Polyurethane foam for use as insulating material at ultra-low temperatures is prepared by reacting polyether polyol mixture with 4,4'-diphenylmethane diisocyanate polymer

摘要

Polyurethane foam (I) for use as an insulating material at ultra-low temperatures is prepared by reacting a mixture of propoxylated/ethoxylated sorbitol, pentaerythritol, sucrose, phthalic anhydride and bisphenol A derivatives with a 4,4'-diphenylmethane diisocyanate polymer in the presence of blowing agents, catalysts, stabilizers and other additives. (I) is prepared from: (a) a mixture of 20-60 wt.% propoxylated/ethoxylated sorbitol (IIa), 10-40 wt.% propoxylated/ethoxylated pentaerythritol (IIb), 10-20 wt.% propoxylated/ethoxylated sucrose (IIc), 10-20 wt.% propoxylated/ethoxylated phthalic anhydride (IId) and 10-20 wt.% propoxylated/ethoxylated bisphenol A (IIe); and (b) a 4,4'-diphenylmethane diisocyanate polymer having 2.7-3.1 functional groups per molecule.