Ink-storing body for writing utensil

The ink reservoir for a writing instrument as described in claim 11, wherein the resin is at least one selected from the group consisting of polyacrylonitrile, polyamide, polyvinyl chloride, polyvinylidene chloride, polyester, polypropylene, polyethylene, polycarbonate, polystyrene, an ethylene vinyl acetate copolymer and polyvinyl acetate.

An ink reservoir for a writing instrument molded from a gas barrier resin, wherein a vapor-scarcely permeable coating layer having a vapor permeability (P1) of 0.5 g/m2*atm*24 hr/25 μm or less at 40° C. and 90% RH is formed on the above reservoir for a writing instrument, wherein the ink reservoir for a writing instrument comprises a cap-like or tubular cylinder which is charged with an oil base ink and in which one end is sealed and the other end is a discharge port of the above ink;

• the above cylinder is partially charged with gas in a pressure state in addition to the above oil base ink;
• the above cylinder comprises a gas barrier resin wall, and the vapor-scarcely permeable coating layer is formed on an outside wall of the cylinder described above.