Process for recycling mixed polymer containing polyethylene terephthalate

A process for recovering a polyester polymer from a mixed polymer recycle stream, while maintaining the polyester polymer in polymer form, comprising:

• contacting a mixed polymer recycle stream comprising at least 65 weight percent polyester polymer, lesser portions of other polymers, including one or more polyolefins, and impurities, with a chemical wash solvent selected from the group consisting of methyl ethyl ketone, tetrahydrofuran, and mixtures thereof, to form a chemical wash solution containing impurities dissolved in the chemical wash solvent, and a residual mixed polymer recycle stream;
• separating the chemical wash solution from the residual mixed polymer recycle stream;
• contacting, at an elevated temperature, the residual mixed polymer recycle stream with a selective solvent selected from the group consisting of dimethyl terephthalate, dimethyl phthalate, dimethyl isophthalate, dimethyl naphthalate, ethylene carbonate, propylene carbonate, and mixtures thereof, to form a residual waste stream, a separate polyolefin phase, and a selective solvent solution comprising the polyester polymer dissolved in the selective solvent;
• separating the selective solvent solution from the separate polyolefin phase, and from the residual waste stream;
• and
• precipitating the polyester polymer from the selective solvent solution, to form a precipitated polyester polymer and a spent selective solvent solution;
• separating the spent selective solvent from the precipitated polyester polymer, to obtain a recovered polyester polymer product having an intrinsic viscosity of from about 0.2 dl/g to about 0.8 dl/g;
• and
• combining the recovered polyester polymer, in a melt processing operation, with a virgin polyester polymer stream having a comparable molecular weight to produce a recycle-content polyester polymer product containing from about 15 weight percent to about 55 weight percent of the polyester polymer recovered from the mixed polymer recycle stream.

A process for recovering a polyester polymer from a mixed polymer recycle stream, while maintaining the polyester polymer in polymer form, comprising:

• contacting, at a first elevated temperature, a mixed polymer recycle stream comprising at least 50 weight percent polyester polymer, lesser portions of other polymers, including one or more polyolefins, and impurities, with a chemical wash solvent that dissolves any polyolefins present, and at least a portion of the impurities present in the mixed polymer recycle stream, and substantially rejects dissolution of the polyester polymer present in the mixed polymer recycle stream, to form a residual polymer recycle stream and a chemical wash solution comprising polyolefin polymer and impurities dissolved in the chemical wash solvent;
• separating the chemical wash solution from the residual polymer recycle stream;
• contacting, at a second elevated temperature, the residual polymer recycle stream with a selective solvent that selectively dissolves the polyester polymer and substantially rejects dissolution of other polymers present in the mixed polymer recycle stream, to form a selective solvent solution containing the polyester polymer dissolved in the selective solvent, and a residual waste stream;
• separating the selective solvent solution from the residual waste stream;
• precipitating the polyester polymer from the selective solvent solution, to form a precipitated polyester polymer and a spent selective solvent solution;
• and
• separating the spent selective solvent from the precipitated polyester polymer, to obtain a recovered polyester polymer product having an intrinsic viscosity of from about 0.2 dl/g to about 0.8 dl/g.

A process for recovering a polyester polymer from a mixed polymer recycle stream, while maintaining the polyester polymer in polymer form, comprising:

• contacting, at a first elevated temperature, a mixed polymer recycle stream comprising at least 50 weight percent polyester polymer, lesser portions of other polymers, including one or more polyolefins, and impurities, with a chemical wash solvent selected from the group consisting of cyclohexanone, alkyl-substituted cyclohexanones, diol diacetates, dibutyl phthalate, and mixtures thereof, to form a residual polymer recycle stream and a chemical wash solution comprising polyolefin polymer and impurities dissolved in the chemical wash solvent;
• separating the chemical wash solution from the residual polymer recycle stream;
• contacting, at a second elevated temperature, the residual polymer recycle stream with a selective solvent selected from the group consisting of dialkyl terephthalates, dimethyl phthalate, dialkyl isophthalates, dialkyl naphthalates, alkylene carbonates, and mixtures thereof, to form a selective solvent solution containing the polyester polymer dissolved in the selective solvent, and a residual waste stream;
• separating the selective solvent solution from the residual waste stream;
• precipitating the polyester polymer from the selective solvent solution, to form a precipitated polyester polymer and a spent selective solvent solution;
• separating the spent selective solvent from the precipitated polyester polymer, to obtain a recovered polyester polymer product having an intrinsic viscosity of from about 0.2 dl/g to about 0.8 dl/g;
• and
• combining the recovered polyester polymer, in a melt processing operation, with a virgin polyester polymer stream having a comparable molecular weight to produce a recycle-content polyester polymer product containing from about 15 weight percent to about 55 weight percent of the polyester polymer recovered from the mixed polymer recycle stream.

A process for recovering a polyester polymer from a mixed polymer recycle stream, while maintaining the polyester polymer in polymer form, comprising:

• contacting, at an elevated temperature, a mixed polymer recycle stream comprising at least 50 weight percent polyester polymer, lesser portions of other polymers, including one or more polyolefins, and impurities, with a selective solvent that selectively dissolves the polyester polymer and substantially rejects dissolution of the other polymers and impurities present in the mixed polymer recycle stream, to form a residual waste stream, a separate polyolefin phase, and a selective solvent solution comprising the polyester polymer dissolved in the selective solvent;
• separating the selective solvent solution from the separate polyolefin phase, and from the residual waste stream;
• precipitating the polyester polymer from the selective solvent solution, to form a precipitated polyester polymer and a spent selective solvent solution;
• separating the spent selective solvent and the precipitated polyester polymer, to obtain a recovered polyester polymer product having an intrinsic viscosity of from about 0.2 dl/g to about 0.6 dl/g;
• and
• combining, in a melt processing operation, the recovered polyester polymer product with a virgin polyester polymer product having a comparable intrinsic viscosity, to produce a recycle-content polyester polymer product containing at least 15 weight percent of the polyester polymer recovered from the mixed polymer recycle stream.