) has the inherent disadvantage of being cumbersome.
What is more, the three conventional methods have one serious problem in common; that is, they are extremely difficult to apply to the L-type sealer packaging machine which uses doubled (centre-folded) heat-shrinkable films.
The present inventors conducted intensive studies in order to develop an easy-to-open heat-shrunk package that (a) was free from the above-mentioned problems of the prior art, (b) retained the advantages of the heat shrink package to a satisfactory extent, (c) was inexpensive and easy to open, and yet (d) was applicable to the L-type sealer packaging machine using doubled heat-shrinkable films with which no complete solution had been found to the difficulty in packaging opening. As a result, the inventors found that when a cut was made in at least one position in the edge portions of a heat-shrinkable film to form a cut seal, followed by heat shrinking of the film, a tab (serving as an aid in package opening) could be formed very easily in an area of the sealed and cut-off portions of a package made of the heat-shrunk film. The present invention has been accomplished on the basis of this finding.
The present invention provides a packaging method comprising placing an article in an envelope of heat-shrinkable film, sealing superposed portions of said film at an edge region to seal the envelope, and heat-shrinking the envelope on to the article, characterised by forming a cut in the sealed portion of superposed film, substantially before the heat-shrinking step, to form a tab at at least one location on the heat-sealed superposed film portions to serve as an aid in opening the package.
Preferably a marker line is defined on or around the cut in the film seal and/or the resulting tab in the finished package.
In order that the present invention may more readily be understood the following description is given, merely by way of example, with reference to the accompanying drawings, in which:-

FIGURE 1 is an illustration showing an embodiment of a packaging method according to the present invention;
FIGURE 2 is a perspective illustration showing an embodiment of a package formed by the method of the present invention;
FIGURE 3 is an illustration of the package of Figure 2, seen from the left-hand side;
FIGURE 4 is an illustration showing another embodiment of a packaging method according to the present invention;
FIGURE 5 is a perspective illustration of another embodiment of a package; and
FIGURE 6 is an illustration of the package of Figure 5 seen from the left-hand side.

Figure 1 is a perspective view showing an article 1 wrapped with a heat-shrinkable film 2. In the illustrated case, the heat-shrinkable film 2 is centre-folded (doubled) and the article 1 is wrapped with the doubled film 2, followed by heat-sealing and cutting off at edge portions 3, 3' and 4 of the film.
Thereafter, the film is heat-shrunk to complete a tight package.
In accordance with the invention, before the heat shrinking step, a cut 5 is made in at least one position in the edge portions of the film, in this case adjacent a corner of the film envelope and parallel to the edge 4, whereby a cut seal 8 is formed. The cut 5 may be formed at any stage of the process before shrinking; it may be formed during or after wrapping the article with the heat-shrinkable film or, alternatively, the cut may be formed simultaneously with the step of heat-sealing and cutting off along the edge portions of the film. The cut 5 may be formed as the heat shrinking step starts, but must be complete before the film shrinks.
Almost all conventional methods, such as heat sealing and impulse sealing, that are commonly employed in producing heat-shrunk packages may be used in heat-sealing and cutting off the edge portions of heat-shrinkable films. In the heat sealing method a heated element, typically in the form of a frame, is pressed against the edge portions of the heat-shrinkable film so that the edge portions are fused, sealed and cut off. In the impulse sealing method, the heated element is replaced by electric impulses that are applied to fuse, seal and cut off the edge portions of the heat-shrinkable film.
The way in which the cut 5 is made at at least one position in the portions of the heat-shrinkable film varies depending on the specific method used for heat-sealing and cutting off the film along the edge portions. If the heat-sealing bar method is to be adopted, a heating element for forming a cut seal is attached to a selected portion of the heating bar element for sealing the edge portions of the film. In this way, a cut seal can be formed simultaneously with the step of heat-sealing the film along the edge portions.
In the next step the film is heated overall, to cause it to shrink, thereby forming a tight package as shown in Figure 2. Figure 3 shows how the tight package looks if seen in elevation from the left-hand side. In the process of heat shrinking the film, the cut seal 8 formed in the one of edge portions 3 of the film will deform in such a way that a tab 6 forms in the selected area of the film that has been heat-sealed and cut off along the edge portions. The size and shape of the tab 6 to be formed can be determined empirically by adjusting the shape and length and position of the cut 5 to be formed in at least one position in the edge portions of the film, as well as by adjusting the width of the cut seal to be formed.
The heat-shrinkable film can be thermally shrunk by any conventional methods known in the art, such as by passing the package through a heated air shrunk tunnel.
The thus produced package has a pleasing and attractive appearance that is not significantly different from the conventional heat-shrunk packages except that it has the tab 6 as an aid in package opening. To open the package, one may simply pull the tab 6 along the film edge portion 4 which was heat-sealed and cut off.
If desired, a marker line serving as a supplemental aid in package opening may be defined on or around the tab 6. The marker line thus described gives a clear indication of the position of the tab 6, thereby providing greater ease in the package opening operation.
Figures 4 to 6 show a marker line 7 which can be provided in the cut seal portion of the film, by various methods that are readily understood by the skilled artisan. In one method, a printing device is incorporated as part of the packaging machine and at the same time as the cut 5 is made in part of the heat-sealed portion 4 of the film, the marker line 7 is printed on or around the thus formed cut seal 8. If desired, the making of the cut 5 in the heat-sealed portion 4 of the film may be preceded by the step of providing the marker line 7 on or around the area where the cut seal 8 is about to be formed in that heat-sealed portion. The film may even be pre-printed with the marker lines 7 of several packages.
Alternatively, the marker line 7 may be formed on or around the cut seal 8 which has already been formed by making the cut 5 in the heat-sealed portion 4 of the film (see Figure 4). After the cut seal 8 has been formed and the marker line 7 provided, by one of these methods, the film is heat-shrunk to produce a package that has the marker line 7 on or around the tab 6 which serves as an aid in opening the package (see Figures 5 and 6).
In still another method, the cut 5 is made in the heat-sealed portion 4 of the film, which is then heat-shrunk to produce a package having the tab 6. Thereafter, the marker line 7 may be provided on or around the tab 6.
Any inks that are known in the art may be used to print the marker line 7 and, to name only one example, a commercial quick-drying ink may be used.
To open the thus produced heat-shrunk package, the consumer only need pull the tab 6 in the direction of the marker line 7 which clearly indicates the position of the tab 6.
The drawings show only the embodiment where a box-shaped article is wrapped with a doubled film. However, it will be apparent to the skilled artisan that the packaging methods of the invention are applicable to spherical, cylindrical, prismatic and any other shapes of articles to be wrapped. In all embodiments of the invention, a cut is made in at least one position in the superposed edge portions of a heat-shrinkable film to form a cut seal and the film is subsequently heat-shrunk, to cause a tab to result from the cut seal.
As described above, the packages, and the methods of their preparation, retain the inherent advantages of heat-shrunk packages such as good hermeticity and aesthetic appeal and yet they render heat-shrunk packages easily openable in a very simple and economical manner without employing any special equipment or additional members such as paper labels. The industrial benefits of the invention are obviously great.

Claims

A packaging method comprising placing an article (1) in an envelope (2) of heat-shrinkable film, sealing superposed portions of said film at an edge region (3, 4, 3') to seal the envelope, and heat-shrinking the envelope (2) on to the article (1), characterised by forming a cut (5) in the sealed portion of superposed film, substantially before the heat-shrinking step, to form a tab (8) at at least one location on the heat-sealed superposed film portions to serve as an aid in opening the package.
A method according to claim 1, wherein the cut (5) is formed parallel to a sealed edge (4) of the package.
A method according to claim 1, wherein the package is rectangular and the cut (5) is formed in one edge (3) of the sealed perimeter of the film envelope adjacent to a corner of the rectangle.
A method according to claim 1, 2 or 3, and including the step of cutting said superposed film portions and forming a seal of the cut portions to close and seal the envelope.
A method according to any one of claims 1 to 4, and including the step of defining a marker line (7) on said superposed sealed film portions (3, 4, 3') adjacent said cut (5).
A pack according to claim 5, wherein said marker line (7) is parallel to said cut (5).
A method according to any one of claims 1 to 6, wherein said envelope is formed by sealing various edges of a package formed of centre-folded film with the article placed between the folded-together plies of the film.