Abstract: Provided are an ink composition for an aqueous ink ball point pen, which contains modified polyvinyl alcohol and at least one selected from boric acid and salts thereof, and an aqueous ink ball point pen charged with the ink composition, wherein the boric acid and the salts thereof are preferably at least one selected from boric acid, alkali metal salts of boric acid and ammonium salts of boric acid.

Abstract: Provided is an aqueous ink composition for a writing instrument which is excellent in storage stability of particles, such as pigments, a writing property with the passage of time, followability, and quality of the drawn lines, though having a low viscosity, as compared with aqueous ink compositions prepared by using conventional thickeners and gelling agents, such as xanthan gum. The ink composition for a writing instrument described above includes an aqueous ink composition for a writing instrument containing 0.05 to 1.5% by mass of an oxidized cellulose and having a limiting viscosity of 16 mPa·s or less derived from Casson's equation, a viscosity value of 100 to 3000 mPa·s at a shear rate of 3.83 s?1 and a viscosity value of 10 to 40 mPa·s at a shear rate of 383 s?1.

Abstract: Provided is an aqueous ink composition for a writing instrument which is excellent in storage stability of particles such as pigments, a writing property with the passage of time, and quality of the drawn lines, though having a low viscosity, as compared with conventional thickener and gelling agents such as a xanthane gum. The above ink composition for a writing instrument is characterized by containing 0.05 to 1.5% by mass of an oxidized cellulose and having a limiting viscosity of 10 mPa·s or less derived from a Casson's equation.

Abstract: Provided is an aqueous ink composition for a writing instrument which is inhibited in time-dependent heterogeneity (difference in viscosity between up- and down-sides) in viscosity distribution in an aqueous ink composition containing an oxidized cellulose and which is excellent in time-dependent viscosity distribution stability. The above aqueous ink composition for a writing instrument includes, for example, an aqueous ink composition containing at least 0.05 to 1.5% by mass of an oxidized cellulose and 0.001 to 30% by mass of sugars having a weight average molecular weight of 5000 or less.

Abstract: Provided is an ink composition for an aqueous ballpoint pen making it possible to draw sharp and fine lines which are less likely to be blurred at an initial part of writing and are written smoothly and which are clear at stop, jump and sweep parts to provide beautiful characters. The ink composition for an aqueous ballpoint pen contains at least water and a colorant and having a dilatant fluid characteristic in at least a part of a region of a shear rate of 1 to 383 s?1 (25° C.).

Abstract: Provided is an ink composition for an aqueous ballpoint pen making it possible to draw sharp and fine lines which are less likely to be blurred at an initial part of writing and are written smoothly and which are clear at stop, jump and sweep parts to provide beautiful characters. The ink composition for an aqueous ballpoint pen contains at least water and a colorant and having a dilatant fluid characteristic in at least a part of a region of a shear rate of 1 to 383 s?1 (25° C.).

Abstract: Provided are an ink composition for an aqueous ink ball point pen, which contains modified polyvinyl alcohol and at least one selected from boric acid and salts thereof, and an aqueous ink ball point pen charged with the ink composition, wherein the boric acid and the salts thereof are preferably at least one selected from boric acid, alkali metal salts of boric acid and ammonium salts of boric acid.