Aqueous binder based on polyester-polyuréthane

A 20-60 wt.% aq. dispersion of a polyester-polyurethane (I) with a viscosity of 10-20000 mPa.s at 23 degrees C and pH of 5.5-10 is claimed. (I) has a Mw of 1500-100000, OH number of 20-300 mg KOH/g, acid number of 7-70 mg KOH/g, corresp. to 20-100% COOH gps. neutralised as carboxylate gps. and a urethane (-NH-CO-O-) content of 2.5-15 wt.%. (I) is a salt obtd. by (partial) neutralisation of a reaction prod. (II) with a base. (II) is prepd. from (a) 50-91 wt.% polyester component, comprising polyester-polyol(s) (III) with an OH no. of 25-350; (b) 7-45 wt.% polyisocyanate component (IV), comprising at least 50 wt.% 1-methyl-2,4- and/or 2,6-diisocyanatocyclohexane (IVA), rest organic polyisocyanates (IVB) of molecular wt. 140-1500; (c) 2-12 wt.% (potential) anionic component (V), comprising cpd(s). with NCO-reactive gp(s). and opt. (partly) neutralised salt-forming gps., opt. (d) 0.10 wt.% nonionic-hydrophilic component (VI), comprising a mono- or di-functional cpd. with hydrophilic polyether chain(s); and/or opt. (e) 0-30 wt.% other components (VII) with NCO-reactive H atoms and a molecular wt. of 62-2500. Also claimed is an aq. binder combination of an aq. (I) dispersion and a hardener.