METHOD FOR PRODUCING POLYESTER POLYOLS, POLYESTER POLYOLS PRODUCED BY SAID METHOD AND POLYURETHANES OBTAINED THEREFROM

摘要

A process for preparing a polyester polyol comprises the steps of: (a) preparing a reaction mixture comprising the following components: A: at least one carboxylic acid recovered from natural raw materials and having at least two acid groups, B: at least one polyhydric alcohol, C: at least one organic phosphite compound, D: at least one Lewis acid; (b) heating the reaction mixture to a temperature of at least 160° C. and removing the water formed in the course of the reaction; (c) heating the reaction mixture to a temperature of at least 210° C. under a pressure below 1013 mbar for a period of time in the range from 0.1 to 25 hours.