Inkjet ink comprising dynamic surface tension agent

Abstract

An inkjet ink comprising water, colorant, and a dynamic surface active agent at an effective concentration such that dynamic surface tension DST20 min at 20 minutes universal surface age is less than each of dynamic surface tension DST1 sec at 1 second universal surface age and dynamic surface tension DST10 sec at 10 seconds universal surface age, and the difference between DST10 sec and DST20 min is greater than 9.2 mN/m at 21° C. or the difference between DST1 sec and DST20 min is greater than 15.5 mN/m at 21° C., and static surface tension of the ink is less than 50 mN/m. Large dynamic surface tension differences between the indicated time scales yield an optical density improvement in printed images. Anionic fluorosurfactant comprising a phosphate group at concentrations up to about 1 weight percent enables a combination of high optical density and good felt wetting in inkjet cartridges.

Dependencies are inferred from the claim text.