Polyols and process for their preparation from PET-waste or waste from the PET-production

摘要

The prodn. of polyols in the form of bifunctional aromatic polyester-alcohols (I) from scrap PET or PET prodn. waste comprises (a) dissolving the waste material in diethylene glycol (DEG) in amts. such that the polyester-alcohol obtd. after trans-esterification has an OH no. of 700 mg KOH/g, (b) trans-esterification in the presence of suitable known catalysts, after removing any undissolved solid if necessary, with distn. of at least some of the liberated ethylene glycol (EG), and (c) removal of free DEG by distn. of the equilibrium mixt. obtd. at 140 degrees C, to give a polyester-alcohol with an OH no. of 260-500. Also claimed is a storable polyol with an OH no. of 260-500 as above, with a content of higher oligomers which is lower than the equilibrium content for the OH no. of the prod..