Open ended container closure including a flexible membrane and a rigid cap

Abstract

The invention concerns a closure for a cylindrical can (10) The closure includes a flexible member (11) of the easy-open type secured across the open end of the can (10). A rigid, screw cap (22) is screwed over the thus sealed end of the can. An annular, resilient member (24) depending downwardly from the underside of the end wall of the cap (22), engages the membrane (11) in the vicinity of the end flange (18) of the can body (10) thereby strengthening the seal between the membrane (11) and the flange (18). This advantageously permits cooking of the contents of the can with the flexible membrane (11) in situ, thereby giving rise to a can having an easy-open end, the contents of which can are cooked and sterilized using conventional processing lines.

Description

CROSS REFERENCE TO RELATED APPLICATIONS [0001] This application is a divisional of U.S. patent application Ser. No. 09 / 445,043, filed Mar. 20, 2000, the entirety of which is hereby incorporated by reference. This application also claims priority to PCT Application No. PCT / IB98 / 00825, filed May 28, 1998, and United Kingdom Patent Application No. 9711462.3, filed Jun. 4, 1997, the entireties of which are hereby incorporated by reference.BACKGROUND OF THE INVENTION [0002] This invention relates to container assemblies in particular the invention concerns such assemblies including closures known as “easy open ends”. [0003] Easy open ends are typically provided in containers that are elongate and, in the unfilled state, open at at least one end. An example of such a container is a metal can. [0004] There are two main types of easy open end. One is made from relatively thick and rigid steel or aluminum, which incorporates a “score” or weakened annular region. This weakened region allows t...

AI Technical Summary

Benefits of technology

"The invention provides a container assembly with a flexible membrane and a rigid closure system that reinforces the seal to withstand pressures generated on heating of the contents of the container. This assembly is advantageous because the resiliently deformable member continuously and evenly reinforces the seal while the rigid closure is mounted on the container. The container can be made of metal, plastic, or composite and the method allows for mass production of canned food products that are accessible via easy open ends. The invention also provides a method of packaging a food product in an open ended container with a closure system that maintains the seal during heating."

Problems solved by technology

This weakened region allows the centre part of the end to be removed, but has the disadvantages that the required opening force is relatively high, making it difficult for less dextrous people to open, and that the ruptured edge is sharp and may cause laceration injuries.

Also, many people find can opening machines difficult or impossible to use.

What is not currently possible is to use foil sealed cans in a continuous steriliser, without the use of over-pressure to counterbalance the pressure generated inside the can.

It has not previously been possible to employ the flexible membrane-type easy open ends in the continuous mass production of cans the contents of which require cooking in situ.

This is primarily because the heating process causes expansion of gases sealed within the cans, and causes further gases to evaporate from the food products, with the result that the seals between the flexible membranes and the can ends burst or, less desirably, leak in a manner that is difficult to detect.

Failures of the flexible membranes themselves (as contrasted with the seals) also occur.

This apparatus is disadvantageous, however, since its heating chamber must be sealed and pressurised during the cooking process.

Thus the overpressure cooker cannot be used for continuous mass production employing moving conveyor lines.

However, this arrangement only serves to promote a good seal between the container end and the flexible membrane before final curing of the adhesive therebetween.

This results in a smooth and well sealed membrane, but would be unlikely to prevent bursting of the seal during cooking since by that stage the strength of the seal depends entirely on the properties of the adhesive material securing the flexible membrane on the container end.

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