Patent ID: 6635710
Filing Date: 2003-10-21
Classification: C08G

Abstract:
A method of making polycarbonate comprisingmelt polycondensing a carbonic acid diester and a bisphenol containing an alkali metal compound or alkaline earth metal compound and determining the transesterification activity of the bisphenol containing an alkali metal compound or an alkaline earth metal compound; comparing the transesterification activity of the bisphenol containing an alkali metal compound or an alkaline earth metal compound to a calibration curve relating the transesterification activity of pure bisphenol to the amount of bisphenol A disodium salt per mole of pure bisphenol in a melt polycondensation reaction; and adjusting the amount of alkali metal compound or alkali earth metal compound in the bisphenol containing an alkali metal compound or alkaline earth metal compound to attain transesterification activity equivalent to the transesterification activity of pure bisphenol containing about 1Ã—10âˆ’8 to 1Ã—10âˆ’6 moles bisphenol A disodium salt.