Patent ID: 8318829

Claim:
A process for preparing a rigid polyurethane foam, comprising a) forming a reactive mixture consisting of 1) a polyol mixture that contains 5 to 50% by weight of (i) a methylene bis(cyclohexylamine)-initiated polyol having an average hydroxyl functionality of 3.7 to 4.0 and a hydroxyl equivalent weight of from 100 to 130, the methylene bis(cyclohexylamine)-initiated polyol being a reaction product of ethylene oxide, propylene oxide or a mixture of ethylene oxide and propylene oxide with a methylene bis(cyclohexylamine) initiator compound, (ii) 20 to 70% of a sorbitol or sucrose and glycerine initiated polyether polyol having an average functionality of 4.5 to 7 hydroxyl groups and a hydroxy equivalent weight of 100 to 175 (iii) 2 to 20% by weight of an ethylenediamine-initiated polyol having an equivalent weight of 100 to 225 and (iv) 0 to 15% by weight of a non-amine-initiated polyol having a functionality of 2.0 to 3.0 and a hydroxyl equivalent weight of 200 to 500; 2) at least one hydrocarbon, hydrofluorocarbon, hydrochlorofluorocarbon, fluorocarbon, dialkyl ether or fluorine-substituted dialkyl ether physical blowing agent; 3) water; 4) at least one polyisocyanate; 5) one or more catalysts for the reaction of the polyols and water with the polyisocyanate; 6) a surfactant; and 7) optionally one or more of a filler, a colorant, an odor mask, a flame retardant, a biocide, an antioxidant, a UV stabilizer, an antistatic agent; and b) subjecting the reactive mixture to conditions such that the reactive mixture expands and cures to form a rigid polyurethane foam.