Patent ID: 8960877
Filing Date: 2015-02-24
Classification: B41J,C08K,C09D

Abstract:
1. A black ink composition comprising a self-dispersing pigment having a hydrophilic group on its surface, wherein the amount of the pigment is not less than 6% by mass of the ink composition, wherein the ink composition comprises 10% to 60% by mass of water based on the amount of the ink composition, a water soluble organic solvent, and a surfactant which is an acetylene glycol surfactant and/or a polyether modified siloxane surfactant and the amount of the surfactant is 0.1 to 3.0% by mass of the ink composition, and wherein the value, X, calculated, from the average particle diameter (nm), D50%, of the pigment contained in the ink composition, the particle size distribution width (nm), D90%−D10%, of the pigment contained in the ink composition, and the ink viscosity (mPa·s), η at 20° C., by the following Expression (I): is within a range of 2500 to 4500, and the number of coarse particles having a pigment particle size not smaller than 0.5 μm contained in the ink composition is 7.0×10 9 or less per 1 mL of the ink composition.