US20080105698A1

US20080105698A1 - Flexible Container

Info

Publication number: US20080105698A1
Application number: US11/793,226
Authority: US
Inventors: Massimo Paradiso
Original assignee: Individual
Current assignee: Individual
Priority date: 2004-12-21
Filing date: 2005-12-16
Publication date: 2008-05-08
Also published as: WO2006082473A2; EP1833664A2; WO2006082473A3

Abstract

The present invention relates to a flexible container. In particular, the flexible container for containing either solid or liquid products, comprising a lateral wall of flexible material forming a first and a second end opening, these openings being associated, respectively, with reclosable closing means and a base, wherein the reclosable closing means comprise a stiffening element which forms a passage to allow the exit of the product and can be associated with said first opening so as to stiffen said lateral wall in the proximity of the first opening, and a closing element which can be coupled by means of a positive connection to the stiffening element to close the passage.

Description

The present invention relates to an expandable mandrel (or expansion chuck), a flexible container intended to contain products in either solid or liquid form, and a process for making this container by means of the said expandable mandrel (or expansion chuck), according to the precharacterizing clauses of Claims 1, 12 and 17.
For simplicity of explanation, the present description is provided without restrictive intent with particular reference to a flexible container which is particularly suitable for use in containing food products in powder and granular form, such as ground coffee.
Rigid, semi-rigid and flexible containers for containing liquids or solid substances are commonly used in large-scale distribution of food products. These containers are usually made from multi-layer materials.
For example, there are known flexible containers of the envelope or sachet type, completely heat-sealed on their peripheral edges, consisting of multi-layer flexible materials, and intended to contain food products.
There are also known containers for food products which consist of a single sheet of plastics material wrapped around the product. This sheet is heat-welded on its two opposing flaps in order to form a kind of tubular sachet to enclose the product.
Although these containers are satisfactory in many respects, they have a drawback related to the opening operation.
This is because this type of container becomes torn when the consumer opens it.
This adversely affects the possibility of reclosing the container and means that the product must be consumed in a rather short period, in order to avoid degradation of the organoleptic qualities of the product.
A further drawback concerns the shape of the flexible container. This is because these flexible containers have a truncated conical shape which, while having various advantages, does not provide the maximum storage capacity for a given area used.
In view of the prior art described above, the object of the present invention is to provide a sealed, flexible and reclosable cylindrical container for containing both solid and liquid products.
This object is achieved by means of an expandable mandrel, according to Claim 1, a process for making the flexible container by means of the said expandable mandrel, the said process being in accordance with Claim 12, and the said flexible container, according to Claim 17.
By means of the present invention it is possible to make a flexible container which is inexpensive, more usable and hygienically protected, by comparison with known containers.
Furthermore, according to one embodiment, it is possible to produce a flexible container of cylindrical shape.

Further characteristics and advantages of the expandable mandrel, the flexible container and the production method according to the present invention will be made clear by the following description of a number of preferred examples of embodiment, provided for guidance only and without restrictive intent, with reference to the attached figures, in which:

FIG. 1 shows a partially exploded and partially sectional view of a first embodiment of the flexible container according to the present invention;

FIGS. 2 to 9 show schematically the steps of the process for producing the flexible container of the type shown in FIG. 4, according to the present invention;

FIG. 10 shows a perspective view of the expandable mandrel, in the expanded configuration, used in the process shown in FIGS. 2 to 9, according to the present invention;

FIG. 11 shows a sectional view taken along the line XII-XII of the expandable mandrel of FIG. 13;

FIG. 12 shows a front view of the mandrel of FIG. 11 in the expanded configuration;

FIG. 13 shows a front view of the mandrel of FIG. 11 in the retracted configuration.

With reference to the attached figures, the number 1 indicates the whole of a flexible container for containing either solid or liquid products, particularly food products, such as grains or ground coffee.
The container 1 comprises a containing part formed by a lateral wall of flexible material 2 creating a first opening 3 and a second opening 4. These openings 3 and 4 are associated, respectively, with reclosable closing means 5 and a base 6.
The reclosable closing means 5 comprise:
a stiffening element 7 which can be associated with the said first opening 3; and
a closing element 8 which can be joined by a positive connection to the said stiffening element 7.
It should be noted that the stiffening element 7 can stiffen the lateral wall 2 in the proximity of the first opening 3 and creates a passage which allows the exit of the product contained in the container 1.
In this specific embodiment, the stiffening element 7 consists of a tubular element (or sleeve or ring) having two opposing ends 7A and 7B and a side 7C of predetermined height “H”.
In the specific embodiment which is illustrated, the stiffening element 7 consists of an element with a circular cross section.
Clearly, the use of a stiffening element 7 having a circular section is only preferred, mainly for aesthetic reasons; however, there is no reason why a stiffening element of elliptical or polygonal section should not be used as the stiffening element 7.
In another embodiment (not shown in the attached figures), the stiffening element 7 can comprise a lattice having a number of holes, to permit the measured extraction of the product contained in the container 1.
To close the container 1 and thus prevent the exit of the contained product, the closing element 8 is provided. This closing element 8 consists of a cap 8A having a side 8B.
Preferably, both the stiffening element 7 and the cap 8A can be made by a moulding operation and formed from a thermoplastic material such as polyethylene.
It should be noted that the first opening 3 of the container 1 is associated with the stiffening element 7 by a heat-sealing operation; in other words, the lateral wall 2 is joined to the side 7C by the application of pressure and heat.
In a preferred embodiment, the lateral wall 2 can be joined to the stiffening element 7 on the outer wall of the side 7C. This has the advantageous result that the lateral wall 2 conceals the stiffening element 7 (at least partially) from the view of a user.
Alternatively, the lateral wall 2 can be joined to the stiffening element 7 on the inner wall of the side 7C.
This heat-sealing operation can be carried out with a heating iron of annular shape, or by ultrasound or induction.
It should be noted that the base 6 comprises a side 6A on which the lower end of the lateral wall 2 bears.
In this case also, the operation of heat sealing between the (inner or outer) side 6A of the base 6 can be carried out with a heating iron of annular shape, or by ultrasound or by induction, so as to hermetically seal the opening 4 of the container 1.
The base 6 can be of substantially discoid shape or can have any shape consisting of curved portions joined together.
In the preferred embodiment, the base 6 consists of an element with a circular cross section.
Clearly, the use of the base 6 with a circular cross section is only preferred, mainly for aesthetic reasons: there is no reason why a base of elliptical or polygonal shape should not be used as the base.
The material from which this base 6 is made is, for example, a thermoplastic material. This thermoplastic material is mouldable and can be, for example, polyethylene.
To provide the hermetic sealing of the container 1, the lateral wall 2 of the container 1 is closed on to itself and heat-sealed along a longitudinal profile 2A seamlessly. This produces a containing part which can have a substantially cylindrical or tubular shape.
For this purpose, the lateral wall 2 consists of a polymer film comprising an inner layer which can be heat-sealed on to the inner or outer sides of the base 6 and of the stiffening element 7, and an outer layer which can be heat-sealed along the longitudinal profile 2A. If necessary, the lateral wall 2 also comprises an interposed joining film such as an aluminium (Al) film.
It is also possible to interpose other joining films, such as nylon (N) or cellulose films, for the production of the lateral wall 2.
It should be noted that the material forming the lateral wall 2 is a material compatible with the material forming the base 6 and the stiffening element 7; the term “compatible” denotes that the material forming the lateral wall 2 can be made to adhere, under the action of heat with a simultaneous pressing action, to the thermoplastic material forming the base 6 and the stiffening element 7. Therefore, if the base 6 (and/or the stiffening element 7) consists of polyethylene, the wall 2 will be made from polyethylene, and similarly, if the base 6 (and/or the stiffening element 7) is made from polypropylene, the aforesaid lateral wall 2 will be also made from polypropylene.
This solution provides a container 1, in which the base 6 and the stiffening element 7 and the containing part (in other words the lateral wall 2) form a single whole.
The reclosable closing means 5 additionally comprise a membrane seal 9. This seal 9 extends over the whole area of the first opening 3; in other words, it completely covers the opening 3, thus preventing the exit of the product.
Advantageously, the membrane seal 9 is heat-sealed to the end 7A of the stiffening element 7 by heating (with a heating iron, ultrasound or induction) so as to ensure the perfect adhesion of the seal 9 to the said stiffening element.
For example, the seal 9 consists of a layered laminated sheet which comprises:
an outer layer of polyester which provides the necessary mechanical tear resistance;
an intermediate layer of aluminium; and
a layer of high-adhesion varnish or plastic film which is joined to the stiffening element 7.
The membrane seal 9 is therefore associated with the stiffening element, thus providing effective hygienic protection of the product contained in the container 1.
As shown in the attached figures, the membrane seal 9 is provided with a tab 10 to enable the container 1 to be opened for the first time. This tab 10 is outside the heat-seal, thus providing the user with a convenient and particularly strong gripping point.
The tab 10 makes it possible to carry out the “stripping” operation, in other words the removal of the seal 9.
The membrane seal 9 is therefore a security seal whose removal indicates that the container 1 has been opened.
The presence of the cap 8 enables the opening 3 of the container 1 to be closed when the membrane seal 9 has been removed by the user at the time of first use; the cap 8 then prevents the exit of the product contained in the container 1 and preserves the flavour of the product contained in it.
In the specific embodiment shown in FIG. 1, it should be noted that the positive connection between the stiffening element 7 and the cap 8A takes the form of a pressure or snap-fitting engagement.
For this purpose, the stiffening element 7 has on its side 7C a peripheral rim 7D which can engage with a corresponding peripheral rim 8C formed on the inner surface of the side 8B of the cap 8A.
Alternatively, a different kind of coupling between the stiffening element 7 and the cap 8A is provided. For example, a coupling of the male and female thread type (not shown in the figures) can be provided in place of the aforesaid snap-fitting between the stiffening element 7 and the cap 8A.
For this purpose, the stiffening element 7 would have a plurality of threads on its outer side for engagement with corresponding threads present on the inner surface of the side 8B of the cap 8A.
Clearly, a person skilled in the art can replace the aforesaid snap-fitting or the aforesaid male and female thread coupling between the stiffening element 7 and the closing element 8 with other types of engagement or coupling which are structurally and/or functionally equivalent.
It should be noted that the diameter D1 of the base 6, in the preferred embodiment, can be identical to the diameter D2 of the stiffening element 7.
In this case, the shape assumed by the container 1 is cylindrical.
For reasons which will be made clearer by the rest of the description, a perfectly cylindrical container, of the type shown in FIG. 4, is produced by means of a process which forms an object of the present invention.
In use, a user wishing to dispense a quantity of product must initially remove the cap 8A so as to uncover the membrane seal 9. The removal of the cap 8A takes place in different ways, according to the type of engagement provided between the stiffening element 7 and the cap 8A, in other words by exerting a tractive force or by unscrewing the cap respectively.
The user then exerts a tractive force by means of the tab 10 to enable the membrane seal 9 to be fully removed, thus uncovering the opening 3.
Finally, the user inclines the container 1, to cause the product contained in the container to pass out through the passage delimited by the stiffening element 7.
When the desired quantity of product has been dispensed, the user re-seals the container by fitting the cap 8A.
A description will now be given of a method of producing the flexible container 1, particularly a process for producing a flexible container of the type shown in FIG. 4, using an expandable mandrel 11.
For the reasons which will be explained more fully in the rest of the description, the expandable mandrel 11 (FIGS. 10 to 13) is of the type which can cause a circumferential expansion of the body 11A of the mandrel 11, in other words of the type which can change from a first retracted or minimum diameter configuration (FIG. 13) to a second expanded or maximum diameter configuration (FIG. 12).
It should also be noted that the base 6 and the stiffening element 7, as described above, can be made by a moulding process which is independent from (or outside the line of) the process for making the container 1.
With reference to FIG. 2, the inventive process includes an initial step during which the stiffening element 7 is positioned on the expandable mandrel 11 by means of suitable mechanical manipulators (not shown in the attached figures).
For this purpose, the expandable mandrel 11 advantageously comprises a first circumferential seat 12 for receiving this stiffening element 7.
It should be noted that, in this first step, the expandable mandrel 11 is in the retracted configuration, in other words the minimum diameter configuration (FIG. 13). Advantageously, in this first configuration the mandrel 11 has a diameter D′ which is less than the diameter D2 (or D1) of the stiffening element 7, to facilitate the fitting of the latter on to the mandrel 11.
When the stiffening element 7 has been positioned in the seat 12, the mandrel 11 is radially expanded so as to change to the second configuration (FIG. 12). This expansion causes the lateral wall 20 of the body 11A of the mandrel 11 to expand circumferentially to a diameter D″.
It should be noted that, advantageously, the lateral wall 20 of the body 11A of the mandrel 11 bears on the surface of the inner wall 7E of the stiffening element 7 so as to secure and retain it (FIG. 3).
On completion of the expansion of the mandrel 11, it is then possible to fit the base 6 in a second seat 13 (FIG. 3).
In particular, this second seat 13 is provided at the free end 11B of the mandrel 11, in other words is spaced longitudinally apart from the portion in which the stiffening element 7 is retained.
It should be noted that the base 6 is also fitted on the mandrel by means of mechanical manipulators (not shown in the figures).
However, it should be noted that the base 6 is retained in the seat 13 provided at the free end 11B of the mandrel 11 by means of a suction device (not shown in the figures).
For example, such a suction device may be of the type which can create a fall in atmospheric pressure, in other words which can create a pneumatic vacuum.
For this purpose, the free end 11B of the mandrel 11 comprises a plurality of holes 19 associated for operation with the suction device.
At this point of the process for making the flexible container 1, a step is provided, as shown in FIGS. 10 and 11, in which the containing wall 2 is created.
For this purpose, mechanical equipment, connected for operation to the expandable mandrel 11, is provided for unwinding a flexible film 14 from a reel 15. The mechanical equipment is known and therefore will not be described in the rest of the present text.
It should be noted that the film 14 forms the lateral wall 2 of the flexible container 1.
The free flap 14A of this film 14 is positioned on the body of the mandrel 11 by means of the aforementioned mechanical equipment and is retained in position there by the vacuum generation device (FIG. 11).
This is because this device can provide sufficient suction to retain the film 14 firmly on the body of the mandrel 11.
For this purpose, the lateral wall 20 of the body 11A of the mandrel 11 comprises a plurality of holes 16 positioned longitudinally along the axis X-X.
Advantageously, these holes 16 are associated for operation with the suction device.
In other words, when the flap 14A of the film 14 has been positioned on the body of the mandrel 11, it is retained there by the pneumatic vacuum creation device, so as to form the lateral part 2 of the flexible container 1.
With reference to FIG. 4, it should also be noted that the expandable mandrel 11 can be rotated about its own longitudinal axis X-X by suitable motor means (not shown in the figures).
It should be noted that the rotation of the body of the mandrel 11 must be sufficient to allow an adequate portion of the film 11 to be unwound.
In other words, the rotation of the mandrel 11 must be such that the portion unwound from the reel 15 is sufficient to form the lateral wall 2 of the container 1.
Advantageously, when the mandrel 11 is in the said expanded configuration (FIG. 12), the lateral wall 20 of the body 11A of the mandrel 11 is substantially continuous, so as to provide an adequate support for the flap 14A of the film 14.
This configuration formed by the lateral wall 20 of the body 11A of the mandrel 11 makes it possible to produce a flexible container of the type shown in FIG. 1.
With reference to FIG. 7, when the portion required to create the wall 2 of the container 1 has been wound on to the body 11A of the mandrel 11 and has been retained there by the suction device, a step is provided in which the film 14 is cut by suitable cutting means 14C.
Advantageously, following the cutting operation, a second free flap 14B is created, which is also retained on the lateral wall 20 of the body 11A of the mandrel 11 by means of the pneumatic vacuum creation device.
In other words, the film 14 is wound around the body 11A of the mandrel 11 in such a way that the two flaps 14A and 14B are overlapped (FIG. 9).
With reference to FIG. 9, which shows a further step of the inventive process, it will be noted that there is a sealing unit 17 for carrying out a sealing operation on both flaps 14A and 14B of the film 14 to carry out the longitudinal sealing 2A of the flexible container 1.
It should be noted that the sealing operation consists of a heat-sealing operation which can be carried out by ultrasound or by induction.
With reference to FIGS. 5 and 6, it will be noted that there is a second sealing unit 18, preferably of the type with a sealing head in the form of an arc, for carrying out the operation of heat sealing the film 15 to the stiffening element 7 (FIG. 5) and to the base 6 (FIG. 6) respectively.
Finally, when the container 1 is fully formed, the mandrel 11 is retracted to the minimum diameter D′, enabling the container 1 formed in this way to be removed, for example by means of mechanical manipulators (not shown in the figures).
In an alternative embodiment of the present process for making the container 1, the step of making the containing part of the container 1, in other words the lateral wall 2, can be carried out in one separate operation independently of the process of making the container 1 described herein.
In particular, it is provided that a sufficient portion of the flexible film 14 is unwound from the reel 15 to form the lateral wall 2 of the container 1.
This film 15 is then cut by suitable cutting means, so as to form the two free flaps. At this point, the free ends are heat-sealed together to form a containing part having a substantially tubular shape.
This containing part is then coupled by heat-sealing to the stiffening element 7 and the base 6 according to the steps described above.
A description will now be given of the expandable mandrel 11 which is particularly advantageous for the process of making the flexible container 1 of the type shown in FIG. 1.
The expandable mandrel 11 comprises:
the body 11A extending along the predetermined longitudinal direction X-X having a lateral wall 20;
the lateral wall 20 being formed by a plurality of longitudinal sectors 21 extending parallel to the longitudinal direction X-X; and
actuator means 22 associated for operation with the said plurality of longitudinal sectors 21 to cause a reversible radial expansion of the said plurality of longitudinal sectors 21.
It should be noted that these actuator means 22 enable the mandrel 11 to change between a first retracted configuration (FIG. 16), in which the mandrel 11 has a minimum diameter D′, and a second expanded configuration (FIG. 17), in which the mandrel 11 has a maximum diameter D″.
Advantageously, the change between the first retracted configuration (FIG. 16) and the second expanded configuration (FIG. 17) makes it possible to obtain a corresponding circumferential expansion of the lateral wall 20 of the body 11A of the mandrel 11.
It should be noted that, in the preferred embodiment, the plurality of longitudinal sectors 21 into which the body 11A of the mandrel 11 is divided consists of four longitudinal sectors 21A-21D extending along the longitudinal axis X-X.
Clearly, a person skilled in the art can provide a greater number of sectors, for example six or eight.
Advantageously, the longitudinal sides 23 of each sector of the said plurality of sectors 21 are comb-shaped.
In particular, with reference to FIG. 10, it will be noted that the longitudinal sides 23 of each sector are interleaved in a comblike way with the corresponding longitudinal sides of the adjacent sectors, in such a way that the lateral wall 20 of the said body 11A of the mandrel 11 is substantially continuous when the said plurality of longitudinal sectors 21 are in the said second expanded configuration (FIG. 12).
Advantageously, the opposing sides 23 of the adjacent sectors 21A and 21B are consequently interleaved in a comblike way with each other.
It should be noted that such a configuration of the sides 23 of the plurality of sectors 21A-21D, when the mandrel 11 is in the said expanded configuration (FIG. 10), makes it possible to obtain a lateral wall 20 having a substantially continuous surface, so as to provide an adequate support for the production of the flexible container 1.
In other words, the characteristic according to which the longitudinal sides 23 of each sector 21A-21D are interleaved in a comblike way with the corresponding longitudinal sides of the adjacent sectors makes it possible for the body 11A of the mandrel 11 to have a cylindrical shape.
As described above, the actuator means 22 enable the mandrel 11 to be changed between the first retracted configuration (FIG. 13), in which it has a minimum diameter D′, and the second expanded configuration (FIG. 12), in which it has a maximum diameter D″.
In a preferred embodiment, and with particular reference to FIG. 11, which shows a sectional view of the expandable mandrel 11 of FIG. 10, the actuator means 22 comprise:
a pushing element 24, slidably supported in the said body 11A along the said predetermined longitudinal direction X-X; and
expander means 25 which can expand radially to cause the said radial expansion of the said plurality of longitudinal sectors 21A-21D from the said first retracted configuration (FIG. 13), in which it has a minimum diameter D′, to the second expanded configuration (FIG. 12), in which it has a maximum diameter D″, and vice versa.
It should be noted that, in the embodiment shown in FIG. 11, the expander means 25 comprise at least one sliding block 25A, while the pushing element 24 has a tapered profile 24A at one of its ends.
In the preferred embodiment, the expander means 25 consist of two sliding blocks, each of which is fixed to the body 11A of the mandrel 11 by suitable fixing means 28.
Advantageously, each sliding block 25A is coupled in sliding engagement to the tapered profile 24A of the pushing element 24.
In particular, in a preferred embodiment of the present invention, the coupling between the sliding block 25A and the tapered profile 24A of the said pushing element 24 takes place along an inclined plane, so as to generate a wedge effect between the said sliding block 25A and the said pushing element 24.
It should also be noted that the sliding block 25A is interposed between the said plurality of sectors 21A-21D and the said tapered profile 24A of the said pushing element 24.
In particular, the pushing element 24 consists of a piston which is actuated by actuating means (not shown in the figures).
These actuating means are capable of actuating the said piston with a reciprocating motion between a bottom dead centre, corresponding to the retracted configuration of the mandrel, in other words the configuration in which the mandrel 11 has the minimum diameter D′, to an upper dead centre, corresponding to the expanded configuration of the mandrel 11, in other words the configuration in which the mandrel 11 has the maximum diameter D″.
Therefore, due to the presence of the wedge effect, the linear motion of the pushing element 24 is converted into a radial expansion motion of the plurality of longitudinal sectors 21 so as to provide, in the expanded configuration, a mandrel 11 having a substantially continuous lateral wall 20, thus enabling a flexible container of the type shown in FIG. 1 to be produced by the process described above.
It should also be noted, again with reference to FIG. 11, that the expandable mandrel 11 according to the present invention additionally comprises:
a first circumferential seat 12 for housing the stiffening element 7 of the flexible container 1; and
a second circumferential seat 13, opposite the said first seat 12, the said second seat 13 being capable of receiving the base 6 of the said flexible container 1.
Finally, it should be noted that a plurality of holes 16 associated for operation with the pneumatic vacuum generation device are positioned on the wall 20 of the body 11A of the mandrel 11.
FIG. 14 shows a channel 26 which can provide fluid communication between the holes 16 and the suction device.
Advantageously, the plurality of holes 16 are positioned longitudinally along the direction X-X so as to efficiently retain the flaps 14A and 14B of the flexible film 14.
Additionally, the free end 11B of the mandrel 11 is the seat of a further plurality of holes 19, also associated for operation with the suction device by means of another channel 27.
This plurality of holes 19, as described previously, enables the base 6 to be retained during the process of making the flexible container 1.
A person skilled in the art will be able to make numerous modifications and adaptations to the preferred embodiments of the invention described above, and replace elements with other functionally equivalent ones, without departing from the scope of the following claims.

Claims

1-26. (canceled)

27. Flexible container for containing either solid or liquid products, comprising a lateral wall of flexible material forming a first and a second end opening, these openings being associated, respectively, with reclosable closing means and a base, wherein the reclosable closing means comprise a stiffening element which forms a passage to allow the exit of the product and can be associated with said first opening so as to stiffen said lateral wall in the proximity of the first opening, and a closing element which can be coupled by means of a positive connection to the stiffening element to close the passage.

28. Flexible container according to claim 27, wherein the stiffening element is heat-sealed to the lateral wall at the first opening, and in that the base is heat-sealed to said lateral wall at said second opening.

29. Flexible container according to claim 27, wherein the stiffening element comprises a sleeve in which are formed a side of predetermined height and two opposing ends.

30. Flexible container according to claim 27, wherein in the closing element comprises a cap having an external and internal surface and the lateral wall comprises an inner layer and an outer layer.

31. Flexible container according to claim 30, wherein the external surface of the outer layer of the lateral wall is flush with the external surface of the cap, when the cap is joined by a positive connection to the stiffening element.

32. Flexible container according to claim 30, wherein the inner layer of the lateral wall is heat-sealed on to the outer sides of the base and of the stiffening element.

33. Flexible container according to claim 31, wherein the positive connection comprises a pressure engagement between the stiffening element and the closing element, in which the side of the stiffening element comprises a peripheral rim in the proximity of one of the ends, the peripheral rim being engageable with a corresponding peripheral rim of the cap.

34. Flexible container according to claim 31, wherein the positive connection comprises a male and female thread engagement between the stiffening element and the closing element, in which the side of the stiffening element comprises a plurality of threads in the proximity of one of the ends, which are engageable with corresponding threads of the cap.

35. Flexible container according to claim 27, wherein the closing element comprises a membrane seal.

36. Flexible container according to claim 35, wherein the membrane seal comprises a tab.

37. Flexible container according to claim 36, wherein the membrane seal consists of a layered laminated sheet which comprises:

an outer layer of polyester;

an intermediate layer of aluminium;

a layer of high-adhesion varnish which is joined to the stiffening element.

38. Flexible container according to claim 36, wherein the membrane seal consists of a layered laminated sheet which comprises:

an outer layer of polyester;

an intermediate layer of aluminium;

a plastic film which is joined to the stiffening element.

39. Flexible container according to claim 27, wherein the stiffening element and the closing element are made from thermoplastic material.

40. Flexible container according to claim 27, wherein the diameter of the stiffening element is equal to the diameter of the base, thus producing a container of cylindrical shape.

41. Flexible container according to claim 27, wherein the base is made from the same flexible material as the lateral wall.

42. Flexible container according to claim 27, wherein the inner layer and an outer layer of the lateral consist of a polymer film.

43. Flexible container according to claim 42, wherein the lateral wall comprises an aluminium film being interposed between the inner layer and the outer layer polymer film.