| abstract |
The present invention relates to an aqueous polyurethane dispersion, a method for the preparation thereof, a product comprising the same, and use thereof for a coating composition, an impregnating composition, an adhesive or a sealant. The aqueous polyurethane dispersion comprises a polyurethane obtained by reacting a system comprising the following components: A1) at least one polyisocyanate having an isocyanate functionality of not less than 2; A2) at least two different polytetramethylene ether glycols A2a) and A2b), the A2a) having a number average molecular weight of not more than 1500 g/mol, the A2b) having a number average molecular weight of more than 1500 g/mol; and A3) at least one anionic or potentially anionic hydrophilic agent having a number average molecular weight of 32 g/mol to 400 g/mol and containing hydroxyl and carboxyl functions; B) at least one amino-functional anionic or potentially anionic hydrophilic agent; and C) at least one amino-functional compound having a number average molecular weight of 32 g/mol to 400 g/mol and containing no hydrophilic group; wherein the ratio of the number average molecular weight of the A2a) to the number average molecular weight of the A2b) is 1:9 to less than 1:1, and the weight of the A3) amounts to 20% to 70% of the weight of the hydrophilic agents of the system, wherein the hydrophilic agents of the system are components A3 and B. |