Deep-drawn preformed closure for the hermetic sealing of a can or similar container

Claim 1

A deep-drawn preformed closure element adapted for the hermetic sealing of an opening of a can or similar container having a can body having a top and said opening in said top, the wall of which can body is lined on its inside surface with a protective coating which is rendered thermo-glueable upon heating, and said closure element being in a state ready for introduction and gluing into said opening of said can top and essentially consisting of a membrane deep drawn from an aluminum foil or similar sheet material, and being adapted for serving as a warranty seal for said container, said membrane comprising: (a) a flat part, adapted for covering the top opening in said can body, (b) an annular collar part, joined to the periphery of said flat part, said membrane bearing at least on the side of said collar part destined to contact said can body, a coating which is rendered thermo-glueable upon heating, whereby said collar part is adapted for being glued to the thermo-glueable coating of the inside wall surrounding the top opening of said can body, (c) a peripheral rim-covering part, joined to the periphery of said collar part away from said flat part, and destined for covering the rim of said can about said can top opening, and (d) collar part rupturing line means comprising at least one endless reduced thickness portion in said collar part, extending all the way thereabout, in a zone of said collar part extending parallel to the peripheral junction of said flat part with said collar part and intermediate said last-mentioned junction and the peripheral junction of said collar part with said rim-covering part, for separating the closure element into two parts, during assembly of the closure element to the can, through tensioning of said collar part in a direction substantially perpendicular to said flat part, and inwardly toward the can interior, and heating the same, whereby an upper portion of said collar part, above said collar part-rupturing line means, becomes thermo-glued to the underlying protective coating of the can body wall in an upper contact zone of the latter, and a lower portion of said collar part, below said collar part-rupturing line means, becomes thermo-glued sealingly to the underlying protective coating in a second, lower zone of the can body wall, while leaving a circumferential zone of said protective coating intermediate said first and second contact zone thereof uncovered and intact.