Bottles and jars – Closures – Cap type
Patent
1996-02-15
1998-07-21
Shoap, Allan N.
Bottles and jars
Closures
Cap type
215345, 215DIG1, 215252, 215331, B65D 4134, B65D 5300
Patent
active
057823693
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
This invention relates to closures for sealing the opening of containers. In particular, the invention provides a closure which seals the opening of a screw top container for carbonated liquid such as soft drink, but is also well adapted to seal other containers such as glass or poly(ethylene terephthalate) (PET) containers with contents at, above, or below atmospheric pressure or having gaseous components or requiring an hermetic seal.
Screw top closures have been used for some time to seal various containers. Although many screw tops include a separate sealing gasket within the closure, there is substantial advantage to be had in producing a one-piece closure which will effectively seal the container.
The present invention also relates to closures for carbonated beverage containers which are improved to prevent sudden release of the closure from the container if the closure is over-torqued.
BACKGROUND ART
It is known from the applicant's prior Australian patent specification 627746 to provide a one piece closure for a container having an externally screw threaded neck. Such closures are moulded in one piece from a resilient synthetic plastic material and comprise a top portion and a skirt depending from an underside of the top portion, the skirt having an internal surface with a complementary screw thread to that on the container. The seal between the closure and the container is provided by an annular sealing rib which projects downwardly from the underside of the top portion, the rib includes a first portion contiguous with the top portion and abutting or lying adjacent to the skirt and a second, frusto-conical, portion contiguous with an end of the first portion distal to the top portion and extending radially inwardly to terminate in a circular free edge. The internal diameter of the first portion is sized such that during threaded engagement of the closure with the neck, the second, frusto-conical portion will be engaged by a free end of the container neck and folded back against the inner surface of the first portion of the rib to form a gas-tight seal between at least an outer surface of the neck of the container and the closure.
Such closures have been found to work well on containers which are designed for single use. In such single use containers the dimensions of the neck remain within tight tolerances and the annular contact area between container and rib may be relatively small and still form a good seal between the rib and the neck of the container. When the aforedescribed closures are used on multi-trip or reusable containers, the dimensions of the neck may not be so uniform, due to distortion or chipping of the neck during use. With reusable containers, it is desirable to make the contact area between the neck and the rib larger so that there is a larger zone of sealing between the rib and the neck of the container. This raises a problem, however, because the present inventors have found that as the length of the first portion of the rib increases, the ability of the free end of the first portion to exert radially inward pressure forcing the second portion of the rib into sealing engagement with the neck of the closure decreases. Thus, merely lengthening the first of the rib has been found not to necessarily increase the effective sealing area between the rib and the neck of the container to the extent expected. It has also been determined that merely lengthening the second portion of the rib does also not necessarily increase the effective sealing area between the rib and the neck of the container. The present invention is directed to providing a means of at least ameliorating this problem.
Another problem which has been observed with closures having an integral sealing system or a separate sealing means, such as an annular gasket or a circular pad, is that, if the closure is over-torqued, the threads on the closure may override those on the container. This can allow the closure to be propelled off the container under the pressure exerted by the carbonated cont
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patent: 3067900 (1962-12-01), Kessler
patent: 3203571 (1965-08-01), Plunkett
patent: 4540102 (1985-09-01), Wiedmer
patent: 4598835 (1986-07-01), Brownbill
patent: 4739893 (1988-04-01), Zumbuhl
patent: 5004112 (1991-04-01), McBride
patent: 5050753 (1991-09-01), Trump et al.
patent: 5090788 (1992-02-01), Ingram et al.
patent: 5197621 (1993-03-01), Bartl et al.
Newhouse Nathan
Shoap Allan N.
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