Patent ID: 7922315

Claim:
An inkjet ink for printing on hydrophobic media, comprising: a pigment; water; a surfactant having a dynamic contact angle of no more than 20°, the dynamic contact angle being an angle formed by a droplet of a 0.1% aqueous solution of the surfactant and a substrate surface of a stainless steel SUS 304 as measured, 300 ms after contact of the droplet with the substrate surface upon dropping the surfactant solution onto the substrate surface under an environment having a temperature of 23° C.; from 40 to 75 weight % of a polar aprotic solvent having a molecular weight of 40 to 130, and at least one of an acetylene glycol and a glycol ether, and at least one ethylene oxide adduct of ammonium citrate expressed by Formula (4): where M 1 , M 2 , and M 3 may be the same or differ, with each of M 1 , M 2 , and M 3 indicating sodium, potassium, or other alkali metal, the ammonium group, or hydrogen, but with not all of M 1 , M 2 , and M 3 indicating hydrogen at the same time, and n indicating a numeral from 1 to 28.