PLASTIC BOTTLE AND PREFORM

摘要

PROBLEM TO BE SOLVED: To provide a plastic bottle and a preform that have a partially thinned mouth portion and thus can reduce the entire weight without changing the shape of an existing cap.SOLUTION: A plastic bottle 10 includes a mouth portion 15 that has: an external thread 13 having an upper end 13a and a lower end 13b; a coupler 16 disposed below the external thread 13; a support ring 17 disposed below the coupler 16; and a concave ring surface 18 formed on the external surface between the coupler 16 and the support ring 17. A bottle body 11 is provided below the mouth portion 15. The relationship 1.125≤d/d≤1.165 holds where the crest diameter that is the outer diameter of the external thread 13 is dand the root diameter that is the inner diameter of the external thread 13 is d.