EP0893361A1 - Pack of objects wrapped in a plastic film, plastic film for such a pack, and method of manufacturing such a plastic film - Google Patents

Abstract

The package (1), comprising a series of objects (2) in one or more layers, is wrapped in plastics film (3) with a preferred tearing direction (D) and a zone (A) of reduced strength across it. The zone of reduced strength is made from rows of perforations (7, 9, 10) lying perpendicular to the preferred tear direction. This creates a zone with a mechanical strength which is sufficient to hold the packaged articles in position, while being sufficiently weak to allow the package to be opened at any point along the zone without the aid of a tool. The film is in the form of coextruded polyethylene/ionomer layer, and especially comprising at least one layer of a polyolefin and at least one layer of an ionic copolymer. The perforations are between 5 and 30 mm apart and cover a zone 30-100 mm wide.

Description

The invention relates to a pack of objects, such as cans, cans, bottles, etc., packed with a plastic film having a preferential direction of tearing, several objects being arranged side by side in one or more layers superimposed, the film being folded in a direction winding around the objects it encloses, means opening being provided on the film to facilitate its tear.

Such a pack is prepared in a known manner by wrapping the group of objects. Bundling consists of surround all of the objects to be packaged with a film heat-shrinkable plastic, in particular of a heat shrinkable polyethylene film. The envelope produced with the film is welded on the overlapping edges so as to form a sleeve around the objects grouped together. Objects can be tightened by example, by the effect of heat which causes the tightening of the film around the objects it envelops. The two open ends of the sleeve shrink to form an opening at the two ends of the pack oval shape, usually called the lunula.

Opening the pack and extracting objects pose a problem.

We want to avoid using a sharp tool, which is not always available immediately when we want to extract one of the objects, and which, moreover, risks damaging the objects and / or cause a poorly controlled film tear releasing more objects than desired.

A solution already proposed by EP-A-0537079 consists in providing as a means of opening tongues, for example of rectangular shape, the large dimension is oriented parallel to the preferential direction of tearing, these tabs being precut along their two long sides and a small side. Such tabs are produced by "cookie cutter" type fingerprints, in places distant from each other.

This solution, while constituting progress, has several drawbacks, including the discontinuous production of these prints, as well as the limitation of the choice of opening locations which must match these tabs.

The object of the invention is, above all, to provide a pack of objects in which the film opening means made of plastic allow easy opening and controlled burden of the pack of objects in one as many points as possible, so that allow the user to choose the most suitable for each opening.

According to the invention, the object pack is characterized by the fact that the means for opening the plastic film include a continuous area attenuation oriented transversely to the preferential direction of tearing, and forming a belt that surrounds the pack, this area weakening with mechanical strength strong enough to withstand tensile forces exerted on the film to enclose the objects, but low enough to allow film opening without tools at any point in the area.

Advantageously, the continuous weakening zone is perpendicular to the preferred direction of tearing.

Preferably the continuous weakening zone includes at least one line of perforations, particular regularly spaced.

Advantageously, the continuous weakening zone includes a central line of perforations surrounded by two parallel lines of perforations, away from the center line, and in which the distance between two successive perforations is greater than the distance between two perforations successive lines of the central line. Preferably the distance between two successive perforations of the lines is equal to twice the distance between two perforations in the center line.

The perforations of the two outer lines are advantageously aligned with a line perforation central in a direction orthogonal to the line central. The patterns created by the perforations have thus the shape of an I.

The plastic packaging film is preferably a two-layer film whose direction preferential tear is perpendicular to the extrusion direction. The film is in particular a film coextruded ionomer polyethylene. Such a film can be consisting of at least one layer of polyolefin and at minus one layer of an ionic copolymer.

Punch lines may be distant from 5 to 30 mm, over a width of 30 to 100 mm.

The invention also relates to a film in plastic material for wrapping of pack objects, this film with a preferred direction of tearing and being characterized by the presence of a continuous weakening zone oriented transversely, especially perpendicular to the direction preferential tearing.

This continuous weakening zone includes at least minus a line of perforations spaced regularly, and preferably at least three lines of perforations, know a center line where the perforations are less set apart only in two outer lines parallel to the central line and located on either side, the perforations in the center line and lines exterior preferably making I-patterns.

In the case of a plastic film of which the preferred direction of tearing is perpendicular to the direction of extrusion, a process of film preparation consists in making the perforations when unwinding or winding the front film the packaging, along its entire length, in particular at extrusion, rewinding, printing or on the shrinkwrapper, by a device made up of rollers needles with a brush-like counterpart cylindrical. The plastic film to be perforated scrolls between the needle roller and its counterpart.

This operation can be repeated across the width of the film, in consideration of the end use, in order to create several continuous parallel weakening zones to each other, in the direction of the length of the movie.

La Figure 1 du dessin est une vue en perspective schématique d'un pack d'objets selon l'invention.

La Figure 2, enfin, est une vue de dessus, à plus grande échelle, d'une partie du pack de la Figure 1.

The invention consists, apart from the arrangements set out above, of a certain number of other arrangements which will be more explicitly discussed below in connection with a particular embodiment described with reference to the attached drawing, but which is in no way limiting.

Figure 1 of the drawing is a schematic perspective view of a pack of objects according to the invention.

Figure 2, finally, is a top view, on a larger scale, of part of the pack of Figure 1.

Referring to Figure 1 of the drawing, we can see a pack 1 of objects 2 made up of boxes of canned, cans or the like, wrapped with film 3 made of plastic, generally transparent. Several objects are arranged side by side, following two horizontal layers superimposed in the example shown in Figure 1. A plate 4, in particular of cardboard, separates the two tablecloths.

Film 3 has been folded in one direction of winding E to form a sleeve around the burden constituted by the objects 2. The edges of this sleeve perpendicular to direction E are welded one to the other.

Generally, the arrangement of objects forms globally a rectangular parallelepiped whose large sides are perpendicular to the winding direction of the film. The open ends of the sleeve made around the packaging correspond to the small sides of the parallelepiped.

The film 3 is subjected to a heat treatment causing it to tighten around 2 objects so that the open ends of the sleeve tighten also to form oval openings 5, or lunula, appreciably in the center of each small face end of the parallelepiped.

Film 3 has a preferred direction tear D parallel to the long sides of the parallelepiped.

The film 3 is advantageously constituted by a film comprising at least two layers. The film is formed at least two thermoplastic resins, and the management preferential tear D of the film is substantially perpendicular to the extrusion direction E which is the same as the winding direction. The film is in particular formed of at least one polyolefin layer and at least one layer of an ionic copolymer. The movie is, for example, an ionomer coextruded polyethylene film. A film according to EP-A-0537080 is particularly suitable.

Pack 1 includes opening means formed by a continuous zone A of weakening of the film 3 oriented transversely, preferably perpendicular to the preferred direction of tear D of the film. Zone A forms a belt 6 which surrounds the pack on four sides of the parallelepiped.

In the example shown in Figure 1, a only belt 6 is provided, mid-length of the large sides of the parallelepiped, that is to say halfway down the film 3. It is possible, as required, to plan several parallel belts 6, spaced along the film width 3.

The continuous weakening zone A is thus oriented in the direction of unwinding of the film reel 3.

Zone A includes a central line 7 of perforations 8, regularly spaced, aligned orthogonally to direction D.

Two outer lines 9, 10 of perforations are located on either side of the center line 7 parallel to it, equidistant, and have perforations 11a, 11b. The distance h between the lines of perforations is preferably between 5 and 30 mm. The width L of the weakening zone is preferably between 30 and 100 mm. This width L corresponds to the distance between the outer edges of the perforations in lines 9 and 10.

The distance f between two perforations 11a or 11b outer lines 9 and 10 is greater than the distance g of two successive perforations 8 of the line central 7. In particular, the distance f is double of the distance g (f = 2 g).

The perforations 11a, 11b of the two lines outside are aligned with a perforation 8 of the central line 7 in a direction orthogonal to this central line.

With f = 2 g, an opening 8 on two is not surrounded by openings 11a, 11b as visible on the Figure 2. The patterns created by these perforations have a I-shaped, lying horizontally in Fig. 2.

The example given of three parallel lines of perforations, with a central line in which the number of perforations per unit of length is double, is not limiting. We could plan on each side of the center line two or more lines outer with more spaced perforations.

The perforations 8, 11a, 11b can be made during the extrusion of the film 3, or else during its rewinding, either in printing, or in the device (shrink wrapper) to make the pack.

The perforations are preferably made by a device (not shown) consisting of rollers hot or cold needles, with a counterpart in cylindrical brush shape on which the movie. Punch needles have a diameter about 1 mm and a length of about 10 mm and are mounted on rotating shafts, the film to be perforated running between the needle roller and its counterpart.

The precut formed by zone A is thus performed continuously.

In Figure 2 are shown the contours circulars 12 of cans of the same diameter tangent to each other and defining between them empty spaces 13 in the shape of four stars branches; the contour centers 12 are located at vertices of squares having a side length equal to contour diameter. Preferably zone A covers a succession of empty spaces 13, and the central line 7 of perforations pass appreciably in the middle of these empty spaces.

We combine the arrangement of objects in the pack and the distribution of zone (s) A over the film width so that zone (s) A covers (s) a succession of empty spaces 13. Thus, in the case where zone A is provided at mid-width of the film, the number of objects in a row orthogonal to direction E is an even number.

Opening film 3 to remove one or more several cans are made in the same way next.

We press with a finger at a place chosen from zone A, for example at a vacuum 13 formed between the boxes tangent to each other and wrapped, to initiate a tongue J (Fig. 2) whose width is roughly twice the distance f between two perforations 11a or 11b of the lines outside. The edge of the tab corresponding to the center line 7 will be cut. Then just grab this edge and pull tab J in the direction of the arrow T1 or T2, that is to say in the direction D preferential tearing, perpendicular to perforation lines 7,9,10 for opening by cutting, in film 3, a band K whose width corresponds to that of tongue J. Traction on the tongue J is therefore exercised in a direction transverse, advantageously perpendicular, to the direction of the weakening zone A forming belt, not along the direction of this zone A materialized by the lines of perforations 7, 9, 10.

The band K has a width substantially double of the interval f between two perforations 11a or 11b and, in practice, between 10 and 60 mm.

Heat shrink film 3 undergoes stresses thermal during shrinking or shrinking. The distance between the perforations 8, 11a, 11b as well as their diameter is chosen according to mechanical characteristics of film 3, in order to avoid formation of holes in the film which would join under the effect of thermal stresses, while allowing weakening of the area considered A which will allow prime the opening tabs J.

Printing can be done on the area attenuation A, in particular on the lines of perforations in order to materialize them and make them more visible. This print will give indications on the movements to be carried out to initiate and propagate tearing of the film 3 from the perforations 8, 11a and 11b.

The solution of the invention is of great ease of implementation allowing the adaptation of the precut at any stage of production / processing / use of the product. This solution is complementary to the properties of a film 3 to good transverse tear.

The invention ensures continuous production of the weakening zone A while preserving the integrity of the heat-shrunk burden relative to a discontinuous process with "cookie cutter" type imprint.

Claims (14)

Pack of objects, such as cans, cans, bottles, etc., wrapped with a film (3) of material plastic with a preferred direction of tearing (D), several objects (2) being arranged side by side side by side in one or more overlapping layers, the film being folded in a winding direction around objects which it encloses, means of opening being provided on the film to facilitate tearing, characterized by the fact that the means for opening the plastic film (3) includes an area continuous weakening (A) oriented transversely to the preferential direction of tearing (D), and forming a belt (6) which surrounds the pack, this area weakening (A) with mechanical strength strong enough to withstand tensile forces exerted on the film to enclose the objects, but low enough to allow film opening without tools at any point in the area. Object pack according to claim 1, characterized by the fact that the continuous weakening zone (A) is perpendicular to the preferred direction of tearing (D). Pack of objects according to claim 1 or 2, characterized by the fact that the area continues attenuation (A) comprises at least one line (7) of perforations (8). Object pack according to one of the claims previous, characterized in that the area continuous weakening (A) includes a line central (7) of perforations surrounded by two lines parallel (9,10) of perforations, spaced from the line central, and in which the distance (f) between two successive perforations is greater than the distance (g) between two successive perforations (8) of the line central. Object pack according to claim 4, characterized by the fact that the distance (f) between two perforations successive lines (11a; 11b) of the outer lines (9,10) is equal to twice the distance (g) between two perforations in the center line. Object pack according to claim 5, characterized by the fact that the perforations (11a, 11b) of the two outer lines (9,10) are aligned with a perforation (8) of the central line along a direction orthogonal to the center line. Object pack according to one of the claims previous, characterized by the fact that the film plastic packaging material (3) is a two-layer film whose preferred tearing direction (D) is perpendicular to the direction of extrusion (E). Object pack according to claim 7, characterized by the fact that the film (3) is a polyethylene film coextruded ionomer, in particular consisting of at least a layer of polyolefin and at least one layer of a ionic copolymer. Pack of objects according to one of claims 4 to 6, characterized by the fact that the perforation lines are 5 to 30 mm apart, 30 to 30 mm wide 100 mm. Object pack according to one of the claims previous, characterized in that the area weakening (A) of the film covers a succession empty spaces (13) between the objects (2). Object pack according to one of the claims previous, characterized in that the area attenuation (A) of the film is provided at mid-width of the film (3). Plastic film for wrapping objects a pack according to one of the preceding claims, having a preferred direction of tear (D), characterized in that it presents a continuous weakening zone (A) oriented transversely, in particular perpendicularly, to the preferential direction of tearing (D). Plastic film according to claim 12, characterized by the fact that the area continues attenuation (A) comprises at least one line (7) of regularly spaced perforations, and in particular three lines of perforations (7,9,10), namely a line central (7) where the perforations (8) are less apart only in two outer lines (9,10) parallel to the central line and located on both sides. Process for preparing a plastic film according to claim 12 or 13, characterized in that that the perforations (8,11a, 11b) are made during the unwinding or winding of the film (3) before the packaging, along its entire length, in particular at extrusion, rewinding, printing or on the shrink wrapper.

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