METHOD FOR RECOVERY OF VALUABLE INGREDIENT FROM DYED POLYESTER FIBER

摘要

The object is to establish a method for recovering a variable ingredient which can recover a variable ingredient from a dyed polyester fiber at a high purity and which is efficient and economically advantageous. A method for the recovery of a variable ingredient from a dyed polyester fiber, the method comprising a dye extraction step in which a dye is extracted from the dyed polyester fiber, a solid/liquid separation step, a depolymerization step, a transesterification step and a step for separating the variable ingredient, the dye extraction step comprising extracting a dye with a combination of a xylene extraction solvent and an alkyleneglyol extraction solvent at a temperature ranging from the glass transition temperature of the polyester to 220°C inclusive and then removing the extracted dye.