| 摘要 |
<p>A thermoplastic closure (10) for fitment to a container for packaging product capable of producing internal container pressure, e.g., carbonated beverages, is disclosed. The closure (10) comprises a top wall (12) and an annular sidewall (14) downwardly depending from the top wall (12). An extended closure thread (20) on the inside surface of the sidewall (14) which requires the user to make two turning motions to achieve removal is provided for cooperation with the container neck thread (42) to achieve fitment of the closure (10) to the container neck (40). A sealing system (22) adjacent the top wall of the closure provides sealing of the closure to the container. Venting structure is provided on the closure for venting of pressurized gas from the container upon loss of the seal when the closure is rotated to remove it from the container. A rigidifying means (34) having a perpendicular height less than the perpendicular height of the closure thread is provided at the point of traverse of the venting groove (26) and the closure thread (20). A heat-shrinkable tamper-indicating means (16) is attached to the lowermost edge of the sidewall of the closure (10). Application of heat to the tamper indicating means (16) causes it to shrink towards the container and to a point of interference with a container flange (48). A heat sink structure (30), such as an annular bead about the outside surface of the sidewall (14), is utilized to keep the sidewall at a temperature below that temperature which would normally cause the sidewall (14) to shrink.</p> |
