Abstract: A method, according to one embodiment, depolymerizes waste polyester by means of a multi-step reaction, wherein a latter reaction is carried out at a low temperature, and ion exchange, etc., is further carried out, thereby enabling the provision of high-purity and high-quality recycled bis(2-hydroxyethyl) terephthalate having reduced generation of diethylene glycol-derived impurities and oligomers.

Abstract: A method for producing bis(2-hydroxyethyl)terephthalate is disclosed. The method includes recovering and reusing ethylene glycol with an acetate removed, after the glycolysis of a waste polyester. According to the method, an acetate is not concentrated even though ethylene glycol is reused in a continuous process, leading to bis(2-hydroxyethyl)terephthalate with excellent purity and quality.

Abstract: A polymerization raw material obtained by the depolymerization of waste polyester is disclosed. The polymerization raw material contains recycled bis(2-hydroxyethyl) terephthalate in which the contents of acetate-based ester compounds and diethylene glycol ester compounds are adjusted to specific levels. The polymerization raw material is excellent in purity and quality, and free from the problem that thermal resistance characteristics deteriorate in the polymerization of a polymer from the recycled monomer.

Abstract: A method for producing bis-2-hydroxyethyl terephthalate is disclosed. The method includes the steps of: (1) adding a waste polyester raw material into a co-extruder to obtain a co-extrudate; (2) adding the co-extrudate into a reactor with an agitation shaft and depolymerizing same to obtain a first reaction product; (3) adding the first reaction product into a first continuous stirred tank reactor and depolymerizing same to obtain a second reaction product; and (4) adding the second reaction product into a second continuous stirred tank reactor and depolymerizing same to obtain a third reaction product.