Writing implement using liquid ink, in particular a solvent-based ink

Abstract

A liquid ink writing implement comprises a body whose rear portion constitutes a reservoir for containing an ink, a transfer rod whose rear end opens out into the reservoir and whose front end projects out from the body and forms a writing tip, and a buffer reservoir in contact with the transfer rod. The ink has a surface tension lying in the range 21 of mN/m to 25 mN/m, and is intended for use on a non-absorbent media made of metal or of plastic. The surface tension of the material constituting the buffer reservoir is less than that of the ink by a predetermined difference which is preferably equal to or less than 4 mN/m, thereby enabling the buffer reservoir to absorb and give back any excess ink coming from the transfer rod by capillarity in the event of variation in the pressure inside the reservoir. The surface tension of the material of the buffer reservoir has been lowered by depositing an agent, whose surface tension is less than that of the ink but within the predetermined difference, e.g. fluorine, polysiloxane, or a fluorine-containing resin.

Dependencies are inferred from the claim text.