IT201600104605A1 - CASING AND MULTILAYER FILM - Google Patents

Description

DESCRIPTION

The present invention relates to a tubular envelope and a multilayer film which can be used to make said envelope. A tube according to the preamble of claim 1 is known from US2605018.

The tubes for containing products (creams or cosmetic pastes, purely by way of example) are mainly divided into three macro-categories, namely aluminum tubes, laminate tubes and plastic tubes.

Each of these categories has its own strengths, but also drawbacks.

More precisely, aluminum tubes are able to offer the best barrier and protection of the product contained in them towards the external environment, but they are expensive, have a high environmental impact by virtue of their weight, and have mediocre surface printing qualities. with current technologies.

Furthermore, these pipes are very easily deformed, accidentally, a circumstance that - upstream of the purchase - makes them defective or dented in the eyes of the consumer.

Laminate tubes have a characteristic three-layer structure and - compared to aluminum tubes - the advantages of these tubes essentially reside in a lower cost and environmental impact, and in a higher surface print quality.

A typical feature of laminate tubes is the so-called phenomenon. of "bounce back". This term refers to the ability of the pipe to resume its original shape after the user's pressure on the walls of the pipe has ended. This return of shape is possible in the face of an aspiration of ambient air inside the tube.

Finally, plastic pipes are made by extrusion, and constitute a segment of medium quality as, on the one hand, they do not guarantee a reliable barrier like aluminum pipes and, on the other hand, they do not allow good communication as they are molded with the same techniques as for aluminum tubes. This type of tube is also characterized by a marked bounce back phenomenon. A progressively greater number of companies is trying to reduce the presence of antioxidants and / or preservatives in the formulations of their products, which will be contained in the tubes of the aforementioned types. The presence of antioxidants and / or preservatives is necessary so that the products do not deteriorate, or degrade over a longer period, in contact with environmental oxygen.

The decrease or elimination of antioxidants and / or preservatives in future products imposes the need to obtain tubes with the least possible bounce back, since - as previously mentioned - the return of shape involves an inevitable aspiration of ambient air (and therefore of oxygen) in the tube, in contact with the product, thus changing its characteristics in a negative and irreversible way.

The present invention is placed in the previous context, proposing to provide a tubular envelope and a multilayer film designed to be manufactured in an economical way, which produce barriers as performing as those of aluminum tubes, but which have a bending return to a reduced extent compared to plastic pipes and laminate pipes.

This object is achieved by means of a wrapper according to claim 1, and by means of a multilayer film according to claim 16. The claims dependent on these show preferred embodiments. The object of the present invention will now be described in detail, with the aid of the attached tables, in which:

Figures 1, 2, 3 show two views from above and a side view of an enclosure object of the present invention, according to a possible embodiment, in different possible conditions of collapse of the enclosure compartment;

- Figures 4, 5 illustrate a casing according to a further embodiment, in which the casing compartment is shown open or unsealed at one end;

figure 6 shows a schematic diagram of a section of a multilayer film object of the present invention, according to an exemplary embodiment;

- Figures 7-39 show possible variants of the stratifications and compositions of the multilayer film.

With reference to the attached tables, the reference number 10 denotes, in its entirety, a tubular casing which comprises a dispensing neck 2 and a flexible wall 4, sealed connected to said neck 2.

For example, this envelope 10 is suitable for containing a food, pharmaceutical or cosmetic product. The flexible wall 4 develops along a prevalent development axis X and delimits a casing compartment 6 for containing the product.

For example, figures 4 and 5 illustrate an intermediate manufacturing step of the envelope 10, in which the compartment 6 is still open at one end 36 of the flexible wall.

The flexible wall 4 consists of a multilayer film 1 and is deformable by an external force F (for example see figure 1) to collapse the housing compartment 6 and force the product through an opening 8 of the dispensing neck 2.

In the three variants shown in Figures 1-3, this force could be exerted in the form of crushing, torsion and / or transversal bending of the flexible wall 4, three possible deformations of the flexible wall are generated.

The multilayer film 1 comprises, as shown schematically in the variant of Figure 6, an outer polymeric layer 12, a metal barrier layer 14 to gas and / or humidity and an inner polymeric layer 16. These layers 12, 14, 16 are joined between them through the thickness A of the film 1 and are closed in a tubular way around the prevailing development axis X.

More precisely, each of the aforementioned layers (and optionally also the layers mentioned below) substantially extends 360 ° around the X axis.

It should be noted that, within this description, the terms "internal" and "external" will be used in relation to the barrier metal layer 14. More precisely, the expression "internal" will be used for the layers facing or facing from the layer 14 towards the envelope compartment, in the conditions of correct use of the flexible film 1.

On the contrary, the expression "external" will refer to the layers and surfaces arranged at the opposite surface of the metal layer 14, towards the external environment.

According to a variant, the multilayer film 1 has a thickness A included in the range 100-300 µm.

According to a further variant, the multilayer film 1 has a thickness A included in the range 120-220 µm. According to a still further variant, the multilayer film 1 has a thickness A included in the range 140-190 µm.

According to a variant, the external polymeric layer 12 has a thickness in the range of 4-40 µm.

According to an advantageous variant, the ratio M between the thickness of the metal barrier layer 14 and the thickness A of the multilayer film 1 is in the range 10-33%.

According to a further advantageous variant, the metal barrier layer 14 has a thickness in the range 20-45 µm.

According to one embodiment, the metal barrier layer 14 consists of or comprises aluminum, or an aluminum alloy.

According to a further embodiment, the polymeric outer layer 12 consists of or comprises polyethylene terephthalate or polyethylene, or consists of or comprises polyphthalaldehyde or oriented polypropylene.

According to a still further embodiment, the polymeric inner layer 16 consists of or comprises polypropylene or polyethylene.

Advantageously, the internal polymeric layer 16 separates the envelope compartment from the metal barrier layer 14, preserving the latter from any aggression of the product.

According to a variant not shown, the internal polymeric layer 16 is fixed - in a direct way - to the metal barrier layer 14.

It should be noted that, within this description, the term "directly" will mean a contact without intermediate states between the indicated layers.

In other words, in this variant the internal polymeric layer preferably creates on the one hand a contact-product layer, and on the other it separates and preserves the metal barrier layer 14.

For example, the inner polymeric layer 16 could comprise or consist of an extruded polymer solidified / cross-linked on a surface of the metal barrier layer 14, and in particular on the surface of the metal barrier layer 14 opposite the outer polymeric layer 12.

According to an advantageous embodiment, the internal polymeric layer 16 forms a sealable layer in a joint line 30 between opposite edges of the multilayer film 1 (specifically to close the flexible wall 4 on itself, in a tubular way) and / or between the flexible wall 4 and the delivery neck 2 of the casing 1.

According to an embodiment, the wrapping 10 comprises this junction line 30 which develops along the prevailing development axis X and in correspondence with which opposite edges of the multilayer film 1 converge to make a seal of the wrapping compartment 6 .

According to a variant not illustrated, the edges of the multilayer film are welded to each other in mutual overlap (in a so-called "lap seal").

In the variants shown in Figures 4 and 5, the thicknesses A of the edges are welded in mutual abutment (edge-to-edge) with a substantially zero overlap of material of the multilayer film 1.

In other words, this variant provides that only the thicknesses of the edges to be welded touch each other, so that the weld does not generate steps - internal or external - on the flexible wall.

According to a preferred variant, the casing 10 could comprise a reinforcement band 32 of the seam 30, which develops between the opposite edges and which is preferably received in the casing compartment 6.

According to different embodiments, the delivery neck 2 is coupled (for example welded or molded) internally or externally to an end 34 of the flexible wall 4.

Optionally, an opposite end 36 of the flexible wall 4 could be sealed by a transverse weld 38 (for example see figure 1 or figure 3) between flattened opposite portions of the flexible wall 4.

According to a preferred variant, the internal polymeric layer 16 is made from a co-extruded film with at least five (or at least seven) layers, at least one of which consists of or comprises ethylene vinyl alcohol. More precisely, the co-extruded film with at least five (or at least seven) layers could comprise polyethylene, ethylene vinyl alcohol and polyethylene, or polypropylene, ethylene vinyl alcohol, polypropylene, optionally bonded or interspersed with layers of maleic anhydride or other suitable substance .

The multilayer film 1 comprises deformation sealing means configured to limit or prevent an elastic return of the flexible wall 4 to a condition prior to the collapse of the casing compartment 6, once the external force F.

According to the invention, the tubular envelope 10 is characterized by the fact that the metal barrier layer 14 realizes (preferably: on its own) the deformation sealing means.

In other words, innovatively, the metal barrier layer 14 does not perform the mere traditional function of separating the product contained in the enclosure compartment from gas and / or humidity of the external environment but, in addition, is configured to limit or prevent such compartment can freely re-expand after the external force F.

More precisely, the metal barrier layer 14 constitutes a manually moldable core, specifically designed to maintain - within certain limits (depending, in addition to other factors, on the properties of the other layers of the film) - the shape that the user gives to the flexible wall during forced release of the product from the casing.

It follows that, since the envelope compartment cannot expand again in the condition preceding the collapse (crushing, twisting and / or bending) of the wall delimiting the compartment 6, a reduced quantity of atmospheric air can be sucked in through the opening 8 of the package. supply 2, and therefore a smaller quantity of atmospheric oxygen can enter the compartment to deteriorate the product contained in the casing 10.

According to an embodiment, the multilayer film 1 comprises at least a first intermediate layer 18 interposed between the polymeric outer layer 12 and the metal barrier layer 14.

According to a further embodiment, the multilayer film 1 comprises at least a second intermediate layer 20, interposed between the metal barrier layer 14 and the internal polymeric layer 16.

As already indicated in one of the previous variants, the second intermediate layer 20 could also be absent by virtue of the direct contact between the polymeric inner layer 16 and the metal barrier layer 14.

According to an advantageous aspect, the first intermediate layer 18 and / or the second intermediate layer 20 independently comprise at least one binding substance having a thickness in the range 2-100 µm.

According to different embodiments, the first intermediate layer 18 and / or the second intermediate layer 20 could have a thickness of about 2-9 µm, 10-35 µm or 10-60 µm, selected independently (i.e. , for example, the first intermediate layer in the range 2-9 µm, and the second intermediate layer in the range 10-60 µm, or vice versa).

According to further embodiments, the first intermediate layer 18 and / or the second intermediate layer 20 could comprise or consist of maleic acid anhydride, ethylene methacrylate, ethylene-acrylic acid copolymers, ionomers, ethylene vinyl acetate, terpolymers (e.g. ethylene acrylic acid) ester of acrylic acid-anhydyride), ethylene vinyl acetate, polyolefins, in particular polyethylene, polypropylene, modified olefins, or their mixtures.

Purely by way of example, the first intermediate layer 18 and / or the second intermediate layer 20 could comprise - in a mutually independent way - a solidified / cross-linked extruded polymer (for example extruded polyethylene) and / or an adhesive layer, for example a layer two-component polyurethane or a solvent-free adhesive layer.

According to a possible variant, the multilayer film 1 could comprise a plurality of first intermediate layers 18 which - for example in the direction from the external polymeric layer 12 towards the internal polymeric layer 16 - comprise a solidified / cross-linked extruded polymer, a film polymer and an adhesive layer.

For example, the first intermediate layers 18 could comprise extruded polyethylene, polyethylene film and an adhesive layer. According to an embodiment, these layers could respectively have thicknesses within the following ranges: 5-35 µm, 10-70 µm, 1-10 µm, where the sum of these thicknesses is preferably in any case included in the range 20- 100 µm. According to a first variant, the multilayer film 1 or the flexible wall 4 defines an external surface 42, and a ratio R1 between the distance of the metal barrier layer 14 from this external surface 42 and the thickness of the metal barrier layer 14 is included in 'range 0.3-3.8.

According to a second variant, the multilayer film 1 or the flexible wall 4 defines an internal surface 24, and a ratio R2 between the distance of the metal barrier layer 14 from this internal surface 24 and the thickness of the metal barrier layer 14 is in the range 1-5.6.

Both the ratio M and the ratios R1, R2 are explained in figures 7-39 for each embodiment.

From these ratios it is clear that the metal barrier layer 14 determines to a certain extent the tenacity with which the multilayer film retains the deformation imparted by the external force F, but that also the distance between the layer 14 and one or both internal surfaces and / or external can play a role in predetermining or influencing the shape retention and springback of the flexible wall 4.

For the embodiments which provide a polymeric outer layer 12 consisting of polyethylene or polypropylene, the maximum thickness of this layer is preferably included in the range 10-40 µm.

According to a variant, the external polymeric layer 12 is characterized by a thickness, a density and a composition suitable for giving this layer 12 an at least partial transparency.

According to a further variant, the external polymeric layer 12 and the optional first intermediate layer 18 are at least partially permeable to light, so that a metal surface 26 of the metal barrier layer 14 can partially reflect the permeated light.

According to preferred embodiments:

- the envelope 10 comprises a metallized layer 28, placed between the external polymeric layer 12 and the metal barrier layer 14, or externally to the external polymeric layer 12 (in particular: placed below or superimposed on said layer 12) and which it develops in a tubular way around the latter; and / or - the inner polymeric layer 16 is made from a co-extruded film with at least five (or at least seven layers), at least one of which consists of or comprises ethylene vinyl alcohol.

According to these variants, at least one of the metallized layer and / or internal polymeric layer 16 forms a safety barrier against gas and / or humidity, in the event of fracture of the metal barrier layer 14.

In fact, during the collapse of the compartment or due to production or transport problems, the metal barrier layer 14 could be damaged, so as to no longer guarantee the barrier continuity.

However, according to these embodiments, the metallized layer 28, the internal polymeric layer 16 or both allow to preserve the integrity of the barrier in any circumstance, especially since they are by their nature flexible layers and difficult to puncture in ordinary operations of collapse of the enclosure compartment.

For the variants which envisage a metallized layer arranged above the polymeric outer layer (i.e. facing the surface of the layer 12 opposite the metal barrier layer), this metallized layer could comprise an outer protective layer (variant not shown), of preference at least partially transparent to light, which covers it predominantly or completely.

For the variants that provide a metallized layer arranged below the external polymeric layer 12, it is preferable that the latter be at least partially transparent to light, so as to constitute itself the outer protective layer of the metallized surface.

Optionally, a surface 42 of the polymeric outer layer 12 facing away from the envelope compartment 6 could comprise graphic elements 40, for example printed.

The aforesaid object is also achieved by means of a multilayer film 1 for making a flexible wall of a tubular envelope with the following characteristics.

Since a variant embodiment provides that this film 1 is used to make the flexible wall and the tubular envelope described above, even where this is not expressly indicated, this film could include any characteristic that can be deduced - even if only implicitly - from the description that comes before.

The multilayer film 1 comprises an outer polymeric layer 12, a metal barrier layer 14 to gas and / or humidity and an inner polymeric layer 16, these layers 12, 14, 16 being joined together through the thickness A of the film 1 and being closable in a tubular way around a prevalent development axis X.

This multilayer film 1 is deformable by an external force F (and is in particular suitable for being pressed, folded or twisted) and comprises deformation sealing means configured to limit or prevent an elastic return of the film 1 to a condition preceding the deformation, once the external force has ceased F.

In this film, the metal barrier layer 14 provides the deformation sealing means in an innovative way.

According to particularly advantageous embodiments:

- the ratio R1 between the distance of the metal barrier layer 14 from an external surface 42 delimited by the film 1 and the thickness of the metal barrier layer 14 is in the range 0.3-3.8; And

- the ratio R2 between the distance of the metal barrier layer 14 from an internal surface 24 delimited by the film 1 and the thickness of the metal barrier layer 14 is in the range 1-5.6.

The present invention is illustrated on the basis of some non-limiting examples, shown in figures 7-39 attached hereto.

In these figures, for each variant of multilayer film, the columns from left to right illustrate which layer it is with reference to the numbering used in the previous description and in the tables, the material of which this layer is made, and the thickness of the layer expressed in micrometers (µm).

Furthermore, for each example the overall thickness A of the film and the numerical value of the ratios M, R1 and R2 described above are indicated.

In the examples shown in Figures 7-39, the abbreviations used have the following meaning: PET = polyethylene terephthalate; PE = polyethylene; PE / OH / PE = co-extruded film with at least five layers comprising polyethylene (PE), ethylene vinyl alcohol (OH), polyethylene (PE) interspersed with two layers of binder, for example maleic anhydride; the suffix “/ M” = metallized layer placed internally, or externally, to the material preceding this indication; “PE-MS” = multilayer comprising a layer of extruded polyethylene, a layer of polyethylene film and an adhesive layer.

Regarding the variants with a PE-MS layer, it should be noted that the thicknesses of each layer have been adjusted in the following ranges: 5-35 µm for extruded PE, 10-70 µm for PE film, 1-10 µm per layer adhesive.

Although in these figures the external polymeric layer is indicated as PET or PE (optionally comprising a metallized layer), in further variants this layer could consist of any one of optionally metallized polyphthalaldehyde, optionally metallized oriented polypropylene, or optionally metallized polyethylene, as specified above.

Innovatively, the wrapping and the multilayer film object of the present invention allow to brilliantly solve the drawbacks related to the known art.

More precisely, the envelope and the film object of the present invention allow to combine barrier characteristics comparable to those of aluminum tubes, a lightness more similar to known polymeric tubes and a little marked bounce back phenomenon in order to meet the requirements of those who find it necessary to fill these wrappers with products having lower concentrations of antioxidants and / or preservatives.

Advantageously, the envelope object of the present invention has a maximum ovality of 6%, so it lends itself well to the mass production of dispensing packages.

Advantageously, the casing and the multilayer film object of this invention have been specially designed to be processable in a traditional tube packaging line, without undergoing unwanted deformations of the flexible wall during the production phases.

Advantageously, the envelope object of the present invention is made for the most part in a polymeric material, which can be collected, transported and used on a reel.

Advantageously, the envelope object of the present invention can be used to contain different types of product, regardless of the chemical nature and / or possible aggressiveness of the latter.

Advantageously, the casing and the multilayer film object of this invention lend themselves and be manufactured with the metallized surface finish of the aluminum tubes.

Advantageously, the wrapper and the multilayer film object of the present invention provide excellent printing qualities.

Advantageously, the characteristics and / or positioning of the metal layer are the result of a careful balance between the creation of a barrier towards the outside, the calibrated elastic return of the polymer layers, and suitable processability in manufacturing and packaging.

In fact, while inserting an aluminum thickness of the current laminate tubes, and increasing this thickness to obtain a desired barrier, severe production and sealing problems would be generated.

Moreover, a traditional laminate modified in this way could have a marked bend seal in a similar way to aluminum tubes, so as to highlight irremediable bends and geometric defects already in the tube formation phase on the forming machines. By way of example only, should the tubular be oval beyond a certain value, this would make a subsequent extrusion of the dispensing neck impossible.

In addition to this, in this hypothesis, the resulting aesthetic effect would in any case not be satisfactory, as the typical structures of laminate tubes provide for an external polymeric component of medium-high thickness that would irretrievably dampen the brilliant effect of the aluminum placed inside the structure. .

Advantageously, the characteristics of the multilayer film object of the present invention allow to obtain a marked external brightness of the casing wall.

Advantageously, the casing wall object of the present invention has a double or triple gas and / or humidity barrier, which makes it unique with respect to any type of pipe currently on the market.

Advantageously, the integrity of the barrier in the envelope object of the present invention is guaranteed even in dynamic conditions of use. Advantageously, the casing wall object of the present invention could be metallized towards the inside or towards the outside.

In this regard, in the event that the underlying barrier layer was visible, even if part of the metallization was damaged (for example scratched) during the manufacturing or transport of the casing, such damage would not be clearly visible, or would be at least dampened. , by virtue of the metal surface of the underlying barrier layer.

Advantageously, the use of adhesive substances of moderate thickness to join the layers of the present multilayer film makes it possible to bring the visible surface closer to the metal layer, and in this way reduce the opacification of the visible surface of the envelope or of the multilayer film. The wrapping and the film object of the present invention allow to guarantee a reliable watertight closure of the environment in which the product is contained.

Advantageously, the casing and the film object of the present invention have been designed to ensure resistance to high external pressures. Advantageously, the wrapping and the film object of the present invention allow to achieve considerable manufacturing economies, by virtue of the fact that specific processes do not require additional or additional machinery than those normally provided for in this sector.

Advantageously, the wrapping and the film object of the present invention allow to resist the return of shape even in extreme conditions and to date absolutely subject, in particular to twisting of the flexible wall, carried out in such a way as to deform the wrapping in a helical way around the main development axis.

To the embodiments of the aforementioned tubular envelope and multilayer film, a person skilled in the art, in order to meet specific needs, could make variations or replacements of elements with other functionally equivalent ones.

These variants are also contained within the scope of protection as defined by the following claims.

Furthermore, each variant described as belonging to a possible embodiment can be made independently of the other variants described.

Claims (17)

CLAIMS 1. Tubular envelope (10) comprising a dispensing neck (2) and a flexible wall (4), sealedly connected to said neck (2), extending along a prevalent development axis (X) and delimiting an envelope compartment (6) for containing a product, said wall (4) being made up of a multilayer film (1) and being deformable by an external force (F) to collapse said compartment (6) and force the product through an opening ( 8) of the delivery package (2); wherein the multilayer film (1) comprises an outer polymeric layer (12), a metal barrier layer (14) to gas and / or humidity and an inner polymeric layer (16), said layers (12, 14, 16) being joined together through the thickness (A) of said film (1) and closed in a tubular way around said axis (X); the multilayer film (1) comprising deformation sealing means configured to limit or prevent an elastic return of said wall (4) to a condition prior to the collapse of said compartment (6), once the external force (F) has ceased; said casing (1) being characterized in that the metal barrier layer (14) provides said deformation sealing means. 2. Casing according to the previous claim, in which the metal barrier layer (14) constitutes a manually moldable core of the multilayer film (1). 3. Casing according to any of the preceding claims, in which the ratio (M) between the thickness of the metal barrier layer (14) and the thickness (A) of the multilayer film (1) is in the range 10-33%. Casing according to any one of the preceding claims, wherein the inner polymeric layer (16) is directly attached to the metal barrier layer (14), the inner polymeric layer (16) comprising or consisting of a solidified / cross-linked extruded polymer on a surface of the metal barrier layer (14) opposite the polymeric outer layer (12). Casing according to any one of claims 1-3, wherein the multilayer film (1) comprises at least a first intermediate layer (18) interposed between the polymeric outer layer (12) and the metal barrier layer (14), and / or at least a second intermediate layer (20), interposed between the metal barrier layer (14) and the inner polymeric layer (16), the first intermediate layer (18) and / or the second intermediate layer (20) independently comprising at least one binding substance having a thickness in the range 2-100 µm, for example about 2-9 µm, 10-35 µm or 10-60 µm. A shell according to the preceding claim, wherein the first intermediate layer (18) and / or the second intermediate layer (20) comprise a solidified / cross-linked extruded polymer or an adhesive layer, for example a two-component polyurethane layer or an adhesive-free layer of solvents. A shell according to claim 5 or 6, comprising a plurality of first intermediate layers (18) which, for example in the direction from the polymeric outer layer (12) towards the polymeric inner layer (16), comprise a solidified / cross-linked extruded polymer, a polymer in film and an adhesive layer. Enclosure according to any one of the preceding claims, in which the multilayer film (1) or the flexible wall (4) defines an external surface (42), and in which the ratio (R1) between the distance of the metal barrier layer ( 14) from this external surface (42) and the thickness of the metal barrier layer (14) is in the range 0.3-3.8. Casing according to any one of the preceding claims, in which the multilayer film (1) or the flexible wall (4) defines an internal surface (24), and in which the ratio (R2) between the distance of the metal barrier layer ( 14) from this internal surface (24) and the thickness of the metal barrier layer (14) is in the range 1-5,6. 10. Casing according to claim 8, in which the external polymeric layer (12) consists of polyethylene or polypropylene, and in which the maximum thickness of this layer is in the range 10-40 µm. Enclosure according to any one of the preceding claims optionally when dependent on claim 5, wherein the polymeric outer layer (12) and the optional first intermediate layer (18) are at least partially permeable to light, so that a metal surface (26 ) of the metal barrier layer (14) can partially reflect said permeated light. 12. Casing according to any one of the preceding claims: - comprising a metallized layer (28), placed between the external polymeric layer (12) and the metal barrier layer (14), or externally to the external polymeric layer, and which develops in a tubular manner around the latter; and / or - wherein the inner polymeric layer (16) is made from a co-extruded film with at least five or at least seven layers at least one of which consists of or comprises ethylene vinyl alcohol; and in which at least one of the metallized layer and / or internal polymeric layer (16) forms a safety barrier against gas and / or humidity, in case of fracture of the metallic barrier layer (14). 13. Casing according to any one of the preceding claims, wherein: - the multilayer film (1) has a thickness (A) in the range 100-300 µm, optionally in the range 120-220 µm, preferably in the range 140-190 µm; - the external polymeric layer (12) has a thickness in the range 4-40 µm; - the metal barrier layer (14) has a thickness in the range 20-45 µm; - the polymeric outer layer (12) consists of or comprises polyethylene terephthalate or polyethylene, or consists of or comprises polyphthalaldehyde or oriented polypropylene; - the inner polymeric layer (16) consists of or comprises polypropylene; - the internal polymeric layer (16) creates a sealable layer in a joint line (30) between opposite edges of the multilayer film (1) and / or between the flexible wall (4) and the dispensing neck (2) of said casing (1); - the internal polymeric layer (16) is made from a co-extruded film with at least five or at least seven layers comprising polyethylene, ethylene vinyl alcohol and polyethylene, or polypropylene, ethylene vinyl alcohol, polypropylene, optionally bound by maleic anhydride; and / or - the metal barrier layer (14) consists of or comprises aluminum. 14. Casing according to any one of the preceding claims, comprising a junction line (30) which extends along said axis (X) and in correspondence with which opposite edges of the multilayer film (1) converge to make a sealing of the compartment casing (6), the thicknesses (A) of said edges being welded to each other with an overlap of material of the multilayer film (1) substantially zero, between the opposite edges and received in the casing compartment (6) developing a reinforcement band (32) of the seam (30). Enclosure according to any one of the preceding claims, wherein the dispensing neck (2) is coupled internally or externally to one end (34) of the flexible wall (4), an opposite end (36) of said wall (4 ) being optionally sealed by a transverse weld (38) between flattened opposing portions of the flexible wall (4). 16. Multilayer film (1) for making a flexible wall (4) of a tubular envelope, for example a tubular envelope (10) according to any one of the preceding claims; said multilayer film (1) comprising an outer polymeric layer (12), a metal barrier layer (14) to gas and / or humidity and an inner polymeric layer (16), said layers (12, 14, 16) being joined between them through the thickness (A) of said film (1) and being closable in a tubular way around a prevalent development axis (X); the multilayer film (1) being deformable by an external force (F) and comprising deformation sealing means configured to limit or prevent an elastic return of said film (1) to a condition preceding said deformation, once the external force ceases ( F); in which the metal barrier layer (14) forms the deformation sealing means. 17. Multilayer film according to the preceding claim, wherein: - the ratio (R1) between the distance of the metal barrier layer (14) from an external surface (42) delimited by said film (1) and the thickness of the metal barrier layer (14) is in the range 0.3 -3.8; and / or - the ratio (R2) between the distance of the metal barrier layer (14) from an internal surface (24) delimited by said film (1) and the thickness of the metal barrier layer (14) is in the range 1-5 , 6.