Abstract: The present invention relates to a printing ink composition comprising a polymer selected from a poly(styrene-maleic acid) co-polymer having an acid number of ?225 mg KOH/g, a poly(styrene-maleamic acid) co-polymer having an acid number of ?225 mg KOH/g or a combination thereof, wherein the co-polymer is a lithium, sodium, potassium, ammonium or quaternary ammonium salt or combinations thereof. The printing ink composition is suitable for directly printing onto non-porous substrates particularly without the need for a chemical primer layer or chemical pre-treatment.

Abstract: The invention provides an aqueous printing ink composition comprising a polyurethane dispersion, wherein the polyurethane of the polyurethane dispersion comprises the properties of (a) ketone or aldehyde groups present at one or more polymer chain ends; (b) a number average molecular weight ?50,000, more preferably ?25,000 and; (c) the content of ketone and/or aldehyde groups is in the range 0.02 to 4.0 mmol g?1, based on the dry polymer weight.