| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a method for producing a high-purity polyethylene terephthalate by utilizing a used polyethylene terephthalate as bis-β-hydroxyethyl terephthalate. SOLUTION: This method comprises a pretreatment process for obtaining a crude polyethylene terephthalate, a depolymerization process for producing a crude bis-β-hydroxyethyl terephthalate (BHET) by adding an excess ethylene glycol for depolymerization, a foreign substance-removing process for removing the foreign plastics and solid foreign substances and/or precipitates other than the polyethylene terephthalate resin, a concentrated BHET producing process by distillation and vaporization, a vacuum vaporization process for obtaining a refined BHET, and a melt-polycondensation process for obtaining a high-purity polyethylene terephthalate polymer.</p> |
