Patent 7803852 was granted and assigned to Kao Corporation on September, 2010 by the United States Patent and Trademark Office.
The present invention relates to a water-based ink for ink-jet printing which not only satisfies a high optical density but also exhibits an excellent high lighter-fastness; and a water dispersion used for the water-based ink. There are provided a water dispersion for ink-jet printing containing (A) a pigment and (B) water-insoluble polymer particles produced by polymerizing an ethylenically unsaturated monomer containing 25 to 85% by weight of an aromatic group-containing monomer in the presence of a reactive surfactant; and a water-based ink containing the water dispersion.