PIGMENT DISPERSING AGENT FOR INKJET PRINTING, AQUEOUS PIGMENT DISPERSION FOR INKJET PRINTING, AQUEOUS INK COMPOSITION FOR INK JET PRINTING, AND IMAGE FORMATION METHOD

摘要

Provided are the following: a pigment dispersing agent for inkjet printing, which can provide a pigment dispersion and an ink composition having excellent storage stability, with this ink composition able to improve nozzle rest recovery in an inkjet recording method; an aqueous pigment dispersion for inkjet printing and an aqueous ink composition for ink jet printing which are obtained using this dispersing agent; and an image formation method in which this ink composition is used. This pigment dispersing agent for inkjet printing contains a polymer having a polyvinyl compound structure portion and a polyurethane structure portion. The total content of constituent components represented by formulae (1) and (2) in the polyvinyl compound structure portion is 30 mass% or less. The acid value of the polymer exceeds 80 mg KOH/g. In formulae (1) and (2), R^1a and R^1b each denote a hydrogen atom or an alkyl group having 1-4 carbon atoms. A¹ denotes -O- or -NR^A-. L^1a and L^1b each denote an alkyl group having 4 or more carbon atoms, or the like.