Patent ID: 8631954

Claim:
A stopper for a neck of a container, the stopper comprising: a substantially tubular skirt centered on a longitudinal axis and adapted to be fastened around the neck; an end wall closing off one of the longitudinal ends of the skirt and extending substantially perpendicularly to the axis; a substantially annular sealing lip centered on the axis and extending inside the skirt from the inside face of the end wall; and a projecting piece in relief that interconnects the inside face of the end wall and the inside face of a peripheral portion of the lip, and that is adapted to transmit to the lip movement of the end wall relative to the skirt, so that said portion of the lip is moved radially towards the axis when the pressure inside the skirt is greater than a predetermined threshold value; wherein the projecting piece in relief occupies the entire space defined jointly by the inside face of the end wall, by the inside face of said portion of the lip and by a plane that passes through said lip portion and that intersects the inside face of the end wall along a straight line forming a chord of a circle centered on the axis.