Abstract: The invention relates to a process for the production of foams based on polyisocyanates by reaction of polyisocyanates, compounds having at least two hydrogen atoms which are reactive toward isocyanate groups, blowing agents and if appropriate other additives. A blowing agent which consists to the extent of at least 10 mol % of one or more branched dodecafluorohexanes is used here.

Abstract: Fiber-containing polyurethane foams having improved compression properties, especially at deformations of greater than 50%, are obtained by incorporating in the foam-forming composition from 0.1 to 10% by weight, based on the weight of finished foam, of polyolefin fibers, e.g., polyethylene or polypropylene fibers, that have been treated to provide them with functional groups that are reactive with isocyanates. The reactive fibers may be obtained by fixing to the fiber surface or incorporating in the fiber polyfunctional compounds, e.g., starch, methylcellulose, carboxy methylcellulose, saccharin, polyglycols, polyvinyl alcohol, hydroxyl-group-containing block copolymers, completely saponified copolymers of ethylene and vinylacetate and oxidation products of a polyolefin.