| 摘要 |
A method of preparing polycarbonate by the melt process comprising the steps of:a) melting a dihydric phenol and a diester of carbonic acid for a time and at a temperature sufficient to form a melt; and thereafter introducing a catalyst composition comprising a tetraorganophosphonium salt or a derivative thereof and1) an alkali and/or alkali earth metal compound or derivative thereof or2) a less active alkali and/or alkali earth metal derivative thereof into the melt; andb) oligomerizing the product from step a) to a number average molecular weight of from about 3000 to about 7500; andc) polymerizing the product from step b) to a number average molecular weight of from about 16,000 to about 35,000. |
