WO1995030600A1

WO1995030600A1 - Device for easy and controlled opening of a flexible bag and bag so obtained

Info

Publication number: WO1995030600A1
Application number: PCT/FR1995/000614
Authority: WO
Inventors: François Chaygneaud-Dupuy
Original assignee: Chaygneaud Dupuy Francois
Priority date: 1994-05-10
Filing date: 1995-05-10
Publication date: 1995-11-16
Also published as: FR2719826A1

Abstract

Device for easy and controlled opening of a flexible bag (2, 2', 2') consisting of at least one plastic film providing mechanical resistance and impermeability. The opening device is characterized by the combination of, firstly, a weakening of the mechanical characteristics of one of the plastic films in one or more suitable distinct areas (A) of the outer side of the bag wall and, secondly, a cut label (1, 1', 1') secured to the outer side in the region of one or more of said areas (A). The label made of a material (5), which is more rigid than the material of the bag wall, is covered by an adhesive film (8) for securing to the bag and includes at least one precut line (10, 27) of a suitable shape facing one or several of the weak regions of said bag. Application for opening bags.

Description

EASY AND CONTROLLED OPENING DEVICE OF A FLEXIBLE BAG

AND BAG THUS OBTAINED

The present invention relates to flexible bags made up in particular of a complex formed of at least two superimposed plastic films and providing both mechanical strength and sealing against various products which can be stored inside said bags, in particular liquid or pulverulent food products for example.

Such complexes consisting, for example, of a polyester film associated with a polyethylene film or a metallized polyester associated with a polyethylene film, exhibits the qualities of mechanical strength and sealing suitable for constituting storage containers and preservation in particular of foodstuffs, but having difficulties in opening the sachets thus formed, because the complexes in question are particularly • difficult to tear if one does not have suitable tools such as knife or scissors.

Attempts have been made to create, in suitable areas of the walls of such sachets, weakenings by various techniques aimed at locally reducing the mechanical resistance of at least one of the plastic films, the polyester film for example, in order to allow in these weakened areas the tearing of the complex using the fingers. The result is however not optimal because, on the one hand, the tearing of the complex causes a stretching of the plastic films which notably deforms the sachet at the place of its opening, on the other hand, the tearing lips are formed in an uncontrolled manner without a clear and perfectly predetermined guideline and, finally, the sealing is systematically achieved over the entire treated area. In addition, such openings do not lend themselves absolutely to a temporary reclosure of the partially emptied sachet, capable of ensuring a certain seal with respect to the outside air, due to the flexible elastic nature of the wall of the sachet. The present invention aims to overcome these various drawbacks by proposing a device allowing the easy and controlled opening by tearing of a flexible bag with a wall formed in particular of a complex of the type mentioned above, but also of a simple polyethylene film. or polypropylene for example, as well as, optionally, the temporary closing of the opening orifice thus practiced.

To this end, the invention relates to an easy and controlled device for opening a flexible bag formed using at least one plastic film ensuring mechanical strength and sealing, characterized in that it consists of the combination, on the one hand, of a weakening of the mechanical characteristics of or one of the plastic films in one or more appropriate separate zones of the external face of the wall of the sachet and, on the other hand, a pre-cut label attached to said external face, up to the abovementioned zone or zones, said label being made of a material relatively rigid compared to the material of the wall of the bag, covered with an adhesive film of attachment to the bag and provided with at least one pre-cut line of suitable shape and facing the weakening zone or zones of said bag.

Such a device makes it possible to initiate the tearing of the film or of the complex at the location or at one of the locations of the pre-cutting line lying opposite a weakening zone, the tearing propagating in the film or the complex opposite said pre-cutting line which channels it according to an absolutely clear opening and without any local stretching or elongation of the plastic film (s), perfectly held by the label stuck on the sachet.

By thus applying a label of the type described in French patent application FR-93 07720 filed in the name of the Applicant, for example flush with the upper transverse sealing line of a flexible bag, straddling a fold of the bag, we can easily produce in the sachet an opening with a perfectly clear outline delimited by a pre-cut line formed in said label, without otherwise affecting the sealing of the sachet since the areas of weakness of the plastic film are either covered by the adhesive film of the label, either made in the upper transverse sealing area.

The opening being clean and made in the relatively rigid label with respect to the sachet, a kind of pouring spout is thus obtained facilitating the emptying of the contents of the sachet.

The shapes and dimensions of the opening thus produced by tearing can be pre-determined according to various configurations, by carrying out suitable pre-cutouts in the label and possibly the realization of zones of weakening of the plastic film of the sachet opposite by example of inflection points of the pre-cut line (s) formed on said label, which makes it possible to proceed with tearing, as desired, at one of several points of the pre-cut line or lines of the weakened zones of the wall of the bag, these areas being of course arranged opposite said points.

According to an alternative embodiment of the device of the invention applied to a flexible bag with vertical sealing in the position of use, the label is arranged astride a horizontal fold of the bag, flush with said sealing, and has a line pre-cutting straddling said horizontal fold and the ends of which are opposite one another flush with the seal on the two opposite faces of the bag.

In this embodiment, the opening of the bag is preferably effected by tearing at the level of the crossing of the horizontal fold and the pre-cutting line, the wall of the bag being weakened at least at the level of said crossing. Furthermore, by an appropriate constitution of the label, for example by using as a material a complex formed of a polyester film and of an aluminum film itself coated with an adhesive film for fixing the label on the flexible bag, a label is produced which, on the one hand, ensures a perfect seal, only the polyester film being pre-cut, the aluminum film reinforcing the seal to the right of the weakening zones practiced in the plastic film of the bag and, on the other hand, allows the bag to be closed by folding the label over itself, the latter retaining the fold or folds applied, thanks to the aluminum foil and to a series of grooves parallel pre-cuts, made for this purpose in the outer polyester film of the label.

Advantageously, the weakening zones formed in the plastic film of the sachet, in particular a polyester film, are produced by the joint local application of pressure and ultrasound, using a sonotrode with a surface constituted by asperities so as to print in said plastic film, in said areas, a multitude of small craters.

Other characteristics and advantages will emerge from the description which follows of embodiments of the device of the invention, description given by way of example only and with reference to the appended drawings in which:

Figure 1 is a front view of a label according to the invention, for a vertical side seal bag;

- Figure 2 is a view of the edge of the label;

Figure 3 illustrates the label in place on a vertical seal bag;

Figure 4 is a front view of a label according to the invention, intended for a sachet with horizontal lateral sealing;

Figure 5 illustrates the label of Figure 4 in place on a horizontal sealing bag; Figure 6 shows another label according to the invention for sachets of the coffee powder type;

Figure 7 illustrates the formation of a weakening zone of a complex using a sonotrode according to the invention.

Figure 8 is an enlarged sectional view of the complex of Figure 7 after completion of the weakening, and - Figures 9 and 10 illustrate an alternative embodiment of label with reclosing tab.

In Figure 1, there is shown in 1 a first type of label according to the invention intended to be applied to a flexible bag 2 (Figure 3) with vertical seal 3 in the position of use.

The label 1, of generally rectangular shape, is applied astride the upper horizontal fold 4 of the bag 2 and flush with the seal 3.

The sachet is of known structure and formed from either a single film, for example polyethylene or polypropylene, or from a complex formed pr example of a polyester film associated with a polyethylene film or a metallized polyester film associated with a polyethylene film. In the following description, the term wall of the sachet applies equally to a single-film sachet as to a sachet produced with a complex.

According to a preferred embodiment of the label 1, the latter (FIG. 2) consists of a complex formed of a

• polyester film 5 and an aluminum film 6 itself coated with an adhesive film 7 for fixing the label 1 to the bag 2. The thickness of the films 5 and 6 is for example 1 'order of a few tens of micrometers.

The polyester film 5 is provided with a set of grooves 8 parallel to the edges of the label or diagonally, intended to facilitate the shaping of the label in order to constitute a sort of pouring spout, as well as the folding possible of this spout for its closure.

Among these grooves 8, there is a central groove 8a which will come opposite the fold 4 of the bag, two grooves 8b parallel to the groove 8a and at equal distance from the latter and two oblique grooves 8c starting from the end 9 of the groove

8a to come close to the seal 3.

In addition, the film 5 is provided throughout its thickness with a pre-decov.pe line 10 of generally arched shape consisting of segments connecting the ends 11 of the grooves

8b, sealing side 3. This line 10 forms a tear line for the wall of the bag 2, intersecting the grooves

8a and 8c in points 12 and 13 respectively.

According to the invention, in the wall of the bag 2, in a zone symbolically marked at A in FIG. 3, opposite point 12, a local weakening is carried out on the external face of said wall.

This weakening aims to make the wall tearable at this location, which, without this prior treatment, would be tear-resistant by hand.

Very advantageously and according to another characteristic of the invention, said weakening is achieved by the application at A on the external face of the sachet

2 of a pressure combined with ultrasound, using a sonotrode with a surface constituted of asperities so as to print in the plastic film in _regard of the sonotrode a multitude of small craters.

We illustrated in Figures 7 and 8 such a process.

In these figures, 14 shows a complex formed by a polyester film 15 of about ten micrometers and a polyethylene film 16 of a few tens of micrometers.

In areas of the complex where you want to

Weakening, the complex 14 is pressed between a sonotrode 17 with an active face 18 made up of asperities, for example of generally conical shape, and an anvil 19, the asperities regularly distributed over said active face 18 being applied against the polyester film 15.

The shape of the sonotrode 17 is for example circular, square or rectangular and of variable dimensions depending on the shape and extent of the area to be weakened.

The pressure exerted on the complex 14 is for example of the order of 2 bars, the duration of application of the ultrasound is of the order of 60 to 100 s and the frequency of the ultrasound is for example of 20,000 Hz. The asperities (18) of the sonotrode are for example constituted by frustoconical studs of height less than 1mm and separated from each other by a distance of the order of

0.75 mm. The application of ultrasound in conjunction with the pressure exerted on the sonotrode 17 causes in the polyester film 15 (FIG. 8) small craters 20 penetrating slightly into the underlying film which simply undergoes, next to said craters 20, flows causing the appearance of small projections 21 and which nevertheless keep the film 16 its sealing power. The polyester film 15 is weakened at the height of the craters 20 and can be relatively easily torn there.

If the wall of the bag 2 is a simple film of polyethylene or polypropylene, a sonotrode of the type illustrated in FIG. 7 causes the same localized weakening of the film by local micro-fusions similar to micro-fusions 21 and which do not pass through the wall of the film.

A weakening of the above type is carried out for example in zone A of the wall of the bag 2, before the constitution of the bag and the positioning of the label 1.

When one wants to open by tearing by hand such a sachet provided with such a label, the sachet is pinched at point 12 on line 4 and a tearing torque D is exerted in line with point 12, which causes the label 1 and the bag 2 to be torn along the pre-cut line 10 in the direction of the two ends 11. It suffices to tear the wall of the bag at the level of zone A for the tear to propagate without difficulty beyond zone A by being channeled by pre-cut line 10. Arrival at seal 3 the tear line continues naturally, without particular guidance, but that no longer matters, up to the extreme edge of the sealing.

The hatched part of FIG. 3, formed of a part of the label 1 and of the upper corner of the bag 2, is thus separated from the bag and reveals a pouring orifice for the contents of the bag, entirely delimited by line 10.

The relative rigidity of the label 1 relative to the bag 2 and the grooves 8 allow a shaping of the label in spout and possibly a folding of the parts of the labels on themselves, ensuring a relatively tight reclosure of the bag. Such reclosing by folding is facilitated by the existence of the aluminum film 6 of the label. The groove 8a which does not extend over the entire width of the label 1, retains the latter, in the non-grooved area 8'a opposite the fold 4, sufficient rigidity to give the upper edge rounded spout. Figures 4 and 5 illustrate the application of another type of label l 'on a bag 2' whose wall is for example similar to that of bag 2, but whose sealing line 3 'is horizontal and partly superior.

More specifically, the label is of the type described in said document FR-93 07720 and comprises an upper part

22 forming a spout and a lower part 23 forming a support and maintaining the shape of the spout.

The label structure is of the type shown in FIG. 2, namely an outer polyester film 5, an underlying aluminum film 6 and an adhesive film 7.

Part 22 is provided with two central grooves 24,25, oblique grooves 26 and a pre-cut line 27, throughout the thickness of the polyester film 5, starting from the upper edge 28 and returning to this edge in intersecting the grooves 24 and 26.

At the ends of the line 27 is provided a notch 29 for scrapping pipe.

The label l 'is placed on the bag 2' so that the upper edge 28 is flush with the seal 3 'and the groove 24 in line with the vertical fold 30.

Prior to the positioning of the label and the production of the bag 2 ′, the wall of the bag is provided with weakening zones A similar to that of FIG. 3, at the height of the intersections of the pre-cutting line 27 with the grooves 24, 26 and the edge 28 as well as on the extreme edge of the seal 3 'opposite another zone A.

The opening of the bag 2 ′ can thus be done in several places (zones A), at the choice of the user. A tearing torque exerted in one of the zones A causes the tear the wall of the bag and continue tearing along line 27.

There is thus, as in the case of FIG. 3, a perfectly clean tearing line and channeled by the pre-cutting line 27 which provides an orifice for discharging the contents of the sachet perfectly pre-determined and calibrated.

Is shown in Figure 5 hatched parts of the label 1 'and the bag 2' removed during tearing. The arrangement of the line 27 can be designed so as to allow the lips of the orifice of the pouring spout to be folded edge to edge for reclosing the spout, for example on itself by folding around the crease 25.

It should be noted with the sachet 2 ′ as with the sachet 2 that the structure of the label l ′, l is of a nature to compensate for any possible but improper sealing failures of the wall of the sachet in zones A, because these areas are covered by the adhesive aluminum film 6 which is intact as long as the bag is not opened. FIG. 6 illustrates the production of another type of 1 "label, always and advantageously consisting of the complex of FIG. 2, intended for a flexible 2" parallelepiped bag (once filled), of the ground coffee type.

The label 1 "comprises a polyester film 5 divided into strips 31 arranged parallel to the upper horizontal edge 32 of the coffee package (2"), the label being glued so as to extend very widely over the upper part of the sachet folded over the top of the package.

The strips 31 are detachable and linked together by bridges 33.

Opposite the two lateral edges 34 of the label, there are formed in the wall of the bag 2 "weakening zones A covering the intersections of the edges 34 and the lines of separation of the strips 31. These zones A are punctual or, better , arranged in two narrow bands corresponding to the edges 34.

To open the package, the wall of the bag 2 "is torn at the intersection of one of the folds 35 of the upper part of the bag with one of the edges 34 of the label 1" which is necessarily placed so that in any event, despite the uncertainty of the positioning of said folds 35, one of said zones A in FIG. 6 is located opposite a fold 35.

Thus, when the bag is opened, one or more strips 31, or even no strip, will be detached if the tearing is carried out along the upper edge 36 as would be the case with the bag in FIG. 6.

Finally, it should be noted that the rest of the label 1 "can be used for reclosing the bag by folding the remaining strips 31 onto themselves and the wall of the bag on which they are stuck.

Figures 9 and 10 illustrate an alternative embodiment of the label 1 of Figures 1 and 3, incorporating a tab L for closing the bag 2 after opening. Said tab L is a rectangular piece of adhesive tape attached (Figure 1) on a side part of the label 1, that is to say outside the central zone provided with the pre-cut 10, on one side or the other.

The tongue L has a marking edge 37 on its edge coinciding with the edge of the label on which said pre-cut 10 is formed.

To close the bag 2 provided with a label 1 with a tab L, fold the seal 3 against the wall of the bag (Figure 9), flatten the beak delimited between the two grooves 8b of the label and fold it against the flank of the bag, after peeling off the tab L from the label part located on said flank.

Then, the two half-parts FI and F2 of the said flank are closed on themselves, along the internal edge 38 of the seal 3, according to the arrows and (FIG. 10) the tongue L is folded down on the other side to stick it on the opposite side of the label 1 and the bag 2.

The tongue L keeps the spout thus closed tightly sealed. The reopening of the sachet takes place by a process opposite to that which has just been described.

It should be noted that with such an arrangement, the adhesive side of the tongue L is preserved from any contamination by the product which may remain in the immediate vicinity of the spout. Finally, the invention is obviously not limited to the embodiments shown and described above, but on the contrary covers all the variants in particular with regard to the shapes, dimensions and structures of the labels, the shape, the arrangement. of the pre-cut line (s) 10,27, as well as the extent, the dimensions and the arrangement of the weakening zone (s) A facing said pre-cut line and that the nature of the wall, simple or complex, from the flexible sachet.

Claims

1. Device for easy and controlled opening of a flexible bag (2.2 ′, 2 ") formed using at least one plastic film ensuring mechanical strength and sealing, characterized in that it is constituted by the combination, on the one hand, of a weakening of the mechanical characteristics of or one of the plastic films in one or more appropriate distinct zones (A) of the external face of the wall of the sachet and, on the other hand part, of a pre-cut label (1,1 ', 1 ") attached to said external face, up to the abovementioned zone or zones (A), said label being made of a material (5) relatively rigid by relative to the material of the wall of the bag, covered with an adhesive film (7) for fixing on the bag and provided with at least one pre-cut line (10,27) of suitable shape and facing the or areas of weakness of said sachet.

2. Device according to claim 1, characterized in that the label (1,1 ') is provided with grooves (8; 24 to 26) for shaping the spout and the pre-cutting line (10,27 ) has a generally arcuate shape, its two ends being on the same edge (28) of the label.

3. Device according to claim 1, characterized in that the label (1 ") consists of separable parallel strips (31) connected by bridges (33).

4. Device according to claim 1 to 3, characterized in that the label (1,1 ', 1 ") is formed of a complex comprising a polyester film or the like (5), an aluminum film or the like (6) and an adhesive film (7).

5. Device according to one of claims 1 to 3, more especially intended for flexible sachets with sealing

(3) vertical in the position of use, characterized in that the label (1) is placed astride a horizontal fold (4) of the bag and flush with said seal (3), the edge of the label provided with said pre-cutting line (10) being on the side of the seal.

6. Device according to one of claims 1 to 3, more especially intended for flexible sachets with sealing horizontal (3 '), characterized in that the label (1') is placed astride a vertical fold (30) of the bag and flush with said seal (3 '), the edge (28) of the label provided of said pre-cutting line (27) being on the side of the seal.

7. Device according to claim 4, more especially intended for flexible parallelepiped sachets of the ground coffee type, characterized in that the label (1 ") is placed in line with one of the foldable end parts of the sachet, said strips (31) being arranged parallel to one of the end edges (32) of the filled bag.

8. Device according to one of claims 1 to 7, characterized in that the weakening zone or zones (A) are produced by the local joint application of pressure and ultrasound, using a sonotrode (17) with surface made up of asperities (18) so as to print in said plastic film (15), in said zones (A), a multitude of small craters (20).

9. Device according to claims 2 to 3,5,6 and 8, characterized in that the weakening zone or zones (A) are formed in one or more places on the pre-cutting line (10,27), including the ends of the latter.

10. Device according to claim 9, characterized in that one or more weakening zones (A) are provided opposite the intersections between said pre-cutting line (10,27) and said grooves (8,24 to 26 ).

11. Device according to one of claims 4,7 and 8, characterized in that the weakening zone (s) (A) are formed along the edges (3 ') of the label (1 ") where s' intersect the dividing lines of said strips (31).

12. Device according to claim 5, characterized in that the label (1) is provided with an adhesive tongue (L) for tightly closing the pouring spout after folding over themselves parts of the label forming said pouring spout .

13. Bag with easy and controlled opening, possibly reclosable, provided with the device according to any one of claims 1 to 12.