Aqueous ink compositions and methods for their production
AssigneeSakura Color Products Corporation
InventorsToshimitsu Kawasumi, Hiroshi Inoue, Toshihiro Sawaki, Keiko Nakamura, Hiroyuki Fukui, Yoshiko Yamaoka
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Abstract
An aqueous ink is provided which comprises a coloring agent, a water-soluble solvent and water, where the amount of gas dissolved therein is less than the amount of gas present at the situation level. Where the aqueous ink composition is used for a writing instrument of ink-free type having a confined ink chamber structure, the writing instrument rarely causes ink leakage and writing defects such as uneven ink density and skips in a drawn line, even if it is allowed to stand at a high temperature or to stand for a long time.
Claims20
An ink composition comprising a coloring agent, a water-soluble solvent and water, wherein the amount of gas dissolved therein is less than the amount of gas at the saturation level.
A method of making an ink composition comprising mixing at least a coloring agent, a water-soluble organic solvent and water, and then permitting the mixture to stand at a reduced pressure for a period of time sufficient to reduce the amount of gas dissolved in the mixture to less than its saturation level.
A writing instrument comprising an ink container which includes an ink composition comprising at least a coloring agent, a water-soluble solvent and water, wherein the amount of gas dissolved in the ink composition is less than the amount of gas at a saturation level of the gas.
Dependencies are inferred from the claim text.