| 摘要 |
The present invention relates to a two-component, aqueous polyurethane coating composition which may be cured at ambient temperature and which contains I) a first component based on an aqueously dispersed polyurethane wherein the polyurethane has a) an average hydroxy functionality of at least 1.8 b) a total content of urethane and urea groups, calculated as -NH-C-O-, of 9 to 20% by weight, based on the weight of the polyurethane, and c) sufficient chemically incorporated anionic groups and d) ethylene oxide units incorporated within terminal and/or lateral polyether chains to maintain the polyurethane stably dispersed in water, and II) a second component based on a water dispersible polyisocyanate wherein the polyisocyanate has a) an isocyanate content of 2 to 30% by weight, based on the weight of the polyisocyanate, b) an average functionality of at least 1.8 and c) sufficient chemically incorporated anionic groups and d) ethylene oxide units incorporated within terminal and/or lateral polyether chains to maintain the polyisocyanate stably dispersed in water, and components I and II are present in an amount sufficient to provide an equivalent ratio of isocyanate groups to hydroxyl groups of 0.8:1 to 6:1. The present invention is also directed to the coatings prepared from these coating compositions.
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