WO1999001354A1

WO1999001354A1 - Bottle stopper made of synthetic material

Info

Publication number: WO1999001354A1
Application number: PCT/US1998/013687
Authority: WO
Inventors: Jerome M. Zech, Jr.; Dennis L. Burns
Original assignee: Supreme Corq
Priority date: 1997-07-01
Filing date: 1998-06-30
Publication date: 1999-01-14
Also published as: AU8474498A

Abstract

A synthetic cork for removable insertion into an opening of a bottle. The synthetic cork comprises a hard plastic top having a first diameter coupled to a shaft comprising a thermoplastic elastomer having a second diameter, wherein the second diameter of the shaft is smaller than the first diameter of the top, and wherein the second diameter is shaped to removably seal the opening of the bottle. The thermoplastic elastomer of the shaft comprises one or more block copolymers.

Description

BOTTLE STOPPER MADE OF SYNTHEΗC MATERIAL

TECHNICAL FIELD

The present invention is generally directed to an easily removable synthetic cork suitable for removable insertion into a bottle. In particular, this invention is directed to a synthetic cork having a hard plastic top coupled to a shaft comprising a thermoplastic elastomer. As such, the bi-compositional synthetic cork of the present invention may be used, for example, as a bottle closure or stopper for liquor, wine, spirits and specialty foods.

BACKGROUND OF THE INVENTION Containers such as bottles for hard spirits and specialty foods (such as brandy and other liquors, maple syrup and vinegar) are often closed via the use of a T-shaped closure that comprises a hard plastic grasping portion and a natural cork shaft adapted to be removable inserted into the opening of the container. Some problems associated with such T-shaped closures include, among other things, incidence of trichloral-alanine (TCA), a bacteria that imparts "off flavors to the beverage in the container, disintegration of cork within the liquid, improper sealing which causes spoilage, and separation of the shaft from the hard plastic top.

In addition, there are significant disadvantages with using natural cork in the manufacture and marketing of T-shaped bottle closures. For example, natural cork has variable properties with respect to color, drying, shrinkage or expansion, crumbling, sticking to containers and seal formation. These features are often unsatisfactory in terms of production and consumer costs, as well as product performance. In the case of wine closures, natural cork may also impart an odor to the product, causing it to be rejected by consumers. In addition, nearly 10% of bottled wine is discarded because of unpredictable contamination by mold from natural cork. Further, the use of cork for producing bottle closures is becoming increasingly expensive as the supply of trees from which natural cork is obtained rapidly diminishes.

Numerous attempts have been made to develop alternatives to natural cork bottle stoppers. Among these, screw top closures for wine containers have been found largely unsuitable because they do not provide the appearance, ceremony or romance that surrounds traditional natural cork wine closures. A number of synthetic cork closures have also been developed. In particular, recent efforts to develop closures from injection molded foam thermoplastics have encountered numerous pitfalls, particularly in terms of production costs, product performance, and consumer acceptance. Some of these closures have exhibited a tendency to noticeably taint the product and/or offer low resistance to oxygen permeation into the container. In addition, synthetic corks from foam thermoplastics have generally exhibited poor uniformity in terms of size, shape, weight, and other features important to production, marketing, and performance.

In a particular case of injection molding of foam thermoplastic closures for liquid containers, thermoplastic compositions are injected into relatively cool molds, leading to the formation of a dense outer "skin" at the surface of the closure and a porous, foam-like interior. The composition of the closure and the structural relationship between the outer skin and porous core of the closure may be critical to the sealing capabilities of the finished closure. Other foam thermoplastic closures have suffered problems due to wrinkling of the outer skin layer, which can produce leakage fissures between the closure and container. Other prior art closures have different sealing problems, for example, failing to quickly return to normal size after compression, such that reliable seal formation requires containers to be kept in an upright position for an extended period after insertion of the closure. Further, prior art closures are unable to significantly retain printed matter for a significant period of time.

United States Patent No. 4,363,849 discloses the production of thermoplastic closures having a natural cork-like appearance. Special molding apparatus are used, however, and it is necessary to gradually release the air in the cold molding cavity that is displaced by the injected thermoplastic resinous material by means of controlled minimum venting or other means in order to maintain a heightened pressure, for example, about 16,000 psi. within the mold. United States Patent No. 4,188,457 discloses a thermoplastic composition that is also used to form closures for wine bottles. The thermoplastic composition includes sulfur dioxide and water, and the sulfur dioxide is said to act as an oxygen scavenger. This method is undesirable, however, because the sulfur dioxide or the metabisulphite from which it is produced may taint the liquid in the bottle or container. Accordingly, there is a need in the art for an easily removable synthetic cork that overcomes these and other disadvantages. The present invention fulfills these needs and provides further related advantages.

SUMMARY OF THE INVENTION

Briefly stated, the present invention is directed to a synthetic cork for removable insertion into an opening of a bottle. The synthetic cork comprises a hard plastic top having a first diameter coupled to a shaft comprising a thermoplastic elastomer having a second diameter, wherein the second diameter of the shaft is smaller than the first diameter of the top, and wherein the second diameter is shaped to removably seal the opening of the bottle. In a further aspect of this embodiment, the thermoplastic elastomer of the shaft comprises one or more block copolymers selected from the group consisting of a styrene-ethylene-butylene-styrene copolymer, a styrene-butadiene styrene copolymer or a styrene-isoprene-styrene copolymer. In yet a further aspect of this embodiment, the shaft of the synthetic cork further comprises a rounded circular edge, and the hard plastic top may be of any shape; however, bulbous, substantially spherical, and cylindrical are preferred shapes.

These and other aspects of the present invention will become evident upon reference to the following detailed description and attached drawings. BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 a is a perspective top view of a first representative synthetic cork having a hard plastic top coupled to a thermoplastic elastomer shaft in accordance with the present invention.

Figure lb is a cross-sectional view taken substantially along line lb- lb of Figure la showing the hard plastic top having an extension that extends downwardly into the thermoplastic elastomer shaft.

Figure lc is a cross-sectional view taken substantially along line 2c-2c of Figure lb showing a portion of the hard plastic top encircling the shaft, and a portion of the shaft encircling the extension of the hard plastic top.

Figure 2a is a perspective top view of a second representative synthetic cork having a hard plastic top coupled to a thermoplastic elastomer shaft in accordance with the present invention. Figure 2b is a cross-sectional view taken substantially along line 2b-2b of Figure 2a showing the hard plastic top having an extension that extends downwardly into the thermoplastic elastomer shaft.

Figure 2c is a cross-sectional view taken substantially along line 2c-2c of Figure 2b showing a portion of the hard plastic top encircling the shaft, and a portion of the shaft encircling the extension of the hard plastic top.

Figure 3a is a perspective top view of a third representative synthetic cork having a hard plastic top coupled to a thermoplastic elastomer shaft in accordance with the present invention.

Figure 3b is a cross-sectional view taken substantially along line 3b-3b of Figure 3a showing the hard plastic top having an extension that extends downwardly into the thermoplastic elastomer shaft.

Figure 3c is a cross-sectional view taken substantially along line 3c-3c of Figure 3 b showing a portion of the hard plastic top encircling the shaft, and a portion of the shaft encircling the extension of the hard plastic top. DETAILED DESCRIPTION OF THE INVENTION

The present invention provides a synthetic cork for a container, such as a bottle, comprising a hard plastic top coupled to a shaft, wherein the shaft comprises a thermoplastic elastomer. The hard plastic top may be made from any suitable hard plastic, many varieties of which are well known in the art, and preferably an acrylonitrile-butadiene-styrene (ABS) and/or a high-impact polystyrene (HPS). A suitable HPS is Dow #478, a suitable ABS/HPS is Dow AIM 4800, and a suitable ABS may be purchased from either The Dow Chemical Company (Midland, Michigan) or Bayer AG (Leverkusen, Germany). The shaft comprises a thermoplastic elastomer, preferably a styrene block copolymer, and further preferably one or more of a styrene-ethylene-butylene-styrene copolymer (SEBS), a styrene- ethylene-butylene copolymer, a styrene-butadiene-styrene copolymer, a styrene- butadiene copolymer, a styrene-isoprene-styrene copolymer, a styrene-isoprene copolymer. a stryrene-ethylene-propylene-styrene copolymer or a styrene-ethylene- propylene copolymer. Such copolymers are discussed in United States Patent Nos. 5,480,915 and 5.496,862, each of which are incorporated herein by reference in their entirety. Preferably, the thermoplastic elastomer is combined with a blowing agent to produce the shaft. More specifically, the present invention features a synthetic cork for a bottle or container comprising a hard plastic top and a shaft that comprises a thermoplastic elastomer (TPE) and a blowing agent in a ratio suitable to provide the shaft with closing and/or sealing capabilities of the bottle, thereby preventing spillage. In addition, the synthetic cork of the present invention is able to prevent the passage of oxygen from the atmosphere into to the bottle, while simultaneously not substantially absorbing oxygen from the contents or air space within the bottle. Furthermore, the synthetic cork has the ability to be manually removed without substantial expansion, crumbling or disintegration.

It is also possible to print on the synthetic cork, including the surface of the synthetic cork that contacts the container, and the container can be placed on its side immediately after the synthetic cork has been inserted into the container. The synthetic cork also has the ability to be used over an extended period (suitable, for example, to allow wine to properly age to reach an appropriate drinkability, which can be about two years or more), and has the ability to resist solvation in alcohol, acid or base, thereby keeping the contents of the container free from tainting. Preferably, the TPE shaft of the synthetic cork further comprises one or more of a lubricant, a coloring agent, a filler, or other additives that can improve the performance and/or producibility of the closures. The TPE shaft of the synthetic cork does not, for example, include an oxygen scavenger, such as sulfur dioxide, which has been used in the past to increase the impermeability of synthetic corks, but which can taint the contents of the container such as wine.

In another aspect of the invention, the shaft portion of the synthetic cork is formed from a composition comprising one or more TPEs and one or more blowing agents. The durometer measurement of the shaft portion, which is effectively an indirect measure of the hardness of the TPE used to make the shaft of the synthetic cork, is generally from about 65A to about 90A, typically from about 70A to about 85A, and preferably from about 75A to about 80A. The TPE generally comprises from about 70% to about 97% by volume of a mixture suitable for forming the shaft, typically from about 80% to about 95%, and preferably from about 90% to about 95% (unless otherwise noted, all percentages herein are by volume). The TPE exhibits little or no interaction with, or tainting of, liquids such as wine. The TPE also has a suitable force of compression for improved sealability and long service life. The TPE is easily processed, enabling fast cycle times and high production rates. Further, selected TPEs meet FDA requirements for indirect food additives intended to come in contact with food.

In a preferred embodiment, the TPE comprises a styrenic block copolymer, and further preferably comprises one or more of a styrene-ethylene- butylene-styrene copolymer ("SEBS"), a styrene-ethylene-butylene copolymer, a styrene-butadiene-styrene copolymer, a styrene-butadiene copolymer, a styrene- isoprene-styrene copolymer, a styrene-isoprene copolymer, a styrene-ethylene- propylene-styrene copolymer, and a styrene-ethylene-propylene copolymer. Many of these copolymers are available under the tradename KRATON®. In a still further preferred embodiment, the styrenic block copolymer is SEBS. Examples of such an SEBS copolymers include J-VON®, DYNAFLEX GS6771-000 and DYNAFLEX GX6768-1000, which possess desirable ozone and heat resistance for a long service life. In addition, such SEBS copolymers are resistant to water, bases, acids, and alcohol. J-VON® is commercially available from J. Von Ltd. Partnership, Leominster, Massachusetts; DYNAFLEX GS6771-000 and GX6768-1000 are available from CC&P, Portland, Oregon. The blowing agent generally comprises from about 3% to about 5% of a mixture suitable for forming the shaft portion of the synthetic cork, typically from about 3.5% to about 4.5%, and preferably about 4%. The precise amount of blowing agent used may be determined by one skilled in the art by taking into account the precise polymer, blowing agent, and other ingredients used, as well as the molding conditions. Generally, the amount of blowing agent should not substantially exceed about 5% of the total mixture. The use of substantially above about 5% of blowing agent will generally result in a shaft that has excessively large cells in its interior, thus causing the shaft to be overly spongy and potentially inconsistent during production. Generally, the amount of blowing agent should not be substantially less than about 3% of the total mixture. The use of substantially less than about 3% of blowing agent will generally result in a shaft that does not have enough cells or inadequately sized cells. Such a shaft can be too hard for routine manual removal, among other problems.

In a preferred embodiment, the blowing agent is Spectratech™ FM1150H, which is commercially available from Quantum Chemical Corp., USI Division, Cincinnati, Ohio. Spectratech™ FM1 150H is a polyolefm-based compound consisting of a low-density polyethylene based endofhermic foam concentrate, comprising 50% resin of the formula CH3-(CH2)_n- H3 and 50% of a combination of sodium bicarbonate (NaHCO3) and citric acid. The beneficial qualities of Spectratech™ FM1150H include rapid degassing, improved cycle times. improved density distribution, and superior surfaces for molded articles. Other suitable blowing agents such as azodicarbonamide, ozodecarbonoxide, and sodium bicarbonate also may be used. Other such blowing agents may be used without departing from the spirit and scope of the present invention. In another embodiment, one or more fillers may be used in combination with the TPE and other added materials. For example, the filler may comprise calcium carbonate. If such a filler is used, it comprises up to about 20% or more of a mixture suitable for forming the shaft portion of the synthetic cork, but preferably up to about 5% of the mixture. Using such a filler can economize material expenditures. Other filler materials are apparent to those skilled in the art.

In another embodiment of the present invention, powder or liquid pigments are added to the mixture of TPE and other materials. The powder or liquid pigments generally comprise less than about 1 % of the total composition. Preferably, the pigment is pre-blended with a thermoplastic resinous material such as polypropylene, and/or a portion of the TPE, before its addition to the main feedstock of TPE and other materials.

In a preferred embodiment, the mixture suitable for forming the shaft portion of the synthetic cork comprises about 94% TPE. about 4% blowing agent, about 2% low density polypropylene, and a minor percentage of a desired pigment. In a further preferred embodiment, the pigment, the polypropylene and about 2% of the TPE are pre-blended, then introduced as a homogeneous mixture to the remaining TPE and blowing agent. In an alternative preferred embodiment, wherein the composition further comprises a filler, the composition comprises from about 75% to about 95% TPE, from about 3.5% to about 4.5% blowing agent, and up to about 20% filler.

In yet another preferred embodiment, a lubricant such as a fatty acid, a silicone, alcohol or water is added before or after the synthetic cork formation process, which may ease insertion of the synthetic cork into a container. Preferably, the lubricant is a fatty acid, and comprises less than about 0.5% of the total composition. It is a feature of the present invention that the synthetic cork can permanently retain printed matter on the surface of the synthetic cork that contacts the container. The surface of many synthetic corks are typically very slick and therefore unable to effectively receive or to retain such printed matter. In order to retain printed matter, the compound is preferably a TPE, preferably a styrene block copolymer, and further preferably an SEBS copolymer, although a thermoplastic resin may also be used. Further, the synthetic cork, subsequent to molding, is preferably subjected to a treatment to prepare the surface for printing. Preferably, the treatment comprises subjecting the synthetic cork to high intensity electromagnetic radiation, and further preferably in the visible light range or near the visible light range (e.g., U.V. light). One example of such a treatment is known as a corona pre-treatment, which is a standard treatment in the printing industry. The treatment is preferably performed prior to printing, but can be performed after printing.

It is yet another feature of the present invention that a container, such as a wine bottle, can be placed horizontally generally within about 4 hours, typically within about 1 hour, and preferably substantially immediately after receiving a synthetic cork produced in accordance with the present invention. It is believed that this property of the synthetic cork is attained because the inventive composition permits the synthetic closure to achieve an interior cell size that causes the synthetic closure to return to at least about 90% of its original diameter within about 4 to about 5 seconds after being released from a compressed state.

Accordingly, after the synthetic cork is compressed and inserted into the container, the synthetic cork returns to approximately its normal size within from about 4 to about 5 seconds, thereby allowing the container to be substantially immediately placed horizontally without spilling the contents of the container and without interfering with the seal between the synthetic cork and the container. For example, when the container is a wine bottle, it does not need a standing period before being racked.

In still another embodiment of the present invention, one or more other materials may also be added to the overall composition, including chemical blowing agent activators and other additives that can improve the producibility and/or performance of the closures. For example, if desired, a material may be added that can enhance the aroma and/or flavor of the liquid in the container.

The molded closure, comprising a hard plastic top and a thermoplastic elastomer shaft, may be produced using a variety of known molding and joining methods. For example, the shaft portion of the synthetic cork may be formed by conventional processing techniques such as injection molding, extrusion, vacuum forming, and solution casting. Preferably, the synthetic cork is made using co- injection molding equipment that injection molds two different types of materials at or about the same time. Thus, the co-injection molding equipment, and the process of using the same, molds the hard top and the elastomeric shaft as a single unit. Examples of bi-compositional synthetic corks in accordance with the present invention are set forth in the Figures attached hereto.

Referring to Figures l a, 2a. and 3a, therein is shown a top perspective view of three representative synthetic corks each having a hard plastic top coupled to a thermoplastic elastomer shaft in accordance with the present invention. Specifically, Figure la depicts a synthetic cork having a bulbous shaped hard plastic top; Figure 2a depicts a synthetic cork having a cylindrical shaped hard plastic top with a plurality of longitudinal grooves on the outer circumference; and Figure 3a depicts a synthetic cork having a cylindrical shaped plastic hard top with a plurality of longitudinal ridges on the outer circumference. In each of these exemplary embodiments, the bulbous shape, the plurality of longitudinal grooves, and the plurality of longitudinal ridges, allow one to more easily grip the synthetic cork, thereby facilitating removal and insertion of the synthetic cork into a suitable container or bottle.

Referring now to Figures lb, 2b, and 3b. therein is shown a cross- sectional view taken substantially along line 1-1, line 3-3, and line 5-5 of Figures la. 2a, and 3a, respectively. Specifically, each of these figures depicts a hard plastic top having an extension, wherein the extension extends downwardly into the thermoplastic elastomer shaft. The extension portion of the hard plastic top allows the production of a more cost-effective product.

Referring now to Figures lc, 2c, and 3c, therein is shown a cross- sectional view taken substantially along line 2-2, line 4-4, and line 6-6 of Figures lb, 2b, and 2c, respectively. Specifically, each of these figures depicts a preferred shape of the extension and exemplary configurations of the interface between the hard plastic top and the thermoplastic elastomer shaft. The plurality of longitudinal cogs of the extension portion of the hard plastic top strengthens the coupling between thermoplastic shaft and hard plastic top. The bi-compositional synthetic corks of the present invention are typically used as a bottle closure or stopper for liquor, wine, spirits and specialty foods. These synthetic corks are particularly well suited for such use because such beverages are typically packaged in a bottle that is opened and closed several times over an extended period. For this reason, durability and sealing capability are very important to the closure. The thermoplastic elastomer shaft is a strong material that provides superior properties for such uses, while the hard plastic top makes the closure easy to grasp, remove and reinsert. The co-injection molding process is also preferred both because of its cost-effectiveness, and because it permanently attaches the thermoplastic elastomer shaft to the hard plastic top, thereby allowing for multiple openings and resealings of containers with reduced incidence of separation or breakage of the shaft from the top (although other manufacturing processes can also provide such benefits). The bi-compositional synthetic corks of the present invention may be produced such that both the hard plastic top and the thermoplastic elastomer shaft are of the same color, or of different colors as desired. Accordingly, the present invention provides a synthetic cork for a liquid container that comprises a hard plastic top coupled or otherwise joined to a shaft comprising a thermoplastic elastomer, and preferably a blowing agent, wherein, upon insertion of the synthetic cork into a bottle containing a liquid, the synthetic cork does not permit substantial passage of oxygen into the bottle, does not substantially absorb oxygen from the contents of the bottle, does not substantially taint the contents of the bottle, permits the bottle to be placed horizontally substantially immediately after insertion of the synthetic cork into the bottle, and, if desired, may permanently retain printed matter on a surface of the synthetic cork.

While the present invention has been described in the context of the embodiments described and illustrated herein, the invention may be embodied in other ways or in other specific forms without departing from its spirit and essential characteristics. Therefore, the embodiments of the present invention as described and illustrated herein are to be considered in all respects only as illustrative and not restrictive. The scope of the present invention is, therefore, indicated by the appended claims rather than by the forgoing description, and all changes that come within the meaning and range of equivalency of the claims are to be embraced within their scope.

Claims

1. A synthetic cork for removable insertion into an opening of a bottle, the synthetic cork comprising a hard plastic top having a first diameter coupled to a shaft comprising a thermoplastic elastomer having a second diameter, wherein the second diameter of the shaft is smaller than the first diameter of the top, and wherein the second diameter is shaped to removably seal the opening of the bottle.

2. The synthetic cork of claim 1, wherein the hard plastic top further comprises an extension that extends into the shaft.

3. The synthetic cork of claim 1 or 2, wherein the thermoplastic elastomer of the shaft comprises a styrene block copolymer.

4. The synthetic cork of claim 3, wherein the thermoplastic elastomer comprises one or more block copolymers selected from the group consisting of a styrene- ethylene-butylene-styrene copolymer, a styrene-butadiene styrene copolymer, a styrene- isoprene-styrene copolymer, or a styrene-ethylene-propylene-styrene copolymer

5. The synthetic cork of claim 3, wherein the thermoplastic elastomer comprises a styrene-ethylene-butylene-styrene block copolymer.

6. The synthetic cork of claim 1 , wherein the shaft further comprises a filler.

7. The synthetic cork of claim 6, wherein the filler comprises about 5% to about 20% by volume of a mixture suitable for forming the shaft.

8. The synthetic cork of claim 1, further comprising a coloring agent selected from the group consisting of a powder pigment and a liquid pigment.

9. The synthetic cork of claim 1 , further comprising a lubricant selected from the group consisting of a fatty acid, a silicon, an alcohol and water.

10. The synthetic cork of claim 9, wherein the lubricant is a fatty acid.

1 1. The synthetic cork of claim 1 , wherein the shaft further comprises one or more of a chemical blowing agent activator and a material able to enhance the aroma or flavor of the contents of the bottle.

12. The synthetic cork of claim 1. wherein the synthetic cork has a symbol embossed thereon.

13. The synthetic cork of claim 1, wherein the shaft further comprises a marbled surface texture.

14. The synthetic cork of claim 1, wherein the shaft further comprises a rounded circular edge.

15. The synthetic cork of claim 1 , wherein the hard plastic top has a bulbous shape.

16. The synthetic cork of claim 15, wherein the hard plastic top has a substantially spherical shape.

17. The synthetic cork of claim 1, wherein the hard plastic top has a cylindrical shape with an outer circumference.

18. The synthetic cork of claim 16, wherein the hard plastic top has a plurality of longitudinal grooves on the outer circumference.

19. The synthetic cork of claim 16, wherein the hard plastic top has a plurality of longitudinal ridges on the outer circumference.