| abstract |
The present invention relates to aqueous polyurethane dispersions, processes for their preparation, products containing them and their use for coating compositions, impregnating compositions, adhesives or sealants. The aqueous polyurethane dispersion comprises the following components: A1) at least one polyisocyanate having an isocyanate functionality of 2 or greater; A2) at least two different polytetramethylene ether glycols A2a) and A2b) where A2a) is A2b) has a number average molecular weight of greater than 1500 g/mol]; and A3) has a number average molecular weight of 32 g/mol to 400 g/mol and has hydroxyl and carboxyl functional at least one anionic or potentially anionic hydrophilic agent containing groups; B) at least one amino-functional anionic or potentially anionic hydrophilic agent; and C) from 32 g/mol to 400 g/mol comprising a polyurethane obtained by reacting a system comprising at least one amino-functional compound having a number-average molecular weight and containing no hydrophilic groups, wherein the number-average molecular weight of A2a) and the number-average molecular weight of A2b) and the weight of A3) is 20% to 70% of the weight of the hydrophilizing agent of the system, the hydrophilizing agents of the system being components A3 and B. |