摘要 |
Processes are disclosed for recovery and purification of dibasic aromatic acids or esters thereof from waste polyester film, fiber, bottles, manufacturing residues, and other manufactured articles. The processes comprise: depolymerization of polyester resin in a liquid solvent under conditions of elevated temperature and pressure suitable for opening of ester bonds to form a solution of dibasic aromatic acid or ester, polyol, organic impurities, and other components of the resin; crystallization of the dibasic aromatic acid or ester from the solution by flash crystallization to form a vapor containing a major mount of the polyol and solvent, and a slurry of dibasic aromatic acid or ester crystals in mother liquor; separation of crude dibasic aromatic acid or ester from the mother liquor; crystallization of retained organic impurities from the mother liquor solution by flash crystallization to a pressure in a range downward from about one atmosphere to form a slurry of mother liquor solids; recovery of mother liquor solids from the slurry; and recycle of the recovered mother liquor solids to the depolymerization.
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