A method for dissolving and recovering pet

CN121873426BActive Publication Date: 2026-06-23TIANJIN POLYTECHNIC UNIV +1
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Patent Information

Authority / Receiving Office
CN · China
Patent Type
Patents(China)
Current Assignee / Owner
TIANJIN POLYTECHNIC UNIV
Filing Date
2026-03-18
Publication Date
2026-06-23

AI Technical Summary

Technical Problem

Existing solvent dissolution methods for PET recycling suffer from high toxicity and cost. Furthermore, high temperatures can easily lead to the breakage and depolymerization of PET molecular chains, affecting the molecular weight and mechanical properties of the recycled PET.

Method used

A mixed solvent system of propylene carbonate and/or ethylene carbonate with diaryl ethers was used to dissolve PET at 160-200°C. The PET was then precipitated by adding water as an antisolvent. Combined with appropriate stirring and temperature control, the depolymerization reaction was suppressed, thereby improving the molecular weight retention and thermal stability of PET.

Benefits of technology

It efficiently dissolves PET under mild conditions, maintaining molecular weight and mechanical properties, with a recovery rate of over 95%, resulting in products with performance comparable to virgin PET. It is low-cost and environmentally friendly, making it suitable for large-scale industrial applications.

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Abstract

The application provides a method for dissolving and recycling PET, comprising the following steps: 1) mixing the PET to be recycled with a mixed solvent system composed of a good solvent and a di-arylether under the protection of an inert atmosphere, stirring and dissolving under a first temperature condition to obtain a first material; the good solvent is propylene carbonate and / or ethylene carbonate; the di-arylether is at least one of diphenyl ether, butyl phenyl ether and dibenzyl ether; the first temperature is 160-200 DEG C; 2) cooling the first material to a second temperature, adding anti-solvent water to precipitate and separate out the PET; 3) separating, washing and drying the material obtained in the step 2) to obtain the recycled PET. The method for dissolving and recycling PET has the whole process in line with the green development route, effectively avoids the problem of degradation of the PET under high temperature dissolving, and the performance of the recycled PET is comparable to that of the raw material. Meanwhile, the PET yield can be as high as 97%, and the method has important large-scale industrial application value.
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Citation Information

Patent Citations

  • Polyester polymer recovery from dyed polyester fabrics

    US4003881A

  • Process for recycling mixed polymer containing polyethylene terephthalate

    US5554657A