Patent ID: 7959807
Filing Date: 2011-06-14
Classification: B01D,C07C,C08J,C09B,D06P,Y02W

Abstract:
1. A method for recovering useful components from a dyed polyester fiber, comprising a dye extraction step, a solid liquid separation step, a depolymerization reaction step, an ester interchange reaction step, and a useful component separation step, the dye extraction step being a step of extracting and removing a dye at the glass transition temperature of the polyester or higher and at 220° C. or less by an extracting solvent including xylene and alkylene glycol from the dyed polyester fiber, the solid liquid separation step being a step of separating a dye-extracted polyester fiber and a dye-containing extracting solvent after the dye extraction step, the depolymerization reaction step being a step of allowing the dye-extracted polyester fiber to undergo a depolymerization reaction with alkylene glycol in the presence of a depolymerization catalyst, thereby to obtain a depolymerized solution containing bis-ω-hydroxy alkylene terephthalate, the ester interchange reaction step being a step of allowing the depolymerized solution to undergo an ester interchange reaction by an ester interchange catalyst and methanol, and the useful component separation step being a step of separating and recovering dimethyl terephthalate and alkylene glycol from the ester interchange reaction product mixture obtained in the ester interchange reaction step.