Synthetic resin container closure

A synthetic resin container closure to be applied to a container in which an external thread and an engaging jaw portion located below the external thread are formed on an outer peripheral surface of a mouth-and-neck portion, the synthetic resin container closure comprising:

• a body which has a top panel wall, and a cylindrical skirt wall extending downwardly from a peripheral edge of the top panel wall, and in which an internal thread to be screwed to the external thread is formed on an inner peripheral surface of the skirt wall;
• and
• a cylindrical tamper evident bottom portion which is connected to the skirt wall of the body via a plurality of breakable bridge portions arranged with spacing in a circumferential direction, and in which an engaging means to be engaged with the engaging jaw portion is disposed on an inner peripheral surface of the tamper evident bottom portion,
• the engaging means being composed of a plurality of engaging pieces disposed with spacing in the circumferential direction and extending upward and radially inwardly from a base end connected to the tamper evident bottom portion, or an annular engaging piece extending continuously in the circumferential direction and extending upward and radially inwardly from the base end connected to the tamper evident bottom portion,
• a protruding piece protruding downward being disposed on the skirt wall of the body, and
• an unbroken connecting piece being disposed to connect the skirt wall of the body and the tamper evident bottom portion and to allow the body to be moved upward with respect to the tamper evident bottom portion,
• wherein an extending portion is formed at the engaging piece at least in an angle region where the protruding piece is present, the extending portion being located between the engaging jaw portion of the mouth-and-neck portion and the tamper evident bottom portion in a state where the synthetic resin container closure is mounted on the mouth-and-neck portion, and an interlock means is formed on an outer surface of the extending portion,
• an interlocking means to be interlocked with the interlock means is formed on an outer surface of the protruding piece, and
• when the body is rotated in an opening direction to unseal the mouth-and-neck portion sealed with the synthetic resin container closure mounted thereon, the breakable bridge portions are broken, so that the body is moved upward from the tamper evident bottom portion, and when the body is pivoted about a predetermined site of the unbroken connecting piece by more than a predetermine angle with respect to the tamper evident bottom portion, a lower part of the protruding piece elastically passes over the extending portion until the interlocking means of the protruding piece is interlocked with the interlock means of the extending portion.