An aqueous ink composition including water; an optional co-solvent; an optional colorant; a sulfonated polyester; and an isoprene rubber. A process of digital offset printing, the process including applying an ink composition onto a re-imageable imaging member surface at an ink take up temperature, the re-imageable imaging member having dampening fluid disposed thereon; forming an ink image; transferring the ink image from the re-imageable surface of the imaging member to a printable substrate at an ink transfer temperature; wherein the ink composition comprises: water; an optional co-solvent; an optional colorant; a sulfonated polyester; and an isoprene rubber. A process including combining a sulfonated polyester resin, water, an optional co-solvent, an optional colorant, a sulfonated polyester, and an isoprene rubber to form an aqueous ink composition.