| abstract |
Polyurethane which is obtainable by reacting a) an NCO-containing prepolymer composed of a1) at least one polyesterpolyol, preferably polycarbonatepolyol, carbonate group-free polyesterpolyol, polyestercarbonatepolyol, polyesteramidepolyol, in particular polyesterdiol, having an average molecular weight, determined as the number average, greater than or equal to 500 g/mol, preferably from 500 to 6000 g/mol, in particular from 500 to 4000 g/mol, very particularly preferably from 800 to 4000 g/mol, and a2) at least one polyetherpolyol which differs from a1) and is preferably polyalkylene glycol, such as polyethylene glycol, polypropylene glycol, polytetramethylene glycol, polyhexamethylene glycol and copolyethers, in particular those containing building blocks from the group consisting of ethyleneoxy, propyleneoxy, tetramethyleneoxy and/or hexamethyleneoxy, having a molecular weight, determined as the number average, greater than or equal to 500, preferably from 500 to 10 000 g/mol, in particular from 500 to 4000, particularly preferably from 800 to 4000, g/mol, preferably a polyetherdiol, and a3) at least one polyol, in particular diol, having a molecular weight of less than 500 g/mol, which carries one or more ionic groups and/or one or more potentially ionic groups, preferably carries one or more carboxylate groups, and a4) at least one aliphatic polyisocyanate, preferably diisocyanate, preferably having a molecular weight of less than 500 g/mol, in particular from 112 to 400 g/mol, particularly preferably from 168 to 262 g/mol, and a5) optionally a nonionic polyol, preferably diol having a molecular weight of less than 500 g/mol, preferably from 61 to 499 g/mol, and a6) optionally a monoalcohol with b) at least one polysiloxane reactive towards NCO groups and having a molecular weight, determined as the number average, of less than 1500 g/mol, preferably having 1 to 6, in particular 1 to 3, amino and/or hydroxyl groups reactive towards NCO groups, in particular amino groups, and c) at least one amine reactive towards NCO groups and having an average amino functionality of from 1 to 6 and a molecular weight of less than 500 g/mol (molecular weight determined as the number average), which may be substituted by hydroxyl groups and/or sulpho groups and/or carboxyl groups, and d) water, the molar ratio of the hydroxy-functional compounds used for the preparation of the prepolymer a) to the polyisocyanate being from 1: 1.1 to 1: 2.5, preferably from 1.1:1 to 1: 1.7. |