Method for direct ammonolysis of polycarbonate-containing materials and products

Patent metadata

Field	Value
Publication number	US-9328046-B2
Application number	US-201314053954-A
Country	US
Kind code	B2
Filing date	Oct 15, 2013
Priority date	Oct 15, 2013
Publication date	May 3, 2016
Grant date	May 3, 2016

Abstract

A method for recovering a dihydroxy aromatic compound and urea from a polycarbonate-containing composition comprising a polycarbonate and a phosphorus-containing flame retardant, comprising contacting the composition with ammonia in the presence of a swelling solvent for a time sufficient to depolymerize the polycarbonate producing a dihydroxy aromatic compound and urea.

First claim

We claim:

1. A method for recovering a dihydroxy aromatic compound from a polycarbonate-containing composition comprising contacting the polycarbonate-containing composition with ammonia and a swelling solvent during substantially coextensive periods at a temperature of from 50° C. to 100° C. for a time sufficient to depolymerize the polycarbonate to provide a dihydroxy aromatic compound and urea and to obtain insoluble polymer, other than polycarbonate, that retains a physical appearance which enables its recycle.

2. The method of claim 1 , wherein the composition comprises from 10 to 90 weight percent polycarbonate.

3. The method of claim 1 , wherein the composition comprises from 10 to 70weight percent polycarbonate.

4. The method of claim 1 , wherein the composition comprises from 20 to 50weight percent polycarbonate.

5. The method of claim 1 , wherein the composition comprises from 12 to 30weight percent polycarbonate.

6. The method of claim 1 , wherein the swelling solvent is a C 1-10 alcohol or a ketone.

7. The method of claim 6 , wherein the swelling solvent is methanol.

8. The method of claim 1 , wherein the method further comprises separating the dihydroxy aromatic compound and the urea from the solid residual polymeric composition by filtration.

9. The method of claim 1 , further comprising separating a blend of the swelling solvent and the urea from the dihydroxy aromatic compound by distillation.

10. The method of claim 1 , wherein the polycarbonate is bisphenol A polycarbonate, and the dihydroxy aromatic compound is bisphenol-A.

11. The method of claim 1 , wherein the polycarbonate-containing composition, in addition to comprising 10 to 90 weight percent polycarbonate, further comprises a phosphorus-containing flame retardant selected from the group consisting of bisphenol A bis(diphenyl phosphate), resorcinol bis(diphenyl phosphate), and a combination thereof.

12. The method of claim 1 , wherein the urea is isolated.

13. The method of claim 1 , wherein the urea obtained by the depolymerization of the polycarbonate is further reacted to form CO 2 and NH 3 .

14. The method of claim 13 , wherein the NH 3 is reused in the process.

15. The method of claim 1 , wherein the dihydroxy aromatic compound obtained by the depolymerization of the polycarbonate is further processed to reduce the color thereof.

16. The method of claim 15 , wherein the further processing is selected from the group of solvent recrystallization or exposure to adsorbent or chelants to bind impurities.

17. A method for recovering a dihydroxy aromatic compound from a polycarbonate-containing composition containing 10 weight percent to 90 weight percent of a polycarbonate, acrylonitrile-butadiene-styrene, and phosphorous-containing flame retardant, which method comprises contacting the composition with ammonia and, as a swelling solvent, which swelling agent comprises a C 1-10 alcohol or ketone, during substantially coextensive periods at a temperature of from 50° C. to 100° C. for a time sufficient to depolymerize the polycarbonate to provide a dihydroxy aromatic compound, urea, and insoluble acrylonitrile-butadiene-styrene as pellets or flakes that retain a physical appearance that enables their recycle, wherein the method further comprises separating the dihydroxy aromatic compound and the urea from the insoluble acrylonitrile-butadiene-styrene by filtration and then separating a blend of the alcohol or ketone and the urea from the dihydroxy aromatic compound by distillation.

18. The method of claim 17 wherein the polycarbonate-containing composition is electronic waste consisting of polycarbonate, acrylonitrile-butadiene-styrene, and phosphorous-containing flame retardant and wherein the polycarbonate content is 10 to 70 weight percent.

19. The method of claim 17 wherein the polycarbonate- containing composition has a polycarbonate content that is 10 to 50 weight percent.

Assignees

• Saudi Basic Ind Corp

Inventors

• Stanislaus Alexander
• Ganapathy Bhotla Venkata Ramanarayanan
• Sreenivasan P S
• Bell Philip Wesley

Classifications

• C08J11/16 Primary

  by treatment with inorganic material (C08J11/14 takes precedence) · CPC title

• Y02W30/705

  Cross-Sectional Technologies · mapped topic

• C08G64/38

  using other monomers · CPC title

• C08J2369/00

  Characterised by the use of polycarbonates; Derivatives of polycarbonates · CPC title

• C07C37/00 Primary

  Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom of a six-membered aromatic ring · CPC title