EP1510472B1 - Pouch and package with a pouch - Google Patents

Abstract

The container/dispenser (1) consists of a flask (2) with an inner deformable pouch (5) for the product made from two layers (6, 7) of the same material or different materials, joined together by a direct physico-chemical reaction. Each of the layers of the pouch has at least 80 per cent of its mass made from one or more components of the same chemical family. The container/dispenser (1) consists of a flask (2) with an inner deformable pouch (5) for the product made from two layers (6, 7) of the same material or different materials, joined together by a direct physico-chemical reaction. Each of the layers of the pouch has at least 80 per cent of its mass made from one or more components of the same chemical family. The pouch can have a filler to make it colored or opaque for easy detection, and the layers can be coextruded or made by extrusion blowing; they can also be coextruded with the flask.

Description

The present invention relates to a packaging device according to the preamble of claim 1 and a pouch according to the preamble of claim 18. It finds more particularly its use in the field of packaging devices for sensitive cosmetic products, of liquid to pasty consistency, such as coloring and / or bleaching oxidants, skincare creams, or sunscreens, which must be brought into contact with the air only when they are used. Indeed, the contact with the air generates reduction reactions degrading said cosmetics, which makes them ineffective at the time of their use.

In order to dispense such sensitive cosmetic products under optimum conditions, devices with a bottle are usually used inside which a deformable inner bag is arranged, the product being stored inside the bag. Preferably, these devices are then equipped with means for dispensing the product without air intake. There is therefore a need to make internal pockets both flexible and waterproof. To ensure flexibility of these bags generally made of plastic material, they are generally made thin.

For example, the teaching of the document is known WO-93 / 22,220 , a product dispenser with deformable bag, the bag being inserted a posteriori into the bottle, the bag being previously formed by welding edges of a longitudinal band on itself. The inner bag being made separately from the bottle, its seal can be tested before it is placed in the bottle. But this embodiment has the disadvantage of being long and tedious to implement.

With such vials, in which the inner bag is later reported, there can be provided pockets whose wall is formed by a complex structure, at least tri-layer. The complex structure then forms a laminated laminated material comprising a first impervious layer made of a first material, for example polyethylene, and a second impermeable layer made of a second material, for example polyamide, distinct from the first material. The two layers are then glued to each other by means of a third uniform and intermediate layer of binder or glue to allow adhesion between these two first layers. This complex structure is then cut in the form of panels, the panels are then assembled together to form said pocket.

At present, the majority of packaging: tubes or flasks, used in particular in cosmetics, are made of thermoplastic material. Generally, polyolefins are used, which are recyclable and non-polluting. In general, the polyolefin packages are prepared by extrusion, more particularly by extrusion blow molding, as taught in the document. US 4179251 .

In particular, it is known from the state of the art a coextrusion blow molding process to obtain a bottle and its internal pocket simultaneously, in particular described by the document EP-0182094 . According to this document, the bottle is made of PVC and the inner bag is made of polyethylene.

Polyolefins have good gas and water impermeability properties and have the advantage of being compatible with most chemicals.

However, the polyolefin packaging obtained can have the disadvantage of having micro-holes. By micro-hole means a hole such that the impermeability of a surface in which it is made is no longer ensured locally and brutally, relative to the overall impermeability of said surface. Indeed, when the packages are made by extrusion blow molding, micro-holes, caused by impurities in the plastic at the time of its transformation, appear. The appearance of these micro-holes is all the more important as the thickness of the wall made is fine.

To overcome the leakage problems, in the state of the art, it is known to increase the thickness of the wall at the expense of the flexibility of the internal pocket thus formed.

Preferably, in the invention it is sought to manufacture such a device according to a manufacturing method, simple, easy to implement and inexpensive, preferably using the same manufacturing process to form the bottle and the inner bag of the device.

The use of the same manufacturing process simplifies manufacturing operations, on the other hand it makes it more difficult to carry out quality control tests of the production. Indeed, the inner bag is already inside the bottle at the output of the manufacturing machine, it is impossible to test the bottle and the bag separately, without losing the advantage of having been able to manufacture these two elements by a same process.

A leakproofness test of a pocket consists in placing the pocket cavity in overpressure, and then measuring, after a determined period of time, the variation of the pressure inside the pocket. If no decrease in the inner pressure of the pocket is observed, then the pocket is considered non-leaking. The problem with performing such tests is that they do not allow effective detection of leaks.

Indeed, when the inner bag of a bottle is placed in overpressure, it then sticks tightly around the inner periphery of the bottle, inside which it was made. Thus, if a micro-hole of this bag is plated locally against the inner periphery of the bottle, during the test, the inner periphery of the bottle will close this micro-hole and the micro hole will not be detected. If such internal pocket leak tests are performed in situ, the reliability of such tests is very low.

A device according to the preamble of claim 1 is known from US 4,265,949 .

The subject of the invention is a packaging device for which the bottle and the inner bag can in particular be obtained by the same method, and such that the need to test the tightness of the internal bag can be overcome by choosing a structure of this inner layer to ensure the absence of micro-holes.

The process for obtaining the bag and the bottle is extrusion blow molding. The bag being flexible, to allow a retraction of the bag on itself, inside the bottle, it is essential that during the manufacturing process, there is no adhesion between the inner wall of the bottle. bottle and the outer wall of the pocket. For this purpose, the bottle is made of a first material, and the inner bag is made of a second material. The first material is incompatible with the second material. Thus during the cooling of these materials, the inner bag does not adhere to the bottle.

The innovative structural feature of the pocket consists of providing a pocket whose wall comprises at least two layers contiguous to each other, without the intermediary of binder or glue, to remain at the same time simple while guaranteeing the absence of micro-holes .

Indeed, if one or both layers have one or more micro-holes, because of its manufacture by extrusion, the probability that a hole of a first layer is vis-à-vis a hole the second layer is almost zero. The pocket thus produced in double thickness, from one or more materials of one and the same chemical family, therefore does not have a through hole. This guarantee avoids the risk of leakage on finished products. In addition, this guarantee facilitates leak testing, as only large leaks are likely to occur and only need to be detected. The tests for the detection of micro-leaks, difficult to perform during a production cycle, can be eliminated, which globally improves the process of coextrusion of the bag in the bottle.

The subject of the invention is a packaging device according to claim 1.

In the invention, by physico-chemically compatible materials, materials which, when they are brought into contact with each other in the molten state, are capable of creating physicochemical bonds producing adhesion are understood. of the two materials with each other. Thus, the cohesion of the layers between them is de facto provided, and the integrity of the pocket is thus obtained.

By direct physicochemical reaction, it is understood that the reaction that occurs between the materials, under given temperature and pressure conditions, allows the joining and the adhesion of the layers to one another, the layers being respectively formed from each of these materials. Direct physicochemical reactions exclude reactions requiring the use of a binder between the materials. In particular, the physicochemical reactions take place at temperatures close to the melting temperatures of the different materials. It is then a question of heat-sealing or thermofusion of the materials of the different layers together.

When the reaction is complete, all the layers are brought back to room temperature, around 25 ° C., at which it can be observed that the layers thus assembled are integral with each other.

Preferably, the inner bag has only layers made of the same material and directly contiguous to each other.

Advantageously, each of the two layers comprises at least 80% of its mass represented by the same compound or several compounds of the same chemical family, in all cases the compound (s) chosen (s) for the realization of each of these layers all belong to the same chemical family.

By "chemical family" is meant a group of molecules characterized by the presence of a particular chemical function on each of the molecules of the group.

In this case, and since the first layer is made from a compound of the same chemical family as that of the compound used to form the second layer, the two layers are physico-chemically compatible with each other and adhere perfectly to each other. one to another. They remain welded to each other to form, after cooling, the wall of the inner bag.

Advantageously, said chemical family is chosen from one of the following chemical families of thermoplastic polymers: the family of polyolefins, the family of polyvinyl chloride and their derivatives, the family of styrenics, the family of polyoxymethylenes, the family of polyamides, the family of saturated polyesters, the family of polycarbonates, the family of sulfonic polymers, the family of polyphenylene oxides, the family of cellulosics, and the family of polyurethanes.

According to a preferred embodiment, the two coextruded layers of the inner bag are made from the same compound, representing more than 80% of their mass. This same compound is for example from the family of polyamides, and in this case, preferably polyamide 11.

Alternatively, the two coextruded layers of the inner bag are each made from two distinct compounds, nevertheless from the same chemical family. For example, a first layer of this internal pocket comprises at least 80% of a compound of the family of polyamides, for example polyamide 6,6, whereas a second layer of this internal pocket comprises, it, at least 80% of another compound of this family of polyamides, for example polyamide 11.

In particular, one of the layers forming the inner bag has a charge, colored or not, so as to color or opaque said layer of the inner bag. This change in appearance of one of the layers makes it possible to form a means for detecting the presence of the internal bag in the bottle. The pocket, if it is colored, is easier to detect by cameras installed on the production line and whose images are analyzed in real time on the production line. Alternatively, adjuvants or other molecules with properties such as antistatic, can be incorporated into the composition of said layers. Additives may represent up to 20% by weight of the composition of each of the layers of the inner bag.

Another advantage of placing the coloring filler, or any other type of additive, in only one of the layers of the bag is to make it possible to save on the amount of coloring filler or additive to be used.

Preferably, the coloring filler and / or additives are incorporated into the composition of the inner layer of the bag, which layer does not come into contact with the inner wall of the bottle, said inner layer possibly coming into contact with the product to be stored. This arrangement also makes it possible to avoid interference with the inner wall of the bottle, and in particular makes it possible to avoid adhesion phenomena, which are not desired, and solely caused by the presence of these additives or dyes.

The inner bag is obtained by an extrusion blow molding process. Advantageously, the inner bag and the bottle are coextruded simultaneously through the same extrusion blow molding process.

In particular, the bottle may also be made of a material comprising at least one compound of one of the chemical families of thermoplastic polymers mentioned above. In this case, it is made from one or several compounds from chemical families different from that in which were chosen more than 80% by weight of the constituent compounds of the inner bag.

Advantageously, the bottle is made from a material having a low adhesion with an outer layer of the inner bag, especially during the extrusion blow molding process, to ensure non-adhesion between the outer layer of the inner bag and a inner wall of the bottle.

For example, the bottle may be made from a compound selected from the family of polyolefins, and the bag is then made from one or more compound (s) chosen (s) in the family of polyamides. More particularly, the bottle may be made of high density polyethylene, and at least one of the layers of the inner bag with at least 80% by weight of polyamide 11.

Preferably, the wall of the inner bag has a thickness of between 1/10 and 3 / 10th of a millimeter. The thicknesses of the different layers may be equal to each other, or different, and in the latter case, the outer layer is generally thicker than the inner layer.

Advantageously, the inner bag has an opening arranged so that it is circumscribed in the opening of the bottle. The product can be inserted and removed from the device through these openings. Preferably, the product is stored in the inner bag.

According to a preferred embodiment of the invention, the device is provided with a dispensing means, for example of the type of pumps without air intake, generally called "airless" pumps. These pumps without air intake are widely used, especially in the field of cosmetics for the distribution of care products in the form of a single phase, usually liquid, including body milks, moisturizers or sunscreen products. . Such dispensers are particularly advantageous in that they make it possible in particular to keep the product isolated from the air. Due to their instability in the presence of air, staining and / or discoloration products Capillary can be advantageously distributed by such pump systems without air intake. The pump may be of the piston, membrane or valve type. Such pumps are well known, and therefore require no further detailed description.

At each new operation of such a pump without air intake, the volume of the bag of the bottle on which it is mounted decreases by a value corresponding to the volume of the dispensed dose, so that the product occupies, throughout the life of the device, substantially all the available volume of the internal pocket. For this purpose, the bottle has an air intake port so that the outer periphery of the inner bag is always subjected to ambient pressure.

Alternatively, the device is simply provided with a plug for sealingly and hermetically closing said openings of the inner bag and the bottle. In particular, in the case where the dispensing means is to be mounted on said openings only before use, and after introducing other compositions inside the bottle, and or the inner bag, a plug is then provided for the storage phase of the device.

Advantageously, the product is intended to contain a product of the type of skin care products and or hair.

It is another object of the invention to provide a pouch according to claim 18.

Preferably, the flexible pouch comprises only layers made of the same material and directly contiguous to each other.

Advantageously, the at least two layers are adjacent, such that each of the two layers each comprises at least 80% of their mass represented by the same compound or several compounds of the same chemical family, the compound (s) chosen (s) ) for the realization of these at least two layers belonging to the same chemical family.

Advantageously, the chemical family is chosen from one of the following chemical families of thermoplastic polymers: the family of polyolefins, the family of polyvinyl chloride and their derivatives, the family of styrenics, the family of polyoxymethylenes, the family of polyamides, the family of saturated polyesters, the family of polycarbonates, the family of sulfonic polymers, the family of polyphenylene oxides, the family of cellulosics, and the family of polyurethanes.

Advantageously, the two layers are made from the same compound, for example from the family of polyamides, in particular polyamide 11.

Preferably, a first layer of the pocket is made from a compound of the family of polyamides, for example polyamide 6,6, and a second layer of said pocket is made from a compound different from this same family of polyamides, for example polyamide 11.

For example, one of the layers forming the inner bag may comprise a charge, colored or not, so as to color or to make opaque said layer of the flexible bag.

Advantageously, the flexible pouch forms a wall of a thickness between 1/10 ^th and 3/10 ^th of millimeters, which notably guarantees its flexibility.

• un flacon, et
• une poche interne disposée à l'intérieur du flacon et apte à contenir ledit produit, la poche étant librement déformable à l'intérieur du flacon,

la poche interne comporte plusieurs couches réalisées dans des matériaux différents et physico-chimiquement compatibles entre eux tels que chacune des couches est apte à être accolée à n'importe quelle autre couche de la poche par réaction physico-chimique directe entre lesdits matériaux constituant respectivement chacune de ces couches caractérisé en ce que la poche est obtenue par un procédé d'extrusion soufflage.Alternatively, the subject of the invention is also a device for packaging a product, in particular a cosmetic product, comprising

• a bottle, and
• an inner bag disposed inside the bottle and adapted to contain said product, the bag being freely deformable inside the bottle,

the inner bag comprises several layers made of different materials and physico-chemically compatible with each other such that each of the layers is capable of being contiguous to any other layer of the pocket by direct physico-chemical reaction between said materials respectively constituting each of these layers characterized in that the bag is obtained by a method of extrusion blow molding.

• Figure 1 : un dispositif selon l'invention dans un premier mode de réalisation;
• Figure 2 : un dispositif selon l'invention dans un deuxième mode de réalisation.

The invention will be better understood on reading the description which follows and on examining the figures which accompany it. These are presented only as an indication and in no way limitative of the invention. The figures show:

• Figure 1 a device according to the invention in a first embodiment;
• Figure 2 : a device according to the invention in a second embodiment.

The figure 1 shows a device 1 according to the invention. The device 1 comprises a substantially cylindrical bottle 2 of axis X. The bottle 2 is made of polyethylene. The bottle 2 has an opening 3 orthogonal to the axis X. The bottle 2 is surmounted by a dispensing means 4 of a product P contained in an inner bag 5 disposed inside the bottle 2.

The inner pocket 5 is flexible wall and deformable. It comprises a first inner layer 6 in contact with the product, and a second outer layer 7 which may optionally be brought into contact with the inner wall 8 of the bottle 2. The inner 6 and outer 7 layers are made of the same material, for example polyamide.

The two layers 6 and 7 are perfectly joined and apart from their formation in two layers, the existence of a joint plane between these two layers remains invisible to the naked eye because they are each made simultaneously, in the same material and in the absence of a binder interposed between these layers. In the case where one of the layers has a coloring charge, then the joint plane is visible in a cross-sectional view of the wall of the pocket. Alternatively, a joint plane can also be detected by means of a microscope when analyzing a transverse sectional plane of the wall.

Alternatively, the pocket 5 can be made by joining a plurality of layers of the same material.

Alternatively, the pocket 5 may comprise three layers, two of them being made of an identical material so that an intermediate layer disposed between these two identical layers is made of a physico-chemically compatible material and able to react directly with these two layers. For example, the pocket 5 comprises two layers of polyamide 6,6, between which a layer of polyamide 11 is placed. In another variant, the pocket 5 may comprise a first layer of low density polyethylene contiguous by direct physicochemical reaction to a layer of polyamide. high density polyethylene itself contiguous by direct physicochemical reaction to a layer of polypropylene. In this structure, the low density polyethylene chosen could also be able to react physico-chemically directly with polypropylene. In this structure, the different layers are each physico-chemically compatible respectively two by two with the other layers.

An opening 9 of the bag 5 is circumscribed in the opening 3 of the bottle 2. For example, the bag 5 has a border 10 falling over a periphery 11 of the opening 3. The bottle 2 preferably comprises a collar 12 defining including said opening 3. According to figure 1 , the neck 12 is threaded to retain the dispensing means 4. Alternatively, as shown figure 2 , the neck 12 is also threaded to receive a plug 13 adapted to seal the opening 3 of the bottle 2 and the opening 9 of the bag 5.

In the example presented Figure 1 , the dispensing means 4 is a pump comprising an actuating surface 14 perpendicular to the X axis, a nozzle 15 of the pump directing a jet of product along a path orthogonal to the X axis.

In particular, a pump is mounted without air intake on the device 1. In this case, at each dispensing of a dose of product P, the internal volume of the inner bag 5 decreases by a volume equal to that of the distributed dose. To allow such a retraction of the bag 5 on itself, the bottle 2 has an air intake port 16. Through this orifice 16, the outer periphery 17 of the inner bag 5 is always subjected to pressure atmospheric, and the inner pocket 5 can thus be drained as and when by the pump 4 without air intake.

Nevertheless, other types of distribution means may be considered in the context of the present invention.

The dispensing means 4 optionally comprises a dip tube T, depending on the filling mode, under vacuum or not the product P in the inner bag 5.

In the example presented Figure 1 , the pump 4 is screwed, but it can alternatively be slammed, crimped or even mounted in force.

For example, when the product P contained in the bag 5 must first be mixed with another composition before being dispensed, then the device 1 is initially closed by the plug 13, and only after completion of said mixture, a dispensing means such as 4 is mounted on the neck 12. In this case, the pump delivered separately from the device 1 is provided to be for example screwed around the neck 12, instead of and instead of the plug 13 initially closing the bottle 2.

In the example presented figure 1 the bag 5 is closed at a solder joint 18. At this level, the materials of the bottle 2 and the bag 5 being incompatible, an opening is maintained, it can for example play the role of the air return 16.

Of course, the invention is not limited to the examples which have just been described and it is possible in particular to combine the characteristics of the various exemplary embodiments.

Throughout the description, including the claims, the phrase "comprising two" should be understood as being synonymous with "having at least two", unless the contrary is specified.

Claims (27)

1. Device (1) for packaging a product (P), especially a cosmetic product, comprising:

   - a bottle (2); and

   - an internal pouch (5) placed inside the bottle and capable of containing said product, the pouch being freely deformable inside the bottle, the internal pouch comprising:

   i) either at least two layers (6, 7) made of the same material and joined to each other by a direct physico-chemical reaction between the materials of said at least two layers;

   ii) or first and second layers (6, 7) made of at least two different materials, which are physico-chemically compatible with each other, the first layer (6) being in contact with the product and the second layer (7) being in contact with a space defined between the pouch and an internal wall of the bottle, the first and second layers being joined together by a direct physico-chemical reaction between the material of the first layer and the material of the second layer,

   characterized in that the internal pouch is obtained by an extrusion-blow moulding process.
2. Device according to Claim 1, characterized in that the internal pouch comprises only layers (6, 7) made of the same material and directly joined to each other.
3. Device according to Claim 1 or 2, characterized in that each of the layers comprises at least 80% of their weight represented by the same compound or several compounds of the same chemical family, the compound or compounds chosen for producing these at least two layers belonging to the same chemical family.
4. Device according to Claim 3, characterized in that the chemical family is chosen from one of the following chemical families: the family of polyolefins; the family of polyvinylchlorides and derivates thereof; the family of styrenics; the family of polyoxymethylenes; the family of polyamides; the family of saturated polyesters; the family of polycarbonates; the family of sulphone polymers; the family of polyphenylene oxides; the family of cellulosics; and the family of polyurethanes.
5. Device according to one of Claims 1 to 4,
   characterized in that the two layers are produced from the same compound, for example from the family of polyamides, in particular the polyamide nylon-11.
6. Device according to one of Claims 1 to 4,
   characterized in that a first layer of the pouch is produced from a compound of the family of polyamides, for example the polyamide nylon-6,6, and a second layer of said pouch is produced from a different compound from this same family of polyamides, for example the polyamide nylon-11.
7. Device according to one of Claims 1 to 6,
   characterized in that one of the layers forming the internal pouch includes a coloured or colourless filler so as to colour or render opaque said layer of the internal pouch, so as to form a means of detecting the presence of the internal pouch in the bottle.
8. Device according to Claim 7, characterized in that an inner layer (6) of the internal pouch includes said coloured or colourless filler.
9. Device according to one of Claims 1 to 8, characterized in that the layers of the internal pouch are coextruded.
10. Device according to one of Claims 1 to 9, characterized in that the internal pouch and the bottle are coextruded.
11. Device according to one of Claims 1 to 10, characterized in that the bottle is produced from a material having low adhesion to an outer layer (7) of the internal pouch, especially during the extrusion-blow moulding process, in order to ensure that there is no adhesion between the outer layer of the internal pouch and an inner wall (8) of the bottle.
12. Device according to one of Claims 1 to 11, characterized in that the bottle is produced from a compound chosen from the family of polyolefins and the pouch is produced from one or more compound(s) chosen from the family of polyamides.
13. Device according to one of Claims 1 to 12, characterized in that the internal pouch forms a wall with a thickness of between 0.1 and 0.3 millimetres.
14. Device according to one of Claims 1 to 13, characterized in that an opening (9) in the pouch lies within an opening (3) in the bottle.
15. Device according to one of Claims 1 to 14, characterized in that it includes a means (4) for dispensing the product contained in the pouch, especially of the pump type with no air intake.
16. Device according to one of Claims 1 to 14, characterized in that it includes a cap (13) for closing off the opening (9) in the pouch.
17. Device according to one of Claims 1 to 16, characterized in that the product contained is a skin care or hair care product.
18. Flexible pouch (5) capable of containing a product, especially a cosmetic product, characterized in that the pouch comprises:

    i) either at least two layers (6, 7) made of the same material and joined to each other by a direct physico-chemical reaction between the materials of said at least two layers;

    ii) or first and second layers (6, 7) made of at least two different materials, which are physico-chemically compatible with each other, the first layer (6) being in contact with the product and the second layer (7) defining the external wall of the pouch, the first and second layers being joined together by a direct physico-chemical reaction between the material of the first layer and the material of the second layer,

    and in that the flexible pouch is obtained by an extrusion-blow moulding process.
19. Pouch according to Claim 18, characterized in that the flexible pouch comprises only layers (6, 7) produced from the same material and joined directly to each other.
20. Pouch according to Claim 18, characterized in that it comprises at least two adjacent layers (6, 7), each of the two layers each comprising at least 80% of their mass represented by the same compound or several compounds of the same chemical family, the compound or compounds chosen for producing these at least two layers belonging to the same chemical family.
21. Pouch according to Claim 20, characterized in that the chemical family is chosen from one of the following chemical families of thermoplastic polymers: the family of polyolefins; the family of polyvinylchlorides and derivates thereof; the family of styrenics; the family of polyoxymethylenes; the family of polyamides; the family of saturated polyesters; the family of polycarbonates; the family of sulphone polymers; the family of polyphenylene oxides; the family of cellulosics; and the family of polyurethanes.
22. Pouch according to one of Claims 18 to 21, characterized in that the two layers are produced from the same compound, for example from the family of polyamides, in particular the polyamide nylon-11.
23. Pouch according to one of Claims 18 to 22, characterized in that a first layer of the pouch is produced from a compound of the family of polyamides, for example the polyamide nylon-6,6, and a second layer of said pouch is produced from a different compound from this same family of polyamides, for example the polyamide nylon-11.
24. Pouch according to one of Claims 18 to 23, characterized in that one of the layers forming the internal pouch includes a coloured or colourless filler so as to colour or render opaque said layer of the flexible pouch.
25. Pouch according to one of Claims 18 to 24, characterized in that the flexible pouch forms a wall with a thickness of between 0.1 and 0.3 millimetres.
26. Pouch according to one of Claims 18 to 25, characterized in that it is obtained by an extrusion-blow moulding process.
27. Device (1) for packaging a product (P), especially a cosmetic product, comprising:

    - a bottle (2); and

    - an internal pouch (5) placed inside the bottle and capable of containing said product, the pouch being freely deformable inside the bottle,

    the internal pouch comprising several layers produced from different materials that are physico-chemically compatible with each other, such that each of the layers is capable of being joined to any other layer of the pouch by a direct physico-chemical reaction between said materials constituting each of these layers respectively, characterized in that the flexible pouch is obtained by an extrusion-blow moulding process.

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