Patent ID: 6599950
Filing Date: 2003-07-29
Classification: B03B,B29B,B29K,C08J,Y02W

Abstract:
A method of separating a portion of acrylonitrile-butadiene-styrene (ABS) from a mixture containing ABS and for separating a portion of ABS and polycarbonate (PC) from a mixture of plastics containing ABS and PC comprising the steps of:shredding and/or granulating the mixture of plastics containing ABS and PC to provide a selected particle size; dispersing the shredded mixture of plastics in a first aqueous solution having a specific gravity of 1.04Â±0.01 g/cc, a pH in the range of 11.5Â±0.8 and a surface tension of 34Â±4 dynes/cm wherein a first reject fraction floats and a first retained fraction sinks, separating the first reject fraction from the first aqueous solution, introducing the first retained fraction into a second aqueous solution having a specific gravity of 1.09Â±0.01 g/cc and a pH in the range of 11.5Â±0.8 and a surface tension of 34Â±4 dynes/cm wherein a first product fraction floats and a second retained fraction sinks, separating the first product fraction from the second aqueous solution with the second retained fraction, introducing the second retained fraction into a third aqueous solution having a specific gravity of 1.16Â±0.01 and a pH in the range of 11.5Â±0.8 and a surface tension of 34Â±4 dynes/cm wherein a second reject fraction floats and a third retained fraction sinks, separating the second reject fraction from the third aqueous solution with the third retained fraction, introducing the third retained fraction into a fourth aqueous solution having a specific gravity of 1.203Â±0.002 and a pH in the range of 11.5Â±0.8 and a surface tension of 34Â±4 dynes/cm wherein a second product fraction floats and a third reject fraction sinks, and separating the second product fraction from the third reject fraction, wherein the first and second product fractions after drying are not less than about 96% ABS and PC.