The present invention relates to an open-cell polyurethane foam comprising polyester and polyether structures and having a density of 70 to 300 g/L, 1 to 20 cells/cm, a rebound intensity greater than 30%, an elongation at break of greater than 200%, a tear propagation resistance of greater than 1.2 N/mm and a tensile strength of greater than 200 kPa. The present invention further relates to a process for producing inventive open-cell polyurethane sponges and to the use thereof as a pipe cleaning sponge.