EP0948446B1 - Sealed bag and method for making and packaging liquid in said bag - Google Patents

Description

The present invention relates to a sachet for the packaging of liquid formed using material film plastic, including a liquid-tight enclosure and a pocket, adjacent to this enclosure, in which is housed a liquid sampling conduit, means being arranged to access the interior of said pocket, a opening being formed through part of the wall of this pocket, adjacent to said enclosure, to allow said sampling conduit entering tightly into said enclosure. This invention also relates to a process for making sachets and packaging liquid continuously in these sachets.

We have already proposed, in particular in WO 95/23742 a sachet for the packaging of liquid comprising a integrated valve to control the outlet of the liquid and susceptible to be able to be manufactured continuously from thermoplastic film. The preamble of claim 1 is based on this state of the art. We proposed to associate a straw to this sachet to allow access to the liquid to through the valve formed by a channel formed between two layers of film normally joined and which open when from the introduction of straw. Therefore, when one at least partially remove the straw from the forming channel valve, this channel closes and the liquid can no longer exit. The disadvantage of this system is that removing the straw, the latter brings out the liquid which is found in the valve channel, gradually dirtying the outside of the bag.

It is obviously not easy to make a joint effective in such a type of sachet and even less when this sachet is fitted with a valve of the aforementioned type. The edges of the channel delimiting the valve are made by welding films of thermoplastic material. Now, by welding these films, we locally transform the structure of matter of the film, which becomes amorphous and loses its elasticity, harming thus the quality of the seal which can be formed. It is otherwise excluded from using an element fitted at the end inlet of this valve channel. This clearly shows the complexity of the problem to be solved, the solution to be adapted to the very low cost price acceptable for a bag of this type. Other problems related to this concept of sachet and whose solutions are taken up in combination with the present invention, have already been made by the inventor of the present invention and have been the subject of other protections. These include the question of incorporation of a straw in the sachet and inviolability of this sachet for obvious reasons of hygiene and of security.

On the other hand, the problems related to sealing as well that a certain method of manufacturing and packaging the continuous liquid had not yet, so far, received from satisfactory answer. One of these problems is related to incorporation a straw in a closed pocket of the package in a manufacturing process on a material in continuous strip.

The object of the present invention is precisely to provide a solution to the problem of sealing, as well as that of the manufacture of sachets and the packaging of liquid continuously in such sachets, allowing in particular to use known machine concepts, even if they are nevertheless called upon to undergo transformation substantial to adapt to manufacturing and packaging of these sachets.

To this end, the present invention has first of all for object a sachet for the packaging of liquid of the type the aforementioned as defined by claim 1. This element tubular of decreasing section is obtained by stretching with a plastic film and thus allows to retain the elasticity of the film, guaranteeing an effective seal. It's about more than a very simple solution, perfectly adapted to the product for which it is intended.

Preferably, the wall of the pocket containing said sampling line is integral with a cut tongue in a layer of film intended to form the enclosure waterproof. This tab guarantees inviolability access to the straw used to distribute the liquid.

Advantageously, the opening formed at the end of the tubular element forming a seal communicates with one end of a valve channel between this opening and inside the waterproof enclosure, the pocket of the bag being formed between a first layer of film forming one of the walls of said channel and a second layer of film significantly narrower than the first layer and secured to the pocket opening tab. Thanks to this arrangement, we gain a film thickness since a of the walls of the pocket is formed by one of the films of the channel valve. This gain in thickness has an advantage when the blank of banded sachets must be rolled up reel to be sent to a packaging unit of the liquid. The extra thickness made up of two thicknesses of film forming the pocket walls can thus be reduced in half, also reducing the difference in thickness from one edge to the other of the blank reel.

Alternatively, this pocket can however be formed in the fold of a film folded back on itself. Preferably, this fold may lie adjacent to one end of the canal controlling the liquid flow and the tubular element forming seal may extend over part of it channel.

This invention also relates to a method of manufacture of sachets and liquid packaging in continuous in these sachets according to claim 9. One of the advantages of this process is to allow the filling of sachets and placing straws laterally, one longitudinal edges of the strip material intended to form one of the edges of these sachets remaining open until filling time. Because of this, the straw can be introduced laterally in the axis of the joint and the channel valve when this channel exists, and a supply conduit liquid can pass between the walls of the sachet, along from its edge coinciding with the longitudinal edge of the material in a band. The welding of this longitudinal edge is carried out as the strip material advances, just before filling.

Advantageously, the process takes place in two separate phases, one consisting of forming a continuous band of sachet blanks, the second of which is to form the tubular joint, to introduce the sampling conduit and to condition the liquid in the enclosure. The advantage of this embodiment is to allow the manufacture of blanks and liquid packaging in two units of separate productions, the conditioner of the product not being not necessarily capable of solving the problems posed by manufacture of such a bag.

Therefore, the conditioner of the liquid in the packaging can then use the draft thus produced as the simple sheets or films used for packaging liquid in cartons, sachets or bricks, in carrying out the packaging using the usual machines, so that to condition the liquid he wants sell in sachets according to the invention, in particular the valve bags, the liquid conditioner, replace simple extruded films or sheet materials usual, by the blanks of sachets according to the present invention.

One of the main advantages of the enclosure the invention is to have a sealing of the valve channel which allows, by piercing this lid not by cutting, but by punctual deformation of the cover in the direction of the valve channel until it breaks, to obtain an annular seal slightly tapered which guarantees elastic tightening straw, ensuring a seal that avoids that liquid in the valve channel does not get out escapes.

In addition, the two sides of the enclosure from the same sheet folded back on itself does not undergo any offset between them, so it is the same for the inscriptions screen printed arranged on both sides of this pregnant.

Thanks to the packaging process according to the invention, the pocket intended to accommodate the curved part of the straw located outside the valve channel is performed after the introduction of straw into the entrance to this canal, so that the straw does not pull on the side welds from the pocket.

La figure 1 est une vue en plan, illustrant une première phase du procédé de fabrication;

la figure 2 est une vue en coupe de la figure 1;

la figure 3 est une vue en plan illustrant une deuxième phase de ce procédé;

la figure 4 est une vue en coupe de la figure 3;

la figure 5 est une vue en plan illustrant une troisième phase de ce procédé;

la figure 6 est une vue en coupe de la figure 5;

la figure 7 est une vue en plan illustrant une quatrième phase de ce procédé;

la figure 8 est une vue en coupe de la figure 7;

la figure 9 est une vue en plan illustrant une cinquième phase de ce procédé;

la figure 10 est une vue en coupe de la figure 9;

la figure 11 est une vue en plan illustrant une sixième phase de ce procédé;

la figure 12 est une vue en coupe de la figure 11;

la figure 13 est une vue en plan illustrant une septième phase de ce procédé;

la figure 14 est une vue en coupe de la figure 13;

la figure 15 est une vue en plan du sachet terminé;

la figure 16 est une vue en coupe de la figure 15;

la figure 17 est une vue en plan de la quatrième phase d'un second mode de réalisation du procédé pour la fabrication et le conditionnement de liquide dans un sachet selon une seconde forme d'exécution;

la figure 18 est une vue en coupe de la figure 17;

la figure 19 est une vue en plan de la cinquième phase de ce procédé;

la figure 20 est une vue en coupe de la figure 19;

la figure 21 est une vue en plan d'une phase ultérieure de ce procédé;

la figure 22 est une vue en coupe de la figure 21;

la figure 23 est une vue en plan de la première phase du processus de conditionnement du liquide dans le sachet selon la seconde forme d'exécution;

la figure 24 est une vue en coupe de la figure 23.

Other advantages and other variants will become apparent during the description which follows, made with the aid of the appended drawing which illustrates, very schematically and by way of example, an embodiment and a variant of the enclosure object of this invention, as well as the corresponding modes of implementation of the manufacturing and packaging methods objects of this invention.

Figure 1 is a plan view, illustrating a first phase of the manufacturing process;

Figure 2 is a sectional view of Figure 1;

Figure 3 is a plan view illustrating a second phase of this process;

Figure 4 is a sectional view of Figure 3;

Figure 5 is a plan view illustrating a third phase of this process;

Figure 6 is a sectional view of Figure 5;

Figure 7 is a plan view illustrating a fourth phase of this process;

Figure 8 is a sectional view of Figure 7;

Figure 9 is a plan view illustrating a fifth phase of this process;

Figure 10 is a sectional view of Figure 9;

Figure 11 is a plan view illustrating a sixth phase of this process;

Figure 12 is a sectional view of Figure 11;

Figure 13 is a plan view illustrating a seventh phase of this process;

Figure 14 is a sectional view of Figure 13;

Figure 15 is a plan view of the finished bag;

Figure 16 is a sectional view of Figure 15;

FIG. 17 is a plan view of the fourth phase of a second embodiment of the method for manufacturing and packaging liquid in a sachet according to a second embodiment;

Figure 18 is a sectional view of Figure 17;

Figure 19 is a plan view of the fifth phase of this process;

Figure 20 is a sectional view of Figure 19;

Figure 21 is a plan view of a later phase of this process;

Figure 22 is a sectional view of Figure 21;

FIG. 23 is a plan view of the first phase of the process for conditioning the liquid in the sachet according to the second embodiment;

FIG. 24 is a sectional view of FIG. 23.

Figures 1 and 2 show three sheets 1, 2, 3 overlapping sheet material, the third of which is width significantly smaller than the first two. The first sheet 1, which is intended to form the wall of a waterproof enclosure, in this example, a sachet for packaging of a liquid, especially a drink, is preferably made of a plastic sheet multilayer, as usually used for packaging of food products. The different layers of these multilayer sheets can be formed of different plastics or the same material, this which allows them to be recycled. Of course, the sachet object of the present invention is not limited to the packaging of drinks, but can be used for any type of liquid.

The second sheet 2 is a plastic film extruded, especially polyethylene, as well as the third sheet 3. It should also be specified here that, even if sheets 2 and 3 have been shown to be initially two separate sheets, they could also form initially a common sheet, folded around an axis longitudinal to that of this strip sheet, to form then the two sheets 2 and 3 of different widths shown in Figures 1 and 2.

As another variant, sheets 2 and 3 could be from a tubular film, put under slight overpressure internal, the superimposed layers being obtained in gradually flattening the tube and folding longitudinally and gradually inward, a portion of this tube. In this way, we obtain four superimposed layers, two of which are narrower than the other two, connected to each other, as illustrated in Figure 8, but without requiring welding between them.

These three sheets 1, 2, 3 of different widths, at less for one of them, are first aligned so as to make their left edges coincide.

The first step in manufacturing the process consists, in this example, to cut a tab 4 in the first sheet 1 intended to form the wall of the sachet. This tab 4 remains attached to sheet 1 by one end. The cutting tools are symbolized by the rectangles 5 and 6 of figure 2. During the same stage, one can pierce sheet 3 in the middle of its width to form a hole 7 for the passage of a straw. Tools for the realization of this hole 7 are symbolized by a conical punch 8 and a matrix 9 in Figure 2. How to do this hole 7 is important. It is not a question of cutting this hole 7, but occasionally stretch the film using the punch 8 in the housing formed in the matrix 9, until rupture of the film 3. As a result, the material of the film surrounding the opening 7 deforms while flowing, forming a kind of small conical tube 7a (Fig. 15) at the bottom of which is the hole 7. Consequently, when the straw 21 (Fig.15) is introduced into the hole 7 through the side of the film 3 through which the punch 8 has drilled this hole 7, this hole being calibrated for be of a diameter slightly smaller than that of straw 21, tubular part 7a produced during drilling of this hole 7 encloses the straw 21 and forms a seal sealing around it.

Alternatively, one can imagine welding on the film 3 a washer of the same plastic as this film 3 to the place where the hole 7 is to be drilled, so as to reinforce the tubular part surrounding the hole 7.

The following operation, illustrated by Figures 3 and 4 consists of welding together the three sheets 1, 2, 3 in the part where the tongue 4 has been cut. Welding 10 obtained covers the whole tab 4, but it spares zone 10a not welded, superimposed on the free end 4a of the tab 4. Thanks to this weld 10, it will be possible to tear the three sheets of film 1, 2, 3 using the tab 4 as will be explained later.

In terms of the manufacturing process, this weld 10 is of particular interest. It makes it possible to join together the three sheets of film 1, 2, 3 together, of so there can no longer be a displacement between they. We know that plastics are likely to creep as a result of traction on them. These leaves also undergo variations of significant dimension following variations in temperature, as well as variations in humidity. When working like here on a strip material up to several hundred in length meters, these variations can result in the long run by significant shifts. By joining together the films at the beginning of the manufacturing process, it is guaranteed that the operations made later on the different sheets on will be in relative positions which can no longer vary in troublesome proportions.

The next step, illustrated by Figures 5 and 6, consists of folding sheets 2 and 3 back on themselves the direction of the width of the bands, around two axes of longitudinal folding to form two parallel folds 2a, 3a. By folding these sheets 2, 3 onto themselves, the edges longitudinal of these sheets 2 and 3 are aligned on the longitudinal left edge, also corresponding to one of the edges of sheet 1 forming the wall of the bag. In due to the difference in width of sheets 2 and 3 in strips, these folded sheets 2, 3 only overlap in the part of the width of these bands adjacent to the overlapping edges of these bands. Sheet 1, meanwhile, is moved away from sheet 2 to allow access to the latter.

If we start from a single tubular film, as mentioned previously as a variant, we proceed by folding parallel to the axis of the tube as already explained in subject of this variant.

During the step illustrated in FIGS. 7 and 8, two non-converging welding lines 11 are made in the part of the folded sheet 2 which does not overlap with the sheet 3. These welding lines 11 form the edges of a channel 12, between the two folded films of the sheet 2, which is intended to form the valve 12a controlling the distribution of the liquid packaged in the sachet. Simultaneously, the two longitudinal edges of the folded parts film sheets 2 and 3 are attached to each other by a longitudinal weld 13. As illustrated by Figure 8, a separator 14 is inserted between the two parts folded back from sheet 3 to maintain a longitudinal opening allowing free access to the interior of the pocket 15 formed between the two films of the folded sheet 3. Tools for welding the edges 11 of the channel 12 are symbolized in FIG. 8 by two rectangles 16 and 17.

Figures 9 and 10 show the cutout 18 of the two superimposed films resulting from the folding of sheet 2, carried out at using two tools symbolized by rectangles 19 and 20 in Figure 10. This division has the shape of a U whose the two parallel branches are asymmetrical. Branch transverse of this cutout 18 is located near the end of the channel 12 adjacent to the fold of the sheet 2. This cutting 18 is intended to make the channel 12 communicate with the inside of the bag. The asymmetry of the parallel branches of this cutout 18 which extend on either side of the part of the channel 12 forming the valve 12a is intended for improve its functioning, in cooperation with narrowing asymmetrical section of the channel 12.

This stage corresponds to the end of the manufacturing of the blank from the sachet. That is, up to this point in the manufacturing, the blank obtained can be rewound to be transported to another manufacturer for packaging liquid in future sachets that he will finish by conditioning the liquid, as we will explain. Well understood, this is only a possibility to which the invention is obviously not limited. We can indeed perform online packaging following the steps in manufacturing process described so far.

Figures 11 and 12 show the installation of straw 21 between the two folded film portions of the sheet 3, to the first part of channel 12 through the opening 7 formed at the end of the seal tubular 7a which has been discussed previously. he note that as a variant, hole 7 could be made at using the straw 21 itself or a separate tool, just before the introduction of straw 21 and not at during the manufacturing of the blank, as described above. In this variant, the hole 7 could also be primed during the manufacturing of the blank, to facilitate drilling with straw 21. As illustrated by these figures, the end of the straw 21 has an annular bulge 21a whose purpose is to provide resistance when the straw 21 is removed from channel 12 and that this bulge arrives at the level of the opening 7. As illustrated by FIGS. 11 and 12, clamps 22 arranged on each side of the straw 21 serve to retain the sachet blanks during the introduction of straw 21.

Alternatively, the annular bulge 21a of the straw 21 can advantageously be replaced by a deformation of the end of the straw that is turned outwards over a certain length, advantageously a few mm, just like you do with a sock. This reversal can easily be obtained hot. The returned part forms a annular space in which the tubular seal 7a can engage when trying to take out the straw 21 of this joint, thus forming a stop.

The last step before packaging the liquid is to connect the end of the channel 12 adjacent to the fold 3a of the third sheet of film 3, at the longitudinal edge where all the longitudinal edges of the sheets are superimposed 1, 2 and 3 by two parallel welds 24, 25. The second longitudinal edge of the first sheet 1 intended to form the wall of the bag 30 will also be fixed along this edge longitudinal, when conditioning the liquid, as will see it below. These two welds 24 and 25 divide the pocket 15 formed between the two adjacent films of the sheet 3 folded, into three compartments 31, 32, 33, the last 33 contains the folded part of the straw 21. These welds 24 and 25 join the two sheets together folded 2 and 3 with sheet 1 not yet folded, that is to say once bag 30 is finished, both sheets folded 2, 3 will be integral with the same internal face of this bag 30.

Figures 15 and 16 show the finished bag 30. This sachet is finished during packaging liquid, it consists of folding longitudinally sheet 1 around the other two sheets 2 and 3 already folded. Then the sheets 1, 2 and 3 are welded longitudinally by a weld 26 joining the longitudinal edges of the six layers of the three folded sheets 1, 2 and 3 and by another longitudinal weld 27 formed along the adjacent folds of the two folded sheets 1 and 2. A third transverse weld 28 is provided between the welds longitudinal 26 and 27. This weld 28 is intended for form the bottom of the bag 30 which is then filled by the fourth side remained open for this purpose, after which the sachet is closed by a second transverse seal 29. The bag 30 thus obtained, is separated from the strip material to which it was attached so far, cutting this material into strips at the flush with the welds 28 and 29.

As can be seen, the bag 30 has two sealing barriers. One is the valve 12a formed by the part of the channel 12 located between the end of this channel 12 adjacent to the cutout 18 and the throttles asymmetrical leading to part of this channel of enlarged section. Another is formed between straw 21 and the tubular joint 7a.

To consume the contents of the sachet 30, when it is of a drink, just grab the end 4a of the tab 4 and pull it towards the weld 26, thus tearing the three overlapping layers and welded together by the weld 10, at the welds 24 and 25, thus giving access to the interior of compartment 33 containing the curved part of the straw 21. We grab the end of this curved part and we spread it outwards from compartment 33, we then push the straw 21 plus before in channel 12 to remove the part of the films sheets 2 forming the valve 12a and we suck the liquid through the straw 21. If you don't want to consume all the contents of the bag 30, just remove the straw in the position illustrated in Figure 15, so that the valve 12a formed in the channel 12 closes. As to the liquid that is in the rest of channel 12, it is prevented to come out thanks to the seal 7a which encloses the straw 21 around the opening 7 formed through the sheet 3. From this done, the outside of the bag always stays clean and dry. The seal 7a in cooperation with the annular bulge 21a of straw 21 also serves to avoid accidental removal of the straw 21 from channel 12. This is why it can be useful to locally reinforce the portion of film 3 forming this seal 7a, as previously mentioned.

The closed compartments 31, 32 located on either side on the other side of compartment 33 containing the curved part of straw 21, are isolated from the main enclosure of the bag 30 intended to contain the liquid, formed between the two folded parts of sheet 1. These compartments could be used to receive all kinds of items, objects, surprises, advertisements, games or items games etc. which can be inserted during the operation for conditioning the liquid in the main enclosure of the bag 30.

In a final variant of this first embodiment, we could imagine starting from a single sheet or strip folded longitudinally to make the whole of the enclosure and the valve described above, which is not impossible in terms of process according to the present invention. However, it should be noted that in the current state of knowledge that we have plastics available on the market, it is better that the wall 1 of the bag is formed by a PE / PET laminate. Gold PET does not weld on itself, hence the impossibility of use it for layers 2 and 3. In addition, sheets formed only of PE to form the walls of the sachet don't give very good results when it comes to the tearing of the tongue 4 for the opening of the bag. In the tests carried out, excellent results were obtained to form the wall of the bag, with PE / PET sheets whose respective thicknesses are 100 and 12 µm, the thin layer of PET for a clean cut of the tongue 4 at the time of opening.

The different stages of the process described above are called to undergo permutations according to the modes of adopted fabrications. We can indeed adopt a step-by-step manufacturing or a method of manufacturing in which the band (s) are advancing continuously and where the operating organs on the production line are of the rotary type. Such a manufacturing method is likely to reach faster production rates and is therefore potentially more interesting. In the case of use a tubular film to make the folded sheets 2 and 3, as mentioned previously as a variant, it is necessary moreover that the tubular element scrolls continuously.

To make continuous scrolling possible in all cases, it may be necessary to provide, for certain welding operations in particular, a device accumulation of tape by forming meanders on pebbles suspended elastically on either side of the band, so that you can gradually dispose of line in case a temporary stop of this band occurs upstream product. Such a device is not necessary if the welding stations are of the "accompanying" type.

To allow to selectively weld together certain overlapping sheets and no others, separators are interposed in the corresponding parts of the trajectory film strip (s). In the case of welds "accompanying", the separators will be animated by alternative movements in the direction of travel of these bands to follow the movement of the electrodes welding or cutting punches.

Since it is possible to make the sachets provided with valves according to the invention, from one, two or three sheets, one of which may be tubular, it may be preferable to start the process by folding the sheets to bring them, before welding or cutting, in the position illustrated in figure 6, after which we start the cutting and welding operations in the order described above. We can however mention the fact that welding 10 superimposed on tab 4 and around the end 4a of this tongue 4, can preferably be produced, simultaneously with the welding 11 of the channel 12 of the valve illustrated by figure 7.

As already mentioned previously, the drilling of the opening to allow the straw 21 to access the channel 12 of the valve in a sealed manner, produced in the fold 3a of sheet 3, can be done during the operation of packaging of the liquid in the sachet.

The bag according to the second embodiment, the manufacturing process is illustrated by FIGS. 17 to 24, differs from that previously described essentially by the fact that the pocket 15 is no longer formed inside a folded sheet, as before, but between a sheet 35 and a sheet 36, between which the channel 12 is formed of the valve 12a by the two non-convergent welds 11. Unlike the previous embodiment, this channel 12 is preferably not formed by a folded sheet 3 around a longitudinal axis of the strip film, but between two sheets 36, 37. The internal longitudinal edge of the sheet 35 is welded along line 38 to sheet 36 forming one of the walls of the channel 12 (Figures 17 and 18).

In this second embodiment, most of the process steps are similar to those of the first form of execution, too, to avoid unnecessary repetitions, these stages have neither been shown nor described.

As in the first embodiment, the wall of the bag is preferably formed by a single sheet 1 intended to be folded longitudinally later. A tab 4 is cut from this sheet 1 (figures 17, 18) by cutting tools 39, 40 and this tongue 4 is welded to the sheet 35 by a weld 10 except from its end 4a which is in the zone 10a not welded (FIG. 19, 20), by welding tools 41, 42. As before, this weld 10 extends all around tab 4 to isolate it from the liquid inside from the sachet.

Then the sheet 1 forming the wall of the bag is folded longitudinally in half to bring its two edges to join, these edges being aligned with one of the edges of each film ribbon 35, 36 and 37. This step marks the last of the manufacturing process of the sachet blank according to the present invention. Two possibilities are then possible, either the strip along which one succeeds a plurality of regularly spaced blanks continues on a liquid conditioning unit, i.e. this strip of blanks is wound up to be transported to a unit separate packaging.

Figures 23 and 24 illustrate the first step in conditioning process, the others will not described since it suffices to refer to the form previous execution in which the subsequent steps relating to the conditioning process are the same as for this second embodiment.

Whereas in the first embodiment, the joint tubular 7a was formed in the folded sheet 3, at the place of its longitudinal fold, in this embodiment, the tubular joint 7a is formed by piercing the film 36 forming a wall of the channel 12 and of the pocket 15, adjacent to the film 35 forming the other wall of this pocket 15, using of a tool 42.

For the rest of the operations relating to the introduction straw 21, filling with liquid and closing of the sachet, these being similar to those described in relation to the previous embodiment, it just refer to the part of the description relating to the conditioning of the liquid of this first form of execution.

One of the advantages of the manufacturing process for this second embodiment of the sachet comes from the fact that the film 1 intended to form the wall of the bag remains flat and should not be spread down as in the first form of execution, which makes it possible to draw the strip material under better conditions.

The bag with a valve 12a constitutes the form preferred embodiment of the invention. However, given of the effectiveness of the tubular joint 7a, this valve could be deleted as long as before its first use, the delivery duct 21 of the bag is closed by a removable shutter such as a plug, then only after first use, the sachet either or capped, or constantly maintained in a position where the outlet opening of the distribution duct 21 is not below the liquid level in the bag.

Claims (13)

1. Bag for packaging liquid formed using plastic in film form, comprising a leaktight chamber (30) for the liquid and a pocket (15, 33), adjacent to this chamber (30), in which a pipe (21) for withdrawing the liquid is housed, means (4) being provided to give access to the inside of the said pocket (15, 33), an opening (7) being formed through part of the wall of this pocket (15, 33), adjacent to the said chamber (30), to allow the said withdrawing pipe (21) to enter the said chamber (30) in a leaktight fashion, characterized in that the said opening (7) is situated at the end of a tubular element (7a) of decreasing section, at the place where the section is the smallest, the element being formed from a film (3, 35) of plastic forming one wall of the said pocket (15, 33) adjacent to the said chamber (30), this tubular element (7a) being intended to accommodate the said pipe (21) for withdrawing the liquid from the chamber (30), the section of which is at least equal to that of the said opening (7), so that the said tubular element (7a) forms a seal around the said withdrawing pipe (21).
2. Bag according to Claim 1, characterized in that the said means (4) for giving access to the inside of the said pocket (15, 33) comprise a tab (4) cut from one of the layers of film (1) intended to form the said chamber (30) and in that the said tab (4), with the exception of its free end (4a), is attached to one of the layers of film (3, 35) forming the said pocket (15, 33), this attachment also extending right around the periphery of this tab (4).
3. Bag according to either of the preceding claims, characterized in that it comprises a first layer of film (1) forming one of the walls of the said chamber (30) and a second layer of film (35), two edges of these first and second layers (1, 35) being adjacent to one another, while the opposite edge of the second layer (35) is situated an appreciably shorter distance away from these adjacent edges than the opposite edge of the first layer (1), a third layer of film (36) covers the second layer (35), one of its edges being aligned with the adjacent edges of the first and second layers (1, 35), these second and third layers (35, 36) being attached along the free edge of the second layer (35) to form the bottom (38) of the said pocket (15, 33), the opposite edge of this third layer (36) to the said adjacent edges extending beyond the bottom (38) of the said pocket (15, 33), a fourth layer of film (37), two opposite edges of which coincide with those of the third layer (36) covering the latter, these third and fourth layers (36, 37) being attached between the bottom (38) of the said pocket (15, 33) and their edges which lie beyond this bottom (38), along two non-converging lines (11) to form a passage (12), the axis of which is more or less perpendicular to the said bottom (38), this passage (12) communicating on the one hand with the said opening (7) and on the other hand with the inside of the said chamber (30), the walls of this passage (12) being intended to be parted by the said dispensing pipe and to close back up in the absence of this pipe in order to control the passage of the liquid, a fifth layer of film (1), forming the second wall of this chamber, being attached around the periphery of the first layer of film.
4. Leaktight bag according to either one of Claims 1 and 2, characterized in that it contains a passage (12) which is open at both ends for controlling the flow of liquid between the inside and the outside of the bag, this passage being formed between two adjacent layers of film (2) of plastic joined together along two non-converging connecting lines (11), the opening of the section of this passage (12) being obtained by parting the said layers of film (2) from one another, two other adjacent layers of film (3) which come from one and the same film of plastic folded over on itself and whose length, perpendicular to the axis (3a) of folding, is appreciably shorter than the corresponding length of the said two first layers of film (2) being inserted between them, the other end of the said passage (12) being adjacent to the said fold (3a), the said tubular element of conical shape (7a) being formed across the said fold and entering the opening of the said passage (12), which opening is adjacent to this fold (3a).
5. Leaktight bag according to Claim 4, characterized in that its wall (1) is formed by folding a film (1) on itself about an axis parallel to the axis (3a) about which the second pair (3) of films is folded.
6. Leaktight bag according to Claim 5, characterized in that the two said layers of film (2, 3) come from one and the same sheet folded about three parallel axes.
7. Leaktight bag according to Claim 4, characterized in that the said common sheet is formed by a tube.
8. Leaktight bag according to one of the preceding claims, characterized in that the said pocket (15) is divided into a number of compartments (31, 32, 33).
9. Method for the manufacture of bags and for packaging liquid in these bags continuously, according to one of the preceding claims, starting from a film of plastic in strip form, characterized in that film in strip form is made to travel longitudinally and in that the bottom of the said pocket (15, 33) is formed between two layers of film in strip form by attaching two films (35, 36) in strip form or by longitudinally folding a film (3) in strip form, two layers of film (1) in strip form appreciably wider than the depth of the said pocket (15, 33) and intended to form the said chamber (30) are superimposed with the two faces of the said pocket (15, 33) and one of their respective edges is aligned with the edges of the opening of the said pocket (15, 33) so that access can be had laterally between these layers of film (3; 35, 36) and in that these layers (1, 3, 35, 36) are made to travel vertically downwards, the layers of film (3; 35, 36) forming the said pocket (15, 33) are parted, and the said tubular seal (7a) and the said opening (7) are formed through a portion of its wall (3, 36) adjacent to the said chamber, a pipe (21) for withdrawing the liquid from the chamber (30) is inserted through this tubular seal (7a), two attachment lines (24, 25) appreciably perpendicular to the fold line (3a) or join line (38) of the walls (3; 35, 36) of the pocket are formed, one on either side of the said withdrawing pipe (21), between this fold (3a) or this join line (38) and the edge of the said strip where the various layers of film (1, 3, 35, 36) are aligned, these two attachment lines (24, 25) joining together the layers of film (3; 35, 36) forming the pocket to the layer of film (1) forming the wall of the chamber equipped with the means (4) provided to give access to the inside of the said pocket, all the layers of film (1, 3, 35, 36) are then attached, on the one hand transversely (28) to the said strip of film, along the lower edge of the bag during packaging and, on the other hand, along the two longitudinal edges (26, 27) of the said strip of film in order to form the said chamber (30), the upper edge (29) of which is open, this chamber is then filled through this open edge and the said bag is closed by attaching all the layers, transversely, along the upper edge (29) of this chamber (30).
10. Method according to Claim 9, characterized in that the said pocket is formed by arranging a second layer of film (35) in strip form over a first layer (1) forming one of the walls of the said chamber, two longitudinal edges of this first layer (1) and of this second layer (35) being adjacent to one another, the width of this second layer (35) corresponding to the depth of the said pocket, a third layer of film (36) in strip form which is wider is arranged over the second layer (35), the two layers (35, 36) forming the said pocket are attached (38) in the longitudinal direction of the said film in strip form, approximately along the edge of the narrowest layer (35) corresponding to the bottom of the said pocket, a fourth layer of film (37) in strip form with the same width as the third layer (36) is added, this third layer (36) and this fourth layer (37) are attached between the said longitudinal attachment (38) forming the bottom of the said pocket and their edges which lie beyond this bottom, along two non-converging lines (11) to form a passage (12), the axis of which is more or less perpendicular to the said longitudinal attachment (38), and a fifth layer (1) is added to form the second wall of the said chamber (30).
11. Method according to Claim 9, characterized in that
       three strips of film (1, 2, 3) are superimposed, a first strip (1) intended to form the wall of the chamber (30), a second strip (2) intended to form a passage (12) forming a valve (12a) to control the flow of liquid, and a third (3) intended to close the passage (12) of the said valve (12a) in a leaktight fashion, the width of this third strip (3) being appreciably less than that of the second strip (2),
       one of the respective longitudinal edges of these superimposed strips (1, 2, 3) is made to coincide,
       the said second strip (2) and the said third strip (3) are folded onto themselves so that their other respective longitudinal edges are superimposed with their three respective longitudinal edges that were aligned earlier so that the folded-over third strip (3) stretches between the two superimposed halves of the second strip (2) over a portion of its width,
       the edges (11) of the said passage (12) are attached in that part of the said folded-over second strip (2) which is not superimposed with the third strip (3) folded over on itself and, at the same time, the folded-over edges of the said second (2) and third (3) strips are attached to one another, and
       the said passage (12) is cut (18) near its end adjacent to the fold (2a) of the said second strip (2).
12. Method according to Claim 11, characterized in that before the said second (2) and third (3) strips of film are folded, the said three strips (1, 2, 3) are welded together in a region (10) superimposed with the said tab (4), leaving within this region (10) an unwelded portion (10a) opposite the free end (4a) of the tab (4).
13. Method according to one of Claims 9 to 12, characterized in that it takes place in two separate phases, one consisting in forming a continuous strip of part-finished bags in which all the layers (1, 2, 3, 35, 36, 37) are attached to one another but are separate from one another along at least one longitudinal edge (26) and along the transverse edges (28, 29) and the second consisting in forming the said tubular seal (7), in inserting the said withdrawing pipe (21) therein and in packaging the liquid in the said chamber (30).

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