EP0332549A1 - Flexible bag provided with a filling valve - Google Patents

Abstract

Bag of the type comprising a filling tube fixed in the basic structure, one of whose ends is closed by a film of flexible elastic material having a central orifice. According to the invention, the film of flexible elastic material (9) is sandwiched between two sheets (11, 12) of flexible material having respective openings (13, 14) centred on the axis of the filling orifice and having dimensions greater than those of this orifice. Application to the production of bags for powdery products. <IMAGE>

Description

The present invention relates to a flexible packaging bag equipped with a filling valve.

In the field of packaging of powdered products, it is known to use paper bags made from a tubular element, the two ends of which are closed by folding and gluing with a view to producing a crossed bottom or 'a square background.

The bottom can be fitted with a paper or synthetic tube, fixed in the folded structure and connecting the outside and the inside of the bag. To fill the bag, it is possible to introduce a bagging spout through the open end of the tube and thus ensure the transport of the product inside the bag.

When the bag is full, the bottom design allows, after removal of the bagging spout, the automatic closing of the tube which flattens under the effect of the pressure of the product contained in the bag. The tube actually behaves like a fill valve.

However, it is not possible to obtain a perfect seal of the bag with such filling valves.

Furthermore, the diameter of the filling tube being necessarily greater than that of the bagging spout, there inevitably occurs, during filling, residual deposits of product in the tube.

To this phenomenon is added that of product leaks out of the filled bag, during handling operations. To avoid these leaks, it is necessary to close the tube tightly after filling. It is thus known, for example, to coat the inner face of the tube with a layer of reactivable glue or else to add, by gluing, on the bottom of the bag, a strip of paper reinforcement, protruding beyond the outer end of the tube. In the case of tubes made of plastic, it is possible to perform ultrasonic welding of the wall of the tube, on itself to achieve the closure thereof.

Of course, a classic bonding can also be carried out in all cases.

This type of operation constitutes an additional phase in the manufacturing process, which requires a complex and costly industrial installation. In addition, its implementation involves significant costs in time and materials.

Document US-A-3 318 511 describes a filling valve for a bag, comprising a sheet of flexible synthetic material folded back on itself and having, along its fold, a slot for the passage of a filling cannula. However, this solution is not satisfactory because the flexible sheet does not have good mechanical strength, it is difficult to achieve correct positioning of the cannula with respect to the slit of the sheet. There is even the risk that the cannula cannot be introduced inside the bag.

The present invention aims to remedy these drawbacks. To this end, the flexible packaging bag which it relates to, of the type produced from a tubular element the two ends of which are closed by folding and gluing for the production of the bottoms, one of these bottoms comprising a tube fixed in the folded structure connecting the outside and the inside of the bag, and one end of the tube of which is closed by a film of flexible elastic material, having, in its central region, an orifice intended to serve for the passage of a bagging spout projecting the filling product into the bag, the dimensions of the filling orifice being smaller than those of the bagging spout, is characterized in that the film of flexible elastic material is plated , at least by one of the faces, against a sheet of flexible material having an opening centered on the axis of the filling orifice and of dimensions greater than those of this orifice.

Advantageously, the film of flexible elastic material is sandwiched between two sheets of flexible material having respective openings centered on the axis of the filling orifice and of dimensions greater than those of this orifice.

This film of flexible elastic material can be likened to an elastic diaphragm whose opening is able to enlarge to adapt to the dimensions of the bagging spout when it is introduced into the tube and to recover its reduced dimensions, by elastic effect, after removal of the bagging spout.

This "diaphragm" effect is added to that of "valve" produced by the flattened tube under the influence of the pressure of the product inside the bag.

The fact that the film of flexible elastic material is associated with at least one sheet of flexible material, such as paper, provides protection of the film, as well as stiffening and mechanical reinforcement of the valve, facilitating the correct positioning of the cannula. in the aperture of the diaphragm, without risk of damaging the film.

These advantageous provisions make it possible, on the one hand, to avoid residual deposits of product in the tube during filling, because the film of flexible elastic material isolates the inside of the bag from the inside of the tube by perfectly matching the bagging bag and, on the other hand, to minimize leakage of product after filling through the combined effects of the tube and the film of flexible elastic material.

In addition, the cost price of this filling valve is very low.

According to a first embodiment of the invention, the inner end of the tube is closed by the flexible elastic film.

According to a second embodiment of the invention, the outer end of the tube is closed by the flexible elastic film.

In order to simplify the manufacture of this filling valve and to improve its efficiency, the filling orifice is advantageously produced from a partial cut in the flexible elastic film, so as to constitute a tab forming a valve capable of closing on the filling hole when removing the bagging spout.

Advantageously, the flexible elastic film is preferably fixed by each of its faces, on a sheet of flexible material, having an opening of dimensions greater than those of the filling orifice and centered on the axis thereof; the opening of at least one of these sheets being constituted by at least four pre-cut radial slots, defining four tabs forming valves, able to close on the opening when removing the bagging spout.

In order to obtain a solid and reliable mounting of the flexible elastic film on one of the ends of the tube, when the latter is made of paper, it is advantageously planned to produce a complex, consisting of two strips of rectangular paper having, in their center, an opening, and by the flexible elastic film interposed therebetween, these three elements being assembled by gluing and arranged in such a way that the two openings and the filling orifice are aligned, the complex being folded in half according to a transverse axis, so as to form two tabs glued to the wall of the tube, the axis of the latter being substantially coincident with that of the openings and the filling orifice.

The flexible elastic film is preferably made of a natural or synthetic rubber with a thickness between 100 and 300 micrometers, hardness of the order of 80 Shore ± 10 and elongation characteristic of the order of 500% .

• Figure 1 est une vue en perspective partielle d'un sac en cours de remplissage et de son fond comportant la valve de remplissage ;
• Figure 2 est une vue éclatée en perspective des éléments consti­tuant la valve de remplissage et de la structure pliée du fond d'un sac la recevant ;
• Figure 3 est une vue en coupe longitudinale partielle d'un sac comportant la valve de remplissage ;
• Figure 4 est une vue de côté du sac de figure 3,
• Figure 5 est une vue du sac de figure 3 au cours du remplissage ;
• Figure 6 est une vue en coupe longitudinale partielle d'un sac comportant une première variante de la valve de remplissage ;
• Figure 7 est une vue de côté du sac de figure 6,
• Figure 8 est une vue en coupe longitudinale partielle d'un sac comportant une seconde variante de la valve de remplissage.

In any case, the invention will be better understood and other advantages will emerge from the description which follows, of nonlimiting examples of embodiment of this filling valve, with reference to the appended drawing in which:

• Figure 1 is a partial perspective view of a bag being filled and its bottom comprising the filling valve;
• Figure 2 is an exploded perspective view of the elements constituting the filling valve and the folded structure of the bottom of a bag receiving it;
• Figure 3 is a partial longitudinal sectional view of a bag comprising the filling valve;
• Figure 4 is a side view of the bag of Figure 3,
• Figure 5 is a view of the bag of Figure 3 during filling;
• Figure 6 is a partial longitudinal sectional view of a bag comprising a first variant of the filling valve;
• Figure 7 is a side view of the bag of Figure 6,
• Figure 8 is a partial longitudinal sectional view of a bag comprising a second variant of the filling valve.

Figure 1 partially shows a flexible packaging bag 1 made of any suitable material, in particular paper. This bag 1 is of a known type, obtained from a tubular element having two closed ends. One of these ends shown in the drawing consists of a flat bottom 2 fitted with a filling valve 3 . This brings the interior and exterior of the bag 1 into communication and allows the introduction of a bagging spout 4 projecting the product to be packaged inside the bag 1 .

As it appears in FIG. 2, the bottom 2 is constituted by a folded structure comprising four identical flaps two by two, namely two interior flaps 5 and two exterior flaps 6 .

The two inner flaps are spaced from one another and provide access 7 to the interior of the bag 1 , while the two outer flaps 6 come, in the closed position, overlapping each other and are glued as well.

In this example, the filling valve 3 is constituted by a tube 8 , by an elastic film 9 having, in its central region, a filling orifice 10 , and by two rectangular strips 11 and 12 of flexible material, for example paper , each with a center circular opening 13.14 with a diameter greater than that of the filling orifice 10 . This tube 8 is made of paper or any other suitable material. It is obtained from a rectangular sheet of paper, shown in dashed lines in FIG. 2, the two longitudinal edges of which are assembled and glued by overlapping one on the other when the bottom 2 is closed. The tube 8 is fixed by gluing in the folded structure of the bottom 2 of the bag 1 so that one of its ends opens into the bag at the access 7 and the other of its ends opens outside of the bag.

As can be seen from FIG. 3, the flexible elastic film 9 is intended to close the inner end of the tube 8 .

This film is preferably made of a synthetic material, such as synthetic rubber with a thickness of between 100 and 300 micrometers, hardness on the order of 80 Shore and an elongation characteristic on the order of 500%. .

For its mounting on the paper tube 8 , the flexible elastic film 10 is bonded between the rectangular paper strips 11 and 12 so as to form a complex in which the openings 13, 14 and the filling orifice have a common axis. This complex is folded transversely so as to form two tongues which are glued to the internal face of the wall of the tube 8 , as shown in FIG. 2.

FIG. 3 shows the filling valve 3 once produced and fixed by gluing in the folded structure of the bottom 2 of the bag 1 . The filling orifice 10 occupies a position substantially centered in the inner end of the tube 8 . As it appears in FIG. 4, the filling orifice 10 is preferably produced, in this example, from a partial cut in the flexible elastic film 9 , so as to constitute a tongue 15 which is substantially circular. The latter thus forms a valve capable of closing on the filling orifice 10 , during the withdrawal of the bagging spout 4 .

The filling orifice 10 has reduced dimensions smaller than those of the bagging spout, which makes it possible to minimize product leaks from the bag.

As is apparent from FIG. 5, during the introduction of the bagging spout 4 through the filling orifice 10 , the latter elongates, deforming elastically, so as to conform perfectly to the contour outside of spout 4 . This therefore insulates the interior from the exterior of the bag 1 , and thus, during the projection of the product therein, to avoid the exit towards the outside of the product and its deposit inside the tube 8 .

Once the filling operation has been completed, the spout 4 is removed from the valve 3 , the filling orifice 10 covers its reduced dimensions and the tongue 15 covers it.

For reasons of clarity of the drawing, the effect of the tube 8 of the filling valve 3 , which combines with that of the orifice 10 to seal the bag, is not shown. filled. This is the flattening of the tube 8 under the effect of the pressure of the product contained in the filled bag.

FIGS. 6 and 7 show a first alternative embodiment of the filling valve 3 , in which the rectangular strip 11 serving to support the elastic film 9 has an opening 14 produced from four precut radial slots 16 . These slots 16 make it possible to define four tabs 17 made of paper forming valves which are capable of closing over the opening 14 after removal of the bagging spout 4 , under the effect of their elasticity and the pressure of the product. This further improves the efficiency of the closure.

In the same way, an identical structure could be provided for the opening 13 of the rectangular strip 11 .

In the embodiment shown in Figure 8, the outer end of the tube 8 is closed by the flexible elastic film 9 provided with its filling orifice 10 , while its inner end is open.

As is apparent from the above, the invention brings a great improvement to the prior art by providing a flexible packaging bag, one of the bottoms of which is equipped with a filling valve of simple and inexpensive structure which prevents the exhaust of product to be conditioned, both during and after filling.

It goes without saying that the invention is not limited to the sole embodiments of the valve described above; on the contrary, it embraces all variants based on the same principle.

This is how the tube at the bottom of the bag could be made of synthetic material independently and then added to the folded structure of the bottom of the bag.

It could also be made in a single whole with the structure of the bag. The flexible elastic film could be mounted alone on one end of the tube. We could even consider the presence of a film on the two ends of the tube.

Finally, the rectangular film support strips could in themselves constitute the tube at the bottom of the bag.

Claims (8)

1. Flexible packaging bag fitted with a filling valve (3), of the type produced from a tubular element the two ends of which are closed by folding and gluing with a view to making the bottoms, one of these bottoms (2) comprising a tube (8) fixed in the folded structure, connecting the outside and the inside of the bag (1), and one of the ends of the tube (8) of which is closed by a film (9) of flexible elastic material, having, in its central region, an orifice (10) intended to be used for the passage of a bagging spout (4) projecting the filling product into the bag (1), the dimensions of the filling orifice (10) being lower than that of the bagging spout (4), characterized in that the film of flexible elastic material (9) is pressed, at least by one of the faces, against a sheet ( 11, 12) of flexible material having an opening (13, 14) centered on the axis of the filling orifice (10) and of dimensions greater than those of this orifice. 2. Bag according to claim 1, characterized in that the film of flexible elastic material (9) is sandwiched between two sheets (11, 12) of flexible material having respective openings (13, 14) centered on the axis of the filling orifice and of dimensions greater than those of this orifice. 3. Bag according to any one of claims 1 and 2, characterized in that the inner end of the tube (8) is closed by the flexible elastic film (9). 4. Bag according to any one of claims 1 and 2, characterized in that the outer end of the tube (8) is closed by the flexible elastic film (9). 5. Bag according to any one of claims 1 to 4, characterized in that the filling orifice (10) is produced from a partial cut in the flexible elastic film (9), so as to constitute a tongue (15) forming a valve capable of closing on the filling orifice (10) during the withdrawal of the bagging spout (4). 6. Bag according to any one of claims 1 to 5, characterized in that the flexible elastic film (9) is fixed by each of its faces, on a sheet (11,12) of flexible material, having an opening (13 , 14) of dimensions greater than those of the filling orifice (10) and centered on the axis thereof, the opening (14) of at least one of these sheets (12) being constituted by at at least four pre-cut radial slots (16) defining four tabs (17) forming valves, able to close on the opening (14) when removing the bagging spout (4). 7. Bag according to any one of claims 2 to 6, characterized in that the tube (8) is made of paper and in that the filling valve (3) is produced from a complex constituted by two strips of rectangular paper (11,12) having, in their center, an opening (13,14) and by the flexible elastic film (9) interposed between them, these three elements (9,11,12) being assembled by gluing and arranged in such a way that the two openings (13,14) and the filling orifice (10) are aligned, the complex being folded in half along a transverse axis, so as to form two tabs glued to the wall of the tube (8 ), the axis of the latter being substantially coincident with that of the openings (13,14) and the filling orifice (10). 8. Bag according to any one of claims 1 to 7, characterized in that the flexible elastic film (9) is made of natural or synthetic rubber with a thickness between 100 and 300 micrometers, of hardness of the order of 80 Shore ± 10 and an elongation characteristic of the order of 500%.

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