Aqueous binders for coating compositions based on polyester polyurethanes

An aqueous dispersion having a viscosity at 23.degree. C. of 10 to 20,000 mPa.s and a pH of 5.5 to 10 and containing 20 to 60 wt. %, based on solids, of a polyester polyurethane which has a weight average molecular weight of 1500 to 100,000, a hydroxyl number of 20 to 300 mg KOH/g, a carboxyl group content corresponding to an acid number of 7 to 70 mg KOH/g (in which 20 to 100% of the carboxyl groups are present in neutralized form as carboxylate groups), and a content of urethane groups (calculated as --NH--CO--O--, molecular weight 59) of 2.5 to 15 wt. %, and is the reaction of

• a) 50 to 91 wt. % of a polyester component containing one or more polyester polyols having a hydroxyl number of 25 to 350,
• b) 7 to 45 wt. % of a polyisocyanate component containing at least 50 wt. %, based on the weight of component b), of 1-methyl-2,4- and/or -2,6-diisocyanatocyclohexane, the remainder selected from organic polyisocyanates having a molecular weight of 140 to 1500,
• c) 2 to 12 wt. % of a component containing one or more compounds having at least one isocyanate-reactive group and at least one anionic or potential anionic group,
• d) 0 to 10 wt. % of a component containing one or more compounds having one or two isocyanate-reactive groups and containing at least one non-ionic, hydrophilic polyether chain and
• e) 0 to 30 wt. % of a component, which is different from components a), c) and d), contains isocyanate-reactive groups and has a molecular weight of 62 to 2500,
• wherein the sum of the percentages of a) to e) add up to 100.