EP0142455B1 - Bag of synthetic flexible material having a tab of heat-sealable foil to open it - Google Patents

Abstract

1. Sachet of flexible synthetic material of the type obtained by suitable folding of a single film of synthetic material, or from two strips of film, and welds forming the different sides of the sachet, comprising, along one weld line and in line with the region of the sachet where the pouring opening must be formed, at least one narrow strip of a bilateral thermo-sealing film interposed between the two film thicknesses connected by the said weld line, characterised in that the narrow strips (16) possess in their central part a curvilinear section possessing a high point (17) outside the weld line.

Description

The present invention relates to a flexible plastic bag of the type obtained by adequate folding of a single film of synthetic material, or from two strips of film, and welds determining the different sides of the bag, comprising, along '' a weld line and at the point of the bag where the pouring opening must be determined, at least one strip of a two-sided heat-sealing film interposed between the two film thicknesses connected by said weld line (known from document BE-A-547 093).

Sachets of this type are well known. They were for example, and not limited to, the subject of French patent applications FR-A-2 314 112, FR-A-2 417 445 and FR-A-2 474 457 in the name of the applicant.

They can be obtained by multiple methods, which essentially fall into two categories, depending on whether the path of the film and of the bags thus formed is horizontal or vertical.

A horizontal type shaping machine is described for example in French patent application FR-A-2 474 457 in the name of the applicant.

A vertical type shaping machine is described for example in French patent FR-A-2,097,845.

For what follows, reference will be made to a process of the “vertical” type, but it will be understood that the invention should not be limited neither to the processes of this type, nor to the modes of implementation described in the aforementioned patents.

Bags of synthetic material of this type have been the subject of numerous developments and researches essentially focused on the problems of gripping on the one hand and stability in vertical position on the other hand, independently of course of researches as to the nature of the film itself.

Sachets of this type, intended in particular for packaging beverages or spring water, are however designed to condition a volume of liquid of one liter or more.

It is therefore imperative that they can be opened easily, but above all in a manner allowing multiple use of the bag. Cutting the bag to allow the pouring of its contents must therefore be able to be carried out by the user correctly, regardless of the user.

In existing sachets, the cutting is carried out essentially by scissors, which therefore does not eliminate the risk of random cuts poorly performed. It is thus necessary to have on hand any means to open the bag, which is impractical during outdoor use (hiking for example).

Thus, patent BE 547 093 has already proposed a sachet comprising a traction strip inserted between the two thicknesses of the sachet, a strip having a determined resistance to tearing for the opening of the sachet. This device is however imperfect insofar as it requires a significant tensile force and where, projecting, it can be accidentally triggered.

French patent 1,417,040 describes a device of identical type, which has the same drawbacks and is, in some of its embodiments, complex to industrialize.

There is therefore a need for sachets of the type described above which are provided with the manufacture of opening means ensuring on the one hand an easy manual opening and on the other hand a perfectly localized opening.

According to the invention, this result is obtained with a flexible plastic bag of the type obtained by adequate folding of a single film of synthetic material, or from two strips of film, and welds determining the different sides of the bag, comprising, along a weld line and at the point of the bag where the pouring opening must be determined, at least one strip of a two-sided heat-sealing film interposed between the two thicknesses of the film connected by said line welding, characterized in that the strips have at their central part a curvilinear section having a high point outside the weld line.

The strip of heat-sealing film can be inserted in a vertical seal (vertical side of the bag), horizontal (upper edge of the bag) or even overlap on two welds, vertical and horizontal, in an upper corner of the bag.

This determines a preferential peel-off zone consisting of the heat-sealed portion which can be easily peeled by the user, without however calling into question the strength and hygiene properties of the sachet.

The heat-sealing film may for example consist of an adhesive varnish placed on each side of an aluminum or other support, the varnish placed on each of the faces possibly being of a different nature. The film must of course be food grade.

According to an alternative embodiment of the invention, the bag will further include near the opening area, a reversible adhesive which will allow the bag to be closed after a first use.

• la figure 1 est une vue schématique de la mise en oeuvre du procédé de l'invention sur machine à cheminement vertical,
• la figure 2 illustre un sachet avec film thermoscellant biface unique sur ligne de soudure horizontale,
• la figure 3 illustre un sachet avec double film thermoscellant biface sur ligne de soudure horizontale,
• la figure 4 illustre un sachet conforme à l'invention avec film thermoscellant à découpe curviligne,
• la figure 5 illustre un sachet avec film thermoscellant biface unique sur ligne de soudure verticale,
• la figure 6 illustre un sachet avec double film thermoscellant biface sur ligne de soudure verticale,
• la figure 7 illustre un sachet avec film thermoscellant en coin,
• la figure 8a illustre un sachet avec adhésif réversible, en position d'ouverture,
• la figure 8b est la même vue que 8a, en position de fermeture.

The invention will be better understood using the description below made with reference to the appended drawings in which:

• FIG. 1 is a schematic view of the implementation of the method of the invention on a machine with vertical tracking,
• FIG. 2 illustrates a bag with a two-sided heat-sealing film on a horizontal welding line,
• FIG. 3 illustrates a bag with a double biface heat-sealing film on a horizontal welding line,
• FIG. 4 illustrates a bag in accordance with the invention with a heat-sealing film with a curvilinear cut,
• FIG. 5 illustrates a bag with a two-sided heat-sealing film on a vertical welding line,
• FIG. 6 illustrates a sachet with a double-sided heat-sealing film on a vertical welding line,
• FIG. 7 illustrates a bag with corner heat-sealing film,
• FIG. 8a illustrates a bag with reversible adhesive, in the open position,
• Figure 8b is the same view as 8a, in the closed position.

We will first refer to Figure 1, in rappe lant that the invention is not limited to an implementation on a vertical routing machine.

On a machine of this type, a film (1) is wound on a mandrel (2) for forming and filling the individual bags formed after vertical sealing and bottom sealing.

The vertical welding is carried out in itself well known manner, by a welding device such as (3), the intermittent operation of which is linked to the device for advancing the film downwards, itself produced by belts from a drive motor.

A sheath (4) is thus obtained, the bottom of which is welded, at the same time as the upper edge of the following bag, by means of a horizontal welding device (5). The cutting is carried out between the two welds by a mechanical cutting station (6).

Interposed between the two ends of the overlapping film at the vertical weld a strip (7) of the heat-sealing film which is fed from a reel (8) which unwinds step by step under the action of a drive motor. A cutting station (9) makes it possible to cut the strip at the vertical weld. The strip being thus inserted between the two ends of the film, the weld secures them.

From there, we arrive at the configurations which are illustrated in Figures 2 to 7.

In Figure 2, the welding was carried out with a coil and a rectilinear welding device. The heat-sealing film (10) is, as indicated above, pinched in the vertical weld (11) produced by the station (3). At the welding station (5), we welded horizontally to the strip (10).

The cut made at the horizontal cutting station, between the two sealing bars (5) leaves two free walls (12, 13) between which the film (10) projects. The opening is done by peeling at this level.

In Figure 3, there is shown the same case as in Figure 2, a double strip (14, 15) interposed in the same way on horizontal weld. In both cases, the strip or strips are pinched between the horizontal (10) and vertical (11) welds.

The two strips are inserted in the same way as one, from two reels such as (8), with two drive devices. The two strips can also be supplied from the same suitable coil.

The application of the welding heat at the level of the strips (10, 14, 15) causes the heat-sealing of this zone on the facing portions, film or other strip.

In Figure 4, there is shown an embodiment in which the strip or strips (16) have a high point (17) outside the weld line, which ensures even greater reliability in terms of the precision of the opening. . Such a strip can be placed on a horizontal or vertical weld.

In the embodiments of FIGS. 5 and 6, the strips are on vertical weld, the horizontal weld taking place above said strips. The opening and therefore the pouring are done on a vertical edge of the bag.

In the variant of FIG. 7, the strip or strips (18) will be at the junction of a vertical weld line (19) and a horizontal line (20). The peeling will therefore be done in the upper corner of the sachet opposite the handle, if it has one.

Advantageously, as shown in FIGS. 8a and 8b, there will be disposed near the strips (10, 14, 15, 18) a reversible adhesive (21) which makes it possible to obtain a reversible security closure, after a first use of the sachet. To do this, the grip edges of the strip (s) are folded against one of the walls so as to close the opening, and they are immobilized in this position thanks to the reversible adhesive, as illustrated in FIG. 8a.

Claims (2)

1. Sachet of flexible synthetic material of the type obtained by suitable folding of a single film of synthetic material, or from two strips of film, and welds forming the different sides of the sachet, comprising, along one weld line and in line with the region of the sachet where the pouring opening must be formed, at least one narrow strip of a bilateral thermo-sealing film interposed between the two film thicknesses connected by the said weld line, characterised in that the narrow strips (16) possess in their central part a curvilinear section possessing a high point (17) outside the weld line.

2. Sachet according to claim 1, characterised in that it comprises, in the vicinity of the opening zone, a reversible adhesive closure piece (2).

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