Polyol compositions useful for preparing dimensionally stable, low density water-blown rigid foams and the processes related thereto

The present invention relates to polyol compositions which can be used to produce dimensionally stable, low density water-blown rigid foams which have acceptable compressive strengths and acceptable k-factors. In one embodiment of the present invention, the polyol compositions are composed of at least one aromatic amine-initiated polyether polyol and at least one polyether polyol having a functionality greater than or equal to 2.5 in which at least 50% by weight of the polyol composition is aromatic amine-initiated polyether polyol and in which no more than 50% by weight of the polyol composition is polyether polyol having a functionality greater than or equal to 2.5. In another embodiment of the present invention, the polyol compositions are composed of at least one aromatic amine-initiated polyether polyol and at least one polyester polyol in which at least 30% by weight of the polyol composition is aromatic amine-initiated polyether polyol and in which no more than 70% by weight of the polyol composition is polyester polyol.