Method of recycling a polyester

Patent metadata

Field	Value
Publication number	US-10259768-B2
Application number	US-201815986930-A
Country	US
Kind code	B2
Filing date	May 23, 2018
Priority date	May 24, 2017
Publication date	Apr 16, 2019
Grant date	Apr 16, 2019

Abstract

A method of recycling a polyester includes the steps of providing the polyester, preparing a solution containing water and an alcohol, submerging the polyester in the solution, and hydrolytically depolymerizing the polyester while the polyester is submerged in the solution.

First claim

What is claimed is:

1. A method of recycling a polyester, with said method comprising the steps of:
preparing a solution containing water and an alcohol;
submerging a poly(lactic acid) in the solution; and
hydrolytically depolymerizing the poly(lactic acid) while the poly(lactic acid) is submerged in the solution.

2. The method according to claim 1 wherein the step of preparing the solution is further defined as preparing the solution containing from 20 to 70 percent by volume of the alcohol and the balance being the water, based on a total of 100 percent by volume of the solution.

3. The method according to claim 1 wherein the step of preparing the solution is further defined as preparing the solution containing from 40 to 50 percent by volume of the alcohol and the balance being water, based on a total of 100 percent by volume of the solution.

4. The method according to claim 1 wherein the step of preparing the solution is further defined as preparing the solution containing 50 percent by volume of the alcohol and 50 percent by volume of water.

5. The method according to claim 1 wherein the step of preparing a solution is further defined as preparing a solution of water and an alcohol selected from ethanol, methanol, 1-butanol, and 1-propanol.

6. The method according to claim 1 wherein the alcohol is further defined as ethanol and the step of preparing the solution is further defined as preparing the solution containing the ethanol and the water.

7. The method according to claim 6 wherein the step of preparing the solution is further defined as preparing the solution containing from 40 to 50 percent by volume of ethanol and the balance being water, based on a total of 100 percent by volume of the solution.

8. The method according to claim 1 wherein the alcohol is further defined as 1-butanol and the step of preparing the solution is further defined as preparing the solution containing from 20 to 30 percent by volume of 1-butanol and the balance being water, based on a total of 100 percent by volume of the solution.

9. The method according to claim 1 wherein the step of preparing a solution is further defined as preparing a solution of water and an alcohol with the solution having a pH of from 10 to 14.

10. The method according to claim 1 wherein the step of hydrolytically depolymerizing the poly(lactic acid) is further defined as hydrolytically depolymerizing the poly(lactic acid) while submerged in the solution at a temperature of from 40 to 90° C.

11. The method according to claim 1 wherein the water is further defined as heavy water and the step of preparing the solution is further defined as preparing the solution containing the heavy water and the alcohol.

12. The method according to claim 1 wherein the method further comprises the step of forming the poly(lactic acid) into a film having a thickness of from 18 to 38 micrometers.

13. The method according to claim 12 further comprising the step of cutting the film into a plurality of pieces prior to the step of submerging the poly(lactic acid) in the solution.

14. The method according to claim 12 wherein the step of preparing the solution is performed independent of the step of forming the film.

15. The method according to claim 1 wherein the step of submerging the poly(lactic acid) includes submerging the poly(lactic acid) in the solution for a time period of from 6 to 3000 hours.

16. The method according to claim 1 wherein the poly(lactic acid) has at least 100,000 monomer units.

17. The method according to claim 1 wherein the poly(lactic acid) has a number average molecular weight of from 1.21×10 3 to 1.21×10 6 Daltons.

18. A method of recycling a polyester, with said method comprising the steps of:
preparing a solution containing water and an alcohol;
submerging a polyglycolic acid in the solution; and
hydrolytically depolymerizing the polyglycolic acid while the polyglycolic acid is submerged in the solution.

Assignees

• Univ Michigan State

Inventors

• Auras Rafael
• Iñiguez-Franco Fabiola Maria
• Rubino Maria
• Holmes Daniel
• Selke Susan E
• Fang Xiaoyi

Classifications

• C08J2367/04

  Polyesters derived from hydroxy carboxylic acids, e.g. lactones (C08J2367/06 takes precedence) · CPC title

• C08J11/14

  by treatment with steam or water · CPC title

• C08J5/18

  Manufacture of films or sheets · CPC title

• C07C51/09 Primary

  from carboxylic acid esters or lactones · CPC title

• Y02W30/62

  Plastics recycling; Rubber recycling · CPC title