| 摘要 |
PROBLEM TO BE SOLVED: To seal a writing utensil by one of an internal cap or an external cap even when either one of them has an unfavorable sealability by a method wherein the internal cap which seals the periphery of the writing body, and the external cap which seals the barrel part of the writing body including the outer peripheral part of the internal cap, are provided. SOLUTION: On an external cap 13, at the approx. central inner peripheral surface in the longitudinal direction, a protuberance 9 for the engagement with an internal cap 5, and a protuberance 11 for the fitting of a writing body main body, are formed. An internal cap 5 is manufactured into a two-step cylindrical shape wherein the overall shape is an approx. bowl shape, and the outer diameter and the inner diameter of the front part 5f are smaller than those of the rear part 5b. On the outer peripheral surface part from the central part to the rear part 5b of the internal cap 5, a plurality of rib-form protruding parts 7 which go in the axial direction, are formed. On the inner peripheral surface part 5c of the internal cap 5, a tapered chamfering 5d which is tapered in toward the rear end, is formed, and the passing property and the joining property of the tip end of the writing utensil main body are improved. By the above mentioned constitution, the protuberance 11 for fitting is fitted in the body outer peripheral surface of the body part of the writing body main body, and the chamfering 5d comes into contact with the tapered part, and the writing utensil is doubly sealed. |
