METHOD OF PROCESSING POLYETHYLENE-TEREPHTHALATE- CONTAINING MATERIALS WITH REMOVAL OF IMPURITIES FROM POLYETHYLENE-TEREPHTHALATE (VERSIONS) Russian patent published in 1999 - IPC

FIELD: polymer materials. SUBSTANCE: polyethylene-terephthalate is freed of impurities by transesterification of polyethylene-terephthalate-containing material with ethylene glycol at boiling temperature of ethylene glycol or temperature close to the latter during period of time sufficient to produce solution containing oligomers of polyethylene-terephthalate and/or bis(hydroxyethyl)terephthalate. Oligomers, ester, and ethylene glycol are then isolated and the two former are hydrolyzed at elevated temperature during period of time sufficient to form ethylene glycol solution and terephthalic acid crystals. Two other variations of this method are also described. EFFECT: simplified process. 37 cl, 6 ex