AU2004281942A1

AU2004281942A1 - Closure for containers and method for the production thereof

Info

Publication number: AU2004281942A1
Application number: AU2004281942A
Authority: AU
Inventors: Frank Schellenbach
Original assignee: Individual
Current assignee: Individual
Priority date: 2003-10-13
Filing date: 2004-10-13
Publication date: 2005-04-28
Also published as: BRPI0415461A; CA2545836A1; WO2005037677A1; EP1673289A1

Description

Commonwealth of Australia Patents, Trade Marks and Designs Acts VERIFICATION OF TRANSLATION I David N. Parrott of Klugstrasse 125, 80637 Munich, Gennany, am the tanslator of the Enish-langage document attached and I state that the attached document is a true tranlation of a) *PCT Intemtional ApplicationNo. PCT/EP2O04/011509 as fied on 13 October 2004 (with amendments) b) *A certified copy of the specification accompanying Patent (Utility Model) Application No. filed in on c) *Trade Mark Application No. fled in on d) *Design Application No. filed in on *Delete inapplicable clauses Datedthis. th.............Mday Of.- -............... 2006 Signature of Tranlato .. . . .. . -

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'.'. F.B. RICE & CO PATENT ATTORNEYS PCT/EP 2004/011509 Schellenbach, Frank A Closure for Containers, and a Method of its Manufacture The invention relates to a closure for containers in which food is stored, in particular for bottles of beer, and also relates to a method of manufacturing such a closure. Closing caps for containers in which food is stored, in particular for beverage bottles, usu ally have a two-part design. They consist of a closing cap and a sealing element in the form of a separate sealing ring or circular sealing washer. Because of its strength, the harder cap ensures that the cap is supported on the container. The sealing washer, which is inserted into the cap, is softer and fulfils the sealing function by pressing onto the edge of the opening of the container. The production and disposal of these closures nevertheless entails drawbacks. For example, the cap and sealing washer are manufactured separately and then fitted to gether before the filled container or bottle is closed. The closure components must be once more separated particularly before they are recycled. In addition, however, one-part closures for bottles for soft drinks have already been pro posed, for instance in PCT/EP99/01357. These closures are made of plastic, especially poly ethylene (PE). One of the factors determining the choice of closure material is that no mate rial is supposed to leave the closing cap and penetrate the food. Furthermore, both the clos ing function, the sealing function and, if need be, the warranty function must be satisfied by a tamper-evident band. In this respect, the choice of material and the closure's structural design must meet different and to an extent opposing demands. The material must thus be hard enough to reliably support the cap that is screwed onto the bottle, yet it must be soft enough to ensure sealing when pressed onto the neck of the bottle. The PE material, in the form of a tamper-evident band, can provide a reliable sealing function, good closing func tion and, if need be, the warranty function too. All the same, perishable food, such as beer, is, in addition, faced with the problem that the oxygen trapped inside the container or entering the container has a negative effect on the product's shelf life, with the result that the prescribed shelf-life warranties cannot be met.

-2 For this reason, the bottle must either be deoxygenated when it is sealed up or the oxygen trapped in the sealed bottle has to be reduced. For this purpose, closures, in particular for bottles of beer, are fitted with a sealing washer that has an "oxygen scavenger", i.e. a material exhibiting properties that scavenge or remove oxygen. Such oxygen scavengers are known, for example, from EP 0 664 824 B 1. The seal ing washers are approx. 0.28 mm thick, are soft and must contain a certain minimum amount of oxygen scavenger material so as to provide a sufficient oxygen scavenging ca pacity. On contact with the high atmospheric humidity inside the container or bottle, these materials, having been in dry storage prior to use, are activated and remove the oxygen pre sent inside the container. In addition, such materials lower the diffusion of oxygen into the interior of the container. As described above, the closures in use have a two-part design. The sealing washer must be made separately from the closing cap; the washer and cap are then fitted together before the bottle is sealed. As an alternative, coatings within, and on the surface of, the packaging ma terials are realized as well. A one-part closing cap would be desirable, however, both for production reasons and owing to easier disposal and more advantageous recycling. So far, however, it has not been possible to manufacture a one-part closure that at the same time satisfactorily complies with the closing and sealing functions as well as deoxygenation for the preservation function. The oxygen scavenger materials are soft and hence counteract reliable closure. Although a decrease in the amount of oxygen scavenger material present in the closing cap material might help to increase strength, particularly the closure's necessary stress-cracking resistance, the warranty demands would then no longer be fulfilled, because the oxygen scavenging capacity drops too much when the oxygen scavenger concentration is lower. It is the object of the invention to design a closure that ensures not only the closing function, but also a reliable sealing function as well as highly effective deoxygenation for the preser vation function. In accordance with a further aspect of the invention, this is, moreover, to be ensured in particular for a one-part closure for a container in which food is stored, especially -3 bottles of beer, which closure is easy to manufacture, can be sealed reliably and is character ized by an effective preservation function for perishable food. As specified by the invention, this object is solved by the features of claim 1. The produc tion of a one-part closure is solved by the characterizing features of claim 3. The invention does, however, also relate to the provision of a sealing material or liner for a closure, by means of which effective deoxygenation, in particular, and a good sealing function are en sured. In this respect, the solution is arrived at from the features of the characterizing por tion of claim 2. The invention is characterized in that the sealing face of a closure is increased relative to its effective area by providing it with an active surface that is larger than an essentially planar or smooth sealing face. Such an enlargement of the effective sealing face can particularly be brought about by erosion of the sealing face or as a result of the fact that the sealing face or sealing element is provided with projections and/or grooves for the purpose of enlarging the active sealing face. This produces a coarsely structured surface with a larger effective con tact surface and hence exhibiting greater absorption of oxygen. The closure, particularly for use in beer bottles, is advantageously made as a single part from a material that contains a substrate and an oxygen.scavenger. Any oxygen scavengers known for example from the aforementioned prior-art document can be used as an oxygen-scavenging material. Nonetheless, the invention does not aim to be restricted to these substances, but is intended to cover all possible suitable oxygen scav engers. Deoxygenation can be based for example on absorption, adsorption or other chemi cal reactions. The sealing face in contact with the interior of the container is provided with an active surface that is larger than the active surface of an essentially planar or smooth sealing face, thereby providing a larger active area that deoxygenates the inside of the bot tle. In this way, the effectiveness of oxygen absorption is increased while maintaining a constant amount of oxygen scavenger in the substrate. The amount of soft oxygen scavenger materials present in the closing cap material can as a result be lowered at least to such a considerable extent that the strength of the closure, especially its stress-cracking resistance, -4 is enough to ensure a reliable closing function. All the same, this measure enables the amount of oxygen scavenger material to be chosen such that on account of the enlarged ac tive oxygen-scavenging surface area, the container can be deoxygenated to such an extent as to meet the desired preservation requirements. The contradictory demands that are raised in order to safeguard the closing, sealing and preservation functions can thus be complied with. The size of the active surface of the sealing face and the amount of oxygen scavenger mate rial are chosen such as to take account of one another. In addition, there is the advantage that the one-part design makes it possible to produce the closure in a single injection moulding process. There is then no need for the second injection-moulding process entailed by conventional closures or for the process of fitting the sealing washer and closing cap to gether. As a result, production is simplified and there are advantages in terms of waste dis posal and recycling. In accordance with a further independent idea, the sealing face is formed by a separate seal ing element, in particular a sealing washer arranged within a closure, or the sealing face can be formed by a sealing liner moulded onto the closure. This makes it possible to transfer the advantages of the inventive idea of an enlarged active sealing surface of a sealing element to other, especially conventional, closures or closing caps as well. In this instance, the sealing element is provided with an oxygen scavenger, but has a much larger active surface, thereby increasing deoxygenation and hence optimizing the preservation function. This is, more over, achieved by means of a liner that is separately moulded on a closure. Independent pro tection for such a sealing element, particularly in the form of a sealing washer or liner, is claimed as part of this invention. The enlargement of the sealing face can particularly be brought about in that the active sur face is formed at least in part by coarse erosion of the sealing face. In this context, coarse erosion means that the sealing face will have been roughened coarsely. The active surface of the sealing face may exhibit a structure having projections and/or grooves so as to increase the active surface. The shape and dimensioning of the projections and grooves can be chosen such that the size of the active surface area is enough to comply with the preservation function.

-5 The enlarged active surface is preferably formed by recesses in the sealing face. This meas ure can be particularly effective because the depth and elongation of the recesses can be chosen in such a way as to obtain the necessary active surface. The enlarged active surface of the sealing face can also be formed by a wavy or rib-like structure within the sealing face. The active surface of the sealing face is preferably 2 to 3 times larger than an essentially smooth or planar sealing face. The closure is preferably made of plastic. In this regard, a polymer composition is normally used as a substrate. Polyethylene (PE) can be chosen, for example, as a substrate. On the one hand, polyethylene can reliably ensure the sealing function, on the other hand it has the strength needed to close the bottle. In particular, use is made of an oxygen scavenger that is activated by water or water vapour. Furthermore, the closure material may contain a catalyst to increase the oxygen scavenger's rate of reaction with the oxygen. The amount of oxygen scavenger present in the closure can particularly be chosen such that the closure has not only the strength needed to ensure the closing function, but also the oxy gen-scavenging capacity necessary for ensuring the shelf-life requirements to be met by the food. The one-part closure is usually designed as a rotary closure. In addition, however, the inven tion can in principle be applied to jettisonable closures, such as crown caps, or twist-off crown caps.

-6 The closure preferably has a tamper-evident band so as to fulfil the warranty function. The closure may have an inner seal that presses against the container's inner wall whenever the container is closed. Moreover, the closure may comprise a tapered seal which makes contact with the container's upper edge at the transition to the inside of the container whenever it is closed. The closure may also have a cap wall with a circular seal that makes contact with the con tainer's outer wall whenever the container is closed. Additionally, the closure may have a pull-off tamper-evident band in order to comply with the warranty function. A method of manufacturing an aforementioned closure comprises the following steps: pro ducing a mixture that comprises a substrate and an oxygen scavenger; and producing the one-part closure from the mixture by means of injection moulding, wherein the active sur face of the closure's sealing face has a coarsely eroded form. In contrast to production proc esses for conventional closures, this method dispenses at least with the steps of manufactur ing a sealing washer and fitting the sealing washer and closing cap together. This reduces the time and effort involved, not to mention the costs. Further features and benefits of the invention are arrived at from the following exemplary embodiment. The figure shows a sectional view of an inventive closure for a bottle of beer. An inventive closure I for a bottle, which is. made either of glass or plastic, is depicted in the figure. An internal thread 9 is formed in the lateral wall 2 of the closure cap. The end wall 3 of the closure 1 has a sealing face 4 that is in contact with the interior of the sealed bottle.

-7 Provided on the end wall 3 is a circular inner seal 5 protruding towards the open end and spaced apart from the cap wall 2. The seal's outer diameter tapers in the region of its free end. Towards the cap wall 2 there is formed a bead 5a that makes contact with the inside of the neck of the bottle whenever the bottle is closed. The bead 5a encompasses the region 5b that tapers in the outer diameter. In contrast, the inner face 5c of the inner seal 5 runs essentially perpendicular to the sealing face 4. On that side which faces the cap wall 2, the inner seal 5 runs roughly in arcuate fash ion towards the bead 5a, i.e. it merges with the bead 5a, from where it in turn tapers roughly in a straight line in the outer diameter. The bead 5a is dimensioned or extends towards the cap wall 2 in such a way that in a screwed-on state, the inner seal 5 or the bead 5a is pressed, at a predefined contact pressure, against the bottle's inner wall in the region of the bottle mouth. The figure also shows that in the region between the cap wall 2 and inner seal 5, the end wall 3 has a circular tapered seal 6 projecting from the end wall 3 and tilting towards the inner seal 5. The tapered seal 6 is positioned and dimensioned such as to make contact, in a screwed-on state, with pre-tension with the radius or inner edge of the neck of the bottle or the transition to bottle mouth. This tapered seal 6 tapers towards its free end. In addition, it is shown that in the upper region, i.e. in the region just before the transition to the end wall 3, the cap wall 2 has a roughly radially or inwardly projecting circular seal 7 for making contact with the outer wall of the neck of the bottle. The seal 7 is dimensioned such as to make contact, in a screwed-on state, with pre-tension with the bottle's outer wall. Closing caps which can be used to seal beverage bottles or similar containers must meet different requirements. First, the beverage bottles or containers must be sealed in such a way that the beverage contained therein cannot escape from the container in a sealed or inter locked state. If the containers that are to be sealed are beverage bottles, this requirement will then be determined by the viscosity of the liquid. If, moreover, a pressurized gas, such as carbonic acid, has been added to the beverages contained in the bottles, the seal must, in -8 addition, be gastight so as to stop the gas from escaping from the bottle. What is more, rela tively high internal pressures may be produced in beer bottles, thus making a reliable and secure seal necessary in order to stop gas from escaping. The invention achieves adequate sealing in the event of any internal pressures that arise and should any external loads be ex erted. Sealing can, furthermore, be brought about by providing a structure that has undulatory ribs; this structure presses the sealant selectively against the upper edge of the container, thereby producing a sealing zone in which the sealant is pressed under high pressure against the up per edge of the container. Additionally, a circular tamper-evident band 8 that adjoins the cap wall 2 and which can be pulled off at a predetermined breaking point is provided in accordance with the figure. This tamper-evident band 8 has for example two predetermined breaking points that face oppo site one another so that when it is pulled off, the tamper-evident band 8 splits into halves of roughly equal length. The closing cap in accordance with the invention has a one-part design as a whole. The clo sure is made of a material that contains polyethylene as a substrate, and an oxygen scaven ger. The one-part design produces advantages in terms of manufacturing and waste disposal. As depicted schematically in the figure, the sealing face 4 is coarsely eroded so as to enlarge, as compared to an essentially planar or smooth sealing face, the active surface area that is intended to deoxygenate the inside of the bottle. In this instance, the enlargement of the active surface area was brought about by means of a plurality of grooves within the seal ing face. By suitably choosing the amount of oxygen scavenger present in the substrate and as a result of the coarsely eroded and hence enlarged sealing face, the contradictory de mands of a high-strength closing cap for the closing function and a high oxygen-scavenging effect for the preservation function can be fulfilled at the same time. The amount of oxygen scavenger within the closure material can be reduced considerably without diminishing the oxygen-scavenging capacity too much. The closing cap is simultaneously lent the necessary resistance to cracking so as to ensure a reliable closing function. This makes it possible to -9 design the closing cap as a single part, thus making the cap easier to manufacture. Besides, material costs can be saved by reducing the relatively more expensive oxygen scavenger. As far as the aforementioned purposes are concerned, it is usually enough to enlarge the active surface area by two to three times. It may be sufficient to roughen only part of the sealing face. In addition, the inner face 5c and/or the tapering region 5b of inner seal 5 can equally be eroded. In this way, a maximum active surface area that deoxygenates the inside of the bot tle can be obtained. The active surface area can be eroded in a variety of ways. What is crucial is merely that the active surface should be larger than an essentially non-roughened surface. The surface area can be provided for example with recesses, undulations, ribs, lamellae, grooves or projec tions etc. The subject matter of the application is not restricted to closures for sealing bottles of beer. On the contrary, the closures are suitable for all manner of container, for example for any type of food container. Moreover, the closing cap in accordance with the invention is suit able both for re-usable bottles and for disposable ones. The closures are suitable, for in stance, for beer bottles that are sold in a sealed six-pack format. The invention can, further more, be used not only in conjunction with rotary closures, but also with crown caps, e.g. twist-off crown caps orjettisonable caps.

Claims

1. A closure for containers in which food is stored, in particular for beer bottles and the like, having a sealing face for sealing the container or bottle opening, characterized in that said closure (1) is formed of a substrate and an oxygen scavenger, said sealing face (4) being provided with an active surface that is larger than an essentially planar respec tively smooth sealing face.

2. The closure in accordance with claim 1, characterized in that said sealing face is formed by a separate sealing element, in particular a sealing washer arranged within said closure, or by a moulded sealing liner.

3. The closure in accordance with claim 1, characterized in that said sealing face (4) is integrally formed with said closure, in particular said closure material.

4. The closure in accordance with any one of claims 1 to 3, characterized in that said active surface is formed at least in part by coarse erosion of said sealing face (4).

5. The closure in accordance with any one of claims 1 to 4, characterized in that said sealing face (4) has projections and/or grooves in order to enlarge said active surface.

6. The closure in accordance with any one of the preceding claims, characterized in that said enlarged active surface is formed by recesses within said sealing face (4).

7. The closure in accordance with any one of the preceding claims, characterized in that said enlarged active surface is formed by a wavy or rib-like structure within said seal ing face (4).

8. The closure in accordance with any one of the preceding claims, characterized in that said active surface of said sealing face (4) is 2 to 5 times larger than an essentially smooth or planar sealing face.

9. The closure in accordance with any one of the preceding claims, characterized in that said closure (1) is made of plastic. - 11

10. The closure in accordance with any one of the preceding claims', characterized in that said substrate is a polymer composition.

11. The closure in accordance with any one of the preceding claims, characterized in that said substrate is polyethylene (PE).

12. The closure in accordance with any one of the preceding claims, characterized in that said oxygen scavenger is activated by water or water vapour.

13. The closure in accordance with any one of the preceding claims, characterized in that the closure material further contains a catalyst to increase said oxygen scavenger's rate of reaction with oxygen.

14. The closure in accordance with any one of the preceding claims, characterized in that the amount of oxygen scavenger is chosen such that said closure (1) has the strength needed to ensure the closing function and the oxygen-scavenging capacity necessary for ensuring the shelf-life requirements to be met by the food.

15. The closure in accordance with any one of the preceding claims, characterized in that said closure (1) is designed as a rotary closure.

16. The closure in accordance with any one of the preceding claims, characterized in that said closure (1) has an inner seal (5) that presses against the container's inner wall whenever the container is sealed.

17. The closure in accordance with any one of the preceding claims, characterized in that said closure (1) comprises a tapered seal (6) that makes contact with the container's upper edge at the transition to the inside of the container whenever the container is closed.

18. The closure in accordance with any one of the preceding claims, characterized in that said closure (1) has a cap wall with a circular seal (7) that makes contact with the con tainer's outer wall whenever the container is closed. - 12

19. The closure in accordance with any one of the preceding claims, characterized in that said closure (1) has a pull-off tamper-evident band (8).

20. A method for manufacturing a closure in accordance with any one of claims 1, 2 or 4 to 19, said method comprising the steps of: - producing a mixture comprising a substrate and an oxygen scavenger; and - producing a one-part closure from the mixture by means of injection moulding, said active surface of said sealing face (4) of said closure being formed by coarse erosion.