| 摘要 |
A cap 10 which has a female screw 14 in the inner peripheral surface and which is to be screwed on a port neck part 13 of a container main body 11 holding a predetermined liquid, wherein a plurality of ribs 18 radially extending astride from an inner surface of a top surface part 16 of the cap 10 to an inner surface of a peripheral wall part and integrally projecting inwards are formed on a peripheral edge part 17 of the inner surface of the top surface part 16 . A female screw 14 is a screw in the form of two threads composed of spiral mated ridges 14 a , 14 b of two threads, for example. The liquid held in the container main body 11 is, for example, a chlorine-based bleach which contains a surface active agent and a sodium hypochlorite. The mated ridges 14 a , 14 b each are 80 to 120 degrees in thread angle theta and 1 to 15% of a valley radius of the female screw 14 in thread height H.
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