Patent ID: 7192988
Filing Date: 2007-03-20
Classification: C08J,Y02W

Abstract:
1. A method for removing colorants from colored polyester waste wherein the method comprises the following sequential steps: a. depolymerizing said colored polyester by adding a glycol to said polyester at a temperature in the range of from 180° C. to 280° C. for a period of from one to five hours to produce a glycolyzed monomer; b. optionally filtering specific contaminants from said glycolyzed monomer; c. feeding said glycolyzed monomer through a bed of activated carbon to remove some colorant; d. extracting the remaining colorant from said glycolyzed monomer by introducing said glycolyzed monomer to a stirred reactor along with an extraction solvent at a temperature that is below the temperature of the glycolyzed monomer, said extraction solvent being selected from water, methanol, or a glycol whereby the glycolyzed monomer precipitates out and the remaining colorant transfers to the extraction solvent; and e. separating said glycolyzed monomer from the extraction solvent.