US 12,473,418 B2
Method of manufacturing for terephthalic acid using polyethylene terephthalate with high degree of polymerization more than 0.75 dl/g of intrinsic viscosity
Yong-Bum Kim, Seoul (KR)
Filed by Yong-Bum Kim, Seoul (KR)
Filed on Jun. 9, 2022, as Appl. No. 17/836,385.
Claims priority of application No. 10-2021-0127706 (KR), filed on Sep. 28, 2021.
Prior Publication US 2023/0107495 A1, Apr. 6, 2023
Int. Cl. C08J 11/16 (2006.01)
CPC C08J 11/16 (2013.01) [C08J 2367/02 (2013.01)] 7 Claims
 
1. A method for production of terephthalic acid using a high polymerization degree polyethylene terephthalate having an intrinsic viscosity of 0.75 dl/g or more, the method comprising:
(i) introducing polyethylene terephthalate (PET) having a polymerization degree of 0.75 dl/g or more into a continuous reactor in the form of an extruder, and then heating and pressurizing the same to prepare a fluidal polyethylene terephthalate;
(ii) introducing a mixed slurry prepared by mixing an alkaline material (abbrev. to “alkali”) containing an alkali-metal, a weak acid salt of the alkali-metal and ethylene glycol together into an internal position of the continuous reactor, through which the fluidal polyethylene terephthalate passes, and implementing neat reaction of the fluidal polyethylene terephthalate with the mixed slurry in the continuous reactor to prepare alkali-metal terephthalate; and
(iii) dissolving the prepared alkali-metal terephthalate in water, removing foreign substances through filtration and centrifugation, adding acid to the alkali-metal terephthalate dissolved in water and reacting the same, thereby producing terephthalic acid.