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(11) | EP 0 974 528 A1 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | Closure element of natural cork |
| (57) A closure element (1; 9; 15) of natural cork for bottles containing drinkable liquids,
is adapted to be inserted with interference into the neck (21) of a bottle (20), the
neck (21) having a determined first axis (22), the closure element (1; 9; 15) having
the shape of a geometric solid with a constant cross-section along a second axis (2;
10; 16) coincident with the first axis (22) when the stopper (1; 9; 15) is inserted
into the neck (21) and a plurality of lenticels (6) characteristic of the natural
cork, which are distributed into the closure element (1; 9; 15), the lenticels being
substantially parallel to each other and extending in a determined direction (R);
the closure element (1; 9; 15) being oriented with respect to the lenticels (6) so
that the second axis (2; 10; 16) is substantially parallel to said lenticels. |
[0001] The present invention relates to a closure element of natural cork for bottles containing drinkable liquids.
[0002] In particular, the present invention relates to a cork stopper for bottles of wine, and the present disclosure will make explicit reference thereto without losing generality,
[0003] In general, wine is preserved in bottles of glass, which is a mineral material with high chemical inertia which can be easily sterilized and has stable mechanic characteristics. For this reason, the glass of the bottles does not interact with the wine and therefore guarantees that the wine is not adulterated by foreign substances during the preservation. For about two hundred years the bottles of wine have been closed by means of either stoppers of natural cork or stoppers made of vegetable material. By virtue of the characteristics deriving from its vegetable origin cork is practically irreplaceable as raw material for producing stoppers for bottles of wine but, on the other hand, is often unreliable because of its own variable chemical and physical characteristics. In other words, in variable measure cork stoppers may confer a taint to the wine, such as for instance the well known cork taint or the like. In addition, they do not guarantee an efficient seal and give rise to a phenomenon known as leakage, and permit excessive exchange of oxygen between outside environment and the wine contained in the bottle. Studies have shown that a tight relationship exhists between leakage and wine taint, the latter deriving not only from specific chemical substances, possibly also polluting substances, contained in the stoppers, but also from a non-homogeneous mechanical behaviour of the stoppers.
[0004] Known stoppers of natural cork are obtained from cork bark of cork oaks from which the bark tissue is removed in the form of planks, from which stoppers are die-cut after a series of treatments. The cork bark has a series of year layers, concentric with respect to the trunk of the oak and lenticels which extend radially with respect to the trunk of the oak. The lenticels, sometimes also called pores, are passages with irregular section which extend in a substantially straight direction and are substantially parallel to each other, when the planks are flattened during the treatment process.
[0005] Normally, for bottling wines there are used stoppers which are substantially monolithic cylinders of natural cork, which are obtained from said planks and have a longitudinal axis which is substantially perpendicular to the lenticels. Said stoppers are intended to be inserted with interference into the necks of respective bottles and apply an elastic force against the internal walls of the respective bottle necks for producing a sealing action. In view of the disposition of the lenticels with respect to the axis of the stopper, the cork of the stoppers mentioned above behaves, from the point of view of the mechanical actions applied on the internal walls of the bottle necks, as a strongly anysotropic material. In fact, the force which the stopper applies inside the bottle neck is substantially due to the elastic reaction of the stopper. In view of the fact that density and resiliency of the cork vary as a function of the position of the area considered and as a function of the direction of the stress/deformation, the stopper does not apply a uniform force on the inner wall of the neck and, consequently, cases of leakage and/or excessive exchange of oxygen can be originated, which determine oxidation of the wine and produce the formation of taint.
[0006] Furthermore, the diameters of the known stoppers are often limited by the thickness of the planks which sometimes is relatively small, and often stoppers with a diameter sufficient for ensuring an efficient seal cannot be manufactured.
[0007] The object of the present invention is therefore to provide a closure element for bottles of wine which achieve maximum reduction of the drawbacks mentioned above.
[0008] In accordance with the present invention there is provided a closure element of natural cork for bottles containing drinkable liquids, adapted to be inserted with interference into the neck of a bottle, the neck having a first axis, the closure element being a geometric solid with a constant cross-section along a second axis which is coincident with said first axis when the closure element is inserted into said neck, said closure element comprising a plurality of lenticels distributed into said closure element, substantially parallel to each other and extending in a determined direction, said lenticels being elements characteristic of natural cork; said closure element being characterized in that it is oriented with respect to the lenticels so that the respective second axis is substantially parallel to said lenticels.
[0009] In accordance with an advantageous embodiment, the closure element according to the invention is defined by a single piece of natural cork.
[0010] In accordance with an alternative embodiment, the closure element according to the invention defined above consists of two or more pieces of natural cork joined to each other transversally to the longitudinal axis.
[0011] The present invention relates also to a method for producing the closure element defined above, said closure element comprising a lateral surface, the method comprising the steps of separating said pieces from a cork plank having a lower face and an upper face substantially parallel to each other, said plurality of lenticels characteristic of natural cork extending between the lower face and the upper face in a direction substantially perpendicular to said upper and lower face, said method being characterized in that it comprises the step of die-cutting or cutting said piece in a direction perpendicular to said lower and upper face for forming said lateral surfaces of said closure element.
[0012] The present invention will now be disclosed with reference to the attached drawings, which show a nonlimiting embodiment thereof, in which:
- Figure 1 is perspective view of a closure element according to the present invention, wherein parts have been removed for the sake of clarity;
- Figure 2 is a perspective view with parts removed for the sake of clarity of a variant of the closure element of figure 1;
- Figure 3 is a perspective view with parts removed for the sake of clarity of a variant of the closure element of figure 1.
- Figure 4 is a perspective view of a bottle adapted to cooperate with a closure element according to the present invention;
- Figure 5 is a perspective view of a plank wherein parts have been removed for the sake of clarity, from which the closure element according to the present invention is formed, and
- Figure 6a, 6b and 6c are cross-sectional views of planks with different thickness from which closure elements according to the present invention are formed.
[0013] The numeral reference 1 in figure 1 indicates a stopper of natural cork, which has substantially a cylindrical shape with a diameter D and a heght H, which has an axis 2, a lateral surface 3 and two end surfaces or bases 4, only one of which is shown in figure 1. The stopper 1 comprises a single piece 5 of natural cork, which has a plurality of lenticels or pores 6, which are passages with irregular section which extend along a substantially straight direction R inside the piece 5 and which are characteristic of the natural cork. The lenticels 6 are substantially parallel to each other, are substantially parallel to the axis 2 and cross the piece 5 from one base 4 to the opposite base 4. The piece 5 has also year layers 7 which are separated from each other by dark coloured rings 8. The heght H of the stopper 1 is substantially equal to or less than the diameter D, which is substantially greater than a diameter D3 of known stoppers 32 (figures 6a, 6b, 6c).
[0014] In accordance with the variant shown in figure 2, a stopper 9 has a cylindrical shape with a diameter D and a heght H, and has a longitudinal axis 10, a lateral surface 11 and two bases 12, only one of which is shown in figure 2. The stopper 9 comprises two pieces of cork 13 and 14 which have a cylindrical shape with a diameter D, the pieces 13, 14 having the same axis 10, being superimposed to each other and being joined to each other by means of glue. The pieces 13 and 14 have an heght equal to H/2, but they could also have a heght different from H/2. The pieces 13 and 14 are crossed by respective plurality of lenticels 6, which extend in the direction R, substantially parallel to the axis 10, and comprise a predetermined number of layers 7, separated from each other by rings 8.
[0015] In accordance with the variant of figure 3, a stopper 15 has the shape of a prism with orthogonal cross-section which has a symmetry axis 16 and comprises a lateral wall 17 and bases 18, only one of which is shown in figure 3. The stopper 15 is defined by a single piece 19 which is crossed by the lenticels 6, which extend in the direction R substantially parallel to the axis 16 and has a certain number of layers 7 delimited by rings 8. The stopper 15 has a heght H and an average diameter substantially equal to the diameter D.
[0016] With reference to figure 4, the numeral reference 20 indicates a bottle, which comprises a neck 21 which extends around an axis 22. The neck 21 has an open end 23 and an internal cavity 24 delimited by a wall 25, which has a substantially cylindrical internal surface 26 with a diameter D2 and an outer surface 27 with a frusto-conical shape and having a ring 28 in correspondence with the open end 23.
[0017] In use, the stoppers 1, 9 and 15 are inserted into respective cavities 24 through the end 23 by means of a known corking machine, not shown. The stoppers 1, 9 and 15 are deformed by compression forces F1 directed radially to the respective axes 2, 10 and 16 which the known and not shown corking machine applies to the stoppers 1, 9 and 15 for imparting to said stoppers 1, 9 and 15 a diameter lower than the internal diameter D2 of the neck 21 so that they can be easily pushed into the cavity 24. The forces F1 are substantially perpendicular to the axes 2, 10 and 16 and to the lenticels 4 of the respective stoppers 1, 9 and 15, which deform temporarily by virtue of the elastic nature of the natural cork. Once the stoppers 1, 9 and 15 have been inserted into the cavity 24, the respective axes 2, 10 and 16 are coincident with the axes 22 of the respective bottles 20 and the elastic reaction of the stoppers 1, 9 and 15 generates forces F2 which are directed radially with respect to the axes 2, 10 and 16, said forces F2 acting on the respective portions of the internal surface 26 which is in contact with the lateral surfaces 3, 11, 17 of the stoppers 1, 9, 15 and determining a sealing action.
[0018] The advantages of the stoppers 1, 9 and 15 consist in that the cork of said stoppers 1, 9 and 15 behaves as a substantially isotropic material with respect to the radial deformations deriving by the compression with respect to the axes 2, 10 and 16 and therefore the forces F2 are substantially constant along planes perpendicular to the respective axes 2, 10 and 16. Furthermore, the static compression applied by the neck 21 of the bottles 20 on the stoppers 1, 9, 15 determines the closure of the lenticels 6 and prevents an excessive exchange of oxygen between the wine and the outer environment.
[0019] The pieces 5, 13, 14 and 19 for producing the stoppers 1, 9 and 15 are obtained by a cork plank 29, a portion of which being shown in figure 5. The plank 29 is detached by the bark tissue of trunks of not shown cork oaks and comprises a lower face 30, commonly called belly, which is the side facing towards the trunk of the not shown cork oak, and an upper face 31, commonly called back, which is the side facing outwardly of the not shown cork oak. The planks 29 generally have an arched shape and are subjected to a treatment for obtaining substantially planar planks 29. The lower face 30 is relatively smooth and uniform, whereas the upper face 31 is strongly rough and irregular; in addition the cork in correspondence with the lower face 30 has a density greater than the density of the cork in correspondence with the upper face 31. The difference between the density of the faces 30 and 31 is due to the fact that the growth of the cork occurs from within to the outside and the layers 7 are progressively pushed outwardly during the growth and reduce their own density and at the same time produce also cracks. As better shown in figure 5, the density DE of the cork of the plank 29 decreases gradually from the lower face 30 towards the upper face 31 along an axis X corresponding to the thickness of the plank 29. The plank 29 has a plurality of passing-through lenticels 6, which extend perpendicularly to the faces 30 and 31 and parallel to the direction R, and a plurality of year layers 7 separated from each other by rings 8. The direction R is called radial direction because it represents the radial direction with respect to the trunk of the cork oak, not shown, before the planks 29 are removed and flattened and maintains the definition of radial direction R also after the planks 29 have been flattened. In accordance with the present method, the pieces 5, 13, 14, 19 are formed by die-cutting or cutting of the respective lateral walls 3, 11 and 17 of the plank 29 along directions parallel to the direction R and to the lenticels 6.
[0020] With reference to figure 6a, a plank 29a with substantial thickness is used for producing a piece 5 with heght H, indicated by dotted lines, which is formed in the part of the cork plank 29a close to the lower face 30, so that the density of the pieces 5 is relatively high and there are no cracks. This solution permits to obtain stoppers 1 formed by cork pieces 5 with high quality both from the mechanical and chemical point of view. The outline of a known stopper 32 with a diameter D3 is shown close to the outline of the piece 5. The fact of forming stoppers 1, 9 and 15 only in correspondence with the lower face 30 has the additional advantage of avoiding the use of cork placed in correspondence with the upper face 31 which, in addition to having a density which is insufficient for ensuring a good mechanical behaviour of the cork itself, has a great quantity of chemical and microbiological pollutants, whereas the cork placed in correspondence with the lower face 30 is substantially free of such pollutants. With reference to figures 6b and 6c, relatively thin planks 29b and 29c with respect to the plank 29a do not permit to form stoppers 1, 5 with heght H which have homogeneous characteristics along the respective axes 2 and 16 and which avoid the use of cork sufficiently far away from the upper face 31. For this reason, pieces 13 and 14 are obtained by the planks 29b and 29c, which have an heght lower than the heght H of the piece 5 and whose outline is indicated by dotted lines in figures 6b and 6c, in correspondence with the lower face 30, thereby preventing the use of cork with poor chemical and physical properties. Figures 6b and 6c also indicate by dotted line the outline of a traditional stopper 32, which in case of thin planks 29b and 29c incorporates also cork with poor chemical and physical properties.
[0021] The fact of forming stoppers 1, 9 and 15 with a substantially high diameter D, and in any case greater than the diameter D3, represents a substantially advantage in view of the fact that the diameter is an important parameter for ensuring an effective closure of the bottle 20. The present method provides also that the stoppers 1, 9, 15 are made by cork coming from known treatments or, as an alternative, they can be made of crude cork, that is of non-boiled cork.
[0022] In accordance with a not shown variant, the stoppers 1, 9 and 15 can be used for bottles 20 of sparkling wines and champagne, possibly in combination with a small cage closed by a strap.
1. Closure element of natural cork for bottles (20) containing drinkable liquids, adapted
to be inserted with interference into the neck (21) of the bottle (20), the neck (21)
having a first axis (22), the closure element (1, 9, 15) being a geometric solid with
a constant cross-section along a second axis (2; 10; 16) which is coincident with
said first axis (22) when the closure element (1; 9; 15) is inserted into said neck
(21), said closure element (1; 9; 15) comprising a plurality of lenticels (6) distributed
into said closure element (1; 9; 15), the lenticels (6) being substantially parallel
to each other and extending in a determined direction (R), said lenticels (6) being
elements characteristic of natural cork; said closure element (1; 9; 15) being characterized
in that it is oriented with respect to the lenticels (6) so that the respective second
axis (2; 10; 16) is substantially parallel to said lenticels (6).
2. Closure element according to claim 1, characterized in that said cross-section is
substantially circular, said second axis (2; 10) being the axis (2; 10) of a cylinder.
3. Closure element according to claim 1, characterized in that said cross-section is
a polygon comprising at least four sides, said second axis (16) being the symmetry
axis (16) of a prism.
4. Closure element according to any of the preceding claims, characterized in that said
closure element is defined by a single piece (5; 19) of natural cork.
5. Closure element according to any of claims 1 to 3, characterized in that said closure
element 9 consists of two or more pieces (13; 14) of natural cork, joined to each
other transversally to the longitudinal axis (10).
6. Closure element according to any of the preceding claims, characterized in that a
first dimension (H) of said closure element (1; 9; 15) measured along said axis (2;
10; 16) is less than or substantially equal to a second dimension (D) of said element
(1, 19, 15) measured perpendicularly to said axis (2; 10; 16).
7. A method for producing a closure element (1; 9; 15) according to claim 4 or 5, said
closure element (1; 9; 15) comprising a lateral surface (3; 11; 17), the method comprising
the steps of separating said pieces (5; 13, 14; 19) from a cork plank (29) having
a lower face (30) and an upper face (31) substantially parallel to each other, said
plurality of lenticels (6) characteristics of natural cork extending from the lower
face (30) and the upper face (31) substantially perpendicular to said lower and upper
faces (30; 31), said method being characterized in that it comprises the steps of
die-cutting or cutting said piece (5; 13; 14; 19) perpendicular to said lower or upper
face (30; 31) for forming said lateral surfaces (3; 11; 17) of said closure element
(1; 9; 15).
8. A method according to claim 7, characterized in that said method comprises the step
of joining at least two of said pieces (13, 14) transversally to the axis (10) of
the pieces (13, 14).
9. A method according to claim 7 or 8, characterized by forming said pieces (5; 13; 14;
19) in correspondence with said lower face (30), said lower face being the belly of
the plank (29).
10. A method according to any of claims 7 to 9, characterized in that said pieces (5;
13; 14; 19) are made of boiled cork.
11. A method according to any claims 7 to 9, characterized in that said pieces (5; 13;
14; 19) are made of crude cork, that is of non-boiled cork.
12. A closure element of natural cork for bottles, substantially as disclosed with reference
to the attached drawings.
13. A method for producing a closure element of natural cork for bottles, substantially
as disclosed with reference to the attached drawings.