| abstract |
The present application relates to a process for preparing rigid polyurethane or urethane modified polyisocyanate foams, from compounds reactive with polyfunctional isocyanate and polyisocyanate, in the presence of expanding agents, where the isocyanate reactive polyfunctional compounds comprise a polyol of polyether having a hydroxyl number that fluctuates between 50 and 400 mg of KOH / g, which is obtained by reacting a polyfunctional initiator first with ethylene oxide and then with propylene oxide, so that the degree of propoxylation of said polyether polyol is between 0.33 and 2 mol of propylene oxide per active hydrogen atom in the initiator, and the molar ratio of ethylene oxide to propylene oxide in said polyether polyol is at least 2. |