Method for producing bis-2-hydroxyethyl terephthalate through continuous depolymerization
AssigneeSK Chemicals Co., Ltd.
InventorsJi-Hun Kim, Kwang-Woo Park, Seong-Ki Lee, Joong Ki Lee, Yuntae Jin
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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.
Claims15
A process for preparing bis(2-hydroxyethyl) terephthalate, which comprises steps of:
- (1) feeding a waste polyester raw material and a glycol based compound to a co-extruder to obtain a co-extrudate;
- (2) feeding the co-extrudate to an agitated shaft reactor and depolymerizing it to obtain a first reactant;
- (3) feeding the first reactant to a first continuous reactor and depolymerizing it to obtain a second reactant;
- and
- (4) feeding the second reactant to a second continuous reactor and depolymerizing it to obtain a third reactant,
- wherein, in step (3), a second glycol-based compound is continuously fed to the first continuous reactor in an amount of 50 to 340 parts by weight relative to 100 parts by weight of the first reactant,
- wherein the depolymerization in step (2) is carried out at 180 to 210° C.,
- wherein the depolymerization in step (4) is carried out at 140 to 170° C., and
- wherein a temperature of the depolymerization in step (2) is higher than a temperature of the depolymerization in steps (3) and (4).
Dependencies are inferred from the claim text.