An ink composition of the present invention includes: (a) a polymer compound which includes a repeating unit (a-1) having a partial structure expressed by the following General Formula (1), a repeating unit (a-2) which has a hydrophilic group and accounts for 8% to 25% by mass with respect to the total mass of the polymer compound, and a repeating unit (a-3) having a hydrophobic group, the polymer compound having a solubility parameter in an unneutralized state of 20.7 MPa1/2 to 23.0 MPa1/2; (b) water; and (c) a water-soluble organic solvent.
本发明的油墨组合物包括(a) 高分子化合物,其中包括具有以下通式(1)表示的部分结构的重复单元(a-1)、具有亲
水基团且占聚合物化合物总质量 8%至 25%的重复单元(a-2)和具有疏
水基团的重复单元(a-3),聚合物化合物在未中和状态下的溶解度参数为 20.7 MPa1/2 至 23.0 MPa1/2; (b)
水;以及 (c)
水溶性有机溶剂。