Pigment dispersion and ink composition

A pigment dispersion comprising:

• water;
• a pigment;
• and
• a polymer dispersant having a crosslinking structure,
• wherein the polymer dispersant having a crosslinking structure further contains a structural unit represented by Formula (1) and a structural unit represented by Formula (2),
• in Formula (1),
• R1 represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms,
• R2 represents an alkylene group having 2 to 5 carbon atoms,
• R3 represents an aromatic group,
• X1 and X2 each independently represent —O— or —NH—, and
• m represents an integer of 2 or more,
• in Formula (2),
• R4 represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms,
• R5 represents an alkyl group having 8 or more carbon atoms, and
• X3 represents —O— or —NH—, and
• wherein an Ar valence of the polymer dispersant having a crosslinking structure, which is represented by the following expression, is 0.4 mmol/g to 2.9 mmol/g,
• the
• ⁢
• Ar
• ⁢
• valence
• =
• (
• the
• ⁢
• nu
• ⁢
• mber
• ⁢
• of
• ⁢
• mmol
• ⁢
• of
• ⁢
• the
• ⁢
• structural
• ⁢
• unit
• ⁢
• represented
• ⁢
• by
• ⁢
• Formula
• ⁢
• (
• 1
• )
• ⁢
• per
• ⁢
• 1
• ⁢
• g
• ⁢
• of
• ⁢
• the
• ⁢
• polymer
• ⁢
• dispersant
• ⁢
• having
• ⁢
• a
• ⁢
• crosslinking
• ⁢
• structure
• )
• ×
• (
• the
• ⁢
• nu
• ⁢
• mber
• ⁢
• of
• ⁢
• aromatic
• ⁢
• rings
• ⁢
• in
• ⁢
• the
• ⁢
• structural
• ⁢
• unit
• ⁢
• represented
• ⁢
• by
• ⁢
• Formula
• ⁢
• (
• 1
• )
• )
• .