SYNTHETIC RESIN CAP

To provide a synthetic resin cap that prevents the cap from falling off or being lost, facilitates grasping when the cap has been opened, and can prevent the cap from coming into contact with cheeks or nose of a drinker when drinking.SOLUTION: A synthetic resin cap of the present invention includes a tamper-evident band, and a cap body including a fixed rib projecting radially outward with respect to a skirt wall at the skirt wall. The fixed rib comprises a projection portion at least including an intermediate step portion extending radially outward, a shoulder portion that bends downward at an outer side end portion of the intermediate step portion, and a bending portion having a diameter that is continuously and gradually reducing downward from the shoulder portion. A posture of the cap body at the time of opening is maintained since a side surface of a container mouth portion and the projection portion come into contact with each other after a jaw provided on the container mouth portion slides along the bending portion at the time of opening the cap and an upper surface of a side extending portion that is provided below the container mouth portion and extends in the radial direction and a top surface plate come into contact with each other.SELECTED DRAWING: Figure 1 【課題】キャップの落下や紛失を抑制するとともに開栓が完了したことを容易に把握しつつ飲用時に飲用者の頬や鼻などにキャップが接触することが抑制可能な合成樹脂キャップを提供する。【解決手段】本発明の合成樹脂キャップは、タンパーエビデントバンドと、スカート壁よりも径方向外側へ突出した固定リブをスカート壁に備えたキャップ本体と、を含み、固定リブは、径方向外側へ延びる中間段部と、中間段部の外側端部で下方に向けて湾曲した肩部と、肩部から連続して下方に向かって漸次に縮径された湾曲部と、を少なくとも含む突出部を有し、開栓時において容器口部に設けられた顎部が湾曲部に沿って摺動した後に容器口部の側面と突出部とが接触するとともに容器口部の下方に設けられて径方向に延長された側方延長部の上面と天面板とが接触することでキャップ本体の開栓時における姿勢が維持される。【選択図】図１