Water dilutable, polyester polyols and their use in coating compositions

A water dilutable, urethane group-containing polyester polyol having an acid number of 9 to 35 mg KOH/g, wherein 45 to 100% of the acid groups are neutralized by bases, a hydroxyl number of 35 to 220 mg KOH/g, a molecular weight (M.sub.w) of 3,500 to 70,000 and a urethane content (--NH--CO--O--) of 3.5 to 13.5% by weight, wherein the polyester polyol comprises the at least partly neutralized reaction product of

• a) 41 to 86% by weight of one or more branched polyester polyols having a hydroxyl number of 50 to 450 and comprising the reaction product of
• a1) 0 to 55% by weight of one or more monocarboxylic acids having 7 to 18 carbon atoms,
• a2) 11 to 58% by weight of one or more di- and/or tricarboxylic acids or their anhydrides,
• a3) 17 to 63% by weight of one or more alcohols having two and/or more hydroxyl groups,
• a4) 0 to 15% by weight of one or more monoalcohols and
• a5) 0 to 20% by weight of one or more hydroxycarboxylic acids, aminocarboxylic acids, lactones, lactams and aminoalcohols,
• b) 1.5 to 7.0% by weight of 2,2-bis(hydroxymethyl)alkanoic acid,
• c) 0 to 10% by weight of one or more compounds containing at least one OH, NH and/or NH.sub.2 group and having a molecular weight of 32 to 500,
• d) 5 to 26% by weight of one or more compounds containing at least two isocyanate groups and having a molecular weight of 168 to 2,000 and
• e) 5 to 40% by weight of one or more polycarbonate polyols having a molecular weight of 450 to 16 000,
• wherein the percentages of a) to e) and a1) to a5) add up to 100% and wherein the urethane group-containing polyester polyols contain 1 to 25% by weight of carbonate groups (--O--CO--O--) incorporated through component e).

A water dilutable, urethane group-containing polyester polyol having an acid number of 9 to 35 mg KOH/g, wherein 45 to 100% of the acid groups are neutralized by bases, a hydroxyl number of 35 to 220 mg KOH/g, a molecular weight (M.sub.w) of 3,500 to 70,000 and a urethane content (--NH--CO--O--) of 3.5 to 13.5% by weight, wherein the polyester polyol comprises the at least partly neutralized reaction product of

• a) 41 to 86% by weight of one or more branched polyester polyols having a hydroxyl number of 50 to 450 and comprising the reaction product of
• a1) 0 to 45% by weight of one or more monocarboxylic acids having 7 to 18 carbon atoms,
• a2) 11 to 55% by weight of one or more di- and/or tricarboxylic acids or their anhydrides,
• a3) 14 to 60% by weight of one or more alcohols having two and/or more hydroxyl groups,
• a4) 0 to 15% by weight of one or more monoalcohols,
• a5) 0 to 20% by weight of one or more hydroxycarboxylic acids, aminocarboxylic acids, lactones, lactams and aminoalcohols and
• a6) 5 to 45% by weight of one or more polycarbonate polyols having a molecular weight of 450 to 16,000,
• b) 1.5 to 7.0% by weight of 2,2-bis(hydroxymethyl)alkanoic acid,
• c) 0 to 10% by weight of one or more compounds containing at least one OH, NH and/or NH.sub.2 group and having a molecular weight of 32 to 500 and
• d) 5 to 26% by weight of one or more compounds containing at least two isocyanate groups and having a molecular weight of 168 to 2,000,
• wherein the percentages of a) to d) and a1) to a6) add up to 100% and wherein the urethane group-containing polyester polyols contain 1 to 25% by weight of carbonate groups (--O--CO--O--) incorporated through component a6).

A water dilutable binder which comprises

• A) 30 to 98% by weight of a water dilutable, urethane group-containing polyester polyol having an acid number of 6 to 45 mg KOH/g, wherein 25 to 100% of the acid groups are neutralized by bases, a hydroxyl number of 20 to 250 mg KOH/g, a molecular weight (M.sub.w) of 2,000 to 150,000 and a urethane content (--NH--CO--O--) of 2 to 16% by weight, wherein the polyester polyol comprises the at least partly neutralized reaction product of
• a) 35 to 90% by weight of one or more branched polyester polyols having a hydroxyl number of 40 to 600 and comprising the reaction product of
• a1) 0 to 60% by weight of one or more monocarboxylic acids having 6 to 22 carbon atoms,
• a2) 6 to 65% by weight of one or more di- and/or tricarboxylic acids or their anhydrides,
• a3) 10 to 70% by weight of one or more alcohols having two and/or more hydroxyl groups,
• a4) 0 to 35% by weight of one or more monoalcohols,
• a5) 0 to 30% by weight of one or more hydroxycarboxylic acids, aminocarboxylic acids, lactones, lactams and aminoalcohols and
• a6) 0 to 45% by weight of one or more polycarbonate polyols having a molecular weight of 450 to 16,000,
• b) 0.5 to 8.5% by weight of one or more hydroxycarboxylic acids
• c) 0 to 15% by weight of one or more compounds containing at least one OH, NH and/or NH.sub.2 group and having a molecular weight of 32 to 500,
• d) 3 to 33% by weight of one or more compounds containing at least two isocyanate groups and having a molecular weight of 168 to 2,000 and
• e) 0 to 45% by weight of one or more polycarbonate polyols having a molecular weight of 450 to 16,000, and
• B) 2 to 70% by weight of one or more cross-linking agents, wherein the percentages of a) to e) and a1) to a6) add up to 100%, the urethane group-containing polyester polyols contain 1 to 25% by weight of carbonate groups (--O--CO--O--) incorporated through components e) and/or a6) and the percentages of A) and B) are based on the solids content of A) and B).