| 摘要 |
Aqueous polyurethane dispersions containing a polyurethane, composed ofa) at least one polyol having an average molecular weight, determined as the number average, of 500-6000 g/mol, preferably 1000 to 4000, in particular 1500 to 3000 g/mol,b) at least one polyol, preferably diol, having a molecular weight of less than 500 g/mol, preferably of 61 to 499 g/mol,c) at least one aliphatic polyisocyanate, preferably diisocyanate,d) at least one diol having a molecular weight of less than 450 g/mol, which carries one or more ionic groups and/or one or more potentially ionic groups, preferably at least one carboxyl group,e) at least one amine which is reactive towards NCO groups, carries hydroxyl groups and has an OH functionality of 1 to 6,f) water and optionallyg) a monoalcohol,characterized in that the molar ratio of polyol of the component a) to the sum of the polyols b) and d) is 1:1.5 to 1:4, preferably 1:2 to 1:3, the molar ratio of the sum of the polyols a), b) and d) to the polyisocyanate c) is 1:1.1 to 1:2.5, preferably 1:1.2 to 1:1.7, the OH functionality of the polyurethane being 2 to 6, preferably 2 to 4, and the average molecular weight, determined as the number average, of the polyurethane being less than 15,000, preferably from 2500 to 10,000, in particular from 3000 to 7000, g/mol.
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