| CPC B65D 51/1661 (2013.01) [B65D 39/08 (2013.01); B65D 2251/20 (2013.01)] | 19 Claims |
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1. A plastic closure for fitting on to the neck of a liquid container in positively locking and sealed relationship, the neck of the liquid container having an inside, comprising
a head plate (1) provided for covering a container opening, the head plate having an edge, and
an outer seal (7) which is circumferential approximately parallel to the edge of the head plate (1) and is provided for engagement with the outside of a container neck (20) defining the container opening, and
an inner seal (5) which is circumferential within the outer seal (7) and parallel thereto and which is provided for engagement with the inside of the container neck,
wherein the outer and the inner seals (7, 5) respectively project from an inside (11) of the head plate (1) in the direction of the container neck to be covered by the head plate,
characterised in that the outer seal (7) has a weakened region (6, 6′, 6″, 16) in at least one circumferential portion,
wherein the configuration of the closure is such that the outer seal yields in the weakened region (6, 6′, 6″, 16) at a lower internal positive pressure than without the weakened region, and
wherein the plastic closure is in the form of a screw closure, wherein the screw closure (100) has the head plate (1) and a cylindrical cap skirt (2) with a female thread (3) which define an axis (50) of the closure, wherein the outer and inner seals are in the form of webs which extend circumferentially in an annular configuration at a spacing relative to the cap skirt and parallel thereto and the weakened region is restricted to an angle sector (α) measured with respect to the axis, wherein the weakened region comprises a circumferential portion of the outer seal, that is axially shortened in the angle sector (α).
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