| 摘要 |
<p>This invention provides a method for preparing polycarbonates, which utilizes polycondensation catalysts of the formula Cs+An, wherein An represents anions such as CH3 SO3, NH2SO3, C2H2O4, BH4, B(C6H5CH3)4, and CH3C3C6H4SO¿3. We have found that this new class of catalysts provides excellent polymerization rates for the preparation of Bisphenol A polycarbonate from the melt polymerization of diphenyl carbonate and Bisphenol A. Moreover, the catalysts of the invention were found to be very selective in substantially reducing the level of branching side reaction, i.e., formation of Fried product, Normally associated with the melt polycarbonate process.</p> |
