Wäßrige Dispersionen, ihre Herstellung und Verwendung als Lackbindemittel

摘要

Polyurethane urea dispersions are obtained by reacting: (A) 15 to 50 wt %, preferably 20 to 40 wt %, of a linear or weakly branched polyester polyol with a molecular weight from 500 to 6000; (B) 2 to 10 wt %, preferably 3 to 7 wt %, of one or several polyols having a molecular weight < 500; (C) 1 to 10 wt % of at least one mono- and/or difunctional compound, as regards the isocyanate reaction, which in addition contains anionic groups or functional groups which can be converted into anionic groups; (D) 0 to 15 wt % of a hydrophilic, monohydric or dihydric alcohol with ethylene oxide units and a molecular weight from 600 to 3000; (E) 3 to 70 wt %, preferably 40 to 60 wt %, of one or several polyisocyanates, at least 70 wt % of the polyisocyanate component consisting of one or several cycloaliphatic diisocyanates. The resulting product of (A) to (E) is then subjected to a chain-lengthening or cross-linking treatment with (F) 0.5 to 10 wt % of a mixture of one or several diamines with a polyamine with a functionality > 2, at least 20 wt % of component (F) being composed of the polyamine with a functionality > 2. The sum of components (A)-(F) always equals 100 %.