Method for alcoholysis of polycarbonate compositions containing flame retardant or acrylonitrile-butadiene-styrene

A method for alcoholysis of a polycarbonate-containing composition comprising a polycarbonate and a component comprising a phosphorus-containing flame retardant, acrylonitrile-butadiene-styrene, or a combination of the phosphorus-containing flame retardant and acrylonitrile-butadiene-styrene, the method comprising

• contacting the composition with a solvent that forms a solution of the polycarbonate but not the component;
• separating the solution from the component;
• recovering the polycarbonate from the solution;
• and
• heating the recovered polycarbonate in the presence of an alcohol and a catalyst at a temperature from 70° C. to 200° C., and a pressure from 5 mbar to 40 bar for a time sufficient to depolymerize the polycarbonate to provide a dihydroxy aromatic compound and a dialkyl carbonate.

A method to separate a phosphorus-containing flame retardant, acrylonitrile-butadiene-styrene, and a polycarbonate, comprising

• contacting a mixture comprising a phosphorus-containing flame retardant, acrylonitrile-butadiene-styrene and a polycarbonate with a first solvent that selectively dissolves the flame retardant and forms a filterable suspension of acrylonitrile-butadiene-styrene but not the polycarbonate;
• separating the solubilized flame retardant and the filterable acrylonitrile-butadiene-styrene as a mixture from the polycarbonate;
• removing the first solvent from the mixture to provide a solid containing the flame retardant and acrylonitrile-butadiene-styrene;
• contacting the solid with a second solvent which selectively dissolves the flame retardant, but not acrylonitrile-butadiene-styrene;
• and
• separating dissolved flame retardant from acrylonitrile-butadiene-styrene.