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Process for recycling polyester materials

  • US 7,192,988 B2
  • Filed: 09/30/2004
  • Issued: 03/20/2007
  • Est. Priority Date: 09/30/2004
  • Status: Expired due to Fees
First Claim
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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.

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