Patent ID: 7553357

Claim:
An ink composition comprising: a colorant, a betaine-based surfactant represented by the following formula (1) and a defoaming agent: (R)p-N-[L-(COOM)q]r (Formula 1) wherein, R represents a hydrogen atom, alkyl group, aryl group or heterocyclic group; L represents a divalent or more linking group; M represents a hydrogen atom, alkali metal atom, ammonium group, protonated organic amine or nitrogen-containing heterocyclic group or quaternary ammonium ion group, or represents a group that does not exist as a cation in the case of being a counter ion of an ammonium ion comprising an N atom in formula (1); q represents an integer of 1 or more; r represents an integer of 1 to 4; p represents an integer of 0 to 4; p+r is 3 or 4; N is a nitrogen atom that composes a quaternary amine in the case where p+r is 4; R may be the same or different when p is 2 or more; COOM may be the same or different when q is 2 or more; and L-(COOM) q may be the same or different when r is 2 or more, wherein the defoaming agent is a diacetylene tetraol represented by the following general formula (3): wherein, R 1 and R 2 each independently represent an alkyl group having 1 to 8 carbon atoms: R 3 each independently represent a hydrogen atom or a methyl group; —O—R 4 — each independently represent an oxyethyl, oxypropyl or oxybutyl group; R 5 represents a divalent linking group, and k, l, m and n respectively represent an integer of 1 to 100.