| 摘要 |
PROBLEM TO BE SOLVED: To provide ink compositions for forming an image excellent in solvent resistance and adhesion to a record medium.SOLUTION: An ink composition comprises: (a) a first polymer compound, which comprises 20-90 mass% of a repeating unit (a-1) including a substructure represented by the specified general formula (1), 8-25 mass% of a repeating unit (a-2) having a betaine structure, and a repeating unit (a-3) having a hydrophobic group; (b) water; and (c) a water-soluble organic solvent. In the general formula (1), Rand Reach represent a hydrogen atom or a C1-C4 alkyl group, with at least one of Rand Rrepresenting a C1-C4 alkyl group, where Rand Rmay be bonded to each other to form a 4-6 membered alicyclic structure; and the symbol * represents a binding site to a main chain or side chain in the polymer compound. |
