An aqueous dispersion of a modified alkyd resin comprising - water, - an emulsifier S - a copolymer P having moieties derived from one or more of - esters M1 of an olefinically unsaturated carboxylic acid M11 having at least one olefinic unsaturation and at least one acid group per molecule, with a linear, branched or cyclic aliphatic hydroxy-functional compound M12 having at least one hydroxyl group per molecule, - esters M2 of an olefinically unsaturated hydroxy functional compound M22 having at least one olefinic unsaturation and at least one hydroxyl group per molecule, with linear, branched or cyclic aliphatic carboxylic acid M21 having no olefinic unsaturation and at least one acid group per molecule, - an olefinically unsaturated carboxylic acid M11 having at least one olefinic unsaturation and at least one acid group per molecule, - an olefinically unsaturated hydroxy functional compound M22 having at least one olefinic unsaturation and at least one hydroxyl group per molecule, - an olefinically unsaturated compound M3 that has at least one olefinic unsaturation, selected from the group consisting of olefinically unsaturated alkylaromatic compounds M31, olefinically unsaturated aliphatic ethers M32, olefinically unsaturated aliphatic ketones M33, olefinically unsaturated aliphatic halogenides M34, and olefinically unsaturated aliphatic pseudohalogenides M35, - an alkyd resin A based on aliphatic linear or branched monocarboxylic acids A1 having from six to forty carbon atoms, aliphatic linear or branched or cyclic hydroxy-functional compounds A2 having at least two hydroxyl groups per molecule, aromatic or aliphatic linear, branched or cyclic acids A3 having at least two acid groups per molecule, wherein the alkyd resin A has an acid number of at least 3 mg/g, wherein the ratio m / m of the mass m of the alkyd resin A to the mass m of the polymer P is at least 1 kg / 0.5 kg, and wherein the emulsifier S is a mixture of a nonionic emulsifier S n and an anionic emulsifier S a. - water, - an emulsifier S - a copolymer P having moieties derived from one or more of - esters M1 of an olefinically unsaturated carboxylic acid M11 having at least one olefinic unsaturation and at least one acid group per molecule, with a linear, branched or cyclic aliphatic hydroxy-functional compound M12 having at least one hydroxyl group per molecule, - esters M2 of an olefinically unsaturated hydroxy functional compound M22 having at least one olefinic unsaturation and at least one hydroxyl group per molecule, with linear, branched or cyclic aliphatic carboxylic acid M21 having no olefinic unsaturation and at least one acid group per molecule, - an olefinically unsaturated carboxylic acid M11 having at least one olefinic unsaturation and at least one acid group per molecule, - an olefinically unsaturated hydroxy functional compound M22 having at least one olefinic unsaturation and at least one hydroxyl group per molecule, - an olefinically unsaturated compound M3 that has at least one olefinic unsaturation, selected from the group consisting of olefinically unsaturated alkylaromatic compounds M31, olefinically unsaturated aliphatic ethers M32, olefinically unsaturated aliphatic ketones M33, olefinically unsaturated aliphatic halogenides M34, and olefinically unsaturated aliphatic pseudohalogenides M35, - an alkyd resin A based on aliphatic linear or branched monocarboxylic acids A1 having from six to forty carbon atoms, aliphatic linear or branched or cyclic hydroxy-functional compounds A2 having at least two hydroxyl groups per molecule, aromatic or aliphatic linear, branched or cyclic acids A3 having at least two acid groups per molecule, wherein the alkyd resin A has an acid number of at least 3 mg/g,