Water-based binder composition and its use for the production of coating or sealing compositions

A water-based binder composition comprising

• A) an aqueous solution or dispersion of a water-dilutable organic polyol component containing a mixture of at least 5% by weight each of at least two hydroxy-functional polymers selected from at least two of the following groups
• A1) polyester resins containing hydroxyl, urethane and carboxylate groups and having a molecular weight (M.sub.w) of 3000 to 100,000, a hydroxyl number of 20 to 240, an acid number (based on all of the carboxyl groups, wherein 25 to 100% are present in carboxylate form) of 8 to 60 and a urethane group content (--NH--CO--O--) of 1.0 to 15.0% by weight,
• A2) polyester resins containing hydroxyl and carboxylate groups, but no urethane or sulfonate groups, and having a molecular weight (M.sub.w) of 1000 to 50,000, a hydroxyl number of 15 to 240 and an acid number (based on all of the carboxyl groups, wherein 25 to 100% are present in carboxylate form) of 15 to 90,
• A3) polyester resins containing hydroxyl and sulfonate groups and, optionally, carboxylate groups and/or urethane groups and having a molecular weight (M.sub.w) of 1000 to 50,000, a hydroxyl number of 15 to 240 and an acid number (based on all the sulfonic acid and optional carboxyl groups, wherein 25 to 100% are present in salt form) of 3 to 45,
• A4) polyacrylate resins containing hydroxyl groups, and also carboxylate and/or sulfonate groups and having a molecular weight (M.sub.w) of 500 to 100,000, a hydroxyl number of 15 to 270 and an acid number (based on all the carboxyl and sulfonic acid groups, wherein 25 to 100% are present in salt form) of 5 to 125 and
• A5) acrylate-grafted polyester resins containing hydroxyl groups, and also carboxylate and/or sulfonate groups and having a molecular weight (M.sub.w) of 3000 to 100,000, a hydroxyl number of 20 to 300 and an acid number (based on al the carboxyl and sulfonic acid groups, wherein 25 to 100% are present in salt form) of 5 to 75, and
• B) a polyisocyanate component which is emulsified in the aqueous solution or dispersion A), has a viscosity at 23.degree. C. of 50 to 10,000 mPa.s and contains one or more organic polyisocyanates,
• wherein the NCO:OH equivalent ratio, based on the isocyanate groups of component B) and the hydroxyl groups of the polyol component present in A), is 0.2:1 to 5:1.