Method for direct ammonolysis of polycarbonate-containing materials and products

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.

I/We claim: 
     
         1 . (canceled) 
     
     
         2 . The method of  claim 22 , wherein the composition comprises from 10 to 90 weight percent polycarbonate. 
     
     
         3 . The method of  claim 22 , wherein the composition comprises from 10 to 70 weight percent polycarbonate. 
     
     
         4 . The method of  claim 22 , wherein the composition comprises from 20 to 50 weight percent polycarbonate. 
     
     
         5 . The method of  claim 22 , wherein the composition comprises from 12 to 30 weight percent polycarbonate. 
     
     
         6 . (canceled) 
     
     
         7 . The method of  claim 22 , wherein the C 1-10  alcohol is methanol. 
     
     
         8 . (canceled) 
     
     
         9 . (canceled) 
     
     
         10 . The method of  claim 22 , wherein the polycarbonate is bisphenol A polycarbonate, and the dihydroxy aromatic compound is bisphenol-A. 
     
     
         11 . The method of  claim 22 , wherein the phosphorus-containing flame retardant is bisphenol A bis(diphenyl phosphate), resorcinol bis (diphenyl phosphate), or a combination thereof. 
     
     
         12 . A method for the manufacture of a polycarbonate, the method comprising recovering the dihydroxy aromatic compound generated in  claim 22 , and polymerizing the dihydroxy aromatic compound and a carbonyl source to provide the polycarbonate. 
     
     
         13 . (canceled) 
     
     
         14 . (canceled) 
     
     
         15 . (canceled) 
     
     
         16 . (canceled) 
     
     
         17 . (canceled) 
     
     
         18 . The method of  claim 22 , wherein the dihydroxy aromatic compound is further processed to reduce the color thereof. 
     
     
         19 . The method of  claim 18 , wherein the further process is selected from the group of solvent recrystallization or exposure to adsorbent or chelants to bind impurities. 
     
     
         20 . (canceled) 
     
     
         21 . (canceled) 
     
     
         22 . A method for recovering a dihydroxy aromatic compound from a polycarbonate-containing composition comprising a polycarbonate and a component comprising a phosphorus-containing flame retardant, or acrylonitrile-butadiene-styrene, or a combination of the phosphorus-containing flame retardant and acrylonitrile-butadiene-styrene, the method comprising:
 contacting the polycarbonate-containing composition with ammonia for a time sufficient to depolymerize the polycarbonate to provide a dihydroxy aromatic compound and urea in a liquid phase and a solid residual polymeric composition having dihydroxy aromatic compound adhering to its surface;   separating the solid residual polymeric composition from the liquid phase; and   washing the solid polymeric composition with a C 1-10  alcohol to recover additional dihydroxy aromatic compound.   
     
     
         23 . The method of  claim 22 , wherein the liquid solution is subjected to distillation to remove ammonia, methanol, and most of the water. 
     
     
         24 . The method of  claim 23 , wherein upon distillation, the ammonia salt of the dihydroxy aromatic compound is recovered as a solid. 
     
     
         25 . The method of  claim 24  wherein the ammonia salt of the dihydroxy aromatic compound is converted to the dihydroxy aromatic compound by treatment with water and heat. 
     
     
         26 . The method of  claim 25  wherein the dihydroxy aromatic compound is separated by filtration from urea in water.