Aqueous solutions or dispersions of copolymers A) a process of making them and their use in binder compositions. Copolymers A) containing a hydroxy-functional, hydrophobic copolymer I) containing 30 to 85% by weight of (meth)acrylic acid esters having C1 to C18 hydrocarbon radicals in the alcohol portion, aromatic vinyl compounds and/or vinyl esters and 5 to 45% by weight of hydroxy-functional monomers; a hydroxy- and carboxy-functional, hydrophilic-hydrophobic copolymer II) containing 4 to 20% by weight of (meth)acrylic acid esters having C1 to C18 hydrocarbon radicals in the alcohol portion, aromatic vinyl compounds and/or vinyl esters, 4 to 15% by weight of hydroxy-functional monomers and 0.8 to 3.0% by weight of acid-functional monomers; and optionally a hydroxy-functional hydrophobic copolymer III) containing 0 to 16% by weight of hydroxy- and/or non-functional (meth)acrylic acid esters or aromatic vinyl compounds, wherein 1) the sum of Ia), Ib), IIa), IIb) IIc) and IIIa) is 100%, based on the weight of these components, 2) copolymers A) have an acid number, based on solids, of 10 to 28 mg KOH/g substance, 3) the weight percent of monomers IIc) in monomer II) is less than 25% by weight and 4) the weight percent of hydroxy-functional monomers IIb) in copolymer II) is higher than the weight percent of hydroxy-functional monomers Ib) in copolymer I).