A binder composition suitable for coating agents is described, that contains one or more unsaturated polyesters with an acid number of 5-60 mg KOH/g, a hydroxyl number of 50-200 mg KOH/g and a weight-average molecular weight (Mw) of 500-3000 g/mol, that are obtainable by reaction ofA) one or more alpha,beta-ethylenically unsaturated dicarboxylic acids or their anhydrides,B) one or more hydroxy-functional allyl ethers andC) one or more ethylenically unsaturated compounds with an oxirane group in the molecule,in the molar ratio of A):B):C)=(2 to 4):(2 to 4):(0.5 to 1.8). The composition is suitable in particular for filling putties and filling compounds that dry rapidly, even at low temperatures.