EP1631504A1 - Structure of closure for closing liquid containers - Google Patents

Abstract

A closure structure (1) for closing containers, particularly wine bottles, comprises a substantially elongate cork body (2), a synthetic insert (3) attached on at least one end face (4) of the body (2) that is designed to be turned toward the inside of the s container to separate the cork body from the liquid contained therein. The synthetic insert (3) is an element made of an elastomeríc thermoplastic resin, which is thermoformed and co-molded directly on the body (2), with no intermediate layer being provided therebetween. The elastomeric thermoplastic resin is selected from the group comprising polyurethane, polyethylene, silicone, rubber, caoutchouc, polybutadiene or polypropylene materials. A particular elastomeric thermoplastic resin is a polyurethane having a Shore A hardness, according to ASTM D2240, of 60 to 80isand preferably of 65 to 75 and density, according to ASTM D792, of 0.80 to1.2kg/dm3.

Description

STRUCTURE OF CLOSURE FOR CLOSING LIQUID CONTAINERS

Field of the invention

The present invention relates to a composite-material closure or stopper structure for closing liquid containers.

The closure structure according to the present invention is designed to be used in automatic corking machines for industrial bottling factories or for private manual corking operations.

More particularly, the closure structure of the present invention may be an advantageously applied in glass bottle corking, particularly for bottling and storage of wines.

State of the art

It is known that bottles may be corked with closures of various kinds, such as screw stoppers, which require a thread to be formed on the bottle, crown stoppers, which have a limited sealing action with time and are known to be unsuitable for wine storage, synthetic stoppers, which are entirely or partly made of plastic, stoppers made of a part of synthetic material and a part of cork and finally entirely made of cork stoppers, which are particularly suitable for bottling of valued wines.

Cork is still widely considered as the most appropriate material for wine preservation, especially for long-term bottle storage.

Finally, it is known that a cork stopper is partly permeable to oxygen, and consequently interacts with the wine ageing process thereby increasing its complexity and richness. On the other hand, the use of cork stoppers requires a number of precautions to be taken to prevent the occurrence of drawbacks that may affect the final quality of wine.

In fact, it is known that cork stoppers have to be selected of the right size, relative to the size of the bottle opening to be closed, and of good quality, as they have to ensure a notable elastic properties in order to yield under pressure and recover their original shape to appropriately seal the bottle neck.

Moreover, closures should not exhibit chipping or cracking signs, caused by a too dry or friable cork, or grooves formed by too close cuts during the manufacturing process, or wooden rings caused by rainless growth seasons.

As is known, stoppers must not generate molds or fungi, such as the trichloroanisole, which might contaminate the wine with an unpleasant, so-called "corky" smell, must not release powders or have abnormal smells and should preferably have a 5 to 8% residual moisture.

In order to obviate such drawbacks, cork closures should be subjected to sterilization, tannin removal and red powder removal from lenticels and, to this end, they should be treated with hot washing processes and chemicals such as: potassium metabisulfite, calcium hypochlorite, oxalic acid, hydrogen peroxide, sodium hydroxide, citric acid.

Further, stoppers are generally subjected to an additional surface treatment with paraffin and/or pure elastomer silicones to reduce liquid permeability and decrease sugar-wine interchange.

After a step in which the oxidizing residues from washing operations are neutralized, stoppers are to be kept in a cool and dry place, preferably in plastic bags containing a certain amount of sulfur dioxide. Thanks to the above arrangements, for non top-quality wines, to be consumed within a few years from bottling, wine makers are increasingly interested in synthetic stoppers, which are less problematic and expensive.

On the other hand, the choice of an entirely-cork closure is mainly associated to a traditional and widespread appreciation of all-natural products, e.g. wines stored in bottles with a cork stopper, instead of wines stored in bottles with wholly or partly synthetic stoppers.

Obviously, stopper manufacturers shall consider this emotional factor which largely affects consumer choices.

As is known, synthetic stoppers are currently available on the market in a number of types.

Obviously, entirely-plastic closures are the least appreciated by consumers which, as mentioned above, are traditionally reluctant to associate a natural product like wine to plastic parts.

Sometimes, plastic stoppers provide a sealing action on bottles by means of annular flanges which, as is known, do not have a satisfactory and reliable elastic behavior.

This type of stopper cannot be extracted from the bottle neck in the conventional manner, namely by using the traditional corkscrew, due to the high hardness of the plastic in use, and requires a manual or mechanical pulling action on a portion of the stopper head protruding out of the bottle neck.

In order to obviate these drawbacks either, composite stopper structures have been recently manufactured, having a cork core and a plastic insert, or stopper structures formed by a cylindrical body made of cork and a plastic end portion attached to at least one end thereof. Such structures are capable of isolating wine from the cork, and protecting it from the above undesired effects. Composite structure stoppers of this type are visually much more similar to cork stoppers than all-synthetic stoppers, and they are accordingly more appreciated by the public.

However, in practice prior art stopper structures of this type have configurations and/or materials that prevent an optimized use thereof.

No composite closure structure, is presently available on the market that is composed of a synthetic part and a cork body, which has an optimal mechanical behavior, particularly a high elasticity, to ensure an effective sealing effect on the bottle neck, while allowing easy extraction of the stopper by using a normal corkscrew.

Furthermore, even the arrangements of stoppers that include synthetic parts having good mechanical properties cannot ensure a satisfactory coupling with the cork body, as an alternative they use highly complex coupling means, otherwise they have no cork body at all and are wholly made of synthetic material.

The composite structure stopper examples, including a cork body and a synthetic insert, disclosed and claimed in patent application MI97A000346 and in patent IT- A-1247147 show particularly complex structures and cannot ensure that the plastic insert is correctly anchored to the cork body.

Both these prior art arrangements use too rigid plastic materials, such as polyethylene, whose mechanical properties are not particularly intended for the requested use.

The stoppers according the contents of the above patents are difficult to remove in practice. It is finally noted that many other arrangements currently on the market do not sufficiently account for the fact that corking operations with composite cork- synthetic large-diameter stoppers (generally for use in Spumante bottles) often causes, especially with low-elasticity and particularly rigid materials like those used to date, an excessive compression of the synthetic part, which does not allow an easy extraction of such stoppers particularly at low temperatures.

As is known, synthetic thermoplastic materials at low temperatures may become excessively hard and be incapable of deformation required for passing through the bottle neck.

FR-A-2644142 discloses a cork stopper structure having on both end faces an elastomeric layer, preferably silicone, which is deposited by spraying or coated.

WO 00/26103 and WO 01/14219 describe the use of plastic materials to make particularly effective synthetic stoppers, having high-performance mechanical and sealing properties.

However, in the embodiment described in WO-A-00/26103, the synthetic part must be bonded to another inner part particularly made of a more rigid plastic material.

The aspect of the resulting stopper structure is that of a wholly or mainly plastic product which is not appreciated by consumers.

For the same reasons, the embodiment described in US-A-6127437 is not much appreciated although it using an elastomeric thermoplastic material having good mechanical properties.

The arrangement proposed by WO-A-01/14219 make use of a synthetic disk, laid over the cork body and attached thereto by a layer of a food-grade adhesive. This arrangement does not provide wine isolation from cork, and has many of the above mentioned cork stopper limitations. Moreover, like the arrangement disclosed in FR-A-1100335, this arrangement does not allow an optimal attachment between the two different parts as the adhesive layer is not suitable to bond materials of different natures.

Finally it is noted that the elastic behavior of most synthetic materials used to make stoppers is characterized by an insufficient resilience.

Therefore during corking operations the closure tends to get out of the bottle neck due to the pressure contained therein, especially if the beverage contained in the bottle is sparkling or added with carbon dioxide.

Disclosure of the invention

The main object of this invention is to obviate the drawbacks of the above mentioned prior art by providing a composite-material closure structure, having high mechanical properties to allow easy insertion in and extraction thereof from a bottle neck.

A further object of this invention is to provide a simple and inexpensive stopper structure.

Yet another object of the invention is to provide a closure structure having a synthetic insert which allows to preserve all the liquid in the container from possible contaminations by the cork body.

A further object of this invention is to provide a composite cork-resin closure structure having a pleasant appearance for consumers.

Another object of this invention is to provide a closure structure allowing easy extraction thereof from the bottle neck even by using a normal corkscrew. These objects as well as other which will be more apparent hereinafter, are achieved by a composite-material closer structure, particularly for wine bottles, which comprises a substantially elongate cork body, a synthetic insert attached to at least one end face of said body to be turned toward the inside of the container, to separate the cork body from the liquid contained therein, characterized in that said synthetic insert is an element made of an elastomeric thermoplastic resin, which is thermoformed and co-molded directly on said body, with no intermediate layer provided therebetween.

Preferably, the elastomeric thermoplastic resin is selected from the group comprising polyurethane, polyethylene, silicone, rubber, caoutchouc, polybutadiene or polypropylene materials.

Moreover, the aforsaid elastomeric thermoplastic resin is a polyurethane having a Shore A hardness of 60 to 80 and preferably of 65 to 75.

Brief description of the drawings

Further features and advantages, will be more clearly understood in the light of the detailed description of preferred embodiments of closure according to the invention furnished by way of non limit example with the assistance of the annexed drawing in which:

FIG. 1 is a general overview of a first embodiment of the closure structure of the present invention;

FIG. 2 is a side view of the closure structure of Fig. 1 ;

FIG. 3 is a side sectional view of the stopper structure as shown in Fig. 1 taken along plane Ill-Ill of Fig. 2;

FIG. 4 is a general overview of a second embodiment of the container closure according to the present invention;

FIG. 5 is a side view of the closure structure as shown in Fig. 4; FIG. 6 is a side sectional view of the closure structure shown in Fig. 4 taken along plane IV-IV of Fig. 5;

Detailed description of a preferred embodiment

With reference to the above mentioned drawings, the closure or stopper structure according to the invention is generally designated by numeral 1.

The closure structure 1 finds an advantageous application as wine bottle closures, even though it but may be similarly used for closures at any other type of container and for the preservation of any food or non-food liquid, without departing from the scope of the present intention.

Structure 1 has a body 2 made of cork or cork conglomerate, having an elongate substantially cylindrical shape, and a synthetic insert 3 attached to an end face 4 of the body 2 designed to be oriented toward the inside of the container.

Thanks to this arrangement, once the closure structure 1 is conventionally inserted into the container neck (not shown), insert 3 is arranged to separate the cork material from the liquid contained in the container.

Thus, the liquid in the container will be protected from any cork contamination (powders or aromas) and air permeability, particularly oxygen permeability will be considerably limited.

According to the invention, insert 3 is an element made of an elastomeric thermoplastic resin, which is thermoformed and co-molded directly on body 2 using a suitable mold whose two parts are coupled to form an inner molding cavity.

In such a manners, at the end of the thermoforming process, insert 3 will be permanently heat-sealed against cork body 2. Particularly, the thermoforming process may include the steps of positioning of the body 2 in an appropriate seat of a base mold, closing the latter with a countermold, injecting or casting melted elastomeric thermoplastic resin into the closed mold, and cooling the closure structure 1 so obtained.

Advantageously, the elastomeric thermoplastic resin shall be a non-toxic and food- grade resin, and may be selected from the group comprising polyurethane, polyethylene, silicone, rubber, caoutchouc, polybutadiene or polypropylene materials.

According to a preferred embodiment, the elastomeric thermoplastic resin is a polyurethane (TPU) having a relatively low Shore A hardness, of 60 to 80, and a melting temperature of 160° to 230°C.

Thanks to the configuration, material and manufacturing process used it will be possible to achieve a high cohesion between cork body 2 and insert 3, to prevent any risk of separation between the two parts during extraction of closure 1.

In accordance with a preferred embodiment of this invention, the insert 3 has a substantially mushroom shape, having a Stem 5 joint to a head 6.

The Stem 5 is accommodated and rigidly engaged inside a corrφlementarily shaped seat 7 formed in body 2.

Head 6 has a disk shape and covers, entirely or at least partly, the end face 4 of body 2.

Preferably, Stem 5 and head of insert 3 are made as a single piece, imparted by the mold shape and by the conformation of the cork body 2. Figures 1 to 3 show a first embodiment of the composite closure structure 1 according to the invention, which is adapted to be used, for instance, on typical Bordeaux style bottles whose opening has an inside diameter of about 17 mm.

Advantageously, in this case, both cylindrical cork body 2 and disk-shaped head 3 made of the elastomeric thermoplastic resin originally have a diameter D of about 24 mm, which must necessarily be deformed during container closing operations.

As is better explained hereinafter, the properties of the material which forms the insert 3 allow a fast shape recovery thereof tight against the inner surface of the bottle neck after the compression step, which is designed to allow container closing operations.

According to a second embodiment, as shown in Figs. 4 to 6, head 6 of insert 3 only overlies a central circular portion 4' of the end 4 of the cork body 2, and leaves the remaining annular portion 4" uncovered.

Such central portion 4' of end face 4 is larger than the opening of the container to still allow insert 3 to be deformed and provide a sealing action during the container closing operation (known as "mushroom corking" for Spumante or other sparkling wine bottles).

The particular configuration used in this latter embodiment allows cork body 2 and insert 3 to exert a differentiated compression and is suitable for the fabrication of closures specially designed for Spumante bottles, namely stoppers 1 that must be highly compressed to exert a strong sealing action against the bottle neck. In fact, as is known, Spumante wines and generally all sparkling wines are stored under pressure due to the presence of a certain amount of gas contained therein.

Thanks to the embodiment shown in Figures 4 to 6, cork body 2 may be designed to perform the mechanical sealing action, whereas insert 3 is designed for isolating the liquid in the container from the outside environment and from cork aromas and contaminating agents.

Advantageously, inserts may all have the same size, to allow the use of a single mold for the fabrication of closures, to be subsequently attached to cork bodies of various sizes.

The mechanical properties of the elastomeric thermoplastic polyurethane (TPU) used herein, and particularly its high elastic memory allow insert 3 to readily recover its original size after deformation.

This allows to perform corking operations in an optimized manner, without running the risk that the stopper 1 inserted in the bottle neck might tend to get out of it due to a too slow elastic recovery.

The particular elastomeric thermoplastic polyurethane being selected has physical and mechanical properties within the value ranges of the Table I below:

TABLE 1

In accordance with a possible embodiment, not shown in the drawings, insert 3 may be also attached, in the above described manner, on both end faces 4 and 8 of cork body 2, i.e not only on the one to be oriented toward turned toward the inside of the container, but also on the one turned toward the outside.

The invention so conceived achieves the intended objects.

In practise, the closure accordy to the invention is susceptible of numerous modifications and changes, all following within the scope of protection defined in the appended claims.

Furthermore, all the details may be replaced by technically equivalents, and any size, shape and material may be any according to various needs.

Claims

1. A closure structure for closing containers, particularly wine bottles, comprising:

- a substantially elongate cork body (2), - a synthetic insert (3) attached on at least one end face (4) of said body (2) to be oriented toward the inside of the container, to separate the cork body from the liquid contained therein; characterized in that said synthetic insert (3) is an element made of an elastomeric thermoplastic resin which is thermoformed and co-molded directly on said body (2) with no intermediate layer provided therebetween.

2. Structure as claimed in claim 1 , characterized in that said elastomeric thermoplastic resin is selected from the group comprising polyurethane, polyethylene, silicone, rubber, caoutchouc, polybutadiene or polypropylene materials.

3. Structure as claimed in claim 2, characterized in that said elastomeric thermoplastic resin is a polyurethane having a Shore A hardness, according to ASTM D2240, of 60 to 80 and preferably of 65 to 75.

4. Structure as claimed in claim 3, characterized in that said elastomeric thermoplastic polyurethane resin has a Shore A hardness according to ASTM D792 of 0.80 to 1.2 Kg/dm³.

5. Structure as claimed in claim 2, characterized in that said insert (3) is a substantially mushroom-shaped element, having a stem (5) engaged inside a complementarily shaped seat (7) formed in said body (2) and a substantially disk- shaped head (6).

6. Structure as claimed in claim 5, characterized in that said substantially disk-shaped head (6) is so sized as to cover at least a central portion (4') of said end face (4), and to leave a remaining substantially annular portion (4") uncovered.

7. Structure as claimed in claim 5, characterized in that said stem (5) is monolithic with said head (6).

8. Structure as claimed in claim 6, characterized in that said central portion (4') of said end face (4) has a diameter larger than the inside diameter of the container neck to allow said insert (3) to be deformed and provide a sealing action during the container closure.

9. Structure as claimed in claim 6, characterized in that said central portion (4') of said end face (4) is so sized that said head (6) of said insert (3) exerts a differentiated compression on cork body (2) and on insert (3) during the container closing operations.