Aqueous binders and their use in aqueous coating compositions

An aqueous binder for aqueous coating compositions which comprises the urethane group-containing reaction product of

• A) 9.9 to 85 wt. % of a hydroxy- and acid-functional poly(meth)acrylate and
• B) 14.9 to 90 wt. % of a hydroxy-functional polyester wherein a portion of the acid component used to prepare the polyester is an unsaturated fatty acid capable of oxidative drying with
• C) 0.1 to 20 wt. % of a diisocyanate having a molecular weight of 140 to 318,
• wherein the sum of the percentages of A) to C) add up to 100 and wherein at least a portion of the carboxyl groups are present in neutralized form.

A one- or two-component, air-drying and/or heat-drying coating composition wherein the binder comprises an aqueous binder containing the urethane group-containing reaction product of

• A) 9.9 to 85 wt. % of a hydroxy- and acid-functional poly(meth)acrylate and
• B) 14.9 to 90 wt. % of a hydroxy-functional, fatty acid-modified polyester with
• C) 0.1 to 20 wt. % of a diisocyanate having a molecular weight of 140 to 318,
• wherein the sum of the percentages of A) to C) add up to 100 and wherein at least a portion of the carboxyl groups are present in neutralized form, said binder optionally being present in combination with other oxidatively drying lacquer binders.