Patent application title: CLOSURE WITH SAFETY FEATURE
Gerry Mavin (Northumberland, GB)
Timothy Stephenson (South Yorkshire, GB)
IPC8 Class: AB65D5116FI
Class name: With condition responsive vent or valve responsive to pressure one-way, outwardly venting pressure relief valve
Publication date: 2010-11-11
Patent application number: 20100282747
Disclosed is a closure for a container wherein the container may
experience an excessive buildup of internal pressure. The closure is
equipped with a "blowout" portion which partially separates from the
remaining closure portion if internal pressure exceeds a predetermined
limit. The separation occurs at a line of weakness. The line of weakness
is specially designed to withstand external, incidental pressure
resulting from normal handling yet fracture in a controlled fashion
should internal pressure exceed a predetermined amount. In this way
inconvenience and possible hazard is avoided from a closure completely
separating from the container from excessive pressure.
1. A closure having a top sized to cover and seal a container orifice,
wherein said top comprises a pressure relief portion, said pressure
relief portion joined to the remainder of said top through a frangible
line of weakness.
2. A closure as in claim 1 wherein said line of weakness is designed to resist external pressure on said pressure relief portion and to fracture in a controlled fashion in response to pressure on said pressure relief portion exceeding a predetermined value.
3. A closure as in claim 2 wherein said line of weakness varies in strength along its length.
4. A closure having a top and a skirt depending from a peripheral edge of the top and further comprising a breakaway portion joined by a line of weakness to an annular peripheral portion defined on the top, wherein the breakaway portion includes a first extending portion extending towards the annular peripheral portion and wherein the annular peripheral portion includes a second extending portion extending towards the breakaway portion, the first and second extending portions overlapping to define an overlapping region.
5. The closure of claim 4 further comprising: a seal plug depending from a bottom surface of the top, the seal plug shaped to form a hollow cylinder and having a smooth external surface intended to seal against an internal surface of a container neck.
6. The closure of claim 5, wherein the first extending portion of the breakaway portion overlaps on top of the second extending portion of the annular peripheral portion, wherein pressure applied downwards on the top causes the seal plug to press against the internal surface of a container neck placing the overlapping region in compression an insufficient force for tearing the line of weakness, whereas pressure applied upwards on the bottom surface places the overlapping region in tension such that the line of weakness is capable of tearing.
7. The closure of claim 4, wherein the breakaway portion has a disk shape.
8. The closure of claim 4, wherein the line of weakness extends as an arcuate line of weakness.
9. The closure of claim 4, wherein the line of weakness extends in an arc less than 360 degrees.
10. A closure having a top, a skirt depending from a peripheral edge of the top, and a seal plug depending from a bottom surface of the top, the seal plug shaped to form a hollow cylinder and having a smooth external surface intended to seal against an internal surface of a container neck, the closure further comprising:a breakaway portion joined by a line of weakness to an annular peripheral portion defined on the top, wherein the breakaway portion includes a first extending portion extending towards the annular peripheral portion and wherein the annular peripheral portion includes a second extending portion extending towards the breakaway portion, the first and second extending portions overlapping to define an overlapping region,and wherein the first extending portion of the breakaway portion overlaps on top of the second extending portion of the annular peripheral portion, wherein pressure applied downwards on the top causes the seal plug to press against the internal surface of a container neck placing the overlapping region in compression an insufficient force for tearing the line of weakness, whereas pressure applied upwards on the bottom surface places the overlapping region in tension such that the line of weakness is capable of tearing.
11. The closure of claim 10, wherein the line of weakness extends as an arcuate line of weakness.
CROSS REFERENCE TO RELATED APPLICATIONS
The present application claims priority to U.S. Provisional Application 61/021,933 filed Jan. 18, 2008.
FIELD OF THE INVENTION
The present invention relates to a closure for containers and to closures in combination with neck structures, and in particular to closures suitable for applications that require safeguard against accidental displacement of closures as resulting from excessive internal pressure within the container void or head space, such as the closure being propelled, or acting as a projectile, away from the container.
In recent years with the increase in non-carbonated beverages and still water drinks, the use of flat closures with mechanical sealing features has become commonplace.
Since the containers do not contain carbonation, inert gas is often "dropped" into the containers to maintain stability. The containers include inert gas with internal pressures up to 2 bar(g). Inert gas is used because it limits the ingress of external gases preventing the container from collapsing and assures product life. The inert gas further provides for a cost effective environmentally acceptable package.
When the containers can be filled under sterile conditions an aseptic container is created. The aseptic container, when correctly sealed, provides an extension of the product's shelf life without the need to add preservatives or inhibitors to the product. In other cases, fresh food products lacking preservatives may be packaged under non-aseptic conditions but maintain their integrity for some period, often under refrigerated conditions. However, if the defined shelf life conditions are violated through improper stock rotation or refrigeration, product spoilage may lead to closure blow-off or "missiling". Such unintended closure displacement is clearly both inconvenient and potentially hazardous.
Conventionally, the closure is constituted by a main body comprising a skirt or neck ring, of various diameters, which must be applied onto the neck of a container. In most cases the skirt or neck ring is threaded although this is not a requirement. Plug or snap fitting closures may also be considered. A sealing device attached to the inner face of the closure suitably comes into contact the upper face or inner wall of the neck to form a seal.
The main body of the closure is normally initially screwed onto the neck of the container. However, in the case of familiar snap-on/screw-off or snap-on/snap-off closures, initial application may be achieved with a straightforward axially directed push.
As a guarantee of the integrity of the container, the container can be provided with a form of tamper evidencing means well known in the art. The means include breakaway bands, tear tabs and the like which separate from the main closure body on initial removal of the closure from the container neck.
The above-described closures normally effectively perform their primary intended task. However, on occasion they suffer the drawback that the integrity of seal is so effective pressure is able to build up as a result of, for example, product reaction (fermentation) or increase in gaseous pressure within the contained void this as a result of expansion due to temperature or overfilling.
This drawback has been dealt with typically, by installing a mechanism to assist the release (venting) of excessive pressure past the sealing mechanism(s) to atmosphere by permitting passage of said gas or product between the closure and neck finish. An example of such a device is disclosed within U.S. Pat. No. 7,314,146, the entire contents of which are herein incorporated by reference. Unfortunately, such current venting systems occasionally plug either through evaporation or with solid ingredients, such as pulp, which may be present in the product. Any such plugging thwarts the effectiveness of the intended venting mechanism.
DISCLOSURE OF INVENTION
The present invention thus includes an embodiment to provide a closure for containers of liquids which solves some or all of the above-mentioned drawbacks.
An embodiment of the present invention further provides for a closure that can be easily sterilized internally with sanitizing liquid according to known methods. An embodiment of the present invention further provides for a closure that is able to operate with pressures greater than 0.5 bar(g) and less than that associated with carbonated products of the order of 3 bar(g) without leakage or premature opening of the upper closure.
A further embodiment of the present invention further provides for a closure that allows repeated opening and re-closing.
Yet another embodiment of the present invention provides for a closure that is able to give the user assurance, at the time of purchase, of the integrity of the container, such that the user is certain that the container has never been opened before.
Another embodiment of the present invention further provides for a closure that can be manufactured at a cost, which is appropriate for single use applications.
Another embodiment of the present invention provides a breakaway shaped disc located within the sealed area of the closure preferably though not necessarily in the portion forming the upper section of package. (roof of cap)
A further embodiment of the present invention provides a disc with a frangible connection able to displace more easily in an outward direction as compared to inwardly in the event of excessive internal pressure thereby avoiding incidental puncture during consumer handling.
A further embodiment of the present invention is that the breakaway disc should be larger than the depending opening along sufficient land so as to inhibit accidental breakage of said frangible connection in a downward direction.
A further embodiment of the present invention is that the frangible connection should be interrupted in form adequately to maintain attachment of a breakaway disc to the primary closure thus avoiding choking risk and full dislodgement of the disc.
A further embodiment of the present invention is that frangible line can be so formed in the top face so as to create a pleasing shape in the form of a decorative logo or wording.
A further embodiment of the present invention is that the frangible line defining a breakaway portion is able to be tapered or graduated in form, thereby allowing gradual and increasing breakage as pressure increases and limiting the risk of product plugging.
A further embodiment of the present invention is that the invention can be used in aseptically clean packages without risk to the standard pack seal integrity.
A further embodiment of the present invention is that is can be used in conjunction with primary venting mechanisms and in this case of use act only as a final safeguard against entire blow-off of the closure from the neck finish.
BRIEF DESCRIPTION OF DRAWINGS
The accompanying drawings which are incorporated in and form a part of the specification illustrate preferred embodiments of the present invention and, together with the description, serve to explain the principles of the invention. In the drawings:
FIG. 1 is a side elevational view in section of an embodiment of the instant invention;
FIG. 2 is an exploded view of the closure portion encircled within the circle identified as "A" in FIG. 1;
FIG. 3 is a sectional view of the structure of a conventional prior art tear line;
FIG. 4 is a perspective view from the top of an embodiment of the instant invention; and
FIG. 5 is a top plan view of the closure of FIG. 4.
DESCRIPTION OF THE EMBODIMENTS
The aspects of the instant invention will now be described in detail in conjunction with the descriptive figures. While the invention is susceptible to embodiments in many different forms, there are shown in the drawings and will be described herein, in detail, the preferred embodiments of the present invention. It should be understood, however, that the present disclosure is to be considered an exemplification of the principles of the invention and is not intended to limit the spirit or scope of the invention and/or the embodiments illustrated.
Referring now to FIG. 1, there is shown a side elevational view in section of a closure identified by numeral 10. Closure 10 comprises a top or "roof" 12 having a generally circular shape. Closure 10 further comprises a skirt or "neck ring" 14 depending from the peripheral edge of top 12. As best seen in FIG. 4, skirt conventionally is of cylindrical form although this form is not a requirement of the instant invention.
Skirt 14 has an internal surface 16 and external surface 18. In the embodiment, a pattern of gripping knurls 20 is positioned on external surface 18. Knurls 20 assure facile manipulation of closure 10 by the consumer and further facilitate rotary application of threaded closures. Closure 10 is further characterized as having container engagement structure 22 positioned on the internal surface 16 of skirt 14. In the embodiment, engagement structure 22 comprises internal helical threads 24. As is known in the art, threads 24 are complimentary to external threads (not shown) positioned of the external surface of a suitable neck finish (not shown) of a container. The internal threads 24 and mating external neck threads interengage to achieve secure and facile application, removal, and reapplication of the closure 10 relative the container. As is known in the art, other disengageable features such as snap beads may often be substituted for the complimentary thread structure of the embodiment.
Depending from closure top 12 is seal plug or valve 26. As is known in the art, plug 26 is in the form of a hollow cylinder depending from the bottom surface 28 of top 12. Plug 26 normally has a smooth, seamless external surface 30 which is intended to seal against an internal surface of a container neck (not shown).
Depending from the lower edge of skirt 14 is a tamper evidencing band 32. Band 32 is conventionally in the form of a cylinder joined to the primary closure skirt 14 through a frangible line of weakness 34. Internal locking structure 36 projects radially inwardly from an internal surface of band 32. Locking structure 36 may take many forms as is known in the art. The function of locking structure 36 is to interengage with complimentary external locking structure on a neck finish. The engagement restricts upward movement of the band 32 during initial closure removal from the container and the band separates from the main closure at the line of weakness 34 during initial closure removal.
In the embodiment of the instant invention shown in FIGS. 1, 2, 4 and 5, the closure top 12 comprises a "breakaway" portion 38 joined to an annular peripheral portion 40 through a line of weakness 42. In the embodiment shown, the portion 38 has a disk-like shape. Many other shapes are possible within the scope of the invention. For example, the shape of the "breakaway" portions may be provided within embossing features. Other geometrical shapes in the form of a logo or other decorative designs are possible. The possibility of this myriad of alternative "breakaway shapes" will be clear in light of the instant teachings. In the embodiment shown, the line of weakness 42 does not extend for a complete circle. Thus the breakaway portion 38 defined by the line of weakness 42 will not completely separate from the package to pose a potential hazard.
The structure of the top frangible line 42 is best seen in FIG. 2, a greatly exploded view of the encircled portion identified as "A" in FIG. 1. In FIG. 2, it is seen that the line of weakness 42 in the embodiment is formed by overlap of extending portion 44 of breakaway portion 38 and extending portion 46 of peripheral portion 40. The overlapping region, generally identified by numeral 48, forms a line of weakness 42 joining top portions 38 and 40. Forming the frangible line of weakness 42 in this way achieves a number of important advantages. First, it mitigates the possibility of accidental rupture of the line of weakness due to inadvertent pressure being applied from the exterior of the container. This is because the frangible line 42 fails in tension rather than compression. Inadvertent exterior pressure, generally indicated by the arrow 50 in FIG. 2, would naturally be applied primarily to the central blowout disk portion 38 of top 12, placing the frangible overlap region 48 in compression. A tensile failure caused by inadvertent external pressure applied to the peripheral portion 40 is prevented by the reinforcing structure present from the plug 26 and container neck finish. On the other hand, pressure from inside the container is exerted primarily over the surface area of the breakaway or blowout disk, thereby placing the frangible line in tension. As can be seen from the sectional view shown in FIG. 3, a conventional tear line formed using a thin score line is essentially unable to discriminate between external and internal pressure since the tear line is placed in tension in either case.
Another important aspect, of the structural geometry of frangible tear line 42 is that the actual strength of the tear line can be easily varied at any point along its length. This variable strength aspect is easily achieved by simply varying the width of the overlapping region 48. For example, a graduated tear line strength allows a gradual but predetermined release of any excessive internal pressure thereby preventing explosive pressure release.
The tear line structure embodied in FIG. 2 is achieved by overlap of extending portions 44 and 46 which are shown to be thinner than immediately adjacent portions 38 and 40 respectively. This structural arrangement allows the closure top to maintain a substantially constant thickness except for the region occupied by the tear line. This characteristic is important should secondary operations such as slitting to form frangible line 34 be employed.
Finally, the tear line structure of FIG. 2 is characterized by smooth accessible surfaces to allow facile sterilization for aseptic packaging.
Patent applications by Gerry Mavin, Northumberland GB
Patent applications in class One-way, outwardly venting pressure relief valve
Patent applications in all subclasses One-way, outwardly venting pressure relief valve