Polyoxypropylene-polyols and polyoxypropylene-polyoxyethylene- polyols containing hydroxyl groups

摘要

The present invention relates to a process for the preparation of a hard foam containing urethane groups or urethane and isocyanurate groups by the polyisocyanate polyaddition process, by reactingP P a) a polyoxypropylene- or polyoxyethylene-polyoxypropylene- polyol containing secondary hydroxyl groups, having a functionality of from 3.5 to 4.3, a hydroxyl number of from 350 to 650 and a viscosity of from 500 to 2,500 mPa·s at 23° C. and prepared by anionic polymerization of 1,2-propylene oxide or ethylene oxide and 1,2-propylene oxide onto an initiator molecule mixture containing, based on the total weight,PPa1) from 40 to 80% by weight of a hexanetetrol, PPa2) from 1 to 30% by weight of a hexanetriol,P Pa3) from 0 to 35% by weight of glycerol andPPa4) from 0 to 15% by weight of sorbitol or mannitol, or a mixture thereof, PPb) optionally, a low-molecular-weight chain extender and/or crosslinking agent withPPc) an organic, modified or unmodified polyisocyanate; in the presence ofPPd) a blowing agent,PPe) a catalyst and, optionally,P Pf) assistants and/or additives, and novel polyoxypropylene- polyols and polyoxyethylene-polyoxypropylene-polyols which can be used for this purpose.