PREPARATION OF FLEXIBLE POLYURETHANE FOAMS HAVING LOW COMPRESSIVE STRENGTH AND BLOCK POLYOXYPROPYLENE POLYOXYETHYLENE POLYOL MIXTURES WHICH CAN BE USED FOR THIS PURPOSE

摘要

Flexible polyurethane foams having low compressive strength and relatively good tensile strength are prepared by reacting a) a block polyoxypropylene-polyoxyethylene-polyol mixture which has a hydroxyl number of from 14 to 65, contains from 2 to 9% by weight, based on the weight of the polyoxypropylene units, of ethylene oxide units bonded in the terminal position and is prepared by anionic polymerization of the alkylene oxides with an initiator mixture having an average functionality of from 2.3 to 2.8 and consisting of water and glycerol and/or trimethylolpropane, or a mixture of these block polyoxypropylene-polyoxyethylene-polyol mixtures with bi- and/or trifunctional polyoxypropylenepolyoxyethylene-polyols having a hydroxyl number of from 20 to 70, and b) if required, 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 required, f) assistants and/or additives.