The recovery of polyethylene terephthalate (PET) is generally carried out by a solvent decomposition method, which is a commercial scale recovery method, including the dimethyl terephthalate (DMT) method and double-2 of Japan Teijin Fiber Co., Ltd. - Hydroxyethyl terephthalate (BHET) method or the like. Almost all of these methods use the alcohols such as methanol or ethylene glycol (EG) for the decomposition of PET. Plastic precision optical lens mold Dongguan Lianlong Photoelectric Technology Co., Ltd , https://www.lianlonggd.com
The DMT method is a method in which Glycol (ethylene glycol) is used for glycolysis, and the recovered PET crumb is decomposed into BHET, and then methanol is added to carry out methanolysis (methanolysis) to obtain DMT. When ethylene glycol is decomposed into PET, an alkaline carbonate is added, and after BHET is formed at a temperature lower than the boiling point of ethylene glycol, separation and recovery are carried out. Further, methanol is added to the crude BHET to decompose it, thereby producing a crude DMT. After the crude DMT is crystallized, it is refined and distilled to obtain 99.99% of high-purity DMT.
This DMT process has been built in Japan's Teijin Fiber for the DMT plant for bottle making, with an annual production capacity of 30,000 metric tons, and a factory for polyester fiber. In addition, the plant for the production of terephthalic acid (PTa) by high-purity DMT and water-decomposition has been officially put into operation, and it has a scale of 62,000 metric tons per year and is a "bottle to bottle" factory.