Closure with seal member

Details Closure with seal member Closure with seal member

2002-02-20

2004-08-10

Ngo, Lien (Department: 3727)

Bottles and jars

Attachment or adjunct

Drip-catching attachment

C215S252000, C215SDIG001

Reexamination Certificate

active

06772894

ABSTRACT:

TECHNICAL FIELD
The present invention relates to linerless closures for containers. More particularly, the invention relates to such closures for use in hot fill and aseptic processes.
BACKGROUND ART
Refrigeration or preservatives are two techniques that have long been used for ensuring that foods and beverages remain suitable for consumption by consumers. Canning, where products are heated in the container over a period of time, has also long been used as a means of sterilising food products.
Hot fill and aseptic processing are two more recent techniques developed for sterilising foods and beverages. Hot fill processing is used in the packaging of beverages such as iced tea, water and fruit juice. Aseptic processing is also used in the packaging of these products and other foods including milk, soups, yoghurts and tomato products.
In the hot fill process, the containers are filled with the beverage while the beverage is still hot. This process serves to sterilise the beverage before sealing of the container. Beverages packed in this way can be shipped without the need to provide refrigeration of the containers.
Due to the temperatures involved, the hot fill process results in an expansion of the container and closure subsequent to the filling and sealing of the container. The subsequent cooling of the container typically extends over a considerable period and creates a partial vacuum inside the container due to contraction of the beverage and of the air in the void above the beverage.
Closures for sealing containers filled using the hot fill process must be able to withstand the high temperatures of the filling process and remain sealed to the container during cooling of the container after filling. Closures for hot fill application usually comprise a polypropylene cap having a top and depending skirt, with a wad or liner positioned within the cap and fixed to the underside of the top.
Linerless closures have also been proposed for use in hot fill applications. Typically, such linerless closures rely on a bore seal that extends into the bore of the end portion of the container and seals with the inside surface of the end portion of the container. By having a bore seal that extends well down the inside surface of the end portion of the container, the prospect of loss of seal due to differential shrinkage of the closure and the container during the hot fill process is minimised.
In aseptic packaging, the container is sterilised and filled with a sterile food product within the confines of a hygienic environment. The liquid food or beverage is sterilised outside the container using an ultra-high temperature process that rapidly heats, then cools the product before filling the container. Any packaging used in the aseptic process must be able to preserve the sterilisation of the package's contents until the package is opened by the end consumer. One form of aseptic packaging container presently used is a box-shaped package that is a laminate of paperboard, polyethylene and aluminium.
Certain linerless closures have been proposed for use in sealing containers for carbonated beverages. U.S. Pat. No. 5,423,444 discloses a plastic closure for a container having an externally screw threaded neck, the closure including a top portion and an internally threaded skirt. The closure has an annular sealing rib which projects downwardly from the underside of the top portion. The rib includes a first substantially cylindrical portion contiguous with the underside of the top portion and lying adjacent to or abutting with the skirt, and a second, frusto-conical, portion contiguous with the end of the first portion distal to the underside of the top portion and extending radially inwardly to a circular free edge. During threaded attachment of the closure with the neck, the second, frusto-conical, portion will be engaged by a free end of the neck and folded back towards the first, substantially cylindrical portion of the rib to form a gas tight seal between at least the outer surface of the neck of the container and the closure.
U.S. Pat. No. 5,609,263 discloses a variant of the above closure in which there is at the free end of the second portion of the rib a thick seal ring of substantially circular cross-sectional shape. The rib and the seal ring are dimensioned to engage the free end of the neck when the closure is threaded onto the neck such that when the neck is fully screwed into the closure its free end crushes the seal ring directly against the inside surface of the top portion of the closure.
Australian Patent Application No 80944/98 discloses still further variants of the closure described in U.S. Pat. No. 5,423,444. In one variant, the sealing rib of the closure has a third portion connected to the second portion at or adjacent its circular edge and extending generally in a direction away from the top portion. The third portion is substantially no thicker than the second portion and has a length longer than its thickness. On attachment of this closure to a container, the third portion is positioned between the neck of the container and the underside of the top portion of the closure.
The present invention is directed to a sealing rib arrangement for closures that further improves the sealing ability of linerless closures of the type identified in the abovemenitioned prior art particularly when used in the hot fill process.
DISCLOSURE OF THE INVENTION
According to a first aspect, the present invention relates to a closure suitable for mounting onto a container, the container having an opening defined by an end portion of the container, the closure including a top portion and a skirt portion depending from the top portion, an annular sealing rib projecting downwardly from an underside of the top portion, the rib including a first portion which is contiguous with the top portion and having an inner surface, which inner surface lies radially inwardly of the skirt portion and at least a second, frusto-conical, portion contiguous with the first portion and separated from the top portion by the inner surface of the first portion, the second portion having an upper side and an underside and extending radially inwardly to a circular edge, the inner surface of the first portion having an internal diameter relative to the external diameter of the end portion of the container to which the closure is to be attached such that during attachment of the closure with the end portion of the container, the sealing rib will be engaged by said end portion of the container so folding the second portion at least towards the inner surface of the first portion of the rib to form a seal between at least an outer surface of the end portion of the container and the closure, the closure being characterized in that there is an annular protrusion formed on the underside of the second portion and extending outwardly therefrom, the protrusion on attachment of the closure with the end portion engages the outer surface of the end portion so causing the sealing rib to be disposed over a greater area of the outer surface of the end portion of the container.
In a preferred embodiment, the annular protrusion comprises an annular ridge extending outwardly to a peak. The ridge is preferably substantially triangular in cross-section. One surface of the ridge preferably comprises an end portion engaging surface that acts to extend the area of the seal between the second portion and the container end portion on attachment of the closure to the container. The annular protrusion can be positioned about midway between the first portion and the circular edge of the second portion. In another embodiment, the annular protrusion can be positioned closer to the first position than the circular free edge of the second portion.
In one embodiment, the annular protrusion can have a resiliently flexible member extending outwardly from or adjacent the peak of the annular ridge. The flexible member, on attachment of the closure, engages the outer surface of the end portion and is flexed relative to the ridge. The flexing of the flexible me

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