EP3055219B1

EP3055219B1 - Stopper for closing containers

Info

Publication number: EP3055219B1
Application number: EP14789415.8A
Authority: EP
Inventors: Mattia BOSCHELLO; Roberto Casini
Original assignee: Microcell SRL
Current assignee: Microcell SRL
Priority date: 2013-10-08
Filing date: 2014-10-08
Publication date: 2017-10-04
Anticipated expiration: 2034-10-08
Also published as: WO2015052659A1; US20160297572A1; ES2654194T3; EP3055219A1; ITPD20130277A1

Description

The present invention relates to a stopper for closing containers, such as bottles, in particular for fluid food substances.
The present invention relates in particular to a stopper designed to close bottles for wine, food oils, vinegar, spirits, etc.
Natural cork stoppers with a cylindrically shaped body to be inserted in the neck of the bottle or container to be closed are well known in the specific prior art.
In the technical sector of bottling of beverages, and in particular wine, it is known that there is a need to replace traditional cork stoppers with synthetic stoppers made from polymer material or other types of closure.
This need is shaped by specific economic factors and by the significant technical drawbacks connected with traditional stoppers, including the possibility that cork stoppers may release substances able to alter the taste of the wine as well as the fact that mechanical properties may vary from stopper to stopper.
In order to meet this need in a positive way, stoppers made from normally expanded polymer material or from so-called composite cork, i.e. comprising a plurality of natural cork granules aggregated together by resins, normally polyurethane resins, have been developed.
These latter stoppers differ in terms of the granulometry of the cork granules and may possibly be provided with natural cork discs secured to both transverse bases of the stopper.
Although the performance of these stoppers is more uniform and they reduce the extent of organoleptic alterations of the wine in comparison with natural cork stoppers, they do not, however, ensure complete neutrality or a high barrier to the absorption of the aromatic fraction of the wine.
T-shaped stoppers are also known, and have a cylindrical body made from one of the materials discussed above and a head made from various different materials, for instance plastics, metal, glass, wood, etc., and are used for the closure of spirits, food oils, vinegar, etc.
The stoppers must make it possible to preserve the integrity of the product contained in the container closed by the stopper, preventing it from deteriorating over time in particular as a result of an undesired interaction between the product and the atmosphere outside the container and/or between the product and the stopper itself.
In order to obtain stoppers suitable for the above purpose, the bases of the natural cork stopper have been covered with a barrier designed to reduce the interaction between the stopper and the product.
Examples of such stoppers are known for instance from WO 03/004367 which discloses a stopper with a body made from cork or synthetic material and provided with a protective film designed to control the passage of gas and reduce the transfer of molecules which may alter the beverage, including halo-anisolic compounds, through the stopper.
The protective film comprises a first 'barrier' layer made from polymer material having a low permeability to H₂O, O₂, CO₂ and impermeable to organic molecules. The protective film further comprises a second adhesion layer so that the film may be applied to the body of the stopper, preferably at one end thereof.
The body of the stopper disclosed in WO03/004367 is tapered at the end to which the protective film is applied so as to limit the deformation of the film when the stopper is being inserted into the neck of the bottle.
The stopper disclosed in WO03/004367 does not, however, definitively resolve the problems of organoleptic neutrality as, since the membrane does not fully cover the base of the stopper, and/or may become at least partially detached from it, there may always be a risk of contamination.
A further drawback of the stopper disclosed in WO03/004367 is that the protective film is glued by a layer of adhesive to the base of the stopper and may become detached from the body of the stopper and fall into the bottle in which the stopper is inserted.
The protective film disclosed in WO03/004367 is not, moreover, stable over time but tends to change colour which users may find off-putting. Another container stopper including a protective barrier is disclosed in WO2004/060764 A1 . The problem underlying the present invention is one of providing a stopper functionally and structurally designed to remedy the drawbacks discussed with respect to the cited prior art.
A particular object of the invention is to provide a stopper provided with a barrier layer made from a material which makes it possible drastically to reduce or block the passage of gas through the stopper.
A further object of the invention is to provide a stopper in which the barrier layer is stably attached to the body of the stopper.
This problem is resolved by the invention by means of a stopper with a barrier layer embodied in accordance with the accompanying claims.
The characteristic features and advantages of the invention will become clear from the following detailed description of preferred embodiments shown, by way of non-limiting example, in the accompanying drawings, in which:

Fig. 1 is a front view of a stopper provided with a barrier element; this stopper is not according to the invention;
Figs. 2-7 are views similar to Fig. 1 but relating to various embodiments of the barrier element, wherein only the embodiments of Figs. 4, 5 are according to the invention;
Fig. 8 is a diagrammatic front view of a T-shaped stopper with a barrier element according to an embodiment which is not part of the invention. Figs. 1-7 show a stopper 100 for containers.

The stopper 100 is preferably designed to close containers by being inserted in the opening provided in the neck of the container, which is not shown in the Figures.
The stopper 100 comprises a compressible body 1 of a generally cylindrical shape with rounded corners extending along a longitudinal axis X between two longitudinally opposite base surfaces 2, 3.
The compressible body 1 has dimensions such that it may be housed and engaged in an opening of a container, which is not shown in the Figures.
The compressible body 1 is made from composite cork or from any other expanded polymer material having mechanical and leak-tightness properties suited for the purpose, for instance polyolefin materials with or without metallocene catalysts, styrene block polymers, EVA, TPV, TPU, TPE.
The material, or mixture of materials, of the compressible body 1 is selected so as to obtain a stopper 100 which can be radially compressed in order to be inserted in the opening of the container and then expands to lock the stopper in the neck of the bottle or container to be closed by the stopper 100.
The material of the compressible body 1 is also selected so as to have a limited weight, low relaxation and good resilient recall and structural fatigue strength.
In some preferred versions, the compressible body 1 is made from one or a plurality of the following materials: polyethylene, polyolefin materials with metallocene catalysts, or styrene polymers, for instance SEBS, SEPS and/or their polymer blends.
The stopper 100 is provided with a barrier element 4 made from a material having a high impermeability to gases in order drastically to limit the passage of gas through the stopper 10 and, at the same time, to reduce the absorption of the aromatic fraction of the wine or beverage with which the stopper 100 comes into contact.
The barrier element 4 is attached to the body 1 of the stopper 100 at a transverse surface portion 5 of the stopper 100 disposed transversely with respect to the longitudinal axis X so as to intercept the flow of gas through the stopper 100 in both directions of the arrow F, i.e. into or out from the container closed by the stopper 100.
The transverse surface portion 5 corresponds, in the versions shown, to a transverse section 5' of the body 1 defined by a cutting plane Y perpendicular to the longitudinal axis X of the body 1 at a desired position along the longitudinal axis X.
In other versions which are not shown, however, the transverse surface portion 5 may be a transverse section of the stopper 100 defined by a cutting plane inclined with respect to the longitudinal axis X.
In other versions, for instance those shown in Figs. 1-5, the barrier element 4 of the stopper 100 is attached to one of the base surfaces 2, 3 of the body 1. In this case, the transverse surface 5 corresponds to the one of the base surfaces 2, 3 of the body 1.
In the versions shown, the barrier element 4 is provided on the base surface 3 designed to face, in use, the interior of the container closed by the stopper 100 in order to provide a better barrier to the aromatic substances present in the beverage contained therein.
In the version of Fig. 2, the barrier element 4 comprises a barrier layer 41 made from a high-barrier plastics material. Use is preferably made of TPV, TPU or polyisobutylene, or a material comprising a polyisobutylene at a percentage of between 10% and 80%.
In the more preferred version, use is made of SIBS, poly(styrene-block-isobutylene-block-styrene), which is a material having a very high barrier to gases and having a high thermal stability and excellent resilience, or an SIBS-based polymer material.
SIBS is a an elastomer material which forms a high barrier drastically reducing the flow of gas from the atmosphere to the container and the flow of aromatic substances of the beverage from the container to the atmosphere, while at the same time retaining a high resilient capacity so that the plastics barrier layer 41 matches the deformations to which the body 1 of the stopper 100 is subject during the closing operation.
SIBS also has a good chemical affinity with the polymer materials from which the body 1 of the stopper 100 is made, as a result of which the barrier element 4 adheres in a stable manner to the body 1 of the stopper 100, creating chemical links with the material of the body 1.
In this case, the stopper 100 is made by co-moulding the body 1 and the barrier element 4 or by over-moulding the barrier element 4 on the body 1. In the version of Fig. 3, the barrier element 4 comprises a barrier layer 42 made from aluminium, or its alloys, or from another ductile metal, for instance tin or copper or, as an alternative, from plastic films of polyvinylidene chloride (PVDC), a very effective barrier polymer, and/or ethylene vinyl alcohol (EVOH).
The metals listed above are materials with a high impermeability to gases, in particular oxygen, and to the aromatic substances contained in beverages in general and thus make it possible to provide an excellent barrier to the passage of these substances through the stopper 100. Aluminium, tin and copper, as they are highly ductile, moreover, may be formed as very thin layers.
PVDC and EVOH also make it possible to produce multi-layer films providing an excellent barrier to the passage of gas through the stopper 100.
In a preferred version, the barrier layer 42 is made from aluminium.
The barrier element 4 further comprises an adhesion layer 421 designed to be interposed, in use, between the compressible body 1 and the barrier layer 42 and to promote the adhesion of the barrier layer 42 to the body 1.
The adhesion layer 421 is made from a polyolefin material such as PE or PP, EVA or even PET. The adhesion layer 421 is made from a material having a good affinity with both the material of the barrier layer 42 and with the material of the body 1 so as to ensure good adhesion with both these materials and avoid any undesirable detachment of the barrier element 4 from the body 1 or the separation of the barrier layer 4 and the adhesion layer 421.
The barrier element 4 further comprises a further adhesion layer 422 designed to be applied externally to the barrier layer 42 so that the latter is interposed between the adhesion layer 421 and the further adhesion layer 422.
The further adhesion layer 422 is made from a polyolefin material, preferably high-barrier, usually PE or PP, EVA or even PET. The further adhesion layer 422 is made from a material having a good affinity with the material of the barrier layer 42 in order to ensure that it adheres properly to the latter.
The material of the adhesion layer 421 and/or the further adhesion layer 422 is selected in line with the material used for the barrier layer 42.
The adhesion layer 421 is preferably made from PE, while the further adhesion layer 422 is made from PET or PE.
The further adhesion layer 422 is shaped so that it covers almost completely the barrier layer 42. In this way, with the stopper inserted in the bottle, the further adhesion layer 422 is interposed between the barrier layer 42 and the content of the bottle, preventing direct contact between the barrier layer 42 and the content of the bottle.
In this way the barrier layer 42 is isolated from the beverage which is an important factor especially in cases in which the barrier layer 42 is made from metal, and the barrier element 4 is provided with greater structural resistance, preventing it from becoming detached from the body 1.
The further adhesion layer 422 also makes it possible to improve the structural compactness of the barrier element 4 in the various conditions of use, making it possible to prevent the barrier element 4 from being deformed following radial compression for the insertion of the stopper 100 in the container.
In other versions (not shown), the barrier element 4 further comprises a further layer interposed between the barrier layer 42 and the adhesion layer 421 or the further adhesion layer 422 made from PET, or another appropriate material having a good chemical affinity with the materials used for the adjacent layers. The further layer is made from a material which may be stamped and may be provided with a stamp in order to personalize the stopper, for instance stamped PET.
The further layer may also further increase the barrier effect and the stability of the barrier elements 4.
The stopper 100 described with reference to Fig. 3 may be made, for instance, by firstly forming the barrier element 4 and then attaching it to the body 1 in order to cause the adhesion layer 421 to adhere to the body 1 of the stopper 100.
If the barrier layer 42 is made from aluminium, a plasma deposition of aluminium powder may possibly be made on the adhesion layer or on the further adhesion layer, and the metal barrier layer then covered with the further adhesion layer or vice versa with the adhesion layer and the barrier element obtained lastly attached to the body 1. The plasma deposition of aluminium powder is preferably carried out under vacuum.
In a further embodiment, shown for instance in Figs. 4 and 5, the stopper 100 comprises a barrier device 40 in turn comprising a barrier element 4 formed, for instance, as one of the versions described with reference to the preceding drawings and preferably as one of the versions described with reference to Fig. 3, possibly provided with the further layer of PET, to which an additional barrier layer 43 shaped so as to encapsulate the previously formed barrier element 4 is applied.
The barrier device 40 may in particular comprise a barrier layer 42 made from aluminium, or its alloys, or from another ductile metal, for instance tin or copper or, as an alternative, from plastic films of polyvinylidene chloride (PVDC), a very effective barrier polymer, and/or ethylene vinyl alcohol (EVOH); an adhesion layer 421 made from a polyolefin material such as PE or PP, EVA or even PET; a further adhesion layer 422 made from a polyolefin material, preferably high-barrier, normally PE or PP, EVA or even PET and a further barrier layer 43 formed as described below. The barrier device 40 may possibly comprise a further layer interposed between the barrier layer 42 and the adhesion layer 421 or the further adhesion layer 422 made from PET, or another material having good chemical affinity with the materials used for the adjacent layers.
In this case as well, the barrier element 4 may first be formed and then attached to the body 1 of the stopper 100 and then the further barrier layer 43 may be over-moulded on the barrier element 4.
The further barrier layer 43 is made from a material having a good affinity with the material of the body 1 of the stopper so as to obtain good adhesion between the further barrier layer 43 and the body 1 of the stopper.
The further barrier layer 43 is made from a material having a good affinity with the material of the further adhesion layer 422.
In a version, the further barrier layer 43 is made from isobutylene-based elastomers, preferably SIBS, or also from TPU and/or TPV, SEBS, or their polymer blends.
In one version, the further barrier layer 43 may be slightly expanded and/or mixed with PE in order farther to improve the adhesion of the further barrier layer 43 to the body 1 of the stopper 100. If the further barrier layer 43 is made from SIBS, 1.5-2% by weight of NaHCO₃ may be added.
In another version, the further barrier layer 43 is made from the same material as the body 1 of the stopper 100 in order further to improve the adhesion of the further barrier layer 43 to the body 1 of the stopper 100. The further barrier layer 43 is injection moulded on the previously formed barrier element 4 so that the barrier element 4 is interposed and completely enclosed between the further barrier layer 43 and the body 1 of the stopper 100.
In this way, it is possible to improve the structural cohesion of the stopper 100 in the various conditions of use, and in particular to prevent damage to and deformations of the barrier device 40 following the radial compression of the stopper 100.
This version also makes it possible to optimise the stability of the barrier device 40 on the body 1 of the stopper 100.
It is possible, in particular, to improve the adhesion of the barrier element 4 to the body 1, preventing undesirable detachments and/or radial deformations thereof when the stopper 100 is being used.
The presence of the further barrier layer 43, moreover, makes it possible further to increase the barrier effect which may be obtained, i.e. further to increase the impermeability to gases and aromatic substances that may be obtained with the stopper 100.
With this version of the stopper 100 it is also possible to increase the integrity of the product contained in the stoppered container.
In order to improve the adhesion of the further barrier layer 43 to the body 1, the barrier element 4, in this version, is shaped such that it occupies a transverse surface portion 5" having a smaller extension than the extension of the normal transverse section 5', considered with reference to the longitudinal axis X of the body 1, so that an attachment area 6 for the further barrier layer 43 is defined on the base surface 3.
The barrier element 4 is in particular shaped such that an attachment area 6, shaped as a circular crown 6 to which the further barrier layer 43 is attached, is defined on the base surface 3 of the body 1.
In a preferred version, the circular crown 6 has a width of between 0.5 and 2% of the diameter of the body of the stopper, preferably approximately 1%.
In order further to increase the attachment of the further barrier layer 43 to the body 1 of the stopper 100, in the version of Fig. 5, the body 1 is tapered along the longitudinal axis X at the longitudinal end portion 3a. The latter therefore has a profile of generally frustoconical shape tapered along the longitudinal axis X, the base surface 3 forming the smaller base of the frustum having a smaller extension than the normal transverse section 5' of the body 1.
The smaller base of the frustum occupies a transverse surface portion 5" having a smaller extension than the extension of the normal transverse section 5'.
The barrier element 4, produced for instance in one of the ways discussed with reference to Fig. 3, is applied to the smaller base of the frustum 5". The further barrier layer 43 is applied to the body 1 so as to completely enclose, the barrier element 4. The further barrier layer 43 is attached to the lateral surface 3b of the frustum so as to surround the longitudinal end portion 3a and to be attached to the lateral surface 3b itself.
The lateral surface 3b of the frustum forms the attachment area 6 for the further barrier layer 43. The tapering takes place such that the lateral surface 3b is inclined with respect to the longitudinal axis by an angle α of between 25° and 75°.
This configuration makes it possible further to improve the attachment of the further barrier layer 43 to the body 1 and to obtain a stopper 100 with high mechanical properties.
In this case as well, the barrier element 4 is encapsulated between the body 1 of the stopper and the further barrier layer 43, obtaining a barrier device 40 having improved mechanical strength and improved performance.
In other versions, as shown for instance in Fig. 6, the stopper 100 comprises two separate barrier elements 4 produced in any one of the ways discussed above and attached to the two opposite base surfaces 2, 3 of the compressible body 1 respectively.
Similarly, in versions which are not shown, the stopper of the invention may be provided with two separate barrier devices 40 produced in any one of the ways discussed above and provided at the two opposite base surfaces 2, 3 of the compressible body 1.
This provides a stopper 100 having a symmetrical configuration and means that it is not necessary to control the orientation of the stopper 100 when it is being applied to the neck of a container.
The stopper 100, provided with the two barrier elements 4, or barrier devices 40, may be inserted at either end 2, 3 in the container for which it is intended, thereby facilitating and speeding up the stoppering process.
In some versions, for instance as shown in Fig. 7, the barrier element 4 is provided on a normal transverse section 5' of the body 1 disposed in an intermediate position along the longitudinal axis X between the two opposite base surfaces 2, 3 of the compressible body 1.
In this version, the stopper 1 has two separate body portions 1a, 1b between which the barrier element 4 is interposed.
In another version (not shown), the barrier device 40 is provided on a normal transverse section 5 of the body 1 disposed in an intermediate longitudinal position between the two opposite base surfaces 2, 3 of the compressible body 1, the barrier device 40 having a smaller transverse section than the normal transverse section 5 of the body 1 so that the barrier device 40 is completely embedded in the body of the stopper.
In some versions (not shown), the barrier element 4 is provided with a plurality of holes provided in the barrier layer 42 and intended to enable the flow of gas through the stopper 100 to be regulated.
By varying the dimensions and/or the number and/or the density of the holes, it is possible to regulate the oxygen transfer rate (OTR) between the interior and the exterior of the container to which the stopper of the invention is applied.
It is also possible, by calibrating and dimensioning the holes, to obtain an oxygen exchange that varies in an almost continuous manner, thus providing a level of permeability defined in accordance with the type of wine, or in general the product contained in the bottle closed by the stopper.
In this way, it is possible to obtain a stopper which is suitable for closing bottles containing various types of beverage and in particular various types of wines.
The various wines, if they are to "age" correctly, in practice require different amounts of oxygen from outside. For the majority of white wines, a high oxygen barrier is for instance necessary, whereas red wines, depending on the grape variety and the type of vinification and ageing, may require an appropriate and variable amount of oxygen to achieve their maximum aromatic level.
In other versions (not shown) of the stopper of the invention, the barrier element 4 is attached to a transverse surface portion 5 corresponding to a zone of a transverse section of the body 1 of the stopper 100 having a smaller extension than the transverse section 5 thereof.
This makes it possible to limit the radial deformation of the barrier element 4 during the compression of the stopper 100 for its insertion into the bottle to be closed. The transverse surface portion lacking the barrier element 4 enables, moreover, some gas to pass through the stopper 100.
Fig. 8 shows a stopper 100' comprising a head 7 from which a body 1' substantially of cylindrical shape extends along the longitudinal axis X of the stopper 100'. The body may be made from one of the materials discussed above and the head 7 may be made from the same material as the body 1' or from a different material, usually a material with a different compressibility, preferably lower than the compressibility of the material of the body 1'.
The head 7 has a transverse section S1 of a greater extension than the transverse section 5 of the body 1'.
In the stoppers configured in this way, known as T-shaped stoppers, the barrier element 4' or respectively the barrier device 40' is provided at the base surface 3' of the compressible body 1' opposite the head 7, i.e. the barrier element 4' or respectively the barrier device is applied to the base surface 3' which is designed to face, in use, the interior of the container to which the stopper 100' is applied.
The barrier element 4' may be made in any one of the ways discussed above.
In a version (not shown), the T-shaped stopper 100' may also be provided with the barrier device made in any one of the ways discussed above.
A T-shaped stopper is thus obtained which prevents the passage of gas through the stopper. In this case as well, moreover, the barrier element 4' may be provided with holes designed to enable the flow of gas through the stopper 100' to be regulated.
The invention thus resolves the stated problem, and achieves many advantages, including that of providing a stopper having a barrier state in respect of gases and aromatic substances which is particularly effective in comparison with known stoppers.
The invention advantageously makes it possible in particular to obtain a stopper which is structurally very compact, preventing the contamination of the beverage contained in the container to which the stopper is applied.
According to the invention, a stopper is also obtained whose oxygen transfer rate may be appropriately varied by adapting the stopper to the particular oxygenation requirements specific to the various types of beverages which may be contained in the container closed by the stopper.

Claims

Stopper (100; 100') for closing a container, comprising a main body (1; 1') so shaped as to be removably housed and engaged in an opening of said container, and extending along a longitudinal axis (X) thereof between two opposed base surfaces (2, 3) which face the outside and the inside of the containers, respectively, when said main body (1; 1') is housed and engaged in said opening, said stopper (100; 100') comprising a barrier element (4; 4') made from a material with high impermeability to gases and provided on a transverse surface portion (5") on a base surface (3) of said stopper (100; 100') positioned transversely with respect to said longitudinal axis (X) so as to intercept the flow of gas through said stopper (100; 100'), said barrier element (4; 4') being intended to reduce the passage of gas through said stopper (100), said barrier element (4, 4') comprising a plastic barrier layer (41; 43) made from polyisobutylene-based elastomers, preferably SIBS and/or TPV and/or TPU, characterized in that it further comprises a further barrier layer (43) applied onto said barrier element (4) so that the latter is enclosed between said further barrier layer (43) and said body (1; 1'), said transverse surface portion (5") having a smaller extension than the transverse section (5') of said body (1; 1') so that an attachment area (6) for said further barrier layer (43) is defined on said base surface (3).
Stopper (100; 100') for closing a container, comprising a main body (1; 1') shaped so as to be removably housed and engaged in an opening of said container, and extending along a longitudinal axis (X) thereof between two opposed base surfaces (2, 3) which face the outside and the inside of the containers, respectively, when said main body (1; 1') is housed and engaged in said opening, said stopper (100; 100') comprising a barrier element (4; 4') made from a material with high impermeability to gases and provided on a transverse surface portion (5") on a base surface (3) of said stopper (100; 100') positioned transversely with respect to said longitudinal axis (X) so as to intercept the flow of gas through said stopper (100; 100'), said barrier element (4; 4') being intended to reduce the passage of gas through said stopper (100), said barrier element (4; 4') comprising a barrier layer (42) made from aluminium and/or alloys thereof, or tin and/or alloys thereof, or EVOH, or PVDC, characterized in that it further comprises a further barrier layer (43) applied onto said barrier element (4) so that the latter is enclosed between said further barrier layer (43) and said body (1; 1'), said transverse surface portion (5") having a smaller extension than the transverse section (5') of said body (1; 1') so that an attachment area (6) for said further barrier layer (43) is defined on said base surface (3).
Stopper according to claim 2, wherein said barrier element (4; 4') additionally comprises an adhesion layer (421) intended to be interposed, in use, between said body (1; 1') and said barrier layer (42), and intended to promote the adhesion of said barrier layer (42) to said body (1; 1').
Stopper according to claim 3, wherein said barrier element (4; 4') additionally comprises a further adhesion layer (422) intended to be applied to said barrier layer (42), so that the latter is interposed between said adhesion layer (421) and said further adhesion layer (422).
Stopper according to claim 3 or 4, wherein said adhesion layer (421) and/or said further adhesion layer (422) is made from a polyolefin material, or from the same material as that of which said body is made.
Stopper according to any one of claims 3 to 5, wherein said adhesion layer (421) and/or said further adhesion layer (422) is made from PE, PP, PET or EVA.
Stopper according to any one of claims 2 to 6, wherein said barrier layer (42) has a plurality of holes for regulating the flow of gas through said body (1; 1').
Stopper according to any one of the preceding claims, wherein said transverse surface portion (5") is provided on at least one of said base surfaces (2, 3) of said body (1; 1').
Stopper according to any one of the preceding claims, and comprising a first and a second barrier element (4, 4') provided on the two opposite base surfaces (2, 3) of said body (1,1').
Stopper according to any one of the preceding claims, wherein said further barrier layer (43) is made from polyisobutylene-based elastomers, preferably from SIBS, or possibly TPU and/or TPV.
Stopper according to any one of the preceding claims, wherein said further barrier layer (43) is made from elastomers similar to the material from which said body (1; 1') is made.
Stopper according to any one of the preceding claims, wherein a longitudinal end (3a) of said body (1; 1') is tapered so as to define said attachment area (6) for said further barrier layer (43) on said body (1, 1').
Stopper according to the preceding claim, wherein said longitudinal end (3a) is tapered so as to define an attachment wall (3b) inclined with respect to said longitudinal axis (X) by an angle (α) of between 25° and 75°.
Stopper according to any one of the preceding claims, wherein said compressible body (1) is of cylindrical shape and is made from polyethylene and/or polyolefin materials with metallocene catalysts, or styrene polymers such as SEBS.
Stopper according to any one of the preceding claims, comprising a head (7) provided at the longitudinal end (2) of said body (1') which is intended to face, in use, towards the outside of said container to be closed with said stopper, said head (7) having a cross section (S1) whose extension is greater than that of the cross section (5) of said body (1').