Patent ID: 7326362

Claim:
A premix for preparing a rigid polyurethane foam or polyisocyanurate foam, consisting of: a blowing agent consisting of 1,1,1,3,3-pentafluoropropane and a vapor pressure depressant therefore in an amount of 1 to 80 parts by weight based on 100 parts by weight of the blowing agent, said vapor pressure depressant being at least one compound compatible with 1,1,1,3,3-pentafluoropropane and selected from the group consisting of dimethyl carbonate, methyl formate, γ-butyrolacetone, tetrahydrofuran, dimethyoxymethane, 1,3-dioxolane, acetonitrile, N-methyl-2-pyrrolidone, sulfoxide, dimethyl sulfoxide and sulfolane; at least one polyol; a reaction catalyst; a foam stabilizer; at least one additive selected from the group consisting of a flame retardant, a surfactant and an agent for stabilizing 1,1,3,3-pentafluoropropane, said agent for stabilizing 1,1,1,3,3-pentafluoropropane being either α-methyl syrene or isopropenyl toluene; and water.