| abstract |
The invention relates to a method for producing a prepolymer for the production of an integral polyurethane foam. According to the invention, the prepolymer is or can be obtained by reaction of a composition that contains or consists of the following components: component A containing or consisting of a polyoxymethylene-polyoxyalkylene block copolymer having a hydroxyl number according to DIN 53240-2 (November 2007) DIN 53240-1:2013-06 of 20 mg KOH/g to 200 mg KOH/g as component A1, optionally a polymer that is different from component A1 and that has an average number of at least 1.7 Zerewitinoff-active hydrogen atoms and a hydroxyl number according to DIN 53240-2 (November 2007) of 40 mg KOH/g to 80 mg KOH/g as component A2, optionally a compound that is different from components A1 and A2 and has at least two Zerewitinoff-active hydrogen atoms and a molecular weight of 50 to 500 g/mol as component A3, component B containing or consisting of di- and/or polyisocyanates with an NCO content according to EN ISO 11909 (2007) of 15 to 45 wt.-% relative to component B, 0.04 to 1.0 wt.-%, relative to the composition, a proton acid as component C, and optionally a component D that contains auxiliary agents, at a characteristic number of 450 to 850. The invention further relates to the prepolymer obtained by the method, to an integral polyurethane foam based on the prepolymer, and to the use thereof. |