A binder, neutralizable with bases, for producing siccativated aqueous coating agents, based on a polydiene resin partially crosslinked with bis(2-oxazoline), with an acid number of 50 to 100, that is obtainable by anhydrous reaction ofA. 40 to 80 wt % of one or several polydiene oils with a weight-average molecular weight of 300 to 5000,B. 5 to 25 wt % of one or several .alpha.,.beta.-ethylenically unsaturated carboxylic acids,C. 1 to 10 wt % of one or several bis(2-oxazoline)s andD. 0 to 20 wt % of one or several physically curing resins and/or ethylenically unsaturated monomers,transfer into an aqueous medium and reaction withE. 1 to 40 wt % of one or several ethylenically unsaturated monomers in presence of an oil-soluble, free-radical-forming polymerization initiator and optionally a polymerization regulator,wherein each of the above percentages by weight relates to the sum of components A, B, C, D, and E. A process for production of the binder and its use in aqueous coating agents.