A BUFFER RESERVOIR FOR A LIQUID-INK WRITING INSTRUMENT, AND A WRITING INSTRUMENT INCLUDING SUCH A RESERVOIR

摘要

The writing instrument includes a reservoir forliquid ink, a feed tip opening out in the reservoir, anda buffer reservoir suitable for absorbing the surplus inkin the event that the pressure in the reservoir variesand for subsequently returning it, and implemented in theform of a compact block made of an open-pore materialbased on microbeads. According to the invention, thebuffer reservoir is made up of microbeads that arehydrophobic relative to said ink and a small proportionof microbeads that are hydrophilic relative to said ink,the mixture being either uniform throughout the entirevolume of the buffer reservoir, or non-uniform with theproportion of hydrophilic microbeads being smaller in thezone immediately in contact with the surplus ink andbeing larger in the zone furthest away therefrom. Theproportion of hydrophilic microbeads preferably lies inthe range 2% to 10% relative to the total weight of thebuffer reservoir.