Abstract: The present invention is directed to the production of free-rise polyurethane foams using sterically hindered diamines of the formula (e) ##STR1## and/or ##STR2## in which R.sup.1 and R.sup.2 may be the same or different and represent C.sub.1 -C.sub.4 -alkyl andR.sup.3 and R.sup.4 may again be the same or different and represent H or CH.sub.3, is added to said reaction mixture.

Abstract: Rigid polyurethane foams are obtained by reacting an isocyanate-reactive component containing at least two isocyanate-reactive hydrogen atoms, having a molecular weight of from 32 to 10,000 or a mixture thereof, with a polyisocyanate composition comprising(a) 30 to 70 pbw of polymethylene polyphenyl polyisocyanate with an iscocyanate content of from 29 to 32%,(b) 30 to 70 pbw of a compound having 30 to 42% by weight isocyanate content obtained by reacting 2,4- and/or 2,6-tolylene diisocyanate with an active hydrogen containing compound, thereafter initiating a reaction in the presence of trimerization catalyst, if necessary diluted with 2,4- and/or 2,6-tolylene diisocyanate,(c) 0 to 30 pbw of other isocyanate compounds in the presence of water and/or organic blowing agents, catalysts and surfactants.

Abstract: Rigid, closed-cell, flame-resistant polyurethane foams are produced by reacting a polyol mixture with a polyphenyl-polymethylene-polyisocyanate in the present of a catalyst system. The polyol mixture includes: (1) from 25 to 43 wt % flame proofing agent, (2) from 5 to 50 wt % sucrose polyether having an OH number of from 350 to 550, (3) from 0 to 30 wt % amine initiated polyethers having an OH number of from 400 to 800, (4) from 0 to 30 wt % other polyether or polyester having an OH number of from 150 to 600, (5) from 4 to 13 wt % glycerol, (6) from 0.5 to 3 wt % silicone stabilizer and (7) from 0.05 to 1.5 wt % water. The catalyst system is made up of at least two components selected from tertiary amines, alkali metal carboxylates, quaternary ammonium carboxylates and organic tin compounds. The reactants are employed in quantities such that the NCO to OH equivalent ratio is from 1.07 to 1.45 (the isocyanate-index is from 1.07 to 1.45).