| 摘要 |
PROBLEM TO BE SOLVED: To provide a cap of which damages caused by the environmental stress breakage can be effectively prevented without increasing the wall thickness. SOLUTION: This cap 10 having an internal screw 14 formed on an inner circumferential surface is screwed to a neck part 13 of a container body 12 for accommodating a surfactant, and four to ten ribs 18 having the width of 0.4 to 1.5 mm which, extended in a radial direction astride from an inner side surface of a top surface 16 to an inner side surface of a circumferential wall part 17, and integrally and inwardly protruded are provided on a circumferential edge portion of the inner side surface of the top surface 16 of the cap 10. The internal screw 14 comprises two threads, and side surfaces of the top surface side 16 of a pair of spiral projecting bars 25 to be screwed constituting the female screw 14 are rubbed against a thread bottom 27 via radiused surfaces 26 curved in a recessed bar. |
