| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an aqueous pigment dispersion and an ink composition, excellent in dispersing property and dispersion stability, less in the increase of particle diameter or elevation of viscosity even under a long period of standing under a high temperature, excellent in preservation stability and obtaining a high image density. <P>SOLUTION: This aqueous pigment dispersion consisting at least of (a) a quinacridone-based pigment, (b) a quinacridone-based compound having a substituent including a phthalimide skeleton, (c) a styrene-acrylic resin, (d) an alkali metal hydroxide, (e) a humectant and (f) water is provided by having 1-20 mass% ratio of the (b) occupying in the total of the (a) and (b), the (c) consisting at least of styrene, acrylic acid and methacrylic acid as constituting monomers having ≥60 mass% styrene monomer component based on the total monomer components, ≥95 mass% total of each of the monomer components of the styrene, acrylic acid and methacrylic acid based on the total monomer components and 7,500-30,000 weight-average molecular weight of the resin, and the ink composition by using the same dispersion is also provided. <P>COPYRIGHT: (C)2005,JPO&NCIPI |
