Abstract: 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.

Abstract: The present invention relates to foamed polyurethane obtainable by mixing a) polyisocyanates, b) relatively high molecular weight compounds having groups reactive toward isocyanate groups, c) solid particles, d) blowing agents, e) if appropriate, chain extender, crosslinking agent or mixtures thereof, f) if appropriate, catalyst and g) if appropriate, other additives to give a reaction mixture and allowing the reaction mixture to react to completion, the proportion of chain extender being less than 6% by weight, based on the total weight of the components a) to f), the content of solid particles being greater than 15% by weight, based on the total weight of the components a) to f), and the average functionality of the relatively high molecular weight compounds having groups reactive toward isocyanate groups being less than 2.5.

Abstract: The invention relates to a process for producing rigid polyurethane foams by reacting a) polyisocyanates with b) compounds having at least two hydrogen atoms which are reactive toward isocyanate groups in the presence of c) blowing agents, wherein at least one graft polyol b1) which can be prepared by in-situ polymerization of olefinically unsaturated monomers in a polyether alcohol b1i), where the polyether alcohol b1i) has a functionality of from 2 to 4 and a hydroxyl number in the range from 100 to 250 mg KOH/g, its polyether chain comprises propylene oxide and up to 20% by weight, based on the polyether alcohol b1i), of ethylene oxide, and acrylonitrile and styrene in a weight ratio of acrylonitrile:styrene of from >1:1 to 4:1 are used as olefinically unsaturated monomers, is used as compounds having at least two hydrogen atoms which are reactive toward isocyanate groups b), and the reaction is carried out in the presence of at least one compound b1ii) which has at least one olefinic double bond an