Patent ID: 7378459
Filing Date: 2008-05-27
Classification: C09D

Abstract:
1. A pigment-dispersed ink-jet ink comprising water, a water-soluble organic solvent, a pigment, and a resinous dispersing agent, wherein the resinous dispersing agent is a vinyl copolymer having an acid value of 50 mg KOH/g or higher and a solubility of at most 3% by mass in an alkaline solution containing KOH in an amount 1.5 times as much as the acid value, and a viscosity characteristic of the ink as measured by means of a viscoelastometer satisfies the following relationship: wherein the resinous dispersing agent is a graft polymer having a hydrophobic main chain and a hydrophilic side chain, in which the weight average molecular weight of the side chain is 300 to 2,000, and the weight average molecular weight of the graft polymer itself and the weight average molecular weight of the side chain satisfy the following relationship: wherein the proportion of hydrophobic monomers making up the main chain is 60% by mass or higher based on the mass of all monomers forming the main chain.