Two=stage prodn. of halogen-free aromatic polycarbonate - by interfacial precondensation using halogen-free organic solvent then melt or solid phase condensation

摘要

2-Stage prodn. of halo-free aromatic polycarbonate (I) involves: (1) prodn. of a partly crystalline oligomeric precondensate (II); and (2) further condensn. to high mol. (I) in the melt or in the solid phase. Claims also cover (I) produced in this way. Pref. (II) has Mw = 1000-15000 and contains the end gps. allowing further condensn. End gps. are phenyl carbonate and/or alkyl carbonate gps. and opt. some (up to 45%) OH gps.; or approx. equimolar amts. of carbonate and aryl and/or alkyl carbonate gps. (II) contains 1 ppm to 1 wt.% condensn. catalyst (alkali hydroxide, alkaline earth hydroxide, (bi)carbonate or acetate, quinoline, PPh3 and/or organic Ti and/or Sn cpds.) for further condensn. USE/ADVANTAGE - (III) can be used instead of the usual halogenated solvents, which are ecologically harmful and very difficult to remove quantitatively. (I) are useful for making semi-finished prods., mouldings and films, e.g. for use in the electrical industry and vehicle construction.