| abstract |
The present invention relates to aqueous solutions or dispersions of copolymers A) containing a hydroxy-functional, hydrophobic copolymer I) containing 30 to 85% by weight of (meth)acrylic acid esters having C 1 to C 18 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 C 1 to C 18 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) copolymer A) has 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). n The present invention also relates to a method of preparing these dispersions or solutions of copolymers A) and to their use in binder compositions with at least one crosslinking resin selected from aminoplast resins, blocked polyisocyanates and polyisocyanates containing free isocyanate groups. |