Patent ID: 9169413
Filing Date: 2015-10-27
Classification: B41J,C09D

Abstract:
1. An ink comprising: a self-dispersion pigment in which a phosphonic acid group is bonded directly or through another atomic group to the surface thereof; a polyurethane polymer; and at least one compound selected from the group consisting of 2-imidazolidinone, 1,3-dimethyl-2-imidazolidinone, 2-pyrrolidone, N-methyl-2-pyrrolidone, and 1,2-alkanediol, wherein a surface charge amount of the self-dispersion pigment is from 0.25 mmol/g to 0.42 mmol/g, wherein the polyurethane polymer has units respectively derived from a polyisocyanate, a polyether polyol having no acid group, and a diol having an acid group, and wherein the mass ratio of (a) the content (% by mass) of the at least one compound based on the total mass of the ink and (b) the content (% by mass) of the polyurethane polymer based on the total mass of the ink is 2.0 times or more.