Refill for writing implements and writing implements using the same

Abstract

A refill for writing implements has an ink reservoir tube (1) made of resin material and formed to be a straight cylinder and a writing tip (2) attached to one end of the ink reservoir tube (1), and a value of an expression of D4−(D−2t)4 is selected to be 45 or greater, where D denotes an outer diameter of the ink reservoir tube (1) and t denotes a thickness of the ink reservoir tube (1). It is possible to secure the necessary storage amount of ink in the ink reservoir tube (1) without increasing the outer diameter thereof, and is also possible to provide a refill for a writing implement and a writing implement which allow one to keep writing comfortably without feeling of discomfort in writing.

Dependencies are inferred from the claim text.