Sakura Color Products Corporation

Yoshiko Yamaoka

Toshimitsu Kawasumi

Hiroshi Inoue

Satoshi Maruyama

Keiko Nakamura

Hiroyuki Fukui

Toshihiro Sawaki

The present invention is an aqueous ink composition for ball-point pen comprising an aqueous ink mixture containing at least a pigment or colored polymer emulsion, a dispersant, a water-soluble organic solvent and water, and a compound of the general formula (1). Examples of such ink compositions include a sodium salt of polyoxyethylene alkyl ether phosphate monoester a sodium salt of polyoxyethylene alkyl ether phosphate diester, a triethanolamine salt of polyoxyethylene alkylphenyl ether phosphate monoester, triethanolamine salt of polyoxyethylene alkylphenyl ether phosphate diester. The aqueous ink composition provides a lubricity effect of rotating a ball smoothly when it is used for a ball-point pen. Therefore, the aqueous ink compositions are superior in lubricity and hence are free of clogging at the tip of ball-point pen even after prolonged use: ##STR1## wherein R 1- is -OX or R 2 -O-(CH 2 CH 2 O)n-; R 2 is C 8 to C 18 which is alkyl group, alkenyl group, or alkylphenyl group;

Aqueous ink composition for ball-point pen

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.

Aqueous ink compositions and methods for their production

An aqueous ink composition for ball-point pen is provided which includes an aqueous ink mixture containing at least a coloring agent, a dispersant, a water-soluble organic solvent and water, and a compound of the general formula (1): ##STR1## wherein R1 and R2 represent OH and/or HO(CH.sub.2 CH.sub.2 O)n and/or ##STR2## where Y is CmH2m+1 (m is an integer of not larger than 4); and X represents an alkali metal salt, amine salt or alkanolamine salt. The aqueous ink composition is excellent in lubricity, wear resistance of ball seat, writing touch and long-term stability, and is less liable to feather on paper.

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Osaka, Japan

Yoshiko Yamaoka