Polyol, polyurethane resin and utilization thereof

A polyol prepared by adding an alkylene oxide to at least one compound having at least one ester bond per molecule, said compound(s) being the reaction product of an organic polycarboxylic acid or anhydride thereof, with one or more compounds selected from the group consisting of:

• (a) polyhydric alcohols having from 3 to 8 hydroxyl groups per molecule, and
• (b) polyoxyalkylene polyols having from 3 to 8 hydroxyl groups per molecule, wherein the organic polycarboxylic acid or anhydride thereof is reacted in an amount of from 0.125 to 1.0 mole per one mole of hydroxyl groups of compounds (a) and/or (b), and wherein said polyol is effective for providing a rigid polyurethane foam upon mixing and reacting an organic polyisocyanate with a resin premix comprising said polyol at an equivalent ratio of polyisocyanate to hydroxyl group in the resin premix of from about 0.8 to 5.0, which rigid polyurethane foam is foamed by a solvent selected from the group of 2,2-dichloro-1,1,1-trifluoroethane, 1,1-dichloro-1-fluoroethane, 1,1,1,2-tetrafluoroethane, 1,1-difluoroethane and mixtures thereof, yet maintains a closed cell content substantially the same as that obtained by CFC foaming agents.