To obtain a low-viscosity ink compsn, which forms a cured film excellent in adhesion to a substrate, hardness, surface gloss, and resistances to solvents and water by compounding a water-base reactive resin dispersion prepd. from a carboxylated polymer with an alkylene-oxide-modified polyol polymethacrylate and a photoinitiator.

A (meth)acrylate having at least one carboxyl group is polymerized (or is copolymerized with an ethylenically unsatd. monomer) at 150-310°C to give a polymer having a number average mol.wt. of 1,000-15,000 and an acid value of 100-300mgKOH/g, which is dissolved or dispersed in an aq. alkaline soln. and subjected to the addition reaction with a (meth)acrylate having an epoxy group to give a water-base reactive resin dispersion having an acid value of 20-200mgKOH/g. This dispersion in an amt. of 80-40 pts.wt. is compounded with 20-60 pts.wt. polyol (meth)acrylate having at least two (meth)acryloyl groups and having 1-10mol of added alkylene oxide units and an effective amt. of a photoiniator.