Method for the Depolymerization of a Terephthalate Polyester

Simple SummaryContent extracted from patent full text and abstract with AI.

This patent describes a new method for breaking down (depolymerizing) terephthalate polyesters, especially PET, into their monomer components using methanol and dimethyl terephthalate (DMT) in the presence of a zinc-based catalyst and heat (preferably microwave heating). By adding DMT at the start, the process improves solubility, reduces the amount of methanol needed, eliminates the need for harmful solvents, and achieves faster and highly efficient recycling. The resulting monomers (DMT and the appropriate diol) can be used to make new polyester via repolymerization, enabling a virtually waste-free closed recycling loop.

Use CasesContent extracted from patent full text and abstract with AI.

• Chemical recycling of waste PET bottles and containers into raw materials for new PET production.
• Recycling of polyester fibers from used textiles and clothing back into new high-quality polyester products.
• Processing of mixed or contaminated PET/polyester waste streams where mechanical recycling is ineffective.
• Depolymerization and recycling of other terephthalate polyesters such as PBT or PPT.
• Industrial-scale polyester plastic recycling facilities seeking more efficient and sustainable chemical recycling methods.

BenefitsContent extracted from patent full text and abstract with AI.

• Allows efficient recycling of terephthalate polyesters regardless of initial material quality or contamination.
• Significantly reduces the amount of methanol and eliminates the need for hazardous solvents in the process, making it cleaner and more sustainable.
• Faster reaction times (minutes instead of hours), improving process throughput and energy efficiency.
• Achieves very high depolymerization yields (>99% demonstrated for PET from bottles and packaging).
• Produces high-purity monomers that are directly compatible with industrial polyester manufacturing, enabling a true closed-loop recycling system.
• Can process a wide range of polyester waste products, including colored, blended, or contaminated materials.

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Inventors & Applicants

Patent Abstract

The invention relates to a method for the depolymerization of a terephthalate polyester, for example a PET polymer. The method comprises the steps of:a) contacting a terephthalate polyester with methanol and dimethyl terephthalate, DMT; andb) heating the mixture of the terephthalate polyester, methanol and DMT in the presence of a catalyst suitable for catalyzing the depolymerization of the terephthalate polyester.