Patent ID: 8529044

Claim:
An ink composition, comprising: water-insoluble polymer particles comprising a colorant and a water-insoluble polymer, wherein the water-insoluble polymer comprises: a structural unit derived from a monomer having a salt-forming group (a), and at least one of a structural unit derived from a styrenic macromer (b) or a structural unit derived from a hydrophobic monomer (c), wherein the structural unit derived from the hydrophobic monomer (c) is represented by the following Formula (1) or Formula (2): wherein, in Formula (1), W represents an imino group, a straight-chain, branched or cyclic alkylene group, an aralkylene group, an arylene group, *-(CR 11 R 12 ) n NHCONH—, *—(CR 11 R 12 ) n CONH— or any combination thereof, each of which may have a substituent, or a single bond; *— represents a bonding position to the main chain; and R 11 and R 12 each independently represent a hydrogen atom or a substituent; wherein, in Formula (2), W represents a single bond or a divalent linking group, and wherein, in Formula (1) and Formula (2), R 1 represents a hydrogen atom or a substituent; one of R 2 to R 5 represents a single bond to W, and the others each independently represent a hydrogen atom or a substituent; J represents *—CO—, *—COO—, *—CONR 10 —, *—OCO—, a methylene group, a phenylene group or *—C 6 H 4 CO—; R 10 represents a hydrogen atom, an alkyl group, an aryl group or an aralkyl group; A 1 represents a hetero ring group; Q 1 represents a group of atoms that is necessary for forming a ring together with the carbon atoms; and *— represents a bonding position to the main chain; and a compound represented by the following formula (A), wherein the content of free polymer derived from the water-insoluble polymer is 1.0% by mass or less with respect to the total mass of the ink composition: wherein, in formula (A), R 1 and R 2 each independently represent a hydrogen atom or a hydrocarbon group having 1 to 22 carbon atoms; R 3 represents a divalent hydrocarbon group having 1 to 18 carbon atoms; R 1 and R 2 may be the same as or different from each other, but R 1 and R 2 do not both represent a hydrogen atom at the same time; R 1 to R 3 may each have a substituent; m and n each independently represent an average addition mole number of AO of from 0 to 30; and AO represents an alkylene oxy group.