WATER-BASED INK COMPOSITION FOR FINE POINTED BALLPOINT PEN AND FINE POINTED BALLPOINT PEN

摘要

Provided is a water-based ink composition for a fine pointed ballpoint pen characterized by blending an ink composition comprising at least water, a colorant and a water soluble solvent with at least one kind of ultra fine particles selected from the group consisting of alumina, titanium oxide, silica, silicon carbide and tungsten carbide each having an average particle diameter of less than 0.1 µm, wherein a blending amount of the ultra fine particles is 0.002 to 2 % by weight based on the ink composition, particularly preferably an ink composition having a viscosity of 50 to 2000 mPa⋅s (25° C) which is measured at 1 rpm by means of a corn and plate type rotational viscometer (1°34'R24 corn). Further, provided is a fine pointed ballpoint pen having a ball of a diameter of 0.4 mm or less, filled with the water-based ink composition described above.