Hybrid polyester-polyether polyols for improved demold expansion in polyurethane rigid foams

Abstract

The present invention discloses polyester-polyether polyols suitable for blending with other polyols or other materials mutually compatible with the polyester polyols to achieve polyurethane and polyisocyanurate products. In particular the present invention discloses polyester-polyether polyols produced by the reaction of: 1) phthalic anhydride with an alcohol having a nominal functionality of 3 and a molecular weight of 90 to 500 under conditions to form a phthalic anhydride half-ester; and 2) alkoxylating the half-ester formed in step 1 to form a polyester-polyether polyol having a hydroxyl number of from 200 to 350; with the proviso when the alcohol is a polyether polyol, the polyether polyol contains at least 70 weight percent of polyoxypropylene.

Dependencies are inferred from the claim text.