EP0948446A1 - Sealed chamber, method for making and packaging liquid in said chambers - Google Patents

Abstract

The invention concerns a bag for packaging liquid formed by a plastic film, comprising a sealed chamber (30) for the liquid and a pocket (15, 33) in which is located a conduit (21) for drawing the liquid, means (4) being arranged for reaching inside the pocket (15, 33). An opening (7) is formed through part of the wall of said pocket (15, 33), adjacent to the chamber (30), for the drawing conduit (21) to penetrate the chamber (30) in sealed manner. The opening (7) is located at the end of a tubular element (7a) with decreasing cross-section, at the point where the section is smallest, made from a plastic film (3, 35) forming a wall of the pocket (15, 33) adjacent to the chamber (30) and is designed for forming a sealing joint around the drawing conduit (21).

Description

WATERPROOF ENCLOSURE, METHOD OF MANUFACTURING AND PACKAGING OF LIQUID IN THESE ENCLOSURES

The present invention relates to a sachet for packaging liquid formed using plastic film, comprising a sealed enclosure for the liquid and a pocket, adjacent to this enclosure, in which is housed a conduit for sampling the liquid, means being arranged to access the interior of said pocket, an opening being formed through a part of the wall of this pocket, adjacent to said enclosure, to allow said sampling conduit to enter leaktightly said enclosure. This invention also relates to a method of manufacturing sachets and continuously packaging liquid in these sachets.

We have already proposed, in particular in WO 95/23742, a sachet for packaging liquid comprising an integrated valve for controlling the outlet of the liquid and capable of being continuously produced from a film of thermoplastic material. It has been proposed to associate a straw with this sachet to allow access to the liquid through the valve constituted by a channel formed between two layers of film normally contiguous and which open during the introduction of the straw. Consequently, when the straw is at least partially removed from the valve channel, this channel closes and the liquid can no longer exit. The disadvantage of this system lies in the fact that by removing the straw, it causes the liquid which is in the channel of the valve to come out, gradually dirtying the outside of the sachet.

It is obviously not easy to make an effective seal in such a type of sachet and even less when this sachet is provided with a valve of the aforementioned type. The 5 edges of the channel delimiting the valve are produced by welding the films of thermoplastic material. However, by welding these films, we locally transform the structure of the material of the film, which becomes amorphous and loses its elasticity, thereby adversely affecting the quality of the seal which can be formed. It is also excluded to use an element attached to the inlet end of this valve channel. This clearly shows the complexity of the problem to be solved, the solution having to be adapted to the very low cost price acceptable for a bag of this type. Other problems related to this concept of sachet, the solutions of which are used in combination with the present invention, have already been provided by the inventor of the present invention and have been the subject of other protections. This concerns in particular the question of incorporating a straw into the sachet and the inviolability of this sachet for obvious reasons of health and safety. On the other hand, the problems associated with sealing as well as with a certain method of manufacturing and packaging the liquid continuously had not, until now, received a satisfactory answer. One of these problems is related to the incorporation of a straw into a closed pouch of the package in a manufacturing process on a continuous strip material.

The object of the present invention is precisely to provide a solution to the problem of sealing, as well as to that of the manufacture of sachets and of the continuous packaging of liquid in such sachets, making it possible in particular to use concepts of known machines, even if they are nevertheless required to undergo substantial transformation to adapt to the manufacture and packaging of these sachets. To this end, the present invention firstly relates to a sachet for packaging liquid of the aforementioned type as defined by claim 1. This tubular element of decreasing section is obtained by stretching a plastic film and thus allows to keep the elasticity of the film, guaranteeing an effective seal. It is also a very simple solution, perfectly suited to the product for which it is intended. Preferably, the wall of the pocket containing said sampling conduit is integral with a tongue cut from a layer of film intended to form the sealed enclosure. This tab makes it possible to guarantee the inviolability of the access to the straw serving as a conduit for distributing the liquid.

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

As a variant, this pocket can however be formed in the fold of a film folded back on itself. Preferably, this fold can be located adjacent to one end of the channel controlling the flow of the liquid and the tubular element forming a seal can extend over part of this channel. This invention also relates to a process for the manufacture of sachets and the continuous packaging of liquid in these sachets according to claim 9. One of the advantages of this method is that it allows the sachets to be filled and the straws to be placed laterally. , one of the longitudinal edges of the strip material intended to form one of the edges of these sachets remaining open until the time of filling. Because of this, the straw can be introduced laterally in the axis of the seal and of the valve channel when this channel exists, and a liquid supply conduit can pass between the walls of the sachet, along its edge coinciding with the longitudinal edge of the strip material. The welding of this longitudinal edge is carried out as the strip material advances, just before filling.

Advantageously, the process takes place in two distinct phases, one consisting in forming a continuous strip of blanks of sachets, the second consisting in forming the tubular joint, in introducing the sampling conduit therein and in conditioning the liquid in the enclosure. The advantage of this embodiment is that it allows the production of the blanks and the packaging of the liquid in two separate production units, the product conditioner not necessarily being able to solve the problems posed by the manufacture of such a sachet. .

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

One of the main advantages of the enclosure which is the subject of the invention is to have a sealing of the valve channel which, by piercing this seal not by cutting, but by punctual deformation of the seal in the direction of the valve channel until it breaks, to obtain a slightly conical annular seal which guarantees an elastic clamping of the straw, ensuring a seal which makes it possible to prevent the liquid in the valve channel from escaping. In addition, the two faces of the enclosure from the same sheet folded back on itself do not undergo any offset therebetween, so that it is the same for the screen-printed inscriptions placed on the two faces of this enclosure.

Thanks to the packaging method according to the invention, the pocket intended to accommodate the curved part of the straw situated outside the valve channel is produced after the introduction of the straw into the inlet of this channel, so that the straw does not pull on the side welds of the pocket.

Other advantages and other variants will become apparent in the course of 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.

FIG. 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 superimposed of sheet material, the third of which is substantially narrower in width than the first two. The first sheet 1, which is intended to form the wall of a sealed enclosure, in this example, a sachet for packaging a liquid, in particular a drink, is preferably constituted by a sheet of multilayer plastic material, as commonly used for the packaging of food products. The different layers of these multilayer sheets can be formed from different plastics or from the same material, 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 film of extruded plastic, in particular polyethylene, as is the third sheet 3. It should also be specified here that, even if sheets 2 and 3 have been shown as being initially two separate sheets, they could also initially form a common sheet, folded around an axis longitudinal to that of this strip sheet, to then form the two sheets 2 and 3 of different widths shown in Figures 1 and 2.

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

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

The first manufacturing step of the process consists, in this example, in cutting a tab 4 in the first sheet 1 intended to form the wall of the bag. This tab 4 remains attached to the sheet 1 by one end. The cutting tools are symbolized by rectangles 5 and 6 in Figure 2. During the same step, we can drill the sheet 3 in the middle of its width to form a hole

7 for the passage of a straw. The tools for making this hole 7 are symbolized by a conical punch 8 and a matrix 9 in FIG. 2. The manner of making this hole 7 is important. It is not a question of cutting this hole 7, but of punctually stretching the film using the punch

8 in the housing formed in the matrix 9, until the film 3 breaks. As a result, the material of the film surrounding the opening 7 deforms while flowing, forming a sort 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 by which the punch 8 has pierced this hole 7, this hole being calibrated for be of a diameter very slightly smaller than that of the straw 21, the tubular part 7a produced during the drilling of this hole 7 encloses the straw 21 and forms a seal around it. As a variant, it is possible to imagine welding on the film 3 a washer of the same plastic material as this film 3 at the place where the hole 7 must be drilled, so as to reinforce the tubular part surrounding the hole 7.

The following operation, illustrated by FIGS. 3 and 4, consists in welding together the three sheets 1, 2, 3 in the part where the tongue 4 has been cut. The weld 10 obtained covers the entire tongue 4, but it provides an area 10a which is not welded, superimposed on the free end 4a of the tongue 4. With 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 the three sheets of film 1, 2, 3 together, so that no movement can occur between them. It is known in fact that plastics are liable to creep following a traction exerted on them. These sheets also undergo significant variations in size following variations in temperature, as well as variations in the humidity. When one works as here on a strip material which can reach a length of several hundred meters, these variations can be expressed in the long run by large shifts. By joining the films at the start of the manufacturing process, it is guaranteed that the operations carried out subsequently on the different sheets will be carried out in relative positions which can no longer vary in troublesome proportions.

The next step, illustrated by FIGS. 5 and 6, consists in folding the sheets 2 and 3 back on themselves in the direction of the width of the strips, around two longitudinal folding axes to form two parallel folds 2a, 3a. By folding these sheets 2, 3 back on themselves, the longitudinal edges of these sheets 2 and 3 are aligned on the left longitudinal edge, also corresponding to one of the edges of the sheet 1 for forming the wall of the bag. Due to the difference in width of the sheets 2 and 3 in strips, these folded sheets 2, 3 only overlap in the part of the width of these strips adjacent to the superimposed edges of these strips. The sheet 1, for its part, is separated from the sheet 2 in order to allow access to the latter.

If we start from a single tubular film, as mentioned previously by way of a variant, we proceed by folding parallel to the axis of the tube as has already been explained with regard to this variant. During the step illustrated in FIGS. 7 and 8, two non-convergent 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 d '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 conditioned liquid in the sachet. Simultaneously, the two longitudinal edges of the folded parts of the film sheets 2 and 3 are fixed to each other by a longitudinal weld 13. As illustrated in FIG. 8, a separator 14 is inserted between the two folded parts of the 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. The tools used 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 cutting 18 of the two superimposed films from the folding of the sheet 2, performed using two tools symbolized by the rectangles 19 and 20 of Figure 10. This cutting has the shape of a U whose two parallel branches are asymmetrical. The transverse branch of this cutout 18 is located near the end of the channel 12 adjacent to the fold of the sheet 2. This cutout 18 is intended to communicate the channel 12 with the interior 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 to improve its operation, in cooperation with the asymmetrical narrowing of the section of the channel 12.

This stage corresponds to the end of the manufacturing of the blank of the sachet. That is to say that, up to this stage of manufacture, the blank obtained can be rewound to be transported to another manufacturer in order to condition liquid in future sachets which it will finish by conditioning the liquid , as we will explain. Of course, this is only a possibility to which the invention is obviously not limited. It is indeed possible to carry out the packaging online following the steps of the manufacturing process described so far.

Figures 11 and 12 show the establishment of the straw 21 between the two folded film portions of the sheet 3, into the first part of the channel 12 through the opening 7 formed at the end of the seal tubular 7a which has been discussed previously. It should be noted that, as a variant, the hole 7 could be made using the straw 21 itself or a separate tool, just before the introduction of the straw 21 and not during manufacture. of the blank, as described above. In this variant, the hole 7 could also be primed during the manufacture of the blank, to facilitate drilling using the straw 21. As illustrated by these figures, the end of the straw 21 has a bulge annular 21a whose purpose is to provide resistance when the straw 21 is removed from the channel 12 and this bulge arrives at the opening 7. As illustrated by FIGS. 11 and 12, clamps 22 arranged on each side of the straw 21 serve to retain the blanks of sachets during the introduction of the straw 21. As a variant, the annular bulge 21a of the straw 21 can advantageously be replaced by a deformation of the end of the straw which is turned outwards over a certain length, advantageously a few mm, as is done with a sock . This reversal can easily be obtained hot. The inverted part forms an annular space in which the tubular seal 7a can engage when an attempt is made to remove the straw 21 from this seal, thus forming a stop. The last step before packaging the liquid consists in connecting the end of the channel 12 adjacent to the fold 3a of the third film sheet 3, at the longitudinal edge where all the longitudinal edges of the sheets 1, 2 and 3 are superimposed 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 longitudinal edge, during the packaging of the liquid, as will be seen below. These two welds 24 and 25 divide the pocket 15 formed between the two adjacent films of the folded sheet 3, into three compartments 31, 32, 33, the last 33 of which contains the folded part of the straw 21. These welds 24 and 25 bring together together the two folded sheets 2 and 3 with the sheet 1 not yet folded, that is to say that once the bag 30 is finished, the two folded sheets 2, 3 will be integral with the same internal face of this bag 30.

Figures 15 and 16 show the finished bag 30. The finishing of this sachet is carried out during the packaging of the liquid, it consists in longitudinally folding the 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 formed between the longitudinal welds 26 and 27. This weld 28 is intended for form the bottom of the bag 30 which is then filled by the fourth side which remains open for this purpose, after which the bag is closed by a second transverse weld 29. The bag 30 thus obtained is separated from the strip material to which it was attached so far, by cutting this material into a strip flush with the welds 28 and 29.

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

To consume the contents of the sachet 30, when it is a drink, it suffices to grasp the end 4a of the tongue 4 and pull it in the direction of the weld 26, thus tearing the three superimposed layers and welded together by the weld 10, at the welds 24 and 25, thus giving access to the interior of the compartment 33 containing the curved part of the straw 21. The end of this curved part is grasped and one 1 ' away from the outside of compartment 33, the straw 21 is then pushed further into the channel 12 to spread the part of the adjacent films of the sheet 2 forming the valve 12a and the liquid is sucked through the straw 21. If the we do not want to consume all the contents of the bag 30, it suffices to remove the straw in the position illustrated in FIG. 15, so that the valve 12a formed in the channel 12 closes. As for the liquid which is in the rest of the channel 12, it is prevented from coming out thanks to the seal 7a which encloses the straw 21 around the opening 7 formed through the sheet 3. As a result, the outside of the sachet always remains clean and dry. The seal 7a in cooperation with the annular bulge 21a of the straw 21 also serves to avoid accidental withdrawal of the straw 21 from the channel 12. This is the reason why it may be useful to locally reinforce the portion of the film 3 forming this joint 7a, as mentioned previously. The closed compartments 31, 32 located on either side of the compartment 33 containing the curved part of the straw 21, are isolated from the main enclosure of the bag 30 intended to contain the liquid, formed between the two folded parts of the sheet. 1. These compartments could be used to receive all kinds of articles, objects, surprises, advertisements, games or play items etc., which can be inserted during the operation of packaging the liquid in 1 main enclosure of the bag 30.

In a final variant of this first embodiment, one could imagine starting from a single sheet or strip folded longitudinally to produce the assembly of the enclosure and the valve described above, which has nothing to do with impossible in terms of the method according to the present invention. However, it should be noted that in the current state of knowledge that we have of plastics available on the market, it is preferable that the wall 1 of the bag is formed by a PE / PET laminate. However, PET does not weld on itself, hence the impossibility of using it for layers 2 and 3. In addition, sheets formed solely of PE to form the walls of the sachet do not give very good results with regard to the tearing of the tongue 4 for the opening of the bag. In the tests carried out, excellent results have been obtained in forming the wall of the sachet, with PE / PET sheets whose respective thicknesses are 100 and 12 μm, the thin layer of PET making it possible to obtain a clean cut of the tab 4 when opening. The different stages of the process described above are called to undergo permutations according to the manufacturing methods adopted. It is in fact possible to adopt a step-by-step manufacturing mode or a manufacturing mode in which the strip or strips advance continuously and in which the operating members on the production line are of the rotary type. Such a manufacturing method is likely to reach faster production rates and is therefore potentially much more interesting. In the case of the use of a tubular film to produce the folded sheets 2 and 3, as mentioned previously as a variant, it is also necessary for the tubular element to scroll continuously. To make continuous scrolling possible in all cases, it may be necessary to provide, for certain welding operations in particular, a strip accumulation device by forming meanders on rollers elastically suspended on either side. of the strip, so that it can be gradually arranged in line in the event that a temporary stop of this strip occurs upstream. Such a device is not necessary if the welding stations are of the "accompanying" type.

To make it possible to selectively weld together certain superimposed sheets and not others, separators are interposed in the corresponding parts of the trajectory of the film strip or strips. In the case of "accompanying" welds, the separators will be driven by reciprocating movements in the direction of travel of these strips to enable tracking of the movement of the welding electrodes or of the cutting punches.

Since the sachets provided with valves according to the invention can be produced 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 FIG. 6, after which the cutting and welding operations are started in the order described above. It may however be mentioned that the welding 10 superimposed on the tongue 4 and around the end 4a of this tongue 4 can preferably be carried out simultaneously with the welding 11 of the channel 12 of the valve illustrated in the 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 conditioning the liquid in the sachet.

The bag according to the second embodiment, the manufacturing process of which is illustrated in FIGS. 17 to 24, differs from that described above essentially in that the bag 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 of the valve 12a is formed by the two non-convergent welds 11. Unlike the previous embodiment, this channel 12 is preferably not not formed by a sheet folded 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 the sheet 36 forming one of the walls of the channel 12 (Figures 17 and 18).

In this second embodiment, most of the steps of the method are similar to those of the first embodiment, therefore, to avoid unnecessary repetitions, these steps 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 (FIGS. 17, 18) by cutting tools 39, 40 and this tab 4 is welded to the sheet 35 by a weld 10 with the exception of its end 4a which is located in the zone 10a which is not welded (FIG. 19, 20), by welding tools 41, 42. As before, this weld 10 extends all around the tab 4 to isolate it from the liquid situated inside it from the sachet.

Then, the sheet 1 forming the wall of the sachet is folded longitudinally in half to bring its two edges to meet, these edges being aligned with one of the edges of each film ribbon 35, 36 and 37. This step marks the last of the process for manufacturing the blank of the sachet according to the present invention. Two possibilities are then possible: the strip along which one succeeds a plurality of regularly spaced blanks continues on a liquid packaging unit, or this strip of blanks is wound to be transported to a separate packaging unit. Figures 23 and 24 illustrate the first step of the packaging process, the others will not be described since it suffices to refer to the previous embodiment in which the subsequent steps relating to the packaging process are the same as for this second embodiment.

While in the first embodiment, the tubular joint 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 for - mant 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 a tool 42.

For the rest of the operations relating to the introduction of the straw 21, the filling of the liquid and the closing of the sachet, these being similar to those described in relation to the previous embodiment, it suffices to refer to the part of the description relating to the packaging of the liquid of this first embodiment. One of the advantages of the method of manufacturing this second embodiment of the sachet comes from the fact that the film 1 intended to form the wall of the sachet remains flat and must not be spread down as in the first form d 'execution, which allows the drawing of the strip material in better conditions.

The bag provided with a valve 12a constitutes the preferred embodiment of the invention. However, taking into account the efficiency of the tubular joint 7a, this valve could be omitted provided that before its first use, the dispensing conduit 21 of the bag is closed by a removable shutter such as a plug, then that after the first use, the sachet is either capped, or tautly maintained in a position where the outlet opening of the dispensing conduit 21 is not below the level of the liquid in the sachet.

Claims

1. Sachet for packaging liquid formed using plastic film, comprising a sealed enclosure (30) for the liquid and a pocket (15, 33), adjacent to this enclosure (30), in which is housed a liquid sampling conduit (21), means (4) being arranged to access the interior of said pocket (15, 33), an opening (7) being formed through a part of the wall of this pocket ( 15, 33), adjacent to said enclosure (30), to allow said sampling conduit (21) to enter in a sealed manner into said enclosure (30), characterized in that said opening (7) is located at the end a tubular element (7a) of decreasing section, at the point where the section is the smallest, formed from a film (3, 35) of plastic material forming a wall of said pocket (15, 33) adjacent to said enclosure (30), this tubular element (7a) being intended to receive said sampling conduit (21) liquid from the enclosure (30) whose section is at least equal to that of said opening (7), so that said tubular element (7a) forms a seal around said sampling conduit (21).

2. Bag according to claim 1, characterized in that said means (4) for accessing the interior of said pocket (15, 33) comprise a tongue (4) cut from one of the layers of film (1) intended to form said enclosure (30) and in that said tongue (4), with the exception of its free end (4a), is assembled with one of the layers of film (3, 35) forming said pocket (15, 33), this assembly also extending over the entire periphery of this tongue (4).

3. Bag according to one of the preceding claims, characterized in that it comprises a first layer of film (1) forming one of the walls of said enclosure (30) and a second layer of film (35), two edges of these first and second layers (1, 35) being adjacent to each other, while the opposite edge of the second layer (35) is located at a distance from these adjacent edges substantially smaller 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 cents of the first and second layers (1, 35), these second and third layers (35, 36) being assembled along the free edge of the second layer (35) to form the bottom (38) of said pocket (15, 33 ), the edge of this third layer (36) opposite said adjacent edges extending beyond the bottom (38) of 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 assembled between the bottom (38) of said pocket (15, 33) and their edges located beyond this bottom (38) , along two non-converging lines (11) to form a channel (12) with an axis substantially perpendicular to said bottom (38 ) this channel (12) communicating on the one hand with said opening (7) and, on the other hand with the interior of said enclosure (30), the walls of this channel (12) being intended to be separated by said conduit distribution and to close in the absence of this conduit to control the passage of the liquid, a fifth layer of film (1) forming the second wall of this enclosure, being assembled around the first layer of film.

4. Waterproof bag according to one of claims 1 and 2, characterized in that it contains a channel (12) open at its two ends for controlling the flow of liquid between the inside and the outside of the bag. , this channel being formed between two adjacent film layers (2) of plastic material joined along two non-convergent connecting lines (11), the opening of the section of this channel (12) being obtained by spacing of said film layers

(2) one from the other, two other adjacent film layers

(3) from the same plastic film folded back on itself, the length of which, perpendicular to the folding axis (3a), is substantially shorter than the corresponding length of said first two layers of film (2) , being inserted therebetween, the other end of said channel (12) being adjacent to said fold (3a), said tubular element of conical shape (7a) being formed through said fold and penetrating into the opening of said channel (12) adjacent to this fold (3a).

5. A waterproof bag according to claim 4, characterized in that its wall (1) is formed by folding a film (1) on itself around an axis parallel to the folding axis (3a) of the second pair (3) of films.

6. A waterproof bag according to claim 5, characterized in that the two said layers of film (2, 3) come from the same sheet folded around three parallel axes.

7. Sealed bag according to claim 4, characterized in that said common sheet is formed by a tube.

8. Waterproof bag according to one of the preceding claims, characterized in that said pocket (15) is divided into several compartments (31, 32, 33).

9. A method of manufacturing sachets and packaging liquid in these sachets continuously, according to one of the preceding claims, from strip plastic film, characterized in that the strip film is passed longitudinally and that the bottom of said pocket (15, 33) is formed between two layers of strip film by assembling two strip films (35, 36) or longitudinal folding of a strip film (3), on the two faces of said pocket (15, 33) two layers of strip film (1) substantially wider than the depth of said pocket (15, 33), intended to form said enclosure (30) and one of their edges is aligned respective on the edges of the opening of said pocket (15, 33) to allow lateral access between these layers of film (3; 35, 36) and in that these layers are scrolled (1, 3, 35, 36) vertically from top to bottom, the film layers (3; 35, 36) are spread apart forming said pocket (15, 33) and m swimming said tubular seal (7a) and said opening (7) through a portion of its wall (3, 36) adjacent said chamber, introducing a withdrawing pipe (21) liquid from the enclosure (30) through this tubular joint (7a), two assembly lines (24, 25) are formed substantially perpendicular to the fold line (3a) or junction line (38) of the walls (3; 35, 36) of the pocket, on either side of said sampling conduit (21), between this fold (3a) or this junction line (38) and the edge of said strip where the different layers of film (1 , 3, 35, 36) are aligned, these two assembly lines (24, 25) connecting the film layers (3; 35, 36) forming the pocket to the film layer (1) forming the wall the enclosure provided with means (4) arranged to access the interior of said pocket, all the layers of film (1, 3, 35, 36) are then assembled, on the one hand transversely (28) to said strip of film, along the lower edge of the sachet during packaging, and on the other hand along the two longitudinal edges (26, 27) of said film strip to form said enclosure (30), the upper edge (29 ) East open, this enclosure is filled through this open edge and the said bag is closed by assembling all the layers, transversely along the upper edge (29) of this enclosure (30).

10. Method according to claim 9, characterized in that said pocket is formed by placing a second layer of strip film (35) on a first layer (1) forming one of the walls of said enclosure, two longitudinal edges of these first (1) and second (35) layers being adjacent to each other, the width of this second layer (35) corresponding to the depth of said pocket, there is a third layer of strip film (36) of greater width on the second layer (35), an assembly (38) is carried out in the longitudinal direction of said strip film between the two layers (35, 36) forming said pocket substantially along the edge of the layer (35 ) the less wide corresponding to the bottom of said pocket, a fourth layer of strip film (37) of the same width as that of the third layer (36) is added, these third (36) and fourth (37) layers are assembled between said longitudinal assembly (38) forming the bottom of said pocket and l their edges located beyond this bottom, along two non-converging lines (11) to form a channel (12) of axis substantially perpendicular to said longitudinal assembly (38) and a fifth layer (1) is added to form the second wall of said pregnant (30).

11. Method according to claim 9, characterized in that three film strips (1,2,3) are superimposed, a first (1) intended to form the wall of the enclosure (30), a second (2 ) intended to constitute a channel (12) forming a valve (12a) for controlling the flow of the liquid and a third (3) intended for sealing the channel (12) of said valve (12a), the width of this third band (3) being substantially less than that of the second band (2), one of the respective longitudinal edges of these superimposed bands (1,2,3) is made to coincide, said second (2) is folded back on themselves 2) and third (3) strips for superimposing their other respective longitudinal edges on their respective three longitudinal edges previously aligned, so that the third folded strip (3) extends between the two superimposed halves of the second strip (2 ), over a portion of its width, the edges (11) of said channel (12) are assembled , in the part of said second folded strip (2), not superimposed on the third strip (3) folded back on itself and, simultaneously, the folded edges of said second (2) and third are assembled together (3) strips and said channel (12) is cut (18) in the vicinity of its end adjacent to the fold (2a) of said second strip (2).

12. Method according to claim 11, characterized in that, before folding said second (2) and third (3) strips of film, said three strips (1,2,3) are welded together in a superimposed zone (10) to said tongue (4), by providing inside this zone (10), a door tion (10a) not welded vis-à-vis the free end (4a) of the tongue (4).

13. Method according to one of claims 9 to 12, characterized in that it takes place in two distinct phases, one consisting in forming a continuous band of blanks of sachets of which all the layers (1, 2 , 3, 35, 36, 37) are joined to each other, but are separated from each other along at least one longitudinal edge (26) and along the transverse edges (28, 29) the second consisting of forming said tubular joint (7), introducing said sampling conduit (21) therein and conditioning the liquid in said enclosure (30).