| 摘要 |
PROBLEM TO BE SOLVED: To provide a gas permeable cap for a writing utensil without obstructing gas permeability owing to invasion of narrow long foreign matter by a method wherein a cap for the writing utensil of a double cylinder structure provided wherein under a state in which an air circulating part is secured between an inner cylinder and an inner peripheral face of an outer cylinder of which front and rear are opened, a closed end shaped inner cylinder is coaxially held in the outer cylinder, gas permeability as a gas permeable cap can be certainly maintained without being blocked with ink, and further risks caused by narrow foreign matter can be avoided in advance. SOLUTION: In a double cylindrical structured cap provided wherein a closed end cylindrical inner cylinder 2 is coaxially held in an outer cylinder 1 under a state in which an air circulating part 3 is secured between the inner cylinder 2 and an inner peripheral face of a cylindrical outer cylinder 1, a necessary gap 11 communicating the air circulating part 3 between the outer cylinder 1 and the inner cylinder 2 to a front end opening part side of the outer cylinder 1 is provided between an inclined lower end of a tapered part provided to the front end opening part of the inner cylinder 2 and the inner peripheral face of the outer cylinder 1, and gas permeability is prevented from being obstructed with ink stuck to the tapered part 6 in an attaching process to an axial cylinder 4. |
