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.
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.
Abstract:
A method to produce a purified dihydroxy aromatic compound from a polycarbonate-containing composition is provided. The method includes depolymerizing the polycarbonate by alcoholysis using a titanium-based catalyst producing a dihydroxy aromatic compound and a dialkyl carbonate, recovering the dihydroxy aromatic compound as a crude dihydroxy aromatic compound; and contacting the recovered crude dihydroxyl aromatic compound with an acid in the presence of a solvent at an elevated temperature. Alternatively, the method comprises dissolving the recovered crude dihydroxyl aromatic compound in a solvent; contacting the dissolved crude dihydroxy aromatic compound with a base; and neutralizing the combination of the dissolved crude dihydroxy aromatic compound and the base with an acid.
Abstract:
The disclosure provides a method for recovering a dihydroxy aromatic compound and a dialkyl carbonate from a polycarbonate-containing composition comprising a polycarbonate and acrylonitrile-butadiene-styrene. The method comprises heating the composition in the presence of an alcohol and a transesterification catalyst at a temperature of 70° C. to 200° C. and a pressure of 50 mbar to 40 bar in a reactor for a time sufficient to depolymerize the polycarbonate producing a dihydroxy aromatic compound and a dialkyl carbonate; removing the dihydroxy aromatic compound and the dialkyl carbonate from the reactor, the acrylonitrile-butadiene-styrene remaining as a coating on the surfaces of the reactor; adding a solvent to the reactor; and heating the solvent to remove the acrylonitrile-butadiene-styrene from the surfaces of the reactor.
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.
Abstract:
The disclosure provides a method for alcoholysis of a polycarbonate-containing composition comprising a polycarbonate and a component comprising a phosphorus-containing flame retardant, an acrylonitrile-butadiene-styrene, or a combination of the phosphorus-containing flame retardant and acrylonitrile-butadiene-styrene. The method comprises contacting the composition with a solvent that forms a solution or a filterable suspension of the component but not the polycarbonate; separating the solution or the filterable suspension from the polycarbonate; and heating the 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 and produce a dihydroxy aromatic compound and a dialkyl carbonate.
Abstract:
The disclosure provides a method for alcoholysis of a polycarbonate-containing composition comprising a polycarbonate and a component comprising a phosphorus-containing flame retardant, an acrylonitrile-butadiene-styrene, or a combination of the phosphorus-containing flame retardant and acrylonitrile-butadiene-styrene. The method comprises contacting the composition with a solvent that forms a solution or a filterable suspension of the component but not the polycarbonate; separating the solution or the filterable suspension from the polycarbonate; and heating the 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 and produce a dihydroxy aromatic compound and a dialkyl carbonate.