Granted Patent B2

US 12,617,748 · App. 18/036,881 · Granted May 5, 2026

Inventors: Kasinath Bhaumik (Gujarat, IN); Anupam Acharya (Gujarat, IN); Madhu Sudhan Bhageria (New Delhi, IN); Ashok Chauhan (New Delhi, IN); Vyanu Vyas (Gujarat, IN)

Assignee: FILATEX INDIA LIMITED

C07C67/03B01J19/0013B01J19/245C08J11/24C08J2367/02

Abstract

Claims (57)

1 . A process for production of bis(2-hydroxyethyl) terephthalate (BHET) from polyethylene terephthalate (PET), said process comprising the steps of:

partially depolymerizing of the polyethylene terephthalate (PET) by mixing the polyethylene terephthalate (PET) with ethylene glycol in a weight ratio of PET:ethylene glycol ranging from 1:0.3 to 1:1.5 while maintaining temperature of the mixture in a range of 200° C. to 250° C. to obtain a partially depolymerized polyethylene terephthalate (PET), wherein the partial depolymerization is effected in absence of a depolymerization catalyst; and

depolymerizing the partially depolymerized polyethylene terephthalate (PET) by contacting the partially depolymerized polyethylene terephthalate (PET) with ethylene glycol in a weight ratio of PET:ethylene glycol ranging from 1:1 to 1:4 in presence of the depolymerization catalyst at a temperature ranging from 170° C. to 200° C. for a time period ranging from 2 hours to 5 hours, to produce crude product mixture comprising bis(2-hydroxyethyl) terephthalate (BHET).

2 . The process as claimed in claim 1 , wherein said polyethylene terephthalate (PET) comprises polyethylene terephthalate (PET) waste selected from the group consisting of at least one of: PET bottle flakes, PET yarn, PET thermoformed packages, PET fabric, bright PET yarn waste popcorn, semi dull PET yarn waste popcorn.

3 . The process as claimed in claim 1 , wherein said polyethylene terephthalate (PET) comprises polyethylene terephthalate (PET) waste having an intrinsic viscosity ranging from 0.5 to 0.8 as measured in 60:40 Phenol:Dichlorobenzene mixed solvent at 25° C., a melting point ranging from 240° C. to 260° C., and an ash content ranging from 0.03% to 2.0% by weight.

4 . The process as claimed in claim 1 , wherein the step of partial depolymerization of polyethylene terephthalate (PET) comprises:

exposing polyethylene terephthalate (PET) to a temperature ranging from 240° C. to 330° C. to obtain molten polyethylene terephthalate (PET); and

contacting the molten polyethylene terephthalate (PET) with hot ethylene glycol in a weight ratio of PET:ethylene glycol ranging from 1:0.3 to 1:1.5 while maintaining the temperature of the mixture in a range of 200° C. to 250° C. to obtain partially depolymerized polyethylene terephthalate (PET).

5 . The process as claimed in claim 4 , wherein the hot ethylene glycol has a temperature ranging from 180° C. to 190° C.

6 . A process for recycling of polyethylene terephthalate (PET) from polyethylene terephthalate (PET) waste, said process comprising the steps of:

partially depolymerizing the polyethylene terephthalate (PET) waste by mixing the polyethylene terephthalate (PET) waste with ethylene glycol in a weight ratio of PET:ethylene glycol ranging from 1:0.3 to 1:1.5 while maintaining a temperature of the mixture in a range of 200° C. to 250° C. to obtain a partially depolymerized polyethylene terephthalate (PET);

depolymerizing the partially depolymerized polyethylene terephthalate (PET) by contacting the partially depolymerized polyethylene terephthalate (PET) with ethylene glycol in a weight ratio of PET:ethylene glycol ranging from 1:1 to 1:4 in the presence of a depolymerization catalyst at a temperature ranging from 170° C. to 200° C. for a time period ranging from 2 hours to 5 hours to produce a crude product mixture comprising bis(2-hydroxyethyl) terephthalate (BHET);

purifying the crude product mixture to obtain purified bis(2-hydroxy ethyl) terephthalate BHET); and

polymerizing the purified bis(2-hydroxyethyl) terephthalate (BHET) in the presence of a polymerization catalyst at a temperature ranging from 200° C. to 300° C. and at a pressure ranging from 50 mbar to 2 mbar for a time period ranging from 2 hours to 5 hours to obtain the recycled polyethylene terephthalate (PET).

7 . The process as claimed in claim 6 , wherein the polyethylene terephthalate (PET) waste is selected from the group consisting of one or more of: PET bottle flakes, PET yarn, PET thermoformed packages, PET fabric, bright PET yarn waste popcorn, semi dull PET yarn waste popcorn, having an intrinsic viscosity ranging from 0.5 to 0.8 as measured in 60:40 Phenol:Dichlorobenzene mixed solvent at 25° C., a melting point ranging from 240° C. to 260° C., and an ash content ranging from 0.03% to 2.0%.

8 . The process as claimed in claim 6 , wherein the step of partial depolymerization of the polyethylene terephthalate (PET) waste comprises:

exposing the polyethylene terephthalate (PET) waste to a temperature ranging from 240° C. to 330° C. to obtain molten polyethylene terephthalate (PET); and

contacting the molten polyethylene terephthalate (PET) with hot ethylene glycol in a weight ratio of PET:ethylene glycol ranging from 1:0.3 to 1:1.5, to obtain partially depolymerized polyethylene terephthalate (PET).

9 . The process as claimed in claim 6 ,

wherein the depolymerization catalyst is a metal based catalyst, the metal being selected from the group consisting of at least one of zinc, titanium and antimony, and

wherein the polymerization catalyst is selected from the group consisting of Antimony Trioxide, Antimony Triacetate, Antimony Glycolate, and Germanium Dioxide.

10 . The process as claimed in claim 6 , wherein depolymerizing the partially depolymerized polyethylene terephthalate (PET) step comprises contacting the partially depolymerized polyethylene terephthalate (PET) with the ethylene glycol in the presence of the depolymerization catalyst comprising zinc acetate in an amount ranging from 400 ppm to 1400 ppm.

11 . The process as claimed in claim 6 , wherein the step of purification of the crude product mixture comprises:

filtering the crude product mixture;

crystallizing bis(2-hydroxyethyl) terephthalate (BHET) from the filtered crude product mixture;

separating crystallized bis(2-hydroxyethyl) terephthalate (BHET) to obtain a cake comprising bis(2-hydroxyethyl) terephthalate (BHET);

immersing the cake in a hot water in a weight ratio ranging from 1:4 to 1:8 to obtain an immersion mixture, said hot water having temperature ranging from 90° C. to 98° C.;

recrystallizing the bis(2-hydroxyethyl) terephthalate (BHET) from the immersion mixture; and

separating the recrystallized bis(2-hydroxyethyl) terephthalate (BHET) to obtain purified bis(2-hydroxyethyl) terephthalate (BHET).

12 . A method for production of bis(2-hydroxyethyl) terephthalate (BHET) from polyethylene terephthalate (PET), comprising:

feeding polyethylene terephthalate (PET) and ethylene glycol into a first reaction vessel, wherein polyethylene terephthalate (PET) and the ethylene glycol are in a weight ratio of PET:ethylene glycol ranging from 1:0.3 to 1:1.5;

maintaining the first reaction vessel at a temperature in a range of 200° C. to 250°, resulting in partially depolymerized polyethylene terephthalate (PET);

feeding the partially depolymerized polyethylene terephthalate (PET) and ethylene glycol into a second reaction vessel having a depolymerization catalyst, wherein the partially depolymerized polyethylene terephthalate (PET) and the ethylene glycol are in a weight ratio of PET:ethylene glycol ranging from 1:1 to 1:4; and

maintaining the second reaction vessel at a temperature ranging from 170° C. to 200° C. for a time period ranging from 2 hours to 5 hours, resulting in a crude product mixture comprising bis(2-hydroxyethyl) terephthalate (BHET),

wherein the first reaction vessel may be the same or different from the second reaction vessel;

and

wherein the depolymerization catalyst is not present in the first reaction vessel when the polyethylene terephthalate (PET) and ethylene glycol are fed into the first reaction vessel.

13 . The system method as claimed in claim 12 , wherein said polyethylene terephthalate (PET) comprises polyethylene terephthalate (PET) waste selected from the group consisting of at least one of: PET bottle flakes, PET yarn, PET thermoformed packages, PET fabric, bright PET yarn waste popcorn, semi dull PET yarn waste popcorn.

14 . The method as claimed in claim 12 , wherein said polyethylene terephthalate (PET) comprises polyethylene terephthalate (PET) waste having an intrinsic viscosity ranging from 0.5 to 0.8 as measured in 60:40 Phenol:Dichlorobenzene mixed solvent at 25° C., a melting point ranging from 240° C. to 260° C., and an ash content ranging from 0.03% to 2.0% by weight.

15 . The method as claimed in claim 12 ,

further comprising heating

the polyethylene terephthalate (PET) in the first vessel to a temperature ranging from 240° C. to 330° C. to obtain molten polyethylene terephthalate (PET), and

receiving hot ethylene glycol in the first vessel and mixing the received hot ethylene glycol with the molten polyethylene terephthalate (PET) in a weight ratio of PET:ethylene glycol ranging from 1:0.3 to 1:1.5, while maintaining the mixture at a temperature in a range of 200° C. to 250° C.,

to obtain the partially depolymerized polyethylene terephthalate (PET).

16 . The method as claimed in claim 15 , wherein the hot ethylene glycol is received into the first vessel at a temperature ranging from 180° C. to 190° C.

17 . The method as claimed in claim 12 , wherein the depolymerization catalyst comprises zinc acetate present in the second vessel in an amount ranging from 400 ppm to 1400 ppm.

18 . The process as claimed in claim 1 , further comprising:

purifying the crude product mixture to obtain purified bis(2-hydroxy ethyl) terephthalate (BHET); and

polymerizing the purified bis(2-hydroxyethyl) terephthalate (BHET) in the presence of a polymerization catalyst at a temperature ranging from 200° C. to 300° C. and at a pressure ranging from 50 mbar to 2 mbar for a time period ranging from 2 hours to 5 hours to obtain the recycled polyethylene terephthalate (PET).

19 . The process as claimed in claim 18 , wherein the step of purifying comprises:

filtering the crude product mixture;

crystallizing bis(2-hydroxyethyl) terephthalate (BHET) from the filtered crude product mixture;

separating crystallized bis(2-hydroxyethyl) terephthalate (BHET) to obtain a cake comprising bis(2-hydroxyethyl) terephthalate (BHET);

immersing the cake in a hot water in a weight ratio ranging from 1:4 to 1:8 to obtain an immersion mixture, said hot water having temperature ranging from 90° C. to 98° C.;

recrystallizing the bis(2-hydroxyethyl) terephthalate (BHET) from the immersion mixture; and

separating the recrystallized bis(2-hydroxyethyl) terephthalate (BHET) to obtain purified bis(2-hydroxyethyl) terephthalate (BHET).

20 . The process as claimed in claim 6 , wherein the depolymerizing is conducted at a temperature ranging from 180° C. to 190° C.

Assignments (2)

Priority Claims (1)

Continuity (1)

References Cited (17)