Patent ID: 8268908

Claim:
A pigment dispersion liquid comprising a polymer dispersant, a coloring material and water, wherein the polymer dispersant is formed of at least a hydrophobic unit and a hydrophilic unit, the hydrophobic unit having a block portion formed of at least one hydrophobic monomer; the coloring material is formed of a pigment having on its surface an acid form anionic group; and the pigment dispersion liquid further contains a basic compound capable of forming a complex with an alkaline metal, wherein the hydrophilic unit comprises, as a repeating unit, an acrylic amide structure represented by the following general formula (1): where R1 represents a hydrogen atom or a methyl group; X represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms; and n is 1 to 10, and wherein the basic compound is at least one compound selected from the group consisting of the following general formulae (2) to (5): where R1 represents a hydrogen atom or an alkyl group having 1 to 18 carbon atoms; R2 is a hydrogen atom or -Py-R1 (Py: pyridyl group); R3 is a hydrogen atom, —C(R5)=N—R4 or —CH(R5)-N(R6)-R4; R4 is an alkyl group having 1 to 18 carbon atoms, —CH 2 -Py or —CH 2 —CH 2 —N(R6)-CH 2 -Py (Py: pyridyl group); R5 is a hydrogen atom or a methyl group; R6 is a hydrogen atom or —R4; R7 and R8 are each an alkyl or alkenyl group having 1 to 4 carbon atoms; R9 is an alkyl group having 1 to 4 carbon atoms or —CH 2 —CH 2 —N(R8)-R7; and m is 1 or 2.