| abstract |
The present invention discloses a method for improving the heat resistance of a polyurethane or polyisocyanurate foam after aging, the method comprising producing the foam from a foamable composition comprising an isocyanate and polyol premix composition, wherein the foam is The polyol premix composition comprises a polyol or a mixture of polyols, a blowing agent and a flame retardant, and the blowing agent is selected from the group consisting of 1,3,3,3-tetrafluoropropylene (1234ze), 1,1, 1,4,4,4-hexafluoro-2-butene (1336mzzzm) and/or 1-chloro-3,3,3-trifluoropropene (1233zd), wherein the flame retardant comprises 25phpp or less Phosphate based flame retardant. |