| 摘要 |
PROBLEM TO BE SOLVED: To prevent leakage of the contents from a PET bottle without interfering with decrease of the cycle cost relating to a leakage preventive material provided between a cap formed of polyethylene terephthalate and the pouring hole at the neck of the PET bottle. SOLUTION: A leakage preventive material discussed here is crushed under pressure between the inside bottom of a cap 2 and the pouring hole 11a at the bottle neck 11 when the cap 2 is screwed up in stopping the bottle. Then under a repellent force from the main body a1, the film a2 is put in tight contact with the pouring hole 11a, more specifically with the forward end surface 11a' of the pouring hole 11a. The film a2 is so thin that, while maintaining surface smoothness, the film changes its shape in a manner of following the shape of the forward end surface 11a' of the pouring hole 11a and is firmly put in surface contact therewith. The leakage is prevented by cooperation of the repulsive action of the main body al, change of form of the film a2 following the shape of the forward end surface 11a' of the pouring hole 11a, and the action of the film a2 to maintain the surface smoothness. |
