| 摘要 |
The present invention relates to a process for the preparation of flexible, soft polyurethane foams having viscoelastic, structure-borne sound-proofing properties in a temperature range of from -20.degree.C to +80.degree.C by reacting a) a polyoxyalkylene-polyol mixture containing ai) block polyoxypropylene-polyoxyethylene-polyol mixture having a hydroxyl number of from 14 to 65 and containing from 2 to 9 % by weight of terminal ethylene oxide units, based on the weight of the polyoxypropylene units, prepared by anionic polymerization, at elevated temperatures, of 1,2-propyleneoxide onto an initiator molecule mixture having a mean functionality of from 2.3 to 2.8, comprising water and ylycerol and/or trimethylolpropane, and polymerization of acylene oxide onto the resultant polyoxypropylene adduct, and aii) one or more difunctional and/or trifunctional polyoxypropylene-polyoxyethylene-polyol containing from 60 to 85 % by weight of oxyethylene units, based on the total weight of polymerized alkylene oxide units, and having a hydroxyl number of from 20 to 80, and b) if desired low-molecular-weight chain extenders with c) organic and/or modified organic polyisocyanates in the presence of d) catalysts, e) blowing agents, preferably water, and, if desired, f) auxiliaries and/or additives, and to the polyoxyalkylene-polyol mixtures (a) which can be used for this purpose.
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